JPH03149541A - Projector for video color image - Google Patents

Abstract

PURPOSE: To simplify constitution and to reduce the loss of light in the entire optical path by making mutually tilted three mirror surfaces cross at an intersection, dividing the pupil of a projection objective lens into the three segments of an almost equal area and passing through only one of three partial light fluxes to the respective segments. CONSTITUTION: The optical axes of the three partial light fluxes 14R, 14G and 14B are mutually tilted so as to be crossed at one common intersection 16. The three mirror surface 17, 17' and 17" are crossed at the intersection 16 and they are mutually tilted so as to turn the three partial light fluxes 14R, 14G and 14B to a common direction matched with the optical axis of the projection objective lens 18. The formation of the three partial light fluxes 14R, 14G and 14B corresponds to a normal projection light beam route and a light source is image formed in the pupil 19 of the projection objective lens 18 by an illumination system present near liquid crystal light valves 15R, 15G and 15B. Thus, light beams are geometrically gathered, the constitution is simplified and the loss of the light is reduced.

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention is a device for projecting a video color image using three partial light streams of different colors controlled by a liquid crystal light valve, the invention comprising: The axes intersect at one common light point, additively superimposing the three partial light streams into one
The present invention relates to a device as described above, in which the three partial light streams are diverted to a projection objective for obtaining two color images.

[Conventional technology and problems]

A device of this kind is known from EP-A-0266184. In this device, white light emitted from one light source is split into three color partial light streams by a dichroic mirror. The first dichroic mirror reflects only blue light, the second dichroic mirror reflects green light, and the third dichroic mirror only reflects red light. Each reflected color partial light stream then passes through a liquid crystal light valve, producing an image of its respective color. These images are integrated by a dichroic prism. The dichroic prism is composed of four square prisms, each prism having a dichroic mirror surface including a right angle. The thus combined image is projected onto a screen by a projection objective. Although this known device has a compact design, the required dichroic mirror is difficult to manufacture. Also. Image disturbances may occur in the center of the image field. From DE 37 20 375 A1, an electro-optical projection device is known which has a light source and a device for producing a white parallel beam of light. The white collimated beam is deflected by a deflecting mirror and acts on the light valve unit. The light valve unit shapes the color distribution and intensity distribution of the white light beam according to the image to be projected, and the objective lens produces a projected image on the screen. The light valve unit has a polarizing beam splitter, the top surface of which is used as the input part for the white collimated light beam, and the side surface facing the objective lens as the exit part - this polarizing beam splitter is made of high refractive glass. It happens. It is a Mac Neill prism that splits an unpolarized incident beam into two beams of opposite polarization. The polarizing beam splitter is equipped with two color splitters, in which the two light beams are separated into colors, and reflected by six reflective liquid crystal light valves provided on different end faces of the two color splitters. be done. With this known projection device, it is possible to obtain a color projected image by superimposing six extracted images on a polarizing beam splitter, but the disadvantage is that the optical configuration is extremely complicated and light loss is large. [The problem that the invention attempts to solve! ! ] An object of the present invention is to configure the video color image projector mentioned at the beginning to have a simple configuration and to reduce light loss along the entire optical path. [Means for Solving the Problems] In order to solve the above problems, the present invention is an apparatus for projecting a video color image using three partial light streams of different colors controlled by a liquid crystal light valve. , the optical axes of the three partial light streams intersect at one common light point, and the three partial light streams are directed to a projection objective for additively superimposing the three partial light streams to obtain one color image. In the above device, the three mutually inclined mirror surfaces intersect at the intersection point, and the pupil of the projection objective is divided into three segments of approximately equal area;
It is characterized in that only one of the two partial light streams passes through each segment. Effects of the Invention By arranging three mirror surfaces that reflect almost 100% at the intersections of the three partial light streams, the light rays can be collected geometrically rather than physically. In this way, the configuration can be simplified and light loss can be reduced. [Example] Next, an example of the present invention will be described using the accompanying drawings. The device illustrated in FIG. 1 includes a reflector 11, 1.1. A light source 10 with a condenser lens 13 is provided at the light source 10, and a red filter 12m is provided with a condenser lens 13 at the light source 10
1, and a blue filter 12. with a condenser lens 13" is attached to the light source 10 degrees. In this way, the basic colors red,
Three partial light streams, green and blue14. , 14G, 14. is formed. The three partial light streams 14*, 14G, 14a pass through liquid crystal light valves 15□ 15G, 15m, respectively. LCD light valve 15
□ 15°, 15. 14. Partial light flow as a so-called active-free CD matrix. ,14. . 14° is controlled in a pixel manner (yixelweise),
Regarding its composition and operation, for example, see West German Patent Publication No. 3.
It is explained in the publication No. 130407. Three partial light streams14. , 14°, 14. are mutually inclined such that their leading axes intersect at one common intersection point 16. This intersection 1
6 with three mirror surfaces 17.17bu. 1b' intersect. Three mirror surfaces 17.17. 17'° indicates the three partial light streams 14. ,14. . 14, are mutually tilted such that they are deflected in a common direction coinciding with the optical axis of the projection objective 18. The formation of the three partial light streams 14m-14G, 14m corresponds to the normal projection ray path, ie close to the pattern. In this example, the liquid crystal light valve is 15□, 15°. 15, such that the light source is imaged into the pupil 19 of the projection objective 18 by means of an illumination system near the pupil 19 of the projection objective 18. Filament 20.20 for each light source to, to, to'',
20" is not located exactly on the optical axis, but is slightly offset to the side. In this way, the three approximately equal area segments 21.21 of the pupil 19 of the projection objective 18 ', 21'', respectively, produce light source images colored in one of the basic colors. FIG. 2 shows a pupil 19 divided into three triangular segments 21, 21, 21°'', three light sources 10, 10°, 1
Colored partial light flow from 0” 14□ 14G, 14*
are superimposed by the projection objective 18 onto a projection screen (not shown) to form a colored image. In the illustrated example, the three mirror surfaces 17, 17, 17'' are formed flat like a corner reflector, but they may also be formed spherically or toroidally to improve imaging efficiency.Projection objective In order to avoid interference with imaging due to the pupil 19 of the lens 18 being only partially utilized, the mirror surface 1B, 1B° is placed just in front of the rear lens of the projection objective 18. In order to avoid vignetting in this case, the projection objective 18 must have a relatively large free lens diameter. Also according to an embodiment not shown in the drawings, the mirror surface can be used to save space. For this purpose, lenses are provided in the three ducts through which the light passes before the partial light stream impinges on the mirror surface.
Focusing must be performed by displacing the individual lenses behind a mirror surface. Also within the scope of the invention, although not shown in the drawings,
A corner reflector may be provided in which the three segments are shaped like strips, in which case the three light source images occur laterally offset in only one direction, for example overlapping. In this case, the common intersection of the optical axes where the mirror surfaces collide is a virtual intersection. This embodiment is advantageous when using light sources with long filaments. Next, embodiments of the present invention will be listed. (1) Three partial light streams (14*e 140514m>
A light source (10,1
0,10"). Spectral selection filter (12m, 120e1
21) condenser lens (13°13, 1
2. The device according to claim 1, characterized in that: (2) the mirror surface (17, 17', 179°) is arranged immediately in front of the rear lens of the projection objective (18); 1. The device according to claim 1, characterized in that: (3) the mirror surface (17, 17, 17'')' is - the projection lens (
18) The apparatus according to claim 1, characterized in that the mirror surface (17, 1, 17") is arranged in a flat structure. Item 1゜ Item 2 or 3 above
Equipment described in Section. -5) The device according to claim 1, the second or third item, characterized in that the mirror surface (17, 17', 1°) has a spherical or annular shape. The device according to claim 1, characterized in that (6) Sebumen) (21, 21, 21'') are configured in a triangle. (7) Sebumen) (21, 21', 21'',) 1. The device according to claim 1, characterized in that it is constructed in the form of a strip. (8) The three mirror surfaces (I7.1, 17") form one corner reflector. The device according to claim 1, wherein:

[Brief explanation of the drawing]

FIG. 1 shows a perspective view of the device according to the invention, and FIG. 2 shows a segmented pupil of the projection objective. 10.10,10°9...Light source 14□ 14□ 14. ...Partial light flow 16...
... Intersection 17.17.17''' ... Mirror surface 18 ... Projection objective lens 19 ... Pupil

Claims (1)

[Claims] (1) A device for projecting a video color image using three partial light streams of different colors controlled by a liquid crystal light valve, the optical axes of the three partial light streams forming a common light point. In the device, the three partial light streams are diverted to a projection objective for additively superimposing the three partial light streams to obtain one color image, at the intersection point (16), Three mirror surfaces (17
, 17', 17'') intersect, and the pupil (19) of the projection objective (18) is divided into three segments (21, 21', 21'') with approximately equal areas; Partial light flow (14_R, 14_G, 14
__B) is included in each segment (21, 21', 21
″); and a device characterized by: