KR20030020721A - optic system of projector - Google Patents

Abstract

PURPOSE: An optimal system of a projector is provided to realize clear images by removing the non-polarized light included in the polarized light via a polarizer. CONSTITUTION: An optical system of a projector comprises first and second light sources(301,304), first and second condensing lenses(302,305) condensing the non-polarized light emitted from the first and second light sources, a first mirror(303) reflecting the light condensed in the first condensing lens, a second mirror(306) reflecting the light condensed in the second condensing lens, a third condensing lens(307) condensing the light reflected from the first and second mirrors again, and a PBS array(308) polarizing the condensed light.

Description

Optical system of projector

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to projections and projectors, and more particularly to an optical system capable of compact construction using two light sources.

As satellite and digital broadcasting have been promoted in recent years, as demand and interest for large screen displays having high resolution have increased, expectations and roles for projection and projectors have increased.

At the same time, the demand for high brightness and high definition image information has become stronger, and researches on new optical systems having high light utilization efficiency are being conducted in various ways.

At this time, the projection method can be largely divided into a transmissive type and a reflective type, but in recent years, a lot of technical developments regarding the reflective type have been progressed in order to secure aperture ratio and price competitiveness while pursuing high resolution.

1 is a basic optical system of a three-plate reflective projection system using a conventional light source and three reflective liquid crystal panels.

Referring to FIG. 1, light emitted from a light source 101 such as a lamp is separated by mirrors 104, 105, and 108 and divided into R, G, and B wavelengths, and then each polarized beam splitter corresponding to R, G, and B. Incident to (PBS) 106,109, 111 and divided into S-polarized light and P-polarized light. Among these lights, a specific polarized light (here, S-polarized light is used) is incident on the liquid crystal panels 107, 110, and 112, and has a structure capable of realizing an image with light reflected back.

That is, the non-polarized white light from one light source 101 is converted into S-polarized light through both condensinglens 102 and PBS array 103, and then has a first dichroic mirror having wavelength selectivity. mirror 104). The first dichroic mirror 104 reflects red light and transmits cyan light. The red light reflected by the first dichroic mirror 104 is reflected by the mirror 105 to be incident to the PBS 106. The PBS 106 separates the incident red light into S-polarized light and P-polarized light. At this time, the S-polarized red light is reflected by the PBS 106 again and enters the first reflective liquid crystal panel 107 having the red image information. The red light reflected by the liquid crystal panel 107 is incident to the PBS 106 again, and the P-polarized red light of the incident light passes through the PBS 106 and exits to the recombiner 113.

On the other hand, the cyan light transmitted through the first dichroic mirror 104 is separated into green and blue via the second dichroic mirror 108, and each of the second and third reflections in the same process as the red light. It enters the type liquid crystal panels 110 and 112. Light modulated through each liquid crystal panel 107, 110, 112 and each PBS 106, 109, 111 is finally combined with three colors by a recombiner 113, and then projected onto a screen through a projection lens. do.

When configuring the optical system of the projection system as described above, in general, one light source and three liquid crystal panels are used as shown in FIG. 1, in which case, red, green, blue (red) Since the three colors must be separated and re-synthesized to produce full color, in terms of light utilization efficiency, there is a limit to expressing bright and clear images on the final screen. In addition, by using a large number of PBSs and dichroic films, the optical system is complicated and it is difficult to miniaturize the device. That is, since the brightness and clarity of the image seen on the final screen are inferior, and the configuration of the device is complicated, it is difficult to achieve a compact configuration.

FIG. 2 illustrates an optical system having a compact configuration of only one PBS and a dichroic prism.

That is, referring to FIG. 2, unpolarized white light from one light source 201 is converted into S-polarized light through the condensing lens 202 and the PBS array 203 and then enters the PBS 204. At this time, the S-polarized light is reflected by the PBS 204 and incident on the dichroic prism 208, separated by each of the R, G, B by the dichroic prism 208, each of the red Incident on the green, blue, and blue liquid crystal panels 205-207.

The P-polarized R, G, and B lights modulated by the liquid crystal panels 205 to 207 according to whether the red, green, and blue liquid crystal panels 205 to 207 are applied with voltage are again converted into the dichroic prism 208. After recombination, it enters PBS 204. In this case, the P-polarized light passes through the PBS 204 and is incident to the projection lens 209. On the other hand, S polarized light of the light reflected from each of the liquid crystal panels 205 to 207 is reflected back to the light source 201 by 90 degrees reflected by the PBS (204).

However, such a structure is also possible in a compact configuration, but likewise uses a single light source, there is a limit in realizing high brightness and high definition images in the final screen.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an optical system of a projector having a high light utilization efficiency and a compact configuration by using two light sources and disposing a polarizer at the final output stage. have.

1 is a configuration diagram showing an example of an optical system of a typical projector

2 is a configuration diagram showing another example of an optical system of a conventional projector

3 is a configuration diagram showing an example of an optical system of a projector according to the present invention;

4 is a configuration diagram showing another example of the optical system of the projector according to the present invention;

Explanation of symbols for main parts of the drawings

301,304,401,405: light source

302,305,308,402,406,409: condensing lens

303,306,404,408: Mirror 308,403,407: PBS array

309,411: PBS310,312,314,412,414,416: Color filter

311,313,315,413,415,417: Liquid Crystal Filter

316,418: Recombiner317,419: Polarizer

318,420: projection lens 410: pre-polarizer

The optical system of the projector according to the present invention for achieving the above object, the first and second light source and the condenser lens for emitting non-polarized light to focus in a predetermined direction, and the first, second light source and the condenser lens A mirror for reflecting the non-polarized light emitted through each of the light, a polarization converting unit for condensing the light reflected from the mirror and polarizing it with a specific wave, and a PBS reflecting or transmitting the light emitted through the polarization converting unit according to the polarization direction R, G, and B are separated into the respective colors of R, G, and B, and emitted to the corresponding R, G, and B liquid crystal panels, and R, G, and B are modulated from the R, G, and B liquid crystal panels. And a recombiner for recombining the light and exiting the PBS, and a projection lens for receiving and diffusing the light emitted through the PBS.

Preferably, a polarizer for removing the non-polarization component included in the light emitted from the PBS and exiting the projection lens is further disposed between the PBS and the projection lens.

A PBS array for polarizing unpolarized light with a specific wave may be further disposed between the first and second light sources and the condenser lens and the mirror.

In this case, the polarization converter is a pre-polarizer for removing the non-polarization components included in the polarized light emitted from the PBS array.

Preferably, a color filter is further disposed between the recombiner and the R, G, and B liquid crystal panels.

Other objects, features and advantages of the present invention will become apparent from the following detailed description of embodiments taken in conjunction with the accompanying drawings.

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

3 is a view showing an optical system configuration of a projector according to the present invention, in which non-polarized light emitted from first and second light sources 301 and 304 and first and second light sources 301 and 304 respectively emit unpolarized light. First and second condensing lenses 302 and 305 for condensing light, a first mirror 303 for reflecting light condensed by the first condensing lens 302, and light condensed by the second condensing lens 305. And a second mirror 306 for reflecting. In addition, a third condensing lens 307 for condensing the light reflected from the first and second mirrors 303 and 306 and a PBS array 308 for polarizing the condensed light in one direction are provided in the first and the second. 2 are sequentially arranged on the optical path of the mirrors 303 and 306. In addition, light emitted from the PBS array 308 is incident to the PBS 309, and the PBS 309 is disposed between the recombiner 316 and the polarizer 317.

The polarizer 317 is disposed to remove unpolarized light included in the light emitted from the PBS 318, and the light emitted through the polarizer 317 is projected onto the screen through the projection lens 318. .

In addition, the recombiner 316 separates the light incident through the PBS 309 into the respective colors of R, G, and B, and emits the light to the red, green, and blue liquid crystal panels 311, 313, and 315, respectively. It is made of a dichroic prism to recombine R, G, and B light reflected from the blue liquid crystal panels 311, 313, and 315. Further, color filters 310, 312, and 314 are additionally disposed between the red, green, and blue liquid crystal panels 311, 313, 315 and the recombiner 316 to improve color purity.

In the present invention configured as described above, the unpolarized light emitted from the first light source 301 is emitted to the condensing lens 302, and the unpolarized light emitted from the second light source 304 is emitted to the condensing lens 305. do. The condensing lenses 302 and 305 advance the light emitted from the first and second light sources 301 and 304 in a predetermined direction, that is, in the directions of the first and second mirrors 303 and 306, respectively.

The first and second mirrors 303 and 306 totally reflect incident light to the condenser lens 307. The condenser lens 307 advances the incident light in parallel in a predetermined direction, that is, in the direction of the PBS array 308.

The PBS array 308 converts non-polarized light incident in parallel and converted into light polarized in one direction (eg, S-polarized light) to be incident to the PBS 309.

The PBS 309 reflects S-polarized light and transmits P-polarized light, or conversely, S-polarized light is transmitted and P-polarized light is reflected. And assume that the P-polarized light is designed to transmit.

Thus, the PBS 309 reflects the S-polarized light incident from the PBS array 308 to the recombiner 316. At this time, the light incident by the recombiner 316 is separated into the respective colors of R, G, and B, and then incident to each of the red, green, and blue liquid crystal panels 311, 313, and 315.

Then, the P-polarized R, G, and B light modulated by each of the liquid crystal panels 311, 313, and 315 are recombined by the recombiner 316 according to whether the red, green, and blue liquid crystal panels 311, 313, and 315 are applied with voltage. Then enters PBS 309. At this time, the P-polarized light is transmitted through the PBS 309 and is incident to the polarizer 317, and if there is an S-polarized light, the P-polarized light is reflected by the PBS 309 again and fed back to the first and second light sources 301 and 304. . In this case, when the color filters 310, 312, 314 are disposed between the recombiner 316 and the red, green, and blue liquid crystal panels 311, 313, and 315, color purity may be improved. In this case, a more improved high definition image may be obtained.

On the other hand, the polarizer 317 removes the non-polarization component that is partly mixed with the output light of the PBS 309 and exits to the projection lens 318. The projection lens 318 projects the light having high brightness and high definition image information on the final screen by the polarizer 317.

4 illustrates a PBS array 403 and 407 between the first condenser lens 402 and the first mirror 404 and between the second condenser lens 406 and the second mirror 408 as another embodiment of the present invention. ), And a prepolarizer 410 is disposed between the condenser lens 309 and the PBS 411. That is, the non-polarized light emitted from the first and second light sources 401 and 405 is collected by the first and second condensing lenses 402 and 406, and converted into S-polarized light in each of the PBS arrays 403 and 407. The first and second mirrors 404 and 408 and the condenser lens 409 are incident to the pre-polarizer 410. In this case, since the polarization conversion efficiency of the PBS arrays 403 and 407 is not 100% perfect, only the S-polarized light is transmitted by the pre-polarizer 410, thereby further increasing the contrast ratio.

As described above, according to the optical system of the projector according to the present invention, by minimizing the loss of light by using two light sources in the three-plate liquid crystal panel structure, it is possible to improve the light utilization efficiency and brightness, thereby realizing high brightness and high definition image Can be realized. In addition, by using only one expensive PBS and using universal optical components, it is possible to reduce the price of the device and to configure a compact optical system, thereby enabling application to a portable projector. In addition, a color filter may be disposed on each liquid crystal panel to improve color purity, and a polarizer may be disposed at the final output terminal to remove non-polarization components included in the polarized light, thereby realizing a clearer image.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the spirit of the present invention.

Therefore, the technical scope of the present invention should not be limited to the contents described in the embodiments, but should be defined by the claims.

Claims (6)

In the optical system of the projector having a three-plate liquid crystal panel structure, First and second light sources and a condenser lens that emit unpolarized light and condense in a predetermined direction; A mirror for reflecting unpolarized light emitted through the first and second light sources and the condenser lens, respectively; A polarization converting unit which collects light reflected from the mirror and polarizes it with a specific wave; PBS for reflecting or transmitting the light emitted through the polarization converting unit according to the polarization direction; The light reflected from the PBS is separated into respective colors of R, G, and B, and emitted to the corresponding R, G, and B liquid crystal panels, and the R, G, and B light emitted from the R, G, and B liquid crystal panels are respectively modulated. A recombiner recombined and exited to the PBS; And And a projection lens configured to receive and diffuse light emitted through the PBS. The method of claim 1, And a polarizer which removes the non-polarization component included in the light emitted from the PBS and exits to the projection lens, is further disposed between the PBS and the projection lens. The method of claim 1, And a PBS array further disposed between the first and second light sources and the condenser lens and the mirror to polarize unpolarized light with a specific wave. The method of claim 3, wherein the polarization converter And a pre-polarizer for removing non-polarization components included in the polarized light emitted from the PBS array. The method of claim 1, And said recombiner is comprised of a dichroic prism. The method of claim 1, And a color filter further disposed between the recombiner and the R, G, and B liquid crystal panels.