JP2005227477A - Optical modulator and optical display device, and optical modulation method and picture display method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical modulator suitable for realizing the enlargement of a luminance dynamic range and gradation number, the improvement of the luminance and the quality of a display picture and the miniaturization of the device. <P>SOLUTION: The projection display device 100 is equipped with a light source 10, a reflection type liquid crystal light valve 30 having a plurality of pixels which can control reflectance T1 independently, a relay lens 16 forming the optical image of the light valve 30 on the pixel surface of a color modulation light valve, dichroic mirrors 44a and 44b separating a light beam from the relay lens 16 to light beams of three primary colors RGB, a plurality of color modulation light valves having a plurality of pixels on which the light beams separated by the mirrors 44a and 44b are made incident respectively and which can control transmittance T2 independently, and a dichroic prism 48 composing the light beams from the respective color modulation light valves. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an apparatus and method for modulating light from a light source via a plurality of light modulation elements, and in particular, to expand the dynamic luminance range and the number of gradations, improve the luminance and image quality of a display image, and reduce the size of the apparatus. The present invention relates to a light modulation device, an optical display device, a light modulation method, and an image display method that are suitable for realizing the image processing.

In recent years, LCD (Liquid Crystal Display), EL, plasma display, CRT (Cathode Ray Tube), projectors, and other optical display devices have seen remarkable improvements in image quality, and the resolution and color gamut have achieved performance that is almost comparable to human visual characteristics. It is being done. However, regarding the luminance dynamic range, the reproduction range is limited to about 1 to 10 ² [nit], and the number of gradations is generally 8 bits. On the other hand, human visual perception has a luminance dynamic range perceived at a time of about 10 ⁻² to 10 ⁴ [nit], and the luminance discrimination capability is about 0.2 [nit], which is the number of gradations. Is converted to 12 bits. Looking at the display image of the current optical display device through such visual characteristics, the narrowness of the luminance dynamic range is conspicuous, and in addition, the reality and power of the display image are insufficient due to the lack of gradation in the shadow part and highlight part. Will feel unsatisfactory.

  Further, in computer graphics (hereinafter abbreviated as CG) used in movies, games, etc., display data (hereinafter referred to as HDR (High Dynamic Range) display data) that represents a luminance dynamic range and gradation number close to human vision. The movement of pursuing the reality of depiction is being mainstream. However, since the performance of the optical 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 OS (Operating System), the adoption of a 16-bit color space is planned, and the luminance dynamic range and the number of gradations are dramatically increased as compared with the current 8-bit color space. Therefore, it is desired to realize an optical display device that can make use of the 16-bit color space.
Among optical display devices, projection display devices such as liquid crystal projectors and DLP projectors are capable of displaying on a large screen and are effective in reproducing the reality and power of display images. In this field, the following proposals have been made to solve the above problems.

  As a projection display device with a high dynamic range, for example, there is a technique disclosed in Patent Document 1, which includes a light source, a first light modulation element that modulates luminance in the entire wavelength region of light, and a wavelength region of light. Among these, each wavelength region of the RGB three primary colors is provided with a second light modulation element that modulates the luminance of the wavelength region, and the light from the light source is modulated by the first light modulation element to form a desired luminance distribution, and its optical image Is imaged on the pixel surface of the second light modulation element, color-modulated, and second-order modulated light is projected. Each pixel of the first light modulation element and the second light modulation element is individually controlled based on the first control value and the second control value determined from the HDR display data. As the light modulation element, a transmission type light modulation element having a pixel structure or a segment structure whose transmittance can be controlled independently and capable of controlling a two-dimensional transmittance distribution is used. A typical example is a liquid crystal light valve.

  Consider a case where a light modulation element having a dark display transmittance of 0.2% and a bright display transmittance of 60% is used. With a single light modulation element, the luminance dynamic range is 60 / 0.2 = 300. Since the conventional projection display apparatus corresponds to optically arranging light modulation elements having a luminance dynamic range of 300 in series, a luminance dynamic range of 300 × 300 = 90000 can be realized. The same idea holds for the number of gradations, and an 8-bit gradation light modulation element is optically arranged in series, whereby a gradation number exceeding 8 bits can be obtained.

In addition, as a projection display device that realizes a high luminance dynamic range, for example, a projection display device disclosed in Patent Document 2 is known.
The invention described in Patent Document 2 includes a DMD (Digital Micromirror Device) in which a plurality of pixels are arranged in a line, an illumination unit that irradiates a light beam to the DMD, a processing unit that converts an input video signal into a DMD drive signal, An optical scanning unit that scans the light beam modulated by the DMD and a projection lens that projects the light beam from the light scanning unit onto the screen surface, and the illumination unit modulates the amount of irradiation light according to the input video signal.
Japanese Patent Laid-Open No. 2001-1000068 JP 2001-174919 A

FIG. 18 is a diagram illustrating a pixel surface of each pixel of the transmissive liquid crystal light valve.
In the transmissive liquid crystal light valve, a transistor for driving a pixel electrode is provided for each pixel. Therefore, as shown in FIG. 18, an opening (refers to a portion through which light is transmitted) in each pixel is a window. Thus, the aperture ratio is not 100%.
Therefore, in the invention described in Patent Document 1, in order to ensure the brightness of the display image, the optical image of the opening of each pixel of the first light modulation element is used as the opening of the corresponding pixel of the second light modulation element. Therefore, it is necessary to perform alignment so as to form an image accurately, and high alignment accuracy is required. However, in the invention described in Patent Document 1, there is no imaging means such as a lens between the first light modulation element and the second light modulation element. There is a problem that it is difficult to accurately transmit the optical image of the element to the pixel surface of the second light modulation element, and the luminance of the display image is lowered.

FIG. 19 is a diagram illustrating a pixel surface of each pixel of the reflective light modulation element.
In contrast to a transmissive liquid crystal light valve, a reflection type light modulation element such as a DMD can be provided with a drive unit for driving a mirror on the back surface of the mirror. The aperture ratio of the portion (referring to a part that reflects light) can be made almost 100%.

Patent Document 1 describes that the second light modulation element can be configured by DMD, but the imaging accuracy between the first light modulation element and the second light modulation element is not high. There were the following problems.
FIG. 20 is a diagram illustrating a configuration of an optical path of the first light modulation element and the second light modulation element in the projection display device described in Patent Document 1. Although other optical elements such as mirrors are also arranged on the actual optical path, these optical elements are omitted in FIG. 20 for easy understanding of the following description.

  In the optical system of FIG. 20, the first light modulation element 130 for luminance modulation is disposed on the light source side with the fly-eye lenses 112a and 112b interposed therebetween, and the color modulation element is disposed on the opposite side of the light source with the fly-eye lenses 112a and 112b interposed therebetween. The second light modulation element 140 is arranged. In this optical system, an optical image of each element lens constituting the fly-eye lens 112 a close to the first light modulation element 130 is formed on the pixel surface of the second light modulation element 140. Therefore, in order to obtain a desired luminance distribution, this luminance distribution must be formed for each element lens. By the way, the fly-eye lenses 112a and 112b are optical elements used for the purpose of uniforming the luminance distribution, and for that purpose, it is desirable that the number of element lenses is large. Then, the size of each element lens is inevitably smaller than each pixel size of the second light modulation element 140. Specifically, those having a size of about 1/3 to 1/5 are used. Now, considering that the pixels of the second light modulation element 140 and the pixels of the first light modulation element 130 have a one-to-one correspondence, the pixel density of the first light modulation element 130 is the pixel of the second light modulation element 140. 3-5 times the density is required. However, the current light modulation element (for example, a liquid crystal light valve) has a pixel density close to the upper limit of the microfabrication technology for high definition, and considering that point, the first light modulation element 130 It is difficult to achieve a pixel density of 3 to 5 times. Accordingly, the accuracy of the luminance distribution that can be formed by the first light modulation element 130 must be 3 to 5 times as coarse as the pixel density of the second light modulation element 140. Furthermore, since the optical image of each element lens is formed on the pixel surface of the second light modulation element 140 by at most two lenses, the fly-eye lens 112b and the condenser lens 12d that are far from the first light modulation element 130, Sufficient aberration correction cannot be performed and it must be considerably blurred.

On the other hand, in the invention described in Patent Document 2, since a solid-state laser or a semiconductor laser is used as a light source, there is a problem that the apparatus becomes large. In addition, when a semiconductor laser is used as the light source, there is a problem that the luminance of the display image is lowered because the light output is small.
Therefore, the present invention has been made paying attention to such an unsolved problem of the conventional technology, and has been made to expand the luminance dynamic range and the number of gradations, improve the luminance and image quality of the display image, and the apparatus. An object of the present invention is to provide a light modulation device, an optical display device, a light modulation method, and an image display method that are suitable for realizing the downsizing of the display.

[Invention 1] In order to achieve the above object, an optical modulation device of Invention 1 comprises:
A first light modulation element; and a second light modulation element that receives light from the first light modulation element, and modulates light from a light source via the first light modulation element and the second light modulation element. A device that performs
The first light modulation element is composed of a reflection type light modulation element,
A relay lens for forming an optical image of the first light modulation element on a light receiving surface of the second light modulation element is provided on an optical path between the first light modulation element and the second light modulation element. To do.

With such a configuration, the light from the light source is primarily modulated by reflecting the light from the light source toward the second light modulation element by the first light modulation element. At this time, the optical image of the first light modulation element is formed on the light receiving surface of the second light modulation element via the relay lens. The light from the first light modulation element is secondarily modulated by the second light modulation element.
Thereby, since the light from the light source is modulated via the first light modulation element and the second light modulation element, an effect that a relatively high luminance dynamic range and gradation number can be realized is obtained. In addition, since the first light modulation element is composed of a reflective light modulation element having a high aperture ratio, the brightness of the display image can be increased to some extent even if the alignment accuracy between the first light modulation element and the second light modulation element is not high. Can be secured. Therefore, the effect that it can suppress that the brightness | luminance of a display image falls compared with the past is also acquired. Further, since the optical image of the first light modulation element is formed on the light receiving surface of the second light modulation element via the relay lens, the optical image of the first light modulation element is relatively formed on the light receiving surface of the second light modulation element. In addition to being able to form an image with high accuracy, it is not necessary to reduce the light receiving surface of the first light modulation element, so that relatively high-precision modulation can be performed. Accordingly, an effect that the possibility that the image quality is deteriorated can be reduced as compared with the conventional case. Furthermore, since it is not necessary to use a solid-state laser or a semiconductor laser as a light source, an effect that the size of the apparatus can be reduced as compared with the prior art can be obtained.

Here, as the light source, any medium that generates light can be used. For example, the light source may be a light source built in an optical system such as a lamp, or may be a sun light or an indoor light. It may be an external light source. The same applies to the light modulation method of the fifth aspect.
In addition, the first light modulation element may have any configuration as long as it reflects light, and the structure may be, for example, a single plate type composed of a single light modulation element. In addition, a multi-plate type composed of a plurality of light modulation elements may be used. As a function, for example, the luminance of the entire wavelength region of light may be modulated, or the luminance of the specific wavelength region may be modulated for a plurality of different specific wavelength regions out of the wavelength region of light. It may be. The same applies to the optical display device of the invention 2, the light modulation method of the invention 5, and the image display method of the invention 6.

  In addition, the second light modulation element may have any configuration as long as it modulates light, and the structure may be, for example, a single plate type formed of a single light modulation element. In addition, a multi-plate type composed of a plurality of light modulation elements may be used. As a function, for example, the luminance of the entire wavelength region of light may be modulated, or the luminance of the specific wavelength region may be modulated for a plurality of different specific wavelength regions out of the wavelength region of light. It may be. The same applies to the light modulation method of the fifth aspect.

[Invention 2] On the other hand, in order to achieve the above object, an optical display device of Invention 2 comprises:
A light source, a first light modulation element, a light separation means for separating light from the first light modulation element into light of a plurality of different specific wavelength regions, and a plurality of light incident on the light separated by the light separation means, respectively A second light modulation element; and light combining means for combining light from the second light modulation elements, and modulates light from the light source via the first light modulation element and the second light modulation elements. And display an image,
The first light modulation element is composed of a reflection type light modulation element,
A relay lens for forming an optical image of the first light modulation element on a light receiving surface of each of the second light modulation elements is provided on an optical path between the first light modulation element and the light separation unit. .

  With such a configuration, the light from the light source is primarily modulated by reflecting the light from the light source toward the second light modulation element by the first light modulation element. Next, the light from the first light modulation element is separated into light of a plurality of specific wavelength regions by the light separation means, and the separated light is incident on each second light modulation element. At this time, the optical image of the first light modulation element is formed on the light receiving surface of each second light modulation element via the relay lens. Then, the light from the first light modulation element is secondarily modulated by each second light modulation element, and the light from each second light modulation element is combined by the light combining means to display an image.

  Thereby, since the light from the light source is modulated via the first light modulation element and the second light modulation element, an effect that a relatively high luminance dynamic range and gradation number can be realized is obtained. In addition, since the first light modulation element is composed of a reflective light modulation element having a high aperture ratio, the brightness of the display image can be increased to some extent even if the alignment accuracy between the first light modulation element and the second light modulation element is not high. Can be secured. Therefore, the effect that it can suppress that the brightness | luminance of a display image falls compared with the past is also acquired. Further, since the optical image of the first light modulation element is formed on the light receiving surface of each second light modulation element via the relay lens, the optical image of the first light modulation element is formed on the light receiving surface of each second light modulation element. In addition to being able to form an image with relatively high accuracy, it is not necessary to make the light receiving surface of the first light modulation element small, so that it is possible to perform modulation with relatively high accuracy. Accordingly, an effect that the possibility that the image quality is deteriorated can be reduced as compared with the conventional case. Furthermore, since it is not necessary to use a solid-state laser or a semiconductor laser as a light source, an effect that the size of the apparatus can be reduced as compared with the prior art can be obtained.

Here, the specific wavelength region is not limited to be set for each of the RGB three primary colors, but can be arbitrarily set as necessary. However, if it is set for each of the RGB primary colors, the existing liquid crystal light valve can be used as it is, which is advantageous in terms of cost. The same applies to the image display method of the sixth aspect.
[Invention 3] Furthermore, the optical display device of Invention 3 is the optical display device of Invention 2,
The first light modulation element is constituted by a reflective liquid crystal display element.

  With such a configuration, since the first light modulation element is configured by a reflective liquid crystal display element having a high aperture ratio, even if the alignment accuracy between the first light modulation element and the second light modulation element is not high, The brightness of the display image can be secured to some extent. In addition, polarization characteristics can be maintained in light transmission between the first light modulation element and the second light modulation element. Therefore, it is possible to further suppress the decrease in the luminance of the display image.

[Invention 4] Furthermore, the optical display device of Invention 4 is the optical display device of Invention 2,
The first light modulation element is constituted by DMD.
With such a configuration, since the first light modulation element is configured by DMD having a high aperture ratio, the brightness of the display image can be obtained even if the alignment accuracy between the first light modulation element and the second light modulation element is not high. Can be secured to some extent. In addition, the first light modulation element can be digitally driven.

[Invention 5] On the other hand, in order to achieve the above object, the light modulation method of Invention 5 includes:
A first modulation step for modulating light from the light source via the first light modulation element; and a second modulation step for modulating light from the first light modulation element via the second light modulation element. , A method of modulating light from the light source,
The first light modulation element is a reflective light modulation element;
An optical image of the first light modulation element is formed on a light receiving surface of the second light modulation element through a relay lens in an optical path between the first light modulation element and the second light modulation element. .
Thereby, an effect equivalent to that of the light modulation device of aspect 1 is obtained.

[Invention 6] On the other hand, in order to achieve the above object, an image display method of Invention 6 includes:
Light from the first light modulation element via a first modulation step for modulating light from the light source via the first light modulation element and light separation means for separating the light into a plurality of different specific wavelength regions. A light separation step for separating the light, a second modulation step for modulating the separated light via a second light modulation element for each separated light from the light separation means, and a light synthesis means for synthesizing the light A light combining step of combining the separated light from each of the second light modulation elements, and modulating the light from the light source to display an image,
The first light modulation element is a reflective light modulation element;
An optical image of the first light modulation element is formed on a light receiving surface of each of the second light modulation elements via a relay lens in an optical path between the first light modulation element and the light separation means.
Thereby, an effect equivalent to that of the optical display device of aspect 2 is obtained.

[Invention 7] Furthermore, the image display method of Invention 7 is the image display method of Invention 6,
The first light modulation element is a reflective liquid crystal display element.
Thereby, an effect equivalent to that of the optical display device of aspect 3 is obtained.

[Invention 8] Furthermore, the image display method of Invention 8 is the image display method of Invention 6,
The first light modulation element is a DMD.
Thereby, an effect equivalent to that of the optical display device of aspect 4 is obtained.

Embodiments of the present invention will be described below with reference to the drawings. 1 to 12 are diagrams showing an embodiment of a light modulation device and an optical display device, and a light modulation method and an image display method according to the present invention.
In the present embodiment, the light modulation device and the optical display device, and the light modulation method and the image display method according to the present invention are applied to a projection display device 100 as shown in FIG.

First, the configuration of the projection display device 100 will be described with reference to FIG.
FIG. 1 is a block diagram illustrating a hardware configuration of the projection display apparatus 100.
As shown in FIG. 1, the projection display device 100 includes a light source 10, a luminance distribution uniformizing unit 12 that uniformizes a luminance distribution of light incident from the light source 10, and a light incident from the luminance distribution uniforming unit 12. A luminance modulation unit 14 that modulates luminance in all wavelength regions, a relay lens 16 that relays light incident from the luminance modulation unit 14, and a luminance of RGB three primary colors in the wavelength region of light incident from the relay lens 16 are modulated. The color modulation unit 18 includes a projection unit 20 that projects light incident from the color modulation unit 18 onto a screen (not shown).

The light source 10 includes a lamp 10a such as a high-pressure mercury lamp and a reflector 10b that reflects light emitted from the lamp 10a.
The luminance modulation unit 14 includes a reflective liquid crystal light valve 30 in which a plurality of pixels whose reflectance can be controlled independently is arranged in a matrix, a polarization beam splitter 32 that transmits P-polarized light and reflects S-polarized light, and a reflective type The liquid crystal light valve 30 includes a polarization conversion element 34 made of a λ / 4 plate for improving the contrast characteristics. First, the P-polarized component of the light flux from the luminance distribution uniformizing unit 12 is incident on the reflective liquid crystal light valve 30 via the polarization beam splitter 32 and the polarization conversion element 34, and the luminance of the incident light in the entire wavelength region is reflected. The light is modulated by the liquid crystal light valve 30 and reflected. Then, the reflected light is incident on the polarization beam splitter 32 via the polarization conversion element 34, and the S-polarized component (luminance modulated light subjected to the first light modulation) of the incident light flux is transmitted via the polarization beam splitter 32. The light is emitted to the relay lens 16.

  The reflective liquid crystal light valve 30 is configured by disposing a silicon substrate having reflective pixel electrodes formed in a matrix on a surface thereof and a transparent substrate having transparent electrodes disposed therebetween via a spacer, and enclosing liquid crystal therebetween. Yes. A drive circuit for driving the reflective pixel electrode is also formed on the silicon substrate. An alignment film for aligning liquid crystals in a predetermined direction is formed on the surfaces of these two substrates. The reflective liquid crystal light valve 30 is driven in a normally white mode in which a white / bright (transmission) state is applied when no voltage is applied, and in a black / dark (non-transmission) state when a voltage is applied, or vice versa. The gradation between light and dark is analog controlled according to the given control value.

The color modulation unit 18 includes a plurality of transmissive liquid crystal light valves 40R, 40G, and 40B that have a plurality of pixels in which the transmittance can be controlled independently in a matrix and have a higher resolution than the reflective liquid crystal light valve 30. , five field lenses 42R, 42G, and 42B ₁ ~42B _3, 2 dichroic mirrors 44a, and 44b, 3 mirrors 46a, 46b, and 46c, and a dichroic prism 48, respectively composed of a plurality of lenses 2 It is composed of a pair of sub-relay lenses 50a and 50b. First, the dichroic mirror 44a of the light from the relay lens 16, as well as spectral red, green and blue RGB3 primary by 44b, the field lens 42R, 42G, 42B ₁ ~42B ₃ and transmissive liquid crystal via the mirror 46a~46c It enters the light valves 40R to 40B. The luminance of the RGB three primary colors is then modulated by the transmission type liquid crystal light valves 40R to 40B, and the modulated RGB three primary colors are synthesized by the dichroic prism 48 and emitted to the projection unit 20.

Here, the optical image of the reflective liquid crystal light valve 30 formed by the relay lens 16 is formed as an inverted optical image on the transmissive liquid crystal light valves 40R and 40G, but the optical path to the transmissive liquid crystal light valve 40B is Since the optical path length is longer than the optical path to the transmissive liquid crystal light valves 40R and 40G, an inverted optical image is formed at the dotted line position in this optical path. Therefore, in the optical path from the dichroic mirror 42b to the transmissive liquid crystal light valve 40B, an inverted optical image of the reflective liquid crystal light valve 30 formed at the dotted line position in FIG. 1 via the field lens 42B ₁ and the sub-relay lens 50a. was formed as an erecting optical image on or near the field lens 42B _2, further imaging the erect optical image through the sub-relay lens 50b as an inverted optical image on the pixel surfaces of the transmissive liquid crystal light valves 40B .

  The transmissive liquid crystal light valves 40R to 40B include a glass substrate on which pixel electrodes and switching elements such as thin film transistors and thin film diodes for driving the pixel electrodes 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 transmissive liquid crystal light valves 40R to 40B are in a normally white mode in which a white / bright (transmission) state is applied when no voltage is applied, and a black / dark (non-transmission) state is applied when a voltage is applied, or vice versa. It is driven, and the gradation between light and dark is analog controlled according to the given control value.

The dichroic prism 48 is formed by bonding four right-angle prisms, and a dielectric multilayer film that reflects red light and a dielectric multilayer film that reflects blue light are formed in an X-shaped cross section. With these dielectric multilayer films, RGB three primary colors can be synthesized.
The luminance distribution uniformizing unit 12 includes two fly-eye lenses 12a and 12b, a polarization conversion element 12c, and a condenser lens 12d. Then, the brightness distribution of the light from the light source 10 is made uniform by the fly-eye lenses 12a and 12b, and the uniformed light is polarized by the polarization conversion element 12c in the polarization direction (P polarization direction) that can be incident on the brightness modulation light valve. The collected light is condensed by the condenser lens 12 d and emitted to the luminance modulation unit 14.

  For example, the polarization conversion element 12c includes a PBS array and a half-wave plate. The half-wave plate is a birefringent element in which a phase difference occurs between S-polarized light and P-polarized light when light of a specific wavelength passes. The artificial quartz crystal is polished by setting the thickness corresponding to each specific wavelength, and bonded so that the optical axes of the respective crystals are orthogonal to each other. The half-wave plate converts linearly polarized light into linearly polarized light orthogonal to the half-wave plate, and makes its phase difference 180 ° (π).

FIG. 2 is a diagram illustrating a configuration of the relay lens 16.
The relay lens 16 forms an optical image of the reflective liquid crystal light valve 30 on the pixel surfaces of the transmissive liquid crystal light valves 40R to 40B, and is substantially symmetric with respect to the aperture stop as shown in FIG. This is an equal-magnification imaging lens composed of a front lens group and a rear lens group arranged in the lens. The front lens group and the rear lens group are configured by a plurality of convex lenses and one concave lens. However, the shape, size, arrangement interval and number of lenses, telecentricity, magnification and other lens characteristics can be appropriately changed depending on required characteristics, and are not limited to the example of FIG. In the case of constituting the relay lens 16 on either side telecentric, it is possible to omit the field lens 42R, 42G, and 42B _3. The lens configuration of FIG. 2 can be similarly applied to the configurations of the sub-relay lenses 50a and 50b.

FIG. 3 is a diagram illustrating the operating principle of the relay lens 16.
As shown in FIG. 3, the relay lens 16 is typically formed with an equal-magnification image, so that even if the pixel densities of the reflective liquid crystal light valve 30 and the transmissive liquid crystal light valves 40R to 40B are the same, The pixels of the reflective liquid crystal light valve 30 and the pixels of the transmissive liquid crystal light valves 40R to 40B can be made to correspond one-to-one. Further, since the relay lens 16 is composed of a large number of lenses, aberration correction is good, and the luminance distribution formed by the reflective liquid crystal light valve 30 can be accurately transmitted to the transmissive liquid crystal light valves 40R to 40B. it can.

  On the other hand, the projection display device 100 includes a display control device 200 (not shown) that controls the reflective liquid crystal light valve 30 and the transmissive liquid crystal light valves 40R to 40B. Hereinafter, the reflective liquid crystal light valve 30 is generically referred to as a luminance modulation light valve, and the transmissive liquid crystal light valves 40R to 40B are generically referred to as color modulation light valves. In the present embodiment, the color modulation light valve determines the display resolution (refers to the resolution perceived by the observer when the observer views the display image of the projection display device 100).

Next, the configuration of the display control apparatus 200 will be described in detail with reference to FIGS.
FIG. 4 is a block diagram illustrating a hardware configuration of the display control apparatus 200.
As shown in FIG. 4, the display control device 200 reads out from the CPU 70 that controls the operation and the entire system based on the control program, the ROM 72 that stores the control program of the CPU 70 in a predetermined area, the ROM 72, and the like. It is composed of a RAM 74 for storing data and calculation results required in the calculation process of the CPU 70, and an I / F 78 that mediates input / output of data to / from an external device, and these are used for transferring data. They are connected to each other via a bus 79 which is a signal line so as to be able to exchange data.

The I / F 78 is connected as an external device to a light valve driving device 80 that drives the luminance modulation light valve and the color modulation light valve, a storage device 82 that stores data, tables, and the like as files, and an external network 199. And a signal line for connecting.
The storage device 82 stores HDR display data.
The HDR display 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. Currently, it is used to synthesize CG objects into actual scenery, especially in the CG world. Although there are various image formats, there are many formats in which pixel values are stored in a floating-point format in order to realize a luminance dynamic range higher than a conventional image format such as sRGB. As values to be stored, physical radiance that does not consider human visual characteristics (Radiance = W / (sr · m ² )), or luminance that considers human visual characteristics (luminance = cd / m ² ). It is also a feature that it is a value regarding. In this embodiment, a format in which pixel values indicating radiance levels for each of the three primary colors of RGB are stored as floating point values for one pixel as HDR display data is used. For example, a value of (1.2, 5.4, 2.3) is stored as the pixel value of one pixel.

  The HDR display data is generated based on a HDR image having a high luminance dynamic range and a captured HDR image. However, with current film cameras and digital still cameras, HDR images with a high luminance dynamic range in nature cannot be taken at a time. Therefore, one HDR image is generated from a plurality of photographed images whose exposure is changed by some method. For details of the method for generating HDR display data, see, for example, publicly known document 1 “PEDebevec, J. Malik,“ Recovering High Dynamic Range Radiance Maps from Photographs ”, Proceedings of ACM SIGGRAPH97, pp.367-378 (1997). It is published in.

Assuming that the luminance level of the pixel p in the HDR display data is Rp, the reflectance of the pixel corresponding to the pixel p of the luminance modulation light valve is T1, and the transmittance of the pixel corresponding to the pixel p of the color modulation light valve is T2, (1) and (2) hold.

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 10 and G is a gain, both of which are constants. Tp is a light modulation rate.

From the above equations (1) and (2), it can be seen that there are an infinite number of combinations of T1 and T2 for the pixel p. However, T1 and T2 may not be arbitrarily determined. Since the image quality may deteriorate depending on the method of determination, T1 and T2 need to be appropriately determined in consideration of the image quality.
When the luminance modulation light valve and the color modulation light valve have different resolutions, the pixel p1 is imaged across a plurality of pixels of the color modulation light valve for one pixel p1 of the luminance modulation light valve, and vice versa. For one pixel p2 of the color modulation light valve, a plurality of pixels of the luminance modulation light valve are imaged on the pixel p2. Here, when calculating the reflectance T1 for the pixel p1 of the luminance modulation light valve, if the transmittance T2 of a plurality of overlapping pixels of the color modulation light valve is determined, an average value of the transmittance T2 is calculated. Considering the calculated average value and the like as the transmittance T2 of the pixel corresponding to the pixel p1 of the color modulation light valve, it is conceivable to calculate the reflectance T1 by the above equations (1) and (2). However, since the average value or the like is regarded as the transmittance T2 of the color modulation light valve, an error is inevitably generated there. This error occurs regardless of the order of determination, regardless of whether the reflectance T1 of the luminance modulation light valve is determined first or the transmittance T2 of the color modulation light valve is determined first. The modulation light valve and the color modulation light valve that determine the display resolution have a large visual influence, so it is better to minimize the error.

  Therefore, let us examine how the magnitude of the error changes depending on the order of determination. First, consider determining the transmittance T2 of the color modulation light valve first. The reflectance T1 of the pixel p1 of the luminance modulation light valve is calculated by calculating the average value or the like of the transmittance T2 of a plurality of overlapping pixels of the color modulation light valve, and using the above formula (1 ) And (2). As a result, when viewed from the pixel p1 of the luminance modulation light valve, the reflectance T1 has an error with respect to the transmittance T2 of a plurality of overlapping pixels of the color modulation light valve, but the degree of error is an average value or the like. This is the degree of error caused by statistical calculations. On the other hand, when viewed from the pixel p2 of the color modulation light valve, even if the transmittance T2 is calculated as an average value or the like of the reflectance T1 of a plurality of overlapping pixels of the luminance modulation light valve, Thus, a large error may occur that does not satisfy the above equations (1) and (2). This is because even if the relationship (a relationship satisfying the above equations (1) and (2)) with a plurality of overlapping pixels of the color modulation light valve is defined based on the pixel p1, the opposite relationship is not necessarily established. It is thought to be caused. Therefore, the error of the transmittance T2 of the color modulation light valve is likely to be larger.

The same applies to the opposite case, and when the reflectance T1 of the luminance modulation light valve is determined first, there is a high possibility that the error of the reflectance T1 of the luminance modulation light valve will be larger.
From the above, from the viewpoint of improving the image quality, the reflectance or transmittance (hereinafter referred to as reflectance or the like) of the luminance modulation light valve and the color modulation light valve that determines the display resolution is determined later. It can be concluded that the effect of error is less. In this embodiment, since the color modulation light valve determines the display resolution, the transmittance T2 of the color modulation light valve is determined later.

Further, the storage device 82 stores a control value registration table 400 in which control values of the luminance modulation light valve are registered.
FIG. 5 is a diagram illustrating a data structure of the control value registration table 400.
In the control value registration table 400, as shown in FIG. 5, one record is registered for each control value of the luminance modulation light valve. Each record includes a field in which the control value of the luminance modulation light valve is registered and a field in which the reflectance of the luminance modulation light valve is registered.

  In the example of FIG. 5, “0” is registered as the control value and “0.003” as the reflectance is registered in the first row record. This indicates that when the control value “0” is output to the luminance modulation light valve, the reflectance of the luminance modulation light valve becomes 0.3%. Note that FIG. 5 shows an example in which the number of gradations of the luminance modulation light valve is 4 bits (0 to 15 values), but in reality, there is a record corresponding to the number of gradations of the luminance modulation light valve. be registered. For example, when the number of gradations is 8 bits, 256 records are registered.

The storage device 82 stores control value registration tables 420R, 420G, and 420B in which the control values of the color modulation light valves are registered for each color modulation light valve.
FIG. 6 is a diagram illustrating a data structure of the control value registration table 420R.
In the control value registration table 420R, as shown in FIG. 6, one record is registered for each control value of the transmissive liquid crystal light valve 40R. Each record includes a field in which the control value of the transmissive liquid crystal light valve 40R is registered and a field in which the transmittance of the transmissive liquid crystal light valve 40R is registered.

  In the example of FIG. 6, “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 output to the transmissive liquid crystal light valve 40R, the transmittance of the transmissive liquid crystal light valve 40R is 0.4%. FIG. 6 shows an example in which the number of gradations of the color modulation light valve is 4 bits (0 to 15 values). However, in actuality, there is a record corresponding to the number of gradations of the color modulation light valve. be registered. For example, when the number of gradations is 8 bits, 256 records are registered.

The data structure of the control value registration tables 420G and 420B is not particularly shown, but has the same data structure as that of the control value registration table 420R. However, the difference from the control value registration table 420R is that the transmittance corresponding to the same control value is different.
Next, the configuration of the CPU 70 and the processing executed by the CPU 70 will be described.
The CPU 70 includes a microprocessing unit (MPU) or the like, starts a predetermined program stored in a predetermined area of the ROM 72, and executes display control processing shown in the flowchart of FIG. 7 according to the program. .

FIG. 7 is a flowchart showing the display control process.
The display control process is a process of determining the control values of the luminance modulation light valve and the color modulation light valve based on the HDR display data, and driving the luminance modulation light valve and the color modulation light valve based on the determined control value. When executed in the CPU 70, as shown in FIG. 7, first, the process proceeds to step S100.

In step S100, the HDR display data is read from the storage device 82.
In step S102, the read HDR display data is analyzed, and a histogram of pixel values, a maximum value, a minimum value, an average value, and the like of the luminance level 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 tone mapping is performed on the luminance level of the HDR display data to the luminance dynamic range of the projection display device 100 based on the analysis result of step S102.
FIG. 8 is a diagram for explaining tone mapping processing.
As a result of analyzing the HDR display data, it is assumed that the minimum value of the luminance level included in the HDR display data is Smin and the maximum value is Smax. Further, it is assumed that the minimum value of the luminance dynamic range of the projection display apparatus 100 is Dmin and the maximum value is Dmax. In the example of FIG. 8, since Smin is smaller than Dmin and Smax is larger than Dmax, HDR display data cannot be appropriately 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 disclosed in, for example, publicly known document 2 “F. Drago, K. Myszkowski, T. Annen, N. Chiba,“ Adaptive Logarithmic Mapping For Displaying High Contrast Scenes ”, Eurographics 2003, (2003)”. It is posted.
Next, the process proceeds to step S106, and the HDR image is resized (enlarged or reduced) in accordance with the resolution 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, where an initial value (for example, 0.2) is given as the transmittance T2 of each pixel of the color modulation light valve, and the transmittance T2 of each pixel of the color modulation light valve is provisionally determined.

  Next, the process proceeds to step S112, and based on the calculated light modulation rate Tp, provisionally determined transmittance T2 and gain G, the reflection of the luminance modulation light valve in units of pixels of the color modulation light valve according to the above equation (2). The rate T1 ′ is calculated. Here, since the color modulation light valve is composed of three transmissive liquid crystal light valves 40R to 40B, the reflectance T1 'is calculated for each of the three primary colors of RGB for the same pixel. On the other hand, since the luminance modulation light valve is composed of one reflection type liquid crystal light valve 30, the average value thereof is calculated as T1 'of the pixel.

Next, the process proceeds to step S114, and for each pixel of the luminance modulation light valve, the weighted average value of the reflectance T1 ′ calculated for the pixel of the color modulation light valve overlapping with the pixel on the optical path is used as the reflectance T1 of the pixel. Calculate as Weighting is performed based on the area ratio of overlapping pixels.
Next, the process proceeds to step S116, and for each pixel of the luminance modulation light valve, a control value corresponding to the reflectance T1 calculated for that pixel is read from the control value registration table 400, and the read control value is controlled for that pixel. Determine as value. In reading the control value, the reflectance closest to the calculated reflectance T1 is searched from the control value registration table 400, and the control value corresponding to the reflectance found by the search is read. This search is performed using, for example, a binary search method, thereby realizing a high-speed search.

  Next, the process proceeds to step S118, and for each pixel of the color modulation light valve, the weighted average value of the reflectance T1 determined for the pixel of the luminance modulation light valve that overlaps the pixel on the optical path is calculated, and the calculated average value Based on 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). Weighting is performed based on the area ratio of overlapping pixels.

  Next, the process proceeds to step S120, and for each pixel of the color modulation light valve, a control value corresponding to the transmittance T2 calculated for the pixel is read from the control value registration tables 420R to 420B, and the read control value is read from the pixel. Is determined as the control value. In the reading of the control value, the transmittance that most closely approximates the calculated transmittance T2 is searched from the control value registration tables 420R to 420B, and the control value corresponding to the transmittance found by the search is read. This search is performed using, for example, a binary search method, thereby realizing a high-speed search.

Next, the process proceeds to step S122, the control values determined in steps S116 and S120 are output to the light valve driving device 80, the luminance modulation light valve and the color modulation light valve are driven to project a display image, and a series of operations are performed. End the process and return to the original process.
Next, the operation of the present embodiment will be described with reference to FIGS.
In the following, all of the color modulation light valves have a resolution of 18 horizontal pixels × 12 vertical pixels and a gradation number of 4 bits, and the luminance modulation light valves have a resolution of 15 horizontal pixels × 10 vertical pixels and a 4-bit resolution. The case where the number of gradations is provided will be described as an example. The diagrams of the luminance modulation light valve and the color modulation light valve are both viewed from the light source 10 side.

  In the display control device 200, the HDR display data is read through steps S100 to S104, the read HDR display data is analyzed, and the luminance level of the HDR display data is determined based on the analysis result. Tone-mapped to 100 luminance dynamic range. Next, through step S106, the HDR image is resized in accordance with the resolution of the color modulation light valve.

  Next, through step S108, the light modulation rate Tp is calculated for each pixel of the resized image. For example, the light modulation rate Tp of the pixel p in the resized image is such that the luminance level Rp (R, G, B) of the pixel p is (1.2, 5.4, 2.3) and the luminance Rs (R, R, If (G, B) is (10000, 10000, 10000), then (1.2, 5.4, 2.3) / (10000, 10000, 10000) = (0.00012, 0.00054, 0.00023).

FIG. 9 is a diagram showing a case where the transmittance T2 of the color modulation light valve is provisionally determined.
Next, through step S110, 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. 10 is a diagram illustrating a case where the reflectance T1 ′ of the luminance modulation light valve is calculated for each pixel of the color modulation light valve.
Next, through step S112, the reflectance T1 ′ of the luminance modulation light valve is calculated for each pixel of the color modulation light valve. When attention is paid to the pixels p21 to p24, the reflectances T11 to T14 of the luminance modulation light valves corresponding to the pixels p21 to p24 are as shown in FIG. It can be calculated by the following formulas (3) to (6).

Actually calculate using numerical values. When Tp1 = 0.00012, Tp2 = 0.05, Tp3 = 0.02, Tp4 = 0.01, T20 = 0.1, T11 = 0.0012, T12 = 0.5, T13 = 0.2, T14 = 0.1 according to the following equations (3) to (6). Become.

T11 = Tp1 / T20 (3)
T12 = Tp2 / T20 (4)
T13 = Tp3 / T20 (5)
T14 = Tp4 / T20 (6)

FIG. 11 is a diagram illustrating a case where the reflectance T1 of each pixel of the luminance modulation light valve is determined.

  Next, through step S114, the reflectance T1 of each pixel of the luminance modulation light valve is determined. When pixels in the upper left four sections of the luminance modulation light valve are p11 (upper left), p12 (upper right), p13 (lower left), and p14 (lower right), the pixel p11 has a color as shown in FIG. Since the modulation light valve and the luminance modulation light valve have different resolutions, they overlap with the pixels p21 to p24 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, the pixel p11 can be divided into a 6 × 6 rectangular area from the least common multiple. Then, the overlapping area ratio of the pixel p11 and the pixels p21 to p24 is 25: 5: 5: 1 as shown in FIG. Therefore, the reflectance T15 of the pixel p11 can be calculated by the following equation (7) as shown in FIG.

Actually calculate using numerical values. When T11 = 0.0012, T12 = 0.5, T13 = 0.2, and T14 = 0.002, T15 = 0.008 according to the following equation (7).

T15 = (T11 × 25 + T12 × 5 + T13 × 5 + T14 × 1) / 36 (7)

Similarly to the pixel p11, the reflectances T16 to T18 of the pixels p12 to p14 can be obtained by calculating a weighted average value based on the area ratio.

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

FIG. 12 is a diagram illustrating a case where the transmittance T2 of each pixel of the color modulation light valve is determined.
Next, through step S118, the transmittance T2 of each pixel of the color modulation light valve is determined. As shown in FIG. 12A, the pixel p24 overlaps the pixels p11 to p14 on the optical path because the color modulation light valve and the luminance modulation light valve have different resolutions. Since the resolution of the color modulation light valve is 18 × 12 and the resolution of the luminance modulation light valve is 15 × 10, the pixel p24 can be divided into a rectangular area of 5 × 5 from its least common multiple. Then, the overlapping area ratio of the pixel p24 and the pixels p11 to p14 is 1: 4: 4: 16 as shown in FIG. Therefore, when attention is paid to the pixel p24, the reflectance T19 of the luminance modulation light valve corresponding to the pixel p24 can be calculated by the following equation (8). Then, the transmittance T24 of the pixel p24 can be calculated by the following equation (9) as shown in FIG. 12C when the gain G is “1”.

Actually calculate using numerical values. When T15 = 0.09, T16 = 0.33, T17 = 0.15, T18 = 0.06, and Tp4 = 0.01, T19 = 0.1188 and T24 = 0.0842 are obtained from the following equations (8) and (9).

T19 = (T15 × 1 + T16 × 4 + T17 × 4 + T18 × 16) / 25 (8)
T24 = Tp4 / T19 (9)

Similarly to the pixel p24, the transmittances T21 to T23 of the pixels p21 to p23 can be obtained by calculating a weighted average value based on the area ratio.

  Next, through step S120, for each pixel of the color modulation light valve, a control value corresponding to the transmittance T2 calculated for the pixel is read from the control value registration tables 420R to 420B, and the read control value is read out. Is determined as the control value of the pixel. For example, when T24 = 0.0842 for the pixel p24 of the transmissive liquid crystal light valve 40R, referring to the control value registration table 420R, 0.07 is the closest approximation as shown in FIG. Therefore, “7” is read from the control value registration table 420R as the control value of the pixel p24.

Then, through step S122, the determined control value is output to the light valve driving device 80. Thereby, the luminance modulation light valve and the color modulation light valve are driven, and an optical image is formed on the pixel surface of the luminance modulation light valve and the color modulation light valve.
In the projection display device 100, the light from the light source 10 is primarily modulated by the luminance modulation light valve, and the light from the luminance modulation light valve is separated into RGB three primary color lights by the dichroic mirrors 44a and 44b. Light enters each color modulation light valve. At this time, the optical image of the luminance modulation light valve is formed on the pixel surface of each color modulation light valve via the relay lens 16. The light from the relay lens 16 is secondarily modulated by each color modulation light valve, and the light from each color modulation light valve is synthesized by the dichroic prism 48 to display an image.

  In this way, in the present embodiment, the light source 10, the reflective liquid crystal light valve 30 having a plurality of pixels whose reflectance T1 can be controlled independently, and the optical image of the reflective liquid crystal light valve 30 are converted into each color modulated light. The relay lens 16 that forms an image on the pixel surface of the bulb, the dichroic mirrors 44a and 44b that separate the light from the relay lens 16 into light of the RGB three primary colors, and the light separated by the dichroic mirrors 44a and 44b are incident and transmitted. A plurality of color modulation light valves having a plurality of pixels that can control T2 independently, and a dichroic prism 48 that combines light from each color modulation light valve.

Thereby, since the light from the light source 10 is modulated through the luminance modulation light valve and the color modulation light valve, a relatively high luminance dynamic range and number of gradations can be realized.
Further, since the luminance modulation light valve is composed of the reflective liquid crystal light valve 30 having a high aperture ratio, the luminance of the display image is secured to some extent even if the alignment accuracy between the luminance modulation light valve and the color modulation light valve is not high. be able to. In addition, polarization characteristics can be maintained in light transmission between the luminance modulation light valve and the color modulation light valve. Therefore, it is possible to suppress a decrease in the brightness of the display image as compared with the conventional case.

  Furthermore, since the optical image of the luminance modulation light valve is formed on the pixel surface of each color modulation light valve via the relay lens 16, the optical image of the luminance modulation light valve is connected to the pixel surface of each color modulation light valve with relatively high accuracy. In addition to being able to image, since it is not necessary to reduce the pixel surface of the luminance modulation light valve, it is possible to perform modulation with relatively high accuracy. Therefore, it is possible to reduce the possibility that the image quality is deteriorated as compared with the conventional case.

Furthermore, since it is not necessary to use a solid-state laser or a semiconductor laser as the light source 10, it is possible to reduce the size of the apparatus as compared with the conventional case.
Furthermore, in this embodiment, an optical image of the luminance modulation light valve is connected to the pixel surface of the color modulation light valve corresponding to the optical path on the optical path having the longest optical path length among the plurality of optical paths to each color modulation light valve. Sub relay lenses 50a and 50b and a field lens 42B ₂ for imaging are provided.

As a result, as shown in FIG. 1, an optical image of the luminance modulation light valve is formed on the pixel surface of the color modulation light valve with relatively high accuracy even if a structure in which the optical path length to each color modulation light valve is different is adopted. be able to.
Further, in this embodiment, inverted through the erecting optical image of the luminance modulation light valve is imaged on the field lens 42B ₂ via the sub relay lens 50a is sub relay lens 50b on the pixel surfaces of the color modulation light valves The sub relay lenses 50a and 50b and the field lens 42B ₂ are arranged so as to form an optical image.

Thereby, an optical image of the luminance modulation light valve can be formed on the pixel surface of each color modulation light valve with substantially the same luminance distribution.
Furthermore, in the present embodiment, the luminance modulation light valve and the color modulation light valve are liquid crystal light valves.
Thereby, since an existing optical component can be used, an increase in cost can be further suppressed.

Furthermore, in the present embodiment, the luminance distribution uniformizing unit 12 that equalizes the luminance distribution of the light from the light source 10 is provided on the optical path between the light source 10 and the luminance modulation unit 14.
This can reduce the possibility of uneven brightness.
Further, in the present embodiment, the luminance distribution uniformizing unit 12 includes a polarization conversion element 12c that polarizes the light from the light source 10 in the incident polarization direction of the luminance modulation light valve.

As a result, most of the amount of light from the light source 10 is to be modulated by the luminance modulation light valve, so that the luminance of the display image can be improved.
Furthermore, in this embodiment, the transmittance T2 of each pixel of the color modulation light valve is provisionally determined, and the reflectance T1 of each pixel of the luminance modulation light valve is determined based on the provisionally determined transmittance T2 and HDR display data. The control value of each pixel of the luminance modulation light valve is determined based on the determined reflectance T1, and the transmittance T2 of each pixel of the color modulation light valve is determined based on the determined reflectance T1 and HDR display data. The control value for each pixel of the color modulation light valve is determined based on the determined transmittance T2.

Thereby, since the transmittance T2 of the color modulation light valve that determines the display resolution is determined later, the influence of the error can be suppressed, and the possibility that the image quality is deteriorated can be reduced. Furthermore, since it is not necessary to maintain the number of gradation tables corresponding to the number of gradations, even if the number of gradations is increased, the size and generation time of the gradation table do not increase so much.
Furthermore, in the present embodiment, the reflectance T1 ′ of the luminance modulation light valve is calculated for each pixel of the color modulation light valve based on the provisionally determined transmittance T2 and HDR display data, and the calculated reflectance T1 ′ is calculated. Based on this, the reflectance T1 of each pixel of the luminance modulation light valve is calculated.

  When the luminance modulation light valve and the color modulation light valve have different resolutions, rather than directly calculating the reflectance T1 of each pixel of the luminance modulation light valve based on the provisionally determined transmittance T2, it is temporarily determined. It is easier to calculate the reflectance T1 ′ of each luminance modulation light valve after calculating the reflectance T1 ′ of the luminance modulation light valve in units of pixels of the color modulation light valve based on the transmitted transmittance T2. become. Therefore, when the luminance modulation light valve and the color modulation light valve have different resolutions, the reflectance T1 of each pixel of the luminance modulation light valve can be calculated relatively easily.

Further, in the present embodiment, for each pixel of the luminance modulation light valve, the reflectance T1 of the pixel is calculated based on the reflectance T1 ′ calculated for the pixel of the color modulation light valve that overlaps the pixel on the optical path. It is supposed to be.
Thus, when the luminance modulation light valve and the color modulation light valve have different resolutions, the reflectance T1 of each pixel of the luminance modulation light valve is the transmittance of the pixel of the color modulation light valve that overlaps the pixel in the optical path. Since it is a relatively appropriate value for T2, the possibility of image quality deterioration can be further reduced. In addition, the reflectance T1 of each pixel of the luminance modulation light valve can be calculated more easily.

Further, in the present embodiment, for each pixel of the luminance modulation light valve, the weighted average value of the reflectance T1 ′ calculated for the pixel of the color modulation light valve that overlaps the pixel on the optical path is used as the reflectance T1 of the pixel. Is calculated as
Thus, when the luminance modulation light valve and the color modulation light valve have different resolutions, the reflectance T1 of each pixel of the luminance modulation light valve is the transmittance of the pixel of the color modulation light valve that overlaps the pixel in the optical path. Since it becomes a more appropriate value with respect to T2, the possibility that the image quality deteriorates can be further reduced. In addition, the reflectance T1 of each pixel of the luminance modulation light valve can be calculated more easily.

Further, in the present embodiment, for each pixel of the color modulation light valve, the transmittance T2 of the pixel is calculated based on the reflectance T1 determined for the pixel of the luminance modulation light valve that overlaps the pixel on the optical path. It is like that.
Accordingly, when the luminance modulation light valve and the color modulation light valve have different resolutions, the transmittance T2 of each pixel of the color modulation light valve is the reflectance of the pixel of the luminance modulation light valve that overlaps the pixel in the optical path. Since it is a relatively appropriate value for T1, the possibility of image quality degradation can be further reduced. Further, the transmittance T2 of each pixel of the color modulation light valve can be calculated relatively easily.

Furthermore, in the present embodiment, for each pixel of the color modulation light valve, a weighted average value of the reflectance T1 determined for the pixel of the luminance modulation light valve that overlaps the pixel on the optical path is calculated, and based on the average value Then, the transmittance T2 of the pixel is calculated.
Accordingly, when the luminance modulation light valve and the color modulation light valve have different resolutions, the transmittance T2 of each pixel of the color modulation light valve is the reflectance of the pixel of the luminance modulation light valve that overlaps the pixel in the optical path. Since it becomes a more appropriate value with respect to T1, the possibility that the image quality is deteriorated can be further reduced. In addition, the transmittance T2 of each pixel of the color modulation light valve can be calculated more easily.

Further, in the present embodiment, a luminance modulation light valve is used as the first-stage light modulation element, and a color modulation light valve is used as the second-stage light modulation element.
Accordingly, since only one light modulation element needs to be added to the conventional projection display device, the projection display device 100 can be configured relatively easily.
In the above embodiment, the reflective liquid crystal light valve 30 is the first light modulation element of the inventions 1 to 3, 5 to 7, the reflection light modulation element of the inventions 1, 2, 5 or 6, or the invention 3 or 7. Corresponding to the reflective liquid crystal display element, the color modulation light valve corresponds to the second light modulation element of the invention 1, 2, 5 or 6. The dichroic mirrors 44a and 44b correspond to the light separating means of the invention 2 or 6, and the dichroic prism 48 corresponds to the light combining means of the invention 2 or 6.

In the above embodiment, the luminance modulation light valve is configured by the reflective liquid crystal light valve 30, but instead, the luminance modulation light valve is configured by the DMD 36 as shown in FIGS. You can also.
FIG. 13 is a diagram illustrating a case where the projection display apparatus 100 is configured using the DMD 36.

As shown in FIG. 13, the projection display device 100 includes a light source 10, a luminance distribution uniformizing unit 12, a luminance modulation unit 14, a relay lens 16, a color modulation unit 18, and a projection unit 20.
The luminance modulation unit 14 includes a DMD 36 in which a plurality of pixels whose reflectance can be controlled independently are arranged in a matrix. The DMD 36 is disposed in front of the relay lens 16, and the light source 10 and the luminance distribution uniformizing unit 12 are disposed obliquely (off-axis) with respect to the DMD 36 so that light is incident at a predetermined incident angle. .

  The DMD 36 performs modulation by controlling the reflection direction of the light beam as a mirror, in other words, by time control for switching the light passing state or the blocking state. When each pixel of the DMD 36 is controlled in a predetermined frame unit, for example, if the incident light is controlled to be reflected toward the relay lens 16 for half the time of one frame, the luminance of the pixel becomes 1/2. Accordingly, the polarization beam splitter 32 and the polarization conversion element 34, which are necessary when the liquid crystal light valve is used, are unnecessary, and the light amount loss corresponding to the polarization beam splitter 32 is reduced.

FIG. 14 is a diagram illustrating a case where the projection display apparatus 100 is configured using the DMD 36.
As shown in FIG. 14, the projection display device 100 includes a light source 10, a luminance distribution uniformizing unit 12, a luminance modulation unit 14, a relay lens 16, a color modulation unit 18, and a projection unit 20.
The luminance modulation unit 14 includes a DMD 36 in which a plurality of pixels whose reflectance can be controlled independently is arranged in a matrix, and a TIR prism 38. The DMD 36 is disposed in front of the relay lens 16, and the light source 10 and the luminance distribution uniformizing unit 12 are oblique (off-axis) to the DMD 36 so that light is incident at a predetermined incident angle via the TIR prism 38. ). First, the light from the luminance distribution uniformizing unit 12 is reflected by the TIR prism 38 and is incident on the DMD 36, and the luminance in the entire wavelength region of the incident light is modulated by the DMD 36 and reflected. Then, a predetermined component of the reflected light beam is emitted to the relay lens 16 via the TIR prism 38. A TIR prism 38 is disposed between the luminance distribution uniformizing unit 12 and the DMD 36. The TIR prism 38 is used to improve the contrast characteristics of an optical system using the DMD 36, and is color modulated. The imaging relationship between the light valve and the DMD 36 is not affected.

Thus, since the luminance modulation light valve is configured by the DMD 36 having a high aperture ratio, the luminance of the display image can be ensured to some extent even if the alignment accuracy between the luminance modulation light valve and the color modulation light valve is not high. In addition, the luminance modulation light valve can be digitally driven.
In the above embodiment, since the configuration in which the light from the luminance modulation light valve is separated into the RGB three primary colors is adopted, the sub-relay lenses 50a and 50a are arranged on the optical path from the dichroic mirror 42b to the transmissive liquid crystal light valve 40B. 50b and the field lens 42B ₂ are provided, but not limited to this, as shown in FIG. 15, in the case of adopting a configuration in which light from the luminance modulation light valve is separated into light of two primary colors among the three RGB primary colors , there is no need to provide the sub-relay lens 50a, and 50b and the field lens 42B _2.

FIG. 15 is a block diagram illustrating another hardware configuration of the projection display apparatus 100.
As shown in FIG. 15, the projection display device 100 includes a light source 10, a luminance distribution uniformizing unit 12, a luminance modulation unit 14, a relay lens 16, a color modulation unit 18, and a projection unit 20.
The color modulator 18 includes two transmissive liquid crystal light valves 40RB and 40G, two field lenses 42RB and 42G, one dichroic mirror 44a, two mirrors 46a and 46b, and a dichroic prism 48. It consists of First, light from the relay lens 16 is split into two RGB primary colors (red and blue) and RGB single primary color (green) by the dichroic mirror 44a, and a transmissive liquid crystal light valve is passed through the field lenses 42RB and 42G and the mirrors 46a and 46b. Incident on 40RB and 40G. Then, the brightness of the separated RGB primary color light and single primary color light is modulated by the transmissive liquid crystal light valves 40RB and 40G, and the modulated RGB 3 primary color light is condensed by the dichroic prism 48 and emitted to the projection unit 20.

Thus, the sub-relay lenses 50a, 50b, since it is not necessary provided the field lens 42B ₁ ~42B ₃ and transmissive liquid crystal light valves 40B, it is possible to reduce the manufacturing cost.
In the above embodiment, the transmissive liquid crystal light valves 40R to 40B are configured using active matrix liquid crystal display elements. However, the present invention is not limited to this, and the transmissive liquid crystal light valves 40R to 40B are passive matrix liquid crystal display elements. A liquid crystal display element 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, since the luminance modulation light valve is composed of one reflection type liquid crystal light valve 30, one control value registration table 400 is prepared and based on the control value registration table 400. Although the configuration is such that the control value of each pixel of the luminance modulation light valve is determined, the present invention is not limited to this, and control value registration tables 400R, 400G, and 400B are prepared for each of the RGB three primary colors, and based on the control value registration tables 400R to 400B. The control value of each pixel of the luminance modulation light valve can be determined. Since the luminance modulation light valve modulates the luminance in the entire wavelength region of light, the control value registration table 400 registers the reflectance of light having typical wavelengths. However, the respective reflectances of the RGB three primary colors are not necessarily registered reflectances.

  Therefore, for the luminance modulation light valve, strictly, the reflectance corresponding to the control value is measured for each of the three primary colors of RGB, and the control value registration tables 400R to 400B are configured. Next, the reflectance T1 of each pixel of the luminance modulation light valve is determined for each of the RGB three primary colors, the reflectance closest to the reflectance T1 calculated for R is retrieved from the control value registration table 400R, and the search is performed by searching. A control value corresponding to the reflected reflectance is read out. Similarly, the corresponding control value is read out from the control value registration tables 400G and 400B based on the reflectance T1 calculated for G and the reflectance T1 calculated for B. Then, the average value of the control values read for the same pixel of the luminance modulation light valve is calculated as the control value of that pixel.

As a result, the control value of each pixel of the luminance modulation light valve becomes a relatively appropriate value with respect to the reflectance of each of the RGB primary colors of the pixel of the color modulation light valve that overlaps the pixel in the optical path. The possibility of doing so can be further reduced.
In the above embodiment, the color modulation light valve is configured as a light modulation element that determines display resolution. However, the present invention is not limited thereto, and the luminance modulation light valve is configured as a light modulation element that determines display resolution. You can also. In this case, after determining the transmittance T1 of each pixel of the color modulation light valve (the reflectance of the light modulation element determined in advance is T1), the reflectance T2 of each pixel of the luminance modulation light valve is determined. (The reflectance of the light modulation element, which will be determined later, is T2.) Is determined. Further, similarly to the above, the control value registration tables 400R to 400B are prepared for each of the three primary colors of RGB, and the control value of each pixel of the luminance modulation light valve is determined based on the control value registration tables 400R to 400B. You can also.

  Specifically, the reflectance T2 of each pixel of the luminance modulation light valve is determined for each of the RGB three primary colors, and the reflectance closest to the reflectance T2 calculated for R is searched from the control value registration table 400R. The control value corresponding to the reflectance retrieved by is read out. Similarly, the corresponding control value is read from the control value registration tables 400G and 400B based on the reflectance T2 calculated for G and the reflectance T2 calculated for B. Then, the average value of the control values read for the same pixel of the luminance modulation light valve is calculated as the control value of that pixel.

As a result, the control value of each pixel of the luminance modulation light valve becomes a relatively appropriate value with respect to the reflectance of each of the RGB primary colors of the pixel of the color modulation light valve that overlaps the pixel in the optical path. The possibility of doing so can be further reduced.
In the above embodiment, the control values of the luminance modulation light valve and the color modulation light valve are determined based on the HDR display data. However, when the normal 8-bit RGB image data for each color is used, The RGB image data of 0 to 255 is not a physical quantity of luminance but a relative value of 0 to 255. Therefore, in order to display the display device of the present invention based on normal RGB image data, the physical brightness Rp to be displayed or the reflectance Tp of the entire display device or the like must be determined from the normal RGB image. should not.

FIG. 16 is a diagram illustrating a data structure of the input value registration table 440.
Therefore, by using the input value registration table 440 of FIG. 16, it is possible to convert an input value of 0 to 255 of a normal RGB image into Tp such as physical reflectance, and the reflectance of this table. It is possible to easily change the display appearance (gradation characteristics) of a normal RGB image depending on the setting of equal Tp. Since the reflectance Tp in this table is Tp in the above equation (2), once this value is determined, the same processing as in the above embodiment is performed to reflect the reflection of a plurality of light modulation elements. The rate T1 and the transmittance T2 are determined and can be displayed.

FIG. 17 is a diagram illustrating a data structure of the input value registration table 460.
The input value registration table 460 in FIG. 17 uses the luminance Rp instead of the reflectance Tp. Since the luminance Rp in this table is Rp in the above equation (1), if this value is determined, the same processing as in the above embodiment is performed thereafter, and thereby the reflectance T1 of the plurality of light modulation elements is obtained. The transmittance T2 is determined and can be displayed.

In the above embodiment, for each pixel of the color modulation light valve, the weighted average value of the reflectance T1 determined for the pixel of the luminance modulation light valve that overlaps the pixel on the optical path is calculated, and the average value is calculated as the average value. The transmittance T2 of the pixel is calculated based on the control value, but the present invention is not limited to this. For each pixel of the color modulation light valve, the control value determined for the pixel of the luminance modulation light valve that overlaps the pixel on the optical path Based on the above, the reflectance T1 _table corresponding to the control value is read from the control value registration table 400, a weighted average value of the read reflectance T1 _table is calculated, and the transmittance T2 of the pixel is calculated based on the average value. Can also be configured to calculate.

  In the above-described embodiment, the average value of the reflectance T1 ′ calculated for each of the three primary colors of RGB for the same pixel is calculated as T1 ′ of the pixel. 'May be calculated as it is for each of the three primary colors of RGB, and in step S114, the average value of the reflectance T1 calculated for each of the three primary colors of RGB for the same pixel may be calculated as T1 of that pixel.

  In the above embodiment, for each pixel of the color modulation light valve, the weighted average value of the reflectance T1 determined for the pixel of the luminance modulation light valve that overlaps the pixel on the optical path is calculated, and the average value is calculated as the average value. The transmittance T2 of the pixel is calculated based on this, but the present invention is not limited to this. For each pixel of the color modulation light valve, the reflectance determined for the pixel of the luminance modulation light valve that overlaps the pixel on the optical path. The maximum value, the minimum value, or the average value of T1 can be calculated, and the transmittance T2 of the pixel can be calculated based on the calculated value.

  In the above embodiment, the color modulation light valve is configured by the transmissive liquid crystal light valves 40R to 40B. However, the present invention is not limited to this, and any light modulation element having a plurality of pixels whose light propagation characteristics can be controlled independently. Anything can be used. Here, the light propagation characteristics refer to characteristics that affect light propagation, and include, for example, light transmission characteristics, reflection characteristics, refraction characteristics, and other propagation characteristics.

Further, in the above embodiment, for the sake of simplicity, the light modulation element having a small number of pixels and the number of gradations is used. Processing can be performed in the same manner as in the embodiment.
Further, in the above embodiment, the gain G = 1.0 is set for the sake of simplicity, but the gain G = 1.0 is not obtained depending on the hardware configuration. Further, when considering the actual calculation cost, it is better to register the control value, the reflectance and the like in the control value registration table in a manner including the influence of the gain G.

Further, in the above embodiment, when executing the processing shown in the flowchart of FIG. 7, the case where the control program stored in advance in the ROM 72 is executed has been described. The program may be read from the storage medium storing the program into the RAM 74 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.

  In the above embodiment, the light modulation device and the optical display device, and the light modulation method and the image display method according to the present invention are applied to the projection display device 100 as shown in FIG. The present invention is not limited, and can be applied to other cases without departing from the gist of the present invention.

2 is a block diagram showing a hardware configuration of a projection display apparatus 100. FIG. 2 is a diagram illustrating a configuration of a relay lens 16. FIG. FIG. 4 is a diagram illustrating an operation principle of the relay lens 16. 3 is a block diagram illustrating a hardware configuration of a display control device 200. FIG. 6 is a diagram illustrating a data structure of a control value registration table 400. FIG. It is a figure which shows the data structure of the control value registration table 420R. It is a flowchart which shows a display control process. It is a figure for demonstrating a tone mapping process. It is a figure which shows the case where the transmittance | permeability T2 of a color modulation light valve is provisionally determined. It is a figure which shows the case where the reflectance T1 'of a brightness | luminance modulation light valve is calculated per pixel of a color modulation light valve. It is a figure which shows the case where the reflectance T1 of each pixel of a brightness | luminance modulation light valve is determined. It is a figure which shows the case where the transmittance | permeability T2 of each pixel of a color modulation light valve is determined. It is a figure which shows the case where the projection type display apparatus 100 is comprised using DMD36. It is a figure which shows the case where the projection type display apparatus 100 is comprised using DMD36. 3 is a block diagram showing another hardware configuration of the projection display apparatus 100. FIG. It is a figure which shows the data structure of the input value registration table. It is a figure which shows the data structure of the input value registration table 460. It is a figure which shows the pixel surface of each pixel of a transmissive liquid crystal light valve. It is a figure which shows the pixel surface of each pixel of a reflection type light modulation element. It is a figure which shows the structure of the optical path of the 1st light modulation element in a projection type display apparatus of patent document 1, and a 2nd light modulation element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Projection type display apparatus, 10 ... Light source, 10a ... Lamp, 10b ... Reflector, 12 ... Luminance distribution equalization part, 12a, 12b ... Fly eye lens, 12c ... Polarization conversion element, 12d ... Condensing lens, 14 ... Luminance Modulation unit, 30 ... reflective liquid crystal light valve, 32 ... polarization beam splitter, 34 ... polarization conversion element, 36 ... DMD, 38 ... TIR prism, 16 ... relay lens, 18 ... color modulation unit, 40R to 40B, 40RB ... transmission type liquid crystal light _{valves, 42R, 42G, 42B 1 ~42B} 3, 42RB ... field lenses, 44a, 44b ... dichroic mirror, 46a through 46c ... mirror, 48 ... dichroic prism, 50a, 50b ... sub relay lens, 20 ... projection unit 70 ... CPU, 72 ... ROM, 74 ... RAM, 78 ... I / F 79 ... Bus, 80 ... Light valve driving device, 82 ... Storage device, 199 ... Network, 400, 400R to 400G, 420R to 420G ... Control value registration table, 440,460 ... Input value registration table, 112a, 112b ... Flyeye Lens 112d ... Condensing lens 130 ... First light modulation element 140 ... Second light modulation element

Claims (6)

A first light modulation element; and a second light modulation element that receives light from the first light modulation element, and modulates light from a light source via the first light modulation element and the second light modulation element. A device that performs
The first light modulation element is composed of a reflection type light modulation element,
A relay lens for forming an optical image of the first light modulation element on a light receiving surface of the second light modulation element is provided on an optical path between the first light modulation element and the second light modulation element. Light modulation device. A light source, a first light modulation element, a light separation means for separating light from the first light modulation element into light of a plurality of different specific wavelength regions, and a plurality of light incident on the light separated by the light separation means, respectively A second light modulation element; and light combining means for combining light from the second light modulation elements, and modulates light from the light source via the first light modulation element and the second light modulation elements. And display an image,
The first light modulation element is composed of a reflection type light modulation element,
A relay lens for forming an optical image of the first light modulation element on a light receiving surface of each of the second light modulation elements is provided on an optical path between the first light modulation element and the light separation unit. Optical display device. In claim 2,
An optical display device, wherein the first light modulation element is constituted by a reflective liquid crystal display element. In claim 2,
An optical display device, wherein the first light modulation element is constituted by DMD. A first modulation step for modulating light from the light source via the first light modulation element; and a second modulation step for modulating light from the first light modulation element via the second light modulation element. , A method of modulating light from the light source,
The first light modulation element is a reflective light modulation element;
An optical image of the first light modulation element is formed on a light receiving surface of the second light modulation element through a relay lens in an optical path between the first light modulation element and the second light modulation element. Light modulation method. Light from the first light modulation element via a first modulation step for modulating light from the light source via the first light modulation element and light separation means for separating the light into a plurality of different specific wavelength regions. A light separation step for separating the light, a second modulation step for modulating the separated light via a second light modulation element for each separated light from the light separation means, and a light synthesis means for synthesizing the light A light combining step of combining the separated light from each of the second light modulation elements, and modulating the light from the light source to display an image,
The first light modulation element is a reflective light modulation element;
An image in which an optical image of the first light modulation element is formed on a light receiving surface of each of the second light modulation elements through a relay lens in an optical path between the first light modulation element and the light separation means. Display method.

Images