JP2006113093A - Projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high luminance projector capable of adjusting light quantity difference for every wavelength band due to characteristics of a light source without using a special projection lens and causing a color shift and the like and obtaining a satisfactory white balance. <P>SOLUTION: In the modulation of an optical modulator 50, a light quantity is reduced and contrast is increased about green light GL by using a vertical type liquid crystal panel and a light quantity is secured about red light RL and blue light BL by using a parallel type liquid crystal panel. The aiming projector can be provided. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a projector that has a plurality of light modulation devices and synthesizes and projects modulated light from each of the light modulation devices.

  In a projector using a liquid crystal panel, when a high-pressure mercury lamp, a metal halide lamp, or the like is used as a light source, the amount of light varies depending on the wavelength band due to the wavelength distribution characteristics of the light generated by the light source. For example, when light from a high-pressure mercury lamp is separated into three colors of red, green, and blue, the amount of red light and blue light is less than that of green light. As a technique for supplementing this, for example, at least one of the liquid crystal panels on the optical path of the three color lights is provided with a microlens array, and the use efficiency of green light is enhanced ( Patent Document 1). As another technique for obtaining the same effect, a technique using a panel having a different aperture ratio is also known (Patent Document 2).

On the other hand, as a technology different from these, it is common to use a TN type liquid crystal panel which is a parallel alignment type for a projector. However, by using a vertical alignment liquid crystal for the projector liquid crystal panel, the contrast is improved. Is known (for example, Patent Document 3).
JP 2003-241304 A JP 2003-5167 A Japanese Patent Laid-Open No. Hei 6-273772

  However, when a microlens is used, the light emitted from the liquid crystal panel spreads, and it is necessary to use a projection lens with a large aperture corresponding to the microlens, which may increase the size and cost of the apparatus. In addition, when liquid crystal panels having different aperture ratios are used, there is a problem that color misregistration or color blur occurs due to a difference in the size or shape of the opening, making it difficult to match the images. In addition, when the vertically aligned liquid crystal is used, the contrast of the image is improved, but the brightness tends to be insufficient.

  Therefore, the present invention can adjust the light amount difference for each wavelength band according to the characteristics of the light source without using a special projection lens or causing color misregistration, and enables better white balance. An object is to provide a projector with high brightness.

  In order to solve the above problems, a projector according to the present invention includes a plurality of liquid crystal panels that respectively modulate a plurality of color lights, a color synthesis optical system that combines light modulated by the plurality of liquid crystal panels, and a color synthesis optical system. And a projection type optical system for projecting light synthesized by the liquid crystal panel, wherein a liquid crystal panel that modulates at least one color light among a plurality of color lights has a pair of substrates and a liquid crystal vertically aligned between the substrates A liquid crystal panel, wherein the liquid crystal panel that modulates the remaining color light among a plurality of color lights is a parallel type liquid crystal panel having a pair of substrates and a liquid crystal aligned in parallel between the substrates. Here, the vertical alignment means a state in which the liquid crystal alignment vector is aligned perpendicularly to the substrate surface or slightly tilted (with a pretilt) from the substrate normal direction when no voltage is applied to the liquid crystal. Means. Further, the parallel alignment means a state in which the liquid crystal alignment vector is aligned parallel to the substrate surface or slightly tilted (with a pretilt) when no voltage is applied to the liquid crystal.

  In general, a vertical liquid crystal panel is excellent in contrast, although its light transmission characteristics are slightly inferior. On the other hand, the parallel-type liquid crystal panel is bright because it has excellent light transmission characteristics although it is slightly inferior in contrast. In order to utilize both of these properties, a vertical liquid crystal panel having liquid crystal vertically aligned between the substrates is used for at least one color light among the respective color lights, and parallel alignment is performed between the substrates for the other color lights. Each image light is formed using a parallel type liquid crystal panel having liquid crystal. As a result, the at least one color light can be modulated utilizing the characteristics of the vertical liquid crystal panel, and the other color lights can be modulated utilizing the characteristics of the parallel liquid crystal panel. Each formed image light is combined by a color combining optical system, and projected by a projection optical system, thereby forming an image.

  For example, it is inevitable that each color light used as illumination light in a projector normally has a deviation in light amount due to the characteristics of the light source. Further, depending on the application of the projector, there is a case where it is desired to emphasize or suppress the expression by a specific color light. The enhancement of expression by colored light is achieved, for example, by increasing the brightness and contrast of the color. In the projector of the present invention, as described above, the parallel alignment and the vertical alignment are selectively used depending on the color light, so that the projected image can be adapted to the image projection application.

  As a specific aspect of the present invention, a vertical liquid crystal panel is used for color light having a relatively large light amount among the plurality of color lights. In this case, the light amount difference between the respective color lights after the synthesis of the plurality of color lights is reduced, and the synthesized light for image formation with a relatively white balance can be obtained.

  As a specific aspect of the present invention, a vertical liquid crystal panel is used for color light requiring high contrast among the plurality of color lights. In this case, the contrast can be increased with respect to the target color light, and an image can be formed with a high contrast ratio as a whole.

  As a specific embodiment of the present invention, the parallel liquid crystal panel is a twisted nematic (TN) liquid crystal panel. In this case, bright modulated light can be obtained from the color light by an inexpensive device.

  As a specific aspect of the present invention, the projector further includes a light source and a color separation optical system that separates light emitted from the light source into the plurality of color lights. In this case, separated light separated for each specific wavelength band from a single light source such as a lamp having a predetermined spectral distribution can be obtained as colored light of each color.

  As a specific aspect of the present invention, the light source is either a high-pressure mercury lamp or a metal halide lamp, the plurality of color lights include three color lights of red light, blue light, and green light, and the green light is vertical type. While being modulated using a liquid crystal panel, blue light and red light are modulated using a parallel liquid crystal panel. In this case, the vertical liquid crystal panel increases the contrast ratio of green light, which has a relatively large amount of light, and the parallel liquid crystal panel ensures a sufficient amount of blue light and red light. Can be set.

  As a specific aspect of the present invention, the light source is either a high-pressure mercury lamp or a metal halide lamp, and the plurality of color lights includes three color lights of red light, blue light, and green light, and green light and blue light. Is modulated using a vertical liquid crystal panel, and red light is modulated using the parallel liquid crystal panel. In this case, the vertical liquid crystal panel increases the contrast ratio of green light and blue light, which has a relatively large amount of light, and the parallel liquid crystal panel ensures a sufficient amount of red light, so that there is no wasteful white according to the application. Balance can be set.

  As a specific aspect of the present invention, the light source is a halogen lamp, the plurality of color lights include three color lights of red light, blue light, and green light, and the red light having a relatively large amount of light is a vertical liquid crystal panel. The green light and the blue light are modulated using a parallel liquid crystal panel. In this case, the vertical liquid crystal panel enhances the contrast ratio of red light, and the parallel liquid crystal panel ensures a sufficient amount of green light and blue light, making it possible to set a lean white balance according to the application. Become.

  Further, as a specific aspect of the present invention, the light source is a halogen lamp, the plurality of color lights include three color lights of red light, blue light, and green light, and the red light and green light having a relatively large amount of light are vertical. The blue light is modulated using a parallel liquid crystal panel. In this case, the vertical liquid crystal panel increases the contrast ratio of green light as well as red light, and the parallel liquid crystal panel ensures a sufficient amount of blue light, allowing you to set a lean white balance according to the application. It becomes.

  Moreover, as a specific aspect of the present invention, the plurality of color lights are four color lights. In this case, a more expressive color image is formed by using four color lights.

  Further, as a specific aspect of the present invention, the four color lights are obtained by adding one color light to the three color lights of red light, blue light, and green light. In this case, it is possible to set the white balance and the like according to the application by adjusting the relative specific gravity of the light quantity and contrast for the three color lights and further adjusting the relative specific gravity of the light quantity and contrast for one color light. At the same time, by using four color lights, a more expressive color image is formed.

  As a more specific aspect of the present invention, four color lights are obtained by adding yellow light to the above three color lights. In this case, it is possible to set a white balance or the like according to the application by adjusting the light amount and contrast of yellow light.

  As a specific aspect of the present invention, the plurality of color lights are two color lights. In this case, a color image can be formed.

  As a more specific aspect of the present invention, the two color lights are achromatic color light and chromatic color light, and the color light requiring the high contrast is achromatic color light. In this case, it is possible to form a color image with particularly good contrast.

  As a more specific aspect of the present invention, the light source is either a high-pressure mercury lamp or a metal halide lamp, one of the two colored lights is green light, and the green light is colored light having a relatively large light amount. is there. In this case, it is possible to obtain combined light for image formation with white balance.

  As a specific aspect of the present invention, the vertical liquid crystal panel operates in a normally black mode, and the parallel liquid crystal panel operates in a normally white mode. Here, the normally black mode means a display mode in which a black display is obtained by setting a light blocking state when no voltage is applied to the liquid crystal, and the normally white mode means that no voltage is applied to the liquid crystal. In this case, the light transmission state means a display mode in which white display is performed when white light is incident. In this case, it is possible to effectively increase the contrast ratio by operating the vertical liquid crystal panel in the normally black mode, and the transmittance, that is, the brightness of the image, by operating the parallel liquid crystal panel in the normally white mode. It is possible to effectively increase the thickness.

[First Embodiment]
FIG. 1 is a diagram for explaining the projector according to the first embodiment. The projector 100 according to the present embodiment includes an illumination device 10, a light separation optical system 30, a light modulation device 50, a cross dichroic prism 70 that is a light combining optical system, and a projection lens 90 that is a projection optical system.

  The illumination device 10 includes a light source 1 that is a source of the light source light WL, and an integrator optical system 20 that forms illumination light SL from the light source light WL. The integrator optical system 20 further includes fly lens arrays 2 and 3. , A polarization conversion element array 4, a superimposing lens 5, and a mirror 6. In the present embodiment, in particular, the light source 1 is a high-pressure mercury lamp. Thereby, it is possible to obtain the light source light WL having a light amount sufficient for forming the image light. The light source light WL has a wavelength distribution unique to the high-pressure mercury lamp. The fly lens arrays 2 and 3 and the superimposing lens 5 make the light source light WL uniform in the beam cross section. The polarization conversion element array 4 converts the light source light WL into predetermined polarized light and emits it. Further, the mirror 6 bends the optical path of the light source light WL by reflection. By these integrator optical systems 20, illumination light SL that is uniform polarized light is formed from the light source light WL.

  The light separation optical system 30 includes dichroic mirrors 31, 32, mirrors 33, 34, 35, relay lenses 36, 37, and field lenses 38, 39, 40 as a color separation optical system. Here, the dichroic mirrors 31 and 32 selectively separate or transmit the illumination light SL formed by the illumination device 10 to separate colors for each predetermined wavelength band, thereby forming colored light of each color. In particular, the dichroic mirror 31 has a characteristic of transmitting the components in the wavelength region including the red light RL while reflecting the other regions. Thereby, the red light RL is separated from the illumination light SL. The dichroic mirror 32 has a characteristic of reflecting the components in the wavelength region including the blue light BL while transmitting the other regions. Thereby, the blue light BL is separated from the remaining components of the illumination light SL, and the rest becomes the green light GL. The mirrors 33, 34, and 35 change the optical path of each color light in a predetermined direction by reflection. The relay lenses 36 and 37 correct the beam shape necessary for the optical path difference between the color lights, that is, the difference in the optical path length from the illumination device 10 to the liquid crystal light valves 51r, 51b, and 51g. The field lenses 38, 39, and 40 adjust the incident angle of each color light obtained by color separation of the illumination light to a polarizer that will be described later.

  The light modulation device 50 includes liquid crystal light valves 51r, 51b, and 51g. The liquid crystal light valves 51r, 51b, and 51g are polarizers 52r, 52b, and 52g, a vertical alignment liquid crystal panel 53g, and a TN alignment liquid crystal, respectively. Panels 53r, 53b and analyzers 54r, 54b, 54g are provided. The polarizers 52r, 52b, and 52g are respectively positioned on the incident side of the liquid crystal panel on the optical path, and are used to increase the degree of polarization by limiting the polarization direction of the incident light to the liquid crystal panels 53r, 53b, and 53g to a narrower range. It is a polarizing plate. Each of the liquid crystal panels 53r, 53b, and 53g forms modulated light by adjusting each incident color light to a polarization state for each pixel in accordance with a drive signal or image signal input as an electrical signal. The analyzers 54r, 54b, and 54g are polarizing plates for selecting a polarization component in a specific direction from the modulated light emitted from the liquid crystal panels 53r, 53b, and 53g.

  Here, the vertical alignment liquid crystal panel 53g is a vertical liquid crystal panel including a pair of substrates and liquid crystal vertically aligned between the substrates when no voltage is applied, and changes the polarization direction of incident light when no voltage is applied. Without passing through, the polarization direction of incident light is rotated by 90 ° when a voltage is applied. The vertical alignment liquid crystal panel 53g is slightly inferior in transmission characteristics but excellent in contrast. On the other hand, the TN alignment liquid crystal panels 53r and 53b are parallel type liquid crystal panels including a pair of substrates and liquid crystal aligned in parallel when no voltage is applied between the substrates, and the polarization direction of incident light is 90 ° when a voltage is applied. Rotate and pass as it is without changing the polarization direction of incident light when no voltage is applied. The TN alignment liquid crystal panels 53r and 53b are excellent in transmission characteristics. A more specific example of operation will be described. First, when the vertically aligned liquid crystal panel 53g is used in a normally black type mode, the liquid crystal is vertically aligned when no voltage is applied, and a black display that blocks light while maintaining the polarization state. Therefore, it is excellent in black reproduction stability. Further, the vertical alignment liquid crystal panel 53g has small wavelength dispersion and angle dependency, and is not easily affected by differences in color and angle. As a result, the contrast ratio can be effectively increased. On the other hand, when the TN alignment liquid crystal panels 53r and 53b are used in the normally white type mode, the liquid crystal is arranged in a twisted horizontal state when no voltage is applied, and the polarization state is rotated by 90 °, resulting in a white display that transmits light and becomes bright. Become. As a result, it is possible to effectively increase the transmittance while ensuring a certain degree of contrast.

  The cross dichroic prism 70 is a light combining optical system for combining image light obtained according to the modulated light emitted from the liquid crystal panels 53r, 53b, and 53g to form combined light.

  The projection lens 90 is a projection optical system for projecting the formed combined light as projection light onto a screen (not shown) or the like.

  Hereinafter, the function of the main image forming unit will be described with reference to FIG. In the illumination device 10, the emitted light source light WL generated from the light source 1 is first transmitted through the lens array 2. Thereafter, the light source light WL is reflected by the mirror 6 and further passes through the lens array 3. The lens arrays 2 and 3 make the light amount distribution of the light source light WL uniform in the light beam cross section. At this time, all the light included in the light source light WL is reflected by the mirror 6 to be redirected. The light source light WL is converted into one type of linearly polarized light by passing through the lens array 3 and then passing through the polarization conversion element array 4. Further, the light source light WL is superimposed by the superimposing lens 5 to form the illumination light SL.

  Next, in the light separation optical system 30, among the illumination light SL formed by the illumination device 10, first, the wavelength band including the red light RL as a main component is color-separated by the first dichroic mirror 31. Next, the remaining components of the illumination light SL are color-separated by the second dichroic mirror 32 into a wavelength band including the blue light BL as a main component and a wavelength band including the green light GL as a main component. The illumination light SL is separated into red light RL, green light GL, and blue light BL for each wavelength band by the function of each dichroic mirror described above. The red light RL is reflected by the mirror 33, and the incident angle is adjusted by the field lens 38. The red light RL is guided to the liquid crystal light valve 51r of the light modulator 50, and irradiates the liquid crystal light valve 51r. Similarly, after the blue light BL is extracted by reflection by the dichroic mirror 32, the incident angle is adjusted by the field lens 39, and the light is guided to the liquid crystal light valve 51b of the light modulation device 50 to irradiate the liquid crystal light valve 51b. The green light GL is extracted by transmission through the dichroic mirror 15 and then reflected by the mirrors 34 and 35. Further, the incident angle is adjusted by the field lens 40 and guided to the liquid crystal light valve 51r of the light modulator 50. The liquid crystal light valve 51r is irradiated. In the light separating optical system 30, the optical path of the green light GL is physically longer than the optical paths of other lights. Therefore, it is necessary to correct the beam shape, and relay lenses 36, 37, etc. are provided in the optical path of the green light GL for such correction.

  Next, in the light modulation device 50, the color lights RL, BL, and GL of the respective colors irradiated to the respective liquid crystal light valves 51r, 51b, and 51g are firstly polarizers 52r and 52b in the respective liquid crystal light valves 51r, 51b, and 51g. , 52g, the polarization direction of the incident light to the liquid crystal panels 53r, 53b, 53g is limited to a narrower range, and the degree of polarization is increased. Of each color light with an increased degree of polarization, the green light GL enters the vertical alignment liquid crystal panel 53g, and the red light RL and the blue light BL enter the TN alignment liquid crystal panels 53r and 53b, respectively. In each color light RL, BL, GL modulated by the liquid crystal panels 53r, 53b, 53g, a polarization component in a specific direction is further selected by the analyzers 54r, 54b, 54g. As described above, the image light of each color light RL, BL, GL is formed by each liquid crystal light valve 51r, 51b, 51g. At this time, the selection of the polarization component is determined by the relationship between the liquid crystal panels 53r, 53b, and 53g and the corresponding analyzers 54r, 54b, and 54g, thereby setting the normally black type mode and the normally white type mode. Is possible.

  Here, in the present embodiment, a high-pressure mercury lamp is used as the light source 1. In this case, due to the characteristics of the high-pressure mercury lamp, the amount of light in the wavelength band of the green light GL, among each color light, becomes relatively large. Therefore, in order to improve the white balance, it is desirable to relatively reduce the green light GL. Therefore, a vertically aligned liquid crystal panel 53g that operates in a normally black type mode that improves contrast although it is slightly inferior in transparency is used. As a result, the green light GL is automatically attenuated within a certain range and is also modulated into modulated light with high contrast. On the other hand, TN alignment liquid crystal panels 53r and 53b that operate in a normally white mode type with high transparency are used for red light RL and blue light BL, which have a smaller amount of light than green light GL. As a result, the red light RL and the blue light BL are modulated into modulated light with a sufficient amount of light secured.

  The image lights formed by the light modulation device 50 are combined with each other by the cross dichroic prism 70. The synthesized light thus formed is projected as projection light from the projection lens 90 onto a screen or the like, and a color synthesized image having a desired magnification is displayed on the screen.

  In summary, in the projector 100 of the present embodiment, the amount of green light GL out of the color lights RL, BL, and GL increases due to the characteristics of the high-pressure mercury lamp used as the light source 1. However, in the modulation by the light modulation device 50, the green light GL is dimmed by using the vertical alignment liquid crystal panel 53g and the contrast is increased, while the red light RL and the blue light BL are TN alignment liquid crystal panels 53r and 53b. The amount of light is secured by using. Accordingly, it is possible to provide a projector that obtains a better white balance by correcting a light amount difference for each wavelength band due to the characteristics of the light source 1 without using a special projection lens or causing a color shift or the like. It becomes possible.

  In the present embodiment, the light source 1 is a high-pressure mercury lamp, but the light source 1 is not limited to a high-pressure mercury lamp. For example, a metal halide lamp may be used. Also in this case, the amount of green light is the largest. Further, although the high-pressure mercury lamp and the metal halide lamp basically have a large amount of light in the order of green light, blue light, and red light, the spectral distribution differs slightly depending on the characteristics of each lamp used. The color temperature to be set varies depending on the usage application of the projector. For example, it is desirable that images for television are strong in red and blue, but images for theater are good in red. Therefore, depending on these situations, for example, a vertical liquid crystal panel may be used not only for green light but also for blue light. That is, the liquid crystal panel 53b may be a vertical liquid crystal panel.

  In the present embodiment, the vertical alignment liquid crystal panel 53g is used as a vertical liquid crystal panel on the color light reducing side, and the TN alignment liquid crystal panels 53r and 53b are used as parallel liquid crystal panels on the side that secures the amount of color light. However, by adopting a normally black type on the side that reduces the color light, and a normally white type on the side that secures the amount of color light, the white balance is not limited to this. It is expected to provide a projector that has obtained

[Second Embodiment]
The projector according to the second embodiment is obtained by modifying the projector according to the first embodiment shown in FIG. Hereinafter, the projector according to the second embodiment will be described. In the first embodiment, a high-pressure mercury lamp is used as the light source 1 and a metal halide lamp is exemplified, but a halogen lamp exhibiting a spectral distribution different from these can also be used as the light source. Hereinafter, the case where a halogen lamp is used as the light source 1 will be described in comparison with the characteristics of a high-pressure mercury lamp. FIGS. 2A and 2B are spectral distribution diagrams of the light source for explaining the characteristics of the light source in the present embodiment. FIG. 2A is a graph showing spectral distribution characteristics of a general high-pressure mercury lamp. As can be seen from the figure, the high-pressure mercury lamp has a relatively large relative intensity in the green light wavelength band and the blue light wavelength band, which are on the short wavelength side, in the visible light range of approximately 400 nm to 700 nm. In this case, when visually recognized, the light in the green light wavelength band is felt most strongly. On the other hand, FIG. 2B is a graph showing the spectral distribution characteristics of a general halogen lamp. As can be seen from the figure, the halogen lamp has a relatively high relative intensity in the red light wavelength band on the long wavelength side. That is, the amount of light increases in the order of red light, green light, and blue light. Therefore, in this case, a vertical liquid crystal panel may be used as the liquid crystal panel 53r for the red light RL, and a parallel liquid crystal panel may be used as the liquid crystal panels 53g and 53b for the green light GL and the blue light BL. . In this case, as described above, a vertical liquid crystal panel may be used for the red light RL and the green light GL, and a parallel liquid crystal panel may be used for the blue light BL, depending on the usage. .

[Third Embodiment]
FIG. 3 is a diagram for explaining the projector according to the third embodiment. The projector 200 according to the present embodiment is a so-called four-plate projector that combines four color lights, and includes a lighting device 210, a light separation optical system 230, a light modulation device 250, a light combining optical system 270, and a projection optical system. A projection lens 290.

  The illumination device 210 includes a light source 201 that is a generation source of the light source light WL, and an integrator optical system 220 that forms the illumination light SL from the light source light WL. Also in this embodiment, the light source 201 is a high-pressure mercury lamp as in the light source 1 of FIG. Since the integrator optical system 220 has the same mechanism as the integrator optical system 20 in FIG. 1 except that it does not have the mirror 6 that changes the direction of light, the description is omitted. The illumination light SL is formed from the light source light WL through the integrator optical system 220 and the like.

  The light separation optical system 230 includes a cross dichroic mirror 233 including first and second dichroic mirrors 231 and 232 crossed in a cross, third and fourth dichroic mirrors 234 and 235, and mirrors 236, 237, 238, and 239. , 240 and field lenses 241, 242, 243, 244. The cross dichroic mirror 233 and the dichroic mirrors 234 and 235 selectively transmit or reflect the illumination light SL formed by the illumination device 210 to separate colors for each predetermined wavelength band, thereby forming colored light of each color. More specifically, of the cross dichroic mirror 233, the first dichroic mirror 231 has a characteristic of reflecting a component in a wavelength region including the blue light BL and the green light GL. On the other hand, the second dichroic mirror 232 has a characteristic of reflecting a component in a wavelength region including the yellow light YL and the red light RL. Thereby, two types of color lights are separated from the illumination light SL. Furthermore, the third dichroic mirror 234 has a characteristic of reflecting the wavelength region component including the yellow light YL and transmitting the wavelength region component including the red light RL. The fourth dichroic mirror 235 reflects the wavelength region component including the green light GL, and transmits the wavelength region component including the blue light BL. The illumination light SL is separated into red light RL, yellow light YL, green light GL, and blue light BL for each wavelength band by the function of each dichroic mirror described above. The mirrors 236, 237, 238, 239, and 240 change the optical path of each color light in a predetermined direction by reflection. The field lenses 241, 242, 243, and 244 adjust the incident angle of each color light obtained by color separation of the illumination light to a polarizer described later.

  The light modulation device 250 includes liquid crystal light valves 251r, 251y, 251g, and 251b. The liquid crystal light valves 251r, 251y, 251g, and 251b each include a polarizer disposed on the incident side and a vertical alignment liquid crystal panel 253g. TN alignment liquid crystal panels 253r, 253y, 253b, and an analyzer disposed on the emission side. Note that the same names as those in the first embodiment have the same locations and functions, and will not be described.

  The light combining optical system 270 includes dichroic prisms 271 and 272, reflecting prisms 273 and 274, and a cross dichroic prism 275. The dichroic prisms 271 and 272 are columnar prisms having a square bottom surface, and are formed by bonding two right-angled isosceles triangular prisms with the same maximum side surface. At this time, a function as a dichroic mirror is achieved by applying a dichroic film to the bonded portion. The reflecting prisms 273 and 274 are right-angled isosceles triangular prisms having the same shape as described above, and the direction of light is changed by providing a mirror on the maximum side surface. The cross dichroic prism 275 further synthesizes the color lights synthesized by the dichroic prisms to form synthesized light that becomes projection light. The dichroic prism 271 and the reflecting prism 273 are pasted, the dichroic prism 272 and the reflecting prism 274 are pasted, and the reflecting prisms 273 and 274 are pasted on the cross dichroic prism 275 so that they are integrated into an integrated state. An optical system 270 is formed.

  The projection lens 290 is a projection optical system for projecting the formed combined light as projection light onto a screen (not shown) or the like.

  Hereinafter, the operation of the projector 200 of the present embodiment will be described with reference to FIG. In the illumination device 210, illumination light SL that is polarized light is formed by the integrator optical system 220 from the light source light WL generated and emitted from the light source 201.

  Next, in the light separation optical system 230, the illumination light SL formed by the illumination device 210 is first color-separated for each wavelength band by the dichroic mirrors 231 and 232 included in the cross dichroic mirror 233. With the function of each dichroic mirror, the illumination light SL is separated into red light RL, yellow light YL, green light GL, and blue light BL for each wavelength band. The incident angles of the colored lights of the respective colors are adjusted by the field lenses 241, 242, 243, and 244, respectively, and are guided to the liquid crystal light valves 251r, 251y, 251g, and 251b of the light modulator 250, and the liquid crystal light valves 251r, 251y, 251g, 251b is irradiated.

  Next, in the light modulation device 250, the color lights RL, YL, GL, BL of the respective colors incident on the liquid crystal light valves 251r, 251y, 251g, 251b are first converted into the liquid crystal panels 253r, The polarization direction of the incident light to 253y, 253g, and 253b is limited to a narrower range, and the degree of polarization is increased. Of each color light with an increased degree of polarization, the green light GL enters the vertical alignment liquid crystal panel 253g, and the red light RL, the yellow light YL, and the blue light BL enter the TN alignment liquid crystal panels 253r, 253y, and 253b, respectively. Incident. For each color light RL, YL, GL, BL modulated by the liquid crystal panels 253r, 253y, 253g, 253b, a polarization component in a specific direction is further selected by the analyzer on the emission side. As described above, image light of each color light RL, YL, GL, and BL is formed by the liquid crystal light valves 251r, 251y, 251g, and 251b.

  Here, also in the present embodiment, as in the first embodiment, a high-pressure mercury lamp is used as the light source 201. In this case, the amount of light in the wavelength band of the green light GL, among each color light, is relatively large due to the characteristics of the high-pressure mercury lamp. Therefore, the vertical alignment liquid crystal panel 253g, which is a vertical liquid crystal panel, is used for the green light GL. It is used. That is, the contrast ratio is increased for the green light GL, and the light quantity is secured for the other color lights RL, YL, and BL.

  Next, in the synthesis optical system 270, the formed image lights of the respective colors are combined with each other. First, the dichroic prism 271 combines the red light RL and the yellow light YL to form the two-color light RY. On the other hand, the green light GL and the blue light BL are combined by the dichroic prism 272 to form the two-color light GB. The two-color lights RY and GB are redirected by the reflecting prisms 273 and 274, respectively, and are incident on the cross dichroic prism 275 to form combined light. The formed composite light is projected as projection light from the projection lens 290 onto a screen or the like, and a color composite image having a desired magnification is displayed on the screen.

  Also in the present embodiment, as in the first embodiment, a metal halide lamp or the halogen lamp of the second embodiment can be used as the light source 201 instead of the high-pressure mercury lamp. Similarly to the first embodiment, the types of the liquid crystal panels 253r, 253y, 253g, and 253b may be appropriately determined according to the situation.

[Fourth Embodiment]
FIGS. 4A and 4B are views for explaining a projector according to the fourth embodiment. One projector 300 shown in FIG. 4A is a so-called two-plate projector that combines two color lights, and is an illumination device 310, a light separating optical system 330, a light modulating device 350, and a light combining optical system. A synthesis prism 370 and a projection lens 390 which is a projection optical system are provided.

  The illumination device 310 includes the light source 301 and the integrator optical system 320, but the structure is the same as that of the illumination device 210 of the projector 200 in FIG.

  The light separation optical system 330 includes a dichroic prism 331, mirrors 332 and 333, and field lenses 334 and 335. The dichroic prism 331 semi-transmits and semi-reflects the illumination light SL formed by the illumination device 310. The mirrors 332 and 333 change the optical path of each color light in a predetermined direction by reflection. The field lenses 334 and 335 adjust the incident angle of each color light obtained by color separation of the illumination light to a polarizer described later.

  The light modulation device 350 includes liquid crystal light valves 351w and 351c. The liquid crystal light valves 351w and 351c each include a polarizer disposed on the incident side, a vertical alignment liquid crystal panel 353w, a TN alignment liquid crystal panel 353c, And an analyzer disposed on the emission side. In addition, the thing with the same name as the thing in 1st and 2nd embodiment has omitted the description, since the installation location, the mechanism to have, etc. are the same.

  The combining prism 370 is, for example, a polarization beam splitter, and is a light combining optical system for combining image light obtained according to modulated light emitted from the liquid crystal panels 351w and 351c to form combined light.

  The projection lens 90 is a projection optical system for projecting the formed combined light as projection light onto a screen (not shown) or the like.

  Hereinafter, the operation of the projector 300 will be described with reference to FIG. In the illumination device 310, illumination light SL is formed by the integrator optical system 320 from the light source light WL generated and emitted from the light source 301.

  Next, in the light separation optical system 330, the illumination light SL formed by the illumination device 310 is semi-transmitted and semi-reflected by the dichroic prism 331. The reflected light thereby becomes monochrome light WB that is achromatic light, and the transmitted light becomes color light TC that is chromatic light. The monochrome light WB is redirected by being reflected by the mirror 332, and the incident angle is adjusted by the field lens 334. Further, the black and white light WB is guided to the liquid crystal light valve 351w of the light modulator 350 and irradiates the liquid crystal light valve 351w. Similarly, the color light TC is redirected by being reflected by the mirror 333. In this process, the transmission color is switched in time series by an adjustment valve (not shown), and the color light included in the color light TC is adjusted. For example, the adjustment can be performed by controlling a color wheel using a color filter. The color light TC having undergone the color light adjustment is adjusted in incident angle by the field lens 335, guided to the liquid crystal light valve 351w of the light modulator 350, and irradiates the liquid crystal light valve 351w.

  Next, in the light modulation device 350, the two color lights WB and TC irradiated to the liquid crystal light valves 351w and 351c are first applied to the liquid crystal panels 353w and 353c by the polarizers in the liquid crystal light valves 351w and 351c. The polarization direction of incident light is limited to a narrower range, and the degree of polarization is increased. Of each color light having an increased degree of polarization, the black and white light WB enters the vertical alignment liquid crystal panel 353w, and the color light TC enters the TN alignment liquid crystal panel 353c. For each color light WB and TC modulated by the liquid crystal panels 353w and 353c, a polarization component in a specific direction is further selected by the analyzer. As described above, image light of the respective color lights WB and TC is formed by the liquid crystal light valves 351w and 351c.

  The formed image lights are combined with each other by the combining prism 370. The composite light thus formed is projected as projection light from the projection lens 390 onto a screen or the like, and a color composite image having a desired enlargement ratio is displayed on the screen.

  Here, by using the vertical alignment liquid crystal panel 353w which is a vertical liquid crystal panel on the monochrome light WB side, the contrast ratio is high, and on the color light TC side, the TN alignment liquid crystal panel 353w which is a parallel liquid crystal panel is provided. By using it, a bright color image can be formed.

  The other projector 400 shown in FIG. 4B is also a so-called two-plate projector by combining two color lights, like the projector 300 in FIG. 4B, and includes the illumination device 410, the light separation optical system 430, and the light. A modulation device 450, a dichroic prism 470 that is a light combining optical system, and a projection lens 490 that is a projection optical system are provided.

  The illuminating device 410 includes a light source 401 and an integrator optical system 420. The structure is the same as that of the illuminating device 310 of the projector 300 in FIG.

  The light separation optical system 430 includes a dichroic mirror 431, mirrors 432 and 433, and field lenses 434 and 435. The dichroic mirror 431 color-separates a wavelength band including the green light GL as a main component in the illumination light SL formed by the illumination device 410. That is, the dichroic mirror 431 has a characteristic of reflecting the components in the wavelength region including the green light GL and transmitting the other components, that is, the components in the wavelength region including the two-color light RB of red light and blue light. Thereby, the illumination light SL is separated into the green light GL and the two-color light RB. The mirrors 432 and 433 change the optical path of each color light in a predetermined direction by reflection. The field lenses 334 and 335 adjust the incident angle of each color light obtained by color separation to a polarizer described later.

  The light modulation device 450 includes liquid crystal light valves 451g and 451r. The liquid crystal light valves 451g and 451r each include a polarizer disposed on the incident side, a vertical alignment liquid crystal panel 453g, a TN alignment liquid crystal panel 453r, And an analyzer disposed on the emission side. In addition, the thing with the same name as the thing in 1st and 2nd embodiment has omitted the description, since the installation location, the mechanism to have, etc. are the same.

  The dichroic prism 470 is a light combining optical system for combining image light obtained according to the modulated light emitted from the liquid crystal panels 451g and 451r to form combined light.

  The projection lens 490 is a projection optical system for projecting the formed combined light as projection light onto a screen (not shown) or the like.

  Hereinafter, the function of the image forming unit will be described according to the image forming procedure of the projector 400 with reference to FIG. In the illumination device 410, illumination light SL is formed by the integrator optical system 420 from the light source light WL generated and emitted from the light source 401.

  Next, in the light separation optical system 430, the illumination light SL formed by the illumination device 410 is separated into the green light GL and the two-color light RB by the dichroic mirror 431. The reflected light thereby becomes green light GL, and the transmitted light becomes two-color light RB. The green light GL is redirected by being reflected by the mirror 432, and the incident angle is adjusted by the field lens 434. Further, the green light GL is guided to the liquid crystal light valve 451g of the light modulator 450 and irradiates the liquid crystal light valve 451g. Similarly, the two-color light RB is redirected by being reflected by the mirror 433. In this process, the color transmitted in time series is switched by an adjustment valve (not shown), and the color adjustment of the two-color light RB is performed. For example, the adjustment can be performed by controlling a color wheel using a color filter. The two-color light RB having undergone color light adjustment is adjusted in incident angle by the field lens 435, guided to the liquid crystal light valve 451g of the light modulation device 450, and irradiates the liquid crystal light valve 451r.

  Next, in the light modulator 450, the color lights GL and RB of the respective colors irradiated to the liquid crystal light valves 451g and 451r are first transferred to the liquid crystal panels 453g and 453r by the polarizers in the liquid crystal light valves 451g and 451r. The polarization direction of the incident light is limited to a narrower range, and the degree of polarization is increased. Of each color light with an increased degree of polarization, the green light GL enters the vertical alignment liquid crystal panel 453g, and the two-color light RB enters the TN alignment liquid crystal panel 453r. For each color light GL and RB modulated by the liquid crystal panels 453g and 453r, a polarization component in a specific direction is further selected by the analyzer. As described above, the image lights of the color lights GL and RB are formed by the liquid crystal light valves 451g and 451r.

  The formed image lights are combined with each other by the dichroic prism 470. The composite light thus formed is projected onto the screen or the like as projection light from the projection lens 490, and a color composite image having a desired enlargement ratio is displayed on the screen.

  Here, also in the present embodiment, as in the first embodiment, a high-pressure mercury lamp is used as the light source 401. In this case, because of the characteristics of the high-pressure mercury lamp, the amount of light in the wavelength band of the green light GL among each color light is relatively large. Therefore, the vertical alignment liquid crystal panel 453g, which is a vertical liquid crystal panel, is used for the green light GL. It is used.

  In the present embodiment, as in the first and second embodiments, a metal halide lamp or a halogen lamp can be used as the light source 401 instead of the high-pressure mercury lamp. In this case, the reflection / transmission characteristics may be set so that colored light with a relatively large amount of light is extracted by the dichroic mirror 431.

  In addition, this invention is not restricted to said embodiment, In the range which does not deviate from the summary, it can implement in a various aspect, For example, the following deformation | transformation is also possible.

  In the above embodiment, the two fly lens arrays 2 and 3 are used to divide the light from the illumination device 10 into a plurality of partial light beams. However, the present invention does not use such a fly lens array. It can also be applied to a projector. Furthermore, the fly lens arrays 2 and 3 can be replaced with rod integrators.

  Further, in the projector 100, the polarization conversion element array 4 that converts the light from the illumination device 10 into polarization in a specific direction is used. However, the present invention is also applicable to a projector that does not use such a polarization conversion element array 4. Is possible.

  In the above embodiment, an example in which the present invention is applied to a transmissive projector has been described. However, the present invention can also be applied to a reflective projector. Here, “transmission type” means that the light valve including the liquid crystal panel is a type that transmits light, and “reflection type” is a type that the light valve reflects light. Means. In the case of a reflection type projector, the light valve can be constituted only by a liquid crystal panel, and a pair of polarizing plates is unnecessary. The light modulation device is not limited to a liquid crystal panel or the like, and may be a light modulation device using a micromirror, for example.

  Further, as the projector, there are a front projector that projects an image from the direction of observing the projection plane and a rear projector that projects an image from the opposite side to the direction of observing the projection plane. The projector configuration shown in FIG. Is applicable to both.

It is a figure for demonstrating the projector which concerns on 1st Embodiment. (A), (b) is a graph which shows the spectral distribution of a light source. It is a figure for demonstrating the projector which concerns on 3rd Embodiment. (A), (b) is a figure for demonstrating the projector which concerns on 4th Embodiment.

Explanation of symbols

  100, 200, 300, 400 ... projector, 1, 201, 301, 401 ... light source, 10, 210, 310, 410 ... illumination device, 30, 230, 330, 430 ... light separation optical system, 50, 250, 350, 450 ... Light modulation device, 51r, 51b, 51g, ... Liquid crystal light valve, 53g ... Vertical alignment liquid crystal panel, 53r, 53b ... TN alignment liquid crystal panel, 70 ... Cross dichroic prism, 270 ... Photosynthesis optical system, 370,470 ... Dichroic Prism, 90, 290, 390, 490 ... Projection lens, RL ... Red light, GL ... Green light, BL ... Blue light

Claims (16)

A plurality of liquid crystal panels that respectively modulate a plurality of color lights;
A color synthesis optical system for synthesizing light modulated by the plurality of liquid crystal panels;
A projection optical system for projecting light synthesized by the color synthesis optical system;
A projector comprising:
The liquid crystal panel that modulates at least one of the plurality of color lights is a vertical liquid crystal panel having a pair of substrates and a liquid crystal vertically aligned between the substrates,
The liquid crystal panel that modulates the remaining color light of the plurality of color lights is a parallel type liquid crystal panel having a pair of substrates and a liquid crystal aligned in parallel between the substrates.   The projector according to claim 1, wherein the vertical liquid crystal panel is used for color light having a relatively large light amount among the plurality of color lights.   3. The projector according to claim 1, wherein the vertical liquid crystal panel is used for color light requiring high contrast among the plurality of color lights. 4.   The projector according to claim 1, wherein the parallel liquid crystal panel is a twisted nematic liquid crystal panel.   The projector according to claim 1, further comprising a light source and a color separation optical system that separates light emitted from the light source into the plurality of color lights. The light source is either a high-pressure mercury lamp or a metal halide lamp,
The plurality of color lights include three color lights of red light, blue light, and green light. The green light is modulated using the vertical liquid crystal panel, and the blue light and the red light are 6. The projector according to claim 5, wherein the projector is modulated using a parallel liquid crystal panel. The light source is either a high-pressure mercury lamp or a metal halide lamp,
The plurality of color lights include three color lights of red light, blue light, and green light. The green light and the blue light are modulated using the vertical liquid crystal panel, and the red light is 6. The projector according to claim 5, wherein the projector is modulated using a parallel liquid crystal panel. The light source is a halogen lamp;
The plurality of color lights include three color lights of red light, blue light, and green light. The red light is modulated using the vertical liquid crystal panel, and the green light and the blue light are 6. The projector according to claim 5, wherein the projector is modulated using a parallel liquid crystal panel. The light source is a halogen lamp;
The plurality of color lights include three color lights of red light, blue light, and green light. The red light and the green light are modulated using the vertical liquid crystal panel, and the blue light is 6. The projector according to claim 5, wherein the projector is modulated using a parallel liquid crystal panel.   The projector according to claim 1, wherein the plurality of color lights are four color lights.   11. The projector according to claim 10, wherein the four color lights are obtained by adding one color light to the three color lights of red light, blue light, and green light.   12. The projector according to claim 11, wherein the four color lights are obtained by adding yellow light to the three color lights.   6. The projector according to claim 5, wherein the plurality of color lights are two color lights.   14. The projector according to claim 13, wherein the two color lights are achromatic color light and chromatic color light, and the color light requiring high contrast is the achromatic color light. The light source is either a high-pressure mercury lamp or a metal halide lamp,
14. The projector according to claim 13, wherein one of the two color lights is green light, and the green light is color light having a relatively large amount of light.   The projector according to any one of claims 1 to 15, wherein the vertical liquid crystal panel operates in a normally black mode, and the parallel liquid crystal panel operates in a normally white mode.

Images