JP2004219990A - Image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To adjust color balance while contrast is maintained. <P>SOLUTION: The image display device is equipped with a light source 11, a first lens array 13 for illuminating in superposition with a plurality of second or third-order light source image formed from the light source, a second lens array 14 and a lens 16 of superposition. In addition, the device is provided with a filter 15 which, among the optical fluxes illuminating in superposition, transmits a level-reducing wavelength region for the optical fluxes away from the optical axis LO while transmitting as they are for the remaining optical fluxes, and is also provided with a projection lens for projecting light modulated by a liquid crystal light valve 18. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to an image display device that displays an image by forming an image of modulated light modulated using a spatial light modulator (liquid crystal light valve).

  2. Description of the Related Art Conventionally, a liquid crystal image that displays an image by modulating illumination light for a liquid crystal light modulation element (hereinafter, referred to as a liquid crystal light valve) with the liquid crystal light modulation element and forming (projecting) the modulated light on a screen. A display device is provided. Such a liquid crystal image display device modulates the polarization state of the illumination light by controlling the illumination light for each pixel of the liquid crystal light valve using a reflective or transmissive liquid crystal light valve. ing.

  FIG. 15 is a side view showing a schematic configuration of the liquid crystal image display device.

  FIG. 15A shows a configuration of a lens array type liquid crystal image display device.

  A lens array type liquid crystal image display device uses a lens array as superimposing means for superimposing illumination on a liquid crystal light valve.

  As shown in FIG. 15A, the liquid crystal image display device includes a light source 111, a reflector 112 for reflecting light emitted from the light source 111 in the direction of the optical axis L0, and a first lens array (fly-eye lens) 113. , A second lens array (fly-eye lens) 114, a superposition lens 116, a condenser lens 117, and a liquid crystal light valve 118.

  On the first and second lens arrays 113 and 114, a plurality of two-dimensionally arranged lens cells having openings substantially similar in shape to the liquid crystal light valve 118 are used to spatially divide the exit opening surface of the reflector 112. are doing.

  Each lens cell of the first lens array 113 focuses a light beam on a lens cell of the second lens array 114 corresponding to each lens cell. On the second lens array 114, the same number of secondary light source images as the lens cells of the first lens array 113 are formed. On the other hand, each lens cell on the second lens array 114 matches the image of each lens cell aperture of the corresponding first lens array 113 with the incident surface of the liquid crystal light valve 118, and the superimposing lens 116 and the condenser lens Through the lens 117 and the polarizing beam splitter 119, the images of the respective lens cells of the first lens array 113 are overlapped on the incident surface of the liquid crystal light valve 118.

  In this way, a plurality of secondary light source images are formed in the second lens array 114. Further, a plurality of tertiary light source images are formed in the superimposing lens 116.

  The condenser lens 117 is arranged so that the illumination light of the liquid crystal light valve 118 is incident on the entrance pupil of the projection lens (not shown).

  As a result, the intensity of the reflected light beam from the reflector 112 is integrated, and the liquid crystal light valve 118 is superimposed and illuminated with a uniform intensity distribution by the plurality of secondary or tertiary light source images. In this way, the first and second lens arrays 113 and 114 and the superimposing lens 116 constitute a superimposing unit.

  The liquid crystal light valve 118 has a transmissive or reflective liquid crystal plate in which a plurality of liquid crystal cells are two-dimensionally arranged, and an analyzer (polarizing plate) that transmits only polarized light in a predetermined direction. Then, the transmitted or reflected light is polarization-modulated by the liquid crystal plate being controlled by an electric signal. That is, the illumination light is modulated into P-polarized light and S-polarized light according to the image information in the liquid crystal light valve 118.

  By the way, a light flux whose incident angle is shifted in a direction orthogonal to a plane including the incident optical axis and the output optical axis with respect to the polarizing beam splitter 119 has a polarization direction after passing through the polarizing beam splitter 119 which is a liquid crystal light valve. It deviates from the optimal direction at 118. Therefore, by arranging a λ / 4 plate (quarter wavelength plate) (not shown) between the polarization beam splitter 119 and the liquid crystal light valve 118, an optimal polarization direction for the liquid crystal light valve 118 is obtained. Compensated.

  The modulated light that has returned to the polarization beam splitter 119 via the liquid crystal light valve 118 passes through the polarization beam splitter 119 according to the polarization direction, returning to the first and second lens arrays 113 and 114, and the projection lens. And the optical path incident on the optical path. Then, only light in the polarization direction corresponding to the white information of the image information is projected as an image.

  This liquid crystal image display device enlarges and displays the information of the liquid crystal light valve with the above-described configuration.

  FIG. 15B shows a rod integrator type liquid crystal image display device.

  As shown in FIG. 15B, the rod integrator type liquid crystal image display device uses a rod integrator (glass rod) instead of the above-mentioned lens array as a superimposing means for superimposing and illuminating a liquid crystal light valve. is there.

  This liquid crystal image display device includes a light source 111, a reflector 112 for reflecting light emitted from the light source 111 in the optical axis L0 direction, a glass rod 121 as a rod integrator, an emission lens 122, a superimposing lens 116, a condenser It has a lens 117 and a liquid crystal light valve 118.

  In this liquid crystal image display device, the reflector 112 condenses and irradiates the light from the light source 111 on the incident surface of the glass rod 121 in the direction of the optical axis L0. Light incident on the incident surface of the glass rod 121 is repeatedly superimposed on the glass rod 121 by total reflection, and has a uniform distribution of emitted light. The outgoing lens 122 into which the outgoing light from the glass rod 121 is incident collects the outgoing light from the glass rod 121 onto the superimposing lens 116. A plurality of tertiary light source images corresponding to the number of reflections in the glass rod 121 are formed by the superimposing lens 122.

  As described above, the glass rod 121, the exit lens 122, and the superimposing lens 116 constitute a superimposing unit that superimposes and illuminates the liquid crystal light valve 118 through the condenser lens 117 and the polarizing beam splitter 119.

  In this liquid crystal image display device, the modulated light returned to the polarization beam splitter 119 via the liquid crystal light valve 118 is incident on the polarization beam splitter 119 according to the polarization direction to the optical path returning to the glass rod 121 side and to the projection lens. Optical path.

  Also in this liquid crystal image display device, a light beam whose incident angle is deviated in a direction orthogonal to a plane including the incident optical axis and the outgoing optical axis with respect to the polarizing beam splitter 119 is transmitted after passing through the polarizing beam splitter 119. The polarization direction deviates from the optimal direction in the liquid crystal light valve 118. Therefore, by arranging a λ / 4 plate (quarter wavelength plate) (not shown) between the polarization beam splitter 119 and the liquid crystal light valve 118, an optimal polarization direction for the liquid crystal light valve 118 is obtained. Compensated.

  The liquid crystal image display device shown in FIG. 15 is of a monochrome display. In a color display liquid crystal image display device, the light from the superimposing means is decomposed into RGB (three primary colors), and the RGB light is modulated by a corresponding liquid crystal light valve, and then these RGB lights are combined and projected.

  In such a color display liquid crystal image display device, it is necessary to perform color balance (white balance) adjustment for adjusting the ratio of RGB light. Such color balance adjustment is performed by adjusting the magnitude of an electric signal for controlling each of the RGB liquid crystal light valves. For example, the amount of transmitted light increases according to the magnitude of the electric signal applied to the liquid crystal light valve.

  For example, when the color temperature is set to be high, the electric signal of the RG is reduced and the modulation amount of the liquid crystal of the RG is suppressed so that the light amount of the RG is relatively small with respect to B. When the color temperature is set low, the electric signal of the BG is reduced so that the modulation amount of the liquid crystal of the BG is suppressed so that the light amount of the BG is relatively small with respect to R.

On the other hand, in a conventional liquid crystal image display device, miniaturization of the device and high brightness of a projected image are required. For this reason, in the liquid crystal image display device, since the liquid crystal light valve illuminates a wider range of light with a short optical path, the diameter of the light beam illuminating the liquid crystal light valve increases, and the F value of the illumination optical system tends to decrease. is there.
JP-A-7-49494 JP-A-2000-137289 JP 2001-33773 A

  By the way, in a liquid crystal image display device in which information of a light valve is enlarged and projected by the above-described superimposing means, when the RGB color balance is adjusted by an electric signal, a problem occurs that the contrast is reduced.

  Further, even when the F value of the illumination optical system is lowered, the leakage light of the liquid crystal light valve at the time of displaying black information increases, and a problem that the contrast is reduced occurs.

  FIG. 16 is a diagram illustrating a relationship between an input signal and a light output in the liquid crystal image display device.

  C in FIG. 16 is a light output L at the time of displaying black information where the input signal S is smaller than a predetermined value. Originally, the light output L is ideally at a zero level. However, due to various performances of the color separation / synthesis optical system and various performances of the liquid crystal used in the liquid crystal light valve 118, C-level light is output as leakage light. . On the other hand, when the input signal S reaches a peak, the light output L becomes A level. At this time, the contrast ratio CR of the liquid crystal image display device is determined by A / C.

  Here, since the C level due to the leak light increases due to the lower F-number, the contrast ratio CR decreases.

  By the way, if the light output L is suppressed and the signal is adjusted to the A 'level light output in order to balance the colors, the contrast ratio CR' = A '/ C, which causes significant contrast deterioration.

  Here, the incident angle characteristics of the transmittance of the polarization beam splitter will be examined.

  FIG. 17 is a graph showing the incident angle characteristics of the transmittance of the polarizing beam splitter.

  As shown in FIG. 17A, the angle between the incident light and the optical axis is referred to as an incident angle β with respect to a polarizing beam splitter installed such that the incident surface is perpendicular to the optical axis.

  The broken lines a to e shown in FIG. 17B indicate the P-polarized light transmittance of the polarizing beam splitter with respect to the light beam having the incident angle βc <βb <βa = 0 <βd <βe. As described above, when the incident angle shifts from the optical axis and the incident angle with respect to the polarizing film surface of the polarizing beam splitter changes, the transmittance of S-polarized light increases and the transmittance of P-polarized light decreases. Therefore, the transmitted S-polarized light component and the reflected P-polarized light component become leaked light, which increases the C level in FIG. 17 and lowers the contrast.

  The deterioration of the contrast due to such factors depends on the shift amount of the incident angle in a direction parallel to a plane including the incident optical axis and the exit optical axis of the polarizing beam splitter.

  Further, the dispersion characteristics of a λ / 4 plate (quarter wavelength plate) for compensating the polarization direction with respect to the liquid crystal light valve 118 will be discussed.

  FIG. 18 is a graph showing dispersion characteristics of a λ / 4 plate.

  The straight line a in the figure is the ideal λ / 4 wavelength plate characteristic, and the curve b shows the actual λ / 4 wavelength plate characteristic (when the optimum wavelength is 550 nm).

  As described above, the λ / 4 plate has a dispersion characteristic, and has an optimum characteristic with respect to incident light of a certain single wavelength. However, when the incident light covers a certain band, the λ / 4 plate has a dispersion characteristic. All of the bands do not have optimal characteristics. As the light incident on the λ / 4 plate deviates from the optimum wavelength, the polarization direction compensating ability also deteriorates, and components that cannot be fully compensated are generated. The component that could not compensate for the polarization direction becomes leaked light, which increases the C level in FIG. 16 and lowers the contrast.

  Contrast degradation due to such factors depends on the amount of incident angle shift in a direction orthogonal to a plane including the incident optical axis and the exit optical axis of the polarizing beam splitter.

  As described above, with respect to the plane including the incident optical axis and the output optical axis of the polarizing beam splitter, the incident angle shift in the parallel direction and the contrast deterioration factor due to the incident angle shift in the orthogonal direction are different. Whether the deviation of the incident angle in the direction is the main cause of the contrast deterioration depends on the characteristics of the polarizing beam splitter and the λ / 4 plate used.

  Here, a configuration has conventionally been proposed in which the outer peripheral portion of the illumination optical system is shielded from light to lower the F value of the illumination optical system to prevent deterioration in contrast.

  FIG. 19 is a side view showing a step of forming a filter and a light shielding film on a part of the optical component.

  When a filter and a light-shielding film are formed by vapor deposition on an outer peripheral portion of an optical component 123 such as a lens array, as shown in FIG. When applying an AR (Antireflection; antireflection) coat, an annular mask A is used.

  When a filter or a light shielding film is formed on the outer peripheral portion 127 as shown in FIG. 19B, a circular mask 129 is required as shown in FIG. 19C. However, it is necessary to position the mask 129 on the inner peripheral portion of the optical component 123, but it is impossible to hold the mask 129 at this position. Can not.

  On the other hand, as described above, since the vertical angle shift component and the horizontal angle shift component in the illumination optical system have different optical components that cause contrast deterioration, the entire outer peripheral portion of the illumination optical system is shielded. You don't have to.

  The present invention has been proposed in view of the above-described situation, and in adjusting the color balance, by increasing the F value of the illumination optical system for the color to be adjusted, it is possible to effectively prevent the deterioration of contrast. It is an object of the present invention to provide an image display device capable of performing the above.

  In addition, the present invention optimizes the shape of the filter in the illumination optical system, thereby increasing the F value of the illumination optical system for the color to be adjusted in the color balance adjustment, thereby achieving more effective contrast deterioration. It is an object of the present invention to provide an image display device capable of realizing the prevention of the above.

  In order to solve the above-described problem, an image display device according to the present invention includes a white light source, a superimposing unit that superimposes light emitted from the white light source, and decomposes the light superimposed by the superimposing unit into three primary colors. Splitting / combining means for supplying the spatial light modulating elements that respectively modulate the three primary colors of light, and synthesizing the modulated light modulated by the spatial light modulating element; , The superimposing means has means for adjusting three primary colors.

  Preferably, the superimposing means has one of a set of a lens array, a glass rod, or a prism having internal reflection.

  The spatial light modulating element is a reflective spatial light modulating element, and transmits an optical path of modulated light from each of the reflective spatial light modulating elements to an optical path returning to the decomposing / combining means in accordance with a polarization direction of the modulated light. And a polarization beam splitter for separating the light beam into another light path, wherein the superimposing means attenuates and passes light of an arbitrary wavelength band of the illumination light on both sides of the optical axis by passing the light. The filter has a filter for adjusting the ratio of three primary colors in light, and the edge of the filter on the optical axis side is orthogonal to or parallel to a plane including an optical axis entering and exiting the polarization beam splitter. Preferably, it is oriented.

  The spatial light modulating element is a reflective spatial light modulating element, and transmits an optical path of modulated light from each of the reflective spatial light modulating elements to an optical path returning to the decomposing / combining means in accordance with a polarization direction of the modulated light. And a polarization beam splitter for separating the light into another optical path, wherein the superimposing means adjusts the ratio of the three primary colors in the modulated light by attenuating and passing light of an arbitrary wavelength band of the illumination light. And a light-shielding unit that shields a light flux in an arbitrary area of the illumination light, wherein the filter excludes at least a part of the outer peripheral portion in the illumination light flux defined by the light-shielding means. Preferably, it is provided in the region.

  In this image display device, of the luminous flux incident on the liquid crystal light valve, the luminous flux distant from the optical axis is blocked by a filter in the wavelength range where the level is reduced. As described above, in this image display device, since the light incident on the liquid crystal light valve is optically controlled, it is not necessary to suppress the amount of modulated light by electrically controlling the liquid crystal light valve. Therefore, the light quantity of the liquid crystal light valve at the time of displaying black information is also relatively reduced, so that even if the color balance (white balance) is adjusted, the contrast of the displayed image does not decrease.

  In this image display device, the wavelength range in which the level is reduced is blocked for a light beam far from the optical axis. Therefore, the substantial system of the light beam can be reduced, and the F value of the illumination optical system can be increased. That is, since the angle of light incident on the liquid crystal light valve that modulates light can be reduced, the amount of light leaking to the liquid crystal light valve during black information display can be reduced. Therefore, the level of output light at the time of displaying black information can be reduced, and the contrast can be improved.

  It is preferable that the filter adjusts the color balance by controlling the light supplied from the superimposing means.

  According to the present invention, in adjusting the color balance in the image display device, the deterioration of the contrast can be effectively prevented by increasing the F value of the illumination optical system for the color to be adjusted.

  In addition, the present invention optimizes the shape of a filter in an illumination optical system in an image display device, thereby increasing the F value of the illumination optical system for a color to be adjusted in color balance adjustment, thereby achieving a further effect. Thus, it is possible to effectively prevent the contrast from being deteriorated.

  Hereinafter, embodiments of an image display device according to the present invention will be described in detail with reference to the drawings.

[First Embodiment]
FIG. 1 is a diagram illustrating a configuration of a liquid crystal image display device according to the present embodiment.

  FIG. 1 shows a monochrome liquid crystal image display device in which light emitted from a light source 11 irradiates a single liquid crystal light valve 18 for simplicity. This diagram is provided to explain the principle of the present invention. A color separation optical system that separates / combines light into RGB is used in a liquid crystal image display device for color display that requires adjustment of color balance (white balance). System and a color combining optical system.

  FIG. 1A is a diagram illustrating a lens array type liquid crystal image display device.

  This liquid crystal image display device has a light source 11 and a reflector 12 that reflects light emitted from the light source in the direction of the optical axis L0.

  As the light source 11, a light source that emits white light, such as a high-pressure mercury lamp or a metal halide lamp, is used. The reflector 12 has a spheroidal reflecting surface around the optical axis L0, reflects light emitted from the light source 11 on the reflecting surface, and emits the light as a light beam parallel to the optical axis L0.

  This liquid crystal image display device has a first lens array (fly-eye lens) 13, a second lens array (fly-eye lens) 14, a filter 15, a superposition lens 16, a condenser lens 17, A liquid crystal light valve 18.

  The first and second lens arrays 13 and 14 are two-dimensionally arranged with a plurality of lens cells having a shape similar to the liquid crystal light valve 18 so that the opening from which the reflector 12 emits a light beam is spatially divided. .

  The first lens array 13 condenses a light beam on the lens cells of the second lens array 14 corresponding to the lens cells, and the same number of lens cells on the second lens array 14 as the lens cells of the first lens array 13. Is formed.

  The second lens array 14 matches the lens cell aperture of the first lens array 13 with the surface of the liquid crystal light valve 18 for each lens cell, and the lens cells of the first lens array 13 Overlap on 18 faces.

  The filter 15 cuts off a wavelength range in which the level of the light flux transmitted through the first and second lens arrays 13 and 14 is lowered for the light flux far from the optical axis L0, and transmits the remaining light flux as it is.

  The superimposing lens 16 makes each lens cell center coincide with the center of the liquid crystal light valve 18 so that each lens cell of the first lens array 132 overlaps on the liquid crystal light valve 18 surface.

  The condenser lens 17 allows the illumination light of the liquid crystal light valve 18 to enter the direction of the entrance pupil of a projection lens (not shown).

  The liquid crystal light valve 18 has a liquid crystal plate in which a plurality of liquid crystal cells are two-dimensionally arranged and an analyzer (polarizing plate) that transmits only polarized light in a predetermined direction, and controls the amount of light transmitted through each liquid crystal cell. Modulate the image.

  In this liquid crystal image display device, a plurality of secondary light source images on the second lens array 14 are formed. Further, a plurality of tertiary light source images are formed in the superimposing lens 16. Then, the liquid crystal bulb 18 is superimposedly illuminated using the tertiary light source image. In the liquid crystal image display device, the superimposing means for performing the superimposed illumination includes the first and second lens arrays 13 and 14 and the superimposing lens 16.

  The filter 15 is installed between the second lens array 14 where the secondary light source image is formed and the superimposing lens 16 where the tertiary light development is formed. Then, it is applied to a light beam having an area corresponding to the level to be dropped to block a desired wavelength range, and the remaining light beam is transmitted as it is.

  Here, the filter 15 blocks the desired wavelength range in order from a light beam far from the optical axis. Thereby, the diameter of the light beam transmitted through the filter 15 is substantially reduced. That is, although the diameter of the light beam is narrowed only in the desired wavelength region by the filter 15, the light amount outside the light beam is reduced as a whole light beam including each wavelength region, so that the diameter of the light beam is substantially reduced. It can be said. In other words, it can be said that the F value has substantially increased.

  As described above, since the diameter of the light beam is substantially reduced by the filter 15, the light far from the optical axis L0 and incident on the liquid crystal light valve 18 at a large angle is reduced. Therefore, as will be described later, light leakage when the liquid crystal light valve 18 displays black information is reduced.

  For example, when an R transmission filter is applied to a light flux having an area corresponding to the level to be dropped, light rays a, b, e, and f are only R light, and light rays c and d are white light of R + G + B. Therefore, the light superimposed on the liquid crystal light valve 18 becomes light having a low color temperature with the components of G and B reduced.

  Although FIG. 1 shows an example in which the filter 15 is provided between the second lens array 14 and the superimposed lens 16, the filter 15 may be provided between the first and second lens arrays 13 and 14. it can.

  FIG. 1B is a diagram showing a glass rod type liquid crystal image display device.

  This liquid crystal image display device employs a lens array type liquid crystal image display device shown in FIG. 1A and a glass rod 21 and an emission lens 22 in place of the first and second lens arrays 13 and 14. , The filter 15 is provided behind the superimposing lens 16. Portions similar to those in the lens array system shown in FIG. 1A are denoted by the same reference numerals, and description thereof is omitted.

  The reflector 12 reflects the light emitted from the light source 11 on the spheroidal reflecting surface, and condenses and enters the incident surface of the glass rod 21.

  The glass rod 21 totally reflects the light incident from the reflector 12 multiple times on the inner surface. The emission lens 22 supplies the light emitted from the glass rod 21 to the relay lens 16.

  At this time, a plurality of secondary light source images are formed on the emission surface of the glass rod 21. A plurality of tertiary light source images are formed on the superimposing lens 16. The number of the secondary light source images and the number of the tertiary light source images correspond to the number of times that the light is totally reflected in the glass rod 21.

  The filter 15 is installed downstream of the superimposing lens 16 on which a tertiary light source image is formed. Then, it is applied to a light beam having an area corresponding to the level to be dropped to block a desired wavelength range, and the remaining light beam is transmitted as it is. As in the case of the lens array system shown in FIG. 1 (a), it shows an R transmission filter. Light rays a, b, e, and f are only R light, and light rays c and d are R + G + B white light. is there.

  As described above, in the liquid crystal image display device shown in FIG. 1, parts related to the color separation optical system and the color synthesis optical system are omitted for simplicity. Actually, a liquid crystal light valve for modulating RGB light is provided. A color separation optical system for separating light into RGB is provided at a stage preceding the liquid crystal light valve, and a color combining optical system for combining RGB light is provided at a stage subsequent to the liquid crystal light valve. The projection lens projects the light combined by the color combining optical system.

  FIG. 2 is a perspective view showing a filter.

  The filter 31 in the figure shows a specific example of the filter 15 shown in FIG. The filter 31 has 6 × 6 elements in the vertical and horizontal directions, and can control light transmission for each element. That is, for each element, it is possible to switch between a state in which light in a wavelength range where the level is lowered is blocked and a state in which light is transmitted as it is.

  For example, as shown in FIG. 2 (a), the light is kept intact for the remaining central two columns of elements 31b in a state where the wavelength range in which the level is lowered for the two columns of elements 31a from the rightmost column and the leftmost column is cut off. It can be controlled to transmit light.

  In this way, the light in the wavelength range where the level is reduced is blocked in order from the elements away from the optical axis L0 of the lens so as to be symmetric about one straight line orthogonal to the optical axis passing through the center of the filter 31, and the remaining light is blocked. The element can be controlled to transmit light as it is.

  In addition, for example, as shown in FIG. 2B, light in a wavelength range where the level is reduced is cut off for elements 31c around the array, and light for the remaining four elements 31d at the center is transmitted as it is. Can be controlled.

  As described above, it is possible to control the elements constituting the filter 31 so as to block the light in the wavelength range in which the level is reduced in order from the surrounding elements, and to transmit the remaining elements as they are.

  In the present embodiment, in both of FIGS. 2A and 2B, control is performed so that light is transmitted through the central element near the optical axis L0 as it is. Therefore, the substantial diameter of the light beam illuminating the liquid crystal light valve 18 becomes smaller, so that the F value becomes larger. Further, it is possible to suppress light incident on the liquid crystal valve 18 at a large angle.

  Here, when a lens array is used as shown in FIG. 1A, the elements constituting the filter 31 can be arranged so as to correspond to the arrangement of the lens cells constituting the lens array. In this way, by associating the elements of the filter 31 and the lens array with the arrangement of the lens cells, it is possible to suppress color unevenness resulting from mismatching of these arrangements.

  FIG. 3 is a diagram showing the relationship between the F value and the leakage light of the liquid crystal light valve.

  This liquid crystal light valve schematically shows the liquid crystal light valve 18 shown in FIG. 1, and has a liquid crystal plate 41 and an analyzer (polarizing plate) 42. In the figure, no signal is applied to the liquid crystal plate 41, and the liquid crystal molecules are aligned so that the major axis direction is perpendicular to the liquid crystal plate 41.

  Here, the description will be made assuming that the reflection type liquid crystal plate 41 is used. However, the relationship between the F value and the incident angle and the leakage light is the same when the transmission type liquid crystal plate is used.

  FIG. 3A illustrates a state in which light L1 that is orthogonal to the liquid crystal plate 41 or has a small angle (high F value) passes. In this case, the light L2 that has passed (reflected) through the liquid crystal plate 41 is absorbed and blocked by the analyzer 42 without being modulated because the major axis direction of the liquid crystal molecules is aligned with the light L1 direction.

  FIG. 3B illustrates a state in which light L1 ′ having a large angle (low F value) with respect to the liquid crystal plate 41 passes. In this case, the liquid crystal has its major axis aligned in a direction orthogonal to the liquid crystal plate 41, but the light L1 'is slightly modulated because it enters the liquid crystal molecules at a large angle. Therefore, the modulated light passes through the analyzer 42 and becomes leaked light. Such light leakage raises the light output when displaying black information.

  As described above, in the present embodiment, the filter 15 reduces the substantial diameter of the light beam and the F value. Therefore, the liquid crystal image display device of the present embodiment corresponds to FIG. 3A in which the angle of incidence is orthogonal or small. That is, in the present embodiment, the leakage light is small, and the light output when displaying black information is small.

  FIG. 4 is a diagram illustrating a relationship between an input signal and a light output in the liquid crystal image display device according to the present embodiment.

  In the figure, C is the light output L when displaying black information where the input signal S is smaller than a predetermined value. Although the light output L in this case is ideally zero level, C-level light is output as leakage light due to various performances of the color separation / synthesis optical system and various performances of the liquid crystal used in the liquid crystal light valve 18. You. As described above, in the liquid crystal image display device of the present embodiment, the F value is large and the incident angle is small, so that the leakage light of the liquid crystal light valve is small.

  On the other hand, when the input signal S reaches a peak, the light output L becomes A level. At this time, the contrast ratio CR of the liquid crystal image display device is determined by A / C. In the present embodiment, the contrast ratio CR is large because there is little leakage light and the level C when displaying black information is low.

  Here, if the light output L is suppressed and the signal is adjusted to the A 'level light output in order to adjust the color balance (white balance), the leakage light at the time of displaying black information also decreases to the C' level. This is because, in the present embodiment, the color balance is adjusted by optically limiting the amount of light transmitted through the filter. For this reason, the leakage light C ‘at the time of displaying the black information decreases according to the amount of light blocked by the filter for color balance adjustment.

  Therefore, in the present embodiment, even if the light output decreases from A to A ', the leakage light C at the time of displaying black information also decreases at the same ratio to C'. As a result, the contrast ratio CR ′ = A ′ / C ′ = CR, and the contrast is maintained even if the peak level light output is adjusted to lower the A level for color balance.

  FIG. 5 is a diagram more specifically showing the configuration of the liquid crystal image display device of the present embodiment.

  This liquid crystal image display device shows the lens array type liquid crystal image display device shown in FIG. 1A in more detail, including a color separation / synthesis optical system.

  This liquid crystal image display device includes a light source 51, a reflector 52 that reflects light of the light source 51 in one direction, a collimator lens 53, a red light / ultraviolet light cut filter 54, a first lens array 55, and a filter 56. , A second lens array 57, a combiner 58, a superposition lens 59, a condenser lens 69, and a polarizer (polarizing plate) 61.

  The collimator lens 53 brings the light supplied from the reflector 52 closer to parallel light so as to increase the light use efficiency.

  The infrared light / ultraviolet light cut filter 54 blocks infrared light and ultraviolet light unnecessary for displaying an image, thereby preventing heat generation of a subsequent optical system.

  The first and second lens arrays 54 and 57 and the superimposing lens 59 constitute superimposing means for superimposing and illuminating the liquid crystal light valve with a plurality of tertiary light source images formed on the superimposing lens 59.

  The filter 56 is installed between the first and second lens arrays 54 and 47, and controls so that a light beam far from the optical axis is blocked in a wavelength range in which the level is reduced, and a light beam close to the optical axis is transmitted as it is. The color balance (white balance) of the liquid crystal image display device is adjusted by limiting the amount of light flux limited to the wavelength range.

  The combiner 58 converts incident light into S-polarized light in order to improve the use efficiency of light in the polarization optical system at the subsequent stage.

  The condenser lens 60 allows the illumination light of the liquid crystal light valve to enter the entrance pupil of the projection lens.

  The polarizer 61 restricts only S-polarized light to be transmitted.

  This liquid crystal image display device includes a color separation / synthesis optical system 65, a B color liquid crystal light valve 62, an R color liquid crystal light valve 63, a B color liquid crystal light valve 64, an analyzer 66, a projection lens 67, have.

  The color separation / synthesis optical system 65 separates the incident light into RGB and supplies the light to the liquid crystal light valves 62, 63, 64 corresponding to each color, and the RGB modulated by the liquid crystal light valves 62, 63, 64. Synthesize light.

  Since the color separation optical system 65 can have various configurations using a prism or a dichroic mirror, a specific configuration is omitted in the drawings. In the block of the color separation optical system 65 in the figure, only the optical path until the RGB light reaches the liquid crystal light valves 62, 63, 64 of each color is shown.

  The analyzer (polarizing plate) 66 transmits only P-polarized light. Therefore, light not modulated by the liquid crystal light valves 62, 63, 64 is blocked by the analyzer 66.

  The projection lens 67 projects the light transmitted through the analyzer 66 toward the screen.

  In the present embodiment, the F number of the optical system can be configured to be, for example, 2.4. In this case, the angle of incidence on the reflection type liquid crystal light modulation element is 11.8 degrees at the maximum. Here, for example, if it is desired to reduce the B color light by 50%, the F number is changed from 2.4 to 3.4. The incident angle at this time is 8.4 degrees at the maximum.

[Second embodiment]
FIG. 6 is a side view showing a second embodiment of the liquid crystal image display device according to the present invention using a lens array type illumination optical system.

  The illumination optical system according to the second embodiment has the same configuration as that of the first embodiment except that a polarizing beam splitter 19 is disposed between the condenser lens 17 and the liquid crystal light valve 18. It is.

  The illumination light for the liquid crystal light valve 18 is modulated into P-polarized light and S-polarized light in accordance with the image information in the liquid crystal light valve 18 and returns to the polarization beam splitter 19. , And an optical path returning to the first and second lens arrays 13 and 14 and an optical path incident on the projection lens. Then, only light in the polarization direction corresponding to the white information of the image information is projected as an image.

  In this illumination optical system, a light beam whose incident angle is shifted in a direction orthogonal to a plane including the incident optical axis and the outgoing optical axis with respect to the polarization beam splitter 19 is polarized light transmitted through the polarization beam splitter 19. Since the direction deviates from the optimum direction in the liquid crystal light valve 18, by disposing a λ / 4 plate (quarter wavelength plate) (not shown) between the polarizing beam splitter 19 and the liquid crystal light valve 18, Compensation is performed so that the polarization direction is optimal for the liquid crystal light valve 18.

  In the vicinity of the second lens array 14 where the secondary light source image of the light source 11 is formed, a filter 15 for cutting a color whose level is to be reduced is covered corresponding to the opening of the lens array 14 corresponding to the level to be reduced. Are arranged as follows.

  At this time, the light rays a, b, e, and f are R light only, and c and d are R + G + B white light, and the G and B components of the illumination light superimposed on the liquid crystal light valve 18 are reduced. And light having a low color temperature.

  As a result, in the relationship of the optical output with respect to the input signal shown in FIG. 4, even if the optical output changes from A to A ′, C becomes C ′ at the same rate, and the contrast does not deteriorate. In the case of the GB color, a component having a sharp angle with respect to the polarizing film surface of the polarizing beam splitter 19 is eliminated, that is, the F value is increased, so that the contrast is improved as described with reference to FIG.

  FIG. 7 is a side view showing a second embodiment of the liquid crystal image display device according to the present invention using a rod integrator type illumination optical system.

  This illumination optical system has the same configuration as that of the first embodiment except that a polarizing beam splitter 19 is disposed between the condenser lens 17 and the liquid crystal light valve 18.

  The illumination light for the liquid crystal light valve 18 is modulated into P-polarized light and S-polarized light in accordance with the image information in the liquid crystal light valve 18 and returns to the polarization beam splitter 19. , The optical path returning to the glass rod 21 side and the optical path entering the projection lens. Then, only light in the polarization direction corresponding to the white information of the image information is projected as an image.

  Also in this illumination optical system, a light beam whose incident angle is deviated in a direction orthogonal to a plane including the incident optical axis and the outgoing optical axis with respect to the polarization beam splitter 19 is polarized after passing through the polarization beam splitter 19. Since the direction deviates from the optimum direction in the liquid crystal light valve 18, by disposing a λ / 4 plate (quarter wavelength plate) (not shown) between the polarizing beam splitter 19 and the liquid crystal light valve 18, Compensation is performed so that the polarization direction is optimal for the liquid crystal light valve 18.

  After a relay lens 16 on which a tertiary light source image of a light source is formed, a filter 15 for cutting a color whose level is to be lowered is disposed so as to cover an area corresponding to the level to be lowered. For example, if an R transmission filter is disposed, the light rays a, b, e, and f are only R light, c and d are R + G + B white light, and the illumination light superimposed on the liquid crystal light valve 18 is G light. And B components are reduced, resulting in light having a low color temperature.

  FIGS. 8A and 8B are perspective views showing an example of a direction in which a filter is inserted in this embodiment.

  As shown in FIG. 8A, the filter 15 has an edge A on the inner side (optical axis side) of the filter 15 with respect to a plane including the incident optical axis and the output (reflection) optical axis of the polarizing beam splitter 19. Are arranged so as to be orthogonal to each other. Alternatively, as shown in FIG. 8B, the edge A on the inner side (on the optical axis side) of the filter 15 is positioned with respect to a plane including the incident optical axis and the output (reflected) optical axis of the polarizing beam splitter. To be parallel to each other.

  In other words, when there is much leakage light due to the inclination of the incident angle of the light beam incident on the polarization beam splitter 19, as shown in FIG. 8A, the edge A on the inner side (optical axis side) of the filter 15 is polarized. The beam splitter 19 is disposed so as to be in a direction orthogonal to a plane including the incident optical axis and the output (reflection) optical axis of the beam splitter 19.

  If there is much leakage light due to the deterioration of the polarization direction compensating ability due to the dispersion characteristic of the λ / 4 plate, as shown in FIG. 8B, the inner (optical axis side) edge of this filter 15 A is arranged so as to be parallel to a plane including the incident optical axis and the outgoing (reflective) optical axis of the polarizing beam splitter.

  FIG. 9 is a perspective view showing an example in which the filter 15 is formed by directly depositing the filter 15 on the second lens array 14.

  The filter 15 may be formed by vapor deposition directly on the second lens array 14, as shown in FIGS. 9A and 9B.

  The insertion position of the filter 15 may be anywhere between the light source 11 and the liquid crystal light valve 18. However, when the filter 15 is inserted between the light source 11 and the superimposing lens of the superimposing means, color unevenness does not occur. Therefore, it is preferable.

  Even if this illumination optical system is used, a liquid crystal image display device can be configured as shown in FIG. The configuration of this liquid crystal image display device is the same as that described above.

[Third Embodiment]
FIG. 10 is a side view showing a third embodiment of the liquid crystal image display device according to the present invention using a lens array type illumination optical system.

  The overall configuration of the illumination optical system according to the third embodiment is the same as that of the second embodiment described above except that the filter 15 is formed directly on the incident surface side of the second lens array 14 by vapor deposition. This is the same as the embodiment.

  That is, on the incident surface side of the second lens array 14 where the secondary light source image of the light source 11 is formed, a filter 15 for cutting a color whose level is to be lowered is provided corresponding to the opening of the lens array corresponding to the level to be lowered. And cover it. At this time, the light rays a, b, e, and f are R light only, and c and d are R + G + B white light, and the light superimposed on the liquid crystal light valve 18 has the G and B components reduced. , Resulting in light having a low color temperature.

  As a result, in the relationship of the optical output with respect to the input signal shown in FIG. 4, even if the optical output changes from A to A ′, C becomes C ′ at the same rate, and the contrast does not deteriorate. In the case of the GB color, a component having a sharp angle with respect to the polarizing film surface of the polarizing beam splitter 19 is eliminated, that is, the F value is increased, so that the contrast is improved as described with reference to FIG.

  FIG. 11 is a side view showing a third embodiment of the liquid crystal image display device according to the present invention using a rod integrator type illumination optical system.

  The overall configuration of this illumination optical system is the same as that of the above-described second embodiment, except that the filter 15 is formed directly on the emission surface side of the relay lens 16 by vapor deposition.

  That is, a filter 15 for cutting a color whose level is to be lowered is formed on the emission surface side of the relay lens 16 on which the tertiary light source image of the light source 11 is formed so as to cover an area corresponding to the level to be lowered. For example, if an R transmission filter is arranged, the light rays a, b, e, and f are only R light, c and d are white light of R + G + B, and the light superimposed on the liquid crystal light valve 18 is G light. The B component is reduced, resulting in light having a low color temperature.

  FIG. 12 is a perspective view showing a state where the filter 15 is deposited on the second lens array 14.

  In this embodiment, as shown in FIG. 12, at least a part of the outer peripheral portion of the second lens array 14 is provided with a region without the filter 15. Accordingly, as described above with reference to FIG. 17, when the filter 15 is formed by vapor deposition, it is possible to hold the mask B that covers the central portion of the second lens array 14.

  Here, whether the region without the filter 15 is provided in the vertical direction as shown in FIG. 12A or in the horizontal direction as shown in FIG. 12B depends on the polarization beam splitter to be used and the λ / It differs depending on the four-wavelength plate and is provided on the side where the contrast is high.

  That is, when there is much leakage light due to the inclination of the incident angle of the light beam incident on the polarization beam splitter 19, as shown in FIG. It is formed so as to be in a direction (vertical direction in FIG. 12) arranged in a direction parallel to a plane including the emission (reflection) optical axis.

  If there is a large amount of leaked light due to the deterioration of the polarization direction compensating ability due to the dispersion characteristic of the λ / 4 plate, as shown in FIG. It is formed so as to be a direction (left-right direction in FIG. 12) arranged in a direction orthogonal to a plane including the incident optical axis and the outgoing (reflective) optical axis.

  Further, as shown in FIG. 12, the filter 15 is formed in an area in units of cells of the second lens array 14 so that the amount of transmitted light of the filter 15 and the contrast of the displayed image are most balanced. It can be optimized to a certain shape.

  Even if this illumination optical system is used, a liquid crystal image display device can be configured as shown in FIG. The configuration of this liquid crystal image display device is the same as that described above.

[Fourth Embodiment]
FIG. 13 shows an embodiment in which a lens array type illumination system is used.

  In the vicinity of the second array 14 where the secondary light source image is formed, a filter for cutting a color whose level is to be reduced is covered with the number of apertures of the lens array corresponding to the level to be reduced. For example, when the R transmission filter 15 and the RG transmission filter 25 are arranged, light rays a and f are R light only, b and e are R + G light, c and d are R + G + B white (white) light. The superimposed light has a low color temperature with a reduced GB component. Thereby, as shown in the relationship of the optical output with respect to the input signal in FIG. 4, even if the optical output changes from A to A ', C becomes C' at the same ratio, and the contrast does not deteriorate. At the same time, the GB light has no sharp component with respect to the film surface of the polarizing beam splitter 19 (the F value increases), and the contrast is improved.

  FIG. 14 shows an example of a structure in which a filter and a light shielding plate are integrated.

  As shown in FIG. 14, a light shielding plate is provided between the lens arrays, and the first filter is fixed. In addition, the second filter is deposited on the second lens array, but it may be attached to a light shielding plate, or both the first and second filters may be deposited on the second lens array. The adhesive bonding the light-shielding plate and the first filter has heat resistance of 200 ° C. or more. Furthermore, the filter attached to the light shielding plate has a structure in which the light shielding plate and the fixing member for the lens array are integrated, so that the number of components can be reduced.

  The above-described embodiment shows a specific example of the present invention, and the present invention is not limited to this. It will be apparent to those skilled in the art that various modifications and the like can be made without departing from the present invention.

FIG. 1 is a side view illustrating a configuration of a liquid crystal image display device according to an embodiment of the present invention. It is a perspective view which shows a filter. FIG. 4 is a cross-sectional view illustrating a relationship between an F value and leakage light of a liquid crystal light valve. 5 is a graph illustrating a relationship between an input signal and a light output in the liquid crystal image display device according to the present embodiment. FIG. 2 is a side view more specifically showing the configuration of the liquid crystal image display device of the present embodiment. FIG. 9 is a side view showing a second embodiment of the liquid crystal image display device according to the present invention using a lens array type illumination optical system. FIG. 9 is a side view showing a second embodiment of the liquid crystal image display device according to the present invention using a rod integrator type illumination optical system. FIG. 13 is a perspective view illustrating an example of a direction in which a filter is inserted in the second embodiment. FIG. 13 is a perspective view illustrating an example in which a filter is formed by vapor deposition in the second embodiment. FIG. 11 is a side view showing a third embodiment of the liquid crystal image display device according to the present invention using a lens array type illumination optical system. FIG. 11 is a side view showing a third embodiment of the liquid crystal image display device according to the present invention using a rod integrator type illumination optical system. FIG. 13 is a perspective view illustrating an example in which a filter is formed by vapor deposition in the third embodiment. FIG. 4 is a diagram illustrating a fourth embodiment. It is a figure showing the example of the structure at the time of integrating a filter and a shading plate. FIG. 2 is a diagram illustrating a schematic configuration of a liquid crystal image display device. FIG. 4 is a diagram illustrating a relationship between an input signal and a light output in the liquid crystal image display device. 5 is a graph showing the incident angle characteristics of the transmittance of the polarizing beam splitter. 5 is a graph showing dispersion characteristics of a λ / 4 plate. It is a side view which shows the process of forming a filter and a light shielding film in a part of optical component.

Explanation of reference numerals

Reference Signs List 11 light source 12 reflecting mirror 13 first lens array 14 second lens array 15 filter 16 relay lens 17 condenser lens 18 liquid crystal light valve 19 polarizing beam splitter 21 glass rod 22 emission lens

Claims (4)

A white light source,
Superimposing means for superimposing light emitted from the white light source,
A decomposing / combining unit that decomposes the light superimposed by the superimposing unit into three primary colors, supplies the light to the three primary colors, and supplies the modulated light to the spatial light modulators, and synthesizes the modulated light modulated by the spatial light modulator;
Projection means for projecting light that has passed through the decomposition and synthesis means,
In the image display device having
The image display device, wherein the superimposing means has means for adjusting three primary colors.   2. The image display device according to claim 1, wherein the superimposing means includes one of a set of a lens array, a glass rod, and a prism having internal reflection.   The spatial light modulating element is a reflective spatial light modulating element, and transmits an optical path of modulated light from each of the reflective spatial light modulating elements to an optical path returning to the decomposing / combining means in accordance with a polarization direction of the modulated light. And a polarization beam splitter for separating the light beam into another light path, wherein the superimposing means attenuates and passes light of an arbitrary wavelength band of the illumination light on both sides of the optical axis by passing the light. The filter has a filter for adjusting the ratio of three primary colors in light, and the edge of the filter on the optical axis side is orthogonal to or parallel to a plane including an optical axis entering and exiting the polarization beam splitter. The image display device according to claim 1, wherein the image display device is oriented in a direction.   The spatial light modulating element is a reflective spatial light modulating element, and transmits an optical path of modulated light from each of the reflective spatial light modulating elements to an optical path returning to the decomposing / combining means in accordance with a polarization direction of the modulated light. And a polarization beam splitter for separating the light into another optical path, wherein the superimposing means adjusts the ratio of the three primary colors in the modulated light by attenuating and passing light of an arbitrary wavelength band of the illumination light. And a light-shielding unit that shields a light flux in an arbitrary area of the illumination light, wherein the filter excludes at least a part of the outer peripheral portion in the illumination light flux defined by the light-shielding means. The image display device according to claim 1, wherein the image display device is provided in an area.

Images