WO2018008720A1

WO2018008720A1 - Display device

Info

Publication number: WO2018008720A1
Application number: PCT/JP2017/024804
Authority: WO
Inventors: 正史屋鋪
Original assignee: シャープ株式会社
Priority date: 2016-07-07
Filing date: 2017-07-06
Publication date: 2018-01-11

Abstract

Provided is a display device that can realize greater diversity of display modes of images through backlight control, and that reduces power consumption. A display device 10 comprises: a light source 19; a display panel 11; a panel driving unit that outputs a signal that controls the transmittance of each pixel of the display panel 11; and a light source driving unit 16. At the time of a first operation mode, the panel driving unit outputs to the display panel 11 a signal that causes an image to be sequentially displayed in each of a plurality of sub field periods during one frame period, and the light source driving unit 16 switches the color of emitted light in each sub field period. At the time of a second operation mode, the panel driving unit outputs to the display panel 11 a signal that causes an image to be displayed without dividing one frame period into sub frame periods, and the light source driving unit 16 drives the light source using a different mode from that at the time of the first operation mode.

Description

Display device

The present application relates to a display device, and more particularly to a display device capable of realizing a variety of image display modes by backlight control.

For example, there is a display device including a backlight and a display panel that displays an image by modulating light of the backlight, such as a liquid crystal display device. In such a display device, technologies for realizing various display performances by controlling the turning on and off of the backlight in accordance with the timing of displaying an image have been developed.

As an example, Patent Document 1 below realizes color display by combining a backlight that can emit red, green, and blue light in a time-sharing manner with a liquid crystal panel, and synchronizing the switching of the liquid crystal element and the light emission of the backlight. A field sequential type liquid crystal display device is disclosed.

Further, Patent Document 2 below discloses that a field sequential liquid crystal display device is used in an electronic camera having a monitor screen capable of displaying a captured subject image. This liquid crystal display device uses a color display mode in which color display is performed by switching between lighting of backlights of R, G, and B colors and display of the liquid crystal shutter panel at high speed, and a liquid crystal shutter panel without lighting the backlight. It is possible to switch between a monochrome display mode for performing only display. Thereby, the electronic camera can operate with low power consumption even when the monitor screen is displayed.

Japanese Patent No. 3912999 JP 2003-60944 A

However, the display device described in Patent Document 2 performs field sequential display even in the black and white display mode in which the backlight is turned off. Therefore, an object of the present application is to reduce power consumption in a display device that can realize a variety of image display modes by backlight control.

In one embodiment of the present invention, the display device
A light source;
A light guide plate having an incident surface for light from the light source and an exit surface for emitting light from the light source that has entered from the incident surface;
A display panel that is provided so as to overlap the light exit surface of the light guide plate and displays an image by controlling the transmittance of incident light for each of a plurality of pixels;
Based on image data indicating an image to be displayed on the display panel, a panel drive unit that outputs a signal for controlling the transmittance of each pixel of the display panel to the display panel;
A light source driving unit for driving the light source;
A first generation unit configured to generate a plurality of subfield images to be displayed in each of a plurality of subfield periods obtained by dividing one frame period in accordance with the first operation mode based on the image data; An image processing unit including a second generation unit that generates an image for display without dividing one frame period in correspondence with the second operation mode;
The light source can emit a plurality of colors different from each other,
The light source driving unit drives the light source based on lighting control data for controlling a lighting state of the light source when displaying an image indicated by the image data;
In the first operation mode, the panel driving unit outputs a signal for sequentially displaying the images generated by the first generation unit to the display panel for each of a plurality of subfield periods in one frame period. The light source driving unit switches the color of light emitted every subfield period,
In the second operation mode, the panel drive unit outputs a signal for displaying the image generated by the second generation unit to the display panel, and the light source drive unit performs the first operation. This is a display device that drives the light source in a mode different from that in the mode.

According to the present disclosure, it is possible to realize a variety of image display modes by backlight control and to reduce power consumption.

FIG. 1 is a functional block diagram illustrating a configuration example of the display device according to the first embodiment. FIG. 2 is a diagram illustrating a configuration example of the backlight viewed from a direction perpendicular to the display surface. FIG. 3A is a cross-sectional view of a plane perpendicular to the display surface of the display device. FIG. 3B is a cross-sectional view of a surface perpendicular to the display surface of the display device. FIG. 4 is a diagram illustrating an example of a display image in the color display mode. FIG. 5 is a diagram illustrating an example of a transmitted light image display mode. 6 is a functional block diagram illustrating a detailed configuration example of the image processing unit of the display device illustrated in FIG. FIG. 7 is a diagram illustrating an example of an operation in the display device according to the first embodiment. FIG. 8 is a functional block diagram showing a detailed configuration example of the image data generation unit 44 shown in FIG. FIG. 9 is a diagram illustrating an example of a display image in the color display mode according to the second embodiment. FIG. 10 is a diagram illustrating an example of a transmitted light image display mode. FIG. 11 is a functional block diagram illustrating a configuration example of the image data generation unit in the third embodiment. FIG. 12 is a diagram illustrating an example of the operation in the monochromatic display mode in the display device according to the third embodiment. FIG. 13 is a diagram illustrating another example of the operation in the monochromatic display mode in the display device according to the third embodiment. FIG. 14 is a cross-sectional view illustrating a configuration example of the color filter type display device 10. FIG. 15 is a cross-sectional view illustrating a configuration example of a display device using the direct type backlight 41.

A display device according to a first configuration includes a light source, a light guide plate having a light incident surface from the light source, and an output surface that emits light of the light source that has entered from the incident surface, and the light guide plate Based on image data indicating a display panel provided on the exit surface and displaying an image by controlling the transmittance of incident light for each of a plurality of pixels, the display panel Based on the image data, a panel driving unit that outputs a signal for controlling the transmittance of each pixel to the display panel, a light source driving unit that drives the light source, and 1st operation mode. A first generation unit that generates a plurality of subfield images to be displayed in each of a plurality of subfield periods formed by dividing a frame period, and one frame period is not divided corresponding to the second operation mode. Show on And an image processing unit that includes a second generating unit that generates an image for. The light source can emit a plurality of colors different from each other, and the light source driving unit controls the light source based on lighting control data for controlling a lighting state of the light source when displaying an image indicated by the image data. To drive. In the first operation mode, the panel driving unit outputs a signal for sequentially displaying the images generated by the first generation unit to the display panel for each of a plurality of subfield periods in one frame period. Then, the light source driving unit switches a color to be emitted every subfield period. In the second operation mode, the panel drive unit outputs a signal for displaying the image generated by the second generation unit to the display panel, and the light source drive unit performs the first operation. The light source is driven in a mode different from that in the mode.

According to the first configuration, the display device has at least a first operation mode and a second operation mode. In the first operation mode, the image processing unit is configured to display a plurality of subfield images to be displayed in each of a plurality of subfield periods obtained by dividing one frame period based on the image data by the first generation unit. Is generated. That is, the display panel can be driven by a field sequential method. In the second operation mode, the second generation unit generates an image for display without dividing one frame period. In the first operation mode, the panel driving unit outputs a signal for sequentially displaying the images generated by the first generation unit to the display panel for each of a plurality of subfield periods in one frame period. Then, the light source driving unit switches a color to be emitted every subfield period. In the second operation mode, the panel drive unit outputs a signal for displaying the image generated by the second generation unit to the display panel, and the light source drive unit performs the first operation. The light source is driven in a mode different from that in the mode. Here, driving the light source in a mode different from that in the first operation mode includes turning off the light source.

According to this configuration, in the second operation mode, it is not necessary to generate input image data into a plurality of subfield images. In the first operation mode, frame rate conversion processing using a frame memory or the like is necessary for the input image data. Since this conversion process is unnecessary in the second operation mode, power consumption can be reduced. In addition, since the light source is driven in different modes in the first operation mode and the second operation mode, a variety of image display modes can be realized by backlight control.

In the display device according to the second configuration, in the first configuration, light can be transmitted through a back surface, which is a surface facing the emission surface of the light guide plate, and in the first operation mode. The display panel controls the transmittance of light incident on the display panel from the light source through the light exit surface of the light guide plate for each pixel based on a signal from the panel driving unit. In the second operation mode, the light source driving unit turns off the light source, and the display panel transmits the back surface of the light guide plate based on a signal from the panel driving unit. By controlling the transmittance of light incident on the display panel for each pixel, a transmitted light image including a transmissive region through which the rear of the display device can be seen is displayed.

In the second configuration, light can be transmitted through the back surface, which is the surface facing the light exit surface of the light guide plate. In the first operation mode, the display panel displays a color image by controlling the transmittance of light incident on the display panel from the light source through the exit surface of the light guide plate. In the second operation mode, the light source is turned off, and the transmitted light including a transmissive region through which the rear of the display device can be seen is controlled by controlling the transmittance of light that is transmitted through the back surface of the light guide plate and incident on the display panel. Display an image. Therefore, the color image display mode and the transmitted light image display mode can be switched by controlling turning on and off of the light source when displaying an image. As a result, a variety of image display modes can be realized in the display device. Further, since the frame rate conversion process is unnecessary in the second operation mode, the power consumption can be reduced.

In the display device according to the third configuration, in the first or second configuration, the image data further includes a gradation value of each pixel in the image to be displayed. The gradation value of the image data that causes the pixel to display white in the display of the color image corresponds to the gradation value of the transmittance at which light from the back of the light guide plate passes through the pixel in the display of the transmitted light image. It can be set as follows. Thereby, the region corresponding to white in the color image displayed when the light source is turned on becomes a transmissive region that can be seen through the back of the display device in the transmitted light image displayed when the light source is turned off. Therefore, an area corresponding to white in the display image is controlled by controlling turning on and off of the light source. It can be displayed in white or a transmissive region.

In the display device according to the fourth configuration, in addition to the second or third configuration, the image data generation unit is configured to display a subfield image of an image displayed by lighting a light source in the first operation mode. The generation process can be different from the generation process of the subfield image of the image displayed with the light source turned off in the second operation mode. Thereby, a subfield image suitable for a display image can be generated when the light source is turned on and off.

In the display device according to the fifth configuration, in addition to any one of the second to third configurations, the image data generation unit includes a subfield image corresponding to each of the plurality of colors of the light source, A subfield image corresponding to the mixed color of the plurality of colors may be generated. In this case, in the generation processing of the subfield image of the image displayed by turning on the light source, the image data generation unit uses the gradation value of the subfield image corresponding to each color as the gradation of the subfield image of the mixed color. A process of changing according to the value can be executed. In the processing of the subfield image of the image displayed with the light source turned off, the processing of changing the gradation value of the subfield image corresponding to each color according to the gradation value of the subfield image of the mixed color Can be configured not to execute.

With the above configuration, in color image display when the light source is turned on, subfield images corresponding to mixed colors are generated, and color gradation can be suppressed by changing the gradation values of the subfield images corresponding to each color. it can. In the display of the transmitted light image including the transmitted light region when the light source is turned off, the degree of transparency of the transmitted region can be improved by not changing the gradation value of the subfield image corresponding to each color.

In the display device according to the sixth configuration, in any one of the second to fifth configurations, the display panel includes a transmission region and a black region only when displaying an image when the light source is turned off. An optical image can be displayed. Thereby, the difference of the display mode of a color image and a transmitted light image can be enlarged. Therefore, for example, a display mode that draws attention is possible in the display device.

In the display device according to the seventh configuration, in any one of the second to sixth configurations, the light source driving unit causes the panel driving unit to display an image based on the same image data on the display panel. While the light source is on, the light source can be switched on and off. Accordingly, it is possible to switch between color display and transmitted light image display while displaying the content of the same image data. Therefore, two display modes are possible with the same content. For example, an eye-catching display mode is possible.

In the display device according to the eighth configuration, in the first configuration, in the second operation mode, the light source driving unit can light the light source in a single color. Here, “single color lighting” is not limited to each of a plurality of colors that the light source can emit, and by combining various lighting ratios of these colors, a single color image is displayed in the frame for the human eye. Means a lighting state in which is visually recognized. According to this configuration, since the light sources are driven in different modes in the first operation mode and the second operation mode, a variety of image display modes can be realized by backlight control. In the first operation mode, input image data requires frame rate conversion processing using a frame memory or the like, but in the second operation mode, this conversion processing is unnecessary. Power consumption can be reduced.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated. In addition, in order to make the explanation easy to understand, in the drawings referred to below, the configuration is shown in a simplified or schematic manner, or some components are omitted. Further, the dimensional ratio between the constituent members shown in each drawing does not necessarily indicate an actual dimensional ratio.

<Embodiment 1>
(Configuration example of display device)
FIG. 1 is a functional block diagram illustrating a configuration example of the display device according to the first embodiment. The display device 10 shown in FIG. 1 displays an image based on image data supplied from an external signal source 5. The display device 10 includes a display panel 11 and a backlight 12 including a light source 19 and a light guide plate 18. The light guide plate 18 guides light from the light source 19 to the display surface of the display panel 11. The display panel 11 is provided so as to overlap the light guide plate 18. The display panel 11 displays an image by controlling the transmittance of light incident on the display panel 11 for each of a plurality of pixels. In the present embodiment, as an example, the case where the display device 10 is a liquid crystal display device that controls the light transmittance for each pixel by controlling the alignment of the liquid crystal will be described.

As a control circuit for controlling the display panel 11 and the backlight 12, the display device 10 includes an image processing unit 4 that processes image data and outputs data for driving the display panel 11 and the backlight 12, and a display control circuit. 13, a gate driver 14, a source driver 15, and a backlight control circuit 16.

The display panel 11 includes m gate lines G1 to Gm, n source lines S1 to Sn, and (m × n) pixel circuits 17. The gate lines G1 to Gm are formed extending in the first direction (in the example of FIG. 1, the horizontal direction (lateral direction) of the display screen). The source lines S1 to Sn are formed to extend in a direction intersecting the first direction (in the example of FIG. 1, the vertical direction (vertical direction) of the display screen). The (m × n) pixel circuits 17 are provided corresponding to the intersections of the gate lines G1 to Gm and the source lines S1 to Sn, respectively. Note that the gate line can also be called a scan line, and the source line can also be called a data line or a signal line. The gate driver can also be called a scanning line driver circuit, and the source driver can be called a data line driver circuit.

The signal source 5 supplies the display device 10 with image data V1 indicating an image to be displayed every frame period. The image data V1 supplied to the display device 10 is input to the image processing unit 4. The image processing unit 4 processes the input image data V1 and outputs the processed image data V1 to the display control circuit 13, and controls the timing of displaying the image and lighting the light source 19 in the backlight 12.

Specifically, the display control circuit 13 controls the source driver 15 and the gate driver 14 based on the image data, and causes the display panel 11 to output a signal for controlling the transmittance of each pixel of the display panel 11. The display control circuit 13 outputs a control signal C1 and image data V2 to the source driver 15. The control signal C1 includes, for example, a source start pulse and a source clock. The source driver 15 drives the source lines S1 to Sn based on the control signal C2 and the image data V2. The display control circuit 13 outputs a control signal C 2 to the gate driver 14. The gate driver 14 drives the gate lines G1 to Gm based on the control signal C2. The control signal C2 includes, for example, a gate start pulse and a gate clock.

The gate driver 14 sequentially selects the gate lines G1 to Gm one by one at a timing according to the control signal C2. A selection voltage is applied to the selected gate line over one line period. The source driver 15 applies a source voltage corresponding to the image data V2 to the source lines S1 to Sn at a timing according to the control signal C1 over one line period. As a result, the source voltage corresponding to the image data V2 is written to each of the n pixel circuits 17 connected to the selected gate line. This operation is sequentially repeated for the gate lines G1 to Gm. As a result, the source voltage corresponding to the image data V2 in each pixel circuit 17 is written, and the transmittance of each pixel is controlled. The display panel 11 displays an image indicated by the image data V2.

As described above, the display control circuit 13, the gate driver 14, and the source driver 15 control the transmittance of each pixel of the display panel 11 based on the image data V 1 and V 2 indicating the image to be displayed on the display panel 11. The panel driving unit is configured to output a signal to the display panel 11.

Further, the image processing unit 4 outputs backlight data C3 indicating whether or not to turn on the light source 19 to the backlight control circuit 16. The backlight control circuit 16 controls turning on and off of the light source based on the backlight data C3. For example, the backlight control circuit 16 turns on the backlight 12 when the backlight data C3 is 1, and turns off the backlight 12 when the backlight data C3 is 0. The backlight control circuit 16 is an example of a light source driving unit that drives the light source 19.

In the present embodiment, a case where the display device 10 displays a color image by a field sequential method will be described as an example. In the field sequential method, a color image is displayed by displaying different color screens for each of a plurality of subfields obtained by dividing one screen display period, that is, one frame period. The backlight control circuit 16 switches the light emission color of the light source 19 in accordance with the timing when the display control circuit 13 displays sub-field images of different colors on the display panel 11 when displaying a color image.

The backlight control unit 16 can also control the state of the backlight 12 (for example, lighting or extinguishing) for each frame period, for example. For example, lighting control data indicating whether or not to turn on the backlight 12 when displaying the image indicated by the input image data V1 is received from the signal source 5, and one image is obtained based on the lighting control data. It is possible to control whether or not the backlight 12 is lit in one frame period to be displayed. Thus, as will be described later, the display device 10 operates in a color image display mode for displaying a color image and a transmitted light image display mode for displaying a monotone image including a transmissive area through which the back of the display device 10 can be seen. be able to.

The backlight 12 irradiates the back surface of the display panel 11 with light. FIG. 2 is a diagram illustrating a configuration example of the backlight 12 as viewed from a direction perpendicular to the display surface. In the example shown in FIG. 2, the backlight 12 is an edge light type. That is, the light source 19 is disposed so as to face the side surface (the lower side surface in the example of FIG. 2) of the light guide plate 18. The light source 19 is provided with, for example, RGB three-color light emitting diodes (LED: Light Emitting Diode). The light guide plate 18 is formed of a transparent material. The portion of the backlight 12 that overlaps the display screen of the display panel 11, that is, the display area where the pixels are arranged, is transparent. In FIG. 2, the light source 19 is disposed at a position facing one side surface of the light guide plate 18, but the light source 19 may be disposed at a position facing a plurality of side surfaces of the light guide plate 18.

3A and 3B are cross-sectional views of a plane perpendicular to the display surface of the display device 10. FIG. 3A shows an example of a state in which a transmitted light image including a transmissive region in which the backlight 12 is turned off and the back of the display device 10 can be seen is displayed. FIG. 3B shows an example of a state in which the backlight 12 is turned on to display a color image.

3A and 3B, the display panel 11 is provided at a position overlapping the backlight 12 in the direction perpendicular to the display screen. The display panel 11 includes two first and

second substrates

25 and 22 and a liquid crystal 24 provided therebetween. On one surface (for example, the surface opposite to the backlight 12) of the first substrate 25, gate lines G1 to Gm, source lines S1 to Sn, a pixel circuit 17, and the like are provided. A polarizing plate 26 is provided on the other surface of the first substrate 25. A common electrode (not shown) is formed on one surface of the second substrate 22 (for example, the surface on the backlight 12 side). A polarizing plate 21 is provided on the other surface of the second substrate 22. The first substrate 25 and the second substrate 22 can be formed of, for example, glass or resin.

The light guide plate 18 of the backlight 12 has an incident surface 18a for light from the

light source

19 and 18b for emitting light from the light source 19 that has entered from the incident surface 18a. The display panel 11 is provided so as to overlap the light exit surface 18 b of the light guide plate 18. That is, the backlight 12 is an illumination unit that irradiates one surface of the display panel 11 with light.

As shown in FIG. 3A, on the back surface 18c, which is the surface facing the exit surface 18b of the light guide plate 18, the display area on which the image of the display panel 11 is displayed, that is, the region overlapping the display screen, can transmit light. Yes. The backlight 12 is configured so that light can be transmitted through a portion overlapping the display screen of the display panel 11. For example, in the backlight 12, a member provided at a position overlapping in the direction perpendicular to the display area of the display panel 11 and the display screen is formed of a transparent material.

Specifically, a light guide plate 18 capable of transmitting light in a direction perpendicular to the display screen is disposed on the back surface of the display panel 11. That is, no member that shields light is disposed on the back surface of the display panel 11. A transparent material such as an acrylic plate is used for a member on the back side of the light guide plate 18, or nothing can be arranged on the back side of the light guide plate 18. With this configuration, in the pixel in which the liquid crystal 24 is controlled so that light is transmitted through the display panel 11, light transmitted from the back of the display device 10 through the back surface of the light guide plate 18 passes through the pixel of the display panel 11. Transparent to the front of the display screen.

As shown in FIG. 3B, the light guide plate 18 has a configuration in which light from the light source 19 propagating through the light guide plate 18 is easily emitted from the emission surface 18 b facing the display panel 11 toward the display panel 11. Yes. For example, dots (not shown) that reflect incident light can be formed at predetermined intervals on the exit surface 18 b and the back surface 18 c of the light guide plate 18. The light from the light source 19 that has entered from the incident surface 18 a of the light guide plate 18 travels while being totally reflected in the light guide plate 18. The light from the light source 19 that has entered the dots on the back surface 18 c of the light guide plate 18 is reflected by the dots and is emitted from the emission surface 18 b of the light guide plate 18 toward the display panel 11.

The dots are formed, for example, by printing with white opaque ink (such as organic ultraviolet curable ink) or metal ink (such as aluminum or gold). Further, instead of printing dots, the surface of the light guide plate 18 can be processed into a shape in which light is easily reflected by a die press or laser processing. In addition, the light guide plate 18 may be formed of a material that easily reflects light, without being limited to the form using the reflection due to the shape of the surface of the light guide plate 18. As described above, the light guide plate 18 may include a reflection structure that reflects light traveling inside and emits the light to the outside.

Thus, when the backlight 12 is turned on, the amount of light irradiated from the light source 19 through the light guide plate 18 to the display panel 11 passes through the back surface 18 b of the light guide plate 18 and reaches the display panel 11. More than For this reason, when the backlight 12 is turned on, the display panel 11 displays the color of the light from the backlight 12, and the back of the display device 10 is not seen through.

In the present embodiment, the display device 10 has a color display mode and a transmitted light image display mode. In the color display mode, the backlight 12 is turned on, and the display panel 11 displays a color image that does not include a transmissive area through which the back of the display device 10 can be seen. In the transmitted light image display mode, the backlight 12 is turned off, and the display panel 11 displays a monotone image (transmitted light image) including a transmissive area.

The display panel 11 displays an image by controlling the transmittance of light incident on the display panel 11 for each pixel based on the signal of the panel drive unit in both the color display mode and the transmitted light image display mode. To do. In the color display mode, that is, when the backlight 12 is turned on when displaying an image, the display panel 11 transmits light that propagates from the light source 19 through the light guide plate 18 and enters the display panel 11 through the emission surface 18b. Will control the rate. In the case of the transmitted light image display mode, that is, when the backlight 12 is turned off when displaying an image, the display panel 11 enters the display panel 11 through the back surface 18c of the light guide plate 18 from the outside of the display device 10. The transmittance of light to be controlled is controlled. Thereby, the transmitted light image including the transmissive region can be displayed. In the transmissive region, the back of the display device 10 can be seen through.

FIG. 4 is a diagram illustrating an example of a display image in the color display mode. FIG. 5 is a diagram illustrating an example of a transmitted light image display mode. In the example shown in FIG. 4, the region A1 is displayed in red, the region A2 is displayed in blue, the region A3 is displayed in yellow, the region A4 is displayed in white, and the region A5 is displayed in green. The display image shown in FIG. 5 includes a transmissive area A6 and an area A7 displayed in black. In the transmissive area A6, the object B1 behind the display device 10 can be seen through.

For example, in the color display mode, each RGB light emitted from the backlight 12 displays a color corresponding to the transmittance adjusted by the display panel 11. In the transmitted light image display mode, since the backlight 12 is turned off, light transmitted through the back surface of the light guide plate 18 is displayed in a pixel region having a sufficiently large transmittance, as in the region A6 of the image shown in FIG. Output to the front of the screen. Therefore, such a region becomes a transmissive region and the background of the display device 10 can be seen through. This can be achieved, for example, by arranging a light guide plate 18 that allows light from the outside of the display device 10 to be transmitted from the back side of the display panel 11. Note that the transmissive region is not limited to a pixel region having the highest transmittance. For example, a region of a pixel that is controlled to have a transmittance such that the rear can be seen through can be included in the transmissive region.

For example, in the color display mode, in the region of pixels where the transmittance of all the colors of RGB is sufficiently large (for example, the pixel having the maximum transmittance), the backlight 12 is not like the region A4 of the image shown in FIG. White is displayed by light. On the other hand, in the transmitted light image display mode, a pixel having a sufficiently high transmittance becomes a highly transparent transmission region. Therefore, for example, in the display device 10, in the image data V 1 input from the signal source 5, the gradation value region indicating “white” is displayed in white when the backlight is lit, and is transparent when the backlight is turned off. Can do. The transparent display is a state where the back surface of the display device 10 can be seen through. Thereby, for example, a color display can be performed when the backlight is turned on, and a monotone display including a transparent display area and a black (or gray scale) area can be performed when the backlight is turned off. In this way, the display modes possible with the display device 10 are diversified, so that the range of representation by images can be expanded.

(Detailed configuration example of the image processing unit)
FIG. 6 is a functional block diagram illustrating a detailed configuration example of the image processing unit 4 of the display device 10 illustrated in FIG. 1. In this example, the image processing unit 4 includes a coordinate generation unit 41, a determination unit 42, a separation unit 43, an image data generation unit 44, a backlight data generation unit 45, and a timing control unit 46.

The coordinate generation unit 41, the determination unit 42, and the separation unit 43 are circuits that detect the control information of the backlight 12 included in the input image data V1. Here, a case where information for controlling whether or not the backlight 12 is turned on every frame period is detected will be described. The image data V1 includes, for example, data for each of a plurality of pixels (for example, gradation values for each RGB of each pixel). The coordinate generation unit 41 generates data indicating the coordinates (X, Y) of each pixel in the input image data.

The coordinate generation unit 41 has, for example, a memory (register) that can be rewritten from the outside to hold the total number of horizontal pixels M and the total number of vertical lines N. The coordinate generation unit 41 increments the horizontal counter (variable) by 1 each time pixel data is input. When the horizontal counter becomes equal to M, the vertical line counter (variable) is incremented by 1 at the next pixel data input, and the horizontal counter is returned to 1. The coordinate generation unit 41 stores the values of the horizontal counter and the vertical counter as coordinate values (X, Y) when data of each pixel is input. Thereby, the coordinates (X, Y) of each pixel of the input image data V1 can be generated. In this example, the upper left pixel in the image indicated by the image data V1 is the origin, X is the horizontal direction, and Y is the vertical direction.

The determination unit 42 specifies data used as control information for the backlight 12 among a plurality of pixel data included in the image data. In the present embodiment, for example, a pixel value of specific coordinates (as an example, data of coordinates (0, 0)) in the image data is used as a value indicating control information of the backlight 12, that is, the backlight 12. Can be specified as control data. The control data of the backlight 12 is data indicating lighting / extinguishing (non-lighting) of the backlight 12. The determination unit 42 can notify the separation unit 43 of, for example, a value indicating whether the value of each coordinate is the gradation value of the image to be displayed or the control data of the backlight 12 as the determination value.

The image data may have a portion corresponding to the image display period and a portion corresponding to the blanking period. In this case, the control data of the backlight 12 can be included in a portion corresponding to the blanking period. One frame period is divided into an image display period and a blanking period. Correspondingly, the image data V1 for one frame period has a portion corresponding to the image display period and a portion for the blanking period. The portion corresponding to the image display period includes data (for example, gradation value) of each pixel corresponding to each pixel circuit 17. The portion corresponding to the blanking period includes control data of the backlight 12 indicating whether or not the backlight 12 is lit in the frame period.

The separation unit 43 separates the data indicating the image to be displayed from the image data V1 and the control data of the backlight 12 according to the determination by the determination unit 42. The separation unit 43 outputs data indicating an image included in the image data V1 to the image data generation unit 44, and outputs control data of the backlight 12 included in the image data V1 to the backlight data generation unit 45.

The image data generation unit 44 generates a plurality of subfield images to be displayed in each of a plurality of subfield periods obtained by dividing one frame period based on the input image data. For example, as display data for performing field sequential display from image data including gradation values of RGB colors in each pixel, each color of WRGB obtained by adding a mixed color W (white) to each RGB color A subfield image corresponding to is generated. The generated subfield image is output to the timing control unit 46.

Further, the backlight data generation unit 45 generates control data for causing the light source 19 of the corresponding color to emit light in the subfield period corresponding to each color of WRGB, and outputs the control data to the timing control unit 46. For example, the backlight data generation unit 45 and the timing control unit 46 simultaneously emit RGB light sources in the subfield period corresponding to W (white), and correspond to the R light source and G in the subfield period corresponding to R. Control is performed so that the G light source emits light during the subfield period and the B light source emits light during the subfield period corresponding to B.

Also, the backlight data generation unit 45 determines whether to turn on the backlight 12 for each frame based on control data indicating whether to turn on the backlight 12 when displaying the image indicated by the image data V1. The backlight data indicating is generated. For example, when the RGB gradation values (R, G, B) at coordinates (0, 0) included in the image data are larger than the threshold value, the backlight 12 is turned on during the frame period for displaying the image data. When (R, G, B) is smaller than the threshold value, the backlight data can be generated so that the backlight 12 is turned off during the frame period. When the maximum gradation indicated by the image data is 255 gradations, for example, the threshold value can be set to 128. In this case, when the gradation value is (0, 0, 0), the backlight data is instructed to turn off the backlight. When the gradation value is (255, 255, 255), the backlight is instructed to turn on the backlight. Write data can be generated. The generated backlight data is input to the image data generation unit 44 and the timing control unit 46.

In addition, the detection process of the control data of the backlight 12 is not limited to the above example. In the above example, the control data of the backlight 12 is included in the input image data V1, but the control data of the backlight 12 may be input separately in addition to the image data V1. For example, the control data of the backlight 12 can be input simultaneously with the image data V1 or in association with the image data V1. In this case, the image processing unit 4 inputs the control data to the backlight data generation unit 45 or the timing control unit 46 in synchronization with the image data V1 of one frame period or in association with the image data V1 of one frame period. can do.

The timing control unit 46 performs timing control to synchronize the display of each subfield image of WRGB and lighting of the WRGB backlight. In the field sequential display device 10, the backlight 12 includes a light source 19 that emits light of a plurality of colors, that is, RGB colors. The timing control unit 46 generates a timing control signal that synchronizes the timing of irradiating each of the RGB colors and their mixed color W with the timing of displaying the subfield images of each of the WRGB, and the display control circuit 13 and the backlight control circuit. 16 is output.

FIG. 7 is a diagram illustrating an example of the timing of image data input, subfield image display, and backlight 12 lighting on the display device 10. In the example shown in FIG. 7, the image data is input from the signal source 5 to the display device 10 every frame period at 60 Hz.

In the example shown in FIG. 7, in the frames F1 and F2, the backlight 12 is turned on to perform color display by field sequential driving (color display mode). On the other hand, in the frame F3, the backlight 12 is turned off, and transparent / monochrome display is performed (transmitted light image display mode).

In a frame that performs color display by field sequential driving as in frames F1 and F2, one frame period is divided into first to fourth subfield periods. In the first to fourth subfield periods, subfield images corresponding to the respective colors of WRGB are displayed. The first to fourth subfield periods are displayed at 240 Hz, that is, at a frequency that is four times the frequency of the image data.

In the first subfield period, the display control circuit 13 causes the gate driver 14 and the source driver 15 to output a signal based on the data of the subfield image of the mixed color W to the display panel 11, and the backlight control circuit 16 The light 12 is caused to emit RGB light sources simultaneously. Thereby, the mixed color W, that is, white light is emitted from the light source 19. In this way, the W (white) field is displayed in the first subfield period. In the second subfield period, the R (red) light source emits light to display the R (red) field, and in the third subfield period, the G (green) light source emits light to display the G (green) field. In the fourth subfield period, the B (blue) light source emits light and the B (blue) field is displayed.

On the other hand, in the frame F3 (transmitted light image display mode), the image is displayed at the same frequency (60 Hz) as the input image data while the backlight 12 remains off. In the transmitted light image display mode, in each pixel, the transmittance corresponding to any gradation between the gradation with the highest transmittance (total transparency) and the gradation with the lowest transmittance (black). Will display the image. Therefore, in the transmitted light image display mode, a black and white image (totally transparent-black image) including a transmissive area is displayed. In the transmitted light image display mode, the display device 10 can display, for example, a grayscale image between totally transparent and black. Alternatively, the display device 10 can also display a binary image including pixels that are completely transparent and black only.

In the transmitted light image display mode when the backlight is turned off, for example, a binary image can be displayed by setting the input image data V1 as a binary image. Alternatively, the input image data V1 can be converted into a binary image by the image processing unit 4 to display the binary image. In the latter case, the image processing unit 4 is configured so that the processing of the image data differs between the color display mode and the transmitted light image display mode. For example, the image processing unit 4 generates a color image generation unit that generates image data for displaying a color image based on the image data V1, and generates a transparent and black binary image based on the image data V2. A value image generating unit and a switching unit that switches between image data output of the color image generating unit and image data output of the binary image generating unit based on data for controlling lighting of the backlight can be used. .

(Detailed configuration example of the image data generation unit)
In the color display mode, the image data generation unit 44 performs a subfield image generation process for performing field sequential display, and in the transmitted light image display mode, the image data generation unit 44 is transparent for displaying at the same frame rate as the input image. / Generate monochrome image data. FIG. 8 is a functional block diagram showing a detailed configuration example of the image data generation unit 44 shown in FIG.

In the example illustrated in FIG. 8, the image data generation unit 44 includes a first generation unit 441 that generates a subfield image of an image to be displayed by lighting the light source 19 in the color display mode, and the light source 19 in the transmitted light image display mode. And a second generation unit 442 for generating an image to be displayed. The image data generation unit 44 further includes a switching unit 443. The switching unit 443 receives the backlight data output from the backlight data generation unit 45, and transfers the image data V1 to either the first generation unit 441 or the second generation unit 442 in accordance with the turning on / off of the backlight 12. Switch input. That is, the switching unit 443 sends the image data V1 of the frame in which the backlight 12 is turned on to the first generation unit 441, and sends the image data V1 of the frame in which the backlight 12 is turned off to the second generation unit 442.

The first generation unit 441 generates a subfield image corresponding to the mixed color W (white) in which RGB is mixed based on the gradation values of the RGB colors of the input image data V1. Further, the first generation unit 441 generates a subfield image corresponding to each RGB color based on the gradation values of each RGB color of the input image data V1. At this time, the first generation unit 441 changes the gradation value of each color of RGB in the image data V1 according to the gradation value of the subfield image of the mixed color W, and converts the gradation value of the subfield image of each color of RGB. It can be a gradation value.

The second generation unit 442 generates an image for transparent / monochrome display based on the gradation values of the RGB colors of the input image data V1.

As a specific example, the first generation unit 441 performs gradation values (Wout) corresponding to WRGB of display data as described below with respect to RGB gradation values (Rin, Gin, Bin) of input image data V1. , Rout, Gout, Bout) can be determined. In the following, min (Rin, Gin, Bin) represents a gradation value representing the lowest transmittance among RGB gradation values (Rin, Gin, Bin).
Wout = min (Rin, Gin, Bin) * α (0 ≦ α ≦ 1)
Rout = Rin-Wout
Gout = Gin-Wout
Bout = Bin-Wout

That is, the first generation unit 441 compares the gradation values (Rin, Gin, Bin) of each pixel in the input image data V1, and the lowest gradation value min (Rin, Gin, Bin) in each pixel. This is determined as the gradation value Wout of the mixed color W. Here, a gradation value lower than min (Rin, Gin, Bin) can be set as the gradation value Wout of the mixed color W. The first generation unit 441 subtracts the gradation value Wout of the mixed color W from the RGB gradation values (Rin, Gin, Bin) of each pixel in the image data V1 to obtain the gradation value of each RGB subfield. Calculate as

The second generation unit 442 can determine the brightness Y of the display data based on the RGB gradation values (Rin, Gin, Bin) of the input image data V1, for example, as follows. However, this is only an example.
Y = 0.183 * Rin + 0.614 * Gin + 0.062 * Bin + 16

According to the above configuration, in the color display mode in which the backlight 12 is turned on to display a color image, the subfield of the mixed color W is inserted, and the gradation of the RGB subfield is changed accordingly. , Color breakup (color breakup) can be reduced.

Note that generation of a subfield image suitable for the color display mode is not limited to the above example. For example, the first generation unit 441 can set a gradation value lower than the above-described min (Rin, Gin, Bin) as the gradation value of the mixed color W.

In the color display mode, since it is necessary to output the subfield image at 240 Hz for the input image data V1 (60 Hz), the frame rate is converted using the frame memory 446. That is, the image data output from the first generation unit 441 is written into the frame memory 446 by the frame memory writing unit 445. The frame memory reading unit 447 reads the image data from the frame memory 446 at 240 Hz and sends it to the timing control unit 46.

On the other hand, in the transmitted light image display mode, the same frame rate as that of the input image data V1 may be used, so that frame rate conversion processing using a frame memory is unnecessary. Thereby, power consumption can be further reduced.

<Embodiment 2>
FIG. 9 is a diagram illustrating an example of a display image in the color display mode according to the second embodiment. FIG. 10 is a diagram illustrating an example of a transmitted light image display mode. The image data V1 that is the basis of the display image of FIG. 9 and the display image of FIG. 10 is the same, and the backlight 12 is turned on in FIG. 9, and the backlight 12 is turned off in FIG. Therefore, in the example shown in FIG. 9, similarly to FIG. 4, the region A1 is displayed in red, the region A2 is displayed in blue, the region A3 is displayed in yellow, the region A4 is displayed in white, and the region A5 is displayed in green. In the display image shown in FIG. 10, the areas A1, A2, A3, and A5 are displayed in a gray scale corresponding to the RGB gradation values, and the area A4 is transparent. That is, the region A4 becomes a transmissive region, and the thing B1 behind the display device 10 can be seen through. In this example, an area that is “white display” when the backlight 12 is turned on is “transparent display” when the backlight 12 is turned off. Here, the gradation value for white display and the gradation value for transparent display both correspond to the gradation value that maximizes the transmittance of all the RGB colors.

As described above, in the present embodiment, the backlight control circuit 16 includes the backlight while the display control circuit 13 continuously displays images based on the same image data on the display panel 11 over a plurality of frame periods. 12 can be switched on and off.

For example, the display device 10 can receive input of image data V1 of a still image and control data of the backlight 12 corresponding to the still image. In this case, the display control circuit 13 causes the display panel 11 to display the same image data V1 image over a plurality of frame periods. In each of the plurality of frame periods, an instruction to turn on or off the backlight 12 in each frame period is output from the backlight control circuit 16 to the backlight 12.

In the display device 10 of the present embodiment, a light guide plate 18 that is transparent when the backlight 12 is turned off is disposed on the back surface of the liquid crystal 24, and a pixel region indicating “white” in the input image data is displayed in white when the backlight 12 is lit. When the backlight 12 is turned off, the display is transparent. In such a display device 10, the same content (the same image data is input to the display device 10) is used when the backlight 12 is turned on and when the backlight 12 is turned off. When the light 12 is turned off, an area that is displayed in white when the backlight 12 is turned on can be displayed transparently. Thereby, the eye catching effect can be enhanced.

In a conventional display device, color display is performed when the backlight is turned on, and when the backlight is turned off, the display is completely invisible or monochrome display. On the other hand, as in the present embodiment, in a display in which a region that is “white display” when the backlight is lit is “transparent display” when the backlight is turned off, the white display portion is transparent and the back of the display You can see the object in Thereby, for example, a digital signage using the display device 10 can produce an effect that enhances the eye catching effect.

In addition, in the image shown in FIG. 9, when the area A4 is moved up and down and left and right for display, the conventional display appears to simply move the white square. On the other hand, when the backlight 12 is turned off as in the present embodiment, the white display portion (A4) is transparently displayed, so that different portions on the back side that are shielded by the display device 10 (the transparent display moves). Thus, the visible area changes), and the production effect can be enhanced.

Also, as in the first embodiment, in the transmitted light image display mode, the same frame rate as the input image data V1 may be used, so that frame rate conversion processing using a frame memory is unnecessary. Thereby, power consumption can be further reduced.

<Embodiment 3>
Hereinafter, Embodiment 3 of the present invention will be described. In addition, about the member which has the same function as the structure demonstrated in each said embodiment, the same referential mark is attached and description is abbreviate | omitted.

The display device 10 according to the first embodiment and the second embodiment performs, as an operation mode, a color display mode in which the backlight 12 is turned on and field sequential driving is performed, and a transparent / monochrome display with the backlight 12 turned off. And a transmitted light image display mode to be performed.

On the other hand, the display device according to the third embodiment has a full-color display mode (same as the color display mode in the first and second embodiments) by operating the field sequential drive by turning on the backlight 12 as an operation mode. And a monochrome display mode.

The single color display mode is the same as the transmitted light image display mode of the first embodiment in that the output data for transparent / monochrome display described in the first embodiment is used, but the single color display mode is turned on without turning off the backlight 12. In this way, a monochrome image can be seen. However, “single color lighting” means a lighting state in which a monochrome image is visually recognized in the frame by human eyes by variously combining lighting ratios of the RGB light sources of the backlight 12. It does not mean that only one color of the RGB light source is lit. For example, when the R light source and the G light source are turned on simultaneously or in a time-division manner, yellow monochromatic light is visually recognized by human eyes. Such a state is also included in “single color lighting”.

Therefore, the display device according to the third embodiment is different from the display device 10 according to the first embodiment in that the image processing unit 6 illustrated in FIG. 11 is provided instead of the image processing unit 4 illustrated in FIG. ing.

As shown in FIG. 11, the image processing unit 6 of the display device according to the third embodiment includes a coordinate generation unit 41, a determination unit 62, a separation unit 43, an image data generation unit 44, a backlight data generation unit 65, and a timing control unit. 66.

The determination unit 62 identifies data used as control information for the backlight 12 among a plurality of pixel data included in the image data V1. In the present embodiment, for example, pixel values of predetermined specific coordinates (for example, data of coordinates (0, 0) and coordinates (1, 0)) in the image data are specified as control data of the backlight 12. can do. The control data of the backlight 12 is data indicating the lighting state of the backlight 12. The determination unit 42 can notify the separation unit 43 of, for example, a value indicating whether the value of each coordinate is the gradation value of the image to be displayed or the control data of the backlight 12 as the determination value.

The backlight data generation unit 65 generates backlight data indicating how to turn on the backlight 12 for each frame based on the control data of the backlight 12. For example, if the RGB gradation values (R, G, B) at coordinates (0, 0) included in the image data are larger than the threshold value, the backlight 12 is displayed in full color during the frame period for displaying the image data. When the corresponding lighting state is set and (R, G, B) is smaller than the threshold value, the backlight data can be generated so that the backlight 12 is lit in a single color during the frame period. When the maximum gradation indicated by the image data is 255 gradations, for example, the threshold value can be set to 128. In this case, when the gradation value is (0, 0, 0), backlight data instructing single color lighting, and when the gradation value is (255, 255, 255), lighting corresponding to full color display is instructed. Backlight data to be generated can be generated. The generated backlight data is input to the image data generation unit 44 and the timing control unit 66.

For example, in the full color display mode, the backlight data generation unit 65 and the timing control unit 66 simultaneously emit RGB light sources in the subfield period corresponding to W (white), and R in the subfield period corresponding to R. In the subfield period corresponding to G, the G light source is controlled to emit light in the subfield period corresponding to G, and the B light source is controlled to emit light in the subfield period corresponding to B.

On the other hand, in the single color display mode, the backlight data generation unit 65 and the timing control unit 66 can create an arbitrary color by variously combining the lighting ratios of the three light sources of RGB of the light source 19. For example, only one of R, G, and B light sources may be lit in the frame. Further, as shown in FIG. 12, in the frame F3 in the single color display mode, for example, by turning on only the R light source and the G light source, it is possible to realize yellow single color display. Alternatively, as shown in FIG. 13, for example, by turning on the R light source and the G light source alternately in a time division manner in the frame F 3 in the single color display mode, a yellow image can be visually recognized by the human eye. it can. In this way, an arbitrary single color can be created by combining various combinations of light sources displayed in each subfield. When the combinations of light sources and the variations of the respective lighting periods are diverse, the number of data used as control information for the backlight 12 among the data of a plurality of pixels included in the image data V1 is increased, or the image What is necessary is just to comprise so that the control data of a backlight may be input as data different from the data V1.

As described above, according to the present embodiment, in the full color display mode, the field sequential drive is performed at a frequency (240 Hz) that is four times the frequency (60 Hz) of the input image V1, whereas the single color is used. In the display mode, image display is performed at the same frequency as the input image V1.

Therefore, in the single color display mode, as in the transparent / monochrome display of the first embodiment, the frame rate conversion process using the frame memory is not necessary, and the power consumption can be reduced.

In the present embodiment, the display device having the full color display mode and the single color display mode has been described. However, the transmitted light image display mode described in the first and second embodiments may also be included as the operation mode. .

<Modification>
(Configuration example of direct type backlight)
The display device 10 can include a direct type backlight instead of the edge light type backlight 12 described above. FIG. 15 is a cross-sectional view showing a configuration example of a display device using a direct type backlight 41, which is a modification of the first and second embodiments. In the example shown in FIG. 15, the portion of the backlight 41 that overlaps the display area of the display panel 11 is transparent. The backlight 41 is configured using a transparent light source and a transparent substrate. As the transparent light source, for example, organic EL (Electroluminescence) or inorganic EL can be used. In addition, a substantially transparent LED backlight can be configured by arranging a large number of thin and small LEDs on a substrate such as glass or plastic to transmit light for transparent display. Examples of the configuration of the transparent substrate include a configuration in which the substrate itself is formed of a transparent material, and a configuration in which the substrate is configured with a thin film (for example, a thickness of several nm or less) so that light can be transmitted. It is done. As described above, the direct type backlight 4 having a transparent portion overlapping the display area of the display panel 11 can be used.

(Application examples other than liquid crystal display devices)
A display device to which the present invention can be applied is not limited to a liquid crystal display device. The present invention can also be applied to other display devices (display devices other than liquid crystal display devices) that include a lighting unit that irradiates light on one surface of the display panel and has a function of showing through the back of the display screen. it can. For example, the display panel includes a display panel including a plurality of shutter elements that are two-dimensionally arranged and capable of controlling an on state in which light is transmitted and an off state in which light is blocked for each pixel, and a backlight. The present invention can also be applied to a display device that switches an ON state and an OFF state of a shutter element in accordance with each bit of image data a plurality of times.

4 Image processing unit 10 Display device 11 Display panel 12 Backlight 13 Display control circuit 16 Backlight control circuit 18 Light guide plate 19 Light source

Claims

A light source;
A light guide plate having an incident surface for light from the light source and an exit surface for emitting light from the light source that has entered from the incident surface;
A display panel that is provided so as to overlap the light exit surface of the light guide plate and displays an image by controlling the transmittance of incident light for each of a plurality of pixels;
Based on image data indicating an image to be displayed on the display panel, a panel drive unit that outputs a signal for controlling the transmittance of each pixel of the display panel to the display panel;
A light source driving unit for driving the light source;
A first generation unit configured to generate a plurality of subfield images to be displayed in each of a plurality of subfield periods obtained by dividing one frame period in accordance with the first operation mode based on the image data; An image processing unit including a second generation unit that generates an image for display without dividing one frame period in correspondence with the second operation mode;
The light source can emit a plurality of colors different from each other,
The light source driving unit drives the light source based on lighting control data for controlling a lighting state of the light source when displaying an image indicated by the image data;
In the first operation mode, the panel driving unit outputs a signal for sequentially displaying the images generated by the first generation unit to the display panel for each of a plurality of subfield periods in one frame period. The light source driving unit switches the color of light emitted every subfield period,
In the second operation mode, the panel drive unit outputs a signal for displaying the image generated by the second generation unit to the display panel, and the light source drive unit performs the first operation. A display device that drives the light source in a mode different from that in the mode.
Light can be transmitted through the back surface, which is the surface facing the exit surface of the light guide plate,
In the first operation mode, the display panel has a transmittance of light incident on the display panel from the light source through the emission surface of the light guide plate based on a signal from the panel driving unit. Display color images by controlling each pixel,
In the second operation mode, the light source driving unit turns off the light source, and the display panel transmits the back surface of the light guide plate based on a signal from the panel driving unit. The display device according to claim 1, wherein a transmitted light image including a transmissive region through which the rear of the display device can be seen is displayed by controlling a transmittance of light incident on the pixel for each pixel.
The image data includes a gradation value of each pixel in the image to be displayed,
The gradation value of the image data that causes the pixel to display white in the display of the color image corresponds to the gradation value of the transmittance at which light from the back of the light guide plate passes through the pixel in the display of the transmitted light image. The display device according to claim 2.
The image data generation unit includes a generation process of a subfield image of the color image displayed in the first operation mode and a generation process of a subfield image of the transmitted light image displayed in the second operation mode. The display device according to claim 2, wherein the display device is made different.
The image data generation unit generates a subfield image corresponding to a mixed color of the plurality of colors in addition to the subfield image corresponding to each of the plurality of colors of the light source;
In the generation process of the subfield image of the image displayed in the first operation mode, a process of changing the gradation value of the subfield image corresponding to each color according to the gradation value of the subfield image of the mixed color Run,
In the processing of the subfield image of the image displayed in the second operation mode, the processing for changing the gradation value of the subfield image corresponding to each color according to the value of the subfield image of the mixed color is not executed. The display device according to any one of claims 2 to 4.
The display according to claim 2, wherein the display panel displays the transmitted light image including only the transmissive area and the black area when displaying an image in the second operation mode. apparatus.
7. The method according to claim 2, wherein the panel driving unit switches between the first operation mode and the second operation mode while displaying an image based on the same image data on the display panel. The display device described.
The display device according to claim 1, wherein, in the second operation mode, the light source driving unit turns on the light source in a single color.