KR100747799B1 - Image display device and projector - Google Patents

Abstract

An image display apparatus for displaying an image by modulating light from a light source on the basis of display image data, comprising: a regular array of first light modulation elements arranged to modulate light from the light source and the first light modulation element; A second optical modulation element arranged to modulate the light of the light source; and an illumination optical system for guiding the light beam modulated by the first light modulation element to the second light modulation element, wherein the illumination optical system includes the first light modulation element. And an optical element for spectroscopically illuminating the light beam of the first light modulation element to a predetermined position of the second light modulation element between the second light modulation element, the optical element comprising a prism group comprising a prism element having a refractive surface. And the refracting surface refracts the incident light in a predetermined direction.

Description

IMAGE DISPLAY DEVICE AND PROJECTOR}

1 is a schematic configuration diagram of an image display device according to Embodiment 1 of the first aspect of the present invention;

2 is an explanatory diagram showing a periodic structure of a first light modulation element in the image display device according to the embodiment of the present invention shown in FIG. 1;

3 is a view showing a perspective configuration of a group of prisms in the image display device according to the embodiment of the present invention shown in FIG. 1;

4 is an explanatory diagram showing a positional relationship between a first light modulation element and a prism group included in a relay lens in the image display device according to the embodiment of the present invention shown in FIG. 1;

5 is a plan view showing a positional relationship between an opening in a first light modulation element and a group of prisms included in a relay lens;

6 is a plan view showing a positional relationship between an opening in a first optical modulation element of the image display device according to the embodiment of the present invention shown in FIG. 1 and a prism group included in a relay lens;

7 is a plan view showing the positional relationship between an opening in a first light modulation element of the image display device according to the embodiment of the present invention shown in FIG. 1 and a prism group included in a relay lens;

8 is an enlarged view of a prism group included in a relay lens in the image display device according to the embodiment of the present invention shown in FIG. 1;

9 (a) to 9 (d) divide the position of the projected image projected on the second light modulation element in the image display device according to the embodiment of the present invention shown in FIG. 1 according to the incident light on the refractive surface of the prism element. Explanatory drawing which shows,

10 is an explanatory diagram showing a state in which the projection image projected onto the second light modulation element in the image display device according to the embodiment of the present invention shown in FIG. 1 is dividedly projected by the prism element;

11 is a schematic configuration diagram of an image display device according to a modification of Embodiment 1 of the first aspect of the present invention;

12 (a) to 12 (c) show the intensity distribution of the projection light on the surface of the second light modulation element,

Fig. 13 shows the position of the opening image of the first light modulation element on the second modulation element as appropriate by changing the direction or the inclination angle of the refractive surface of the prism element provided in the optical path between the first modulation element and the second modulation element. Explanatory drawing which shows state that there is,

Fig. 14 shows that the opening image position of the first light modulation element on the second modulation element can be appropriately set by changing the direction or the inclination angle of the refractive surface of the prism element provided in the optical path between the first modulation element and the second modulation element. The explanatory drawing which shows the state that there is,

15 (a) to 15 (f) are cross-sectional schematic diagrams illustrating the shape of a prism group of a prism group provided in an optical path between a first modulation element and a second modulation element;

16 is a schematic configuration diagram showing another form of the prism group;

17 is an explanatory diagram showing the positional relationship of a projection image formed on a second light modulation element by the prism of the prism group shown in FIG. 16;

18 is a schematic configuration diagram showing still another form of the prism group;

19 is a view showing a perspective configuration of main parts of a prism group in the image display device according to the second embodiment of the first embodiment of the present invention;

20 is an explanatory diagram showing a branched state of incident light by the prism group shown in FIG. 19;

FIG. 21: is explanatory drawing which shows the positional relationship in the projection surface of the branched light ray in FIG. 20,

22A to 22D are diagrams showing an example of the light intensity distribution of the projected image on the second light modulation element;

FIG. 23 is a diagram showing a cross-sectional structure of a main part of a prism group in the image display device according to the third embodiment of the first aspect of the present invention; FIG.

24 is a diagram showing a cross-sectional structure of a main part of a prism group in the image display device according to Modification Example 1 of Example 3 of the first aspect of the present invention;

FIG. 25 is a view showing a major part perspective configuration of a prism group in the image display device according to Modification Example 2 of Example 3 of the first aspect of the present invention; FIG.

FIG. 26 is a front view showing the neighborhood of the unit area aφ on the prism group shown in FIG. 25;

27 is an explanatory diagram showing an optical path from a light source to a second light modulation element of the image display device according to the third embodiment of the first aspect of the present invention;

28 (a) and (b) are views showing the main part cross-sectional structure when the prism group is made of glass and the main part cross-sectional structure when the prism group is made of acrylic or Zeonex (brand name);

29 is a diagram showing a cross-sectional structure of a main part of a prism group in the image display device according to the third modification of the third embodiment of the first embodiment of the present invention;

30 is an explanatory diagram showing the shape of each prism element constituting the prism group shown in FIG. 29;

FIG. 31 is a view showing the main part upper surface configuration of a group of prisms in the image display device according to Modification Example 4 of Example 3 of the first aspect of the present invention; FIG.

32 is an explanatory diagram showing an example of an arrangement state of prism elements forming a prism group functioning as a low pass filter;

33 is an explanatory diagram showing an example of an arrangement state of prism elements forming another prism group functioning as a low pass filter;

34 is a diagram showing the main optical configuration of the image display apparatus (projector) according to the present invention;

35 is a diagram illustrating a configuration of a relay lens;

36 (a) and 36 (b) are explanatory diagrams of telecentricity;

37 (a) and 37 (b) are explanatory diagrams of telecentricity;

38 is a view showing a pixel plane of a liquid crystal light valve (color modulation light valve);

39 (a) and 39 (b) are explanatory diagrams conceptually showing the causes of moire;

40 (a) to 40 (c) are schematic diagrams of a schematic configuration and function of the optical low pass filter;

41 (a) and 41 (b) are more specific explanatory diagrams of the low pass filter function shown in FIGS. 40 (a) to 40 (c);

42A and 42B are explanatory diagrams of an optical image of a unit pixel;

43 is a sectional view of a liquid crystal light valve (luminance modulating light valve),

44 is a diagram showing another example of the low-pass filter;

45 is a diagram showing another example of the low-pass filter;

46 shows another embodiment of the low-pass filter;

47 shows another embodiment of the low-pass filter;

48 shows another example of the low-pass filter;

49 is a diagram showing another example of the low-pass filter;

50 shows another example of the low-pass filter;

51 shows another example of the low-pass filter;

52 is a diagram showing another example of the low-pass filter;

53 shows another example of the low-pass filter;

FIG. 54 is an explanatory diagram showing a branched state of incident light by the prism group (low pass filter) shown in FIG. 53;

FIG. 55 is an explanatory diagram showing a positional relationship in a projection plane of a branched light ray in FIG. 54;

56 is a block diagram showing the hardware configuration of a display control device;

57 is a diagram showing a data structure of a control value registration table;

58 is a diagram showing a data structure of a control value registration table;

59 is a flowchart showing display control processing;

60 is a view for explaining tone mapping processing;

61 is a diagram showing a case of temporarily determining transmittance of a color modulating light valve;

FIG. 62 is a view showing a case where the transmittance of the luminance modulated light valve is calculated in the pixel unit of the color modulated light valve; FIG.

63 (a) to 63 (c) are views showing a case of determining the transmittance of each pixel of the luminance modulating light valve;

64A to 64C are diagrams showing the case where the transmittance of each pixel of the color modulation light valve is determined.

Explanation of symbols for the main parts of the drawings

1010: light source 1012: reflector

1014: color modulation unit 1020: uniform lighting means

1021 and 1022: fly-eye lens 1023: polarization conversion element

1024: condenser lens 1030, 1035: dichroic mirror

1036, 1045, 1046: mirror

Field lenses: 1041, 1042, 1050R, 1050G, 1050B, 1170R, 1170G, 1170B

1080: cross dichroic prism 1081, 1082: dielectric multilayer film

1100: luminance modulation liquid crystal light valve 1110: projection lens

1160R, 1160G, 1160B: Transmissive Liquid Crystal Light Valve (Color Modulated Light Valve)

1200: Relay Lens

The present invention relates to an image display device such as a projector. The present invention also relates to a technique for improving image quality of an image display device, and more particularly, to an optical configuration suitable for realizing expansion and high adaptation of a dynamic range of display luminance.

This application claims priority with respect to Japanese Patent Application No. 2004-301564 for which it applied on October 15, 2004, and Japanese Patent Application No. 2004-310767 for which it applied on October 26, 2004, and uses the content here do.

In recent years, the high contrast of a video display device is calculated | required, and the expectation to a high contrast projector is increasing. Therefore, the realization of a high quality and high contrast projector is urgently needed.

There is a moire in the characteristic which becomes a problem in an image display apparatus having two spatial modulation elements of a first ruled space modulated element and a second ruled space modulated element. Moire is characterized by superposition of two or more regular patterns, and by optically uniformizing one regularity, moire can be avoided, and a low pass filter (LPF) is proposed as a solution. (See Japanese Patent Publication No. 3506144, Japanese Patent Publication No. 3230225, Japanese Patent Application Laid-open No. Hei 8-122709, and Japanese Patent Application Laid-open No. Hei 5-307174).

However, Japanese Patent Publication No. 3506144 and Japanese Patent Publication No. 3230225 are inventions related to a direct view display device, and in a display device using two spatial light modulation devices, the first light intensity distribution is made uniform. In the case where an illumination optical system for guiding the light modulated by one modulation light beam to a predetermined place of the second spatial light modulation element is determined, the effect is suppressed by the F number determined by the illumination optical system, and a sufficient effect can be obtained. Or there was a problem that the light beam guided to the second spatial modulation element caused by the diffraction by the ridge lines generated from the prism edges caused the contrast to decrease.

In addition, in the LPF defined in Japanese Unexamined Patent Publications No. Hei 8-122709 and Japanese Unexamined Patent Publication No. Hei 5-307174, the above-described problems occur, and in the diffractive optical element, second-order diffraction, third-order Contrast decreases by illumination light outside a predetermined position under the influence of diffraction or the like.

Moreover, in the birefringence system, in the illumination with a polarization component, after combining a phase plate, polarization conversion should be carried out, the fall of light utilization efficiency, the structure become complicated, and the contrast by surface reflection falls, It becomes a problem.

In recent years, the improvement of image quality in electronic display devices such as liquid crystal displays (LCDs), electro-luminescence (EL) displays, plasma displays, cathodic ray tubes (CRTs), projectors, and the like, is remarkable, and resolution and color gamut The device having a performance almost comparable to human visual characteristics has been realized. However, only in the luminance dynamic range, the reproduction range is about 1 to 10 ² [nit], and the contrast number is generally 8 bits. On the other hand, the human visual field has a dynamic dynamic range of 10 ^-2 to 10 ⁴ [nit] perceptible at one time, and a brightness discrimination ability of 0.2 [nit]. Can be. When viewing the display image of the current display device via such visual characteristics, the narrowness of the luminance dynamic range is prominent, and in addition, the gray level of the shadow portion and the highlight portion is lacking, so that the feeling of lack of reality or force of the display image is felt. do.

In addition, in CG (Computer Graphics) used for movies and games, the display data (hereinafter referred to as HDR (High Dynamic Range) display data) has luminance dynamic range and gradation characteristics close to the human's time of view, thereby improving the reality of the description. The pursuit of movement is becoming mainstream. However, there is a problem in that the expressive power of CG content cannot be sufficiently exhibited because of the lack of performance of the display device displaying it.

In addition, in the next OS (Operating System), the use of a 16-bit color space is expected, and the dynamic range and the number of gradations increase dramatically compared with the current 8-bit color space. Therefore, it is expected that the demand for realization of a high dynamic range and high gradation electronic display device capable of utilizing a 16-bit color space will increase.

Among display apparatuses, a projection display device (projector) such as a liquid crystal projector or a digital light processing (DLP) projector is capable of displaying a large screen and is an effective display apparatus for reproducing the reality and the force of a display image. In this field, the following proposal is made | formed in order to solve the said subject (for example, refer Unexamined-Japanese-Patent No. 6-167690).

The basic configuration for enlarging the luminance dynamic region is to modulate the emitted light flux from the light source in the first light modulation element to form a desired illumination light distribution, and to transmit the illumination light quantity distribution on the second light modulation element to illuminate it. will be. As the light modulation element, for example, there is a transmission type modulation element that has a structure in which a plurality of pixels are arranged two-dimensionally periodically and which can control two-dimensional transmittance distribution. Representative examples thereof include liquid crystal light valves. In addition, a reflective modulation element may be used instead of the transmission type modulation element, and a representative example thereof is a digital micromirror device (DMD) element. The first and second transmissive modulators (reflective modulators) are individually driven controlled by the first and second modulated signals made from the video signals.

Now, a case of using a light modulation element having a transmittance of 0.2% and a transmittance of 60% of a bright display is used. In the configuration in which the light modulation element is used alone, the luminance dynamic region is 60 / 0.2 = 300. On the other hand, in the above-described configuration in which the first and second light modulation elements are combined, since the light modulation elements having the brightness dynamic region of 300 correspond to optically arranged in series, in theory, a brightness dynamic region of 300x300 = 90000 can be realized. Can be. In addition, the same idea holds for the gray scale characteristic, and the gray scale characteristic exceeding 8 bits can be obtained by optically arranging the 8-bit gray scale optical modulation elements.

However, in the image display apparatus having the above configuration, when the optical image formed by the first light modulation element is transferred to the second light modulation element, the image quality deterioration due to the optical overlap between the pixel patterns of each light modulation element occurs. There is.

For example, when the first and second light modulation elements have a light shielding pattern (black stripe, black matrix, etc.) having a periodic structure, the alignment of the two is slightly misaligned, so that moire occurs and the image quality of the display image deteriorates.

The first aspect of the present invention has been carried out in view of the above circumstances, and even in the case where a regularly arranged pattern is formed on a second light modulation element on which video information modulated by a regularly arranged spatial light modulation element is projected, spatial modulation is performed. It is an object of the present invention to provide an image display device capable of displaying a high gradation image by reducing moire generated in an element pattern and a pattern provided in a second light modulation element.

In order to achieve the above object, a first aspect of the present invention is an image display apparatus for displaying an image by modulating light from a light source based on display image data, wherein the first ordered light modulates light from the light source. A modulation element, a second regularly arranged light modulation element for modulating light from the first light modulation element, and an illumination optical system for guiding the light modulated by the first light modulation element to a second light modulation element, The illumination optical system includes an optical element for spectroscopically illuminating the light beam of the first light modulation element to a predetermined position of the second light modulation element between the first light modulation element and the second light modulation element, and the optical element is provided with a refractive surface. It has a prism group which consists of a prism element provided, and the said refracting surface refracts the said incident light to a predetermined direction.

The refracting surface is a region adjacent to the incidence position when the incident light travels straight through the prism group, and is disposed between the refracting surface and a reference plane formed in a direction substantially perpendicular to the optical axis. You may have an angle.

The prism group is formed of two sets of prism elements each having a longitudinal cross-sectional shape in a first direction and having a longitudinal direction in a second direction substantially orthogonal to the first direction, wherein the two sets of prism elements Are each provided so as to be substantially perpendicular to each other in the longitudinal direction, and the trapezoidal inclined surface may correspond to the refractive surface.

In addition, the prism element has at least four the refractive surfaces, the refractive surfaces are arranged in different directions, and the optical element does not satisfy the diffraction conditions.

In addition, the shape of the prism element which forms the said prism group may be made into two or more shapes.

The pixel shift amount of the optical element may be 1/2 or less with respect to the pixel pitch in the predetermined direction.

The number of prism elements on the prism group may be determined based on the F number of the illumination optical system.

As described above, according to the first aspect of the present invention, even when a regularly arranged pattern is formed on the second light modulation element on which the image information modulated by the regularly arranged spatial light modulation element is projected, By divisionally projecting the modulated light beam, it is possible to provide a video display system capable of reducing high moiré caused by a spatial modulation element pattern and a pattern provided in the second light modulation element and displaying a high gradation image.

Moreover, the 2nd aspect of this invention was made in view of the above-mentioned situation, The image display apparatus which can suppress the image quality deterioration which arises by the optical overlap of a some optical modulation element, aiming at expansion of a brightness dynamic range. And to provide a projector.

In order to achieve the above object, a first apparatus according to a second aspect of the present invention is an apparatus for displaying an image by modulating light from a light source based on display image data, the first apparatus modulating light from the light source. A light modulation element, a second light modulation element for modulating light from the first light modulation element, and disposed between the first light modulation element and the second light modulation element and formed in the first light modulation element A relay optical system for transmitting an optical image to the pixel plane of the second light modulation element, an optical low pass filter disposed between the first light modulation element and the second light modulation element, and light from the optical low pass filter Has a microlens array concentrating on each pixel of the second light modulation element.

In this image display device, the light from the light source is modulated by two optical image forming elements via two optical modulation elements arranged in series. As a result, this image display device can realize enlargement of the luminance dynamic region and increase of the number of gradations.

Further, the relay optical system is disposed between the first light modulation element and the second light modulation element, so that optical aberration can be reduced. That is, in this image display device, light from the first light modulation element is transmitted to the second light modulation element with relatively high accuracy.

The relay optical system may be configured using any one of a transmission optical element (lens, etc.) and a reflection optical element (mirror, etc.), or may be configured using both. By the relay optical system having both sides telecentricity, uniformity of brightness, color, contrast, etc. of the image transmitted on the pixel plane of the second light modulation element is reliably achieved, resulting in good image display quality. Moreover, the tolerance range regarding the arrangement position of the second optical modulation element in the optical axis direction can be taken relatively wide, so that the design and configuration can be simplified, and the manufacturing cost can be reduced.

In the image display device described above, since an optical lowpass filter is disposed between the first light modulation element and the second light modulation element, it is peculiar to occur due to the optical overlap of the first light modulation element and the second light modulation element. Image quality deterioration is suppressed. The optical low pass filter has a function of obscuring an image, and various filters such as a prism type, a diffraction grating type, and a correction type can be applied.

As the optical image formed in the first light modulation element is blurred by the optical low pass filter, image quality deterioration due to optical overlap between pixel patterns such as moire becomes less likely to occur.

Further, in the image display device described above, the decrease in luminance due to the arrangement of the optical low pass filter is suppressed by the micro lens array. That is, the light from the optical low pass filter is concentrated on each pixel of the second light modulation element by the micro lens array, so that the brightness of the display image is improved.

Further, in the image display device, each pixel of the first light modulation element and the second light modulation element includes an opening and a light shielding portion, and the optical low pass filter covers the opening of the first light modulation element. It is preferable to bend so that a part of the light passing through may be superimposed on the dark part formed by the said light shielding part of a said 1st light modulation element.

According to this structure, the dark part formed by the light shielding part of a 1st light modulation element becomes inconspicuous on the predetermined surface, such as on the light incident surface of a 2nd light modulation element, and optical overlapping of light shielding patterns, such as moire, The phenomenon of pixel degradation due to this is more surely suppressed.

The optical low pass filter may be configured to include a group of prisms composed of a collection of prismatic elements having a refractive surface.

In this case, the prism element can be configured to include a flat portion and a polygonal prism portion.

The microlens array may be arranged on the light incident side of the second light modulation element and include a lens group corresponding one to one to each pixel of the second light modulation element.

A second apparatus according to the second aspect of the present invention is a projector and includes the image display apparatus and the projection means described above.

Since the projector is provided with an image display device which is excellent in enlarging the luminance dynamic region and increasing the quality of the display image, the large screen display can effectively reproduce the reality and the force of the display image.

[First form]

EMBODIMENT OF THE INVENTION Hereinafter, the Example of 1st aspect of this invention is described in detail with reference to drawings.

A light modulation element which is a regularly arranged modulation element used in the image display device according to the present invention, which is generated from a light source other than a self-luminous display device (e.g., an organic EL light modulation element, an LED type light modulation element). Although it is possible to use a transmissive liquid crystal light valve, a reflective liquid crystal light valve, a tilt mirror device or the like which modulates a light beam, in an image display device according to an embodiment of the present invention, The case where it is used for 2 light modulation elements is demonstrated to an example.

The structure of the image display apparatus which concerns on Example 1 of 1st aspect of this invention is shown in FIG. In the present embodiment as an image display device, a projection display device will be described as an example.

(Example 1)

In FIG. 1, the projection display device according to the present embodiment includes a light source 1010, uniform illumination means 1020 for uniformizing the luminance distribution of light incident from the light source 1010, and light incident from the uniform illumination means 1020. A color modulator 1014 for modulating the luminance of the RGB three primary colors in the wavelength region, a relay lens 1200 for relaying light incident from the color modulator 1014, and propagation of light incident from the relay lens 1200. And a projection lens 1110 for projecting the light incident from the luminance modulation liquid crystal light valve 1100 onto a screen (not shown).

The light source 1010 is comprised of lamp 1011, such as a high pressure mercury lamp, and the reflector 1012 which reflects the light emitted from the lamp 1011. The uniform illumination means 1020 consists of two fly-eye lenses 1021 and 1022, the polarization conversion element 1023, and the condensing lens 1024. As shown in FIG. The luminance distribution of the light from the light source 1010 is equalized by the two fly-eye lenses 1021 and 1022, and the uniformized light is polarized in the incident light polarization direction of the color modulation light valve by the polarization conversion element 1023. The polarized light is condensed by the condensing lens 1024 and emitted to the color modulator 1014.

The polarization converting element 1023 is composed of, for example, a PBS array and a half-wave plate, and has a function of converting random polarized light into specific linearly polarized light.

The color modulating unit 1014 includes three transmissive liquid crystal light valves (color modulating light valves) 1160R, 1160G, and 1160B as first light modulation elements in which a plurality of pixels capable of independently controlling transmittance are arranged in a matrix. ), Eight field lenses 1041, 1042, 1050R, 1050G, 1050B, 1170R, 1170G, 1170B, two dichroic mirrors 1030, 1035, and three mirrors 1036, 1045, 1046 and a cross dichroic prism 1080.

The transmissive liquid crystal light valves 1160R, 1160G, and 1160B are provided with a glass substrate in which a pixel electrode and a switching element such as a thin film transistor element or a thin film diode for driving the same are formed in a matrix form, and a glass substrate having a common electrode formed over its entire surface. It is an active matrix liquid crystal display element which hold | maintained TN type liquid crystal and arrange | positioned the polarizing plate on the outer surface.

The transmissive liquid crystal light valves 1160R, 1160G, and 1160B operate in a normally white mode or a reversely normal black mode in which a voltage is not applied to a white / light (transmissive) state and a voltage is applied to a black / dark (nontransparent) state. Driven, contrast between contrasts is analog controlled in accordance with the applied control value.

The cross dichroic prism 1080 is formed by joining four rectangular prisms, and a multilayer dielectric film 1081 reflecting blue light and a dielectric multilayer film 1082 reflecting red light are formed in a cross-sectional X shape. have. These dielectric multilayer films 1081 and 1082 can synthesize RGB primary colors.

First, the light from the uniform illumination means 1020 is spectroscopically divided into the RGB primary colors of red, green and blue by the dichroic mirrors 1030 and 1035, and also the field lenses 1041 and 1042 and the mirrors 1036 and 1045. And 1046, the light enters the transmissive liquid crystal light valves 1160R, 1160G, and 1160B. Then, the luminance of the spectroscopic RGB trichromatic light is modulated by the transmissive liquid crystal light valves 1160R, 1160G, and 1160B, and the modulated RGB trichromatic light is synthesized by the cross dichroic prism 1080 to relay the lens. Exit at 1200.

The relay lens 1200 projects the light synthesized by the cross dichroic prism 1080 in the direction of the transmissive liquid crystal light valve (luminance modulating liquid crystal light valve) 1100 as the second light modulation element. In the relay lens 1200 shown in FIG. 1, the prism group 1025 which is a low pass filter is arrange | positioned in the pupil position which is the conjugate position of an aperture. The prism group 1025 is provided in the optical path between the first light modulation elements (color modulation liquid crystal light valves) 1160R, 1160G, 1160B and the second light modulation elements (luminance modulation liquid crystal light valves) 1100. The detail of the structure of the prism group 1025 is mentioned later.

The luminance modulating liquid crystal light valve 1100 is equivalent to the color modulation liquid crystal light valves 1160R, 1160G, and 1160B described above. The luminance modulating liquid crystal light valve 1100 modulates the luminance of the full-wavelength region of the incident light and exits the projection lens 1110.

2 shows a periodic structure in the transmissive liquid crystal light valve 1160R which is the first light modulation element. The liquid crystal panel of the transmissive liquid crystal light valve 1160R seals the liquid crystal layer for image display between two transparent substrates. On the light incident side of the liquid crystal layer, a black matrix portion 1062 for shielding light is provided. The black matrix part 1062 does not emit toward the second light modulation element 1030 by shielding the R light incident from the lamp 1011 such as the ultra-high pressure mercury lamp in FIG. 1. In addition, the rectangular region surrounded by the black matrix portion 1062 forms the opening 1061.

The opening 1061 passes R light from the lamp 1011. The R light passing through the opening 1061 passes through the substrate and the liquid crystal layer. The polarized light component of R light incident on the transmissive liquid crystal light valve 1160R is modulated in the liquid crystal layer. As such, forming pixels in the projected image is light that has been modulated in the liquid crystal layer and transmitted through the opening 1061. The opening 1061 is a pixel portion that transmits light forming the pixel. In the transmissive liquid crystal light valve 1160R functioning as a spatial light modulation device, a plurality of openings 1061 which are pixel portions are arranged in a matrix.

The transmissive liquid crystal light valve 1160R can be regarded as having a rectangular periodic region composed of an opening 1061 and a black matrix portion 1062 around the opening 1061. Adjacent periodic regions are arranged repeatedly repeatedly without intervals.

Thus, the transmissive liquid crystal light valve 1160R functioning as a spatial light modulation device has a periodic structure of patterns with regularity on the exit side of the modulated light. In addition, the structure of the transmissive liquid crystal light valve 1160G and 1160B is the same as that of the transmissive liquid crystal light valve 1160R.

Since the transmissive liquid crystal light valves 1160R, 1160G, and 1160B all have the same configuration, the light from the opening 1061 of each transmissive liquid crystal light valve 1160R, 1160G, and 1160B is projected so as to overlap exactly. Therefore, when the prism group 1025 is not provided, the image of the pattern in which the periodic regions are repeatedly arranged by the light from each of the transmissive liquid crystal light valves 1160R, 1160G, and 1160B is used as it is. 1100 is formed.

Hereinafter, the configuration of the present invention will be appropriately described using the projection image projected on the second light modulation element 1100.

3 illustrates a perspective configuration of the prism group 1025. A prism group 1025 composed of a plurality of prism elements 1071 is formed on the surface of the ejection side of the transparent plate 1070 made of glass or transparent resin. The transmissive liquid crystal light valve 1160R and the prism group 1025 in the relay lens 1200 are arranged in the relationship shown in FIG. 4. In order to make understanding easy, in FIG. 4, illustration of the other structure except the transmission type liquid crystal light valve 1160R and the prism group 1025 is abbreviate | omitted.

The R light passing through the opening 1061, which is one pixel portion, proceeds as a cone-shaped divergent light.

This R light is incident on the prism group 1025 of at least part of the prism group 1025. The prism group 1025 is composed of a prism element 1071 having at least a refractive surface 1072 and a flat portion 1073. The flat part 1073 is a surface substantially parallel to the surface 1080a in which the opening 1061 is formed. As for the prism element 1071, the width | variety PT and the depth H from the ridgeline of the refracting surfaces 1072 to the flat part 1073 are substantially the same. Accordingly, in the prism group 1025, a plurality of prism elements 1071 are arranged in a regular cycle at regular intervals.

The flat portion 1073 transmits the R light from the opening 1061 as it is. The refracting surface 1072 refracts and transmits R light from the opening 1061. The refracting surface 1072 has a direction and an inclination angle of the refracting surface 1072 that guides the opening 1061 image onto the black matrix portion 1062 image in the second light modulation element 1030. The refracting surface 1072 refracts light from one opening 1061 in a predetermined direction to guide the image onto the black matrix portion 1062 image. As a result, in the second light modulation element 1030, the opening 1061 image is formed overlapping with the area of the black matrix portion 1062 image.

5, 6, and 7 are plan views showing the positional relationship between the opening 1061 and the prism group 1025. In these drawings, each prism element 1071 has a substantially square shape as shown in FIG. 7. And with respect to the direction of the center line CL of the strip | belt-shaped black matrix part 1062 shown in FIG. 5, as shown in FIG. 6, the direction along the periphery part 1071a of each prism element 1071 is comprised in about 45 degrees. It is. As described above, the light transmitted through one opening 1061 is incident on a part of the prism group 1025 including the plurality of prism elements 1071.

8 is an enlarged view of the prism group 1025. Consider a case where the medium (for example, air) between the prism group 1025 and the second light modulation element 1100 has a refractive index n1, and a member constituting the prism group 1025 has a refractive index n2. In addition, the refractive surface 1072 is formed so that it may become angle (theta) with respect to the reference surface 1073a which extended the flat part 1073. As shown in FIG. Hereinafter, the angle θ is called an inclination angle. Of the light passing through the relay lens 1200, light in the optical axis direction is incident substantially perpendicular to the flat part 1073. Light incident perpendicularly to the flat portion 1073 goes straight without being refracted by the flat portion 1073 to form a projection image on the second light modulation element 1100.

In contrast, light incident on the refracting surface 1072 is refracted to satisfy the following conditional expression.

Here, angle (alpha) is an incident angle based on the normal line N of the refractive surface 1072, and angle (beta) is an injection angle. Further, in the second light modulation element 1100 separated from the prism group 1025 by the distance L, the distance S between the position of the straight light and the position of the refracted light is expressed by the following equation.

Thus, by controlling the prism inclination angle θ of the refracting surface 1072, the distance S which is the shift amount of the opening image 1061P in the second light modulation element 1100 can be arbitrarily set. In addition, as is apparent from FIG. 8, the direction in which the light beam LL2 is refracted depends on the direction of the refracting surface 1072. In other words, by controlling the direction of the refractive surface 1072 with respect to the opening 1061, the direction in which the opening image 1061P is formed in the second light modulation element 1100 can be arbitrarily set.

In the case of using the transmissive liquid crystal light valve 1160R functioning as a spatial light modulation device (first light modulation device) having the above-described configuration, a projection image by R light projected on the second light modulation device 1100 is shown. It demonstrates with reference to 9 (a)-FIG. 9 (d). FIG. 9A shows one periodic region image 1063P in the second light modulation element 1100. Light incident substantially perpendicularly to the flat portion 1073 of the prism element 1071 travels straight through the refracting action at the flat portion 1073. The straight light forms an opening image (directly transmitted image) 1061P at the center of the periodic region image 1063P in the second light modulation element 1100.

Next, light incident on the refractive surface 1072a of the prism element 1071 is considered. The light incident on the refracting surface 1072a is subjected to the refracting action by the refraction direction, the refraction amount, and the refraction light amount corresponding to the refraction surface 1072a direction, the inclination angle θ, and the area P1, respectively. As described above, the prism element 1071 is configured such that the edge portion 1071a forms about 45 ° with respect to the centerline CL of the black matrix portion 1062. For this reason, for example, the light refracted by the refraction surface 1072a is, as shown in Fig. 9 (a), the opening image (at a position away from the opening image (direct transmission image) 1061P by the distance S described above in the arrow direction. 1061 Pa). In all the following descriptions, it is assumed that there is no inversion of the top, bottom, left and right of the image due to the imaging action of the relay lens 1200.

Similarly, the light refracted by the refracting surface 1072b forms an opening image 1061Pb at the position shown in Fig. 9B. The light refracted by the refracting surface 1072c forms an opening image 1061Pc at the position shown in Fig. 9C. The light refracted by the refracting surface 1072d forms an opening image 1061Pd at the position shown in Fig. 9D. 9A to 9D illustrate the same periodic region image 1063P by dividing each opening image 1061Pa, 1061Pb, 1061Pc, and 1061Pd.

In practice, these four opening images 1061Pa, 1061Pb, 1061Pc, and 1061Pd overlap and are projected as shown in FIG. As described above, the prism element 1071 includes four refractive surfaces 1072a, 1072b, 1072c, and 1072d, so that the opening image 1061P of the opening 1061 is divided into four opening images 1061Pa, 1061Pb, 1061Pc, and 1061Pd. ) To be projected onto the second light modulation element 1100. By dividing the opening image 1061P into a plurality, the periodicity of the projection light caused by arranging the openings 1061 in a matrix form is weakened. In addition, by dividing the opening image 1061P into a plurality, it is also possible to weaken the periodicity such as a regular shape in the image. By weakening the periodicity of the projection light incident on the second light modulation element 1100, the interference effect of light is reduced even when the second light modulation element 1100 having a periodic structure is used.

In this manner, by providing the prism group 1025 as the low pass filter, the generation of moire can be reduced. The prism group 1025 is placed in the optical path between the transmission type liquid crystal light valves (color modulation light valves) 1160R, 1160G, and 1160B, which are the first light modulation elements, and the second light modulation elements (luminance modulated liquid crystal light valves) 1100. Since the interference of light can be reduced regardless of the configuration of the second light modulation element 1100, the second light modulation element 1100 needs to be configured to reduce the interference of light. Disappears.

The second light modulation element 1100 can be configured to be capable of displaying a fine image and reducing costs without being subject to structural limitations to enable the interference of light to be prevented. As a result, the effect of reducing the occurrence of moire and displaying a fine image can be obtained.

In particular, in the present embodiment, as shown in FIG. 10, the inside of the periodic region image 1063P is filled in the opening images 1061Pa, 1061Pb, 1061Pc, and 1061Pd without gaps. Thus, the prism element 1071 is arranged such that the intersections CPa, CPb, CPc, CPd of the centerline image CLP of the black matrix portion image 62P and one corner portion of the opening image (directly transmitted image) 1061P approximately coincide with each other. The direction of the refracting surface 1072 and the inclination angle θ are set. For this reason, the unevenness of the projection light to the second light modulation element 1100 can be reduced, thereby reducing the periodicity of the projection light.

Returning to FIG. 7, it is assumed that one side of the square prism element 1071 has a length La, and one side of the flat portion 1073 has a length Lb. The area La × La occupied by one prism element 1071 of the prism group 1025 is assumed to be a unit area. The flat portion 1073 has an area FS = Lb × Lb.

In addition, four refractive surfaces 1072a, 1072b, 1072c, and 1072d have areas P1, P2, P3, and P4, respectively. Here, the light amount of light passing through the flat portion 1073 and going straight corresponds to the area FS of the flat portion 1073 occupying a unit area.

Similarly, the total amount of light refracted by the four refracting surfaces 1072a, 1072b, 1072c, and 1072d corresponds to the total area P1 + P2 + P3 + P4 of the refracting surfaces 1072a, 1072b, 1072c, and 1072d occupying a unit area.

Here, if the areas P1, P2, P3, and P4 of the four refractive surfaces 1072a, 1072b, 1072c, and 1072d are substantially the same size, the total area P1 + P2 + P3 + P4 = 4 x P1. In other words, by controlling the area of the flat part 1073 or the refractive surface 1072, the light amount of the light to go straight and the light amount of the light to be refracted can be arbitrarily set.

In order to effectively reduce the moire, it is preferable that the amount of light of the projected image (directly transmitted image) passing through the flat portion 1073 and going straight is equal to the amount of light of the projected image refracted by the refracting surface 1072. For example, if the length La = 1.0 and the length Lb = 0.707, the unit area of the prism element 1071 is 1.0 (= 1.0 × 1.0), and the area FS of the flat portion 1073 is 0.5 = (0.707 × 0.707). In addition, the total area (4xP1) in which the four refractive surfaces 1072a, 1072b, 1072c, and 1072d each having the same area is added is 0.5 (= 1.0-0.5).

By designing the prism element 1071 as described above, the amount of light transmitted through the flat portion 1073 and going straight and the total amount of light refracted by the four refractive surfaces 1072a, 1072b, 1072c, and 1072d can be equalized.

Thus, the light intensity ratio can be designed freely by designing the area ratio of the prism face to a desired ratio.

A prism group 1025 that is a low pass filter is disposed in the optical path between the first light modulation element (color modulation liquid crystal light valve) 1160R, 1160G, 1160B and the second light modulation element (luminance modulation liquid crystal light valve) 1100. Any configuration may be used. For example, as in the projection display device shown in FIG. 11, the prism group 1025 may be provided on the exit surface of the cross dichroic prism 1080. By setting each color light synthesized by the cross dichroic prism 1080 into the prism group 1025, the prism group 1025 can be made into one, and the projection display device can be made simple. .

The prism group 1025 may be provided between the first light modulation elements 1160R, 1160G, and 1160B and the cross dichroic prism 1081, respectively. If it is the structure which provides the prism group 1025 for every color light, the refractive angle setting corresponding to each wavelength can be set.

As a more preferred embodiment, as shown in Fig. 11, the low-pass filter can be miniaturized by inserting the prism group 1025, which is the low-pass filter, at the position where the projection light is concentrated at a high density by inserting it into the pupil position of the optical path. The uniformity of light intensity can be made compatible.

In addition, the light modulation element is not limited to the case where a transmissive liquid crystal display device is used. As a liquid crystal display device, you may use a reflective liquid crystal display device. Further, another micro device, for example, a tilt mirror device, DMD has a structure in which the micro mirrors are arranged in a matrix. For this reason, even when using DMD as a spatial light modulation apparatus, moire can be reduced similarly to the case of using a liquid crystal display device. In addition, even when using a self-light emitting element, for example, an organic EL element, it is possible to reduce the occurrence of moire due to the periodic structure of the pixel.

12 (a) to 12 (c) illustrate changes in the intensity distribution of the projection light by providing the prism group 1025. In the graphs shown in Figs. 12A to 12C, the vertical axis represents the intensity I of the projection light and the horizontal axis represents the distance x in the X direction (I and x are all arbitrary units). The distance S (see FIG. 8), which is the movement amount of the opening image 1061P, is a distance of about 1/2 or less of the pitch of the plurality of openings 1061 by the inclination angle θ of the refracting surface 1072 of the prism group 1025. . Here, the pitch of the some opening 1061 means the distance between the center positions of the adjacent opening 1061.

In the second light modulation element 1100, it is assumed that three images of the opening portion 1061 which is the pixel portion are arranged around the positions of x = 0, 20, and 40 respectively. When the prism group 1025 is not provided, the projection light A1 represents an intensity distribution with the center of the image of the opening 1061 as a peak. In addition, since the image of the opening 1061 is projected onto the second light modulation element 1100 as it is, the positions of x = 10 and 30 where the image of the black matrix portion 1062 is formed have the intensity I of the projection light approximately zero. . As the maximum and minimum values of the intensity I of the projection light and the difference ΔI increase, the periodicity of the projection light is enhanced, and moire is likely to occur.

When providing a group of prisms 1025 that form an image of the opening 1061 at a position about a half of the pitch of the opening 1061, the light from the opening 1061 is light that goes straight to the refracting light. Separated by. The intensity of the light B2 going straight from the opening 1061 becomes weaker as compared with the light A1 by separating some of the light. The light refracted by the prism group 1025 becomes the light C2 having the intensity of peaking at the positions of x = 10 and 30 which are half pitch shifted positions. The light A2 which combines the light B2 which advances the prism group 1025 and the light C2 which refracts can make small the intensity difference (DELTA) I compared with the light A1.

When providing a group of prisms 1025 that form an opening image at a distance of about a quarter of the pitch of the opening 1061, the light from the opening 1061 is a straight line B3 and a quarter of a pitch. The light is separated into light C3 and D3 having the misaligned position as a peak. The light A3 which combines the light B3, C3, D3 can make intensity intensity (DELTA) I small compared with light A1. When the intensity difference ΔI is made small, the regularity of the projection light resulting from the pixel structure is weakened, and the interference of light in the periodic structure of the second light modulation element 1100 can be reduced.

In addition, the interference of light due to the overlap of the periodic structure and the shape of the image in the projection display device can also be reduced. In this manner, by providing the prism group 1025 for guiding the projected image of the opening 1061 at a position at a distance of about 1/2 or less of the pitch of the opening 1061 that is the pixel portion, the occurrence of moire can be reduced. Can be.

Although the description has been given using an example of shifting the projection image of the opening 1061 in the X direction, the distance not exceeding about 1/2 of the pitch of the opening 1061 is not limited to the X direction but also in the Y direction. The projection image of the opening 1061 may be guided to the position. In addition, when shifting the projection image of the opening part 1061 to the position of the inclination direction, it is assumed that the projection image is guided to the position of the distance of about 1/2 or less of the pitch of the inclination direction of the plurality of openings 1061. Also good.

The prism group 1025 can appropriately set the position of the opening 1061 image in accordance with the direction or the inclination angle of the refractive surface 1072 of the prism element 1071. For example, as shown in FIG. 13, the opening part image 151P is isolate | separated into the position separated by the distance S in the inclination 45 degree direction shown by the arrow. Further, a new opening image 1150P may be formed by four opening images 1151Pa, 1151Pb, 1151Pc, and 1151Pd. As shown in FIG. 14, the opening image 1152P may be separated by a distance S and a new opening image 1153P may be formed by superimposing two opening images 1152Pa and 1152Pd.

15A to 15F show various modifications of the prism element shape. For example, FIG. 15A illustrates a prism group 1161 provided with a trapezoidal prism element having a refractive surface 1161a and a flat portion 1161b at predetermined intervals.

FIG. 15B shows a prism group 1162 having a refracting surface 1162a and a flat portion 1162b and provided with a trapezoidal prism element without gaps.

FIG. 15C shows a prism group 1163 having a refractive surface 1163a and a flat portion 1163b and provided with triangular prism elements at predetermined intervals.

15 (d) shows a group of blazed prisms 1164 made up of only the refracting surface 1164a.

Fig. 15E shows a group of prisms 1165 in which the height of the flat portion and the prism pitch are random and there is almost no periodicity for generating diffraction by the prism edges.

15 (f) shows a group of prisms 1166 having a common height but having a random prism pitch and reducing the influence of diffraction by suppressing periodicity which is a diffraction condition.

In this way, various modifications can be made using the direction, the inclination angle and the area of the refractive surface as parameters.

Fig. 16 shows a schematic configuration in which a part of another form of the prism group is enlarged. The prism group 1210 is composed of a square prism-shaped first prism element 1211 and a square prism-shaped second prism element 1212. The first prism element 1211 is formed such that one side thereof is approximately 45 ° to the center line CL. The second prism element 1212 is formed such that one side thereof is substantially parallel to the center line CL. In addition, a flat portion 1215 is provided around the first prism element 1211 and the second prism element 1212.

As shown in FIG. 17, the opening image (direct transmission image) 1220P is formed by the light which permeate | transmitted the flat part 1215. As shown in FIG. The opening surface 1213P is formed by the refracting surface 1213 of the first prism element 1211 in the 45 ° direction with respect to the centerline image CLP. The opening surface 1214P is formed in the direction parallel to the centerline image CLP by the refracting surface 1214 of the second prism element 1212. Then, the direction of the refracting surface and the inclination angle are set so that these projected images fill the black matrix portion 1062 image without gaps. As a result, the intensity unevenness of the projected image can be reduced.

In addition, the shape of the prism group that causes the same refractive effect as that of the prism group 1210 can take various modifications. For example, a prism group 1230 having a refractive surface 1231 and a flat portion 1232 as shown in FIG. 18 may be used. In this manner, the prism refraction surface and the flat surface can be formed in any shape with a desired area ratio.

(Example 2)

Next, an image display device according to Embodiment 2 of the first aspect of the present invention will be described. Since the schematic structure of an image display apparatus is basically the same as that of Embodiment 1, the same code | symbol is attached | subjected to the component same as Embodiment 1, and the overlapping description is abbreviate | omitted.

19 shows the principal part perspective structure of the prism group 1240 which functions as a low pass filter in the image display apparatus which concerns on Example 2 of the 1st form of this invention.

The prism group 1240 is composed of two sets of prism elements 1241a and 1241b. The prism element 1241a has a substantially trapezoidal cross-sectional shape in the y-axis direction that is the first direction. The prism element 1241a has a longitudinal direction in the x-axis direction, which is a second direction that is substantially orthogonal to the y-axis direction, which is the first direction.

In the trapezoidal shape of the cross-sectional shape in the y-axis direction of the prism element 1241a, two inclined surfaces Y1 and Y2 function as a refractive surface. In addition, the upper surface Y0 of the cross-sectional shape in the y-axis direction of the prism element 1241a functions as a flat part. For this reason, the light incident on the inclined surface Y1 or the inclined surface Y2 is refracted in the direction corresponding to the angle of the inclined surface. The refracted transmission image is formed by the refracted light. In addition, the light incident on the upper surface Y0 is transmitted as it is. The transmitted image is formed by the transmitted light as it is.

Prism element 1241b has the same structure as prism element 1241a. In the cross-sectional shape of the prism element 1241b in the x-axis direction, two inclined surfaces X1 and X2 function as refractive surfaces. In addition, in the cross-sectional shape of the prism element 1241b in the x-axis direction, the upper surface X0 functions as a flat portion. The two sets of prism elements 1241a and 1241b are provided so that their respective longitudinal directions are substantially orthogonal to each other.

The prism group 1240 in the image display device according to the present embodiment is fixed to the flat side of the prism element 1241a and the flat side of the prism element 1241b. However, it is not limited to this, Any structure of the following (1)-(3) may be sufficient.

(1) A configuration in which the surfaces on which the inclined surfaces Y1, Y2 and the like of the prism element 1241a are formed and the surfaces on which the inclined surfaces X1 and X2 and the like of the prism element 1241b are formed are fixed to face each other.

(2) A configuration in which the inclined surfaces Y1, Y2, and the like of the prism element 1241a are formed, and the surface of the prism element 1241b is fixed to face each other.

(3) A configuration in which the planar side of the prism element 1241a and the surface on which the inclined surfaces X1, X2 and the like of the prism element 1241b are formed are fixed to face each other.

In addition, although FIG. 19 demonstrated the structure which a prism surface contacts, the structure which both surfaces contact air may be sufficient.

20 shows the branching of incident light by the prism group 1240. In FIG. 20, incident light XY progresses from the left to the right. In addition, in a part of FIG. 20, the light ray is specified using the code | symbol of inclined surface Y0, Y1, Y2 for convenience of description. Incident light XY is split into three light beams by the prism element 1241a shown by the dotted line, the light beams Y1 and Y2 refracted by the inclined plane, and the light beam Y0 passing through the upper surface as it is. The three light beams Y0, Y1, and Y2 branched further are further branched into three light beams by the prism element 1241b. As a result, incident light XY branches into nine light beams Y1X1, Y1X0, Y1X2, Y0X1, Y0X0, Y0X2, Y2X1, Y2X0, Y2X2.

Next, the position in the projection surface of the branched nine light beams is demonstrated using FIG. The area of the direct transmission image by the ray Y0X0 is shown by the part enclosed by the bold border. The projection image of the pixel portion by the refracted light may be formed in a direction orthogonal to the longitudinal directions of the prism elements 1241a and 1241b, respectively. The prism group 1240 is comprised so that the longitudinal direction of two sets of prism elements 1241a and 1241b may be substantially orthogonal. Thereby, regions of the refractive transmission image by eight rays Y1X1, Y1X0, Y1X2, Y0X1, Y0X2, Y2X1, Y2X0, Y2X2 are formed around the area of the direct transmission image by the ray Y0X0. In FIG. 26, the code | symbol of a light ray is attached | subjected to each area | region, and is shown. In addition, the direct transmission image by the ray Y0X0 is formed to be adjacent to each other periodically corresponding to the positions of the plurality of openings 1061 in the first light modulation element (FIGS. 2, 4, and 5). The prism group 1240 forms the refractive-transmission image in the area | region between direct transmission images by the ray Y0X0 by the prism elements 1241a and 1241b. Accordingly, the periodicity of the projection light can be reduced.

In addition, the prism group 1240 is PW0 and the inclined surfaces Y1, Y2, X1, and X2 are the sum of the light intensities through the top surface Y0 of the prism element 1241a, which is a flat surface, and the top surface X0 of the prism element 1241b. When the total of the light intensity passing through is PW1, respectively, PW0 ≧ PW1 is satisfied. In addition, both PW0 and PW1 are light intensities in the second light modulation element 1100.

The sum of the light intensities of the direct-transmitted image by the ray Y0X0 corresponds to the areas of the upper surfaces Y0, X0 which are flat portions. In addition, the sum total of the light intensities of the refractive transmission images by the rays Y1X1, Y1X0, Y1X2, Y0X1, Y0X2, Y2X1, Y2X0, Y2X2 corresponds to the areas of the inclined surfaces Y1, Y2, X1, X2 which are refractive surfaces. Here, when the sum PW1 of the light intensities of the refractive transmission images by the rays Y1X1, Y1X0, Y1X2, Y0X1, Y0X2, Y2X1, Y2X0, Y2X2 becomes larger than the sum PW0 of the light intensities of the directly transmitted image, the observer is, for example, ghost-like Double images may be recognized.

In this embodiment, it is configured to satisfy PW0≥PW1. For this reason, the generation of moire can be reduced similarly to the first embodiment. In addition, it is preferable to satisfy PW0> PW1. More preferably, it is desirable to satisfy PW0> 0.9 × PW1. As a result, it is possible to maintain the original pixel information while making the light intensity distribution by the pixel arrangement uniform, thereby reducing the moire and obtaining a high definition projection image.

Fig. 22A shows the light intensity distribution of the projected image in the second light modulation element 1100. Figs. In FIG. 22A, the horizontal width indicates a position coordinate on the second light modulation element 1100, and the vertical axis indicates an arbitrary intensity unit, respectively. For the sake of simplicity, the BB cross section passing through approximately the center of the three regions of the region I of the direct transmission image, the region K of the adjacent direct transmission image, and the region J between these regions will be described. That is, the part indicated by the symbol I of the horizontal axis of FIG. 22A corresponds to the region I of FIG. 21, the part indicated by the symbol J corresponds to the region J of FIG. 21, and the part indicated by the symbol K is the region of FIG. 21. It corresponds to K.

As shown in Fig. 22A, in the second light modulation element 1100, the projection of the opening 1061 in the first light modulation element 1160R formed by the light from the upper surfaces Y0 and X0 which are flat portions is shown. The first peak value Pa of the intensity distribution of the region I of the image, the region K is the first of the intensity distribution of the region J of the projection image of the projection image of the opening 1061 formed by the light via the inclined planes Y1, Y2, X1, X2 that are the refractive surfaces. It is larger than 2 peak value Pb.

For example, the second peak value Pb is set at approximately half the power distribution of the first peak value Pa. The power distribution of this light intensity can be controlled according to the area ratio of the upper surface Y0, X0 of the prism elements 1241a and 1241b, and the inclined surface Y1, Y2, X1, X2.

In addition, about the area | region between 1st peak value Pa and 2nd peak value Pb, it becomes light intensity according to predetermined intensity distribution curve CV. As a result, it is possible to reduce the periodicity of the projection light and to reduce the generation of moire.

Modifications of the light intensity distribution are shown in Figs. 22 (b), 22 (c) and 22 (d), respectively. In Fig. 22B, two first peak values Pc of the light intensity distributions of the regions I and K are larger than the second peak value Pd of the region J, respectively. In Fig. 22 (c), the first peak value Pe of the light intensity distributions of the region I, the region K is greater than the two second peak values Pf of the region J. In Fig. 22 (d), the first peak value Pg of each of the light intensity distributions of the region I and the region K is approximately the same size as the second peak value Pg of the region J. In these power distributions, the periodicity of the projection light can be reduced, thereby reducing the generation of moire.

(Example 3)

Next, an image display device according to Embodiment 3 of the first aspect of the present invention will be described. Since the schematic structure of the image display apparatus which concerns on Embodiment 3 of 1st Embodiment of this invention is the same as that of Embodiment 1, the same code | symbol is attached | subjected to the same part as Embodiment 1, and the overlapping description is abbreviate | omitted.

FIG. 23 is a sectional view of an essential part of the group of prisms 1280 functioning as a low pass filter in the image display device according to the third embodiment of the first aspect of the present invention.

In the prism group 1280, the two refractive surfaces 1280a form a groove having a periodic V shape. The reference surface 1281 formed in the direction substantially perpendicular to the optical axis AX at a position farthest from the flat portion 1280b at the intersection of the refractive surface 1280a and the optical axis AX, and the flat portion 1280b are separated by a distance d. The distance d corresponds to the depth of the V-shaped groove. Hereinafter, the distance d is appropriately referred to as the depth d. The distance d satisfies the conditional formula (1-1) or (1-2).

Here, the refractive index of the members constituting the prism group 1280 is n and the wavelength of light incident on the prism group 1280 is λ, respectively. In this embodiment, the distance d (depth) is set to 1100 nm.

The depth of the V-shaped groove is the conditional formula (1-A),

을 만족하면, 프리즘군(1280)에 의한 회절 효과가 향상되게 된다.

If satisfied, the diffraction effect by the prism group 1280 is improved.

In the present embodiment, light in the visible light region is used among the light from the lamp 1011 such as an ultra-high pressure mercury lamp as incident light. For example, in the case of the wavelength λ = 480 nm of incident light and the refractive index n = 1.46 of the prism group 1280, from the conditional formula (1-A),

로 된다.

It becomes

Similarly, in the case of the wavelength λ = 650 nm of the incident light and the refractive index n = 1.46 of the prism group 1280, from the conditional formula (1-A),

로 된다.

It becomes

In this manner, when the wavelength? Of the incident light is 480 nm, the diffracted light is effectively generated when the depth d of the V-shaped groove is 522 nm. Further, when the wavelength? Of the incident light is 650 nm, diffracted light is effectively generated when the depth d of the V-shaped groove is 707 nm. The diffracted light may cause moire due to interference of light in the second light modulation element 1100 having a periodic structure. In this embodiment, it is preferable that the depth d of the V-shaped groove does not cause diffracted light, or is such that the observer does not recognize even when diffracted light occurs.

For this reason, in this embodiment, the conditional expression (1-1) or (1-2) is satisfied, and may be different from the distance d (depth) defined by the conditional expression (1-A). For example, in the present Example, in the case of wavelength (lambda) = 480 nm, from conditional formula (1-1),

From conditional formula (1-2),

로 된다.

It becomes

Further, if the same calculation is performed at the wavelength λ = 650 nm, from the conditional formula (1-1),

From conditional formula (1-2),

로 된다.

It becomes

In the present embodiment, as described above, the depth d = 1100 nm. As a result, the conditional expression (1-2) is satisfied for any wavelength?, So that generation of diffracted light in the prism group can be reduced. As a result, the effect of reducing the occurrence of moire can be obtained.

In this embodiment, it is preferable to satisfy the following conditional formula (1-3) or (1-4).

More preferably, it is preferable to satisfy the following condition formula (1-5) or (1-6).

By satisfying any one of the conditional formulas (1-3) to (1-6), the intensity of the diffracted light from the prism group 1280 can be further reduced. Accordingly, the occurrence of moire can be further reduced.

FIG. 24 is a sectional view of a principal part of a group of prisms 1290 that functions as a low pass filter in the image display device according to Modification Example 1 of the present embodiment. The same description as that of the prism group 1280 is omitted. In this modification, the distances d1, d3, d5 from the reference plane 1291 to the flat portion 1290b and the distances d2, d4, d6 from the reference plane 1291 to a predetermined position on the refracting surface 1290a are each non-periodic. It is formed to be. The reference surface 1291 is substantially perpendicular to the optical axis AX and is one surface of the substrate on which the group of prisms 1290 is formed. Here, the predetermined position on the refracting surface 1290a refers to a position closest to the reference plane 1291 among the refracting surfaces 1290a.

One of the structures in which diffracted light is generated by the prism group 1290 is a periodic structure of the prism element. In the present embodiment, the aperiodic configuration described above can reduce the generation of diffracted light due to the periodic structure of the prism element. By reducing the generation of diffracted light in the prism group, the generation of moire can be reduced. In addition, by randomizing the groove depth where the refracting surface is formed and the pitch of the flat portion as shown in Fig. 15F, the diffracted light causing the moire can be reduced.

Fig. 25 shows a major portion perspective configuration of a prism group 1300 functioning as a low pass filter in the image display device according to the second modification of the present embodiment. The same description as that of the prism group 1280 described above is omitted. In this modification, the prism elements 1301 of the prism group 1300 are arranged on the transparent plate 1302 along the shapes of substantially straight lines La1, La2, La3, La4, La5. The number of straight lines La1, La2, La3, La4, La5 is approximately five per unit area aφ. Moreover, the number of substantially straight lines La1, La2, La3, La4, La5 should just be 15 or less per unit area. The prism element 1301 is provided at a cycle of 15 times or less per unit area. The description of the unit area aφ will be described later.

It is a front view of unit area aphi vicinity. Approximately orthogonal to substantially straight lines La1, La2, La3, La4, La5, and six straight lines of approximately straight lines Lb1, Lb2, Lb3, Lb4, Lb5, and Lb6 are formed. The straight lines Lb1, Lb2, Lb3, Lb4, Lb5, and Lb6 may also be 15 or less per unit area. As described above, the prism elements 1301 of the prism group 1300 are formed in a substantially orthogonal lattice shape.

FIG. 27 shows an optical path from the lamp 1011 to the second light modulation element 1100, such as an ultrahigh pressure mercury lamp, for explaining the unit area aφ. In FIG. 27, for the sake of simplicity, only the lamp 1011 constituting the illumination system ILL, the integrator 1013, and the relay lens 1200 constituting the relay system PL are shown in the optical system, and other color separation optical systems are illustrated. Omit. In addition, the relay lens 1200 is shown as a biconvex single lens for convenience. In FIG. 27, the relay lens 1200 and the relay system PL coincide. For convenience, the light transmitted through the first light modulation element (spatial light modulation device) 1160R is shown.

Illumination light from lamp 1011 is incident on integrator 1013. The integrator 1013 overlaps the illumination light from the lamp 1011 to illuminate the first light modulation element (spatial light modulation device) 1160R. Illumination light from the integrator 1013 has a predetermined angle distribution and is incident on the first light modulation element (spatial light modulation device) 1160R. The position OBJ on the first light modulation element (spatial light modulation device) 1160R is superimposed by light of various incidence angles. The light from the position OBJ is incident on the prism group 1300 while spatially widening to the F number of the illumination system ILL. The light emitted from the first light modulation device (spatial light modulation device) 1160R passes through the prism group 1300 and is incident to the relay lens 1200.

The modulation surface of the first light modulation element (spatial light modulation device) 1160R and the second light modulation element 1100 are in an conjugate relationship. For this reason, the position OBJ on the first light modulation element (spatial light modulation device) 1160R is imaged at the position IMG on the second light modulation element 1100. At this time, the light from the position OBJ on the first light modulation element (spatial light modulation device) 1160R is equal to the F number of the relay lens 1200, or the light having the smaller F number is generated by the projection lens 20. 2 is projected onto the light modulation element 1100. The F number of the illumination system ILL and the F number of the relay system PL consider the following three relationships (B), (C) and (D).

(B) F number of lighting system ILL> F number of relay system PL

(C) F number of lighting system ILL = F number of relay system PL

(D) F number of lighting system ILL <F number of relay system PL

In any relationship, on the first light modulation element (spatial light modulation device) 1160R, only the light in the angular range in which the illumination system ILL or the relay system PL is defined as the smaller F number is effectively used for the second light modulation element 1100. Is projected on. For example, in the case of relationship (B) or (C), the following equation is established.

Here, FILL is the F number of the relay system PL, and θa is the angle formed with the optical axis of the light emitted from the position OBJ.

Light emitted from the first light modulation element (spatial light modulation device) 1160R at a spatial expansion angle θa irradiates a unit area aφ, which is a circular area on the prism group 1300. As such, all the light from the unit area aφ on the prism group 1300 is projected from the relay lens 1200 to the second light modulation element 1100. On the other hand, in the case of the relational conditional expression (D), the unit area aφ on the prism group 1300 that is effectively projected onto the second light modulation element 1100 by the F number of the illumination system ILL is defined.

Therefore, in any relationship (B), (C), or (D), the light from the unit area aφ on the prism group 1300 is effectively projected onto the second light modulation element 1100 by the relay lens 1200. . As described above, one of the structures in which diffracted light is generated by the prism group 1300 may include a periodic structure of the prism element array. In this modification, the prism group 1300 is arranged along the shapes of substantially straight lines La1 to La5 and Lb1 to Lb6 per unit area aφ. For this reason, the number of substantially straight lines is 15 or less per unit area aphi. Accordingly, generation of diffracted light due to the periodic structure of the prism element array can be reduced, and generation of moire can be reduced.

In addition, the prism element is provided at least 1 cycle or more, preferably 3 cycles or more, in the unit area aφ, whereby a substantially uniform image can be obtained.

The total sum of the areas of the refracting surface 1072 and the flat area 1073 that are refracted in a predetermined direction per unit area aφ may be the same value in any unit area. Accordingly, the projected image is reduced in the diffracted light, and also overlaps the area of the projected image of the black matrix portion 1062 in the second light modulation element 1100 separated by a predetermined distance from the prism group 1300. A projected image of 1061 is formed. Therefore, by reducing the unevenness of the projection light to the second light modulation element 1100, it is possible to reduce the periodicity of the projection light.

With reference to FIG. 32, the form of the prism group which comprises a prism group which functions as a lowpass filter is further demonstrated. 32 shows an example of arranging prisms of shapes different in size, appearance, and refraction direction. When the area defined by the diameter φ defined by the illumination optical system is defined as the unit area φS, in the region φS shown in FIG. 32, the prism element 2810 and the upper right, lower right and left upper sides, which are refracted up, down, left and right, The prism element 2811 refracting in the lower left four directions is arranged, and is arranged at a predetermined ratio within the region phi S. In this example, the number of prism arrange | positioned in the unit area of diameter (phi) is two on the straight line shown by the arrow, and 19 in the circle within diameter (phi). By arranging a plurality of different prism elements in this manner, the light beams can be refracted at a predetermined ratio in the predetermined direction within the region? S while avoiding diffraction of the transmitted light beams.

At this time, there are two prism elements in contact with the diameter φ, which is one of the arbitrary straight lines shown in FIG. 32, and the number of edges of the boundary of the prism element perpendicular to the arrow which may be the cause of diffraction on this diameter straight line (arrow). Is four.

Next, with reference to FIG. 33, the form of the prism group which comprises another prism group is further demonstrated. In the case where the area | region prescribed | regulated by the diameter phi prescribed | regulated by an illumination optical system is made into unit area phi S, in area phi S shown in FIG. The number of cycles of the prism element in the direction of the arrow is 4, and the number of edges of the boundary of the prism element perpendicular to the arrow that may cause diffraction is 11.

In this way, it is preferable that at least one prism element is disposed on any diameter straight line in the unit area. As a result, the light beam incident on the second light modulation device 1100 can be made uniform, and moire can be effectively reduced.

Moreover, it is preferable that the number of edges of the boundary of the prism element perpendicular | vertical to the straight line of diameter in a unit area is 50 or less. By the number of the edges of the boundary of the prism element perpendicular to the straight line in the unit area determined by the illumination optical system being 50 or less, the influence of diffraction occurring at the edge portions of the prism group can be suppressed and the decrease in contrast due to the diffracted light Can be.

In addition, it is preferable that the number of edges of the boundary of the prism element substantially perpendicular to the diameter straight line in the unit area determined by the illumination optical system is 30 or less. Thereby, the influence of the diffraction which arises in the edge part of a prism group can further be suppressed, and the fall of contrast by diffracted light can be reduced.

More preferably, the number of edges of the boundary of the prism element perpendicular to the straight line of the diameter within the unit area determined by the illumination optical system is 15 or less.

As a result, an image display apparatus capable of recording a higher quality image can be obtained. More preferably, the number of edges is 10 or less. Further, as shown in FIG. 32, the prism 2810 and the prism 2811 having the refractive surfaces guiding in different directions are inserted into and arranged in the phi S, so that an approximately vertical prism edge intersects on a line of any diameter within the phi S. Since the number can be suppressed, diffraction due to the prism edge can be suppressed to enable high gradation image display.

FIG. 28A shows the principal part cross-sectional configuration when the prism group 1330 is made of glass. In this case, the depth d1 is about 30 nm and the angle θ1 with respect to the reference plane 1331 is about 0.06 °. 28 (b) shows the principal part cross-sectional structure in the case where the prism group 1330 is comprised with acrylic or Zeonex (brand name). On the prism group 1330, an optically transparent resin substrate 1332 and a glass substrate 1333 are formed. In this case, the depth d 2 is about 1 μm and the angle θ 2 is about 0.97 °. Thus, since both depth and angle become large compared with the structure of FIG. 28 (a), manufacture of the prism group 1330 becomes easy.

Fig. 29 shows a sectional configuration of principal parts of a group of prisms 1340 serving as a low pass filter in the image display device according to the third modification of the present embodiment. The same description as that of the prism group 1280 described above is omitted. The prism group 1340 of the present modification is configured by alternately arranging three prism elements 1341a, 1341b, and 1341c, and fixing them with an optical adhesive. As shown in FIG. 30, the prism elements 1341a and 1341c are strip | belt-shaped prism elements in which the direction in which the refractive surfaces 1351a and 1352c are inclined mutually is formed. The prism element 341b is a parallel flat plate on which the flat portion 1351b is formed. The prism group 1340 is formed by arranging a plurality of sets of prism elements 1341a, 1341b, and 1341c as one set. In addition, the prism group 1340 is provided in two directions orthogonal to each other. Thereby, it has a function similar to the prism group which has the flat part 1351b and the refracting surfaces 1351a and 1351c which refracts in two directions orthogonally orthogonal.

In this modification, the substantially flat prism elements 1341a, 1341b, and 1341c may be manufactured. For this reason, the prism group 1340 can be manufactured very simply. Further, diffraction light can be reduced by arranging the prism elements 1341a, 1341b, and 1341c to 15 or less per unit area aφ.

Fig. 31 shows the main part upper surface configuration of the prism group 1360 functioning as the low pass filter in the image display device according to the fourth modification of the present embodiment. The same description as that of the prism group 1280 described above is omitted. In the prism group 1360 of this modification, the positions and depths of the prism elements 1361a, 1361b, and 1361c are arranged aperiodically (randomly) within the unit area aφ. Accordingly, diffracted light can be reduced.

In addition, the sum total of the area of the refracting surface 1362 and the area of the flat part 1363 may be made the same value in any unit area aφ per unit area aφ.

In addition, this invention is not limited to each structure described in each Example of this invention. The prism group may be a structure that does not cause diffracted light, or a structure that is not recognized by an observer even when generating diffracted light may be a structure that arbitrarily combines the structures of the embodiments of the present invention.

(Production method of prism group)

3, the manufacturing method of the prism group 1071 is demonstrated. The prism group 1071 is integrally formed on the exit surface of the injection-side dustproof transparent plate 1070. The injection side dustproof transparent plate 1070 is a transparent parallel flat glass. Prismatic groups 1071 are formed on one surface of the parallel plate glass by photolithography. Specifically, the photoresist layer is patterned on the parallel flat glass so as to have a desired prism shape, for example, a rectangular weight shape, using a gray scale method to form a mask. The prism group 1071 is formed by a reactive ion etching (RIE) method using a fluorine-based gas such as CHF ₃ .

The prism group 1071 can also be formed by a wet etching method using hydrofluoric acid. In this way, the injection-side dustproof transparent plate 1070, which is a parallel flat glass having a prism group 1071 formed on one surface thereof, is embedded in the most ejection side in the manufacturing process of the liquid crystal panel.

In addition, another manufacturing method of the prism group 1071 will be described. Optical epoxy resin is apply | coated to one side of parallel plate glass. Next, as a desired prism shape, a mold having a pattern in which unevenness is reversed is prepared. Then, the mold is transferred by pressing the die with an epoxy resin. Finally, an ultraviolet-ray is irradiated to an optical epoxy resin and hardened | cured, and the prism group 1071 is formed.

In the case of metamorphosis, another method may be employed. The parallel plate glass is heated and softened to the extent necessary for mold transfer. And the die mentioned above is pressed and mold-transferred to one surface of the softened parallel plate glass. Also by this, the prism group 1071 can be formed in parallel flat glass.

In addition, the prism group 1071 is not limited to the case where it is integrally formed in the injection-side dustproof transparent plate 1070. For example, the prism group 1071 of a desired prism shape is manufactured as a separate pattern sheet by a hot press method. Then, the pattern sheet is cut to the required size. Next, the cut pattern sheet is adhered to the injection side of the parallel plate glass using an optically clear adhesive. Also by this, the prism group 1071 can be formed in parallel flat glass.

More preferably, it is preferable to prevent dust or the like from adhering to the surface of the prism group 1071. For this reason, the coating layer which consists of a transparent resin of low refractive index, etc. is formed with respect to the injection side of the prism group 1071. For example, the prism group 1071 is formed of an optical epoxy high refractive index resin having a refractive index of n = 1.56. The coating layer is formed of, for example, an optical epoxy low refractive index resin having a refractive index n = 1.38. In addition, the refractive index of the member which comprises the prism group 1071 and the refractive index of a coating layer can also be made to correspond substantially. As a result, the positional shift on the second light modulation element 1100 of the refracted light due to the deviation of the manufacturing error of the refractive surface 1025 can be reduced.

(Relationship between Wavelength and Prism Element Shape)

In the above description, R light is described as a representative example, but the basic configuration of the liquid crystal panel of the second color light spatial light modulator for G light and the liquid crystal panel of the third color light spatial light modulator for B light is The same as in the case of the R light. Specifically, each of the first color light spatial light modulating device, which is the first light modulation element, the second color light spatial light modulating device, and the third color light spatial light modulating device each has a prism group that is a refraction portion.

Here, the angle refracted at the refracting surface depends on the wavelength of light. For this reason, when accurately controlling the position of the image to be refracted and projected in the second light modulation element, it is preferable to consider the wavelength of the light to be refracted. For example, an ultrahigh pressure mercury lamp, which is a light source, has an emission spectrum distribution when the horizontal axis represents wavelength and the vertical axis represents any intensity. The light having a peak wavelength in the bright spectrum of about 440 nm is used as the B light and the light having about 550 nm is used as the G light. Moreover, the light of about 650 nm vicinity which is the center wavelength of a light quantity integral value is used as R light. When light of these wavelengths is refracted at the refracting surface, the inclination angle θ of the refracting surface is controlled so as to form a predetermined projection image on the second light modulation element. Thereby, a high quality image with few color shifts can be obtained on the second light modulation element.

(Example)

For example, when the pitch PT of the prism element shown in FIG. 8 is 1 mm, the optimum height (depth) H is about 1.7 micrometers.

In addition, when a prism group is formed on the exit side of a liquid crystal panel, for example, a quartz substrate surface, a numerical example is given about the inclination-angle (theta) of a prism element. For example, let the distance S = 8.5 micrometer which is the movement amount on a 2nd light modulation element. At this time, the inclination angles θ of each prism element in the R light, the G light, and the B light are 0.31 °, 0.31 °, and 0.30 °, respectively. The inclination angle is different for each color because, as described above, the refractive index of the members constituting the prism group varies depending on the wavelength.

In addition, when providing the prism group for each color in the incident surface of each color light of a cross dichroic prism, the inclination-angle (theta) of each prism element in R light, G light, and B light is 0.10 degrees and 0.10 degrees, respectively. , 0.099 °.

Thus, since the inclination-angle (theta) is a small value, when forming a prism group by cutting, for example, it may be difficult. Thus, at the interface of the prism group, a material having a refractive index close to that of the members constituting the prism group is formed into a mold. Thereby, inclination angle (theta) can be made large and a prism group can be manufactured easily.

For example, the difference in refractive index between the members constituting the prism group and the material to be molded is 0.3. At this time, when each prism group is formed on the exit side of the liquid crystal panel, the amount of movement on the second light modulation element is S = 8.5 μm, and the inclination angles of the R light, the G light, and the B light are θ is 1.16 °, 1.17 ° and 1.18 °, respectively. In addition, in this case, when providing each color prism group in the incident surface of each color light of a cross dichroic prism, the inclination-angle (theta) of each prism element in R light, G light, and B light is 0.31 degrees, respectively. , 0.31 ° and 0.31 °.

[Second form]

EMBODIMENT OF THE INVENTION Hereinafter, the Example of 2nd aspect of this invention is described with reference to drawings.

In this embodiment, as the first light modulation element, a transmissive liquid crystal light valve is provided for each of the other color light of R (red), G (green), and B (blue), and the transmissive liquid crystal light valve is also used for the second light modulation element. An example of a projection liquid crystal display (projector) will be described.

(The overall configuration of the projector)

Fig. 34 is an example of the embodiment of the image display device of the second aspect of the present invention and the projector of the present invention, which shows the main optical configuration of the projector PJ1.

As shown in FIG. 34, the projector PJ1 has RGB among the light source 2010, the uniform illumination system 2020 which equalizes the luminance distribution of the light incident from the light source 2010, and the wavelength region of the light incident from the uniform illumination system 2020. A color modulator 2025 (including three transmissive liquid crystal light valves 2060B, 2060G, and 2060R as first light modulation means) for modulating luminance of three primary colors, an optical low pass filter 2080, and a color; A relay lens 2090 for relaying light incident from the modulator 2025 and a transmissive liquid crystal light valve 2100 as second light modulation means for modulating the luminance of the full-wave region of the light incident from the relay lens 2090 And a projection lens 2110 for projecting light incident from the liquid crystal light valve 2100 onto a screen (not shown).

The light source 2010 includes a lamp 2011 made of an ultra-high pressure mercury lamp, a xenon lamp, and the like, and a reflector 2012 for reflecting and condensing the emitted light from the lamp 2011.

The uniform illumination system 2020 includes two lens arrays 2021 and 2022 made of fly-eye lenses, a polarization conversion element 2023, and a condenser lens 2024. Then, the luminance distribution of the light from the light source 2010 is equalized by the two lens arrays 2021 and 2022, and the uniformized light is polarized in the incident possible polarization direction of the color modulator by the polarization conversion element 2023, and polarized. A light is collected by the condenser lens 2024 and emitted to the color modulator 2025. Moreover, the polarization conversion element 2023 is comprised from a PBS array and a 1/2 wavelength plate, for example, and converts random polarization into specific linearly polarized light.

The color modulation unit 2025 includes two dichroic mirrors 2030 and 2035 as light separation means, three mirrors (reflection mirrors 2036, 2045 and 2046), five field lenses (lens 2041, relays). A lens 2042, parallelizing lenses 2050B, 2050G, and 2050R, three liquid crystal light valves 2060B, 2060G, and 2060R, and a cross dichroic prism 2070 are configured.

The dichroic mirrors 2030 and 2035 separate (spread) the light (white light) from the light source 2010 into RGB primary colors of red R, green G, and blue B. The dichroic mirror 2030 reflects B light and G light on a glass plate or the like and forms a dichroic film having a property of transmitting R light, thereby being included in the white light with respect to the white light from the light source 2010. Reflects B light and G light and transmits R light. The dichroic mirror 2035 reflects G light on a glass plate or the like to form a dichroic film having a property of transmitting B light. Among the G light and B light reflecting the dichroic mirror 2030, the G light is reflected. The reflection is transmitted to the parallelizing lens 2050G, and the blue light is transmitted to the lens 2041.

The relay lens 2042 transmits light (light intensity distribution) near the lens 2041 to the vicinity of the parallelizing lens 2050B, and the lens 2041 has a function of efficiently injecting light into the relay lens 2042. Have The B light incident on the lens 2041 is transmitted to the liquid crystal light valve 2060B which is spatially separated with almost no intensity loss and its intensity distribution.

The parallelizing lenses 2050B, 2050G, and 2050R roughly parallelize each color light incident on the corresponding liquid crystal light valves 2060B, 2060G, and 2060R, and efficiently transmit the light transmitted through the liquid crystal light valves 2060B, 2060G, and 2060R. This has a function of making the relay lens 2090 incident. In addition, the light of the RGB three primary colors spectroscopically detected by the dichroic mirrors 2030 and 2035 is reflected in the above-described mirrors (reflection mirrors 2036, 2045, 2046) and lenses (lens 2041, relay lens 2042, parallelization). The lenses 2050B, 2050G, and 2050R are incident on the liquid crystal light valves 2060B, 2060G, and 2060R.

The liquid crystal light valves 2060B, 2060G, and 2060R have a TN type between a glass substrate having a pixel electrode and a switching element such as a thin film transistor element or a thin film diode for driving the same in a matrix form, and a glass substrate having a common electrode formed over its entire surface. An active matrix liquid crystal display device having a liquid crystal and a polarizing plate disposed on its outer surface.

In addition, the liquid crystal light valves 2060B, 2060G, and 2060R operate in a normally white mode, which is in a white / light (transmissive) state with no voltage applied, and in a black / dark (nontransparent) state with a voltage applied, or vice versa. Driven, contrast between the contrast is analog controlled in accordance with the applied control value. The liquid crystal light valve 2060B modulates the incident B light based on the display image data, and emits modulated light containing the optical image. The liquid crystal light valve 2060G modulates the incident G light on the basis of the display image data, and emits modulated light containing the optical image. The liquid crystal light valve 2060R light modulates the incident R light based on the display image data, and emits modulated light containing the optical image.

The cross dichroic prism 2070 has a structure in which four right angle prisms are bonded to each other, and therein, a dielectric multilayer film (B light reflective dichroic film 2071) reflecting B light and a dielectric material reflecting R light A multilayer film (R light reflection dichroic film 2072) is formed in a cross-sectional X shape. Then, the G light from the liquid crystal light valve 2060G is transmitted, the R light from the liquid crystal light valve 2060R and the B light from the liquid crystal light valve 2060B are folded to synthesize these three colors of light, thereby producing a color image. To form.

The optical low pass filter 2080 is disposed between the liquid crystal light valves 2060B, 2060G and 2060R as the first light modulation element and the liquid crystal light valve 2100 as the second modulation means, and the liquid crystal light valves 2060B and 2060G. , 2060R) to obscure the optical image formed. As the optical low pass filter 2080, various kinds of prisms, diffraction gratings, crystals, and the like can be used. In this example, prismatics are used. The low pass filter 2080 blurs the optical image formed by the liquid crystal light valves 2060B, 2060G, and 2060R, so that the pixel patterns of the liquid crystal light valves 2060B, 2060G, and 2060R and the liquid crystal light valve 2100 Image quality deterioration due to optical overlap is avoided. The configuration and function of the low pass filter 2080 will be described later in detail.

The relay lens 2090 transmits the optical image (light intensity distribution) from the liquid crystal light valves 2060B, 2060G, and 2060R synthesized in the cross dichroic prism 2070 on the display surface of the liquid crystal light valve 2100. will be.

The liquid crystal light valve 2100 has a configuration equivalent to the liquid crystal light valves 2060B, 2060G, and 2060R described above, modulates the luminance of the full-wavelength region of the incident light based on the display image data, and contains the final optical image. One modulated light is emitted to the projection lens 2110.

The projection lens 2110 displays a color image by projecting an optical image formed on the display surface of the liquid crystal light valve 2100 onto a screen (not shown).

Next, the overall light transmission flow of the projector PJ1 will be described. White light from the light source 2010 is spectroscopically reflected by the dichroic mirrors 2030 and 2035 into three primary colors of red R, green G and blue B, and also includes a lens including paralleling lenses 2050B, 2050G and 2050R. Through the lens and the mirror, they are incident on the liquid crystal light valves 2060B, 2060G, and 2060R. Each color light incident on the liquid crystal light valves 2060B, 2060G, and 2060R is color-modulated based on external data according to respective wavelength ranges, and is emitted as modulated light containing an optical image. Each modulated light from the liquid crystal light valves 2060B, 2060G, and 2060R is incident on the cross dichroic prism 2070, respectively, and thus synthesized into one light, the optical low pass filter 2080, the relay lens 2090 The incident light is incident on the liquid crystal light valve 2100. The composite light incident on the liquid crystal light valve 2100 is luminance-modulated based on external data according to the electric field, and is emitted to the projection lens 2110 as modulated light containing the final optical image. In the projection lens 2110, the final synthesized light from the liquid crystal light valve 2100 is projected on a screen (not shown) to display a desired image.

In the projector PJ1, the final display image is converted into a liquid crystal light valve as the second light modulation element by using modulated light in which an optical image (image) is formed from the liquid crystal light valves 2060B, 2060G, and 2060R as the first light modulation element. 2100, and modulates the light from the light source 2010 by a two-step image forming process through two light modulation elements arranged in series. As a result, the projector PJ1 can realize the expansion of the luminance dynamic range and the increase of the number of gradations.

Here, the liquid crystal light valves 2060B, 2060G, and 2060R and the liquid crystal light valve 2100 are all the same in terms of modulating the intensity of transmitted light and embedding an optical image according to the degree of modulation, but the latter liquid crystal light valve 2100. ) Modulates light in the full-wavelength region (white light), while the former liquid crystal light valves 2060B, 2060G, and 2060R use light in a particular wavelength region spectroscopy from the dichroic mirrors 2030 and 2035 as light separation means. They differ in that they modulate color light such as R, G, and B). Therefore, the light intensity modulation performed by the liquid crystal light valves 2060B, 2060G, and 2060R is conveniently referred to as color modulation and the light intensity modulation performed by the liquid crystal light valve 2100 as luminance modulation.

In addition, from the same point of view, in the following description, the liquid crystal light valves 2060B, 2060G, and 2060R may be referred to as color modulation light valves and the liquid crystal light valves 2100 as luminance modulating light valves. The contents of the control data input to the color modulating light valve and the luminance modulating light valve will be described later. In addition, in the present embodiment, the color modulation light valve has a higher resolution than the luminance modulation light valve, so that the color modulation light valve has a display resolution (representing the resolution perceived by the observer when the observer sees the display image of the projector PJ1). It is assumed that this is determined. Of course, the relationship of display resolution is not limited to this, The structure which a brightness modulation light valve determines display resolution is also possible.

35 is a diagram illustrating a configuration example of the relay lens 2090.

The relay lens 2090 forms an optical image of each of the color modulation liquid crystal light valves 2060B, 2060G, and 2060R on the pixel surface of the liquid crystal light valve 2100. As shown in FIG. 35, the aperture stop 2091 It is an equal magnification imaging lens which consists of the front lens group 2090a and the rear lens group 2090b arrange | positioned substantially symmetrically with respect to. It is also desirable to have both telecentric characteristics in view of the viewing angle characteristics of the liquid crystal. The front lens group 2090a and the rear lens group 2090b include a plurality of convex lenses and concave lenses. However, the shape, size, placement interval and number of lenses, telecentricity, magnification and other lens characteristics of the lens may be appropriately changed according to the required characteristics, and the present invention is not limited to the examples in FIG. 35. Since the relay lens 2090 is composed of several lenses, the aberration correction is good, and the luminance distribution formed in each of the color modulation liquid crystal light valves 2060B, 2060G, and 2060R can be accurately transmitted to the liquid crystal light valve 2100. .

36 (a), (b) and 37 (a), (b) are explanatory diagrams of telecentricity, and FIGS. 36 (a) and 37 (a) show a relay lens having bilateral telecentricity. 36 (b) and 37 (b) show a general relay lens.

As shown in Fig. 36 (a), a telecentric lens includes lenses 2402 and 2404 (main reference numeral 2401 denotes a front lens and reference numeral 2404 denotes a rear end) in which main rays represented by thick solid lines are parallel to the optical axis 2406. Lens), which has telecentricity on either the object side (front light valve 2401 side) and the image side (rear light valve 2405 side) is called a bilateral telecentric lens.

In the relay lenses 2402 and 2404 having bilateral telecentricity, the chief rays of light emitted from the front light valve 2401 (in this example, the liquid crystal light valve) are emitted almost vertically from either part of the front light valve. And incident to the rear stage light valve 2405 (in this example, the liquid crystal light valve). Therefore, when comparing the injection angle distribution of the light beam emitted from the position A far from the optical axis 2406 of the front light valve 2401 with the injection angle distribution of the light beam emitted from the position B close to the optical axis 2406, they are almost same.

On the other hand, as shown in FIG. 36 (b), in the general relay lens 2412, the chief ray represented by the thick solid line has different injection angles depending on the injection position of the front light valve 2411, and is incident on the rear light valve 2413. The angle also depends on the position of incidence. Therefore, when comparing the injection angle distribution of the light beam emitted from the position A far from the optical axis 2414 of the front light valve 2411 with the injection angle distribution of the light beam emitted from the position B close to the optical axis 2414, they are considerably different.

In general, liquid crystal light valves have visual dependence. That is, the gradation characteristics, the brightness characteristics, the spectral characteristics, and the like vary depending on the angle of the light beam emitted from the liquid crystal light valve. Therefore, in the general relay lens 2412 shown in FIG. 36 (b), the ejection angle component of the injection light beam is different for each region of the front light valve (liquid crystal light valve) 2411, and as a result, the rear light valve 2413 ( In the screen of the liquid crystal light valve), distribution (nonuniformity) may occur in brightness, color, and contrast of the display image, which may cause deterioration of the image display quality of the projector.

On the other hand, in the relay lenses 2402 and 2404 having both-side telecentricity shown in Fig. 36 (a), since the injection light velocity of any region of the front light valve 2401 (liquid crystal light valve) is almost equal to the injection angle distribution, The brightness, color, and contrast of the display image on the screen of the rear stage light valve 2405 (liquid crystal light valve) are substantially uniform, and the image display quality of the projector is good.

As shown in Fig. 37A, in the relay lenses 2402 and 2404 having both sides telecentricity, even if an error occurs in the arrangement position in the optical axis direction of the rear end light valve 2405 (Fig. 37). As shown in (a), PS1? PS2, since the chief rays of light are parallel to the optical axis, the image of the front-end light valve 2401 is somewhat residual after image, but the size is hardly changed (shown in Fig. 37 (a), AL1 ' AL2). That is, even if there is a slight arrangement error of the rear stage light valve 2405, the image display quality as the projector does not deteriorate so much, so that the manufacturing margin is large.

On the other hand, as shown in FIG. 37 (b), in the general relay lens 2412, when there is an arrangement error similar to the above in the rear stage light valve 2413 (shown in FIG. 37 (b), PS1-&gt; PS2), the chief ray Since it is not parallel to this optical axis, a change in size occurs with an afterimage on the front end light valve 2411 (shown in Fig. 37 (b), AL1 &lt; AL2), and as a result, the image display quality can be greatly reduced. There is this.

(Configuration and Function of Low Pass Filter)

Next, the structure and function of the optical low pass filter 2080 will be described with reference to FIGS. 38 to 42 (b).

38 shows the pixel plane of the liquid crystal light valve 2060B (color modulation light valve).

The pixel surface of the liquid crystal light valve 2060B has a plurality of unit pixels 2065 arranged in two dimensions periodically (matrix shape). Each pixel 2065 is formed in a substantially rectangular shape, and further includes an opening 2065a through which light passes, and a light shielding portion 2065b disposed around the opening 2065a. The light shielding portion 2065b is formed of a pixel wiring, a TFT element, or the like, in addition to the light shielding pattern film (black stripe film, black matrix film, etc.) in which the strip-shaped portions of a predetermined width are periodically arranged. In the liquid crystal light valve 2060B, the light passing through the opening 2065a of each pixel is modulated (transmittance modulated), thereby controlling the two-dimensional transmittance distribution in the pixel plane.

The same applies to the respective pixel surfaces of the liquid crystal light valves 2060G and 2060R (color modulation light valves) and the liquid crystal light valve 2100 (luminance modulation light valves).

39 (a) and 39 (b) are explanatory diagrams conceptually showing the causes of moire.

When the pixel surface of the color modulation light valve composed of repetition of the unit pixels is formed by a relay lens, as shown in Fig. 39 (a), the optical image has a grating-shaped dark portion 2416 and a substantially rectangular shape. The roots 2415 have a periodic structure in which they alternately repeat. When the optical image of the color modulating light valve is transferred onto the pixel surface of the luminance modulating light valve, as shown in Fig. 39 (b), positional shifts and posture shifts (inclination, etc.) between the two light valves. Is present (reference numeral 2417 denotes a luminance modulating liquid crystal light valve, and reference numeral 2418 denotes an optical image of a color modulating liquid crystal light valve), moire occurs and the image quality of the display image is significantly reduced.

40 (a) to 40 (c) are schematic diagrams of a schematic configuration and function of the optical low pass filter 2080, (a) is a plan view of the optical low pass filter 2080, and (b) is shown in (a). It is AA line cross section shown, (c) is a functional explanatory drawing of the optical lowpass filter 2080. As shown in FIG.

As shown in Fig. 40A, the optical low pass filter 2080 includes a group of prisms composed of an assembly of prism elements 2085 having a refractive surface. The periodic arrangement direction of the prism element 2085 is inclined at a predetermined angle (45 degrees in FIG. 40A) with respect to the periodic arrangement direction of the pixel 2065 of the liquid crystal light valve shown in FIG. 38.

As shown in FIG. 40 (b), one prism element 2085 includes a flat portion 2085a and a polygonal prism portion 2085b. As shown in Fig. 40 (c), of the luminous flux emitted from the color modulation light valves 2060B, 2060G, and 2060R, the luminous flux incident on the flat portion 2085a of the prism element 2085 is a low pass filter at an angle equal to the incident angle. It is injected from 2080. On the other hand, the light beam incident on the prism portion 2085b of the prism element 2085 is emitted from the low pass filter 2080 by changing the angle by refraction.

41 (a), (b) and 42 (a), (b) are diagrams for explaining in more detail the function of the low pass filter of FIGS. 40 (a) to 40 (c). FIG. 41A shows an optical system as a comparative example without a low pass filter, and FIG. 42A shows an image of a unit pixel formed in the optical system of FIG. 41A. 41 (b) shows an optical system having a low pass filter, and FIG. 42 (b) shows an image of a unit pixel formed in the optical system of FIG. 41 (b).

As shown in Fig. 41A, in the optical system without a low pass filter, the light beam emitted from one point of the color modulation light valve 2421 is one point of the brightness modulation light valve 2424 by the relay lens 2423. It is formed. On the other hand, as shown in Fig. 41B, in the optical system having the low pass filter 2422, the light beams emitted from one point of the color modulation light valve 2421 are formed at a plurality of points having different positions. That is, a part of the light beam passing through the pixel opening of the color modulation light valve 2421 is bent by the low pass filter 2422, and the optical image (list) of the pixel opening is imaged in a plurality of locations having different positions (recovery). function).

As shown in Fig. 42 (a), in the optical system without a low pass filter, the optical image of the unit pixel of the color modulation light valve is formed by the dark portion 2425 of the spherical annular shape formed by the pixel light blocking portion. It is assumed to have a spine 2426 formed by the pixel openings. In contrast, as shown in Fig. 42 (b), in the optical system having the low pass filter 2080, by the above-described image function of the low pass filter 2080 (prism element 2085), the color modulation light valve In the optical image of the unit pixel, the dark portion formed by the light shielding unit of the unit pixel becomes inconspicuous.

That is, as shown in Fig. 42 (b), in the low pass filter, part of the light passing through the pixel opening of the color modulation light valve is ejected by changing the angle by refraction. Then, the light overlaps the dark portion formed in the light shielding portion of the color modulation light valve.

Specifically, as shown in FIG. 42 (b), the left-side prism portion (refractive surface) of the prism element 2085 of the low pass filter 2080 is formed by the pixel opening of the color modulation light valve. It shifts to the upper left and the luminous flux overlaps with the dark part formed by the pixel light shielding part of the color modulation light valve (image shift. Fig. 42 (b) (b-1)). Similarly, the left and right prism portions (refraction surfaces) of the prism element 2085 are shifted left and right (b-2), and the right and lower prism portions (refraction surfaces) of the prism elements 2085 are shifted and the left and right sides are shifted to the lower right. (b-3), by the prism part (refraction surface) of the upper right of the prism element 2085, a roll shifts to an upper right (b-4). Then, the light is irradiated to the entire dark portion by the above-described recall function, so that the dark portion of the optical image of the unit pixel of the color modulation light valve becomes inconspicuous (b-5).

As described above, in the present example, when the optical image of the color modulation light valve is transferred onto the pixel plane of the luminance modulation light valve, the dark part, which is the optical image of the pixel light blocking part, is applied to the eye by the image return function of the low pass filter 2080. It becomes inconspicuous. That is, the optical image of the color modulating light valve with high uniformity of brightness is imaged on the luminance modulating light valve. Therefore, the pixel deterioration phenomenon by the optical overlap of light shielding patterns, such as moire, is surely suppressed.

43 is a sectional view of the luminance modulating light valve 2100 (the liquid crystal light valve 2100 shown in FIG. 34).

The luminance modulating light valve 2100 includes two transparent substrates 2101 and 2102 disposed to face each other, a light shielding pattern film 2103 (black stripe film, a black matrix film, etc.) having a periodic structure, a liquid crystal layer 2104, and a TFT / wiring 2105, the pixel electrode 2106, the micro lens array 2107, and the like.

The microlens array 2107 is disposed on the light incident side of the luminance modulating light valve 2100 and includes a lens group corresponding one to one to each pixel 2108 of the light valve 2100. Each lens 2109 of the micro lens array 2107 is formed to concentrate the light from the low pass filter 2080 to the opening of each pixel 2108 of the luminance modulating light valve 2100. That is, in the luminance modulating light valve 2100, one condenser lens 2109 is disposed on the light incident side of each pixel 2108.

As described above, the light transmitted through the pixel openings of the color modulation light valves (liquid crystal light valves 2060B, 2060G, and 2060R shown in FIG. 34) is pixels by the low pass filter 2080, as shown in FIG. 42. A wider range is reached than the range corresponding to the opening. As a result, the amount of light reaching the light shielding pattern film 2103 of the luminance modulating light valve 2100 increases, causing a problem that the luminance of the display image is lowered. In this example, the microlens array 2107 is disposed on the light incidence side of the luminance modulating light valve 2100, so that the light from the low pass filter 2080 is applied to each pixel 2108 of the second light modulation element. Focused on the opening, the brightness of the display image is improved.

That is, the incident light beam to the luminance modulating light valve 2100 is condensed by each lens 2109 of the microlens array 2107 and passes through the opening of the pixel 2108 of the luminance modulating light valve 2100. Therefore, a part of the light refracted by the low pass filter 2080 is avoided by being blocked by the light shielding pattern film 2103 of the luminance modulating light valve 2100. Thus, in this example, while the structure using the optical low pass filter 2080 is used, the fall of luminance is suppressed.

The arrangement position of the optical low pass filter 2080 shown in FIG. 34 is not limited between the cross dichroic prism 2070 and the relay lens 2090, but the relay lens 2090 and the luminance modulating light valve (liquid crystal light valve). (2100)). It may also be arranged in the relay lens 2090. It is also possible to arrange between the color modulation light valves (liquid crystal light valves 2060B, 2060G, and 2060R) and the cross dichroic prism 2070. In this case, a low pass filter is required for each of the color modulation light valves of R, G, and B. However, since the low pass filter optimized for each wavelength characteristic can be used, it is possible to reduce the moire more effectively. have.

In addition, the present invention is not limited to the optical system in which the color modulation light valve is placed at the front end and the luminance modulation light valve is arranged at the rear end from the light source 2010 side, and the color modulation light valve is placed at the front end. This invention can be applied also to the optical system arrange | positioned at a rear end. In this case, a low pass filter and a relay lens are disposed between the luminance modulating light valve and the color modulating light valve. Further, a microlens array is arranged on the light incident surface of the color modulating light valve.

In this example, the liquid crystal light valves 2060B, 2060G, and the like are arranged on one side where the microlens array 2107 is disposed adjacent to each pixel of the brightness modulation light valve 2100 (second light modulation element, rear light valve). 2060R) (the first light modulation element, the front light valve) is not arranged in the micro lens array in the adjacent position of each pixel. When a microlens is included in a 1st light modulation element (light valve arrange | positioned at the front end), when the 1st optical modulation element (light valve arrange | positioned) contains a microlens, the emission angle of the light beam which will radiate | emit the 1st light modulation element will become large wide, This is because the F number of the transmission optical system (relay lens 2090) must be made small in order to efficiently transmit the light valve to be disposed, resulting in an increase in the cost of the device and an increase in size and weight. Therefore, it is preferable that a microlens is not included in a 1st light modulation element.

The form of the low pass filter is not limited to those shown in Figs. 40A to 40C and may be other forms. In addition, the low pass filter is not limited to a prism type, and a diffraction type low pass filter can also be used.

(Other example of low pass filter)

44 to 55 show another example of the low pass filter.

44 to 49 show various modifications of the prism element shape.

For example, FIG. 44 shows a prism group 2161 provided with a trapezoidal prism element having a refractive surface 2161a and a flat portion 2161b at predetermined intervals.

45 shows a prism group 2162 having a refracting surface 2162a and a flat portion 2162b and provided with a trapezoidal prism element without gaps.

FIG. 46 shows a prism group 2163 having a refracting surface 2163a and a flat portion 2163b and provided with triangular prism elements at predetermined intervals.

FIG. 47 shows a group of blazed prisms 2164 composed of only the refractive surface 2164a.

FIG. 48 shows a group of prisms 2165 in a state where the height of the flat portion and the prism pitch are random and there is almost no periodicity for generating diffraction by the prism edge.

49 shows a group of prisms 2166 whose flat portions have a common height but whose prism pitch is random and can suppress the effect of diffraction by suppressing periodicity which is a diffraction generation condition.

Thus, various modifications can be taken using the direction, the inclination angle, and the area of the refractive surface as parameters.

50 is a schematic configuration in which a part of another form of the prism group is enlarged. The prism group 2210 is composed of a square prism-shaped first prism element 2211 and a square prism-shaped second prism element 2212. The first prism element 2211 is formed such that one side thereof is approximately 45 ° to the center line CL. The second prism element 2212 is formed such that one side thereof is substantially parallel to the center line CL. In addition, a flat portion 2215 is provided around the first prism element 2211 and the second prism element 2212.

As shown in FIG. 51, the opening image (directly-transmitted image) 2220P is formed by the light which permeate | transmitted the flat part 2215. As shown in FIG. The opening surface 2223P is formed by the refracting surface 2213 of the first prism element 2211 in the 45 ° direction with respect to the centerline image CLP. Opening image 2214P is formed in a direction parallel to centerline image CLP by refracting surface 2214 of second prism element 2212.

Then, the direction of the refracting surface and the inclination angle are set so that these projected images fill the dark portion due to the light shielding pattern without gaps.

As a result, the intensity unevenness of the projected image can be reduced.

In addition, the shape of the prism group that causes the same refractive effect as that of the prism group 2210 can take various modifications. For example, the prism group 2230 having the refractive surface 2231 and the flat portion 232 as shown in FIG. 52 may be used. In this manner, the prism refraction surface and the flat surface can be formed in an arbitrary shape at a desired area ratio.

Fig. 53 is another example of the low-pass filter, and illustrates a major portion perspective configuration of the prism group 2240.

The prism group 2240 is composed of two sets of prism elements 2241a and 2241b. The prism element 2241a has a substantially trapezoidal cross-sectional shape in the y-axis direction that is the first direction. The prism element 2241a has a longitudinal direction in the x-axis direction, which is a second direction that is substantially orthogonal to the y-axis direction, which is the first direction.

In the trapezoidal shape of the cross-sectional shape in the y-axis direction of the prism element 2241a, two inclined surfaces Y1 and Y2 function as a refractive surface. Moreover, of the cross-sectional shape in the y-axis direction of the prism element 2241a, the upper surface Y0 functions as a flat part. For this reason, the light incident on the inclined surface Y1 or the inclined surface Y2 is refracted in the direction corresponding to the angle of the inclined surface. The refracted transmission image is formed by the refracted light. In addition, light incident on the upper surface Y0 is transmitted as it is. The transmitted image is formed by the light transmitted as it is.

Prism element 2241b has the same structure as prism element 2241a. In the cross-sectional shape of the prism element 2241b in the x-axis direction, two inclined surfaces X1 and X2 function as refractive surfaces. In addition, in the cross-sectional shape of the prism element 2241b in the x-axis direction, the upper surface X0 functions as a flat portion. The two sets of prism elements 2241a and 2241b are provided so that their respective longitudinal directions are substantially orthogonal to each other.

The prism group 2240 of this example is fixed to the plane side of the prism element 2241a and the plane side of the prism element 2241b. However, it is not limited to this, Any structure of the following (1)-(3) may be sufficient.

(1) A structure in which the surfaces on which the inclined surfaces Y1, Y2 and the like of the prism element 2241a are formed and the surfaces on which the inclined surfaces X1, X2 and the like of the prism element 2241b are formed are attached to face each other.

(2) A configuration in which the inclined surfaces Y1, Y2, and the like of the prism element 2241a are formed, and the surface of the prism element 2241b is fixed to face each other.

(3) A configuration in which the planar side of the prism element 2241a and the surface on which the inclined surfaces X1, X2, etc. of the prism element 2241b are formed are fixed to face each other.

In addition, although the structure which a prism surface contacts is demonstrated in FIG. 53, the structure which both surfaces contact air may be sufficient.

54 shows the branching of incident light by the prism group 2240.

In FIG. 54, incident light XY advances from left to right. In addition, in some of FIG. 54, the light ray is specified using the code | symbol of inclined surface Y0, Y1, Y2 for convenience of description. Incident light XY branches by the prism element 2241a shown by the dotted line into the three light rays Y1 and Y2 refracted by an inclined surface, and the light ray Y0 which permeate | transmits an upper surface as it is. The three light beams Y0, Y1, and Y2 branched further are further branched into three light beams by the prism element 2241b. As a result, incident light XY branches to nine light rays Y1X1, Y1X0, Y1X2, Y0X1, Y0X0, Y0X2, Y2X1, Y2X0, Y2X2.

Next, the position in the projection surface of the branched nine light beams is demonstrated using FIG.

The area | region of the direct transmission image by the ray Y0X0 is shown enclosed by the bold border. The projected image of the pixel portion by the refracted light may be formed in a direction orthogonal to the longitudinal directions of the prism elements 2241a and 2241b, respectively. The prism group 2240 is comprised so that the longitudinal directions of two sets of prism elements 2241a and 2241b may orthogonally cross. Thereby, regions of the refractive transmission image by the eight rays Y1X1, Y1X0, Y1X2, Y0X1, Y0X2, Y2X1, Y2X0, Y2X2 are formed in the periphery of the area of the direct transmission image by the ray Y0X0. In FIG. 55, the code | symbol of a light ray is provided to each area | region. In addition, the direct-transmitted image by the light ray Y0X0 is formed adjacent to each other periodically corresponding to the position of the some pixel opening part in the 1st light modulation element (liquid crystal light valve 2060B, 2060G, 2060R shown in FIG. 34). The prism group 2240 forms the refractive transmission image in the area | region between direct transmission images by the light ray Y0X0 by the prism elements 2241a and 2241b. Accordingly, the periodicity of the projection light can be reduced.

In addition, the prism group 2240 passes through the total of the light intensities via the upper surface Y0 of the prism element 2241a, which is a flat surface, and the upper surface X0 of the prism element 2241b, via PW0 and the inclined surfaces Y1, Y2, X1, and X2 that are refractive surfaces. When the sum of one light intensity is each called PW1,

PW0≥PW1

Are satisfied. In addition, PW0 and PW1 are the light intensity in a 2nd light modulation element (liquid crystal light valve 2100).

The sum of the light intensities of the direct-transmitted image by the ray Y0X0 corresponds to the areas of the upper surfaces Y0, X0 which are flat portions. In addition, the sum total of the light intensities of the refractive transmission images by the rays Y1X1, Y1X0, Y1X2, Y0X1, Y0X2, Y2X1, Y2X0, Y2X2 corresponds to the areas of the inclined surfaces Y1, Y2, X1, X2 which are refractive surfaces. Here, when the sum PW1 of the light intensities of the refractive transmission images by the rays Y1X1, Y1X0, Y1X2, Y0X1, Y0X2, Y2X1, Y2X0, Y2X2 becomes larger than the sum PW0 of the light intensities of the directly transmitted image, the observer is, for example, ghost-like Double images may be recognized.

In this example, it is configured to satisfy PW0≥PW1. Accordingly, the occurrence of moire can be reduced.

Also, preferably, PW0> PW1 is satisfied. More preferably, it is desirable to satisfy PW0> 0.9 × PW1. As a result, by maintaining the original pixel information while making the light intensity distribution by the pixel arrangement uniform, the moire can be reduced and a high definition projection image can be obtained.

Here, an example of the manufacturing method of the prism group which comprises a low pass filter is demonstrated. The prism group is integrally formed on the exit surface of the transparent plate. The transparent plate is a transparent parallel flat glass. Prismatic groups are formed on one side of the parallel plate glass by photolithography. Specifically, the photoresist layer is patterned on the parallel flat glass so as to have a desired prism shape, for example, a rectangular weight shape, using a gray scale method to form a mask. Then, the group of prisms formed by the RIE method using fluorine-based gas such as CHF _3. Prism group can be formed by the wet etching method using a hydrofluoric acid.

Another example of the prism group manufacturing method will be described.

An optical epoxy resin is apply | coated to one surface of parallel plate glass. Next, as a desired prism shape, a mold having a pattern in which unevenness is reversed is prepared. Then, the mold is transferred by pressing the mold with an epoxy resin. Finally, an ultraviolet-ray is irradiated to an optical epoxy resin and hardened | cured, and a prism group is formed.

In the case of metamorphosis, another method may be employed. The parallel plate glass is heated and softened to the extent necessary for mold transfer. And the die mentioned above is pressed and mold-transferred to one surface of the softened parallel plate glass. Also by this, a prism group can be formed in parallel flat glass.

In addition, a prism group is not limited to the case formed in a transparent plate. For example, the prism group of a desired prism shape is manufactured as a separate pattern sheet by the hot press method. Then, the pattern sheet is cut to the required size. Next, the cut pattern sheet is bonded to the injection side of the parallel plate glass using an optically clear adhesive. Also by this, a prism group can be formed in parallel flat glass.

Preferably, it is preferable to prevent dust or the like from adhering to the surface of the prism group. For this reason, the coating layer which consists of transparent resin of low refractive index, etc. is formed with respect to the injection side of a prism group. For example, the group of prisms is formed of an optical epoxy high refractive index resin having a refractive index of n = 1.56. The coating layer is formed of, for example, an optical epoxy low refractive index resin having a refractive index of n = 1.38. Moreover, the refractive index of the member which comprises a prism group and the refractive index of a coating layer can also be made to correspond substantially. Thereby, the position shift on the predetermined surface of the refracted light resulting from the deviation of manufacture error of a refractive surface, etc. can be reduced.

Here, the angle refracted at the refracting surface depends on the wavelength of light. For this reason, when manufacturing a prism group, it is preferable to consider the wavelength of the refracted light. For example, the ultrahigh pressure mercury lamp, which is the light source, has an emission spectrum distribution. The light having a peak wavelength in the bright spectrum of about 440 nm is used as the B light and the light having about 550 nm is used as the G light. Moreover, the light of about 650 nm vicinity which is the center wavelength of a light quantity integral value is used as R light. When the light of these wavelengths is refracted at the refracting surface, the inclination angle θ of the refracting surface is controlled so as to form a predetermined projection image on the predetermined surface (luminance modulating light valve). Thereby, the high quality image with few predetermined surfaces (luminance modulation light valve) and color shift | offset can be obtained.

(Specific example of liquid crystal light valve modulation)

Next, specific examples of the color modulation light valve and luminance modulation light valve modulation based on the display image data will be described in detail.

In the projector PJ1 (see FIG. 34), a color modulation light valve (liquid crystal light valves 2060B, 2060G, 2060R shown in FIG. 34) is used as a color modulation signal generated from an image signal, and a brightness modulation light valve (Fig. 34). By driving the liquid crystal light valve 2100 shown in Fig. 2, the enlargement of the luminance dynamic region and the increase in the number of gray scales are realized.The modulation control of the liquid crystal light valve is executed by the display control device 2200 described next.

56 is a block diagram illustrating a hardware configuration of the display control device 2200. As shown in Fig. 56, the display control device 2200 includes a CPU 2170 that controls arithmetic and the entire system based on a control program, and a ROM which stores, in advance, a control program of the CPU 2170 in a predetermined area. 2217, RAM 2174 for storing data read from the ROM 2172 or the like, and calculation results required in the calculation process of the CPU 2170, and I / F for mediating input / output of data to an external device ( 2178, and they are connected to each other and also to receive data by bus 2179, which is a signal line for transmitting data.

The I / F 2178 includes a luminance modulating light valve (liquid crystal light valve 2100 shown in FIG. 34) and a color modulating light valve (liquid crystal light valves 2060B, 2060G, and 2060R shown in FIG. 34) as external devices. A light valve driving device 2180 to be driven, a storage device 2182 for storing data, a table, and the like as a file are connected, and a signal line 2199 for connecting to an external network is connected.

The memory device 2182 stores HDR display data for driving the luminance modulating light valve and the color modulating light valve.

The HDR display data is image data capable of realizing a high luminance dynamic region that cannot be realized in a conventional image format such as sRGB, and stores pixel values representing the luminance levels of pixels for all pixels of the image. In the present embodiment, as the HDR display data, a format in which a pixel value indicating a luminance level for each of the three RGB primary colors is stored as a floating point value for one pixel is used. For example, a value of (1.2, 5.4, 2.3) is stored as a pixel value of one pixel.

Here, the luminance level of the pixel p in the HDR display data is Rp, the transmittance of the pixel corresponding to the pixel p of the second light modulation element is T1, and the transmittance of the pixel corresponding to the pixel p of the first light modulation element is T2. The following formulas (2-1) and (2-2) hold.

However, in the formulas (2-1) and (2-2), Rs is the brightness of the light source, G is the gain, and both are integers. Tp is the light modulation rate.

In addition, the detail of the generation method of HDR display data is published in "PEDebevec, J.Malik," Recovering High Dynamic Range Radiance Maps from Photographs ", Proceedings of ACM SIGGRAPH97, pp. 367-378 (1997), for example. It is.

The memory device 2182 also stores a control value registration table 2400 in which the control value of the luminance modulated light valve is registered.

57 is a diagram showing the data structure of the control value registration table 2400. FIG.

In the control value registration table 2400, as shown in FIG. 57, one record is registered for each control value of the luminance modulating light valve. Each record includes a field in which the control value of the luminance modulated light valve is registered, and a field in which the transmittance of the luminance modulated light valve is registered.

In the example of FIG. 57, "0" is registered as a control value and "0.003" is registered as a transmittance | permeability, respectively, in the record of a 1st step | paragraph. This indicates that when the control value "0" is output to the luminance modulating light valve, the transmittance of the luminance modulating light valve is 0.3%.

Although FIG. 57 shows the case where the gradation number of the luminance modulating light valve is 4 bits (0 to 15 values) as an example, a record corresponding to the gradation number of the luminance modulating light valve is registered. For example, when the tone number is 8 bits, 256 records are registered.

The storage device 2182 also stores a control value registration table in which control values of the color modulation light valves are registered for each color modulation light valve.

FIG. 58 is a diagram showing a data structure of a control value registration table 2420R in which the control value of the liquid crystal light valve 2060R is registered.

As illustrated in FIG. 58, one record is registered in the control value registration table 2420R for each control value of the liquid crystal light valve 2060R. Each record includes a field in which the control value of the liquid crystal light valve 2060R is registered, and a field in which the transmittance of the liquid crystal light valve 2060R is registered.

In the example of FIG. 58, "0" is used as a control value and "0.004" is registered as a transmittance | permeability, respectively, in the record of a 1st step | paragraph. This indicates that when the control value "0" is output to the liquid crystal light valve 2060R, the transmittance of the liquid crystal light valve 2060R becomes 0.4%. In addition, although FIG. 58 shows the case where the gradation number of the color modulation light valve is 4 bits (0 to 15 values) as an example, a record corresponding to the gradation number of the color modulation light valve is actually registered. For example, when the tone number is 8 bits, 256 records are registered.

The data structure of the control value registration table corresponding to the liquid crystal light valves 2060B and 2060G is not particularly shown, but has the same data structure as the control value registration table 2420R. However, a different transmittance is registered for the same control value than the control value registration table 2420R.

Next, the configuration of the CPU 2170 and the processing executed by the CPU 2170 will be described. The CPU 2170 is made up of a micro processing unit (MPU) or the like, activates a predetermined program stored in a predetermined area of the ROM 2172 and executes the display control process shown in the flowchart of FIG. 59 according to the program. It is.

59 is a flowchart showing display control processing.

The display control process is a process of determining the control values of the luminance modulating light valve and the color modulating light valve based on the HDR display data, and driving the luminance modulating light valve and the color modulating light valve based on the determined control value, and including the CPU ( If it is executed in 2170, as shown in FIG. 59, the process first proceeds to step S100.

In step S100, the HDR display data is read from the storage device 2182. Subsequently, the process proceeds to step S102, and the read HDR display data is analyzed to calculate a histogram of pixel values, a maximum value, minimum value, average value, and the like of the luminance level. This analysis result is for use in automatic image correction such as lightening a dark scene, darkening an overly bright scene, or emphasizing mid-contrast, or for tone mapping.

Subsequently, the process proceeds to step S104 and based on the analysis result of step S102, tone mapping of the luminance level of the HDR display data to the luminance dynamic region of the projector PJ1 is performed.

60 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. In addition, the minimum value of the luminance dynamic range of the projector PJ1 is Dmin, and the maximum value is Dmax. In the example of FIG. 60, since Smin is smaller than Dmin and Smax is larger than Dmax, HDR display data cannot be displayed properly as it is. Therefore, it is normalized so that the histogram of Smin-Smax is contained in the area | region of Dmin- (d) max.

In addition, the detail of tone mapping is described, for example in "F.Drago, K. Myszkowski, T.Annen, N.Chiba," Adaptive Logarithmic Mapping For Displaying High Contrast Scenes ", Eurographics 2003, (2003).

Subsequently, the flow advances to step S106 to resize (enlarge or reduce) the HDR image in accordance with the resolution of the color modulation light valve. At this time, the size of the HDR image is readjusted while maintaining the aspect ratio of the HDR image. Examples of the resizing method include an average value method, a median value method, and a nearest neighbor method.

Subsequently, the process proceeds to step S108 and based on the luminance level Rp of the pixel of the resized image and the luminance Rs of the light source 2010, the light modulation rate Tp for each pixel of the resized image according to the above formula (2-1). To calculate.

Subsequently, the process proceeds to step S110, 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 temporarily determined.

Subsequently, the process proceeds to step S112, and based on the calculated light modulation rate Tp, the tentatively determined transmittance T2 and the gain G, according to the above formula (2-2), the luminance modulation light valve is provided in units of pixels of the color modulation light valve. The transmittance T1 'is calculated. Here, since the color modulation light valve is composed of three liquid crystal light valves 2060B, 2060G, and 2060R, the transmittance T1 'is calculated for each of the three RGB primary colors for the same pixel. On the other hand, since the luminance modulating light valve is composed of one liquid crystal light valve 2100, their average value and the like are calculated as T1 'of the pixel.

Subsequently, the process proceeds to step S114, and for each pixel of the luminance modulating light valve, the weighted average value of the transmittance T1 'calculated for the pixel of the color modulating light valve overlapping on the optical path is calculated as the transmittance T1 of the pixel. The weighting is performed by the area ratio of the overlapping pixels.

Subsequently, the process proceeds to step S116, for each pixel of the luminance modulating light valve, the control value corresponding to the transmittance T1 calculated for the pixel is read out from the control value registration table 2400, and the read control value is controlled for the pixel. Determined as a value. In reading the control value, the transmittance closest to the calculated transmittance T1 is searched in the control value registration table 2400, and the control value corresponding to the transmittance detected by the search is read. This search is implemented by, for example, using a two-minute search method to realize a fast search.

Subsequently, the process proceeds to step S118 where the weighted average value of the transmittance T1 determined for each pixel of the color modulation light valve and the pixel of the luminance modulation light valve overlapping on the optical path is calculated, and the calculated average value is calculated in step S108. Based on the light modulation rate Tp and the gain G, the transmittance T2 of the pixel is calculated by the above formula (2-2). The weighting is performed by the area ratio of the overlapping pixels.

Subsequently, the process proceeds to step S120, for each pixel of the color modulation light valve, the control value corresponding to the transmittance T2 calculated for the pixel is read out from the control value registration table, and the read control value is determined as the control value of the pixel. do. In reading the control value, the transmittance closest to the calculated transmittance T2 is searched in the control value registration table, and the control value corresponding to the transmittance extracted by the search is read out. This search is implemented by, for example, using a two-minute search method to realize a fast search.

Subsequently, the flow advances to step S122, the control values determined in steps S116 and S120 are output to the light valve drive device 2180, the color modulation light valve and the brightness modulating light valve are respectively driven to project the display image, and a series of processes are performed. To exit and return to the original processing.

Next, a process of generating image data written in the color modulation light valves (liquid crystal light valves 2060B, 2060G, 2060R) and the luminance modulation light valves (liquid crystal light valve 2100) is shown in Figs. 61 to 64 (c). Explain on the basis of

Hereinafter, the color modulation light valves (liquid crystal light valves 2060B, 2060G, and 2060R) all have a resolution of 18 pixels in width x 12 pixels in height and a 4-bit gradation number, and the luminance modulation light valve (liquid crystal light valve 2100). ) Will be described taking the case of having a resolution of 15 pixels in width x 10 pixels in height and a 4-bit gray scale number. In addition, the drawings of a color modulation light valve and a brightness modulation light valve are both seen from the light source 2010 side.

In the display control device 2200, the HDR display data is read through the steps S100 to S104, the read HDR display data is analyzed, and based on the analysis result, the luminance level of the HDR display data is the luminance dynamic of the projector PJ1. Tone mapped to the area. Subsequently, the size of the HDR image is readjusted according to the resolution of the color modulation light valve via step S106.

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

Fig. 61 is a diagram illustrating a case where the transmittance T2 of the color modulation light valve is temporarily determined. Then, through step S110, the transmittance T2 of each pixel of the color modulation light valve is preliminarily determined. When the pixels in the upper left four compartments of the color modulation light valve are P21 (left upper), P22 (right upper), P23 (lower left), and P24 (lower), the transmittance T2 of the pixels P21 to P24 is shown in Fig. 61. The initial value T20 is applied.

Fig. 62 is a diagram illustrating a case where the transmittance T1 'of the luminance modulating light valve is calculated in the pixel unit of the color modulation light valve.

Subsequently, the transmittance T1 'of the luminance modulating light valve is calculated in units of pixels of the color modulation light valve through step S112. In the case of paying attention to the pixels P21 to P24, the transmittances T11 to T14 of the luminance modulating light valve corresponding thereto correspond to the light modulation rates of the pixels P21 to P24 Tp1 to Tp4 and the gain G as shown in FIG. 62. If it is, it can calculate by following formula (2-3)-(2-6).

It actually calculates using numbers. In the case of Tp1 = 0.00012, Tp2 = 0.05, Tp3 = 0.02, Tp4 = 0.01, and T20 = 0.1, T11 = 0.0012, T12 = 0.5, T13 = 0.2, by the following formulas (2-3) to (2-6): T14 = 0.1.

63 (a) to 63 (c) are diagrams illustrating a case where the transmittance T1 of each pixel of the luminance modulating light valve is determined.

Subsequently, through step S114, the transmittance T1 of each pixel of the luminance modulating light valve is determined. Since the luminance modulation light valve and the color modulation panel are inverted and formed by the relay lens 2090, the pixels in the upper left four sections of the color modulation panel are formed in the lower right part of the luminance modulation light valve. When the pixels in the lower right four divisions of the luminance modulation light valve are P11 (lower right), P12 (lower left), P13 (right upper right), and P14 (left upper), the pixel P11 is color-modulated as shown in Fig. 63 (a). Since the resolutions of the light valve and the luminance modulating light valve are different, they overlap 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 rectangular area of 6 × 6 based on the least common multiple of the number of pixels of the color modulation light valve. . The area ratio where the pixels P11 and the pixels P21 to P24 overlap is 25: 5: 5: 1 as shown in Fig. 63 (b). Therefore, the transmittance T15 of the pixel P11 can be calculated by the following formula (2-7) as shown in Fig. 63 (c).

It actually calculates using numbers. When T11 = 0.0012, T12 = 0.5, T13 = 0.2, and T14 = 0.002, T15 = 0.1008 is obtained by the following equation (2-7).

Transmittances T16 to T18 of the pixels P12 to P14 can also be obtained by calculating a weighted average value based on the area ratio, similarly to the pixel P11.

Subsequently, through step S116, for each pixel of the luminance modulating light valve, the control value corresponding to the transmittance T1 calculated for that pixel is read from the control value registration table 2400, and the read control value is the control value of the pixel. Is determined as. For example, since T15 = 0.1008, referring to the control value registration table 2400, as shown in FIG. 57, 0.09 is the closest value. Therefore, "8" is read from the control value registration table 2400 as the control value of the pixel P11.

64 (a) to (c) are diagrams showing a case where the transmittance T2 of each pixel of the color modulation light valve is determined.

Subsequently, through step S118, the transmittance T2 of each pixel of the color modulation light valve is determined. As shown in Fig. 64A, the pixel P24 overlaps the pixels P11 to P14 on the optical path because the resolutions of the color modulation light valve and the brightness modulation light valve are different. Since the resolution of the color modulation light valve is 18 × 12 and the resolution of the brightness modulation light valve is 15 × 10, the pixel P24 can be divided into 5 × 5 rectangular areas based on the least common multiple of the number of pixels of the brightness modulation light valve. . The area ratio where the pixels P24 and the pixels P11 to P14 overlap is 1: 4: 4: 16 as shown in Fig. 64B. Therefore, when focusing on the pixel P24, the transmittance | permeability T19 of the brightness modulation light valve corresponding to this can be computed by following formula (2-8). And if the gain G is set to "1", the transmittance | permeability T24 of the pixel P24 can be computed by following formula (2-9), as shown to FIG. 64 (c).

It actually calculates using numbers. When T15 = 0.09, T16 = 0.33, T17 = 0.15, T18 = 0.06, and Tp4 = 0.01, T19 = 0.1188 and T24 = 0.0842 by the following formulas (2-8) and (2-9).

Transmittances T21 to T23 of the pixels P21 to P23 can also be obtained by calculating a weighted average value based on the area ratio, similarly to the pixel P24.

Subsequently, through step S120, for each pixel of the color modulation light valve, the control value corresponding to the transmittance T2 calculated for that pixel is read from the control value registration table, and the read control value is determined as the control value of the pixel. do. For example, when T24 = 0.0842 with respect to the pixel P24 of the liquid crystal light valve 2060R, referring to the control value registration table 2420R, 0.07 becomes the closest value as shown in FIG. 58 above. Therefore, "7" is read from the control value registration table 2420R as the control value of the pixel P24.

Then, the determined control value is output to the light valve drive device 2180 via step S122. Thereby, the luminance modulating light valve (liquid crystal light valve 2100) and the color modulating light valve (liquid crystal light valves 2060B, 2060G, and 2060R) are respectively driven to project the display image onto the screen.

By the modulation control of the liquid crystal light valve described above, it is possible to realize the expansion of the luminance dynamic region and the increase of the number of gradations by a two-step image forming process.

(Modification of Example)

In the first embodiment, the resolution of the liquid crystal light valves 2060B, 2060G, and 2060R (color modulation light valves) that are the first light modulation elements is the liquid crystal light valve 2100 (luminescence modulation light) that is the second light modulation element. Although the case where it is higher than the valve is demonstrated as an example, the resolution of two light modulation elements (a color modulation light valve and a brightness modulation light valve) may be the same, or may differ. However, when the resolutions of the two are different, as described in the first embodiment, the resolution of the display image data must be converted.

For example, if the luminance modulating light valve has a display resolution higher than the display resolution of the color modulating light valve, there is no need to set a high MTF (Modulation Transfer Function) in the light transfer from the color modulation light valve to the luminance modulating light valve. As a result, it is not necessary to increase the transfer performance of the relay optical system therebetween, and the relay optical system can be configured relatively inexpensively.

On the other hand, if the color modulating light valve has a display resolution higher than the display resolution of the luminance modulating light valve, normally, the display image data is prepared in accordance with the display resolution of the color modulating light valve, so that the conversion processing of the resolution is performed by the luminance modulating light valve. Since it is sufficient to execute once in accordance with the display resolution, the conversion processing of the display image data becomes easy.

(Other modifications)

In each of the embodiments of the second aspect of the present invention, the luminance of the light is modulated in two stages by using the luminance modulating light valve and the color modulating light valve, but not limited to this, but two sets of the luminance modulating light valve are provided. It can also be configured to modulate the brightness of the light in two stages.

Further, in the embodiment of the second aspect of the present invention, the liquid crystal light valves 2060B, 2060G, 2060R, and 2100 are configured by using an active matrix liquid crystal display element, but the present invention is not limited thereto. 2060B, 2060G, 2060R, and 2100 may be configured using a passive matrix liquid crystal display element and a segmented liquid crystal display element. The active matrix liquid crystal display has the advantage of being capable of precise contrast display, and the passive matrix liquid crystal display element and the segment type liquid crystal display element have the advantage of being inexpensively manufactured.

In addition, in the embodiment of the second aspect of the present invention, a relay lens mainly composed of a transmission type optical element is used as a relay optical system for forming an optical image of a liquid crystal light valve in a front stage into a liquid crystal light valve in a rear stage. However, the present invention is not limited thereto, and a reflective relay optical system mainly composed of a reflective optical element (mirror) may be used.

In addition, although the projector PJ1 provided and comprised the transmissive light modulation element in each said embodiment, it is not limited to this, The luminance modulation light valve or the color modulation light valve is a reflection type liquid crystal light valve, DMD (Digital Micromirror Device) It can also be comprised with reflective light modulation elements.

In each of the embodiments of the second aspect of the present invention, the case where the control program stored in the ROM 2172 is executed in advance in executing the processing shown in the flowchart of FIG. 56 is described. The program is not limited and may be read from the RAM 2174 and executed from a storage medium having stored thereon programs.

The storage medium may be a semiconductor storage medium such as RAM or ROM, a magnetic storage type storage medium such as FD or HD, an optical reading system storage medium such as CD, CDV, LD or DVD, or a magnetic storage type / optical such as MO. As a read-out storage medium, any storage medium can be included as long as it is a computer-readable storage medium irrespective of an electronic, magnetic, or optical reading method.

In each of the above embodiments, the white light is spectroscopically divided into three primary colors of RGB using a single light source that emits white light as the light source 2010. However, the present invention is not limited thereto. The light source for emitting red light, the light source for emitting blue light, and the light source for emitting green light may be used to remove the means for spectroscopic white light, respectively.

As mentioned above, although this invention demonstrated the preferable Example, this invention is not limited to these Examples. Additions, omissions, substitutions, and other modifications can be made without departing from the spirit of the invention. The present invention is not limited by the above description, but only by the scope of the appended claims.

According to the first aspect of the present invention, the spatial modulation element pattern and the second light are formed even when a regular arrangement pattern is formed in the second light modulation element on which the image information modulated by the regularly arranged spatial light modulation element is projected. It is possible to provide an image display device capable of displaying a high gradation image by reducing moire generated in a pattern provided in a modulation element.

Further, according to the second aspect of the present invention, it is possible to provide an image display apparatus and a projector which can suppress deterioration in image quality caused by optical overlap of a plurality of light modulation elements while enlarging the luminance dynamic region. .

Claims (6)

An apparatus for displaying an image by modulating light from a light source based on display image data, A first light modulation element for modulating light from the light source, A second light modulation element for modulating light from the first light modulation element, A relay optical system disposed between the first light modulation element and the second light modulation element and transferring an optical image formed by the first light modulation element to the pixel surface of the second light modulation element; An optical low pass filter disposed between the first light modulation element and the second light modulation element; A micro lens array concentrating light from the optical low pass filter on each pixel of the second light modulation element An image display device having a. The method of claim 1, Each pixel of the first light modulation element and the second light modulation element includes an opening portion and a light shielding portion, The optical low pass filter bends a part of the light passing through the opening of the first light modulation element, and overlaps the light with a dark portion formed by the light blocking portion of the first light modulation element. doing Image display device. The method of claim 2, And the optical low pass filter comprises a group of prisms composed of a collection of prismatic elements having a refractive surface. The method of claim 3, wherein And the prism element includes a flat portion and a prism portion in the shape of a polygon. The method of claim 1, And the microlens array is arranged on the light incident side of the second light modulation element, and includes a lens group corresponding one to one to each pixel of the second light modulation element. As a projector, The image display device according to claim 1 Projection means Projector provided with.

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