KR0173707B1 - Optical system for projector - Google Patents

Abstract

The present invention is to provide an optical system of a projection image display device that can change the manufacturing characteristics of the mirror so that the light emitted from the light source is not affected by the inclination angle of the mirror, so that the opacity of the screen color can be resolved. In the configuration of the projection image display device, the third dichroic mirror 52 reflects a green component in the incident white light and transmits the red and blue components, and the fourth dichroic mirror 54 is the third. It is designed to have a cutting area for reflecting only the blue component or only the red component of the color components transmitted from the dichroic mirror 52. When the fourth dichroic mirror 54 is manufactured and installed, a predetermined area is provided. At about 100 nm, it is a useful invention having the effect of eliminating color unevenness because it is not affected by the shift.

Description

Optical system of projection image display device

1 is a plan view showing an optical system of a conventional projection image display device.

2A to 2C show the characteristics of the light spectrum in the conventional projection image labeling apparatus.

3 is a plan view showing an optical system of the projection image display device according to the present invention.

4 is a view showing spectral characteristics of light by a third dichroic mirror in the projection image display apparatus according to the present invention.

5A and 5B show spectral characteristics of light by a fourth dichroic mirror in the projection image display apparatus according to the present invention.

* Explanation of symbols for main parts of the drawings

10: projection image display device 11: light source

12: reflection mirror 20, 30, 40: the first, second and third optical path controller

52, 54: 3rd, 4th dichroic mirror

The present invention relates to an optical system of a projection image display device, and more particularly, in a projection image display device, by changing the manufacturing characteristics of the dichroic mirror for separating red, green, and blue components from white light incident from a light source. The present invention relates to an optical system of a projection image display device capable of eliminating an imbalance in color formed on an image.

An image display apparatus is classified into a direct image display apparatus and a projection image display apparatus according to a display method.

As is well known, a direct view type image display apparatus includes a cathode ray tube (hereinafter referred to as a CRT). Such a CRT image display apparatus has good image quality, but increases in weight and thickness as the screen is enlarged, and the price is increased. There is a problem that this is expensive and there is a limit to having a large screen.

Projection type image display apparatuses are known as liquid crystal displays (hereinafter referred to as LCDs), and the like, and such a large screen LCD can be thinned and the weight can be reduced. However, the LCD has a high light loss due to the polarizing plate, and a thin film transistor for driving the LCD is formed for each pixel, so that there is a limit in increasing the aperture ratio (light transmission area).

Accordingly, a projection image display device using Actuated Mirror Arrays (hereinafter referred to as AMA) has been developed by Aura, USA.

The projection image display device is divided into one-dimensional AMA and two-dimensional AMA. The one-dimensional AMA has mirror surfaces arranged in an M × 1 array, and the two-dimensional AMA has mirror surfaces arranged in an M × N array. Therefore, the projection image display apparatus using the one-dimensional AMA pre-scans the M x 1 rays using a scanning mirror, and the projection image display apparatus using the two-dimensional AMA projects the M x N luminous fluxes to produce an array of M x N pixels. An image with a will be displayed.

1 is a schematic diagram of a conventional projection image display apparatus.

The projection image display apparatus 10 includes a light source 11, a reflection mirror 12, first and second dichroic mirrors 13 and 14, a projection stop 15, a projection lens 16, a screen 17 and first, second and third optical path controllers 20, 30 and 40.

The light source 11 emits high brightness white light, and the light emitted from the light source 11 is reflected by the reflection mirror 12.

The first and second dichroic mirrors 13 and 14 color-separate the light reflected by the reflective mirror 12 to reflect red and blue components, respectively.

The first, second, and third optical path controllers 20, 30, and 40 reflect mirrors 26 to reflect light paths corresponding to the pixels incident from the first, second, and second dichroic mirrors 13, 14. 36, 46 and actuators 24, 34, 44, which allow the mirrors 26, 36, 46 to have a predetermined path, are composed of actuator array panels 22, 32, 42 mounted with M × N pieces. . The actuator array panels 22, 32, and 42 have M × N transistors (not shown), and the actuators 24, 34, and 44 may be electrically connected to the transistors. 32, 42, and are deformed by an electric field generated by an image signal to incline the mirrors 26, 36, 46 mounted thereon.

The light reflected from the first, second, and third optical path controllers 20, 30, 40 reaches the projection stop 15.

The projection lens 16 is adjusted to the amount of light by the first, second, and third optical path controllers 20, 30, 40 and projects the light incident through the projection stop 15 toward the screen 17. .

In general, projectors are classified into front or rear projection TVs according to the position of the light source. Since the projector implements a large screen, many people can simultaneously watch TV in a large place.

The dichroic mirror constituting the optical system of the projection image display device exhibits characteristics according to an angle designed at its manufacture, that is, if the incident light is different from the angle designed at the manufacture, the characteristic wavelength band varies according to the degree and is separated or synthesized. The color will be different.

In general, the effective angle of dichroic mirrors is about + 14 ° for 0 °, + 4 ° for 45 °, and it is an area where the eye does not make a big difference. Will bring.

As shown in FIG. 1, the light emitted from the light source 11 is reflected by the reflecting mirror 12 and passes through the first and second dichroic mirrors 13 and 14, the first and second dikes Since the angles of the light incident from the lower mirrors 13 and 14 are different in the center, the top, and the bottom, respectively, the angles of the light may be different depending on the positions of the optical path control elements 20, 30, and 40 using the AMA. do. As a result, the color on the screen 17 is clear at the center and opaque at the top and bottom. If such a state is expressed by spectrum, the shift phenomenon of the spectrum can be observed as shown in FIG. That is, (a) shows the state shifted to the right, (b) shows the steady state, and (c) shows the state shifted to the left.

The present invention has been made to solve the problems in the optical system of the conventional projection-type image display device as described above, by changing the manufacturing characteristics of the mirror so that the light emitted from the light source is not affected by the tilt angle of the mirror, the screen It is an object of the present invention to provide an optical system of a projection image display device capable of eliminating color opacity.

In order to achieve the above object, the optical system of the projection image display apparatus includes a light source for emitting white light having high brightness, a reflection mirror for reflecting light emitted from the light source, and a part of light reflected from the reflection mirror. A third dichroic mirror for reflecting and transmitting a portion, a fourth dichroic mirror for transmitting a portion of the light transmitted from the third dichroic mirror and reflecting a portion thereof, and A first optical path adjuster positioned on a reflective surface to adjust an optical path to correspond to a pixel according to a predetermined signal, and an optical path positioned on a reflective surface and a transmissive surface of the fourth dichroic mirror to correspond to a pixel according to a predetermined signal; A second and third optical path controllers for adjusting and a projection stop for transmitting light by being located in the optical path of the optical path from which the optical paths are controlled from the first, second and third optical path controllers And a projection lens configured to project light incident from the first, second, and third optical path controllers onto the screen, wherein the third dichroic mirror is configured to display a green component in incident white light. And reflecting and transmitting the red and blue components, and the fourth dichroic mirror has a cutting area for reflecting only the blue component of the color components transmitted from the third dichroic mirror. An optical system of is provided.

The fourth dichroic mirror may be manufactured to have a cutting area for reflecting only a red component.

Hereinafter, an optical system of a projection image display device according to the present invention will be described in detail with reference to the accompanying drawings.

3 is a schematic view showing an optical system of a projection image display device according to the present invention, wherein the same reference numerals are used for the same parts as the conventional drawings. As shown therein, the white light emitted from the light source 11 is reflected by the reflecting mirror 12 so that the green component is reflected by the third dichroic mirror 52 and the blue and red components are transmitted. In this case, the light spectrum is as shown in FIG.

The third dichroic mirror 52 is manufactured and installed such that the characteristic angle α is 20 ° or less with respect to the normal of the mirror 52 in order to reduce the nonuniformity of the color generated when light is transmitted or reflected. .

The fourth dichroic mirror 54 used next to the third dichroic mirror 52 may be formed of the light transmitted by the third dichroic mirror 52, as shown in FIG. The center of the spectrum is cut and manufactured, i.e., even if the transmission characteristic of light passing through the fourth dichroic mirror 54 is shifted, the third dichroic mirror ( 52), the green component is removed and is not affected by the shift. In general, in the light spectrum, the red component appears at about 490 nm, and the blue component appears at about 580 nm, with about 100 nm being the green component region. However, in the present invention, since the green component is reflected by the third dichroic mirror 52 and only the red and blue components are transmitted, in the middle portion of the spectrum of the light reaching the fourth dichroic mirror 54. Since there was no color component, the fourth dichroic mirror 54 had a blue component at about 580 nm to 600 nm if the fourth dichroic mirror 54 had the same spectrum as the dotted line (a) of FIG. Therefore, only the red component can be reflected, and when the spectrum (shown by a dashed line) as shown in (b) is formed, the red component appears at about 490 nm to 510 nm, so the red component is transmitted and only the blue component can be reflected. The mirror is constructed. In the figure, hatched areas indicate light transmission areas. That is, the red component is reflected or transmitted by the arrangement of the dichroic mirror 54. Therefore, when the fourth dichroic mirror 54 is manufactured and installed to have the cutting area as shown in FIGS. 5A and 5B, the shift is not affected by the shift in a certain area (about 100 nm). Color nonuniformity does not occur.

As described and shown in the above embodiment, according to the optical system of the projection image display device, the effect of eliminating color unevenness in the optical system of the projection image display device by changing the manufacturing characteristics of the dichroic mirror. There is.

Claims (2)

A light source 11 emitting high brightness white light, a reflection mirror 12 reflecting light emitted from the light source 11, and a part of the light reflected from the reflection mirror 12 to reflect and transmit a part of the light. A third dichroic mirror 52, a fourth dichroic mirror 54 that transmits and reflects a part of light transmitted from the third dichroic mirror 52, and the third dichro A first optical path adjuster 20 positioned on a reflecting surface of the mirror 52 to adjust an optical path to correspond to a pixel according to a predetermined signal, and a reflecting surface and a transmitting surface of the fourth dichroic mirror 54, respectively. Second and third optical path controllers 30 and 40 positioned to adjust the optical paths to correspond to the pixels according to a predetermined signal, and optical paths of the optical paths adjusted from the first and second optical path controllers 20, 30 and 40; A projection stop 15 which transmits light and is located in the first and second optical path controllers 20 and 30; A projection image display device comprising a projection lens 16 for projecting incident light by adjusting an optical path from the reference point 40 to the screen 17, wherein the third dichroic mirror 52 has a green component in incident white light. And the red and blue components are transmitted, and the fourth dichroic mirror 54 is manufactured to have a cutting area for reflecting only the blue component of the color components transmitted by the third dichroic mirror 52. An optical system of a projection image display device. The optical system of a projection image display device according to claim 1, wherein said fourth dichroic mirror (54) has a cutting area for reflecting only a red component.