JP2004333583A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device capable of improving display luminance and easily adjusting screen luminance highly precisely. <P>SOLUTION: An LED (light emitting diode) array 7 of a backlight 22 has a plurality of LED chips of which the single chip is composed of red, green and blue LED elements. A plurality of the LED chips are separated into a plurality of groups in a nearly uniformly distributed and disposed manner. The luminance is adjusted by controlling turning on and turning off of the LED elements as a single unit for the respective groups and controlling driving currents of the LED elements for the respective groups. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device using a plurality of display light sources.
[0002]
[Prior art]
With the progress of the so-called information society in recent years, electronic devices represented by personal computers, PDAs (Personal Digital Assistants), and the like have been widely used. With the spread of such electronic devices, there is a demand for portable devices that can be used both in offices and outdoors, and there is a demand for reductions in their size and weight. A liquid crystal display device is widely used as one of means for achieving such an object. The liquid crystal display device is an indispensable technology not only for reducing the size and weight but also for reducing the power consumption of a portable electronic device driven by a battery.
[0003]
Liquid crystal display devices are roughly classified into a reflection type and a transmission type. The reflective type is a configuration in which light rays incident from the front of the liquid crystal panel are reflected on the back side of the liquid crystal panel, and the image is visually recognized by the reflected light. This is a configuration in which an image is visually recognized by transmitted light. Since the reflection type is inferior in visibility because the amount of reflected light is not constant depending on environmental conditions, a transmission type color liquid crystal using a color filter is generally used as a display device such as a personal computer for performing multi-color or full-color display. A display device is used.
[0004]
As a color liquid crystal display device, a TN (Twisted Nematic) type using a switching element such as a TFT (Thin Film Transistor) is widely used at present. Although the TFT-driven TN type liquid crystal display device has a higher display quality than the STN (Super Twisted Nematic) type, the light transmittance of the liquid crystal panel is only about 4% at present, so that a high screen luminance can be obtained. Requires a high-luminance backlight. For this reason, power consumption by the backlight increases. In addition, since color display is performed using a color filter, one pixel must be composed of three sub-pixels, and it is difficult to achieve high definition, and the display color purity is not sufficient.
[0005]
In order to solve such a problem, the present inventors have developed a field sequential type liquid crystal display device (for example, see Non-Patent Documents 1, 2, and 3). Compared with the color filter type liquid crystal display device, the field sequential type liquid crystal display device does not require sub-pixels, so that a display with higher accuracy can be easily realized. Since the light emission color of the light source can be used for display as it is, the display color purity is excellent. Furthermore, since the light use efficiency is high, there is an advantage that power consumption is small. However, in order to realize a field sequential type liquid crystal display device, high-speed response (2 ms or less) of the liquid crystal is essential.
[0006]
Therefore, the present inventors have proposed a field-sequential type liquid crystal display device or a color filter type liquid crystal display device having the above-mentioned excellent advantages to achieve a high-speed response by 100 to 1000 compared to the conventional liquid crystal display device. Research and development of driving a liquid crystal such as a ferroelectric liquid crystal having spontaneous polarization that can expect twice as fast response by using a switching element such as a TFT (for example, see Patent Document 1). In a ferroelectric liquid crystal, the major axis direction of the liquid crystal molecules changes by a tilt angle when a voltage is applied. A liquid crystal panel sandwiching a ferroelectric liquid crystal is sandwiched between two polarizing plates whose polarization axes are orthogonal to each other, and the intensity of transmitted light is changed by utilizing birefringence caused by a change in the long axis direction of liquid crystal molecules.
[0007]
[Patent Document 1]
JP-A-11-119189
[Non-patent document 1]
Toshiaki Yoshihara, et al. (T. Yoshihara, et. Al.): ICLC 98 (IL CC 98), pp. 1-074, 1998
[Non-patent document 2]
Toshiaki Yoshihara, et al. (T. Yoshihara, et. Al.): AM-LCD '99 Digest of Technical Papers (AM-LCD'99 Digest of Technical Papers,) p. 185, published in 1999
[Non-Patent Document 3]
Toshiaki Yoshiwara, et al. (T. Yoshihara, et. Al.): SID'00 Digest of Technical Papers (SID'00 Digest of Technical Papers,) p. 1176, 2000
[0008]
[Problems to be solved by the invention]
Field-sequential liquid crystal display devices have the advantages of high light use efficiency and reduction of power consumption, but especially for application to portable devices, the power consumption is further increased. Reduction is desired. In addition, when the use outdoors in the daytime is considered, a display with high luminance is required from the viewpoint of visibility, but when the use in the nighttime is considered, the luminance is required to be reduced. As described above, it is necessary to adjust the screen brightness. From the viewpoint of power consumption, the adjustment of the screen brightness is important. Such adjustment of the screen luminance is required not only in the field sequential type liquid crystal display device but also in the color filter type liquid crystal display device.
[0009]
However, in a conventional liquid crystal display device using a plurality of display light sources, since the plurality of display light sources are controlled collectively, high-luminance display and luminance adjustment cannot be performed sufficiently. There is a problem.
[0010]
The present invention has been made in view of such circumstances, and it is an object of the present invention to provide a liquid crystal display device capable of improving display luminance and easily adjusting screen luminance with high accuracy.
[0011]
[Means for Solving the Problems]
The liquid crystal display device according to the first invention is characterized in that a plurality of display light sources are grouped into a plurality of groups, and a unit is provided for controlling collective turning on / off of the display light sources for each group.
[0012]
In the first invention, a plurality of display light sources in the liquid crystal display device are divided into a plurality of blocks, and collective lighting / collective turning off of the display light sources in each block is controlled in units of each block.
[0013]
For example, when the light sources are connected in parallel and divided into two blocks, the drive current in the blocks can be reduced to about half as compared with the conventional example in which all the display light sources are made into one block and the lighting / extinguishing is collectively controlled. The drive current in each block decreases as the number of blocks increases. Therefore, by increasing the number of divided blocks, the required current to the power supply corresponding to each block can be reduced. On the other hand, since the emission intensity of the display light source depends on the drive current, the emission intensity can be increased by increasing the drive current. Therefore, by controlling the lighting / extinguishing for each block as a unit as in the present invention, the driving current for each block can be suppressed low, and the current capacity of the power supply per block is the same. In this case, higher display brightness can be realized as compared with the conventional example.
[0014]
Further, since a plurality of display light sources are divided into a plurality of blocks, and each block can be turned on / off and the brightness can be adjusted in units of each block, all display light sources are driven as one block. Compared to the example, finer brightness adjustment is possible. For example, when n types of drive currents are used in one block, only n types of brightness can be obtained in the conventional example. However, in the present invention, when divided into two blocks, the brightness is adjusted to (2n-1) types of brightness. it can. In general, when one block has n types of drive currents and the number of divisions is m blocks, {n + (m-1) (n-1)} types of luminance can be expressed. As described above, since the brightness of the display light source is adjusted for each block, highly accurate adjustment of the screen brightness can be easily performed.
[0015]
The liquid crystal display device according to the second invention is characterized in that, in the first invention, the display light sources in each group are arranged substantially uniformly.
[0016]
According to the second aspect, since the plurality of display light sources in each of the plurality of divided blocks are arranged substantially uniformly, it is not necessary to turn on all the installed display light sources. By turning on all the display light sources in at least one block, it can function as a light source for uniform surface light emission, and display with uniform high luminance can be realized.
[0017]
In the liquid crystal display device according to a third aspect, in the first or second aspect, the display light source is a light source that emits red, green, and blue light, or red, green, blue, and white light. Features.
[0018]
In the third invention, red, green, and blue light, or red, green, blue, and white light are emitted from the display light source. Therefore, full color display is possible.
[0019]
A liquid crystal display device according to a fourth aspect is the liquid crystal display device according to any one of the first to third aspects, wherein the display light source is a light emitting diode.
[0020]
In the fourth invention, a light emitting diode is used as a display light source. Therefore, emission of each color can be easily performed, emission intensity can be easily adjusted, and adjustment of screen luminance can be easily performed.
[0021]
A liquid crystal display device according to a fifth aspect is characterized in that in any one of the first to fourth aspects, a liquid crystal material having spontaneous polarization is used.
[0022]
In the fifth invention, a liquid crystal material having spontaneous polarization such as a ferroelectric liquid crystal material or an antiferroelectric liquid crystal material is used. Therefore, a display excellent in high-speed response can be realized, and a liquid crystal display device excellent in moving image display characteristics can be provided.
[0023]
A liquid crystal display device according to a sixth aspect is the liquid crystal display device according to any one of the first to fifth aspects, wherein color display is performed by a field sequential system.
[0024]
According to the sixth aspect of the present invention, since color display is performed by the field sequential method, high definition, high speed response, high color purity display, and display realizing high transmittance can be performed.
[0025]
BEST MODE FOR CARRYING OUT THE INVENTION
The present invention will be specifically described with reference to the drawings showing the embodiments. Note that the present invention is not limited to the following embodiments.
[0026]
FIG. 1 is a block diagram showing a circuit configuration of a liquid crystal display device according to the present invention, FIG. 2 is a schematic sectional view of a liquid crystal panel and a backlight, and FIG. 3 is a schematic diagram showing an example of the overall configuration of the liquid crystal display device. 5 is a plan view of the backlight.
[0027]
In FIG. 1, reference numerals 21 and 22 denote a liquid crystal panel and a backlight whose sectional structure is shown in FIG. Reference numeral 31 denotes a control signal generation circuit which receives a synchronization signal SYN from a personal computer and generates various control signals CS required for display. The pixel data PD is output from the image memory unit 30 to the data driver 32. Based on the pixel data PD and the control signal CS for changing the polarity of the applied voltage, a voltage is applied to the liquid crystal panel 21 via the data driver 32 during a plurality of data writing scans.
[0028]
The control signal generation circuit 31 outputs a control signal CS to the reference voltage generation circuit 34, the data driver 32, the scan driver 33, and the backlight control circuit 35, respectively. The reference voltage generation circuit 34 generates reference voltages VR1 and VR2, and outputs the generated reference voltage VR1 to the data driver 32 and the reference voltage VR2 to the scan driver 33, respectively. The data driver 32 outputs a signal to the signal line 42 of the pixel electrode 40 based on the pixel data PD from the image memory unit 30 and the control signal CS from the control signal generation circuit 31. In synchronization with the output of this signal, the scan driver 33 sequentially scans the scanning lines 43 of the pixel electrodes 40 line by line. Further, the backlight control circuit 35 applies a driving voltage to the backlight 22 to cause the backlight 22 to emit red light, green light, and blue light, respectively.
[0029]
As shown in FIGS. 2 and 3, the liquid crystal panel 21 includes a polarizing film 1, a glass substrate 2, a common electrode 3, a glass substrate 4, and a polarizing film 5 from the upper layer (front surface) side to the lower layer (back surface) side. Are arranged in this order, and pixel electrodes 40, 40... Arranged in a matrix are formed on the surface of the glass substrate 4 on the side of the common electrode 3. An alignment film 12 is disposed on the upper surfaces of the pixel electrodes 40, 40,..., And an alignment film 11 is disposed on the lower surface of the common electrode 3, and a liquid crystal material is filled between the alignment films 11, 12 to form a liquid crystal layer 13. Is done. Reference numeral 14 denotes a spacer for maintaining the thickness of the liquid crystal layer 13.
[0030]
The liquid crystal panel 21 having such a configuration is specifically manufactured as follows. After washing the TFT substrate having the pixel electrodes 40, 40 ... (640 × 480 pixels) and the glass substrate 2 having the common electrode 3, polyimide is applied and baked at 200 ° C. for 1 hour to obtain about 200 ° C. A polyimide film is formed as the alignment films 11 and 12. Further, these alignment films 11 and 12 are rubbed with a rayon cloth, and these two substrates are overlapped so that the rubbing directions are parallel, and a silica spacer having an average particle size of 1.8 μm is provided between the two substrates. At 14, an empty panel is produced by superimposing while maintaining the gap. A liquid crystal layer 13 is formed by filling a ferroelectric liquid crystal having a half V-shaped electro-optical response characteristic as shown in FIG. 4 when the TFT 41 is driven between the alignment films 11 and 12 of the empty panel. The magnitude of spontaneous polarization of the enclosed ferroelectric liquid crystal is 8 nC / cm. ² The maximum value of the angle between the average molecular axis of the liquid crystal molecules when no voltage is applied and the average molecular axis of the liquid crystal molecules when voltage is applied is 30 ° on one side. The produced panel is sandwiched between two polarizing films 1 and 5 in a crossed Nicols state to form a liquid crystal panel 21 so that a dark state is obtained when no voltage is applied.
[0031]
As shown in FIG. 3, a driving unit 50 including a data driver 32, a scan driver 33, and the like is connected between the common electrode 3 and the pixel electrodes 40, 40. The data driver 32 is connected to the TFT 41 via a signal line 42, and the scan driver 33 is connected to the TFT 41 via a scanning line 43. The TFT 41 is turned on / off by the scan driver 33. Each pixel electrode 40 is connected to a TFT 41. Therefore, the transmitted light intensity of each pixel is controlled by a signal from the data driver 32 provided through the signal line 42 and the TFT 41.
[0032]
The backlight 22 includes the LED array 7 and the light guide and light diffusing plate 6 as shown in FIGS. The backlight 22 is located on the lower layer (back side) of the liquid crystal panel 21, and includes the LED array 7 in a state facing the end surface of the light guide and light diffusing plate 6 forming the light emitting area. The LED array 7 has 16 LEDs as a plurality of display light sources, each of which has an LED element that emits three primary colors, that is, red, green, and blue, on a surface facing the light guide and light diffusion plate 6. It has a chip 17.
[0033]
These 16 LED chips 17 are divided into two blocks (first block and second block) each having eight lamps. Specifically, for example, the odd-numbered eight LED chips 17 arranged in the odd-numbered position as viewed from the upper end side in FIG. Block. As a result, the LED chips 17 belonging to the first block and the LED chips 17 belonging to the second block are alternately arranged, and the eight LED chips 17 are uniformly distributed in each block. Then, collective lighting / extinguishing of the eight LED chips 17 is controlled for each block, and the luminance of the eight LED chips 17 is adjusted.
[0034]
FIG. 6 is a diagram showing a drive circuit of the LED array 7 which is a light source of the backlight 22. In the circuit shown in FIG. 6, the anode is common to each group. Eight LED elements that belong to the first group and emit red light are provided in parallel between the first anode and the first cathode for red, and a first LED and a first cathode for green are provided between the first anode and the first cathode for green. Eight LED elements that emit green light belonging to one group are provided in parallel, and eight LED elements that emit blue light belong to the first group between the first anode and the first cathode for blue. They are provided in parallel. Also, between the second anode and the second cathodes for red, green, and blue, eight LED elements each belonging to the second group and emitting red light, green light, and blue light are provided in parallel. ing.
[0035]
Then, in each of the red, green, and blue sub-frames described later, the red, green, and blue LED elements are respectively turned on. The light guide and light diffusion plate 6 functions as a light emitting area by guiding light from each LED element of the LED array 7 to the entire surface thereof and diffusing the light to the upper surface. The liquid crystal panel 21 and a backlight 22 capable of time-division light emission of red, green, and blue are overlaid. The lighting timing and emission color of the backlight 22 are controlled in synchronization with a data writing scan based on display data for the liquid crystal panel 21.
[0036]
Next, the operation of the liquid crystal display device according to the present invention will be described. When pixel data PD for display is input from the personal computer to the image memory unit 30, and the image memory unit 30 temporarily stores the pixel data PD and receives the control signal CS output from the control signal generation circuit 31. And outputs the pixel data PD. The control signal CS generated by the control signal generation circuit 31 is provided to the data driver 32, the scan driver 33, the reference voltage generation circuit 34, and the backlight control circuit 35. When receiving the control signal CS, the reference voltage generation circuit 34 generates reference voltages VR1 and VR2, and outputs the generated reference voltage VR1 to the data driver 32 and the reference voltage VR2 to the scan driver 33, respectively.
[0037]
When receiving the control signal CS, the data driver 32 outputs a signal to the signal line 42 of the pixel electrode 40 based on the pixel data PD output from the image memory unit 30. When receiving the control signal CS, the scan driver 33 sequentially scans the scanning lines 43 of the pixel electrodes 40 line by line. The TFT 41 is driven according to the output of the signal from the data driver 32 and the scanning of the scan driver 33, a voltage is applied to the pixel electrode 40, and the transmitted light intensity of the pixel is controlled.
[0038]
The backlight control circuit 35 supplies a drive voltage to the backlight 22 when receiving the control signal CS, and applies the driving voltage to the red, green, and blue colors of the LED array 7 (16 LED chips 17) of the backlight 22. The LED elements of each color emit light in a time-division manner, and sequentially emit red light, green light, and blue light over time. At this time, lighting / off of the LED elements of each color is controlled for each of the first block and the second block. However, eight LED elements of each color are controlled collectively in the first and second blocks, and all LED elements of the corresponding color in each block are turned on and turned off simultaneously. Further, at the time of lighting, the brightness of the LED element of each color is adjusted for each of the first block and the second block. However, within each block, the brightness of all LED elements of the corresponding color is the same.
[0039]
The liquid crystal panel 21 and the backlight 22 are superimposed, and color display is performed by a field sequential method according to a drive sequence as shown in FIG. Assuming that the frame frequency is 60 Hz, one frame (period: 1/60 s) is divided into three subframes (period: 1/180 s), and for example, as shown in FIG. In the second sub-frame, two data scans of the red image data are performed, in the next second sub-frame, two data scans of the green image data are performed, and in the last third sub-frame, the blue scan is performed. Two data scans of the image data are performed. In two data scans in each subframe, a voltage applied to the liquid crystal of each pixel during the first (first half) data scan and a voltage applied to the liquid crystal of each pixel during the second (second half) data scan Means that the polarities are opposite and substantially equal. Then, the polarity of the voltage applied to the liquid crystal is set so that the luminance by the first data scanning is higher than the luminance by the second data scanning.
[0040]
On the other hand, as shown in FIG. 7B, lighting of each color of the backlight 22 in red, green, and blue is a part of each sub-frame. That is, emission of red light, green light, or blue light is started in synchronization with the start timing of the first (first half) data scanning (start timing of the subframe), and the end timing of the second (second half) data scanning is started. The light emission is stopped in synchronization.
[0041]
Here, in the present invention, using the circuit configuration shown in FIG. 6, the magnitude of the drive current to the LED element of each color in the red, green, and blue subframes is determined by the first block and the second block. Independently controlled every time. For example, color display can be performed by turning off all the eight LED chips 17 belonging to the first block and turning on only the eight LED chips 17 belonging to the second block. Even in this case, since the LED chips 17 of the first block and the LED chips 17 of the second block are arranged alternately, since the LED chips 17 are uniformly distributed in each block, there is little unevenness. Uniform display is possible.
[0042]
Further, since the magnitude of the drive current of the LED element is separately controlled in each of the first block and the second block, finer adjustment of luminance is possible. It is assumed that the magnitude of the driving current of the LED element can be controlled in five stages including the case of 0. FIGS. 8A and 8B are schematic diagrams showing the conventional example and the example of luminance adjustment in the present invention in such a case, that is, the conventional example and the magnitude of the screen luminance that can be realized in the present invention. . 8A and 8B, the area represents the size (level) of the screen luminance.
[0043]
In a conventional example in which all the LED elements (LED chips) of each color are collectively controlled, as shown in FIG. 8A, only five screen luminance levels equal to the number of drive current types can be realized. On the other hand, in the present invention, the first block and the second block individually control the magnitude of the driving current of the LED element (LED chip) of each color, and therefore, as shown in FIG. Screen luminance can be realized.
[0044]
As described above, according to the present invention, it is possible to finely adjust the screen luminance. Also, in comparison with the conventional example in which all the LED chips are collectively controlled as one block, when a drive power supply circuit having the same current capacity is used, in the present invention, the drive current flowing through each of the first and second blocks is reduced. Since the brightness can be increased up to twice, high brightness can be realized.
[0045]
Another embodiment of the present invention will be described. In the following embodiment, input pixel data of three colors of red, green, and blue are converted into pixel data of four colors of red, green, blue, and white, and full-color is used using the converted pixel data of four colors. Display. First, the conversion method will be described.
[0046]
FIG. 9A shows the original red (r), green (g), and blue (b) gradation levels in each frame, and FIG. 9B shows the converted red (r ') in each frame. ), Green (g ′), blue (b ′), and white (w). In each frame, the lowest gradation level is detected by comparing the gradation levels of the red, green, and blue pixel data. For example, in the first frame shown in FIG. 9A, the gradation level of the green display data is the lowest. In this case, in the red and blue display sub-frames, the gradation level (r ′ = r−) obtained by subtracting the green gradation level (g) from the red and blue gradation levels (r, b) before comparison. g, b '= b-g).
[0047]
In a white display subframe that is a mixed color of red, green, and blue, white display (w = g) is performed according to the green gradation level (g). In the green display sub-frame, the green display corresponding to the gray level (g ′ = gg) obtained by subtracting the green gray level (g) from the green gray level (g) before the comparison is performed. However, since the subtracted gradation level (g ') becomes 0, this generally results in "black" display.
[0048]
FIG. 10 is a block diagram showing a circuit configuration of a liquid crystal display device according to such another embodiment. 10, the same or similar members as those in FIG. 1 are denoted by the same reference numerals. In the white subframe, the red, green, and blue LED elements of the LED chip 17 are simultaneously turned on while independently controlling the first block and the second block.
[0049]
In FIG. 10, reference numeral 23 denotes a pixel data conversion circuit for converting three-color pixel data PD input from an external personal computer, for example, into four-color pixel data PD 'for display in accordance with the above-described method. The conversion circuit 23 outputs the converted pixel data PD 'to the image memory unit 30. The other components such as the control signal generation circuit 31, the data driver 32, the scan driver 33, and the reference voltage generation circuit 34 have the same configuration and operation as described above, except that the pixel data PD is changed to the converted pixel data PD '. Since it is basically the same as the embodiment (FIG. 1), description thereof will be omitted.
[0050]
FIG. 11 is a diagram showing a driving sequence in such another embodiment. Assuming that the frame frequency is 60 Hz, one frame (period: 1/60 s) is divided into four subframes (period: 1/240 s), and for example, as shown in FIG. , Two data scans of the red image data are performed in the next subframe, two data scans of the green image data are performed in the next second subframe, and the blue scan is performed in the next third subframe. Two data scans of the image data are performed, and two data scans of the white image data are performed in the last fourth subframe. In the two data scans in each sub-frame, a voltage applied to the liquid crystal of each pixel during the first (first half) data scan and a voltage applied to the liquid crystal of each pixel during the second (second half) data scan. Voltage is opposite in polarity and substantially equal in magnitude. Then, the polarity of the voltage applied to the liquid crystal is set so that the luminance by the first data scanning is higher than the luminance by the second data scanning.
[0051]
On the other hand, as shown in FIG. 11B, lighting of each color of the backlight 22 in red, green, blue, and white is a part of each subframe. That is, emission of red light, green light, blue light or white light is started in synchronization with the start timing of the first (first half) data scanning (start timing of the subframe), and the second (second half) data scanning is started. The light emission is stopped in synchronization with the end timing.
[0052]
In this embodiment, the magnitude of the drive current to the LED elements in the red, green, blue, and white subframes is determined for each of the first block and the second block by using the circuit configuration shown in FIG. Since independent control is performed, similar to the above-described embodiment using the red, green, and blue subframes, the display luminance can be improved and the effect of easily adjusting the screen luminance with high accuracy can be obtained. Play.
[0053]
In the above-described embodiment, the number of block divisions is set to two. However, it goes without saying that the same operation can be performed even when the number of divisions is three or more. The larger the number of blocks to be divided, the higher the display luminance can be realized, and the more accurate the screen luminance can be adjusted. Therefore, it is necessary to make the number of divided blocks equal to the number of LED chips. Ideal if you don't care. In the present invention, the LED chips are connected in parallel in the block, but may be connected in series.
[0054]
Further, a ferroelectric liquid crystal material exhibiting a half V-shaped electro-optical response characteristic is used as a liquid crystal material, but a ferroelectric liquid crystal material exhibiting a V-shaped electro-optical response characteristic or a half-V An antiferroelectric liquid crystal material exhibiting a V-shaped or V-shaped electro-optical response characteristic may be used. Although the light source used is an LED light source, the light source is not particularly limited to the LED light source as long as it is a light source such as an EL (Electronic Luminescence), a cold cathode tube or the like.
[0055]
In the above-described embodiment, the field sequential type liquid crystal display device has been described as an example. However, a similar effect can be obtained in a color filter type liquid crystal display device provided with a color filter. This is because the present invention can be similarly applied by dividing a plurality of white light source elements that emit white light into a plurality of blocks.
[0056]
FIG. 12 is a schematic sectional view of a liquid crystal panel and a backlight in a color filter type liquid crystal display device. 12, the same parts as those in FIG. 2 are denoted by the same reference numerals, and description thereof will be omitted. The common electrode 3 is provided with color filters 60 of three primary colors (R, G, B). The backlight 22 includes a white light source 70 having a plurality of white light source elements that emit white light, and a light guide and light diffusion plate 6. The plurality of white light source elements constituting the white light source 70 are divided into a plurality of blocks, and the driving is independently controlled for each block. In such a color filter type liquid crystal display device, color display is performed by selectively transmitting white light emitted from the white light source 70 through the color filters 60 of a plurality of colors.
[0057]
Even in the color filter type liquid crystal display device, similarly to the above-described field sequential type liquid crystal display device, a plurality of white light source elements are divided into a plurality of blocks, and collective lighting / collective lighting control and By performing the brightness adjustment, the same effect can be obtained that the display brightness can be improved and the screen brightness can be adjusted with high accuracy.
[0058]
【The invention's effect】
As described in detail above, in the present invention, a plurality of display light sources are divided into a plurality of blocks, and collective lighting / collective turning off of the display light sources in each block is controlled in units of each block. The display luminance can be improved, and the screen luminance can be easily adjusted with high accuracy.
[0059]
Further, in the present invention, since the plurality of display light sources in each of the plurality of divided blocks are arranged so as to be substantially uniformly distributed, even if all of the installed display light sources are not turned on, at least By turning on all the display light sources in one block, it can function as a light source for uniform surface light emission, and uniform high-luminance display can be realized.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating an example of a circuit configuration of a liquid crystal display device of the present invention.
FIG. 2 is a schematic sectional view of a liquid crystal panel and a backlight of a field sequential liquid crystal display device.
FIG. 3 is a schematic diagram showing an example of the overall configuration of a liquid crystal display device of the present invention.
FIG. 4 is a graph showing an electro-optical response characteristic of a liquid crystal material used in the liquid crystal display device of the present invention.
FIG. 5 is a plan view of a backlight in the liquid crystal display device of the present invention.
FIG. 6 is a diagram showing a driving circuit of an LED array in the liquid crystal display device of the present invention.
FIG. 7 is a diagram showing an example of a driving sequence in the field sequential type liquid crystal display device of the present invention.
FIG. 8 is a diagram showing an example of luminance adjustment in the conventional example and the present invention.
FIG. 9 is a diagram showing a conversion example of pixel data in the liquid crystal display device of the present invention.
FIG. 10 is a block diagram showing another example of the circuit configuration of the liquid crystal display device of the present invention.
FIG. 11 is a diagram showing another example of the driving sequence in the field sequential type liquid crystal display device of the present invention.
FIG. 12 is a schematic cross-sectional view of a liquid crystal panel and a backlight of a color filter type liquid crystal display device.
[Explanation of symbols]
3 Common electrode
7 LED array
17 LED chip
21 LCD panel
22 Backlight
31 Control signal generation circuit
32 Data Driver
35 Backlight control circuit
40 pixel electrode
41 TFT
60 color filter
70 White light source

Claims (6)

In a liquid crystal display device including a plurality of display light sources, the display light sources are grouped into a plurality of groups, and a unit for controlling collective lighting / blanking of the display light sources for each group is provided. Liquid crystal display. 2. The liquid crystal display device according to claim 1, wherein the display light sources in each group are substantially uniformly distributed. 3. The liquid crystal display device according to claim 1, wherein the display light source is a light source that emits red, green, and blue light, or red, green, blue, and white light. The liquid crystal display device according to claim 1, wherein the display light source is a light emitting diode. 5. The liquid crystal display device according to claim 1, wherein a liquid crystal material having spontaneous polarization is used. 6. The liquid crystal display device according to claim 1, wherein color display is performed by a field sequential method.

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