JP2011099961A - Display device, display method, display program, and computer-readable recording medium - Google Patents

Abstract

An object of the present invention is to control driving of a light source and prevent a change in hue of an image to be displayed.
A liquid crystal display device (1) changes an emission rate of LEDs (52r, 52g, 52b) corresponding to an image frame displayed on the LCD panel (60), a storage unit (25) for storing color correction parameters, and an image displayed on the LCD panel (60). When the light emission rate calculation unit 32, the state detection unit 11 that detects a change in the light emission rate of the LEDs 52r, 52g, and 52b, and the state detection unit 11 perform the above detection, the LED 52r, 52g, and the light emission rate calculation unit 32 have changed. The correction rate acquisition unit 12 that acquires the correction rate of the color correction parameter stored in the storage unit 25 from the mix rate or offset of 52b, the correction rate of the color correction parameter acquired by the correction rate acquisition unit 12, and the storage unit 25 A color correction parameter calculation unit 22 for calculating a color correction parameter of the frame after the change in the light emission rate from the color correction parameters stored in Eteiru.
[Selection] Figure 1

Description

  The present invention relates to a display device that controls driving of a light source by an image signal of an image to be displayed.

  Generally, a backlight is used as a light source for illuminating a liquid crystal display panel in a liquid crystal display device. However, even when optimal color correction is performed on the liquid crystal display panel side, when the type of backlight changes, there is a problem that the color of the liquid crystal display panel changes depending on the color of the backlight.

  Patent Document 1 discloses a liquid crystal display device including a color LCD and a backlight composed of a fluorescent lamp.

  The liquid crystal display device described in Patent Document 1 is provided with a sensor for detecting the color temperature of the backlight on the back side of the color LCD and within the illumination range of the backlight. The liquid crystal display device of Patent Document 1 obtains the three primary color signals R, G and B of the backlight from the color temperature of the backlight detected by the sensor, and adjusts the white balance of the color LCD based on this signal. Yes. Thereby, it is possible to improve the accuracy of color correction in a liquid crystal display device in which a fluorescent lamp is used as the backlight and the illumination area of the backlight is not divided.

  In recent years, in order to reduce the power consumption of the backlight, a driving method for controlling the luminance of the entire backlight by an image signal displayed on the display panel has been developed. In the following description, such a driving method is referred to as active driving. As a light source of an active drive backlight, an LED combining white or three colors of red (R), green (G), and blue (B) is used.

  In order to further reduce power consumption, backlights have been developed in which the backlight is divided into a plurality of areas and the LEDs arranged in the divided areas are individually controlled. . In the following description, such a driving method is referred to as area active driving.

  Patent Document 2 discloses a liquid crystal display device in which at least one LED for illuminating a liquid crystal display panel is arranged for each of a plurality of divided regions. And according to a video signal, LED of the area | region which needs illumination is controlled for every division area. Thereby, the power consumption required for illumination is controlled.

  Patent Document 3 discloses a liquid crystal display device in which a liquid crystal display panel is divided into a plurality of regions, and a plurality of LEDs are arranged in a backlight so as to illuminate each of the divided regions. And the liquid crystal display device of patent document 2 controls the brightness | luminance of the light of a light emitting diode by the peak gradation value of each area | region of the divided | segmented liquid crystal display panel. This makes it possible to control the brightness locally.

  Further, as in Patent Documents 2 and 3, when the backlight is used for an LED, a combination of three colors of R, G, and B can be used for the LED. And, for example, when only red is displayed in the display area of the image on the display panel, only the red light of the backlight is emitted. It can also be changed. In this way, by independently driving and controlling the LEDs for each color, it is possible to reproduce a high color gamut while reducing power consumption.

JP 63-261327 A (published October 28, 1988) JP 2001-142409 A (released May 25, 2001) JP 2005-338857 A (released on December 8, 2005) JP 2006-304149 A (published on November 2, 2006) JP 2007-228240 A (published on September 6, 2007) JP 2008-99170 A (published April 24, 2008) Japanese Patent Application No. 2008-239924

  However, since Patent Document 1 does not control the luminance of the backlight, the power consumption cannot be reduced.

  In Patent Documents 2 and 3, since driving of the backlight is controlled, power consumption can be reduced. However, the method for controlling the driving of the backlight as described above has the following problems.

  FIG. 12 is a diagram illustrating a state of a display image divided into a plurality of display areas.

  13A shows the aperture ratio of the LDC panel that displays the display area a in FIG. 12 and the light emission amount of each RGB-LED that illuminates the display area a, and FIG. 13B shows the display in FIG. It is the schematic showing the mode of the aperture ratio of the LDC panel which displays the area b, and the light emission amount of each RGB-LED which illuminates the display area b. 14A shows the effect of crosstalk between electrodes of the LCD panel of FIG. 13A, and FIG. 14B shows the effect of crosstalk between electrodes of the LCD panel of FIG. 13B. Yes.

  As shown in FIG. 12, a background image 120 is displayed in the display areas a and b. The gradation of the background image 120 is set to R, G, B = 50, 30, and 30 for both the display area a and the display area b. A white circle image 121 is displayed in the display area b.

  FIG. 13A shows pixels aR, aG, and aB that display the background image 120 of the display area a and the respective aperture ratios (liquid crystal transmittances) in the upper row, and R− that illuminates the display area a in the lower row. LED, G-LED, B-LED and the respective light emission amounts are shown. FIG. 13B shows the pixels bR, bG, and bB that display the background image 120 of the display area b and the respective aperture ratios in the upper stage, and the R-LEDs and G- that illuminate the display area b in the lower stage. LED, B-LED and the light emission amount of each are shown.

  The pixels aR and bR are pixels provided with a red color filter. The pixels aG and bG are pixels provided with a green color filter. The pixels aB and bB are pixels provided with a blue color filter.

  The background image 120 in FIG. 12 has the same color in the display area a and the display area b. However, since the white circle image 121 is displayed in the display area b, the light emission amount of each LED in the display area b is larger than the light emission amount of each LED in the area A. For this reason, the aperture ratio of the pixel displaying the background image 120 is different between the display area a and the display area b.

  As shown in FIG. 13 (a), in the display area a, the aperture ratios of the pixels aR, aG, and aB of the LCD panel are 100, 100, and 100, and the R-LED, G-LED, and B-LED emit light. The amount is 50, 30, and 30. As shown in FIG. 13B, in the display area b, the aperture ratios of the pixels bR, bG, and bB of the LCD panel are 50, 30, and 30, and R-LED, G-LED, and B-LED. Is set to 100, 100, 100. Note that the upper limit of the aperture ratio of the pixels of the LCD panel is 100.

  However, when the aperture ratios of the pixels are different, the aperture ratios are substantially different between adjacent pixels due to crosstalk between electrodes.

  As an example, a case where 10% of the aperture ratio is affected by the crosstalk between the electrodes between adjacent pixels (that is, the 10% aperture ratio increases) will be described.

  As shown in FIG. 14A, in the display area a, since the aperture ratio of each pixel aR / aG of the LCD panel is large, the influence of crosstalk between electrodes is large between adjacent pixels. However, since the pixel aG has an upper limit of 100 for the aperture ratio, the aperture ratio does not increase even if the influence from the pixel aR due to crosstalk between the electrodes is 10%. On the other hand, as shown in FIG. 14B, in the display area b, since the aperture ratio of each pixel bR / bG of the LCD panel is small, the influence of crosstalk between electrodes is small between adjacent pixels. However, the pixel bG in the display area b has an aperture ratio of 35 due to the influence of the pixel aR, and the aperture ratio increases. Thus, the display area a and the display area b have different rates of increasing the aperture ratio between adjacent pixels.

  As described above, the display area a and the display area b include the background image 120 having the same gradation, but the R-LED, G-LED, and B-LED have different light emission rates in the respective areas. The aperture ratios of the pixels in the respective regions are different, and thus the color components of the background image 120 in the respective regions that are actually displayed are different.

  For this reason, when the optimal color correction is performed before the white circle image 121 of the display area b is displayed, when the white circle image 121 is displayed in the display area b, the display area b is This will deviate from the optimum color correction value.

  This is the same even when white (W) LEDs are used instead of the R-LEDs, G-LEDs, and B-LEDs.

  15A shows the aperture ratio of the LDC panel that displays the display area a in FIG. 12 and the light emission amount of the W-LED that illuminates the display area a, and FIG. 15B shows the display area in FIG. It is the schematic showing the aperture ratio of the LDC panel which displays b, and the mode of the emitted light amount of W-LED which illuminates the display area b. 16A shows the influence of crosstalk between the electrodes of the LCD panel of FIG. 15A, and FIG. 16B shows the influence of crosstalk between the electrodes of the LCD panel of FIG. 15B. Yes.

  As shown in FIG. 15A, in the display area a, the aperture ratios of the pixels aR, aG, and aB of the LCD panel are 100, 60, and 60, and the light emission amount of the W-LED is 50. 15B, in the display area b, the aperture ratios of the pixels bR, bG, and bB of the LCD panel are 50, 30, and 30, and the light emission rate of the W-LED is 100.

  Similarly, when adjacent pixels are affected by 10% (+10) of the aperture ratio due to crosstalk between electrodes, as shown in FIG. 16A, in the display area a, the pixel aG is the pixel aR. In effect, the aperture ratio is 70%. Also, as shown in FIG. 16B, in the display area b, the pixel bG is affected by 10% (+5) of the aperture ratio of the pixel bR, and the aperture ratio is actually 35%.

  As described above, even when the W-LED is used, the display area a and the display area b have different rates of increase in the aperture ratio between adjacent pixels.

  Further, the same applies when the backlight is driven actively. For example, assuming that the display area a in FIG. 12 is the first frame image displayed on the entire display screen and the display area b is the next second frame image, the first frame image and the second frame Even when the background image 120 of the same gradation is displayed with the image, the white frame image 121 is displayed with the second frame image, so that the light emission rate of the backlight differs, and the aperture of each pixel of the LED The rate will be different. For this reason, the first frame image and the second frame image are different in the influence of the increase in the aperture ratio exerted between the adjacent pixels of the LCD. Therefore, in the case of the first frame image, optimum color correction is performed. If it has been performed, the second frame image deviates from the optimum color correction value.

  As described above, in the backlight that performs active driving and area active driving, the color of the displayed image is actually different before and after changing the light emission rate of the backlight.

  The present invention has been made in view of the above problems, and an object of the present invention is to control driving of a light source and to prevent a change in color of an image to be displayed.

  In order to solve the above problems, a display device of the present invention includes a display panel capable of displaying an image and a light source that illuminates the display panel, and the light source is an image of an image displayed on the display panel. A display device that changes a light emission rate of the light source in response to a signal, a storage unit that stores a correction value for color correction of the image signal, and a light emission rate of the light source in correspondence with the image signal. A light emission rate changing means for changing, a detection means for detecting that the light emission rate changing means has changed the light emission rate of the light source, and a change in the light emission rate when the detection means detects a change in the light emission rate of the light source. Correction rate acquisition means for acquiring the correction rate of the correction value of the color correction stored in the storage unit from the amount of change in the light emission rate of the light source changed by the means, and the color acquired by the correction rate acquisition means Correction rate of correction and the above memory Color correction calculation means for calculating a color correction correction value of the image signal after the light emission rate changing means changes the light emission rate of the light source from the stored correction value of the color correction. It is characterized by having.

  In order to solve the above problems, a display method of the present invention includes a display panel capable of displaying an image, and illuminating the display panel with light corresponding to an image signal of the image displayed on the display panel. A display method comprising: a light source that changes a rate; and a storage step that stores a correction value for color correction of the image signal; A light emission rate change step for changing the light emission rate of the light source, a detection step for detecting that the light emission rate of the light source has been changed in the light emission rate change step, and a change in the light emission rate of the light source is detected in the detection step. Then, a correction rate acquisition step of acquiring a correction rate of the correction value of the color correction stored in the storage step from the amount of change in the light emission rate of the light source changed in the light emission rate change step, and the correction rate acquisition The image signal after the light emission rate of the light source is changed in the light emission rate changing step from the color correction correction rate acquired in the step and the color correction correction value stored in the storage step. And a color correction calculation step for calculating a correction value for the color correction.

  With the above configuration, the light emission rate changing means changes the light emission rate of the light source corresponding to the image signal of the image to be displayed on the display panel. Therefore, the optimal light emission rate of the light source is set for each image signal. The drive can be controlled. And if the said light emission rate change means changes the light emission rate of the said light source, the said detection means will detect the change of the light emission rate of the said light source.

  When the detection unit detects a change in the light emission rate of the light source, the correction rate acquisition unit calculates the color stored in the storage unit from the amount of change in the light emission rate of the light source changed by the light emission rate change unit. Get the correction rate of the correction value.

  The color correction calculation means is configured such that the light emission rate change means emits light from the light source based on the color correction correction rate acquired by the correction rate acquisition means and the color correction correction value stored in the storage unit. A correction value for color correction of the image signal after changing the rate is calculated.

  For this reason, among the image signals of the image to be displayed on the display panel, the color correction of the image signal after the light emission rate changing means has changed the light emission rate can be performed. Thereby, the drive of a light source can be controlled and the change of the hue of the image displayed can be prevented.

  Furthermore, the light source is divided into a plurality of regions, the storage unit stores a correction value for color correction of the image signal for each of the plurality of regions, and the light emission rate changing means includes the plurality of regions. Each time, the light emission rate of the light source is changed corresponding to the image signal, and the detection means changes the light emission rate of the light source in at least one of the plurality of regions. When the detection means detects a change in the light emission rate of the light source, the correction rate acquisition means detects the light emission rate of the light source in the region where the light emission rate change means has changed the light emission rate. The correction rate of the correction value of the color correction corresponding to the area stored in the storage unit is acquired from the amount of change, and the color correction calculation unit is the correction rate of the color correction acquired by the correction rate acquisition unit. And stored in the storage unit And a correction value of the color correction corresponding to the region, after which the emission ratio change means the region has changed the emission rate of the light source, it is preferable to calculate a correction value for color correction of the image signal.

  With the above configuration, the storage unit stores a correction value for color correction of the image signal for each of the plurality of regions. And the said light emission rate change means changes the light emission rate of the said light source corresponding to the said image signal for every said some area | region. In addition, the detection unit detects that the light emission rate changing unit has changed the light emission rate of the light source in at least one of the plurality of regions.

  When the detection means detects a change in the light emission rate of the light source, the correction rate acquisition means obtains the storage unit from the amount of change in the light emission rate of the light source in the region where the light emission rate change means has changed the light emission rate. The correction rate of the correction value of the color correction corresponding to the area stored in the above is acquired.

  Then, the color correction calculation unit calculates the color correction correction rate acquired by the correction rate acquisition unit and the color correction correction value corresponding to the region stored in the storage unit. A light emission rate changing means calculates a correction value for color correction of the image signal after the light emission rate of the light source is changed.

  For this reason, among the image signals of the image displayed on the display panel, color correction of the image signal is performed for each of the plurality of regions when the light emission rate changing unit changes the light emission rate for each of the plurality of regions. be able to. For this reason, it is possible to control the driving of the light source for each of the plurality of areas and to prevent a change in the hue of the image to be displayed for each of the plurality of areas.

  Further, when the detection means detects a change in the light emission rate of the light source, the correction rate acquisition means calculates the amount of change in the light emission rate of the light source changed by the light emission rate change means into the storage unit by calculation. It is preferable to obtain the correction rate of the stored color correction correction value.

  With the above configuration, the correction rate acquisition unit acquires the amount of change in the light emission rate of the light source changed by the light emission rate change unit, thereby correcting the correction rate of the correction value of the color correction stored in the storage unit. Can be obtained by calculation. For this reason, the color correction calculation unit performs color correction of the image signal after the light emission rate changing unit changes the light emission rate, using the correction rate acquired by the correction rate acquisition unit. Can do.

  In addition, the storage unit stores a change amount of the light emission rate of the light source and a correction rate of the correction value of the color correction in association with each other, and the detection unit detects a change in the light emission rate of the light source. Then, it is preferable that the correction rate acquisition unit acquires the correction rate of the color correction associated with the amount of change in the light emission rate of the light source changed by the light emission rate change unit from the storage unit.

  When the amount of change in the light emission rate of the light source changed by the light emission rate changing means is acquired with the above configuration, the correction rate for the color correction corresponding to the acquired amount of change is acquired from the storage unit. Accordingly, the color correction calculation unit performs color correction of the image signal after the light emission rate changing unit changes the light emission rate, using the correction rate acquired by the correction rate acquisition unit from the storage unit. be able to.

  The above may be realized by a computer. In this case, a display program for realizing the above in the computer by operating the computer as each of the above means and a computer-readable recording medium recording the display program are also included in the category of the present invention.

  The display device of the present invention includes a display panel capable of displaying an image and a light source that illuminates the display panel, and the light source corresponds to an image signal of an image displayed on the display panel, and A storage unit that changes a light emission rate and stores a correction value for color correction of the image signal; a light emission rate change unit that changes a light emission rate of the light source corresponding to the image signal; and the light emission rate change unit. Detection means for detecting that the light emission rate of the light source has changed, and when the detection means detects a change in the light emission rate of the light source, the amount of change in the light emission rate of the light source changed by the light emission rate change means The correction rate acquisition means for acquiring the correction rate of the correction value of the color correction stored in the storage unit, the correction rate of the color correction acquired by the correction rate acquisition unit, and the storage unit From the correction value of the color correction, Rate change means comprises in the case of changing the light emission rate of the light source, and a color correction calculation means for calculating a correction value for color correction of the image signal.

  The display method of the present invention includes a display panel that can display an image, and a light source that illuminates the display panel with light and changes the light emission rate in response to an image signal of the image displayed on the display panel. A display method for displaying the image on a display device, a storage step for storing a correction value for color correction of the image signal, and a light emission rate change for changing the light emission rate of the light source corresponding to the image signal A detection step for detecting that the light emission rate of the light source has been changed in the light emission rate change step; and a change in the light emission rate change step when a change in the light emission rate of the light source is detected in the detection step. The correction rate acquisition step of acquiring the correction rate of the correction value of the color correction stored in the storage step from the change amount of the light emission rate of the light source, and the color correction acquired in the correction rate acquisition step. The correction value for the color correction of the image signal after the light emission rate of the light source is changed in the light emission rate change step is calculated from the correction rate of the color and the color correction correction value stored in the storage step. And a color correction calculation step.

  For this reason, it is possible to control the driving of the light source and to prevent a change in the hue of the displayed image.

It is a block diagram showing the structure of the liquid crystal display device concerning the 1st Embodiment of this invention. It is a top view showing the structure of the backlight of the said liquid crystal display device. (A) is a figure showing the mode of the luminous rate of the LED when the mix rate is 0, (b) is the diagram showing the mode of the luminous rate of the LED when the mix rate is 0.4, ( c) is a diagram showing the state of the light emission rate of the LED when the mix rate is 1. FIG. (A) is a figure showing the mode of the light emission rate of LED when an offset is 0, (b) is a figure showing the mode of the light emission rate of LED when an offset is 30%. It is the schematic showing a mode that the light emitted from LED permeate | transmits a color filter. It is a figure showing the relationship between the permeation | transmission wavelength of each color filter of RGB, and the light emission wavelength of each LED of RGB. It is a figure explaining the mode of the light leakage between the illumination areas showing the mode of the display screen of a liquid crystal display device. It is a figure explaining the flow of a process of the liquid crystal display device which concerns on the 1st Embodiment of this invention. It is a flowchart showing the flow of a process of the liquid crystal display device of this invention. It is a figure showing the area | region for calculating the correction rate of a color correction parameter. It is a figure explaining the flow of a process of the liquid crystal display device which concerns on the 2nd Embodiment of this invention. It is a figure showing the mode of the display image divided | segmented into the several display area. (A) represents the aperture ratio of the LDC panel that displays the display area a in FIG. 12 and the light emission amount of each RGB-LED that illuminates the display area a, and (b) represents the display area b in FIG. It is the schematic showing the mode of the aperture ratio of the LDC panel which displays LED, and the mode of the light emission amount of each RGB-LED which illuminates the display area b. (A) represents the influence of the crosstalk between the electrodes of the LCD panel shown in FIG. 13 (a), and (b) represents the influence of the crosstalk between the electrodes of the LCD panel shown in FIG. 13 (b). (A) represents the aperture ratio of the LDC panel that displays the display area a in FIG. 12 and the light emission amount of the W-LED that illuminates the display area a, and (b) represents the display area b in FIG. It is the schematic showing the opening ratio of the LDC panel to display, and the mode of the emitted light amount of W-LED which illuminates the display area b. (A) represents the influence of the crosstalk between the electrodes of the LCD panel shown in FIG. 15 (a), and (b) represents the influence of the crosstalk between the electrodes of the LCD panel shown in FIG. 15 (b).

[Embodiment 1]
Hereinafter, the first embodiment of the present invention will be described in detail.

(Configuration of the liquid crystal display device 1)
FIG. 1 is a block diagram showing a configuration of a liquid crystal display device 1 according to the present embodiment.

  As shown in FIG. 1, the liquid crystal display device 1 (display device) includes a control unit 10, a video processing unit 20, a storage unit 25, an active processing unit 30, a backlight driving unit 42, and an LCD panel driving unit. 41, a backlight 50, and an LCD panel 60 (display panel).

  The control unit 10 includes a state detection unit 11 (detection unit) and a correction rate acquisition unit 12 (correction rate acquisition unit). The video processing unit 20 includes a color correction unit 21 including a color correction parameter calculation unit 22 (color correction calculation unit) and an image data calculation unit 23. The active processing unit 30 includes an LCD aperture ratio calculation unit 31 and a light emission rate calculation unit 32 (light emission rate changing means).

  The video processing unit 20 performs various signal processing on the input RGB video signal. When the video processing unit 20 acquires an RGB video signal via an external receiving antenna, the video processing unit 20 extracts an image signal (frame) from the acquired RGB video signal at regular time intervals. Then, the video processing unit 20 adjusts the size of the extracted image signal. In addition, the video processing unit 20 appropriately performs color space conversion processing, scaling processing, synchronization detection processing, gamma correction processing, and OSD (On-Screen Display) display processing as various signal processing. Then, the video processing unit 20 outputs various types of information such as the size of the adjusted image and the gradation of the image signal calculated by the color correction unit 21 to the active processing unit 30.

  The color correction unit 21 performs color correction on the image signal extracted by the video processing unit 20 and calculates the gradation of the image displayed on the LCD panel 60.

  Here, the color correction is to perform image quality adjustment of an image displayed on the LCD panel 60. Among image quality adjustments, one of the methods for adjusting the color system is a method for adjusting three color attributes. The three attributes of color are “saturation”, “luminance (lightness)”, and “hue”. In the present invention, correction using at least one of “saturation”, “luminance (brightness)”, and “hue” as a parameter is referred to as color correction. “Saturation”, “luminance (lightness)”, and “hue” are three independent elements. A typical example is the Munsell color system, which is widely used as a standard for object colors. Further, as a method for performing color correction using these “saturation”, “luminance (brightness)”, and “hue” as parameters, for example, methods disclosed in Patent Documents 4 to 6 can be used. In the present embodiment, the correction amounts (correction values) of the three color attributes “saturation”, “luminance (brightness)”, and “hue” are referred to as color correction parameters.

  When the correction rate of the correction amount (color correction parameter) for color correction is acquired from the correction rate acquisition unit 12, the color correction parameter calculation unit 22 acquires the initial value of the color correction parameter stored in the storage unit 25, In the LCD panel 60 when the light emission rate of a light source such as an LED arranged in the backlight 50 changes from the correction rate of the acquired color correction parameter and the initial value of the color correction parameter acquired from the storage unit 25. A color correction parameter corresponding to the frame of the image to be displayed is calculated.

  The image data calculation unit 23 calculates the gradation of the frame of the image displayed on the LCD panel 60 using the frame extracted by the video processing unit 20 and the color correction parameter calculated by the color correction parameter calculation unit 22. Then, the image data calculation unit 23 outputs a frame (gradation data) obtained by calculating the gradation to the active processing unit 30.

  The storage unit 25 stores initial values of color correction parameters and corrected color correction parameters. Further, the correction rate of the color correction parameter associated with the mix rate (details will be described later) or the offset (details will be described later) calculated by the light emission rate computation unit 32 may be stored.

  The active processing unit 30 acquires the gradation data of the frame assigned by the image data calculation unit 23. The light emission rate calculating unit 32 calculates the light emission rate of a light source such as an LED disposed in the backlight 50 from the frame gradation acquired by the active processing unit 30.

  The light emission rate calculation unit 32 calculates the light emission rate of each light source of the backlight 50. Then, the light emission rate calculation unit 32 feeds back the calculated light emission rate of each light source (that is, the color component information of the light source) to the correction rate acquisition unit 12 of the control unit 10, and the correction rate acquisition unit 12 receives the correction rate of the color correction parameter. Is to get.

  The light emission rate calculation unit 32 calculates a mix rate (details will be described later) or an offset (details will be described later) for each frame from the gradation data of the frames acquired by the active processing unit 30. Then, the light emission rate calculation unit 32 calculates the light emission rate of a light source such as an LED disposed in the backlight 50 from the calculated mix rate or offset and the gradation data acquired by the active processing unit 30. Then, the light emission rate calculation unit 32 outputs the calculated light emission rate of the light source to the LCD aperture ratio calculation unit 31 and also outputs it to the backlight drive unit 42 to control the light emission rate of the backlight 50 for each frame. Let Further, the light emission rate calculation unit 32 outputs the calculated mix rate or offset to the state detection unit 11 and the correction rate acquisition unit 12.

  The LCD aperture ratio calculation unit 31 uses the gradation data acquired by the active processing unit 30 and the light emission rate of a light source such as an LED arranged in the backlight 50 calculated by the light emission rate calculation unit 32 for each frame. The aperture ratio of each subpixel of the LCD panel 60 is calculated. Then, the LCD aperture ratio calculation unit 31 outputs the calculated aperture ratio of each subpixel of the LCD panel 60 to the LCD panel drive unit 41, thereby calculating the aperture ratio of each subpixel of the LCD panel 60 for each frame. Let me control.

  The LCD panel drive unit 41 acquires the aperture ratio of each subpixel of the LCD panel 60 output from the LCD aperture ratio calculation unit 31. Then, the LCD panel drive unit 41 generates source and gate drive data for driving the LCD panel 60 from the aperture ratio of each sub-pixel of the LCD panel 60, and drives and controls the LCD panel 60.

  The backlight drive unit 42 acquires the light emission rate of the LED output from the light emission rate calculation unit 32. And the backlight drive part 42 produces | generates the drive data of each LED of the backlight 50 from the acquired light emission rate of LED, and drives each LED.

  The control unit 10 includes a microcomputer and controls the entire liquid crystal display device 1 by controlling each unit included in the liquid crystal display device 1.

  When the light emission rate calculation unit 32 calculates a mix rate, an offset, or the like, the state detection unit 11 detects whether or not the light emission rate of the light source of the backlight 50 has been changed based on the calculation result.

  The correction rate acquisition unit 12 calculates the color correction parameter repair rate and feeds back the acquired correction rate to the color correction parameter calculation unit 22 so that the color correction parameter calculation unit 22 calculates the optimum color correction parameter. It is something to be made.

  The correction rate acquisition unit 12 determines the correction rate of the initial value of the color correction parameter from the mix rate or offset acquired from the light emission rate calculation unit 32 when the state detection unit 11 detects a change in the light emission rate of the light source of the backlight 50. And the calculation result is output to the color correction parameter calculation unit 22.

  Alternatively, when the correction rate acquisition unit 12 detects a change in the light emission rate of the light source of the backlight 50, the correction rate of the initial value of the color correction parameter associated with the mix rate or offset acquired from the light emission rate calculation unit 32 May be acquired from the storage unit 25, and the acquired correction rate may be output to the color correction parameter calculation unit 22.

  The LCD panel 60 has pixels arranged in a matrix. Each pixel is provided with a sub-pixel (sub-pixel) provided with a color filter that transmits red (R), green (G), and blue (B) light. The LCD panel 60 has a display surface capable of displaying an image. Note that the number of colors of the color filter arranged in the sub-pixel is not limited to the above-described three colors, and may be two colors or four colors, for example.

  The backlight 50 is disposed on the back surface (surface opposite to the image display surface) of the LCD panel 60. The backlight 50 irradiates the LCD panel 60 with light from the back side of the LCD panel 60.

  FIG. 2 is a plan view illustrating the configuration of the backlight 50.

  As shown in FIG. 2, the backlight 50 is divided into a plurality of areas 51 (regions). For each area 51, an LED 52 r that emits red (R) color light and a green (G) light source. An LED 52g that emits colored light and an LED 52b that emits blue (B) colored light are arranged. Each of the LEDs 52r, 52g, and 52b can be independently driven and controlled (referred to as independent driving). The LEDs 52r, 52g, and 52b, which are the light sources of the backlight 50, change the light emission rate in accordance with the gradation of the frame of the image displayed on the LCD panel 60. In the present embodiment, description will be made assuming that the backlight 50 is subjected to active drive control.

  Instead of the LEDs 52r, 52g, and 52b, LEDs that emit white (W) color light may be provided. Furthermore, if the light emission rates of the LEDs 52r, 52g, and 52b are the same, the colors are mixed to become white light, so that the light emission rates of the LEDs 52r, 52g, and 52b in each area 51 are the same (the LEDs 52r, 52g, and 52b are It may be driven (white driving) as a white light source.

  Note that the number of emission colors of the LEDs 52r, 52g, and 52b is not limited to the above-described three colors, and may be two colors or four colors, for example. Further, the number of LEDs 52r, 52g, 52b arranged in each area 51 is not limited to one each, and a plurality of LEDs may be arranged.

  Next, a method for changing the ratio of the light emission rates of the LEDs 52r, 52g, and 52b when the backlight 50 is actively driven will be described. As a method of changing the ratio of the light emission rates of the LEDs 52r, 52g, and 52b, a method of changing the light emission rate by calculating a mix rate (light emission rate change amount) and an offset (light emission rate change amount) are mainly used. And a method of changing the light emission rate by calculating.

  Even when the backlight 50 is area-active driven, the ratio of the light emission rates of the LEDs 52r, 52g, and 52b can be changed for each area 51 in the same manner.

  Whether to change the light emission rate of the LEDs 52r, 52g, and 52b by calculating the mix rate or to change the light emission rate of the LEDs 52r, 52g, and 52b by calculating the offset depends on the important parameter in the displayed image. Selected.

(Mix rate)
First, the mix rate will be described.

  FIG. 3A is a diagram illustrating a state of the light emission rate of the LED when the mix rate is 0, and FIG. 3B is a diagram illustrating a state of the light emission rate of the LED when the mix rate is 0.4. (C) is a figure showing the mode of the light emission rate of LED in case a mix rate is 1. FIG.

  The mix rate is a ratio when changing the light emission rate of each of the LEDs 52r, LED52g, and LED52b, and is calculated by the light emission rate calculation unit 32.

The mix rate is calculated by the following formula.
rm = (r2-r1) * m + r1
gm = (g2−g1) × m + g1
bm = (b2−g1) × m + b1
rm, gm, bm: Luminescence rate due to mix rate.
m: Mix ratio (0 ≦ m ≦ 1).
r1, g1, b1: The light emission rates of the respective LEDs 52r, 52g, and 52b when the mix rate is 0.
r2, g2, b2: luminous rates of the respective LEDs 52r, 52g, and 52b in the case of white light. In other words, the maximum value among r1, g1, and b1.

  As shown in FIG. 3A, when the mix rate is 0 (m = 0), the LED 52r emits 10%, the LED 52g emits 60%, and the LED 52b emits 30%. As shown in FIG. 3 (b), when the mix rate is 0.4 (m = 0.4), the R-LED 52r has a light emission rate of 30%, the G-LED 52g has a light emission rate of 60%, and the B-LED 52b has a light emission rate. 42%. As shown in FIG. 3C, when the mix rate is 1 (m = 1), the light emission rates of the R-LED 52r, the G-LED 52g, and the B-LED 52b are all 60%.

  When the light emission rate of each LED 52r, LED 52g, and LED 52b calculated by the light emission rate calculation unit 32 of the active processing unit 30 is the optimal light emission rate for each color component of the frame, the mix rate is zero. In other words, when the mix rate is 0, the light emission rates of the respective LEDs 52r, 52g, and 52b are not changed. Further, when the light emission rate of each LED 52r, LED 52g, and LED 52b is made to coincide with the maximum light emission rate of each LED 52r, LED 52g, and LED 52b, that is, when the backlight is a white light source, the mix rate is 1.

  If the gradation of the frame is 10% for the R component, 60% for the G component, and 30% for the B component, the respective light emission rates of the LEDs 52r, 52g, and 52b are generally 10% for the LED 52r and 60% for the LED 52g. LED 52b is 30%.

  When the mix rate is increased, the color (saturation) of the display image rapidly decreases. However, even if the mix rate is maximized, the luminance distribution within the plane of the display screen can be left.

(offset)
Next, offset will be described.

  FIG. 4A is a diagram showing the state of the light emission rate of each LED 52r, LED 52g, and LED 52b when the offset is 0, and FIG. 4B is the light emission rate of each LED 52r, LED 52g, and LED 52b when the offset is 30%. FIG.

  The offset is a constant value added to each of the LEDs 52r, 52g, and 52b when the light emission rate of each of the LEDs 52r, 52g, and 52b is changed, and is calculated by the light emission rate calculating unit 32.

  As shown in FIG. 4A, when the offset is 0 (m = 0), the light emission rate of the R-LED 52r is 10%, the light emission rate of the G-LED 52g is 60%, and the light emission rate of the B-LED 52g is 30%. As shown in FIG. 4B, when the offset is 30%, the light emission rate of the LED 52r is 40%, the light emission rate of the LED 52g is 90%, and the light emission rate of the LED 52b is 60%.

  When the offset is increased, the color (saturation) of the display image does not rapidly decrease and can be left to some extent. However, when the offset reaches the maximum value, the in-plane luminance distribution of the display image becomes small and the display image becomes white as a whole.

(Light leakage from the color filter)
When the light emission rates of the LEDs 52r, 52g, and 52b are individually controlled (independent drive), light leakage from the color filter may occur. Due to light leakage from the color filter, the color of the image displayed on the display screen of the LCD panel 60 may be different before and after the active control of the backlight 50 is performed. This will be described with reference to FIGS.

  FIG. 5 is a schematic diagram illustrating a state in which light emitted from each of the LEDs 52r, 52g, and 52b is transmitted through the color filter. FIG. 6 is a diagram illustrating the relationship between the transmission wavelengths of the RGB color filters and the emission wavelengths of the RGB LEDs. FIG. 7 is a diagram for explaining a state of light leakage between illumination areas representing a state of the display screen of the liquid crystal display device. In FIG. 6, the transmission wavelengths of the RGB color filters are represented by broken lines, and the light emission wavelengths of the RGB LEDs are represented by solid lines.

  The transmission wavelengths of the RGB color filters 61r, 61g, and 61b provided on the LCD panel 60 match the emission wavelengths of the LEDs 52r, 52g, and 52b of the backlight 50, and light is emitted from LEDs of other colors. Ideally, the light should not leak. That is, the color filter 61r that transmits red light transmits only the light of the LED 52r among the LEDs 52r, 52g, and 52b, and the color filter 61g that transmits green light transmits only the light of the LED 52g among the LEDs 52r, 52g, and 52b. Ideally, the color filter 61b that transmits blue light transmits only the light of the LED 52b among the LEDs 52r, 52g, and 52b.

  However, actually, as shown in FIG. 5, for example, the color filter 61b transmits the blue light of the LED 52b and also transmits part of the green light of the LED 52g.

  This is because, for example, as shown in FIG. 6, the transmission wavelength of the color filter 61b (B-CF) has a portion that overlaps the emission wavelength of the LED 52g (G-LED) (region c shown in FIG. 6). ). Therefore, even when only the light of the LED 52b (B-LED) is allowed to pass through the color filter 61b (B-CF), the light of the LED 52g (G-LED) passes through the color filter 61b (B-CF). To do. For this reason, extra light leakage occurs.

  The influence of such light leakage will be described with reference to FIG.

  FIG. 7 is a diagram illustrating an image displayed on the display screen of the LCD panel 60.

  As shown in FIG. 7, a green rectangular image 71 is displayed on a blue background image 70 on the display screen of the LCD panel 60. The display screen of the LCD panel 60 is divided into a plurality of display areas including a display area a and a display area b corresponding to each area 51 of the backlight 50. The rectangular image 71 is displayed in the display area a smaller than the area of the display area a.

  Since only the blue background image 70 is displayed in the display area b, only the LED 52b emits light in the display area b. For this reason, in the display area b, there is no light leakage due to light emission of the other color LEDs (LEDs 52r and 52g), and a blue image with high purity can be displayed.

  On the other hand, in the display area a, since the blue background image 70 and the green rectangular image 71 are displayed, the LED 52b and the LED 52g emit light. As described above, part of the light emitted from the LED 52g passes through the color filter 61b, and thus light leakage occurs in the blue background image 70 displayed in the display area a. When this light leakage is large, the contour portion 72 around the rectangular image 71 in the display area a has a high blue luminance, and a phenomenon (halo phenomenon) in which a ring of light can be seen faintly occurs. As described above, when independent driving control is performed on the respective LEDs 52r, 52g, and 52b, the image quality is deteriorated due to the halo phenomenon.

  When the light emission rates of the respective LEDs 52r, 52g, and 52b are the same and fixed, or when a white LED is used, the ratio of the light transmission amount of the LED 52b and the light transmission amount of the LED 52g with respect to the color filter 61b is Since it is always constant, by incorporating the amount of light leakage of the LED 52g with respect to the color filter 61b at the time of design, the occurrence of light leakage can be suppressed and the halo phenomenon can be suppressed.

  Further, as described in Patent Document 7, the mix rate is calculated, and the light emission rates of the respective LEDs 52r, 52g, and 52b are brought closer to each other by the calculated mix rate, that is, the LEDs 52r, 52g, and 52b are brought closer to a white light source. The halo phenomenon can be reduced.

  For example, in the case of FIG. 7, the mix rate is determined to be 33%.

  The amount of light leakage from the LED 52g to the color filter 61b is 10% of the light emission rate of the LED 52g, and the allowable value of light leakage is less than 20% with respect to the light emission rate of the LED 52b. Note that the allowable value of light leakage is a light leakage limit value that may impair image quality.

  Then, the light emission rates of the LEDs 52r, 52g, and 52b in the display area a before the change are set to 0%, 80%, and 20%, and the aperture ratio of the LCD panel 60 is set to 100%.

  Since the light emission rate of the LED 52g in the display area a is 80%, the amount of light leakage is 8%. Further, since the light emission rate of the LED 52b is 20%, the allowable value of light leakage is 4%. Thus, before the light emission rate is changed, the light leakage amount of the LED 52g exceeds the allowable value of light leakage.

  On the other hand, after the light emission rate is changed by the mix rate, the light emission rates of the LEDs 52r, 52g, and 52b in the display area a are 26%, 80%, and 40%. Since the light emission rate of the LED 52g in the display area a is 80%, the amount of light leakage is 8%. Further, since the light emission rate of the LED 52b is 40%, the allowable amount of light leakage is 8%. As described above, after the light emission rate is changed, the light leakage amount of the LED 52g can be set to be equal to or less than the allowable value of light leakage.

  That is, by calculating the mix rate, changing the ratio of the light emission rates of the LEDs 52r, 52g, and 52b according to the calculated mix rate, and making each LED 52r, 52g, and 52b transition to (approach) white light, the halo phenomenon is caused. Can be reduced.

  In the above description, the light emission rate of each LED 52r, 52g, 52b included in the display area a may be changed by area active driving only the display area a, or the LED 52r, included in the entire display area. The light emission rate of the LEDs 52r, 52g, and 52b may be changed by actively driving the entire 52g and 52b.

(Explanation of color correction parameter correction)
As described above, for example, to reduce the halo phenomenon, the amount of light leakage before and after the LEDs 52r, 52g, and 52b are transitioned to white light by the mix rate, and before and after the emission rate of the LEDs 52r, 52g, and 52b is raised by the offset. Therefore, the color correction parameter deviates from the optimum range between frames. A method for correcting the color correction parameter when such a shift occurs will be described. As described above, the cause of the deviation includes the case where the color gamut is changed and the case where light is leaked from the color filter (sub-pixel). These will be described below.

(Process when color gamut changes)
A processing flow of the liquid crystal display device 1 will be described with reference to FIG.

  FIG. 8 is a diagram for explaining the processing flow of the liquid crystal display device 1.

  When the LEDs 52r, 52g, and 52b of the backlight 50 are independently driven, the color gamut within the frame is enlarged, and the image displayed on the screen of the LCD panel 60 is displayed with high saturation. When the backlight 50 is driven independently, a color correction parameter (color correction correction value) that lowers the saturation is set as an initial value of the color correction parameter by the user or the like as an initial setting, for example, in the storage unit 25. It is stored ((1) in FIG. 8). The initial value may be preset and stored in the storage unit 25 at the time of factory shipment.

  Next, when it is necessary to reduce the halo phenomenon, the light emission rate calculation unit 32 calculates the mix rate and offset, and adds the mix rate and offset to the light emission rates of the LEDs 52r, 52g, and 52b. The ratio of the light emission rates of 52g and 52b changes (transitions to white). That is, the light emission state of the backlight 50 changes ((2) in FIG. 8).

  When the light emission state of the backlight 50 transitions, the state detection unit 11 detects the transition of the light emission state of the backlight 50 ((3) in FIG. 8).

  As described above, when the ratio of the light emission rates of the LEDs 52r, 52g, and 52b is reduced, the color gamut within one frame is reduced. For this reason, the color correction parameters set for decreasing the saturation performed before each LED 52r, 52g, and 52b transitions to white have an excessive correction amount, and the image displayed on the screen of the LCD panel 60 is colored. The degree will be displayed low.

  That is, when the ratio of the light emission rates of the LEDs 52r, 52g, and 52b changes, the gradation data changes between frames. For this reason, even if the ratio of the light emission rates of the LEDs 52r, 52g, and 52b changes, if the color correction parameters such as saturation are kept constant, the color correction parameters will be out of the optimum correction amount range. .

  Here, the optimum correction amount range of the color correction parameter, whether or not the set correction amount is excessive, the degree of excessive correction amount, and the like are the models to which the liquid crystal display device 1 is applied. The optimum correction amount range is confirmed in advance, and the threshold value is set in advance.

  It should be noted that a predetermined range is provided in advance in the mix rate and offset, and when the mix rate and offset acquired by the state detection unit 11 exceed a predetermined range provided in advance, the state detection unit 11 You may make it detect that the light emission state of the backlight 50 changed ((3) of FIG. 8).

  When the state detection unit 11 detects the transition of the light emission state of the backlight 50, the correction rate acquisition unit 12 then calculates the correction rate of the color correction parameter from the mix rate or offset acquired from the light emission rate calculation unit 32. ((4) in FIG. 8).

  The correction rate of the color correction parameter acquired by the correction rate acquisition unit 12 can be calculated from the mix rate, for example, as in the following formula (1).

Correction rate of color correction parameter = 100 [%]-(X-mix rate [%]) (1)
X is an arbitrary constant. The value of X is variously set for each color correction parameter (luminance, saturation, hue) depending on the model to which the liquid crystal display device 1 is applied.

  For example, when calculating the correction rate of the saturation color correction parameter, if X = 50 is set, the saturation correction rate is 90 when the mix rate is set to 40% (0.4). Calculated as a percentage.

  When the correction rate acquisition unit 12 acquires an offset instead of the mix rate, the correction rate of the color correction parameter is obtained by calculating using the acquired offset instead of the mix rate of the above formula (1). Can do.

  In the example of (4) in FIG. 8, the correction rate acquisition unit 12 calculates “luminance: 120%”, “saturation: 90%”, and “hue: 85%” by calculation as the correction rates of the respective color correction parameters. is doing. Here, the value of X when calculating the luminance when the mix rate is 40% is 20, and the value of X when calculating the hue is 55.

  As a method for obtaining the correction rate of the color correction parameter, as described above, calculation may be performed using the above equation (1), or the correction rate of each color correction parameter corresponding to the mix rate or offset in advance. (For example, if the mix rate is 30%, the correction rate is set to 50%, etc.) and stored in the storage unit 25 as a LUT (Look Up Table), and each color correction corresponding to the mix rate or offset The parameter correction rate may be acquired from the storage unit 25.

  As such a method for obtaining the correction rate of the color correction parameter, an optimum method may be selected depending on the electronic apparatus to which the liquid crystal display device 1 is applied. In addition, it is preferable that the LUT determines a correction amount corresponding to the mix ratio or offset in advance, including the determination of the excess or deficiency of the color correction parameter in which the light emission rate of the backlight 50 is changed.

  When the color correction parameter calculation unit 22 acquires the correction rate of the color correction parameter acquired by the correction rate acquisition unit 12, the color correction parameter calculation unit 22 acquires the initial value of the color correction parameter stored in the storage unit 25, and sets the color correction parameter. The color correction parameters are corrected by recalculation ((5) in FIG. 8).

  For example, when the correction rate of the color correction parameter “saturation: 90%” is acquired from the correction rate acquisition unit 12, the color correction parameter calculation unit 22 acquires the initial value of saturation stored in the storage unit 25. To do.

  The color correction parameter calculation unit 22 calculates the color correction parameter by calculating “color correction parameter = initial value × correction rate”.

  The color correction parameter calculation unit 22 stores a value of 90% with respect to the initial saturation value acquired from the storage unit 25 in the storage unit 25 as a corrected saturation correction amount, and also stores the value in the image data calculation unit 23. Output. In this way, the color correction parameter for saturation is corrected. Similarly, the color correction parameters are corrected for luminance and hue.

  Thereby, it is possible to control the driving of the light emission rates of the respective LEDs 52r, 52g, and 52b and to prevent the color of the image displayed on the LCD panel 60 from changing.

  The correction of these color correction parameters may be corrected in synchronization with a signal for driving the backlight 50 by the backlight driving unit 42, or changes more slowly than a signal for driving the backlight 50 by the backlight driving unit 42. You may do it.

  In addition, the area for acquiring the correction rate for correcting the color correction parameter may be a part of the display screen.

  FIG. 10 is a diagram showing an area for calculating the correction rate of the color correction parameter of the image to be displayed on the LCD panel 60.

  For example, an area where the state detection unit 11 detects a change in the state of the light emission rate of the LEDs 52r, 52g, and 52b is a part of the display area d in the image display surface of the LCD panel 60 as shown in FIG. To do. Then, the state detection part 11 detects the change of the light emission rate only when the light emission rate of LED52r * 52g * 52b contained in the display area d changes.

  Then, the correction rate acquisition unit 12 acquires the correction rate of the frame color correction parameter in the image included in the display area d among the images displayed on the display screen. Then, the color correction parameter calculation unit 22 corrects the color correction parameter of the frame of the entire screen from the correction rate of the color correction parameter of the frame in the image included in the display area d.

  In this way, resources can be saved by narrowing down the area for obtaining the correction rate for correcting the color correction parameter, so that the load on the circuit can be reduced.

  Further, the target color for performing color correction may be limited. For example, when the correction rate of the color correction parameter is acquired from the correction rate acquisition unit 12, the color correction parameter calculation unit 22 may correct only the color correction parameter for the skin color among red, green, and skin color. In this way, resources can be saved by narrowing down the color for correcting the color correction parameter, so that the load on the circuit can be reduced.

  Further, for example, the color correction parameter calculation unit 22 increases the correction amount of the color correction parameter for the skin color among red, green, and flesh color, and decreases the correction amount for red, depending on the target color for color correction. The correction rate of the correction parameter may be changed. The color correction parameter calculation unit 22 does not necessarily have to correct the color correction parameter in accordance with the correction rate output from the correction rate acquisition unit 12.

  Thus, by changing the correction rate of the color correction parameter for each color, it is possible to prevent the correction amount of the color correction from changing extremely. For this reason, it is possible to prevent the user who is observing the image from feeling uncomfortable due to the color correction.

(If the influence from sub-pixels changes)
As described with reference to FIG. 12 to FIG. 16A and FIG. 16B, the case where the correction of the color correction parameter is required due to the change in the influence from the sub-pixel will be described with reference to FIG.

  When each of the LEDs 52r, 52g, and 52b of the backlight 50 is independently driven, a color correction parameter that lowers the saturation is set as an initial value of the color correction parameter by a user or the like as an initial setting, for example. It is stored in the storage unit 25 ((1) in FIG. 8).

  Next, when it is necessary to reduce the halo phenomenon, the light emission rate calculation unit 32 calculates the mix rate and offset, and adds the mix rate and offset to the light emission rates of the LEDs 52r, 52g, and 52b. The ratio of the light emission rates of 52g and 52b changes (transitions to white). That is, the light emission state of the backlight 50 changes ((2) in FIG. 8).

  When the light emission state of the backlight 50 transitions, the state detection unit 11 detects the transition of the light emission state of the backlight 50 ((3) in FIG. 8).

  In this way, when the ratio of the light emission rates of the respective LEDs 52r, 52g, and 52b is reduced, as shown in FIG. 12, even in the background image 120 of the same gradation, in the display area a and the display area b, Since the white circle image 121 is displayed in the display area b, the aperture ratio of the LCD panel 60 differs between the display area a and the display area b.

  Thus, since the aperture ratio of the LCD panel 60 is different between the display area a and the display area b, the influence of light leakage between adjacent subpixels changes. For this reason, even if the ratio of the light emission rates of the LEDs 52r, 52g, and 52b is changed, if the color correction parameter such as saturation is kept constant, it is out of the optimum correction amount range.

  When the state detection unit 11 detects the transition of the light emission state of the backlight 50, the correction rate acquisition unit 12 then uses the above formula (1) from the mix rate and offset acquired from the light emission rate calculation unit 32. The correction rate of the color correction parameter is calculated ((4) in FIG. 8).

  Note that, as described above, as a method for obtaining the correction rate of the color correction parameter, each color correction parameter corresponding to a predetermined mix rate or offset is used instead of the calculation using the above equation (1). May be stored in the storage unit 25 as an LUT, and the correction rate of each color correction parameter corresponding to the mix rate or offset may be acquired from the storage unit 25.

  When the color correction parameter calculation unit 22 acquires the correction rate of the color correction parameter acquired by the correction rate acquisition unit 12, the color correction parameter calculation unit 22 acquires the initial value of the color correction parameter stored in the storage unit 25. By calculating “= initial value × correction rate”, the color correction parameter is calculated.

  The color correction parameter calculation unit 22 stores the calculated color correction parameter in the storage unit 25 and outputs it to the image data calculation unit 23. In this way, the color correction parameter stored in the storage unit 25 is corrected ((5) in FIG. 8). As a result, the color correction parameter is corrected so as to cancel out light leakage between adjacent sub-pixels of the LCD panel 60.

(flowchart)
The processing flow of the liquid crystal display device 1 will be described with reference to FIG. FIG. 9 is a flowchart showing a process flow of the liquid crystal display device 1.

  First, the initial value of the color correction parameter is set (step S11), and the initial value of the set color correction parameter is stored in the storage unit 25 (storage step). The initial value of the color correction parameter may be set as appropriate by the user, or may be set in advance at the time of factory shipment.

  Next, the light emission rate calculation unit 32 calculates a mix rate, an offset, or the like corresponding to a frame (image signal) of an image to be displayed on the LCD panel 60. The light emission rate calculation unit 32 outputs the calculated mix rate or offset to the LCD aperture ratio calculation unit 31, the state detection unit 11, and the correction rate acquisition unit 12, and also to the backlight drive unit 42. The output is performed, and the backlight drive unit 42 is caused to change the light emission rate of the backlight 50 (light emission rate change step). Thereby, the light emission rate calculation part 32 makes the backlight 50 transition to white by making the backlight drive part 42 drive-control the light emission rate of each LED52r * 52g * 52b of the backlight 50 (step S12). ).

  Next, when the state detection unit 11 acquires the mix rate or offset output from the light emission rate calculation unit 32, the state detection unit 11 detects that the light emission state of the backlight 50 has changed to white. That is, the state detection part 11 detects that the light emission rate of each LED52r * 52g * 52b changed (detection step) (YES of step S13).

  Here, the range of the mix rate or the offset value is determined in advance, and the state detection unit 11 determines that the mix rate or the offset value acquired from the light emission rate calculation unit 32 exceeds the predetermined range. When it is detected that the light emission state of the backlight 50 has changed to white (YES in step S13), and the mix rate or the offset value acquired from the light emission rate calculation unit 32 does not exceed the predetermined range. The process may return to step S12 without detecting that the light emission state of the backlight 50 has changed to white (NO in step S13).

  When the state detection unit 11 detects that the light emission state of the backlight 50 has changed to white in the YES process of step S <b> 13, the state detection unit 11 outputs a notification that the detection has been made to the correction rate acquisition unit 12. To do.

  When the correction rate acquisition unit 12 acquires a notification that the transition of the light emission state has been detected from the state detection unit 11, the correction rate acquisition unit 12 stores the notification as the initial value in the storage unit 25 from the mix rate or offset acquired from the light emission rate calculation unit 32. The correction rate of the current color correction parameter is acquired (correction rate acquisition step) (step S14).

  Then, the correction rate acquisition unit 12 outputs the acquired correction rate of the color correction parameter to the color correction parameter calculation unit 22.

  When the color correction parameter calculation unit 22 acquires the correction rate of the color correction parameter from the correction rate acquisition unit 12, the color correction parameter calculation unit 22 acquires the color correction parameter stored in the storage unit 25, and the correction rate of the acquired color correction parameter. The color correction parameter corresponding to the frame of the image to be displayed on the LCD panel 60 when the light emission rate of each of the LEDs 52r, 52g, and 52b is changed is calculated from the color correction parameter acquired from the storage unit 25 (color correction). Calculation step). Then, the color correction parameter calculation unit 22 overwrites and stores the calculated color correction parameter in the storage unit 25 and outputs it to the image data calculation unit 23 to correct the color correction parameter (step S15).

  The image data calculation unit 23 sets the gradation of the frame of the image displayed on the LCD panel 60 from the color correction parameters acquired from the color correction parameter calculation unit 22, and outputs the gradation data to the active processing unit 30. When the active processing unit 30 acquires the gradation data from the image data calculation unit 23, the light emission rate calculation unit 32 calculates the light emission rates of the respective LEDs 52r, 52g, and 52b of the backlight 50 from the gradation data. As a result of the calculation, if calculation of the mix rate or offset is necessary, the processing returns to the above-described step S12.

  When calculation of the mix rate or offset is necessary, the light emission rate calculation unit 32 outputs the calculation result to the LCD aperture ratio calculation unit 31 and also outputs it to the backlight drive unit 42, to the backlight drive unit 42. Then, the light emission of the LEDs 52r, 52g, and 52b is controlled. Further, the LCD aperture ratio calculation unit 31 calculates each sub-panel of the LCD panel 60 from the calculation result of the light emission rates of the LEDs 52r, 52g, and 52b acquired from the light emission rate calculation unit 32 and the gradation data acquired by the active processing unit 30. Calculate the aperture ratio of the pixel. Then, the LCD aperture ratio calculation unit 31 outputs the calculated result to the LCD panel drive unit 41, thereby causing the LCD panel drive unit 41 to control the aperture ratio of each sub-pixel of the LCD panel 60. As a result, an image is displayed on the display surface of the LCD panel 60.

[Embodiment 2]
Another embodiment of the display device according to the present invention will be described below with reference to FIGS. FIG. 11 is a diagram for explaining a processing flow of the liquid crystal display device 1 according to the second embodiment.

  For convenience of explanation, members having the same functions as those in the drawings described in the first embodiment are given the same reference numerals, and descriptions thereof are omitted.

  The liquid crystal display device 1 according to the present embodiment is different from the liquid crystal display device 1 according to the first embodiment described above in that the backlight 50 is area active drive controlled. That is, the LEDs 52r, 52g, and 52b that are the light sources of the backlight 50 according to the present embodiment correspond to the gradation of the frame of the image displayed on the LCD panel 60 for each of the plurality of areas 51. Is to be changed.

(Process when color gamut changes)
For each area 51 of the backlight 50, when the LEDs 52r, 52g, and 52b are independently driven and area active driving, the color gamut in the frame is enlarged and the image displayed on the screen of the LCD panel 60 is colored. The degree is displayed high. When the LEDs 52r, 52g, and 52b are independently driven and are area active, for example, a color correction parameter that lowers the saturation is set as an initial value of the color correction parameter by, for example, a user as an initial setting and stored. It is stored in the unit 25 ((1) in FIG. 11). Here, the initial value of the color correction parameter is stored in the storage unit 25 for each of the plurality of areas 51.

  Next, when it becomes necessary to reduce the halo phenomenon among the plurality of areas 51, the light emission rate calculation unit 32 calculates the mix rate and the offset for each area 51. For each area 51, a mix rate and an offset are added to the light emission rates of the LEDs 52r, 52g, and 52b. Thereby, for each area 51, the ratio of the light emission rates of the LEDs 52r, 52g, and 52b changes (transitions to white). That is, the light emission state of the backlight 50 changes for each area 51 ((2) in FIG. 11).

  When the ratio of the light emission rates of the LEDs 52r, 52g, and 52b in at least one area 51 among the plurality of areas 51 changes, the state detection unit 11 detects the transition of the light emission state of the backlight 50 ((3 in FIG. 11). )).

  As described above, when the ratio of the light emission rates of the LEDs 52r, 52g, and 52b changes for each area 51, the color gamut of the background image 120 changes between the display areas a and b (see FIG. 12). For this reason, even if the ratio of the light emission rates of the LEDs 52r, 52g, and 52b changes between the areas 51, if the color correction parameter such as saturation is constant for each display area a and b, the color correction parameter is This is outside the range of the optimum correction amount.

  When the state detection unit 11 detects that the light emission state of the LEDs 52r, 52g, and 52b in at least one area 51 among the plurality of areas 51 has been changed by the light emission rate calculation unit 32 ((3) in FIG. 11). Next, the correction rate acquisition unit 12 calculates the correction rate of the color correction parameter for each area 51 from the mix rate or offset in the area 51 by causing the light emission rate calculation unit 32 to change the light emission rate ((FIG. 11 ( 4)).

  As the calculation method of the correction rate, the above-described equation (1) can be used. Alternatively, the correction rate is not a calculation, but a correction rate for each color correction parameter corresponding to the mix rate or offset is determined in advance, and stored in the storage unit 25 for each area 51 as an LUT, and the mix rate or offset Alternatively, the correction rate of each color correction parameter corresponding to the above may be acquired from the storage unit 25 for each area 51.

  The color correction parameter calculation unit 22 then calculates the light emission rate calculation unit 32 from the correction rate of the color correction parameter calculated by the correction rate acquisition unit 12 and the color correction parameter corresponding to the area 51 stored in the storage unit 25. The color correction parameter is calculated by recalculating the color correction parameter of the frame to be displayed in the area 51 after the light emission rate is changed (FIG. 11 (5)).

  For this reason, among the frames of the image to be displayed on the LCD panel 60, the color of the frame displayed in the display areas a and b after the light emission rate calculating unit 32 changes the light emission rate can be corrected. For this reason, it is possible to prevent a change in hue between the areas a and b caused by a change in the light emission rate of the LEDs 52r, 52g, and 52b.

  Here, in the independent drive control, the area where color correction is performed when area active drive is performed may be a part of the display screen.

  For example, an area where the state detection unit 11 detects a change in the state of the light emission rate of the LEDs 52r, 52g, and 52b is a part of the display area d in the image display surface of the LCD panel 60 as shown in FIG. To do. Then, the state detection part 11 detects the change of the light emission rate only when the light emission rate of LED52r * 52g * 52b contained in the display area d changes.

  Then, the correction rate acquisition unit 12 acquires the correction rate of the frame color correction parameter in the image included in the display area d among the images displayed on the display screen. Then, the color correction parameter calculation unit 22 corrects the color correction parameter of the frame in the display area d from the correction rate of the color correction parameter of the frame in the image included in the display area d.

  As described above, resources can be saved by narrowing the area for correcting the color correction parameter in the display screen, so that the load on the circuit can be reduced.

  Further, by narrowing down the area for correcting the color correction parameter, it is possible to prevent the correction amount of the color correction from changing extremely. For this reason, it is possible to prevent the user viewing the image from feeling uncomfortable due to the color correction.

(If the influence from sub-pixels changes)
When the LEDs 52r, 52g, and 52b perform independent area active driving for each area 51 of the backlight 50, for example, a color correction parameter that lowers the saturation by a user or the like as an initial setting is a color correction parameter. The initial value is set and stored in the storage unit 25 ((1) in FIG. 11). Here, the initial value of the color correction parameter is stored in the storage unit 25 for each of the plurality of areas 51.

  Next, when it becomes necessary to reduce the halo phenomenon among the plurality of areas 51, the light emission rate calculation unit 32 calculates the mix rate and the offset for each area 51. For each area 51, a mix rate and an offset are added to the light emission rates of the LEDs 52r, 52g, and 52b. Thereby, for each area 51, the ratio of the light emission rates of the LEDs 52r, 52g, and 52b changes (transitions to white). That is, the light emission state of the backlight 50 transitions ((2) in FIG. 11).

  When the ratio of the light emission rates of the LEDs 52r, 52g, and 52b in at least one area 51 among the plurality of areas 51 changes, the state detection unit 11 detects the transition of the light emission state of the backlight 50 ((3 in FIG. 11). )).

  In this way, when the ratio of the light emission rates of the respective LEDs 52r, 52g, and 52b is reduced, as shown in FIG. 12, even in the background image 120 of the same gradation, in the display area a and the display area b, Since the white circle image 121 is displayed in the display area b, the aperture ratio of the LCD panel 60 is different between the display area a and the display area b.

  Thus, since the aperture ratio of the LCD panel 60 is different between the display area a and the display area b, the influence of light leakage between adjacent subpixels changes. For this reason, even if the ratio of the light emission rates of the LEDs 52r, 52g, and 52b changes, if the color correction parameters such as saturation are constant for each of the areas a and b, the color correction parameter has an optimum correction amount. It will be out of range.

  When the state detection unit 11 detects that the light emission state of the LEDs 52r, 52g, and 52b in at least one area 51 among the plurality of areas 51 has been changed by the light emission rate calculation unit 32 ((3) in FIG. 11). Next, the correction rate acquisition unit 12 calculates the correction rate of the color correction parameter for each area 51 from the mix rate or offset in the area 51 by causing the light emission rate calculation unit 32 to change the light emission rate ((FIG. 11 ( 4)).

  As the calculation method of the correction rate, the above-described equation (1) can be used. Alternatively, the correction rate is not a calculation, but a correction rate for each color correction parameter corresponding to the mix rate or offset is determined in advance, and stored in the storage unit 25 for each area 51 as an LUT, and the mix rate or offset Alternatively, the correction rate of each color correction parameter corresponding to the above may be acquired from the storage unit 25 for each area 51.

  The color correction parameter calculation unit 22 then calculates the light emission rate calculation unit 32 from the correction rate of the color correction parameter calculated by the correction rate acquisition unit 12 and the color correction parameter corresponding to the area 51 stored in the storage unit 25. The color correction parameter is calculated by recalculating the color correction parameter of the frame to be displayed in the area 51 after the light emission rate is changed (FIG. 11 (5)).

  For this reason, among the frames of the image displayed on the LCD panel 60, the color between the display areas a and b among the frames shown in the display areas a and b after the light emission rate calculating unit 32 changes the light emission rate. Correction can be performed. For this reason, it is possible to prevent a change in hue between the display areas a and b caused by a change in the light emission rate of the LEDs 52r, 52g, and 52b.

(Program, computer-readable recording medium)
In addition, each block of the display device 1, in particular, the state detection unit 11, the correction rate acquisition unit 12, the color correction parameter calculation unit 22, the image data calculation unit 23, and the light emission rate calculation unit 32 is configured by hardware logic. Alternatively, it may be realized by software using a computer as follows.

  That is, the state detection unit 11, the correction rate acquisition unit 12, the color correction parameter calculation unit 22, the image data calculation unit 23, and the light emission rate calculation unit 32 are CPUs (central processing) that execute instructions of a control program for realizing each function unit), a ROM (read only memory) storing the program, a RAM (random access memory) expanding the program, a storage device (recording medium) such as a memory storing the program and various data, and the like.

  An object of the present invention is a control program for the state detection unit 11, the correction rate acquisition unit 12, the color correction parameter calculation unit 22, the image data calculation unit 23, and the light emission rate calculation unit 32 that is software that implements the functions described above. Are recorded on a computer-readable recording medium such as a state detection unit 11, a correction rate acquisition unit 12, a color correction parameter calculation unit 22, and an image data calculation unit 23. It can also be achieved by supplying to the light emission rate calculation unit 32 and reading and executing the program code recorded on the recording medium by the computer (or CPU or MPU).

  Examples of the recording medium include a tape system such as a magnetic tape and a cassette tape, a magnetic disk such as a floppy (registered trademark) disk / hard disk, and an optical disk such as a CD-ROM / MO / MD / DVD / CD-R. Card system such as IC card, IC card (including memory card) / optical card, or semiconductor memory system such as mask ROM / EPROM / EEPROM / flash ROM.

  Further, the state detection unit 11, the correction rate acquisition unit 12, the color correction parameter calculation unit 22, the image data calculation unit 23, and the light emission rate calculation unit 32 are configured to be connectable to a communication network, and the program code is transmitted via the communication network. May be supplied. The communication network is not particularly limited. For example, the Internet, intranet, extranet, LAN, ISDN, VAN, CATV communication network, virtual private network, telephone line network, mobile communication network, satellite communication. A net or the like is available. Further, the transmission medium constituting the communication network is not particularly limited. For example, even in the case of wired such as IEEE 1394, USB, power line carrier, cable TV line, telephone line, ADSL line, etc., infrared rays such as IrDA and remote control, Bluetooth ( (Registered trademark), 802.11 wireless, HDR, mobile phone network, satellite line, terrestrial digital network, and the like can also be used. The present invention can also be realized in the form of a computer data signal embedded in a carrier wave in which the program code is embodied by electronic transmission.

  In addition, this invention is not limited to embodiment mentioned above, A various change is possible in the range shown to the claim. That is, embodiments obtained by combining technical means appropriately modified within the scope of the claims are also included in the technical scope of the present invention.

  The present invention can be applied to a display device that controls the light emission rate of a light source by a video signal of a display image.

1 Liquid crystal display device (display device)
10 Control unit 11 State detection unit (detection means)
12 Correction rate acquisition unit (correction rate acquisition means)
20 video processing unit 21 color correction unit 22 color correction parameter calculation unit (color correction calculation means)
23 image data calculation unit 25 storage unit 30 active processing unit 31 LCD aperture ratio calculation unit 32 light emission rate calculation unit (light emission rate changing means)
41 LCD panel drive unit 42 Backlight drive unit 50 Backlight 51 Area
52r, 52g, 52b LED (light source)
60 LCD panel (display panel)
a ・ b ・ d display area

Claims (7)

A display device comprising: a display panel capable of displaying an image; and a light source that illuminates the display panel, wherein the light source changes a light emission rate of the light source in response to an image signal of an image displayed on the display panel Because
A storage unit for storing correction values for color correction of the image signal;
A light emission rate changing means for changing the light emission rate of the light source in response to the image signal;
Detecting means for detecting that the light emission rate changing means has changed the light emission rate of the light source;
When the detection unit detects a change in the light emission rate of the light source, the correction rate of the correction value of the color correction stored in the storage unit is determined from the amount of change in the light emission rate of the light source changed by the light emission rate change unit. Correction rate acquisition means for acquiring
When the light emission rate changing means changes the light emission rate of the light source from the correction rate of the color correction acquired by the correction rate acquisition unit and the correction value of the color correction stored in the storage unit. And a color correction calculation means for calculating a correction value for color correction of the image signal. The light source is arranged for each of the divided areas,
The storage unit stores a correction value for color correction of the image signal for each of the plurality of regions,
The light emission rate changing means changes the light emission rate of the light source corresponding to the image signal for each of the plurality of regions,
The detection means detects that the light emission rate changing means has changed the light emission rate of the light source in at least one of the plurality of regions,
When the detection unit detects a change in the light emission rate of the light source, the correction rate acquisition unit stores, in the storage unit, the amount of change in the light emission rate of the light source in the region where the light emission rate change unit has changed the light emission rate. Obtain the correction rate of the correction value of the color correction corresponding to the stored area,
The color correction calculation unit is configured to calculate the light emission rate of the region from the correction rate of the color correction acquired by the correction rate acquisition unit and a correction value of color correction corresponding to the region stored in the storage unit. The display device according to claim 1, wherein the change unit calculates a correction value for color correction of the image signal when the light emission rate of the light source is changed.   When the detection means detects a change in the light emission rate of the light source, the correction rate acquisition means is stored in the storage unit by calculation from the amount of change in the light emission rate of the light source changed by the light emission rate change means. The display device according to claim 1, wherein a correction rate of the correction value of the current color correction is acquired. The storage unit stores a change amount of the light emission rate of the light source and a correction rate of the correction value of the color correction in association with each other.
When the detection unit detects a change in the light emission rate of the light source, the correction rate acquisition unit corrects the color correction associated with the amount of change in the light emission rate of the light source changed by the light emission rate change unit. The display device according to claim 1, wherein the rate is acquired from the storage unit. The above image is displayed on a display device that includes a display panel capable of displaying an image, and a light source that illuminates the display panel with light and changes a light emission rate corresponding to an image signal of the image displayed on the display panel. Display method for displaying
A storage step for storing a correction value for color correction of the image signal;
A light emission rate changing step for changing the light emission rate of the light source corresponding to the image signal,
A detection step for detecting that the light emission rate of the light source has been changed in the light emission rate change step;
When the change in the light emission rate of the light source is detected in the detection step, the correction value of the color correction stored in the storage step is corrected from the amount of change in the light emission rate of the light source changed in the light emission rate change step. A correction rate acquisition step for acquiring a rate;
When the light emission rate of the light source is changed in the light emission rate change step from the color correction correction rate acquired in the correction rate acquisition step and the color correction correction value stored in the storage step. And a color correction calculation step for calculating a correction value for color correction of the image signal.   A display program for operating the display device according to claim 1, wherein the computer functions as each of the above-described means.   A computer-readable recording medium in which the display program according to claim 6 is recorded.

Images