JP2007094171A - Image display control device, projection image display device, and rear projection image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the occurrence of a color break phenomenon without reducing the quantity of light, by controlling a light source driving frequency and a light valve driving frequency in accordance with a luminance level of an image signal. <P>SOLUTION: An image display control device 1 includes: a luminance level detection means 20 which detects the luminance level of the image signal; a light source driving circuit 21 which determines the light source driving frequency defining timings of successive emission of light in a plurality of colors from a light source in accordance with the detected luminance level and drives the light source with the determined light source driving frequency; and a light valve driving circuit which determines the light valve driving frequency defining timings, at which light emitted from the light source should be modulated in a light valve per pixel, in accordance with the detected luminance level and drives the light valve with the determined light valve driving frequency. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image display control device that performs control for displaying an image based on an input image signal, a projection image display device including the image display control device, a rear projection image display device, and the like.

  Conventionally, a light source that sequentially emits light of a plurality of colors (for example, R, G, B) at a predetermined lighting frequency (light source driving frequency), and light emitted by the light source at a predetermined refresh rate (light valve driving frequency) There is known an image display device including a light valve that modulates the pixel by pixel. Note that the lighting frequency and the refresh rate are synchronized (see Patent Document 1).

Further, in the conventional video display device, it is necessary to provide a certain non-lighting period (black display period) in the light source in consideration of the writing of the video signal to the light valve. Since the non-lighting time depends on the data transfer speed in the light valve, it is constant regardless of the lighting frequency of the light source and the refresh rate of the light valve.
JP 2002-189263 A

  However, such a conventional video display device has a problem that the color break phenomenon is visually recognized when the lighting frequency and the refresh rate are low. Here, the color break phenomenon refers to a phenomenon in which a rainbow pattern is seen in an image when subtitles are switched or a fast movement is followed.

  On the other hand, when the lighting frequency and refresh rate are increased, the color break phenomenon is not visually recognized, but the ratio of the black display period to the entire period increases, the amount of light emitted from the light source decreases, and the entire screen becomes dark. There was a problem of becoming.

  Further, the color break phenomenon has a feature that when an object moves while the entire screen is dark, it is easier to visually recognize than when an object moves while the entire screen is bright.

  Therefore, the present invention has been made in view of the above points, and by controlling the light source driving frequency and the light valve driving frequency according to the luminance level of the video signal, the occurrence of a color break phenomenon without reducing the light amount. An object of the present invention is to provide a video display control device capable of preventing the above, a projection display device including the video display control device, a rear projection display device, and the like.

  According to a first aspect of the present invention, there is provided a video display control apparatus that performs control for displaying a video based on an input video signal, a luminance level detection unit that detects a luminance level of the video signal, and a detection A light source driving frequency that defines a timing at which light of a plurality of colors is sequentially emitted from the light source is determined according to the brightness level, and a light source driving circuit that drives the light source at the determined light source driving frequency is detected. In accordance with the brightness level, a light valve driving frequency defining timing for modulating light emitted from the light source in a light valve in a pixel unit is determined, and the light valve is driven at the determined light valve driving frequency. And a light valve driving circuit.

  In the first aspect of the present invention, the light source driving circuit is configured to decrease the light source driving frequency when the luminance level increases and increase the light source driving frequency when the luminance level decreases. The light valve driving circuit may be configured to decrease the light valve driving frequency when the luminance level increases and increase the light valve driving frequency when the luminance level decreases. Good.

  According to this invention, when it is assumed that the luminance level of the video signal decreases and the screen becomes dark, the occurrence of the color break phenomenon is prevented by increasing the light source driving frequency and the light valve driving frequency. Can do.

  Further, according to this invention, when the luminance level of the video signal increases and the color break becomes difficult to be visually recognized, the screen can be brightened by reducing the light source driving frequency and the light valve driving frequency.

  In the first feature of the present invention, the light source driving circuit may drive the light source so as to increase a light amount per unit time of emitted light when the luminance level becomes a predetermined value or less.

  According to this invention, when it is assumed that the luminance level of the video signal is lower than the predetermined value and the screen is darkened, the screen is brightened by increasing the amount of light emitted from the light source per unit time. The occurrence of the color break phenomenon can be prevented.

  Also, in the first feature of the present invention, the light source driving circuit may drive the light source so as to reduce the light amount per unit time of the emitted light when the luminance level becomes a predetermined value or more. Good.

  According to this invention, when it is assumed that the brightness level of the video signal is equal to or higher than the predetermined value and the screen is brightened, the brightness of the screen is reduced by reducing the amount of light emitted from the light source per unit time. While maintaining, the occurrence of the color break phenomenon can be prevented.

  According to a second aspect of the present invention, there is provided a projection-type image display device including an image display control device that performs control for displaying an image based on an input image signal, wherein the image display control device includes: Luminance level detection means for detecting the luminance level of the video signal, and a light source driving frequency that defines the timing of sequentially emitting light of a plurality of colors in the light source according to the detected luminance level, and the determined light source A light source driving circuit that drives the light source at a driving frequency, and a light valve driving frequency that defines timing for modulating light emitted from the light source in a light valve in a pixel unit according to the detected luminance level. And a light valve driving circuit for driving the light valve at the determined light valve driving frequency.

  According to a third aspect of the present invention, there is provided a rear projection type video display device including a video display control device that performs control for displaying a video based on an input video signal. Luminance level detection means for detecting the luminance level of the video signal, and a light source driving frequency that defines the timing for sequentially emitting light of a plurality of colors in the light source according to the detected luminance level. A light source driving circuit that drives the light source at a light source driving frequency, and a light valve driving frequency that defines a timing for modulating light emitted from the light source in a light valve in a pixel unit according to the detected luminance level. And a light valve driving circuit that drives the light valve at the determined light valve driving frequency.

  As described above, according to the present invention, by controlling the light source driving frequency and the light valve driving frequency according to the luminance level of the video signal, it is possible to prevent the occurrence of the color break phenomenon without reducing the light amount. It is possible to provide a video display control device that can be used, a projection video display device including the video display control device, a rear projection video display device, and the like.

(Configuration of Video Display Device According to First Embodiment of the Present Invention)
With reference to FIGS. 1 to 3, the configuration of the projection display apparatus 1A according to the first embodiment of the present invention will be described.

  As shown in FIG. 1, a projection display apparatus 1A according to this embodiment includes an image display control apparatus 1, a light source 10, a cross prism 11, a rod integrator 12, polarizing plates 13A and 13B, and a liquid crystal panel. 14 and a projection lens 15.

  The light source 10 includes a light source (R) 10R that emits red light, a light source (G) 10G that emits green light, and a light source (B) 10B that emits blue light. For example, the light source 10 is a solid light source.

  The light source 10 is driven by a light source driving circuit 21 to be described later, and is configured to sequentially emit light of a plurality of colors (R, G, B) in a time division manner at a lighting frequency (light source driving frequency). Yes.

  Specifically, as shown in FIGS. 2 (a) and 3 (a), the light source 10 turns on the light source (R) 10R, the light source (G) 10G, and the light source (B) 10B in order. , Red, green, and blue light are sequentially emitted.

  The light source 10 is provided with a certain non-lighting period (black display period) in consideration of the writing of the video signal to the liquid crystal panel 14.

  Here, since the non-lighting time is constant irrespective of the lighting frequency of the light source 10 and the refresh rate of the liquid crystal panel 14, as shown in FIGS. 2B and 2C, the lighting frequency of the light source 10 is set. When the refresh rate of the liquid crystal panel 14 is large (see FIG. 2B), compared with the case where the lighting frequency of the light source 10 and the refresh rate of the liquid crystal panel 14 are small (see FIG. 2C), within a predetermined period. It is assumed that the amount of light emitted from the light source 10 decreases and the screen becomes dark.

  The cross prism 11 is an optical element configured to reflect the light emitted from the three light sources 10 (R), 10 (G), and 10 (B) and to enter the rod integrator 12.

  The rod integrator 12 is an optical element that integrates incident light so as to obtain a uniform light amount distribution on the exit surface by using the total reflection action on the inner surface of the rod integrator 12.

  The liquid crystal panel 14 is a light valve (or a spatial modulation element or an optical writing element) configured to modulate light (R, G, B) emitted from the light source 10 in units of pixels. The liquid crystal panel 14 is driven by a light valve driving circuit 22 described later at a refresh rate (light valve driving frequency).

  Here, the light emitted from the light source through the polarizing plate 13A enters the liquid crystal panel 14, and the image output from the liquid crystal panel 14 enters the projection lens 15 through the polarizing plate 13B and enters the screen ( (Not shown) is projected and displayed.

  In the present embodiment, the image display device includes a light source 10, a cross prism 11, a rod integrator 12, polarizing plates 13A and 13B, and a liquid crystal panel 14, and a projection optical system that projects light from the image display device. Is constituted by the projection lens 15.

  The video display control device 1 includes a luminance level detection unit 20, a light source driving circuit 21, and a light valve driving circuit 22.

  The luminance level detection means 20 is configured to detect the luminance level of the video signal input to the video display control device 1.

  For example, the luminance level detection means 20 is configured to detect the mode value of the luminance level in the entire screen of the input video signal as the luminance level (see FIGS. 4B and 4C). .

  Further, the luminance level detection means 20 may be configured to detect an average value of luminance levels in one entire screen of the input video signal as the luminance level.

  Further, the luminance level detection means 20 is configured to divide one screen of the input video signal into a plurality of areas and detect the maximum value and the minimum value of the luminance level in each of the divided areas as the luminance level. (See FIGS. 5B and 5C).

  The light source driving circuit 21 is configured to determine the lighting frequency used in the light source 10 according to the luminance level detected by the luminance level detecting means 20 and drive the light source 10 at the determined lighting frequency.

  The lighting frequency defines the timing at which the light source 10 sequentially emits light of a plurality of colors. In general, when the lighting frequency is low, it is considered that the color break phenomenon is more likely to occur than when the lighting frequency is high. In general, when an object moves while the entire screen is dark, the color break phenomenon is more likely to be visually recognized than when an object moves while the entire screen is bright.

  Therefore, the light source driving circuit 21 is configured to decrease the lighting frequency when the luminance level detected by the luminance level detecting means 20 increases, and increase the lighting frequency when the luminance level decreases.

  Further, the light source driving circuit 21 increases the light amount per unit time (peak light amount, instantaneous light amount) of the emitted light when the luminance level detected by the luminance level detection unit 20 becomes a predetermined value or less. The light source 10 may be configured to be driven.

For example, as shown in FIG. 3B, the light source drive circuit 21 sets the light amount per unit time of the emitted light to L ₀ when the luminance level detected by the luminance level detection means 20 becomes a predetermined value or less. From L to ₁ .

On the other hand, as shown in FIG. 3C, the light source drive circuit 21 sets the amount of emitted light per unit time to L ₀ when the luminance level detected by the luminance level detection means 20 is equal to or higher than a predetermined value. it may be configured to reduce the L ₂ from.

  The light valve driving circuit 22 is configured to determine a refresh rate used in the liquid crystal panel 14 according to the brightness level detected by the brightness level detecting means 20, and to drive the liquid crystal panel 14 at the determined refresh rate. Yes.

  The refresh rate defines the timing at which the light emitted from the light source 10 is modulated by the liquid crystal panel 14 and is synchronized with the lighting frequency of the light source 10.

  The light valve driving circuit 22 is configured to decrease the refresh rate when the luminance level detected by the luminance level detection means 20 increases, and increase the refresh rate when the luminance level decreases.

(Operation of the video display device according to the first embodiment of the present invention)
The operation of the projection display apparatus 1A according to the present embodiment will be described with reference to FIGS.

  First, referring to FIG. 4, the projection display according to the present embodiment in the case of controlling the lighting frequency of the light source 10 and the refresh rate of the liquid crystal panel 14 using the mode value of the luminance level in the entire screen. The operation of the device 1A will be described.

  As shown in FIG. 4A, in step S101, the luminance level detection means 20 detects the mode L of the luminance level in the entire screen of the input video signal as the luminance level of the input video signal. (See FIG. 4B).

  Specifically, as shown in FIG. 4C, the luminance level detecting means 20 detects the mode L of the luminance level by using the luminance level distribution in the entire screen of the input video signal. .

In step S102, the mode L of luminance level as compared with the first threshold value _{L A,} if the mode L the luminance level is less than the first threshold value _{L A,} the operation proceeds to step S103, luminance If the level of the mode L is larger than the first threshold value _{L a,} the operation proceeds to step S104.

In step S103, the light source driving circuit 21 changes the lighting frequency of the light source 10 to “f _A ”, and the light valve driving circuit 22 changes the refresh rate of the liquid crystal panel 14 to “f _A ”.

In step S104, the mode L of luminance level as compared to the second threshold value _{L C,} when the mode L brightness level is greater than a second threshold value _{L C,} the operation proceeds to step S105, luminance If the level of the mode L is smaller than the second threshold _{L C,} the operation proceeds to step S106.

In step S105, the light source drive circuit 21 changes the lighting frequency of the light source 10 to “f _C ”, and the light valve drive circuit 22 changes the refresh rate of the liquid crystal panel 14 to “f _C ”.

In step S106, the light source drive circuit 21 changes the lighting frequency of the light source 10 to “f _B ”, and the light valve drive circuit 22 changes the refresh rate of the liquid crystal panel 14 to “f _B ”.

  In order to realize the first operation, the light source driving circuit 21 and the light valve driving circuit 22 associate the “mode value L of the luminance level” and the “lighting frequency or refresh rate” shown in FIG. Remember the table.

  Second, referring to FIG. 5, one screen is divided into n × m areas, and the lighting frequency of the light source 10 and the liquid crystal panel 14 of the liquid crystal panel 14 are divided using the maximum and minimum luminance levels in each divided area. The operation of the projection display apparatus 1A according to this embodiment when controlling the refresh rate will be described.

As shown in FIG. 5A, in step S201, the luminance level detection means 20 divides one screen of the input video signal into n × m areas as the luminance level of the input video signal, and divides the screen. The luminance levels L _{11 to} L _nm in each of the areas thus detected are detected (see FIG. 5B).

  Specifically, as shown in FIG. 5C, the luminance level detection means 20 detects the mode L of the luminance level in each region using the distribution of luminance levels in each region.

Then, the luminance level detection means 20 detects the maximum value L _max and the minimum value L _min of the detected luminance level mode L in each area as the luminance level of the input video signal.

In step S202, the minimum value _{L min} of the luminance level as compared with the first threshold value _{L A,} if the minimum value _{L min} of the luminance level is less than the first threshold value _{L A,} the operation proceeds to step S203, luminance If the minimum value _{L min} of the level is greater than the first threshold value _{L a,} the operation proceeds to step S204.

In step S203, the light source drive circuit 21 changes the lighting frequency of the light source 10 to “f _A ”, and the light valve drive circuit 22 changes the refresh rate of the liquid crystal panel 14 to “f _A ”.

In step S204, the maximum value _{L max} of the luminance level as compared to the second threshold value _{L C,} when the maximum value _{L max} of the luminance level is greater than a second threshold value _{L C,} the operation proceeds to step S205, luminance If the maximum value _{L max} of the level is less than a second threshold value _{L C,} the operation proceeds to step S206.

In step S205, the light source drive circuit 21 changes the lighting frequency of the light source 10 to “f _C ”, and the light valve drive circuit 22 changes the refresh rate of the liquid crystal panel 14 to “f _C ”.

In step S206, the light source drive circuit 21 changes the lighting frequency of the light source 10 to “f _B ”, and the light valve drive circuit 22 changes the refresh rate of the liquid crystal panel 14 to “f _B ”.

In order to realize the second operation, the light source driving circuit 21 and the light valve driving circuit 22 perform “maximum value L _max or minimum value L _{min of} luminance level” and “lighting frequency or refresh” shown in FIG. A table that associates “rate” is stored.

  Third, referring to FIG. 6, the projection display according to the present embodiment in the case where the lighting frequency of the light source 10 and the refresh rate of the liquid crystal panel 14 are controlled using the mode value of the luminance level in the entire screen. The operation of the device 1A will be described.

  As shown in FIG. 6A, in step S301, the luminance level detection means 20 detects the mode L of the luminance level in the entire screen of the input video signal as the luminance level of the input video signal. (See FIG. 6B).

  Specifically, as shown in FIG. 6C, the luminance level detection means 20 detects the mode L of the luminance level using the luminance level distribution in the entire screen of the input video signal. .

In step S302, the mode L of luminance level as compared with the first threshold value _{L A,} if the mode L the luminance level is less than the first threshold value _{L A,} the operation proceeds to step S303, luminance If the level of the mode L is larger than the first threshold value _{L a,} the operation proceeds to step S304.

In step S303, the light source driving circuit 21 changes the lighting frequency of the light source 10 to “f _A ”, and changes the light amount (instant light amount) per unit time of the light emitted from the light source 10 to “L ₁ ”. The light valve drive circuit 22 changes the refresh rate of the liquid crystal panel 14 to “f _A ”.

In step S304, when the mode L of the luminance level is larger than the second threshold L _C as compared with the second threshold L _C , the operation proceeds to step S305, and the luminance If the level of the mode L is smaller than the second threshold _{L C,} the operation proceeds to step S306.

In step S305, the light source driving circuit 21 changes the lighting frequency of the light source 10 to “f _C ”, changes the light amount per unit time (instantaneous light amount) of the light emitted from the light source 10 to “L ₂ ”, The light valve drive circuit 22 changes the refresh rate of the liquid crystal panel 14 to “f _C ”.

In step S306, the light source driving circuit 21 changes the lighting frequency of the light source 10 to “f _B ”, changes the light amount per unit time (instantaneous light amount) of the light emitted from the light source 10 to “L ₀ ”, The light valve drive circuit 22 changes the refresh rate of the liquid crystal panel 14 to “f _B ”.

  In order to realize the third operation, the light source driving circuit 21 and the light valve driving circuit 22 perform the “brightness level mode L”, “lighting frequency or refresh rate”, and “instantaneous” shown in FIG. A table that associates “light quantity” is stored.

  Fourth, referring to FIG. 7, one screen is divided into n × m areas, and the lighting frequency of the light source 10 and the liquid crystal panel 14 of the liquid crystal panel 14 are divided using the maximum and minimum luminance levels in each divided area. The operation of the projection display apparatus 1A according to this embodiment when controlling the refresh rate will be described.

As shown in FIG. 7A, in step S401, the luminance level detection unit 20 divides one screen of the input video signal into n × m areas as the luminance level of the input video signal, and divides the screen. Luminance levels L _{11 to} L _nm in each of the areas are detected (see FIG. 7B).

  Specifically, as shown in FIG. 7C, the luminance level detection means 20 detects the mode L of the luminance level in each region using the distribution of luminance levels in each region.

Then, the luminance level detection means 20 detects the maximum value L _max and the minimum value L _min of the detected luminance level mode L in each area as the luminance level of the input video signal.

In step S402, when the minimum value L _min of the luminance level is smaller than the first threshold value L _A and the minimum value L _min of the luminance level is smaller than the first threshold value L _A , the operation proceeds to step S403, where the luminance value If the minimum value _{L min} of the level is greater than the first threshold value _{L a,} the operation proceeds to step S404.

In step S <b> 403, the light source driving circuit 21 changes the lighting frequency of the light source 10 to “f _A ” and also changes the light amount per unit time (instantaneous light amount) of the light emitted from the light source 10 to “L ₁ ”. The light valve drive circuit 22 changes the refresh rate of the liquid crystal panel 14 to “f _A ”.

In step S404, the maximum value _{L max} of the luminance level as compared to the second threshold value _{L C,} when the maximum value _{L max} of the luminance level is greater than a second threshold value _{L C,} the operation proceeds to step S405, luminance If the maximum value _{L max} of the level is less than a second threshold value _{L C,} the operation proceeds to step S406.

In step S405, the light source driving circuit 21 changes the lighting frequency of the light source 10 to “f _C ”, and also changes the light amount per unit time (instantaneous light amount) of the light emitted from the light source 10 to “L ₂ ”. The light valve drive circuit 22 changes the refresh rate of the liquid crystal panel 14 to “f _C ”.

In step S406, the light source driving circuit 21 changes the lighting frequency of the light source 10 to “f _B ”, and changes the light amount (instantaneous light amount) per unit time of the light emitted from the light source 10 to “L ₀ ”. The light valve drive circuit 22 changes the refresh rate of the liquid crystal panel 14 to “f _B ”.

In order to realize the fourth operation, the light source driving circuit 21 and the light valve driving circuit 22 perform “maximum luminance level L _max or minimum value L _min ” and “lighting frequency or refresh” shown in FIG. A table that associates “rate” with “instantaneous light intensity” is stored.

  In the above-described embodiment, the example in which the mode value is used as the luminance level has been described. However, the present invention is not limited to this, and can be applied to an example in which another value such as an average value is used as the luminance level. It is.

(Operation and effect of the video display device according to the present embodiment)
According to the projection display apparatus 1A according to the present embodiment, when it is assumed that the luminance level L of the video signal decreases and the screen becomes dark, the frequency of the light source 10 (light source driving frequency) and the liquid crystal panel ( By increasing the refresh rate (light valve driving frequency) of the light valve 14, it is possible to prevent the occurrence of a color break phenomenon.

  Further, according to the projection display apparatus 1A according to the present embodiment, when the luminance level L of the video signal increases and the color break becomes difficult to be visually recognized, the frequency of the light source 10 (light source driving frequency) and the liquid crystal panel (light The screen can be brightened by reducing the number of refresh rates (light valve driving frequency) of the bulbs 14.

  According to the projection display apparatus 1A according to the present embodiment, when it is assumed that the luminance level L of the video signal is equal to or lower than a predetermined value and the screen becomes dark, the light amount per unit time of the light emitted from the light source 10 By increasing the value, the screen can be brightened and the occurrence of the color break phenomenon can be prevented.

  According to the projection display apparatus 1A according to the present embodiment, when it is assumed that the luminance level L of the video signal is equal to or higher than a predetermined value and the screen is brightened, the light amount per unit time of the light emitted from the light source 10 By reducing the image quality, it is possible to prevent the occurrence of a color break phenomenon while maintaining the brightness of the screen.

(Modification 1)
The video display control device 1 according to the present invention may be applied to a virtual image type video display device 1B as shown in FIG.

  The virtual image display apparatus 1B has the same configuration as the projection display apparatus 1A according to the first embodiment, except that the virtual image optical system 16 is provided instead of the projection lens 15. . That is, the video display control device 1 provided in the virtual image type video display device 1B according to the present embodiment is the video display control device 1 provided in the projection type video display device 1A according to the first embodiment described above. It has the same function.

(Modification 2)
The video display control apparatus 1 according to the present invention may be applied to a direct view video display apparatus 1C as shown in FIG.

  Here, the video display control apparatus 1 provided in the direct view video display apparatus 1C according to the present embodiment is the video display control apparatus provided in the projection video display apparatus 1A according to the first embodiment described above. 1 has the same function.

(Modification 3)
The video display control device 1 according to the present invention may be applied to a rear projection video display device 1D as shown in FIG. As shown in FIG. 10, the rear projection type image display apparatus 1 </ b> D includes the projection type image display apparatus 1 </ b> A according to the first embodiment described above, a rear mirror 30, and a screen 31.

  In the rear projection display 1D according to the present embodiment, the image output from the projection display 1A is reflected by the rear mirror 30 and displayed on the screen 31.

  Although the present invention has been described in detail using the above-described embodiments, it is obvious to those skilled in the art that the present invention is not limited to the embodiments described in this specification. The present invention can be implemented as modified and changed modes without departing from the spirit and scope of the present invention defined by the description of the scope of claims. Therefore, the description of the present specification is for illustrative purposes and does not have any limiting meaning to the present invention.

1 is an overall configuration diagram of a video display device according to a first embodiment of the present invention. It is a figure for demonstrating lighting operation of the light source in the video display apparatus concerning the 1st Embodiment of this invention. It is a figure for demonstrating lighting operation of the light source in the video display apparatus concerning the 1st Embodiment of this invention. It is a figure for demonstrating operation | movement of the video display apparatus which concerns on the 1st Embodiment of this invention. It is a figure for demonstrating operation | movement of the video display apparatus which concerns on the 1st Embodiment of this invention. It is a figure for demonstrating operation | movement of the video display apparatus which concerns on the 1st Embodiment of this invention. It is a figure for demonstrating operation | movement of the video display apparatus which concerns on the 1st Embodiment of this invention. 1 is an overall configuration diagram of a virtual image display apparatus according to a first embodiment of the present invention. 1 is an overall configuration diagram of a direct view video display device according to a first embodiment of the present invention. 1 is an overall configuration diagram of a rear projection display apparatus according to a first embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1A ... Projection type video display apparatus 1B ... Virtual image type video display apparatus 1C ... Direct view type video display apparatus 1D ... Rear projection type video display apparatus 10R, 10G, 10B ... Light source 11 ... Cross prism 12 ... Rod integrator 13A, 13B ... Polarizing plate DESCRIPTION OF SYMBOLS 14 ... Liquid crystal panel 15 ... Projection lens 16 ... Virtual image optical system 21 ... Light source drive circuit 22 ... Light valve drive circuit 23 ... Luminance level detection means 30 ... Back mirror 31 ... Screen

Claims (7)

A video display control device that performs control for displaying video based on an input video signal,
A luminance level detecting means for detecting a luminance level of the video signal;
A light source driving frequency that determines the timing of sequentially emitting light of a plurality of colors in the light source according to the detected luminance level, and a light source driving circuit that drives the light source at the determined light source driving frequency;
In accordance with the detected luminance level, a light valve driving frequency that defines timing for modulating light emitted by the light source in a light valve in units of pixels is determined, and the light valve is controlled at the determined light valve driving frequency. An image display control device comprising: a light valve driving circuit for driving. The light source driving circuit is configured to decrease the light source driving frequency when the luminance level increases, and to increase the light source driving frequency when the luminance level decreases,
The light valve driving circuit is configured to decrease the light valve driving frequency when the luminance level increases, and to increase the light valve driving frequency when the luminance level decreases. The video display control device according to claim 1.   The said light source drive circuit drives the said light source so that the light quantity per unit time of the emitted light may be increased when the said brightness | luminance level becomes a predetermined value or less. Video display control device.   4. The light source driving circuit according to claim 1, wherein the light source driving circuit drives the light source so as to reduce a light amount per unit time of emitted light when the luminance level becomes a predetermined value or more. The video display control device according to one item.   The video display control apparatus according to claim 1, wherein the light source is a solid light source. A video display device;
A projection optical system for projecting light from the image display device;
A projection-type image display apparatus comprising: the image display control apparatus according to claim 1 for controlling the image display apparatus. A video display device;
A projection optical system for projecting light from the image display device;
A screen for projecting the projected light;
A rear projection type image display apparatus comprising: the image display control apparatus according to claim 1 for controlling the image display apparatus.

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