JP2004219787A - Projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projector in which a margin for the positional shift of an integrator is large, and a loss of light emitted from a light source is reduced. <P>SOLUTION: The projector is provided with the light source 60 including a mirror 61 of elliptic of revolution and a discharge lamp 62, a color wheel 70 on which light emitted from the light source 60 is made incident and which separates the incident light into light beams having wavelengths of R, G and B colors, the integrator 80 having an incident surface on which the R, G and B light beams separated by the color wheel 70 are made incident and which is formed in a recessed part 81 formed from the leading end and on which an antireflection film is formed, a DMD (digital mirror device) for optically modulating the light from the integrator 80, and a projecting means including an optical system for projecting the light modulated by the DMD. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a projector, and more particularly, to a DLP (Digital Light Processing) using DMD (Digital Mirror Device): DLP is a trademark of Texas Instruments.
[0002]
[Prior art]
The DLP type projector irradiates light to a DMD made of a semiconductor element, and enlarges and projects the reflected light with a lens or the like to display an image. As shown in FIG. 1 of Patent Document 1 previously filed by the present applicant, light from a light source is reflected by a spheroidal mirror 52, and the reflected light is a disk in which R, G, and B color filters are arranged. The light is sequentially converted to RGB light by a color wheel 53 having a rectangular shape, and is incident on a DMD 56. The DMD 56 is time-divisionally driven in synchronization with the RGB light based on the image data, and the reflected light is sequentially displayed on a screen 58 via a projection lens 57. Such a color image display is also called a so-called single-plate optical system because color display is performed using a single color wheel.
[0003]
[Patent Document 1]
Japanese Patent No. 3,121,843
[Problems to be solved by the invention]
However, the conventional projector has the following problems. FIG. 5A is a perspective view of a single-plate optical system, and FIG. 5B is a cross-sectional view thereof. The light source 200 includes a spheroidal mirror 201 and a discharge lamp 202 mounted on its optical axis. Light from the discharge lamp 202 is focused on the surface of the color wheel 210, where it is separated into light of each wavelength of RGB, and these lights are sequentially incident on the integrator 220.
[0005]
FIG. 6 shows a configuration example of the color wheel. The color wheel 210 has R, G, and B color filters arranged on its outer periphery, and its central portion 211 is rotated at a constant speed by a motor. It is desirable that the spot diameter 212 of the light incident on the color wheel 210 from the discharge lamp 202 be limited as small as possible. When the spot diameter 212 spans the boundaries of R, G, and B in the color wheel 210, light of pure wavelengths of RGB is not separated, and a mixed wavelength of R + G, G + B, and B + R is generated. For this reason, it is desirable to limit the spot diameter 212 as small as possible, and the color wheel 210 is arranged near the focal length of the reflector 201.
[0006]
The integrator 220 is positioned close to the color wheel 210, and receives the RGB light from the color wheel 210. The incident light undergoes total internal reflection repeatedly, and is emitted from its exit surface as light having a uniform illuminance distribution. An anti-reflection film 221 is deposited on the incident surface of the integrator 220 to suppress the incident light from being reflected by the incident surface and prevent light from being lost.
[0007]
The closer the light source is to the point light source, the better the light collection efficiency is. Therefore, the tip or the incident surface of the integrator 220 is arranged closer to the color wheel 210. For this reason, light having a very small spot diameter is irradiated to the tip or the incident surface of the integrator 220. It is desirable to focus the light source on the color wheel.However, even if the light source shifts to focus on the tip of the integrator or the incident surface, or if there is no shift in the light source, the focus is formed with a width rather than a point. As a result, light having a very small spot diameter, which is almost the same as the focal point, is applied to the tip or the incident surface of the integrator. The tip or the entrance surface of the integrator 220 is brought close to the color wheel 210. However, when light having a very small spot diameter is applied to the anti-reflection film 221 serving as the incident surface, the anti-reflection film 221 is locally heated, and the heat causes the anti-reflection film 221 to be burned out or deteriorated. There is a possibility that it will end up. If foreign matter such as dust is attached to the anti-reflection film 221, the integrator 220 may be melted and damaged by burning of the foreign matter. When the integrator 220 or the antireflection film 221 is burned or deteriorated, the loss of RGB light on the incident surface increases, and as a result, the efficiency of effectively using light from the light source decreases, and the brightness of the image projected by the projector also decreases. Resulting in.
[0008]
On the other hand, it is conceivable to separate the integrator 220 from the color wheel 210 by a certain distance or more and increase the spot diameter of the incident light on the incident surface of the integrator 220 to reduce the generation of heat. However, the optical path length increases by that much. In addition, the integrator 220 must be accurately positioned with respect to the color wheel 210 so that the spot diameter falls within the size of the incident surface. If the integrator 220 is too far away from the color wheel 210, the spot diameter of the incident light will be larger than the size of the incident surface, and a part of the light will not be incident on the integrator 220, and the light from the light source will be effective. Utilization rate decreases.
[0009]
Therefore, an object of the present invention is to solve the above-mentioned conventional problems, and to provide a projector that maintains the performance of an integrator and has low light loss.
Still another object of the present invention is to provide a projector having a large margin (permissible range) of the displacement of the integrator.
Still another object of the present invention is to provide a projector with improved effective use efficiency of light from a light source.
Still another object of the present invention is to provide a projector that can withstand use for a long time and suppresses deterioration of brightness of a projected image.
[0010]
[Means for Solving the Problems]
A projector according to the present invention includes a light source, a light transmitting member that receives light from the light source, and transmits the incident light, a modulating unit that modulates light transmitted by the light transmitting member, and a modulating unit. Projection means for projecting modulated light, wherein the light transmission member includes, at the light incident position, a surface covered with an anti-reflection film and at least one reflection surface perpendicular to the surface. It is a thing. As a result, the spot diameter of the light applied to the incident surface of the optical transmission member is increased, and the irradiation area is increased, so that the antireflection film on the incident surface is prevented from being thermally damaged (deterioration due to melting, burning, etc.). Furthermore, even if the position of the optical transmission member is slightly displaced and the spot diameter of the incident light becomes larger than the size of the incident surface, the light protruding from the incident surface is reflected by the reflecting surface and is reflected by the incident surface. , Light loss can be prevented as much as possible.
[0011]
A projector according to another aspect of the invention includes a light source, light from the light source, separation means capable of separating the light into lights having at least R, G, and B wavelengths, and R and R separated by the separation means. A light transmission member having an incident surface for receiving the G and B lights, the incident surface being formed at a position depressed from the tip, and an antireflection film formed on the incident surface; and light from the light transmission member. And a projection unit for projecting the light modulated by the modulation unit. Preferably, a reflection film is formed around the incident surface of the optical transmission member. Thus, even when the optical transmission member is displaced with respect to the color wheel, the incident light wider than the incident surface is reflected by the surrounding reflective film and guided to the incident surface. For this reason, loss of light from the light source is reduced as much as possible with respect to displacement of the optical transmission member.
[0012]
Preferably, the light transmission member is a rod-shaped integrator. Then, a cavity (recess or depression) having a certain depth is formed from the tip, and an incident surface is formed on the bottom surface of the cavity. The cavity can be formed by shaving the integrator.
[0013]
Preferably, the light transmission member is positioned within 1 mm from the color wheel, and the spot diameter of the light applied to the incident surface is 5φ or less. Preferably, the light from the light source is focused on the surface of the color wheel.
[0014]
Another projector of the present invention includes a light source, a color wheel capable of receiving light from the light source and separating the light into light having at least R, G, and B wavelengths, and a metal member (preferably a metal A light transmission member, the metal member having an inner wall surface protruding from the front end, and an antireflection film formed on a surface of the front end, and light from the light transmission member. And a projection unit for projecting light modulated by the modulation unit.
[0015]
The inner wall surface of the metal cap can be made to function as a reflection surface or a reflection film by finishing it in a mirror surface state. When it is difficult or insufficient to finish the mirror surface, a reflective film may be coated on the inner wall surface of the cap.
[0016]
The light transmission member includes a rod-shaped integrator, the metal cap is hollow, the tip of the integrator is inserted into the cap, and the cap can be configured to protrude from the tip of the integrator.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram illustrating a main configuration of a DLP projector according to an embodiment of the present invention. The projector 1 receives an image signal 11 and converts the image signal 11 into RGB digital image data having the same number of pixels as the DMD. The projector 1 controls the driving of the DMD 50 based on the digital image data from the preprocessing unit 10. A control unit 20 for controlling the lamp driving circuit 30 and the color wheel driving unit 40; The lamp driving circuit 30 controls activation of the discharge lamp of the light source 60 and AC driving of the discharge lamp after the activation. The color wheel driving unit 40 rotates the color wheel 70 to separate the light from the light source 60 into RGB. The DMD 50 includes a mirror element corresponding to each pixel, and reflects the RGB light emitted via the integrator 80 and the illumination optical system 90 by the mirror element. The projection optical system 100 enlarges and projects the reflected light from the DMD 50 to display an image on a screen.
[0018]
FIG. 2 shows an optical system from the light source to the integrator. The light source 60 includes a spheroidal mirror 61 and a discharge lamp 62 attached to its optical axis. As the discharge lamp 62, for example, a xenon arc short lamp, a metal halide lamp, an ultra-high pressure mercury lamp, or the like is used. As the spheroid mirror 61, a dichroic mirror or a cold mirror that reflects visible light from the discharge lamp 62 and transmits infrared light is used. A color wheel 70 is arranged on the focal length of the spheroid mirror 61, and light from the discharge lamp 62 is imaged on the surface of the color wheel 70.
[0019]
The color wheel 70 arranges R, G, and B color filters in a thin glass disk shape and selects the wavelength of light transmitted therethrough (the basic configuration is the same as that of FIG. 6). The color wheel 70 is rotated at a constant speed by the color wheel driving unit 40, and sequentially converts (or separates) incident light into light having R, G, and B wavelengths.
[0020]
The R, G, and B lights from the color wheel 70 enter the integrator 80. The integrator 80 is a rectangular parallelepiped rod integrator made of a heat-resistant member such as quartz or quartz glass. The integrator 80 is positioned so that light from the color wheel 70 is incident almost perpendicularly and close to the color wheel 70. Preferably, integrator 80 is arranged at a position within 1 mm from color wheel 70.
[0021]
The integrator 80 has a certain length in the axial direction, and has a rectangular entrance surface and exit surface. Light from the color wheel 70 is incident on the incident surface of the integrator -80 at a predetermined incident angle, and the incident light is internally reflected multiple times and propagated to the exit surface, from which a light beam having a uniform light intensity distribution is obtained. Is emitted. The aspect ratio (the ratio of the horizontal side to the vertical long side to the side) of the exit surface of the integrator 80 is 4: 3 or 16: 9.
[0022]
A recess or cavity 81 is formed at the tip of the integrator 70. FIG. 3 shows a cross-sectional view when the integrator is cut along the center in the axial direction. The concave portion 81 is a rectangular groove or dent, and has a depth d from the surface 82 slightly smaller than the surface 82 at the tip. The depth d is preferably d = 0.1 L, where L is the length of the integrator 80 in the axial direction. The recess 81 is defined by a bottom surface 83 parallel to the surface 82 and four inner walls 84 extending from each side (periphery) of the bottom surface 83 to the surface 82 vertically. An antireflection film (shaded portion) 85 is coated on the surface of the bottom surface 83, and a reflective film (shaded portion) 86 made of a metal such as Al is coated on the four inner walls 84. As the antireflection film 85, a known one can be used, and a multilayer antireflection film may be used.
[0023]
The bottom surface 83 of the concave portion 81 or the antireflection film 85 serves as an incident surface of the integrator 80. Since this incident surface is separated from the front surface 82 by the distance d, the spot diameter S (see FIG. 2A) of the incident light on the antireflection film 85 is larger than when the concave portion 81 is not provided. Become. In other words, the spot diameter S is wider than the diameter at the front end surface 82 by the distance d, and the irradiation area on the antireflection film 85 is increased. For this reason, local heat generation by the incident light in the antireflection film 85 is suppressed, and burnout of the antireflection film 85 or deterioration or damage of the film due to heat can be suppressed.
[0024]
As described above, the surface 82 of the integrator 80 is positioned so as to be at a fixed distance from the color wheel 70. At this time, if the integrator 80 is displaced from the color wheel 70 and separated from the color wheel 70 by a distance d1 (d1> d), the spot diameter of the incident light expands according to the distance d1 and It exceeds the area of the incident surface (anti-reflection film) 85. In this case, the light protruding from the incident surface 85 is reflected by the reflection film 86 on the inner wall 84 of the concave portion 81 and is incident on the incident surface 85. Therefore, even if the integrator 80 is slightly displaced from the large wheel 70, it is possible to prevent the effective use efficiency of the light from the light source 60 from decreasing as much as possible.
[0025]
By forming a concave portion, a cavity, or a dent at the tip of the integrator 80 in this manner, even when the integrator 80 is displaced with respect to the color wheel 70, light from the color wheel 70 is efficiently incident on the integrator 80. At the same time, damage and deterioration of the integrator 80 due to heat can be suppressed, and the life of the integrator 80 can be extended while maintaining the performance of the integrator 80.
[0026]
Next, a second embodiment of the present invention will be described. FIG. 4 is a diagram showing an optical system similar to FIG. 3, and the same parts as those in FIG. 3 are denoted by the same reference numerals. The integrator 110 according to the present embodiment is obtained by attaching a metal cap 112 to the tip 111 of a rod-shaped integrator having a rectangular cross section as shown in FIG. The front surface 111 of the integrator 110 is coated with an anti-reflection film. The metal cap 112 is a hollow cylindrical rectangular parallelepiped, and is preferably formed of Al or stainless steel. The inner diameter of the cap 112 is slightly larger than the outer dimensions of the integrator 110, and the tip 111 of the integrator 110 is inserted into the cap 112. By improving the dimensional accuracy of the cap 112, the tip 111 of the integrator 110 can be held in a fitted state. Alternatively, a buffer may be inserted between the integrator 110 to more reliably hold the integrator 110.
[0027]
The tip of the cap 112 projects from the tip 111 of the integrator 110 by a distance d. In other words, the tip 111 of the integrator 110 is inserted into the cap 112 until the inner wall 113 of the cap 112 remains at the distance d. By doing so, the integrator 110 has a depression or a depression equivalent to the depression or the depression in the first embodiment. The shape of the recess is defined by the inner wall 113 of the cap 112. By processing the exposed inner wall 113 of the cap 112, that is, the inner wall 113 corresponding to the distance d to a mirror surface state, the inner wall 113 can be used as a reflecting mirror. Alternatively, a reflective film may be coated on the inner wall 113. The integrator 110 according to the second embodiment has basically the same operation and effect as the integrator 80 according to the first embodiment.
[0028]
In the case of the integrator 110 according to the second embodiment, an integrator that is resistant to displacement and that suppresses deterioration and damage of the antireflection film can be formed only by attaching a cap to a conventional integrator, which is very useful. . Although the cap is made of a metal member, other members may be used to form a reflective film on the inner wall by vapor deposition or other means.
[0029]
In the above embodiment, a rectangular concave portion is formed at the tip of the integrator, but the shape is not necessarily limited to such a shape. For example, the shape of the concave portion may be a circular concave portion depending on the spot diameter from the color wheel, or may be another shape. Further, the shape of the dent or recess defined by the inner wall 113 of the cap 112 attached to the integrator 110 is not limited to a rectangular shape. Further, the integrator has a rectangular cross section as an example, but may have a circular or elliptical cross section.
[0030]
The above embodiment has been described by taking the DLP type projector as an example. However, it is needless to say that the present invention can be widely applied to projectors using other liquid crystal devices, rear projection type projectors, and the like.
[0031]
As described above, the preferred embodiments of the present invention have been described in detail. However, the present invention is not limited to the specific embodiments, and various modifications may be made within the scope of the present invention described in the appended claims. Deformation and modification are possible.
[0032]
【The invention's effect】
According to the present invention, since the concave portion is provided at the tip of the optical transmission member including the integrator and the antireflection film is formed in the concave portion, even when the optical transmission member is displaced, the heat of the optical transmission member can be reduced. It is possible to prevent the damage and deterioration due to the above as much as possible, and to extend the service life while maintaining its performance.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration of a projector used in the present invention.
FIG. 2 shows an optical system of the projector according to the first embodiment, FIG. 2 (a) is a perspective view thereof, and FIG. 2 (b) is a sectional view.
FIG. 3 is a cross-sectional view of the integrator shown in FIG. 2 taken along an axial center.
FIG. 4 shows an optical system of a projector according to a second embodiment, FIG. 4 (a) is a perspective view thereof, and FIG. 4 (b) is a cross-sectional view.
5A and 5B show an optical system of a conventional projector, FIG. 5A is a perspective view thereof, and FIG. 5B is a sectional view thereof.
FIG. 6 is a plan view illustrating a configuration example of a color wheel.
[Explanation of symbols]
10: pre-processing unit, 20: control unit,
30: lamp drive circuit, 40: color wheel drive unit,
50: DMD, 60: light source lamp,
70: color wheel, 80: integrator,
81: concave portion (dent), 82: tip surface,
83: bottom surface, 84: inner wall,
85: anti-reflection film, 86: reflection film

Claims (14)

A light source,
An optical transmission member that receives light from a light source and transmits the received light,
A modulating means for modulating the light transmitted by the light transmitting member,
And projection means for projecting light modulated by the modulation means,
The projector, wherein the light transmission member includes, at a light incident position, a surface covered with an anti-reflection film, and at least one reflection surface perpendicular to the surface. The projector according to claim 1, wherein the antireflection film of the light transmission member includes a rectangular plane, and the reflection surface extends in a vertical direction from each side of the section plane. The projector according to claim 1, wherein the reflection surface is a metal surface. A light source,
Separating means for receiving light from a light source and separating the light into lights having at least R, G, and B wavelengths,
An optical transmission member having an incident surface on which the R, G, and B lights separated by the separating means are incident, the incident surface being formed at a position depressed from the tip, and an antireflection film being formed on the incident surface When,
Modulating means for modulating light from the optical transmission member,
Projection means for projecting light modulated by the modulation means,
Projector equipped with. The projector according to claim 4, wherein a reflection film is formed around the light incident surface of the light transmission member. The projector according to claim 4, wherein the light transmission member is an integrator, a cavity having a predetermined depth is formed from a tip of the integrator, and an incident surface is formed on a bottom surface of the cavity. The optical transmission member is an integrator, a concave portion is formed at a tip thereof, an antireflection film is formed on at least a bottom surface of the concave portion, and a reflection film is formed on a surface adjacent to a bottom surface of the concave portion. A projector according to claim 1. 8. The projector according to claim 4, wherein the light transmission member is positioned within 1 mm from the separation unit, and a spot diameter of light applied to the incident surface is 5φ or less. 9. The projector according to claim 8, wherein the separation unit includes a color wheel, and light from the light source is point-focused on a surface of the color wheel. A light source,
Separating means for receiving light from a light source and separating the light into lights having at least R, G, and B wavelengths,
An optical transmission having a metal member at an axial end, wherein the metal member protrudes from the end, a reflection surface is formed on an inner wall of the protruding portion, and an anti-reflection film is formed on the surface of the end Components,
Modulating means for modulating light from the optical transmission member,
Projection means for projecting light modulated by the modulation means,
Projector equipped with. The projector according to claim 10, wherein an inner wall surface of the metal member functions as a reflection surface. The projector according to claim 11, wherein a reflective film is coated on an inner wall surface of the metal member. The light transmission member includes an integrator having a rectangular cross section, the metal member is a hollow cap, and the tip of the integrator is inserted into the cap so that the cap projects from the tip of the integrator. Item 13. The projector according to any one of Items 10 to 12. 14. The projector according to claim 1, wherein the light source includes a discharge lamp and a reflector that reflects light from the discharge lamp, and the modulation unit includes a semiconductor mirror element.

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