KR19990000323A - LCD projector optical system - Google Patents

Abstract

1. TECHNICAL FIELD OF THE INVENTION

LCD projector

2. Technical problem to be solved of the invention

The present invention is to separate the light incident on the polarizer in advance to transmit the unused light to the outside of the optical system and to reflect the light used to be incident to the R, G, B LCD panel.

3. Summary of the Invention Solution

According to the present invention, the P-wave of incident light irradiated by the light irradiating part 100 transmits the P-wave and emits it to the outside, and the S-wave reflects 90 degrees into the optical system to form a predetermined optical path, and the polarization splitting means. Light conversion polarizing means (2) for converting the polarization planes of R, B, and G separated by (1) to convert S waves into P waves is provided.

4. Important uses of the invention

LCD projector optical system

Description

LCD projector optical system

TECHNICAL FIELD The present invention relates to an LCD projector, and more particularly, to a three-panel LCD projector suitable for separating and synthesizing light into R (red), G (green), and B (blue), respectively.

LCD projectors are generally used for presentations in conference rooms, projectors in small theaters, and large-scale CRTs at home.

The configuration of the LCD projector is, as shown in Figure 1, by removing the ultraviolet light and hot light from the generated light focused on the front irradiation unit 100, and focused and incident by the light irradiation unit 100 An optical separation unit 200 separating the light into R (red), G (green), and B (blue), and images of R, G, and B separated by the optical separation unit 200, respectively, An image combining unit 300 for synthesizing the separated images into one image, and an image forming unit 400 for projecting the image synthesized as one by the image combining unit 300 onto the screen S, If you look at this in more detail:

The light irradiator 100 includes a rearview mirror 120 that reflects light emitted from the rear of the lamp 110 in one direction, and a heat absorption mirror that removes hot light of the light emitted from the lamp 110 and the rearview mirror 120. 130, the UV blocking mirror 140 which blocks the ultraviolet rays of the light from which the heat is removed from the heat absorption mirror 130, and the ultraviolet rays removed by the UV blocking mirror 140 are uniformly irradiated as a whole. First and second integrators 150 and 151 and the first total mirror 160 reflecting the light focused by the first and second integrators 150 and 151 in a predetermined optical path. It is composed of

In addition, the optical separation unit 200 is a R, B transmission dichroic lens 210, 220 for selectively transmitting R and B in the light incident from the light irradiation unit 100, respectively, and the B transmission type dike The second and third total reflection mirrors 230 and 240 disposed to face each other so as to change the optical path of B transmitted through the loch lens 220 by 180 degrees, and the R transmission dichroic lens 210 are transmitted. The fourth total reflection mirror 250 reflects one R upward.

In addition, the image synthesizing unit 300 collects the first, second and third condensing lenses 310, 311, and 312 to focus and irradiate each of R, G, and B separated by the optical separation unit 200. R, G, and B LCD panels 320, 321, and 322 which form images of R, G, and B focused by the first, second, and third condenser lenses 310, 311, and 312 respectively. ), And the dichroic prism 330 for synthesizing each image formed by the R, G, and B LCD panels 320, 321, and 322 into a single image. The LCD panels 320, 321, and 322 have polarizers 320b, 321b, and 322b in front of the liquid crystal cells 320a, 321a, and 322a in a twisted nematic (TN) manner, and an analyzer in the rear. 320c, 321c, and 322c are combined with each other.

In addition, the imaging unit 400 includes a projection lens 410 for enlarging and projecting the incident image synthesized into one image by the dichroic prism 330 onto the screen S.

In the conventional LCD projector configured as described above, light emitted from the lamp 110 and irradiated and reflected forward is blocked by heat and ultraviolet rays through the heat absorption mirror 130 and the UV blocking mirror 140, Subsequently, the first and second integrators 150 and 151 pass through the first and second integrators 150 and 151 through the reflection of the first total reflection mirror 160 to uniformly illuminate the entire body.

As described above, the R, G, and B components are included in the white light uniformly focused forward through the first and second integrators 150 and 151. The R transmits the dichroic lens 210. After transmission, the light is reflected by the fourth total reflection mirror 250 and is sent to the R LCD panel 330. G and components are reflected upward from the R-transmissive dichroic lens 210 and then again transmitted through the B-transmissive dichroic. Reflected in one direction from the lens 220 is sent to the G LCD panel 331, the B component is reflected upward from the R dichroic lens 210 and passes through the B transmission dichroic lens 220, Subsequently, the second and third total reflection mirrors 230 and 240 disposed to face each other are double reflected and sent to the B LCD panel 332.

As described above, R among R, G, and B incident on the R, G, and B LCD panels 320, 321, and 322, respectively, is polarized only in one direction while passing through the polarizer 320b, and thus, the liquid crystal cell 320a. Incident). At this time, when the incident light is incident on the analyzer 320c along the molecules of the twisted liquid crystal cell 320a, the polarization plane is changed by 90 degrees. Therefore, when the analyzer 320c is deviated 90 degrees with respect to the polarizer 320b, it will appear bright through this analyzer 320c, and conversely, the predetermined transparent conductive film (not shown) provided in the upper and lower surfaces of the liquid crystal cell 320a may be provided. When a predetermined voltage is applied, the molecules of the liquid crystal cell 320a are not aligned due to the action of an electric field and the torsion of the upper and lower 90 degrees is eliminated, so that they do not pass through the analyzer 320c and become dark, thereby forming an image by a combination thereof. Similarly, G and B also form images on the G and B LCD panels 321 and 322, respectively.

Therefore, the R, G, B LCD panels 320, 321, 322 are incident on each of the R, G, B LCD panels 320, 321, 322. Images are respectively formed, and the images thus formed are color synthesized by the dichroic prism 330, and then are incident on the projection lens 410 and then imaged on the screen S. FIG. At this time, the operation of color synthesis is performed as follows.

The dichroic prism 330 has A and B surfaces, and both surfaces of the dichroic prism 330 are subjected to dichroic coating to reflect only the R surface and the B surface. As a result, R passing through the R LCD panel 320 is transmitted through the B surface, reflected from the A surface, and is incident to the projection lens 410, and B passing through the B LCD panel 322 is transmitted through the A surface and B The surface is reflected and is incident on the projection lens 410, and G passing through the G LCD panel 321 passes through all surfaces A and B and is incident on the projection lens 410, so that all color components of R, G, and B are dichroic. The light synthesized by the prism 330 is incident on the projection lens 410 and then imaged on the screen S.

By the way, the light incident on the R, G, B LCD panel, especially the wavelength (λ) is shorter than other color light (G: 490-550 nm, R: 640-780 nm), and the energy B (about 430-490 nm) is high. There was a problem that the polarizer is damaged by the light absorbed by the polarized light passing through the polarizer.

In order to solve the above problems, in recent years, a separate protective polarizer (not shown) having high durability and relatively high transmittance is provided between each of the R, G and B LCD panels and the first, second and third collecting lenses. There is an advantage that can prevent the damage of the polarizer due to the absorbed wave, but by using a separate protective polarizer additionally not only causes a loss of light amount, but also to cool the heat generated during polarization By using a cooling fan (not shown) there was a problem that the noise generation and the structure is complicated.

Accordingly, the present invention has been made in view of the above-mentioned conventional defects, and its object is to separate the light incident on the polarizer in advance, and to transmit the unused light to the outside of the optical system and to reflect the light used to reflect the R, It is to provide an optical system of the LCD projector to be incident on the G, B LCD panel.

The optical system of the LCD projector separates the R and B polarization beam mirrors to separate incident light, transmits P waves and reflects S waves in one direction, and changes the polarization plane of the light incident through the R and B polarization beam mirrors by 90 degrees. It is characterized by constituting a 1/2 polarized wave plate converting the P wave.

1 is a block diagram showing an optical path of a typical LCD projector.

Figure 2 is a block diagram showing an optical path of the LCD projector to which the present invention is applied.

Figure 3 is a performance graph according to the wavelength of the present invention R, B polarizing beam mirror.

Explanation of symbols on the main parts of the drawings

1: polarization separation means 2: light conversion polarization means

10,11: R, B polarized beam mirror 20a, 20b, 20c: 1/2 polarized wave plate

100: light irradiation unit 200: light separation unit

210,220: R, B dichroic lens 230,240,250: 2nd, 3rd, 4th total reflection mirror

300: image synthesis unit 310,311,312: first, second, third condenser lens

320, 321, 222: R, G, B LCD panel 330: Dichroic prism

400: imaging part

Hereinafter, the structure of the present invention will be described in detail with reference to the accompanying drawings. Figure 2 is a block diagram showing the optical path of the LCD projector to which the present invention is applied, Figure 3 is a performance graph according to the wavelength (λ) of the R, B polarizing beam mirror of the present invention.

The LCD projector to which the present invention is applied includes a light irradiation unit 100 which removes ultraviolet rays and heat rays from the generated light and focuses it forward to irradiate it, and R (red) in the light focused and incident by the light irradiation unit 100. The optical separation unit 200 which separates G (green) and B (blue) and the R, G, and B images separated by the optical separation unit 200 are formed, respectively, and each separated image is formed. The optical separation unit 200 includes an image synthesizing unit 300 for synthesizing a single image and an image forming unit 400 for projecting an image synthesized as one by the image synthesizing unit 300 onto the screen S. ) Transmits the R and B transmissive dichroic lenses 210 and 220 and the B transmissive dichroic lens 220 to selectively transmit R and B respectively from the light incident from the light irradiator 100. Second and third total reflection mirrors 230 and 240 disposed to face each other so as to change a light path of a B by 180 degrees; and the R-transmissive dike And a fourth total reflection mirror 250 reflecting upwardly the R passing through the blade lens 210, wherein the image synthesizing unit 300 is each R, G, separated by the optical separation unit 200. R, G focused by the first, second and third condensing lenses 310, 311 and 312 that focus and irradiate B, and the first, second and third condensing lenses 310, 311 and 312 R, G, and B LCD panels 320, 321 and 322, which form respective images of B, and the respective images formed by the R, G, and B LCD panels 320, 321, and 322. It consists of the dichroic prism 330 which synthesize | combines into one image.

In the LCD projector, the present invention provides polarization separation means for forming a predetermined optical path by transmitting the P wave of incident light irradiated by the light irradiating part 100 to the outside and reflecting the S wave 90 degrees into the optical system (1). ), And a light conversion polarization means 2 for converting S, P waves into P waves by converting the polarization planes of R, B, and G separated by the polarization separation means 1. Same as

The polarization splitting means (1) is an R, B polarized beam mirror (MgF2) and jet N.S (ZnS: flash light) coated with 17 layers on a glass substrate having a refractive index of 1.674 ( 10) 11 is provided.

In addition, the light conversion polarizing means (2) is a half polarization wavelength plate (20a) (20b) (20c) for converting each of the S, R, B and G waves separated by the polarization separation means (1) into P waves ), The 1/2 polarization wavelength plates 20a, 20b, and 20c are combined with a predetermined 1/2 wavelength plate and the polarizers 320a, 320b, and 320c, respectively.

(Example)

Glass substrate with a refractive index of 1.674

D (Dispersive index): variance coefficient

Incidence angle = (1) 45.00

Total Stacks = 17

Sum (N * D) = 2912.000000

The following describes the optical path of the present invention configured as described above.

In the LCD projector configured as described above, the light emitted from the lamp 110 and irradiated and reflected forward is blocked by heat and ultraviolet rays through the heat absorption mirror 130 and the UV blocking mirror 140, and then Through the reflection of the first total reflection mirror 160 passes through a series of first and second integrator (150, 151) to uniformly illuminate and focus as a whole.

As described above, R, G, and B components are included in the white light focused forward through the first and second integrators 150 and 151. The R transmit dike is performed in a state where the P wave and the S wave coexist. After passing through the lower lens 210, the P-wave is transmitted and the S-wave is reflected by the R polarization beam mirror 10 to be sent to the first condenser lens 310. At this time, the S wave is changed to the P wave in the 1/2 polarization wavelength plate 20a after passing through the first condensing lens 310, and again passes through the liquid crystal cell 320a and the analyzer 320c and is converted into S wave. Incident on the dichroic prism 330.

In addition, the G is reflected upward from the R-transmissive dichroic lens 210 and then reflected back to the right from the B-transmissive dichroic lens 220 to pass through the second condensing lens 311. At this time, the G is incident on the 1/2 polarization wavelength plate 20b in the state where the P wave and the S wave coexist, so that the S wave is polarized in the 1/2 polarization wavelength plate 20b and the P wave is the liquid crystal cell 321a. Passes through the analyzer 321c and is converted into an S wave, and is incident to the dichroic prism 330.

In addition, the B is reflected upward from the R transmission dichroic lens 210 and then transmitted through the B transmission dichroic lens 220 and reflected to the right side from the second total reflection mirror 230. B reflected from the second total reflection mirror 230 to the right is transmitted through the P-polarized beam mirror 11 while P-wave is reflected by 90 degrees and is sent to the third condensing lens 312. At this time, the S wave is changed to P wave in the 1/2 polarization wavelength plate 20c after passing through the third condensing lens 312, and again passes through the liquid crystal cell 322a and the analyzer 322c and passes through the S wave. Is converted and incident on the dichroic prism 330.

As described above, R, G, and B of the incident S wave are detected by the 1/2 polarization wavelength plates 20a, 20b, 20c and the liquid crystal cells 320a, 320b, 320c. Formed on photons 322a, 322b, and 322c, the image thus formed is color synthesized by the dichroic prism 330, and then output to the screen S through the projection lens 410. Thus, an enlarged image is formed.

In this case, the R and B polarized beam mirrors 10 and 11 coated with a total of 17 layers of M.F.2 (MgF2) and J.S. (ZnS) are coated on a glass substrate having a refractive index of 1.674. As shown in FIG. 4, P waves transmit and S waves reflect.

Therefore, according to the present invention, the unused P waves, which are the causes of damage, are transmitted by using the R and B polarized beam mirrors 10 and 11, and are emitted to the outside of the optical system, and the S waves are reflected by a predetermined optical path to reflect each first, The polarized R, G, and B may be irradiated by the 2,3 condenser lenses 310, 311, and 312.

As described above, the present invention uses R and B polarizing beam mirrors to transmit unused P waves, which are the causes of polarizer damage, and emit them to the outside of the optical system, thereby preventing damage of light polarizers that are weak to light energy or heat. It has the effect of increasing the durability of.

In addition, the present invention does not use a separate auxiliary polarizer not only improves the light utilization efficiency but also has the effect of simplifying the work process by reducing the number of parts.

Claims (4)

Each of the R, G, and B images is formed by the light separation unit 200 that separates the incident light focused in the light irradiation unit 100 into R (red), G (green), and B (blue), In the LCD projector which combines each image into one image in the image synthesizing unit 300 and projects it on the screen S, Polarization splitting means (1) for transmitting P waves of incident light irradiated by the light irradiating part (100) and emitting them to the outside and reflecting S waves 90 degrees into an optical system to form a predetermined optical path; And an optical conversion polarization means (2) for converting the polarization planes of R, B, and G separated by the polarization separation means (1) to convert S waves into P waves. According to claim 1, wherein the polarization separation means (1) R and B polarized beam mirrors 10 and 11 coated with 17 layers of M.G.F. and M.Z.S. (zn) are coated on a glass substrate having a refractive index of 1.674. Optical system of the LCD projector, characterized in that. The light conversion polarization means (2) according to claim 1, The LCD projector, characterized in that the 1/2 polarization wavelength plate (20a, 20b, 20c) for converting the S wave of each of the R, B and G separated by the polarization separation means 1 into P wave Optical system. The method according to claim 3, wherein the 1/2 polarization wavelength plate 20a, 20b, 20c, A predetermined 1/2 wavelength plate and polarizers 320b, 321b and 322b are integrally combined with each other.