JP5391563B2 - Display device and display method - Google Patents

Description

  The present invention relates to a technique for displaying a color image.

  Some display devices that display color images include a liquid crystal panel. The liquid crystal panel performs display by blocking or transmitting external light or light emitted by a light source such as a front light or a backlight.

  As one of the display devices including the liquid crystal panel, a three-plate liquid crystal projector including three liquid crystal light valves corresponding to red (R), green (G), and blue (B) has been proposed (for example, Patent Document 1).

JP 2007-264245 A

  In the three-plate liquid crystal projector, a high-pressure mercury lamp is used to increase the brightness of the image. The high-pressure mercury lamp has a property that light intensity of green color light is higher than that of other color lights after color separation. For this reason, in a three-plate liquid crystal projector equipped with a high-pressure mercury lamp, the color balance of red, green, and blue is adjusted by reducing the amount of green light with a liquid crystal light valve.

  However, in the above-described conventional technique, when the amount of green light is adjusted with the liquid crystal light valve, the number of gradations that can be used for image modulation decreases, and the color reproducibility of the image of the projector deteriorates. In addition, since the liquid crystal panel is a hold-type display device, it has a problem that a moving image is blurred due to an afterimage. From both problems, the image quality of the video cannot be overlooked.

  The present invention has been made in order to solve at least a part of the above-described conventional problems. In the case of using a light source lamp that requires adjustment of color balance such as a high-pressure mercury lamp, color reproducibility is provided. The purpose is to achieve both prevention of deterioration of the image and suppression of motion blur.

SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention takes the form shown below .
One aspect of the present invention is:
A display device for displaying a color image,
A plurality of display panels corresponding to each color component of the color;
A plurality of frame memories for storing image data for one frame for each color component as frame image data of each color based on an input video signal;
One frame period of the video signal is divided into a plurality of subframe periods, and frame image data of each color stored in each frame memory is divided into the color in a first subframe period of the plurality of subframe periods. Output as drive image data for each component, and in the second sub-frame period of one frame period of the video signal, the entire display surface is displayed for each color component represented by a low gradation value as a black level. A driving image data generation unit that outputs black frame image data as driving image data for each color component;
A display panel driving unit for driving each of the plurality of display panels based on the driving image data for each color component;
With
The drive image data generation unit includes:
The black frame image data for a specific color component of the plurality of color components is divided into a specific area and a non-specific area, and the gradation value of the specific area is determined by removing the specific color component. A black level defining portion that is determined to be higher than the gradation value of the black frame image data of the color component;
The plurality of display panels are three display panels corresponding to red, green, and blue, respectively.
The specific color component is a red component,
The display device, wherein the specific region is a skin color region and is determined based on at least one of the plurality of frame image data.
In addition, the present invention can be realized as the following forms or application examples.

[Application Example 1]
A display device for displaying a color image, wherein a plurality of display panels corresponding to each color component of the color, and one frame of image data for each color component based on the input video signal A plurality of frame memories to be stored as data, and one frame period of the video signal is divided into a plurality of subframe periods, and stored in each frame memory in a first subframe period of the plurality of subframe periods The output frame image data of each color is output as drive image data for each color component, and in the second sub-frame period of one frame period of the video signal, the entire display surface has a low gray level as a black level. A driving image data generation unit that outputs black frame image data for each color component represented by a value as driving image data for each color component; and for each color component A display panel driving unit configured to drive each of the plurality of display panels based on the driving image data, and the driving image data generation unit includes the specific color component of the plurality of color components. A display device comprising: a black level defining unit that determines a gradation value of black frame image data higher than a gradation value of the black frame image data of other color components excluding the specific color component.

  According to the display device of Application Example 1, frame image data based on the video signal is displayed for each color component in the first subframe period in one frame period of the video signal, and within one frame period of the video signal. During the second sub-frame period, black frame image data whose entire display surface is represented by a low gradation value as a black level is displayed. Further, the gradation value of the black frame image data for a specific color component of the plurality of color components is set higher than the gradation value of the black frame image data of the other color components. For this reason, the light intensity of the color light for the specific color component can be increased. Increasing the gradation value of the black frame image data for this specific color component does not reduce the color reproducibility of the frame image data of each color displayed in the first subframe period. Therefore, even when using a light source lamp that requires color balance adjustment, the color reproducibility is prevented from deteriorating while adjusting the color balance by increasing the light intensity of a specific color component. Moving image blur can be suppressed.

[Application Example 2]
The display device according to application example 1 includes a high-pressure mercury lamp for irradiating the plurality of display panels, and the plurality of display panels include three display panels corresponding to red, green, and blue, respectively. And the specific color component is a red component and / or a blue component.

  As described above, a high-pressure mercury lamp has the property that green color light has a higher light intensity than other color lights. Therefore, projectors equipped with a high-pressure mercury lamp have a color balance of red, green, and blue. Is bad. On the other hand, in the display device of Application Example 2, the color balance can be adjusted by increasing the light intensity of the red component and / or the blue component.

[Application Example 3]
A display device for displaying a color image, wherein a plurality of display panels corresponding to each color component of the color, and one frame of image data for each color component based on the input video signal A plurality of frame memories to be stored as data, and one frame period of the video signal is divided into a plurality of subframe periods, and stored in each frame memory in a first subframe period of the plurality of subframe periods The output frame image data of each color is output as drive image data for each color component, and in the second sub-frame period of one frame period of the video signal, the entire display surface has a low gray level as a black level. A driving image data generation unit that outputs black frame image data for each color component represented by a value as driving image data for each color component; and for each color component A display panel driving unit configured to drive each of the plurality of display panels based on the driving image data, and the driving image data generation unit includes the specific color component of the plurality of color components. The black frame image data is divided into a specific area and a non-specific area, and the gradation value of the specific area is more than the gradation value of the black frame image data of other color components excluding the specific color component. A display device comprising a black level defining portion that is set high.

  According to the display device of Application Example 3, for each color component, frame image data based on the video signal is displayed in the first subframe period within one frame period of the video signal, and within one frame period of the video signal. During the second sub-frame period, black frame image data whose entire display surface is represented by a low gradation value as a black level is displayed. Further, the black frame image data for a specific color component of the plurality of color components is divided into a specific region and a non-specific region, and the gradation value of the non-specific region is a black frame of another color component. It is set higher than the gradation value of the image data. For this reason, it is possible to increase the light intensity of the color light for the specific region in the specific color component. Therefore, it is possible to positively increase the brightness of a specific area in a specific color component and to suppress moving image blur.

[Application Example 4]
The display device according to application example 3, wherein the specific region is determined based on at least one of the plurality of frame image data.

  In the display device according to the application example 4, it is possible to increase the luminance of the specific area determined from the image data for one frame of the video signal.

[Application Example 5]
The display device according to application example 4, wherein the plurality of display panels are three display panels corresponding to red, green, and blue, respectively, the specific color component is a red component, and the specific The display device is a skin color region.

  In the display device of Application Example 5, when the skin color area is determined in the image data for one frame of the video signal, the brightness of the skin color area can be positively increased.

  A display method as another application example is a display method for displaying a color video in a display device including a plurality of display panels corresponding to each color component of color, and (a) based on an input video signal, (B) storing one frame of image data for each color component as frame image data of each color; and (b) dividing one frame period of the video signal into a plurality of subframe periods, The frame image data of each color is output as drive image data for each color component in the first subframe period of the video signal, and the entire display surface is output in the second subframe period of one frame period of the video signal. Outputting black frame image data for each color component represented by a low gradation value as a black level as drive image data for each color component, and (c) the color component And driving each of the plurality of display panels based on the driving image data, wherein the step (b) includes the black frame image data for a specific color component of the plurality of color components. A step of determining a gradation value higher than a gradation value of the black frame image data of other color components excluding the specific color component.

  A computer program as another application example is a computer program for displaying a color video in a computer that controls a plurality of display panels corresponding to each color component. (A) Based on an input video signal, (B) a function of storing one frame of image data for each color component as frame image data of each color; and (b) dividing one frame period of the video signal into a plurality of subframe periods, The frame image data of each color is output as drive image data for each color component in the first subframe period, and the display surface is displayed in the second subframe period in one frame period of the video signal. The black frame image data for each color component represented as a whole by a low gradation value as a black level is used as the driving image for each color component. And (c) a function for driving each of the plurality of display panels based on the driving image data for each color component, the function (b) The gradation value of the black frame image data for a specific color component of the plurality of color components is higher than the gradation value of the black frame image data of other color components excluding the specific color component. A computer program having a function to be defined.

  According to the display method and the computer program, similarly to the display device of Application Example 1, it is possible to suppress motion blur due to black insertion while suppressing luminance reduction.

  A display method as still another application example is a display method for displaying a color video on a display device including a plurality of display panels corresponding to each color component, and (a) based on an input video signal, Storing image data for one frame for each color component as frame image data of each color; (b) dividing one frame period of the video signal into a plurality of subframe periods; The frame image data of each color is output as drive image data for each color component in the first subframe period, and the display surface is displayed in the second subframe period in one frame period of the video signal. (C) outputting the black frame image data for each of the color components represented as a low gradation value as a black level as drive image data for each of the color components; Driving each of the plurality of display panels based on driving image data for each component, wherein the step (b) includes the black frame for a specific color component of the plurality of color components. The image data is divided into a specific area and a non-specific area, and the gradation value of the specific area is set higher than the gradation value of the black frame image data of other color components excluding the specific color component. A display method comprising a process.

  A computer program as still another application example is a computer program for displaying a color video in a computer that controls a plurality of display panels corresponding to each color component. (A) Based on an input video signal A function of storing one frame of image data for each color component as frame image data of each color; and (b) dividing one frame period of the video signal into a plurality of subframe periods, and the plurality of subframe periods. The frame image data of each color is output as drive image data for each color component in a first subframe period of the image, and is displayed in a second subframe period of one frame period of the video signal. Driving the black frame image data for each color component represented by a low gradation value as the black level for the entire surface for each color component A function for outputting as image data; and (c) a function for driving each of the plurality of display panels based on the driving image data for each color component. The function (b) The black frame image data for a specific color component of the plurality of color components is divided into a specific area and a non-specific area, and the gradation value of the specific area is determined by removing the specific color component. A computer program comprising a function for determining a color component higher than a gradation value of the black frame image data.

  According to the display method and the computer program, as in the display device of Application Example 3, the luminance of the specific area in the specific color component can be positively increased, and moving image blur can be suppressed.

  The present invention can be realized in various application examples or forms other than those described above. For example, the present invention can be implemented as various types of apparatuses (for example, projectors) including the form of a system including a display device as an application example and the display apparatus as an application example. It can be realized in a form or the like.

Next, embodiments of the present invention will be described in the following order based on examples.
A. First embodiment:
A-1. Projector configuration:
A-2. Configuration of control unit:
A-3. Control processing procedure:
A-4. effect:
B. Second embodiment:
C. Other embodiments:

A. First embodiment:
A-1. Projector configuration:
FIG. 1 is an explanatory diagram showing a schematic configuration of a projector PJ in the first embodiment. The projector PJ includes a projection optical system OP for projecting an image on a screen (not shown) and a control unit CT that controls the projection light.

  The projection optical system OP is called a three-plate transmissive liquid crystal (3LCD) system, and includes three transmissive liquid crystal light valves 10r, 10g, and 10b. The liquid crystal light valves 10r, 10g, and 10b are of an active matrix type in which pixels are arranged in a matrix on a quartz substrate and thin film transistors (TFTs) formed of high-temperature polysilicon are provided on the pixels. The liquid crystal light valves 10r, 10g, and 10b correspond to the “display panel” of the present invention.

  The projection optical system OP homogenizes the white light beam from the light source lamp 20 by the illumination optical system 30 including the integrator and the polarization conversion optical system and aligns the polarization direction, and then performs R (red), G by the dichroic mirrors 40 and 50. (Green) and B (Blue) are separated into light beams Lr, Lg, and Lb of three colors, and the light beams Lr, Lg, and Lb are irradiated to the liquid crystal light valves 10r, 10g, and 10b corresponding to the respective colors. The light source lamp 20 is a high-pressure mercury lamp.

  The three liquid crystal light valves 10r, 10g, and 10b modulate the light beams Lr, Lg, and Lb of the three colors that have been irradiated using the driving signals Sr, Sg, and Sb of the respective colors sent from the control unit CT. To do. Thereby, light (image light) representing an image of each color is formed on the emission surface of each liquid crystal light valve 10r, 10g, 10b.

  The projection optical system OP further synthesizes the image light of each color by the dichroic prism 60 and projects it on a screen (not shown) by the projection lens 70. As a result, a color image having three colors R, G, and B as components is displayed on the screen.

  The projector PJ receives an input of the video signal AV from an external device such as a player, a video deck, or a personal computer. The control unit CT takes in the input video signal AV, and based on the video signal AV, the color of each of the above-described colors. Drive signals Sr, Sg, Sb are generated, and the drive signals Sr, Sg, Sb are output to the three liquid crystal light valves 10r, 10g, 10b. In this embodiment, the input video signal AV is an analog video signal indicating 60 frame images per second, and includes three components of R, G, and B.

A-2. Configuration of control unit:
FIG. 2 is a block diagram illustrating a configuration of the control unit CT. The captured video signal AV is input to the signal conversion circuit 102 and converted from an analog signal to a digital signal. The digital signal is written into the frame memories 110r, 110g, and 110b for each of R, G, and B components by the memory write control unit 104. Note that the frames are sequentially written into the frame memories 110r, 110g, and 110b in synchronization with the synchronization signal included in the video signal AV.

  The memory read control unit 112 stores image data for one frame of each color stored in the frame memories 110r, 110g, and 110b, that is, frame image data (R) FLr, frame image data (G) FLg, and frame image data ( B) FLb is read out at a double speed of a period (frame period) determined from the synchronization signal included in the video signal AV (that is, read out twice during one frame period). The read frame image data FLr, FLg, FLb is sent to the signal switching unit 120.

  The control unit CT includes a black frame image generation unit 130. The black frame image generation unit 130 generates black frame image data Kr, Kg, and Kb for each of R, G, and B color components. Here, “black frame image data” is image data represented by a low gradation value with the entire display surface as a black level. The black frame image generation unit 130 includes a black level defining unit 132 that determines which value the low gradation value is for each of the R, G, and B color components.

  Specifically, the black level defining unit 132 determines the gradation value at a value of 0, which is the lowest luminance value, for green (G) and blue (B). The red (R) has a value larger than the lowest luminance value, which is each of the gradation values of green (G) and blue (B), specifically, the gradation value distribution is 256 gradations of 0 to 255. Then, the gradation value is set to a value 25, which is about 10% of the value. That is, the black level defining unit 132 stores in advance that R is 25 and G and B are 0. Note that the gradation values of R, G, and B need not be limited to these values. Each gradation value is a low gradation value as a black level, and the gradation value of R is higher than the gradation values of G and B. Any value can be used as long as the value is high.

  The black frame image generation unit 130 reads the R, G, and B tone values stored in the black level defining unit 132, and generates black frame image data Kr, Kg, and Kb based on the tone values. As a result, the black frame image generation unit 130 includes R black frame image data Kr in which each pixel is represented by a value 25, G black frame image data Kg in which each pixel is represented by a value 0, B black frame image data Kb represented by a value 0 is generated. Each black frame image data Kr, Kg, Kb is sent to the signal switching unit 120.

  The signal switching unit 120 converts the frame image data FLr, FLg, FLb sent from the memory read control unit 112 and the black frame image data Kr, Kg, Kb sent from the black frame image generating unit 130 to the external One is selected for each color component based on a control command from a CPU 150 (described later), and the selected image data is output to the liquid crystal drive unit 140 as drive image data Dr, Dg, and Db.

  The control unit CT also includes a CPU 150 and a memory 160. The CPU 150 reads and executes the control program and various data (processing conditions, etc.) stored in the memory 160, thereby executing the memory write control unit 104, the memory read control unit 112, the signal switching unit 120, the black frame image. The operation of each block such as the generation unit 130 is controlled.

A-3. Control processing procedure:
The CPU 150 controls each block in the control unit CT by executing a control process according to a predetermined computer program stored in the memory 160. As a result, the control unit CT generates the drive image data Dr, Dg, Db by combining the frame image data FLr, FLg, FLb and the black frame image data Kr, Kg, Kb, and the drive image data Dr, Each of the liquid crystal light valves 10r, 10g, and 10b can be driven based on Dg and Db. The control process executed by the CPU 150 will be described in detail below.

  FIG. 3 is a flowchart showing a control process executed by the CPU 150. This control process is repeatedly executed in a half time (1/120 seconds) of one frame period of the video signal AV determined from the synchronization signal included in the video signal AV.

  As shown in the figure, when the processing is started, the CPU 150 causes the first half (1) of one frame period of the video signal AV (hereinafter, one frame period of the video signal AV is simply referred to as “one frame period”). / 120-60 / 120 seconds) or the latter half (61 / 120-120 / 120 seconds) is determined (step S10). Hereinafter, the first half of one frame period is referred to as “first subframe period”, and the second half of one frame period is referred to as “second subframe period”.

  If it is determined in step S10 that it is the first subframe period, the signal switching unit 120 is switched to the side for selecting the frame image data FLr, FLg, FLb sent from the memory read control unit 112 ( Step S20). As a result, in the first sub-frame period within one frame period, frame image data FLr, FLg, and FLb that are raw images are sent to the liquid crystal driving unit 140 as drive image data Dr, Dg, and Db. After the execution of step S20, the process returns to “Return” to end this control process once.

  On the other hand, if it is determined in step S10 that the second subframe period is within one frame period, the CPU 150 proceeds to step S30 and instructs the black frame image generation unit 130 to perform black processing. Instructs generation of frame image data Kr, Kg, Kb.

  Thereafter, the CPU 150 switches the signal switching unit 120 to the side for selecting the black frame image data Kr, Kg, Kb sent from the black frame image generation unit 130 (step S40). As a result, in the second sub-frame period of one frame period, the black frame image data Kr, Kg, Kb is sent to the liquid crystal driving unit 140 as drive image data Dr, Dg, Db. After the execution of step S40, the process returns to “Return” to end this control process once.

  FIG. 4 is a timing chart showing the time change of the image light of each color formed on the liquid crystal light valves 10r, 10g, and 10b according to the control process, together with the time change of various signals. FIG. 4A shows image lights of the liquid crystal light valves 10r, 10g, and 10b. FIG. 4B shows drive signals Sr, Sg, and Sb output from the liquid crystal drive unit 140. FIG. 4C shows R, G, and B signal components of the video signal AV. FIG. 4D shows black frame image data Kr, Kg, Kb output from the black frame image generation unit 130.

  In FIG. 4, T1 is the first frame period of the video signal. As shown in FIG. 4C, in the frame period T1, signal components (frame image data) R1, G1, B1 of each color for the first frame included in the video signal AV are input. As shown in FIG. 4B, in the first subframe period T1a in the frame period T1, the signal components R1, G1, and B1 are shortened to one half of the one frame period. And output as drive signals Sr, Sg, Sb. As a result, as shown in FIG. 4A, the image light of each color of the first frame included in the video signal AV is formed in each of the liquid crystal light valves 10r, 10g, and 10b.

  As shown in FIG. 4D, in the second subframe period T1b of the frame period T1, black frame image data Kr, Kg, Kb of each color is output from the black frame image generation unit 130. Each pixel of the R black frame image data Kr has a gradation value of 25, which is higher than the lowest luminance value of each pixel of the G and B black frame image data Kr, Kg, and Kb. . Then, as shown in FIG. 4B, the red drive signal Sr becomes R black frame image data Kr, the green drive signal Sg becomes G black frame image data Kg, and the blue drive signal Sb becomes B black frame image data Kb. As a result, as shown in FIG. 4A, image light of black frame image data Kr having a gradation value of 25 is formed on the R liquid crystal light valve 10r (the gradation value ratio in the figure is “ The G liquid crystal light valve 10g is formed with image light of the G black frame image data Kg having a gradation value of 0 (the gradation value is 0 in the figure). The B liquid crystal light valve 10b is formed with image light of B black frame image data Kb having a gradation value of 0 (shown that the gradation value is 0 in the figure). Shown with hatching to show).

  In FIG. 4, T2 is the second frame period of the video signal. In the frame period T2, as in the above-described period T1, in the first subframe period T2a, the R, G, B color components included in the video signal AV, that is, the raw frame image data FLr, FLg, FLb The image light is formed as it is on the liquid crystal light valves 10r, 10g, and 10b. In the second sub-frame period T2b, the image light of the black frame image data Kr, Kg, and Kb is supplied to the liquid crystal light valves 10r, 10g, and 10b. It is formed. Thereafter, although not shown in the figure, the image light of the frame image data Rn, Gn, Bn (n is an integer) and the image light of the black frame image data Kr, Kg, Kb are repeatedly formed in this order as the cycle progresses. .

  In the embodiment configured as described above, the frame memories 110r, 110g, and 110b correspond to the “frame memory” of the present invention, and the memory read control unit 112, the signal switching unit 120, the black frame image generation unit 130, and the liquid crystal drive. The unit 140 corresponds to the “driving image data generation unit” of the present invention, and the liquid crystal driving unit 140 corresponds to the “display panel driving unit” of the present invention.

A-4. effect:
As described above, according to the projector PJ of the present embodiment, a frame based on the video signal AV in the first subframe period of one frame period of the video signal AV for each of R, G, and B color components. Image data FLr, FLg, and FLb are displayed, and black frame image data Kr, Kg, and Kb are displayed in the second subframe period within one frame period of the video signal AV. Further, the gradation value of the black frame image data Kr for the red component is determined to be higher than the gradation values of the black frame image data Kg and Kb of the green component and the blue component, that is, the lowest gradation value (value 0). ing. For this reason, the light intensity of the colored light for the red component can be increased. Increasing the gradation value of the black frame image data Kr for the red component does not reduce the color reproducibility of the frame image data FLr, FLg, FLb of each color displayed in the first subframe period. Accordingly, it is possible to prevent deterioration of color reproducibility and suppress moving image blur while adjusting the color balance to improve the red component where the light intensity is weaker than that of the green component.

  As a modification of the first embodiment, the gradation values of the black frame image data Kb for the blue component instead of the red component are changed to the gradation values of the black frame image data Kr and Kg for the red component and the green component. That is, it may be configured to be higher than the lowest gradation value (value 0). According to this configuration, it is possible to adjust the color balance so that the blue component has a lower light intensity than the green component.

  Further, the gradation values of the black frame image data Kr and Kb for the red component and the blue component are set higher than the gradation value of the black frame image data Kg of the green component, that is, the lowest gradation value (value 0). It is good also as a structure. According to this configuration, it is possible to adjust the color balance to improve the red component and the blue component where the light intensity is weaker than the green component.

B. Second embodiment:
FIG. 5 is a block diagram illustrating a part of a control unit provided in the projector according to the second embodiment. In the figure, the black frame image generation unit 230 and its periphery are shown. Although omitted in the drawing, the second embodiment similarly includes components other than the black frame image generation unit 230 in the first embodiment. The same blocks as those in the first embodiment will be described below with the same numbers.

  The black frame image generation unit 230 includes a skin color area determination unit 232, an R black level definition unit 234, a G black level definition unit 236, and a B black level definition unit 238. Similarly to the first embodiment, the G black level defining unit 234 and the B black level defining unit 236 store the value 0 which is the lowest luminance value as the G and B gradation values.

  Unlike the G and B black level defining sections 234 and 236, the R black level defining section 234 does not store a single gradation value, but each gradation value for each pixel constituting the frame. Remember. The stored content is determined based on a control signal from the skin color area determination unit 232.

  The skin color area determination unit 232 performs processing for determining a skin color area from the frame image based on the frame image data FLr, FLg, FLb sent from the memory read control unit 112. There are various known methods for determining the skin color area, and the skin color area is determined from the frame image using these methods. As an example, R, G, and B pixel data are converted into HLS color system data, that is, hue (Sue) and saturation (Light) data, and hue (Hue). The skin color area is determined from the data. This is because the skin color belongs to a certain range in the hue (Hue) information. Here, when a plurality of flesh-colored pixels are combined and have a size equal to or larger than a predetermined value, the flesh-color pixel group is defined as a flesh-color area. The skin color region determination unit 232 sends position information representing the skin color region to the R black level defining unit 234 as the control signal.

  The R black level defining unit 234 divides the frame into a skin color region and a region other than the skin color region (hereinafter referred to as “non-skin color region”) based on the control signal, and determines the gradation value of the non-skin color region as G. , B is set to 0, which is the same as the tone value of B, and the tone value of the skin color region is set to a value higher than the tone values of G, B, in this case value 25. The tone values of the R skin color region, the R non-skin color region, and the G and B are not necessarily limited to these values. Each tone value is a low tone value as a black level, and the R skin color region. Any value may be used as long as the gradation value is higher than the gradation values of G and B. The R skin color region is preferably higher in value than the R non-skin color region.

  FIG. 6 is an explanatory diagram showing an example of a skin color area and R black frame image data Kr created based on the skin color area. FIG. 6A shows an example of a frame image obtained based on the frame image data FLr, FLg, FLb. FIG. 6B shows a skin color area P1 obtained by the skin color area determination unit 232 based on the frame image. FIG. 6C shows the R black frame image data Kr obtained by the R black level defining unit 234 based on the skin color region P1.

  As shown in FIGS. 6A and 6B, a skin portion such as a person's face and neck is determined as a skin color region P1, and as shown in FIG. R black frame image data Kr, each representing the non-skin color area P2 with a value of 0, is generated.

  As a result, in this embodiment, frame image data FLr, FLg, FLb based on the video signal AV is displayed in the first subframe period within one frame period of the video signal AV, and one frame period of the video signal AV is displayed. Black frame image data Kr, Kg, and Kb are displayed during the second subframe period. If the skin color region P1 is determined in the image data for one frame of the video signal, the skin color is displayed. The gradation value of the area corresponding to the area P1 is determined to be higher than the respective gradation values of the G and B black frame image data Kg and Kb, that is, the lowest gradation value (value 0).

  Therefore, according to the projector of the second embodiment, when the skin color area is determined in the image data for one frame of the video signal, the brightness of the skin color area can be actively increased, Moving image blur can be suppressed by insertion. As a result, it is possible to display an image with a skin beautifying effect.

  In addition, in the said 2nd Example, although it was the structure which determines a skin color area | region as a specific area, it is good also as a structure which determines a sky blue area | region as a specific area instead. In this case, the B black frame image data Kb is divided into a sky blue area and a non-sky blue area, and the gradation values for the sky blue area are the gradation values of the R and G black frame image data Kr and Kg. Set higher than. According to this configuration, it is possible to positively increase the brightness of the sky blue region and to suppress moving image blur by black insertion.

  In the above-described embodiment, the skin color area is determined using all of the frame image data FLr, FLg, and FLb. Instead, for example, the skin color area is roughly determined using only the R frame image data FLr. It is good also as a structure which determines. Even in the modification in which the sky blue area is the specific area, the sky blue area may be determined using all the frame image data FLr, FLg, and FLb, or the sky blue area may be determined using only the B frame image data FLb. It is good. Further, the specific area may be determined from the frame image data of two color components.

C. Other embodiments:
(1) In the first and second embodiments, the raw frame image data is displayed in the first subframe period in one frame period of the video signal AV, and the first frame period in the one frame period is displayed. However, instead of this, black insertion is performed in the first subframe period, and raw frame image data is displayed in the second subframe period. You may make it perform. Furthermore, a configuration may be adopted in which one frame period is divided into three (1/180 seconds) or four (1/240 seconds), and black insertion is performed in the divided one subframe period.

(2) In the first and second embodiments, the liquid crystal light valve as the display panel is a so-called transmissive light valve. However, instead of this, a reflective light valve may be configured. Further, the display panel is not limited to a liquid crystal panel such as a liquid crystal light valve, and a micromirror type light modulation device such as DMD (digital mirror device, registered trademark of TI) may be used.

(3) In each of the above embodiments, the image signal is represented by the video signals of the three primary colors R, G, and B, but it is not necessarily limited to the three primary colors, and the video signal is also represented by other color components. The present invention can be applied. A monochrome image may also be used. Furthermore, the present invention can also be applied to still image images instead of video signals that are moving images.

(4) The present invention is applicable to various color image display devices other than a projector. For example, the present invention can also be applied to a direct-view color image display device in which a supervisor directly views a display device, and a spatial image-type color image display device to observe an image formed in a space. Examples of the direct-view color image display device include a display for a computer, an in-vehicle small monitor, a viewfinder for a digital camera, and a display for a mobile phone. Further, as a spatial image type color image display device, there is a head mounted display.

  As mentioned above, although this invention was demonstrated based on the Example and the modification, Embodiment mentioned above is for making an understanding of this invention easy, and does not limit this invention. The present invention can be changed and improved without departing from the spirit and scope of the claims, and equivalents thereof are included in the present invention.

It is explanatory drawing which shows schematic structure of the projector PJ in 1st Example. It is a block diagram which shows the structure of control part CT. 3 is a flowchart showing a control process executed by a CPU 150. It is a timing chart which shows the time change of the image light of each color formed in liquid crystal light valve 10r, 10g, 10b according to the said control processing with the time change of various signals. It is a block diagram which shows a part of control part with which the projector in 2nd Example is equipped. It is explanatory drawing which shows an example of the skin color area | region P1, and the R black frame image data Kr produced based on the skin color area | region P1.

Explanation of symbols

 DESCRIPTION OF SYMBOLS 10b ... Liquid crystal light valve, 10g ... Liquid crystal light valve, 10r ... Liquid crystal light valve, 20 ... Light source lamp, 30 ... Illumination optical system, 40 ... Dichroic mirror, 60 ... Dichroic prism, 70 ... Projection lens, 102 ... Signal conversion circuit, 104 ... Memory write control unit, 110r ... Frame memory, 110g ... Frame memory, 110b ... Frame memory, 112 ... Memory read control unit, 120 ... Signal switching unit, 130 ... Black frame image generation unit, 132 ... Black level defining unit, 140 ... Liquid crystal drive unit, 150 ... CPU, 160 ... Memory, 230 ... Black frame image generation unit, 232 ... Skin color area determination unit, 234 ... R black level definition unit, 236 ... G black level definition unit, 238 ... B Black level defining part, P1 ... skin color area, P2 ... non-skin color area, PJ ... projector, O Projection optical system, CT ... Control unit, AV ... Video signal, FLr ... R frame image data, FLg ... G frame image data, FLb ... B frame image data, Kr ... R black level image data, Kg ... G black level image data, Kb ... B black level image data, Dr ... R drive image data, Dg ... G drive image data, Db ... B drive image data, Sr ... R control signals, Sg ... G control signal, Sb ... B control signal

Claims (2)

A display device for displaying a color image,
A plurality of display panels corresponding to each color component of the color image;
A plurality of frame memories for storing image data for one frame for each color component as frame image data of each color based on an input video signal;
One frame period of the video signal is divided into a plurality of subframe periods, and frame image data of each color stored in each frame memory is divided into the color in a first subframe period of the plurality of subframe periods. Output as drive image data for each component, and in the second sub-frame period of one frame period of the video signal, the entire display surface is displayed for each color component represented by a low gradation value as a black level. A driving image data generation unit that outputs black frame image data as driving image data for each color component;
A display panel driving unit that drives each of the plurality of display panels based on the driving image data for each color component;
The drive image data generation unit includes:
The black frame image data for a specific color component of the plurality of color components is divided into a specific area and a non-specific area, and the gradation value of the specific area is determined by removing the specific color component. A black level defining portion that is determined to be higher than the gradation value of the black frame image data of the color component;
The plurality of display panels are three display panels corresponding to red, green, and blue, respectively.
The specific color component is a red component,
The display device, wherein the specific region is a skin color region and is determined based on at least one of the plurality of frame image data. A display method for displaying a color image on a display device including a plurality of display panels corresponding to each color component of color,
(A) storing one frame of image data for each color component as frame image data of each color based on the input video signal;
(B) One frame period of the video signal is divided into a plurality of subframe periods, and the frame image data of each color is driven for each color component in a first subframe period of the plurality of subframe periods. Black frame image data for each color component that is output as image data and is represented by a low gradation value as the black level of the entire display surface in a second subframe period of one frame period of the video signal Output as driving image data for each color component;
(C) driving each of the plurality of display panels based on the driving image data for each color component, and
The step (b)
The black frame image data for a specific color component of the plurality of color components is divided into a specific area and a non-specific area, and the gradation value of the specific area is determined by removing the specific color component. A step of determining a color component higher than the gradation value of the black frame image data,
The plurality of display panels are three display panels corresponding to red, green, and blue, respectively.
The specific color component is a red component,
The display method, wherein the specific region is a skin color region and is determined based on at least one of the plurality of frame image data .

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