JP4581371B2 - Image display device - Google Patents

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).

  Conventionally, a liquid crystal image that displays an image by modulating illumination light on a liquid crystal light modulation element (hereinafter referred to as a liquid crystal light valve) by the liquid crystal light modulation element and forming an image on (projecting) the modulated light on a screen. A display device is provided. Such a liquid crystal image display device uses a reflective or transmissive liquid crystal light valve, and modulates the polarization state of the illumination light by controlling the illumination light for each pixel of the 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 the configuration of a lens array type liquid crystal image display device.

  The lens array type liquid crystal image display device uses a lens array as superimposing means for superimposing and illuminating a liquid crystal light valve.

  As shown in FIG. 15A, the liquid crystal image display device includes a light source 111, a reflector 112 that reflects light emitted from the light source 111 in the direction of the optical axis L0, and a first lens array (fly-eye lens) 113. And a second lens array (fly eye lens) 114, a superimposing 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 lens cells having openings substantially similar to the liquid crystal light valve 118 are two-dimensionally arranged, and the exit opening surface of the reflector 112 is spatially divided. is doing.

  Each lens cell of the first lens array 113 collects the light flux on the lens cell of the second lens array 114 corresponding to each lens cell. The same number of secondary light source images as the lens cells of the first lens array 113 are formed on the second lens array 114. On the other hand, each lens cell on the second lens array 114 causes the image of each lens cell opening of the corresponding first lens array 113 to coincide with the incident surface of the liquid crystal light valve 118, and the overlapping lens 116 and the condenser lens. Through 117 and the polarizing beam splitter 119, the images of the 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 overlapping lens 116.

  The condenser lens 117 is arranged so that the illumination light of the liquid crystal light valve 118 is incident in the entrance pupil direction of a 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 superimposing means.

  The liquid crystal light valve 118 includes 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 liquid crystal plate is controlled by an electric signal, so that the transmitted or reflected light is polarized and modulated. That is, the illumination light is modulated into P-polarized light and S-polarized light according to image information in the liquid crystal light valve 118.

  By the way, 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 polarizing beam splitter 119 has a polarization direction after passing through the polarizing beam splitter 119 is a liquid crystal light valve. The optimum direction at 118 is deviated. Therefore, by arranging a λ / 4 plate (quarter wavelength plate) (not shown) between the polarizing beam splitter 119 and the liquid crystal light valve 118, an optimum polarization direction with respect to the liquid crystal light valve 118 is obtained. Compensation.

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

  This liquid crystal image display device projects and displays the information of the liquid crystal light valve in 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) in place of the lens array described above as 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 that reflects light emitted from the light source 111 in the direction of the optical axis L0, a glass rod 121 as a rod integrator, an exit lens 122, an overlapping lens 116, a condenser A lens 117 and a liquid crystal light valve 118 are provided.

  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. The light incident on the incident surface of the glass rod 121 is superimposed by repeating total reflection in the glass rod 121 and has a uniform distribution in the emitted light. The outgoing lens 122 into which the outgoing light from the glass rod 121 is incident condenses the outgoing light from the glass rod 121 on the overlapping lens 116. A plurality of tertiary light source images corresponding to the number of reflections in the glass rod 121 are formed by the overlapping lens 122.

  Thus, the glass rod 121, the exit lens 122, and the superimposing lens 116 constitute superimposing means for superimposing and illuminating 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 that has returned to the polarizing beam splitter 119 via the liquid crystal light valve 118 is incident on the optical path returning to the glass rod 121 side and the projection lens in the polarizing beam splitter 119 according to the polarization direction. The light path is separated.

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

  The liquid crystal image display device shown in FIG. 15 is for monochrome display. In the liquid crystal image display device for color display, the light from the superimposing means is decomposed into RGB (three primary colors), the RGB light is modulated by the corresponding liquid crystal light valve, and the RGB light is synthesized and projected.

  In such a color liquid crystal image display device, it is necessary to perform color balance (white balance) adjustment for adjusting the proportion 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 in accordance with the magnitude of an electric signal applied to the liquid crystal light valve.

  For example, when the color temperature is set high, the electrical signal of RG is reduced to suppress the modulation amount of the liquid crystal of RG so that the amount of light of RG is relatively small with respect to B. Further, when the color temperature is set low, the electrical signal of the BG is reduced to suppress the modulation amount of the liquid crystal of the BG so that the amount of light of the BG is relatively small with respect to R.

On the other hand, in a conventional liquid crystal image display device, downsizing of the device and higher brightness of a projected image are required. For this reason, in the liquid crystal image display device, since the liquid crystal light valve is illuminated with a wider range of light by a short optical path, the diameter of the light beam that illuminates 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 2000-137289 A JP 2001-33773 A

  By the way, in the liquid crystal image display device that enlarges and projects the information of the light valve by the superimposing means as described above, if the RGB color balance is adjusted with an electric signal, there is a problem that the contrast is lowered.

  Furthermore, even when the illumination optical system has a low F value, there is a problem that the leakage light of the liquid crystal light valve increases during black information display and the contrast is lowered.

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

  C in FIG. 16 is a light output L when black information is displayed when the input signal S is smaller than a predetermined value. Originally, the optical output L is ideally zero level, but 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 118. . On the other hand, when the input signal S reaches a peak, the optical 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 leaked light increases due to the low F value, the contrast ratio CR decreases.

  By the way, if the light output L is suppressed to adjust the signal to an A ′ level light output in order to balance the color, the contrast ratio CR ′ = A ′ / C is obtained, which causes a significant deterioration in contrast.

  Here, the incident angle characteristic of the transmittance of the polarizing beam splitter will be examined.

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

  As shown in FIG. 17A, the angle formed between the incident light and the optical axis is defined as an incident angle β with respect to the polarization beam splitter installed so that the incident surface is perpendicular to the optical axis.

  Polygonal lines a to e shown in FIG. 17B indicate the P-polarized light transmittance of the polarizing beam splitter with respect to light rays having an incident angle βc <βb <βa = 0 <βd <βe. Thus, when the incident angle deviates 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 component and the reflected P-polarized component become leakage light, which increases the C level in FIG. 17 and causes a decrease in contrast.

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

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

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

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

  As described above, the λ / 4 plate has a dispersion characteristic, and has an optimum characteristic for incident light of a single wavelength. All of the bands do not have optimal characteristics. As the incident light with respect to the λ / 4 plate deviates from the optimum wavelength, the compensation capability of the polarization direction deteriorates, and a component that cannot be compensated is generated. The component that could not compensate the polarization direction becomes leaked light, which increases the C level in FIG. 16 and causes a decrease in contrast.

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

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

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

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

  When forming a filter or a light-shielding film on the outer peripheral portion of the optical component 123 such as a lens array by vapor deposition, as shown in FIG. 19A, so that the vapor deposition film does not extend outside a desired region of the optical component 123, When applying an AR (Antireflection) coat, an annular mask A is used.

  As shown in FIG. 19B, when a filter or a light-shielding film is formed on the outer peripheral portion 127, a circular mask 129 is required as shown in FIG. However, the mask 129 needs to be positioned on the inner peripheral portion of the optical component 123, but cannot be held at this position. In practice, a filter film having such a shape is formed by vapor deposition. I can't.

  On the other hand, as described above, the optical component that causes the contrast deterioration is different between the vertical angular deviation component and the horizontal angular deviation component in the illumination optical system, so that the entire outer periphery of the illumination optical system is shielded. It's not always necessary to do that.

  The present invention has been proposed in view of the above-described circumstances, and in the adjustment of color balance, the deterioration of contrast is effectively prevented by increasing the F value of the illumination optical system for the color to be adjusted. An object of the present invention is 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 adjusting the color balance, and more effective contrast degradation. An object of the present invention is to provide an image display device capable of preventing the above-described problem.

In order to solve the above-described problem, an image display device according to the present invention includes a white light source and a superimposition that splits the light emitted from the white light source into a plurality of partial lights and superimposes the plurality of the divided partial lights. Means, corresponding to the three primary colors, light-modulating incident light and emitting the modulated light as modulated light, and separating the light superimposed by the superimposing means into the three primary colors. supplies the respective spatial light modulator as a light, a position between the separating and synthesizing means for synthesizing the modulated light from each of the spatial light modulator, and said separating and combining means and the superimposing means, input morphism Orthogonal to the optical axis that is arranged at two predetermined distances across the optical axis of the light to be emitted, attenuates the light intensity in an arbitrary wavelength band of the incident light, and adjusts the ratio of the three primary colors. and two optical attenuating means arranged in a direction, the decomposition Comprising a projection means for projecting the light passing through the forming means.

The decomposing / combining means has a plurality of polarizing beam splitters, and the polarizing beam splitter disposed at a position where the light from the superimposing means in the decomposing / combining means is incident is a polarization direction of the incident light. It is preferable that the light is transmitted according to the light intensity and reflected in the direction orthogonal to the optical axis of the incident light.

  In this image display device, light in a wavelength region whose level is lowered by a filter is blocked by a filter for light beams far from the optical axis among light beams incident on the liquid crystal light valve. Thus, in this image display device, since the light incident on the liquid crystal light valve is optically controlled, it is not necessary to control the light amount of the modulated light by electrically controlling the liquid crystal light valve. For this reason, the amount of light at the time of black information display of the liquid crystal light valve is also relatively reduced, so that even if the color balance (white balance) is adjusted, the contrast of the displayed image does not decrease.

  Further, in this image display device, the wavelength range where the level is lowered is cut off for the light beam far from the optical axis. Therefore, the F system of the illumination optical system can be increased by reducing the substantial light flux system. That is, since the angle of light incident on the liquid crystal light valve that modulates light can be reduced, leakage light reaching the liquid crystal light valve can be reduced during black information display. Therefore, the level of output light at the time of displaying black information can be reduced and the contrast can be improved.

  In addition, it is preferable that a filter adjusts a color balance by controlling the light supplied from the superimposing means.

  According to the present invention, in color balance adjustment in an image display apparatus, contrast deterioration 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 the filter in the illumination optical system in the image display device, thereby increasing the F value of the illumination optical system for the color to be adjusted in the adjustment of the color balance, and is more effective. Prevention of contrast degradation can be realized.

  Embodiments of an image display apparatus according to the present invention will be described below 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.

  For the sake of simplicity, 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. This figure is shown for explaining the principle of the present invention. In a liquid crystal image display device for color display that requires adjustment of color balance (white balance), color separation optics for separating / combining light into RGB System and a color synthesis optical system.

  FIG. 1A shows a lens array type liquid crystal image display device.

  The liquid crystal image display device includes 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 with the optical axis L0 as an axis, reflects the light emitted from the light source 11 by the reflecting surface, and emits it as a light beam parallel to the optical axis L0.

  In addition, the liquid crystal image display device includes a first lens array (fly eye lens) 13, a second lens array (fly eye lens) 14, a filter 15, an overlay 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 reflector 12 spatially divides the aperture from which the light beam is emitted. .

  The first lens array 13 condenses the light fluxes on the lens cells of the second lens array 14 corresponding to the lens cells, respectively, and the same number as the lens cells of the first lens array 13 on the second lens array 14. The secondary light source image is formed.

  The second lens array 14 makes the lens cell opening of the corresponding first lens array 13 coincide with the surface of the liquid crystal light valve 18 for each lens cell, and each lens cell of the first lens array 13 is a liquid crystal light valve. Overlap on 18 sides.

  The filter 15 blocks the wavelength region in which the level of the light beam far from the optical axis L0 from among the light beams transmitted through the first and second lens arrays 13 and 14 is reduced, and transmits the remaining light beam as it is.

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

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

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

  In this liquid crystal image display device, a plurality of secondary light source images in the second lens array 14 are formed. In addition, a plurality of tertiary light source images are formed in the overlapping lens 16. Then, the liquid crystal bulb 18 is superimposed and illuminated using this tertiary light source image. In the liquid crystal image display device, the superimposing means for performing the superimposing 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 overlapping 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 region, and the remaining light beam is transmitted as it is.

  Here, the filter 15 blocks the desired wavelength range in order from the light beam far from the optical axis. As a result, the diameter of the light beam transmitted through the filter 15 is substantially reduced. In other words, the filter 15 reduces the diameter of the light beam only in the desired wavelength range, but the light diameter outside the light beam is reduced even in the entire light beam including each wavelength range, 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.

  Thus, since the diameter of the light beam is substantially reduced by the filter 15, light that is far from the optical axis L0 and enters the liquid crystal light valve 18 at a large angle is also reduced. Accordingly, as will be described later, leakage light at the time of displaying black information by the liquid crystal light valve 18 is also reduced.

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

  Although the example in which the filter 15 is provided between the second lens array 14 and the overlapping lens 16 is shown in the figure, the filter 15 may be installed 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 exit lens 22 in place of the first and second lens arrays 13 and 14. The difference is that the filter 15 is placed behind the overlapping lens 16. Parts 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 by the reflection surface of the spheroid and condenses the light on the incident surface of the glass rod 21.

  The glass rod 21 totally reflects light incident from the reflector 12 multiple times on the inner surface. The exit 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 exit surface of the glass rod 21. In addition, a plurality of tertiary light source images are formed on the overlapping lens 16. The number of these secondary light source images and tertiary light source images corresponds to the number of times the light is totally reflected in the glass rod 21.

  The filter 15 is installed at the rear stage of the superimposing lens 16 on which the 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 region, and the remaining light beam is transmitted as it is. As in the case of the lens array system shown in FIG. 1 (a), an R transmission filter is shown. For the rays a, b, e, and f, only R light is used, and for the rays c and d, R + G + B white light is used. is there.

  As described above, in the liquid crystal image display device shown in FIG. 1, portions related to the color separation optical system and the color synthesis optical system are omitted for the sake of simplicity. In practice, a liquid crystal light valve for modulating RGB light is provided. In addition, a color separation optical system for separating light into RGB is installed in the front stage of these liquid crystal light valves, and a color synthesis optical system for synthesizing RGB light is installed in the rear stage of the liquid crystal light valve. The projection lens projects the light synthesized by this color synthesis optical system.

  FIG. 2 is a perspective view showing the 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 length and width, and can control the transmission of light for each element. That is, for each element, it is possible to switch between a state of blocking light in a wavelength range that drops the level and a state of transmitting light as it is.

  For example, as shown in FIG. 2 (a), light is left as it is for the remaining elements 31b in the central two rows in a state in which the wavelength regions whose levels are lowered for the two elements 31a from the rightmost column and the leftmost column are cut off. It is possible to control the transmission state.

  In this way, the light in the wavelength region whose level is lowered is blocked in order from the element away from the optical axis L0 of the lens so as to be symmetric with respect to one straight line perpendicular to the optical axis passing through the center of the filter 31. The element can be controlled to transmit light as it is.

  Further, for example, as shown in FIG. 2B, the light in the wavelength region that drops the level of the element 31c around the array is blocked and the light of the remaining four elements 31d in the center is transmitted as it is. Can be controlled.

  In this way, 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 lowered in order from the surrounding elements, and allow the remaining elements to pass through as they are.

  In this embodiment, in both FIGS. 2A and 2B, the central element near the optical axis L0 is controlled to transmit light as it is. Therefore, since the substantial diameter of the light beam that illuminates the liquid crystal light valve 18 is reduced, the F value is increased. Further, it is possible to suppress the light incident on the liquid crystal lie valve 18 at a large angle.

  Here, when the 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. As described above, by associating the arrangement of the lens cells with the elements of the filter 31 and the lens array, it is possible to suppress color unevenness resulting from the mismatch of these arrays.

  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 reflective liquid crystal plate 41 is used, but the relationship between the F value, the incident angle, and the leakage light is the same when the transmissive liquid crystal plate is used.

  FIG. 3A shows a state where 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 shielded by the analyzer 42 without being modulated because the major axis direction of the liquid crystal molecules is aligned with the direction of the light L1.

  FIG. 3B shows a state where light L1 ′ having a large angle (low F value) with respect to the liquid crystal plate 41 passes. In this case, although the major axis of the liquid crystal is aligned in a direction perpendicular to the liquid crystal plate 41, the light L1 ′ is slightly modulated because it is incident on the liquid crystal molecules at a large angle. Therefore, the amount of light that has been modulated passes through the analyzer 42 and becomes leaked light. If there is such leakage light, the light output during black information display will be raised.

  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 where the incident angles are orthogonal or small. That is, in the present embodiment, there is little leakage light, and the light output when displaying black information is small.

  FIG. 4 is a diagram showing the relationship between the input signal and the optical output in the liquid crystal image display device of the present embodiment.

  In the figure, C is the light output L when black information is displayed when the input signal S is smaller than a predetermined value. The light output L in this case is ideally zero level, but 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. The 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 optical 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, in order to adjust the color balance (white balance), if the light output L is suppressed and the signal is adjusted to the A ′ level light output, the leakage light at the time of displaying the black information is also reduced to the C ′ level. This is because, in the present embodiment, the color balance is adjusted by optically limiting the amount of light that passes through the filter. For this reason, the leakage light C ′ at the time of black information display 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 leaked 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 light output at the peak level is adjusted to decrease to 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.

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

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

  The infrared light / ultraviolet light cut filter 54 blocks the infrared light and ultraviolet light unnecessary for image display, thereby preventing heat generation in the optical system at the subsequent stage.

  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 the light beam far from the optical axis to block the wavelength region that drops the level, and transmits the light beam close to the optical axis as it is. And the color balance (white balance) of this liquid crystal image display apparatus is adjusted by restrict | limiting the quantity of the light beam restrict | limited to the said wavelength range.

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

  The condenser lens 60 is configured so that the illumination light of the liquid crystal light valve is incident in the direction of the entrance pupil of the projection lens.

  The polarizer 61 limits so that only S-polarized light is transmitted.

  The 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 the respective colors, and RGB modulated by these 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, the specific configuration is not shown. 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 the respective colors is shown.

  The analyzer (polarizing plate) 66 transmits only the P-polarized light. Therefore, light that is 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 2.4, for example. In this case, the incident angle to the reflective liquid crystal light modulation element is 11.8 degrees at the maximum. Here, for example, if the B-color light is to be reduced by 50%, the F number is changed from 2.4 to 3.4. The incident angle at this time is a maximum of 8.4 degrees.

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

  In the illumination optical system according to the second embodiment, the polarization beam splitter 19 is disposed between the condenser lens 17 and the liquid crystal light valve 18, and the configuration is the same as in the first embodiment described above. It is.

  Illumination light for the liquid crystal light valve 18 is modulated into P-polarized light and S-polarized light according to image information in the liquid crystal light valve 18 and returns to the polarizing beam splitter 19, and the polarizing beam splitter 19 responds to the polarization direction. The optical path returning to the first and second lens arrays 13 and 14 and the optical path incident on the projection lens are separated. And only the light of the polarization direction corresponding to the white information of 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 polarizing beam splitter 19 is polarized after passing through the polarizing beam splitter 19. Since the direction deviates from the optimum direction in the liquid crystal light valve 18, by arranging a not-shown λ / 4 plate (quarter wavelength plate) between the polarization beam splitter 19 and the liquid crystal light valve 18, The liquid crystal light valve 18 is compensated so as to have an optimum polarization direction.

  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 dropped is covered corresponding to the opening of the lens array 14 corresponding to the level to be dropped. Are arranged as follows.

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

  Thereby, in the relationship of the optical output with respect to the input signal shown in FIG. 4, even if the optical output is changed from A to A ′, C becomes C ′ at the same ratio, and the contrast is not deteriorated. Further, the GB color does not have a component with a strong angle with respect to the polarizing film surface of the polarizing beam splitter 19, that is, the F value increases, 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 is the same as the configuration in the first embodiment described above except that a polarizing beam splitter 19 is disposed between the condenser lens 17 and the liquid crystal light valve 18.

  Illumination light for the liquid crystal light valve 18 is modulated into P-polarized light and S-polarized light according to image information in the liquid crystal light valve 18 and returns to the polarizing beam splitter 19, and the polarizing beam splitter 19 responds to the polarization direction. The optical path returning to the glass rod 21 side and the optical path incident on the projection lens are separated. And only the light of the polarization direction corresponding to the white information of image information is projected as an image.

  Also 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 polarizing beam splitter 19 is polarized after passing through the polarizing beam splitter 19. Since the direction deviates from the optimum direction in the liquid crystal light valve 18, by arranging a not-shown λ / 4 plate (quarter wavelength plate) between the polarization beam splitter 19 and the liquid crystal light valve 18, The liquid crystal light valve 18 is compensated so as to have an optimum polarization direction.

  After the relay lens 16 on which the tertiary light source image of the light source is formed, a filter 15 for cutting a color whose level is to be dropped is arranged so as to cover an area corresponding to the level to be dropped. For example, when an R transmission filter is disposed, light rays a, b, e, and f are only R light, c and d are R + G + B white light, and illumination light superimposed on the liquid crystal light valve 18 is G And B components are reduced, and the light has 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 outgoing (reflective) optical axis of the polarizing beam splitter 19. So that the directions are perpendicular to each other. Alternatively, as shown in FIG. 8B, the filter 15 has an inner edge (optical axis side) edge A with respect to a plane including the incident optical axis and the outgoing (reflective) optical axis of the polarizing beam splitter. So that they are parallel to each other.

  That is, when there is a lot of leakage light due to the inclination of the incident angle of the light beam incident on the polarization beam splitter 19, the edge A on the inner side (optical axis side) of the filter 15 is polarized as shown in FIG. The beam splitter 19 is disposed so as to be orthogonal to a plane including the incident optical axis and the outgoing (reflecting) optical axis.

  Further, when there is a large amount of leaked light due to the deterioration of the polarization direction compensation ability due to the dispersion characteristic of the λ / 4 plate, as shown in FIG. 8B, the inner edge (optical axis side) of the filter 15 is shown. A is arranged so as to be parallel to a plane including the incident optical axis and the outgoing (reflecting) optical axis of the polarizing beam splitter.

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

  The filter 15 may be formed by directly depositing on the second lens array 14 as shown in FIGS.

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

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

  In the illumination optical system according to the third embodiment, the overall configuration 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, the filter 15 for cutting the color whose level is to be dropped corresponds to the opening of the lens array corresponding to the level to be dropped. And formed so as to cover. At this time, light rays a, b, e, and f are only R light, c and d are R + G + B white light, and G and B components are reduced in the light superimposed on the liquid crystal light valve 18. , Light with low color temperature.

  Thereby, in the relationship of the optical output with respect to the input signal shown in FIG. 4, even if the optical output is changed from A to A ′, C becomes C ′ at the same ratio, and the contrast is not deteriorated. Further, the GB color does not have a component with a strong angle with respect to the polarizing film surface of the polarizing beam splitter 19, that is, the F value increases, so that the contrast is improved as described with reference to FIG.

  FIG. 11 is a side view showing a third embodiment of a 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 overall configuration as that of the second embodiment described above 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 that cuts a color whose level is to be dropped is formed on the exit surface side of the relay lens 16 where the tertiary light source image of the light source 11 is formed so as to cover an area corresponding to the level to be dropped. For example, when an R transmission filter is disposed, light rays a, b, e, and f are only R light, c and d are R + G + B white light, and light superimposed on the liquid crystal light valve 18 is G and The B component is reduced, and the light has a low color temperature.

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

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

  Here, whether the region without the filter 15 is provided in the vertical direction as shown in FIG. 12 (a) or in the horizontal direction as shown in FIG. 12 (b) depends on the polarization beam splitter and λ / It differs depending on the 4-wavelength plate, and is provided on the side where the contrast is higher.

  That is, when there is a large amount of leakage light due to the inclination of the incident angle of the light beam incident on the polarization beam splitter 19, the region of the filter 15 is defined as the incident optical axis of the polarization beam splitter 19 as shown in FIG. It forms so that it may become the direction (up-down direction in FIG. 12) arranged in the direction parallel to the plane containing an output (reflection) optical axis.

  Also, when there is a lot of leakage light due to the deterioration of the polarization direction compensation ability due to the dispersion characteristic of the λ / 4 plate, the region of the filter 15 is moved to the polarization beam splitter 19 as shown in FIG. It forms so that it may become the direction (left-right direction in FIG. 12) arranged in the direction orthogonal to the plane containing an incident optical axis and an output (reflection) optical axis.

  Further, as shown in FIG. 12, the filter 15 is formed in a region in which the cell of the second lens array 14 is a unit, and the transmitted light amount of the filter 15 and the contrast of the display image are most balanced. The shape can be optimized.

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

[Fourth Embodiment]
FIG. 13 shows an embodiment when 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 that cuts the color whose level is to be dropped is covered with the number of openings of the lens array corresponding to the level to be dropped. For example, when the R transmission filter 15 and the RG transmission filter 25 are arranged, the light beams a and f are only R light, b and e are R + G light, and c and d are R + G + B white (white) light. The superimposed light is reduced in GB component and becomes light with a low color temperature. As a result, 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 rate, and the contrast is not deteriorated. At the same time, the GB light has no component with a strong angle with respect to the film surface of the polarizing beam splitter 19 (F value is increased), and the contrast is improved.

  FIG. 14 shows an example of the structure when the filter and the 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. The second filter is vapor-deposited on the second lens array, but this may be attached to a light shielding plate, or both the first and second filters may be vapor-deposited on the second lens array. The adhesive that bonds the light shielding plate and the first filter has heat resistance of 200 ° C. or higher. Further, the filter attached to the light shielding plate has a structure in which the light shielding plate and the lens array fixing member are integrated to reduce the number of components.

  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 can be made without departing from the present invention.

It is a side view which shows the structure of the liquid crystal image display apparatus of embodiment of this invention. It is a perspective view which shows a filter. It is sectional drawing which shows the relationship between F value and the leak light of a liquid crystal light valve. It is a graph which shows the relationship between the input signal and optical output in the liquid crystal image display apparatus of this Embodiment. It is a side view which shows more concretely the structure of the liquid crystal image display apparatus of this Embodiment. It is a side view which shows 2nd Embodiment of the liquid crystal image display apparatus which concerns on this invention using the illumination optical system of a lens array system. It is a side view which shows 2nd Embodiment of the liquid crystal image display apparatus which concerns on this invention using the illumination optical system of a rod integrator system. In the said 2nd Embodiment, it is a perspective view which shows the example of the direction which inserts a filter. In the said 2nd Embodiment, it is a perspective view which shows the example which formed the filter by vapor deposition. It is a side view which shows 3rd Embodiment of the liquid crystal image display apparatus which concerns on this invention using the illumination optical system of a lens array system. It is a side view which shows 3rd Embodiment of the liquid crystal image display apparatus which concerns on this invention using the illumination optical system of a rod integrator system. In the said 3rd Embodiment, it is a perspective view which shows the example which formed the filter by vapor deposition. It is a figure which shows embodiment 4th. It is a figure which shows the example of a structure at the time of integrating a filter and a light-shielding plate. It is a figure which shows schematic structure of a liquid crystal image display apparatus. It is a figure which shows the relationship between the input signal and light output in a liquid crystal image display apparatus. It is a graph which shows the incident angle characteristic of the transmittance | permeability of a polarizing beam splitter. It is a graph which shows the dispersion characteristic of (lambda) / 4 board. 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 symbols

DESCRIPTION OF SYMBOLS 11 Light source 12 Reflector 13 1st lens array 14 2nd lens array 15 Filter 16 Relay lens 17 Condenser lens 18 Liquid crystal light valve 19 Polarizing beam splitter 21 Glass rod 22 Outgoing lens

Claims (2)

A white light source,
Superimposing means for dispersing the light emitted from the white light source into a plurality of partial lights and superimposing the plurality of the divided partial lights;
Three reflective spatial light modulators that correspond to the three primary colors and that modulate the incident light and emit it as modulated light;
The light superimposed by the superimposing means is divided into three primary colors, supplied to the spatial light modulation elements as light of the three primary colors, and the decomposing / synthesizing means for synthesizing the modulated light from the respective spatial light modulation elements;
A position between said separating and combining means and the superimposing means, disposed in two locations at a predetermined distance across the optical axis of the incoming morphism light, the light intensity of an arbitrary wavelength band of the incident light Two light attenuating means arranged in a direction orthogonal to the optical axis to be emitted by adjusting the ratio of the three primary colors
Projecting means for projecting light that has passed through the decomposing and synthesizing means;
An image display device comprising: The resolving and combining means has a plurality of polarization beam splitters,
The polarizing beam splitter disposed at the position where the light from the superimposing unit in the decomposing / synthesizing unit is incident transmits the incident light according to the polarization direction of the incident light, and is on the optical axis of the incident light. 2. The image display device according to claim 1, wherein the image display device reflects in a direction orthogonal to the direction.

Images