KR0148156B1 - Lcd projector with 2panel - Google Patents

Abstract

The present invention relates to a two-panel liquid crystal projector using a luminance signal liquid crystal panel and a color signal liquid crystal panel, respectively, wherein the amount of light incident on the liquid crystal panels is changed by using an optical separation device for dividing the light at a predetermined ratio. By doing so, it is possible to prevent the inconsistency of the black and white image and the color image to obtain a high resolution and improved brightness image.

Description

2-panel liquid crystal projector

1 is an optical configuration of a conventional two-panel liquid crystal projector,

2A is a structural diagram of a luminance signal liquid crystal panel used in a two panel liquid crystal projector;

3 is an optical diagram of a two-panel liquid crystal projector according to the present invention.

* Explanation of symbols for main parts of the drawings

1,11: Lamp 2,12: Hot mirror

3,8,18 polarization filter 4,6,14,16 mirror

5,15: luminance signal liquid crystal panel 7,17: color signal liquid crystal panel

9,19: projection lens 13: optical separation element

The present invention relates to a projector using a luminance signal liquid crystal panel and a color signal liquid crystal panel, respectively, and in detail, a black and white image and a color image due to a difference in light efficiency by varying the amount of light incident on the liquid crystal panels. The present invention relates to a two-panel liquid crystal projector that prevents mismatches and reproduces an original image.

In general, there is a method of projecting an image using a liquid crystal panel according to the number of use of the liquid crystal panel, there are 1 panel method, 2 panel type and 3 panel method, but the 1 panel method is small at low cost due to the small number of components While it can be easily assembled in size, the liquid crystal panel used has three (R, G, B) subpixels, so the resolution and light efficiency are low (about 3.06%).

In addition, the three-panel method improves image quality and light efficiency by using three dedicated liquid crystal panels according to color signals (approximately 4.23%), so that a relatively bright image can be obtained. Increasing the number of panels, manufacturing costs were expensive.

A two-panel method has been proposed, which is to compensate for the shortcomings of the above-described one- and three-panel methods.

1 is an optical configuration diagram of a conventional two-panel liquid crystal projector, and includes a liquid crystal panel 5 and a liquid crystal panel 7 for a luminance signal. In FIG. 1, the polarization filter 3 reflects the S-polarized component and the P-polarized component through the visible light passing through the hot mirror 2 at the same ratio, so that the luminance signal liquid crystal panel 5 and the color signal liquid crystal panel ( 7) to be incident. When light passing through the polarization filter 3 is incident on the liquid crystal panel to which an image signal is applied, the S-polarized component is converted into a black-and-white image and the P-polarized component is converted to a color image by electrical and optical conversion. When the black and white image and the color image are transmitted and reflected by the polarization filter 8 and input to the projection lens 9, the projection lens 9 enlarges and projects the black and white image and the color image on the screen.

Here, looking at the structure of the liquid crystal panel used in the two-panel method, (a) of Figure 2 is a structural diagram of the liquid crystal panel for the luminance signal, (b) is a structural diagram of the liquid crystal panel for the color signal.

As shown in the drawing, the pixel structure of the liquid crystal panel has a delta pixel array in which the even rows and odd rows are deviated by 1/2 pixel. In particular, in the liquid crystal panel for color signal shown in (b) of FIG. 2, since three subpixels of R, G, and B are staggered, resolution in the horizontal direction is reduced, resulting in inconsistency of the black and white image and the color image.

Such a two-panel method has a relatively high resolution and has a high light efficiency (about 7.34%) compared to the one-panel and three-panel methods, thereby obtaining a bright screen. However, since the two-panel method compensates for the resolution and brightness of the color signal liquid crystal panel in the luminance signal liquid crystal panel, the processing of the luminance signal and the color signal is overlapped. . In addition, the color purity is lowered due to the luminance signal, so that a vivid color cannot be obtained. Due to manufacturing difficulties, the polarizing filter 3 is expensive and the overall manufacturing cost increases.

The present invention is to solve the above problems, an object of the present invention by using an optical separation element by reducing the amount of light incident on the liquid crystal panel for the luminance signal and the liquid crystal panel for the color signal at an appropriate ratio by the high resolution and brightness It is to provide a two-panel liquid crystal projector that can obtain an improved image.

In order to achieve the above object, the two-panel liquid crystal projector of the present invention has an optical splitting device that measures the amount of light incident on each liquid crystal panel so as to prevent inconsistency between the black and white and color images produced by the liquid crystal panels. This is achieved by dividing by an appropriate ratio.

Hereinafter, a preferred example of the present invention will be described with reference to the accompanying drawings.

3 is an optical diagram of a two-panel liquid crystal projector according to the present invention. The two-panel liquid crystal projector of the present invention includes an optical separation element (13). At the front end of the optical separation element 13 is connected a hot mirror 12 which transmits only visible light from the light emitted from the lamp 11. The optical splitter 13 splits incident light by reflecting some of the visible light transmitted through the hot mirror 12 and transmitting the remaining light. In this case, the ratio of splitting the light by the optical separation element 13 is selected in consideration of the light transmittance of the liquid crystal panel 15 for the luminance signal and the liquid crystal panel 17 for the color signal. That is, assuming that the same amount of light is incident on the liquid crystal panel, the liquid crystal panel for color signals composed of a combination of three subpixels R, G, and B, compared to the brightness of the monochrome image produced by the luminance signal liquid crystal panel 15 ( Since the brightness of the color image produced in 17) is reduced to about one third, the splitting ratio is determined so that the optical separation element 13 transmits three times more than the reflection amount. This is expressed as a formula as follows.

Here, L _y is the light reflectance of the optical separation device, L _c is the light transmittance of the optical separation device. In Equation (1), a means a proportional constant and is set to 1/3 in the embodiment of the present invention. The proportionality constant (a) is determined by the transmittance of the liquid crystal panel, and is generalized as follows.

Here, T _c is the light transmittance of the liquid crystal panel for color signals, and T _y is the light transmittance of the liquid crystal panel for luminance signals.

Therefore, if the separation ratio of the optical separation element 13 is properly set based on Equations (1) and (2), it is possible to fundamentally prevent the inconsistency of the black and white image and the color image caused by the physical characteristics of the liquid crystal panel. Can be.

Again, the light divided by the optical separation element 13 in FIG. 3 is incident on the mirrors 14 and 16, respectively, to change the traveling direction. When the light reflected by the optical separation element 13 is incident, the mirror 14 is totally reflected so that the mirror 14 is incident on the liquid crystal panel 15 for the luminance signal. When light is incident on the front surface of the luminance signal liquid crystal panel 15, a black and white image is formed on the rear surface through the liquid crystal panel 15 to which the luminance signal is being applied.

On the other hand, the mirror 16 is totally reflected to the liquid crystal panel 17 for the color signal when the light transmitted through the optical separation element 13 is incident. When light is incident on the front side of the color signal liquid crystal panel 17 while the color signal is being applied, a color image is made on the rear side. Since the amount of light incident on the front side of the luminance signal liquid crystal panel 15 is three times greater, The produced monochrome image and color image have the same level. The black and white image and the color image are transmitted and reflected by the polarization filter 18 to be incident on the projection lens 19. The projection lens 19 enlarges the black and white image and the color image on the screen to form a composite image.

As described above, the present invention can not only implement a two-panel liquid crystal projector that can obtain an image having high resolution and improved brightness by using an optical splitter that splits light at a predetermined ratio, but also properly adjust the amount of light incident on the liquid crystal panel. By adjusting, there is an excellent effect that can prevent the phenomenon that the image floats due to the inconsistency of the black and white image and the color image.

Claims (3)

A panel type liquid crystal projector that separates and transmits light emitted from a light source to a plurality of liquid crystal panels, and synthesizes an image obtained from each panel to form an image. The two-panel liquid crystal projector characterized in that the optical separation element that reflects and transmits at an appropriate ratio according to the transmission characteristics of each panel determines the reflection and transmission ratio by the following equation. The two-panel liquid crystal projector according to claim 1, wherein the optical separation element determines the reflection and transmission ratio by the following equation. Here, Ly is the light reflectance of the optical splitter, L _C is the light transmittance of the optical separation element, a is a proportionality constant. The two-panel liquid crystal projector according to claim 2, wherein the proportionality constant (a) is determined by the following equation. Where T _C is the light transmittance of the liquid crystal panel for color signals, T _y is the light transmittance of the liquid crystal panel for luminance signals.