Source: https://patents.google.com/patent/JP2009031585A/en
Timestamp: 2019-11-12 17:28:41
Document Index: 283272446

Matched Legal Cases: ['art.\n2', 'art, 20', 'art, 21', 'art, 22', 'art, 23', 'art, 40', 'art, 41']

JP2009031585A - Liquid crystal display device - Google Patents
JP2009031585A
JP2009031585A JP2007196238A JP2007196238A JP2009031585A JP 2009031585 A JP2009031585 A JP 2009031585A JP 2007196238 A JP2007196238 A JP 2007196238A JP 2007196238 A JP2007196238 A JP 2007196238A JP 2009031585 A JP2009031585 A JP 2009031585A
JP2007196238A
雅基 土田
2007-07-27 Application filed by Toshiba Corp, 株式会社東芝 filed Critical Toshiba Corp
2007-07-27 Priority to JP2007196238A priority Critical patent/JP2009031585A/en
2009-02-12 Publication of JP2009031585A publication Critical patent/JP2009031585A/en
PROBLEM TO BE SOLVED: To provide a liquid crystal display device having improved dynamic characteristics by suppressing the supply of light from a light source to an image display area where image data is not displayed.
In a liquid crystal display device that includes a display panel for displaying video and a backlight and scan-controls the backlight, video analysis means for analyzing a video signal input from the outside and correcting the video signal; The panel control means for sending the corrected video signal data from the video analysis means to the display panel and controlling the display panel, while taking into account the backlight light source profile based on the information required for backlight control input from the video analysis means A liquid crystal display device comprising: backlight control means for making the luminance constant without changing the black insertion rate and further reducing the luminance of the extinguishing part.
2. Description of the Related Art Conventionally, a liquid crystal display device using a liquid crystal panel is known in which a light source for supplying light from the back side of the liquid crystal panel to an image display area of the liquid crystal panel is provided. In such a light source, for example, by arranging a plurality of light guide plates extending in the horizontal direction vertically, light from the light source can be uniformly supplied to the image display region.
Currently, a CCFL (Cold Cathode Fluorescent Lamp) tube is generally used as a backlight of a liquid crystal display device. Recently, backlights using LEDs have been commercialized. Among them, there are many proposals such as blinking in which the backlight is turned on and off for each horizontal line. The content of this is that when performing scan control for each line, the ratio of black insertion that turns off the backlight and makes the panel transmittance of the video signal 0%, the timing of black insertion, or lighting It is the timing to make it.
For example, Patent Document 1 is a patent for a liquid crystal display device that can further improve moving image performance without lowering the brightness. In particular, the lighting timing of the divided light source region is set to the lighting timing of the central portion and the upper and lower regions. Has proposed a driving method that improves the performance of moving images by matching the lighting timing of.
However, there are few proposals for line control in consideration of the profile that is the spread of the light source of the backlight. That is, there is no disclosure of a technique regarding a light source profile that further improves moving image performance without lowering luminance.
Japanese Patent Laying-Open No. 2005-222011 (page 25, FIG. 5)
That is, in the above technique, since the light guide plate extends in the horizontal direction, the light from the light source may be supplied even to an area where no image is displayed. If light is supplied to a region where no image is displayed, the dynamic characteristics may be degraded.
The present invention has been made to solve such a conventional problem, and an object of the present invention is to provide a liquid crystal display device having improved dynamic characteristics by suppressing the supply of light from a light source to an image display area where no image is displayed. And
In order to achieve the above object, the liquid crystal display device of the present invention analyzes a video signal input from the outside in a liquid crystal display device that includes a display panel for displaying video and a backlight and performs scanning control of the backlight, Necessary for video analysis means for correcting the video signal, panel control means for controlling the display panel by sending the video signal data corrected from the video analysis means to the display panel, and backlight control input from the video analysis means And a backlight control means for making the luminance constant without changing the black insertion rate while considering the backlight light source profile based on various information and further reducing the luminance of the extinguishing part.
The liquid crystal display device of the present invention has improved dynamic characteristics by suppressing the supply of light from the light source to the display area where the image is not displayed by making the light source on and off correspond to the display area where the image is displayed. .
Embodiments according to the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a liquid crystal display device 1 according to an embodiment of the present invention.
As shown in the figure, the liquid crystal display device 1 includes an image data receiving unit 10, an image data processing unit 20, an image display control unit 30, a display unit 40, and a backlight 50 as a light source.
The image data receiving unit 10 is connected to, for example, an antenna (not shown) installed outdoors, and receives image data via this antenna. For example, it is possible to receive various image data carried on terrestrial analog waves, terrestrial digital waves, satellite broadcast radio waves, and the like. Further, although not shown, the image data receiving unit 10 can also be connected to various image reproducing devices (for example, an HD-DVD player, the same recorder, a DVD player, the same recorder, etc.). In this case, the image data receiving unit 10 receives the image data reproduced by the image reproducing device.
The image data receiving unit 10 outputs the received image data to the image display control unit 30 and the image data processing unit 20. The image data received by the image data receiving unit 10 is configured in various aspect ratios such as 4: 3 and 16: 9 in detail. The aspect ratio is the ratio of the horizontal width to the vertical width of image data.
Image aspect ratio information indicating the aspect ratio of the image data is added to the image data.
The image display control unit 30 receives the image data output from the image data receiving unit 10 and causes the display unit 40 to display an image.
The display unit 40 is mainly composed of a liquid crystal panel 43, a gate driver 41, and a source driver 42.
The liquid crystal panel 43 is a liquid crystal panel having an aspect ratio of 16: 9. For example, here, when displaying image data having an aspect ratio of 16: 9 on the left and right, the display area 431, that is, the display area of the entire liquid crystal panel 43 is displayed. When displaying image data having an aspect ratio of 4: 3, an image is displayed using a display area 432 indicated by a broken line at the center.
The aspect ratio of the display area 431 is 16: 9. In the display area 431, an image composed of 16: 9 is displayed.
The aspect ratio of the display area 432 is 4: 3. In the display area 432, an image composed of 4: 3 is displayed.
Although not specifically shown, the liquid crystal panel 43 is configured by sandwiching a liquid crystal material between two pieces of glass and arranging scanning lines and data lines on the glass in a grid pattern. The scanning lines and the data lines are controlled by driving a gate driver 41 and a source driver 42 arranged at the end of the liquid crystal panel 43, respectively. The gate driver 41 has a function of sequentially outputting pulsed voltage waveforms to the scanning lines.
The source driver 42 supplies a voltage to the liquid crystal corresponding to the output of the pulsed voltage waveform by the gate driver 41. Thus, the liquid crystal panel 43 displays an image by applying a voltage to the liquid crystal by driving the source driver 42 and the gate driver 41.
The image data processing unit 20 includes an information acquisition unit 21, a light source control unit 22, and a memory 23. The information acquisition unit 21 receives the image data output from the image data receiving unit 10. The information acquisition unit 21 acquires image aspect ratio information added to the input image data, and outputs the acquired image aspect ratio information to the light source control unit 22.
The memory 23 stores turn-on / off table data of the backlight 50 referred to by the light source control unit 22 when the light source control unit 22 controls the light source unit 51. The on / off table data of the backlight 50 is information for turning on or off the plurality of light source units 51 constituting the backlight 50. This table data has different table data depending on the aspect ratio of the image data.
The light source control unit 22 reads the turn-on / off table data of the backlight 50 stored in the memory 23. The light source control unit 22 controls turning on / off of the plurality of light source units 51 configuring the backlight 50 based on the lighting / turning on / off table data of the backlight 50 corresponding to the image aspect ratio information output from the information acquisition unit 21. That is, the light source control unit 22 functions as a lighting control unit.
The backlight 50 is configured by arranging a plurality of light source units 51 in a vertical arrangement as one group, and this group is arranged in a plurality of rows horizontally.
The backlight 50 supplies light from the light source unit 51 to the display area 431 or the display area 432 of the display unit 40. That is, the backlight 50 functions as a light source.
The backlight 50 is provided on the back side of the liquid crystal panel 43.
Although not shown, a pair of diffusion plates and a prism sheet sandwiched between the diffusion plates are provided between the backlight 50 and the liquid crystal panel 43. The diffusion plate scatters and diffuses the light supplied from the light source unit to make the entire display area uniform brightness.
The prism sheet is for improving the luminance of the light supplied from the backlight 50.
The light source unit 51 includes a plurality of LEDs (Light Emitting Diodes) that emit light of three primary colors of RED (hereinafter referred to as R), GREEN (hereinafter referred to as G), and BLUE (hereinafter referred to as B). Yes. The light source unit 51 can emit white light by mixing the colors of RGB LEDs.
In the present invention, the configuration of the LEDs used in the light source unit 51 is not particularly limited. For example, one RLED, two GLEDs, and one BLED are combined, or two RLEDs, three GLEDs, One set of two BLEDs.
Further, the LEDs used are not limited to the three colors RGB, and various LEDs such as LEDs of four or more colors and white LEDs can be used as the light source.
Moreover, the light source which comprises the light source unit 51 is not limited to LED, A various light emitting element can be used. The light emitting element is, for example, an organic EL (Electro Luminescence), an inorganic EL, or a laser diode (LD).
Hereinafter, a configuration diagram of the liquid crystal display device 1 that performs backlight control in consideration of a light source profile (such as a convexity described later) of the present embodiment will be described.
FIG. 2 is a functional configuration diagram of a liquid crystal display device that performs backlight control in consideration of the light source profile of the present embodiment. Image analysis means 101 for analyzing the input video (corresponding to 10 in FIG. 1), panel control means 102 for controlling the panel as a driver (corresponding to 30 in FIG. 1), and backlight control in consideration of the light source profile Backlight control means 104 (corresponding to 20 in FIG. 1), a liquid crystal panel 103 (corresponding to 40 in FIG. 1) for displaying an image, and a backlight 105 (corresponding to 50 in FIG. 1).
Next, details of the operation will be described. Each value of the video signal input from the outside to the liquid crystal display device is corrected by the image analysis means 101 so that the optimal video signal and the optimal light source luminance are obtained. The video signal corrected by the image analysis unit 101 is input to the panel control unit 102 and controls the liquid crystal panel 103 according to the correction signal. On the other hand, the luminance of the light source set by the image analysis unit 101 and information for scanning control are input to the backlight control unit 104 to control the backlight 105. At this time, in the backlight control means 104, considering the light source profile, that is, the light spread, the backlight control means 104 maintains the same luminance as when the black insertion rate is not adjusted in accordance with the black insertion rate, and the black insertion portion. That is, control is performed so as to make it possible to reduce the luminance of the light-off area of the light source.
Next, an example of a light source capable of scanning the backlight will be described. 3A and 3B show examples of the backlight 105. FIG.
First, FIG. 3A will be described. This is an edge-type backlight light source using a light guide plate. The backlight 105 is divided into a plurality of parts by the light guide plate 108, and in this case, it is shown as six divisions. However, it is not necessary to stick to this division number, and a desired division number may be used. A light source unit 106 is arranged at the edge of the light guide plate 108 according to the number of divisions, and a light source unit 107 that emits RGB light is arranged in the light source unit. This light source is composed of LED, EL, or LD. The present invention may be a white light source such as pseudo white instead of RGB as described above. Further, a light source having a flat surface may be used instead of the light guide plate.
Next, FIG. 3B will be described. This is a backlight light source directly under the light source. This is a configuration corresponding to FIG. The backlight 105 is composed of light sources 106 having RGB, and each light source 106 is divided into a plurality of parts inside the backlight. In this case, the light sources 106 are arranged in a 6 × 8 grid. Yes. Of course, it is not necessary to be particular about the number of divisions, and a desired number of divisions may be used. In this arrangement, it is of course possible to control the light source as in area control at the same time as it is controlled so that it can be controlled in a line in the line direction of the screen. In this case as well, the RGB emitting element 106 may be an LED, EL, or LD. Of course, instead of RGB, a white light source such as pseudo white may be used.
Next, the method of the backlight control means will be described using a backlight using a light source divided in a lattice shape as shown in FIG. FIG. 4A is an explanatory diagram when attention is paid to one light source constituting the backlight. The light source 106 has its own light source spread and spread by an optical film such as a diffusion plate, and light is diffused from the original divided area. In the graph 110 indicated by the XY axes on the right side of the configuration diagram of the backlight, the X axis indicates the distance, and the Y axis indicates the relative luminance. A simple profile 111 indicating the spread of the light source is shown. The profile 111 can be approximated by a spread by a Gaussian distribution or a spread by an exponential function, and the profile 111 shown here shows a rough shape. In the following, the profile shape is also used as an explanatory diagram, but the numerical value of the profile is not particularly shown, but is illustrated to assist in understanding the description. FIG. 4B is a configuration diagram when one line is turned on for scanning control. While FIG. 4A shows the case of one light source, this is a configuration diagram when all the lines are turned on. The profile 112 in the vertical direction of the screen shows a spread almost the same as the previous one. Also, a filled rectangular portion 113 written in the graph 110 simply shows a special state in which one line is lit on the graph. In the following, the backlight control method will be described using this simple rectangular figure and profile shape.
FIG. 5 is a diagram illustrating a control example of backlight control. First, FIG. 5A will be described. This is a state when all the light sources of the backlight 105 are turned on. The state of full lighting at this time is expressed by a rectangle filled with the graph 110 on the right. In this case, the light source luminance value of each line is expressed as 0.5 as relative luminance, and the area of the filled rectangle is the total luminance of the whole. The following will be described with reference to FIG. FIG. 5B shows a case where black is inserted. It is assumed that a portion where the backlight 105 is painted is turned on and a portion other than that is turned off. Since the case shown here is a case of 6 divisions, the black insertion rate is 50% because half shows off and half shows on. The case of the black insertion rate of 50% will be described below. Normally, when the black insertion rate is 50%, the luminance is reduced to half as a whole. For this reason, as shown in FIG. 5 (b), by increasing the light source luminance of each line of the lighting portion from 0.5 to 1.0, the overall luminance is doubled to the same luminance as when all the lighting is on. Do things. In other words, the area of the filled rectangle is adjusted to be the same. The outline of the profile 114 at this time is also listed. In this case, the luminance at the position of the line A is the luminance at the position of a from the profile 114.
The above is the method that is normally performed, but the problem here is that the luminance on the line A is essentially off, so the luminance must be close to 0. When the light profile is widened, the luminance is higher than the original luminance. This causes a black float on the screen, a decrease in contrast, and a decrease in moving image performance. On the other hand, a control method that is a feature of the present embodiment will be described with reference to FIG. As described above with reference to FIG. 5 (b), simply increasing the luminance of the lit portion by the black insertion rate causes light to leak to the extinguished portion, which weakens the improvement in contrast and dynamic characteristics. . Therefore, in the light source region that is lit, the luminance of the light source located farthest from the extinguishing part is increased, and the luminance of the surroundings is decreased. In this method, the whole filled rectangle in the figure is lit like a convex shape. At this time, the overall luminance is made the same by adjusting the luminance to be lit so that the area is the same as the previous one. In addition, the shape of the profile 115 changes accordingly, and the luminance a in the line A can be further reduced as shown in b.
When the video signal is analyzed, the video signal correction value and the backlight luminance are determined, the correction value is given to the panel control means, and the backlight luminance is given to the backlight control means. Therefore, since the convex shape is already woven, it is not necessary to further correct the video signal in the case where the luminance at the center is maximized by the backlight control means.
The backlight control information includes the backlight brightness in addition to the line position.
FIG. 6 is a diagram simultaneously showing the above-described method in which the lighting method is changed (that is, a diagram in which FIGS. 5B and 5C are described on the same screen). It shows that the reduction effect and the overall luminance are the same, that is, the areas are the same.
As described above, in the scan control using the backlight, particularly the LED backlight, while maintaining the black insertion rate constant, the luminance is maintained at the same level as when all the lights are on, and the backlight is turned off on the screen. By implementing the method of further reducing the luminance, it is possible to realize a liquid crystal display device with high contrast and good dynamic characteristics.
Therefore, in this embodiment, in the scan control using the backlight, particularly the LED backlight, the black insertion rate is constant, the luminance is kept at the same level as when all the lights are turned on, and the backlight is turned off on the screen. Presented a method that can further reduce the luminance in the section and improve the dynamic characteristics.
In the method of scanning control of the backlight of the liquid crystal display device, control is performed in consideration of the light source profile (light source spread), and the brightness of the extinguishing part is reduced without reducing the brightness of the entire screen while the black insertion rate is constant. In order to further reduce the luminance, the luminance of the central portion of the lighting region is maximized according to the black insertion rate.
In many backlight scan controls of liquid crystal display devices, the dynamic characteristics have been improved by controlling the backlight turn-off or turn-on timing and the black insertion rate, but the light source profile of the backlight has also been considered. I can't see anything. Therefore, according to the present embodiment, in the scan control using the backlight, particularly the LED backlight, while maintaining the black insertion rate constant, the luminance is maintained at the same level as when all the lights are on, and the backlight is displayed on the screen. There is an effect that the dynamic characteristics can be improved by further reducing the luminance at the light-off portion.
1 is a block diagram showing a configuration of a liquid crystal display device according to an embodiment of the present invention. 1 is a block diagram illustrating a functional configuration of a liquid crystal display device according to an embodiment. An example of a light source capable of performing scan control on the backlight according to the embodiment. Explanatory drawing about the method of the backlight control means of embodiment. Explanatory drawing about the Example of the backlight control of embodiment. Explanatory drawing about the Example of the backlight control of embodiment.
DESCRIPTION OF SYMBOLS 1 ... Liquid crystal display device, 10 ... Image data receiving part, 20 ... Image data processing part, 21 ... Information acquisition part, 22 ... Light source control part, 23 ... Memory, 30 ... Image display control part, 40 ... Display part, 41 ... Gate driver 42... Source driver 43 43 Liquid crystal panel 431 First display area 432 Second display area 50 Backlight 51 Light source unit.
A backlight for irradiating the display panel with a backlight light source;
Video analysis means for analyzing video signals input from the outside and outputting backlight control information;
Backlight control means that makes the luminance of the lighting area of the backlight light source convex in the vicinity of the center while keeping the black image insertion rate constant based on the backlight control information input from the video analysis means,
Video correction means for correcting the video signal input from the outside according to the convexity;
A liquid crystal display device comprising: panel control means for controlling the display panel by sending video signal data corrected by the video correction means to the display panel.
2. The liquid crystal display according to claim 1, wherein the backlight light source is a partial light source that performs scan control, and each partial light source is controlled by being divided into a plurality of parts in a direction perpendicular to the scan control direction of the display panel. apparatus.
The liquid crystal display device according to claim 1, wherein the backlight control unit has the highest luminance at the center of the lighting region.
The video display device according to claim 1, wherein the partial light source includes one or a plurality of light emitting elements.
5. The liquid crystal display device according to claim 4, wherein the light emitting element is any one of an LED (Light Emitting Diode), an EL (Electro Luminescence), and an LD (Laser Diode).
JP2007196238A 2007-07-27 2007-07-27 Liquid crystal display device Pending JP2009031585A (en)
JP2007196238A JP2009031585A (en) 2007-07-27 2007-07-27 Liquid crystal display device
JP2009031585A true JP2009031585A (en) 2009-02-12
ID=40402149
JP2007196238A Pending JP2009031585A (en) 2007-07-27 2007-07-27 Liquid crystal display device
JP (1) JP2009031585A (en)
JP2013015585A (en) * 2011-06-30 2013-01-24 Toshiba Corp Display device and display method
2007-07-27 JP JP2007196238A patent/JP2009031585A/en active Pending