KR19990047454A - Projection type image display device - Google Patents

Abstract

Disclosed is a projection image display apparatus including an AMA module. The apparatus comprises an AMA having a light source for generating light rays, an array of mirrors for reflecting light rays and each mirror being transformed to a deformation size corresponding to the intensity of a corresponding one of the plurality of pixels displayed on the screen. Module, the light beam from the light source, an anamorphic lens for irradiating the AMA module into a light beam having a ratio of a: b (a is height, b is width), and the light reflected from each mirror of the AMA module is screened. And a projection lens for projecting onto. By irradiating the square beam to the square AMA module, the light loss can be reduced and the light efficiency can be increased, and the brightness of the screen can be improved.

Description

Projection type image display device

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection type image display device, and more particularly, to a projection type image display device including an Actuated Mirror Array (AMA) module used to project an image onto a screen. The present invention relates to a projection image display device which can increase the light efficiency of incident light by reducing the loss of light irradiated to the AMA module using an anamorphic lens having a different aspect ratio.

In general, spatial light modulators, which are devices for projecting optical energy onto a screen, can be applied to various fields such as optical communication, image processing, and information display devices. 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 actuated mirror array (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. Such 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.

The thin film type AMA is a reflective type light modulator using a thin film piezo-electric actuator in connection with microscopic mirrors. It has been developed to have a degree. The thin film type AMA is composed of 640x480 pixels representing red (R), green (G), and blue (B), respectively. The pixels are designed as a cantilever structure to maximize the mirror surface area to increase the light efficiency. The container structure includes an active matrix to which an image signal is applied and a mirror operated by the applied signal.

A conventional projection type image display device including a single panel thin film type AMA module is shown in FIG.

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 15, a source lens 12 for condensing the light rays emitted from the lamp 11, a source stop 13 for determining the amount of light rays forming an image with apertures for passing the light rays ), A source mirror 14 for primarily changing the path of the light ray passing through the source stop 13, and a field for mapping the image of the source stop 13 to the projection stop 20 at 1: 1. A lens module 16, an array of mirrors and an AMA module 18 for modulating the intensity of the light emitted from the field lens 16, an aperture for passing the light beam and flux of the modulated light Pro to focus Illustration stop (20), and a projection lens 22 for projecting a light beam passing through the stop projection (20) on a screen (not shown).

The operation principle of the conventional projection type image display apparatus 10 having the above-described structure will be described with reference to FIG. 1 as follows.

First, light rays emitted from the halogen metal lamp 11 are collected by the source lens 12, and then irradiated through the opening of the source stop 13 to the source mirror 14 so that the optical path is primarily changed. . The light reflected by the source mirror 14 is irradiated onto the AMA module 18 with parallel light through the field lens 16. Each mirror of the AMA module 18 vibrates, tilts or bends according to a signal applied to an actuator provided thereunder. Accordingly, light rays passing through the field lens 16 are reflected from the mirrors and then passed through the opening of the projection stop 20 to be projected on the screen through the projection lens 22 to form an image.

At this time, the path of the light beam reflected from each of the mirrors determines the intensity of the light beam passing through the opening of the projection stop 20. That is, the flux of the light rays passing through the opening of the projection stop 20 is controlled by the direction of the mirror of the AMA module 18 with respect to the projection stop 20.

2 is a plan view showing the distribution of light rays radiated onto the AMA module 18. Referring to FIG. 2, in the above-described conventional projection type image display apparatus 10, the AMA module 18 is formed into a quadrangle having a ratio of height h to width w of 3: 4 on the screen. Make a screen with a ratio of four. Therefore, the cross-sectional area of the circular light beam generated from the lamp 11 at the position of the AMA module 18 is

It should have a diameter of and the center of the circular beam should coincide with the center of the AMA module 18.

However, since the circular light beam is irradiated to the rectangular AMA module 18, the light beam portion outside the AMA module 18 is blocked. Therefore, the light rays in that area cannot be used to project the AMA module 18 onto the screen, so that a large amount of light loss occurs to darken the screen.

Accordingly, it is an object of the present invention to provide a projection type image display device which can increase the light efficiency and brighten the screen by reducing the loss of light irradiated to the AMA module.

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

FIG. 2 is a plan view illustrating a light distribution irradiated to the actuated mirror array module of FIG. 1.

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

4 is a plan view illustrating a light distribution irradiated to the actuated mirror array module of FIG. 3.

<Explanation of symbols for main parts of the drawings>

100: AMA optical system 111: lamp

112: anamorphic lens 113: source stop

114: source mirror 115: reflector

116: field lens 118: AMA module

120: projection stop 122: projection lens

The present invention to achieve the above object, a light source for generating a light ray; An AMA module having an array of mirrors for reflecting light rays and each mirror being modified to a deformation size corresponding to the intensity of a corresponding one of the plurality of pixels displayed on the screen; An anamorphic lens for irradiating the AMA module with a light beam having a ratio of a: b (a represents height and b represents width); And a projection lens for projecting light rays reflected from each mirror of the AMA module onto the screen.

As described above, according to the projection-type image display device according to the present invention, an anamorphic lens is used to form a circular ray generated from a light source having a ratio of a: b (a represents height and b represents width). Made of rays Therefore, by irradiating the rectangular light beam to the rectangular AMA module, it is possible to reduce the light loss to increase the light efficiency and to improve the brightness of the screen.

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

Fig. 3 is a schematic diagram showing a projection type image display apparatus including a single plate type thin film type AMA module according to the present invention, illustrating a single plate type monochrome system.

Referring to FIG. 3, the projection image display apparatus 100 according to the present invention includes a lamp 111 for emitting light, an anamorphic lens 112, a source stop 113, a source mirror 114, and a reflector ( 115, field lens 116, AMA module 118, projection stop 120, and projection lens 122.

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 reflects the light emitted from the lamp 111 in the opposite direction with respect to the anamorphic lens 112 and directs it to the anamorphic lens 112.

The anamorphic lens 112 is a light beam having a circular cross-sectional area emitted from the lamp 111 into a light beam having a rectangular cross-sectional area having a ratio of a: b (where height represents and b represents width). It makes a role. For example, if the AMA module 118 has a ratio of 3: 4, the anamorphic lens 112 turns the circular beam into a rectangular beam with a ratio of 3: 4. Therefore, as shown in FIG. 4, the rectangular AMA module 118 having the ratio of 3: 4 is radiated to the rectangular beam having the ratio of 3: 4 to reduce light loss.

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 serves to reflect the light beams passing through the source stop 113 and direct its light path toward the AMA module 118.

The field lens 116 transmits each ray passing through the source stop 113 without light loss so that the image of the source stop 113 corresponds to the projection stop 120 at 1: 1. 118).

The AMA module 118 has an array of mirrors for reflecting the irradiated light rays. Each mirror modulates the light intensity in accordance with a signal applied to an actuator formed 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 projection lens 122 projects a ray passing through the opening of the projection stop 120 on a screen (not shown) to display an image corresponding thereto.

Hereinafter, the operating principle of the projection image display apparatus 100 according to the present invention having the above-described structure will be described with reference to FIG. 3.

First, a light beam having a circular cross-sectional area emitted from the halogen metal lamp 111 is analyzed by the anamorphic lens 112 in a ratio of a: b (where a represents height and b represents width), for example, 3 : A light ray having a square cross-sectional area with a ratio of 4. The light ray having the ratio of 3: 4 passes through the opening of the source stop 113 and is irradiated to the source mirror 114 so that its optical path is primarily changed. The light reflected by the source mirror 114 is irradiated onto the AMA module 118 through parallel light through the field lens 116.

If a signal is not applied to each actuator of the AMA module 118 (ie, 0V state), the corresponding mirror does not vibrate, tilt or bend. As a result, the light rays reflected by each mirror of the AMA module 118 are imaged off the projection stop 120 and thus cannot reach the screen.

When less than the maximum signal is applied to each actuator of the AMA module 118, a corresponding mirror is actuated with a predetermined inclination angle so that only a portion of the incident light beams pass through the opening of the projection stop 120. . Thus, some of the light rays reflected by each mirror of the AMA module 118 are reflected by the front surface of the projection stop 120, and the remaining light rays are projected on the screen through the opening of the projection stop 120. .

When the maximum signal is applied to each actuator of the AMA module 118, the mirror corresponding thereto is tilted completely so that the incident light beam is directed through the opening of the projection stop 120. As a result, the light rays reflected by each mirror of the AMA module 118 are all imaged in the ratio of 3: 4 on the screen by the projection lens 122 after all of the light passes through the opening of the projection stop 120. 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.

Here, FIG. 3 illustrates a monochromatic system using a single plate AMA, but according to another preferred embodiment of the present invention, a single plate color system or a multiplate color system may be used.

As described above, according to the projection-type image display apparatus according to the present invention, an anamorphic lens is used to form a rectangular light beam having a ratio of a: b (a represents height and b represents width). Made of rays Therefore, by irradiating the rectangular light beam to the rectangular AMA module, it is possible to reduce the light loss to increase the light efficiency and to improve the brightness of the screen.

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 (4)

A light source 111 for generating light rays; An actuated mirror array (AMA) module having an array of mirrors for reflecting light rays, each mirror deformed to a deformation size corresponding to the intensity of a corresponding one of the plurality of pixels displayed on the screen; 118); An anamorphic lens 112 for irradiating the AMA module 118 with the light rays generated from the light source 111 into light rays having a ratio of a: b; And And a projection lens (122) for projecting light rays reflected from each mirror of said AMA module (118) onto a screen. The projection image display device according to claim 1, wherein the AMA module (118) has a ratio of a: b. The method of claim 1, wherein the source stop 113 for concentrating the flux of the light beams passing through the anamorphic lens 112, and reflects the light beams passing through the source stop 113 to the AMA module 118. A source lens 116 for directing the beam reflected by the source mirror 114 to the AMA module 118 with parallel light, and a beam having an aperture and passing through the aperture. And a projection stop (120) whose flux controls the intensity of light reflected from each mirror of said AMA module (118). The projection type image display device according to claim 1, wherein a: b corresponds to a ratio of a height of a screen to a width of a screen.