KR100208675B1 - Optical system of an actuated mirror array - Google Patents

Abstract

An actuated mirror array (AMA) optical system is disclosed. The AMA optical system includes a light source for generating a light beam and a plurality of mirrors on which the light beam is illuminated, each mirror being modified to correspond to the intensity of a corresponding one of the plurality of pixels displayed on the screen. And includes an AMA panel. The cover plate blocks light reflected from the periphery of the AMA panel. The field lens irradiates the AMA panel with light rays generated from the light source. The field lens barrel fixes the field lens, and is formed to have a slope at the bottom thereof to reflect light scattered from the cover plate. The projection lens projects light rays reflected from each mirror of the AMA panel onto the screen. The light reflected from other surfaces except for the pixel surface of the AMA panel is blocked by the inclined surface of the field lens barrel so that a clean screen can be realized.

Description

Actuated Mirror Array Optics

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to an Actuated Mirror Array (hereinafter referred to as AMA) optical system, and more particularly, in an optical system using an AMA panel used as a light modulator for projecting an image onto a screen, in addition to the pixel plane of the AMA panel. It relates to an optical system that can improve the image quality by blocking the light reflected from the surface.

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.

Projection type image display apparatuses include liquid crystal displays (hereinafter referred to as LCDs), deformable mirror devices (hereinafter referred to as DMDs), and activated mirror arrays (hereinafter referred to as AMAs). And the like). 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 contrast, AMA is a piezoelectrically driven mirror array that provides light efficiency of 10% or more. In an AMA light modulator, each actuator causes a deformation in accordance with the electric field generated by the applied electrical image signal and the bias voltage. When the actuator causes deformation, each of the mirrors mounted on top of the actuator is tilted. Accordingly, the inclined mirrors can reflect light incident from the light source at a predetermined angle. The AMA optical modulator has a simple structure and operation principle, and can obtain high light efficiency compared to LCD or DMD. It also provides enough contrast to provide a bright and clear image under normal room temperature light conditions. Moreover, it is not only affected by the polarity of the incident light, but also does not affect the polarity of the reflected light. In addition, the reflective properties of the AMA are relatively less sensitive to temperature, which has the advantage that the brightness of the screen can be improved over other devices that are easily affected by high power light sources.

Such AMA devices are largely classified into bulk type devices and thin film type devices. The bulk AMA has a center electrode between two piezoelectric layers. The central electrode is connected to an active matrix having a conductive epoxy for the signal voltage. On top of the bulk AMA is a mirror layer, which has an inclination angle of +/- 0.25 ° under a voltage of up to 30V. For this reason, bulk AMA requires very high precision in design and manufacture, and there are many difficulties in assembling the structure.

Accordingly, recently, a thin film type AMA (hereinafter referred to as TFAMA) has been developed that can be manufactured using a semiconductor manufacturing process in order to complete the quality of mirror arrays. The TFAMA is disclosed in Korean Patent Application No. 95-13358, filed May 26, 1995 by the applicant.

TFAMA is a reflective light modulator that uses thin film piezo-electric actuators in conjunction with microscopic mirrors to provide uniformity of large scale integration across more than 300,000 pixels of a single-plate mirror. Has been developed. 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 the applied signal voltage.

A conventional optical system using a single panel TFAMA as an optical modulator is shown in FIG.

Referring to FIG. 1, a conventional AMA optical system 10 includes a 170 ha to 250 w metal halide lamp 11 for emitting light, and a reflector for reflecting light from the lamp 11. (15), a source lens (12) for making the light beam emitted from the lamp (11) into parallel light, a source stop for determining the amount of light beam forming an image with an aperture for passing the light beam; (13), a source mirror (14) for reflecting light rays passing through the source stop (13), and a field lens (16) for one-to-one correspondence of the image of the source stop (13) to the projection stop (20). A projection panel having a plurality of mirrors and having an AMA panel 18 for modulating the intensity of the light beam irradiated from the field lens 16, an opening for passing the light beam, and concentrating the flux of the modulated light beam. Stop 20, and the projection And a top projection lens 22 for projecting a light beam passing through the 20 onto a screen (not shown).

The operation principle of the conventional AMA optical system 10 is briefly described as follows.

First, when the AMA optical system 10 is driven, light rays emitted from the halogen metal lamp 11 are condensed into parallel light by the source lens 12, and then pass through the opening of the source stop 13 to obtain a source mirror ( 14) is irradiated onto. The light rays reflected from the source mirror 14 are irradiated onto the AMA panel 18 with parallel light through the field lens 16 after the path is primarily changed.

Each mirror of the AMA panel 18 vibrates, tilts or bends in accordance with an image signal voltage applied to an actuator provided below it. 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 the mirrors of the AMA panel 18 determines the intensity of the light beam passing through the opening of the projection stop 20. In other words, the flux of light rays passing through the opening of the projection stop 20 is controlled by the direction of the mirror of the AMA panel 18 with respect to the projection stop 20.

2 is an enlarged view of the field lens 16 and the AMA panel 18 used in the conventional AMA optical system described above.

Referring to FIG. 2, the field lens 16 is fixed by a field lens barrel 17 formed of a material having high heat resistance, for example, plastic. The AMA panel 18 is formed on a substrate 25 in which a driving integrated circuit (IC) or the like is embedded, and the substrate 25 is fixed by a back plate 27. A cover plate 19 is formed on the back plate 27, and the cover plate 19 has a periphery except for the pixel surface 18a on which the mirror of the AMA panel 18 is attached. To prevent an image from forming on the screen. The field lens barrel 17 is attached to the cover plate 19. 3 is an enlarged view of a portion A of FIG. 2.

Referring to FIG. 3, light is also scattered in the cover plate 19 itself to block light reflected from the periphery of the AMA panel 18. As a part of the light scattered from the cover plate 19 is projected on the screen through the projection stop, the edge of the screen is not clean.

Further, in general, the AMA panel 18 is finely tilted in the mirror even when no image signal voltage is applied. Part of the light scattered by the tilting tilt of the mirror itself passes through the projection stop, thereby degrading the picture quality.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to improve image quality by blocking light reflected from a surface other than the pixel surface of an AMA panel in an optical system using an AMA panel as an optical modulator. It is to provide an optical system that can be made.

1 is a schematic diagram showing a conventional actuated mirror array optical system.

FIG. 2 is an enlarged view of a field lens and an actuated mirror array panel used in the optical system of FIG. 1.

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

4 is a schematic diagram showing an actuated mirror array optical system according to an embodiment of the present invention.

FIG. 5 is an enlarged view of a field lens and an actuated mirror array panel used in the optical system of FIG. 4.

FIG. 6 is an enlarged view of the dotted line portion A ′ of FIG. 5.

Explanation of symbols for main parts of the drawings

10, 100 ... AMA optics 11, 111 ... lamp

12, 112 ... source lens 13, 113 ... source stop

14, 114 ... source mirror 15, 115 ... reflector

16, 116 ... field lens 17, 117 ... field lens barrel

18, 118 ... AMA panel 19, 119 ... cover plate

20, 120 ... projection stop 22, 122 ... projection lens

In order to achieve the above object of the present invention,

A light source for generating light rays;

A plurality of mirrors on which the rays are illuminated, each mirror modified to correspond to the intensity of a corresponding one of the plurality of pixels displayed on the screen, the AMA panel;

A cover plate for blocking light reflected from the periphery of the AMA panel;

A field lens for irradiating the light generated from the light source to the AMA panel as parallel light;

A field lens barrel portion fixing the field lens and having a bottom portion thereof inclined to reflect light scattered from the cover plate; And

Provided is an optical system of an actuated mirror array having an optical system, comprising a projection lens for projecting light reflected from each mirror of the AMA panel onto a screen.

As described above, in the AMA optical system according to the present invention, the AMA panel is formed on a substrate in which a drive integrated circuit (IC) or the like is embedded, and the substrate is fixed by a back plate. On the back plate, a cover plate for blocking light reflected from the peripheral portion except the pixel surface, that is, the mirror of the AMA panel is attached, is formed. The field lens is fixed by the field lens barrel, and the bottom portion of the field lens barrel is inclined. Preferably, the bottom portion of the field lens barrel is formed with an inclination angle of 10 ° or more, and more preferably with an inclination angle of 30 ° to 45 °. The inclined surface formed as described above serves as a mirror to reflect light scattered from the cover plate so that the projection stop does not pass. In addition, the inclined surface also reflects light scattered by the tilting tilt of the mirror of the AMA panel itself, thereby preventing it from passing through the projection stop.

Therefore, according to the present invention, since the light reflected from other surfaces except for the pixel surface of the AMA panel can be blocked by the field lens barrel formed so that its bottom portion is inclined, a clean screen can be realized.

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

Fig. 4 is a schematic diagram showing an optical system using a single plate type thin film type AMA according to the present invention as an optical modulator, and illustrates a single plate monochrome system.

Referring to FIG. 4, the AMA optical system 100 according to the present invention includes a lamp 111 for emitting light, a source lens 112, a source stop 113, a source mirror 114, a reflector 115, and a field. Lens 116, AMA panel 118, projection stop 120, and projection lens 122.

Lamp 111 for emitting light preferably emits long wavelength infrared (LWIR) to ultraviolet (UV) light in the spectrum as an arc lamp, such as a halogen metal lamp of 170W to 250W. The reflector 115 serves to reflect the light rays emitted from the lamp in the opposite direction to the source lens 112 and back to the source lens 112.

The source lens 112 collects the 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 serves to reflect the light rays passing through the source stop and redirect its path towards the AMA panel 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 in a 1: 1 manner. Investigate with). The AMA panel 118 includes a plurality of mirrors for reflecting the irradiated rays, which modulate the intensity of the rays in accordance with the image signal voltage applied to the 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.

5 is an enlarged view of the field lens 116 and the AMA panel 118.

Referring to FIG. 5, the field lens 116 is fixed by the field lens barrel 117 formed of a material having high heat resistance, for example, plastic. The AMA panel 118 is formed on a substrate 125 in which a driving integrated circuit (IC) or the like is embedded, and the substrate 125 is fixed by a back plate 127. A cover plate 119 is formed on the back plate 127, and the cover plate 119 is a surface on which the mirror of the AMA panel 118 is attached, that is, a peripheral portion except the pixel surface 118a. To prevent an image from forming on the screen. However, light is also scattered in the cover plate 119 itself, and the AMA panel 118 is finely tilted even when an image signal voltage is not applied.

The field lens barrel 117 is attached to the cover plate 119. FIG. 6 is an enlarged view of a dotted line A ′ of FIG. 5.

Referring to FIG. 6, the bottom portion of the field lens barrel 117 is formed to have an inclination angle μH. Preferably, the bottom portion of the field lens barrel 117 is formed with an inclination angle of 10 degrees or more, and more preferably with an inclination angle of 30 degrees to 45 degrees. The inclined surface formed as described above serves as a mirror to reflect the light scattered from the cover plate 119 so as not to pass through the projection stop. In addition, the inclined surface also reflects light scattered by the tilting tilt of the mirror itself of the AMA panel 118, thereby preventing it from passing through the projection stop. Here, the cover plate 119 measures the length d of the inclined surface of the field lens barrel 117 and adjusts its position.

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 light modulator 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.

Referring to the operation principle of the AMA optical system 100 according to the present invention having the above-described structure in more detail as follows.

First, when the AMA optical system 100 is driven, the light emitted from the lamp 111 composed of an arc lamp such as a halogen metal lamp is condensed into parallel light through the source lens 112, and then the source stop 113 is closed. It passes through and is irradiated onto the source mirror 114. The light rays reflected from the source mirror 114 are irradiated onto the AMA panel 118 with parallel light through the field lens 116 after the path is primarily changed.

If no image signal voltage is applied to the actuators of the AMA panel 118 (ie, when the voltage is OFF), the respective mirrors of the AMA panel 118 do not vibrate, tilt or bend. As a result, light rays are imaged out of the projection stop 120 and thus cannot reach on a screen (not shown).

If a predetermined voltage less than the maximum voltage is applied to the actuators of the AMA panel 118, each of the mirrors of the AMA panel 118 is inclined to some extent, so that a part of the rays irradiated onto the AMA panel 118 is projected. Projected on the screen by passing through the opening of the stop 120. That is, some of the light rays that are irradiated are reflected by the front surface of the projection stop 120, and the remaining light rays pass through the opening of the projection stop 120.

When the maximum signal voltage is applied to the actuators of the AMA panel 118, the respective mirrors of the AMA panel 118 are completely inclined so that the light beam irradiated on the AMA panel 118 passes through the opening of the projection stop 120. Aim. As a result, the light rays reflected by the mirror of the AMA panel 118 pass through the opening of the projection stop 120 and are projected on the screen by the projection lens 122 to display an image corresponding thereto. 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 light rays passing through the opening of the projection stop 120 is controlled by the direction of the mirror of the AMA panel 118 relative to the projection stop 120.

Here, FIG. 4 illustrates a monochromatic system using a single-plate AMA, but according to another preferred embodiment of the present invention, a color wheel consisting of a series of color fragments of red, green and blue transmission filters The invention can be applied to a single plate color system capable of displaying red, green and blue images by sequentially irradiating red, green and blue light to a single panel AMA using a color wheel.

In addition, according to another preferred embodiment of the present invention, the present invention can be applied to a multi-panel color system using a three panel AMA.

As described above, in the AMA optical system of the present invention, the AMA panel is formed on a substrate in which a drive integrated circuit (IC) or the like is embedded, and the substrate is fixed by a back plate. On the back plate, a cover plate for blocking light reflected from the peripheral portion except the pixel surface, that is, the mirror of the AMA panel is attached, is formed. The field lens is fixed by the field lens barrel, and the bottom portion of the field lens barrel is inclined. The inclined surface acts as a mirror to reflect the light scattered from the cover plate so that it does not pass through the projection stop. In addition, the inclined surface also reflects light scattered by the tilting tilt of the mirror of the AMA panel itself, thereby preventing it from passing through the projection stop.

Therefore, according to the present invention, since the light reflected from other surfaces except for the pixel surface of the AMA panel can be blocked by the field lens barrel formed so that its bottom portion is inclined, a clean screen can be realized.

Although the above has been described 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 present invention without departing from the spirit and scope of the invention described in the claims below. I can understand that you can.

Claims (5)

A light source 111 for generating light rays; A plurality of mirrors on which the rays are illuminated, each mirror modified to correspond to the intensity of a corresponding one of the plurality of pixels displayed on the screen, and an activated mirror array panel 118; A cover plate (119) for blocking light rays reflected from the periphery of the actuated mirror array panel; A field lens 116 for irradiating light rays generated from the light source to the actuated mirror array panel with parallel light; A field lens barrel 117 which fixes the field lens and has a bottom portion thereof inclined to reflect light scattered from the cover plate; And And a projection lens (122) for projecting light rays reflected from each mirror of the actuated mirror array panel onto the screen. The optical system according to claim 1, wherein the actuated mirror array panel (118) is fixed by a back plate (127), and the cover plate (119) is formed on the back plate (127). The optical system according to claim 1, wherein a bottom portion of the field lens barrel portion (117) is formed at an inclination angle of 10 degrees or more. The optical system according to claim 3, wherein the bottom portion of the field lens barrel portion (117) has an inclination angle of 30 degrees to 45 degrees. According to claim 1, Source lens 112 for condensing the light rays generated from the light source, Source stop 113 for opening and concentrating the flux of the light beam, Light rays passing through the source stop 113 Source mirror 114 for reflecting and changing its path, and a projection stop for controlling the intensity of light reflected from each mirror of the actuated mirror array panel 118 having an opening and flux of light passing through the opening Optical system further comprises (120).