JP2008071603A - Backlight, transmission type display device, and control method of transmission type display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display with improved power consumption reduction effect of a backlight, in a liquid crystal display carrying out brightness control using an active backlight. <P>SOLUTION: The backlight 17 is provided with light-emitting areas 17A to 17D capable of controlling emission brightness by backlight brightness adjustment parts 16A to 16B, respectively. An emission brightness of each of the light-emitting area 17A to 17D is set in compliance with maximum display brightness of the corresponding display area, with a transmittance of pixels in a liquid crystal panel 20 set in accordance with an emission brightness value of each light-emitting area 17A to 17D of the backlight. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a backlight used in a transmissive display device such as a liquid crystal display device, and a control method therefor.

  There are various types of color displays, each of which has been put to practical use. Thin displays can be broadly classified into self-luminous displays such as PDP (plasma display panel) and non-luminous displays typified by LCD (liquid crystal display). As an LCD that is a non-light-emitting display, a transmissive LCD in which a backlight is disposed on the back side of a liquid crystal panel is known.

  FIG. 13 is a cross-sectional view showing a general structure of a transmissive LCD. In this transmissive LCD, a backlight 110 is disposed on the back surface of the liquid crystal panel 100. The liquid crystal panel 100 has a configuration in which a liquid crystal layer 103 is disposed between a pair of transparent substrates 101 and 102, and polarizing plates 104 and 105 are provided outside the pair of transparent substrates 101 and 102. Further, by providing the color filter 106 in the liquid crystal panel 100, color display is possible.

  Although illustration is omitted, an electrode layer and an alignment film are formed inside the transparent substrates 101 and 102, and the amount of light transmitted through the liquid crystal panel 100 is controlled by controlling the voltage applied to the liquid crystal layer 103. Are controlled for each pixel. In other words, the transmissive LCD performs display control by controlling the amount of light emitted from the backlight 110 through the liquid crystal panel 110.

  The backlight 110 is mainly a white backlight including three wavelengths of RGB necessary for a color display, and by adjusting the light transmittance of each color of RGB by combination with the color filter 106, respectively. It is possible to arbitrarily set the luminance and hue as a pixel. The backlight 110 includes a light source for each of RGB colors.

  For example, in the LCD described above, the transmittance of the output display information is controlled by the shutter action of the liquid crystal panel 110 with the RGB color filters 106 existing for each pixel, and the range of 0 to 100% is determined. The intensity of transmitted light is controlled by controlling in steps. When 100% of the irradiation light of the backlight 110 is transmitted, ideally, the corresponding color element intensity of the backlight light is output as it is, and this time is the maximum luminance. Further, when the transmittance is 0%, the display is black. Thus, in the configuration of a normal transmissive LCD that performs display control by the shutter action of the liquid crystal panel 110, the backlight 110 continues to emit light with a certain luminance.

  However, the above configuration in which the luminance of the backlight 110 is constant has a problem that power consumption by the backlight 110 is large. That is, even when the LCD performs a dark screen display as a whole, the backlight 110 emits light with the maximum luminance, and much of the irradiation light is blocked by the shutter action of the liquid crystal panel 100. It becomes. For this reason, the amount of emitted light in the backlight 110 is wasted, and the power consumption of the backlight 110 is increased. In the LCD, since the backlight occupies most of the power consumption, this waste is a very large loss when viewed from the whole system.

  In order to deal with such a problem, Patent Document 1 discloses that an active backlight with adjustable brightness is used, and LCD display control (brightness control) is performed by controlling the transmittance of the liquid crystal panel and the brightness of the active backlight. A technique for reducing the power consumption of the light is disclosed. FIG. 14 shows a schematic configuration of the LCD system described in Patent Document 1.

  The LCD shown in FIG. 14 is configured such that the CPU 202 sends image information stored in the RAM 201 to an active BL (backlight) controller 203. Then, the active BL controller 203 controls the transmittance of the liquid crystal panel 210 via the liquid crystal drivers 204 and 205, and the red backlight 207R and the green backlight 207G via the backlight luminance adjustment units 206R, 206G, and 206B. , The luminance of the blue backlight 207B is controlled. That is, in the LCD, each of the red backlight 207R, the green backlight 207G, and the blue backlight 207B is an active backlight whose brightness can be adjusted.

  With reference to FIGS. 15A to 15C, the power consumption reduction effect of the backlight in Patent Document 1 will be described. In the following, for the sake of simplicity of explanation, display control in an area composed of four pixels (one pixel includes each color component of RGB) will be exemplified.

  First, consider a case where display is performed with display data as shown in FIG. 15A when the display gradation is 256 gradations (0 to 255). Here, when the backlight luminance control is not performed, the backlight luminance is the maximum luminance (255), and only the transmittance of the liquid crystal panel is controlled according to the display data (see FIG. 15B). ).

On the other hand, as shown in FIG. 15C, when performing display control using an active backlight, the brightness of the backlight is controlled to match the maximum brightness value in the display data. When a backlight is provided for each color of RGB, the luminance of the backlight of each color is controlled so as to match the maximum luminance value of the corresponding color component. The transmittance of the liquid crystal panel is adjusted according to the luminance of the backlight at that time. For example, in FIG. 15C, in order to display R = 128, the backlight brightness of R is set to 128, and the transmittance of the corresponding pixel of the liquid crystal panel is set to 255 (100%). Luminance (= luminance 128 × transmittance 100%) is obtained. In order to display R = 128, the backlight brightness of R is set to 255, and the transmittance of the corresponding pixel of the liquid crystal panel is set to 128 (50%). The brightness is reduced from 255 to 128.
JP 2006-47594 A (published February 16, 2006)

  However, in the configuration of Patent Document 1, the luminance control of the active backlight is performed by using the entire screen as one area. For this reason, even if the display brightness is low on most of the screens, if the display brightness is high on some screens, the brightness of the backlight must be set in accordance with the partial screen on which the display brightness is high. In such a case, in most of the screens with low display brightness, the amount of light emitted from the backlight is wasted, and the power consumption reduction effect of the backlight is reduced.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a liquid crystal display device that can increase the power consumption reduction effect of the backlight in a liquid crystal display device that performs luminance control using an active backlight. Is to realize.

  In order to solve the above-described problems, the backlight according to the present invention has a plurality of light emitting regions each capable of controlling light emission luminance.

  Further, in the backlight, the plurality of light emitting areas are configured in different voltage input systems of light sources existing in the respective light emitting areas, or the plurality of light emitting areas exist in the respective light emitting areas. The control signal input system for controlling the light emission period of the light source can be different.

  In order to solve the above problems, the transmissive display device according to the present invention includes a backlight and a transmission control panel, and the transmittance of the light emitted from the backlight is controlled by the transmission control panel. In the transmissive display device that performs display, the backlight has a plurality of light emitting regions each capable of controlling light emission luminance, and light emission that sets the light emission luminance in each light emitting region of the backlight. It is characterized by comprising brightness setting means and transmittance setting means for setting the transmittance of the pixels in the transmission control panel in accordance with the emission luminance value for each light emitting area of the backlight.

  According to the above configuration, since the backlight can control the light emission luminance for each, the display screen on the transmission control panel is divided into a plurality of areas, and the transmission is performed for each of the divided areas. Control of the transmittance of the control panel and luminance control of the backlight can be performed. Thereby, compared with the structure of patent document 1 which performs the brightness | luminance control of a backlight by making the whole screen into one area | region, the further power consumption reduction of a backlight can be aimed at.

  In the transmissive display device, the light emission luminance change timing in each of the light emitting regions can be configured to coincide with the beginning of the pixel rewriting period in each light emitting region.

  According to the above configuration, the non-corresponding period between the backlight luminance and the pixel transmittance is shortened, and image deterioration due to a difference between the backlight luminance change timing and the liquid crystal transmittance change timing can be suppressed.

  In the transmissive display device, a period in which pixel rewriting is not performed can be provided in one frame period.

  According to the above configuration, by providing a period during which one pixel does not rewrite pixels (for example, by increasing the driving frequency of the liquid crystal panel to shorten the pixel rewriting period), back-up within one frame period is achieved. The non-corresponding period between the light luminance and the pixel transmittance can be further shortened, and image degradation due to a difference between the backlight luminance change timing and the liquid crystal transmittance change timing can be suppressed.

  In the transmissive display device, the light emitting area is turned off during the pixel rewriting period corresponding to each light emitting area, and the backlight luminance of the light emitting area is changed when the pixel rewriting is completed. it can.

  According to the above configuration, during the pixel rewriting period in each area, the corresponding light emitting area is turned off, so that the non-corresponding period between the backlight luminance and the pixel transmittance can be completely eliminated. Degradation of the image due to a difference between the luminance change timing and the liquid crystal transmittance change timing can be avoided.

  In the transmissive display device, the backlight may have a white light source.

  According to said structure, in each light emission area | region of the said backlight, the brightness | luminance of each color of RGB can be adjusted collectively, and the structure of a backlight can be simplified.

  In the transmissive display device, the backlight includes a light source for each color of RGB, and the light emission luminance value can be controlled for each color of RGB.

  According to said structure, since the brightness | luminance of each color of RGB can be controlled separately in each light emission area | region of the said backlight, the power consumption reduction effect of a backlight can be improved more.

  In the transmissive display device, the light emission luminance value for each light emitting region of the backlight may be configured to match the maximum display luminance value in each light emitting region.

  According to said structure, since the brightness | luminance in each light emission area | region of the said backlight can be set to the minimum brightness | luminance required for a display, the power consumption reduction effect of a backlight can be improved more.

  In the transmissive display device, the transmissive control panel may be a liquid crystal panel.

  As described above, the backlight according to the present invention has a plurality of light emitting regions each capable of controlling the light emission luminance.

  Further, as described above, the transmissive display device according to the present invention includes the backlight and the transmission control panel, and displays the irradiation light from the backlight by controlling the transmittance by the transmission control panel. In the transmissive display device, the backlight has a plurality of light emitting regions each capable of controlling light emission luminance, and light emission luminance setting means for setting the light emission luminance in each light emission region of the backlight. And a transmittance setting means for setting the transmittance of the pixel in the transmission control panel in accordance with the light emission luminance value for each light emitting region of the backlight.

  Therefore, in the transmissive display device, the display screen on the transmissive control panel can be divided into a plurality of regions, and the transmittance control of the transmissive control panel and the brightness control of the backlight can be performed for each of the divided regions. it can. Thereby, compared with the structure of patent document 1 which performs the brightness | luminance control of a backlight by making the whole screen into one area | region, there exists an effect that the power consumption of a backlight can be aimed at further.

  An embodiment of the present invention will be described below with reference to FIGS. First, a schematic configuration of the liquid crystal display device according to the present embodiment will be described with reference to FIG.

  The liquid crystal display device shown in FIG. 1 includes a RAM 11, a CPU 12, an active BL controller 13, liquid crystal drivers 14 and 15, a liquid crystal panel 20, a backlight luminance adjustment unit 16, and a backlight 17.

  In the liquid crystal display device, the image information stored in the RAM 11 is sent from the CPU 12 to the active BL (backlight) controller 13. The active BL controller 13 controls the transmittance of the liquid crystal panel 20 via the liquid crystal drivers 14 and 15 and controls the luminance of the backlight 17 via the backlight luminance adjusting unit 16.

  Here, the backlight 17 is a white backlight including RGB three-color wavelengths, and four light emitting areas 17A to 17D are provided corresponding to the display areas obtained by dividing the display screen of the liquid crystal panel 20 into four. Have. The backlight 17 is an active backlight that can individually adjust the luminance in each of the light emitting regions 17A to 17D. The backlight luminance adjusting unit 16 includes backlight luminance adjusting units 16A to 16D, and the light emission luminances of the light emitting areas 17A to 17D are controlled by the backlight luminance adjusting units 16A to 16D, respectively.

  In other words, the liquid crystal display device according to the present embodiment divides the display screen of liquid crystal panel 20 into a plurality of regions, and for each divided region, is based on the transmittance of the liquid crystal panel and the luminance control of the active backlight. And display control.

  With reference to FIGS. 2A and 2B, the backlight power consumption reduction effect in the liquid crystal display device shown in FIG. 1 will be described. In the following, in order to simplify the description, display control is exemplified on the assumption that the display screen is composed of 8 pixels (each pixel includes RGB color components).

  First, consider a case where display is performed with display data as shown in FIG. 2A when the display gradation is 256 gradations (0 to 255). Here, it is assumed that the display screen is divided into four areas, with two pixels as one area. In FIGS. 2A and 2B, the upper left two pixels are the region A, the upper right two pixels are the region B, the lower left two pixels are the region C, and the lower right two pixels are the region D.

  In the display control, as shown in FIG. 2B, the luminance of the backlight is controlled so as to coincide with the maximum luminance value in the display data in each area A to D. The transmittance of the liquid crystal panel is adjusted according to the luminance of the backlight at that time. For example, in FIG. 2B, the maximum luminance value of the region A is R = 128, and the backlight luminance is 128 in this region A. The transmittance of the pixels in the region A is determined so that a desired display brightness can be obtained with the backlight brightness value set to 128. In the regions B to D, the luminance value of the backlight is set to 60.

  As described above, in the liquid crystal display device, even if the maximum luminance value in the entire screen is 128, the backlight luminance value may be set to 128 only in the region A including the pixel having the maximum luminance value. In B to D, lower backlight luminance values can be obtained. Therefore, the power consumption of the backlight can be further reduced as compared with the configuration of Patent Document 1 in which the luminance of the active backlight is controlled with the entire screen as one region.

  In the above description, the number of divisions of the display screen is 4. However, the present invention is not limited to this, and the number of divided areas is arbitrary. Further, the size and shape of the divided regions may be the same in all the regions, or may be different from each other.

  Next, the control timing of backlight luminance control and liquid crystal panel transmittance control in the liquid crystal display device will be described.

  In the active backlight according to the present embodiment, desired display luminance can be obtained by controlling both the luminance of the backlight and the liquid crystal transmittance. In this case, basically, in each pixel, the backlight luminance change timing and the liquid crystal transmittance change timing need to match.

  However, in actuality, rewriting of pixels in the liquid crystal panel is performed line-sequentially in the vertical direction. For this reason, when the luminance is changed at the same timing in all the light emitting areas of the active backlight, there is a difference between the backlight luminance changing timing and the liquid crystal transmittance changing timing. Since there is a period in which the transmittance does not correspond, normal display cannot be performed. For example, consider a case where the display area in the liquid crystal panel and the light emitting area in the active backlight are divided into nine areas A to I as shown in FIG. At this time, as shown in FIG. 4, if the luminance is changed at the head of the frame in all the light emitting areas corresponding to the areas A to I, a large deviation occurs between the backlight luminance changing timing and the liquid crystal transmittance changing timing. To do. In particular, the lower the screen is, the greater the deterioration of the image because the backlight luminance and the pixel transmittance do not correspond in most of one frame period.

  As one method for avoiding such a problem, as shown in FIG. 5, in each light emitting area of the active backlight, the luminance change timing is matched with the head of the pixel rewriting period in each light emitting area. Conceivable. In the timing control shown in FIG. 5, the non-corresponding period between the backlight luminance and the pixel transmittance is shortened compared to the timing control shown in FIG. 4, and image degradation can be suppressed. The backlight luminance shown in FIGS. 4 and 5 is an illustration for showing the luminance change timing, and the actual backlight luminance value is different for each light emitting area.

  When the timing control as shown in FIG. 5 is performed, in each light emitting area of the active backlight and the display area in the liquid crystal panel corresponding thereto, the non-contrast between the backlight luminance and the pixel transmittance is reduced as the vertical line width is reduced. The response period is shortened and good display can be performed. However, also in the timing control described above, the backlight luminance change timing and the liquid crystal transmittance change timing completely coincide with each other only in the first line of each region, and do not coincide with the second and subsequent lines. For this reason, if the vertical line width in each light emitting area and display area is large, the above-described timing shift problem cannot be solved sufficiently.

  As a method for more effectively suppressing the timing shift problem, as shown in FIG. 6, the pixel rewriting period is shortened by increasing the driving frequency of the liquid crystal panel during one frame period. It is conceivable to provide a period during which pixel rewriting is not performed. In such a period in which no rewriting is performed, the backlight luminance and the pixel transmittance can be completely matched in all the regions. As a result, the backlight luminance and the pixel transmittance in one frame period are not supported. The period is further shortened compared to the control in FIG.

  Further, as a method for surely solving the timing shift problem, as shown in FIG. 7, in the pixel rewriting period of each area, the light emitting area of the backlight corresponding to the area is turned off (or the luminance is sufficiently reduced). Control method is possible. Then, when the pixel rewriting of each region is completed, the backlight luminance is changed so that the emission luminance corresponding to the pixel transmittance is obtained.

  According to this control, during the pixel rewriting period in each area, the corresponding light emitting area is turned off, so that the non-corresponding period between the backlight luminance and the pixel transmittance can be completely eliminated. In addition, since the light-out period is provided in each light-emitting area of the backlight, the luminance of the entire frame is lowered. However, this can be dealt with by increasing the light-emitting luminance during lighting.

  In the liquid crystal display device, it is necessary to use a backlight 17 capable of controlling the light emission luminance for each divided region. Next, the configuration of such a backlight will be described.

  In a backlight used in a liquid crystal display device, a fluorescent tube (such as a cold cathode tube) or an LED (Light Emitting Diode) is used as a light source. For example, in a backlight using a fluorescent tube as a light source, when the fluorescent tube is arranged as shown in FIG. 8A, the backlight is arranged along the arrangement row of the fluorescent tube as shown in FIG. 8B. It is conceivable to divide the light area. Further, for example, when an LED is used as the light source, as shown in FIG. 9, for example, as shown in FIG. 9, in each area divided in the backlight, the LED existing in the area is used as the light source of the area. Good.

  In the present invention, the number of divided areas in the backlight is not particularly limited, and the shape of each divided area is not particularly limited. Furthermore, the same size and shape are not necessarily required in all divided areas.

  In the backlight divided into regions as described above, the following method can be considered in order to control the light emission luminance for each divided region.

  For example, if the light source used for the backlight is a light source whose emission brightness can be controlled by the input voltage, the voltage input system to each area is different, and the input voltage for obtaining the required emission brightness in each area is individually set. It can be set as the structure supplied to. Alternatively, when the light source used for the backlight is a light source whose light emission luminance can be controlled by controlling the light emission period, a control signal for controlling the light emission period is individually supplied to each region. Can do. Taking the liquid crystal display device of FIG. 1 as an example, in any control, the backlight luminance adjustment units 16A to 16D perform the above-described control on the light emitting areas 17A to 17D of the backlight 17, respectively.

  The liquid crystal display device described above exemplifies a configuration using a backlight including a white light source. In this configuration, the luminance of each color of RGB can be adjusted collectively, and the configuration of the backlight can be simplified. However, the present invention is not limited to this, and a configuration using a backlight having a light source for each color of RGB may be used. FIG. 10 shows a configuration example of a liquid crystal display device using a backlight having a light source for each color of RGB.

  The liquid crystal display device shown in FIG. 10 includes a RAM 11, a CPU 12, an active BL controller 13, liquid crystal drivers 14 and 15, a liquid crystal panel 20, a backlight luminance adjustment unit 32, and a backlight 33. Since the RAM 11, the CPU 12, the liquid crystal drivers 14 and 15, and the liquid crystal panel 20 have the same configuration as in FIG. 1, detailed description thereof is omitted here.

  The backlight 33 has four light emitting areas 33A to 33D corresponding to each display area obtained by dividing the display screen of the liquid crystal panel 20 into four. The light emitting areas 33A to 33D are provided as backlights each having a light source for each of RGB colors of a red backlight, a green backlight, and a blue backlight. The backlight luminance adjusting unit 32 includes backlight luminance adjusting units 32A to 32D, and each of the light emitting areas 33A to 33D is controlled by the backlight luminance adjusting units 33A to 33D.

  With reference to FIGS. 11A and 11B, the backlight power consumption reduction effect in the liquid crystal display device shown in FIG. 10 will be described. In the following, in order to simplify the description, display control is exemplified on the assumption that the display screen is composed of 8 pixels (each pixel includes RGB color components).

  First, consider a case where display is performed with display data as shown in FIG. 11A when the display gradation is 256 gradations (0 to 255). Here, it is assumed that the display screen is divided into four areas, with two pixels as one area. In FIGS. 11A and 11B, the upper left two pixels are the region A, the upper right two pixels are the region B, the lower left two pixels are the region C, and the lower right two pixels are the region D.

  In the above display control, as shown in FIG. 11B, the luminance of the backlight is controlled so as to coincide with the maximum luminance value in the display data in each area A to D for each RGB color component. The The transmittance of the liquid crystal panel is adjusted according to the luminance of the backlight at that time. In the liquid crystal display device having the configuration shown in FIG. 10, the power consumption can be reduced more favorably for each color component of the RGB colors of the backlight than the liquid crystal display device shown in FIG.

  As described above, the liquid crystal display device according to the present embodiment divides the display screen of the liquid crystal panel 20 into a plurality of regions, and controls the transmittance of the liquid crystal panel and the luminance of the active backlight for each of the divided regions. Display control is performed based on the above. Next, a specific processing procedure for performing the transmittance of the liquid crystal panel and the luminance control of the active backlight based on the display data will be described.

  In the liquid crystal display device shown in FIG. 1 or 10, the transmittance of the liquid crystal panel and the luminance of the active backlight are set by the active BL controller 13. FIG. 12 shows the configuration of the active BL controller 13.

  As shown in FIG. 12, the active BL controller 13 includes an image area division unit 41, image memories 42A and 42B, maximum luminance extraction units 43A and 43B, maximum luminance storage units 44A and 44B, BL luminance calculation units 45A and 45B, liquid crystal Transmittance 46A, 46B is provided. Here, the component with the subscript A is a processing unit for the region A, and the component with the subscript B is a processing unit for the region B. Here, in order to simplify the description, the number of divisions of the display screen is two divisions of areas A and B.

  The image data input to the active BL controller 13 is first distributed for each corresponding area by the image data area dividing unit 41 and sent to the image memory 42A or 42B. Thus, when image data for one frame is input to the image memories 42A and 42B to the active BL controller 13, the image data corresponding to the areas A and B is distributed to the image memories 42A and 42B, respectively. And memorized.

  The maximum luminance extraction units 43A and 43B extract data indicating the maximum luminance value from the pixel data stored in the image memories 42A and 42B. The extracted maximum brightness value is stored in the maximum brightness storage units 44A and 44B.

  The BL luminance calculation units 45A and 45B determine the light emission luminance of the backlight in the corresponding region based on the maximum luminance value stored in the maximum luminance storage units 44A and 44B. Here, in the pixel having the maximum luminance value, the light emission luminance is set so that a desired display luminance can be obtained when the transmittance of the liquid crystal is 100%. The light emission luminance of the backlight set by the BL luminance calculating units 45A and 45B is output to the backlight luminance adjusting units 16A and 16B.

  The liquid crystal transmittance calculation units 46A and 46B calculate the transmittance for all the pixels in the region, and output the gradation value corresponding to the calculated transmittance to the liquid crystal drivers 14 and 15. The transmittance of each pixel is calculated by the following formula based on the backlight luminance in the corresponding region and the display data (that is, the input gradation value) of the pixel.

(Transmittance of pixel) = (Input gradation value of the pixel) / (Backlight luminance value)
Further, the gradation value corresponding to the calculated transmittance is calculated by the following equation.

(Tone value corresponding to transmittance) = (transmittance) × (maximum tone value)
In the above description, the brightness of the backlight is controlled so as to coincide with the maximum brightness value in the display data in each area. In this configuration, since the luminance in each light emitting region of the backlight can be set to the minimum luminance necessary for display, the effect of reducing the power consumption of the backlight can be further improved. In this case, the backlight needs to have the number of luminance gradations that matches the number of display gradations (if the number of display gradations is 256, the backlight needs to be able to adjust the luminance in 256 levels). .

  However, the liquid crystal display device according to the present invention is not limited to the above example, and the luminance gradation number of the backlight may be smaller than the display gradation number. For example, when the number of display gradations is 256, and the backlight can only be adjusted in brightness in four steps (levels 1 to 4 in dark order), the maximum display gradation in the region is 0 to 63. It is conceivable that the backlight brightness is set to level 1, level 2 is set to 64 to 127, level 3 is set to 128 to 191 and level 4 is set to 192 to 255.

  The processing function for image collation described above is realized by a program. In the second embodiment, this program is stored in a computer-readable recording medium.

  In the present embodiment, as the recording medium, a memory necessary for processing performed by the computer shown in FIG. 1, for example, the RAM 11 itself may be a program medium. The recording medium may be a recording medium that is detachably attached to an external storage device, and a program recorded therein can be read via the external storage device. Examples of such external storage devices include magnetic tape devices, FD drive devices, and CD-ROM drive devices (not shown), and examples of recording media include magnetic tape, FD, and CD-ROM (not shown). It is. In any case, the program recorded in each recording medium may be configured to be accessed and executed by the CPU 12, or in any case, the program is once read from the recording medium and stored in a predetermined program storage. An area, for example, a program storage area of the RAM 11 may be loaded and read by the CPU 12 to be executed. This loading program is assumed to be stored in advance in the computer.

  Here, the above-described recording medium is configured to be separable from the computer main body. As such a recording medium, a medium that carries a program in a fixed manner can be applied. Specifically, tape systems such as magnetic tape and cassette tape, magnetic disks such as FD and fixed disk, and optical disks such as CD-ROM / MO (Magnetic Optical Disc) / MD (Mini Disc) / DVD (Digital Versatile Disc) Semiconductor systems such as disk systems, card systems such as IC cards (including memory cards) / optical cards, mask ROM, EPROM (Erasable and Programmable ROM), EEPROM (Electrically EPROM), flash ROM, etc. are applicable. In addition, the recording medium may be a recording medium in which the program is downloaded from the communication network and fluidly carried. When a program is downloaded from a communication network, the download program may be stored in advance in the computer main body, or may be installed in advance in the computer main body from another recording medium.

  Note that the content stored in the recording medium is not limited to a program, and may be data.

  In the description of the above embodiment, the case where the present invention is applied to a liquid crystal display is described. However, the present invention can be applied to a transmissive display in general by the same method.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1, showing an embodiment of the present invention, is a block diagram illustrating a main configuration of a liquid crystal display device. FIG. 2A is a diagram showing an example of display data in the liquid crystal display device shown in FIG. 1, and FIG. 2B is a diagram showing the transmittance of the liquid crystal when performing display based on the above display data example. It is a figure which shows the brightness | luminance of a backlight. It is a figure which shows the example of a division | segmentation of the display area in a liquid crystal panel, and the light emission area | region in an active backlight. It is a timing chart which shows the relationship between the brightness | luminance change timing of a backlight, and the transmittance | permeability change timing of a liquid crystal. It is a timing chart which shows the relationship between the brightness | luminance change timing of a backlight, and the transmittance | permeability change timing of a liquid crystal. It is a timing chart which shows the relationship between the brightness | luminance change timing of a backlight, and the transmittance | permeability change timing of a liquid crystal. It is a timing chart which shows the relationship between the brightness | luminance change timing of a backlight, and the transmittance | permeability change timing of a liquid crystal. FIG. 8A is a diagram showing an arrangement example of fluorescent tubes in a backlight using the fluorescent tube, and is a diagram showing an example of display data. FIG. 8B corresponds to the arrangement example of the fluorescent tubes. It is a figure which shows the example of a division | segmentation of the area | region of the backlight to perform. It is a figure which shows the example of arrangement | positioning of LED in the backlight using LED, and the division | segmentation example of an area | region. 1, showing an embodiment of the present invention, is a block diagram illustrating a main configuration of a liquid crystal display device. FIG. FIG. 11A is a diagram showing an example of display data in the liquid crystal display device shown in FIG. 10, and FIG. 11B is a diagram showing the transmittance of the liquid crystal when displaying based on the above display data example. It is a figure which shows the brightness | luminance of a backlight. It is a block diagram which shows the structure of the active BL controller in the said liquid crystal display device. It is sectional drawing which shows the general structure of a transmissive liquid crystal display device. It is a block diagram which shows the principal part structure of the conventional liquid crystal display device using an active backlight. FIG. 15A is a diagram showing an example of display data in the liquid crystal display device, and FIG. 15B is a diagram in the case of performing display based on the above display data example in the liquid crystal display device not using the active backlight. FIG. 15C is a diagram showing the display of the conventional liquid crystal display device using the active backlight based on the above display data example. It is a figure which shows the transmittance | permeability of a liquid crystal, and the brightness | luminance of a backlight.

Explanation of symbols

11 RAM
12 CPU
13 Active BL controller (light emission luminance setting means, transmittance setting means)
14, 15 Liquid crystal driver 16 Backlight brightness adjustment unit 17 Backlight 20 Liquid crystal panel (transmission control panel)
32 Backlight luminance adjustment unit 33 Backlight 41 Image data area division unit 42 Image memory 43 Maximum luminance extraction unit 44 Maximum luminance storage unit 45 BL luminance calculation unit (light emission luminance setting means)
46 Liquid crystal transmittance calculator (transmittance setting means)

Claims (13)

  A backlight having a plurality of light emitting regions each capable of controlling light emission luminance.   2. The backlight according to claim 1, wherein the plurality of light emitting areas have different voltage input systems of light sources existing in the respective light emitting areas.   2. The backlight according to claim 1, wherein the plurality of light emitting areas have different input systems of control signals for controlling a light emission period of a light source existing in each of the light emitting areas. In a transmissive display device that includes a backlight and a transmission control panel, and displays the irradiation light from the backlight by controlling the transmittance with the transmission control panel.
The backlight has a plurality of light emitting areas each capable of controlling the light emission luminance,
Light emission luminance setting means for setting the light emission luminance in each light emission region of the backlight;
A transmissive display device, comprising: a transmittance setting means for setting a transmittance of a pixel in the transmission control panel according to a light emission luminance value for each light emitting region of the backlight.   5. The transmissive display device according to claim 4, wherein a change timing of the light emission luminance in each of the light emitting regions is made coincident with a head of a pixel rewriting period in each light emitting region.   6. The transmissive display apparatus according to claim 5, wherein a period during which no pixel is rewritten is provided in one frame period.   5. The transmissive display device according to claim 4, wherein the light emitting area is turned off during the pixel rewriting period corresponding to each light emitting area, and the backlight luminance of the light emitting area is changed when the pixel rewriting is completed. .   The transmissive display device according to claim 4, wherein the backlight includes a white light source.   5. The transmissive display device according to claim 4, wherein the backlight includes a light source for each color of RGB, and the light emission luminance value can be controlled for each color of RGB.   5. The transmissive display device according to claim 4, wherein a light emission luminance value for each light emitting region of the backlight is made to coincide with a maximum display luminance value in each light emitting region.   The transmissive display device according to claim 4, wherein the transmissive control panel is a liquid crystal panel. In a display control method for a transmissive display device, which includes a backlight and a transmission control panel, and displays the irradiation light from the backlight by controlling the transmittance by the transmission control panel.
The backlight has a plurality of light emitting areas each capable of controlling the light emission luminance,
A first step of setting light emission luminance in each light emission region of the backlight;
A second step of setting the transmittance of the pixels in the transmission control panel according to the light emission luminance value for each light emitting region of the backlight set in the first step;
A third step of displaying an image based on the light emission luminance value for each light emitting area of the backlight set in the first step and the transmittance of the pixel set in the second step. And a control method for the transmissive display device.   A display control program for causing a computer to execute each step of the backlight control method for a transmissive display according to claim 12.

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