JP2020034805A - Projection display device - Google Patents

Abstract

To provide a projection display device capable of solving a problem that it is necessary to perform color separation for each wavelength to illuminate the display elements of each color after luminance modulation, and the optical path length is different only for certain colors resulting in a lower resolution due to the color separation.SOLUTION: The projection display device includes: a first condensing lens system for illuminating a first light modulation element from a light source; a color separation system for separating modulated light from the first light modulation element into multiple color lights; a second condensing lens system for illuminating the color-separated lights to multiple second light modulation elements; and a projection lens for combining the light from the multiple second light modulation elements and projecting it onto the illuminated surface. The projection display device has means for unifying the optical path length of each color of the first light modulation element and the second light modulation element.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a projection display device that enlarges and projects a display element image.

  2. Description of the Related Art A projection display device that enlarges and projects an image on a screen or the like due to the spread of personal computers and the expansion of video content is frequently used. Such a projection display device illuminates light emitted from a light source onto a small light modulation element such as a liquid crystal panel (LCD, LCOS) or a digital micromirror device (DMD) to display an enlarged image on a screen. It is.

  In recent years, the movement of pursuing the reality of depiction by giving display data a luminance range and the number of gradations close to human vision has become mainstream. However, there is a problem in that the display device cannot display the expression sufficiently because the performance of the display device for displaying the display is insufficient.

  In order to solve the above problems, the following proposals have been made.

Japanese Patent No. 4158775 Japanese Patent No. 4241872

  According to the technique disclosed in Patent Document 1, in the conventional technique disclosed in Patent Document 1, image light from a red image display element, a green image display element, and a blue image display element is subjected to luminance modulation. In order not to degrade the resolution performance of the image light, a high-performance relay lens is required, so that the image projection device is increased in cost and size.

  On the other hand, by illuminating the red image display element, the green image display element, and the blue image display element after performing the luminance modulation, a high contrast can be realized with a simple configuration. However, it is necessary to perform color separation for each wavelength in order to illuminate the display element of each color after performing the luminance modulation.Therefore, due to the color separation, there is a problem that the optical path length is different only for a certain color and the resolution is reduced. Was.

In order to solve the above problems, the projection display device according to the present invention is,
A first condenser lens system for illuminating a first light modulation element from a light source, a color separation system for separating modulated light from the first light modulation element into a plurality of color lights, and a second An optical display device comprising: a second condenser lens system that illuminates a light modulation element; and a projection lens that combines light from the plurality of second light modulation elements and projects the light onto a surface to be irradiated. It is characterized in that there is means for unifying the optical path length of each color between the light modulation element and the second light modulation element. Such a configuration will be described in more detail based on an embodiment of the present invention.

  ADVANTAGE OF THE INVENTION According to this invention, provision of the projection type display apparatus which can obtain a high quality image with a wide luminance dynamic range with a simple structure can be realized.

Configuration explanatory diagram of the projection type display device shown in the first embodiment of the present invention. Configuration explanatory diagram of the projection type display device shown in the first embodiment of the present invention. Diagram showing reduced resolution Configuration explanatory diagram of a projection type display device shown in a second embodiment of the present invention. Configuration explanatory diagram of a projection type display device shown in a third embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a configuration diagram showing a configuration of the first exemplary embodiment of the present invention.

  The present invention separates the light modulated by the first image display element 7 into a plurality of color lights by illuminating the first image display element 7 which illuminates the light from the light source unit 40 with a plurality of second color lights. Of the image display elements 13R, 13G, and 13B.

  The light source unit 40 has a light source 1 such as an ultra-high pressure mercury lamp or a xenon lamp, and a reflector 2 that reflects light from the light source 1. Note that an LED or a laser may be used as the light source unit 40. Further, a configuration using a laser using fluorescent light and a fluorescent material may be used.

  The light from the light source unit 40 is split and condensed by a first fly-eye lens (a lens array in which small spherical lenses are two-dimensionally arranged) 3a, which is a light equalizing element. Each of the split light beams is collected near the second fly-eye lens 3b to form an image of a light source (secondary light source image). The first fly-eye lens 3a and the second fly-eye lens 3b are means for splitting a light beam. The small lenses constituting these fly-eye lenses 3a and 3b have a rectangular lens shape similar to the light modulation element 7 which is the surface to be illuminated. Each small lens of the first fly-eye lens 3a is substantially optically conjugate with the position of the light modulation element 7. A polarization conversion element 4 is provided near the second fly-eye lens 3b where the light source image is formed.

  The plurality of light beams as non-polarized light that has entered the polarization conversion element 4 are converted by the polarization conversion element 4 into polarized light having a predetermined polarization direction (here, P-polarized light), and the first polarized beam splitter 5 is used. (P polarized light transmission, S polarized light reflection). The P-polarized light transmitted through the first polarizing beam splitter 5 is focused on the first image display element 7 via the first condenser lens 6.

  The light (S-polarized light) modulated by the first image display element 7 is reflected by the first polarizing beam splitter 5 via the first condenser lens 6 and then the first wavelength light by the dichroic filter 8. (B light) and the second wavelength light (G light + R light).

  The first wavelength light is reflected by the first mirror 9B, and is illuminated on the second image display element 13B via the second condenser lens 10B and the second polarizing beam splitter 12B. The first wavelength light (P-polarized light) modulated by the second image display element 13B passes through the second polarizing beam splitter 12B, reflects off the cross dichroic prism 20, and is projected by the projection optical system 30 into a screen (not shown). Projected onto

  The second wavelength light (G light + R light) is reflected by the second mirror 9Y, passes through the second condenser lens 10Y, and is output by the dichroic filter 11 to the third wavelength light (G light) and the fourth wavelength light (R light). Light).

  The third wavelength light (G light) is illuminated on the second image display element 13G via the second polarizing beam splitter 12G. The third wavelength light (P-polarized light) modulated by the second image display element 12G passes through the second polarizing beam splitter 12G, passes through the cross dichroic prism 20, and is projected by the projection optical system 30 into a screen (not shown). Projected to

  The fourth wavelength light (R light) is illuminated on the second image display element 13R via the second polarizing beam splitter 12R. The fourth wavelength light (P-polarized light) modulated by the second image display element 12R passes through the second polarizing beam splitter 12R, reflects off the cross dichroic prism 20, and is projected by the projection optical system 30 into a screen (not shown). Projected to

  Although the first polarization beam splitter 5 of the present embodiment is of a flat plate type, it may be of a prism type. The second polarizing beam splitters 12R, 12G, and 12B are of a prism type, but may be of a flat plate type (FIG. 2).

  The color separation / synthesis system of this embodiment is an optical system using a reflection type liquid crystal panel, but may be an optical system using a transmission type liquid crystal panel or a DMD (Digital Mirror Device).

  When the color separation unit is used, only the fourth wavelength light (R light) is transmitted through the dichroic filter 11, and the optical path length is different from the first wavelength (B light) and the third wavelength (G light). (Figure 3).

  By moving the position of the second image display element 13R corresponding to the fourth wavelength light (R light) in the optical axis direction, the light of each wavelength light of the first image display element 7 and the second image display element 13 is changed. Although it is possible to unify the optical path lengths, the back focus with respect to the projection optical system 30 differs, which does not improve the image projected on the screen.

  In this embodiment, the first image display element 7 and the second image display are arranged by arranging the means for unifying the optical path length as shown in FIG. 1 at the first wavelength (B light) and the third wavelength (G light). The optical path length of each wavelength light of the element 13 and the back focus of each wavelength light with respect to the projection optical system 30 can be unified. As a result, a high-quality image with a wide luminance dynamic range can be obtained.

  Hereinafter, a more desirable configuration will be described.

Assuming that the thickness of the dichroic filter 11 is d (mm), the refractive index is nd, the F number of the optical system is F, and the correction amount is X (mm), the correction amount X is X = (d / nd) ± 0.07. * F
It is desirable to satisfy

  As described above, the preferred embodiments of the present invention have been described, but the present invention is not limited to these embodiments, and various modifications and changes can be made within the scope of the gist.

  FIG. 4 is a diagram showing a second embodiment of the present invention.

  In this embodiment, in order to reduce the leakage light, an absorption or reflection type polarizing plate is arranged on one or both of the entrance side 60R, 60G, 60B and the exit side 61R, 61G, 61B of the second polarizing beam splitter 12. I do. In the first embodiment, the optical path length correcting means 50B and 50G are arranged at the first wavelength (B light) and the third wavelength (G light). By changing the thickness of the arranged polarizing plate 60 for each wavelength optical path, the optical path length is unified. More desirably, it is desirable to dispose an absorption type polarizing plate on the exit side of the polarizing beam splitter.

  Except for this, there is no difference from the first embodiment, and the description of the entire optical system is omitted.

  FIG. 5 is a diagram showing a third embodiment of the present invention. The arrangement of the condenser lens is different.

  In the first embodiment, the third wavelength light (G light) and the fourth wavelength light (R light) are provided with a common condenser lens 10Y, whereas in the present embodiment, the first wavelength light (B light) and the third Condenser lenses 73 are arranged for each of the wavelength light (G light) and the fourth wavelength light (R light).

  The polarized light having a predetermined polarization direction (here, P-polarized light) converted by the polarization conversion element 4 is passed through the first field lens 70, the first polarization beam splitter 5, and the first condenser lens 71. Are focused on the first image display element 7.

  The light (S-polarized light) modulated by the first image display element 7 is reflected by the first polarizing beam splitter 5 via the first condenser lens 71 and passes through the second field lens 72. The light is separated into a first wavelength light (B light) and a second wavelength light (G light + R light) by the dichroic filter 8.

  The first wavelength light is reflected by the first mirror 9B, and is illuminated on the second image display element 13B via the second condenser lens 73B and the second polarization beam splitter 12B. The first wavelength light (P-polarized light) modulated by the second image display element 13B passes through the second polarizing beam splitter 12B, reflects off the cross dichroic prism 20, and is projected by the projection optical system 30 into a screen (not shown). Projected to

  The second wavelength light (G light + R light) is reflected by the second mirror 9Y and is separated by the dichroic filter 11 into third wavelength light (G light) and fourth wavelength light (R light).

  The third wavelength light (G light) is illuminated on the second image display element 13G via the second condenser lens 73G and the second polarization beam splitter 12G. The third wavelength light (P-polarized light) modulated by the second image display element 12G passes through the second polarizing beam splitter 12G, passes through the cross dichroic prism 20, and is projected by the projection optical system 30 into a screen (not shown). Projected to

  The fourth wavelength light (R light) is illuminated on the second image display element 13R via the second condenser lens 73R and the second polarization beam splitter 12R. The fourth wavelength light (P-polarized light) modulated by the second image display element 12R passes through the second polarizing beam splitter 12R, reflects off the cross dichroic prism 20, and is projected by the projection optical system 30 into a screen (not shown). Projected to

  In the present embodiment, the optical path length is unified by changing any or all of the radius of curvature, the glass material, and the thickness of the condenser lens 73.

  The preferred embodiments of the present invention have been described above. However, it goes without saying that the present invention is not limited to these embodiments, and various modifications and changes can be made within the scope of the gist.

  For example, in this embodiment, an optical system using a reflective liquid crystal panel is used, but an optical system using a transmissive liquid crystal panel or a DMD (Digital Mirror Device) may be used.

1 light source, 2 reflector, 3a / 3b light homogenizing element, 4 polarization conversion element,
5 first polarizing beam splitter, 6/71 first condenser lens,
7 1st modulation element, 8/11 dichroic filter, 9B / 9Y mirror,
10B / 10Y second condenser lens,
73R / 73G / 73B second condenser lens,
12R / 12G / 12B second polarizing beam splitter,
13R / 13G / 13B second modulation element,
20 cross dichroic prism, 30 projection optical system, 40 light source unit,
50G / 50B optical path length correction means, 60R / 60G / 60B incident side polarizing plate,
61R / 61G / 61B output side polarizing plate, 70 first field lens,
72 Second field lens

Claims (4)

A first condenser lens system for illuminating the first light modulation element from a light source;
A color separation system for separating modulated light from the first light modulation element into a plurality of color lights;
A second condenser lens system for illuminating the color-separated light on the plurality of second light modulation elements;
A projection lens that combines light from the plurality of second light modulation elements and projects the light on a surface to be irradiated;
An optical display device comprising:
An optical display device comprising means for unifying the optical path length of each color between the first light modulation element and the second light modulation element. 2. The optical display device according to claim 1, further comprising means for correcting an optical path length difference generated by an optical element disposed in the color separation system. The optical display device according to claim 1, wherein the optical element is a dichroic filter. If the thickness of the dichroic filter is d (mm), the refractive index is nd, the F number of the optical system is F, and the correction amount is X (mm),
X = (d / nd) ± 0.07 * F
The optical display device according to claim 1, wherein the following condition is satisfied.