JP4928909B2 - Projection display - Google Patents

Description

  The present invention relates to a projection display device that displays a color image.

  As a typical configuration of a projection display device capable of color display, one using three primary colors of red (R), green (G), and blue (B) is known. FIG. 3 is a schematic diagram showing a dichroic prism type three-plate liquid crystal panel (3LCD) projection display device as a conventional projection display device.

  A dichroic prism type 3LCD projection display device will be described with reference to FIG. The light source 101 of the 3LCD projection display apparatus 100 includes a high-pressure mercury lamp 101a and a parabolic reflector 101b that converts the white light emitted from the lamp 101a into a substantially parallel light flux. The light emitted from the light source 100 is removed by a UVIR filter (not shown) to reduce the thermal load on the subsequent optical member.

  The light emitted as parallel light by the parabolic reflector 100b is split into light beams by a so-called fly eye integrator including first and second fly eye lenses 103 and 104 formed of a convex lens group. The respective light beams converge and enter the polarization conversion element 105, and are emitted with the polarization directions aligned.

  Then, the light whose polarization directions are aligned passes through the condenser lens 106 and the like, and then the red to green band light is transmitted by the dichroic mirror 107 and the blue band light is reflected.

  The blue band light reflected by the dichroic mirror 107 and whose optical path is changed by 90 degrees is changed by the total reflection mirror 108 and the optical path is changed by 90 degrees and is incident on the blue liquid crystal display element 120B for displaying the blue band light component image via the field lens 109B. Here, the light is modulated according to the input signal.

  The light modulated light enters the dichroic prism 121, enters the projection lens 130 with the optical path changed by 90 degrees in the dichroic prism 121, is enlarged and projected, and is imaged on a screen (not shown).

  On the other hand, the red to green band light transmitted through the dichroic mirror 107 enters the dichroic mirror 112. Since the dichroic mirror 112 has a characteristic of reflecting the green band light, the green band light is reflected here, the optical path is changed by 90 degrees, and the green band light component image is displayed via the field lens 119G. The light enters the liquid crystal display element 120G and is optically modulated according to the input signal. The light-modulated green band light enters the dichroic prism 121 and the projection lens 130 in this order, and is enlarged and projected to form an image on the screen.

  The red band light transmitted through the dichroic mirror 112 is incident on the red liquid crystal display element 120R for displaying the red band light component image from the field lens 129R via the lenses 123 to 124 and the total reflection mirrors 126 and 127, where the input signal The light is modulated in response to. The light-modulated red band light is incident on the dichroic prism 121, is incident on the projection lens 130 with the optical path changed by 90 degrees by the dichroic prism 121, is enlarged and projected, and is imaged on the screen.

  Each of the liquid crystal display elements 120B, 120G, and 120R includes an incident side polarizing plate PI, a liquid crystal LC, and an output side polarizing plate PO. The liquid crystal display element is provided with an incident side polarizing plate PI and an output side polarizing plate PO.

  In the 3LCD projection display device described above, since the three primary colors are synthesized by the dichroic prism, the optical path length of one primary color is different from the optical path lengths of the other two primary colors. In the example described above, the optical path length of G light is different from the optical path lengths of the other two primary colors, and a relay optical system is required. In addition, the color reproduction range is also limited to the inside of the color triangle defined by the three primary color chromaticity coordinates, and is currently much narrower than the reproduction range of the xy chromaticity diagram. FIG. 2 shows a schematic diagram of an xy chromaticity diagram (CIE chromaticity diagram). In this figure, black squares indicate the chromaticities of R, G, and B primary colors by conventional color separation.

As described above, in the conventional projection display apparatus that separates colors into three colors, the color reproducibility is not good. In order to solve this problem, there has been proposed a projection display device that is color-separated into four colors of blue, emerald, green, and red (see Patent Document 1).
JP-A-2005-241904

  In the projection display device described above, since four colors of blue, emerald, green, and red are used, the color reproduction range becomes wider than the chromaticity range of the three primary colors, and the color reproducibility is improved. However, in the projection apparatus described above, light from one light source is separated into four colors by a color separation system. For this reason, it is difficult to define the color ranges of the four primary colors to appropriate color intensities. Further, the optical path lengths of the two primary colors are different from the optical path lengths of the other two primary colors, and there is a possibility that the color intensity may be uneven.

  The present invention has been made in view of the above-described conventional problems, and an object thereof is to provide a projection display device that widens the color reproduction range and has no unevenness in color intensity.

  The present invention includes a first light source, a first color separation optical system that separates white light from the first light source into two colors of a first color and a second color, and a first color separation optical system. First and second light modulation elements that modulate each of the separated colors in response to a color signal, a second light source, and white light from the second light source for the third and fourth colors. A second color separation optical system that separates into two colors, a third and a fourth light modulation element that modulates each color separated by the second color separation optical system in accordance with a color signal, and A color combining unit configured to combine the modulated light modulated by the first to fourth light modulation elements; and a projection unit configured to enlarge and project the combined light from the color combining unit.

  The first color separation system can be configured to separate white light into two colors, red and cyan, and the second color separation system can be separated into two colors, blue, green, and yellow.

  The first and second color separation systems can be composed of two dichroic mirrors having different cutoff frequencies.

The color composition means has a first dichroic prism having a characteristic of reflecting red band light and transmitting cyan band light, and a characteristic of reflecting green or yellow band light and transmitting blue band light. The second dichroic prism can have a polarization beam splitter that receives light from the first and second dichroic prisms.

  Furthermore, the present invention provides a first color rotator that is provided between the first dichroic prism and the polarization beam splitter and rotates a polarization plane in a wavelength range from red to cyan, the second dichroic prism, and the polarization. And a second color rotator for rotating a polarization plane in a wavelength range from blue to yellow provided between the beam splitter and the beam splitter.

  In the present invention, two light sources are used, and each light source is divided into two colors by a color separation optical system, then modulated by a color signal of each color by a video modulation element, and the modulated light is synthesized by a color synthesizing unit. Therefore, the light quantity ratio for one lamp can be improved from about 1.5 to about 1.8 times. Also, since the two light sources are separated into two colors by each light source, the optical path lengths can be made equal, and unevenness in light intensity can be eliminated.

  In addition, by selecting the chromaticity of the four colors, the color reproduction range can be greatly expanded, and intermediate colors that could not be reproduced with the three-color configuration can be reproduced, and two light sources can be used. Therefore, it is easy to select a desired color reproduction range.

  Embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram showing the configuration of a projection display apparatus according to the first embodiment of the present invention. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and the description thereof will not be repeated in order to avoid duplication of description.

  As shown in FIG. 1, the present invention has two light sources 10 and 50, and the light of the first light source 10 is separated into two colors of red (R) and cyan (Cy) by a color separation optical system, Each light is given to the light modulation element, modulated by the color signal of each color, and then given to the color synthesis means. The second light source 50 is separated into two colors of blue (B) and green (G) by a color separation optical system, and each light is supplied to a light modulation element and modulated by a color signal of each color. Give to the synthesis means. The light combining means combines the four colors of image light and projects them from the projection lens 70 onto the screen. That is, in this embodiment, the two light sources 10 and 50 are used, and each light source is divided into two colors by the color separation optical system, and then modulated by the color signal of each color by the video modulation element.

  By using the two light sources 10 and 50 as in the present invention, the light quantity ratio to one lamp becomes about 1.8 times. Further, if the color to be decomposed is shifted from green (G) to yellow (Y), the color reproduction range can be expanded. In this case, the light quantity ratio for one lamp is about 1.5 times. Since two light sources are used, it is easy to select a desired color reproduction range.

  From the above, it is only necessary to select four colors for color separation depending on whether priority is given to the amount of light or the color reproduction range. Hereinafter, a specific embodiment of the present invention will be further described with reference to FIG.

  The first light source 10 includes a lamp 10a formed of a high-pressure mercury lamp or a xenon lamp and a parabolic metal reflector 10b that converts white light emitted from the lamp 10a into a substantially parallel light flux. Since the metal reflector 10b is used as the reflector, breakage is prevented, the cooling characteristics of the reflector 10b are improved, and the time during which the lamp 10a can be lit again can be shortened. The metal reflector 10b reflects all UVIR components other than visible light forward. For this reason, although not shown in the figure, a filter, a cold mirror, and the like for removing the UVIR component are provided to emit the UVIR component to the outside of the optical path and reduce the thermal load on the subsequent optical member.

  The light emitted as parallel light by the parabolic reflector 10b is split into light beams by a so-called fly eye integrator including first and second fly eye lenses 11 and 12 composed of convex lens groups.

  The first fly-eye lens 11 is a lens in which minute lenslets having a rectangular outline are arranged in a matrix of M rows in the vertical direction and N columns in the horizontal direction. It is set so as to be almost similar to the shape of the transmissive liquid crystal panels 80a and 80b.

  The partial light beams divided by the first fly-eye lens 11 are converged by the plurality of lenses of the second fly-eye lens 12 to be incident on the polarization conversion element 13 and emitted with their polarization directions aligned. Is done.

  The polarization conversion element 13 includes a polarization beam splitter array and a λ / 2 phase difference plate that is selectively disposed on a part of the light exit surface of the polarization beam splitter array. The polarization beam splitter array has a shape in which a plurality of columnar translucent members each having a parallelogram in cross section are sequentially bonded. Polarization separation films and reflection films are alternately formed on the interface of the translucent member. The λ / 2 phase difference plate is selectively attached to the outgoing surface of the transmitted light by the polarization separation film or the reflected light by the reflective film.

  This incident light is separated into S-polarized light and P-polarized light by the polarization separation film. S-polarized light is reflected substantially perpendicularly by the polarization separation film, and is further reflected by the reflection film and emitted. On the other hand, the P-polarized light passes through the polarization separation film as it is. A λ / 2 phase difference plate is arranged on the exit surface from which the P-polarized light transmitted through the polarization separation film is emitted, and the P-polarized light transmitted through the polarization separation film is converted into S-polarized light by the λ / 2 phase difference plate. Is injected. Therefore, most of the light that has passed through the polarization conversion element 13 is emitted as S-polarized light. If the light emitted from the polarization conversion element 13 is to be P-polarized light, a λ / 2 phase difference plate may be disposed on the exit surface from which S-polarized light reflected by the reflective film is emitted.

  Then, the light whose polarization directions are aligned passes through the condenser lens 14 and the like, and is then given to the first dichroic mirror 15. In the present embodiment, the first dichroic mirror 15 having a cutoff frequency of 560 nm is used. Therefore, light in the yellow to red (R) band is reflected, and light in the green to purple band is transmitted.

  Light including red band light reflected by the dichroic mirror 15 and whose optical path is changed by 90 degrees is changed by 90 degrees by the total reflection mirror 16, and a red liquid crystal for displaying a red band light component image via the R optical path condenser lens 17a. The light enters the display element 80a and is optically modulated according to the input signal. An R filter having a cutoff frequency of 605 nm is formed on the R optical path condenser lens 17a, and a red band light component is applied to the red liquid crystal display element 80a.

  The light modulated light is incident on the dichroic prism 61. In this embodiment, the dichroic prism 61 having a cutoff frequency of 580 nm is used. For this reason, the red light incident on the dichroic prism 61 is reflected and is given to the polarization beam splitter 63 via the R-Cy color rotator 62 by changing the optical path by 90 degrees. In this embodiment, the polarization beam splitter 63 has a characteristic of transmitting P-polarized light and reflecting S-polarized light. The color rotator is a plate-like optical element that rotates only the polarization plane of incident light in a predetermined wavelength range by 90 degrees. This predetermined wavelength range can be freely set. The R-Cy color rotator 62 is a plate-like optical element that rotates only the polarization plane of a predetermined wavelength region from red to cyan by 90 degrees.

  The red light that has passed through the R-Cy color rotator 62 becomes P-polarized light, passes through the polarizing beam splitter 63, enters the projection lens 70, is enlarged and projected, and is imaged on a screen (not shown).

  On the other hand, the light in the green to purple band that has passed through the first dichroic mirror 15 enters the second dichroic mirror 18. In this embodiment, the second dichroic mirror 18 having a cutoff frequency of 470 nm is used. Therefore, cyan band light is reflected and blue band light is transmitted. Here, the cyan band light is reflected, its optical path is changed by 90 degrees, and incident on the cyan liquid crystal display element 80b for displaying the cyan band light component image via the condenser lens 17b. Light modulated. The light-modulated cyan band light enters the dichroic prism 61. Cyan band light is transmitted through the dichroic prism 61 and is applied to the polarization beam splitter 63 via the R-Cy color rotator 62. The cyan light that has passed through the R-Cy color rotator 62 becomes P-polarized light, passes through the polarization beam splitter 63, enters the projection lens 70, is enlarged and projected, and is imaged on the screen.

  The chromaticities of the two primary colors of red (R) and cyan (Cy) are R (685, 315) and Cy (201, 557). The red color (R) and cyan color (Cy) are displayed as black circles on the chromaticity diagram shown in the figure. The combined chromaticity of these two colors is (302, 522).

  Next, as with the first light source 10, the second light source 50 is a parabolic shape that makes a lamp 50a formed of a high-pressure mercury lamp or a xenon lamp and white light emitted from the lamp 50a into a substantially parallel light flux. The metal reflector 50b. Although not shown in the figure, the second light source 50 is also provided with a filter, a cold mirror, etc. for removing the UVIR component so that the UVIR component is emitted out of the optical path and the thermal load on the subsequent optical member is reduced. ing.

  Similar to the illumination system of the first light source 10, the light emitted as parallel light by the parabolic reflector 50 b is a so-called fly comprising first and second fly-eye lenses 51 and 52 composed of convex lens groups. The light is split by an eye integrator.

  The first fly-eye lens 51 is set so as to be substantially similar to the shapes of the transmissive liquid crystal panels 80c and 80d.

  The partial light beams divided by the first fly-eye lens 51 are converged by the plurality of lenses of the second fly-eye lens 52, enter the polarization conversion element 53, and exit with the polarization directions aligned. Is done.

  Then, the light whose polarization direction is aligned passes through the condenser lens 54 and the like, and is given to the third dichroic mirror 55. In this embodiment, the third dichroic mirror 55 has a cutoff frequency of 520 nm. For this reason, light in the green (G) to red (R) band is transmitted, and light in the blue to purple band is reflected.

  The light that is reflected by the dichroic mirror 55 and includes blue band light whose optical path is changed by 90 degrees is changed by 90 degrees by the total reflection mirror 56, and a blue band light component image is displayed via the B optical path condenser lens 57c. The light enters the liquid crystal display element 80c and is optically modulated according to the input signal.

  The light-modulated light enters the dichroic prism 64. In this embodiment, the dichroic prism 64 having a cutoff frequency of 500 nm is used. For this reason, the blue light incident on the dichroic prism 64 is transmitted and provided to the polarization beam splitter 63 via the B-Ye color rotator 65. The B-Ye color rotator 65 is a plate-like optical element that rotates only a polarization plane in a predetermined wavelength range from blue to yellow by 90 degrees.

  The red light that has passed through the B-Ye color rotator 65 becomes S-polarized light, is reflected by the polarization beam splitter 63, changes its optical path by 90 degrees, enters the projection lens 70, is enlarged and projected, and forms an image on a screen (not shown). Is done.

  On the other hand, light in the green (G) to red (R) band that has passed through the third dichroic mirror 55 is incident on the fourth dichroic mirror 58. In this embodiment, a fourth dichroic mirror 58 having a cutoff frequency of 585 nm is used. Therefore, the green band light is reflected and the red band light is transmitted. Here, the green band light is reflected, changes its optical path by 90 degrees, and enters the green liquid crystal display element 80d for displaying the green band light component image via the condenser lens 57d, where it is optically modulated according to the input signal. The The light-modulated green band light enters the dichroic prism 64. Green band light is reflected by the dichroic prism 64 and is applied to the polarization beam splitter 63 via the B-Ye color rotator 65. The green light that has passed through the B-Ye color rotator 65 becomes S-polarized light, is reflected by the polarization beam splitter 63, enters the projection lens 70, is enlarged and projected, and is imaged on the screen.

  Although not shown, the liquid crystal display element described above is provided with an incident side polarizing plate, a liquid crystal layer, and an outgoing side polarizing plate.

  The chromaticities of the two primary colors, green (G) and blue (B), are G (362, 621) and blue (142, 053). The green (G) and blue (B) are displayed as black circles on the chromaticity diagram shown in FIG. The combined chromaticity of these two colors is (256, 346).

  In the state of the combined chromaticity (272, 405) of the four primary colors in this embodiment, the light quantity ratio for one lamp is about 1.8 times. In a state where the y chromaticity is lowered to near 0.35, the light quantity ratio for one lamp is about 1.5 times.

  If the chromaticity for color separation is selected depending on whether priority is given to the amount of light or the color reproduction range, a projection display device suitable for the application and preference can be provided.

  In the above-described embodiment, the chromaticity of the four primary colors is calculated based on the spectrum of the high-pressure mercury lamp, but the color separation optical system of the first light source 10 and the color separation optical system of the second light source 50 are calculated. On the other hand, if a solid-state light source such as a lamp having an optimized spectral characteristic or a light-emitting diode array or a laser array is used, the green (G) and cyan (Cy) chromaticity coordinates can be set further outside, and the color reproduction range. Can be greatly expanded.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and is intended to include meanings equivalent to the scope of claims for patent and all modifications within the scope.

  The present invention can be used for projection display devices such as projectors and rear projectors.

It is a schematic diagram which shows the structure of the projection display apparatus which made the illumination optical system which concerns on 1st Embodiment of this invention the U-shaped arrangement | positioning. It is a schematic diagram of an xy chromaticity diagram (CIE chromaticity diagram). It is a schematic diagram which shows the structure of the 3LCD projection type display apparatus of the conventional dichroic prism system.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 1st light source, 11 and 12 fly eye lens, 13 deflection | deviation conversion element, 15 1st dichroic mirror, 18 2nd dichroic mirror, 50 2nd light source, 51 and 52 fly eye lens, 53 deflection | deviation conversion element, 55 Third dichroic mirror, 58 Fourth dichroic mirror, 61 First dichroic prism, 64 Second dichroic prism, 62, 65 Color rotator, 63 Deflection beep splitter, 80a, 80b, 80c, 80d Liquid crystal display element, 70 Projection lens.

Claims (5)

A first light source, a first color separation optical system that separates the white light from the first light source into two colors of a first color and a second color, and a first color separation optical system that is separated by the first color separation optical system. The first and second light modulation elements that modulate the color of the light in response to the color signal, the second light source, and the white light from the second light source is separated into two colors of the third color and the fourth color. The second color separation optical system, the third and fourth light modulation elements for modulating the respective colors separated by the second color separation optical system in accordance with the color signal, and the first to fourth A projection display device comprising: color combining means for combining modulated light modulated by the light modulating elements; and projection means for enlarging and projecting the combined light from the color combining means. The first color separation system decomposes white light into two colors of red and cyan, and the second color separation system decomposes into two colors of blue, green, and yellow. The projection display device described. 3. The projection display device according to claim 2, wherein each of the first and second color separation systems includes two dichroic mirrors having different cutoff frequencies. The color synthesizing means has a first dichroic prism having a characteristic of reflecting red band light and transmitting cyan band light, and a characteristic of reflecting green or yellow band light and transmitting blue band light. 4. The projection display device according to claim 2, comprising: two dichroic prisms; and a polarization beam splitter that receives light from the first and second dichroic prisms. 5. Between the first dichroic prism and the polarizing beam splitter, the first color rotator that is provided between the first dichroic prism and the polarizing beam splitter and rotates the polarization plane in the wavelength region from red to cyan, and the second dichroic prism and the polarizing beam splitter. The projection display device according to claim 4, further comprising: a second color rotator that rotates a polarization plane in a wavelength range from blue to yellow.

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