JP2009186953A - Projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projector capable of more improving light utilization efficiency, as the projector including a plurality of liquid crystal panels of the TN type and the normally white system. <P>SOLUTION: The projector 1000 includes: an illumination device; a color-separating optical system; liquid crystal light valves 400R, 400G and 400B which include the liquid crystal panels of the TN type and the normally white system and modulates three color lights according to image information respectively; a color composing optical system; and a projection optical system. The liquid crystal light valve is configured so that a wavelength region of light where the light transmittance of the liquid crystal light valve is maximum when a voltage is not applied to the liquid crystal panel, that is, in a state where the voltage is turned off is the same as the wavelength region of the color light of an optical path in which the liquid crystal light valve is arranged or on the longer wavelength side than that. Further, the projector includes a voltage applying device which applies a predetermined bias voltage to the liquid crystal panels of the liquid crystal light valves 400G and 400B, when the projector displays a maximum luminance image. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a projector.

  2. Description of the Related Art Conventionally, a projector including a plurality of liquid crystal light valves having a TN (Twisted Nematic) type and a normally white liquid crystal panel and an emission-side polarizing plate is known (for example, see Patent Document 1). A normally white liquid crystal panel refers to a liquid crystal panel having a maximum light transmittance and a white screen when no voltage is applied.

JP 2003-131320 A

  By the way, in a projector having a plurality of TN type and normally white type liquid crystal panels like a conventional projector, there is a demand for further improving the light utilization efficiency.

  It should be noted that such a request is not required only for a projector having a plurality of TN type and normally white liquid crystal panels. For example, a projector having a plurality of VA (Vertical Alignment) type and normally black liquid crystal panels. However, there is a demand for further improving the light utilization efficiency. A normally black liquid crystal panel is a liquid crystal panel having a light transmittance that is minimized when no voltage is applied, and a black screen, contrary to a normally white liquid crystal panel.

  Accordingly, the present invention has been made in view of such circumstances, and provides a projector capable of further improving light utilization efficiency in a projector having a plurality of TN-type and normally white liquid crystal panels. This is the first purpose. A second object of the present invention is to provide a projector capable of further improving the light use efficiency in a projector having a plurality of VA type normally black liquid crystal panels.

In order to achieve the first object, the present inventor has thoroughly investigated the cause of hindering the improvement of light utilization efficiency in a projector having a plurality of conventional TN type and normally white liquid crystal panels. . As a result, the cause is: “The wavelength of light at which the light transmittance of the liquid crystal light valve arranged in the light path of each color light is maximum when the voltage is not applied to the liquid crystal panel in the voltage OFF state. It was found that the area is configured to exist in the vicinity of the wavelength range of green light with emphasis on brightness.
In this specification, “light transmittance of the liquid crystal light valve” refers to a ratio of light emitted from the liquid crystal light valve to light incident on the liquid crystal light valve.

  FIG. 7 is a diagram for explaining a problem in the conventional projector. FIG. 7 schematically shows the polarization state (linearly polarized light, elliptically polarized light, and circularly polarized light) of light incident on the liquid crystal panel of each liquid crystal light valve in a voltage OFF state in which no voltage is applied to the liquid crystal panel. ing.

  In a projector having a plurality of conventional TN-type and normally white liquid crystal panels, a liquid crystal light valve for red light, a liquid crystal light valve for green light, and a liquid crystal light valve for blue light are used. The same type of liquid crystal light valve configured to maximize the light transmittance of the liquid crystal light valve in the wavelength range between blue light and green light when the voltage is not applied is used.

At this time, the wavelength range (λ _R , λ _G , λ _B ) of the color light modulated by each liquid crystal light valve and the wavelength range (maximum light transmittance of the liquid crystal light valve when the liquid crystal panel is in the voltage OFF state ( λ _A ) has a wavelength difference (Δλ), and as shown in FIG. 7, for blue light, the polarization axis of the light rotates too much by 90 degrees or more, while green light and red light About light, it will be in the state where rotation of the polarization axis of light is insufficient. These are due to the refractive index between blue light, green light and red light. For this reason, when the liquid crystal panel of each liquid crystal light valve is set to the voltage OFF state, light is lost in all color lights of red light, green light, and blue light, and light use efficiency is reduced. In particular, since the above-described wavelength difference (Δλ) is greater for red light than for other color light, the loss of light when the liquid crystal panel is in a voltage OFF state also increases. As a result, the light use efficiency of red light is lower than the light use efficiency of other color lights.

In the process of finding the above knowledge, the present inventor found that when the projector displays an image with the highest luminance, the light transmittance of the liquid crystal light valve is the maximum when the voltage is not applied to the liquid crystal panel and the voltage is OFF. The liquid crystal light is configured such that the wavelength range of light (λ _A ) is longer than the wavelength range of wavelength light (λ _R , λ _G , λ _B ) of the optical path in which the liquid crystal light valve is disposed. When a predetermined bias voltage is applied to the liquid crystal panel of the bulb, the light whose polarization axis has been rotated more than 90 degrees can be returned, and the light of the colored light in the optical path where the liquid crystal light valve is arranged There is also a new finding that it is possible to make the transmittance close to the maximum, or to align the light transmittance of the liquid crystal light valve disposed in the optical path of the corresponding color light in the above wavelength range (λ _R , λ _G , λ _B ) Obtained.

That is, when the plurality of liquid crystal light valves are liquid crystal light valves configured such that the wavelength range (λ _A ) is on the longer wavelength side than the wavelength range (λ _R , λ _G , λ _B ), If a predetermined bias voltage is applied, the light whose polarization axis has been rotated by 90 degrees or more can be returned, and the light transmittance of the colored light in the optical path in which the liquid crystal light valve is arranged is brought close to the maximum. Alternatively, it is possible to make the light transmittances of the liquid crystal light valves arranged in the optical paths of the corresponding colored light in the above wavelength ranges (λ _R , λ _G , λ _B ). Thereby, the light transmittance of the liquid crystal light valve in the wavelength range (λ _A ) when the liquid crystal panel is in the voltage OFF state, and the wavelength range of the colored light in the optical path in which the liquid crystal light valve to which a predetermined bias voltage is applied are arranged ( λ _R , λ _G , λ _B ) can be reduced or eliminated from the light transmittance, so that the above-described loss of light can be suppressed and the light utilization efficiency can be suppressed. Can be suppressed.

Based on the above knowledge, the present inventor has (1) the wavelength range (λ _A ) to be the same as the wavelength range (λ _R , λ _G , λ _B ) or on the longer wavelength side. A liquid crystal light valve configured to exist is disposed in the optical path of each color light, and (2) when the projector displays an image with the highest luminance, the wavelength range (λ _A ) is the wavelength range (λ _R , Λ _G , λ _B ), if a predetermined bias voltage is applied to the liquid crystal panel of the liquid crystal light valve configured to exist on the longer wavelength side, the light utilization efficiency can be further improved as a result. As a result, the present invention has been completed.

  That is, a projector according to the present invention includes an illuminating device that emits an illuminating light beam, a color separation optical system that separates light from the illuminating device into a plurality of color lights, and guides the light to an illuminated area, and a TN type and normally. A plurality of liquid crystals having a white-type liquid crystal panel and an emission-side polarizing plate arranged on the light emission side of the liquid crystal panel, and respectively modulating a plurality of color lights guided by the color separation optical system according to image information A light valve; a color synthesis optical system that synthesizes each color light modulated by the plurality of liquid crystal light valves; a projection optical system that projects image light synthesized by the color synthesis optical system; and the plurality of liquid crystal light valves. A liquid crystal driving device for controlling the driving of the liquid crystal light valve, wherein each of the plurality of liquid crystal light valves is in a voltage OFF state in which no voltage is applied to the liquid crystal panel. In addition, the wavelength range of the light having the maximum light transmittance of the liquid crystal light valve is the same as the wavelength range of the colored light in the optical path in which the liquid crystal light valve is arranged, or the wavelength range is longer than that. When the projector displays an image with the highest luminance, the wavelength of light at which the light transmittance of the liquid crystal light valve becomes maximum when the voltage is OFF among the plurality of liquid crystal light valves. A voltage for applying a predetermined bias voltage to the liquid crystal panel of the liquid crystal light valve configured to have a wavelength region longer than the wavelength range of the colored light in the optical path in which the liquid crystal light valve is disposed It further has an application device.

For this reason, according to the projector of the present invention, each of the plurality of liquid crystal light valves has (1) the light transmittance of the liquid crystal light valve is maximized when the voltage is not applied to the liquid crystal panel. The wavelength range of light (λ _A ) is the same as the wavelength range (λ _R , λ _G , λ _B ) of the colored light in the optical path in which the liquid crystal light valve is disposed, or exists on the longer wavelength side. (2) Since the above-described voltage application device is provided, the wavelength range (λ _A ) is longer than the wavelength range (λ _R , λ _G , λ _B ). The voltage application device applies a predetermined bias voltage to the liquid crystal panel of the liquid crystal light valve configured to make the light transmittance of the color light in the optical path in which the liquid crystal light valve is disposed close to the maximum. Or the above wavelength range (λ _R , λ _G , Λ _B ), the light transmittance of the liquid crystal light valve arranged in the optical path of the corresponding color light can be made uniform. As a result, the light transmittance in the wavelength region (λ _A ) of the liquid crystal light valve in the voltage OFF state and the wavelength region (λ _R) corresponding to the colored light in the optical path in which the liquid crystal light valve to which a predetermined bias voltage is applied are arranged. , Λ _G , λ _B ) with respect to the light transmittance can be reduced or eliminated, so that the occurrence of light loss in the liquid crystal light valve can be suppressed, and the light utilization efficiency can be reduced. Can be suppressed.

  Therefore, the projector of the present invention is a projector that can further improve the light utilization efficiency in a projector that includes a plurality of TN type and normally white liquid crystal panels.

Incidentally, in recent years, the demand for home projectors for watching movies and the like at home has increased dramatically. In such home projectors, it is important to improve the reproducibility of dark scenes and to smoothly reproduce the skin color of a person, so the color temperature of the projected white image is black and the color temperature is low. The one closer to the body trajectory is more preferable. However, in a projector having a plurality of conventional TN type normally white liquid crystal panels, the light use efficiency of red light is low as described above. It is difficult to make the color coordinates of the white image to be brought close to the black body locus.
On the other hand, according to the projector of the present invention, as described above, it is possible to improve the light utilization efficiency of red light. It is possible to make the color coordinates of the image approach the black body locus. As a result, the projector of the present invention is particularly effective for home projectors for watching movies and the like at home.

  In the projector according to the aspect of the invention, the plurality of liquid crystal light valves may have a wavelength range of light that maximizes a light transmittance of the liquid crystal light valve when the voltage is not applied to the liquid crystal panel. It is preferable that the plurality of color lights separated by the color separation optical system are configured to exist in the same wavelength range as that of the color light having the longest wavelength.

  With this configuration, all the liquid crystal light valves can have the same configuration, so that the cost for manufacturing the projector can be reduced.

  In order to achieve the second object, the present inventor has thoroughly investigated the cause of hindering the improvement of light utilization efficiency in a projector having a plurality of conventional VA type and normally black liquid crystal panels. . As a result, the cause is “The liquid crystal light valve arranged in the light path of each color light has a light wavelength at which the light transmittance of the liquid crystal light valve is maximized when the voltage is applied to the liquid crystal panel. It was found that the region is configured to exist in a wavelength region between blue light and green light.

  FIG. 8 is a diagram for explaining a problem in the conventional projector. In FIG. 8, the polarization state (linearly polarized light, elliptically polarized light, circularly polarized light) of light incident on the liquid crystal panel of each liquid crystal light valve when the voltage is in the ON state where a predetermined first voltage is applied to the liquid crystal panel. This is shown schematically.

  In a projector having a plurality of conventional VA type normally black liquid crystal panels, a liquid crystal light valve for red light, a liquid crystal light valve for green light, and a liquid crystal light valve for blue light are used as liquid crystal panels. The same type of liquid crystal light valve configured to maximize the light transmittance of the liquid crystal light valve in the wavelength range between blue light and green light when the voltage is applied is used.

At this time, the wavelength range (λ _R , λ _G , λ _B ) of the color light modulated by each liquid crystal light valve and the wavelength range (maximum light transmittance of the liquid crystal light valve when the liquid crystal panel is in the voltage ON state ( Since a wavelength difference (Δλ) occurs with respect to λ _A ), as shown in FIG. 8, for blue light, the polarization axis of the light rotates too much by 90 degrees or more, while green light and red light About light, it will be in the state where rotation of the polarization axis of light is insufficient. These are due to the refractive index between blue light, green light and red light. For this reason, when the liquid crystal panel of each liquid crystal light valve is in the voltage ON state, light is lost in all color lights of red light, green light, and blue light, and the light use efficiency is lowered. In particular, since the above-described wavelength difference (Δλ) is greater for red light than for other color light, the loss of light when the liquid crystal panel is in a voltage ON state is also increased. As a result, the light use efficiency of red light is lower than the light use efficiency of other color lights.

In the process of finding out the above knowledge, the present inventor, when the projector displays an image with the highest luminance, the light transmission of the liquid crystal light valve when the predetermined first voltage is applied to the liquid crystal panel in the voltage ON state. The wavelength range (λ _A ) of the light having the maximum rate is configured to be on the longer wavelength side than the wavelength ranges (λ _R , λ _G , λ _B ) of the colored light in the optical path in which the liquid crystal light valve is arranged When a predetermined second voltage lower than the first voltage is applied to the liquid crystal panel of the liquid crystal light valve, the liquid crystal whose light polarization axis has been rotated more than 90 degrees can be returned. The light transmittance of the color light of the light path in which the light valve is arranged is made close to the maximum, or the light transmittance of the liquid crystal light valve arranged in the light path of the corresponding color light in the above wavelength range (λ _R , λ _G , λ _B ) New knowledge that it is possible to align It was also obtained.

That is, when the plurality of liquid crystal light valves are liquid crystal light valves configured such that the wavelength range (λ _A ) is on the longer wavelength side than the wavelength range (λ _R , λ _G , λ _B ), If a second voltage lower than the first voltage is applied, the light whose polarization axis has been rotated more than 90 degrees can be returned, and the light transmittance of the colored light in the optical path in which the liquid crystal light valve is arranged It is possible to make the light transmittance of the liquid crystal light valve arranged in the optical path of the corresponding color light in the above wavelength range (λ _R , λ _G , λ _B ) uniform. Accordingly, the light transmittance of the liquid crystal light valve in the wavelength range (λ _A ) of the liquid crystal panel to which the first voltage is applied and the wavelength of the corresponding color light in the optical path in which the liquid crystal light valve to which the second voltage is applied are arranged. Since it is possible to reduce or eliminate the difference from the light transmittance of the regions (λ _R , λ _G , λ _B ), it is possible to suppress the occurrence of the light loss described above, and It is possible to suppress a decrease in usage efficiency.

Based on the above knowledge, the present inventor has (1) the wavelength range (λ _A ) to be the same as the wavelength range (λ _R , λ _G , λ _B ) or on the longer wavelength side. A liquid crystal light valve configured to exist is disposed in the optical path of each color light, and (2) when the projector displays an image with the highest luminance, the wavelength range (λ _A ) is the wavelength range (λ _R , Λ _G , λ _B ), when a predetermined second voltage lower than the first voltage is applied to the liquid crystal panel of the liquid crystal light valve configured to exist on the longer wavelength side than the first voltage, as a result The inventors have conceived that utilization efficiency can be further improved and have completed the present invention.

  The projector of the present invention includes an illuminating device that emits an illuminating light beam, a color separation optical system that separates light from the illuminating device into a plurality of color lights and guides the light to an illuminated area, and a VA type and normally black system And a plurality of liquid crystal light valves that respectively modulate a plurality of color lights guided by the color separation optical system in accordance with image information. A color synthesis optical system that synthesizes each color light modulated by the plurality of liquid crystal light valves, a projection optical system that projects image light synthesized by the color synthesis optical system, and a drive for the plurality of liquid crystal light valves A liquid crystal driving device for controlling the liquid crystal, wherein each of the plurality of liquid crystal light valves is in a voltage ON state in which a predetermined first voltage is applied to the liquid crystal panel. The wavelength range of the light having the maximum light transmittance of the liquid crystal light valve is the same as the wavelength range of the colored light in the optical path in which the liquid crystal light valve is disposed or is present on the longer wavelength side. When the projector displays an image with the highest luminance, the wavelength range of light in which the light transmittance of the liquid crystal light valve is maximum when the voltage is on among the plurality of liquid crystal light valves. Is lower than the first voltage with respect to the liquid crystal panel of the liquid crystal light valve configured to exist on the longer wavelength side than the wavelength range of the colored light in the optical path in which the liquid crystal light valve is disposed. A voltage application device that applies the second voltage is further provided.

Therefore, according to the projector of the present invention, each of the plurality of liquid crystal light valves is (1) the light transmittance of the liquid crystal light valve when the predetermined first voltage is applied to the liquid crystal panel. So that the wavelength range (λ _A ) of light having the maximum becomes the same as the wavelength range (λ _R , λ _G , λ _B ) of the color light in the optical path in which the liquid crystal light valve is arranged (2) Since the above-described voltage application device is provided, the wavelength range (λ _A ) is longer than the wavelength range (λ _R , λ _G , λ _B ). When the voltage application device applies a predetermined second voltage to the liquid crystal panel of the liquid crystal light valve configured to exist on the wavelength side, the light transmittance of the color light in the optical path in which the liquid crystal light valve is disposed the closer to the maximum, or the wavelength range (lambda _{R, G,} lambda _B) be made uniform light transmittance of the liquid crystal light valve that is disposed in an optical path of the corresponding color light becomes possible. As a result, the light transmittance in the wavelength region (λ _A ) of the liquid crystal light valve to which the first voltage is applied to the liquid crystal panel, and the optical path in which the liquid crystal light valve to which the second voltage is applied is disposed on the liquid crystal panel. Since it is possible to reduce or eliminate the difference from the light transmittance in the wavelength range (λ _R , λ _G , λ _B ) corresponding to the color light, the occurrence of light loss in the liquid crystal light valve It is possible to suppress the decrease in light utilization efficiency.

  Therefore, the projector of the present invention is a projector that can further improve the light utilization efficiency in a projector that includes a plurality of VA type and normally black liquid crystal panels.

Incidentally, in recent years, the demand for home projectors for watching movies and the like at home has increased dramatically. In such home projectors, it is important to improve the reproducibility of dark scenes and to smoothly reproduce the skin color of a person, so the color temperature of the projected white image is black and the color temperature is low. The one closer to the body trajectory is more preferable. However, in the conventional projector having a plurality of VA type and normally black liquid crystal panels, the light use efficiency of red light is low as described above. It is difficult to make the color coordinates of the white image to be brought close to the black body locus.
On the other hand, according to the projector of the present invention, as described above, it is possible to improve the light utilization efficiency of red light. It is possible to make the color coordinates of the image approach the black body locus. As a result, the projector of the present invention is particularly effective for home projectors for watching movies and the like at home.

  In the projector according to the aspect of the invention, the plurality of liquid crystal light valves may have a light wavelength range in which the light transmittance of the liquid crystal light valve is maximized when the first voltage is applied to the liquid crystal panel. However, it is preferable to be configured to exist in the same wavelength region as the wavelength region of the color light having the longest wavelength among the plurality of color lights separated by the color separation optical system.

  With this configuration, all the liquid crystal light valves can have the same configuration, so that the cost for manufacturing the projector can be reduced.

  In the projector according to the aspect of the invention, it is preferable that at least two of the plurality of liquid crystal light valves have the same configuration.

  With this configuration, it is possible to reduce the cost for manufacturing the projector.

  In the projector according to the aspect of the invention, it is preferable that the predetermined bias voltage or the predetermined second voltage is a voltage that maximizes the light transmittance of the liquid crystal light valve in a wavelength region where the visibility is maximized.

  With this configuration, a brighter projected image can be obtained.

  In the projector according to the aspect of the invention, it is preferable that the predetermined bias voltage or the predetermined second voltage is a voltage that maximizes the light transmittance of the liquid crystal light valve in a wavelength region where the tristimulus value is maximized.

  With this configuration, a more vivid image can be obtained.

  The projector of the present invention will be described below based on the embodiments shown in the drawings.

[Embodiment 1]
In the first embodiment, a case of a projector including a plurality of TN type normally white liquid crystal panels will be described.
FIG. 1 is a diagram illustrating an optical system of a projector 1000 according to the first embodiment.
FIG. 2 is a diagram for explaining the projector 1000 according to the first embodiment. FIG. 2A is a diagram showing the relationship between a predetermined bias voltage applied to the liquid crystal panel and the light transmittance of the liquid crystal light valve in the projector 1000a according to a comparative example to be described later, and FIG. It is a figure which shows the relationship between the predetermined | prescribed bias voltage applied to the liquid crystal panel in the projector 1000 which concerns on, and the light transmittance of a liquid crystal light valve.
FIG. 3 is a diagram for explaining the projector 1000 according to the first embodiment. FIG. 3A illustrates the polarization state of light incident on the liquid crystal panels 410R, 410G, and 410B (linearly polarized light, elliptically polarized light, and circularly polarized light) when the voltage is off and no voltage is applied to the liquid crystal panels 410R, 410G, and 410B. 3 (b) is a diagram schematically showing the polarization state of light incident on the liquid crystal panels 410R, 410G, and 410B when a predetermined bias voltage is applied to the liquid crystal panels 410G and 410B. It is a figure shown typically.

  As shown in FIG. 1, the projector 1000 according to the first embodiment separates the illumination device 100 and the illumination light flux from the illumination device 100 into three color lights of red light, green light, and blue light and guides them to the illumination area. A color separation optical system 200 that emits light, three liquid crystal light valves 400R, 400G, and 400B that modulate each of the three color lights separated by the color separation optical system 200 according to image information, and three liquid crystal light valves 400R, Cross dichroic prism 500 as a color synthesis optical system that synthesizes the color lights modulated by 400G and 400B, projection optical system 600 that projects the light synthesized by cross dichroic prism 500 onto a projection surface such as a screen SCR, and image information Based on the liquid crystal panel 410R in the liquid crystal light valve 400R, 400G, 400B, 10G, a liquid crystal driving device 700 for driving the 410B (not shown.), A projector and a voltage applying unit 710 (not shown.).

  The illuminating device 100 includes a light source device 110 that emits an illumination light beam toward the illuminated region side, and a first plurality of first small lenses 122 that divide the illumination light beam emitted from the light source device 110 into a plurality of partial light beams. The lens array 120, the second lens array 130 having a plurality of second small lenses 132 corresponding to the plurality of first small lenses 122 of the first lens array 120, and the polarization directions of the partial light beams from the second lens array 130 The polarization conversion element 140 that converts into substantially one type of linearly polarized light that exits and emits the light, and the superimposing lens 150 that superimposes the partial light beams emitted from the polarization conversion element 140 in the illuminated area.

  The light source device 110 includes an ellipsoidal reflector 114, an arc tube 112 having a light emission center near the first focal point of the ellipsoidal reflector 114, and light emitted from the arc tube 112 toward the illuminated region side to the arc tube 112. It has a secondary mirror 116 that reflects toward the head and a concave lens 118 that emits the converged light from the ellipsoidal reflector 114 as substantially parallel light. The light source device 110 emits a light beam having the illumination optical axis OC as a central axis.

  The arc tube 112 has a tube bulb portion and a pair of sealing portions extending on both sides of the tube bulb portion. The tube portion is made of quartz glass formed in a spherical shape, and includes a pair of electrodes disposed in the tube portion, mercury, a rare gas, and a small amount of halogen sealed in the tube portion. As the arc tube 112, various arc tubes can be employed, for example, a metal halide lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, or the like.

  The ellipsoidal reflector 114 includes a cylindrical neck that is inserted and fixed to one sealing portion of the arc tube 112, and a reflective concave surface that reflects light emitted from the arc tube 112 toward the second focal position. Have

  The secondary mirror 116 is a reflecting means that covers substantially half of the bulb portion of the arc tube 112 and is disposed to face the reflective concave surface of the elliptical reflector 114. The sub mirror 116 is inserted and fixed to the other sealing portion of the arc tube 112. The secondary mirror 116 returns the light emitted from the arc tube 112 that is not directed to the ellipsoidal reflector 114 to the arctube reflector 112 and makes it incident on the ellipsoidal reflector 114.

  The concave lens 118 is disposed on the illuminated area side of the ellipsoidal reflector 114. Then, the light from the ellipsoidal reflector 114 is emitted toward the first lens array 120.

  The first lens array 120 has a function as a light beam splitting optical element that splits light from the concave lens 118 into a plurality of partial light beams, and a plurality of first small lenses 122 are arranged in a plane orthogonal to the illumination optical axis OC. It has a configuration arranged in a matrix of rows and columns. Although not described with reference to the drawings, the outer shape of the first small lens 122 is similar to the outer shape of image forming regions of liquid crystal panels 410R, 410G, and 410B described later.

  The second lens array 130 has a function of forming an image of each first small lens 122 of the first lens array 120 in the vicinity of the image forming area of the liquid crystal panels 410R, 410G, and 410B together with the superimposing lens 150. The second lens array 130 has substantially the same configuration as the first lens array 120, and a plurality of second small lenses 132 are arranged in a matrix of a plurality of rows and a plurality of columns in a plane orthogonal to the illumination optical axis OC. Have a configuration.

The polarization conversion element 140 is a polarization conversion element that emits the polarization direction of each partial light beam divided by the first lens array 120 as approximately one type of linearly polarized light having a uniform polarization direction.
The polarization conversion element 140 transmits light having one polarization component (for example, P polarization component) out of the illumination light beam from the light source device 110 and light having the other polarization component (for example, S polarization component) to the illumination optical axis OC. A polarization separation layer that reflects in the vertical direction, a reflection layer that reflects light having the other polarization component reflected by the polarization separation layer in a direction parallel to the illumination optical axis OC, and one polarization that has passed through the polarization separation layer And a phase difference plate that converts light having a component into light having the other polarization component.

  The superimposing lens 150 condenses a plurality of partial light beams that have passed through the first lens array 120, the second lens array 130, and the polarization conversion element 140, and superimposes them in the vicinity of the image forming regions of the liquid crystal panels 410R, 410G, and 410B. It is an element. The superimposing lens 150 is arranged so that the optical axis of the superimposing lens 150 and the illumination optical axis OC of the illumination device 100 substantially coincide. The superimposing lens 150 may be composed of a compound lens in which a plurality of lenses are combined.

  The color separation optical system 200 includes dichroic mirrors 210 and 220, reflection mirrors 230, 240, and 250, an incident side lens 260, and a relay lens 270. The color separation optical system 200 separates the illumination light beam emitted from the superimposing lens 150 into three color lights of red light, green light, and blue light, and the three liquid crystal light valves 400R, It has a function of leading to 400G and 400B.

  The dichroic mirrors 210 and 220 are optical elements in which a wavelength selection film that reflects a light beam in a predetermined wavelength region and transmits a light beam in another wavelength region is formed on a substrate. The dichroic mirror 210 disposed in the front stage of the optical path is a mirror that reflects a red light component and transmits other color light components. The dichroic mirror 220 disposed in the latter stage of the optical path is a mirror that reflects the green light component and transmits the blue light component.

  The red light component reflected by the dichroic mirror 210 is bent by the reflection mirror 230 and enters the liquid crystal light valve 400R for red light via the condenser lens 300R. The condenser lens 300R is provided to convert each partial light beam from the superimposing lens 150 into a light beam substantially parallel to each principal ray. The other condenser lenses 300G and 300B are configured in the same manner as the condenser lens 300R.

  Of the green light component and the blue light component that have passed through the dichroic mirror 210, the green light component is reflected by the dichroic mirror 220, passes through the condenser lens 300G, and enters the liquid crystal light valve 400G for green light. On the other hand, the blue light component is transmitted through the dichroic mirror 220, passes through the incident side lens 260, the incident side reflection mirror 240, the relay lens 270, the emission side reflection mirror 250, and the condensing lens 300B, and is a liquid crystal for blue light. It enters the light valve 400B. The incident side lens 260, the relay lens 270, and the reflection mirrors 240 and 250 have a function of guiding the blue light component transmitted through the dichroic mirror 220 to the liquid crystal light valve 400B.

The liquid crystal light valves 400 </ b> R, 400 </ b> G, and 400 </ b> B modulate the illumination light beam according to the image information, and are the illumination target of the illumination device 100.
The liquid crystal light valves 400R, 400G, and 400B include liquid crystal panels 410R, 410G, and 410B, incident-side polarizing plates 420R, 420G, and 420B disposed on the light incident side of the liquid crystal panels 410R, 410G, and 410B, and the liquid crystal panels 410R and 410G. , 410B and emission side polarizing plates 430R, 430G, and 430B that transmit light having a polarization axis orthogonal to the polarization axis of light that passes through the incident side polarizing plates 420R, 420G, and 420B.

  The liquid crystal panels 410R, 410G, and 410B are a TN type normally white type liquid crystal panel in which a liquid crystal that is an electro-optical material is hermetically sealed in a pair of transparent glass substrates. For example, using a polysilicon TFT as a switching element, the polarization direction of one type of linearly polarized light emitted from the incident side polarizing plates 420R, 420G, and 420B is modulated in accordance with given image information.

  The incident-side polarizing plates 420R, 420G, and 420B, the liquid crystal panels 410R, 410G, and 410B and the emission-side polarizing plates 430R, 430G, and 430B perform light modulation of each color light incident thereon.

  Each of the liquid crystal light valves 400R, 400G, 400B has a light transmittance that maximizes the light transmittance of the liquid crystal light valves 400R, 400G, 400B when no voltage is applied to the liquid crystal panels 410R, 410G, 410B. The wavelength range is configured to exist in the same wavelength range as the wavelength range of red light having the longest wavelength among the three color lights (red light, green light, and blue light) separated by the color separation optical system 200. Yes.

  Accordingly, in the liquid crystal light valves 400G and 400B, when the voltage is OFF, the wavelength range of light in which the light transmittance of the liquid crystal light valves 400G and 400B is maximized is the color light of the optical path in which the liquid crystal light valves 400G and 400B are disposed ( It exists in the long wavelength side rather than the wavelength range of green light or blue light). These are due to the refractive index between blue light, green light and red light.

  The liquid crystal driving device 700 supplies a driving voltage based on image information to each of the liquid crystal panels 410R, 410G, 410B, and drives the liquid crystal panels 410R, 410G, 410B.

  The voltage application device 710 has a function of applying a predetermined bias voltage to the liquid crystal panels 410G and 410B of the liquid crystal light valves 400G and 400B, respectively. The predetermined bias voltage reduces the difference in light transmittance so that the light transmittance of the liquid crystal light valve does not differ for each color light at a wavelength at which the visibility within the wavelength region range of each color light is maximum. Or, the voltage is adjusted to eliminate. Details will be described later.

  The cross dichroic prism 500 is an optical element that forms a color image by synthesizing an optical image modulated for each color light emitted from the exit side polarizing plate. The cross dichroic prism 500 has a substantially square shape in plan view in which four right-angle prisms are bonded together, and a dielectric multilayer film is formed on a substantially X-shaped interface in which the right-angle prisms are bonded together. The dielectric multilayer film formed at one of the substantially X-shaped interfaces reflects blue light, and the dielectric multilayer film formed at the other interface reflects red light. By these dielectric multilayer films, the blue light and the red light are bent and aligned with the traveling direction of the green light, so that the three color lights are synthesized.

  The color image emitted from the cross dichroic prism 500 is enlarged and projected by the projection optical system 600 to form a large screen image on the screen SCR.

  Here, in describing the projector 1000 according to the first embodiment in more detail, a projector 1000a according to a comparative example of the first embodiment will be described.

  The projector 1000a (not shown) according to the comparative example basically has a configuration similar to that of the projector 1000 according to the first embodiment, but the configuration of the liquid crystal light valve is different from that of the projector 1000 according to the first embodiment. .

That is, in the projector 1000a according to the comparative example, the liquid crystal light valve for red light, the liquid crystal light valve for green light, and the liquid crystal light valve for blue light are in a voltage OFF state in which no voltage is applied to the liquid crystal panel. In addition, the light wavelength range (λ _A0 ) at which the light transmittance of the liquid crystal light valve becomes maximum exists between the blue light and the green light.

For this reason, for the liquid crystal light valve for blue light, when the voltage is OFF, the polarized light in the wavelength range (λ _B ) of the blue light incident on the liquid crystal panel is linearly polarized light, but the blue light emitted from the liquid crystal panel The polarized light in the wavelength band (λ _B ) becomes elliptically polarized light that is further modulated than the linearly polarized light that intersects the incident linearly polarized light (refer to FIG. 7 for the polarization state) and is modulated by the liquid crystal panel. Since part of the light in the wavelength region (λ _B ) of the blue light after being blocked is blocked by the exit-side polarizing plate, the light transmittance in the wavelength region (λ _B ) of the blue light is reduced (FIG. 2 ( See a).). At this time, for the elliptically polarized light emitted from the liquid crystal panel for blue light, a predetermined bias voltage is applied to the liquid crystal panel of the liquid crystal light valve for blue light, so that the wavelength range (λ _B ) Light can be modulated into linearly polarized light that passes through the exit-side polarizing plate and emitted from the liquid crystal panel. Therefore, the above wavelength range of the liquid crystal light valve for blue light in which a predetermined bias voltage is applied to the liquid crystal panel ( The light transmittance at λ _B ) is close to the light transmittance at the above wavelength range (λ _A0 ) of the liquid crystal light valve for blue light when no voltage is applied to the liquid crystal panel, or a predetermined bias voltage is applied to the liquid crystal panel. The light transmittance in the above wavelength range (λ _B ) of the liquid crystal light valve for blue light applied in the above wavelength range (λ _A0 ) of the liquid crystal light valve for blue light when no voltage is applied to the liquid crystal panel. Light transmittance It can be aligned to become. Thus, for example, when displaying an image with the highest luminance on the projector 1000a, a predetermined bias voltage is applied to the liquid crystal panel of the liquid crystal light valve for blue light, and the predetermined bias voltage is applied to the liquid crystal panel. Light transmittance in the above wavelength range (λ _B ) of the liquid crystal light valve for blue light and light transmittance in the wavelength range (λ _A0 ) of the liquid crystal light valve for blue light when no voltage is applied to the liquid crystal panel The difference in light can be reduced, or the difference in light transmittance between the two can be eliminated, so that the above-described loss of light can be suppressed, and the decrease in light utilization efficiency of blue light can be suppressed. Is possible.

However, with respect to the liquid crystal light valve for green light and the liquid crystal light valve for red light, it is impossible to suppress a decrease in the light use efficiency of green light and red light for the following reasons. That is, for the liquid crystal light valve for green light and the liquid crystal light valve for red light, when the voltage is OFF, the wavelength range of the green light (λ _G ) and the wavelength range of the red light (λ _R ) incident on each liquid crystal panel The polarized light in the green light is a linearly polarized light, but the polarized light in the wavelength range of the green light (λ _G ) and the wavelength range of the red light (λ _R ) emitted from each liquid crystal panel is a linearly polarized light that intersects the incident linearly polarized light. Is not modulated until it is emitted in the state of elliptically polarized light (refer to FIG. 7 for the polarization state), so that the wavelength region (λ _G ) of green light after being modulated by the liquid crystal panel and A part of the light in the red light wavelength range (λ _R ) is blocked by the exit-side polarizing plate, and the light transmittance in the green light wavelength range (λ _G ) and the red light wavelength range (λ _R ) decreases. (See FIG. 2 (a)). At this time, even if a predetermined bias voltage is applied to the liquid crystal panels of the liquid crystal light valve for green light and the liquid crystal light valve for red light, the wavelength range of green light (λ _G ) and the wavelength range of red light (λ _G ) λ _R ) cannot be compensated for the light modulation, and the light transmittance of the liquid crystal light valve in the wavelength range of green light (λ _G ) and the liquid crystal in the wavelength range of red light (λ _R ) The light transmittance of the light valve approaches the light transmittance in the wavelength range (λ _A0 ) of the liquid crystal light valve when no voltage is applied to the liquid crystal panel, or the light of the liquid crystal light valve in the wavelength range (λ _G ) The transmittance and the light transmittance of the liquid crystal light valve in the wavelength range (λ _R ) cannot be matched to the light transmittance in the wavelength range (λ _A0 ) of the liquid crystal light valve when no voltage is applied to the liquid crystal panel. . In other words, even if a predetermined bias voltage is applied to each liquid crystal panel of the liquid crystal light valve for green light and the liquid crystal light valve for red light, the light transmittance of the liquid crystal light valve in the wavelength range of each color light cannot be increased. Can not. As a result, for example, when displaying an image with the highest luminance on the projector 1000a, the above-described loss of light cannot be suppressed for green light and red light, and the light use efficiency of green light and red light can be suppressed. The decline cannot be suppressed.

On the other hand, according to the projector 1000 according to the first embodiment configured as described above, the liquid crystal light valve 400R of the liquid crystal light valve 400R is in a voltage OFF state in which no voltage is applied to the liquid crystal panel 410R. Since the wavelength range (λ _A ) of light with the maximum light transmittance is configured to be in the same wavelength range as the wavelength range of red light (λ _R ), the light utilization efficiency of red light is improved. It becomes possible.

Further, according to the projector 1000 according to the first embodiment, the liquid crystal light valves 400G and 400B have a light wavelength range (λ _A ) in which the light transmittance of the liquid crystal light valves 400G and 400B is maximum when the voltage is in an OFF state. The liquid crystal light valves 400G and 400B are configured to exist on the longer wavelength side than the wavelength range of the colored light (the wavelength range of the green light (λ _G ) and the wavelength range of the blue light (λ _B )) of the optical path in which the liquid crystal light valves 400G and 400B are arranged. ing.
At this time, when the voltage is OFF, as in the case of the projector 1000a according to the comparative example described above, as shown in FIG. 3A, the wavelength range (λ _G ) and wavelength emitted from each of the liquid crystal panels 410G and 410B. The polarized light in the region (λ _B ) becomes elliptically polarized light that is further modulated than the linearly polarized light that intersects the incident linearly polarized light, and the wavelength region (λ _G ) after being modulated by the liquid crystal panels 410G and 410B and Since part of the light in the wavelength region (λ _B ) is blocked by the exit-side polarizing plates 430G and 430B, the light transmittance in the wavelength region (λ _G ) and the wavelength region (λ _B ) decreases. However, for the elliptically polarized light emitted from the liquid crystal panel 410G for green light and the liquid crystal panel 410B for blue light, a predetermined bias voltage is applied to the liquid crystal panels 410G and 410B by the voltage applying device 710 described above. (See FIG. 2 (b).) Thus, as shown in FIG. 3 (b), linearly polarized light that transmits light in the wavelength region (λ _G ) and wavelength region (λ _B ) through the exit-side polarizing plates 430G and 430B. Therefore, the liquid crystal light valves 400G and 400B in which a predetermined bias voltage is applied to the liquid crystal panels 410G and 410B have the light transmittance in the above wavelength range (λ _G ) and wavelength range (λ _B ). When the voltage is not applied to the panels 410G and 410B, the liquid crystal light valves 400G and 400B are brought close to the light transmittance in the above wavelength range (λ _A ), or the liquid crystal The liquid crystal light valves 400G and 400B to which a predetermined bias voltage is applied to the panels 410G and 410B are not applied to the liquid crystal panels 410G and 410B with respect to the light transmittance in the wavelength range (λ _G ) and wavelength range (λ _B ). In this case, the light transmittance of the liquid crystal light valves 400G and 400B in the wavelength range (λ _A ) can be made uniform. Thereby, particularly when the projector 1000 displays an image with the highest luminance, the liquid crystal light valves 400G and 400B have the light transmittance in the wavelength range (λ _G ) and the wavelength range (λ _B ) and the liquid crystal panels 410G and 410B. When the voltage is not applied to the liquid crystal light valves 400G and 400B, the difference between the light transmittances in the wavelength range (λ _A ) of the liquid crystal light valves 400G and 400B can be reduced, or the difference between the two light transmittances can be eliminated. The occurrence of the above-described light loss can be suppressed, and the decrease in the light use efficiency of the green light and the blue light can be suppressed.

  Therefore, the projector 1000 according to the first embodiment is a projector that can further improve the light utilization efficiency in a projector that includes a plurality of TN-type and normally white liquid crystal panels.

  Further, according to the projector 1000 according to the first embodiment, it is possible to improve the light use efficiency of red light, so that the color temperature is reduced while maintaining the brightness, or the color coordinates of the projected white image Can be moved closer to the black body locus. As a result, the projector 1000 according to the first embodiment is particularly effective for a home projector for watching movies and the like at home.

  In the projector 1000 according to the first embodiment, the liquid crystal light valves 400R, 400G, and 400B have the liquid crystal light valves 400R, 400G, and 400B when the voltage is not applied to the liquid crystal panels 410R, 410G, and 410B. The wavelength range of light having the maximum light transmittance is configured to exist in the same wavelength range as the wavelength range of red light. As a result, the configuration of all the liquid crystal light valves can be made the same, so that the cost for manufacturing the projector can be reduced.

  In the projector 1000 according to the first embodiment, the predetermined bias voltage applied by the voltage application device 710 is a voltage that maximizes the visibility, so that a brighter projected image can be obtained.

[Embodiment 2]
In the second embodiment, a case of a projector including a plurality of VA type and normally black liquid crystal panels will be described.
FIG. 4 is a diagram illustrating an optical system of the projector 1002 according to the second embodiment.
FIG. 5 is a diagram for explaining a projector 1002 according to the second embodiment. FIG. 5A is a diagram showing a relationship between a predetermined first voltage applied to the liquid crystal panel and the light transmittance of the liquid crystal light valve in a projector 1002a according to a comparative example which will be described later, and FIG. FIG. 6 is a diagram showing a relationship between a predetermined second voltage applied to the liquid crystal panel in the projector 1002 according to 2 and the light transmittance of the liquid crystal light valve.
FIG. 6 is a diagram for explaining a projector 1002 according to the second embodiment. FIG. 6A illustrates the polarization state of light incident on the liquid crystal panels 412R, 412G, and 412B (linearly polarized light, elliptically polarized light, and the like) when the first voltage is applied to the liquid crystal panels 412R, 412G, and 412B. FIG. 6B is a diagram schematically showing (circularly polarized light). FIG. 6B is a diagram illustrating light incident on the liquid crystal panels 412R, 412G, and 412B when a predetermined second voltage is applied to the liquid crystal panels 412G and 412B. It is a figure which shows a polarization state typically.
In FIG. 4, the same members as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

  As can be seen from FIG. 4, the projector 1002 according to the second embodiment basically has the same configuration as that of the projector 1000 according to the first embodiment, except that the configuration of the liquid crystal light valve and the voltage application device are not provided. This is different from the projector 1000 according to the first embodiment. Further, the projector 1002 according to the second embodiment differs from the projector 1000 according to the first embodiment in terms of the function of the liquid crystal driving device depending on the configuration of the liquid crystal light valve and the absence of the voltage application device.

  That is, in the projector 1002 according to the second embodiment, the liquid crystal light valves 402R, 402G, and 402B are light incident on the VA type normally black liquid crystal panels 412R, 412G, and 412B and the liquid crystal panels 412R, 412G, and 412B. The incident-side polarizing plates 420R, 420G, and 420B disposed on the side and the liquid crystal panels 412R, 412G, and 412B are disposed on the light exit side and orthogonal to the polarization axis of the polarized light that passes through the incident-side polarizing plates 420R, 420G, and 420B. It has exit side polarizing plates 430R, 430G, and 430B that transmit polarized light of the polarization axis.

  Each of the liquid crystal light valves 402R, 402G, and 402B has the maximum light transmittance of the liquid crystal light valves 402R, 402G, and 402B when a predetermined first voltage is applied to the liquid crystal panels 412R, 412G, and 412B. The wavelength range of the light to be in the same wavelength range as the wavelength range of the red light having the longest wavelength among the three color lights (red light, green light and blue light) separated by the color separation optical system 200 It is configured.

  Therefore, in the liquid crystal light valves 402G and 402B, the wavelength range of light in which the light transmittance of the liquid crystal light valves 402G and 402B is maximized when the voltage is ON is the color light of the optical path in which the liquid crystal light valves 402G and 402B are disposed ( It exists in the long wavelength side rather than the wavelength range of green light or blue light).

  A liquid crystal driving device 702 (not shown) supplies a driving voltage based on image information to each of the liquid crystal panels 412R, 412G, 412B, and in addition to a function of driving the liquid crystal panels 412R, 412G, 412B, a liquid crystal light Each of the valves 402G and 402B has a function of applying a predetermined second voltage to the liquid crystal panels 412G and 412B. The predetermined second voltage reduces the difference in light transmittance so that the light transmittance of the liquid crystal light valve does not differ for each color light at the wavelength where the visibility within the wavelength region range of each color light is maximum. Or a voltage adjusted to eliminate.

  In describing the projector 1002 according to the second embodiment in more detail, a projector 1002a according to a comparative example of the second embodiment will be described.

  The projector 1002a (not shown) according to the comparative example basically has a configuration similar to that of the projector 1002 according to the second embodiment, but the configuration of the liquid crystal light valve is different from that of the projector 1002 according to the second embodiment. .

That is, in the projector 1002a according to the comparative example, a voltage obtained by applying a predetermined first voltage to the liquid crystal panel as a liquid crystal light valve for red light, a liquid crystal light valve for green light, and a liquid crystal light valve for blue light. The light wavelength range (λ _A0 ) in which the light transmittance of the liquid crystal light valve is maximum when the liquid crystal light valve is in an ON state is present between the blue light and the green light.

For this reason, when the voltage is ON, the liquid crystal light valve for blue light is linearly polarized in the wavelength range (λ _B ) of the blue light incident on the liquid crystal panel, but the blue light emitted from the liquid crystal panel is The polarized light in the wavelength region (λ _B ) becomes elliptically polarized light that is further modulated than the linearly polarized light that intersects the incident linearly polarized light (refer to FIG. 8 for the polarization state), and is modulated by the liquid crystal panel. Since part of the light in the wavelength region (λ _B ) of the blue light after being blocked is blocked by the exit-side polarizing plate, the light transmittance in the wavelength region (λ _B ) of the blue light is reduced (FIG. 5 ( See a).). At this time, for the elliptically polarized light emitted from the blue light liquid crystal panel, by applying a predetermined second voltage to the liquid crystal panel of the blue light liquid crystal light valve, the wavelength range of the blue light (λ _B ) the light in the above wavelength range of the liquid crystal light valve for blue light in which a predetermined bias voltage is applied to the liquid crystal panel because the light of _B ) can be modulated into linearly polarized light that passes through the exit side polarizing plate and emitted from the liquid crystal panel. The light transmittance at (λ _B ) is brought close to the light transmittance in the wavelength range (λ _A0 ) of the liquid crystal light valve for blue light when no voltage is applied to the liquid crystal panel, or a predetermined bias voltage is applied to the liquid crystal panel. The wavelength range of the liquid crystal light valve for blue light when no voltage is applied to the liquid crystal panel in the wavelength range (λ _B ) of the liquid crystal light valve for blue light to which is applied. λ _A0 It is possible to align the light transmittance at. Thus, for example, when displaying an image with the highest luminance by the projector 1002a, the light transmittance in the wavelength range (λ _B ) of the liquid crystal light valve for blue light in which a predetermined bias voltage is applied to the liquid crystal panel and the liquid crystal Because it is possible to reduce the difference in light transmittance in the wavelength range (λ _A0 ) of the liquid crystal light valve for blue light when no voltage is applied to the panel, or to eliminate the difference in light transmittance between the two. Thus, it is possible to suppress the occurrence of the above-described light loss, and it is possible to suppress a decrease in light utilization efficiency of blue light.

However, with respect to the liquid crystal light valve for green light and the liquid crystal light valve for red light, it is impossible to suppress a decrease in the light use efficiency of green light and red light for the following reasons. That is, with respect to the liquid crystal light valve for green light and the liquid crystal light valve for red light, when the voltage is ON, the wavelength range of the green light (λ _G ) and the wavelength range of the red light (λ _R ) incident on each liquid crystal panel The polarized light in the green light is a linearly polarized light, but the polarized light in the wavelength range of the green light (λ _G ) and the wavelength range of the red light (λ _R ) emitted from each liquid crystal panel is a linearly polarized light that intersects the incident linearly polarized light. Until it is emitted in an elliptically polarized state (refer to FIG. 8 for the polarization state), the wavelength range of the green light (λ _G ) after being modulated by the liquid crystal panel and A part of the light in the red light wavelength range (λ _R ) is blocked by the exit-side polarizing plate, and the light transmittance in the green light wavelength range (λ _G ) and the red light wavelength range (λ _R ) decreases. (See FIG. 5 (a)). At this time, even if a predetermined second voltage is applied to the liquid crystal panels of the green light liquid crystal light valve and the red light liquid crystal light valve, the green light wavelength range (λ _G ) and the red light wavelength range Insufficient modulation of (λ _R ) into the light cannot be compensated, and the light transmittance of the liquid crystal light valve in the wavelength region of green light (λ _G ) and the wavelength region of red light (λ _R ) The light transmittance of the liquid crystal light valve is brought close to the light transmittance in the above wavelength range (λ _A0 ) of the liquid crystal light valve when no voltage is applied to the liquid crystal panel, or the liquid crystal light valve in the above wavelength range (λ _G ). The light transmittance and the light transmittance of the liquid crystal light valve in the wavelength range (λ _R ) can be matched to the light transmittance in the wavelength range (λ _A0 ) of the liquid crystal light valve when no voltage is applied to the liquid crystal panel. Can not. That is, even when a predetermined second voltage is applied to the liquid crystal light valves for green light and red light, the light transmittance of the liquid crystal light valve in the wavelength range of each color light is increased. I can't. As a result, for example, when an image with the highest luminance is displayed by the projector 1002a, the above-described light loss cannot be suppressed for the green light and the red light, and the light use efficiency of the green light and the red light can be suppressed. The decline cannot be suppressed.

On the other hand, according to the projector 1002 according to the second embodiment configured as described above, the liquid crystal light valve 402R is in the liquid crystal light valve when the first voltage is applied to the liquid crystal panel 412R. Since the wavelength range (λ _A ) of the light having the maximum light transmittance of 402R exists in the same wavelength range as the wavelength range (λ _R ) of red light, the light utilization efficiency of red light is reduced. It becomes possible to improve.

Further, according to the projector 1002 according to the second embodiment, the liquid crystal light valves 402G and 402B have a light wavelength region (λ _A ) in which the light transmittance of the liquid crystal light valves 402G and 402B is maximized when the voltage is on. The liquid crystal light valves 402G and 402B are configured to exist on the longer wavelength side than the wavelength range of the colored light (the wavelength range of the green light (λ _G ) and the wavelength range of the blue light (λ _B )) of the optical path in which the liquid crystal light valves 402G and 402B are arranged. ing.
At this time, when the voltage is ON, as in the projector 1002a according to the comparative example described above, as shown in FIG. 6A, the wavelength range (λ _G ) and wavelength emitted from each of the liquid crystal panels 412G and 412B The polarized light in the region (λ _B ) becomes elliptically polarized light that is further modulated than the linearly polarized light that intersects the incident linearly polarized light, and the wavelength region (λ _G ) after being modulated by the liquid crystal panels 412G and 412B and Since part of the light in the wavelength region (λ _B ) is blocked by the exit-side polarizing plates 430G and 430B, the light transmittance in the wavelength region (λ _G ) and the wavelength region (λ _B ) decreases. However, for the elliptically polarized light emitted from the green light liquid crystal panel and the blue light liquid crystal panel, the liquid crystal driving device 702 described above has a predetermined lower voltage than the first voltage with respect to the liquid crystal light valves 402G and 402B. By applying the second voltage (see FIG. 5 (b)), as shown in FIG. 6 (b), light in the wavelength region (λ _G ) and wavelength region (λ _B ) is emitted on the emission side polarizing plate 430G, Since the light can be modulated into linearly polarized light transmitted through 430B, the liquid crystal light valves 400G and 400B in which the second voltage is applied to the liquid crystal panels 410G and 410B have the above wavelength range (λ _G ) and wavelength range (λ _B ). The light transmittance is brought close to the light transmittance in the above wavelength range (λ _A ) of the liquid crystal light valves 400G and 400B when the first voltage is applied to the liquid crystal panels 410G and 410B, or The first voltage is applied to the liquid crystal panels 410G and 410B in accordance with the light transmittance in the wavelength range (λ _G ) and the wavelength range (λ _B ) of the liquid crystal light valves 400G and 400B to which the second voltage is applied to the channels 410G and 410B. In this case, the light transmittance of the liquid crystal light valves 400G and 400B in the wavelength range (λ _A ) can be made uniform. As a result, particularly when the projector 1002 displays an image with the highest luminance, the light transmittance of the liquid crystal light valves 400G and 400B in the wavelength range (λ _G ) and the wavelength range (λ _B ) and the liquid crystal panels 410G and 410B. When the voltage is not applied to the liquid crystal light valves 400G and 400B, the difference between the light transmittances in the wavelength range (λ _A ) of the liquid crystal light valves 400G and 400B can be reduced, or the difference between the two light transmittances can be eliminated. The occurrence of the above-described light loss can be suppressed, and the decrease in the light use efficiency of the green light and the blue light can be suppressed.

  Therefore, the projector 1002 according to the second embodiment is a projector that can further improve the light utilization efficiency in a projector that includes a plurality of VA type and normally black liquid crystal panels.

  Further, according to the projector 1002 according to the second embodiment, since it is possible to improve the light use efficiency of red light, the color temperature of the white image to be projected can be reduced while maintaining the brightness or the color coordinates of the projected white image. Can be moved closer to the black body locus. As a result, the projector 1002 according to the second embodiment is particularly effective for a home projector for watching movies and the like at home.

  In the projector 1002 according to the second embodiment, the liquid crystal light valves 402R, 402G, and 402B are in the voltage ON state in which the first voltage is applied to the liquid crystal panels 412R, 412G, and 412B. The wavelength range of the light having the maximum light transmittance of 402B is configured to exist in the same wavelength range as the wavelength range of red light. As a result, the configuration of all the liquid crystal light valves can be made the same, so that the cost for manufacturing the projector can be reduced.

  In the projector 1002 according to the second embodiment, the predetermined second voltage applied by the liquid crystal driving device 702 is a voltage that maximizes the visibility, so that a brighter projected image can be obtained.

  The projector of the present invention has been described based on each of the above embodiments. However, the present invention is not limited to each of the above embodiments, and can be implemented in various modes without departing from the scope of the invention. For example, the following modifications are possible.

  In the first embodiment, the liquid crystal light valve for red light, the liquid crystal light valve for green light, and the liquid crystal light valve for blue light are used when the voltage is not applied to the liquid crystal panel in the voltage OFF state. Although the liquid crystal light valve configured so that the wavelength range of the light having the maximum light transmittance of the bulb exists in the same wavelength range as the wavelength range of the red light is used, the present invention is not limited to this. Absent. For example, as a liquid crystal light valve for green light, the wavelength range of light that maximizes the light transmittance of the liquid crystal light valve when the voltage is not applied to the liquid crystal panel is the wavelength range of green light. You may use the liquid crystal light valve comprised so that it might exist in the same wavelength range. Further, as a liquid crystal light valve for blue light, the wavelength range of light that maximizes the light transmittance of the liquid crystal light valve when the voltage is not applied to the liquid crystal panel is the wavelength range of blue light or You may use the liquid crystal light valve comprised so that it might exist in the same wavelength range as the wavelength range of green light. However, in this case, at least two liquid crystal light valves of the plurality of liquid crystal light valves have the same configuration, and the light transmittance of the liquid crystal light valve is maximized when the voltage is OFF. In a liquid crystal light valve that modulates light in a short wavelength range, when the projector displays an image with the highest luminance, a predetermined bias voltage is applied, and the light transmittance of the liquid crystal light valve in the wavelength range of the modulated light is We will adjust it to the maximum value.

  In the second embodiment, when the liquid crystal light valve for red light, the liquid crystal light valve for green light, and the liquid crystal light valve for blue light are in the voltage ON state when the first voltage is applied to the liquid crystal panel, Although the liquid crystal light valve configured so that the wavelength range of the light having the maximum light transmittance of the liquid crystal light valve exists in the same wavelength range as the wavelength range of the red light is used, the present invention is limited to this. It is not a thing. For example, as a liquid crystal light valve for green light, the wavelength range of light that maximizes the light transmittance of the liquid crystal light valve when the first voltage is applied to the liquid crystal panel is the wavelength of green light. A liquid crystal light valve configured to exist in the same wavelength region as the region may be used. In addition, as a liquid crystal light valve for blue light, the wavelength range of light at which the light transmittance of the liquid crystal light valve becomes maximum when the first voltage is applied to the liquid crystal panel is the wavelength of blue light. A liquid crystal light valve configured to exist in the same wavelength range as that of the green light or the wavelength range of green light may be used. However, in this case, at least two liquid crystal light valves among the plurality of liquid crystal light valves have the same configuration, and the light transmittance of the liquid crystal light valve is maximized when the voltage is on. In a liquid crystal light valve that modulates light in a short wavelength region, when the projector displays an image with the highest luminance, a predetermined second voltage is applied to the light transmittance of the liquid crystal light valve in the wavelength region of light to be modulated. It will be adjusted so that becomes the maximum value.

  In each of the above embodiments, the liquid crystal light valve for red light, the liquid crystal light valve for green light, and the liquid crystal light valve for blue light all use the liquid crystal light valve having the same configuration. However, the present invention is not limited to this, and two liquid crystal light valves out of the three liquid crystal light valves may have the same configuration.

  In each of the above embodiments, the predetermined bias voltage applied by the voltage application device or the predetermined second voltage applied by the liquid crystal driving device is a liquid crystal in a wavelength region where the visibility is maximized in the color light modulated by the liquid crystal panel. The case where the voltage is adjusted so that the transmittance of the light valve is maximized has been described as an example. However, the present invention is not limited to this, and the tristimulus value in the color light modulated by the liquid crystal panel is described. The voltage may be adjusted so that the light transmittance of the liquid crystal light valve is maximized in the wavelength region where the maximum is. Specifically, in the case of a liquid crystal panel that modulates red light, a bias voltage or a predetermined second voltage is set so that the light transmittance in the wavelength region where the tristimulus value X is maximum is maximized. If the liquid crystal panel modulates blue light, the bias voltage or the predetermined second voltage is set so that the light transmittance in the wavelength range where the tristimulus value Y is maximum is maximized. For example, the bias voltage or the predetermined second voltage is set so that the light transmittance in the wavelength region where the tristimulus value Z is maximum is maximized. In either case, the predetermined bias voltage or the predetermined second voltage may be finely adjusted so that the light transmittance for each color light is equal.

  In the first embodiment, the case where the liquid crystal driving device and the voltage applying device are separately provided has been described as an example, but the present invention is not limited to this. For example, the liquid crystal driving device and the voltage application device may be integrated, and the device may have a function of applying the predetermined bias voltage described above.

  In each of the above embodiments, the secondary mirror is used as the reflecting means disposed on the arc tube. However, the present invention is not limited to this, and it is also preferable to use a reflective film as the reflecting means. Further, in each of the above embodiments, the projector in which the secondary mirror as the reflecting means is disposed on the arc tube is described as an example, but the present invention is not limited to this, and the secondary mirror is arranged. It is also possible to apply the present invention to a projector that is not provided.

  In each of the above-described embodiments, the light source device including the ellipsoidal reflector and the concave lens is used as the light source device. However, the present invention is not limited to this, and it is also preferable to use the light source device including the parabolic reflector. .

  In each of the above embodiments, a lens integrator optical system including a lens array is used as the light uniformizing optical system. However, the present invention is not limited to this, and a rod integrator optical system including a rod member is also preferable. Can be used.

Each of the above embodiments is a transmissive projector, but the present invention is not limited to this. The present invention can also be applied to a reflection type projector. Here, “transmission type” means that an electro-optic modulation device as a light modulation means, such as a transmission type liquid crystal device, transmits light, and “reflection type” This means that an electro-optic modulation device as a light modulation means, such as a reflective liquid crystal device, is a type that reflects light. Even when the present invention is applied to a reflective projector, the same effect as that of a transmissive projector can be obtained.
Specifically, light from the illumination device is incident from the light incident / exit surface of the reflective liquid crystal panel, reciprocates through the liquid crystal layer, is emitted from the light incident / exit surface, and the emitted light is projected as an image projected by the polarizing plate. Even in the case of a reflective liquid crystal light valve that is separated into light to be used and light that is not projected, if it is normally white, it will be an image of color light in the longer wavelength side of each color light in the voltage OFF state. By configuring each reflective liquid crystal panel so that the illuminance of the light used is maximized, the same effects as those of the transmissive liquid crystal light valve of each of the above embodiments can be obtained. Further, in the case of normally black, each illuminance of light used as an image of color light in the wavelength region on the longer wavelength side of each color light in a voltage ON state where a predetermined first voltage is applied is maximized. By configuring the reflective liquid crystal panel, the same effects as those of the transmissive liquid crystal light valve of each of the above embodiments can be obtained.

  In the projector 1000 and the projector 1002 according to the above embodiment, the projector using the three liquid crystal light valves 400B, 400G, and 400R has been described as an example. However, the present invention is not limited to this, and two or The present invention can also be applied to a projector using four or more liquid crystal light valves.

  The present invention can be applied to a front projection type projector that projects from the side that observes the projected image, or to a rear projection type projector that projects from the side opposite to the side that observes the projected image. is there.

FIG. 3 shows an optical system of the projector 1000 according to the first embodiment. FIG. 3 is a diagram for explaining a projector 1000 according to the first embodiment. FIG. 3 is a diagram for explaining a projector 1000 according to the first embodiment. FIG. 6 is a diagram showing an optical system of a projector 1002 according to a second embodiment. FIG. 6 is a diagram for explaining a projector 1002 according to a second embodiment. FIG. 6 is a diagram for explaining a projector 1002 according to a second embodiment. The figure shown in order to demonstrate the problem in the conventional projector. The figure shown in order to demonstrate the problem in the conventional projector.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 100 ... Illuminating device, 110 ... Light source device, 112 ... Light emission tube, 114 ... Ellipsoidal reflector, 116 ... Secondary mirror, 118 ... Concave lens, 120 ... First lens array, 122 ... First small lens, 130 ... Second lens array 132 ... second small lens, 140 ... polarization conversion element, 150 ... superimposed lens, 200 ... color separation optical system, 210,220 ... dichroic mirror, 230,240,250 ... reflection mirror, 260 ... incident side lens, 270 ... Relay lens, 300R, 300G, 300B ... Condensing lens, 400R, 400G, 400B, 402R, 402G, 402B ... Liquid crystal light valve, 410R, 410G, 410B, 412R, 412G, 412B ... Liquid crystal panel, 420R, 420G, 420B ... Incident side polarizing plate, 430R, 430G, 430B... Exit side polarizing plate 500 ... cross dichroic prism 600 ... projection optical system, 1000, 1002 ... projector, OC ... illumination optical axis, SCR ... screen.

Claims (7)

An illumination device that emits an illumination beam;
A color separation optical system that separates light from the illumination device into a plurality of color lights and guides the light to an illuminated area;
A TN type normally white liquid crystal panel and an emission-side polarizing plate arranged on the light emission side of the liquid crystal panel, and each of a plurality of color lights guided by the color separation optical system according to image information Multiple liquid crystal light valves that modulate
A color synthesis optical system for synthesizing each color light modulated by the plurality of liquid crystal light valves;
A projection optical system for projecting image light synthesized by the color synthesis optical system;
A projector comprising a liquid crystal driving device for controlling the driving of the plurality of liquid crystal light valves,
Each of the plurality of liquid crystal light valves has a wavelength range of light in which the light transmittance of the liquid crystal light valve is maximum when a voltage OFF state in which no voltage is applied to the liquid crystal panel is disposed in the liquid crystal light valve. It is configured to be the same as the wavelength range of the colored light in the optical path to be present or on the longer wavelength side than that,
When the projector displays an image with the highest brightness, among the plurality of liquid crystal light valves, the wavelength range of light at which the light transmittance of the liquid crystal light valve is maximum when the voltage is OFF is the liquid crystal light. A voltage applying device that applies a predetermined bias voltage to the liquid crystal panel of the liquid crystal light valve configured to exist on the longer wavelength side of the wavelength range of the colored light in the optical path in which the bulb is disposed; Projector. The projector according to claim 1, wherein
The plurality of liquid crystal light valves are separated by the color separation optical system in a wavelength range of light in which the light transmittance of the liquid crystal light valve is maximum when a voltage is not applied to the liquid crystal panel. A projector configured to exist in the same wavelength range as the wavelength range of the color light having the longest wavelength among the plurality of color lights. An illumination device that emits an illumination beam;
A color separation optical system that separates light from the illumination device into a plurality of color lights and guides the light to an illuminated area;
A liquid crystal panel of VA type and normally black type and an emission side polarizing plate arranged on the light emission side of the liquid crystal panel, and each of a plurality of color lights guided by the color separation optical system according to image information Multiple liquid crystal light valves that modulate
A color synthesis optical system for synthesizing each color light modulated by the plurality of liquid crystal light valves;
A projection optical system for projecting image light synthesized by the color synthesis optical system;
A projector comprising a liquid crystal driving device for controlling the driving of the plurality of liquid crystal light valves,
Each of the plurality of liquid crystal light valves has a wavelength range of light in which the light transmittance of the liquid crystal light valve is maximum when a predetermined first voltage is applied to the liquid crystal panel. It is configured to be the same as the wavelength range of the colored light in the optical path in which the light valve is arranged or to exist on the longer wavelength side than that,
The liquid crystal driving device is configured such that, when the projector displays an image with the highest luminance, the wavelength of light at which the light transmittance of the liquid crystal light valve is maximum when the voltage is on among the plurality of liquid crystal light valves. The liquid crystal panel of the liquid crystal light valve configured to be present on a longer wavelength side than the wavelength range of the color light of the optical path in which the liquid crystal light valve is disposed is lower than the first voltage. A projector having a function of applying the second voltage. The projector according to claim 3, wherein
The plurality of liquid crystal light valves have a wavelength range of light in which the light transmittance of the liquid crystal light valve is maximized when the first voltage is applied to the liquid crystal panel. The projector is configured to exist in the same wavelength range as the wavelength range of the color light having the longest wavelength among the plurality of color lights separated in step (b). The projector according to claim 1 or 3,
The projector characterized in that at least two of the plurality of liquid crystal light valves have the same configuration. The projector according to any one of claims 1 to 5,
The projector according to claim 1, wherein the predetermined bias voltage or the predetermined second voltage is a voltage that maximizes the light transmittance of the liquid crystal light valve in a wavelength region where the visibility is maximized. The projector according to any one of claims 1 to 5,
The projector according to claim 1, wherein the predetermined bias voltage or the predetermined second voltage is a voltage that maximizes the light transmittance of the liquid crystal light valve in a wavelength region where the tristimulus value is maximum.

Images