KR19990034630A - Projection type image display device - Google Patents

Abstract

Disclosed is a projection image display apparatus including a single-plate AMA module capable of displaying a color image using a color wheel. The apparatus comprises a light source for generating a light beam, a plurality of mirrors on which the light beam is illuminated, each mirror modified to correspond to the intensity of a corresponding one of the plurality of pixels displayed on the screen. An AMA module having an opening, the projection stop of which the flux of the light rays passing through the opening controls the intensity of the light reflected from each mirror of the AMA module, the light beam passing through the projection stop in red, green or blue color rays And a projection lens for projecting the color light beams passing through the color wheel onto the screen. Since the space for installing the color wheel can be easily secured and the size of the color wheel can be reduced in response to the size of the projection stop, the optical system can be compactly configured.

Description

Projection type image display device

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection image display device and a projection method using the same, and particularly, to a projection image display device including a single-plate Actuated Mirror Array (AMA) module, which displays a color image using a color wheel. The present invention relates to a projection type image display apparatus.

In general, a spatial light modulator, which is an apparatus for projecting optical energy onto a screen, may be applied to various fields such as optical communication, image processing, and information display apparatus. Typically, such devices are classified into a direct-view image display device and a projection-type image display device according to a method of displaying optical energy on a screen.

An example of a direct-view image display device is a CRT (Cathode Ray Tube). The CRT device is called a CRT, which has excellent image quality but increases in weight and volume as the screen is enlarged, leading to an increase in manufacturing cost. There is.

Examples of the projection image display apparatus include a liquid crystal display (LCD), a deformable mirror device (DMD), and an AMA. Such projection image display devices can be further divided into two groups according to their optical characteristics. That is, devices such as LCDs can be classified as transmissive spatial light modulators, while DMD and AMA can be classified as reflective spatial light modulators.

Transmission optical modulators, such as LCDs, have a very simple optical structure, which makes them thinner, lighter in weight, and smaller in volume. However, due to the polarity of the light, the light efficiency is low, there is a problem inherent in the liquid crystal material, for example, there is a disadvantage that the response speed is slow and the inside is easy to overheat. In addition, the maximum light efficiency of existing transmission light modulators is limited to a range of 1-2%, requiring dark room conditions to provide acceptable display quality.

Optical modulators such as DMD and AMA have been developed to solve the problems of the aforementioned LCD type optical modulators. DMD shows a relatively good light efficiency of about 5%, but serious fatigue problems are caused by the hinge structure employed in the DMD. In addition, there is a disadvantage that a very complicated and expensive driving circuit is required.

In the AMA, each of the mirrors installed therein reflects light incident from the light source at a predetermined angle, and the reflected light is projected on the screen through an aperture such as a slit or a pinhole. It is a device that can adjust the speed of light to form an image. Therefore, its structure and operation principle are simple, and high light efficiency (more than 10% light efficiency) can be obtained compared to LCD or DMD. In addition, the contrast of the image projected on the screen is improved to obtain a brighter and clearer image.

Each actuator of the AMA generates a deformation in accordance with the electric field generated by the applied electric picture signal and the bias signal. As the actuator deforms, each of the mirrors mounted thereon is tilted. Accordingly, the inclined mirrors reflect light incident from the light source at a predetermined angle to form an image on the screen. Piezoelectric materials such as PZT (Pb (Zr, Ti) O ₃ ), or PLZT ((Pb, La) (Zr, Ti) O ₃ ) are used as actuators for driving the respective mirrors. Further, the actuator may be configured by using a warping material such as PMN (Pb (Mg, Nb) O ₃ ).

These AMAs are largely divided into bulk type and thin film type. Bulk AMA is disclosed in US Pat. No. 5,085,497 to Gregory Um et al. The bulk AMA is made by thinly cutting a multilayer ceramic to mount a ceramic wafer having a metal electrode formed therein in an active matrix in which a transistor is built, and then processing by a sawing method and installing a mirror thereon. However, bulk AMA requires very high precision in design and manufacture, and has a disadvantage of slow response of the strained layer. Accordingly, recently, a thin film type AMA that can be manufactured using a semiconductor manufacturing process has been developed. For example, such a thin film type AMA is disclosed in Korean Patent Application No. 95-13353 (name of the invention: a method for manufacturing an optical path control device), filed by the applicant with the Korean Patent Office.

Thin Film Type Actuated Mirror Array (TFAMA) is a reflective light modulator that uses a thin film piezoelectric actuator in connection with microscopic mirrors, combined with more than 300,000 pixels of a single-plate mirror. It has been developed to have uniformity of massive accumulation. This TFAMA consists of panels of 640x480 pixels representing red (R), green (G) and blue (B), respectively. The pixels are designed as cantilever structures to maximize the mirror surface area to increase the light efficiency. The cantilever structure includes an active matrix to which an image signal voltage is applied and a mirror operated by an applied electrical signal.

1 illustrates a conventional projection type image display apparatus which can display red, green and blue light rays sequentially on a screen using a single-plate thin film type AMA to display a color image corresponding to the colored light rays. Illustrated.

In order to display a color image on the screen, three rays of red, green and blue must be modulated by a spatial light modulator such as an AMA, especially in projection systems using single-plate light modulators. There is a need for means for irradiating green and blue lights.

Referring to FIG. 1, a conventional projection type image display apparatus 10 includes a metal halide lamp 11 of 170 W to 250 W for emitting light, and a reflector for reflecting light from the lamp 11. reflector 12, a source lens 13 for condensing the light rays emitted from the lamp 11, a color wheel 15 for separating the light rays into red, green and blue light sequentially, passing the light rays through A source stop 14 having apertures for determining the amount of light rays forming an image, a source mirror 16 for primarily changing the light path of the color light beams obtained by the color wheel 15, the A field lens 18 for mapping the image of the source stop 14 to the projection stop 22 1: 1, an AMA having a plurality of mirrors and modulating the intensity of the light emitted from the field lens 18 Module 20, through light beam A projection stop 22 having an opening for concentrating the flux of the modulated light beam, and a projection lens 26 for projecting the light beam passing through the projection stop 22 onto the screen 28. .

FIG. 2 is an enlarged plan view of the color wheel 15 of the apparatus of FIG. 1. As shown in FIG. 2, the color wheel 15 consists of a series of color segments of red, green and blue transmission filters and is rotated about its axis by a drive such as a motor. To change the color.

The operation principle of the conventional projection type image display apparatus 10 having the above structure will be briefly described as follows.

First, the light rays emitted from the halogen metal lamp 11 are focused by the source lens 13 and then focused toward the color wheel 15. The color wheel 15 rotates about its axis such that its color segments sequentially block white light. Accordingly, after the white light passes through the color wheel 15, the light turns into red, green, and blue color rays sequentially, which pass through the opening of the source stop 14 to the source mirror 16. It is irradiated and the light path is primarily changed and then incident on the field lens 18. The color light rays that have passed through the field lens 18 sequentially, ie, the red, green and blue light rays, are sequentially irradiated to the AMA module 20 with parallel light. Each mirror of the AMA module 20 modulates the color rays in accordance with an image signal voltage applied to an actuator provided thereunder. As a result, the color rays reflected from each mirror of the AMA module 20 are focused on the field lens 18 and then irradiated onto the projection stop 22.

The color light rays incident on the front surface of the projection stop 22 do not pass through the openings but are totally reflected, and the color light rays passing through the openings are projected onto the screen 28 by the projection lens 26 to correspond to the color image corresponding thereto. Is displayed. For example, when red light is irradiated to the AMA module 20, the AMA module 20 forms an image corresponding to red and projects it on the screen 28. Then, the green image by green light and the blue image by blue light are sequentially displayed on the screen. However, with the naked eye, the monochrome images of each of the red, green, and blue colors are combined and recognized as full color.

According to the conventional projection type image display device described above, the color light 15 is used to sequentially change white light into red, green and blue light. In this case, in order to match the color of the color wheel 15 with the signal applied to the AMA module 20, that is, to maintain the imaging relationship between the color wheel 15 and the AMA module 20. ) And a predetermined lens unit 30 is added between the source stop 14. In addition, in order to irradiate the light collected by the source lens 13 to the AMA module 20 without light loss, the size of the color fragment of the color wheel 15 should be made larger than that of the source lens 13. Therefore, not only the size of the optical system is increased, but also it is difficult to arrange the color wheel 15 and the lens unit 30 between the source lens 13 and the source stop 14.

Accordingly, an object of the present invention is to provide a projection type image display apparatus which can easily secure a space for arranging a color wheel in a projection type image display apparatus including a single-plate AMA module.

1 is a schematic diagram showing a conventional projection type image display apparatus.

FIG. 2 is an enlarged plan view of the color wheel of FIG. 1.

3 is a schematic diagram showing a projection image display device according to the present invention.

4 is a plan view for explaining a relationship between the color wheel and the projection stop shown in FIG.

<Explanation of symbols for main parts of the drawings>

100: projection display device 111: lamp

112: source lens 113: source stop

114: source mirror 115: reflector

116: field lens 118: AMA module

120: projection stop 122: projection lens

124: screen 125: color wheel

In order to achieve the above object, a projection image display apparatus according to the present invention includes a light source for generating light rays, a plurality of mirrors on which the light rays are illuminated, and each mirror includes a plurality of pixels displayed on a screen. An AMA module deformed to correspond to an intensity of a corresponding pixel, a projection stop having an opening, and a flux of the light passing through the opening controlling the intensity of the light reflected from each mirror of the AMA module; Provided is a projection-type image display device including a color wheel for separating light rays passing through into red, green or blue color light rays, and a projection lens for projecting the color light rays passing through the color wheel on a screen.

As described above, according to the present invention, a color wheel for separating white light into red, green and blue color light rays is provided immediately after the projection stop. Therefore, it becomes easy to secure space for installing the color wheel. In addition, since the size of the color wheel is determined by the size of the projection stop, the size of the color wheel can be reduced, and the optical system can be compactly configured.

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

FIG. 3 shows a projection type image display apparatus capable of displaying color images corresponding to the color rays by projecting red, green and blue rays sequentially on a screen using a single-plate thin film type AMA according to the present invention. do.

Referring to FIG. 3, the projection image display apparatus 100 according to the present invention includes a lamp 111, a source lens 112, a source stop 113, a reflector 115, and a source mirror 114 for emitting light rays. , Field lens 116, AMA module 118, projection stop 120, projection lens 122, screen 124, and color wheel 125.

The lamp 111 for emitting light is preferably a 170 W to 250 W halogen metal lamp that emits long wavelength infrared (LWIR) to ultraviolet (UV) light in the spectrum. The reflector 115 serves to reflect the light emitted from the lamp in the opposite direction with respect to the source lens 112 to be directed back to the source lens 112.

The source lens 112 collects light rays emitted from the lamp 111 into parallel light. The source stop 113 is an optically opaque member and has an opening formed to allow light to pass therethrough. The source stop 113 determines the amount of light that forms the image. The source mirror 114 primarily changes the path of the light beams passing through the source stop 113 to the AMA module 118.

The field lens 116 transmits the light reflected by the source mirror 114 without light loss so that the image of the source stop 113 corresponds to the projection stop 120 in a 1: 1 manner. Investigate with).

The AMA module 118 includes a plurality of mirrors for reflecting the irradiated rays, which modulate the intensity of the rays in accordance with an image signal applied to an actuator provided thereunder. That is, each mirror is deformed to a deformation size corresponding to the intensity of the corresponding one pixel among the plurality of pixels displayed on the screen.

The projection stop 120 is an optically opaque member, and has an optically reflective surface and an opening formed to pass a light beam. Preferably, the opening is a pinhole or slit. The flux of light rays passing through the opening of the projection stop 120 controls the intensity of light rays reflected from each mirror of the AMA module 118.

The color wheel 125 consists of a series of color fragments of red, green and blue transmission filters and changes the color of the white light while rotating about its axis by a drive such as a motor. In the present invention, by arranging the color wheel 125 immediately after the projection stop 120, it becomes easy to secure a space for installing the color wheel 125. In addition, since the size of the color wheel 125 may be determined by the size of the projection stop 120, the size of the color wheel 125 may be reduced.

The projection lens 122 projects a color ray obtained by the color wheel 125 on the screen 124 to display a color image corresponding thereto.

The operation principle of the projection image display device 100 according to the present invention having the above-described structure will be described in more detail as follows.

First, light rays emitted from the halogen metal lamp 111 are collected by the source lens 112, and then irradiated to the source mirror 114 through the opening of the source stop 113. The light beam whose light path is changed from the source mirror 114 is irradiated to the AMA module 118 by parallel light by the field lens 116.

If the OFF signal is applied to the AMA module 118, the respective mirrors of the AMA module do not vibrate, tilt or bend. As a result, light rays are imaged out of the projection stop 120 and thus cannot reach on the screen 124.

If the ON signal is applied to the AMA module 118, the respective mirrors of the AMA module 118 are completely inclined so that all the light beams irradiated on the AMA module 118 pass through the opening of the projection stop 120. do. At this time, the path of the light beam reflected from each mirror determines the intensity of the light beam passing through the opening of the projection stop 120. That is, the flux of the light rays passing through the opening of the projection stop 120 is controlled by the direction of the mirror of the AMA module 118 relative to the projection stop 120.

As such, the light rays passing through the opening of the projection stop 120 are changed into red, green, or blue color light rays by the color wheel 125 and are projected onto the screen 124 by the projection lens 122 to thereby correspond to the color corresponding thereto. Display an image. For example, when white light passing through the opening of the projection stop 120 is irradiated to the red fragment of the color wheel 125, the color wheel 125 projects a red image on the screen 124. Then, the green image and the blue image are sequentially displayed on the screen 124. However, with the naked eye, the monochrome images of each of the red, green, and blue colors are combined and recognized as full color.

On the other hand, if the color wheel is disposed between the projection stop and the projection lens as described above, the color noise of the color wheel of the color wheel and the signal applied to the AMA module may not be synchronized. The way to solve this problem is as follows.

The first method is to drive the AMA module in a frame manner. For example, when a red image is to be displayed, a red signal to be applied to the pixels of the AMA module is stored in a predetermined buffer unit, and the signals are simultaneously turned on at any moment. In this case, data of one frame (that is, a red image) corresponding to one screen is simultaneously displayed on the screen.

The second method is to make the length (a) of the arc of the color wheel 125 very large compared to the opening size (b) of the projection stop 120, as shown in FIG. In this way, noise generated by the color boundary of the color wheel 125 can be reduced.

As described above, according to the projection type image display device of the present invention, a color wheel for separating white light into red, green and blue color light rays is provided immediately after the projection stop. Therefore, it becomes easy to secure space for installing the color wheel. In addition, since the size of the color wheel is determined by the size of the projection stop, the size of the color wheel can be reduced, and the optical system can be compactly configured.

Although described above with reference to a preferred embodiment of the present invention, those skilled in the art will be variously modified and changed within the scope of the invention without departing from the spirit and scope of the invention described in the claims below I can understand that you can.

Claims (3)

A light source 111 for generating light rays; Above that includes a plurality of mirrors in which the rays are illuminated, each mirror being modified to correspond to the intensity of the corresponding one of the plurality of pixels displayed on the screen. ; A projection stop (120) having an opening and controlling the intensity of light reflected from each mirror of said AMA module (118) by the flux of light passing through said opening; A color wheel 125 for separating the light beams passing through the projection stop 120 into red, green or blue color light beams; And And a projection lens (122) for projecting the color light beams passing through the color wheel (125) onto a screen. The projection image display device according to claim 1, wherein the color wheel (125) is composed of a series of color fragments of red, green and blue transmission filters. The projection type image display device according to claim 1, wherein the arc length of the color wheel (125) is larger than the opening size of the projection stop (120).