JP2006039089A - Driving method for image display apparatus, image display apparatus and projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a driving method for an image display apparatus having an excellent image display quality. <P>SOLUTION: In the driving method for the image display apparatus which displays an image by inputting a control value to a color modulation light bulb and a luminance modulation light bulb and by modulating light from a light source, the control value is inputted by synchronizing a vertical synchronous signal VSYNC1 to the color modulation light bulb and a vertical synchronous signal VSYNC2 to the luminance modulation light bulb. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image display device driving method, an image display device, and a projector.

  In recent years, electronic display devices such as LCD (Liquid Crystal Display), EL (Electro-luminescence) displays, plasma displays, CRTs (Cathode Ray Tubes), and projectors have been remarkably improved, and the resolution and color gamut have become human visual characteristics. Devices with nearly comparable performance are being realized. However, regarding the luminance dynamic range, the reproduction range is about 1 to 102 [nit], and the number of gradations is generally 8 bits. On the other hand, the range of luminance dynamic range that can be perceived at one time by human vision is about 10-2 to 104 [nit], and the luminance discrimination capability is 0.2 [nit]. It is said to be a bit equivalent. Looking at the display image of the current display device through such visual characteristics, the narrowness of the luminance dynamic range is conspicuous, and the gradation and shadow of the shadow part and highlight part are insufficient. Will feel unsatisfactory.

  In CG (Computer Graphics) used in movies, games, and the like, image data having luminance dynamic range and gradation characteristics close to human vision (hereinafter referred to as HDR (High Dynamic Range) image data) is used. The movement to pursue the reality of depiction is becoming mainstream. However, since the performance of the display device that displays it is insufficient, there is a problem that the expressive power inherent in the CG content cannot be fully exhibited.

  Further, in the next generation OS (Operating System), the adoption of a 16-bit color space is planned, and the dynamic range and the number of gradations are dramatically increased as compared with the current 8-bit color space. Therefore, it is expected that the demand for realizing a high dynamic range and high gradation electronic display device capable of utilizing the 16-bit color space will increase.

  Among display devices, projection display devices such as liquid crystal projectors and DLP (Digital Light Processing, a registered trademark of TI) projectors can display large screens, and are effective in reproducing the reality and power of display images. Display device. In this field, the following proposals have been made to solve the above problems.

As a display device for the purpose of expanding the dynamic range, for example, there is a technique disclosed in Patent Document 1. In this technique, a liquid crystal panel is provided as a first light modulation element, and a backlight in which a plurality of LEDs (Light Emitting Diodes), fluorescent lamps, and the like are arranged and arranged as a second light modulation element. Then, based on the pixel value data of each pixel, luminance control by the backlight and gradation control by the liquid crystal panel are performed. That is, by arranging two light modulation elements in series and individually controlling the pixels of each light modulation element corresponding to the pixels of the display image, it is possible to improve the contrast and expand the luminance dynamic range.
JP 2002-99250 A

FIGS. 21 and 22 are graphs showing temporal changes in drive control values and display luminance in corresponding pixels of the first light modulation element and the second light modulation element, and FIG. 21 is a still image display case. Reference numeral 22 denotes a case of moving image display. Here, the control value is a value input to each light modulation element in order to control the light transmittance of each light modulation element in the pixel.
In the case of the still image display of FIG. 21, the drive control value is constant for both the first light modulation element shown in FIG. 21 (a) and the second light modulation element shown in FIG. 21 (b). As a result, as shown in FIG. 21C, the display luminance in the pixel is also constant, and still image display is performed.

On the other hand, in the case of the moving image display of FIG. 22, the control value of the first light modulation element shown in FIG. 22A and the control value of the second light modulation element shown in FIG. As shown in FIG. 22 (c), the display luminance of the pixel is changed, and moving image display is performed.
However, the update time of the control value of the second light modulation element is delayed with respect to the update time of the control value of the first light modulation element. For this reason, the display luminance of the pixel temporarily increases and then decreases to a predetermined luminance. Due to the temporary increase in display brightness, the display screen shines like a flash, and there is a problem that the image display quality is lowered.

  Note that as a feature of a display device in which a plurality of light modulation elements are optically arranged in series, there are a plurality of combinations of control values of each light modulation element for realizing an intermediate gradation. Therefore, even if the display brightness is slightly different, the control value of each light modulation element that realizes the display brightness may change greatly. At this time, if the update time of the control value is different for each light modulation element, an unintended luminance display is performed as shown in FIG. 22C, and the image display quality is lowered. As a result, the contrast is lowered, which is a big problem particularly in a display system with high luminance.

  SUMMARY An advantage of some aspects of the invention is to provide an image display device driving method, an image display device, and a projector that are excellent in image display quality.

In order to achieve the above object, the image display apparatus driving method of the present invention displays an image by modulating the light from the light source by inputting control values to the first light modulation element and the second light modulation element. A method for driving an image display device, wherein a vertical synchronization signal for the first light modulation element and a vertical synchronization signal for the second light modulation element are synchronized, and a control value is input to each of the light modulation elements It is characterized by that.
According to this configuration, the input start times of the control values in the vertical direction of the respective light modulation elements can be made substantially coincident. When the number of pixels of each light modulation element is different, the drawing time of the entire screen of each light modulation element is different, but the time difference is accumulated by synchronizing each vertical synchronization signal before the next drawing. There is no. Thereby, since the control value of each light valve is updated at substantially the same time, even when moving image display is performed, it is possible to prevent a temporary increase in luminance display due to a shift in the update timing of the control value. Therefore, the image display quality is not deteriorated.

According to another image display device driving method of the present invention, an image display for displaying an image by modulating a light from a light source by inputting a control value to the first light modulation element and the second light modulation element. A device driving method, wherein a horizontal synchronization signal immediately before the start of input of a control value for the first light modulation element and a horizontal synchronization signal immediately before the start of input of a control value for the second light modulation element are synchronized, A control value is input to each of the light modulation elements.
According to this configuration, it is possible to substantially match the input start timings of the control values in the horizontal direction of the respective light modulation elements. When the number of pixels of each light modulation element is different, the drawing time of the entire screen of each light modulation element is different, but the time difference is accumulated by synchronizing each horizontal synchronization signal before the next drawing. There is no. Thereby, since the control value of each light valve is updated at substantially the same time, even when moving image display is performed, it is possible to prevent a temporary increase in luminance display due to a shift in the update timing of the control value. Therefore, the image display quality is not deteriorated.

According to another image display device driving method of the present invention, an image display for displaying an image by modulating a light from a light source by inputting a control value to the first light modulation element and the second light modulation element. A method of driving an apparatus, wherein a ratio between a frequency of a dot clock signal for the first light modulation element and a frequency of a dot clock signal for the second light modulation element is determined by inputting a control value in the first light modulation element. The control value is input to each of the light modulation elements so as to be approximately equal to the ratio between the number of pixels involved in image formation and the number of pixels involved in image formation by inputting the control value in the second light modulation element. And
According to this configuration, the drawing time of the entire screen in the first light modulation element and the drawing time of the entire screen in the second light modulation element can be substantially matched. Thereby, since the control value of each light valve is updated at substantially the same time, even when moving image display is performed, it is possible to prevent a temporary increase in luminance display due to a shift in the update timing of the control value. Therefore, the image display quality is not deteriorated.

Note that the control value input start time for the pixels involved in image formation in the vertical direction of the first light modulation element is the control value input start time for the pixels involved in image formation in the vertical direction of the second light modulation element. It is desirable to generate a vertical synchronization signal for the first optical modulation element and a vertical synchronization signal for the second optical modulation element so as to substantially coincide with each other.
According to this configuration, it is possible to substantially match the input timing of the control values for the pixels involved in image formation in the vertical direction of the first light modulation element and the second light modulation element, so that the pixels involved in image formation are controlled. It is possible to suppress a temporary increase in the luminance display due to a shift in the value update timing. Therefore, the image display quality is not deteriorated.

Note that the control value input start timing for the pixels involved in image formation in the horizontal direction of the first light modulation element is the control value input start timing for the pixels involved in image formation in the horizontal direction of the second light modulation element. It is desirable to generate a horizontal synchronization signal for the first light modulation element and a horizontal synchronization signal for the second light modulation element so as to substantially coincide with each other.
According to this configuration, the input timings of the control values for the pixels involved in image formation in the horizontal direction of the first light modulation element and the second light modulation element can be substantially matched, so that the pixels involved in image formation are controlled. It is possible to suppress a temporary increase in the luminance display due to a shift in the value update timing. Therefore, the image display quality is not deteriorated.

On the other hand, the image display device of the present invention is an image display device that displays an image by inputting control values to the first light modulation element and the second light modulation element and modulating light from the light source, The vertical synchronization with respect to the first light modulation element is such that the input start time of the control value in the vertical direction of the first light modulation element substantially coincides with the input start time of the control value in the vertical direction of the second light modulation element. It has a drive control part which generates a signal and a vertical synchronizing signal to the 2nd light modulation element.
According to this configuration, the input timings of the control values in the vertical direction of the first light modulation element and the second light modulation element can be substantially coincided with each other, so that the luminance display is temporarily displayed due to the shift of the control value update timing. Increase can be suppressed. Therefore, the image display quality is not deteriorated.

Another image display device of the present invention is an image display device that displays an image by inputting control values to the first light modulation element and the second light modulation element and modulating light from the light source. Thus, the input start time of the control value in the horizontal direction of the first light modulation element is substantially equal to the input start time of the control value in the horizontal direction of the second light modulation element. It has a drive control part which generates a horizontal synchronizing signal and a horizontal synchronizing signal to the 2nd above-mentioned light modulation element.
According to this configuration, the input timings of the control values in the horizontal direction of the first light modulation element and the second light modulation element can be substantially coincided with each other, so that the luminance display is temporarily displayed due to the shift in the control value update timing. Increase can be suppressed. Therefore, the image display quality is not deteriorated.

Another image display device of the present invention is an image display device that displays an image by inputting control values to the first light modulation element and the second light modulation element and modulating light from the light source. The ratio of the frequency of the dot clock signal to the first light modulation element and the frequency of the dot clock signal to the second light modulation element is a pixel that participates in image formation by inputting a control value in the first light modulation element. And a drive control unit for generating each dot clock signal so as to substantially match a ratio between the number of pixels and the number of pixels involved in image formation by inputting a control value in the second light modulation element.
According to this configuration, the drawing time of the entire screen in the first light modulation element and the drawing time of the entire screen in the second light modulation element can be substantially matched. As a result, the control values of the pixels involved in the image formation of each light valve are updated almost at the same time, so even when performing moving image display, the control values of the pixels involved in the image formation are caused by a shift in the update timing. Temporary increase in luminance display can be prevented. Therefore, the image display quality is not deteriorated.

On the other hand, a projector according to the present invention includes the above-described image display device and a projection unit.
According to this configuration, it is possible to provide a projector having excellent image display quality.

  Embodiments of the present invention will be described below with reference to the drawings.

[First Embodiment]
[Overall configuration of projector]
FIG. 1 is an example of an embodiment of an image display device of the present invention and a projector of the present invention, and is a diagram showing a main optical configuration of a projector PJ1.
As shown in FIG. 1, the projector PJ 1 includes a light source 10, a uniform illumination system 20 that uniformizes the luminance distribution of light incident from the light source 10, and RGB three primary colors in a wavelength region of light incident from the uniform illumination system 20. A color modulator 25 (including three transmissive liquid crystal light valves 60B, 60G, and 60R as a first modulator), a relay lens 90 that relays light incident from the color modulator 25, A transmissive liquid crystal light valve 100 as a second modulation means for modulating the luminance of light in the entire wavelength region of light incident from the relay lens 90, and a projection lens (not shown) for projecting light incident from the liquid crystal light valve 100 Projecting means) 110.

  The light source 10 includes a lamp 11 such as an ultrahigh pressure mercury lamp or a xenon lamp, and a reflector 12 that reflects and collects light emitted from the lamp 11.

  The uniform illumination system 20 includes two lens arrays 21 and 22 made of fly-eye lenses, a polarization conversion element 23, and a condenser lens 24. Then, the luminance distribution of the light from the light source 10 is made uniform by the two lens arrays 21 and 22, and the uniformed light is polarized by the polarization conversion element 23 in the polarization direction in which the color modulation unit can be incident, and the polarized light is condensed. The light is condensed by the lens 24 and emitted to the color modulation unit 25. The polarization conversion element 23 is composed of, for example, a PBS (polarization beam splitter) array and a half-wave plate, and converts random polarization into specific linear polarization.

  The color modulation unit 25 includes two dichroic mirrors 30 and 35 as light separating means, three mirrors (reflection mirrors 36, 45, and 46), and five field lenses (lens 41, relay lens 42, and collimating lens 50B). , 50G, 50R), three liquid crystal light valves 60B, 60G, 60R, and a cross dichroic prism 80.

  The dichroic mirrors 30 and 35 separate (spread) the light (white light) from the light source 10 into RGB three primary color lights of red light (R light), green light (G light), and blue light (B light). is there. The dichroic mirror 30 is formed by forming a dichroic film having a property of reflecting B light and G light and transmitting R light on a glass plate or the like, and reflects B light and G light included in white light from the light source 10. , R light is transmitted. The dichroic mirror 35 is formed by forming a dichroic film having a property of reflecting G light and transmitting B light on a glass plate or the like. Of the G light and B light transmitted through the dichroic mirror 30, the dichroic mirror 35 reflects G light. The light is transmitted to the collimating lens 50G, and the B light is transmitted and transmitted to the lens 41.

The relay lens 42 transmits light in the vicinity of the lens 41 (light intensity distribution) to the vicinity of the collimating lens 50B, and the lens 41 has a function of causing light to enter the relay lens 42 efficiently.
The B light incident on the lens 41 is transmitted to the liquid crystal light valve 60B which is spatially separated with the intensity distribution almost preserved and almost no light loss.

  The collimating lenses 50B, 50G, 50R substantially collimate the respective color lights incident on the corresponding liquid crystal light valves 60B, 60G, 60R to narrow the angle distribution of the incident light, thereby improving the display characteristics of the liquid crystal light valves 60B, 60G, 60R. It has a function to improve. The light of the three primary colors of RGB dispersed by the dichroic mirrors 30 and 35 passes through the above-described mirrors (reflection mirrors 36, 45, 46) and field lenses (lens 41, relay lens 42, collimating lenses 50B, 50G, 50R). Through the liquid crystal light valves 60B, 60G, and 60R.

  The liquid crystal light valves 60B, 60G, and 60R are composed of a glass substrate on which pixel electrodes and switching elements for driving the pixel electrodes, such as thin film transistors and thin film diodes, are formed in a matrix, and a glass substrate on which a common electrode is formed over the entire surface. This is an active matrix type liquid crystal display element in which a TN liquid crystal is sandwiched between and a polarizing plate is disposed on the outer surface.

  The liquid crystal light valves 60B, 60G, and 60R are normally white mode in which white / bright (transmission) state is applied when no voltage is applied, and black / dark (non-transmission) state is applied when voltage is applied, or vice versa. It is driven in the black mode, and the gradation between light and dark is analog controlled according to the control value (control voltage) given between the electrodes. The liquid crystal light valve 60B optically modulates the incident B light based on the control value, and emits modulated light including an optical image. The liquid crystal light valve 60G optically modulates the incident G light based on the control value, and emits modulated light containing an optical image. The liquid crystal light valve 60R optically modulates the incident R light based on the control value, and emits modulated light including an optical image.

  The cross dichroic prism 80 has a structure in which four right-angle prisms are bonded to each other, and a dielectric multilayer film (B light reflecting dichroic film 81) that reflects B light and a dielectric multilayer film that reflects R light are included therein. (R light reflecting dichroic film 82) is formed in an X-shaped cross section. Then, the G light from the liquid crystal light valve 60G is transmitted, and the R light from the liquid crystal light valve 60R and the B light from the liquid crystal light valve 60B are bent to combine these three colors of light to form a color image. .

  The relay lens 90 transmits an optical image (light intensity distribution) from the liquid crystal light valves 60B, 60G, and 60R synthesized by the cross dichroic prism 80 onto the display surface of the liquid crystal light valve 100. Since the relay lens 90 is composed of a large number of lenses, aberration correction is good, and the luminance distribution formed by the liquid crystal light valves 60B, 60G, 60R for color modulation can be accurately transmitted to the liquid crystal light valve 100. it can.

The liquid crystal light valve 100 has the same configuration as the liquid crystal light valves 60B, 60G, and 60R described above, and modulates the luminance in the entire wavelength region of the incident light based on the control value, and modulates the final optical image. Light is emitted to the projection lens 110.
The projection lens 110 projects an optical image formed on the display surface of the liquid crystal light valve 100 onto a screen (not shown) to display a color image.

  Next, the overall light transmission flow of the projector PJ1 will be described. The white light from the light source 10 is split into three primary colors of red (R), green (G), and blue (B) by the dichroic mirrors 30 and 35, and the lenses and mirrors including the collimating lenses 50B, 50G, and 50R. Through the liquid crystal light valves 60B, 60G, and 60R. The liquid crystal light valves 60B, 60G, and 60R are driven by control values generated based on HDR image data, which will be described later, so that the light transmittance can be changed in units of pixels. Accordingly, the respective color lights incident on the liquid crystal light valves 60B, 60G, and 60R are color-modulated according to the respective wavelength regions, and emitted as modulated light including an optical image.

  The modulated lights from the liquid crystal light valves 60B, 60G, and 60R enter the cross dichroic prism 80, where they are combined into a single light, and enter the liquid crystal light valve 100 via the relay lens 90. Similarly, the liquid crystal light valve 100 is driven by a control value generated based on HDR image data, which will be described later, and can change the light transmittance in units of pixels. Therefore, the combined light incident on the liquid crystal light valve 100 is subjected to luminance modulation over the entire wavelength region, and is emitted to the projection lens 110 as modulated light including a final optical image. Then, the projection lens 110 projects the final combined light from the liquid crystal light valve 100 on a screen (not shown) to display a desired image.

  Thus, in the projector PJ1, the final display image is used as the second light modulation element by using the modulated light that forms the optical image (image) with the liquid crystal light valves 60B, 60G, and 60R as the first light modulation element. The liquid crystal light valve 100 is used, and the light from the light source 10 is modulated through two stages of image forming processes via two light valves arranged in series. As a result, the projector PJ1 can realize expansion of the luminance dynamic range and increase of the number of gradations.

  Here, the liquid crystal light valves 60B, 60G, 60R and the liquid crystal light valve 100 all match in that the intensity of transmitted light is modulated and an optical image corresponding to the degree of modulation is included. Modulates light in the entire wavelength range (white light), whereas the former liquid crystal light valves 60B, 60G, and 60R split the light in a specific wavelength range (R) by the dichroic mirrors 30 and 35, which are light separation means. , G, B, etc.). Accordingly, the light intensity modulation performed by the liquid crystal light valves 60B, 60G, and 60R is referred to as color modulation, and the light intensity modulation performed by the liquid crystal light valve 100 is referred to as brightness modulation for convenience. From the same viewpoint, in the following description, the liquid crystal light valves 60B, 60G, and 60R may be referred to as color modulation light valves and the liquid crystal light valve 100 may be referred to as luminance modulation light valves.

  The contents of the control values input to the color modulation light valve and the luminance modulation light valve will be described in detail later. In the present embodiment, the color modulation light valve has a higher resolution than the luminance modulation light valve. Therefore, when the color modulation light valve displays the display resolution (the observer views the display image of the projector PJ1) It is assumed that the resolution to be perceived) is determined. Of course, the relationship of display resolution is not limited to this, and it is possible to adopt a color modulation light valve and a luminance modulation light valve with the same resolution, and the luminance modulation light valve has a higher resolution than the color modulation light valve. It is also possible to adopt a configuration in which the luminance modulation light valve determines the display resolution.

[Display control device]
In the projector PJ1 shown in FIG. 1, control values for the color modulation light valves (liquid crystal light valves 60B, 60G, 60R) and the luminance modulation light valve (liquid crystal light valve 100) are generated from the HDR image data, and the control values are used for each light. Input to the bulb to perform light modulation and luminance modulation. Thereby, display control of an image is performed.

FIG. 2 is a block diagram illustrating a hardware configuration of the display control device.
The display control device stores in the ROM 172 an I / F 178 that mediates input of HDR image data from an external device, an input frame memory 192 that temporarily stores HDR image data input via the I / F 178, and the like. CPU 170 for generating control values of each light valve from HDR image data according to the programmed program, output frame memories 194 and 195 for storing the generated control values, luminance modulation light valve 100 and color using the control values A drive control unit 210 that drives the modulation light valve 60 is provided, and these are connected by a bus as a signal line so that data can be exchanged.

  The I / F 178 is connected to a signal line for connecting to an external network 199 and a storage device 182 for storing data and the like as a file. The storage device 182 stores HDR image data to be displayed by the projector and a control value registration table for driving the luminance modulation light valve 100 and the color modulation light valve 60.

  The HDR image data is image data capable of realizing a high luminance dynamic range that cannot be realized by a conventional image format such as sRGB, and stores pixel values indicating pixel luminance levels for all pixels of the image. In the present embodiment, the HDR image data uses a format in which a pixel value indicating a luminance level for each of the RGB three primary colors is stored as a floating point value for one pixel. For example, values (1.2, 5.4, 2.3) are stored as pixel values of one pixel. In addition, as a value to be stored, a value related to physical luminance such as radiance or luminance is stored. Since luminance is obtained by multiplying radiance by human visual characteristics, in the following description, the two will be referred to as luminance without distinction.

  For details of the method for generating HDR image data, see, for example, “PEDebevec, J. Malik,“ Recovering High Dynamic Range Radiance Maps from Photographs ”, Proceedings of ACM SIGGRAPH97, pp.367-378 (1997)”. Has been.

  FIG. 3 is an explanatory diagram of a data structure of a control value registration table 400 in which control values to be input to the luminance modulation light valve are registered. Each record of the control value registration table (LUT) 400 includes a field in which the control value of the luminance modulation light valve is registered and a field in which the transmittance of the luminance modulation light valve corresponding to each control value is registered. It consists of

  In the example of FIG. 3, “0” is registered as the control value and “0.003” is registered as the transmittance in the first row record. This indicates that when the control value “0” is input to the luminance modulation light valve, the transmittance of the luminance modulation light valve is 0.3%. Note that FIG. 3 shows an example in which the number of gradations of the luminance modulation light valve is 4 bits (0 to 15 values), but a record corresponding to the number of gradations of the luminance modulation light valve is actually registered. Is done. For example, when the number of gradations is 8 bits, 256 records are registered.

  FIG. 4 is an explanatory diagram of a data structure of a control value registration table 420R in which control values to be input to the color modulation light valve are registered. Each record of the control value registration table (LUT) 420R includes a field in which the control value of the color modulation light valve 60R in FIG. 1 is registered and a field in which the transmittance of the color modulation light valve 60R is registered. It is configured.

In the example of FIG. 4, “0” is registered as the control value and “0.004” is registered as the transmittance in the first row record. This indicates that when the control value “0” is input to the color modulation light valve, the transmittance of the color modulation light valve is 0.4%. Note that FIG. 4 shows an example in which the number of gradations of the color modulation light valve is 4 bits (0 to 15 values), but a record corresponding to the number of gradations of the color modulation light valve is actually registered. Is done. For example, when the number of gradations is 8 bits, 256 records are registered.
The data structure of the control value registration table corresponding to the color modulation light valves 60B and 60G in FIG. 1 is not particularly shown, but has the same data structure as the control value registration table 420R in FIG. However, different transmittances may be registered for the same control value.

[Display control method]
Next, a method for generating a control value for each light valve from the above-described HDR image data and driving the projector will be described.
Now, the luminance level of the pixel p in the HDR image data is Rp, the light modulation rate of the region corresponding to the pixel p in the whole projector is Tp, the transmittance of the region corresponding to the pixel p in the luminance modulation light valve is T1, and the color modulation light When the transmittance of the region corresponding to the pixel p in the bulb is T2, the following expressions (1) and (2) are established.
Rp = Tp × Rs (1)
Tp = T1 × T2 × G (2)
However, in the above formulas (1) and (2), Rs is the luminance of the light source, G is the gain, and both are constants.
For example, when the luminance level Rp (R, G, B) of the pixel p is (1.2, 5.4, 2.3) and the luminance Rs (R, G, B) of the light source is (10000, 10000, 10000), the pixel p The optical modulation rate Tp is (1.2, 5.4, 2.3) / (10000, 10000, 10000) = (0.00012, 0.00054, 0.00023).

FIG. 5 is a flowchart of a control value generation method.
First, in step S100, HDR image data is input from the storage device 182 of FIG. 2 to the input frame memory 192 via the I / F 178, and the CPU 170 reads the HDR image data.

  Next, the process proceeds to step S102 in FIG. 5, the read HDR image data is analyzed, and a histogram of pixel values, a maximum value, a minimum value, an average value, and the like of luminance levels are calculated. This analysis result is for use in automatic image correction such as brightening a dark scene, darkening a scene that is too bright, or coordinating intermediate contrast, or for tone mapping.

Next, the process proceeds to step S104, and the luminance level of the HDR image data is tone mapped to the luminance dynamic range of the projector based on the analysis result of step S102.
FIG. 6 is an explanatory diagram of tone mapping processing. As a result of analyzing the HDR image data, it is assumed that the minimum value of the luminance level included in the HDR image data is Smin and the maximum value is Smax. Further, it is assumed that the minimum value of the luminance dynamic range of the projector is Dmin and the maximum value is Dmax. In the example of FIG. 6, since Smin is smaller than Dmin and Smax is larger than Dmax, HDR image data cannot be properly displayed as it is. Therefore, normalization is performed so that the histogram of Smin to Smax falls within the range of Dmin to Dmax.

  Details of tone mapping are described in, for example, “F. Drago, K. Myszkowski, T. Annen, N. Chiba,“ Adaptive Logarithmic Mapping For Displaying High Contrast Scenes ”, Eurographics 2003, (2003)”. Yes.

  Next, the process proceeds to step S106 in FIG. 5, and the HDR image is resized (enlarged or reduced) in accordance with the resolution (number of pixels) of the color modulation light valve. At this time, the HDR image is resized while maintaining the aspect ratio of the HDR image. Examples of the resizing method include an average value method, an intermediate value method, and a nearest neighbor method (nearest neighbor method).

  Next, the process proceeds to step S108, and based on the luminance level Rp of each pixel of the resized image and the luminance Rs of the light source 10, the light modulation rate Tp is calculated for each pixel of the resized image by the above equation (1).

  Next, the process proceeds to step S110, and an initial value (for example, 0.2) is provisionally determined as the transmittance T2 of each pixel of the color modulation light valve.

  Next, the process proceeds to step S112, and the transmittance T1 'is calculated for the luminance modulation light valve region corresponding to each pixel of the color modulation light valve. Specifically, based on the light modulation rate Tp calculated in step S108, the transmittance T2 provisionally determined in step S110, and the gain G, the transmittance T1 'of the region is calculated by the above equation (2). Here, since the color modulation light valve is composed of the three liquid crystal light valves 60B, 60G, and 60R, the transmittance T1 'is calculated for each of the three primary colors of RGB in the same region. Since the luminance modulation light valve is composed of one liquid crystal light valve 100, the average value of the transmittance calculated for each of the three primary colors of RGB is set as the transmittance T1 'of the region.

  Next, the process proceeds to step S114, and the transmittance T1 is calculated for each pixel of the luminance modulation light valve. Specifically, among the transmittances T1 ′ of the regions of the luminance modulation light valve calculated in step S112, a weighted average value of the transmittances T1 ′ of the regions overlapping with the pixels of the luminance modulation light valve is calculated, The transmittance T1 at is determined. Weighting is performed based on the area ratio of overlapping pixels.

  Next, the process proceeds to step S116, and the control value corresponding to the calculated transmittance T1 is read from the control value registration table 400 of FIG. 3 for each pixel of the luminance modulation light valve. In the reading of the control value, the transmittance closest to the calculated transmittance T1 is selected from the control value registration table 400, and the control value corresponding to the selected transmittance is read. For example, this selection is performed by using a binary search method to realize a high-speed search.

  Next, the process proceeds to step S118 in FIG. 5, and the transmittance T2 is calculated for each pixel of the color modulation light valve. Specifically, among the transmittances T1 of the pixels of the luminance modulation light valve calculated in step S114, a weighted average value of the transmittances T1 of the pixels overlapping with the pixels of the color modulation light valve on the optical path is calculated. Weighting is performed based on the area ratio of overlapping pixels. Then, based on the average value of the calculated transmittance T1, the light modulation rate Tp and the gain G calculated in step S108, the transmittance T2 of the pixel is calculated by the above equation (2).

  Next, the process proceeds to step S120, and the control value corresponding to the calculated transmittance T2 is read from the control value registration table 420R of FIG. 4 for each pixel of the color modulation light valve. In reading the control value, the transmittance that is closest to the calculated transmittance T2 is selected from the control value registration table 420R, and the control value corresponding to the selected transmittance is read. For example, this selection is performed by using a binary search method to realize a high-speed search.

  Next, the process proceeds to step S122 in FIG. 5, and the control values determined in steps S116 and S120 are stored in the output frame memory. Thereafter, the control value stored in the drive control unit is read out and output to each light valve to drive them. The configuration and driving process of the drive control unit will be described later.

[Control value generation method]
Next, the process of generating control values to be input to the color modulation light valves (liquid crystal light valves 60B, 60G, 60R) and the luminance modulation light valve (liquid crystal light valve 100) will be described with reference to FIGS.
In the following, the color modulation light valve (liquid crystal light valve 60B, 60G, 60R) has a resolution of 18 horizontal pixels × 12 vertical pixels and a gradation number of 4 bits, and the luminance modulation light valve (liquid crystal light valve 100) is The case where the resolution is 15 pixels horizontally × 10 pixels vertically and the number of gradations is 4 bits will be described as an example. Further, both the color modulation light valve and the luminance modulation light valve are viewed from the light source 10 side.

FIG. 7 is an explanatory diagram of a process for provisionally determining the transmittance T2 of the color modulation light valve.
In step S110 (see FIG. 5, the same applies hereinafter), the transmittance T2 of each pixel of the color modulation light valve is provisionally determined. When the pixels in the upper left four sections of the color modulation light valve are p21 (upper left), p22 (upper right), p23 (lower left), and p24 (lower right), the transmittance T2 of the pixels p21 to p24 is shown in FIG. Thus, an initial value T20 is given.

FIG. 8 is an explanatory diagram of the process of calculating the transmittance T1 ′ for the area of the luminance modulation light valve corresponding to each pixel of the color modulation light valve.
In step S112, the transmittance T1 ′ is calculated for the luminance modulation light valve region corresponding to each pixel of the color modulation light valve. When attention is paid to the pixels p21 to p24 of the color modulation light valve, the transmittances T11 to T14 in the luminance modulation light valve region corresponding thereto correspond to the light modulation rates of the pixels p21 to p24, as shown in FIG. If Tp4 and the gain G are “1”, it can be calculated by the following equations (3) to (6).
T11 = Tp1 / T20 (3)
T12 = Tp2 / T20 (4)
T13 = Tp3 / T20 (5)
T14 = Tp4 / T20 (6)

  For example, when Tp1 = 0.00012, Tp2 = 0.05, Tp3 = 0.02, Tp4 = 0.01, and T20 = 0.1, T11 = 0.0012, T12 = 0.5, T13 = 0.2 by the above formulas (3) to (6), T14 = 0.1.

FIG. 9 is an explanatory diagram of a process of determining the transmittance T1 of each pixel of the luminance modulation light valve.
In step S114, the transmittance T1 of each pixel of the luminance modulation light valve is determined. Since the luminance modulation light valve and the color modulation light valve are in an inverted image relationship by the relay lens 90, the pixels in the upper left four sections of the color modulation panel are imaged on the lower right portion of the luminance modulation light valve. Therefore, as shown in FIG. 9A, the pixels in the lower right four sections of the luminance modulation light valve are defined as p11 (lower right), p12 (lower left), p13 (upper right), and p14 (upper left). Here, since the color modulation light valve and the luminance modulation light valve have different resolutions, the pixel p11 overlaps the pixels p21 to p24 (see FIG. 8) on the optical path. Since the resolution of the color modulation light valve is 18 × 12 and the resolution of the luminance modulation light valve is 15 × 10, based on the least common multiple of the number of pixels of each light valve, as shown in FIG. Can be divided into 6 × 6 rectangular regions. The area ratio in which the pixel p11 overlaps with the pixels p21 to p24 is 25: 5: 5: 1. Therefore, the transmittance T15 of the pixel p11 can be calculated by the following equation (7).
T15 = (T11 × 25 + T12 × 5 + T13 × 5 + T14 × 1) / 36 (7)

For example, when T11 = 0.0012, T12 = 0.5, T13 = 0.2, and T14 = 0.002, T15 = 0.008 according to the above equation (7).
Similarly to the pixel p11, the transmittances T16 to T18 of the pixels p12 to p14 shown in FIG. 9C can also be obtained by calculating the weighted average value based on the area ratio.

  Next, in step S116, for each pixel of the luminance modulation light valve, a control value corresponding to the transmittance T1 calculated for that pixel is read from the control value registration table 400. For example, since T15 = 0.008, referring to the control value registration table 400, 0.09 is the closest approximation as shown in FIG. Therefore, “8” is read from the control value registration table 400 as the control value of the pixel p11.

FIG. 10 is an explanatory diagram of the process of determining the transmittance T2 of each pixel of the color modulation light valve.
In step S118, the transmittance T2 of each pixel of the color modulation light valve is determined. As described above, since the color modulation light valve and the luminance modulation light valve have different resolutions, as shown in FIG. 10A, the pixel p24 overlaps the pixels p11 to p14 (see FIG. 9) on the optical path. . Further, since the resolution of the color modulation light valve is 18 × 12 and the resolution of the luminance modulation light valve is 15 × 10, based on the least common multiple of the number of pixels of the luminance modulation light valve, as shown in FIG. The pixel p24 can be divided into 5 × 5 rectangular areas. The area ratio in which the pixel p24 overlaps with the pixels p11 to p14 is 1: 4: 4: 16. Therefore, the transmittance T19 of the luminance modulation light valve corresponding to the pixel p24 can be calculated by the following equation (8) as a weighted average value of the transmittances of the pixels p11 to p14.
T19 = (T15 × 1 + T16 × 4 + T17 × 4 + T18 × 16) / 25 (8)
The transmittance T24 of the pixel p24 can be calculated by the following equation (9) with the gain G set to “1”.
T24 = Tp4 / T19 (9)

For example, when T15 = 0.09, T16 = 0.33, T17 = 0.15, T18 = 0.06, and Tp4 = 0.01, T19 = 0.1188 and T24 = 0.0842 from the above equations (8) and (9).
Similarly to the pixel p24, the transmittances T21 to T23 of the pixels p21 to p23 shown in FIG. 10C can also be obtained by calculating a weighted average value based on the area ratio.

  Next, in step S120, for each pixel of the color modulation light valve, a control value corresponding to the transmittance T2 calculated for that pixel is read from the control value registration table. For example, when T24 = 0.0842 for the pixel p24 of the liquid crystal light valve 60R, referring to the control value registration table 420R, 0.07 is the closest value as shown in FIG. Therefore, “7” is read from the control value registration table 420R as the control value of the pixel p24.

  In step S122, the control values determined in steps S116 and S120 are stored in the output frame memory. Thereafter, the stored control value is read from the output frame memory, and the drive control unit inputs the control value to each light valve to drive the projector by performing light modulation and luminance modulation.

[Drive control unit]
Next, the configuration of the drive control unit will be described.
FIG. 11 is a block diagram illustrating a hardware configuration of the drive control unit. The drive controller 210 generates a drive signal for each light valve and inputs a control value to each light valve in accordance with the drive signal.

  First, the vertical synchronization signal, horizontal synchronization signal, and dot clock signal, which are drive signals, will be described. When drawing the screen of the image display device, a signal for measuring the timing in the vertical direction is a vertical synchronization signal, and a signal for measuring the timing in the horizontal direction is a horizontal synchronization signal. In general, to draw the screen of the image display device, the image is drawn horizontally from the upper left of the screen toward the upper right, and when reaching the right end, the image is lowered one step and is drawn from the left to the right. When reaching the lower right of the screen, the process returns to the upper left and the same scanning is repeated. Here, it is the vertical synchronization signal that determines the timing of moving from the lower right to the upper left of the screen. The horizontal synchronization signal determines the timing for moving from the upper right end to the lower left end. Furthermore, the input timing of the control value for each pixel is a dot clock signal. The vertical synchronization signal is generated based on the horizontal synchronization signal, and the horizontal synchronization signal is generated based on the dot clock signal.

  The drive control unit 210 includes the vertical synchronization signal and horizontal synchronization signal generation units 214 and 216, the dot clock signal generation unit 212, and the overall control unit 220 that controls the timing of each signal generation unit. . On the other hand, the drive control unit 210 generates an address for reading out the control value of each light valve stored in the output frame memories 194 and 195 (see FIG. 2), and the read control value. Data buffers 224 and 226 for temporary storage are provided. Moreover, the data transfer part 230 which inputs the control value to each light valve according to a drive signal is provided.

[Control value input method]
Next, a method for generating a drive signal and a method for inputting image data to each light valve in accordance with the drive signal will be described.
12 and 13 are explanatory diagrams of drive signals generated in the first embodiment. In the first embodiment, a vertical synchronization signal for each light valve is generated in synchronization. In general, the low level of the vertical synchronization signal and the horizontal synchronization signal is active (trigger). In addition, there is a predetermined time lag (initialization time) for initialization from when the vertical synchronization signal and horizontal synchronization signal are activated until the control value is input.

FIG. 12 shows a case where the number of pixels of the color modulation light valve and the luminance modulation light valve are equal. FIG. 12A shows a drive signal for the color modulation light valve, and FIG. 12B shows a drive signal for the luminance modulation light valve.
In FIG. 12, the vertical synchronization signal 1 for the color modulation light valve and the vertical synchronization signal 2 for the luminance modulation light valve are generated in synchronization. Then, input of control values to each light valve is started at the same time after a predetermined time lag after each vertical synchronization signal becomes active. Thereby, since the control value of each light valve is updated at the same time, even when moving image display is performed, it is possible to prevent a temporary increase in luminance display due to a shift in the update timing of the control value. Therefore, the image display quality is not deteriorated.

  FIG. 13 shows a case where the number of pixels of the color modulation light valve and the luminance modulation light valve are different. In FIG. 13, the vertical synchronization signal 1 for the color modulation light valve and the vertical synchronization signal 2 for the luminance modulation light valve are generated in synchronization. A control value 1 for the color modulation light valve and a control value 2 for the luminance modulation light valve are input to the respective light valves at substantially the same time. Note that the initialization time of each light valve is different due to the difference in the number of pixels of each light valve, but the difference in the control value input start timing is not great. Also, due to the difference in the number of pixels of each light valve, the drawing time of the entire screen of each light valve is different, but the time difference can be accumulated by synchronizing each vertical synchronization signal before the next drawing. Absent. As a result, the control value of each light valve is updated approximately at the same time, so that the degradation of image display quality can be minimized.

[Second Embodiment]
Next, a method for driving the image display apparatus according to the second embodiment will be described. Note that the description of the same configuration as in the first embodiment is omitted.
14 and 15 are explanatory diagrams of drive signals generated in the second embodiment. In the second embodiment, the horizontal synchronization signal immediately before the start of control value input for each light valve is generated at the same timing.

FIG. 14 shows a case where the number of pixels of the color modulation light valve and the luminance modulation light valve are equal. FIG. 14A shows a drive signal for the color modulation light valve, and FIG. 14B shows a drive signal for the luminance modulation light valve.
In FIG. 14, the horizontal synchronization signal 1 immediately before the start of the input of the control value for the color modulation light valve and the horizontal synchronization signal 2 immediately before the start of the input of the control value for the luminance modulation light valve are generated in synchronization. Since the number of pixels of each light valve is equal, if the vertical synchronization signal for each light valve is generated in synchronization, the horizontal synchronization signal immediately before the start of control value input to each light valve is generated in synchronization. Can do. Then, input of control values to each light valve is started at the same time after a predetermined time lag after each horizontal synchronization signal becomes active. Thereby, since the control value of each light valve is updated at the same time, even when moving image display is performed, it is possible to prevent a temporary increase in luminance due to a shift in the update timing of the control value. Therefore, the image display quality is not deteriorated.

  FIG. 15 shows a case where the number of pixels of the color modulation light valve and the luminance modulation light valve are different. Also in FIG. 15, the horizontal synchronization signal 1 immediately before the start of the input of the control value for the color modulation light valve and the horizontal synchronization signal 2 immediately before the start of the input of the control value for the luminance modulation light valve are generated in synchronization. A control value 1 for the color modulation light valve and a control value 2 for the luminance modulation light valve are input to the respective light valves at substantially the same time. Note that the difference in the initialization time of each light valve is slight and does not matter. In addition, although the drawing time of the entire screen of each light valve is different, the time difference is not accumulated by synchronizing the horizontal synchronizing signals before the next drawing. As a result, the control values for each light valve are updated almost at the same time, so that even when moving images are displayed, it is possible to prevent a temporary increase in luminance due to a shift in the update timing of the control values. . Therefore, the image display quality is not deteriorated.

[Third Embodiment]
Next, a method for driving the image display apparatus according to the third embodiment will be described. In the third embodiment, assuming that the number of pixels of the color modulation light valve and the luminance modulation light valve are different, different dot clock frequencies are generated to drive each light valve. Note that the description of the same configuration as in the first embodiment is omitted.

  FIG. 16 is an explanatory diagram of the number of pixels of each light valve. In general, input of control values for each pixel of the light valve is performed in units of dot clock signals. Therefore, by making the ratio of the frequency of the dot clock signal for driving each light valve approximately the same as the ratio of the number of pixels of each light valve, the drawing time of the entire screen in each light valve can be made approximately the same. In FIG. 16, for ease of understanding, it is assumed that the number of pixels of the color modulation light valve is 16 pixels of 4 × 4, and the number of pixels of the luminance modulation light valve is 9 pixels of 3 × 3. At this time, the ratio of the dot clock frequency for driving the color modulation light valve and the dot clock frequency for driving the luminance modulation light valve may be set to 16: 9.

FIG. 17 is an explanatory diagram of drive signals generated in the third embodiment. FIG. 17A shows a drive signal for the color modulation light valve, and FIG. 17B shows a drive signal for the luminance modulation light valve.
In FIG. 17, the control value 1 is input to the color modulation light valve every 1 count of the dot clock signal 1, and the horizontal synchronization signal 1 is activated every 4 counts of the dot clock signal 1 to 4 × 4. One screen of a color modulation light valve composed of 16 pixels is drawn. On the other hand, a control value 2 is input to the luminance modulation light valve every count of the dot clock signal 2, and the horizontal synchronization signal 2 is activated every 3 counts of the dot clock signal 2, and 3 × 3 9 pixels. One screen of the luminance modulation light valve consisting of is drawn.

  As described above, the ratio between the frequency of the dot clock signal 1 that drives the color modulation light valve and the frequency of the dot clock signal 2 that drives the luminance modulation light valve is set to 16: 9. For this reason, in FIG. 17, the drawing time of the entire screen in the color modulation light valve and the drawing time of the entire screen in the luminance modulation light valve are substantially the same. This makes it possible to update the control values for the pixels of each light valve that overlap on the optical path at substantially the same time. Therefore, even when moving image display is performed, it is possible to prevent a temporary increase in luminance display due to a shift in the control value update timing, and image display quality is not deteriorated.

[Fourth Embodiment]
Next, a method for driving the image display apparatus according to the fourth embodiment will be described. In the fourth embodiment, when an image is drawn on only a part of the screen of one light valve, the drawing is started with the other light valve substantially coincided with the drawing start time. Note that the description of the same configuration as in the first embodiment is omitted.
In general, when a color modulation light valve and a luminance modulation light valve having the same number of pixels are employed, moire may occur due to interference of black stripes of both light valves. In order to eliminate this moire, it has been confirmed that an image should be drawn only on a part of the screen of one light valve. That is, even when a light valve having the same number of pixels is employed, an image is drawn only on a part of the screen of one light valve, so that it is used as a light valve having a different number of pixels.

  FIG. 18 is an explanatory diagram of a drawing area of each light valve. In the present embodiment, an image is drawn only on a part (center) of the screen of the luminance modulation light valve. In FIG. 18, for easy understanding, the pixel ratio between the color modulation light valve and the luminance modulation light valve is 4: 3, and the luminance of the six regions of 4 × 4 pixels in the color modulation light valve is represented by luminance. The modulation light valve is made to correspond to 6 regions each composed of 3 × 3 pixels. Then, drawing is started almost simultaneously with the color modulation light valve and the luminance modulation light valve. Specifically, the control values are input substantially simultaneously to the A pixel located at the upper left of the drawing area of the color modulation light valve and the B pixel located at the upper left of the drawing area of the luminance modulation light valve. Here, it should be noted that there is one pixel column that is not drawn (not involved in image formation) above the B pixel, and there are two pixels that are not drawn on the left side of the B pixel.

  FIG. 19 is an explanatory diagram of drive signals generated in the fourth embodiment to obtain horizontal drawing timing. FIG. 19A shows a driving signal for the color modulation light valve, and FIG. 19B shows a driving signal for the luminance modulation light valve. In the present embodiment, as in the third embodiment in which light valves having different numbers of pixels are used, the ratio of the frequency of the dot clock signal that drives each light valve is set to the number of pixels in the drawing area of each light valve (that is, control). The ratio of the number of pixels involved in image formation is substantially matched by the input of the value. That is, the ratio between the frequency of the dot clock signal 1 that drives the color modulation light valve and the frequency of the dot clock signal 2 that drives the luminance modulation light valve is set to 16: 9.

  As described above, there are two pixels that are not drawn on the left side of the B pixel of the luminance modulation light valve. As described in the third embodiment, the control value input (drawing) for each pixel is performed every time the dot clock signal is counted. Therefore, the horizontal synchronization signal 2 for the luminance modulation light valve is generated earlier by 2 counts (DCLK) of the dot clock signal than the horizontal synchronization signal 1 for the color modulation light valve. As a result, the control value input pixels involved in the image formation of the luminance modulation light valve can be advanced by two pixels with respect to the control value input pixels involved in the image formation of the color modulation light valve. Therefore, the drawing start times in the horizontal direction of the color modulation light valve and the luminance modulation light valve can be made substantially coincident.

  FIG. 20 is an explanatory diagram of drive signals generated in the fourth embodiment in order to obtain the vertical drawing timing. As described above, there is one non-drawn pixel column above the B pixel of the luminance modulation light valve. Therefore, the vertical synchronization signal 2 of the luminance modulation light valve is generated earlier by 1H of the horizontal synchronization signal 2 than the vertical synchronization signal 1 of the color modulation light valve. Accordingly, it is possible to advance the control value input pixel column related to the image formation of the luminance modulation light valve by one column with respect to the control value input pixel column related to the image formation of the color modulation light valve. Therefore, the drawing start times in the vertical direction of the color modulation light valve and the luminance modulation light valve can be made substantially coincident.

  19 and 20 are generated together, even when an image is drawn only on a part of the screen of the luminance modulation light valve, the A pixel of the color modulation light valve and the B of the luminance modulation light valve. Control values can be input to the pixels substantially simultaneously. Since the ratio of the dot clock frequency of each light valve is substantially matched to the ratio of the number of pixels in the drawing area of each light valve, drawing between the drawing area of the color modulation light valve and the drawing area of the luminance modulation light valve Timing can be substantially matched in the horizontal and vertical directions. As a result, the control value related to image formation is updated at substantially the same time in the corresponding pixel of each light valve, so even when moving images are displayed, it is caused by a difference in the update timing of the control value related to image formation. It becomes possible to prevent a temporary increase in the luminance display. Therefore, the image display quality is not deteriorated.

  Note that only one of the drive signals shown in FIG. 19 or FIG. 20 may be generated to drive each light valve. Even in this case, the drawing timings of the drawing area of the color modulation light valve and the drawing area of the luminance modulation light valve substantially coincide with each other in the horizontal direction or the vertical direction. This is because a temporary increase in luminance display can be suppressed.

[Other variations]
In the above embodiment, a three-plate projector has been described as an example. However, the present invention can also be applied to a single-plate projector. This single-plate projector mainly comprises a light source, a uniform illumination system, a first light modulation element, a relay lens, a second light modulation element, and a projection lens. When a white light source is adopted as the light source, the first light modulation is performed. A color filter is disposed in a liquid crystal light valve as the element or the second light modulation element.

  In the above embodiment, the projection display device has been described as an example. However, the present invention can also be applied to a direct view display device. In this direct-view display device, the image light modulated on the second modulation element is directly viewed. The direct-view display device has an advantage that it is suitable for viewing in a bright place.

  Further, in the above embodiment, the luminance modulation light valve is configured to perform luminance modulation on the light color-modulated by the color modulation light valve. However, the present invention is not limited to this, and the luminance modulation is performed by the luminance modulation light valve. The light may be configured to be color modulated by a color modulation light valve. In addition, the light intensity is modulated in two steps using the luminance modulation light valve and the color modulation light valve. However, the present invention is not limited to this, and the light luminance is divided into two steps using two sets of the luminance modulation light valves. It can also be configured to modulate.

  In the above embodiment, a single light source that emits white light is used as the light source 10, and the white light is split into light of the three primary colors of RGB. However, the present invention is not limited to this, and the three primary colors of RGB are used. The light source that emits red light, the light source that emits blue light, and the light source that emits green light may be used, and the configuration for removing the white light may be removed.

  In the above embodiment, the liquid crystal light valves 60B, 60G, 60R, 100 are configured using active matrix liquid crystal display elements. However, the present invention is not limited to this, and the liquid crystal light valves 60B, 60G, 60R, 100 are passive matrices. A liquid crystal display element of a type and a segment type liquid crystal display element can also be used. The active matrix type liquid crystal display has an advantage that precise gradation display can be performed, and the passive matrix type liquid crystal display element and the segment type liquid crystal display element have an advantage that they can be manufactured at low cost.

  In the above embodiment, the luminance modulation light valve or the color modulation light valve is configured by a liquid crystal panel which is a transmission type light modulation element. However, the present invention is not limited to this, and reflective light modulation such as DMD (Digital Micromirror Device) is used. It can also be composed of elements.

  A polarization compensation optical system that compensates the polarization state of light may be disposed between the relay lens and the luminance modulation light valve. As the polarization compensation optical system, a configuration using a dielectric film having a polarization compensation function or a rectifier can be employed.

  Further, in each of the embodiments described above, the case where the control program stored in advance in the ROM 172 of FIG. 2 is executed when executing the processing shown in the flowchart of FIG. 5 is not limited to this. The program may be read from the storage medium storing the program showing the procedure into the RAM 174 and executed.

  Here, the storage medium is a semiconductor storage medium such as RAM or ROM, a magnetic storage type storage medium such as FD or HD, an optical reading type storage medium such as CD, CDV, LD, or DVD, or a magnetic storage type such as MO. / Optical reading type storage media, including any storage media that can be read by a computer regardless of electronic, magnetic, optical, or other reading methods.

  As described above, the preferred embodiments according to the present invention have been described with reference to the accompanying drawings, but the present invention is not limited to the examples. It is obvious for those skilled in the art that various changes or modifications can be conceived within the scope of the technical idea described in the claims. It is understood that it belongs to.

It is a main optical block diagram of the image display apparatus (projector) which concerns on this invention. It is a block diagram which shows the hardware constitutions of a display control apparatus. It is a data structure figure of the control value registration table of a brightness | luminance modulation light valve. It is a data structure figure of the control value registration table of a color modulation light valve. It is a flowchart of the production | generation method of a control value. It is explanatory drawing of a tone mapping process. It is explanatory drawing in the case of tentatively determining the transmittance | permeability of a color modulation light valve. It is explanatory drawing in the case of calculating the transmittance | permeability of each area | region of the luminance modulation light valve corresponding to each pixel of a color modulation light valve. It is explanatory drawing in the case of determining the transmittance | permeability of each pixel of a brightness modulation light valve. It is explanatory drawing in the case of determining the transmittance | permeability of each pixel of a color modulation light valve. It is a block diagram which shows the hardware constitutions of a drive control part. It is explanatory drawing of the drive signal produced | generated in 1st Embodiment. It is explanatory drawing of the drive signal produced | generated in 1st Embodiment. It is explanatory drawing of the drive signal produced | generated in 2nd Embodiment. It is explanatory drawing of the drive signal produced | generated in 2nd Embodiment. It is explanatory drawing of the pixel number of each light valve. It is explanatory drawing of the drive signal produced | generated in 3rd Embodiment. It is explanatory drawing of the drawing area | region of each light valve. It is explanatory drawing of the drive signal produced | generated in 4th Embodiment. It is explanatory drawing of the drive signal produced | generated in 4th Embodiment. It is a graph which shows the control value of each light valve, and the time change of display luminance. It is a graph which shows the control value of each light valve, and the time change of display luminance.

Explanation of symbols

  VSYNC1 Vertical sync signal VSYNC2 Vertical sync signal

Claims (9)

A method for driving an image display device that displays an image by inputting control values to a first light modulation element and a second light modulation element and modulating light from a light source,
A method for driving an image display device, comprising: synchronizing a vertical synchronization signal for the first light modulation element and a vertical synchronization signal for the second light modulation element, and inputting a control value to each of the light modulation elements . A method for driving an image display device that displays an image by inputting control values to a first light modulation element and a second light modulation element and modulating light from a light source,
The horizontal synchronization signal immediately before the start of the input of the control value to the first light modulation element and the horizontal synchronization signal immediately before the start of the input of the control value to the second light modulation element are synchronized to control each of the light modulation elements. A method for driving an image display device, wherein: A method for driving an image display device that displays an image by inputting control values to a first light modulation element and a second light modulation element and modulating light from a light source,
The ratio between the frequency of the dot clock signal for the first light modulation element and the frequency of the dot clock signal for the second light modulation element is defined as the number of pixels involved in image formation by inputting a control value in the first light modulation element. A driving method for an image display device, wherein a control value is input to each of the light modulation elements so as to substantially match a ratio with the number of pixels involved in image formation by inputting the control value in the second light modulation element. .   The control value input start time for the pixels involved in the image formation in the vertical direction of the first light modulation element is substantially the same as the control value input start time for the pixels involved in the image formation in the vertical direction of the second light modulation element. 4. The method of driving an image display device according to claim 3, wherein a vertical synchronization signal for the first light modulation element and a vertical synchronization signal for the second light modulation element are generated so as to match.   The input start time of control values for the pixels involved in image formation in the horizontal direction of the first light modulation element is substantially the input start time of control values for the pixels involved in image formation in the horizontal direction of the second light modulation element. 4. The method of driving an image display device according to claim 3, wherein a horizontal synchronization signal for the first light modulation element and a horizontal synchronization signal for the second light modulation element are generated so as to match. An image display device that displays an image by inputting control values to a first light modulation element and a second light modulation element and modulating light from a light source,
The vertical synchronization with respect to the first light modulation element is such that the input start time of the control value in the vertical direction of the first light modulation element substantially coincides with the input start time of the control value in the vertical direction of the second light modulation element. An image display apparatus comprising: a drive control unit that generates a signal and a vertical synchronization signal for the second light modulation element. An image display device that displays an image by inputting control values to a first light modulation element and a second light modulation element and modulating light from a light source,
Horizontal synchronization with respect to the first light modulation element is such that the input start time of the control value in the horizontal direction of the first light modulation element substantially coincides with the input start time of the control value in the horizontal direction of the second light modulation element. An image display device comprising: a drive control unit that generates a signal and a horizontal synchronization signal for the second light modulation element. An image display device that displays an image by inputting control values to a first light modulation element and a second light modulation element and modulating light from a light source,
The ratio between the frequency of the dot clock signal for the first light modulation element and the frequency of the dot clock signal for the second light modulation element is defined as the number of pixels involved in image formation by inputting a control value in the first light modulation element. An image display apparatus, comprising: a drive control unit that generates the dot clock signals substantially in accordance with a ratio with the number of pixels involved in image formation by inputting a control value in the second light modulation element. An image display device according to any one of claims 6 to 8,
And a projector.

Images