JP3998311B2 - Liquid crystal display - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a liquid crystal display device having a backlight and suitable for displaying moving images.
[0002]
[Prior art]
Conventionally, a moving image is projected on a flat panel display device such as various monitors or personal computers by TV broadcasting or DVD. As this type of flat panel display device, a liquid crystal display device is small and light and widely used.
[0003]
However, when a moving image is transferred to a conventional liquid crystal display device, sufficient response cannot be obtained due to the characteristics of the liquid crystal, resulting in a blurred display with a tail. Such a means for solving the problems, is a new liquid crystal display device of the operation principle, for example, ferroelectric Gana research and development of liquid crystal or anti-ferroelectric liquid crystal. Also, in this type of new liquid crystal display element, the liquid crystal layer has to be made much thinner than conventional liquid crystal display elements, and glass lamination and gap control are problems in manufacturing.
[0004]
In addition, there are plasma displays, cathode ray tubes (CRTs), and the like outside the liquid crystal display elements, but these are large in shape and consume large power.
[0005]
[Problems to be solved by the invention]
As described above, the conventional liquid crystal display device cannot obtain sufficient responsiveness due to the characteristics of the liquid crystal, and the liquid crystal display element based on the new operation principle has a manufacturing problem. There is a problem that power consumption is large.
[0006]
The present invention has been made in view of the above problems. A liquid crystal display device that improves the responsiveness of a liquid crystal display without greatly changing the conventional structure and does not produce a blurred and blurred display even when a moving image is displayed. The purpose is to provide.
[0007]
[Means for Solving the Problems]
The present invention relates to a plurality of signal lines and a plurality of scanning lines arranged so as to cross each other, a signal line driver circuit for writing display data for each of these signal lines, and a scanning for each of the scanning lines. A liquid crystal display unit having a scanning line driver circuit, a light emitting region divided into N pieces in the vertical scanning direction, and a lighting control circuit for the light emitting region. The lighting control circuit includes N light emitting regions. A backlight for sequentially turning on and off the liquid crystal display unit in synchronization with a vertical synchronization signal of the liquid crystal display unit to illuminate the liquid crystal display unit , wherein the vertical scanning period T is T, and the vertical scanning period T is the N light emission From the time point when the scanning period corresponding to the self emission region is completed by dividing into the scanning period corresponding to the quantity region and making the scanning order of the N scanning periods correspond to the arrangement order of the N emission regions. , At least T / The self light-emitting region after elapse period in which light is emitted by any one period of T / N and 2T / N and T / 2N.
[0008]
The N light emitting areas are sequentially turned on and off in synchronization with the vertical synchronizing signal of the liquid crystal display unit, thereby improving the response of the liquid crystal display and changing the tail during moving image display without changing the structure from the conventional one. Is lost.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of a liquid crystal display device of the present invention will be described with reference to the drawings.
[0010]
As shown in FIG. 1, the liquid crystal display device uses a thin film transistor (Thin Film Transistor) of 640 × 480 × RGB, for example, and includes a signal input terminal 11 for inputting a video signal and a synchronization signal. Yes.
[0011]
The liquid crystal display device includes a liquid crystal display unit 12 and a backlight unit 13. The liquid crystal display unit 12 includes a plurality of 640 × RGB signal lines 15 and a plurality of 480 scans which are arranged orthogonally to each other. It has a line 16.
[0012]
A signal line driver circuit 18 for writing display data is provided for each signal line 15. These signal line driver circuits 18 have a shift register 19, a latch 20, and a D / A conversion circuit 21 provided for each signal line 15. The shift register 19 receives the timing pulse STH and the shift clock φ1. By inputting, the display data DATA is sequentially taken into each latch 20. When the display data DATA is stored in all the latches 20, the stored display data is received by the horizontal synchronization signal φ2 and output to the D / A conversion circuit 21, and is converted into analog data via the buffer 22. It is output to the corresponding signal line 15.
[0013]
For each scanning line 16, a scanning line driver circuit 23 for scanning is provided. These scanning line driver circuits 23 include a switch circuit 25 having a shift register 24 and switching elements 25a and 25b provided for each scanning line 16. Among these, the shift register 24 sequentially shifts the scanning timing pulse by receiving the scanning timing pulse (vertical synchronizing signal) STV and the scanning shift clock (horizontal synchronizing signal) φ2. In the switch circuit 25, when the scanning timing pulse STV is input, the voltage Vg2 is selected by the switching element 25b, and when the scanning timing pulse STV is not input, the voltage Vg1 is selected by the switching element 25a and output to the corresponding scanning line 16. Is done. That is, a scanning pulse is output to each scanning line 16 for each line.
[0014]
Further, pixel electrodes 27 are provided at the intersections between the signal lines 15 and the scanning lines 16 via thin film transistors 26 for driving pixels, and each pixel electrode 27 includes a liquid crystal layer 28. The auxiliary capacitor 30 is connected in parallel to the pixel electrode 27, the liquid crystal layer 28, and the common electrode 29. As the liquid crystal layer 28, a thin twisted nematic (TN) liquid crystal layer or a ferroelectric liquid crystal layer may be used.
[0015]
Then, the pixel composed of the pixel electrode 27, the liquid crystal layer 28, and the common electrode 29 writes the signal voltage output to the corresponding signal line 15 by outputting the scanning pulse to the corresponding scanning line 16. It is.
[0016]
The backlight unit 13 includes a backlight 33 that illuminates the display surface of the liquid crystal display unit 12. The backlight 33 is divided into N pieces, for example, four pieces in the vertical scanning direction of the liquid crystal display unit 12. Strip-shaped light emitting areas 33-1, 33-2, 33-3, 33-4, and discharge is performed for each of these light emitting areas 33-1, 33-2, 33-3, 33-4. Lamps 34-1, 34-2, 34-3, and 34-4 are provided.
[0017]
A lighting control circuit 35 is provided for each of the discharge lamps 34-1, 34-2, 34-3, and 34-4. The lighting control circuit 35 includes a frequency dividing counter 36 and a shift register 37, and a lighting driving inverter 38. The counter 36 divides the scan shift clock φ2, and the shift register 37 scans the scanning timing pulse STV. The discharge lamp 34-1 provided for each of the four light emitting regions 33-1, 33-2, 33-3, 33-4 is sequentially provided to each inverter 38 with a signal divided in frequency. , 34-2, 34-3, 34-4 are sequentially turned on and off one by one in a predetermined cycle. Therefore, the backlight 33 sequentially emits light for each of the N light emitting regions 33-1, 33-2, 33-3, 33-4.
[0018]
Next, lighting and extinguishing operations of the light emitting regions 33-1, 33-2, 33-3, and 33-4 will be described with reference to a timing chart shown in FIG.
[0019]
First, the vertical scanning period that does not include the vertical blanking period of the liquid crystal display unit 12 is defined as a vertical period T1, and this vertical period T1 is divided into four scanning periods T11, T12, T13, and T14. The scanning order of the four scanning periods T11, T12, T13, and T14 is made to correspond to the arrangement order of the four light emitting regions 33-1, 33-2, 33-3, and 33-4.
[0020]
Further, the liquid crystal display unit 12 has 480 scanning lines 16, and the scanning shift clock φ2 which is also a horizontal synchronizing signal by the scanning line driver circuit 23 applies a pulse voltage to these 480 scanning lines 16 sequentially. Scan.
[0021]
Here, the vertical blanking period, the vertical scanning period not including the period from 481 pulses to 525 pulses, and the period from 1 to 480 pulses required for scanning the 480 scanning lines 16 are defined as the vertical period T1. The vertical period T1 is divided by the number N of light emitting regions N = 4, four scanning periods T11, a period for scanning the first to 120th scanning lines, a scanning period T12, and the 121st to 240th periods. A scanning period is a scanning period, a scanning period T13, a scanning period from the 241st to 360th scanning lines, a scanning period T14, a scanning period from the 361st to 480th scanning lines, and the scanning order is four light emitting regions. Correspond in the order of 33-1, 33-2, 33-3, 33-4.
[0022]
That is, the first scanning period T11 in the scanning order corresponds to the first light emitting area 33-1 in the arrangement order. Similarly, the scanning period T12 is in the light emitting area 33-2, and the scanning period T13 is in the light emitting area 33-3. The scanning period T14 corresponds to the light emitting region 33-4.
[0023]
In such a relationship, the scanning line driver circuit 23 and the lighting control circuit 35 of the backlight 33 are synchronized with the scanning timing pulse STV having a period of 16 ms, and the light emitting regions 33-1, 33-2, 33-3, during 33-4, for example, the scanning of the scan period T11 that corresponds with the light emitting region 33-1 of the self is started, between the time of T1 / 4 period, to scan the 120 scanning lines 16, the following It is controlled by the lighting control circuit 35 so that the light emitting regions 33-2 arranged in stages emit light.
[0024]
Similarly, the next emission region 33-3 is associated with the start of scanning in the scanning period T12 corresponding to the emission region 33-2, and the next emission region is associated with the start of scanning in the scanning period T13 corresponding to the emission region 33-3. 33-4 is further controlled by the lighting control circuit 35 so that the light emitting area 33-1 of the next stage emits light for each T1 / 4 period with the start of scanning in the scanning period T14 corresponding to the light emitting area 33-4. Is done.
[0025]
These light emission periods T1 / 4 are set by dividing the scan shift clock φ2 every 120 pulses by the counter 36 constituting the lighting control circuit 35. Further, the four light emitting areas are sequentially provided at a predetermined cycle T1 / 4 by sequentially supplying the signals divided by the T1 / 4 period by the shift register 37 to the four inverters 38 in synchronization with the vertical synchronizing signal STV. It can be turned on and off, and so-called scanning light emission can be performed.
[0026]
In other words, any one of the discharge lamps 34-1, 34-2, 34-3, and 34-4 provided for each light emitting region is 4 after a three-fourth vertical period from the write timing of the liquid crystal display unit 12. The light is turned on only for one vertical period and is turned off for the remaining three quarter vertical periods.
[0027]
As described above, in the liquid crystal display device in which the backlight 33 is divided into N light emitting areas and sequentially emits light, a television (TV) image, a digital video disc (DVD) image, and the like are projected. The video could be clearly seen without any tailing. In particular, the flowing telop characters could be displayed without a trail regardless of the speed of movement. Further, the four discharge lamps 34-1, 34-2, 34-3, and 34-4 did not stand out as uneven display, and a uniform display could be obtained.
[0028]
Next, a second embodiment will be described with reference to a timing chart shown in FIG.
[0029]
In the second embodiment, the discharge lamps 34-1, 34-2, 34-3 in the corresponding light emitting regions 33-1, 33-2, 33-3, 33-4 are also used during the vertical blanking period. , 34-4 is lit.
[0030]
Here, the vertical scanning period of the liquid crystal display unit 12 and the vertical blanking period between the 1 to 480 pulses required for the operation of the 480 scanning lines 16 and the period between 481 pulses and 525 pulses are added as the vertical period. Let T2. The vertical period T2 is divided by the number of light emitting areas N = 4, and the four scanning periods T21, the period from the first to the 131st scanning line, the scanning period T22, the 132nd to the 262nd Scanning period T23, scanning period T23, scanning period from the 263rd to the 393rd scanning line, scanning period T24, scanning period from the 394th to the 480th scanning line and up to 524 pulses which are vertical blanking periods The scanning order corresponds to the order of arrangement of the four light emitting regions 33-1, 33-2, 33-3, 33-4.
[0031]
That is, the first scanning period T21 in the scanning order corresponds to the first light emitting area 33-1 in the arrangement order. Similarly, the scanning period T22 is in the light emitting area 33-2, and the scanning period T23 is in the light emitting area 33-3. The scanning period T24 corresponds to the light emitting region 33-4.
[0032]
In such a relationship, the scanning line driver circuit 23 and the lighting control circuit 35 of the backlight 33 are synchronized with the scanning timing pulse STV having a period of 16 ms, and the light emitting regions 33-1, 33-2, 33-3, For example, when scanning of the scanning period T21 corresponding to the self light emitting region 33-1 is started, the next stage 33-4 scans 131 scanning lines 16 during the period T2 / 4 from that point. Are controlled by the lighting control circuit 35 so that the light emitting regions 33-2 arranged in the light emitting region 33-2 emit light.
[0033]
Similarly, the next emission region 33-3 is associated with the start of scanning in the scanning period T22 corresponding to the emission region 33-2, and the next emission region is associated with the start of scanning in the scanning period T23 corresponding to the emission region 33-3. 33-4 is further controlled by the lighting control circuit 35 so that the next light emitting area 33-1 emits light during the period T2 / 4, respectively, with the start of scanning in the scanning period T24 corresponding to the light emitting area 33-4. The
[0034]
The light emission period T2 / 4 is set by dividing the scan shift clock φ2 every 131 pulses by the counter 36 constituting the lighting control circuit 35.
[0035]
When a TV image, a DVD image, or the like is projected on the liquid crystal display device having such a configuration, an image with a lot of movement can be clearly seen without causing a tail as in the first embodiment. . In particular, in the second embodiment, since the discharge lamp 34-1 in the light emitting region 33-1 corresponding to the vertical blanking period is turned on, the luminance can be increased.
[0036]
Next, a third embodiment will be described with reference to a timing chart shown in FIG.
[0037]
In the third embodiment, the discharge lamps 34-1, 34-2, 34-2, 34-2, 34-2, 34-2, 34-2, 34-2, 3-4, 34-2, 34-2, 34-2, 34-2, 34-2, Turn on 34-3 and 34-4.
[0038]
Also in this case, a period obtained by adding the vertical blanking period to the vertical scanning period of the liquid crystal display unit 12 is defined as a vertical period T2, and this vertical period T2 is divided by the number N of light emitting regions, and four scanning periods are obtained. T21, T22, T23, and T24 are set, and the scanning order is made to correspond to the order of arrangement of the four light emitting regions 33-1, 33-2, 33-3, and 33-4.
[0039]
That is, the first scanning period T21 in the scanning order corresponds to the first light emitting area 33-1 in the arrangement order. Similarly, the scanning period T22 is in the light emitting area 33-2, and the scanning period T23 is in the light emitting area 33-3. The scanning period T24 corresponds to the light emitting region 33-4.
[0040]
In such a relationship, each of the light emitting regions 33-1, 33-2, 33-3, 33-4 has, for example, a scanning period corresponding to the light emitting region 33-1 arranged in front of the self light emitting region 33-2. The self light emitting region 33-2 is caused to emit light for half of the T21 scan, for example, 131 pulses during the T2 / 4 period from when 65 pulses have elapsed.
[0041]
Similarly, during the period of 131 pulses from the time when scanning of the scanning period T22 corresponding to the light emitting area 33-2 has elapsed, the light emitting area 33-3 is half of the scanning of the scanning period T23 corresponding to the light emitting area 33-3. The light emitting region 33-4 emits light for a period of 131 pulses from the elapsed time. Further, the lighting control circuit 35 controls so that the light emitting region 33-1 emits light for a period of 132 pulses from the time when the scanning of the scanning period T24 corresponding to the light emitting region 33-4 has elapsed halfway.
[0042]
That is, in other words, for example, 131 pulses that are approximately a quarter vertical period before and after the scanning start timing to the scanning period T22 corresponding to the self light emitting area 33-2, but only the light emitting area 33-1 The corresponding discharge lamps 34-1, 34-2, 34-3, and 34-4 are turned on for a period of 132 pulses.
[0043]
Even with such a configuration, when a TV image, a DVD image, or the like was projected, an image with a lot of movement could be clearly seen without causing tailing.
[0044]
Next, a fourth embodiment will be described with reference to a timing chart shown in FIG.
[0045]
In the fourth embodiment, eight discharge lamps 34-1, 34-2, 34-3, 34-4 provided in the light emitting regions 33-1, 33-2, 33-3, 33-4 are provided. Lights up sequentially for one vertical period.
[0046]
Also in this case, a period obtained by adding a vertical blanking period to a vertical scanning period of the liquid crystal display unit 12 is defined as a vertical period T2, and this vertical period T2 is divided by the number N of light emitting regions, and four scanning periods T21 are obtained. , T22, T23, and T24, and the scanning order corresponds to the order of arrangement of the four light emitting regions 33-1, 33-2, 33-3, and 33-4.
[0047]
In such a relationship, each of the light emitting regions 33-1, 33-2, 33-3, 33-4 has, for example, half the scanning period T21 corresponding to its own light emitting region 33-1 and the first scanning line. The light emitting region 33 arranged in the next stage for one-eighth vertical period from the time when 65 pulses, which is the 65th scan, and 66 pulses from the 66th to 131st scanning lines, which is the T2 / 2N period. It is controlled by the lighting control circuit 35 so that -2 emits light.
[0048]
Similarly, when half of the scanning in the scanning period T22 corresponding to the light emitting area 33-2 has elapsed and half of the scanning in the scanning period T23 corresponding to the light emitting area 33-3 has elapsed in the next light emitting area 33-3. From the point in time when the scanning of the scanning period T24 corresponding to the light emitting area 33-4 further halves the next light emitting area 33-4, the next light emitting area 33-1 has a 1/8 vertical period. The lighting control circuit 35 controls to emit light for 66 pulses.
[0049]
Also in this case, when a TV image, a DVD image, or the like was projected, an image with a lot of movement could be clearly seen without causing tailing. In addition, since the lighting time per one of the discharge lamps 34-1, 34-2, 34-3, and 34-4 is short, the luminance decreases, but the outline of the moving image becomes clearer.
[0050]
Next, a fifth embodiment will be described with reference to a timing chart shown in FIG.
[0051]
In the fifth embodiment, the discharge lamps 34-1, 34-2, 34-3, 34-4 provided in the light emitting regions 33-1, 33-2, 33-3, 33-4 are The lamps are sequentially lit for almost a half vertical period.
[0052]
Also in this case, a period obtained by adding the vertical blanking period to the vertical scanning period of the liquid crystal display unit 12 is defined as a vertical period T2, and this vertical period T2 is divided by the number N of light emitting regions, and four scanning periods are obtained. T21, T22, T23, and T24 are set, and the scanning order is made to correspond to the order of arrangement of the four light emitting regions 33-1, 33-2, 33-3, and 33-4.
[0053]
In such a relationship, each of the light emitting regions 33-1, 33-2, 33-3, 33-4, for example, when scanning of the scanning period T21 corresponding to its own light emitting region 33-1 is started, Lighting control so that the light emitting region 33-2 arranged in the next stage emits light during a 2T2 / N period, which is a half vertical period from 1 to 2, for example, scanning from the first scanning line to the 262th scanning line, and 262 pulses Controlled by circuit 35.
[0054]
Similarly, the next emission region 33-3 is associated with the start of scanning in the scanning period T22 corresponding to the emission region 33-2, and the next emission region is associated with the start of scanning in the scanning period T23 corresponding to the emission region 33-3. 33-4 further corresponds to the light emission region 33-4, and the next light emission region 33-1, corresponding to the light emission region 33-4, corresponds to 262 pulses each of which is a half vertical period. Only one is controlled by the lighting control circuit 35 to emit light for a period of 263 pulses.
[0055]
Also in this case, when a TV image, a DVD image, or the like was projected, an image with a lot of movement could be clearly seen without causing tailing. In addition, since the lighting time per discharge lamp 34-1, 34-2, 34-3, 34-4 is set to a half vertical period, the outline of the video is slightly blurred, but the brightness is greatly improved. did.
[0056]
As a comparative example, the scanning light emission control function is removed from the lighting control circuit 35 of the backlight unit 13 shown in FIG. 1, and each discharge lamp 34-1, 34-2, 34-3, 34-4 is continuously turned on as before. As a result, the tailing was noticeable in the TV video, DVD video, etc., and the image became blurred.
[0057]
【The invention's effect】
According to the present invention, the responsiveness of the liquid crystal is enhanced by a simple and inexpensive means without changing the conventional liquid crystal structure, so that a good image can be obtained without causing tailing even when displaying a moving image. it can.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing an embodiment of a liquid crystal display device according to the present invention.
FIG. 2 is a timing chart showing lighting timing of the backlight unit in the first embodiment.
FIG. 3 is a timing chart showing lighting timing of a backlight unit in the second embodiment.
FIG. 4 is a timing chart showing lighting timing of a backlight unit in the third embodiment.
FIG. 5 is a timing chart showing lighting timing of the backlight unit in the fourth embodiment.
FIG. 6 is a timing chart showing lighting timing of the backlight unit in the fifth embodiment.
[Explanation of symbols]
12 LCD display
15 Signal line
16 scan lines
18 Signal line driver circuit
23 Scan line driver circuit
33 Backlight
33-1, 33-2, 33-3, 33-4 Light emission area
35 Lighting control circuit

Claims (2)

A plurality of signal lines and a plurality of scanning lines arranged crossing each other, a signal line driver circuit for writing display data to each of these signal lines, and a scanning line driver for scanning each of the scanning lines A liquid crystal display with a circuit;
There are N light emitting areas divided in the vertical scanning direction and lighting control circuits for the light emitting areas. The lighting control circuits sequentially turn the N light emitting areas in synchronization with the vertical synchronization signal of the liquid crystal display unit. A backlight for turning on and off and illuminating the liquid crystal display unit ,
The vertical scanning period is T, the vertical scanning period T is divided into scanning periods corresponding to the N light emission amount areas, and the scanning order of the N scanning periods is defined as the arrangement order of the N light emitting areas. Correspondingly, at least after the elapse of the T / N period from the end of scanning in the scanning period corresponding to the self light emitting area, the self light emitting area is set to any one of T / N, 2T / N, and T / 2N. A liquid crystal display device that emits light only . The liquid crystal display device according to claim 1 , wherein the vertical scanning period includes a vertical blanking period .

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