JP2010186091A - Projection type display device - Google Patents

Abstract

An object of the present invention is to provide a projection display device that is improved in size and excellent in contrast performance in a multiple light modulation system in which light modulation elements are arranged in multiple.
A green optical path is an optical path having a relay lens that is longer than the optical paths of other color lights, and a second light modulation element is disposed in the green optical path. Using the configuration as described above, a multiple projection method is realized without the need for two relay lenses, an illumination system relay lens and an imaging system relay lens. To provide.
[Selection] Figure 1

Description

  The present invention relates to a technique for providing a projection display device that projects an image on an image surface such as a screen using an image display element such as a liquid crystal.

  In a projection display apparatus, a technique for improving contrast performance by performing multiple modulation with a light modulation element is known. For example, Patent Document 1 discloses the technique.

JP 2006-126261 A

  Japanese Patent Application Laid-Open No. 2004-228561 has a configuration in which color light that has been light-modulated by a first light modulation element corresponding to each color light is color-synthesized by a color synthesis optical system and then light-modulated again by another second light modulation element. That is, the contrast performance is improved by multiplexly modulating each color light with two light modulation elements.

  For the first color light, the first light modulation element performs light modulation peculiar to each color light, and the second light modulation element common to each subsequent color light performs light modulation of the entire image.

  Assuming that the contrast performance of the first light modulation element is 200 and the contrast performance of the second light modulation element is 200, by performing multiple light modulation with the first light modulation element and the second light modulation element, 200 × 200 = A contrast performance of 40,000 is expected.

  As the name implies, the multiplex optical modulation method is a method in which light once optically modulated is optically modulated again. FIG. 7 is a configuration diagram of the multiplex optical modulation method disclosed in Patent Document 1.

  In FIG. 7, the light beam emitted from the lamp 101 a constituting the light source unit 101 is reflected by the reflector 101 b and becomes a light beam deflected in a direction parallel to the optical axis 110. The light beam emitted from the light source unit 101 is divided into partial light beams by the first multi-lens 103a and the second multi-lens 103b that constitute an integrator having a function of uniformizing the light amount distribution. Are superimposed and irradiated on the first light modulation elements 3R, 3G, and 3B. A polarization conversion element 104 is disposed between the second multi-lens 103b and the focusing lens 105, and natural light from the lamp 101a is converted into linearly polarized light having a uniform vibration direction.

  White light is separated into red, green, and blue by dichroic mirrors 107a and 107c having predetermined half-value wavelengths, respectively, between the focusing lens 105 and the first light modulation elements 3R, 3G, and 3B. Specifically, a dichroic mirror 107a having a half-value wavelength (a wavelength at which the transmittance / reflectance is 50%) between the red and green bands transmits the red band light flux, and the green band light flux. Reflects the luminous flux in the blue band. The light beam in the red band is deflected by the optical path bending mirror 106b and applied to the first light modulation element 3R corresponding to red.

  Next, the dichroic mirror 107c having a half-value wavelength between the green and blue bands transmits the light beam in the blue band and reflects the light beam in the green band. The light beam in the green band is directly applied to the first light modulation element 3G corresponding to green. Finally, the light beam in the blue band is irradiated to the first light modulation element 3B corresponding to blue by the illumination relay lenses 109a and 109b and the deflection mirrors 106c and 106d. The respective color lights light-modulated by the first light modulation elements 3R, 3G, and 3B are color-combined by the cross prism 2, and then are again applied to the second light modulation element 6 to be modulated by the imaging relay lens 7. Irradiated. The modulated light modulated again by the second light modulation element 6 is projected onto the image plane by the projection lens 1.

  As described above, in the multiplex light modulation method of FIG. 7, after the color light respectively modulated by the first light modulation element corresponding to each color light is color-synthesized by the cross prism 2 as a color synthesis optical system, Light modulation is performed again with the two light modulation elements. Therefore, the imaging system relay lens 7 is required as a mapping optical system that forms a mapping relationship on the subsequent second light modulation element using the first first light modulation element as an object.

  That is, it is understood that the number of lenses as the imaging system relay lens 7 and the space thereof are required, and the size and size of the imaging system relay lens 7 are increased accordingly.

  In view of the above circumstances, an object of the present invention is to provide a projection display device that is improved in size in a multiple light modulation system in which light modulation elements are arranged in multiple.

  To achieve the above object, the present invention includes a light source unit, a color separation optical system that separates white light emitted from the light source into first color light, second color light, and third color light, and each color separated color From the light source unit to the first light modulation element, three first light modulation elements that respectively modulate light, a color synthesis optical system that synthesizes each modulated color light, a projection lens that projects the synthesized color light In the projection display device having the optical path of the first color light and the second color light having substantially the same optical path length and the optical path of the third color light having a relay lens and longer than the optical path lengths of the other color lights, A second light modulation element as a contrast adjustment element is disposed.

  The optical path length of the third color light from the light source unit to the first light modulation element is substantially equal to the optical path length of the other first color and second color light, or the optical path length from the light source unit to the second light modulation element is The optical path lengths of the first and second color lights from the light source to the first light modulation element are made substantially equal to each other.

  Furthermore, the third color light is green.

  With the above configuration, two relay lenses, the illumination system relay lens 109 and the imaging system relay lens 7 in the conventional multiple light modulation method (FIG. 8) in which the optical paths of the respective color lights are arranged in a straight line, are combined into one. Since it can be realized with a relay lens, it is possible to provide a compact projection display device which has excellent contrast performance.

  According to the present invention, a multiple light system can be realized without the need for two relay lenses of an illumination system relay lens and an imaging system relay lens, so that a compact projection display device having excellent contrast performance is provided. It will be possible.

  Embodiments of the present invention will be described below with reference to the drawings.

  First, an embodiment of the present invention will be described with respect to a projection display device in which a second light modulation element as a contrast adjustment element of the present invention is arranged. Next, the contrast performance of the projection display device as an effect of the second light modulation element will be described.

  A first embodiment will be described with reference to FIGS. 1 to 3.

  In FIG. 1, the light beam emitted from the lamp 101a constituting the light source unit 101 is reflected by the reflector 101b. Since the reflecting surface of the reflector 101b has an elliptical shape, a concave lens 102 is arranged to make the light beam parallel to the optical axis 110.

  The light beam emitted from the concave lens 102 is divided into partial light beams by the first multi-lens 103a and the second multi-lens 103b constituting an integrator having a function of uniformizing the light amount distribution, and the first light modulation element is formed by the focusing lens 105. Irradiation is superimposed on 3R, 3G, and 3B. A polarization conversion element 104 is disposed between the second multi-lens 103b and the focusing lens 105, and natural light from the lamp 101a is converted into linearly polarized light having a uniform vibration direction.

  The white light is separated into red, green, and blue by dichroic mirrors 107a and 107b having predetermined half-value wavelengths, respectively, between the focusing lens 105 and the first light modulation elements 3R, 3G, and 3B. Yes. Specifically, a dichroic mirror 107a having a half-value wavelength (a wavelength at which the transmittance / reflectance is 50%) between the red and green bands transmits the red band light flux, and the green band light flux. Reflects the luminous flux in the blue band. The light beam in the red band is deflected by the optical path bending mirror 106b and applied to the first light modulation element 3R corresponding to red.

  Next, the dichroic mirror 107b having a half-value wavelength between green and blue transmits the light beam in the green band and reflects the light beam in the blue band. The light beam in the blue band is irradiated as it is to the first light modulation element 3B corresponding to blue. Finally, the luminous flux in the green band is optically modulated by the first light modulation element 3G corresponding to green, and then the second light corresponding to green is formed by the imaging system relay lenses 5a and 5b and the deflection mirrors 106c and 106d. The light modulation element 4 is irradiated. The respective color lights after being light-modulated by the first light modulation elements 3R and 3B and the second light modulation element 4 are color-synthesized by the cross prism 2 and projected onto the image plane by the projection lens 1.

  FIG. 2 is an explanatory diagram in which two types of optical paths having different optical path lengths for each color light are arranged in a straight line. The green light path as the third color light also has the same optically arranged position as the first light modulation elements 3R and 3B respectively disposed in the red and blue light paths as the first color light and the second color light. One light modulation element 3G is arranged.

  In the green optical path, an imaging relay lens 5 that forms an image when the first light modulation element 3G is used as an object, and a second light modulation element 4 as a contrast adjustment element are arranged at the image position. Yes. The respective color lights emitted from the first light modulation elements 3R and 3B and the second light modulation element 4 are color-synthesized by the cross prism 2 as a color synthesis optical system and projected onto the image plane by the projection lens 1.

  The reason why the second light modulation element 4 as the contrast adjustment element is arranged in the green light path will be described with reference to FIG.

  FIG. 3 shows the result of calculating red, green, blue and white in the XYZ color system defined based on the principle of additive color mixing of the three primary colors. The XYZ display system is obtained by multiplying the red, green, and blue energy amounts obtained by transmitting / reflecting the light emitted from the light source by the wavelength sensitivity characteristics of the human eye with respect to red, green, and blue. “Tristimulus value XYZ”. The xy chromaticity value is a relative value and is defined by x = X / (X + Y + Z) and y = Y / (X + Y + Z).

  By the way, the contrast performance is defined by the ratio of the Y value (corresponding to the luminous flux) in white display and the Y value in black display in the light modulation by the light modulation element. The contrast performance is influenced by the transmittance and reflectance values of the optical elements arranged in the optical paths of the respective colors, but basically the contrast performance of the light modulation element with respect to the respective color lights is dominant.

  Therefore, in the description of assigning the green light to the third color light, it is assumed that the contrast performance for the respective color lights of the first light modulation elements 3R, 3G, and 3B is the same.

  The projection display device shown in FIG. 3A has a red color with X = 111.3, Y = 58.5, Z = 0.1, X = 87.8, Y = 200.2, and Z = 3.1. And green of X = 92.3, Y = 43.3, and Z = 523.7. White is obtained by adding three colors of red, green and blue. By adding 58.5 lumens of red, 200.2 lumens of green and 43.3 lumens of blue, the amount of luminous flux for white display is 301.9 lumens.

  Here, the contrast performance 200: 1 is applied, and the red 0.29 lumen, the green 1.00 lumen, and the blue 0.22 lumen, which are reduced to 1/200, are added to obtain a luminous flux amount 1.51 lumen in black display. Is obtained.

  The ratio of the green luminous flux is large because of the visual sensitivity of the human eye. In FIG. 3A, the ratio of the green luminous flux to the white luminous flux is as large as about 66%. Yes.

  Therefore, in the case of black display, if the amount of green luminous flux can be reduced, it can be expected that white contrast performance can be improved even if the amount of red / green luminous flux remains constant.

  Therefore, the contrast performance in the case where the second light modulation element 4 as the contrast adjustment element is arranged in the green light path will be described with reference to FIG.

  The extinction ratio of the first light modulation element 3 is 200, and the extinction ratio of the second light modulation element 4 is 2. Since two extinction ratios are applied to the green light beam, the amount of green light beam in black display is 1/400 (= 200 × 2), which is 0.50 lumen. Therefore, the entire black display is 1.01 lumen, and the contrast performance 299 (= 301.9 / 1.01) is obtained.

  For comparison, the contrast performance when the second light modulation element 4 is arranged in the red light path is 221 and the contrast performance when the second light modulation element 4 is arranged in the blue light path is 215, and the green light path It can be seen that the arrangement of the second light modulation element 4 is effective in improving the contrast performance.

  Although the white contrast performance can be further improved by increasing the extinction ratio of the second light modulation element 4, black display is performed when the contrast performance of the projection display device to which the present invention is applied is not so large. In this case, the color looks like a magenta color with a reduced green color, that is, a green complementary color.

  Next, Example 2 will be described with reference to FIGS.

  FIG. 4 is a configuration diagram of the optical system of the projection display apparatus according to the second embodiment of the present invention, and FIG. 5 is an explanatory diagram regarding the optical path length of each color of the projection display apparatus according to the second embodiment of the present invention. As can be seen in FIGS. 4 and 5, the configuration in which the positions of the green first light modulation element 3 </ b> G and the second light modulation element 4 as a contrast adjustment element in the first embodiment are switched is the structure of the second embodiment. It is. 4 and 5, an imaging relay lens 5 that satisfies the mapping relationship is disposed between the green first light modulation element 3 </ b> G and the second light modulation element 4.

  FIG. 6 is an explanatory diagram of the effect of improving the contrast performance in the second embodiment. In this case, the contrast performance of 400: 1 is obtained by adding red 0.15 lumen, green 0.50 lumen, and blue 0.11 lumen, which are reduced to 1/400, to obtain a light flux amount of 0.75 lumen in black display. .

  Similarly, the contrast performance in the case where the second light modulation element 4 as a contrast adjustment element is disposed in the green light path will be described with reference to FIG.

  The extinction ratio of the first light modulation element 3 is 400, and the extinction ratio of the second light modulation element 4 is 4. Since two extinction ratios are applied to the green light beam, the amount of green light beam in black display is 1/1600 (= 400 × 4), which is 0.13 lumen. Accordingly, the entire black display is 0.38 lumen, and a contrast performance of 796 (= 301.9 / 0.38) is obtained.

  For comparison, the contrast performance when the second light modulation element 4 is arranged in the red light path is 468, and the contrast performance when the second light modulation element 4 is arranged in the blue light path is 448, and the green light path It can be seen that the arrangement of the second light modulation element 4 is effective in improving the contrast performance.

  In Example 2, since the extinction ratio in the first light modulation element 3 is good, that is, the contrast performance is large, the amount of light beam in black display is smaller than that in Example 1, and thus the extinction of the second light modulation element 4 is performed. Increasing the ratio to 4 does not stand out.

  As described above, the second light modulation element as the contrast adjustment element is arranged in the green light path, the multiple color modulation is performed on the green color light together with the first light modulation element, and the conventional illumination optical system is used. By using the arranged illumination relay lens as the imaging relay lens, it is possible to provide a projection display device that improves contrast performance while preventing an increase in the size of the projection display device.

  Here, a comparison with a mechanical aperture method for reducing the amount of luminous flux in black display and improving contrast performance is performed. The mechanical aperture method is a method of reducing the amount of light beam applied to the first light modulation element 3 with a newly arranged mechanical aperture. In this method, the light beam for each region (pixel) of the first light modulation element 3 is used. The amount cannot be adjusted. In other words, the mechanical aperture method is effective when the entire image surface is substantially uniformly dark. However, when there are dark regions (pixels) and bright regions (pixels) in the image surface, the effect is obtained. Can not demonstrate.

  On the other hand, the multiple light modulation method of the present invention is a method capable of improving contrast performance even when a dark region (pixel) and a bright region (pixel) exist in the image plane.

It is a block diagram of the optical system of Example 1 of this invention. It is explanatory drawing regarding the optical path of each color of Example 1 of this invention. It is a figure which shows the relationship between the extinction ratio of the contrast adjustment element of Example 1 of this invention, and contrast performance. It is a block diagram of the optical system of Example 2 of this invention. It is explanatory drawing regarding the optical path of each color of Example 2 of this invention. It is a figure which shows the relationship between the extinction ratio of the contrast adjustment element of Example 2 of this invention, and contrast performance. It is a block diagram of the prior art example of a multiplex light modulation system. It is explanatory drawing of a multiple | multiplex optical modulation system.

DESCRIPTION OF SYMBOLS 1 ... Projection lens, 2 ... Cross prism, 3 ... 1st light modulation element, 4 ... 2nd light modulation element, 5 ... Imaging system relay lens, 6 ... 2nd light modulation element, 7 ... Imaging system relay lens, DESCRIPTION OF SYMBOLS 101 ... Light source part, 102 ... Concave lens, 103 ... Multi lens, 104 ... Polarization conversion element, 105 ... Focusing lens, 106 ... Optical path bending mirror, 107 ... Dichroic mirror, 108 ... Condenser lens, 109 ... Illumination system relay lens

Claims (5)

A light source unit;
A color separation optical system that separates white light emitted from the light source unit into first color light, second color light, and third color light;
Three first light modulation elements which are light modulation elements that light-modulate each color light color-separated by the color separation optical system;
A color synthesis optical system that synthesizes each color light modulated by the first light modulation element, and a projection lens that projects the color light synthesized by the color synthesis optical system;
Have
A projection display in which the optical path length of the third color light having a relay lens in the optical path between the light source unit and the first light modulation element is longer than the optical path length of the other first color light or the second color light. In the device
A projection display device, wherein a second light modulation element, which is a light modulation element for optically modulating the third color light, is disposed in an optical path of the third color light. A light source unit;
A color separation optical system that separates white light emitted from the light source unit into first color light, second color light, and third color light;
Three first light modulation elements which are light modulation elements that light-modulate each color light color-separated by the color separation optical system;
A color synthesizing optical system for synthesizing each color light modulated by the first light modulation element;
A projection lens that projects the color light synthesized by the color synthesis optical system;
In the projection display apparatus, the length of the optical path between the light source unit and the first light modulation element is substantially equal to the first color light, the second color light, or the third color light.
Projection characterized in that a second light modulation element, which is a light modulation element for light modulating the third color light, is arranged between the first light modulation element in the optical path of the third color light and the color synthesis optical system. Type display device. The projection display device according to claim 1,
A projection display apparatus, wherein a length of an optical path between the light source unit of the third color light and the second light modulation element is substantially equal to a length of the optical path of the first color light or the second color light. The projection display device according to any one of claims 1 to 3,
A projection display device, wherein a relay lens is provided between the first light modulation element and the second light modulation element of the third color light. 5. The projection display device according to claim 1, wherein the third color light is green. 6.

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