JP2007304607A - Projection type display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projection type display device which does not cause color irregularity by collapse of the white balance on a screen. <P>SOLUTION: The projection type display device comprises: three light valves each of which has at least a polarizing plate on each light emission side, and modulates and emits the light of each color component of red, green and blue; a color synthesizing optical system for synthesizing each emission light from each light valve; and a projection lens of projecting the synthesized light to the screen, wherein a polarizing converting means for converting a polarization state of light of each color component is disposed such that at least the ratio of light quantity in the horizontal direction to light quantity of vertical direction is substantially equal in each color component. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a projection display device using a light valve, and more particularly to a projection display device using a transmissive liquid crystal light valve.

  Among projection display devices using a light valve for light modulation, a projection display device using a liquid crystal light valve called a so-called liquid crystal projector is capable of high-definition and large-screen display. It has the potential to replace it.

  As a conventional projection display device, a transmission axis (or absorption axis) of 45 degrees oblique to the horizontal direction of the projection screen is provided on the light exit side of a normally white liquid crystal panel using TN (twisted nematic) liquid crystal. There is a liquid crystal projector in which a polarizing plate having a polarizing plate is disposed, and a liquid crystal projector in which a polarizing plate having a transmission axis (or absorption axis) parallel or perpendicular to the horizontal direction is disposed.

  Light emitted from these conventional liquid crystal projectors is projected onto the screen after being converted into polarized light that vibrates in a direction parallel to the long side or the short side of the display area of the rectangular screen by a polarization conversion element or the like. In addition, one of the three primary colors has a polarization direction substantially orthogonal to the other two colors.

  An example of a schematic configuration of this conventional projection display apparatus will be briefly described with reference to FIG. FIG. 30 shows a conventional projection display device using a transmissive liquid crystal light valve. The projection optical system of the projection display device includes a light source 1, liquid crystal light valves 21R, 21G, and 21B, dichroic mirrors 4 and 6, a dichroic prism 14, a projection lens 16, and the like. The liquid crystal light valves 21R, 21G, and 21B generally have a structure in which both surfaces of the liquid crystal panels 20R, 20G, and 20B are sandwiched between polarizing plates. Liquid crystal light valves 21R, 21G, and 21B shown in FIG. 30 are provided with polarizing plates 20Rp, 20Gp, and 20Bp on the light emission side of the liquid crystal panels 20R, 20G, and 20B, respectively, and a common polarization conversion device on the light incident side. 2 is arranged in the vicinity of the light source 1. Further, half-wave plates 20Ri ′, 20Gi ′, and 20Bi ′ are inserted into the light incident sides of the liquid crystal light valves 21R, 21G, and 21B, respectively, and the half-wave plates 20Ri and 20Gi are respectively inserted into the light emission sides. , 20Bi are inserted.

  The three liquid crystal light valves 21R, 21G, and 21B form an image by intensity-modulating light of the three primary colors of red (R), green (G), and blue (B) according to the image signal, respectively, and color combining optics For example, the light is emitted to a dichroic prism 14 which is a system. The liquid crystal light valve 21G is disposed at a position where the emitted light passes through the dichroic prism 14 and is emitted from the prism 14. The liquid crystal light valve 21R reflects the emitted light on the dichroic surface 14b in the dichroic prism 14. The liquid crystal light valve 21 </ b> B is arranged at a position where the emitted light is reflected by the dichroic surface 14 a in the dichroic prism 14 and emitted from the prism 14.

  In the projection display device shown in FIG. 30, the white light emitted from the light source 1 passes through the polarization conversion device 2 and is linearly polarized light having a polarization direction (indicated by an arrow in the drawing) parallel to the paper surface (p The light enters the dichroic mirror 4 as polarized light. The dichroic mirror 4 is configured to reflect blue light and transmit other light, and the blue light reflected by the dichroic mirror 4 is further reflected by the mirror 12 and enters the half-wave plate 20Bi ′. . On the other hand, light other than blue light passes through the dichroic mirror 4 and enters the next stage dichroic mirror 6. The blue light incident on the half-wave plate 20Bi 'has its polarization direction rotated by 45 °, and substantially coincides with the alignment direction of the liquid crystal molecules on the light incident side substrate side of the liquid crystal panel 20B of the blue liquid crystal light valve 21B. The incident light enters the liquid crystal panel 20B with the polarization direction.

  On the other hand, the light transmitted through the dichroic mirror 4 enters a dichroic mirror 6 configured to reflect green light and transmit red light, and the green light reflected by the dichroic mirror 6 is reflected by the half-wave plate 20Gi. 'Is incident. The polarization direction of the green light incident on the half-wave plate 20Gi ′ is rotated by 45 °, and is almost in the alignment direction of the liquid crystal molecules on the substrate side of the light incident side of the liquid crystal panel 20G of the green liquid crystal light valve 21G. It enters the liquid crystal panel 20G with the coincident polarization direction. The red light transmitted through the dichroic mirror 6 is reflected by the mirrors 8 and 10 and enters the half-wave plate 20Ri ′. The polarization direction of the red light incident on the half-wave plate 20Ri ′ is rotated by 45 °, and is approximately in the alignment direction of the liquid crystal molecules on the substrate side of the light incident side of the liquid crystal panel 20R of the liquid crystal light valve 21R for red. The light enters the liquid crystal panel 20R with the coincident polarization direction.

  The substrates on the light emission side of the liquid crystal panels 20R, 20G, and 20B are rubbed in a direction orthogonal to the alignment direction of the liquid crystal molecules on the substrate side on which the light is incident. Therefore, any liquid crystal panel 20R, 20G , 20B, a TN (twisted nematic) liquid crystal layer is also formed. Each of the liquid crystal panels 20R, 20G, and 20B is an active matrix type liquid crystal panel having a plurality of pixel regions in which p-Si TFTs (thin film transistors using polysilicon as a channel layer) are formed as switching elements.

  The blue light incident on the blue liquid crystal light valve 21B is light-modulated by the driving of the switching element and emitted from the polarizing plate 20Bp in the liquid crystal panel 20B. The light transmission axis of the polarizing plate 20Bp is set so as to substantially coincide with the alignment direction of the liquid crystal molecules on the substrate side on the light emission side of the liquid crystal panel 20B. Therefore, the liquid crystal panel 20B has a voltage applied to the TN liquid crystal layer in the pixel region. It is driven by a so-called normally white system that achieves the maximum light transmittance when no light is applied. The blue light emitted from the polarizing plate 20Bp is then incident on the half-wave plate 20Bi, the polarization orientation is converted into a polarization orientation perpendicular to the paper surface, and is incident on the dichroic surface 14a and reflected as s-polarized light. Be made.

  Similarly, red light incident on the red liquid crystal light valve 21R is also light-modulated by the driving of the switching element and emitted from the polarizing plate 20Rp in the liquid crystal panel 20R. The light transmission axis of the polarizing plate 20Rp is also set so as to substantially coincide with the alignment direction of the liquid crystal molecules on the substrate side of the light emission side of the liquid crystal panel 20R. Therefore, the liquid crystal panel 20R is driven by a so-called normally white method. It has become so. The red light emitted from the polarizing plate 20Rp is then incident on the half-wave plate 20Ri, the polarization orientation is converted to a polarization orientation perpendicular to the paper surface, and is incident on the dichroic surface 14b and reflected as s-polarized light. Be made.

  On the other hand, the green light incident on the green liquid crystal light valve 21G is light-modulated by the driving of the switching element and emitted from the polarizing plate 20Gp in the liquid crystal panel 20G. The light transmission axis of the polarizing plate 20Gp is also set so as to substantially match the alignment direction of the liquid crystal molecules on the substrate side of the light emission side of the liquid crystal panel 20G. Therefore, the liquid crystal panel 20G is driven by a so-called normally white system. It has become so. The green light emitted from the polarizing plate 20Gp is then incident on the half-wave plate 20Gi, the polarization direction of which is converted into a polarization direction parallel to the paper surface, and passes through the dichroic surfaces 14a and 14b as p-polarized light. .

  In this way, the blue and red light reflected in the dichroic prism 14 and the green light transmitted through the dichroic prism 14 are combined and emitted, enlarged by the projection lens 16, and screen (not shown). A color image is projected on top.

In the conventional projection display apparatus shown in FIG. 30, light transmitted through the dichroic prism 14 is p-polarized light, and light reflected within the prism 14 is s-polarized light. By doing so, spectral separation characteristics on the dichroic surfaces 14a and 14b, which are generated when all the light incident on the dichroic prism 14 is s-polarized light or when each incident light is a mixed light of s-polarized light and p-polarized light. In addition, it is possible to prevent a decrease in spectrum synthesis characteristics. Accordingly, the cut-off characteristics of the reflection spectrum and transmission spectrum on the dichroic surfaces 14a and 14b are improved, and the image quality can be improved. This is a technique disclosed in Patent Document 1 and Patent Document 2.
JP-A-6-222321 JP-A-7-5410 Japanese Patent Laid-Open No. 10-186548 Japanese Patent Laid-Open No. 7-230072 JP 9-318922 A

  By the way, with the recent increase in the projection area of projection-type display devices and the increase in display definition, accurate gradation display with reduced color unevenness and color shift of the display image on the screen has become particularly demanded. It is coming. However, the inventors of the present application have found that even if a method based on the above-described prior art is used, a situation in which sufficient gradation display, color unevenness, and color shift cannot be reduced occurs. This is because the leakage current flows when unnecessary light is irradiated to the channel region of the p-Si TFT provided in each pixel of the liquid crystal panel of the liquid crystal light valve, so that the voltage applied to each pixel of the liquid crystal panel fluctuates. This is because the original gradation display cannot be performed.

  Here, the structure of a liquid crystal panel using p-Si TFTs as switching elements will be described with reference to FIG. FIG. 31 shows a partial cross section of one pixel region of the liquid crystal panel. In an active matrix type liquid crystal display device using a switching element 104 as well as a liquid crystal panel of a projection display device, as shown in FIG. 31, the switching element 104 is provided for each pixel region on the array substrate 100 made of a transparent glass substrate. Is formed. A display electrode 110 made of a transparent electrode such as ITO (Indium Tin Oxide) is formed on the pixel region of the array substrate 100 via an insulating film 108. A counter substrate 102 made of a transparent glass substrate is provided facing the array substrate 100 with a predetermined cell gap, and a common electrode 112 made of a transparent electrode such as ITO is formed on the side surface of the array substrate of the counter substrate 102. . A liquid crystal 106 is sealed in a TN liquid crystal layer between the array substrate 100 and the counter substrate 102. Although not shown, an alignment film made of, for example, polyimide is formed on the contact surface of the array substrate 100 and the counter substrate 102 with the TN liquid crystal layer at least in the light transmission region. The rubbing process etc. which prescribe | regulate a direction are given.

  A switching element 104 shown in FIG. 31 is a p-Si TFT and functions as an n-type polysilicon layer 120, 126 serving as a drain region and a source region on the array substrate 100 and a channel layer between the drain region and the source region. A polysilicon layer 124 is formed. A gate insulating film 122 made of, for example, SiO 2 (silicon oxide film) is formed on the polysilicon layer 124, and a gate electrode 128 is formed on the gate insulating film 122. For example, an Al (aluminum) source electrode 130 is formed on the n-type polysilicon layer 120 serving as the source region, and a display electrode 110 is connected to the n-type polysilicon layer 126 serving as the drain region.

  In addition, a light shielding film (black matrix) 114 that shields incident light incident from the outside of the counter substrate 102 is formed on the counter substrate 102 above the p-Si TFT.

  In the liquid crystal panel configured as described above, the array substrate 100 side is arranged toward the dichroic prism 14 side, and light incident from the light source 1 through the dichroic mirrors 4 and 6 enters from the counter substrate 102 side. Yes. In such an arrangement configuration of the liquid crystal panel, light incident from the counter substrate 102 side is shielded by the light shielding film 114 provided on the counter substrate 102 side so as not to irradiate the switching element 104 of the liquid crystal panel.

  However, if stray light in the projection display device or unnecessary light having a shifted wavelength enters the dichroic prism 14 and enters the liquid crystal panel from the array substrate 100 side, a switching element in which a light shielding film is not formed. 104, the back surface is irradiated, a leakage current is generated, the switching element 104 is turned on, and a voltage is applied between the display electrode 110 and the common electrode 112, and the orientation of the liquid crystal molecules in the region is changed. Gradation display becomes impossible. In particular, in a p-Si TFT having excellent responsiveness, a leak current due to short-wavelength light cannot be ignored. If the light separation characteristic of the dichroic prism 14 is perfect, the extra short wavelength light that has entered the dichroic prism 14 from the blue liquid crystal light valve 21B that emits light in the blue wavelength band on the short wavelength side is almost all. Reflected by the dichroic surface 14a and not incident on the other red and green liquid crystal light valves 21R and 21G, no extra leakage current is generated in those TFTs.

  However, if extra short-wavelength light is incident on the dichroic prism 14 from the red and green liquid crystal light valves 21R and 21G that emit light in the red and green bands on the longer wavelength side than the blue band, these extra lights are added. The short wavelength light is transmitted or reflected by the dichroic surface 14b and enters the blue liquid crystal light valve 21B. As a result, an extra leakage current is generated in the p-Si TFT of the blue liquid crystal light valve 21B.

  FIG. 32 shows the light resistance of the p-Si TFT. The horizontal axis indicates the amount of white light incident on the liquid crystal panel in logarithm, and the vertical axis indicates the gradation of the liquid crystal panel based on the leakage current generated in the p-Si TFT. The degree of display error is shown as the amount of leakage. The amount of incident white light is the total amount of red, green, and blue, and the light amount ratio is “red: green: blue = 3: 12: 1”. In the drawing, the leak amount characteristic at the blue liquid crystal light valve 21B is indicated by a thick solid line (B), the leak amount characteristic at the red liquid crystal light valve 21R is indicated by a broken line (R), and the green liquid crystal light valve 21G. Is shown by a thin solid line (G). As can be seen from FIG. 32, the leakage amount increases with an increase in the amount of light incident on the liquid crystal panel in any liquid crystal light valve, but the increase in the leakage amount in the blue liquid crystal light valve 21B is particularly significant. . For example, in the case of a projection display device with a light quantity incident on the liquid crystal panel of 5000000 lx, the amount of leakage at the blue liquid crystal light valve 21B is 1.25, and other red and green liquid crystal light valves. It can be seen that the gradation change is larger than the leak amount of 0.7 to 0.75 of 21R and 21G. Thus, if the balance of red, green, and blue gradations is lost regardless of the original modulation signal due to the influence of unnecessary light, the color of the light synthesized by the dichroic prism 14 will be different from the desired one. This causes a problem that display quality deteriorates.

  Light emitted from the conventional liquid crystal projector to the screen is converted by a polarization conversion element or the like, and for example, one of the three primary colors is projected as polarized light that vibrates in the horizontal direction with respect to the screen, and the other two colors are projected onto the screen. On the other hand, it is projected as polarized light that vibrates in the vertical direction. However, most screens, including projection screens consisting of a combination of a lenticular lens and a Fresnel lens, have different scattering characteristics depending on the polarization direction, and as a result, the scattering of the three primary colors is different. There are problems that unevenness occurs and color shift occurs in which the color changes depending on the viewing position.

  Further, in the projection display apparatus shown in FIG. 30, since the image is synthesized by the dichroic prism 14 which is a glass block, there is no distortion or misalignment of the transmission and reflection surfaces compared to the dichroic mirror of the flat plate. Although the occurrence of pixel misalignment can be prevented, there is a problem that the optical path lengths from the light source 1 to the light valves 21R, 21G, and 21B of the respective colors are different. In FIG. 30, the red light path is longer than the other green and blue light paths, the light quantity balance of red, green and blue is shifted, and the chromaticity is shifted when a mixed color display such as white display is performed on the projected image. A problem has occurred.

  On the other hand, in the conventional projection display device shown in FIG. 33, the light from the light source 1 is separated into red, green and blue by two dichroic mirrors 140 and 142 and a total reflection mirror 144, and then three liquid crystal panels 156R. 156G and 156B are irradiated to modulate the image. Thereafter, the images are synthesized by the two dichroic mirrors 148 and 150 and the total reflection mirror 146, and then enlarged and projected by the projection lens. Note that the light valves 21R, 21G, and 21B of the projection display device shown in FIG. 33 are arranged in order from the light incident direction, condenser lenses 152R, 152G, and 152B, incident polarizing plates 154R, 154G, and 154B, and liquid crystal panels 156R and 156G. 156B and exit polarizing plates 158R, 158G, and 158B.

  33 is transmitted through the dichroic mirrors 148 and 150 and the total reflection mirror 146 that synthesize the image light of each color image-modulated by the light valves 21R, 21G, and 21B, and the distortion of the reflection surface. If there is a positional shift at the time of arrangement, there is a problem that an image shift is likely to occur at the time of image composition, and a defect called a pixel shift is likely to occur in an enlarged projected image by the projection lens. Therefore, in order to prevent the distortion and displacement of the mirror, it is necessary to increase the mirror thickness or improve the mirror fixing method. However, when the thickness of the mirror is increased, there arises a problem that the aberration of the transmitted image light is enlarged. In addition, the improvement of the mirror fixing method has a problem of high accuracy and high price of the fixing jig.

  Further, projection display devices for displaying a screen of a personal computer or a video on a large screen have a tendency to further increase the number of display pixels as the signal source becomes higher in definition. For this reason, as described above, a projection display apparatus mainly uses a white light source and separates and combines white light into three primary colors. In order to increase the definition of the device and improve portability, it is necessary to form the liquid crystal panel as small as possible and to increase the number of pixels. As the pixel pitch decreases, it is necessary to reduce astigmatism as much as possible to improve display quality. For this reason, a projection display device has also been proposed in which a dichroic mirror for synthesizing all colors is sandwiched between glasses to form a prism (Japanese Patent Laid-Open No. 11-31847). This proposed projection display apparatus is shown in FIG. The non-polarized white light emitted from the light source 221 is color-separated by the dichroic mirrors 224 and 229, and green light enters the liquid crystal panel 231 and red light enters the liquid crystal panel 231 and blue light enters the 226 through the polarizing plate. After being spatially modulated by each liquid crystal panel, it passes through the exit-side polarizing plate to become p-polarized light, undergoes color synthesis through the dichroic mirror 228, the mirror 233, and the dichroic prism 234, and reaches the projection lens 235.

  Due to the nature of the dichroic prism 234, the reflection characteristics of the dichroic prism in the p-polarized light composition are low, so the amount of red and blue light reflected by the dichroic prism 234 is reduced, and the balance of the light amounts of the respective colors is disrupted to display an image to be projected. There is a problem that the quality is drastically reduced.

  An object of the present invention is to provide a high-quality projection display device excellent in gradation display.

  A further object of the present invention is to provide a high-quality projection display device having excellent color reproducibility.

  Still another object of the present invention is to provide a projection display apparatus having a light valve that modulates incident light by driving a switching element, and capable of performing high-quality gradation display by preventing the occurrence of leakage current in the switching element. To provide a mold display device.

  Still another object of the present invention is to display a wide viewing angle with excellent color reproducibility without losing the white balance of the three primary colors of red (R), green (G), and blue (B) when projected onto a screen. An object of the present invention is to provide a projection display device that can perform the above-described operation.

  A further object of the present invention is to provide a projection display device free from pixel shift and chromaticity shift.

  The above purpose is to combine three light valves each having a polarizing plate at least on the light emission side and modulating and emitting light of each color component of red, green, and blue, and color synthesis of each light emitted from each light valve In a projection display device comprising a color synthesis optical system that performs projection and a projection lens that projects color-synthesized light onto a screen, the ratio of at least the horizontal light quantity and the vertical light quantity on the screen is approximately equal for each color component. As described above, this is achieved by a projection display device comprising polarization conversion means for converting the polarization state of light of each color component.

  In the projection display device according to the aspect of the invention, the polarization conversion unit converts each color-combined light into substantially circularly polarized light. The polarization converter has a quarter-wave plate disposed on the light exit side of the color synthesis optical system. The quarter-wave plate has an optical axis that forms an angle of approximately 45 ° with respect to the light transmission axis or light absorption axis of the polarizing plate.

  According to this configuration, each of the image lights color-synthesized by the color synthesis optical system is linearly polarized light, but is converted into circularly polarized light by the polarization conversion means before entering the projection lens. Accordingly, the image light diffused by the projection lens and emitted is projected onto the screen as circularly polarized light. For example, if the screen consists of a combination of a Fresnel lens and a lenticular lens, the color tone of the image changes depending on the angle facing the screen due to the difference in refraction characteristics on the screen if each light of red, green and blue is linearly polarized light. However, such a problem does not occur with the image light emitted by the configuration of the present invention, and a high-quality image can be provided. Moreover, a quarter wavelength plate can be used as a circularly polarized light conversion element.

  In the projection display device according to the aspect of the invention, the polarization conversion unit may convert each of the color-synthesized lights to an angle formed by the polarization azimuth of the light of one color component and the polarization azimuth of the light of the other color component. The equal line is converted into linearly polarized light that substantially matches either the horizontal line or the vertical line of the screen. In addition, the polarization conversion means makes the polarization azimuth of light of one color component and the polarization azimuth of light of another color component substantially orthogonal. The polarization conversion means has a half-wave plate disposed on the light exit side of the color synthesis optical system. The half-wave plate has an optical axis that forms an angle of approximately 22.5 ° with respect to the light transmission axis or light absorption axis of the polarizing plate.

  The projection display device of the present invention further includes a screen on which light projected from the projection lens enters, and the screen includes a Fresnel lens and a lenticular lens. By doing so, the ratio of the light intensity of the horizontal component and the vertical component of the screen can be made substantially the same for the three primary color lights. Therefore, the screen light distribution characteristics of the three primary color lights are the same on the screen, and high-quality image display without color unevenness and color shift can be performed with high illuminance.

  Next, the principle of a projection display device that is realized by the present invention and has no pixel shift or chromaticity deviation will be described with reference to FIG. The projection display device includes a light source 1, a first dichroic mirror 140 ', a second dichroic mirror 142', a total reflection mirror 144 ', each light valve 21R, 21G, 21B, and a first dichroic prism. 160, a second dichroic prism 162, a total reflection prism 164, and a projection lens 16.

  In the present invention, the optical path lengths in the color separation optical system from the light source 1 to the light valves 21R, 21G, and 21B for each color can be arranged equally as in the conventional FIG. 33. Therefore, the projection shown in FIG. There is no problem of chromaticity misalignment due to the difference in optical path length as in the case of the type display device.

  Further, the color synthesizing optical system from the light valves 21R, 21G, and 21B for each color to the projection lens 16 is similar to the conventional example of FIG. 30 in that the first dichroic prism 160 and the second dichroic prism are glass blocks. It is composed only of the prism 162 and the total reflection prism 164, and it is difficult for the mirror surface to be distorted and misaligned, so that the pixel misalignment occurring in the conventional example of FIG. 33 can be prevented.

  However, a prism using a glass block has a problem that it is more expensive than a dichroic mirror in which a filter is attached to a glass plate. In particular, if a band-pass filter that transmits or reflects only a certain wavelength range in the visible light region is used, the film configuration for obtaining good filter characteristics becomes complicated, and the cost is further increased. In order to satisfy this, there is a problem in that the manufacturing yield is also lowered, and the cost is further increased. Therefore, in the configuration of the present invention, unlike the case shown in FIG. 33, first, green and red are synthesized by the first dichroic prism 160 and then synthesized by the second dichroic prism 162. Yes. That is, color separation / color synthesis is performed only with a low-pass filter or a high-pass filter. With this configuration, it is possible to realize a projection optical system in which the increase in cost is small and there is no problem of the chromaticity deviation and the pixel deviation.

  Further, in the projection display device of the present invention, in order to eliminate the reflection of p-polarized light having poor dichroic prism reflection characteristics, the light reflected from the dichroic prism out of the combined light is made to be s-polarized light. If the light transmitted through the dichroic prism is made the same s-polarized light as the reflected light, the cut wavelength for switching between transmission and reflection of the dichroic surface varies depending on the light having an angle with respect to the optical axis and manufacturing errors of the dichroic prism. End up. In order to prevent such variations in projected display colors due to variations in reflection / transmission colors in the dichroic prism, in the present invention, at least transmission light having a wavelength close to the light reflected in the dichroic prism is set as p-polarized light.・ Insensitive to variations in prism cut wavelength.

  In this way, the reflected light in the dichroic prism is s-polarized light, and the transmitted light of a color close to this is p-polarized light, so that color synthesis independent of variations in cut wavelength of the dichroic prism can be obtained and image display Quality can be improved. Further, a brighter projected display image can be obtained by adjusting the polarization direction of light in color separation / combination by designing an optical member in accordance with this.

  As described above, according to the present invention, a high-quality projection display device excellent in gradation display can be realized. Furthermore, according to the present invention, it is possible to realize a high-quality projection display device excellent in color reproducibility. Furthermore, according to the present invention, in a projection display device having a light valve that modulates incident light by driving a switching element, a projection type capable of preventing a leakage current from being generated in the switching element and displaying a high-quality gradation display. A display device can be realized. Furthermore, according to the present invention, when projected onto the screen, the white balance of the three primary colors of red (R), green (G), and blue (B) is not lost, and the color reproducibility is excellent, and a wide viewing angle is displayed. It is possible to realize a projection display device that can Further, even when the screen is observed obliquely, it is possible to obtain a good display image with no color unevenness and little color shift.

  In addition, according to the present invention, since the optical path length for each color in the color separation optical system can be made equal, it is possible to prevent chromaticity deviation due to the difference in optical path length. In addition, since the color composition optical system hardly causes distortion of the mirror surface and displacement of the mounting position, pixel displacement can be prevented.

  In addition, according to the present invention, the optical member can be efficiently transmitted and reflected, and astigmatism can be corrected to a substantially sufficient degree with respect to red light. Therefore, it is possible to obtain a bright, stable image with no blur. Also, by combining red and green, which have a large amount of light among the three colors, first, the display pixel alignment accuracy can be improved, and the assembly efficiency of the device can be improved, thus reducing the cost of device manufacturing. Will be able to.

  A projection display device according to a first embodiment of the present invention will be described with reference to FIGS. First, a schematic configuration of the projection display apparatus according to the present embodiment will be described with reference to FIG.

  The projection optical system of the projection display apparatus according to the present embodiment includes a light source 1 having a lamp fixed at a first focal point of an elliptical mirror whose inner surface is mirror-finished, for example. White light including red (R), green (G), and blue (B) emitted from the light source 1 is shaped into substantially parallel light via a shaping optical system (not shown) and enters the polarization conversion device 2. Yes. In this example, white light from the light source 1 enters the polarization conversion device 2 and is converted into linearly polarized light (p-polarized light) having a polarization orientation (indicated by an arrow in the figure) parallel to the paper surface, and the dichroic mirror 4 Is incident on.

  The dichroic mirror 4 is formed to reflect the blue band light of the incident white light and transmit the other light. Accordingly, the light in the blue band is reflected by the dichroic mirror 4 and further reflected by the mirror 12, and is incident on the half-wave plate 20Bi 'and its polarization direction is rotated by 45 °, so that the blue liquid crystal light valve 21B The liquid crystal panel 20B is incident on the liquid crystal panel 20B with a polarization orientation substantially coinciding with the alignment direction of the liquid crystal molecules on the light incident side substrate side. The blue liquid crystal light valve 21B includes a transmissive liquid crystal panel 20B and a polarizing plate 20Bp. In general, a liquid crystal light valve having a structure in which both sides of a liquid crystal panel are sandwiched by polarizing plates is used. In the present embodiment, as shown in FIG. 1, a polarizing plate 20Bp is provided on the light emission side of the liquid crystal panel 20B. A polarization conversion device 2 that is provided and shared with the other liquid crystal light valves 21R and 21G is disposed in the vicinity of the light source 1 on the light incident side. The liquid crystal light valve transmits light guided from the light source 1 and reflects an image on a screen (not shown), and a reflection that reflects light from the light source 1 and displays an image on the screen. There is a type liquid crystal light valve, but the projection type display apparatus of the present embodiment shown in FIG. 1 uses a transmission type liquid crystal light valve.

  Thus, the blue band light that has reached the blue liquid crystal light valve 21B first enters the liquid crystal panel 20B. Similarly to the liquid crystal panel described with reference to FIG. 30, the liquid crystal panel 20B has an active matrix type liquid crystal panel structure having a plurality of pixel regions in which p-Si TFTs are formed as switching elements. Blue band light is incident from the counter substrate 102 side toward the liquid crystal layer 106.

  The array substrate 100 side which is the light emission side substrate of the liquid crystal panel 20B is rubbed in a direction perpendicular to the alignment direction of the liquid crystal molecules on the counter substrate 102 side which is the light incident side substrate. A TN liquid crystal layer is formed on 20B. The light incident on the liquid crystal panel 20B is modulated in accordance with an image signal applied to each p-Si TFT in each of the plurality of pixel regions and is emitted from the polarizing plate 20Bp. The light transmission axis of the polarizing plate 20Bp is set so as to substantially coincide with the alignment direction of the liquid crystal molecules on the substrate side on the light emission side of the liquid crystal panel 20B. Therefore, the liquid crystal panel 20B has a voltage applied to the TN liquid crystal layer in the pixel region. It is driven by a so-called normally white system that achieves the maximum light transmittance when no light is applied. The blue light emitted from the polarizing plate 20Bp is then incident on the half-wave plate 20Bi, the polarization orientation is converted into a polarization orientation perpendicular to the paper surface, and is incident on the dichroic surface 14a and reflected as s-polarized light. Then, the light is emitted from the dichroic prism 14 toward the projection lens 16.

  Next, the light transmitted through the dichroic mirror 4 will be described. The light transmitted through the dichroic mirror 4 is reflected by the dichroic mirror 6 while the green band light is reflected and the red band light is transmitted. The light in the green band reflected by the dichroic mirror 6 is incident on the half-wave plate 20Gi ′ and the polarization direction is rotated by 45 °, and the light on the light incident side substrate side of the liquid crystal panel 20G of the liquid crystal light valve 21G for green. The light is incident on the liquid crystal panel 20G with a polarization orientation substantially coinciding with the alignment direction of the liquid crystal molecules. The green liquid crystal light valve 21G includes a transmissive liquid crystal panel 20G and a polarizing plate 20Gp having the same configuration as the blue liquid crystal light valve 21B. The light in the green band that reaches the green liquid crystal light valve 21B first enters the liquid crystal panel 20G. Similarly to the liquid crystal panel described with reference to FIG. 30, the liquid crystal panel 20G has an active matrix type liquid crystal panel structure having a plurality of pixel regions in which p-Si TFTs are formed as switching elements. Light in the green band enters the liquid crystal layer 106 from the counter substrate 102 side.

  The array substrate 100 side which is the light emission side substrate of the liquid crystal panel 20G is rubbed in a direction orthogonal to the alignment direction of the liquid crystal molecules on the counter substrate 102 side which is the light incident side substrate. In 20G, a TN liquid crystal layer is formed. The light incident on the liquid crystal panel 20G is modulated in accordance with an image signal applied to each p-Si TFT in each of the plurality of pixel regions and is emitted from the polarizing plate 20Gp. The light transmission axis of the polarizing plate 20Gp is set so as to substantially coincide with the alignment direction of the liquid crystal molecules on the light emission side substrate side of the liquid crystal panel 20G. Therefore, the liquid crystal panel 20G applies a voltage to the TN liquid crystal layer in the pixel region. It is driven by a so-called normally white system in which a maximum light transmittance is obtained when no voltage is applied. The green light emitted from the polarizing plate 20Gp is then incident on the half-wave plate 20Gi, the polarization direction of which is converted into a polarization direction parallel to the paper surface, and is incident on the dichroic prism 14 as p-polarized light. The green light incident on the dichroic prism 14 passes through the dichroic surfaces 14 a and 14 b, exits from the dichroic prism 14, and travels toward the projection lens 16.

  Further, the red light transmitted through the dichroic mirror 6 is reflected by the mirrors 8 and 10 and is incident on the half-wave plate 20Ri ′ so that the polarization direction is rotated by 45 °, and the red liquid crystal light valve 21R The liquid crystal panel 20R is incident on the liquid crystal panel 20R with a polarization orientation substantially coinciding with the alignment direction of the liquid crystal molecules on the light incident side substrate side. The red liquid crystal light valve 21R includes a transmissive liquid crystal panel 20R and a polarizing plate 20Rp having the same configuration as the blue liquid crystal light valve 21B. The light in the red band that reaches the red liquid crystal light valve 21R first enters the liquid crystal panel 20R. Similarly to the liquid crystal panel described with reference to FIG. 30, the liquid crystal panel 20R also has an active matrix type liquid crystal panel structure having a plurality of pixel regions in which p-Si TFTs are formed as switching elements. Light in the red band enters the liquid crystal layer 106 from the counter substrate 102 side.

  The array substrate 100 side which is the light emitting side substrate of the liquid crystal panel 20R is rubbed in a direction orthogonal to the alignment direction of the liquid crystal molecules on the counter substrate 102 side which is the light incident side substrate. A TN liquid crystal layer is formed on 20R. The light incident on the liquid crystal panel 20R is modulated in accordance with an image signal applied to each p-Si TFT in each of the plurality of pixel regions and is emitted from the polarizing plate 20Rp. The light transmission axis of the polarizing plate 20Rp is set so as to substantially coincide with the alignment direction of the liquid crystal molecules on the substrate side on the light emission side of the liquid crystal panel 20R. Therefore, the liquid crystal panel 20R has a voltage applied to the TN liquid crystal layer in the pixel region. It is driven by a so-called normally white system that achieves the maximum light transmittance when no light is applied. The red light emitted from the polarizing plate 20Rp is then incident on the half-wave plate 20Ri serving as the polarization conversion element in the present embodiment, and the polarization direction is converted into a polarization direction parallel to the paper surface. Is incident on the dichroic prism 14. The red light incident on the dichroic prism 14 is reflected by the dichroic surface 14 b, exits from the dichroic prism 14, and travels toward the projection lens 16.

  In this manner, the blue and red light reflected in the dichroic prism 14 and the green light transmitted through the dichroic prism 14 are combined and emitted, enlarged by the projection lens 16, and displayed on a screen (not shown). The image is projected.

  Now, in the above configuration, it is assumed that unnecessary light having a short wavelength is mixed with light incident on the dichroic prism 14 from the red or green liquid crystal light valves 21R and 21G. Since this unnecessary light is short-wavelength light, it is not reflected / transmitted by the dichroic surfaces 14a, 14b that reflect / transmit red and green, but instead is transmitted / reflected by those surfaces, and the liquid crystal light valve 21B side for blue To reach. However, since the unnecessary light has a polarization direction parallel to the paper surface as in the case of the red or green light incident on the dichroic prism 14, the ½ wavelength plate 20Bi on the liquid crystal light valve 21B side for blue is used. , The polarization direction is rotated and light having a polarization direction perpendicular to the transmission axis of the polarizing plate 20Bp is absorbed by the polarizing plate 20Bp and does not reach the back surface of the liquid crystal panel 20B. Accordingly, it is possible to prevent the occurrence of leakage current caused by this unnecessary light in the p-Si TFT of the liquid crystal panel 20B.

  In this embodiment, a half-wave plate is used as the polarization conversion element. For example, a liquid crystal panel in which liquid crystal that rotates the polarization direction of the emitted light is rotated by a predetermined angle is used instead of the half-wave plate. Of course it is also possible.

  Next, the effect obtained by the projection display apparatus of this embodiment will be described with reference to FIG. FIG. 2 shows the light resistance of the p-Si TFT. The horizontal axis indicates the amount of white light incident on the liquid crystal panel in logarithm, and the vertical axis indicates the gradation of the liquid crystal panel based on the leakage current generated in the p-Si TFT. The degree of display error is shown as the amount of leakage. The amount of incident white light is the total amount of red, green, and blue, and the light amount ratio is “red: green: blue = 3: 12: 1”. In the figure, the leak amount characteristic of the liquid crystal light valve for blue of the conventional projection display device is shown by a thin solid line (B), and the leak at the liquid crystal light valve for blue of the projection display device according to the present embodiment is shown in FIG. The quantity characteristic is indicated by a thick solid line (B after countermeasure).

  As is apparent from FIG. 2 with reference to FIG. 32, both the conventional and the present embodiments increase the amount of leakage when the amount of light incident on the liquid crystal panel increases. For example, the amount of light incident on the liquid crystal panel is 5000000 lx. Taking the case as an example, the amount of leakage in the conventional blue liquid crystal light valve 21B was 1.25 as shown in FIG. 32, but in the blue liquid crystal light valve 21B according to the present embodiment, It can be seen that the amount of leakage is greatly reduced to about 0.7. The leakage amount 0.7 in the blue liquid crystal light valve 21B is substantially the same as the leakage amount in the conventional red and green liquid crystal light valves shown in FIG. According to the type display device, it is possible to reduce the influence of unnecessary light and to adjust the balance of the gradations of red, green, and blue to the original modulation signal, and the desired color of the light synthesized by the dichroic prism 14 can be obtained. It becomes possible to improve display quality by using colors.

  Although the illustration of the effect is omitted, when the emitted light of the blue color component includes the unnecessary light and enters the dichroic prism 14, the blue component is on the relatively short wavelength side, and therefore the unnecessary light is included together with the blue component. The light is emitted from the dichroic prism 14. Therefore, although there is little deterioration in display quality due to unnecessary light, the red and green light valves 21R and G that emit light of red or green color components have polarization directions almost orthogonal to the polarization direction of the unnecessary light. Since only linearly polarized light is transmitted, unnecessary light can be reliably prevented from entering.

  In the projection display apparatus according to the present embodiment, for example, the principal axes of the half-wave plates 20Ri ′, 20Gi ′, and 20Bi ′ are set in the same direction as viewed from the light incident side, and the liquid crystal panels 20R, 20G are used. , 20B and the polarizing plates 20Rp, 20Gp, and 20Bp are arranged in the same direction (almost parallel when viewed from the light incident side). Then, the direction of the principal axis of the half-wave plate 20Bi as the polarization conversion element is adjusted so that the emitted light of the blue color component becomes s-polarized light in the dichroic prism 14, while the red and green colors The directions of the principal axes of the half-wave plates 20Ri and 20Gi as the polarization conversion elements are adjusted so that the component emission light becomes p-polarized light in the dichroic prism 14.

  On the other hand, when viewed from the light incident side, the directions of the principal axes of the red and green half-wave plates 20Ri 'and 20Gi' are the same, and the blue half-wave plates 20Bi 'are the same. The orientations of the main axes are adjusted to be different, and the orientation directions of the liquid crystal molecules of the liquid crystal panels 20R, 20G, and 20B and the respective directions are made to correspond to the directions of the main axes of the half-wave plates 20Ri ′, 20Gi ′, and 20Bi ′. Of course, the direction of the transmission axis of the polarizing plates 20Rp, 20Gp, and 20Bp may be adjusted and disposed. In this case, even if the principal axes of the half-wave plates 20Ri, 20Gi, and 20Bi on the light emission side are made the same direction, the emitted light of the blue color component becomes s-polarized light in the dichroic prism 14. Also, the emitted light of the red and green color components can be made p-polarized light in the dichroic prism 14.

Furthermore, the configuration including the liquid crystal light valve and the dichroic prism of the projection display device according to the present embodiment described above can be variously modified. For example, the configuration shown in FIG. In the example shown in FIG. 3, the liquid crystal molecules in the liquid crystal panels 20R, 20G, and 20B of the liquid crystal light valves 21R, 21G, and 21B are perpendicular to the paper surface from the orientation direction parallel to the paper surface in the traveling direction of light from the light source 1. It has a TN liquid crystal layer that is aligned. Accordingly, the half-wave plates 20Ri ′, 20Gi ′, and 20Bi ′ provided in the projection display device shown in FIG. 1 are not arranged because they do not need to be used. The half-wave plate 20Bi is disposed only on the light emission side of the blue liquid crystal light valve 21B, that is, only between the polarizing plate 20Bp and the dichroic prism 14. Even in this configuration, the same light source 1, polarization conversion device 2, dichroic mirrors 4 to 6, and mirrors 10 and 12 as shown in FIG. 1 can be used. Even in this case, the effect of the present embodiment shown in FIG. 2 can be obtained. Further, instead of arranging the half-wave plate 20Bi only on the light exit side of the liquid crystal light valve 21B for blue, a half-wave plate as a polarization conversion element is replaced with two polarizing plates 20Rp and 20Gp and a dichroic prism 14. The same effect can be obtained even if sandwiched between the two.

  Furthermore, the projection display apparatus according to the present embodiment can be configured as shown in FIG. 4 as a modification of the projection display apparatus shown in FIG. In the projection display device shown in FIG. 3 described above, a structure in which a phase plate such as a half-wave plate 20Bi is disposed as a polarization conversion means between the polarizing plate 20Bp on the light exit side of the liquid crystal panel 20B and the dichroic prism 14. However, in the modification shown in FIG. 4, a configuration is shown in which no polarization conversion means is provided between the light emission side polarizing plates 20Rp, 20Gp, 20Bp and the dichroic prism 14. For example, the transmission axis of the polarizing plate 20Bp of the liquid crystal panel 20B that transmits the emitted light of the blue color component is relative to the transmission axes of the polarizing plates 20Rp and 20Gp of the liquid crystal panels 20R and 20B that transmit the other two emitted lights. The liquid crystal panels 20R, 20G, and 20B are arranged so as to be substantially orthogonal. A half-wave plate 20Bi is disposed as a polarization conversion means on the light incident side of the blue liquid crystal light valve 21B. Even in this configuration, the same light source 1, polarization conversion device 2, dichroic mirrors 4 to 6, and mirrors 8, 10, and 12 as shown in FIG. 1 can be used.

  According to this configuration, even if short-wavelength light is emitted from the polarizing plates 20Rp and 20Gp, the polarization direction thereof is orthogonal to the transmission axis of the polarizing plate 20Bp, and thus cannot pass through the polarizing plate 20Bp. A leak current is not generated in the p-Si TFT of the liquid crystal panel 20B that modulates.

  In this configuration, the transmission axis of the polarizing plate 20Bp of the blue liquid crystal panel 20B and the transmission axes of the red and green liquid crystal panels 20R and 20G are almost orthogonal to each other. The liquid crystal panel 20B may be formed so that the rubbing direction applied to the alignment film of the liquid crystal cell is substantially orthogonal to the rubbing directions of the red and green liquid crystal panels 20R and 20G.

  Next, another modification of the vicinity including the liquid crystal light valve and the dichroic prism of the projection display apparatus according to the present embodiment will be described with reference to FIG. First, the configuration in the vicinity including the liquid crystal light valve and the dichroic prism will be described with reference to FIG. In the present modification, as the polarization conversion means provided between each polarizing plate 20Rp, 20Gp, 20Bp and the dichroic prism 14 that transmits the emitted light of each color component, the half wavelength of the projection display device shown in FIG. The liquid crystal panels 20Rl, 20Gl, and 20Bl are arranged in place of the plates 20Ri, 20Gi, and 20Bi. In this modified example, the liquid crystal light valves 21R, 21G, and 21B are arranged so that light in the blue band is transmitted through the dichroic surfaces 14a and 14b in the dichroic prism 14.

  FIGS. 5B to 5D show the polarization direction of the emitted light viewed from the dichroic prism 14 side toward each liquid crystal light valve and the transmission axis of the polarizing plate of each liquid crystal light valve. The upper row shows blue light, and the lower row shows red and green light.

  In FIG. 5B, the directions of the transmission axis 30 of the polarizing plate 20Bp of the liquid crystal light valve 21B and the transmission axes 32 of the polarizing plates 20Rp and 20Gp of the liquid crystal light valves 21R and 21G are all the same and are inclined at 45 °. Yes.

  The blue liquid crystal panel 20B1 provided on the dichroic prism 14 side of the blue polarizing plate 20Bp is provided with a TN liquid crystal layer that rotates the polarization direction 34 of the blue light emitted from the polarizing plate 20Bp by 45 ° counterclockwise. The red and green liquid crystal panels 20Rl and 20Gl provided on the dichroic prism 14 side of the red and green polarizing plates 20Rp and 20Gp have polarization directions of red and green light respectively emitted from the polarizing plates 20Rp and 20Gp. A TN liquid crystal layer is provided for rotating 36 by 45 ° clockwise. Accordingly, the blue light transmitted through the blue liquid crystal panel 20B1 is incident on the dichroic prism 14 with a polarization direction 34 perpendicular to the paper surface, and the red and green light transmitted through the red and green liquid crystal panels 20Rl and 20Gl is the paper surface. Is incident on the dichroic prism 14 with a polarization direction 36 parallel to the dichroic prism. Therefore, even with this configuration, it is not necessary to irradiate the p-Si TFT in the blue liquid crystal light valve 21B with unnecessary light having a short wavelength, and therefore, the effect described with reference to FIG. 2 can be obtained.

  Further, in the projection display device according to the present embodiment, the liquid crystal light valve 21B that emits the modulated light of the blue color component is disposed at a position where the emitted light is transmitted through the dichroic prism 14, and the blue emitted light is Since the dichroic prism 14 is p-polarized light and the other two colors are s-polarized light, a more balanced color composition can be performed and high-quality image display can be performed.

  Next, a modified example shown in FIG. In FIG. 5C, the directions of the transmission axis 30 of the polarizing plate 20Bp of the liquid crystal light valve 21B and the transmission axes 32 of the polarizing plates 20Rp and 20Gp of the liquid crystal light valves 21R and 21G are all the same and aligned in the horizontal direction. Yes.

  The blue liquid crystal panel 20B1 provided on the dichroic prism 14 side of the blue polarizing plate 20Bp is provided with a TN liquid crystal layer that rotates the polarization direction 34 of the blue light emitted from the polarizing plate 20Bp by 45 ° clockwise. The red and green liquid crystal panels 20Rl and 20Gl provided on the dichroic prism 14 side of the red and green polarizing plates 20Rp and 20Gp have polarization directions 36 of red and green light respectively emitted from the polarizing plates 20Rp and 20Gp. Is provided with a TN liquid crystal layer that is rotated 45 ° counterclockwise.

  Accordingly, the blue light transmitted through the blue liquid crystal panel 20B1 is incident on the dichroic prism 14 with a polarization azimuth 34 of 45 ° with respect to the paper surface, and the red and green light transmitted through the red and green liquid crystal panels 20Rl and 20Gl. Is incident on the dichroic prism 14 with a polarization azimuth 36 perpendicular to the polarization azimuth 34 at an angle of 45 ° with respect to the paper surface. Therefore, even with this configuration, it is not necessary to irradiate the p-Si TFT in the blue liquid crystal light valve 21B with unnecessary light having a short wavelength, and therefore, the effect described with reference to FIG. 2 can be obtained.

  Next, a modified example shown in FIG. The direction of the transmission axis 30 of the polarizing plate 20Bp in FIG. 5 (d) and the direction of the transmission axis 32 of the polarizing plates 20Rp and 20Gp are the same and are obliquely aligned at 45 °, but the transmission axis shown in FIG. The difference is that they are orthogonal.

  In FIG. 5D, the polarization direction 34 of blue light emitted from the polarizing plate 20Bp is rotated 45 ° counterclockwise, and the polarization directions 36 of red and green light emitted from the polarizing plates 20Rp and 20Gp are clockwise. Rotated by 45 °. Accordingly, the blue light transmitted through the blue liquid crystal panel 20B1 is incident on the dichroic prism 14 with a polarization direction 34 perpendicular to the paper surface, and the red and green light transmitted through the red and green liquid crystal panels 20Rl and 20Gl is the paper surface. Is incident on the dichroic prism 14 with a polarization direction 36 parallel to the dichroic prism.

  Therefore, even with this configuration, it is not necessary to irradiate the p-Si TFT in the blue liquid crystal light valve 21B with unnecessary light having a short wavelength, and therefore, the effect described with reference to FIG. 2 can be obtained. Similarly to the case of FIG. 5B, the emitted light of the blue color component is transmitted through the dichroic prism 14 as p-polarized light, and the other two colors are reflected by the dichroic surfaces 14a and 14b as s-polarized light. Therefore, it is possible to perform color synthesis in a more balanced manner, and high-quality image display can be performed.

  Next, a projection display apparatus according to a second embodiment of the present invention will be described with reference to FIGS. FIG. 6A shows a schematic configuration of a modification of the projection display apparatus according to the present embodiment. This modification is the first except that a quarter-wave plate 40 is disposed as a circularly polarized light conversion means at the end of the dichroic prism 14 where the color-combined light is emitted, and a transmissive screen 42 is illustrated. The configuration is the same as that shown in FIG. The quarter-wave plate 40 has an optical axis so as to form an angle of approximately 45 ° with respect to the polarization direction of the blue color component light emitted from the dichroic prism 14 and the polarization direction of the red and green color component light. A tuned, achromatic wave plate with three primary color bands.

  With this configuration, the color-combined linearly polarized light emitted from the dichroic prism 14 passes through the quarter-wave plate 40 and becomes all circularly polarized light and enters the transmissive screen 42.

  As shown in FIG. 6B, the transmissive screen 42 is configured by laminating a double-sided lenticular lens 44 and a Fresnel lens 46 in this order as viewed from the image display side. Each color-combined light magnified and projected by the projection lens 16 is first incident on the Fresnel lens 46 to be condensed, and then incident on a light diffusion double-sided lenticular lens 44 for expanding the viewing angle. At this time, when each color-combined light is incident on the Fresnel lens 46 and the double-sided lenticular lens 44 as linearly polarized light, as shown in FIG. 6B, the intensity of light in the polarization direction a perpendicular to the paper surface and the paper surface The intensity of light having a polarization direction b parallel to is different depending on the exit angle θ from the surface of the double-sided lenticular lens 44 due to the difference in refractive characteristics of the double-sided lenticular lens 44 (light intensity of the polarization direction a)> (The light intensity in the polarization direction b). Therefore, when the transmissive screen 44 is observed obliquely from the image display side, the light having the polarization direction a, that is, the blue light is emphasized more than the red and green lights, and a bluish color tone is displayed. However, if the ¼ wavelength plate 40 is arranged on the light exit side of the dichroic prism 14 as in the present embodiment, any linearly polarized light becomes circularly polarized light and is emitted to the projection lens 16 to the screen. Since the projection is performed in an enlarged manner, the light of the three primary colors of red, green, and blue all have polarization azimuth a and b components at a uniform ratio, and the ratio of the light intensity of each color does not collapse in the display area. Therefore, in the present embodiment, even when the transmissive screen 42 is observed from an oblique direction, it is possible to see a good display image with no color unevenness and reduced color shift.

  Furthermore, the projection display apparatus according to the present embodiment can have various configurations as shown in FIGS. 7 to 12 as modifications of the projection display apparatus shown in FIG.

  In the configuration shown in FIG. 7A, the liquid crystal molecules in the liquid crystal panels 20R, 20G, and 20B of the liquid crystal light valves 21R, 21G, and 21B are aligned from the orientation direction parallel to the paper surface in the light traveling direction from the light source 1. The TN liquid crystal layer has an alignment direction perpendicular to the. A half-wave plate 20Gi is disposed on the light incident side of the green liquid crystal light valve 21G. Even in this configuration, the same light source 1, polarization conversion device 2, dichroic mirrors 4 to 6, and mirrors 10 and 12 as those shown in FIG. 1 of the first embodiment can be used.

  Lights of the three primary colors having polarization orientations parallel to the paper surface enter the corresponding liquid crystal light valves 21R, 21G, and 21B, undergo modulation in accordance with image signals, and then enter the dichroic prism 14. The blue light passes through the liquid crystal light valve 21B, enters the dichroic prism 14 as s-polarized light, and is reflected by the dichroic surface 14a. The red light passes through the liquid crystal light valve 21R, enters the dichroic prism 14 as s-polarized light, and is reflected by the dichroic surface 14b. The green light passes through the half-wave plate 20Gi and has a polarization orientation perpendicular to the paper surface, then passes through the liquid crystal light valve 21G, enters the dichroic prism 14 as p-polarized light, and passes through the dichroic surfaces 14a and 14b. To Penetrate. The light of the three primary colors emitted from the dichroic prism 14 is incident on a half-wave plate 50 that is a polarization conversion element and rotated in the polarization direction, and then is enlarged by the projection lens 16 and is enlarged by the screen 42 (shown in FIG. 7). Is omitted).

  Here, the conversion of the polarization direction of each light in the half-wave plate 50 will be described with reference to FIG. FIG. 7 shows a state where the half-wave plate 50 is viewed from the screen 42 side, for example. In FIG. 7B, the half-wave plate 50 is arranged so that the optical axis 41 forms an angle of approximately 22.5 ° with respect to the light transmission axis 52 of the polarizing plate 20Gp. For this reason, the light of the blue and red color components having the polarization direction in the vertical direction transmitted through the light transmission axis 53 of the polarizing plates 20Bp and 20Rp and incident on the half-wave plate 50 is inclined 45 with respect to the horizontal direction. The light 55 having a polarization orientation of 65 ° is emitted from the half-wave plate 50. The light of the green color component having the horizontal polarization direction that is transmitted through the light transmission axis 52 of the polarizing plate 20Gp and incident on the half-wave plate 50 is 45 ° obliquely with respect to the horizontal direction. The light 54 having an orthogonal polarization direction is emitted from the half-wave plate 50. In this way, the light synthesized by the dichroic prism 14 is converted into linearly polarized light that is inclined by 45 ° with respect to the horizontal direction and is projected onto the screen 42, so that the angle formed by the polarization direction of the light of each color component The bisecting line can always be approximately coincident with either the horizontal line or the vertical line. That is, the light of the three primary colors of red, green, and blue all have a polarization component in the horizontal direction and the vertical direction at a uniform ratio, and the ratio of the light intensity of each color does not collapse in the display area. Accordingly, even in this example, even when the transmissive screen 42 is observed obliquely, it is possible to see a good display image with no color unevenness and preventing color shift. Further, as in this modification, when the half-wave plate 50 is used instead of the quarter-wave plate 40 as a polarization conversion element for the color-combined light traveling toward the screen, the optical axis of the wave plate can be adjusted. It becomes easier and the apparatus cost can be reduced.

  Next, another modification of the vicinity including the liquid crystal light valve and the dichroic prism of the projection display device according to the present embodiment will be described with reference to FIG. The color composition optical system of the projection display device described with reference to FIGS. 1 to 7 described above is the dichroic prism 14 having orthogonal dichroic surfaces 14a and 14b, whereas the color composition optical in this modification example. The system includes a dichroic prism 15 having one dichroic surface 15a and a dichroic mirror 60. Further, the present modification is characterized in that the liquid crystal light valves 21R, 21G, and 21B are arranged so that the light in the blue band is transmitted through the dichroic surface 15a in the dichroic prism 15. In FIG. 8, illustration of an optical system and the like for color-separating white light from the light source 1 is omitted.

  The light of the three primary colors that have been color-separated is aligned in the polarization direction parallel to the paper surface and is guided to the liquid crystal light valves 21R, 21G, and 21B for each color. The blue component light is transmitted through the blue liquid crystal light valve 21B, modulated by the image signal in the liquid crystal panel 20B having the TN liquid crystal layer, and emitted from the polarizing plate 20Bp in a polarization direction perpendicular to the paper surface. Next, the blue component light is incident on the half-wave plate 20Bi, the polarization direction is rotated by 90 °, becomes a polarization direction parallel to the paper surface, is reflected by the mirror 61, is incident on the dichroic prism 15, and is p-polarized light. Is transmitted through the dichroic surface 15a.

  On the other hand, the light of the red color component is transmitted through the liquid crystal light valve 21R and is transmitted through the dichroic mirror 60 in a polarization direction perpendicular to the paper surface. Further, the light of the green color component passes through the liquid crystal light valve 21G and is reflected by the dichroic mirror 60 in a polarization direction perpendicular to the paper surface. Light of red and green color components having a polarization direction perpendicular to the paper surface is color-combined by the dichroic mirror 60 and enters the dichroic prism 15. The red and green color component light incident on the dichroic prism 15 is reflected by the dichroic surface 15a as s-polarized light.

  Accordingly, in the dichroic prism 15, the s-polarized red and green color component light and the p-polarized blue color component light are color-combined and emitted. Next, the color-combined light enters the half-wave plate 50, and the light of each color component is converted into orthogonal linearly polarized light and enlarged by the projection lens 16 in the same manner as shown in FIG. The image is displayed on a screen (not shown in FIG. 8) 42.

  Even with the configuration according to this modification, it is not necessary to irradiate the p-Si TFT in the blue liquid crystal light valve 21B with unnecessary light having a short wavelength, so that the description has been given with reference to FIG. 2 according to the first embodiment. The same effect can be obtained. Furthermore, also in this modified example, the light of the three primary colors of red, green, and blue all have polarization components in the horizontal direction and the vertical direction at a uniform ratio, and the ratio of the light intensity of each color collapses in the display area. Therefore, even when the transmissive screen 42 is observed from an oblique direction, it is possible to obtain a good display image with no color unevenness and little color shift.

  Next, another modification of the projection display device described with reference to FIG. 8 will be described with reference to FIG. The projection display device shown in FIG. 9 is applied to two substrates sandwiching the TN liquid crystal layers of the respective liquid crystal panels 20R, 20G, and 20B in the same manner as described with reference to FIG. 1 of the first embodiment. The configuration is the same as that of the projection display device shown in FIG. 8 except that the orientation direction thus formed is obliquely 45 ° and perpendicular to the paper surface. Accordingly, the half-wave plates 20Ri ', 20Gi', 20Bi 'and the half-wave plates 20Ri, 20Gi, 20Bi are arranged on both sides of the liquid crystal light valves 21R, 21G, 21B, respectively. Then, among the light of each color component having a polarization direction parallel to the paper surface guided from the light source 1 side, the blue component light becomes a polarization direction parallel to the paper surface and reflected by the mirror 61 and enters the dichroic prism 15. , And passes through the dichroic surface 15a as p-polarized light. On the other hand, light of red and green color components is polarized in a direction perpendicular to the paper surface, is color-combined by the dichroic mirror 60, and enters the dichroic prism 15. The red and green color component light incident on the dichroic prism 15 is reflected by the dichroic surface 15a as s-polarized light.

  Accordingly, the s-polarized red and green color component light and the p-polarized blue color component light are color-combined in the dichroic prism 15 and incident on the half-wave plate 500, and the light of each color component is shown in FIG. In the same manner as shown in FIG. 9B, the light of each color component is converted into orthogonal linearly polarized light, enlarged by the projection lens 16, and displayed on a screen (not shown in FIG. 9) 42. Even in such a configuration, an effect equivalent to that of the projection display device described with reference to FIG. 8 can be obtained.

  Next, still another modification of the projection display device described with reference to FIG. 8 will be described with reference to FIG. The projection display apparatus shown in FIG. 10 transmits red and green band light as p-polarized light through the dichroic surface 15a in the dichroic prism 15, while blue band light as s-polarized light. 15 is characterized in that it is configured to be reflected by the dichroic surface 15a in the inside. Therefore, the blue half-wave plate 20Bi shown in FIG. 8 is removed, and instead, the half-wave plates 20Ri and 20Gi are arranged in the next stage of the red and green liquid crystal light valves 21R and 21G, respectively. It has become. Even if it does in this way, the effect similar to what was shown in FIG. 8 can be acquired.

  Next, still another modification of the projection display device described with reference to FIG. 10 will be described with reference to FIG. In the projection display apparatus shown in FIG. 11, a dichroic prism 70 is arranged in place of the dichroic mirror 60 at the arrangement position of the dichroic mirror 60 shown in FIG. A half-wave plate 71 is disposed between the dichroic prism 70 and the dichroic prism 15. The half-wave plate 71 is an achromatic wave plate in the red and green color component bands. Further, the half-wave plate 20Gi for green in FIG. 10 is removed. By doing so, the light in the red band passes through the dichroic prism 70 as p-polarized light, enters the half-wave plate 71, is converted into a polarization direction perpendicular to the paper surface, and enters the dichroic prism 15. Then, it passes through the dichroic surface 15a of the dichroic prism 15 as s-polarized light. The green band light is reflected by the dichroic surface 70a of the dichroic prism 70 as s-polarized light, enters the half-wave plate 71, and passes through the dichroic surface 15a of the dichroic prism 15 as p-polarized light. On the other hand, the blue band light is reflected by the dichroic surface 15a in the dichroic prism 15 as s-polarized light. Even if it does in this way, the effect similar to what was shown in FIG. 8 can be acquired.

  Next, still another modification of the projection display device according to the present embodiment will be described with reference to FIG. The projection display device shown in FIG. 12 is a quarter wavelength plate in the band of the three primary color components, instead of the half wavelength plate 50 as the polarization conversion element in the projection display device described with reference to FIG. This is characterized in that a quarter-wave plate 40 functioning as is disposed.

  In the configuration shown in FIG. 12A, the liquid crystal molecules in the liquid crystal panels 20R, 20G, and 20B of the liquid crystal light valves 21R, 21G, and 21B are aligned from the orientation direction parallel to the paper surface in the light traveling direction from the light source 1. The TN liquid crystal layer has an alignment direction perpendicular to the. A half-wave plate 20Gi is disposed on the light incident side of the green liquid crystal light valve 21G. Even in this configuration, the same light source 1, polarization conversion device 2, dichroic mirrors 4 to 6, and mirrors 10 and 12 as those shown in FIG. 1 of the first embodiment can be used.

  Now, light of the three primary colors having polarization directions parallel to the paper surface are incident on the corresponding liquid crystal light valves 21R, 21G, and 21B, modulated in accordance with image signals, and then incident on the dichroic prism 14. The blue light passes through the liquid crystal light valve 21B, enters the dichroic prism 14 as s-polarized light, and is reflected by the dichroic surface 14a. The red light passes through the liquid crystal light valve 21R, enters the dichroic prism 14 as s-polarized light, and is reflected by the dichroic surface 14b. The green light passes through the half-wave plate 20Gi and has a polarization orientation perpendicular to the paper surface, then passes through the liquid crystal light valve 21G, enters the dichroic prism 14 as p-polarized light, and passes through the dichroic surfaces 14a and 14b. To Penetrate. The light of the three primary colors emitted from the dichroic prism 14 is incident on a quarter-wave plate 40 that is a polarization conversion element, converted into circularly polarized light, and then enlarged by the projection lens 16 to be displayed on the screen 42 (shown in FIG. 12). Is omitted).

  Here, the conversion of the polarization state of each light in the quarter-wave plate 40 will be described with reference to FIG. FIG. 12B shows a state where the quarter wavelength plate 40 is viewed from the screen 42 side, for example. In FIG. 12B, the quarter-wave plate 40 is arranged so that the optical axis 41 forms an angle of approximately 45 ° with respect to the light transmission axis 53 of the polarizing plates 20Bp and 20Rp and the light transmission axis 52 of the polarizing plate 20Gp. Adjusted and arranged. For this reason, the light of the blue and red color components having the polarization direction in the vertical direction that is transmitted through the light transmission axis 53 of the polarizing plates 20Bp and 20Rp and incident on the quarter wavelength plate 40 is the right circularly polarized light 56. The light is emitted from the quarter-wave plate 40. The light of the green color component having the horizontal polarization direction that is transmitted through the light transmission axis 52 of the polarizing plate 20Gp and incident on the quarter wavelength plate 40 becomes the left circularly polarized light 57, and the quarter wavelength plate. Inject from 40. In this way, all the light synthesized by the dichroic prism 14 is converted into circularly polarized light and projected onto the screen 42, so that the ratio of at least the horizontal light quantity and the vertical light quantity on the screen is substantially equal for each color. Can be made. That is, the light of the three primary colors of red, green, and blue all have a polarization component in the horizontal direction and the vertical direction at a uniform ratio, and the ratio of the light intensity of each color does not collapse in the display area. Accordingly, even in this example, even when the transmissive screen 42 is observed obliquely, it is possible to see a good display image with no color unevenness and little color shift.

  Similarly to this modification, the same effect can be obtained by replacing the half-wave plate 500 of the projection display apparatus shown in FIGS. 7 to 11 with the quarter-wave plate 40.

  Next, a projection display apparatus according to a third embodiment of the present invention will be described with reference to FIG. The projection display apparatus shown in FIG. 14 includes a light source 1, first and second dichroic mirrors 140 ″ and 142 ″ that separate light emitted from the light source 1 into a plurality of color lights, and a total reflection mirror 144 ′. It has a color separation optical system consisting of In addition, the projection display device combines a plurality of light valves 21R, 21G, and 21B that spatially modulate a plurality of color lights emitted from the color separation optical system, and a first and a first that combine a plurality of color lights spatially modulated for each color. The color synthesizing optical system includes two dichroic prisms 160 ′ and 162 ′ and a total reflection prism 164 ′. Furthermore, the projection display apparatus has a projection lens 16 that projects a plurality of synthesized color lights.

  The light source 1 includes an arc tube composed of a halogen lamp or a metal halide lamp and a parabolic reflector, and emits white light emitted from the arc tube as substantially parallel light by the parabolic reflector.

  The first dichroic mirror 140 ″ is a high-pass filter that transmits light having a wavelength of 500 nm or less, that is, blue light, and reflects light having a wavelength longer than 500 nm (light having a short wavelength, that is, light having a high frequency). This is called a high-pass filter in order to transmit light).

  The second dichroic mirror 142 ″ is a low-pass filter that transmits light having a wavelength of 600 nm or more, that is, red light, and reflects light having a wavelength shorter than 600 nm (light having a long wavelength, that is, light having a low frequency). Is referred to as a low-pass filter).

  The light valves 21R, 21G, and 21B are arranged in order from the light incident direction, such as condenser lenses 152R, 152G, and 152B, incident polarizing plates 154R, 154G, and 154B, transmissive TN liquid crystal panels 156R, 156G and 156B, and outgoing polarizing plates 158R and 158G. 158B.

  The first dichroic prism 160 ′ is a high-pass filter that transmits blue light, that is, light having a wavelength of 500 nm or less and reflects light having a wavelength longer than 500 nm, and is diagonally formed of a glass cube. A reflective surface is formed. The second dichroic prism 162 ′ is a low-pass filter that transmits red light, that is, light having a wavelength of 600 nm or more, and reflects light having a wavelength shorter than 600 nm, and is diagonally made of a glass cube. A reflective surface is formed.

  The projection lens 16 projects the image modulated by each light valve and color-combined by the first and second dichroic prisms 160 ′ and 162 ′ onto a screen (not shown).

  The white light emitted from the light source 1 enters the first dichroic mirror 140 ″, and blue light having a wavelength of 500 nm or less is transmitted and reflected by the total reflection mirror 144 ″. The blue light bent almost at right angles by the total reflection mirror 144 '' enters the blue light valve 21B and is spatially modulated. Further, green and red light having a wavelength of 500 nm or more reflected by the first dichroic mirror 140 ″ is incident on the second dichroic mirror 142 ″, and red light having a wavelength of 600 nm or more is transmitted therethrough for red. The light is incident on the light valve 21R and spatially modulated. Similarly, green light having a wavelength of 500 nm to 600 nm reflected by the second dichroic mirror 142 ″ is incident on the green light valve 21G and spatially modulated.

  The blue light spatially modulated by the blue light valve 21B enters the first dichroic prism 160 ′ and is transmitted therethrough. The green light spatially modulated by the green light valve 21G is incident on the first dichroic prism 160 ′ and reflected. At this time, the blue light and the green light are combined in the first dichroic prism 160 ′ and simultaneously incident on the second dichroic prism 162 ′, where they are reflected and redirected in the direction of the projection lens 16. .

  The red light spatially modulated by the red light valve 21R enters the total reflection prism 164 ′, changes its direction, and enters the second dichroic prism 162 ′. At this time, the combined light of the blue light and the green light emitted from the first dichroic prism 160 ′ and the red light are combined in the second dichroic prism 162 ′. The combined light exits from the second dichroic prism 162 ′, then enters the projection lens 16 and is enlarged and projected onto the screen.

  Only the low-cost high-pass and low-pass filters can be used due to the arrangement of the members such as the optical system and the operation of the light beam described above. In addition, the color composition system from the light valves 21R, 21G, and 21B to the projection lens 16 is composed of a dichroic prism made of a glass block with little distortion and misalignment. Therefore, the projection type has no pixel misalignment or chromaticity deviation. A display device can be realized.

  Further, even when the first dichroic prism 160 ′ and the total reflection prism 164 ′ are replaced with flat mirrors and only the second dichroic prism 162 ′ is used as a prism, the distortion and the second dichroic prism 162 ′ can be reduced. Since the shift can be reduced, the pixel shift and the chromaticity shift can be prevented more effectively than when a flat mirror is used. In addition, in this configuration, the cost of the optical system can be reduced compared with the case where the first and second dichroic prisms 160 ′ and 162 ′ and the total reflection prism 164 ′ are all prisms, and there is an advantage of cost reduction. is there. Similarly, the same effect can be obtained when the second dichroic prism 162 ′ is a flat mirror.

  Next, a projection display apparatus according to a fourth embodiment of the present invention will be described with reference to FIGS. The arrangement of the optical system of the projection display apparatus according to the present embodiment is the same as that shown in FIG. 14 of the third embodiment. The reflected light of a dichroic mirror, that is, a prism whose both surfaces are in contact with a solid or liquid, is s-polarized light. FIG. 15 shows the wavelength dependence of the transmittance of the first dichroic prism 160 ′. Since light is hardly absorbed by the mirror, the reflectance is a value obtained by subtracting the transmittance from 100%. The polarization of conventional reflected light is unpolarized unless otherwise specified. The non-polarized reflection characteristic is almost the same as the averaged characteristic of the p-polarized reflection characteristic and the s-polarized reflection characteristic. For this reason, the characteristics before and after the cut wavelength are gradually inclined as shown in FIG. In general, since the s-polarized light has the highest reflectance, the projection display apparatus can be made to have high illuminance by applying this.

  In order to realize this configuration, when the polarization directions of light emitted from the light valves 21R, 21G, and 21B are different, a polarization rotation unit or polarization shaping unit that rotates or shapes the polarization direction on the emission side is provided. A λ / 2 phase difference plate can be used as the polarization rotating means. As the polarization shaping means, a polarizing plate or an elliptical polarizing plate can be shaped with high efficiency, and it is easy to handle at low cost. FIG. 16 shows the wavelength dependence of the transmittance of the second dichroic prism 162 ′. The second dichroic prism 162 ′ and the total reflection prism 164 ′ can obtain the same effect by making the reflected light s-polarized light.

  Next explained is a projection display apparatus according to the fifth embodiment of the invention. The arrangement of the optical system of the display device of this embodiment is the same as that shown in FIG. 14 in the first embodiment. The present embodiment is characterized in that the transmitted light of the dichroic mirror whose both surfaces are in contact with a solid or liquid is p-polarized light. This will be described with reference to FIG. 15 used in the fourth embodiment. FIG. 15 shows the wavelength characteristics of the reflectance and transmittance of s-polarized light and p-polarized light of the first dichroic prism 160 ′. The cut wavelength of the s-polarized light of the first dichroic prism 160 ′ is 490 nm, and light having a wavelength of 490 nm or more is reflected. Further, the cut wavelength of the p-polarized light of the first dichroic prism 160 ′ is 510 nm, and light having a wavelength of 510 nm or less is transmitted. Since reflection / transmission characteristics become gentle in the vicinity of the cut wavelength, it is possible to project all of the light having a wavelength near the cut wavelength generated in the color separation optical system. With this configuration, it is possible to project all the light except for 510 nm or less of blue light and red light of 490 nm or more for green light, and it is possible to increase the illuminance of the apparatus. Similarly, since it is relatively easy to set the cut wavelength by using s-polarized light for reflected light and p-polarized light for transmitted light as in this configuration, each color of the projected image can be designed arbitrarily. High illuminance and high color purity (realization of a wide color reproduction range) can be easily realized.

  In order to realize this configuration, when the polarization of the light emitted from each of the light valves 21R, 21G, and 21B is different, a polarization rotation unit or a shaping unit that rotates or shapes the polarization direction is provided on the light emission side. A λ / 2 phase difference plate can be used as the polarization rotating means. As the polarization shaping means, a polarizing plate or an elliptically polarizing plate can be shaped with high efficiency, and it is easy to handle at low cost. The second dichroic prism 162 ′ having the wavelength dependency of the transmittance shown in FIG. 16 can obtain the same effect by making the transmitted light p-polarized light.

  Next, a projection display apparatus according to a sixth embodiment of the present invention is described with reference to FIG. This embodiment is characterized in that the light source 1 in FIG. 14 of the third embodiment is changed to a light source that emits only polarized light. In the projection display apparatus shown in FIG. 17, for example, a half-wave plate 180 is disposed on the light incident side of each of the light valves 21R, 21G, and 21B as the changing rotation means. In addition, a polarization generating element 170 that converts light from the light source 1 into a polarization direction perpendicular to the paper surface is disposed. The light source 1 has an arc tube composed of a halogen lamp or a metal halide lamp, and a parabolic reflector. As the polarization generating element 170, a polarization generating element using a reflective polarizing plate described in Japanese Patent Application No. 9-112603 can be used. The polarized light generating element described in Japanese Patent Application No. 9-112603 is designed to cause white light emitted from an arc tube and made substantially parallel by a parabolic reflector to be incident on a reflective polarizing plate to emit effective polarized light. The optical system is arranged so as to be incident on the optical system. Unnecessary polarized light is again returned to the lamp side, converted into effective polarized light by a reflector or the like, and then emitted from the reflective polarizing plate. With such a configuration, since the emitted light is polarized light at the time of emission from the light source, it is possible to prevent light absorption of unnecessary polarized light in each of the light valves 21R, 21G, and 21B, which is effective in improving the reliability of the apparatus. . In addition, the use of this reflective polarizing plate increases the effective polarization and is effective in increasing the amount of light in the apparatus. Similarly, when an absorption type polarizing plate is used as a polarization generating element, there is an effect of improving reliability, but there is no effect of increasing the amount of light. A polarization beam splitter (PBS) in which a dielectric multilayer film is formed on a glass prism also has the same effect. It is also possible to use a polarization generating element that is a combination of a PBS and a lens as in US Pat. No. 2,748,659.

  Next, a projection display apparatus according to a seventh embodiment of the present invention is described with reference to FIG. The polarized light source 1 in the present embodiment has an arc tube composed of a halogen lamp or a metal halide lamp, and a parabolic reflector. A combination of a PBS and a lens is used as the polarization generating element. Fly eye lens lens arrays (fly eye lenses) 172 and 174 are arranged on the light emitting side of the light source 1, and a PBS phase conversion element array 176 is arranged in the next stage. A plurality of lens arrays 172 and 174 are arranged between the paraboloid reflector and the polarization generating element 176. This lens array group usually consists of two sets. The focal length of the small lens of the lens array 172 on the reflector side is the distance between the lens arrays 172 and 174, and the focal point of the small lens of the lens array 172 is the lens. Wait for the function to focus the light on the corresponding small lens of the array 174. The small lens of the lens array 174 has a focal length at which the image of the small lens of the lens array 172 is enlarged to a light irradiation object (light valves 21R, 21G, and 21B in this projection optical system) or rarely reduced and projected. Have. A combination of a PBS phase conversion element array 176 and a lens array 174 as a polarization generating element used in this polarized light source is disclosed in US Pat. No. 2,748,659. By using this configuration, the conversion efficiency to the effective polarization is higher than the polarized light generation by the reflective polarizing plate of the sixth embodiment (in the polarized light generation by the reflective polarizing plate, the light reflected back to the reflector happens to be effective. Since conversion to polarization is used, the conversion efficiency is low), and there is an effect of high efficiency and high illuminance.

  In addition, since the fly-eye lens is used, the light valves 21R, 21G, and 21B can be uniformly illuminated, and the projection lens 16 magnifies and projects the light valve, thereby improving the uniformity of the amount of light on the screen.

  In FIGS. 17 and 18, the projection display devices according to the sixth and seventh embodiments convert the polarized light emitted from the polarized light source into the s-polarized light of the color separation optical system (the polarized light that is the oscillation direction of the electric field vector of light). It is characterized in that the orientation is polarized light orthogonal to the paper surface.

  By using this configuration, the reflection characteristics in the color separation optical system are improved, and it becomes possible to increase the transmittance of the optical system, that is, the amount of light that irradiates each light valve 21R, 21G, 21B. As a result, there is an effect of increasing the efficiency and illuminance of the projection apparatus. In addition, as described in the fourth embodiment, since the cut wavelength can be sharpened, the color characteristics of the image can be improved. However, when the incident polarized light to each light valve 21R, 21G, 21B is different, the polarization rotating means for rotating the polarization azimuth to the light incident side of each light valve 21R, 21G, 21B, or the polarization shaping for shaping the polarization azimuth. Means are provided. A λ / 2 retardation plate can be used as a low-cost, simple and highly efficient polarization rotating means.

  Next, a projection display apparatus according to an eighth embodiment of the present invention is described with reference to FIG. In this embodiment, the optical path from the light source 1 to each light valve 21R, 21G, 21B and its operation are the same as in the third embodiment, but the second dichroic prism 162 '' reflects red light. Is configured to do. The projection lens 16 is changed to a position where the reflected light of the red light of the second dichroic prism 162 ″ is projected. In addition, the color composition optical system of the projection display device according to the present embodiment has a plurality of dichroic mirrors whose surfaces are in contact with a solid or liquid, that is, first and second dichroic prisms 160 ″ and 162 ′. The polarization rotation means 182 is disposed between the two.

  Blue light spatially modulated by the blue light valve 21B is converted into a polarization orientation parallel to the paper surface by the polarization rotation element 182. Accordingly, the light enters the first dichroic prism 160 ″ as p-polarized light and passes through the prism 160 ″. The green light spatially modulated by the green light valve 21G is converted into a polarization orientation perpendicular to the paper surface by the polarization rotation element 182. Therefore, the light enters the first dichroic prism 160 ″ as s-polarized light and is reflected by the prism 160 ″. At this time, blue light and green light are emitted from the first dichroic prism 160 '' while maintaining the polarization direction by color synthesis. Next, the light is incident on the polarization rotating means 182, and blue light is converted into s-polarized light in the second dichroic prism 162 ″, and green light is p-polarized light in the second dichroic prism 162 ″. , Is incident on and transmitted through the second dichroic prism 162 ″, and travels toward the projection lens 16.

  The red light spatially modulated by the red light valve 21R is converted into a polarization azimuth perpendicular to the paper surface by the polarization rotation element 180, enters the total reflection prism 164 ', and the optical path is bent to form the second dichroic prism. Incident at 162 ″. Accordingly, the light enters the second dichroic prism 162 ″ as s-polarized light and is reflected by the prism 162 ″. At this time, the red light is combined with the blue and green combined light incident from the first dichroic prism 160 ″ and the second dichroic prism 162 ″. The combined light emitted from the second dichroic prism 162 '' enters the projection lens 16 and is enlarged and projected on the screen. Here, the cut wavelengths of the p-polarized light and the s-polarized light of the second dichroic prism 162 ″ are 620 nm and 580 nm, respectively. With this configuration, since the green light incident from the first dichroic prism 160 ″ is p-polarized light, light having a wavelength of 620 nm or less is transmitted. Similarly, since blue light is s-polarized light, light having a wavelength of 580 nm or less is transmitted. Since blue light originally has a wavelength of 520 nm or less, all blue light is transmitted.

  Moreover, since red light is s-polarized light, light of 580 nm or more is reflected. As a result, all the light including the leakage light in the vicinity of the cut wavelengths of red and green light can be used for the projection light, which is effective in increasing the light amount of the projection apparatus. Similarly, since the cut wavelength for each color can be made different, the degree of freedom in color design can be increased, and the amount of light of the image can be increased or the color purity can be increased.

  As the polarization rotating means 180 and 182, it is easy to use a uniaxial crystal flat plate cut parallel to the optical axis of the crystal, a mica plate, a crystal wave plate, or a λ / 2 retardation plate using a uniaxially stretched film at low cost. And highly efficient.

  The same effect can be obtained by attaching the polarization rotating means 182 to the light exit surface of the first dichroic prism 160 ″ or the light entrance surface of the second dichroic prism 162 ″. Since two surfaces can be reduced, it is possible to contribute to further increase in the amount of light.

  The polarization rotating means 180 disposed in the vicinity of the polarizing plates 158R, 158G, and 158B of the light valves 21R, 21G, and 21B is also attached to the polarizing plates 158R, 158G, and 158B or the prisms 160 ″ and 164 ′ so that the surface reflection surface is provided. Since two surfaces can be reduced, the amount of light can be further increased.

  Next, a projection display apparatus according to a ninth embodiment of the invention is shown in FIG. In FIG. 20, an optical element 184 that changes the direction of the light beam is arranged between the light source 1 and the color separation optical system, and the latter is adjacent to the light source 1 and the color separation optical system. The rest is the same as the display device shown in FIG. By adopting this configuration, it is possible to reduce the size of the device housing that encloses the entire optical system, and it is possible to realize cost reduction and device size reduction.

Next, a projection display apparatus according to a tenth embodiment of the present invention is shown in FIG. The display device shown in FIG. 21 includes a light source 1 and a color separation optical system that separates light emitted from the light source 1 into a plurality of color lights. In addition, a plurality of light valves 21R, 21G, and 21B that spatially modulate a plurality of color lights emitted from the color separation optical system and a color synthesis optical system that combines a plurality of color lights spatially modulated for each color are provided. A projection lens 16 that projects a plurality of synthesized color lights is also provided. The color separation optical system includes two dichroic mirrors 140 ″ and 142 ″ and a total reflection mirror 144 ″. The color synthesis optical system has dichroic prisms 160 ′ and 162 ′ which are two dichroic mirrors whose both surfaces are in contact with a solid or liquid. The color synthesis optical system further includes a total reflection prism 164 ′ which is a total reflection mirror whose both surfaces are in contact with a solid or liquid. The projection display apparatus according to the present embodiment is characterized in that all the dichroic mirrors of the color separation system and the color synthesis system described above are low-pass filters or high-pass filters. Table 1 shows the combinations of color separation and synthesis in this configuration. There are eight combinations as shown in Table 1 from the order of color separation, the position of the projection lens 16, and the position of the light source 1. In this combination table, the seventh term has already been explained in the third embodiment, and the fifth term has been explained in the eighth embodiment. In Table 1, DM1 is a first dichroic mirror, DM2 is a second dichroic mirror, DP1 is a first dichroic prism, and DP2 is a second dichroic prism.

  By adopting these configurations shown in Table 1, it is possible to realize a projection optical system that suppresses an increase in cost and does not have the problems of chromaticity deviation and pixel deviation already described.

次に、本発明の第１１の実施の形態による投写型表示装置について説明する。本実施の形態による表示装置は、表１において、色分離・合成の組合せとして色分離光学系は、赤透過タイプのローパス・フィルタである第１のダイクロイック・ミラーＤＭ１と、青透過タイプのハイパス・フィルタである第２のダイクロイック・ミラーＤＭ２と、全反射ミラー１４４''から構成されている。色合成光学系は、赤透過タイプのローパス・フィルタである第１のダイクロイック・プリズムＤＰ１と、赤と緑（黄色）透過タイプのローパス・フィルタである第２のダイクロイック・プリズムＤＰ２と、全反射プリズム１６４'とから構成されている。

Next, a projection display apparatus according to an eleventh embodiment of the present invention is described. In the display device according to the present embodiment, in Table 1, as a combination of color separation and synthesis, the color separation optical system includes a first dichroic mirror DM1, which is a red transmission type low-pass filter, and a blue transmission type high-pass filter. The filter is composed of a second dichroic mirror DM2 as a filter and a total reflection mirror 144 ''. The color synthesis optical system includes a first dichroic prism DP1 that is a red transmission type low-pass filter, a second dichroic prism DP2 that is a red and green (yellow) transmission type low-pass filter, and a total reflection prism. 164 ′.

  By adopting such a configuration, the coating of DM1 and DP1 can be made the same, so that the coating operation can be performed simultaneously, and the cost required for the coating can be reduced. This effect is the same in the first, third, fourth, fifth, seventh and eighth terms in Table 1. Further, red and green images in which pixel deviation is conspicuous can be synthesized at DP1, and the probability of pixel deviation can be further reduced. The first to fourth items in Table 1 have the same effect. In addition, since the reflection characteristic can be set higher than the transmission characteristic, blue light, which tends to decrease in amount of light compared to red, can be projected only by DM2 transmission, and everything else can be projected by reflection. There is an effect to improve. The reason why the amount of blue light tends to decrease is that the blue light having a wavelength of 420 nm to 430 nm or less is reduced by the UV cut prism that cuts the UV light emitted from the light source 1.

  Next, a color separation / synthesis optical system of a projection display apparatus according to a twelfth embodiment of the present invention will be described. The apparatus configuration is the same as in the eleventh embodiment. In the present embodiment, the cut wavelength of each dichroic mirror, prism DM1, DP1 is defined. The cut wavelength of the transmitted light of the first dichroic mirror DM1 is 560 to 590 nm, the cut wavelength λdp1 of the reflected light of the first dichroic prism DP1 is 590 to 620 nm, and similarly the cut of the transmitted light of the first dichroic prism DP1 The wavelength is equal to or smaller than λdp1.

  Among the white light, yellow light having a wavelength of 560 to 590 nm is incident on the red light valve 21R, and when projected, there is a problem that red color purity is lowered and red becomes orange. Similarly, when yellow light is incident on the green light valve 21G, there is a problem that when this is projected, the color purity of the green is lowered and green becomes yellow. In addition, the green light valve 21G has a large amount of light as compared with the red light valve 21R, and there is a problem that problems due to heat generation are likely to occur.

  These problems can be solved by using this configuration. That is, yellow light having a wavelength of 560 to 590 nm is transmitted through DM1, and after entering the red light valve 21R, is reflected off the optical path by DP1 so as not to be projected. Therefore, it is not necessary to increase the amount of light of the green light valve 21G while maintaining the red and green color purity high, so that heat generation can be suppressed.

  Next, a projection display apparatus according to a thirteenth embodiment of the present invention is described. The color separation / synthesis optical system in the present embodiment is the same as that in the eleventh embodiment. In the present embodiment, the cut wavelengths of the dichroic mirror DM2 and prism DP2 are defined.

  The cut wavelength of the transmitted light of the second dichroic mirror DM2 is 480 to 510 nm, the cut wavelength λdp2 of the reflected light of the second dichroic prism DP2 is 510 to 540 nm, and similarly the cut of the transmitted light of the second dichroic prism DP2 The wavelength is smaller than λdp2.

  Since the light having a wavelength of 480 to 510 nm at the boundary between the blue and green colors is light blue, it is blue regardless of whether it is incident on the blue light valve 21B or projected on the green light valve 21G. The decrease in the color purity of each green is slight, and the problem due to yellow light as described in the third embodiment does not occur.

  With this configuration, the blue light valve 21B can project all light having a wavelength of 480 to 510 nm or less, and green and red light can project all light having a wavelength of 510 nm or more. Can be prevented, while reducing the amount of green and red light.

  Next, a projection display apparatus and an operation principle thereof according to a fourteenth embodiment of the present invention will be described with reference to FIG. In the present embodiment, the projection lens 16, the dichroic prism 160, and the two light valves 21R and 21G are shown as part of the color synthesis optical system of the projection optical system.

  The dichroic prism of the color synthesizing optical system is changed even if the angle formed by the line connecting the approximate center of the entrance pupil of the projection lens 16 from an arbitrary point of each light valve 21R, 21G and the filter surface of the dichroic prism 160 changes. The present embodiment is characterized in that the cut wavelengths of 160 are substantially the same. In order to realize this, the filter characteristic of the ichroic prism 160 according to the present embodiment has an in-plane distribution.

  In FIG. 22, the incident angle of incident light is 45 ° at point O of the dichroic prism 160, whereas it is 50 ° at point A and 40 ° at point B. Thus, the cut wavelength of the dichroic prism 160 is set to be the same even if the incident angle varies depending on the position. For this reason, a thin film having a cut wavelength of 600 nm is formed at an incident angle of 50 ° at the point A, and a thin film is formed so as to have the same cut wavelength at an incident angle of 45 ° at the point O. In this respect, a thin film having the same cut wavelength at an incident angle of 40 ° is formed. The film characteristics are changed between the points A and O and between the points O and B so that intermediate characteristics that gradually change depending on the location can be obtained. Such film characteristics can be obtained by forming a multilayer interference film constituting a dichroic filter by using an oblique deposition method.

  By configuring the filter according to the present embodiment, it is possible to prevent color unevenness of the projected image due to the incident angle distribution.

  Incidentally, since the incident angle distribution hardly occurs in the direction perpendicular to the paper surface of the dichroic prism 160, there is little need to provide the characteristic distribution according to the position of the filter film as described above.

  Next, the operation principle of the projection display apparatus according to the fifteenth embodiment of the invention will be described with reference to FIG. FIG. 23 shows, as an example, the light source 1 of the projection optical system, a part of the color separation optical system, the light source 1, the dichroic mirror 140, and the two light valves 21R and 21G.

  The present embodiment corresponds to the angle formed by a straight line connected from each arbitrary point of the light source 1 to the approximate center of each of the liquid crystal panels 158R and 158G of the light valves 21R and 21G and the filter surface of the dichroic mirror 140. Further, the present invention is characterized in that a distribution is provided in the filter characteristics of the dichroic mirror of the color separation optical system.

  In FIG. 23, the incident angle is 45 ° at point O of the dichroic mirror 140, whereas it is 50 ° at point A and 40 ° at point B. In the present embodiment, a uniform cut wavelength is obtained regardless of the position of the filter surface of the dichroic mirror 140. That is, a thin film having a cut wavelength of 500 nm at an incident angle of 50 ° is formed at point A, a thin film that can obtain the same cut wavelength at an incident angle of 45 ° is formed at point O, and 30 is formed at point B. A thin film having the same cut wavelength is formed at an incident angle of °. Between the point A and the point O and between the point O and the point B, the intermediate characteristic of each characteristic is formed so as to be a film characteristic that gradually changes depending on the position.

  This film characteristic can be realized by forming a multilayer interference film of a dichroic filter by an oblique deposition method. The film configuration according to the present embodiment can prevent uneven color in the projected image due to the incident angle distribution.

  Incidentally, since the incident angle distribution hardly occurs in the direction perpendicular to the paper surface of the dichroic mirror 140, the necessity of applying the film characteristic distribution is small.

  A projection display apparatus according to a sixteenth embodiment of the present invention will be described with reference to FIG. The present embodiment is substantially the same in the configuration of the color separation / combination optical system as in FIG. 21, but is characterized in that the total reflection mirror 144 ″ in FIG. 21 is replaced with a dichroic mirror 190. The dichroic mirror 190 is formed so that the cut wavelength of reflected light is 590 to 620 nm. Accordingly, light having a wavelength longer than this wavelength is reflected by the dichroic mirror 190, and light having a shorter wavelength is transmitted.

  By adopting such a configuration, unnecessary yellow light is transmitted through the dichroic mirror 190 and escaped, and can be prevented from entering the red light valve 21R. By using the dichroic mirror 190, the reliability of the light valve can be prevented from being lowered, the degree of freedom in selecting the cut wavelength can be increased, and the effects of high color purity and high brightness can be expected.

  A dichroic prism may be used instead of the total reflection prism 164 ′ in the color separation / synthesis optical system of the present embodiment. In this case, the cut wavelength of the reflected light at the dichroic prism is 510 to 540 nm, light having a wavelength longer than this wavelength is transmitted, and light having a shorter wavelength is reflected. By adopting such a configuration, it is possible to prevent the leakage light near the cut wavelength from being projected and to improve the color purity of the projected image. In addition, the degree of freedom in selecting the cut wavelength can be increased, and the effect of high color purity and high brightness can be expected.

  Next, a projection display apparatus according to a seventeenth embodiment of the present invention is described with reference to FIG. The present embodiment is characterized in that the fixing jig for the dichroic mirror 190 is improved. That is, the light absorbing material is arranged on the back surface of the dichroic mirror 190 or on the wall surface after passing through the mirror. In FIG. 25, a black light absorbing material 192 is sandwiched between the mirror 190 and the mounting bracket so as to absorb the transmitted light of the dichroic mirror 190. By doing so, compared to the case where the light absorbing material 192 is not used, stray light in the apparatus due to light transmitted through the dichroic mirror 190 can be reduced, and the contrast of the projected image can be improved. Become.

  Similarly, the light absorbing material 196 may be disposed on the back surface of the dichroic prism 194 disposed in place of the prism mirror 164 ′ or on the wall surface after transmitting the prism. In FIG. 25, a black light absorbing material 196 is sandwiched between the prism 194 and the mounting bracket so as to absorb the light transmitted through the dichroic prism 194. By so doing, stray light in the apparatus due to light transmitted through the dichroic prism 194 can be reduced and the contrast of the projected image can be improved as compared with the case where the light absorber 194 is not used. Become.

  Next, a projection display apparatus according to an eighteenth embodiment of the present invention is described. This embodiment is characterized in that the reflection films of the total reflection mirror 144 ″ and the total reflection prism 164 ′ in the third embodiment shown in FIG. 14 are dielectric multilayer films. A mirror formed of an aluminum or silver vapor deposition film generally has a reflectivity of about 90%, but when formed of a dielectric multilayer film as in this embodiment, a reflectivity of about 95% can be obtained. . Such a configuration can contribute to an increase in the amount of light in the projection apparatus.

  Next, a projection display apparatus according to a nineteenth embodiment of the present invention is described with reference to FIGS. FIG. 26 shows a schematic configuration of the projection display apparatus according to the present embodiment. In FIG. 26, the white light emitted from the light source 300 is converted into a polarization azimuth (referred to as s-polarized light for convenience) perpendicular to the paper surface by the polarization conversion element 302. Light emitted from the light source 300 is bent by 90 ° by the mirror 303. Since the mirror 303 has a higher reflectivity for s-polarized light than light having a polarization orientation parallel to the paper surface (p-polarized light), it is more efficient to use the device with light converted to s-polarized light by the polarization conversion element 302. . Further, due to the presence and arrangement of the mirror 303, the light having an angle with respect to the optical axis X emitted directly from the lamp without being reflected by the reflector of the light source 300 without increasing the size of the apparatus is shown in FIG. 27 (a) and 27 (b), it is possible to prevent the light from directly entering the liquid crystal panels 306 and 310 without going through the dichroic mirror 304 to increase the panel temperature or to become stray light.

  The light reflected by the mirror 303 is transmitted through red light by the dichroic mirror 304 and is separated by color by reflecting green and blue light. The transmitted red light is efficiently reflected by the mirror 305 having excellent s-polarized reflection characteristics, bent 90 °, and incident on the red liquid crystal panel 306 with the polarization direction changed by 45 ° by the phase difference plate. The emission light modulated by the liquid crystal panel 306 is further converted in polarization direction by 90 °, passes through the polarizing plate, and further changed in polarization direction by 45 ° by the phase difference plate to become p-polarized light as shown in FIG. As shown, the light passes through a glass plate (white plate) 307 and a dichroic mirror 308 which are 5 mm thick and are inclined by 15 ° with respect to the optical axis. The glass plate 307 is used to correct an optical path shift that occurs when light passes through the dichroic mirror 308. If the glass plate 307 is formed of a material such as borosilicate glass or quartz that is expensive but has a low refractive index, the thickness of the glass plate can be reduced and the device capacity can be reduced. By correcting the optical path deviation by the glass plate 307, a good projected image free from color deviation and astigmatism can be obtained. In addition to this correction method, the dichroic mirror 308 itself is made thin to reduce the optical path deviation, or the dichroic mirror 308 and the mirror 313 are made dichroic prisms so that the glass incidence is substantially perpendicular to the optical axis. -It is also possible to reduce the optical path deviation by forming an exit surface.

  The green light reflected by the dichroic mirror 304 is reflected by the next stage dichroic mirror 309, passes through the liquid crystal panel 310, the polarizing plate, and the phase difference plate, and becomes p-polarized light by the dichroic mirror 308. Reflected. The blue light passes through the dichroic mirror 309, passes through the liquid crystal panel 311 and the polarizing plate, is converted into s-polarized light by the phase difference plate 312, and is bent by the mirror 313. This blue light is reflected by the dichroic prism 314 having the characteristics shown in FIG. 29, is incident on the projection lens 315, and is projected.

  The combined red and green light is transmitted through the dichroic prism 314 with the p-polarization characteristic shown in FIG. In addition, since red and green, which have a large amount of light, where color misregistration is conspicuous, are combined first, the pixel misalignment of the display pixels can be adjusted only by adjusting the angle of the dichroic mirror 308. Assembling efficiency is improved and the cost can be reduced.

  Thus, according to the present embodiment, the apparatus capacity can be minimized by arranging the mirror 303. Further, by providing the mirror 303, it is possible to prevent unnecessary light from entering each liquid crystal panel. Furthermore, since the light incident on the mirror 303 is reflected as s-polarized light, the reflectance can be improved. In addition, since the green and red lights are first color-combined by the dichroic mirror 308 while preventing the display quality from being deteriorated due to aberration, the efficiency of pixel matching can be increased. Since the dichroic mirror uses p-polarized light more efficiently than s-polarized light, the amount of light used can be increased by using green and red light as p-polarized light. The dichroic prism 314 uses blue light as reflected light as s-polarized light, green light and red light as transmitted light as p-polarized light, and green and red lights having different wavelengths as different polarization characteristics. As a result, the transmission / reflection efficiency can be increased, so that the light utilization efficiency can be improved.

  The present invention is not limited to the above embodiment, and various modifications can be made.

  In the above embodiment, the transmissive liquid crystal light valve that transmits the light guided from the light source 1 by the dichroic mirrors 4, 6, and 8 and displays an image on a screen (not shown) is used. However, the present invention is not limited to this, and it is also possible to use a reflective liquid crystal light valve using a reflective liquid crystal panel that reflects light from a light source and displays an image on a screen. In this case, it is effective when the switching element is irradiated from the back surface when the light incident on the reflective liquid crystal panel is reflected. In the case of using a reflective liquid crystal panel, the color separation optical system and the color synthesis optical system may be shared in whole or in part. In this case, the apparatus can be downsized.

  In the above embodiment, the present invention is applied to a projection display apparatus having a rear projection type screen. However, the present invention is not limited to this and can be applied to a front projection type display apparatus.

  The present invention can also be applied to the case where an EL (electroluminescence) light emitting display element provided with a switching element is used for a light valve.

  In the above embodiment, the p-Si TFT is used as the switching element of the liquid crystal panel. However, the present invention can naturally be applied even when an a-Si (amorphous silicon) TFT or MIM is used as the switching element. It is.

  In applying the present invention, it is clear that the arrangement of the color synthesis optical system and the polarization conversion element is not limited to the configuration exemplified in the above embodiment. For example, in the configuration shown in FIG. 4, the half-wave plate 20Bi is disposed on the light incident side of the blue liquid crystal light valve. However, the present invention is not limited to this. For example, white light from the light source 1 is blue. When separating into color components other than blue and blue, a polarization separation element (for example, a polarization beam splitter) that makes the polarization direction of blue light orthogonal to the polarization direction of other red and green light is used as a polarization conversion means. Of course, it may be arranged between each of the liquid crystal panels 20R, 20G, 20B and the light source 1.

  Of course, a color filter for color correction may be inserted in front of each liquid crystal light valve.

  In the above-described embodiment, the description has been given using the normally white liquid crystal panel. However, the present invention is not limited to this, and the present invention is not limited to this, but a projection display apparatus having a liquid crystal light valve using a normally black liquid crystal panel. Can of course also be applied.

  In the above embodiment, each liquid crystal panel 20R, 20G, 20B has been described as having a TN liquid crystal layer. However, the present invention is not limited to this, and may be applied to a vertical alignment type (VA type) liquid crystal panel. Is possible.

  In the above embodiment, a transmissive screen combining a lenticular lens and a Fresnel lens has been described as an example. However, a phenomenon in which light distribution characteristics differ due to a difference in polarization direction also occurs in a Fresnel lens. Color unevenness and color shift also occur when using a lens-type light distribution (diffusion) element. The same phenomenon occurs when the light passes through the simple diffusion plate. The present invention can be applied to almost all of these screens in the same manner as in the above embodiment.

The present invention is applicable to a projection type liquid crystal display device using a light valve.

1 is a diagram showing a schematic configuration of a projection display apparatus according to a first embodiment of the present invention. It is a figure which shows the effect by the projection type display apparatus by the 1st Embodiment of this invention. It is a figure which shows the other structural example vicinity of the liquid crystal light valve and dichroic prism of the projection type display apparatus by the 1st Embodiment of this invention. It is a figure which shows the further another structural example of the liquid crystal light valve and dichroic prism vicinity of the projection type display apparatus by the 1st Embodiment of this invention. It is a figure which shows the further another structural example of the liquid crystal light valve of the projection type display apparatus by the 1st Embodiment of this invention, and the dichroic prism vicinity. It is a figure which shows the structure of the outline of the projection type display apparatus by the 2nd Embodiment of this invention. It is a figure which shows the other structural example of the projection type display apparatus by the 2nd Embodiment of this invention. It is a figure which shows the structure of the modification of the projection type display apparatus by the 2nd Embodiment of this invention. It is a figure which shows the structure of the other modification of the projection type display apparatus by the 2nd Embodiment of this invention. It is a figure which shows the structure of the further another modification of the projection type display apparatus by the 2nd Embodiment of this invention. It is a figure which shows the structure of the further another modification of the projection type display apparatus by the 2nd Embodiment of this invention. It is a figure which shows the structure of the further another modification of the projection type display apparatus by the 2nd Embodiment of this invention. It is a figure explaining the principle of the projection type display apparatus by which this invention implement | achieved by the present invention without a pixel shift and chromaticity shift | offset | difference. It is a figure which shows the schematic structure of the projection type display apparatus by the 3rd Embodiment of this invention. It is a figure explaining the projection type display apparatus by the 4th Embodiment of this invention. It is a figure explaining the projection type display apparatus by the 4th Embodiment of this invention. It is a figure which shows the structure of the outline of the projection type display apparatus by the 6th Embodiment of this invention. It is a figure which shows the schematic structure of the projection type display apparatus by the 7th Embodiment of this invention. It is a figure which shows the structure of the outline of the projection type display apparatus by the 8th Embodiment of this invention. It is a figure which shows the structure of the outline of the projection type display apparatus by the 9th Embodiment of this invention. It is a figure which shows the structure of the outline of the projection type display apparatus by the 10th Embodiment of this invention. It is a figure which shows the outline of the projection type display apparatus by 14th Embodiment of this invention, and its operation principle. It is a figure which shows the outline of the principle of operation of the projection type display apparatus by 15th Embodiment of this invention. It is a figure which shows the structure of the outline of the projection type display apparatus by the 16th Embodiment of this invention. It is a figure which shows the structure of the outline of the projection type display apparatus by the 17th Embodiment of this invention. It is a figure which shows the schematic structure of the projection type display apparatus by 19th Embodiment of this invention. It is a figure explaining the projection type display apparatus by the 19th Embodiment of this invention. It is a figure explaining the projection type display apparatus by the 19th Embodiment of this invention. It is a figure explaining the projection type display apparatus by the 19th Embodiment of this invention. It is a figure which shows the schematic structure of the conventional projection display apparatus. It is a figure showing the structure of a liquid crystal panel. It is a figure explaining the problem which arises in the conventional projection display apparatus. It is a figure explaining the problem which arises in the conventional projection display apparatus. It is a figure which shows the structure of the outline of the proposed projection display apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light source 2 Polarization conversion apparatus 4, 6, 8, 61 Dichroic mirror 10, 12, 60 Mirror 14, 15, 70 Dichroic prism 14a, 14b, 15a, 70a Dichroic surface 16 Projection lens 21R, 21G, 21B Liquid crystal light valve 20R, 20G, 20B Liquid crystal panels 20Rp, 20Gp, 20Bp Polarizing plates 20Ri, 20Gi, 20Bi Half-wave plates 20Ri ', 20Gi', 20Bi 'Half-wave plates 20Rl, 20Gl, 20Bl Liquid crystal panels 30, 32 Transmission axes 34, 36 Polarization direction 40 1/4 wavelength plate 41, 51 Optical axis 42 Screen 44 Double-sided lenticular lens 46 Fresnel lens 50, 71 Half wavelength plate 52, 53 Transmission axis 54, 55 Polarization direction 56, 57 Circular polarization 100 Array substrate 102 Opposing Substrate 104 switching element 106 liquid crystal layer 108 insulating film 110 display electrode 112 common electrode 114 light blocking film 120, 126 n-type polysilicon layer 122 gate insulating film 124 of polysilicon layer 128 gate electrode 130 drain electrode

Claims (16)

Three light valves that each have a polarizing plate at least on the light exit side and modulate and emit light of each color component of red, green, and blue, and color composition that color-combines each light emitted from each light valve In a projection display device comprising an optical system and a projection lens that projects color-synthesized light onto a screen,
A projection type comprising polarization conversion means for converting the polarization state of the light of each color component so that the ratio of at least the horizontal light amount and the vertical light amount on the screen is substantially equal for each color. Display device. The projection display device according to claim 1,
The polarization conversion means is configured such that a bisector of an angle formed by the polarization direction of light of one color component and the polarization direction of light of another color component is the horizontal line or vertical line of the screen. A projection display device characterized by converting into linearly polarized light that substantially matches one of the lines. The projection display device according to claim 2, wherein
A projection display device, wherein the polarization direction of the light of the one color component is substantially orthogonal to the polarization direction of the light of the other color component. The projection display device according to any one of claims 1 to 3,
The projection display device, wherein the polarization conversion unit includes a half-wave plate disposed on a light emission side of the color synthesis optical system. The projection display device according to claim 1,
The projection display device is characterized in that the polarization conversion means converts the color-synthesized lights into substantially circularly polarized light. The projection display device according to claim 5, wherein
The projection display device characterized in that the polarization conversion means has a quarter-wave plate disposed on the light exit side of the color synthesis optical system. The projection display device according to any one of claims 1 to 6,
The light valve has a liquid crystal panel. The projection display device according to any one of claims 1 to 7,
The projection display apparatus, further comprising a screen on which light projected from the projection lens is incident, wherein the screen includes a Fresnel lens and a lenticular lens. A color separation optical system that includes at least one dichroic mirror and a light reflection mirror, and separates light emitted from the light source into red, green, and blue color components;
Three light valves each having a polarizing plate at least on the light emitting side, and modulating and emitting light of each color component of red, green, and blue,
In a projection display device having a color synthesis optical system that color-synthesizes each light emitted from each light valve,
The color synthesizing optical system includes at least one dichroic mirror having both surfaces in contact with a solid or liquid, and at least one light reflecting mirror having a surface in contact with the solid or liquid. And the dichroic mirror of the color synthesis optical system has a low-pass filter or a high-pass filter. The projection display device according to claim 9, wherein
The projection display apparatus characterized in that the reflected light of the dichroic mirror having both surfaces in contact with a solid or liquid is s-polarized light. The projection display device according to claim 9 or 10,
The projection display device characterized in that the transmitted light of the dichroic mirror having both surfaces in contact with a solid or liquid is p-polarized light. The projection display device according to any one of claims 9 to 11,
The projection display device, wherein the light source emits polarized light. The projection display device according to any one of claims 9 to 12,
The color separation optical system includes a first dichroic mirror that functions as a low-pass filter that transmits red light, and a second dichroic mirror that functions as a high-pass filter that transmits blue light,
The color synthesis optical system includes a first dichroic prism that functions as a low-pass filter that transmits red light, and a second dichroic prism that functions as a low-pass filter that transmits red and green. A projection type display device characterized by The projection display device according to claim 13, wherein
The cut wavelength of the transmitted light of the first dichroic mirror is 560 to 590 nm, the cut wavelength of the reflected light of the first dichroic prism is 590 to 620 nm, and the transmitted light of the first dichroic prism The projection display device is characterized in that the cut wavelength is less than or equal to the cut wavelength of the reflected light. The projection display device according to claim 13 or 14,
The cut wavelength of the transmitted light of the second dichroic mirror is 480 to 510 nm, the cut wavelength of the reflected light of the second dichroic prism is 510 to 540 nm, and the transmitted light of the second dichroic prism The projection display device is characterized in that the cut wavelength is smaller than the cut wavelength of the reflected light. The projection display device according to any one of claims 9 to 15,
A projection display device comprising a light-absorbing material that absorbs light transmitted through the dichroic mirror.

Images