JP2005321544A - Projection type display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projection type display device in which the color irregularities of a projection image are reduced. <P>SOLUTION: Each of the color rays of light into which light is decomposed by a color decomposing optical system is reflected by the polarizing separation part of a polarization beam splitter and made incident on a reflection type light valve. The color rays of light modulated by the reflection type light valve are transmitted through the polarizing separation part of the polarization beam splitter and detected. The detected color rays of light are composed by a color composing optical system and then made incident on a projection lens. The light emitted from the projection lens is made incident on the polarizing conversion member, simulatively converted into non-polarized light, and thereafter projected onto a transmission type screen comprising a Fresnel lens. Since the light is projected onto the transmission type screen after simulatively converted into the non-polarized light by the polarizing conversion member, the projection type display device in which color irregularities are reduced can be provided. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a projection display device.

  2. Description of the Related Art Conventionally, there is known a projection type display device that separates light from a light source into three colors of light, irradiates the light valve via three polarization beam splitters arranged for each color, and projects the color combined light. ing. Light emitted from the light source is separated into three colors of red (R), green (G), and blue (B) by a color separation optical system. Each color light that has undergone color separation enters a polarization beam splitter disposed for each color light, is polarized and separated, and the S-polarized light reflected by the polarization separation film is disposed for each color light. Is incident on. The light modulated by the reflection type light valve is reflected and emitted, and enters the polarization beam splitter again.

Of the light incident on the polarization beam splitter, the P-polarized light that passes through the polarization separation unit is analyzed and is incident on a color combining optical system composed of a composite prism composed of four triangular prisms. The light synthesized by the color synthesizing optical system is incident on a projection lens having an aspherical lens made of a plastic optical member, deflected by a reflection mirror disposed inside the projection lens, and then emitted. . The emitted light is projected on the screen. In a rear projection display device, so-called reapplication television, a projected image is projected on a transmission screen composed of a Fresnel lens.
JP-A-2003-29210

  In a conventional projection display device, each color light detected by the polarization beam splitter is polarized light, and this polarized light is polarized by a lens or mirror in the projection lens when passing through the projection lens. Is disturbed. At that time, the polarization state is different for each color light of B, G, and R, and the polarization state varies depending on the direction in which the light is emitted. For this reason, when this light is incident on the screen of the Fresnel lens, there is a problem in that color unevenness occurs in the image transmitted through the screen due to the interaction between the polarization characteristics inherent to the screen and the polarization state of the incident light. .

  The present invention has been made in view of such problems, and an object of the present invention is to provide a projection display device in which color unevenness of a projected image is reduced.

In order to solve the above problem, an invention according to claim 1 is directed to a light valve that modulates light from a light source, a projection lens that projects light modulated by the light valve onto a transmissive screen, and the transmissive screen. There is provided a projection type display device comprising a polarization conversion member that makes a polarization state of projected light pseudo-non-polarized.

The invention according to claim 2 provides the projection display device according to claim 1, wherein the polarization conversion member is disposed between the projection lens and the transmission screen.
The invention according to claim 3 is a color separation optical system that separates light from the light source into R (red) light, G (green) light, and B (blue) light, and a reflection that is arranged for each of the color lights. The R-type light valve and the color-separated R light, G light, and B light are polarized and separated to enter the reflective light valve arranged for each color light, and the light emitted from the reflective light valve A polarizing beam splitter arranged for each color light to be analyzed, a color synthesis optical system for color-combining each color light detected by the polarization beam splitter, and a projection for projecting the color-synthesized light onto a transmission type screen A projection comprising: a lens; and a polarization conversion member that is disposed between the projection lens and the transmission screen, and makes a polarization state of light projected on the transmission screen pseudo-unpolarized. A type display device is provided.

  The invention according to claim 4 includes a half-wavelength phase plate disposed in each optical path of the R light and the B light or the optical path of the G light between the polarizing beam splitter and the color combining optical system, The color synthesizing optical system includes a first dichroic film that reflects R light and a second dichroic film that reflects B light, which are arranged orthogonal to each other, with respect to the first dichroic film and the second dichroic film. 4. The projection display device according to claim 3, wherein the polarization directions of the R light and the B light incident on the color synthesis optical system are S-polarized light and the G light is P-polarized light.

  The invention according to claim 5 has a quarter-wave phase plate disposed between the color synthesizing optical system and the projection lens, and the projection display device according to claim 3 or 4 I will provide a.

  The invention according to claim 6 is a color separation optical system for color-separating light from the light source into R (red) light, G (green) light, and B (blue) light, and a light disposed for each color light. Light is emitted from the bulb, a polarizer that polarizes the color-separated R light, G light, and B light and enters the light valve arranged for each color light, and light emitted from the light valve. An analyzer, a color synthesis optical system that color-synthesizes each color light analyzed by the analyzer, a projection lens that projects the color-synthesized light onto a transmission screen, and the projection lens and the transmission screen. There is provided a projection display device comprising a polarization conversion member that is disposed between the polarization conversion members to make the polarization state of light projected on the transmission screen pseudo-unpolarized.

  The invention according to claim 7 is provided with a half-wavelength phase plate disposed in each optical path of the R light and the B light or the optical path of the G light between the analyzer and the color synthesis optical system, and the color The synthesizing optical system includes a first dichroic film that reflects R light and a second dichroic film that reflects B light, which are arranged orthogonally, and with respect to the first dichroic film and the second dichroic film, The projection type display device according to claim 6, wherein the polarization directions of the R light and the B light incident on the color synthesis optical system are S polarization, and the G light is P polarization.

  The invention according to claim 8 is the projection display device according to any one of claims 1 to 7, wherein the polarization conversion member is a phase plate having a phase difference of 20000 nm or more. provide.

  The invention according to claim 9 is characterized in that the direction of the optical axis of the phase plate is arranged at an angle of 45 degrees with the polarization direction of each of the detected color lights. A type display device is provided.

The invention according to claim 10 provides the projection display device according to claim 8, wherein the optical axis of the phase plate can rotate around the optical axis of the projection lens.
The invention according to an eleventh aspect provides the projection display device according to any one of the first to ninth aspects, wherein the transmissive screen is made of a Fresnel lens.

  The present invention can provide a projection display device in which color unevenness of a projected image is reduced.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a configuration diagram of a projection display device according to the first embodiment, and FIG. 2 is a configuration diagram of an optical engine 10-1 of the projection display device shown in FIG.
First, the configuration of the optical engine 10-1 will be described with reference to FIG. The light emitted from the light source 11 enters the polarization conversion illumination device 12 and is converted into polarized light. The polarization conversion illumination device 12 is not shown in FIG. 2, but includes a first lens plate in which a plurality of lenses for dividing a light beam from the light source 11 into a plurality of intermediate light beams are arranged in a matrix shape, and a lens of the first lens plate. A second lens plate in which a plurality of lenses are disposed in a similar manner at a substantially focal position, and polarized light that converts light from a plurality of light source images formed on the lenses of the second lens plate into single polarized light. And a conversion unit. The polarization converter transmits light polarized in a specific direction from light from the light source and reflects light polarized in a direction orthogonal to the light, and transmits light reflected by the polarization element through the polarization element. A plurality of combinations in which reflective elements that are deflected so as to travel in the same direction as the emitted light are alternately combined are arranged. A half-wave plate is disposed on one of the exit surfaces of the light transmitted through the polarizing element or the light reflected by the reflecting element after being reflected by the polarizing element. Thereby, all the emitted light is converted into polarized light that vibrates in the same direction.

  Furthermore, the polarization conversion illumination device 12 includes a condenser lens that illuminates the polarized light by superimposing it on light valves 18B, 18G, and 18R described later. The light emitted from the light source 11 is converted into polarized light having a polarization direction in a direction perpendicular to the paper surface by the polarization conversion illumination device 12. This polarization direction is S-polarized light for the polarization beam splitters 17B, 17G, and 17R described later.

  The light emitted from the polarization conversion illumination device 12 reflects B (blue) light, reflects R (red) light and G (green) light, and reflects R light and G light. Then, the dichroic mirror 13RG having the characteristic of transmitting the B light is incident on the cross dichroic mirror 13 arranged orthogonal to each other. The incident light is color-separated into B light that is perpendicular to the incident light and travels in opposite directions, and mixed light of R light and G light. The color-separated B light is deflected by the deflecting mirror 14 and enters the polarization beam splitter 17B, and the S-polarized light reflected by the polarization separation unit enters the B light reflection type light valve 18B.

The mixed light of the color-separated R light and G light is deflected by the deflecting mirror 15, then reflects the G light, enters the dichroic mirror 16 having a characteristic of transmitting the R light, and is reflected by the G light. And color separation into transmitted R light. The cross dichroic mirror 13, the dichroic mirror 16, and the deflecting mirror 15 constitute a color separation optical system.
The color-separated R light and G light enter the polarization beam splitters 17G and 17R, respectively, and the S-polarized light reflected by the polarization separation unit enters the reflection type light valves 18G and 18R, respectively.

  The respective color lights incident on the reflection type light valves 18B, 18G, and 18R are reflected and emitted by being modulated by the respective color signals, and enter the polarization beam splitters 17B, 17G, and 17R again. For each color light incident on the polarization beam splitters 17B, 17G, and 17R, P-polarized light that passes through the polarization separation unit is extracted as analysis light. The detected color lights enter the cross dichroic prism 20 constituting the color synthesis optical system from different incident surfaces. Inside the cross dichroic prism 20, an R light reflecting dichroic film 20R and a B light reflecting dichroic film 20B are arranged orthogonally, the R light is reflected by the R light reflecting dichroic film 20R, and the B light reflecting dichroic film 20B. The B light is reflected and the G light is color-synthesized by passing through the two dichroic films. The color-combined light enters the projection lens 21. The projection lens 21 includes an aspheric lens made of a plastic optical member, a reflection mirror that changes the emission direction, and the like.

FIG. 1 shows a configuration diagram of the projection display device viewed from the Y-axis direction, that is, from the side. The light emitted from the projection lens 21 of the optical engine 10-1 enters the reflection mirror 23 through the phase plate 22 having a predetermined phase difference, and is projected onto the screen 24 composed of a Fresnel lens. The phase plate 22 makes the light emitted from the projection lens 21 pseudo-unpolarized light.
Here, the color unevenness of the projected image when the phase plate 22 is not used will be described. A Fresnel lens used as a screen is made of plastic, and has concentric circular saw-tooth grooves. Light emitted from the optical engine is incident on the screen, but is incident on the saw-tooth groove on the Fresnel lens at a large incident angle in a peripheral portion away from the optical axis.

  When the light is incident on a dielectric material, in this case plastic, at a large angle, the transmittance varies depending on the oscillation direction of the incident polarized light (for example, P-polarized light and S-polarized light). Accordingly, the amount of transmitted light varies depending on the ratio of the amount of light in the polarization oscillation direction (for example, P-polarized light and S-polarized light) of incident light.

Thus, since the light transmitted through the Fresnel lens has a polarization characteristic, the brightness on the screen changes depending on the polarization state of the incident light.
On the other hand, since the phase difference generated by reflection by the mirror arranged in the projection lens 21, transmission of the plastic member, and reflection by the bending mirror arranged in front of the screen differs depending on the color, the polarization state of light incident on the Fresnel lens is , R light, G light and B light are not the same. The state of polarization also varies depending on the direction in which the projected light is emitted from the projection lens. Therefore, the light passing through the Fresnel lens has a different light quantity ratio depending on the position on the screen, resulting in color unevenness in the screen surface.

  Accordingly, when considering a method for eliminating the color unevenness, it is presumed from the above description that the polarization states of the respective color lights and all the lights in the respective emission directions may be aligned in the same manner. However, it is difficult to align the polarization states in the same way for all directions of emission and for all color lights.

  Therefore, in the present invention, the polarization state is not made uniform, but rather the polarization state is greatly disturbed to make it a pseudo non-polarization state. By this method, the intensity ratio of the P-polarized component and the S-polarized component incident on the Fresnel lens is made uniform for each color light, thereby reducing color unevenness on the screen 24.

  Next, the phase plate 22 that makes the projected light pseudo-polarized will be described. First, the relationship between the degree of polarization of transmitted light (ratio of P-polarized component intensity and S-polarized component intensity) and the amount of phase difference when linearly polarized light enters the phase plate 22 will be described.

  FIG. 3 shows the wavelength dependence of the light intensity of the P-polarized component and S-polarized component of the emitted light when P-polarized light is incident on the phase plate 22. The phase difference of the phase plate 22 is 138 nm, and the orientation of its optical axis is 45 degrees with respect to the directions of P-polarized light and S-polarized light. The horizontal axis represents wavelength (nm) and the vertical axis represents intensity (relative value). Here, the polarization components are normalized so that the total sum of the polarization components is 1. Ip indicates the intensity of the P-polarized component after transmission, and Is indicates the intensity of the S-polarized component after transmission.

  In this case, the intensities of the P-polarized light and the S-polarized light substantially coincide with each other at a wavelength near 550 nm, but the difference in intensity between the P-polarized light and the S-polarized light increases as the distance from the wavelength increases. Specifically, the intensity of the S-polarized component is larger in the B light wavelength region (400 to 500 nm), whereas the intensity of the P-polarized component is conversely in the R light wavelength region (600 to 700 nm). growing. From this, in the phase plate having a phase difference of 138 nm, the polarization state in the B light wavelength region (ratio of S polarization component intensity and P polarization component intensity) and the polarization state in the R light wavelength region are greatly different. The amount of light transmitted through the screen also varies greatly between B, G, and R, and the screen transmitted light is colored, that is, color unevenness occurs. In other words, a pseudo non-polarized state cannot be obtained with a phase difference of about 138 nm.

  FIG. 4 shows the wavelength dependence of the light intensities of the P-polarized component and the S-polarized component of the emitted light when P-polarized light is incident on a phase plate having a phase difference of 5000 nm. In this phase plate, the intensity of the P-polarized component and the intensity of the S-polarized component change periodically. On average in the wavelength region of each color light (400 to 500 nm for B light, 500 to 600 nm for G light, and 600 to 700 nm for R light), the intensity ratio of each polarization component becomes equal. However, considering that the human visual sensitivity characteristic is highest near 555 nm, the polarization component ratio is biased on the long wavelength side in the B light wavelength region where the visual sensitivity is high, and also on the short wavelength side in the R light wavelength region. Is seen. In other words, the intensity changes only for about one cycle near 450 to 500 nm on the long wavelength side of B light, and the intensity changes only for one period or less near 600 to 650 nm on the short wavelength side of R light. It is still not enough to be regarded as pseudo-unpolarized light.

  FIG. 5 shows the wavelength dependence of the light intensity of the P-polarized component and the S-polarized component of the emitted light when P-polarized light is incident on a phase plate having a phase difference of 20000 nm. In this case, even in the R light having the longest period of intensity change, each polarization component has changed by four cycles or more, and the ratio of the P polarization component to the S polarization component is almost the same even in consideration of human visibility. Can be considered the same. Since the period of B light and G light is further increased, it can be said that by arranging this phase plate, the light emitted from the projection lens is made pseudo-polarized. That is, by disposing the phase plate after the projection lens, color unevenness on the screen can be reduced.

  The direction of the optical axis of the phase plate 22 is preferably about 45 degrees with respect to the X axis or Y axis in FIG. Since the light transmitted through the polarization beam splitters 17B, 17G, and 17R as P-polarized light is emitted from the optical engine 10-1, the light immediately after exiting the projection lens 21 is the strongest polarized light in the Y-axis direction or the X-axis direction. This is because it is expected that there are ingredients. Further, if the phase plate is rotated around the optical axis of the projection lens 21 so that the optical axis direction can be adjusted, color unevenness can be corrected according to variations in the optical engine and the projection lens, or characteristics specific to the Fresnel lens used. Can be brought to the best state.

  The phase difference of 20000 nm of the phase plate is a phase difference of about 36 wavelengths with respect to light having a wavelength of 550 nm. On the other hand, the phase difference generated by an aspheric lens made of a plastic optical member in the projection lens, a reflection mirror, or the like is about several wavelengths. Therefore, if there is such an amount as the phase difference of the phase plate, it can be said that the influence of the phase generated in the projection lens disturbing the pseudo non-polarized state by the phase plate can be ignored. Phase plate materials include plastic materials such as polycarbonate, birefringent materials with a uniaxial or biaxial crystal structure, such as sapphire glass and quartz plates, but the thickness depends on the amount of birefringence unique to these materials. It is only necessary to adjust the azimuth of the optical axis so that the phase difference becomes a value of 20000 nm or more.

  In this embodiment, a phase plate having a phase difference of about 20000 nm is used, but it is needless to say that a further non-polarized state can be achieved if a phase plate having a phase difference of 20000 nm or more is used. Furthermore, by adjusting the direction of the optical axis of the phase plate, it is possible to optimize the quasi-non-polarized state of the projection light emitted from the phase plate according to the variations of individual optical engines and the characteristics specific to the Fresnel lens used. Therefore, it is possible to obtain a projected image with reduced color unevenness on the screen on which the Fresnel lens is arranged. Note that the phase difference may be 20000 nm or less as long as it can be regarded as a practically non-polarized state from the state of color unevenness on the screen.

(Second Embodiment)
FIG. 6 shows a configuration diagram of an optical engine 10-2 used in the projection display device of the second embodiment. The configuration of the optical engine 10-2 of the present embodiment is different from the optical engine of the first embodiment in that a half-wave phase plate is disposed in the optical paths of the B light and R light analysis light. The configuration is the same.

  The light reflected and emitted from the reflection light valves 18B and 18R for the B light and the R light again enters the polarization beam splitters 17B and 17R. Of the incident light, P-polarized light that passes through the polarization separation unit is extracted as the analysis light. The B light and R light detection lights emitted from the polarization beam splitters 18B and 18R are incident on the half-wave phase plates 25B and 25R, respectively, and their polarization directions are rotated by 90 degrees to be converted to S-polarized light. The B light and R light analysis light converted to S-polarized light is incident on the cross dichroic prism 20 and is color-combined with P-polarization G light detection light. The color-combined light enters the projection lens 21 and is projected.

Considering the polarization characteristics of a general dichroic film, the B light reflected by the dichroic films 20R and 20B of the cross dichroic prism 20 is changed to S-polarized light, and the G light passing through it is changed to P-polarized light. The amount of light lost can be reduced.
The projection-type projection display device has the same configuration as that shown in FIG. 1, and the phase plate 22 having a phase difference of 20000 nm or more after the projection lens is emitted has an optical axis direction with respect to the X axis or the Y axis. It arrange | positions so that it may become 45 degree | times. By arranging the phase plate 22, the light emitted to the screen 24 can be regarded as pseudo non-polarized light, and the occurrence of color unevenness in the screen 24 is reduced.

  In this embodiment, each color light incident on the polarization beam splitter for each color light is reflected by the polarization separation unit and then incident on the reflection type light valve. Of the reflected emission light from the reflection type light valve, the polarization beam splitter. The P-polarized light that has passed through the polarization separation unit is used as the analysis light. For this reason, the B light and R light incident on the cross dichroic prism 20 are converted to S-polarized light by the half-wave phase plate. However, by changing the oscillation direction of the polarized light by the polarization conversion illumination device 12 by 90 degrees, the light transmitted through the polarization separation unit of the polarization beam splitter is incident on the reflection type light valve, and the light reflected and emitted from the reflection type light valve The S-polarized light reflected by the polarization separation unit of the polarization beam splitter may be configured to be the analysis light. In this case, a ½ wavelength phase plate is disposed only in the optical path of G light, R light and B light are incident on the cross dichroic prism as S-polarized light, and G light is incident as P-polarized light. Even if it is this structure, there can exist the same effect.

  In any of the above configurations, a half-wave phase plate may be disposed between the G polarization beam splitter and the cross dichroic prism so that the G light incident on the cross dichroic prism is used as S-polarized light. Good.

(Third embodiment)
FIG. 7 shows a configuration diagram of an optical engine 10-3 used in the projection display device of the third embodiment. The configuration of the optical engine 10-3 of the present embodiment is the same as that of the optical engine 10-1 of the first embodiment in that a quarter-wave phase plate 26 is disposed between the cross dichroic prism 20 and the projection lens 21. Is different.

  The color-combined light emitted from the cross dichroic prism 20 passes through the quarter wavelength plate 26 and then enters the projection lens 21. The quarter-wave phase plate 26 prevents the light reflected from the surface of the lens member in the projection lens 21 and going back to the reflective light valve from entering the projection lens again and being projected as ghost light. it can. Since the light passing through the quarter-wave plate 26 is R light, G light, and B light, the quarter-wave phase plate is usually optimized for G light, which is the center wavelength of each color.

  In this case, the light emitted from the cross dichroic prism 20 is converted into circularly polarized light by the ¼ wavelength phase plate 26, B light and R light are converted into elliptically polarized light, and the polarization state is different for each color light. become. Therefore, if the phase plate 22 is not disposed, the difference in polarization state of each color light by the quarter wavelength phase plate 26 appears as color unevenness when entering the screen 24. However, as shown in FIG. 1, the phase plate 22 having a phase difference of 20000 nm or more after the projection lens 21 exits is disposed so that the optical axis direction thereof is 45 degrees with respect to the X axis or the Y axis. By arranging the phase plate 22, the light emitted to the screen 24 can be regarded as pseudo non-polarized light, and the occurrence of color unevenness in the screen 24 is reduced.

(Fourth embodiment)
FIG. 8 shows a configuration diagram of a projection display device according to the fourth embodiment, and FIG. 9 shows a configuration diagram of an optical engine 10-4 used in the projection display device. The basic configuration of the optical engine 10-4 of the present embodiment is the same as that of the optical engine 10-1 of the first embodiment, except that the light valve used is a transmissive light valve.

  In FIG. 9, the B light, G light, and R light, which are color-separated by the same color separation optical system as in the first embodiment, change the traveling direction by the deflecting mirrors 31B, 31G, 31R, and transmit S-polarized light. The light enters the transmissive light valves 33B, 33G, and 33R through the polarizers 32B, 32G, and 32R that absorb the P-polarized light. In this embodiment, light polarized in the direction perpendicular to the paper surface and in the Z-axis direction is S-polarized light. Each incident color light is emitted after being modulated by the respective color signal, transmitted through the P-polarized light, and incident on the polarizers 34B, 34G, and 34R that absorb the S-polarized light, and the P-polarized light is taken as the analysis light. It will be. The analyzed light is incident on the cross dichroic prism 20 from different incident surfaces and is color-synthesized. The color-synthesized light enters the projection lens 35 and is projected.

  As shown in FIG. 8, the light emitted from the projection lens 35 of the optical engine 10-4 is incident on the phase plate 22 having the characteristics shown in FIG. 5, and is reflected after being converted into pseudo non-polarized light. The light is reflected by the mirror 23 and enters the screen 24 using a Fresnel lens. Since it is converted into pseudo non-polarized light by the phase plate 22, a good projection image with reduced color unevenness can be obtained even if it is incident on the screen 24.

  Also in the present embodiment, as in the second embodiment, the R light and B light detection light may be S-polarized light and incident on the cross dichroic prism. In the first to fourth embodiments, the light from the light source is color-separated and a light valve is arranged for each color light. However, the light from the light source is time-sequentially processed by the time-series color separation optical system. Even in a projection type display device that performs color separation, modulates with one light valve, and projects the modulated light of each color light in time series, a phase plate having a phase difference of about 20000 nm is disposed between the projection lens and the screen. As in the above embodiment, color unevenness in the projected image can be reduced.

  In the embodiments described so far, the phase plate 22 is disposed between the projection lens and the screen. However, if the light projected on the screen can be made non-polarized in a pseudo manner, the phase plate 22 is disposed. Not limited to. For example, you may arrange | position in a projection lens, ie, the lens which comprises a projection lens, or between mirrors.

The block diagram of the rear projection type display apparatus of 1st, 2nd, 3rd embodiment. The block diagram of the optical engine of 1st Embodiment. The characteristic view which shows the optical characteristic of the phase plate of phase difference 138nm. The characteristic view which shows the optical characteristic of the phase plate of phase difference 5000nm. The characteristic view which shows the optical characteristic of the phase plate of phase difference 20000nm. The block diagram of the optical engine of 2nd Embodiment. The block diagram of the optical engine of 3rd Embodiment. The block diagram of the rear projection type display apparatus of 4th Embodiment. The block diagram of the optical engine of 4th Embodiment.

Explanation of symbols

10-1, 10-2, 10-3, 10-4 Optical engine 11 Light source 12 Polarization conversion illumination device 13 Cross dichroic mirrors 14, 15, 31R, 31G, 31B Deflection mirror 16 Dichroic mirrors 17R, 17G, 17B Polarization beam splitter 18R, 18G, 18B Reflective light valve 20 Cross dichroic prism 21, 35 Projection lens 21M Reflection mirror 22 in projection lens 22 Phase plate 23 Reflection mirror 24 Screen 25R, 25B 1/2 wavelength phase plate 26 1/4 wavelength phase plate 32R, 32G, 32B, 34R, 34G, 34B Polarizers 33R, 33G, 33B Transmission type light valve

Claims (11)

A light valve that modulates the light from the light source;
A projection lens that projects light modulated by the light valve onto a transmissive screen;
A projection display device, comprising: a polarization conversion member that makes the polarization state of light projected on the transmission screen pseudo-unpolarized. The projection display device according to claim 1, wherein the polarization conversion member is disposed between the projection lens and the transmission screen. A color separation optical system that separates light from the light source into R (red) light, G (green) light, and B (blue) light;
A reflective light valve arranged for each color light;
Each color that separates the color-separated R light, G light, and B light, enters the reflective light valve disposed for each color light, and analyzes the light emitted from the reflective light valve A polarizing beam splitter arranged for each light;
A color synthesizing optical system for synthesizing each color light detected by the polarizing beam splitter;
A projection lens that projects the color-synthesized light onto a transmission screen;
A projection display device, comprising: a polarization conversion member that is disposed between the projection lens and the transmissive screen and makes a polarization state of light projected on the transmissive screen pseudo-unpolarized. . A half-wavelength phase plate disposed in the optical path of each of the R light and the B light between the polarizing beam splitter and the color combining optical system, or the optical path of the G light,
The color synthesis optical system includes a first dichroic film that reflects R light and a second dichroic film that reflects B light, which are arranged orthogonally,
With respect to the first dichroic film and the second dichroic film, the polarization directions of R light and B light incident on the color synthesis optical system are S-polarized light, and G light is P-polarized light. The projection display device according to claim 3. 5. The projection display device according to claim 3, further comprising a ¼ wavelength phase plate disposed between the color synthesis optical system and the projection lens. 6. A color separation optical system that separates light from the light source into R (red) light, G (green) light, and B (blue) light;
A light valve arranged for each color light;
A polarizer that polarizes the color-separated R light, G light, and B light and enters the light valve disposed for each color light;
An analyzer for analyzing the light emitted from the light valve;
A color synthesizing optical system that synthesizes each color light analyzed by the analyzer;
A projection lens that projects the color-synthesized light onto a transmission screen;
A projection display device, comprising: a polarization conversion member that is disposed between the projection lens and the transmissive screen and makes a polarization state of light projected on the transmissive screen pseudo-unpolarized. . A half-wavelength phase plate disposed in the optical path of each of R light and B light between the analyzer and the color synthesis optical system, or the optical path of G light,
The color synthesis optical system includes a first dichroic film that reflects R light and a second dichroic film that reflects B light, which are arranged orthogonally,
With respect to the first dichroic film and the second dichroic film, the polarization directions of R light and B light incident on the color synthesis optical system are S-polarized light, and G light is P-polarized light. The projection display device according to claim 6. The projection display device according to any one of claims 1 to 7, wherein the polarization conversion member is a phase plate having a phase difference of 20000 nm or more. 9. The projection type display device according to claim 8, wherein the direction of the optical axis of the phase plate is arranged at an angle of 45 degrees with the polarization direction of each of the analyzed color lights. The projection display device according to claim 8, wherein an optical axis of the phase plate can rotate around an optical axis of the projection lens. The projection display device according to claim 1, wherein the transmissive screen is made of a Fresnel lens.