JP2002278514A - Electro-optical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correct luminance and hue by detecting secular changes in organic EL elements. SOLUTION: A prescribed voltage is applied to organic EL elements 54 by a current-measuring circuit 34 and the current flows are measured; and a temperature measurement circuit 35 estimates the temperature of the organic EL elements. Comparison is made for the voltage value applied to the elements 54, the flow of current values and the estimated temperature, the changes due to aging of the applied voltage-current characteristics beforehand, obtained for the elements having a same constitution of the elements 54, the changes due to aging in the current-luminance characteristics and the temperature at the time of the characteristics measurements for estimating the current- luminance characteristics of the elements. Then, the total sum of the amount of currents, being supplied to first electrooptical elements in the interval during which display data, are displayed is changed so as to obtain the luminance that is to be originally displayed, based on the estimated values of the current- luminance characteristics, the values of the current flowing in the elements and the display data.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electro-optical device using an electro-optical element such as a self-luminous element or a liquid crystal element, and more particularly to a display substrate on which a self-luminous element such as an organic EL element or FED is arranged for each pixel. And an electro-optical device suitably used as a display device.

[0002]

2. Description of the Related Art In recent years, organic EL (Electro Lu) has been developed.
menesence) or FED (Field Emi)
For example, a thin display device using a self-light-emitting element, such as a device such as a “ssion device”, has been actively developed.

It is known that in these devices using self-luminous elements, the light emission luminance of the elements is proportional to the current density flowing through the elements. In addition, it is known that element characteristics, particularly applied voltage-current characteristics vary, and it is considered that a drive circuit using a constant current source is preferable in these devices.

However, since it is difficult to actually manufacture a constant current source driving circuit, constant current driving is performed using a constant voltage source. In this case, a method has been proposed in which a means for detecting a current flowing through the element is provided and the current detected by the detecting means is controlled to be constant.

FIG. 1 shows an example of such a current detecting means.
This is an example of an organic EL display that performs brightness correction.
Organic compounds disclosed in Japanese Unexamined Patent Publication No. 2000-187467.
2 shows a configuration of a matrix type display device using EL elements.
FIG. In this display device, the organic EL panel 12
1 is a cathode (C) formed in a matrix.₀~ C_n)When
Anode (S₀~ S_m) And the organic EL arranged at the intersection
Element, and the cathode (C₀~ C_n)
A cathode drive circuit 122 for driving the anode (S ₀~ S_m)
Drive circuit (PG₁, P
G_Two, ..., PG _m) 123 and its anode drive circuit
Current detection circuit (IS₁,
IS_Two, ..., IS_m) 124 are connected. Soshi
And the current detection circuit IS_xThe current value detected by the control device 1
25 to the pixel lighting time according to the detected current.
Alternatively, the lighting current is adjusted. Note that the current
Detection circuit IS_xAre both ends of the resistor R1 as shown in FIG.
A / D conversion circuit 126 detects and outputs the voltage difference
Configuration.

It has also been pointed out that in an organic EL element, even when the element is driven under a constant voltage condition, the value of a flowing current changes with time. Therefore, there has been proposed a means for performing a current measurement and correcting the luminance with respect to such a temporal change.

FIG. 3 shows an example of an organic EL display which performs luminance correction using such a current detecting means, and is a view showing a configuration of a display device disclosed in Japanese Patent Application Laid-Open No. 10-254410. In this display device, all the organic EL elements of the display panel 109 are driven at the same constant voltage, the current value flowing through each organic EL element is measured, and the measured current value is stored in the current value memory 108. The arithmetic circuit 102 processes the stored data and display data externally input through the A / D conversion circuit 101 to adjust the total amount of current flowing through each pixel. Specifically, the current values of all the pixels are measured, and the current flowing through the organic EL element in which the deterioration of the light emission luminance characteristics is maximized is selected as a reference, and the light emission current of each organic EL element is divided by the reference current to obtain a value. The gradation data of the organic EL element is corrected, and the light emission time of the organic EL element is controlled based on the corrected gradation data. Note that the organic E forming each pixel of the display panel 109 is
As shown in FIG. 4, the current measuring stage of the L element
A current detector 204 is arranged between the second and the organic EL element 205, and the output of the current detector 204 is converted into digital data by the A / D converter 206 and stored in the current value memory 207.

Furthermore, it has been pointed out that in these self-luminous elements, the applied voltage-luminous current characteristics change with the temperature of the element. FIG. 5 shows an organic EL as an example of a self-luminous element.
4 shows an example of a temperature characteristic of an element. In FIG. 5, the horizontal axis indicates the applied voltage, and the vertical axis indicates the current flowing through the element. From this figure, it can be seen that the emission current changes even when the same voltage is applied due to a temperature change. Therefore, a method has been proposed in which a panel temperature is detected and a voltage applied to the element is adjusted to adjust a current flowing through the element.

FIG. 5 shows an example of an organic electroluminescent device which performs luminance correction using such a temperature detecting means, and shows a block diagram of the luminance correcting means disclosed in Japanese Patent Application Laid-Open No. 7-122361. It is. The temperature of the organic electroluminescent element 160 is determined by the temperature detector 16 disposed in the vicinity thereof.
2 is detected. Further, a voltage V _temp corresponding to the temperature detected from the temperature detector 162 is input to the ROM 164 through the A / D converter 163. Data stored in advance corresponding to the input temperature is output from the ROM 164 to the drive power supply unit 161 through the D / A converter 165 and the variable voltage amplifier 166. As shown in FIG. 7, the temperature detector 162 includes a thermistor 167 and a fixed resistor 168, and is configured to obtain an output voltage V _temp corresponding to the detected temperature according to the temperature characteristics of the thermistor 167.

[0010]

FIG. 8 shows an example of the change over time of the organic EL element as an example of the change over time of the self-luminous element. In FIG. 8, the horizontal axis indicates elapsed time, and the applied voltage indicated by the broken line (a) (vertical axis on the right) changes how the applied voltage necessary to make the current flowing through the element a certain value is changed. Indicates The standardized brightness (left vertical axis) shown by the solid line (b) shows how the brightness changes under the condition that the current is a certain value when the initial brightness is 1. From this figure, in the organic EL device, even if the applied voltage is adjusted so that the current flowing through the device is constant as shown in (b), the light emission luminance is changed due to the aging of the device characteristics as shown in (a). There is a problem of falling.

Accordingly, as disclosed in Japanese Patent Application Laid-Open No. 7-122361, means for detecting the element temperature and correcting the luminance includes:
Since there is no means for correcting the temporal change of the current-luminance characteristic in the self-luminous element as shown in FIG. 8, the above problem cannot be dealt with.

Further, as disclosed in Japanese Patent Application Laid-Open Nos. 2000-187467 and 10-254410, a method of measuring a current flowing through an element in a state where a specific voltage is applied, and correcting the luminance using the current value. Does not disclose means for correcting a change over time in the current-luminance characteristics of the self-luminous element as shown in FIG.

That is, Japanese Patent Application Laid-Open No. 2000-187467 discloses a means for correcting a temporal change so that a current value flowing through a self-luminous element becomes constant. However, according to this conventional technique, it is not possible to correct a temporal change in the current-luminance characteristics of the self-luminous element as shown in FIG.

Further, according to the technique disclosed in Japanese Patent Application Laid-Open No. H10-254410, the organic EL device in which the degradation of the light emission luminance characteristic is the largest is disclosed.
Means for correcting the drive current of another organic EL element based on the emission current of the element is disclosed. However, in this conventional technique, since the driving current of the reference organic EL element is not corrected, the relative aging characteristics between the organic EL elements can be compensated. It is not possible to compensate for the aging characteristics.

For example, since the panel temperature can be expected to be constant, the relative voltage of each organic EL element is measured by measuring the voltage required to supply a constant current to each organic EL element in the panel. It is possible to know the variation over time. However, even if the voltage required for flowing a constant current is increased by 10% from the initial value, the cause is as shown in FIG.
If it is not known whether the change is due to the temperature change shown in FIG. 8 or the change with time in FIG. 8, the absolute time-dependent change characteristics of each organic EL element cannot be compensated.

That is, in the above prior art, each organic EL
Although it is possible to compensate for variations in the aging characteristics between elements, it is not possible to correct absolute luminance characteristics of each organic EL element. In this case, a problem such as darkening of the screen according to the usage time occurs.

In particular, in an organic EL element for performing color display, since the luminescent material used for light emission is different for each of the RGB colors, the temperature characteristics and the aging characteristics are different for each of the RGB colors. Therefore, it is not possible to correct the luminance characteristics due to the temporal change between the RGB colors only by comparing the relative currents of the RGB colors. For this reason, the relative luminance characteristics between the respective colors of RGB change with the passage of time and appear as a change in the tint of the display image. When such a color change occurs, T
This is a serious problem because when a human face is reflected in a V-picture or the like, the complexion appears to change.

The present invention has been made in order to solve such problems of the prior art, and detects an aging change of a self-luminous element such as an organic EL element, and is capable of correcting luminance and color. It is an object to provide an optical device.

[0019]

According to the present invention, there is provided an electro-optical device comprising: means for inputting display data; means for displaying display data by means of first electro-optical elements arranged in a matrix; Means for measuring a current flowing by applying a predetermined voltage to the electro-optical element or the active element for controlling the first electro-optical element, and a temperature measuring means arranged around the first electro-optical element. A means for estimating the temperature of one electro-optical element, a voltage value applied to the first electro-optical element or an active element controlling the same, a current value flowing through the first electro-optical element, and the first electric element. An analogy value of the temperature of the optical element and the time-dependent change of the applied voltage-current characteristic, the time-dependent change of the current-luminance characteristic, and the temperature at the time of characteristic measurement for the electro-optical element having the same configuration as the first electro-optical element are determined in advance. Means for estimating the current-luminance characteristics of the first electro-optical element, comparing the obtained current-luminance characteristics, and the current flowing through the first electro-optical element. Means for changing a total amount of current supplied to the first electro-optical element during a period in which the display data is displayed, based on the value and the display data, so that a luminance to be originally displayed is obtained, Thereby, the above object is achieved.

According to the electro-optical device of the present invention, there are provided a means for inputting display data, a means for displaying display data by first electro-optical elements arranged in a matrix, and a means for displaying the first electro-optical element or the first electro-optical element. Means for measuring a current flowing by applying a voltage to an active element for controlling one electro-optical element, a second electro-optical element disposed around the first electro-optical element, and the second electro-optical element Means for applying a voltage to the element or the active element for controlling the second electro-optical element to measure a current flowing therethrough; a voltage value applied to the second electro-optical element or the active element for controlling the second electro-optical element; By comparing the current value flowing through the second electro-optical element with the voltage value applied to the first electro-optical element or the active element controlling the same and the current value flowing through the first electro-optical element Means for estimating the current-luminance characteristic of the first electro-optical element, and displaying the original current-luminance characteristic based on the estimated value of the obtained current-luminance characteristic, the current value flowing through the first electro-optical element, and the display data. Means for changing a total amount of current supplied to the first electro-optical element during a period in which the display data is displayed, so that power luminance is obtained;
Thereby, the above object is achieved.

The frequency of applying a voltage to the second electro-optical element or the active element for controlling the same should be less than the frequency of applying a voltage to the first electro-optical element or the active element for controlling the same. desirable.

In this case, it is considered that the second electro-optical element hardly changes with time. Therefore, by examining the applied voltage-current characteristics of the second electro-optical element, it is possible to know the element temperature that is not related to the change with time. By comparing the element temperature with the applied voltage-current characteristic of the first electro-optical element, it is possible to infer the state of the first electro-optical element over time. In addition, the temporal change of the first electro-optical element can be directly obtained from the applied voltage-current characteristic of the second electro-optical element without once estimating the temperature. The analogy of the change over time of the first electro-optical element can be performed in advance before displaying.

That is, there is provided storage means for storing a current value flowing through the first electro-optical element or data obtained by processing the current value, and based on the data read out from the storage means, The total amount of current supplied to one electro-optical element may be changed.

With respect to the electro-optical element having the same configuration as the first electro-optical element, the change with time of the applied voltage-current characteristic, the change with time of the current-luminance characteristic and the temperature at the time of measuring the characteristic are stored. May be provided.

The electro-optical element having the same configuration as that of the second electro-optical element may have a storage means for storing an applied voltage-current characteristic and a temperature at which the characteristic is measured beforehand.

A voltage value applied to the first electro-optical element or an active element for controlling the first electro-optical element, a current value flowing through the first electro-optical element, and an estimated value of a temperature of the first electro-optical element are externally provided. It may have a means for sending out, or a means for externally receiving and rewriting data stored in the storage means. In addition, a voltage value applied to the second electro-optical element or an active element that controls the second electro-optical element, a current value flowing through the second electro-optical element, and an analog value of a temperature of the second electro-optical element are sent to the outside. And means for rewriting the data stored in the storage means by receiving it from outside. Note that rewriting is effective when the changes over time are not sufficiently understood at the time of shipment.
Since transmission is effective when the change is recognized over time and applied to a product to be shipped from Shintani, a configuration not having both the transmission function and the reception function is also possible.

According to the electro-optical device of the present invention, there are provided means for inputting display data, means for displaying display data by first electro-optical elements arranged in a matrix, storage means, and data read from the storage means. Means for changing a total amount of current supplied to the first electro-optical element during a period in which the display data is displayed based on the data, the data being stored in the storage means. Means for externally receiving and rewriting, thereby achieving the above object. In this case, the data can be sent from the outside and rewritten to the storage means so that the luminance that should be displayed can be obtained, or the data can be rewritten to the storage means so that the luminance that should not be displayed can be obtained.

The operation of the present invention will be described below.

According to the present invention, a current flowing by applying a predetermined voltage to the first electro-optical element or an active element for controlling the first electro-optical element is measured to determine the current of the first electro-optical element.
By analogizing the luminance characteristics, the obtained current-analog value of the luminance characteristics,
On the basis of the current value flowing through the first electro-optical element and the display data, the total amount of the current supplied to the first electro-optical element during the period in which the display data is displayed is determined so that the luminance to be originally displayed is obtained. change.

In this configuration, since the means for measuring the current of the first electro-optical element itself may cause a drop (drop) in the power supply voltage, the current is supplied during the normal display of the first electro-optical element. It is preferable to prepare a first current supply line to be supplied and a second current supply line to supply a current at the time of current measurement, and to make the first current supply line open at the time of current measurement.

In the first means for estimating the current-luminance characteristic of the first electro-optical element, as described in a first embodiment described later, the first electro-optical element or an active element for controlling the first electro-optical element is provided with a predetermined value. The current flowing when the voltage is applied is measured, and the temperature of the first electro-optical element is inferred by temperature measuring means arranged around the first electro-optical element. A voltage value applied to the first electro-optical element or an active element that controls the first electro-optical element, a current value flowing through the first electro-optical element, and an analog value of the temperature of the first electro-optical element; For the electro-optical element having the same configuration as the element, the time-dependent change of the applied voltage-current characteristic, the time-dependent change of the current-luminance characteristic, and the temperature at the time of the characteristic measurement are compared with data that have been measured or predicted in advance. The current-luminance characteristics of the electro-optical element are analogized.

The means for estimating the temperature of the first electro-optical element can be obtained by, for example, arranging a temperature measuring means such as a thermocouple or a thermistor adjacent to the first electro-optical element, or by integrally disposing the element. Can be realized by arranging them in the vicinity of. Further, when these temperature measuring means are formed integrally with the electro-optical element, a plurality of temperature measuring means are formed, and the temperature is measured by using a normally operating one of the plurality of temperature measuring means. Even if the production yield of the measuring means is low, it is possible to prevent the influence on the production yield of the electro-optical device.

As described above, the temperature characteristic of the first electro-optical element is influenced by comparing the applied voltage-current characteristic of the first electro-optical element, which is measured or predicted in advance by knowing the element temperature. Instead, the absolute value of the change with time can be known. As a result, even in an electro-optical element that performs color display, variations in the absolute luminance of each of the RGB colors can be corrected, so that it is possible to reproduce human flesh colors neatly.

In the second means for estimating the current-luminance characteristics of the first electro-optical element, as will be described later in a second embodiment, a voltage is applied to the first electro-optical element or an active element for controlling the first electro-optical element. The applied current is measured, and at the same time, a current is measured by applying a voltage to the second electro-optical element disposed around the first electro-optical element or an active element that controls the second electro-optical element. Then, the voltage value applied to the second electro-optical element or the active element controlling the same and the current value flowing to the second electro-optical element, and the voltage applied to the first electro-optical element or the active element controlling the same. Values, current values flowing through the first electro-optical element, and time-dependent changes in applied voltage-current characteristics and time-dependent changes in current-luminance characteristics of an electro-optical element having the same configuration as the first electro-optical element were determined in advance. The current-luminance characteristics of the first electro-optical element are inferred by comparing the current-luminance characteristics.

The second electro-optical element or the active element for controlling the second electro-optical element is normally held without applying a voltage, and is considered to be held without deterioration of the applied voltage-current characteristics. Can be Therefore, it is possible to estimate the temperature of the second electro-optical element by using this characteristic, and thus it is possible to estimate the temperature of the first electro-optical element.

In particular, as shown in a third embodiment described below,
Made by the same process, a part of the electro-optical element having substantially the same configuration as the second electro-optical element, and the other as the first electro-optical element, no extra process is required, preferred .

When the first electro-optical element and the second electro-optical element are manufactured with the same configuration, the applied voltage-current characteristic of the second electro-optical element does not degrade the first electro-optical element. It is considered that the applied voltage-current characteristics in the state. In this case, even if the element temperature is not determined once, the current-
The luminance characteristics can be estimated.

In this case, it is better to obtain the change with time of the applied voltage-current characteristic and the change with time of the current-luminance characteristic of the first electro-optical element in advance, but there is some correlation between them. If so, the correlation can be obtained by calculation without having to measure it in advance.

The frequency of applying a voltage to the second electro-optical element or the active element controlling the same is lower than the frequency of applying a voltage to the first electro-optical element or the active element controlling the same. As long as the two electro-optical elements are held in a state of substantially less deterioration, a voltage may be applied to the second electro-optical element other than at the time of measuring the applied voltage-current characteristics. For example, a part of the display screen (one pixel at each of the four corners) can be used as the second electro-optical element, and the applied voltage may be at a level that hardly emits light (eg, 1 / 10,000 or less of the maximum luminance). . Whether the second electro-optical element is substantially in a state of little deterioration is considered to be equivalent to no deterioration within 1H, for example, in the time-dependent change characteristic of FIG.
It is conceivable to keep the voltage-current measurement time per pixel within the range. Assuming that the display period is 60 frames per second and the measurement is performed by the configuration of FIG. 16, if the voltage-current measurement time per pixel is within 10 μs,
24 × 60 × 60 × 10 μs = 51.84 seconds per day. To reach 1H degradation, 60 × 60/5
1.84 to 69 days are required. Further, since the change with time is not considered to change significantly even after several hours, 1
The voltage-current measurement for each pixel may be performed within one second for each pixel once a day or once an hour. Even if it is assumed that measurement is performed once an hour, it will take 60 × 60 × 60 times longer to reach 1H degradation.

As described above, by examining the applied voltage-current characteristics of the second electro-optical element which causes almost no deterioration, the element temperature of the second electro-optical element is reduced, and the element of the first electro-optical element is reduced. It is possible to infer the temperature.

Further, the second electro-optical element and the first electro-optical element have almost the same configuration, and a voltage is hardly applied to the second electro-optical element except at the time of measuring the voltage-current characteristics. By measuring the voltage-current characteristics of the first electro-optical element, it is possible to compare the voltage-current characteristics of the first electro-optical element with the voltage-current characteristics that do not change with time at the same temperature. It is possible to obtain an absolute change with time of the electro-optical element.

In this case, it is better to determine beforehand the change over time in the applied voltage-current characteristic and the change over time in the current-brightness characteristic of the first electro-optical element, but there is some correlation between the two. For example, even if it is not measured in advance, it can be obtained by calculation using the correlation.

By the way, in the present invention, when measuring the applied voltage-current characteristics of the first electro-optical element, display is performed by the first electro-optical element. In a passive matrix display device as disclosed in Japanese Patent Application Laid-Open No. 2000-187467,
Since the current can be measured while performing the display, there is no need for a means for storing the current measured value.
However, in an active matrix type display device as disclosed in Japanese Patent Application Laid-Open No. H10-254410, it is difficult to measure a current while performing display. Means is needed. Therefore, a storage unit for storing a current value flowing through the first electro-optical element or data obtained by processing the current value may be provided, and data read from the storage unit may be used. Further, with respect to the electro-optical element having the same configuration as the first electro-optical element, the time-dependent change of the applied voltage-current characteristic, the time-dependent change of the current-luminance characteristic, and the temperature at the time of characteristic measurement were measured or predicted in advance. A storage unit for storing data may be provided, and data read from the storage unit may be used. Or
For the electro-optical element having the same configuration as the second electro-optical element, a storage unit is provided for storing a temperature at which the temperature at the time of characteristic measurement is previously obtained from the applied voltage-current characteristic, and data read from the storage unit is stored. The above temperature may be used to infer the temperature.

In the present invention, the phrase “based on the current value flowing through the electro-optical element” means not only the current value obtained from the direct current measuring means but also data obtained by processing the current value. This means that the current value and the data obtained by processing the current value are temporarily stored in the storage means and then the read data is used.

As described above, by storing the voltage-current measurement result of each pixel and the analogy of the current-luminance characteristic, etc., which are measured in advance using the storage means, the voltage-current is measured for each frame.
There is no need to perform a current measurement. This makes it possible to suppress a decrease in the light emission period due to the voltage-current measurement and a change with time of the second electro-optical element.

Further, by storing the applied voltage-current characteristic of the second electro-optical element, which is measured or predicted in advance, in the storage means, the voltage-current measurement temperature is specified, and the factor due to the temperature change is specified. And a factor due to a change with time can be distinguished.

Further, the relationship between the applied voltage-current characteristics of the first electro-optical element, the temperature, and the change with time, which is measured or predicted in advance, is stored in the storage means, so that the temperature can be compared with the temperature. The absolute value of the change with time can be known without being influenced by the temperature characteristics of the first electro-optical element.

Even if the data of the change with time is not known at the time of shipment of the electro-optical device, the latest data may be sequentially received and updated later through the Internet, broadcasting / communication means, or the like. Further, if there is a function of transmitting measurement or analogy data to the outside of the apparatus, such as the temperature data, the applied voltage-current characteristic of the first electro-optical element or the second electro-optical element, the current-luminance characteristic is analogized. Even if the processing is not performed in the electro-optical device, the processing can be performed by another device. In this case, it is also possible to send out the measurement data through the Internet or communication means and receive necessary data such as current-brightness characteristics through the Internet or broadcasting / communication means and store it in each storage means.

The measurement of the change over time takes time, while the life cycle of a portable terminal or the like is shortened. Therefore,
There may be cases where it is not possible to measure the change over time when a display is sold. However, with the spread of digital broadcasting and the Internet, most displays are used for these purposes. Therefore, even if the above characteristics are not measured at the time of selling the display, it is also possible to give these data to the display later through digital broadcasting or the Internet.
Also, even if the correction data of the aging change is not created on the display side, the applied voltage-current characteristic of the first electro-optical element and the measured temperature are sent to the base station, and instead, the current correction characteristic of each pixel is received. By directly storing the data in the storage element, it is also possible to perform current correction. Further, by transmitting the time-dependent change data of each terminal device to the base station, it is possible for the manufacturer to grasp the state of the display.

The concept of receiving the stored data via the Internet or broadcasting / communication means can be used not only for the aging process of the electro-optical element but also for a wide range of video processing in general. In particular, when the latest video processing technology (data or software) is developed, the chance of using the new technology is reduced if the processing technology can only be applied to a new product. However, if it can be applied to existing products, new technologies can be widely used, and an environment in which the effects of technology development can be easily spread can be constructed.

[0051]

Embodiments of the present invention will be described below with reference to the drawings.

In the following embodiments 1 to 4, the organic EL device shown in FIG. 9 is used as the electro-optical device. The organic EL element 9 includes a cathode 2 made of Al or the like, an organic multilayer film 3 and an ITO (Indium T
An anode 3 made of a transparent material such as in oxide is formed in this order. Several structures can be considered as the organic multilayer film 4. Here, Alq (tris- (8-hydroxyq) is used as the electron transport layer 5 on the cathode 2.
uinoline / aluminum) etc. in the light emitting layer 6
As shown in FIG. 10A, DPVBi (1,4-bis
(2,2-diphenylvinyl) biphen
yl (blue light emitting layer) or Zn (oxz) _{2 in} FIG.
(Blue light emitting layer), Alq (red light emitting layer) in FIG. 10 (c) or Alq using DCM in FIG. 10 (d) as a dopant.
The (green light emitting layer) has a configuration in which the TPD of FIG. 10E is stacked as the hole transport layer 7 and the CuPc of FIG. 10F is stacked as the hole injection layer (or anode buffer layer) 8.

Further, in an active matrix type display device, a TFT manufactured using silicon having a large charge mobility is used as a TFT for driving such an organic EL element. Therefore, a manufacturing process for manufacturing the TFT used in the first to fourth embodiments will be described below. This manufacturing process is also described in, for example, Japanese Patent Application Laid-Open No. 10-301536.

First, as shown in FIGS. 11A to 11C, an amorphous silicon thin film 12 is deposited on a glass substrate 11, and the amorphous silicon thin film 12 is irradiated with an excimer laser. A polycrystalline silicon thin film 13 is formed.

Next, as shown in FIGS. 11D and 11E, the polycrystalline silicon thin film 13 is patterned into a desired shape to form an active region 14, on which a gate insulating film 15 is formed. To form And FIG.
As shown in (f), the gate electrode 1 of the thin film transistor
6 is formed of aluminum or the like.

Subsequently, as shown in FIG. 12G, the gate electrode 16 of one of the thin film transistors is replaced with a resist material 17.
Then, P + ion doping is performed. Thereby, the gate electrode 1 not covered with the resist material 17 is formed.
In the active region 14 on the sixth side, the region other than the region masked by the gate electrode 16 becomes the n + region 18. Then, as shown in FIG. 12H, after removing the resist material 17 formed in FIG. 12G, the gate electrode 16 of the other thin film transistor is covered with a resist material 19, and B + ion doping is performed. As a result, the active region 14 on the side of the gate electrode 16 not covered with the resist material 19 is formed.
Out of the region other than the region masked by the gate electrode 16 is p +
An area 20 is obtained. That is, FIG. 12 (g) and FIG.
In (h), an impurity (P (phosphorus) in the n-type region and B (phosphorus) in the p-type region)
(Boron)) is implanted.

Thereafter, as shown in FIG.
On the thin film transistor in which the region 18 and the p + region 20 are formed, an interlayer insulating film 21 made of silicon dioxide or silicon nitride is deposited. Then, as shown in FIGS. 12 (j) and 12 (k), after a contact hole 22 is formed on the interlayer insulating film 21, a metal wiring 23 such as aluminum is formed.

In the above steps, the maximum temperature of the process is 600 ° C. during the formation of the gate insulating film. Therefore, as the glass substrate 1, high heat resistant glass such as 1737 glass manufactured by Corning Incorporated in the United States may be used. it can.

In the above-mentioned electro-optical device, after the formation of the thin film transistor, the cathode 2 shown in FIG. 9 is formed via another interlayer insulating film, and then each layer shown in FIG. 9 is formed. Further, after forming each of these layers, sealing is performed using a glass lid or the like in order to shield from outside air.

(Embodiment 1) FIG. 13 is a system configuration diagram for explaining the configuration of an electro-optical device according to an embodiment of the present invention. In the present embodiment, an example will be described in which the first means is used as a means for estimating the current-luminance characteristics of the electro-optical element.

In this electro-optical device, the gate-side wiring Ci and the data wiring Sj are arranged on the substrate 31 so as to intersect (here, orthogonal), and the pixel Aij is arranged at the intersection. Further, a scanning side driving circuit 33 is arranged as a driving circuit for applying a voltage to the gate side line Ci, and a data side driving circuit 32 is arranged as a driving circuit for driving the data line Sj.

The data input to the signal processing control circuit 38 are stored in the storage means 40 as temperature and aging characteristics of the voltage-current characteristics of the electro-optical element and storage means 39.
Is processed using the measured voltage-current value of each pixel and the measured temperature stored in the temperature measuring circuit 35, output to the data driving circuit 32, and transmitted from the data driving circuit 32 to the data wiring Sj. Is supplied.

The pixel configuration shown in FIG. 13 is a configuration generally used as an organic EL pixel TFT circuit.
Each pixel Aij has an organic EL whose stacked structure is shown in FIG.
It comprises a device 53, a TFT 54 connected in series to the organic EL device 53, a TFT 55 and a capacitor 56 connected to the gate side of the TFT 54.

The TFTs 54 and 55 and the capacitor 56
Are formed by the TFT manufacturing process described with reference to FIGS. Further, the scanning-side driving circuit 33, the data-side driving circuit 32, and other elements and circuits on the substrate 31 are formed by the above-described TFT manufacturing process.
In some cases, a separately manufactured element or circuit is mounted on the substrate 31 later.

The first means comprises a current measuring circuit 34, a temperature measuring circuit 35 and a signal processing control circuit 3 shown in FIG.
8 is realized.

In this embodiment, as the temperature measuring circuit 35, a resistor 37 provided adjacent to a display pixel and the thermistor 3
A circuit for measuring the temperature of the thermistor (that is, the temperature of the panel) using the fact that the resistance ratio of 6 changes with the panel temperature is used. In this embodiment, four temperature measuring circuits 35 are arranged around the display unit. When these temperature measurement circuit 35, thermistor 36, and resistor 37 are formed by the TFT manufacturing process described with reference to FIGS. 11 and 12, even if a large number of these elements and circuits are formed, a large cost increase factor is caused. Not be. Therefore, in consideration of the yield of these temperature measuring circuits, thermistors, temperature measuring means such as resistors, etc., arrange more temperature measuring means around the display section than necessary and select one that operates normally. Can be used. This is preferable because the production yield can be prevented from lowering due to the production of the temperature measuring means.

In this embodiment, the current measuring circuit 34
As shown in FIG.
Utilizing the fact that a potential difference occurs at both ends of 1, a circuit for detecting the potential difference by the A / D conversion circuit 50 and transferring it to the signal processing control circuit 38 is used.

Since the current measuring circuit 34 has the resistor 51 shown in FIG. 14 for each power supply line, a plurality of pixels Aij (in FIG. 13, a plurality of pixels connected to one data line Sh in FIG. Pixel Aih is one resistor 5
1 is shared), a specific voltage Vs is stored only in the capacitor 56 of one pixel Akh, and the other pixels A
The OFF voltage is stored in the capacitor 56 of gh (g ≠ k).

As a result, the current flowing through the resistor 51 corresponding to the data line Sh is only the current flowing through the organic EL element 53 of the pixel Akh, and the applied voltage-current characteristic of the organic EL element 53 of the pixel Akh is Can be measured.

In order to know the change with time, it is sufficient to examine the applied voltage-current characteristic for only one voltage. Therefore, by setting this specific voltage Vs to a complete ON voltage, the applied voltage-current characteristics of the organic EL element 53 can be measured ignoring the ON resistance of the TFT 54. Further, by setting the specific voltage Vs to an intermediate potential between the ON voltage and the OFF voltage, the applied voltage-current characteristics of the organic EL element 53 including the ON resistance of the TFT 54 can be measured.

When current is supplied to each pixel through the resistor 51 in FIG. 14 when the above measurement is completed and each pixel in FIG. 13 is in the display state, a voltage drop (drop) due to the resistor 51 occurs. The power consumption due to this voltage drop also poses a problem. Therefore, as shown in FIG.
When each pixel is in the display state, the FET 52 is turned on to reduce the current flowing through the resistor 51. When the current of each pixel is measured, the FET 52 is turned off.
The current flowing through 52 is reduced. This is preferable because voltage drop and heat generation at the resistor 51 can be suppressed.

Since the temperature measuring means does not measure the temperature of the organic EL element itself, it is necessary to infer the temperature of the organic EL element based on the temperature measurement result. Normally, in a self-luminous element such as an organic EL element, a current flows during display, and the temperature of the element itself rises due to heat generated by the current. Therefore, even if the display history of each element is recorded, this temperature rise It is difficult to guess the minute.
However, there is a time zone in which any display device is always in a non-display state (for example, a standby state in a mobile phone). At that time, after waiting until it can be inferred that the temperature of the self-light-emitting element has become equal to the panel temperature, each pixel is sequentially displayed as described above, so that the organic EL element of each pixel at the above-described measurement temperature is displayed. The applied voltage-current characteristics can be measured. In addition, by measuring the current at a time after the display, the temperature variation of each element existing immediately after the display can be ignored, which is preferable.

In a consumer device, since the usage time is set to 10,000 hours or more, the time-dependent change characteristic does not change significantly by a difference of about 10 hours. In addition, the display device is continuously
It is rarely used for time. Therefore, if the change over time is obtained by measuring the characteristics of the organic EL element of each pixel immediately after the power of the display device is turned on or several hours after the power is turned off, it is possible to sufficiently respond. is there.
In particular, in a portable device, since the power supply itself is incorporated in the device, such a measure can be taken without preparing a special power supply, which is preferable. In addition, since a mobile phone has a standby time, it is preferable to periodically measure using the standby time.

On the other hand, with respect to the organic EL element having the same configuration as the above-mentioned organic EL element 53, the change with time of the applied voltage-current characteristic at several measurement temperatures was measured in a state where a constant voltage was applied. The current-luminance characteristics are also measured in advance. The voltage applied to the capacitor 56 constituting each pixel Aij, the value of the current flowing through the organic EL element 53 constituting the pixel Aij, and the value of the organic EL element 5
The degree of deterioration of the current-luminance characteristics of each pixel can be determined by comparing the analog value of the temperature of No. 3 with the result measured in advance.

For example, FIG. 8 shows that the current 1 at a measurement temperature of 25 ° C.
The graph shows changes over time in the applied voltage-current characteristics and changes over time in the current-luminance characteristics when constant current driving is performed at 0 mA / cm ² . FIG. 8 is a diagram showing that there is a luminance change even under a constant current condition. The actual measurement is performed by measuring the current under a constant voltage condition. Here, the constant voltage means that the power supply voltage is constant and the measurement voltage Vs applied to the capacitor 56 of each pixel Aij is also constant. For example, an organic EL element is subjected to a conduction test under a constant luminance condition or a constant current condition, and the measurement temperature is decreased by -10 every 10 hours.
The current value at a constant power supply voltage and a constant measurement voltage Vs can be obtained by changing the temperature in steps of 5 ° C. from about 60 ° C. to about 60 ° C.

Then, according to the degree of deterioration of the current-luminance characteristic, each organic EL element 53 is provided with a predetermined display data during the display data display period so that the luminance to be originally displayed can be obtained when the display data is input. It is possible to adjust the total amount of the supplied current.

The data necessary for the temperature measuring means (for example, data showing the relationship between the current value of the thermistor 36 and the temperature under a constant voltage application condition) and the applied voltage-current characteristics of the organic EL element at a previously measured temperature. The change with time and the change with time in the current-luminance characteristic are obtained by the storage circuit 40 shown in FIG.
Can be stored.

Using the stored data, the analog temperature of the organic EL element estimated by the temperature measuring circuit, and the applied voltage-current characteristic measured by the current measuring circuit,
A current correction characteristic (magnification) required to correct a change over time of the organic EL element of each pixel can be obtained. When the temperature measurement and the measurement of the applied voltage-current characteristics are performed during periods other than the display period, the current correction characteristics can be stored in the storage circuit 39 shown in FIG.

Note that the storage circuit 39 may store a measured current value instead of the current correction characteristic. In this case, the processing for obtaining the current correction characteristic from the measured temperature and the measured current value is also performed by the signal processing control circuit 38 in real time.

A circuit having a control function of such a current measurement circuit and a temperature measurement circuit and a function of adjusting the sum of currents is provided by a signal processing control circuit 38 (means for processing input display data) shown in FIG. is there. In the signal processing control circuit 38, the measured current value (or the current correction value obtained from the current value) and the input display data (signal)
, The signal data giving the sum of the necessary current amount is created. When adjusting the average luminance of the entire screen, it is preferable to change the power supply voltage rather than performing such signal data conversion.

In order to adjust the total value of the current supplied to the organic EL element 53 of each pixel as described above, two methods can be used in the circuit configuration for driving each pixel by TFT as shown in FIG. . The first method is to use the data wiring Sj
Through the capacitor (corresponding to analog gradation display in which the potential of the capacitor 56 is changed,
The voltage is supplied from the data line Sj).
This is a method of controlling the conduction state of the FT 54 and controlling the total amount of current flowing through the organic EL element 53. The second method is to store a voltage (ON voltage) for turning on the TFT 54 and a voltage (OFF voltage) for turning off the TFT 54 through the data wiring Sj in the capacitor 56 (display the gray scale by time division gray scale), and turn on the ON. By controlling the ratio of the time for applying the voltage to the time for applying the OFF voltage, the organic EL element 5
3 is a method of controlling the sum of the current amounts flowing through the circuit 3.

Either method can be used to implement the means for adjusting the sum of the current values. But,
Considering the variation of the threshold voltage and the variation of the ON resistance in the TFT 54 for driving the organic EL element, the latter O
The method of controlling the ratio between the N voltage application time and the OFF voltage application time is preferable because the gradation display characteristics are uniform.

As described above, the current-
It becomes possible to correct the deterioration with time of the luminance characteristic. Further, since the light-emitting materials and the like are different for each of the RGB colors, the applied voltage-current characteristics, the current-luminance characteristics, and the aging characteristics are also different. Therefore, by preparing data to be measured in advance for each of the RGB colors and performing the above-described correction for each of the RGB colors, it is possible to obtain a display device with a small change in tint irrespective of deterioration characteristics different for each of the RGB colors. Becomes

In the above embodiment, the display luminance is kept the same as that at the time of shipment. However, in an actual display device, the problem of tint is more important than the absolute luminance. Therefore, according to the means of the present embodiment, the deterioration characteristics of each of the RGB colors can be known. Therefore, when the absolute brightness is changed with the lapse of time, the brightness can be adjusted between the RGB colors so as to maintain the color. It is possible.

Further, in the configuration of FIG. 13, since the temperature measuring circuit 35 is provided, not only the correction of the aging characteristics but also the correction of the temperature characteristics can be performed. In particular, as shown in FIG. 5, in an organic EL element, a change in applied voltage-current characteristics depending on the element temperature is large. Therefore, as described above, even when the current measurement is performed by the current measurement circuit 34 when the panel is in the non-display state or the standby screen state, when the voltage-current characteristic is corrected in the normal display state, It is effective to use a real-time panel temperature measurement result by the measurement means.

As shown in FIG. 16, which will be described later, there is also a method of measuring the current during the display period, and a method of measuring the temperature of the entire panel and uniformly correcting the current for all the pixels. On the other hand, in the present embodiment, the temperature of the entire panel is measured, and current correction is uniformly performed on all pixels. Further, the temperature can be corrected using temperature measuring means provided at the four corners of the panel.

(Embodiment 2) FIG. 15 is a system configuration diagram for explaining the configuration of an electro-optical device according to Embodiment 2. In the present embodiment, an example will be described in which the above-described second means is used as a means for estimating the current luminance characteristics of the electro-optical element.

In this electro-optical device, Embodiment 1
13, a voltage applied current measuring circuit 41, an organic EL element 45, and a TF are used instead of the temperature measuring means including the temperature measuring circuit 35, the thermistor 36, and the resistor 37 shown in FIG.
T46 is arranged. This voltage applied current measuring circuit 4
1 applies a power supply voltage to the organic EL element 45,
6 is a circuit for measuring a current flowing through the organic EL element 45 by applying a voltage to the gate terminal 6. The temperature can be obtained by comparing the current values at the power supply voltage and the gate terminal voltage with the relationship between the power supply voltage, the gate terminal voltage and the current value measured in advance at each temperature.

As shown in FIG. 5, the applied voltage-current characteristics of the organic EL element easily change with temperature. Therefore, as shown in FIG. 15, the panel temperature can be inferred from the applied voltage-current characteristics of the organic EL element 45 disposed around the display section.

As shown in FIG. 8, since the applied voltage-current characteristics of the organic EL element change with time, no current flows through the organic EL element 45 arranged in the periphery of the pixel during normal display in FIG. It is preferable to keep it in a state. This can be realized by setting the TFT 46 connected to the organic EL element 45 to a non-conductive state other than at the time of current measurement or temperature measurement in FIG. 15, or by applying a reverse polarity voltage to the organic EL element 45. can do. As a result, it is possible to exclude the influence of the characteristic deterioration due to the voltage application history of the organic EL element 45 and to infer the panel temperature from the applied voltage-current characteristic of the organic EL element 45.

The applied voltage-current characteristics of the organic EL element 45 arranged around the display section at a previously measured measurement temperature, and the applied voltage-current characteristics of the organic EL element 53 arranged at the display section at a previously measured measurement temperature And the time-dependent change of the current-luminance characteristic can be stored in the storage circuit 44 shown in FIG.

The panel temperature is inferred from the stored data and the applied voltage-current characteristics of the organic EL element 45 disposed around the display section, and the analogous value of the temperature, the stored data and the current measuring circuit Using the applied voltage-current characteristics measured in step 34, a current correction characteristic (magnification) required to correct the aging of the organic EL element of each pixel can be obtained. When the temperature measurement and the measurement of the applied voltage-current characteristic are performed during periods other than the display period, the current correction characteristic can be stored in the storage circuit 43 shown in FIG.

Note that the storage circuit 43 may store a measured current value instead of the current correction characteristic. In this case, the operation of obtaining the current correction characteristic from the measured temperature and the measured current value is also performed by the signal processing control circuit 38 in real time.

A circuit having such a control function of the current measuring circuit and the temperature measuring means and a function of adjusting the sum of the currents is the signal processing control circuit 42 shown in FIG. The signal processing control circuit 42 creates signal data that gives the total of the required current amount from the measured current value (or the current correction value obtained from the current value) and the input display data (signal).

In FIG. 15, the applied voltage-current characteristics of the organic EL element 45 disposed around the display section correspond one-to-one with the panel temperature. Therefore, even if the panel temperature is not determined, the current-luminance characteristic of each pixel can be directly obtained by comparing the applied voltage-current characteristic of the organic EL element 45 with the applied voltage-current characteristic of the organic EL element 53 of the display unit. Can also be predicted. Data correction can be performed by obtaining a current correction characteristic (magnification) for each pixel. If the applied voltage and the value of the current flowing through the organic EL element are known without change over time, the temperature can be estimated. But,
Since the applied voltage uses a fixed value, the measured current and the temperature correspond one-to-one. In this case, even if the operation of obtaining the temperature is not performed, the aging characteristic at a temperature at which the measured current is given (without aging) from the measured current (from the aging characteristic measurement results at several temperatures). ) Can be asked. In such a case, there is no need to determine the panel temperature.

(Embodiment 3) FIG. 16 is a system configuration diagram for explaining the configuration of an electro-optical device according to Embodiment 3. In the present embodiment, another example using the above-described second means will be described as a means for estimating the current luminance characteristics of the electro-optical element.

In this electro-optical device, a special temperature measuring circuit is not provided, and pixels in the peripheral portion of the display section are normally kept in a non-display state. That is, a data voltage at which the luminance of the organic EL element is turned off is applied to make the organic EL element emit no light. In many display devices, even if one pixel at each of the four corners on the diagonal is in a non-display state, there is no problem in display.

As described above, by using the organic EL element of the pixel kept in the non-display state as an organic EL element for comparison (second electro-optical element) used in the second means, a special temperature can be obtained. This eliminates the need for a measurement circuit and an additional manufacturing process, and makes it possible to correct luminance and color by detecting a temporal change in a self-luminous element such as an organic EL element, which is an object of the present invention.

In FIG. 16, an organic EL for comparison was used.
Organic EL elements of each of RGB colors can be easily arranged as elements. In addition, since the current measuring means can be used in common with the organic EL element used for other display, the applied voltage-current characteristics can be compared without being affected by the variation of the current measuring means, which is preferable. .

The time-dependent change of the applied voltage-current characteristic and the time-dependent change of the current-luminance characteristic of the organic EL element at a previously measured measurement temperature can be stored in the storage circuit 49 shown in FIG.

The stored data and an organic EL for comparison
By inferring the panel temperature from the applied voltage-current characteristics of the element,
Using the analogy of the temperature, the stored data, and the applied voltage-current characteristic measured by the current measuring circuit 34, a current correction characteristic (magnification) required to correct the temporal change of the organic EL element of each pixel. Can be requested. When the temperature measurement and the measurement of the applied voltage-current characteristic are performed during periods other than the display period, the current correction characteristic can be stored in the storage circuit 48 shown in FIG.

Note that the storage circuit 48 may store a measured current value instead of the current correction characteristic. In this case, the operation of obtaining the current correction characteristic from the measured temperature and the measured current value is also performed by the signal processing control circuit 38 in real time.

A signal processing control circuit 47 shown in FIG. 16 has such a control function of the current measuring circuit and the temperature measuring means, and a function of adjusting the sum of the currents. The signal processing control circuit 47 creates signal data that gives the sum of the necessary current amount from the measured current value (or the current correction value obtained from the current value) and the input display data (signal).

Here, an example of a method of measuring the applied voltage-current characteristics of each organic EL element while performing display on the display device will be described. Although the configuration of the third embodiment will be described here, the present invention is also applicable to the configurations of the first and second embodiments.

First, in the display device of FIG. 16, the number of gate-side wirings Ci is m. At this time, one frame period TF is divided into a display period T1 and a current-side period T0.
Then, for example, as shown in FIG. 16, the first T0 period of one frame period TF is set as a current measurement period. During this period, the applied voltage-current characteristics of the color pixels A1j to Amj are measured.

For example, FIG. 16 shows that the number of gradations of the display device is one.
This is an example in which 6 gradations and m = 16 are shown, but the TFT 55 of each pixel is turned on in order from the pixel A1j to the pixel A16j using the gate side wiring Ci. And T
The TFT 54 of each pixel is turned on by the voltage supplied to the data line Sj while the FT 55 is turned on, and the applied voltage-current characteristic of each pixel is measured. In this current measurement period T0, display for one gradation is performed, so that each display gradation level is reduced by one gradation in the display period T1.

For example, when the numerical value below the column labeled Data in FIG. 16 is the gradation level to be displayed,
The gradation level in the display period is 1 as shown in the display period T1.
It becomes smaller by the gradation. In addition, in the example of FIG. 16, the current measurement is not performed on the pixel performing the 0 gradation display. But,
Actually, 64-gradation display and the like are performed, and external light reflection and the like also exist. Therefore, even if emission of the lowest level is performed and the applied voltage-current measurement is performed, no problem occurs.

As described above, while performing display, each organic EL
By measuring the applied voltage-current characteristics of the element, it is possible to quickly adjust the current even if there is a change in panel temperature or element temperature.

Even if the applied voltage-current characteristics change in each organic EL element due to a change in element temperature, it can be predicted that the current-luminance characteristics do not greatly change. Therefore, each organic EL element obtained in the previous non-display period can be predicted. The sum of the currents may be adjusted using the current-luminance characteristics of the EL element. This display period (1
The purpose of measuring the current during the frame period) is to adjust the luminance (current) due to the temperature change of each pixel, not to adjust the current-luminance characteristics. As can be seen from FIG. 8 described above, the change in the current-luminance characteristics hardly occurs when the energizing time is about 1 hour.

(Embodiment 4) In Embodiments 1 to 3 described above, the temporal change of the applied voltage-current characteristic and the temporal change of the current-luminance characteristic at the measurement temperature of the organic EL element arranged in the display section are stored in advance in the storage circuit. However, it is difficult to measure the time-dependent change characteristics of 10,000 hours before the product is released.

For this reason, normally, an acceleration test or the like is performed to predict the time-dependent characteristics in advance. Although this is important in knowing the service life of the display device, it is difficult to know the change over time of the applied voltage-current characteristic and the change over time of the current-luminance characteristic at a predetermined measurement temperature in this measurement. .
Therefore, in a mobile device having a communication function or a display device having a broadcast receiving function, it is possible to prevent such a temporal change characteristic from being predicted in advance.

That is, in parallel with the shipment of the display device, the applied voltage-current characteristics and the current-luminance characteristics of the organic EL element at a predetermined measurement temperature under normal use conditions are started.
Then, the latest measurement data is transmitted through broadcasting or communication as shown in FIG.
A system for transferring data to the storage circuit 40 or the like is prepared. This is preferable because it is possible to perform luminance correction and tint correction when necessary without having to measure the time-dependent change characteristic before shipping, so that quick product shipment can be performed.

Further, when a device having a communication function is used, it is not necessary for the electro-optical device itself to have the time-dependent change characteristic data. That is, the temperature and applied voltage-current characteristics of the organic EL element are measured, the data is transmitted to the outside using a communication function, and an appropriate current-luminance characteristic is obtained for each pixel on the device receiving the data. And send it back. This is the current correction characteristic (magnification) for each pixel.
Is stored in the storage circuit 39 of FIG. In this case, the storage circuit 40 and the like in FIG. 13 can be replaced with communication means.

By including such a communication system, an enormous measured temperature, applied voltage-current characteristics and current-
This is preferable because it is not necessary for the electro-optical device to have the data corresponding to the luminance characteristics, which saves memory. Also,
It is not necessary to calculate the correspondence between these data in each electro-optical device, which can contribute to low power consumption of each device, which is preferable.

The method of controlling the display quality of the display device through the above-mentioned broadcasting and communication is not only for solving the above-mentioned problem of deterioration of the aging characteristics, but also for controlling the display quality of the display device. It can also be used effectively as an effective means.

In the above embodiment, the case where the present invention is applied to the active matrix configuration has been described. However, the absolute current-brightness temporal change characteristic of the organic EL element forming each pixel in the present invention is described. Knowing that, the concept of adjusting the sum of the current values supplied to the pixel is also effective for a simple matrix configuration.

In this case, a configuration in which a current value is measured in a simple matrix configuration and the current value is constant is disclosed in FIG. 1 of Japanese Patent Application Laid-Open No. 2000-187467. In the present invention, instead of making the current value constant, as shown in the above-described embodiment, the current correction characteristic may be obtained and the current value of each pixel may be corrected. Description is omitted.

Further, the above-mentioned problems with time and temperature dependency are found not only in organic EL devices but also in other self-luminous devices such as FEDs. Here, description of an example of application to other self-luminous elements such as an FED is omitted, but as described in the above embodiment, it is not possible to obtain a current correction characteristic and correct the current value of each pixel. It is apparent that the present invention can be applied to other self-luminous elements.

[0119]

As described in detail above, according to the present invention,
As described in the first to third embodiments, it is possible to correct a temporal change in the luminance characteristic of the electro-optical element. Further, according to the first means for estimating the current-luminance characteristic, as described in the first embodiment, the element temperature of the electro-optical element is surely grasped, and the temporal change of the luminance characteristic of the electro-optical element is measured. Correction can be made reliably. Further, according to the second means for estimating the current-luminance characteristics, according to the second embodiment,
Also, as described in the third embodiment, it is possible to reliably grasp the element temperature of the electro-optical element, and to reliably correct the temporal change of the luminance characteristic of the electro-optical element.

In particular, in the second and third embodiments, an electro-optical element (organic EL element) used in the display unit can be used as the temperature measuring means. Since the electro-optical element as the temperature measuring means can be considered to be in a state where there is no change with time, it can be used for the current value of the electro-optical element as the temperature measuring means and the display unit without re-estimating the substrate temperature. By comparing the current values of the electro-optical elements, the amount of change with time of the electro-optical element can be grasped, and the luminance can be corrected.

Further, as described in the first to third embodiments, by performing the current measurement during the non-display period, it is possible to prevent the display quality from being deteriorated due to the current measurement. On the other hand, by performing the current measurement during the display period, the temperature can be corrected and the current can be quickly adjusted.

Further, as described in the first to third embodiments, by storing data in the storage means, it is possible to read out the time-dependent deterioration characteristics necessary for the luminance correction from the storage means.

Further, as described in the fourth embodiment,
By transmitting and receiving data through communication and broadcasting means, it is possible to perform measurements to estimate changes over time after product shipment, and to adjust necessary display quality after product shipment, which is necessary for commercialization. Development time can be shortened. In addition, the concept of rewriting data in the storage means through the Internet or broadcasting can be used not only for correction of temporal change but also for correction of image quality, and thus can be applied to non-light emitting elements such as liquid crystal.

[Brief description of the drawings]

FIG. 1 is a diagram showing a circuit configuration of a display device having a conventional current detecting means.

FIG. 2 is a diagram showing a configuration of a current detection circuit in the display device of FIG.

FIG. 3 is a diagram showing a circuit configuration of another display device having a conventional current detection unit.

FIG. 4 is a diagram illustrating a circuit configuration of a pixel in the display device of FIG. 3;

FIG. 5 is a diagram illustrating temperature dependence of voltage-current characteristics of an organic EL element.

FIG. 6 is a diagram showing a circuit configuration of a display device having a conventional temperature detecting means.

FIG. 7 is a diagram illustrating a circuit configuration of a temperature detecting unit in the display device of FIG. 6;

FIG. 8 is a diagram illustrating a voltage required to drive an organic EL element with a constant current and a temporal change in luminance obtained at that time.

FIG. 9 is a diagram showing a laminated structure of an organic EL element used in an embodiment of the present invention.

FIGS. 10A to 10F are diagrams showing examples of materials used for an organic EL device used in an embodiment of the present invention.

FIGS. 11A to 11F are views for explaining a process for manufacturing a TFT used in an embodiment of the present invention.

FIGS. 12G to 12K are views for explaining a process for manufacturing a TFT used in the embodiment of the present invention.

FIG. 13 is a diagram illustrating a system configuration of the electro-optical device according to the first embodiment.

FIG. 14 is a diagram showing a circuit configuration of a current measuring circuit used in the embodiment of the present invention.

FIG. 15 is a diagram illustrating a system configuration of an electro-optical device according to a second embodiment.

FIG. 16 is a diagram illustrating a system configuration of an electro-optical device according to a third embodiment.

FIG. 17 is a diagram for explaining a current measuring method used in the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Glass substrate 2 Cathode 3 Anode 4 Organic multilayer film 5 Electron transport layer 6 Light emitting layer 7 Hole transport layer 8 Hole injection layer (or anode buffer layer) 9 Organic EL element 11 Glass substrate 12 Amorphous silicon thin film 13 Polycrystal Silicon thin film 14 Active region 15 Gate insulating film 16 Gate electrode 17 Resist material 18 n + region 19 Resist material 20 p + region 21 Interlayer insulating film 22 Contact hole 23 Metal wiring 31 Display substrate 32 Data side drive circuit 33 Scan side drive circuit 34 Current measurement Circuit 35 Temperature measurement circuit 36 Thermistor 37 Resistance 38 Signal processing control circuit 39, 40 Storage circuit 41 Voltage application current measurement circuit 42 Signal processing control circuit 43, 44 Storage circuit 45 Organic EL element 46 TFT 47 Signal processing control circuit 48, 49 storage Circuit 50 A / D conversion circuit 51 resistor 52 FET 53 Organic EL element 54 TFT 55 TFT 56 Capacitor 101 A / D conversion circuit 102 Arithmetic circuit 103 Frame memory 104 Controller 105 Scan circuit 106 Write circuit 107 Power supply circuit 108 Current value memory 109 Display panel 121 Organic EL panel 122 Cathode drive circuit 123 Anode drive circuit 124 Current detection circuit 125 Controller 126 A / D conversion circuit 160 Organic electroluminescent element 161 Drive power supply 162 Temperature detector 163 A / D converter 164 ROM 165 D / A converter 166 Variable voltage amplifier 167 Thermistor 168 Fixed resistance 201 FET 202 FET 203 Capacitor 204 Current detector 205 Organic EL element 206 A / D conversion circuit 207 Current value memory

Claims (9)

[Claims] Means for inputting display data; means for displaying display data by means of first electro-optical elements arranged in a matrix; and means for displaying the first electro-optical element or the first electro-optical element. Means for measuring a current flowing by applying a predetermined voltage to the active element to be controlled; and means for estimating the temperature of the first electro-optical element by temperature measuring means arranged around the first electro-optical element. A voltage value applied to the first electro-optical element or an active element that controls the first electro-optical element, a current value flowing through the first electro-optical element, and an analogous value of the temperature of the first electro-optical element,
For the electro-optical element having the same configuration as that of the first electro-optical element, a change with time of the applied voltage-current characteristic, a change with time of the current-luminance characteristic, and the temperature at the time of characteristic measurement are compared with those obtained in advance. Means for estimating the current-luminance characteristic of the first electro-optical element, and an analogous value of the obtained current-luminance characteristic, a current value flowing through the first electro-optical element, and display data based on the display data. Means for changing the total amount of current supplied to the first electro-optical element during a period in which the display data is displayed so as to obtain a desired luminance. Means for inputting display data; means for displaying display data by means of first electro-optical elements arranged in a matrix; and means for displaying the first electro-optical element or the first electro-optical element. Means for measuring a current flowing by applying a voltage to the active element to be controlled; a second electro-optical element arranged around the first electro-optical element; and the second electro-optical element or the second A means for measuring a current flowing by applying a voltage to the active element for controlling the electro-optical element; and a voltage value applied to the second electro-optical element or the active element for controlling the second electro-optical element and the second electro-optical element. The value of the flowing current is compared with the value of the voltage applied to the first electro-optical element or the active element that controls the first electro-optical element and the value of the current flowing in the first electro-optical element, and Means for estimating the current-luminance characteristics of the current and the obtained current-luminance characteristics, the current value flowing through the first electro-optical element, and the display data. Means for changing the total amount of current supplied to the first electro-optical element during a period in which the display data is displayed. 3. The frequency of applying a voltage to the second electro-optical element or the active element controlling the same is lower than the frequency of applying a voltage to the first electro-optical element or the active element controlling the same. The electro-optical device according to claim 2, wherein: 4. A storage device for storing a current value flowing through the first electro-optical element or data obtained by processing the current value, wherein the data is read based on data read from the storage device. The electro-optical device according to any one of claims 1 to 3, wherein a total amount of current supplied to one electro-optical element is changed. 5. An electro-optical element having the same configuration as that of the first electro-optical element, wherein an applied voltage-current characteristic changes with time.
The electro-optical device according to claim 1, further comprising a storage unit configured to store a change in current-luminance characteristics with time and a temperature at the time of characteristic measurement. 6. An electro-optical element having the same configuration as that of the second electro-optical element, further comprising storage means for storing an applied voltage-current characteristic and a temperature obtained beforehand for measuring the characteristic. An electro-optical device according to claim 5. 7. A means for sending out a voltage value applied to the electro-optical element or an active element for controlling the electro-optical element, a current value flowing through the electro-optical element, and an analog value of a temperature of the electro-optical element to the outside. An electro-optical device according to any one of claims 4 to 6. 8. The electro-optical device according to claim 4, further comprising a unit for externally receiving and rewriting data stored in the storage unit. 9. A means for inputting display data, a means for displaying display data by means of first electro-optical elements arranged in a matrix, a storage means, and the data read out from the storage means. Means for changing the total amount of current supplied to the first electro-optical element during a period in which display data is displayed, further comprising: receiving data stored in the storage means from outside; An electro-optical device having rewriting means.