JP2007293140A - Image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image display device capable of displaying an image with a good contrast without impairing the dynamic range of an image signal even when the display image changes in light and shade in short cycles in accordance with the frame frequency of the image signal, when one frame includes both a white-peak-level image and a black-level image together, and so on. <P>SOLUTION: The image display device having display devices 13, 20, and 24 which receive illumination light from a light source 1 and modulates the illumination light according to the display image and an imaging lens system 25 which images illumination light beams passed through the display devices 13, 20, and 24 is provided with an optical modulating means 6 of imposing intensity modulation on the illumination light made incident on the display devices 13, 20, and 24 or the illumination light passed through the display devices 13, 20, and 24 according to the image to be displayed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image display apparatus including a display device that modulates illumination light from a light source according to a display image, and an imaging lens system that forms an image of illumination light that has passed through the display device.

  Conventionally, a display device is illuminated with illumination light from a light source, the illumination light is modulated according to a display image by the display device, and the illumination light that has passed through the display device is imaged on a screen by an imaging lens system A projection-type image display device (projector) has been proposed. Various display devices such as LCD (transmission type), DLP, LCOS, and GLV are used as display devices in such an image display apparatus.

  In such an image display device, as described in Patent Document 1, illumination light is separated into red (R) band, green (G) band, and blue (B) band components by color separation means. Then, the illumination light of each color component is incident on each display device for red, green, and blue, and the illumination light that has passed through each display device is synthesized and projected by the color synthesis means, thereby displaying a color image. There is a proposal to do this.

  In recent years, in such an image display device, it has been required to improve the contrast of the display image as well as the brightness of the display image. In order to improve the contrast of the display image, an image display device is proposed in which an aperture mechanism that is operated in accordance with the brightness of the display image is provided on the optical path from the light source to the display device or on the optical path through the display device. Has been.

  For example, as shown in FIG. 9, the illumination light from the light source 101 is color-separated and led to display devices (LCOS) 102R, 102G, and 102B for red, green, and blue, and these display devices 102R, 102G, In the image display apparatus in which the illumination light passing through 102B is color-combined and incident on the projection lens 103, the illumination system integrator 104 is formed in the vicinity of the illumination system integrator 104 on the optical path of the illumination light from the light source 101 or the projection lens 103. A lens system in which a diaphragm mechanism 105 is provided between the lens groups has been proposed. In this image display device, by varying the diaphragm mechanism 105 according to the brightness of the display image, that is, by opening the diaphragm mechanism 105 when the display image is bright, and by narrowing the diaphragm mechanism 105 when the display image is dark, The contrast (dynamic range) from black to white in the display image can be improved.

Japanese Patent No. 3596322

  As described above, in an image display device provided with a diaphragm mechanism on the optical path of illumination light, if the entire screen is bright or the entire screen is continuously displayed as a dark image, the contrast of the display image is reduced. Improvement is possible. For example, when brightness is not required for a display image such as a movie, it is possible to increase the contrast of the image by using the aperture mechanism in a state where the aperture mechanism is always stopped.

  However, there is a limit to the responsiveness of the diaphragm mechanism. When the brightness of the display image changes in a short cycle, it cannot be driven in real time according to the brightness of the display image, and the frame frequency of the image signal It cannot be driven according to the above.

  In addition, as long as there is an image signal, the diaphragm structure cannot be completely stopped, that is, the illumination light cannot enter the projection lens. Therefore, this image display apparatus cannot cope with the case where the white peak level image and the black level image coexist in the same frame. In other words, improving the contrast by the diaphragm mechanism does not expand the dynamic range of the display image itself, but only improves the contrast value as the ratio of light and dark when measuring an all-white image and an all-black image. It can be said that there is.

  Therefore, the present invention is proposed in view of the above-described circumstances, and when the brightness of the display image changes in a short cycle according to the frame frequency of the image signal, or when the white peak level image is included in the same frame. An object of the present invention is to provide an image display device capable of displaying an image with good contrast without impairing the dynamic range of an image signal even when a black level image coexists.

  In order to solve the above-described problems and achieve the above object, an image display apparatus according to the present invention has any one of the following configurations.

[Configuration 1]
An image display apparatus according to the present invention includes a light source, a display device that receives illumination light from the light source and modulates the illumination light according to a display image, and an imaging lens that forms an image of the illumination light that has passed through the display device. And a light modulation means for modulating the intensity of illumination light incident on the display device or illumination light that has passed through the display device in accordance with an image displayed on the display device.

[Configuration 2]
An image display device according to the present invention includes a light source, color separation means for separating illumination light from the light source into red band, green band, and blue band components, and red band illumination light that has passed through the color separation means. Display device for red light, green display device for receiving green band illumination light through color separation means, blue display device for blue light illumination light entering through color separation means, and each display Color synthesizing means for synthesizing illumination light that has passed through the device, an imaging lens system that forms an image of the illumination light that has passed through the color synthesizing means, and illumination light incident on the color separation means or illumination light that has passed through the color synthesizing means And a light modulation means for modulating the intensity according to an image displayed by each display device.

[Configuration 3]
An image display device according to the present invention includes a light source, color separation means for separating illumination light from the light source into red band, green band, and blue band components, and red band illumination light that has passed through the color separation means. Display device for red light, green display device for receiving green band illumination light through color separation means, blue display device for blue light illumination light entering through color separation means, and each display Color synthesis means for synthesizing illumination light that has passed through the device, an imaging lens system that forms an image of illumination light that has passed through this color synthesis means, and a display device that is installed corresponding to each display device and that corresponds to the color separation means Light modulation means for red, green and blue that modulates the intensity of incident illumination light or illumination light incident on the color synthesis means via a corresponding display device in accordance with an image displayed by the display device. Preparation It is characterized in that the.

[Configuration 4]
According to the present invention, in the image display device having the configuration 2 or the configuration 3, the γ characteristics resulting from the Vt characteristics of the light modulation means are γ gradations required for a display image for red, green, and blue. The characteristic is that the characteristic is divided by the γ characteristic resulting from the Vt characteristic of the device.

  In the image display apparatus according to the present invention, the illumination light incident on the display device or the illumination light that has passed through the display device is intensity-modulated by the light modulation means according to the image displayed on the display device. The dynamic range of the image signal is impaired even when the brightness of the image changes in a short cycle according to the frame frequency of the image signal, or when the white peak level image and the black level image coexist in the same frame. An image with good contrast can be displayed.

  The image display apparatus according to the present invention includes a color separation unit and a color synthesis unit, and is configured to display a color image using a display device for red, green, and blue as a display device. The light modulating means may be provided either on the optical path before entering the color separating means, or on the optical path after passing through the color synthesizing means, or color-separated corresponding to each display device. It may be provided on the optical path of the illumination light. The light modulation means provided corresponding to each display device may be provided either on the optical path before entering the corresponding display device or on the optical path after passing through the corresponding display device.

  Furthermore, in the image display apparatus according to the present invention, the γ characteristic due to the Vt characteristic (Voltage Transmission: also referred to as S-curve) of the light modulation means is used, and the γ gradation required for the display image is used as the Vt characteristic of each display device. By setting the characteristic divided by the resulting γ characteristic, an image having good color reproducibility can be displayed.

  That is, in the present invention, when the brightness of the display image changes in a short cycle according to the frame frequency of the image signal, or when the white peak level image and the black level image coexist in the same frame, It is possible to provide an image display device capable of displaying an image with good contrast without impairing the dynamic range of the image signal.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

[First Embodiment]
FIG. 1 is a plan view showing the configuration of the image display apparatus according to the first embodiment of the present invention.

  In this embodiment, the image display apparatus according to the present invention is configured by using an LCOS device (Liquid Crystal on Silicon) as a display device. This image display apparatus has a light source 1 as shown in FIG. As the light source 1, an ultra-high pressure mercury lamp (UHP lamp), a xenon lamp, a laser light source, an LED light source, or the like can be used. This light source 1 (in the case of a UHP lamp or a xenon lamp) is attached to a lamp house 1a having a concave mirror.

  The illumination light emitted from the light source 1 and reflected by the concave mirror of the lamp house 1 a is emitted from the lamp house 1 a, passes through the UV / IR filter 2, and enters the integrator 3. The UV / IR filter 2 is a filter that absorbs and blocks ultraviolet rays and infrared rays, and is provided to prevent subsequent deterioration of optical components due to heat and ultraviolet rays. The integrator 3 makes the illuminance distribution of the illumination light uniform, and a fly eye integrator may be used in addition to the rod integrator shown in FIG. The UV / IR filter 2 may be arranged separately before and after the integrator 3.

  The illumination light that has passed through the integrator 3 passes through a first relay lens 4 for condensing the illumination light on a display device, which will be described later, and enters a Y wire grid (Wire Grid) 5 that is inclined at 45 °. The Y wire grid 5 is a polarization separation element, which transmits P-polarized light of the illumination light and reflects S-polarized light. In place of the Y wire grid 5, a polarization beam splitter (PBS) may be used.

  The P-polarized illumination light transmitted through the Y wire grid 5 is incident on a Y device 6 that serves as a light modulation means. As the Y device 6, an LCOS device can be used similarly to a display device described later, and the illumination light is polarization-modulated according to an image displayed by the display device. The illumination light incident on the Y device 6 is reflected by the Y device 6 and returns to the Y wire grid 5. The component modulated into S-polarized light in the Y device 6 is reflected by the Y wire grid 5 and is incident on the second relay lens 7. The component not modulated in the Y device 6 passes through the Y wire grid 5 and returns to the optical path on the light source 1 side. In this way, the illumination light is intensity-modulated by the Y device 6 and the Y wire grid 5 according to the image displayed by the display device.

  The illumination light incident on the second relay lens 7 is incident on the B / RG cross dichroic mirror 8 serving as color separation means. This B / RG cross dichroic mirror 8 separates the incident illumination light into R light (red band component), G light (green band component), and B light (blue band component), each of which is 90 °. The light is deflected and emitted in the opposite direction. Illumination light in which R light (red band component) and G light (green band component) are mixed is Y light (yellow light).

  B light from the B / RG cross dichroic mirror 8 is reflected by the mirror 9, passes through the field lens 10, and is incident on the B wire grid 11 inclined at 45 °. The B wire grid 11 reflects S-polarized light in the B light. In this case, the B light has almost only the S-polarized component because it passes through the Y wire grid 5. Instead of the B wire grid 11, a polarization beam splitter (PBS) may be used.

  The S-polarized B light reflected by the B wire grid 11 passes through a retarder (corresponding to a λ / 4 plate in the case of PBS) 12 adapted to the wavelength of the B light, and becomes a blue display device. 13 is incident. The B device 13 is an LCOS device. The B device 13 polarization-modulates B light according to the blue component of the display image. The B light incident on the B device 13 is reflected by the B device 13 and returns to the B wire grid 11. The component modulated into P-polarized light in the B device 13 passes through the B wire grid 11 and enters the RGB dichroic prism 14 serving as a color composition unit from one side.

  On the other hand, the Y light from the B / RG cross dichroic mirror 8 is reflected by the mirror 15 and is incident on an R / G dichroic mirror 16 inclined at 45 ° as a color separation means. The R / G dichroic mirror 16 transmits the R light component of the Y light and reflects the G light component.

  The R light that has passed through the R / G dichroic mirror 16 passes through the field lens 17 and enters the R wire grid 18 inclined at 45 °. The R wire grid 18 reflects S polarized light in the R light. Here, since the R light passes through the Y wire grid 5, almost only the S polarization component is present. Instead of the R wire grid 18, a polarization beam splitter may be used.

  The S-polarized R light reflected by the R wire grid 18 passes through a retarder (corresponding to a λ / 4 plate in the case of PBS) 19 adapted to the wavelength of the R light, and becomes an R device that becomes a red display device. 20 is incident. The R device 20 is an LCOS device. The R device 20 modulates the polarization of the R light according to the red component in the display image. The R light incident on the R device 20 is reflected by the R device 20 and returns to the R wire grid 18. The component modulated into P-polarized light in the R device 20 passes through the R wire grid 18 and enters the RGB dichroic prism 14 from the other side surface.

  The G light reflected by the R / G dichroic mirror 16 passes through the field lens 21 and enters the G wire grid 22 inclined at 45 °. The G wire grid 22 reflects S-polarized light in the G light. Here, since the G light passes through the Y wire grid 5, it has almost only the S-polarized component. Instead of the G wire grid 22, a polarization beam splitter may be used.

  The S-polarized G light reflected by the G wire grid 22 passes through a retarder (corresponding to a λ / 4 plate in the case of PBS) 23 adapted to the wavelength of the G light, and becomes a green display device. 24 is incident. The G device 24 is an LCOS device. The G device 24 modulates the polarization of the G light according to the green component of the display image. The G light incident on the G device 24 is reflected by the G device 24 and returns to the G wire grid 22. The component modulated into P-polarized light in the G device 24 passes through the G wire grid 22 and enters the RGB dichroic prism 14 from the rear surface.

  The R light, G light, and B light incident on the RGB dichroic prism 14 from three directions are color-combined, emitted in front of the RGB dichroic prism 14, and incident on a projection lens 25 serving as an imaging lens system. . The projection lens 25 projects incident illumination light onto a screen (not shown) and forms an image.

  In this image display apparatus, a device other than LCOS (LCD (transmission type), DLP, GLV, etc.) may be used as a display device. Further, the color separation into R light, G light, and B light may be performed in a time division manner, and one display device may be used as a display device for each color in a time division manner.

In this image display apparatus, the illumination light from the light source 1 is intensity-modulated by the Y device 6 and the Y wire grid 5 according to the images displayed by the display devices 13, 20, and 24, so that the same. In this frame, only the black display portion can be displayed as dark as the light source light is focused. That is, as shown in the following formula, the contrast (Total-Cont.) Of the display image is the contrast (RGBDevice-Cont.) By each display device 13, 20, 24 and the contrast (Illumination-Cont.) By the Y device 6. ).
[Total-Cont.] = [RGBDevice-Cont.] × [Illumination-Cont.]

For example, when the contrast by each display device 13, 20, 24 is 1000: 1 and the contrast by the Y device 6 is also 1000: 1, the improvement in the contrast of the display image is 1 million: 1
[1000: 1] × [1000: 1] = [1000000: 1]

  As described above, in the image display device according to the present invention, it is possible to display an image having a contrast exceeding 100,000: 1 which is the dynamic range (contrast range) of the human eye.

[Second Embodiment]
FIG. 2 is a plan view showing the configuration of the image display device according to the second embodiment of the present invention.

  As shown in FIG. 2, the image display device according to the present invention allows illumination light emitted from the light source 1 and passed through the integrator 3 to enter the B / RG cross dichroic mirror 8 as it is through the field lens 26. Good. In this embodiment, the configuration from the B / RG cross dichroic mirror 8 to the RGB dichroic prism 14 is the same as the configuration in the first embodiment described above.

  In this embodiment, the light beam emitted from the RGB dichroic prism 14 is incident on the Y wire grid 5 inclined at 45 ° via the mirror 27. The Y wire grid 5 transmits P-polarized light of incident light and reflects S-polarized light. Instead of the Y wire grid 5, a polarization beam splitter may be used. Here, the incident light to the Y wire grid 5 is almost only the P-polarized light component through the wire grids 11, 18, and 22 for each color.

  The P-polarized illumination light transmitted through the Y wire grid 5 is incident on a Y device 6 that serves as a light modulation means. The Y device 6 polarization-modulates illumination light in accordance with an image displayed by the display device. The illumination light incident on the Y device 6 is reflected by the Y device 6 and returns to the Y wire grid 5. The component modulated into S-polarized light in the Y device 6 is reflected by the Y wire grid 5 and is incident on the projection lens 25. The projection lens 25 projects incident illumination light onto a screen (not shown) and forms an image.

  In this image display device, the illumination light that has passed through the display devices 13, 20, 24 is intensity-modulated by the Y device 6 and the Y wire grid 5 in accordance with the images displayed by the display devices 13, 20, 24. Therefore, in the same frame, only the black display portion can be displayed as dark as the light source light is focused.

  That is, also in this image display device, as in the image display device in the first embodiment described above, the contrast (Total-Cont.) Of the display image is the contrast (RGBDevice-) of each display device 13, 20, 24. Cont.) Multiplied by the contrast (Illumination-Cont.) By the Y device 6, and an image with a contrast exceeding 100,000: 1, which is the dynamic range (contrast range) of the human eye, is displayed. Is possible.

[Description of driving of each device]
In the image display device of each of the embodiments described above, the drive of each device 6, 13, 20, 24 ensures the γ characteristics and gradation accuracy (Bit accuracy) required for the original image signal in the display image. It is preferable to do so.

Therefore, if the light modulation degree in each display device 13, 20, 24 is Bf (t), Rf (t), Gf (t), and the light modulation degree required in the Y device 6 is Yf (t), Each RGB color light projected on the screen is obtained by multiplying the light modulation degree of each display device 13, 20, 24 by the light modulation degree of the Y device 6. That is, the output R of red light, the output G of green light, and the output B of blue light projected on the screen are expressed by the following equations.
[Output R] = Rf (t) · Yf (t)
[Output G] = Gf (t) · Yf (t)
[Output B] = Bf (t) · Yf (t)

  When a display device having a linear Vt characteristic (Voltage Transmission: also referred to as an S-shaped curve) such as a DLP device other than the liquid crystal display device is used, the same expression is used for each of the RGB colors. Therefore, a Y component that is a luminance signal is calculated from each RGB color, and the Y device 6 may be driven based on the Y component.

  However, as in the above-described embodiments, when LCOS is used as a display device, the Vt characteristic differs depending on the wavelength of each RGB color light, which is necessary for rotating liquid crystal molecules to perform light modulation. The level of the liquid crystal drive voltage varies depending on each color.

  Therefore, if, for example, the maximum value of the liquid crystal drive voltage in the RGB display devices 13, 20, 24 is selected as the waveform required for driving the Y device 6, the difference in Vt characteristics in the RGB display devices is absorbed. It becomes possible.

  FIG. 3 is a graph showing the electric drive operation of the display device in the image display apparatus according to the present invention.

  As shown in FIG. 3, the Vt characteristics of the RGB display devices 13, 20, and 24 are different for each color. That is, in a liquid crystal display device, by applying an alternating voltage to the liquid crystal cell and rotating the liquid crystal molecules, a light output corresponding to the drive voltage can be obtained, but in general, B light with a short wavelength of light rotates fast. R light with a long wavelength requires more voltage. This curve is called a Vt characteristic, but if this curve is left as it is, the human eye cannot feel natural display. Therefore, in the case of a television receiver, the voltage of the inverse S-shaped correction curve is generally applied to the liquid crystal cell so as to have a gamma 2.2 curve.

  However, in the above-described embodiment, all of the R, G, and B color lights are incident on the Y device 6 that modulates the illumination light from the light source, and only one drive voltage can be applied to the liquid crystal cell. Therefore, when the voltage of the reverse S-shaped correction curve similar to that of the television receiver is applied to the RGB display devices 13, 20, and 24, the output ranges of the RGB colors are different.

  For example, considering the drive voltage of the G device 24, as shown in FIG. 3, if the B point corresponding to 95% of the G light modulation is the white peak of the input signal, the output of the B light is already The liquid crystal is inverted and starts to fall. Conversely, the R light is still in the middle of the curve, and only outputs about 60% to 70%. Therefore, white that is 95% modulated by the Y device 6 and the G device 24 becomes cyanish white in which the R light is less than the G light and the B light is slightly more than the G light.

As described above, in the image display apparatus according to the present invention, the white illumination light light-modulated by the Y device 6 is color-separated and then incident on the RGB display devices 13, 20, and 24. In consideration of the difference in the Vt characteristics, the display devices 13, 20, and 24 for each of the RGB colors have a drive voltage obtained by adding a reverse correction to the Y device 6 in addition to the normal S-shape + γ correction. It is necessary to correct. This can be expressed as follows:
[Output Rout · Vt] = RD · Vt · (R ₀ -Y _∪G 0 _{-Y ∪B} 0 _-Y ) max · Vt
[Output Gout · Vt] = GD · Vt · (R ₀ -Y _∪G 0 _{-Y ∪B} 0 _-Y ) max · Vt
[Output Bout · Vt] = BD · Vt · (R ₀ -Y _∪G 0 _{-Y ∪B} 0 _-Y ) max · Vt

  In this equation, [Rout · Vt], [Gout · Vt], and [Bout · Vt] indicate the light amounts of the respective colors emitted from the projection lens 25. RD · Vt, GD · Vt, and BD · Vt represent light modulation characteristics when constant light is input to the RGB display devices 13, 20, and 24, respectively. Since the incident light to the RGB display devices is modulated by the Y device 6, this is (Ro-y∪Go-y∪Bo-y) max · Vt. That is, the largest signal (0 to Y voltage) of any of R light, G light, and B light is multiplied by the Vt characteristic.

  In the Y device 6 and the RGB display devices 13, 20, and 24, inverse γ and S-curve correction of each device are performed so that the output of the modulated RGB color light matches the γ characteristic of the input signal. Corrections including are also performed.

  FIG. 4 is a functional block diagram for driving the Y device and the RGB display devices.

  In this image display apparatus, in order to drive the Y device 6 and the RGB display devices 13, 20, and 24, as shown in FIG. 4, the drive signal of the Y device 6 is based on the drive signals for the RGB color lights. Is generated.

  That is, in the block diagram shown in FIG. 4, the R optical input signal is input to the input block 31. The input block 31 sends the input HDTV signal or computer signal as a LVDS signal for the digital circuit at the subsequent stage, with the bits aligned.

  Next, the signal that has passed through the input block 31 is sent to the inverse γ block 32. The inverse γ block 32 multiplies a signal multiplied by the power of 2.2, such as an HD input signal, with the inverse γ once to make it easier to perform the calculation in the subsequent blocks, and converts it to linear gamma (γ = 1.0). return.

  The signal that has passed through the inverse γ block 32 is sent to the image processing block 33. The image processing block 33 performs various image processing on the signal returned to the linear signal by the inverse γ block 32. That is, the image processing block 33 performs processing such as CGP (Computer Graphics Processor), blending, CP (Color Processor), and the like. CGP (Computer Graphics Processor) is a geometry correction, and is a correction that straightens an image distorted by a keystone correction, a cylindrical screen, or the like. Blending is a process of reducing the brightness and color of the overlapped portion so that it cannot be recognized when two or more images are overlapped to create a single image. CP (Color Processor) is a process of converting a specific color or luminance into a desired color by a color management function.

  Up to the image processing block 33 described above is a block that performs processing for converting an input signal into an image that is required at the time of projection, and thereafter is a block that performs signal processing in accordance with the characteristics of each display device. .

  The signal that has passed through the image processing block 33 is sent to the RVt block 34. As described with reference to FIG. 3, the RVt block 34 reversely corrects Vt characteristics that are different for each display device for each color of RGB using a lookup table.

  The signal that has passed through the RVt block 34 is sent to R-Shading 35. The R-shading 35 is a block that corrects in-plane unevenness inherent to the R device, and has a plurality of correction surfaces according to the signal level. Each correction surface is divided into vertical (Y) and horizontal (X) in accordance with the resolution of the display device, and the correction amount necessary for the display device is interpolated from the X / Y correction point data. This interpolation is performed by using linear calculation, quadratic, or spline curves from adjacent data in the correction plane. In this way, smooth correction is performed on the input signal level to eliminate luminance unevenness of each display device and prevent color unevenness when RGB colors are combined.

  The signal that has passed through the R-shading 35 is sent to the R drive D / A converter 36. The R drive D / A converter 36 receives the signal corrected according to the display device by the R-shading 35 and converts it into a drive signal necessary for driving the display device. The R drive D / A converter 36 directly supplies a drive voltage necessary for driving the R device.

  The drive voltage from the R drive D / A converter 36 is supplied to the R device 20. In the R device 20, a drive voltage is applied to the liquid crystal cell, and the illumination light from the light source is modulated with the characteristics shown in FIG.

  Similarly, the G light input signal is input to the input block 41, and sent to the GVt block 44 through the inverse γ block 42 and the image processing block 43. A signal passing through the GVt block 44 is converted into a drive signal necessary for driving the display device via a G-shading 45 and a G drive D / A converter 46. The G drive D / A converter 46 directly supplies a drive voltage necessary for driving the G device.

  The drive voltage from the G drive D / A converter 46 is supplied to the G device 24. In the G device 24, a drive voltage is applied to the liquid crystal cell, and the illumination light from the light source is modulated with the characteristics shown in FIG.

  Similarly, the B light input signal is input to the input block 51 and is sent to the BVt block 54 via the inverse γ block 52 and the image processing block 53. The signal passing through the BVt block 54 is converted into a drive signal necessary for driving the display device via a B-shading 55 and a B drive D / A converter 56. The B drive D / A converter 56 directly supplies a drive voltage necessary for driving the B device.

  The drive voltage from the B drive D / A converter 56 is supplied to the B device 13. In the B device 13, a drive voltage is applied to the liquid crystal cell, and the illumination light from the light source is modulated with the characteristics shown in FIG.

  The output signals from the image processing blocks 33, 43, 53 are sent to the RGB matrix circuit 61. The RGB matrix circuit 61 calculates the luminance signal Y and sends it to the YVt block 64. The blocks after the YVt block 64 are the same as the Vt block, shading, and D / A converter for each color light of RGB. That is, a signal that has passed through the YVt block 64 is converted into a drive signal necessary for driving the device via a Y-shading 65 and a Y drive D / A converter 66. The Y drive D / A converter 66 directly supplies a drive voltage necessary for driving the Y device.

  The drive voltage from the Y drive D / A converter 66 is supplied to the Y device 6. In the Y device 6, a drive voltage is applied to the liquid crystal cell to modulate illumination light from the light source.

[Third Embodiment (Structure of Six Plates)]
As described above, the image display apparatus according to the present invention is not limited to the configuration using a total of four devices, that is, a display device for each color light of RGB and a Y device. A device using a total of six devices may be provided.

  FIG. 5 is a plan view showing a configuration of an image display apparatus according to the third embodiment in which a device serving as a light modulation unit is provided for each display device of RGB color light, and a total of six devices are used.

  In this image display apparatus, as shown in FIG. 5, the illumination light emitted from the light source 1 and reflected by the concave mirror of the lamp house 1a is emitted from the lamp house 1a, passes through the UV / IR filter 2 and is integrated into the integrator. 3 is incident.

  The illumination light that has passed through the integrator 3 is incident on an R / GB dichroic mirror 29 serving as color separation means via a mirror 28 and a field lens 26. The R / GB dichroic mirror 29 separates incident illumination light into R light (red band component), G light (green band component), and B light (blue band component), and reflects R light. , G light and B light are transmitted. Illumination light in which G light and B light are mixed is C light (cyan light).

  The R light reflected by the R / GB dichroic mirror 29 is incident on the R wire grid 18b inclined at 45 °. The R wire grid 18b transmits the P-polarized light of the R light. The P-polarized R light transmitted through the R wire grid 18b passes through a retarder (corresponding to a λ / 4 plate in the case of PBS) 19b adapted to the wavelength of the R light, and then enters an R device 20b serving as a light modulation means. Incident. The R device 20b is an LCOS device. The R device 20b polarization-modulates the R light according to the red component of the display image. The R light incident on the R device 20b is reflected by the R device 20b and returns to the R wire grid 18b. The component modulated into S-polarized light in the R device 20b is reflected by the R wire grid 18b, passes through the field lens 17, and enters the R wire grid 18 inclined by 45 °. The R wire grid 18 reflects S polarized light in the R light. In this case, the R light is substantially only the S-polarized component because it passes through the R wire grid 18b.

  The S-polarized R light reflected by the R wire grid 18 passes through a retarder (corresponding to a λ / 4 plate in the case of PBS) 19 adapted to the wavelength of the R light, and becomes an R device that becomes a red display device. 20 is incident. The R device 20 is an LCOS device. The R device 20 modulates the polarization of the R light according to the red component in the display image. The R light incident on the R device 20 is reflected by the R device 20 and returns to the R wire grid 18. The component modulated into P-polarized light in the R device 20 passes through the R wire grid 18 and enters the RGB dichroic prism 14 from one side.

  On the other hand, the C light transmitted through the R / GB dichroic mirror 29 is incident on a G / B cross dichroic mirror 30 serving as color separation means. The G / B cross dichroic mirror 30 separates the incident illumination light into G light (green band component) and B light (blue band component), and deflects them by 90 ° and emits them in opposite directions.

  The G light that has passed through the G / B cross dichroic mirror 30 enters the G wire grid 22b inclined at 45 °. The G wire grid 22b transmits the P-polarized light in the G light. The P-polarized G light transmitted through the G wire grid 22b passes through a retarder (corresponding to a λ / 4 plate in the case of PBS) 23b adapted to the wavelength of the G light, and then enters a G device 24b serving as a light modulation means. Incident. The G device 24b is an LCOS device. The G device 24b polarization-modulates the G light according to the green component in the display image. The G light incident on the G device 24b is reflected by the G device 24b and returns to the G wire grid 22b. The component modulated into S-polarized light in the G device 24b is reflected by the G wire grid 18b, passes through the field lens 21, and enters the G wire grid 22 inclined at 45 °. The G wire grid 22 reflects S-polarized light in the G light. Here, the G light has almost only the S-polarized light component through the G wire grid 22b.

  The S-polarized G light reflected by the G wire grid 22 passes through a retarder (corresponding to a λ / 4 plate in the case of PBS) 23 adapted to the wavelength of the G light, and becomes a green display device. 24 is incident. The G device 24 is an LCOS device. The G device 24 modulates the polarization of the G light according to the green component of the display image. The G light incident on the G device 24 is reflected by the G device 24 and returns to the G wire grid 22. The component modulated into P-polarized light in the G device 24 passes through the G wire grid 22 and enters the RGB dichroic prism 14 from the rear surface.

  The B light that has passed through the G / B cross dichroic mirror 30 is incident on the B wire grid 11b inclined at 45 °. The B wire grid 11b transmits the P-polarized light of the B light. The P-polarized B light transmitted through the B wire grid 11b passes through a retarder (corresponding to a λ / 4 plate in the case of PBS) 12b adapted to the wavelength of the B light, and then enters a B device 13b serving as a light modulation unit. Incident. The B device 13b is an LCOS device. The B device 13b polarization-modulates B light according to the blue component of the display image. The B light incident on the B device 13b is reflected by the B device 13b and returns to the B wire grid 11b. The component modulated into S-polarized light in the B device 13b is reflected by the B wire grid 11b, passes through the field lens 10, and enters the B wire grid 11 inclined at 45 °. The B wire grid 11 reflects S-polarized light in the B light. In this case, the B light has almost only the S-polarized light component by passing through the B wire grid 11b.

  The S-polarized B light reflected by the B wire grid 11 passes through a retarder (corresponding to a λ / 4 plate in the case of PBS) 12 adapted to the wavelength of the B light, and becomes a blue display device. 13 is incident. The B device 13 is an LCOS device. The B device 13 polarization-modulates B light according to the blue component of the display image. The B light incident on the B device 13 is reflected by the B device 13 and returns to the B wire grid 11. The component modulated into P-polarized light in the B device 13 passes through the B wire grid 11 and enters the RGB dichroic prism 14 from the other side surface.

  The R light, G light, and B light incident on the RGB dichroic prism 14 from three directions are color-combined, emitted in front of the RGB dichroic prism 14, and incident on a projection lens 25 serving as an imaging lens system. . The projection lens 25 projects incident illumination light onto a screen (not shown) and forms an image.

In this image display device, the illumination light from the light source 1 is color-separated, and then the R light is modulated by the two R devices 20 and 20b, and the G light is two G devices 24, The B light is modulated by two B devices 13 and 13b. Therefore, in the same frame, only the black display portion can be displayed as dark as the light source light is focused. That is, as shown in the following expression, the contrast (Total-Cont.) Of the display image is the contrast (RGBDevice-Cont.) By each display device 13, 20, 24 and the contrast by the corresponding devices 13b, 20b, 24b. It is a value obtained by multiplying (Illumination-Cont.).
[Total-Cont.] = [RGBDevice-Cont.] × [Illumination-Cont.]

For example, when the contrast by the display devices 13, 20, and 24 is 1000: 1 and the contrast by the corresponding devices 13b, 20b, and 24b is also 1000: 1, the contrast of the display image is improved as follows. 1 million: 1.
[1000: 1] × [1000: 1] = [1000000: 1]

  Thus, in this image display device, it is possible to display an image having a contrast exceeding 100,000: 1, which is the dynamic range (contrast range) of the human eye.

  FIG. 6 shows another example of the configuration of the image display apparatus according to the third embodiment of the present invention in which a device serving as a light modulation unit is provided for each display device for each color of RGB, and a total of six devices are used. It is a top view.

  FIG. 6 shows another example of the configuration of the image display apparatus according to the third embodiment of the present invention in which a device serving as a light modulation unit is provided for each display device for each color of RGB, and a total of six devices are used. It is a side view.

  In this embodiment, the RGB optical paths are configured so as to be on a single plane, but the horizontal width of the apparatus can be shortened by configuring these optical paths not on a single plane.

  That is, in this image display device, as shown in FIG. 6 and FIG. 7, the illumination light emitted from the light source 1 and reflected by the concave mirror of the lamp house 1a is emitted from the lamp house 1a and passes through the UV / IR filter 2. The light is transmitted and incident on the integrator 3.

  The illumination light that has passed through the integrator 3 passes through the mirror 28 and the field lens 26 and is incident on a G / RB dichroic mirror 29 serving as color separation means. The G / RB dichroic mirror 29 separates incident illumination light into G light (green band component), R light (red band component), and B light (blue band component), and reflects G light. , R light and B light are transmitted. Illumination light in which R light and B light are mixed is M light (magenta light).

  As shown in FIG. 7, the G light reflected by the G / RB dichroic mirror 29 is deflected to the lower side of the apparatus and is incident on the G wire grid 22b inclined at 45 °. The G wire grid 22b transmits the P-polarized light in the G light. The P-polarized G light transmitted through the G wire grid 22b passes through a retarder (corresponding to a λ / 4 plate in the case of PBS) 23b adapted to the wavelength of the G light, and then enters a G device 24b serving as a light modulation means. Incident. The G device 24b is an LCOS device. The G device 24b polarization-modulates the G light according to the green component in the display image. The G light incident on the G device 24b is reflected by the G device 24b and returns to the G wire grid 22b. The component modulated into S-polarized light in the G device 24b is reflected by the G wire grid 18b, passes through the field lens 21, is deflected upward by the mirror 30b, and is incident on the G wire grid 22 inclined by 45 °. Is done. The G wire grid 22 reflects S-polarized light in the G light. Here, the G light has almost only the S-polarized light component through the G wire grid 22b.

  The S-polarized G light reflected by the G wire grid 22 passes through a retarder (corresponding to a λ / 4 plate in the case of PBS) 23 adapted to the wavelength of the G light, and becomes a green display device. 24 is incident. The G device 24 is an LCOS device. The G device 24 modulates the polarization of the G light according to the green component of the display image. The G light incident on the G device 24 is reflected by the G device 24 and returns to the G wire grid 22. The component modulated into P-polarized light in the G device 24 passes through the G wire grid 22 and enters the RGB dichroic prism 14 from the rear surface.

  On the other hand, the C light transmitted through the G / RB dichroic mirror 29 is incident on an R / B cross dichroic mirror 30 serving as color separation means. The R / B cross dichroic mirror 30 separates the incident illumination light into R light (red band component) and B light (blue band component), and deflects them by 90 ° and emits them in opposite directions.

  The R light having passed through the R / B cross dichroic mirror 30 is incident on the R wire grid 18b inclined at 45 °. The R wire grid 18b transmits the P-polarized light of the R light. The P-polarized R light transmitted through the R wire grid 18b passes through a retarder (corresponding to a λ / 4 plate in the case of PBS) 19b adapted to the wavelength of the R light, and then enters an R device 20b serving as a light modulation means. Incident. The R device 20b is an LCOS device. The R device 20b polarization-modulates the R light according to the red component of the display image. The R light incident on the R device 20b is reflected by the R device 20b and returns to the R wire grid 18b. The component modulated into S-polarized light in the R device 20b is reflected by the R wire grid 18b, passes through the field lens 17, and enters the R wire grid 18 inclined by 45 °. The R wire grid 18 reflects S polarized light in the R light. In this case, the R light is substantially only the S-polarized component because it passes through the R wire grid 18b.

  The S-polarized R light reflected by the R wire grid 18 passes through a retarder (corresponding to a λ / 4 plate in the case of PBS) 19 adapted to the wavelength of the R light, and becomes an R device that becomes a red display device. 20 is incident. The R device 20 is an LCOS device. The R device 20 modulates the polarization of the R light according to the red component in the display image. The R light incident on the R device 20 is reflected by the R device 20 and returns to the R wire grid 18. The component modulated into P-polarized light in the R device 20 passes through the R wire grid 18 and enters the RGB dichroic prism 14 from one side.

  The B light that has passed through the R / B cross dichroic mirror 30 is incident on the B wire grid 11b inclined at 45 °. The B wire grid 11b transmits the P-polarized light of the B light. The P-polarized B light transmitted through the B wire grid 11b passes through a retarder (corresponding to a λ / 4 plate in the case of PBS) 12b adapted to the wavelength of the B light, and then enters a B device 13b serving as a light modulation unit. Incident. The B device 13b is an LCOS device. The B device 13b polarization-modulates B light according to the blue component of the display image. The B light incident on the B device 13b is reflected by the B device 13b and returns to the B wire grid 11b. The component modulated into S-polarized light in the B device 13b is reflected by the B wire grid 11b, passes through the field lens 10, and enters the B wire grid 11 inclined at 45 °. The B wire grid 11 reflects S-polarized light in the B light. In this case, the B light has almost only the S-polarized light component by passing through the B wire grid 11b.

  The S-polarized B light reflected by the B wire grid 11 passes through a retarder (corresponding to a λ / 4 plate in the case of PBS) 12 adapted to the wavelength of the B light, and becomes a blue display device. 13 is incident. The B device 13 is an LCOS device. The B device 13 polarization-modulates B light according to the blue component of the display image. The B light incident on the B device 13 is reflected by the B device 13 and returns to the B wire grid 11. The component modulated into P-polarized light in the B device 13 passes through the B wire grid 11 and enters the RGB dichroic prism 14 from the other side surface.

  The R light, G light, and B light incident on the RGB dichroic prism 14 from three directions are color-combined, emitted in front of the RGB dichroic prism 14, and incident on a projection lens 25 serving as an imaging lens system. . The projection lens 25 projects incident illumination light onto a screen (not shown) and forms an image.

  In addition, in this image display apparatus, various other arrangements of the optical paths of RGB colors are conceivable.

[Description of driving of each device]
In the image display apparatus according to the third embodiment described above, each of the devices 13, 20, 24, 13b, 20b, and 24b is driven by the γ characteristic and gradation accuracy (Bit) required for the original image signal in the display image. (Accuracy) is preferably performed.

Therefore, the light modulation degree in each display device 13, 20, 24, 13b, 20b, 24b is set to Bf (t), Rf (t), Gf (t), B′f (t), R′f (t), Assuming G′f (t), the RGB color light projected on the screen is obtained by multiplying the light modulation degree of each display device 13, 20, 24 by the light modulation degree of the corresponding device 13b, 20b, 24b. Become. That is, the output R of red light, the output G of green light, and the output B of blue light projected on the screen are expressed by the following equations.
[Output R] = Rf (t) · R′f (t)
[Output G] = Gf (t) · G′f (t)
[Output B] = Bf (t) · B′f (t)

  When a display device having a linear Vt characteristic (Voltage Transmission: also referred to as an S-shaped curve) such as a DLP device other than the liquid crystal display device is used, the same expression is used for each of the RGB colors. Therefore, the devices 13b, 20b, 24b corresponding to the RGB display devices 13, 20, 24 may be driven in the same manner as the RGB display devices 13, 20, 24.

  The number of bits (Bit) of the input signal is also Rf (t) and R′f (t), Gf (t) and G′f (t), Bf (t) and B′f (t), respectively. Therefore, when using a normal 8-bit signal (for example, DVI output on a personal computer), Rf (t) is divided into 4 bits and R'f (t) is divided into 4 bits. (The same applies to G light and B light). When a 10-bit signal is used, it can be divided into 5 bits at a time, and when a 16-bit signal is used, it can be divided into 8 bits. Even if the bit accuracy of the output circuit that drives each device is low, a high bit Accuracy, that is, high gradation can be realized. That is, when each device is driven by an 8-bit D / A output signal, 16-bit gradation can be expressed for each color, and an image having high gradation can be displayed.

  When LCOS is used as a display device, the Vt characteristic differs depending on the wavelength of each RGB color light, and the level of the liquid crystal drive voltage required for rotating the liquid crystal molecules to perform light modulation is different for each color. Different. Therefore, the inverse γ and the output of each device are adjusted so that the output of each RGB light modulated by the RGB display devices 13, 20, 24 and the corresponding devices 13b, 20b, 24b matches the γ characteristics of the input signal. It is preferable to perform correction including S-curve correction.

  FIG. 8 is a functional block diagram for driving the display device of the image display apparatus according to the third embodiment.

  In this image display apparatus, in order to drive the display devices 13, 20, 24 and the corresponding devices 13b, 20b, 24b for each color of RGB, as shown in FIG. Drive signals for the devices 13b, 20b, and 24b to be generated are generated.

  That is, in the block diagram shown in FIG. 8, the R optical input signal is input to the input block 31 as described with reference to FIG. The input block 31 sends the input HDTV signal or computer signal as a LVDS signal for the digital circuit at the subsequent stage, with the bits aligned.

  Next, the signal that has passed through the input block 31 is sent to the inverse γ block 32. The inverse γ block 32 temporarily applies inverse γ to a signal that has been multiplied by the power of 2.2, such as an HD input signal, in the subsequent blocks, and returns the signal to linear gamma.

  The signal that has passed through the inverse γ block 32 is sent to the image processing block 33. The image processing block 33 performs various image processing on the signal returned to the linear signal by the inverse γ block 32.

  The signal that has passed through the image processing block 33 is sent to the RVt block 34. As described with reference to FIG. 3, the RVt block 34 reversely corrects Vt characteristics that are different for each display device for each color of RGB using a lookup table.

  The signal that has passed through the RVt block 34 is sent to R-Shading 35. The R-shading 35 is a block that corrects in-plane unevenness inherent to the R device.

  The signal that has passed through the R-shading 35 is sent to the R drive D / A converter 36. The R drive D / A converter 36 receives the signal corrected according to the display device by the R-shading 35 and converts it into a drive signal necessary for driving the display device. The R drive D / A converter 36 directly supplies a drive voltage necessary for driving the R device.

  The drive voltage from the R drive D / A converter 36 is supplied to the R device 20. In the R device 20, a drive voltage is applied to the liquid crystal cell, and the illumination light from the light source is modulated with the characteristics shown in FIG.

  Similarly, the G light input signal is input to the input block 41, and sent to the GVt block 44 through the inverse γ block 42 and the image processing block 43. A signal passing through the GVt block 44 is converted into a drive signal necessary for driving the display device via a G-shading 45 and a G drive D / A converter 46. The G drive D / A converter 46 directly supplies a drive voltage necessary for driving the G device.

  The drive voltage from the G drive D / A converter 46 is supplied to the G device 24. In the G device 24, a drive voltage is applied to the liquid crystal cell, and the illumination light from the light source is modulated with the characteristics shown in FIG.

  Similarly, the B light input signal is input to the input block 51 and is sent to the BVt block 54 via the inverse γ block 52 and the image processing block 53. The signal passing through the BVt block 54 is converted into a drive signal necessary for driving the display device via a B-shading 55 and a B drive D / A converter 56. The B drive D / A converter 56 directly supplies a drive voltage necessary for driving the B device.

  The drive voltage from the B drive D / A converter 56 is supplied to the B device 13. In the B device 13, a drive voltage is applied to the liquid crystal cell, and the illumination light from the light source is modulated with the characteristics shown in FIG.

  The output signal from the image processing block 33 is also sent to the R′Vt block 34b. The signal that has passed through the R'Vt block 34b is sent to an R'-Shading 35b. The R′-shading 35b is a block that corrects in-plane unevenness inherent to the device.

  The signal that has passed through the R′-shading 35b is sent to the R ′ drive D / A converter 36b. The R ′ drive D / A converter 36b receives the signal corrected according to the display device by the R′-shading 35b and converts it into a drive signal necessary for driving the device. The R ′ drive D / A converter 36b directly supplies a drive voltage necessary for driving the device 20b corresponding to the R device.

  The drive voltage from the R ′ drive D / A converter 36b is supplied to the device 20b. In the device 20b, a drive voltage is applied to the liquid crystal cell to modulate illumination light from the light source.

  The output signal from the image processing block 43 is also sent to the G′Vt block 44b. The signal that has passed through the G′Vt block 44b is sent to a G′-Shading 45b. The G′-shading 45b is a block that corrects in-plane unevenness inherent to the device.

  The signal that has passed through the G′-shading 45b is sent to the G ′ drive D / A converter 46b. The G ′ drive D / A converter 46 b receives the signal corrected according to the display device by the G′-shading 45 b and converts it into a drive signal necessary for driving the device. The G ′ drive D / A converter 46b directly supplies a drive voltage necessary for driving the device 24b corresponding to the G device.

  The drive voltage from the G ′ drive D / A converter 46b is supplied to the device 24b. In the device 24b, a drive voltage is applied to the liquid crystal cell to modulate illumination light from the light source.

  Further, the output signal from the image processing block 53 is also sent to the B′Vt block 54b. The signal that has passed through the B′Vt block 54b is sent to a B′-Shading 55b. The B′-shading 55b is a block that corrects in-plane unevenness inherent to the device.

  The signal that has passed through the B′-shading 55b is sent to the B ′ drive D / A converter 56b. The B ′ drive D / A converter 56b receives the signal corrected according to the display device by the B′-shading 55b and converts it into a drive signal necessary for driving the device. The B ′ drive D / A converter 56b directly supplies a drive voltage necessary for driving the device 13b corresponding to the B device.

  The drive voltage from the B ′ drive D / A converter 56b is supplied to the device 13b. In the device 13b, a drive voltage is applied to the liquid crystal cell to modulate illumination light from the light source.

It is a top view which shows the structure in 1st Embodiment of the image display apparatus which concerns on this invention. It is a top view which shows the structure in 2nd Embodiment of the image display apparatus which concerns on this invention. It is a graph which shows the electric drive operation | movement of the display device in the image display apparatus which concerns on this invention. FIG. 3 is a functional block diagram for driving a Y device and RGB display devices in the image display apparatus according to the present invention. It is a top view which shows the structure of the image display apparatus in the 3rd Embodiment of this invention which provided the device used as a light modulation means for every display device of RGB each color light, and used a total of 6 devices. It is a top view which shows the other example of a structure of the image display apparatus in the 3rd Embodiment of this invention which provided the device used as a light modulation means for every display device of each color light of RGB, and used a total of six devices. . It is a side view which shows the other example of a structure of the image display apparatus in the 3rd Embodiment of this invention which provided the device used as a light modulation means for every display device of each RGB light, and used a total of six devices. . It is a graph which shows the electric drive operation | movement of the display device of the image display apparatus in the 3rd Embodiment of this invention. It is a top view which shows the structure of the conventional image display apparatus.

Explanation of symbols

1 Light source 6 Y device 8 B / RG cross dichroic mirror 13 B device 13b device 14 RGB dichroic prism 20 R device 20b device 24 G device 24b device 25 Projection lens 16 R / G dichroic mirror 29 G / RB dichroic mirror 30 R / B Cross dichroic mirror

Claims (4)

A light source;
A display device that receives illumination light from the light source and modulates the illumination light according to a display image;
An imaging lens system that forms an image of illumination light that has passed through the display device;
An image display apparatus comprising: a light modulation unit that modulates the intensity of illumination light incident on the display device or illumination light that has passed through the display device in accordance with an image displayed by the display device. A light source;
Color separation means for separating illumination light from the light source into red band, green band and blue band components;
A red display device into which illumination light in the red band having passed through the color separation means is incident;
A green display device into which green band illumination light having passed through the color separation means is incident;
A blue display device on which the blue band illumination light having passed through the color separation means is incident;
Color synthesizing means for synthesizing the illumination light passed through each of the display devices;
An imaging lens system that forms an image of the illumination light that has passed through the color synthesis means;
And a light modulation unit that modulates the intensity of the illumination light incident on the color separation unit or the illumination light that has passed through the color synthesis unit in accordance with an image displayed by each display device. Display device. A light source;
Color separation means for separating illumination light from the light source into red band, green band and blue band components;
A red display device into which illumination light in the red band having passed through the color separation means is incident;
A green display device into which green band illumination light having passed through the color separation means is incident;
A blue display device on which the blue band illumination light having passed through the color separation means is incident;
Color synthesizing means for synthesizing the illumination light passed through each of the display devices;
An imaging lens system that forms an image of the illumination light that has passed through the color synthesis means;
Illumination light installed corresponding to each display device and incident on the corresponding display device via the color separation means, or illumination light incident on the color composition means via the corresponding display device, An image display device comprising: red, green, and blue light modulating means for modulating the intensity according to an image displayed by the device. The γ characteristic due to the Vt characteristic of the light modulation means is a characteristic obtained by dividing the γ tone required for the display image by the γ characteristic due to the Vt characteristic of each of the red, green and blue display devices. The image display device according to claim 2, wherein the image display device is an image display device.

Images