CN113410262B - Micro light-emitting diode display panel - Google Patents
Micro light-emitting diode display panel Download PDFInfo
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- CN113410262B CN113410262B CN202110805683.8A CN202110805683A CN113410262B CN 113410262 B CN113410262 B CN 113410262B CN 202110805683 A CN202110805683 A CN 202110805683A CN 113410262 B CN113410262 B CN 113410262B
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
- H01L27/15—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components having potential barriers, specially adapted for light emission
- H01L27/153—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components having potential barriers, specially adapted for light emission in a repetitive configuration, e.g. LED bars
- H01L27/156—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components having potential barriers, specially adapted for light emission in a repetitive configuration, e.g. LED bars two-dimensional arrays
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
- G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
- G09G3/22—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources
- G09G3/30—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels
- G09G3/32—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED]
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Abstract
The invention provides a miniature light-emitting diode display panel which comprises a plurality of display units and a control element. The display unit arrays are arranged and each display unit comprises a first sub-pixel. The first sub-pixel comprises a first micro light emitting diode and a second micro light emitting diode. The control element is used for controlling the light emission of the first micro light emitting diode and the second micro light emitting diode and determining the operation current of the first micro light emitting diode and the second micro light emitting diode. The operating current of the first micro light emitting diode increases with the operating temperature of the first sub-pixel under the same display image.
Description
Technical Field
The present invention relates to a display panel, and more particularly, to a micro light emitting diode display panel.
Background
With the evolution of photoelectric technology, solid-state light sources (such as light emitting diodes) have been widely used in various fields, such as road lighting, large outdoor billboards, traffic lights, etc. Recently, a micro light emitting diode display panel has also been developed, which uses micro light emitting diodes as sub-pixels in the display panel, so that each sub-pixel can be individually driven to emit light. The light beams emitted by the micro light emitting diodes capable of emitting light independently are combined into an image to form the display panel of the micro light emitting diode.
In the conventional high-resolution or large-sized micro led display panel, since the current supply time for each data line is short, the current density transferred by each data line needs to be increased, and thus it is easily damaged by heat. In addition, as the operating temperature increases, the micro light emitting diode tends to have problems of reduced light emitting efficiency or wavelength shift, resulting in inconsistent performance of the micro light emitting diode display panel in terms of brightness or color.
Disclosure of Invention
The invention provides a micro light emitting diode display panel which is beneficial to improving the problems of brightness reduction or color cast during high-temperature operation.
According to an embodiment of the present invention, a micro light emitting diode display panel includes a plurality of display units and control elements. The display unit arrays are arranged and each display unit comprises a first sub-pixel. The first sub-pixel comprises a first micro light emitting diode and a second micro light emitting diode. The control element is used for controlling the light emission of the first micro light emitting diode and the second micro light emitting diode and determining the operation current of the first micro light emitting diode and the second micro light emitting diode. The operating current of the first micro light emitting diode increases with the operating temperature of the first sub-pixel under the same display image.
In an embodiment according to the invention, the impedance of the first micro light emitting diode is smaller than the impedance of the second micro light emitting diode.
In an embodiment according to the invention, the operating current of the first micro light emitting diode is controlled by the control element.
In an embodiment according to the present invention, the operating current of the second micro light emitting diode decreases as the operating temperature of the first sub-pixel increases.
In an embodiment according to the present invention, the operating current of the first micro light emitting diode is greater than the operating current of the second micro light emitting diode when the first sub pixel is operated at a high temperature. When the first sub-pixel operates at a low temperature, the operating current of the second micro light emitting diode is larger than that of the first micro light emitting diode.
In an embodiment according to the present invention, the micro light emitting diode display panel further includes a substrate. The control element is connected with the first micro light emitting diode and the second micro light emitting diode in the display unit on the substrate.
In an embodiment according to the present invention, the micro light emitting diode display panel further includes a plurality of micro chips. The plurality of microchips are bonded on the substrate, and each microchip is positioned between the plurality of display units and is electrically connected with the plurality of display units.
In an embodiment according to the invention, the first micro light emitting diode and the second micro light emitting diode are different in at least one of: the area of the current diffusion layer, the thickness of the current diffusion layer, the junction area of the electrode and the epitaxial layer, and the material of at least one of the electrode and the epitaxial layer.
In an embodiment according to the invention, each display unit further comprises a second sub-pixel. The first sub-pixel and the second sub-pixel emit different colors, wherein the first micro light emitting diode of the first sub-pixel has a shorter wavelength than the second micro light emitting diode.
In an embodiment according to the invention, the first sub-pixel further comprises an impedance variable element. The impedance variable element is connected with the first micro light emitting diode and the second micro light emitting diode.
In an embodiment according to the present invention, in the first sub-pixel, the first micro light emitting diode and the second micro light emitting diode are connected in series, and the variable impedance element is connected in parallel with the first micro light emitting diode.
In an embodiment according to the invention, the impedance of the impedance variable element increases with increasing operating temperature of the first sub-pixel.
In an embodiment according to the present invention, the operating current of the first micro light emitting diode increases as the operating temperature of the first sub-pixel increases.
In an embodiment according to the invention, the first micro light emitting diode has a shorter wavelength than the second micro light emitting diode.
Based on the above, in the embodiment of the invention, the first sub-pixel has two micro light emitting diodes, and the operation current of at least one micro light emitting diode is controlled according to the operation temperature of the first sub-pixel, so as to compensate the problem of brightness reduction or color shift of the micro light emitting diode during high temperature operation, and further improve the consistency of the micro light emitting diode display panel in brightness or color expression.
In order to make the above features and advantages of the present invention more comprehensible, embodiments accompanied with figures are described in detail below.
Drawings
The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
FIG. 1 is a schematic top view of a micro light emitting diode display panel according to an embodiment of the present invention;
FIG. 2 is a first simple circuit diagram of the control element and first subpixel of FIG. 1;
FIGS. 3A and 3B are schematic cross-sectional views of the first and second micro light emitting diodes of FIG. 2, respectively;
FIG. 4 is a second simple circuit diagram of the control element and first subpixel of FIG. 1;
FIG. 5 is a schematic diagram of the wavelength and the light intensity of the first micro light emitting diode and the second micro light emitting diode in the first sub-pixel of FIG. 2;
fig. 6 to 8 are schematic partial top views of micro light emitting diode display panels according to other embodiments of the present invention.
Description of the reference numerals
100. 200, 300, 400: a micro light emitting diode display panel;
112: a first subpixel;
112A, 112B: a micro light emitting diode;
112C: an impedance variable element;
114: a second subpixel;
114A, 114B: a micro light emitting diode;
116: a third sub-pixel;
116A, 116B: a micro light emitting diode;
120: a control element;
130: a substrate;
140: a microchip;
1120: an epitaxial layer;
1120-1: an n-type semiconductor layer;
1120-2: a multiple quantum well;
1120-3: a p-type semiconductor layer;
1121: a current diffusion layer;
1122: an insulating layer;
1123: an electrode layer;
a1121: opening holes;
e1: a first electrode;
e2: a second electrode;
g: a groove;
I112A, 112B, 112C: a current;
o1, O2: an opening;
SW: a sidewall;
t1120-1, T1120-2, T1120-3, T1121, T1122, T1123: thickness;
u: a display unit;
w: a center of gravity wavelength;
W112A, W B: a wavelength of emitted light.
Detailed Description
Directional terms mentioned herein, such as: "upper", "lower", "front", "rear", "left", "right", etc., are merely directions with reference to the drawings. Thus, the directional terminology is used for purposes of illustration and is not intended to be limiting of the invention.
In the drawings, the various figures illustrate the general features of methods, structures and/or materials used in certain embodiments. However, these drawings should not be construed as defining or limiting the scope or nature of what is covered by these embodiments. For example, the relative dimensions, thicknesses, and locations of various layers, regions, or structures may be reduced or exaggerated for clarity.
The terms "first," "second," and the like in the description and in the claims, are used for naming discrete (discrete) elements or distinguishing between different embodiments or ranges and not for limiting the upper or lower limit on the number of elements or for limiting the order in which the elements are manufactured or arranged. Furthermore, the placement of an element/film on (or over) another element/film may encompass the placement of the element/film directly on (or over) the other element/film, with both elements/films being in direct contact; and the element/film layer is indirectly disposed on (or over) the other element/film layer, with one or more element/film layers between the two element/film layers.
Fig. 1 is a schematic top view of a micro led display panel according to an embodiment of the present invention. Fig. 2 is a first simple circuit diagram of the control element and the first sub-pixel of fig. 1. Fig. 3A and 3B are schematic cross-sectional views of the first micro led and the second micro led in fig. 2, respectively. Fig. 4 is a second simple circuit diagram of the control element and first sub-pixel of fig. 1. FIG. 5 is a schematic diagram of the wavelength and the light intensity of the first micro light emitting diode and the second micro light emitting diode in the first sub-pixel of FIG. 2. Fig. 6 to 8 are schematic partial top views of micro light emitting diode display panels according to other embodiments of the present invention.
In fig. 1 to 8, the same or similar elements will be given the same or similar reference numerals, and their redundant description will be omitted. Furthermore, the features of the different embodiments may be combined with each other without conflict and simple equivalent variations and modifications of the present specification or claims are intended to fall within the scope of the present invention.
Referring to fig. 1, the led display panel 100 may include a plurality of display units U, each of which is composed of a first sub-pixel 112, a second sub-pixel 114 and a third sub-pixel 116. The plurality of display units U are arranged in an array such that the micro light emitting diode display panel 100 performs display of an image (fig. 1 only schematically illustrates four display units U). A first subpixel 112. The first subpixel 112 may include a plurality of micro light emitting diodes. Fig. 1 schematically illustrates that the first subpixel 112 includes a micro light emitting diode 112A (also referred to as a first micro light emitting diode) and a micro light emitting diode 112B (also referred to as a second micro light emitting diode). However, the number of micro leds in the first sub-pixel 112 is not limited thereto. In some embodiments, the micro leds may have the same size to facilitate the bonding process and circuit design, but not limited thereto.
In some embodiments, as shown in fig. 2, the micro light emitting diode 112A and the micro light emitting diode 112B may be electrically independent from each other. For example, the micro led display panel 100 may further include a control element 120. The control element 120 is used for controlling the light emission of the micro light emitting diode 112A and the micro light emitting diode 112B and determining the operation current of the micro light emitting diode 112A and the micro light emitting diode 112B. Specifically, the control element 120 can control the light emitting state (light emitting, non-light emitting or light emitting intensity) of the micro light emitting diode, wherein the micro light emitting diode 112A and the micro light emitting diode 112B can be electrically connected to the control element 120 independently, such that the control element 120 can individually control the current I112A input to the micro light emitting diode 112A and the current I112B input to the micro light emitting diode 112B. The control element 120 may be a circuit chip or a driver of a micro light emitting diode, but is not limited thereto.
In some embodiments, as shown in fig. 1, the control element 120 may be disposed on one side of the micro light emitting diode display panel 100, and each sub-pixel is individually connected through a wire (not shown) to individually control the current input to the micro light emitting diode in each sub-pixel. However, in other embodiments, the micro led display panel 100 may include a plurality of control elements 120, and the plurality of control elements 120 may be disposed in respective sub-pixels.
In some embodiments, the micro light emitting diode 112A and the micro light emitting diode 112B may have the same or close emission wavelength. The light emission wavelength refers to the wavelength corresponding to the maximum light intensity in the spectrum of the micro light emitting diode. The plurality of micro light emitting diodes having the close light emitting wavelength means that the difference of the light emitting wavelengths of the plurality of micro light emitting diodes is not more than 10nm, for example, falls in the range of 1nm to 10nm, and preferably falls in the range of 3nm to 5nm, but not limited thereto.
In the first sub-pixel 112, the operation current of the at least one micro light emitting diode is changed as the operation temperature of the first sub-pixel 112 is changed. Specifically, the operating current of at least one micro light emitting diode (e.g., the micro light emitting diode 112A or the micro light emitting diode 112B) is controlled according to the operating temperature of the first sub-pixel 112 to compensate for the problem of brightness reduction or color shift of the micro light emitting diode during high temperature operation, so as to improve the consistency of brightness or color representation of the micro light emitting diode display panel 100.
For example, under the architecture of fig. 2, the micro light emitting diode 112A and the micro light emitting diode 112B may have different impedances. The micro light emitting diode having small resistance may have a large operation current at a high temperature operation, and the micro light emitting diode having large resistance may have a large operation current at a low temperature or at a normal temperature operation. The method of providing the micro light emitting diode 112A and the micro light emitting diode 112B with different impedances may include providing the micro light emitting diode 112A and the micro light emitting diode 112B with different at least one of: the area of the current diffusion layer, the thickness of the current diffusion layer, the junction area of the electrode and the epitaxial layer, and the material of at least one of the electrode and the epitaxial layer.
Taking the example that the impedance of the micro light emitting diode 112A is smaller than the impedance of the micro light emitting diode 112B, the micro light emitting diode 112A may have a smaller area of the current diffusion layer, a thickness of the current diffusion layer, or a junction area of the electrode and the epitaxial layer than the micro light emitting diode 112B, or a material of at least one of the electrode and the epitaxial layer may be adjusted so that the impedance of the micro light emitting diode 112A is smaller than the impedance of the micro light emitting diode 112B.
Fig. 3A and 3B schematically illustrate that the impedance of the micro light emitting diode 112A is made smaller than the impedance of the micro light emitting diode 112B by adjusting the area of the current diffusion layer. As shown in fig. 3A and 3B, each of the micro light emitting diode 112A and the micro light emitting diode 112B may include, for example, an epitaxial layer 1120, a current diffusion layer 1121, and an electrode layer 1123.
The epitaxial layer 1120 may include an n-type semiconductor layer (e.g., n-GaN or the like) 1120-1, a Multiple-Quantum Well (MQW) layer 1120-2, and a p-type semiconductor layer (e.g., p-GaN or the like) 1120-3, wherein the Multiple-Quantum Well 1120-2 is located between the n-type semiconductor layer 1120-1 and the p-type semiconductor layer 1120-3, and the p-type semiconductor layer 1120-3 is located between the Multiple-Quantum Well 1120-2 and the current diffusion layer 1121. In some embodiments, the thickness T1120-1 of the n-type semiconductor layer 1120-1 is 3000nm, the thickness T1120-2 of the multi-quantum well 1120-2 is 300nm, the thickness T1120-3 of the p-type semiconductor layer 1120-3 is 600nm, and the thickness of the epitaxial layer 1120 (i.e., the sum of the thickness T1120-1, the thickness T1120-2, and the thickness T1120-3) is 4 μm to 5 μm, but is not limited thereto.
A current spreading layer 1121 is disposed on the epitaxial layer 1120. In some embodiments, the current diffusion layer 1121 is a metal oxide layer (such as an ITO layer or the like), and the thickness T1121 of the current diffusion layer 1121 is 100nm, but not limited thereto.
Since the larger the area of the current diffusion layer 1121 is, the smaller the current density and the larger the impedance, the micro light emitting diode 112A can have a smaller impedance than the micro light emitting diode 112B by making the area of the current diffusion layer 1121 of the micro light emitting diode 112A smaller than the area of the current diffusion layer 1121 of the micro light emitting diode 112B. The area of the current spreading layer 1121 refers to the area of the orthographic projection of the current spreading layer 1121 on the n-type semiconductor layer 1120-1.
In some embodiments, the area ratio of the current spreading layer 1121 of the micro light emitting diode 112B to the current spreading layer 1121 of the micro light emitting diode 112A may fall within the range of 1.2 to 2. For example, the area of the current diffusion layer 1121 of the micro light emitting diode 112A is 10 μm 2 To 30 μm 2 (approximately less than 15 μm) 2 ) And the area of the current diffusion layer 1121 of the micro light emitting diode 112B is 30 μm 2 To 100 μm 2 But is not limited thereto.
An electrode layer 1123 is provided on the current diffusion layer 1121. In some embodiments, the electrode layer 1123 is a metal layer (such as a copper layer or the like), and the thickness T1123 of the electrode layer 1123 is 2nm, but not limited thereto.
In some embodiments, each of the micro light emitting diodes 112A and 112B may also include, for example, an insulating layer 1122. The insulating layer 1122 covers the current spreading layer 1121 and the epitaxial layer 1120 (e.g., the insulating layer 1122 covers the sidewall SW of the epitaxial layer 1120). The material of the insulating layer 1122 may include silicon oxide, silicon nitride, or the like, and the thickness T1122 of the insulating layer 1122 may be 700nm, but is not limited thereto.
The insulating layer 1122 may have an opening O1 exposing the current diffusion layer 1121 and an opening O2 exposing the epitaxial layer 1120, the electrode layer 1123 may have a first electrode E1 contacting the epitaxial layer 1120 through the opening O2 and a second electrode E2 contacting the current diffusion layer 1121 through the opening O1, and the first electrode E1 and the second electrode E2 are electrically insulated from each other. In the micro light emitting diode 112A, the current diffusion layer 1121 overlaps the second electrode E2 and is larger than the opening O1. In the micro light emitting diode 112B, the current diffusion layer 1121 covers the epitaxial layer 1120, and the opening a1121 of the current diffusion layer 1121 exposes the groove G of the epitaxial layer 1120.
It should be understood that fig. 3A and 3B are only schematically illustrating a structure of the micro light emitting diode, however, the structures, the number of layers, and/or the shapes or sizes of the layers, the openings, or the openings of the micro light emitting diode 112A and the micro light emitting diode 112B may be changed as required. The micro light emitting diode 112A and the micro light emitting diode 112B herein are intended to summarize any type of micro light emitting diode known.
Referring to fig. 2, in the first sub-pixel 112, the operation current of the micro light emitting diode 112A (micro light emitting diode with small impedance) may increase with the increase of the operation temperature of the first sub-pixel 112, and the operation current of the micro light emitting diode 112B (micro light emitting diode with large impedance) may decrease with the increase of the operation temperature of the first sub-pixel 112. In other words, the operation current of the micro light emitting diode 112A at the time of the high temperature operation is greater than the operation current of the micro light emitting diode 112A at the time of the normal temperature operation, and the operation current of the micro light emitting diode 112B at the time of the normal temperature operation is greater than the operation current of the micro light emitting diode 112B at the time of the high temperature operation.
In some embodiments, the operating current of the micro light emitting diode 112A (micro light emitting diode with small impedance) may be greater than the operating current of the micro light emitting diode 112B (micro light emitting diode with large impedance) when the first sub-pixel 112 is operated at high temperature. On the other hand, when the first sub-pixel 112 is operated at a low temperature, the operation current of the micro light emitting diode 112B may be greater than the operation current of the micro light emitting diode 112A. Specifically, when operating at low temperature or at normal temperature, the micro light emitting diode with high impedance (such as micro light emitting diode 112B) can have a large operating current to maintain the required brightness; in high temperature operation, since the micro light emitting diode 112A and the micro light emitting diode 112B both have high temperature light attenuation problem (i.e. the brightness of the micro light emitting diode 112A and the micro light emitting diode 112B are reduced), the micro light emitting diode with small impedance (e.g. the micro light emitting diode 112A) can have a larger operation current (e.g. the operation current of the micro light emitting diode with small impedance is increased), so as to increase the brightness through high current density, thereby maintaining uniform brightness at different operation temperatures. It should be appreciated that at any operating temperature, the micro light emitting diode 112A and the micro light emitting diode 112B may be on or off or both may be illuminated. When the operating temperature of any micro light emitting diode is too high, the micro light emitting diode can be turned off or the operating current of the micro light emitting diode can be reduced based on the safety or service life.
Herein, the high temperature in the high temperature operation refers to the temperature at which the micro light emitting diode generates significant brightness or lifetime decay, typically, but not limited to, 60 degrees celsius or more. The normal temperature in normal temperature operation refers to a typical working temperature of the micro light emitting diode, which is usually 25 degrees celsius, but not limited thereto. The operation current of the micro light emitting diode refers to the current flowing through the micro light emitting diode. The operating temperature of the first sub-pixel refers to the temperature of the region where the first sub-pixel is located.
In some embodiments, a temperature sensor (not shown) may be used to measure the temperature of a single sub-pixel or a single display unit in a micro-led display panel, or to measure the temperature of an area containing multiple sub-pixels or multiple display units. In other embodiments, the temperature sensor may be omitted by flowing the operating current of the micro light emitting diode in the subpixel back to the operating temperature of the push subpixel. In still other embodiments, the temperature sensor may be omitted by pushing back the operating temperature of the sub-pixels through the operating time of the micro-leds in the sub-pixels in an architecture in which Pulse-Width Modulation (PWM) is used to drive the micro-leds. In still other embodiments, the temperature sensor may be omitted by pushing back and forth the operating temperature of the sub-pixel through a voltage drop (voltage drop) across the micro-leds due to an increase in operating temperature. The operating temperature of the sub-pixel is obtained in the above manner, and the information is fed back to the control element, so that the control element can be helped to perform corresponding treatment (for example, the operating current or the operating time of the micro light emitting diode is changed based on the operating temperature of the sub-pixel).
In some embodiments, a photosensor (not shown) may be used to measure the brightness or the emission wavelength of a single sub-pixel or a single display unit in the led panel, or measure the brightness or the emission wavelength of a region including a plurality of sub-pixels or a plurality of display units, to be used as a basis for the control element to determine whether a corresponding treatment is required, or to confirm the validity of the adjustment after the control element adjusts the emission state of the led. For example, the brightness or the light emission wavelength measured by the light sensor can be compared with the preset brightness or the preset light emission wavelength to determine whether the light emission state of the micro light emitting diode needs to be adjusted. For example, when the brightness or the light emitting wavelength of the micro light emitting diode is changed, the changed information can be fed back to the control element so that the control element can perform corresponding treatment. After the control element makes the corresponding treatment, the light sensor may be used to measure the adjusted brightness or emission wavelength to determine whether the adjustment is effective or appropriate. If the adjustment is effective to adjust the brightness or emission wavelength back to an acceptable range, a second degree of adjustment may be avoided. If the adjustment does not bring the brightness or the emission wavelength back to the acceptable range, one or more additional adjustments may be made until the brightness or the emission wavelength is brought back to the acceptable range. If the brightness or the light emitting wavelength cannot be adjusted back to the acceptable range after multiple adjustments or the operation parameter to be adjusted exceeds the operable range (if the operation current to be adjusted exceeds the maximum current which can be born by the micro light emitting diode), the adjustment is stopped.
In some embodiments, as shown in fig. 1, the micro led display panel 100 may further include a second sub-pixel 114 and a third sub-pixel 116 in addition to the first sub-pixel 112. The second sub-pixel 114 has a micro light emitting diode (e.g., micro light emitting diode 114A), and the third sub-pixel 116 has a micro light emitting diode (e.g., micro light emitting diode 116A), but not limited thereto. The control element 120 is further electrically connected to the micro light emitting diode 114A in the second sub-pixel 114 and the micro light emitting diode 116A in the third sub-pixel 116 to control the light emitting states of the micro light emitting diode 114A and the micro light emitting diode 116A.
In some embodiments, the first sub-pixel 112, the second sub-pixel 114, and the third sub-pixel 116 are sub-pixels of different colors. Thus, the micro light emitting diode display panel 100 can perform full color display. For example, the first, second and third sub-pixels 112, 114 and 116 may be red, green and blue sub-pixels, respectively. That is, the micro light emitting diode 112A and the micro light emitting diode 112B are red micro light emitting diodes, the micro light emitting diode 114A is green micro light emitting diode, and the micro light emitting diode 116A is blue micro light emitting diode.
Since the red light high temperature light attenuation problem is more remarkable than that of the green light or the blue light, the micro light emitting diode display panel 100 of the present embodiment can have good display quality by providing two red micro light emitting diodes with different impedances in the red sub-pixel, and the input current of at least one of the two red micro light emitting diodes is changed based on the operation temperature, so as to maintain the consistency of the light intensity of the red light at different operation temperatures.
It should be understood that, although the above method or structure for improving the light attenuation problem is illustrated by the red sub-pixel, it is not limited thereto. In other embodiments, the method or structure for improving the light attenuation problem can be applied to sub-pixels of other colors. In addition, the sub-pixels of one or more colors in the micro led display panel 100 can be configured or arranged to improve the light attenuation.
In addition, fig. 1 shows that four display units U are electrically connected to one control element 120, i.e. the four display units U share one control element 120, but not limited thereto. In another embodiment, a display unit U may be connected to a control element 120.
In some embodiments, as shown in fig. 1, the micro light emitting diode display panel 100 may further include a substrate 130. The control element 120 and the micro light emitting diode in the display unit U may be commonly bonded on the substrate 130. For example, the substrate 130 may be a printed circuit board (Printed Circuit Board, PCB), a flexible printed circuit board (Flexible Printed Circuit Board, FPCB), a glass carrier with a circuit or a ceramic substrate with a circuit, but is not limited thereto.
The above embodiment is described with the micro light emitting diode 112A and the micro light emitting diode 112B having different impedances, and the control device 120 individually controls the operation currents of the micro light emitting diode 112A and the micro light emitting diode 112B, but the disclosure is not limited thereto. Under the structure of fig. 4, the micro light emitting diode 112A and the micro light emitting diode 112B may have the same impedance, and the micro light emitting diode 112A and the micro light emitting diode 112B are arranged in series. Specifically, the micro light emitting diode 112B is electrically connected between the control element 120 and the micro light emitting diode 112A, and the first sub-pixel 112 further includes an impedance variable element 112C. The variable impedance element 112C is connected in parallel with the micro light emitting diode 112A, wherein the impedance of the variable impedance element 112C increases as the operating temperature of the first subpixel 112 increases.
According to fig. 4, the current I112B flowing through the micro light emitting diode 112B is equal to the sum of the current I112A flowing through the micro light emitting diode 112A and the current I112C flowing through the impedance variable element 112C. Under constant current operation (i.e., the current I112B maintains a constant value), the current I112C flowing through the variable impedance element 112C decreases as the impedance of the variable impedance element 112C increases, such that the current I112A flowing through the micro light emitting diode 112A increases. In other words, the current I112A flowing through the micro led 112A increases with the increase of the operating temperature of the first sub-pixel 112. Under constant current operation, when the first sub-pixel 112 is at a high temperature, the brightness of the micro light emitting diode 112A and the micro light emitting diode 112B are both reduced, and at this time, the impedance of the impedance variable element 112C is increased, so that the current I112A flowing through the micro light emitting diode 112A can be increased, and the brightness of the micro light emitting diode 112A is increased, thereby compensating for the problem of the reduced brightness of the micro light emitting diode during the high temperature operation, and further improving the uniformity of the brightness of the micro light emitting diode display panel.
Although the embodiments of fig. 2 and 4 are illustrated with the micro light emitting diode 112A and the micro light emitting diode 112B having the same wavelength, the disclosure is not limited thereto. Under the architectures of fig. 2 and 4, the micro light emitting diode 112A may also have a shorter wavelength than the micro light emitting diode 112B. As shown in fig. 5, the spectrum of the micro light emitting diode 112B may partially overlap with the spectrum of the micro light emitting diode 112A, and the light emitting wavelength W112B of the micro light emitting diode 112B is greater than the light emitting wavelength W112A of the micro light emitting diode 112A. In some embodiments, the difference between the emission wavelength W112A of the micro light emitting diode 112A and the emission wavelength W112B of the micro light emitting diode 112B falls within a range of 1nm to 10nm, and preferably falls within a range of 3nm to 5 nm.
In the first sub-pixel 112, the magnitude of the center of gravity wavelength W can be controlled by changing the input current ratio of the micro light emitting diodes having different light emitting wavelengths, and the current density required for each micro light emitting diode can be reduced. Because the smaller the amount of change in current density, the smaller the shift in center of gravity wavelength, replacing a single micro light emitting diode with a plurality of micro light emitting diodes helps to reduce the amount of color shift for each micro light emitting diode. Thus, consistency of the gravity center wavelength and the light intensity can be maintained under different gray scales. In some embodiments, the control element 120 controls the current density to the micro light emitting diode 112A and the micro light emitting diode 112B to be less than 3A/cm respectively 2 Can obviously improve the color cast problem.
In addition, when the micro light emitting diode is operated at a high temperature, the emission wavelength is easily shifted to a long wavelength, and the larger the operation current of the micro light emitting diode is, the emission wavelength is shifted to a short wavelength. Therefore, when operating at high temperature, the micro light emitting diode with short wavelength (such as micro light emitting diode 112A) has a larger operating current (or a larger current density) to help compensate for the color shift caused by the wavelength shift.
Since the human eye is most sensitive to green light (appears brighter at the same brightness) among red light, green light, and blue light, the color shift problem (blue shift phenomenon) of the green micro light emitting diode is remarkable. In the embodiment, two green micro light emitting diodes with different light emitting wavelengths are arranged in the green sub-pixel, and the input current of at least one of the two green micro light emitting diodes is changed based on the operation temperature, so that the consistency of the center of gravity wavelength and the light intensity of green light is maintained at different operation temperatures, and the micro light emitting diode display panel can have good display quality.
It should be understood that, although the above method or structure for improving the light attenuation and color shift problem is illustrated by green sub-pixels, it is not limited thereto. In other embodiments, the method or structure for improving the light attenuation and color shift problem can be applied to sub-pixels of other colors. In addition, the sub-pixels of one or more colors in the micro light emitting diode display panel can adopt the method or structure for improving the light attenuation problem.
As shown in fig. 6, in the micro led display panel 200, the above method for improving light attenuation and/or color shift can be further applied to the second sub-pixel 114. Specifically, in the micro light emitting diode display panel 200, the second sub-pixel 114 (e.g., green sub-pixel) includes the micro light emitting diode 114A and the micro light emitting diode 114B. The micro light emitting diode 114A and the micro light emitting diode 114B may have the same size to facilitate the bonding process and the circuit design, but not limited thereto. The design of the micro light emitting diode 114A and the micro light emitting diode 114B may be described with reference to fig. 2, 4 or 5, and will not be repeated here.
As shown in fig. 7, in the micro led display panel 300, the above method for improving light attenuation and/or color shift can be further applied to the third sub-pixel 116. Specifically, in the micro light emitting diode display panel 300, the third sub-pixel 116 (e.g., blue sub-pixel) includes the micro light emitting diode 116A and the micro light emitting diode 116B. The micro light emitting diode 116A and the micro light emitting diode 116B may have the same size to facilitate the bonding process and the circuit design, but not limited thereto. The design of the micro light emitting diode 116A and the micro light emitting diode 116B may be described with reference to fig. 2, 4 or 5, and will not be repeated here.
Referring to fig. 8, the micro light emitting diode display panel 400 is similar to the micro light emitting diode display panel 100 of fig. 1, except that the micro light emitting diode display panel 400 further includes a plurality of micro chips (micro ICs) 140. The plurality of micro chips 140 are bonded on the substrate 130, and each micro chip 140 is located between (but not limited to) the plurality of (e.g. four, but not limited to) display units U and electrically connected to the plurality of display units U to control the plurality of micro light emitting diodes located in the plurality of display units U. In some embodiments, the thickness ratio of the microchip 140 to the micro light emitting diode may fall within the range of 0.8 to 1.2, but is not limited thereto. In some embodiments, the thickness of the microchip 140 is 5 μm to 10 μm, and the thickness of the micro light emitting diode is 5 μm to 10 μm, but not limited thereto. The small size (e.g., thickness) design described above aids in the transfer process or display quality.
In summary, in the embodiment of the invention, the first sub-pixel has two micro light emitting diodes, and the operation current of at least one micro light emitting diode is controlled according to the operation temperature of the first sub-pixel, so as to compensate for the problem of brightness reduction or color shift of the micro light emitting diode during high temperature operation, thereby improving the consistency of the brightness or color representation of the micro light emitting diode display panel.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the invention.
Claims (6)
1. A miniature light emitting diode display panel, comprising:
the display device comprises a plurality of display units, a plurality of display units and a display unit, wherein each display unit comprises a first sub-pixel, and the first sub-pixel comprises a first micro light emitting diode and a second micro light emitting diode; and
the control element is used for controlling the light emission of the first micro light emitting diode and the second micro light emitting diode and determining the operation current of the first micro light emitting diode and the second micro light emitting diode;
wherein the operating current of the first micro light emitting diode increases with an increase in the operating temperature of the first sub-pixel under the same display image,
wherein the first sub-pixel further comprises an impedance variable element, the first micro light emitting diode and the second micro light emitting diode are connected in series, and the impedance variable element is connected in parallel with the first micro light emitting diode,
wherein the impedance of the variable impedance element increases with increasing operating temperature of the first subpixel under the same display image, such that the current flowing through the first micro light emitting diode increases with increasing impedance of the variable impedance element.
2. The micro light emitting diode display panel of claim 1, further comprising:
and the control element is connected with the first micro light emitting diode and the second micro light emitting diode in the display unit on the substrate.
3. The micro light emitting diode display panel of claim 2, further comprising:
the micro chips are bonded on the substrate, are positioned among the display units and are electrically connected with the display units.
4. The micro light emitting diode display panel of claim 1, wherein each display unit further comprises a second sub-pixel, the first sub-pixel and the second sub-pixel emitting different colors, wherein the first micro light emitting diode of the first sub-pixel has a shorter wavelength than the second micro light emitting diode.
5. The led display panel of claim 1, wherein the operating current of the first led increases as the operating temperature of the first subpixel increases.
6. The micro light emitting diode display panel of claim 1, wherein the first micro light emitting diode has a shorter wavelength than the second micro light emitting diode.
Applications Claiming Priority (2)
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| US16/988,717 US11289012B2 (en) | 2017-09-07 | 2020-08-10 | Micro light emitting diode display panel and driving method thereof |
| US16/988,717 | 2020-08-10 |
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| CN113410262A CN113410262A (en) | 2021-09-17 |
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| JP4357413B2 (en) * | 2002-04-26 | 2009-11-04 | 東芝モバイルディスプレイ株式会社 | EL display device |
| KR20070077719A (en) * | 2006-01-24 | 2007-07-27 | 삼성전기주식회사 | Driver of color led |
| KR20090011702A (en) * | 2007-07-27 | 2009-02-02 | 삼성모바일디스플레이주식회사 | Organic light emitting display and driving method thereof |
| JP2011013551A (en) * | 2009-07-03 | 2011-01-20 | Toshiba Mobile Display Co Ltd | Organic el device |
| US8907991B2 (en) * | 2010-12-02 | 2014-12-09 | Ignis Innovation Inc. | System and methods for thermal compensation in AMOLED displays |
| US8890437B2 (en) * | 2012-12-12 | 2014-11-18 | Ledzworld Sdn Bhd | Method and system of automatically adjusting light intensity of a lighting fixture having multiple emitters |
| CN104969663B (en) * | 2013-02-05 | 2017-06-23 | 株式会社流明斯 | LED light device |
| US9831387B2 (en) * | 2014-06-14 | 2017-11-28 | Hiphoton Co., Ltd. | Light engine array |
| US10255834B2 (en) * | 2015-07-23 | 2019-04-09 | X-Celeprint Limited | Parallel redundant chiplet system for controlling display pixels |
| CN106782308B (en) * | 2017-02-10 | 2020-05-01 | 上海天马有机发光显示技术有限公司 | Organic light-emitting circuit structure with temperature compensation function |
| CN106910461B (en) * | 2017-05-11 | 2020-12-22 | 京东方科技集团股份有限公司 | Display panel, display device and display driving method |
| CN107946369B (en) * | 2017-11-24 | 2020-10-13 | 合肥鑫晟光电科技有限公司 | Thin film transistor, preparation method, detection device, array substrate and display device |
| TWI735865B (en) * | 2018-04-18 | 2021-08-11 | 聯詠科技股份有限公司 | Led driving system and led driving device |
| CN110416254B (en) * | 2018-04-27 | 2022-03-01 | 上海和辉光电股份有限公司 | Array substrate and display panel |
| TWM579865U (en) * | 2018-11-30 | 2019-06-21 | 宏碁股份有限公司 | Light-emitting diode driving circuit |
| CN109445159B (en) * | 2018-12-27 | 2021-07-09 | 厦门天马微电子有限公司 | Flexible display module, driving method thereof and flexible display device |
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| CN113410262A (en) | 2021-09-17 |
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