WO2011155244A1

WO2011155244A1 - Display device

Info

Publication number: WO2011155244A1
Application number: PCT/JP2011/056794
Authority: WO
Inventors: 上原和弘
Original assignee: シャープ株式会社
Priority date: 2010-06-08
Filing date: 2011-03-22
Publication date: 2011-12-15

Abstract

A liquid crystal display device (1) includes a backlight device (backlight unit) (3) and a liquid crystal panel (display unit) (2) for displaying information and displays information by dividing one frame period into first to third sub-field periods. In the liquid crystal display device (1), a controller (control unit) (6) selects, among light sources (13) having a plurality of colors, a light source color used as a reference for calculating the permeability of each pixel in each of the three sub-field periods on the basis of an image signal stored in a storage device (storage unit) (4), calculates the permeability of each pixel on the basis of the selected color, and determines, among the light sources (13) having the plurality of colors, a light source subjected to a lighting operation and the luminance value of the light source in each of the three sub-field periods.

Description

Display device

The present invention relates to a display device, particularly a non-light-emitting display device such as a liquid crystal display device.

In recent years, for example, liquid crystal display devices have been widely used in liquid crystal televisions, monitors, mobile phones and the like as flat panel displays having features such as thinness and light weight compared to conventional cathode ray tubes. Such a liquid crystal display device includes a backlight device that emits light, and a liquid crystal panel that displays a desired image by acting as a shutter for light from a light source provided in the backlight device. Yes.

Further, the liquid crystal display device as described above has three colors of light emitting diodes (LEDs) of red (R), green (G), and blue (B) for a liquid crystal panel not provided with a color filter. Color display using a driving method that displays red-only images, green-only images, and blue-only images in sequence in one frame period by sequentially flashing the LEDs of each color as a light source, so-called field sequential driving method Is known to do.

However, in the normal field sequential drive system as described above, since the color display is performed by switching the images of red, green, and blue at high speed, the color of the display image is displayed when the moving image is displayed. May cause a problem called color braking (color breakage) phenomenon.

Therefore, in a conventional liquid crystal display device, for example, as described in Patent Document 1 below, a first subfield period in which at least a green light emitting diode among red, green, and blue light emitting diodes emits light is provided. Among the red and blue light emitting diodes, a second subfield period in which at least the red light emitting diode emits light and a third subfield period in which the blue light emitting diode emits light are set as one frame period. Further, in this conventional liquid crystal display device, in each of the first to third subfield periods, the light emission time of each light emitting diode is determined according to the image signal, and to the liquid crystal panel according to the determined light emission time. Image output signal (instruction signal) is generated. Thereby, in this conventional liquid crystal display device, the color breaking phenomenon can be suppressed.

JP 2009-134156 A

However, in the conventional liquid crystal display device as described above, since the color processing order is fixedly determined as green, red, and blue, depending on the image signal input from the outside, that is, the display image, the color brake In some cases, the bending phenomenon could not be suppressed.

In view of the above problems, an object of the present invention is to provide a display device that can reliably suppress the color breaking phenomenon regardless of the display image.

In order to achieve the above object, a display device according to the present invention includes a backlight unit having a plurality of color light sources that can be mixed with white light, a plurality of pixels, and illumination light from the backlight unit. And a display device that displays information and displays information by dividing one frame period into N (N is an integer of 3 or more) subfield periods,
A storage unit for storing the input image signal;
A control unit that performs drive control of the backlight unit and the display unit using an image signal stored in the storage unit,
The control unit, based on an image signal stored in the storage unit, of a light source serving as a reference for calculating a transmittance for each pixel among the light sources of the plurality of colors in each of the N subfield periods. The color is selected, the transmittance for each pixel is calculated based on the selected color, and the light source to be turned on and its luminance value are determined among the light sources of the plurality of colors in each of the N subfield periods. It is characterized by doing.

In the display device configured as described above, the control unit calculates the transmittance for each pixel of the light sources of a plurality of colors in each of the N subfield periods based on the image signal stored in the storage unit. Select the color of the light source that is the reference for calculation. In addition, the control unit calculates the transmittance for each pixel based on the selected color, and determines the light source to be turned on and the luminance value among the light sources of a plurality of colors in each of the N subfield periods. Thus, unlike the conventional example, the color braking phenomenon can be reliably suppressed regardless of the display image.

Further, in the above display device, the control unit includes each histogram of the maximum values of all the mixed colors constituted by a combination of a plurality of colors of light sources from the image signal stored in the storage unit, and a minimum value for each of the plurality of colors. It is preferable that each of the histograms is acquired for each pixel, and based on the acquired histogram, a reference color for calculating the transmittance for each pixel in each of the N subfield periods is selected.

In this case, the control unit can select the reference color in consideration of color mixture and luminance concentration in the displayed image in each subfield period, and more reliably suppress the color breaking phenomenon. be able to.

Further, in the display device, the control unit acquires, for each pixel, each histogram of the maximum values of all the mixed colors configured by a combination of a plurality of light source colors from the image signal stored in the storage unit, When it is determined that the values of the histograms of these maximum values are all 0, the control unit turns on only the light source of one color in one subfield period in the N subfield periods. As described above, it is preferable to turn on the light sources of a plurality of colors in a predetermined order.

In this case, since the light sources of a plurality of colors are not turned on in one subfield period, the power consumption of the display device can be reduced.

In the display device, the first, second, and third subfield periods are used as the N subfield periods.
As the multi-color light sources, red, green, and blue light emitting diodes that emit red, green, and blue light, respectively, are used.
In the first subfield period, the control unit calculates a transmittance for each pixel of any one of red, green, and blue based on the image signal stored in the storage unit. Select the reference color, determine the luminance value of the light emitting diode of the selected color, calculate the transmittance for each pixel in the first subfield period, and calculate the calculated transmittance for each pixel Is used to determine the luminance value of each light emitting diode of the remaining two colors of red, green, and blue,
In the second subfield period, the control unit, based on the image signal stored in the storage unit, removes any one of the two colors of red, green, and blue. Is selected as a reference color for calculating the transmittance of each pixel, the luminance value of the light emitting diode of the selected color is determined, and the transmittance of each pixel in the second subfield period is calculated. And determining the luminance value of the light emitting diode of the other color of the two colors using the calculated transmittance for each pixel,
In the third subfield period, based on the image signal stored in the storage unit, the control unit converts the other color of the two colors among red, green, and blue to the transmittance for each pixel. May be selected as a reference color for calculating and the luminance value in the light emitting diode of the selected color may be determined, and the transmittance for each pixel in the third subfield period may be calculated.

In this case, it is possible to appropriately determine the luminance value of each color light of red, green, and blue and the transmittance for each pixel in each subfield period. As a result, the color purity of each color light can be used appropriately, and a display device having excellent display quality and capable of color display can be easily configured.

In the display device, the light source of at least one color among the light sources of the plurality of colors is turned on in the N subfield periods, or one subfield in the N subfield periods. It is preferable to provide a mode switching means for switching whether or not the light sources of a plurality of colors are turned on in a predetermined order so that only one color light source is turned on during the period.

In this case, it is possible to set whether the color braking phenomenon is surely suppressed by the mode switching means or whether the display device can save power.

According to the present invention, it is possible to provide a display device that can reliably suppress the color breaking phenomenon regardless of the display image.

FIG. 1 is a diagram for explaining a main configuration of a liquid crystal display device according to a first embodiment of the present invention. FIG. 2 is a diagram for explaining a main configuration of the liquid crystal panel shown in FIG. FIG. 3 is a plan view showing a main configuration of the backlight device shown in FIG. FIG. 4 is a flowchart showing the basic operation of the liquid crystal display device shown in FIG. FIG. 5 is a flowchart showing a specific operation in the first subfield period shown in FIG. FIG. 6 is a flowchart showing a specific operation in the second subfield period shown in FIG. FIG. 7 is a flowchart showing a specific operation in the third subfield period shown in FIG. FIG. 8A to FIG. 8B are diagrams for explaining an example of the processing operation in the controller shown in FIG. FIG. 9A to FIG. 9D are diagrams for explaining an example of the processing operation in the controller shown in FIG. FIGS. 10A to 10D are diagrams for explaining an example of another processing operation in the controller shown in FIG. FIG. 11 is a diagram for explaining a main configuration of a liquid crystal display device according to the second embodiment of the present invention. FIG. 12 is a flowchart showing a specific operation in the first subfield period in the liquid crystal display device shown in FIG. FIGS. 13A to 13D are diagrams for explaining an example of the processing operation of the conventional FSD process in the controller shown in FIG. FIG. 14 is a diagram for explaining a main configuration of a liquid crystal display device according to the third embodiment of the present invention. FIG. 15 is a flowchart showing the basic operation of the liquid crystal display device shown in FIG.

Hereinafter, preferred embodiments of the display device of the present invention will be described with reference to the drawings. In the following description, the case where the present invention is applied to a transmissive liquid crystal display device will be described as an example. Moreover, the dimension of the structural member in each figure does not faithfully represent the actual dimension of the structural member, the dimensional ratio of each structural member, or the like.

[First Embodiment]
FIG. 1 is a diagram for explaining a main configuration of a liquid crystal display device according to a first embodiment of the present invention. In FIG. 1, a liquid crystal display device 1 according to the present embodiment includes a liquid crystal panel 2 as a display unit for displaying information, and a backlight device 3 as a backlight unit for irradiating the liquid crystal panel 2 with illumination light. The liquid crystal panel 2 and the backlight device 3 are integrated as a transmissive liquid crystal display device 1.

Further, the liquid crystal display device 1 of the present embodiment includes a storage device 4 that stores an image signal input from the outside, an arithmetic device 5 that is sequentially connected to the storage device 4, and a controller 6 that serves as a control unit. . The controller 6 is connected to a gate driver 7 and a source driver 8 that drive the liquid crystal panel 2, and a backlight control device 9 that controls driving of the backlight device 3. The gate driver 7 and the source driver 8 drive a source wiring and a gate wiring, which will be described later, provided on the liquid crystal panel 2 based on an instruction signal (control signal) from the controller 6.

In the liquid crystal display device 1 of the present embodiment, as will be described in detail later, one frame period (one TV field period) is divided into first, second, and third subfield periods to display information. It is configured as follows.

Here, the liquid crystal panel 2 and the backlight device 3 will be described in detail with reference to FIGS. 2 and 3 respectively.

FIG. 2 is a diagram for explaining a main configuration of the liquid crystal panel shown in FIG. FIG. 3 is a plan view showing a main configuration of the backlight device shown in FIG.

In FIG. 2, the gate driver 7 and the source driver 8 are connected to the liquid crystal panel 2. The gate driver 7 and the source driver 8 are drive circuits that drive a plurality of pixels P provided in the liquid crystal panel 2 in units of pixels. The gate driver 7 and the source driver 8 include a plurality of gate lines G1 to GN. (N is an integer of 2 or more) and a plurality of source lines S1 to SM (M is an integer of 2 or more) are connected to each other. The gate lines G1 to GN and the source lines S1 to SM are arranged in a matrix, and the regions of the plurality of pixels P are formed in the regions partitioned in the matrix.

Further, the liquid crystal panel 2 is not provided with a color filter, and red, green and blue (RGB) light emitting diodes provided in the backlight device 3 are driven to turn on sequentially, so that each pixel P has a light emitting diode. The light is modulated so as to modulate the light from, and functions as red, green, and blue pixels.

The gate lines G1 to GN are provided for each pixel P, and connected to the gate of the switching element 10 using, for example, a thin film transistor (ThinThFilm Transistor). On the other hand, the source of the switching element 10 is connected to each of the source lines S1 to SM. In addition, a pixel electrode 11 provided for each pixel P is connected to the drain of each switching element 10. In each pixel P, the common electrode 12 is configured to face the pixel electrode 11 with a liquid crystal layer (not shown) provided on the liquid crystal panel 2 interposed therebetween.

In the liquid crystal panel 2, a control signal is input from the controller 6 to the source driver 8. Then, the source driver 8 appropriately outputs a voltage signal corresponding to the input control signal to the source lines S1 to SM. The gate driver 7 sequentially outputs gate signals for turning on the gates of the corresponding switching elements 10 to the gate lines G1 to GN based on the control signal from the controller 6. Thereby, in the liquid crystal panel 2, in order to display the input image corresponding to the input image signal, the transmittance is changed for each pixel P, and the input image is displayed.

The backlight device 3 will be specifically described with reference to FIG.

As shown in FIG. 3, the backlight device 3 includes a plurality of light emitting diodes 13 as light sources and a bottomed casing 14 that houses the plurality of light emitting diodes 13. In the backlight device 3, a diffusion plate (not shown) is provided so as to block the opening of the housing 14, and planar illumination light is irradiated to the liquid crystal panel 2 side through the diffusion plate. . Further, in the backlight device 3, as illustrated in FIG. 3, a total of 100 light emitting diodes 13 in 10 rows and 10 columns provided in parallel in the horizontal and vertical directions on the display surface of the liquid crystal panel 2 are used. Has been.

Further, for example, red, green, and blue light-emitting

diodes

13r, 13g, and 13b that emit red (R), green (G), and blue (B) light, respectively, are integrated with each of the plurality of light-emitting diodes 13. The so-called three-in-one (3 in 1) type configured as described above is used. That is, the backlight device 3 uses light sources of a plurality of colors that can be mixed with white light.

Returning to FIG. 1, the storage device 4 constitutes a storage unit, and is configured to temporarily hold an image signal for one frame input from the outside. The arithmetic device 5 performs predetermined image processing on the image signal stored in the storage device 4. That is, the arithmetic device 5 reads the image signal held in the storage device 4 and performs the predetermined image processing for improving the output image quality such as γ correction on the read image signal. Thereafter, the arithmetic device 5 outputs the image signal after the image processing to the controller 6.

The controller 6 outputs a control signal to the gate driver 7 and the source driver 8 based on the image signal stored in the storage device 4, and also controls the light emitting diode 13 to the backlight control device 9. Output a signal. Further, as will be described in detail later, the controller 6 selects a pixel among the RGB

light emitting diodes

13r, 13g, and 13b in each of the three subfield periods based on the image signal stored in the storage device 4. The color of the light emitting diode 13 serving as a reference for calculating the transmittance for each pixel is selected, the transmittance for each pixel is calculated based on the selected color, and the RGB light emitting diode 13r is used in each of the three subfield periods. , 13g, and 13b, the light source to be turned on and the luminance value thereof are determined.

The backlight control device 9 causes the light emitting diode 13 to emit light based on a control signal from the controller 6. That is, in the backlight device 3, the lighting operation is performed so that each of the

light emitting diodes

13r, 13g, and 13b has the luminance value (LED luminance value) obtained by the controller 6.

The operation of the liquid crystal display device 1 of the present embodiment configured as described above will be specifically described with reference to FIGS. In the following description, the operation of the controller 6 will be mainly described.

FIG. 4 is a flowchart showing the basic operation of the liquid crystal display device shown in FIG. FIG. 5 is a flowchart showing a specific operation in the first subfield period shown in FIG. FIG. 6 is a flowchart showing a specific operation in the second subfield period shown in FIG. FIG. 7 is a flowchart showing a specific operation in the third subfield period shown in FIG.

As shown in step S1 of FIG. 4, the controller 6 of the present embodiment first selects a reference color for calculating the transmittance for each pixel in the first subfield period. In the selection of the reference color, the controller 6, as will be described in detail later, sets each of the maximum values of all the mixed colors composed of combinations of a plurality of colors of the light emitting diodes 13 from the image signal stored in the storage device 4. The histogram and each histogram of the minimum value for each of the plurality of colors are acquired for each pixel, and the process is performed based on the acquired histogram (the same applies to step S3 described later).

Next, as shown in step S2 of FIG. 4, the controller 6 of this embodiment calculates the transmittance for each pixel and the LED luminance value of each color in the first subfield period.

Subsequently, as shown in step S3 of FIG. 4, the controller 6 of the present embodiment selects a reference color for calculating the transmittance for each pixel in the second subfield period.

Next, as shown in step S4 of FIG. 4, the controller 6 of the present embodiment calculates the transmittance for each pixel and the LED luminance value of each color in the second subfield period.

Finally, as shown in step S5 of FIG. 4, the controller 6 of the present embodiment calculates the transmittance and color LED luminance value for each pixel in the third subfield period.

More specifically, the processing operations shown in FIG. 5 are sequentially performed in steps S1 and S2.

That is, as the processing operation in the first subfield period, first, as shown in step S100 of FIG. 5, the controller 6 of the present embodiment uses white, yellow, and cyan colors from the image signal stored in the storage device 4. , And the histogram of the maximum value of magenta color is acquired for each pixel.

Next, as shown in step S 101 of FIG. 5, the controller 6 of the present embodiment obtains each histogram of red, green, and blue minimum values for each pixel from the image signal stored in the storage device 4. .

Subsequently, as shown in step S102 of FIG. 5, the controller 6 of the present embodiment is a mixed color (that is, white, yellow, cyan) having a large value (large number of pixels) in each histogram of the acquired maximum value in each histogram. Color and magenta color). At this time, the controller 6 of the present embodiment gives priority to white when the area of white and other mixed colors is close and the area of other mixed colors> area of white in the maximum histogram. Whether to give priority to other color mixing is determined by a threshold value and a setting flag set in the controller 6. In addition to this description, for example, it may be set so that white is always prioritized.

Next, as shown in step S103 of FIG. 5, the controller 6 of the present embodiment is selected in step S102 from among red, green, and blue in each histogram of the minimum value acquired in step S101. One primary color having a small area and a large area (number of pixels) is selected from the primary colors constituting the mixed color.

Subsequently, as shown in step S104 of FIG. 5, the controller 6 of the present embodiment uses the primary color selected in step S103 as a reference color for calculating the transmittance for each pixel in the first subfield period. .

Next, as shown in step S105 of FIG. 5, the controller 6 of the present embodiment detects the maximum value of the primary color selected in step S103. That is, the controller 6 detects the maximum component value among the component values (signal values) of the selected primary color in the image signal stored in the storage device 4.

Subsequently, as shown in step S106 of FIG. 5, the controller 6 of the present embodiment calculates the LED luminance value of the primary color selected in step S103. That is, the controller 6 sets the transmittance in the first subfield period to the maximum value (that is, 100%), and uses the maximum component value detected in step S105 as the LED luminance value of the primary color selected in step S103. And

Next, as shown in step S 107 of FIG. 5, the controller 6 of this embodiment calculates the transmittance for each pixel. That is, in the image signal stored in the storage device 4, the controller 6 divides the component value for each pixel in the selected primary color by the LED luminance value calculated in step S 106, thereby Calculate the transmittance.

Subsequently, as shown in step S108 of FIG. 5, the controller 6 of the present embodiment uses the transmittance for each pixel calculated in step S107 to provide each of the two primary colors other than the primary color selected in step S103. LED brightness value for each pixel is calculated. That is, in the image signal stored in the storage device 4, the controller 6 calculates the component value for each pixel in each of the two primary colors other than the primary color as the transmittance of the corresponding pixel calculated in step S 107. By dividing, the LED luminance value for each pixel in each primary color is calculated.

However, when this step S108 is performed, if the transmittance of the pixel is “0”, the LED luminance value is set to an infinite value. As a result, the pixel having the transmittance of “0” is excluded from the determination process of the LED luminance value in the subsequent step S109. When this step S108 is performed, if the color mixture selected in step S102 is a color other than white (that is, any one of yellow, cyan, and magenta), the color mixture other than white is selected. The primary color light emitting diodes 13 that are not configured are not lit in the first subfield period. That is, the controller 6 sets the LED luminance value for each pixel in the primary colors that do not constitute a mixed color other than white to “0”.

Next, as shown in step S109 of FIG. 5, the controller 6 of the present embodiment uses the minimum value of the LED luminance value calculated in step S108 for each of the two types of primary colors as the LED luminance in the corresponding primary color. Value.

Further, in steps S3 and S4, the processing operations shown in FIG. 6 are sequentially performed.

That is, as the processing operation in the second subfield period, first, as shown in step S200 of FIG. 6, the controller 6 of the present embodiment performs image processing for each of the two primary colors other than the primary color selected in step S103. The output luminance value displayed in the first subfield period is subtracted from the component value of the signal to obtain the component value in the second subfield period. That is, in the image signal stored in the storage device 4, the controller 6 determines in step S109 the transmittance of the corresponding pixel calculated in step S107 from the component values for each pixel in the two primary colors. By subtracting the output luminance value in the first subfield period, which is obtained by multiplying the LED luminance value in the corresponding primary color, the component value of each primary color in the second subfield period is obtained. calculate.

Next, as shown in step S201 of FIG. 6, the controller 6 of the present embodiment acquires each histogram of the minimum values of the two primary colors calculated in step S200 for each pixel.

Subsequently, as shown in step S202 of FIG. 6, the controller 6 according to the present embodiment selects a primary color having a small value and a wide area (number of pixels) in each histogram of the minimum values acquired in step S201. Select one.

Next, as shown in step S 203 of FIG. 6, the controller 6 of the present embodiment uses the primary color selected in step S 202 as a reference color for calculating the transmittance for each pixel in the second subfield period. .

Subsequently, as shown in step S204 of FIG. 6, the controller 6 of the present embodiment detects the maximum value of the primary colors selected in step S202. That is, the controller 6 detects the maximum component value among the corresponding primary color component values in the second subfield period calculated in step S200.

Next, as shown in step S205 of FIG. 6, the controller 6 of the present embodiment calculates the LED luminance value of the primary color selected in step S202. That is, the controller 6 sets the transmittance in the second subfield period to the maximum value (that is, 100%), and uses the maximum component value detected in step S204 as the LED luminance value of the primary color selected in step S202. And

Subsequently, as shown in step S 206 of FIG. 6, the controller 6 of the present embodiment calculates the transmittance for each pixel. That is, the controller 6 divides the component value for each pixel of the corresponding primary color in the second subfield period calculated in step S200 by the LED luminance value calculated in step S205, thereby transmitting each pixel. Calculate the rate.

Next, as shown in step S207 of FIG. 6, the controller 6 of the present embodiment uses the transmissivity for each pixel calculated in step S206 for each primary color other than the primary color selected in step S202. The LED brightness value is calculated. That is, in the image signal stored in the storage device 4, the controller 6 divides the component value for each pixel in a primary color other than the primary color by the transmittance of the corresponding pixel calculated in step S206. The LED luminance value for each pixel in the primary color is calculated.

However, when this step S207 is performed, the LED luminance value is set to an infinite value when the transmittance of the pixel is “0”, as in step S108. As a result, a pixel having a transmittance of “0” is excluded from the LED luminance value determination process in the subsequent step S208.

Subsequently, as shown in step S208 of FIG. 6, the controller 6 of the present embodiment uses the minimum value of the LED luminance value calculated in step S207 for the primary colors other than the primary colors as the LED luminance value of the primary color. To do.

In step S5, the processing operations shown in FIG. 7 are sequentially performed.

That is, as a processing operation in the third subfield period, first, as shown in step S300 of FIG. 7, the controller 6 of the present embodiment uses the remaining primary colors other than the primary color selected in step S202. The output luminance value displayed in the first and second subfield periods is subtracted from the component value to obtain the component value in the third subfield period. That is, in the image signal stored in the storage device 4, the controller 6 determines the corresponding pixel transmittance calculated in step S107 from the component values for each pixel in the remaining primary colors in step S109. The output luminance value in the first subfield period, which is obtained by multiplying the LED luminance value in the primary color, the transmittance of the corresponding pixel calculated in step S206, and the relevant value determined in step S208 The component value of the primary color in the third subfield period is calculated by subtracting the output brightness value in the second subfield period, which is obtained by multiplying the LED brightness value in the primary color.

Subsequently, as shown in step S301 in FIG. 7, the controller 6 of the present embodiment detects the maximum value of the remaining primary colors. That is, the controller 6 detects the maximum component value among the component values of the primary color in the third subfield period calculated in step S300.

Next, as shown in step S302 of FIG. 7, the controller 6 of the present embodiment calculates the LED brightness values of the remaining primary colors. That is, the controller 6 sets the transmittance in the third subfield period to the maximum value (that is, 100%), and sets the maximum component value detected in step S301 as the LED luminance value of the primary color.

Subsequently, as shown in step S 303 of FIG. 7, the controller 6 of the present embodiment calculates the transmittance for each pixel. That is, the controller 6 divides the component value for each pixel of the remaining primary color in the third subfield period calculated in step S300 by the LED luminance value calculated in step S302, so that Calculate the transmittance.

Here, the processing operation shown in FIGS. 5 to 7 will be specifically described with reference to FIGS.

FIG. 8A to FIG. 8B are diagrams for explaining an example of the processing operation in the controller shown in FIG. FIG. 9A to FIG. 9D are diagrams for explaining an example of the processing operation in the controller shown in FIG. FIGS. 10A to 10D are diagrams for explaining an example of another processing operation in the controller shown in FIG.

In the following description, as illustrated in FIG. 8A, processing operations for eight pixels arranged on a straight line will be described.

In the following description, a case where the red component value, the green component value, and the blue component value of each pixel are values illustrated in FIG. 8A in the image signal stored in the storage device 4 will be described. To do. Specifically, for example, in the pixel 1, all values of the red component value, the green component value, and the blue component value are “80”, and in this pixel 1, white light emission with a luminance of 80% of the maximum luminance ( Display). For example, in the pixel 7, the red component value, the green component value, and the blue component value are “0”, “80”, and “” 0 ”, respectively, and in this pixel 7, the luminance is 80% of the maximum luminance. It is required to emit green light (display).

The controller 6 of the present embodiment performs the processing operations of steps S100 and S101 of FIG. 5, whereby the histogram shown in FIG. 8B is acquired from the image signal shown in FIG. That is, after the histograms of the maximum values of white, yellow, cyan, and magenta are acquired for each pixel, the histograms of the minimum values of red, green, and blue are acquired for each pixel.

Subsequently, the controller 6 of the present embodiment performs the processing operation of step S102 in FIG. At this time, a case where the controller 6 selects white according to a preset setting flag will be described. In this case, the controller 6 selects red, green, and blue as the primary colors constituting white, and calculates the area (number of pixels) from the red minimum value, green minimum value, and blue minimum value shown in FIG. ) Is a reference color for calculating the transmittance of each pixel in the first subfield period.

Then, the controller 6 according to the present embodiment performs the processing operation of steps S105 to S107 in FIG. The transmittance is determined. Specifically, as shown in FIG. 9A, a value of “80” is determined as the blue LED luminance value in the first subfield period, and each transmittance of the pixels 1 to 8 is determined. .

Further, in the actual display operation in the first subfield period, each of the pixels 1 to 8 has a blue output luminance value (= blue LED luminance value × transmittance / 100) shown in FIG. A blue light emission operation (display operation) is performed. Specifically, for example, in the pixel 1, blue light emission (display) is performed with a blue output luminance value of “80”, that is, luminance of 80% of the maximum luminance. For example, in the pixel 5, since the transmittance value is “0”, the blue output luminance value is also “0”, and blue light is not emitted.

Subsequently, the controller 6 according to the present embodiment performs the processing operations of steps S108 to S109 in FIG. 5, whereby the luminance values of the green and red

light emitting diodes

13g and 13r in the first subfield period, that is, the green LED. A luminance value and a red LED luminance value are determined. Specifically, as shown in FIG. 9A, a value of “80” is determined as the green LED luminance value and the red LED luminance value in the first subfield period.

Further, in the actual display operation in the first subfield period, simultaneously with the blue light emission operation, each of the pixels 1 to 8 has a green output luminance value (= green LED luminance value × transmission in FIG. 9A). The green light emission operation (display operation) is performed at a value indicated by (rate / 100), and the red light emission operation (display operation) is indicated by a red output luminance value (= red LED luminance value × transmittance / 100). I do. Specifically, for example, in the pixel 1, green light emission (display) is performed with a green output luminance value of “80”, that is, a luminance of 80% of the maximum luminance. For example, in the pixel 5, since the transmittance value is “0”, the green output luminance value is also “0” and green light is not emitted. Similarly, for example, the pixel 1 emits red light (display) with a red output luminance value of “80”, that is, 80% of the maximum luminance. For example, in the pixel 5, since the transmittance value is “0”, the red output luminance value is also “0” and red light is not emitted.

Next, when the controller 6 of the present embodiment performs the processing operation of step S200 in FIG. 6, the component values in the second subfield period are obtained as shown in FIG. 9B. That is, the controller 6 subtracts the red output luminance value and the green output luminance value shown in FIG. 9A from the red component value and the green component value shown in FIG. The red component value and the green component value in the two subfield periods are calculated. The blue component values of the pixels 1 to 8 are “0” values. That is, blue is used as a reference color in the first subfield period, and in each of the pixels 1 to 8 in the first subfield period, the light emission operation according to the image signal is performed. Each blue component value of the pixels 1 to 8 is a value of “0”.

Subsequently, when the controller 6 of the present embodiment performs the processing operations of steps S202 to S203 in FIG. 6, the reference color for calculating the transmittance for each pixel in the second subfield period is determined to be red. . That is, the controller 6 finds a red component value having a large number of pixels of the minimum value (that is, a value of “0”) from among the red component value and the green component value shown in FIG. The reference color for calculating the transmittance for each pixel in the sub-field period is used.

Next, the controller 6 of the present embodiment performs the processing operations of steps S204 to S206 in FIG. 6, so that the luminance value of the red light emitting diode 13r in the second subfield period, that is, the red LED luminance value and each pixel. Is determined. Specifically, as shown in FIG. 9C, a value of “80” is determined as the red LED luminance value in the second subfield period, and each transmittance of the pixels 1 to 8 is determined. .

In the actual display operation in the second subfield period, each of the pixels 1 to 8 has a value indicated by a red output luminance value (= red LED luminance value × transmittance / 100) in FIG. 9C. The red light emission operation (display operation) is performed with. Specifically, for example, the pixel 5 emits red light (display) with a red output luminance value of “80”, that is, 80% of the maximum luminance. Further, for example, in the pixel 7, since the transmittance value is “0”, the red output luminance value is also “0”, and red light is not emitted.

Subsequently, the controller 6 according to the present embodiment performs the processing operations of steps S207 to S208 in FIG. 6 to determine the luminance value of the green light emitting diode 13g in the second subfield period, that is, the green LED luminance value. The Specifically, as shown in FIG. 9C, a value of “80” is determined as the green LED luminance value in the second subfield period.

Further, in the actual display operation in the second subfield period, simultaneously with the red light emission operation, each of the pixels 1 to 8 has a green output luminance value (= green LED luminance value × transmission in FIG. 9C). The green light emission operation (display operation) is performed at a value indicated by (rate / 100). In the second subfield period, as shown in FIG. 9B, since the blue component values of all the pixels 1 to 8 are “0”, the blue LED luminance value and the blue output luminance value are As shown in FIG. 9C, all the pixels 1 to 8 have a value of “0”. That is, the blue light emission operation (display operation) is not performed in the second subfield period.

Next, the controller 6 according to the present embodiment performs the processing operations of steps S300 to S303 in FIG. 7, so that the luminance value of the green light emitting diode 13g in the third subfield period, that is, the green LED luminance value and each pixel. Is determined. Specifically, as shown in FIG. 9D, a value of “80” is determined as the green LED luminance value in the third subfield period, and each transmittance of the pixels 1 to 8 is determined. .

Further, in the actual display operation in the third subfield period, each of the pixels 1 to 8 has a value indicated by a green output luminance value (= green LED luminance value × transmittance / 100) in FIG. 9D. The green light emission operation (display operation) is performed with. Specifically, for example, the pixel 7 emits green light (display) with a green output luminance value of “80”, that is, luminance of 80% of the maximum luminance. For example, in the pixel 1, since the transmittance value is “0”, the green output luminance value is also “0”, and green light is not emitted. In the third subfield period, the blue component value and the red component value of all the pixels 1 to 8 are “0”, so the blue LED luminance value, the blue output luminance value, the red LED luminance value, and the red color. As shown in FIG. 9D, the output luminance value is “0” in all the pixels 1 to 8. That is, the blue and red light emission operations (display operations) are not performed in the third subfield period.

Further, when the controller 6 of the present embodiment performs the processing operation of step S102 of FIG. 5, the controller 6 performs color mixing (that is, white, yellow, cyan, and magenta) according to a preset setting flag. Of these, as shown in FIG. 8B, a case where yellow having a large area (number of pixels) is selected will be described. In this case, the controller 6 selects red and green as the primary colors constituting yellow, and the red having a wide area (number of pixels) from the red minimum value and the green minimum value shown in FIG. A reference color for calculating the transmittance of each pixel in the subfield period is used. Further, the controller 6 does not perform the light emission operation (display operation) for blue that does not constitute yellow in the first subfield period.

Then, the controller 6 according to the present embodiment performs the processing operation of steps S105 to S107 in FIG. 5, whereby the luminance value of the red light emitting diode 13r in the first subfield period, that is, the red LED luminance value and the pixel-by-pixel value. The transmittance is determined. Specifically, as shown in FIG. 10A, a value of “80” is determined as the red LED luminance value in the first subfield period, and each transmittance of the pixels 1 to 8 is determined. .

In the actual display operation in the first subfield period, each of the pixels 1 to 8 has a value indicated by a red output luminance value (= red LED luminance value × transmittance / 100) in FIG. The red light emission operation (display operation) is performed with. Specifically, for example, in the pixel 1, red light emission (display) is performed with a red output luminance value of “80”, that is, luminance of 80% of the maximum luminance. Further, for example, in the pixel 7, since the transmittance value is “0”, the red output luminance value is also “0”, and red light is not emitted.

Subsequently, when the controller 6 of the present embodiment performs the processing operation of steps S108 to S109 in FIG. 5, the luminance value of the green light emitting diode 13g in the first subfield period, that is, the green LED luminance value is determined. The Specifically, as shown in FIG. 10A, a value of “80” is determined as the green LED luminance value in the first subfield period.

Further, in the actual display operation in the first subfield period, simultaneously with the red light emission operation, each of the pixels 1 to 8 has a green output luminance value (= green LED luminance value × transmission in FIG. 10A). The green light emission operation (display operation) is performed at a value indicated by (rate / 100). Specifically, for example, in the pixel 1, green light emission (display) is performed with a green output luminance value of “80”, that is, a luminance of 80% of the maximum luminance. For example, in the pixel 7, since the transmittance value is “0”, the green output luminance value is also “0”, and green light is not emitted. Further, since the blue light emission operation (display operation) is not performed in the first subfield period, as shown in FIG. 10A, the blue LED luminance value and the blue output luminance value are the same for all the pixels 1 to 8, the value is “0”.

Next, the controller 6 according to the present embodiment performs the processing operation of step S200 in FIG. 6 to obtain the component values in the second subfield period as shown in FIG. 10B. That is, the controller 6 subtracts the green output luminance value and the blue output luminance value shown in FIG. 10A from the green component value and the blue component value shown in FIG. The green component value and the blue component value in the two subfield periods are calculated. The red component values of the pixels 1 to 8 are “0” values. That is, red is used as a reference color in the first subfield period, and in each of the pixels 1 to 8 in the first subfield period, the light emitting operation corresponding to the image signal is performed. Each red component value of the pixels 1 to 8 is a value of “0”.

Subsequently, when the controller 6 of the present embodiment performs the processing operations of steps S202 to S203 in FIG. 6, the reference color for calculating the transmittance for each pixel in the second subfield period is determined to be green. . That is, the controller 6 finds a green component value having a large number of pixels of the minimum value (that is, a value of “0”) out of the green component value and the blue component value shown in FIG. The reference color for calculating the transmittance for each pixel in the sub-field period is used.

Next, the controller 6 according to the present embodiment performs the processing operations of steps S204 to S206 in FIG. 6, so that the luminance value of the green light-emitting diode 13g in the second subfield period, that is, the green LED luminance value and each pixel. Is determined. Specifically, as shown in FIG. 10C, a value of “80” is determined as the green LED luminance value in the second subfield period, and each transmittance of the pixels 1 to 8 is determined. .

Further, in the actual display operation in the second subfield period, each of the pixels 1 to 8 has a value indicated by a green output luminance value (= green LED luminance value × transmittance / 100) in FIG. The green light emission operation (display operation) is performed with. Specifically, for example, the pixel 7 emits green light (display) with a green output luminance value of “80”, that is, luminance of 80% of the maximum luminance. For example, in the pixel 1, since the transmittance value is “0”, the green output luminance value is also “0”, and green light is not emitted.

Subsequently, when the controller 6 of the present embodiment performs the processing operations of steps S207 to S208 in FIG. 6, the luminance value of the blue light emitting diode 13b in the second subfield period, that is, the blue LED luminance value is determined. The Specifically, as shown in FIG. 10C, a value of “0” is determined as the blue LED luminance value in the second subfield period. In the pixels 1 to 4, the blue component value is a value of “80” as shown in FIG. 10B, and in the pixels 5 to 6, the blue component value is the value shown in FIG. As shown in FIG. 10, although the value is “0”, since the transmittance of the pixel is “0” as shown in FIG. 10C, each blue LED luminance value is set to an infinite value. . In the pixels 7 to 8, since the blue component value is “0” as shown in FIG. 10B, the transmittance of the pixel is “100” as shown in FIG. ”, Each blue LED luminance value is a value of“ 0 ”, and this minimum value“ 0 ”is determined as the blue LED luminance value.

Further, in the actual display operation in the second subfield period, simultaneously with the green light emission operation, each of the pixels 1 to 8 has a blue output luminance value (= blue LED luminance value × transmission in FIG. 10C). The blue light emission operation (display operation) is performed at a value indicated by (rate / 100). However, in this case, since the blue output luminance values of all the pixels 1 to 8 are “0”, the blue light emission operation (display operation) is not performed in the second subfield period. In the second subfield period, as shown in FIG. 10B, the red component values of all the pixels 1 to 8 are “0”, so the red LED luminance value and the red output luminance value are As shown in FIG. 10C, all the pixels 1 to 8 have a value of “0”. That is, the red light emission operation (display operation) is not performed in the second subfield period.

Next, the controller 6 according to the present embodiment performs the processing operation of steps S300 to S303 in FIG. 7, so that the luminance value of the blue light-emitting diode 13b in the third subfield period, that is, the blue LED luminance value and each pixel is changed. Is determined. Specifically, as shown in FIG. 10D, a value of “80” is determined as the blue LED luminance value in the third subfield period, and each transmittance of the pixels 1 to 8 is determined. .

Further, in the actual display operation in the third subfield period, each of the pixels 1 to 8 has a blue output luminance value (= blue LED luminance value × transmittance / 100) shown in FIG. A blue light emission operation (display operation) is performed. Specifically, for example, in the pixel 1, blue light emission (display) is performed with a blue output luminance value of “80”, that is, luminance of 80% of the maximum luminance. For example, in the pixel 5, since the transmittance value is “0”, the blue output luminance value is also “0”, and blue light is not emitted. In the third sub-field period, the red component value and the green component value of all the pixels 1 to 8 are “0”, and therefore the red LED luminance value, the red output luminance value, the green LED luminance value, and the green color. As shown in FIG. 10D, the output luminance value is a value of “0” in all the pixels 1 to 8. That is, the red and green light emission operations (display operations) are not performed in the third subfield period.

In the liquid crystal display device 1 of the present embodiment configured as described above, the controller (control unit) 6 has three subfield periods based on the image signal stored in the storage device (storage unit) 4. The color of the light emitting diode (light source) 13 that is a reference for calculating the transmittance for each pixel is selected from among the RGB

light emitting diodes

13r, 13g, and 13b (multiple color light sources). Further, the controller 6 calculates the transmittance for each pixel based on the selected color, and among the three

light emitting diodes

13r, 13g, and 13b, the light emitting diode 13 that is lit and the luminance thereof. The value is determined. That is, in the liquid crystal display device 1 of the present embodiment, the controller 6 can analyze the input image signal and suppress the color breaking phenomenon as shown in the flowcharts of FIGS. The order of colors and their luminance values are determined. Thereby, in the liquid crystal display device 1 of this embodiment, unlike the conventional example, the color braking phenomenon can be reliably suppressed regardless of the display image.

In the present embodiment, the controller 6 uses the histograms of the maximum values of white, yellow, cyan, and magenta colors from the image signal stored in the storage device 4 and the minimum values of red, green, and blue. A histogram is acquired for each pixel, and based on the acquired histogram, a reference color for calculating the transmittance for each pixel in each of the three subfield periods is selected. As a result, in this embodiment, the controller 6 can select the reference color in consideration of color mixing and luminance concentration in the displayed image in each subfield period, and the color braking phenomenon can be selected. It can suppress more reliably.

[Second Embodiment]
FIG. 11 is a diagram for explaining a main configuration of a liquid crystal display device according to the second embodiment of the present invention. In the figure, the main difference between the present embodiment and the first embodiment is that the controller has each of the maximum values of white, yellow, cyan, and magenta colors in the image signal stored in the storage device. When it is determined that the values of the histogram are all 0, RGB light-emitting diodes are set in a predetermined manner so that only one color light-emitting diode is lit in one sub-field period in three sub-field periods. The point is to turn on the lighting in order. In addition, about the element which is common in the said 1st Embodiment, the same code | symbol is attached | subjected and the duplicate description is abbreviate | omitted.

That is, as shown in FIG. 11, the liquid crystal display device 1 of this embodiment is provided with a controller 15 as a control unit. If the controller 15 determines that the histogram values of the maximum values of white, yellow, cyan, and magenta are all 0 in the image signal stored in the storage device 4, the controller 15 In the subfield period, the RGB

light emitting diodes

13r, 13g, and 13b are lit in a predetermined order so that only the light emitting diode 13 of one color is lit in one subfield period.

In other words, the controller 15 of the present embodiment determines whether or not the CBU (Color Breaking Up) suppression mode that can reliably suppress the color braking phenomenon shown in the first embodiment can be performed, and determines that it cannot be performed. In this case, it is possible to select a power saving priority mode using conventional FSD (Field Sequential Display) driving that can immediately save power.

Here, the operation of the liquid crystal display device 1 of the present embodiment configured as described above will be specifically described with reference to FIGS. In the following description, operations different from those in the first embodiment will be mainly described.

FIG. 12 is a flowchart showing a specific operation in the first subfield period in the liquid crystal display device shown in FIG. FIGS. 13A to 13D are diagrams for explaining an example of the processing operation of the conventional FSD process in the controller shown in FIG.

As shown in FIG. 12, the controller 15 of the present embodiment performs the processing operation of step S 100, and determines each of the maximum values of white, yellow, cyan, and magenta from the image signal stored in the storage device 4. After obtaining the histogram for each pixel, it is determined whether or not there is a color mixture. That is, the controller 15 checks whether all of the maximum values of white, yellow, cyan, and magenta are “0” (step S1001). When the controller 15 determines that a value other than “0” exists, the controller 15 determines that there is color mixing in the image to be displayed, and executes the processing operation of step S101 as in the first embodiment. .

On the other hand, when it is determined in step S1001 that there is no value other than “0”, the controller 15 determines that there is no color mixture in the image to be displayed, and executes the conventional FSD process (power saving priority mode). (Step S1002). That is, in the three subfield periods, the controller 15 lights the RGB

light emitting diodes

13r, 13g, and 13b in a predetermined order so that only one color light emitting diode 13 is turned on in one subfield period. Make it work.

Hereinafter, a case where the conventional FSD process in step S1002 is executed on the image signal shown in FIG. 8A will be described as an example. Further, the case where the red, green, and blue

light emitting diodes

13r, 13g, and 13b are turned on in the first, second, and third subfield periods will be described as an example.

The controller 15 of the present embodiment, based on the red component value shown in FIG. 8A, the luminance value of the red light emitting diode 13r in the first subfield period, that is, the red LED luminance value and the transmission for each pixel. Determine the rate. Specifically, as shown in FIG. 13A, a value of “80” is determined as the red LED luminance value in the first subfield period, and each transmittance of the pixels 1 to 8 is determined. .

Further, in this conventional FSD process, the green and blue

light emitting diodes

13g and 13b are not turned on during the first subfield period. That is, as shown in FIG. 13A, the controller 15 of this embodiment sets the green LED luminance value, the green output luminance value, the blue LED luminance value, and the blue output luminance value for all the pixels 1 to 8 as “ The value is 0 ”.

Also, the red component value, the green component value, and the blue component value in the second and third subfield periods are values shown in FIG. Then, the controller 15 of the present embodiment, based on the green component value shown in FIG. 13B, the luminance value of the green light emitting diode 13g in the second subfield period, that is, the green LED luminance value and each pixel. Determine the transmittance. Specifically, as shown in FIG. 13C, a value of “80” is determined as the green LED luminance value in the second subfield period, and each transmittance of the pixels 1 to 8 is determined. .

In the actual display operation in the second subfield period, each of the pixels 1 to 8 has a value indicated by a green output luminance value (= green LED luminance value × transmittance / 100) in FIG. The green light emission operation (display operation) is performed with. Specifically, for example, in the pixel 1, green light emission (display) is performed with a green output luminance value of “80”, that is, a luminance of 80% of the maximum luminance.

Furthermore, in this conventional FSD process, the blue and red

light emitting diodes

13b and 13r are not turned on in the second subfield period. That is, as shown in FIG. 13C, the controller 15 of the present embodiment sets the blue LED luminance value, the blue output luminance value, the red LED luminance value, and the red output luminance value for all the pixels 1 to 8 as “ The value is 0 ”.

Finally, the controller 15 of the present embodiment, based on the blue component value shown in FIG. 13B, the luminance value of the blue light emitting diode 13b in the third subfield period, that is, the blue LED luminance value and the pixel. The transmittance for each is determined. Specifically, as shown in FIG. 13D, a value of “80” is determined as the blue LED luminance value in the third subfield period, and each transmittance of the pixels 1 to 8 is determined. .

Further, in the actual display operation in the third subfield period, each of the pixels 1 to 8 has a blue output luminance value (= blue LED luminance value × transmittance / 100) shown in FIG. A blue light emission operation (display operation) is performed. Specifically, for example, in the pixel 1, blue light emission (display) is performed with a blue output luminance value of “80”, that is, luminance of 80% of the maximum luminance. Further, for example, in the pixel 7, since the transmittance value is “0”, the blue output luminance value is also “0”, and blue light is not emitted.

Furthermore, in this conventional FSD process, the green and red

light emitting diodes

13g and 13r are not lit in the third subfield period. That is, as shown in FIG. 13D, the controller 15 of the present embodiment sets the green LED luminance value, the green output luminance value, the red LED luminance value, and the red output luminance value for all the pixels 1 to 8 as “ The value is 0 ”.

With the above configuration, the present embodiment can achieve the same operations and effects as the first embodiment. In the present embodiment, the controller 15 determines that all the histogram values of the maximum values of white, yellow, cyan, and magenta are all 0 in the image signal stored in the storage device 4. In this case, the power saving priority mode is executed. Thereby, in this embodiment, it is determined whether the CBU suppression mode is operable in the first part of the operation flow. If it is determined that the CBU suppression mode cannot be operated, the power saving priority mode is immediately selected. Since the operation of the CBU suppression mode flow is omitted, unnecessary operations after the determination of the CBU suppression mode can be omitted.

[Third Embodiment]
FIG. 14 is a diagram for explaining a main configuration of a liquid crystal display device according to the third embodiment of the present invention. In the figure, the main difference between the present embodiment and the second embodiment is that a mode switching register for switching modes in the liquid crystal display device is provided. In addition, about the element which is common in the said 1st Embodiment, the same code | symbol is attached | subjected and the duplicate description is abbreviate | omitted.

That is, as shown in FIG. 14, the liquid crystal display device 1 of the present embodiment is provided with a mode switching register 16 as mode switching means and a controller 17 connected thereto. The mode switching register 16 is configured to select the CBU suppression mode or the power saving priority mode and instruct the controller 17 in accordance with an instruction from the outside (that is, an instruction from the user). In other words, in the liquid crystal display device 1 of the present embodiment, the mode switching register 16 suppresses CBU that causes the light emitting diode 13 of at least one color among the plurality of light emitting diodes 13 to be lit in the three subfield periods. Power saving in which the light emitting diodes 13 of a plurality of colors are turned on in a predetermined order so that only the light emitting diode 13 of one color is turned on in one subfield period in the three subfield periods. The priority mode can be switched.

Here, the operation of the liquid crystal display device 1 of the present embodiment configured as described above will be specifically described with reference to FIG. In the following description, operations different from those in the second embodiment will be mainly described.

FIG. 15 is a flowchart showing the basic operation of the liquid crystal display device shown in FIG.

As shown in step S6 of FIG. 15, the controller 17 of this embodiment determines whether or not the mode set by the mode switching register 16 is the CBU suppression mode. When it is determined that the CBU suppression mode is set, the controller 17 executes the process of step S1 as in the first embodiment.

On the other hand, when it is determined in step S6 that the CBU suppression mode is not set, that is, the power saving priority mode is set, the controller 17 executes the conventional FSD process (step S7). That is, the controller 17 performs the same process as that in step S1002 in the second embodiment.

With the above configuration, the present embodiment can achieve the same operations and effects as those of the second embodiment. Further, in the present embodiment, it is possible to set whether the color braking phenomenon is surely suppressed by the mode switching register (mode switching means) 16 or power saving of the liquid crystal display device 1 is achieved.

It should be noted that all of the above embodiments are illustrative and not restrictive. The technical scope of the present invention is defined by the claims, and all modifications within the scope equivalent to the configurations described therein are also included in the technical scope of the present invention.

For example, in the above description, the case where the present invention is applied to a transmissive liquid crystal display device has been described. However, the display device of the present invention is not limited to this, and information is obtained using light of a light source. The present invention can be applied to various non-light emitting display devices for display. Specifically, the display device of the present invention can be suitably used for a transflective liquid crystal display device or a projection display device such as a rear projection using the liquid crystal panel as a light valve. Also, display devices (projectors) using DMD (Digital Micromirror Device) elements, organic EL (electroluminescence) display devices, plasma display panels (PDP: Plasma Display Panel), field emission displays (FED: Field Display, etc.) The present invention can also be applied to other display devices.

In the above description, a case where a 3in1 type light emitting diode in which RGB light emitting diodes are integrated is used as the light source is described. However, the light source of the present invention is not limited to this, for example, a cold cathode fluorescent tube. Alternatively, a light emitting device such as a discharge tube such as a hot cathode fluorescent tube, a light emitting element such as an organic EL (Electronic Luminescence) or inorganic EL element, or a PDP (Plasma Display Panel) can be used as a light source.

However, it is preferable to use a light-emitting diode as a light source as in the above-described embodiments in that a display device with low power consumption and excellent environmental characteristics can be easily configured.

In addition, the light emitting diode of the present invention is not limited to the above 3in1 type light emitting diode, and each of R, G, and B uses a single color individual light emitting diode or a white (W) light emitting diode emitting white light. Alternatively, a so-called four-in-one (4in1) type light emitting diode in which four light emitting diodes such as RGBW and GRGB are integrated can be applied. In addition, light emitting diodes of colors other than RGBW can be added. In this case, it is necessary to add a color to the pixel configuration of the liquid crystal panel, but a wider range of colors can be reproduced. Specific colors to be added include, for example, yellow and magenta.

However, as in the above-described embodiments, the case where light emitting diodes of different colors and different colors that can be mixed with white light (for example, RGB) are used is composed of only white light emitting diodes. Compared to the above, it is preferable in that the color purity of each color light can be easily increased, and a display device having excellent display quality and capable of color display can be easily configured.

In the above description, the case where one frame period is divided into first to third subfield periods has been described. However, the present invention is not limited to this, and N frame periods (N is There is no limitation as long as information display is performed by dividing into subfield periods of an integer of 3 or more. Specifically, for example, four or more subfield periods added with black may be used, and the present invention is applied to a plurality of continuous subfield periods constituting one frame period (1 TV field period). be able to.

In the above description, the histograms of the maximum values of white, yellow, cyan, and magenta colors, and the minimum values of red, green, and blue from the image signals stored in the storage device (storage unit). The case where the histogram is acquired for each pixel has been described. However, the present invention is not limited to this, and each histogram of the maximum values of all the mixed colors composed of a combination of a plurality of colors of light sources from the image signal stored in the storage unit, and each of the plurality of colors. What is necessary is just to acquire each histogram of the minimum value for every pixel.

In addition to the above description, a plurality of display areas are set on the display unit (liquid crystal panel), and a plurality of illumination areas into which the light from the light source is incident on the plurality of display areas are provided as backlight units (backlights). The present invention can also be applied to a display device of a local dimming (area active backlight) driving method in which a light source is lit and driven in units of illumination areas.

The present invention is useful for a display device that can reliably suppress the color breaking phenomenon regardless of the display image.

1 Liquid crystal display device 2 Liquid crystal panel (display unit)
3 Backlight device (backlight part)
4. Storage device (storage unit)
6, 15, 17 Controller (control unit)
16 Mode switching register (mode switching means)
13 Light emitting diode (light source)
13r Red light emitting diode (light source)
13g Green light-emitting diode (light source)
13b Blue light emitting diode (light source)

Claims

A backlight unit having a plurality of color light sources that can be mixed with white light, a plurality of pixels, a display unit that displays information using illumination light from the backlight unit, and one frame period A display device that displays information divided into N (N is an integer of 3 or more) subfield periods,
A storage unit for storing the input image signal;
A control unit that performs drive control of the backlight unit and the display unit using an image signal stored in the storage unit,
The control unit, based on an image signal stored in the storage unit, of a light source serving as a reference for calculating a transmittance for each pixel among the light sources of the plurality of colors in each of the N subfield periods. The color is selected, the transmittance for each pixel is calculated based on the selected color, and the light source to be turned on and the luminance value thereof among the light sources of the plurality of colors are determined in each of the N subfield periods. To
A display device characterized by that.
The control unit, for each pixel, each histogram of the maximum value of all the mixed colors composed of a combination of a plurality of colors of light sources from the image signal stored in the storage unit, and each histogram of the minimum value for each of the plurality of colors. The display device according to claim 1, wherein the display device selects a color that serves as a reference for calculating transmittance for each pixel in each of the N subfield periods based on the acquired histogram.
The control unit acquires, for each pixel, each histogram of the maximum value of all the mixed colors configured by a combination of a plurality of colors of light sources from the image signal stored in the storage unit, and each histogram of these maximum values In the case where it is determined that the values of all are zero, the control unit is configured to output a plurality of colors so that only one color light source is turned on in one subfield period in the N subfield periods. The display device according to claim 2, wherein the light sources are turned on in a predetermined order.
As the N subfield periods, first, second, and third subfield periods are used,
As the multi-color light sources, red, green, and blue light emitting diodes that emit red, green, and blue light, respectively, are used.
In the first subfield period, the control unit calculates a transmittance for each pixel of any one of red, green, and blue based on the image signal stored in the storage unit. Select the reference color, determine the luminance value of the light emitting diode of the selected color, calculate the transmittance for each pixel in the first subfield period, and calculate the calculated transmittance for each pixel Is used to determine the luminance value of each light emitting diode of the remaining two colors of red, green, and blue,
In the second subfield period, the control unit, based on the image signal stored in the storage unit, removes one of the two colors of red, green, and blue. Is selected as a reference color for calculating the transmittance of each pixel, the luminance value of the light emitting diode of the selected color is determined, and the transmittance of each pixel in the second subfield period is calculated. And determining the luminance value of the light emitting diode of the other color of the two colors using the calculated transmittance for each pixel,
In the third subfield period, based on the image signal stored in the storage unit, the control unit converts the other color of the two colors among red, green, and blue to the transmittance for each pixel. 4. The method according to claim 1, wherein the reference color is selected as a reference color, the luminance value of the light emitting diode of the selected color is determined, and the transmittance for each pixel in the third subfield period is calculated. The display device according to claim 1.
In the N subfield periods, a light source of at least one color among the light sources of the plurality of colors is turned on, or in the N subfield periods, a light source of one color in one subfield period The display device according to any one of claims 1 to 4, further comprising mode switching means for switching whether the light sources of a plurality of colors are lit in a predetermined order so that only the lit operation is performed.