KR19990043704A - Projection type image display device - Google Patents

Abstract

A projection type image display device including an AMA module is disclosed. The apparatus has 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. A module, a projection stop having an opening and flux of light passing through the opening controlling the intensity of light reflected from each mirror of the AMA module, a projection lens for projecting the light beam passing through the projection stop on a screen, and And a side panel attached to the projection lens and having a plurality of light absorbers formed at the site where the light rays reach the projection lens and fail to pass through the projection stop. A large number of light absorbers can prevent the temperature rise inside the optical system and suppress the generation of scattered light.

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 capable of preventing a temperature rise and reducing noise caused by scattered light.

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.

The AMA reflects the light incident from the light source at each of the mirrors installed therein, 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 filed by the applicant of the Korean Patent Office.

The thin film type AMA is a reflective type optical modulator using a thin film piezoelectric actuator in connection with microscopic mirrors. The thin film type AMA combines more than 300,000 pixels of a single plate type mirror to achieve evenness of large scale integration. It has been developed to have. 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 16, an array of mirror pixels and an AMA module 18 for modulating the intensity of the light emitted from the field lens 16, having an opening for passing the light and concentrating the flux of the modulated light Pro to let 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 rays reflected from the respective mirrors of the AMA module 18 determines the intensity of the light rays 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.

In the projection type image display apparatus 10 described above, a projection lens barrel (not shown) formed of a material having high heat resistance to fix the projection lens 22 is a side panel 25 that protects the optical system. ) Is attached. Another side panel 24 is attached to the source lens 12.

Therefore, the light rays that do not pass through the projection stop 20 are concentrated at corner portions of the side panel 25 positioned next to the projection stop 20, thereby acting as a factor of raising the temperature inside the optical system.

In addition, the surface of the side panel 25 is not subjected to optical treatment and scatters light rays incident on the surface. As such, the scattered light generated from the surface of the side panel 25 passes through the projection stop 20 and is projected onto the screen, thereby generating optical noise.

Accordingly, it is an object of the present invention to provide a projection image display apparatus which can prevent the temperature rise inside the optical system and reduce the noise caused by the scattered light.

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

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

3 is an enlarged view of a portion 'A' of FIG. 2.

<Explanation of symbols for main parts of the drawings>

100: AMA optical system 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

130: side panel 135: light absorber

In order to achieve the above object, the present invention has a light source for generating light rays, an array of mirrors for reflecting light rays and each mirror corresponds to the intensity of a corresponding one of the plurality of pixels displayed on the screen. An AMA module which is deformed to a deformation size, a projection stop having an opening and flux of the light rays passing through the opening controlling the intensity of the light rays reflected from each mirror of the AMA module, and a light beam passing through the projection stop on the screen. It provides a projection lens for projecting, and a side panel attached to the projection lens, the side panel is formed with a plurality of optical light absorbers in the area where the light rays that do not pass through the projection stop reaches. .

As described above, according to the projection type image display device according to the present invention, a plurality of light absorbers are formed in the corner portion of the side panel where light rays that do not pass through the projection stop arrive. The light absorbers are antireflective coated and tilted at an angle. Accordingly, the light absorbers do not generate scattered light by transmitting incident light rays in one direction, and prevent the temperature rise inside the optical system by sending the absorbed heat out of the optical system.

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

Fig. 2 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. 2, the projection image display apparatus 100 according to the present invention includes a lamp 111 for emitting light rays, a source 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 serves to reflect the light emitted from the lamp 111 in the opposite direction with respect to the source lens 112 so as to be directed back to the source lens 112.

The source lens 112 collects light rays emitted from the lamp 111. 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 a corresponding image.

In addition, the projection lens 122 is fixed by a projection lens barrel (not shown) formed of a material having high heat resistance, and the barrel is attached to the side panel 130 that protects the optical system. Another side panel 129 is attached to the source lens 112.

3 is an enlarged view of the side panel 130. Referring to FIG. 3, a plurality of light absorbers 135 are formed at corner portions of the side panel 130, that is, portions where light rays that do not pass through the projection stop 120 arrive. The light absorber 135 is formed of a material having high thermal conductivity, for example, aluminum, and the surface of the light absorber 135 is antireflective coated. The light absorber 135 is formed to be inclined at a predetermined angle, thereby transmitting incident light rays in one direction to suppress generation of scattered light.

In addition, according to another preferred embodiment of the present invention, by connecting the cooling fan to the corner portion of the side panel 130 in which the plurality of light absorbers 135 are formed to absorb the heat absorbed by the light absorbers 135 of the optical system Pass it upwards.

Hereinafter, the operation 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. 2.

First, light rays emitted from the halogen metal lamp 111 are collected by the source lens 112, and then irradiated through the opening of the source stop 113 to the source mirror 114 so that the 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 a signal smaller than the maximum signal is applied to each actuator of the AMA module 118, only a part of the incident light beams passes through the opening of the projection stop 120 because the mirror corresponding thereto is tilted with a predetermined tilt angle. 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 completely inclined so that the incident light beam is passed through the opening of the projection stop 120. As a result, the light rays reflected by each mirror of the AMA module 118 are projected onto 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. 2 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 multi plate color system may be used.

As described above, according to the projection type image display device according to the present invention, a plurality of light absorbers are formed in the corner portion of the side panel where light rays that do not pass through the projection stop arrive. The light absorbers are antireflective coated and tilted at an angle. Accordingly, the light absorbers do not generate scattered light by transmitting incident light rays in one direction, and prevent the temperature rise inside the optical system by sending the absorbed heat out of the optical system.

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); A projection stop (120) having an opening and the flux of light passing through the opening controlling the intensity of light reflected from each mirror of the AMA module (118); A projection lens 122 for projecting light beams passing through the projection stop 120 onto a screen; And And a side panel (130) attached to the projection lens (122) and having a plurality of light absorbers (135) formed at a portion where light rays that do not pass through the projection stop (120) reach. Device. The projection type image display apparatus according to claim 1, wherein the surfaces of the plurality of light absorbers (135) are antireflective coating. The projection type image display apparatus according to claim 1, wherein the plurality of light absorbers (135) are inclined at a predetermined angle. The projection type image display device according to claim 1, wherein the side panel (130) is attached to a barrel portion for fixing the projection lens (122).