JP2005077638A - Video display device and projection type display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To adjust a feeling of the brightness of a video without ruining the impression of the video. <P>SOLUTION: The video in the circumferential part of a screen is modulated to an extent larger than in the central part of the screen when the gradation of the video is modulated by signal processing. As a result, the information which is of principal importance for a viewer is expressed with high reproducibility and the feeling of the brightness of the screen can be adjusted in a simple manner. More specifically, the video signal in the circumferential part of the screen is modulated to a higher gradation side in a bright viewing and listening environment and the video signal in the circumferential part of the screen is modulated to a lower gradation side in a dark viewing and listening environment. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a video display device and a projection display device, and more particularly to a signal processing technique for adjusting a feeling of brightness of a video.

Various video signal correction techniques, such as an expansion processing technique (for example, Patent Document 1) for expanding the dynamic range of an image and a brightness value correction technique (for example, Patent Document 2) for correcting brightness, are available. Are known.
Japanese Patent Laid-Open No. 11-187284 JP 2003-162715 A

However, excessive application of signal processing can lead to degradation of display quality.
For example, when viewing a video using a projector, a method of expanding the video signal according to the ambient brightness can be considered as a method of improving the visibility of the video. In this case, if the expansion amount increases, the highlight portion May cause viewers to feel unnaturalness such as white-out or color changes. On the other hand, in a dark environment, if the image is too bright, it will warp and deteriorate the visibility of the image, so it is necessary to weaken the signal strength, but if the signal strength is excessively reduced, this will cause blackout, etc. As a result, the gradation expression is reduced, which also gives the viewer a sense of incongruity.

  The present invention has been made to solve the above-described problems, and provides a video display device and a projection display device that can adjust the brightness of the video without destroying the impression of the video. For the purpose.

The conventional signal correction technique performs uniform processing on the image in the screen. For example, in the case of adaptive signal processing that determines the correction amount of a video signal based on video information, a common correction level is determined for one entire screen based on the input video signal. However, when looking at the contents of the video, in many cases, the main members of the video are arranged in the center of the screen, and the viewer's line of sight is also directed to the center of the screen. That is, even if the image is similarly projected on the screen, the degree of impression given to the viewer differs depending on the position where the image is displayed.
On the other hand, recent research on the living environment (for example, Journal of Lighting Society Vol.87, No.2, p.105-p.112) It has been reported that it will lead to an improvement in brightness.
From such a background, the present inventor has obtained the following idea.

That is, in order to achieve the above object, the video display device of the present invention includes signal processing means capable of modulating the gradation of video by signal processing, and the signal processing means is provided at the screen center and the screen periphery. The video modulation amount (that is, the degree of image processing) is varied.
According to this configuration, priority is given to image quality at the center of the screen, and image processing is performed with emphasis on brightness adjustment rather than image quality at the periphery of the screen. Both reproducibility can be adjusted optimally. Specifically, the image at the periphery of the screen is greatly modulated compared to the center of the screen, so that the main information for the viewer can be expressed with high reproducibility and the brightness of the screen can be easily adjusted. Can do. In this case, in order to ensure the continuity of the image as a whole screen, it is desirable that the signal processing means changes the modulation amount of the image substantially continuously in the screen.

The signal processing means desirably sets the modulation amount of the video based on the brightness of the viewing environment.
As described above, the brightness of the video varies depending on the surrounding lighting conditions and the like. For example, a brighter display is required in a bright environment, but in a dark environment, an image that is too bright warps and deteriorates visibility. For this reason, for example, when viewing a video in a dark environment, it is possible to suppress a sense of brightness of the video by modulating the video signal at the periphery of the screen to the low gradation side. Conversely, when viewing a video in a bright environment, it is possible to increase the brightness of the video by modulating the video signal at the periphery of the screen to the high gradation side. In addition, when the screen peripheral area is brightened in this way, the boundary line becomes clearer due to the contrast effect with the area outside the screen, so that an effect of increasing the presence of the video can be expected.

The signal processing means preferably sets the modulation amount of the video based on the brightness of the video detected based on the video signal.
When the signal processing described above is performed based only on the brightness of the environment, color collapse may occur depending on the video. In particular, since the video at the periphery of the screen is greatly modulated as compared with the central portion of the screen, such color collapse may be manifested. For this reason, the brightness of the image is detected based on the video signal, and the modulation amount is adjusted based on the brightness information of the video so that the modulated video signal stays within a substantially displayable gradation range. Thus, deterioration of image quality can be prevented.

  Further, the signal processing means can set the modulation amount of the video based on the user's preference other than the brightness of the viewing environment and the brightness of the video. In this case, the user can input the modulation amount for both the peripheral portion of the screen and the central portion of the screen by an external input means such as a controller. The user can input only the other modulation amount. By doing so, it is possible to perform optimum settings for the user.

By the way, the following are mentioned as a concrete form of the above-mentioned signal processing.
(A) Multiply the video signal by a predetermined correction coefficient.
(B) A predetermined offset is added to or subtracted from the video signal.
(C) Apply tone curve modulation to the video signal.
(D) When each pixel constituting the video display area is composed of a plurality of dots of different hues including white display dots, the number of lighting white display dots or the brightness of each white display dot is adjusted. .

  In the forms (a) and (b), the degree of image processing, that is, the amount of video modulation is defined by the correction coefficient and the offset, respectively. On the other hand, in the form (c), the relationship between the input and the output is not necessarily linear, and the modulation amount of the video may change depending on the gradation level of the input signal. In the mode (d), the degree of image processing is defined by the number of white display dots that are turned on or the brightness of the white display dots.

According to another aspect of the present invention, there is provided a projection display apparatus comprising the above-described video display apparatus and a projection lens that projects an image formed by the video display apparatus.
According to this configuration, it is possible to realize a projection display with high reproducibility and excellent visibility.

[First Embodiment]
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a diagram showing a schematic configuration of a projection display apparatus according to the present invention, FIG. 2 is a block diagram showing the configuration of a drive circuit thereof, and FIGS. 3 to 8 are diagrams for explaining the drive method.
The projection display device according to the present embodiment is a three-plate projection color liquid crystal display device having a transmissive liquid crystal light valve for each color of R (red), G (green), and B (blue). FIG. 1 is a schematic configuration diagram showing the projection type liquid crystal display device, in which reference numeral 1 is an illumination device, 2 is a light source, 3 and 4 are fly-eye lenses (uniform illumination means), and 13 and 14 are dichroic mirrors. 15, 16 and 17 are reflection mirrors, 22, 23 and 24 are liquid crystal light valves (image display devices), 25 is a cross dichroic prism, and 26 is a projection lens (projection means).

  The illuminating device 1 in this Embodiment is comprised from the light source 2 and the fly eye lenses 3 and 4. FIG. The light source 2 includes a lamp 7 such as a high-pressure mercury lamp and a reflector 8 that reflects light from the lamp 7. Further, as uniform illumination means for making the illuminance distribution of the light source light uniform in the liquid crystal light valves 22, 23, 24 that are the illuminated areas, the first fly-eye lens 3 and the second fly-eye lens from the light source 2 side. 4 are installed sequentially. Here, the first fly-eye lens 3 forms a plurality of secondary light source images, and the second fly-eye lens 4 functions as a superimposing lens that superimposes them at the light valve position. In some cases, a condenser lens for superimposing the secondary light source image may be arranged at the position of the second fly-eye lens 4 or at the subsequent stage. Hereinafter, the case where the second fly-eye lens is used as the superimposing lens will be described.

The configuration of the latter stage of the lighting device 1 will be described below together with the operation of each component.
The dichroic mirror 13 of the blue light, green light reflection, transmits red light L _R of the light beam from the light source 2, is intended to reflect the blue light L _B and the green light L _G. The red light _{LR that} has passed through the dichroic mirror 13 is reflected by the reflection mirror 17 and enters the liquid crystal light valve 22 for red light. Meanwhile, among the color light reflected by the dichroic mirror 13, the green light L _G is reflected by the dichroic mirror 14 for reflecting green light, is incident on the green light liquid crystal light valve 23. On the other hand, the blue light L _B dichroic mirror 14 also passes through the relay lens 18, reflecting mirror 15, a relay lens 19, reflecting mirror 16, is incident on the liquid crystal light valve 24 for blue light through a relay system 21 comprising a relay lens 20 The

  The three color lights modulated by the liquid crystal light valves 22, 23 and 24 are incident on the cross dichroic prism 25. In this prism, four right-angle prisms are bonded together, and a dielectric multilayer film that reflects red light and a dielectric multilayer film that reflects blue light are formed in a cross shape on the inner surface. These dielectric multilayer films combine three color lights to form light representing a color image. The synthesized light is projected on a screen 27 by a projection lens 26 which is a projection optical system, and an enlarged image is displayed.

Next, a driving method of the projection type liquid crystal display device 30 of the present embodiment will be described.
FIG. 2 is a block diagram showing the configuration of the drive circuit of the projection type liquid crystal display device 30 of the present embodiment.
In the present embodiment, as shown in FIG. 2, the video signal input as an analog signal is input to a signal processing unit (signal processing means) 32 that is a digital signal processing circuit through an AD converter 31. The signal processing unit 32 determines the modulation amount of the video based on the brightness of the viewing environment, and the video signal is modulated into an appropriate gradation range according to the modulation amount. Here, the following three types of signal processing methods are conceivable.

(A) A method of multiplying a video signal by a predetermined correction coefficient (FIG. 3A).
In this method, the gradation of the output signal is linearly changed with respect to the gradation of the input signal. In this method, when the correction coefficient is larger than 1 (indicated by a solid line in the figure), the gradation range of the image is expanded to the high gradation side, and the image is brightened as a whole. On the contrary, when the correction coefficient is smaller than 1 (indicated by a dotted line in the figure), the gradation range of the image is compressed to the lower gradation side, and the image becomes dark overall.

(B) A method of adding or subtracting a predetermined offset to the video signal (FIG. 3B).
This method is a method of raising the overall gradation level of an image. In this method, when the offset is positive (indicated by a solid line in the figure), the gradation range of the image is shifted to the high gradation side, and the image is brightened as a whole. On the contrary, when the offset is negative (indicated by a dotted line in the figure), the gradation range of the image is shifted to the low gradation side, and the image becomes dark overall.

(C) A method of applying tone curve modulation to the video signal (FIG. 3C).
This method is a method of changing the gradation of the output signal nonlinearly with respect to the gradation of the input signal. Here, the “tone curve” refers to a curve representing a change in output gradation with respect to input when the input signal gradation is plotted on the horizontal axis and the output signal gradation is plotted on the vertical axis. The signal processing based on this is called tone curve modulation. In this method, for example, as indicated by a solid line in the figure, the tone curve is located above a straight line having a slope of 45 ° (indicated by a one-dot chain line in the figure) (for example, the tone curve has a slope on the low gradation side). In the case of an upwardly convex curve having a steep and gentle slope on the high gradation side), the gradation range of the image is expanded to the high gradation side, and the image is brightened as a whole. On the contrary, as shown by the dotted line in the figure, when the tone curve is located below the straight line having the inclination of 45 ° (for example, the tone curve has a gentle inclination on the low gradation side and an inclination on the high gradation side). In the case of a steep downward convex curve), the gradation range of the image is compressed to the lower gradation side, and the image becomes dark overall. In this tone curve modulation, the brightness and contrast of the video can be finely adjusted as compared with the method (a).

In the forms (a) and (b), the degree of image processing, that is, the amount of video modulation is defined by the correction coefficient and the offset, respectively. On the other hand, in the form (c), the relationship between the input and the output is not necessarily linear, and the modulation amount of the video may change depending on the gradation level of the input signal.
In this embodiment, a case where the method (a) is used as a signal processing method will be described.

  The video signal after the signal processing is converted again to an analog signal by the DA converter 37 and then input to the panel driver 38. The liquid crystal light valve 22 for red light (R panel in FIG. 2) from the panel driver 38, for green light It is supplied to each of the liquid crystal light valve 23 (G panel) and the blue light liquid crystal light valve 24 (B panel).

Here, as a method for determining the amount of video modulation, two methods, [1] display video non-adaptive type and [2] display video adaptive type, are conceivable depending on whether or not the signal processing is based on video information. Hereinafter, each method will be described.
[1] Display image non-adaptive control First, consider the case of non-adaptive control, that is, the case where the brightness of an image is controlled only by the brightness of the environment without depending on the image information.
In this case, the signal processing unit 32 first uses the two types of correction level curves A1 and A2 (including straight lines) as shown in FIG. 4 to correct the correction levels (correction coefficients) of the image at the screen center and the screen edge. a1 and a2 are set independently. This correction level curve defines the relationship between the viewing environment brightness L detected by an optical sensor or the like (not shown) and the image correction coefficient a. In these curves A1 and A2, it is defined that the correction coefficient a increases as the viewing environment becomes brighter (that is, L increases). Further, the slopes of the curves A1 and A2 are different, and the curve A1 is a gentler slope than the curve A2.

  When the correction coefficients a1 and a2 for the screen center and the screen edge are set in this way, the signal processing unit 32 sets the correction coefficient for the video area located in the middle as the intermediate value of the a1 and a2. Is done. At this time, the correction coefficient is set so as to change substantially continuously from the center of the screen to the end of the screen. In addition, in a video area at the center of the screen (for example, when the distance from the screen center to the screen edge is D, the distance from the screen center is about D / 2), the correction coefficient due to the movement of the spatial position The value of the coefficient is adjusted so that the correction coefficient greatly changes in the video area in the peripheral portion of the screen located around the change.

5 and 6 show the relationship between the video display position and the video correction coefficient. Note that (if the brightness L in FIG. 4 is greater than L ₀₎ when 5 to view images in a bright environment, the brightness L in the case (FIG. 4 FIG. 6 is to view images in a dark environment shows the relationship between them in small case) than L _0.

[2] Display video adaptive control Next, consider a case where adaptive control is performed, that is, brightness control adapted to a video signal is performed so as to prevent the occurrence of whiteout in a highlight portion and blackout in a dark portion. .
In this case, in the signal processing unit 32, first, the correction coefficient a1 of the video at the center of the screen is set based on the brightness of the viewing environment. Specifically, the correction coefficient a1 is set using a curve similar to the correction level curve A1 in FIG. Further, the correction coefficient a2 of the video at the edge of the screen is set based on the brightness of the video and the brightness of the viewing environment. Here, as a method for detecting the brightness of the image, for example, the following two methods are conceivable.

(A) A method of setting the number of gradations having the maximum brightness among the pixel data included in the frame of interest as the brightness of the video.
For example, a video signal including the number of gradations of 256 steps from 0 to 255 is assumed. When attention is paid to an arbitrary frame constituting a continuous video, it is assumed that the appearance number distribution (histogram) for each gradation number of pixel data included in the frame is as shown in FIG. In this figure, since the brightest number of gradations included in the histogram is 190, this number of gradations 190 is detected as the brightness of the video. This method is a method that can detect the brightness most faithfully to the input video signal.

(B) From the appearance number distribution (histogram) for each number of gradations included in the frame of interest, the number of gradations with a certain ratio (for example, 10%) with respect to the number of appearances is determined from the maximum brightness. How to make it bright.
For example, when the appearance number distribution of the video signal is as shown in FIG. 7B, an area of 10% is taken from the brighter side than the histogram. If the number of gradations corresponding to 10% is 230, the number of gradations 230 is the brightness of the video. When there is a sudden peak in the vicinity of the number of gradations 255 as in the histogram shown in FIG. 7B, the number of gradations 255 becomes the brightness of the image if the method (a) is adopted. . However, this sudden peak portion does not make much sense as information on the entire screen. On the other hand, the present method in which the number of gradations 230 is the brightness of the video can be said to be a method of determining by a region having meaning as information in the entire screen. In addition, you may change said ratio in about 2 to 50% of range.

When the brightness of the thus detected image and L _P, the correction coefficient a2 of the image of the correction coefficient a1 and the screen edge portion of the image of the screen center on the basis of the brightness of the image is set. Here, the setting method is divided into two types according to the brightness L of the environment.
For example, when viewing a video in a bright environment (when brightness L is greater than L ₀ in FIG. 4),
a1 = 255 / _{L P
a2 = b * 255 / L P} ( where b> 1)
The correction coefficient is set as follows. At this time, L _P sets a lower limit value I as shown in FIG. 8A, and if L _P ≧ I, it is possible to avoid an image from appearing unnatural due to excessive decompression processing. it can.
The case of viewing an image in a dark environment in the reverse (when the brightness L in FIG. 4 is smaller than L _0), and a small range of values than the correction coefficient a1 center of the screen correction coefficient of the screen end To do. In particular,
a1 = I / _{L P
a2 = b * I / L P} ( where b <1)
Here, I is the lower limit value of the brightness of the image for which gradation correction is performed as shown in FIG. 8B, and it is possible to avoid blackout of the image due to excessive correction.

When the correction coefficients a1 and a2 for the screen center and the screen edge are set in this way, the signal processing unit 32 sets the correction coefficient for the video area located in the middle as the intermediate value of the a1 and a2. Is done. At this time, the correction coefficient is set so as to change substantially continuously from the center of the screen to the end of the screen. In addition, the coefficient value is adjusted so that the change in the correction coefficient due to the movement of the spatial position becomes substantially zero in the video area at the center of the screen, and the correction coefficient greatly changes in the video area at the periphery of the screen.
By performing image processing based on the brightness information of the video in this way, it is possible to avoid color collapse at the periphery of the screen as much as possible.

[3] Control from outside Enables the user to control the correction coefficients of the image at the center of the screen and the periphery of the screen according to his / her preference. In this case, the configuration may be such that the user directly specifies the value of the correction coefficient by a numerical value using an external input means such as a controller, or may be configured to select the value of the correction coefficient from among several options. . At this time, it is also possible to input the modulation amount for both the screen center portion and the screen edge portion, and one of these is specified by the method [1], [2], and the other is used. The user may input the information.
By enabling the user to finely adjust the brightness in this way, optimal settings for the user can be performed.

As described above, in the present embodiment, the degree of image processing is different between the central portion of the screen and the peripheral portion of the screen, and the brightness of the video is adjusted mainly by the gradation change of the video in the peripheral portion of the screen. The main information can be expressed with high reproducibility.
In the present embodiment, since the image correction coefficient is changed substantially continuously from the center of the screen to the edge of the screen, the continuity of the image in the screen is not impaired.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIGS.
FIG. 9 is a diagram showing a schematic configuration of the video display device of the present invention, FIG. 10 is an enlarged diagram showing the configuration of one pixel, (a) is a sectional view thereof, and (b) is a plan view thereof. It is. FIG. 11 is a block diagram showing the configuration of the main part of the drive circuit, and FIG. 12 is a diagram for explaining the drive method. In this embodiment, FIG. 4 is used.

The video display device of this embodiment is a color liquid crystal display device including a color filter array on one substrate. The liquid crystal display device 50 includes a TFT array substrate 40, a counter substrate 44, and a liquid crystal layer 43 as a light modulation layer held between the substrates 40 and 44.
On the TFT array substrate 40, a plurality of pixel electrodes 41 made of ITO or the like are arranged in a matrix. In the present embodiment, four pixel electrodes 41 in one pixel P, that is, red, correspond to color filters of R (red), G (green), B (blue), and W (white), which will be described later. The pixel electrode 41r, the green pixel electrode 41g, the blue pixel electrode 41b, and the white pixel electrode 41w are juxtaposed. That is, in this embodiment, one pixel P is composed of 4 dots of R, G, B, and W. An alignment film 42 made of polyimide or the like is provided on the substrate 40 so as to cover these pixel electrodes 41 (41r, 41g, 41b, 41w). In FIG. 9 and FIG. 10, illustrations of switching elements, scanning lines, signal lines, and the like for performing energization control of the pixel electrodes 41 are omitted.

  The counter substrate 44 is configured as a color filter array substrate, and four types of color filters 45 (45r, 45g, 45b, 45w) of R, G, B, and W are juxtaposed on the substrate 44. A common electrode 38 made of ITO or the like is provided on the entire surface of the substrate 44 so as to cover the color filter 45, and an alignment film 39 made of polyimide or the like is further provided so as to cover the common electrode 38. .

Next, a driving method of the liquid crystal display device 50 of the present embodiment will be described with reference to FIG.
In the present embodiment, a video signal input as an analog signal is input to a signal processing unit (signal processing means) 60 that is a digital signal processing circuit via an AD converter (not shown). In the signal processing unit 60, a video modulation amount is determined based on the brightness of the viewing environment, and the video signal is modulated into an appropriate gradation range according to the modulation amount.
In the present embodiment, in order to more easily control the brightness of the video, the video signals of all dots of R, G, B, and W are not modulated, but only the video signals of W dots are modulated. Here, as the method for determining the video modulation amount, there are two methods, the display video non-adaptive method and the display video adaptive method, as in the first embodiment. That is, the case of a display video non-adaptive type is described.

In the present embodiment, a method similar to that in the first embodiment is used when obtaining the modulation amount of the white image. That is, the signal processing unit 60 first obtains the correction coefficients a1 and a2 of the white image at the center of the screen and the edge of the screen independently using two types of correction level curves A1 and A2 as shown in FIG. Then, the correction coefficient of the video region located between these is set as an intermediate value between these correction coefficients a1 and a2. At this time, the correction coefficient is set so as to change substantially continuously from the center of the screen to the end of the screen. In addition, the coefficient value is adjusted so that the change in the correction coefficient due to the movement of the spatial position becomes substantially zero in the video area in the center of the screen, and the correction coefficient greatly changes in the video area in the peripheral area of the screen located around it. .
FIG. 12 shows the relationship between the video display position and the number of gray levels of the white image. Note that FIG. 12 shows the relationship between them in the case (if the brightness L in FIG. 4 is greater than L ₀₎ to view images in a bright environment.

The W dot video signal thus modulated is converted again to an analog signal by a DA converter (not shown), then input to the panel driver 61 and supplied from the panel driver 61 to the W dot. Note that the video signals of the R, G, and B dots are not modulated by the brightness of the environment.
As described above, in this embodiment, the modulation amount of the W dot image is made different between the center portion of the screen and the peripheral portion of the screen, and the brightness of the image is adjusted mainly by the gradation change of the W dots in the peripheral portion of the screen. Therefore, it is possible to express the main information for the viewer with high reproducibility. In the present embodiment, since the image correction coefficient is changed substantially continuously from the center of the screen to the end of the screen, the continuity of the image in the screen is not impaired.

  In this embodiment, the brightness of the image is adjusted by adjusting the gradation of each W dot. Instead, the brightness is adjusted by adjusting the number of W dots that are turned on (the amount of insertion of W dots). May be performed. In this case, the number of W dots to be lit is different between the screen center and the screen periphery. At this time, the continuity of the video can be ensured by changing the number of W dots that are lit up substantially continuously from the center of the screen to the end of the screen.

In addition, this invention is not limited to the above-mentioned embodiment, It can implement in various deformation | transformation in the range which does not deviate from the meaning of this invention.
For example, in the first embodiment, an example in which a transmissive liquid crystal light valve is used as the projection display device has been described. However, the technical scope of the present invention is not limited to such a transmission type. For example, a projection type display device using a reflective projection display device such as LCOS, or a mirror type spatial light modulation device based on MEMS technology. The present invention can also be applied to a display device.
Similarly, in the second embodiment, a liquid crystal display device has been exemplified as a video display device. However, the present invention is not limited to this, and a self-luminous display device such as an electroluminescence display device, an electrophoretic display device, or the like. It is also possible to apply to a reflection type display device or the like. Further, the pixel structure shown in the second embodiment is merely an example. In the present invention, if the pixels constituting the video display area are composed of a plurality of dots of different hues including white display dots (W dots). As long as the configuration includes such W dots, the configuration is not limited to the above-described 4-dot configuration.

The figure which shows schematic structure of the projection type display apparatus which concerns on 1st Embodiment of this invention. The block diagram which shows the structure of the drive circuit of a projection type display apparatus similarly. The figure for demonstrating the drive method of a projection type display apparatus similarly. The figure for demonstrating the drive method of a projection type display apparatus similarly. The figure for demonstrating the drive method of a projection type display apparatus similarly. The figure for demonstrating the drive method of a projection type display apparatus similarly. The figure for demonstrating the drive method of a projection type display apparatus similarly. The figure for demonstrating the drive method of a projection type display apparatus similarly. Sectional drawing which shows schematic structure of the video display apparatus which concerns on 2nd Embodiment of this invention. The figure which expands and shows the principal part of a video display apparatus. The block diagram which shows the structure of the drive circuit of a video display apparatus similarly. The figure for demonstrating the drive method of a video display apparatus similarly.

Explanation of symbols

22, 23, 24 ... liquid crystal light valve (video display device), 26 ... projection lens, 30 ... projection type display device, 32, 60 ... signal processing unit (signal processing means), 50. ..Video display devices

Claims (10)

Provided with signal processing means capable of modulating the gradation of video by signal processing,
The video display apparatus according to claim 1, wherein the signal processing means makes the modulation amount of the video different between the central portion of the screen and the peripheral portion of the screen.   2. The video display device according to claim 1, wherein the signal processing means modulates a video in a peripheral portion of the screen to be larger than that in a central portion of the screen.   The video display device according to claim 1, wherein the signal processing unit sets the modulation amount of the video based on brightness of a viewing environment.   4. The video display according to claim 1, wherein the signal processing unit sets the modulation amount of the video based on the brightness of the video detected based on the video signal. apparatus.   The video display device according to claim 1, wherein the signal processing unit changes the modulation amount of the video substantially continuously in a screen.   The video display device according to claim 1, wherein the signal processing is performed by multiplying the video signal by a predetermined correction coefficient.   6. The video display device according to claim 1, wherein the signal processing is performed by adding or subtracting a predetermined offset to the video signal.   6. The video display device according to claim 1, wherein the signal processing is performed by applying tone curve modulation to the video signal. Each pixel constituting the video display area consists of a plurality of dots of different hues including dots for white display,
6. The video display device according to claim 1, wherein the signal processing is performed by adjusting the number of lighting white display dots or the brightness of each white display dot. A projection display device comprising: the image display device according to any one of claims 1 to 9; and a projection lens that projects an image formed by the image display device.

Images