KR0141548B1 - L.c.d projector type image display apparatus - Google Patents

Abstract

The present invention relates to an optical system for a liquid crystal projector, and more particularly, to provide a liquid crystal projection type image display device which increases light efficiency by preventing light spread and loss of light by six polarizing plates.

Such an object of the present invention is to separate the light emitted from the light source to have a uniform intensity and a specific spectrum of red, green, blue light emitted and the light emitting means for reflecting the light having a color other than the inside, and the light radiation It can be achieved by constructing an image forming means for forming an image by using red, green, and blue light emitted from the means and projecting it on a screen.

Description

LCD Projection Image Display

1 is a block diagram of a conventional liquid crystal projection type image display apparatus

2 is a configuration diagram of a liquid crystal projection image display device of the present invention.

3 is a block diagram of a transmissive liquid crystal panel and a polarization split prism type combined optical system of the present invention

4 is a block diagram of an optical device using the reflective liquid crystal panel of the present invention.

5 is a schematic diagram of an optical system using an optical fiber bundle according to the present invention

6 is a shape diagram of a cross section of the optical fiber bundle constituting FIG.

7 is a cross-sectional structural view of the microlens side of the optical fiber bundle end constituting FIG.

8 is a schematic view for explaining a polarization control process of the polarization splitting prism constituting FIG.

FIG. 9 is a schematic diagram for explaining a control process of the reflective polarizer of FIG.

* Explanation of symbols for main parts of the drawings

1: light source 2: reflector

3: junction of reflector and resonator 4: resonator

5: Blue transmission filter 6: Red transmission filter

7: Green transmission filter 8: Female thread junction

9: male thread joint 10: optical fiber bundle

10a: optical fiber cover 10b: optical fiber core

11: Micro lens group 12: First lens

13: second lens 14: first polarizing plate

15: transmissive liquid crystal panel 16: second polarizing plate

17: Dichroic Separation Prism 17 ': Color Synthesis Prism

18: projection lens 19: pinhole

20: third lens 21: mirror

22: polarization separation prism 23: screen

24: Reflective liquid crystal panel

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical system for a liquid crystal projector, and more particularly, to provide a liquid crystal projection type image display device which increases light efficiency by preventing light spread and loss of light by six polarizing plates.

1 is a configuration diagram of a liquid crystal projection type image display apparatus, which includes a light source 1, a reflector 2 that reflects light emitted from the light source toward a target screen side, and the light source 1 from the light source 1; The dichroic separation prism 17 which separates the white light reflected and projected by the direct projection or reflector 2 into blue, green, and red light as transmission and reflection, and is reflected with a single monochromatic light transmitted through the dichroic separation prism. A first polarizing plate 14, a transmissive liquid crystal panel 15, a second polarizing plate 16, and the first polarizing plate, a transmissive liquid crystal panel, and a second polarizing plate converting two incident monochromatic light in order of polarization, modulation, and polarization. A color synthesizing prism 17 'for synthesizing images by synthesizing information, and a projection lens 18 for enlarging and projecting an image incident from the color synthesizing prism to be displayed on the screen 23.

In the liquid crystal projection type image display device configured as described above, the image projected on the screen passes through the following path.

In the above configuration, the dichroic separation prism 17 has a characteristic of transmitting any color and reflecting other colors. Here, for the sake of explanation, light transmitted through the dichroic separation prism 17 is red, Assume that the light reflecting is green and blue.

The green and blue light reflected by the dichroic separation prism 17 are converted into paths by the first to fourth reflective mirrors 21a to 21d, respectively, and are incident on the respective transmissive liquid crystal panels 15.

The green and blue light incident on the transmissive liquid crystal panels 15a and 15c are first polarized through the first polarizing plates 14a and 14c, and the liquid crystal panels 15a and 15c are modulated by optical information by pixels. It has unique image information, and is polarized again at the second polarizing plates 16a and 16c to enter the color synthesizing prism 17 '.

In addition, the red light transmitted through the dichroic separation prism 17 is irradiated to the liquid crystal panel 15b for controlling red color, and the liquid crystal panel receives an electric signal of a red image and transmits light by controlling each pixel on the panel surface. The image for color will be displayed.

Light having image information for each color in the first to third liquid crystal panels 15a to 15c is incident on the color synthesizing prism 17 ', and colors are synthesized, and the image formed by this color synthesizing process is a projection lens. It is enlarged by 18 and projected on the screen.

However, since the light source used in such a liquid crystal projection type image display device cannot produce parallel light regardless of the reflector of any shape due to its constant size, the spreading degree from the parallelism plays the role of all means and key means constituting the optical system. The specific characteristics of the liquid crystal panel are weakened. Specific examples thereof include a problem that the color spread of the dichroic separation prism is larger, the color spread becomes worse, and the light spread of the liquid crystal panel and the polarizer increases as the light spreads. There is a problem that the contrast is reduced due to the lack of capability, and the light irradiated onto the liquid crystal panel is incident through the polarizing plate because it must be linearly polarized for control, which causes a problem of deterioration of the light efficiency.

Therefore, in the present invention, the problem of the spreading angle of light was solved by using a resonator, and the decrease in the efficiency of light caused by the polarizing plate was performed by using a polarization separation prism and a mirror in the optical transmission path or through the optical fiber bundle. I tried to solve by doing.

Such an object of the present invention is to separate the light emitted from the light source to have a uniform intensity and a specific spectrum of red, green, blue light emitted and the light emitting means for reflecting the light having a color other than the inside, and the light radiation It can be achieved by the image forming means for forming an image by using the red, green, blue light emitted from the means to project on the screen, the light emitting means is a light source for generating white light and the white light emitted from the light source A reflector reflecting only a specific spectral region, a resonator for diffusing the light reflected directly from the light source and the reflector to make the light distribution uniform through three holes, and attached to each hole of the resonator Selectively transmits one of red, green, and blue light from the light emitted through its respective holes, and the remaining light And a color filter, wherein the image forming means receives light of red, green, and blue transmitted by the light, and red, green, and blue light transmitted by the light transmitting means. A color synthesis image by enlarging a liquid crystal panel which forms an image for a color of the color, a polarizing plate for polarizing an image for each color formed in the liquid crystal panel, and an image for each color polarized by the polarizing plate and incident Or a color synthesizing means for projecting onto a screen, or the image forming means comprising optical transmission means for transmitting the emitted red, green and blue light as polarized parallel light, and red, green and blue light transmitted by the optical transmission means. A polarization separation prism for transmitting and reflecting light, a mirror for reflecting light transmitted through the polarization separation prism, and light reflected from the polarization separation prism A reflection type liquid crystal panel that forms an image for color and reflects the image for each formed color, and an image for each color reflected and incident on the reflection type liquid crystal panel; It can comprise a color combining means projected on.

In addition, the optical transmission means for polarizing the optical fiber bundle for transmitting the emitted red, green, blue light, a micro lens group for approximating the light transmitted from the optical fiber bundle into parallel light, and polarizing the light transmitted from the micro lens group It can be configured as a polarizing plate, the light transmitting means is a lens for converting the emitted red, green, blue light into parallel light, and a polarizing plate for polarizing the light incident through the lens, the light transmission The means includes a lens for converting the emitted red, green, and blue light into parallel light, a polarization splitting prism for transmitting and reflecting the light whose path is converted by projecting the lens, and reflected by the polarization splitting prism. It can be configured as a mirror that reflects light back.

2 is a block diagram of a light projection type liquid crystal image display device according to the present invention, including a light source 1, a reflector 2, a connecting portion 3, a resonator 4, a blue transmission filter 5, and a green transmission filter ( 5), green transmission filter (6), red transmission filter (7), pinhole (19), lens (20), dichroic separation prism (17), color synthesis prism (17 '), mirror (21) And a first polarizing plate 14, a liquid crystal panel 15, a second polarizing plate 16, a projection lens 18, a screen 23, and the like.

3, 4, and 5 show another embodiment of the present invention, in which an optical system is constructed using the polarization splitting prism 22, the reflective liquid crystal panel 24, and the optical fiber bundle 10 as optical transmission means.

In the above configuration, the color synthesizing prism 17 'may use a dichroic separating prism, a plurality of dichroic mirrors, or a dichroic filter.

First, an image forming process of the configuration of FIG. 2 will be described.

White light emitted from the light source 1 has a proper spectral distribution of blue, green, and red.

The light emitted from the light source effectively reflects only the light in the visible region in the reflector 2, and the light in the infrared and ultraviolet regions is transmitted.

The visible light reflected by the reflector 2 and the white light emitted from the light source are emitted outside the resonator through the three pinholes 19 of the resonator 4, and the light not directed to the pinhole is totally reflected at the surface of the resonator.

The light emitted to the outside through the three pinholes is transmitted only through the corresponding colors by the blue, green, and red transmission filters 5, 6, and 7 attached to the respective pinholes. Reflected.

In other words, the pinhole 19 and the color filters 5, 6 and 7 are in contact with each other so that light inside the resonator does not leak to the outside.

The blue, green, and red light emitted through the pinhole and the transmission filter are converted by the reflection mirror 21, and emitted by the lens 20 corresponding to each of them to be close to the parallel light.

Blue, green, and red light passing through the lens are irradiated with liquid crystal panels corresponding to the respective angles to form respective images.

FIG. 3 is a block diagram of the liquid crystal projection image display device of the present invention in which the light transmission path from the color filter to the transmissive liquid crystal panel is different from that in FIG. 2. The light emitted from each color filter is converted into parallel light. A lens 20, mirrors 21a and 21b for converting a path of parallel light transmitted through the lens, a polarization separation prism 22 for transmitting and reflecting light reflected from the mirror, and the polarization separation And mirrors 21e, 21f and 21g for reflecting light reflected back from the prism, and mirrors 21c and 21d for converting the light transmitted through the polarization separation prism 22 toward the liquid crystal panel side.

Referring to the operation of the optical device configured as described above is as follows.

When white light is emitted from the light source 1 having an appropriate spectral distribution of blue, green, and red, the reflector 2 effectively reflects only the visible light of the light source and transmits light in the infrared and ultraviolet light regions.

Light emitted by one or more light sources is effectively totally reflected at the surface of the resonator or exits through the three pinholes 19 without reflection.

The light emitted through the pinhole to the outside of the resonator is transmitted only through the red, green, and blue transmission filters 5, 6, and 7 in contact with the pinhole, and the remaining color light is reflected back into the resonator 4. do.

The blue light passing through the blue transmission filter 5 becomes parallel light by the lens 20a, is reflected by the mirror 21a, and is separated into P and S waves by the polarization separation prism 22a. The path is changed by 21c) to be incident on the transmissive liquid crystal panel 15a, and the image of the incident color is displayed by the image forming process of the liquid crystal panel.

In addition, the S wave reflected by the polarization splitting prism 22a is reflected by the mirror 21e, and is reflected back by the polarization splitting prism 22a to reflect the mirror 21a, the lens 20a, the color filter 5, and the pinhole. It enters into the resonator 4 through 19.

The P wave means light in a linear state vibrating in the same direction as the boundary surface of the polarization separation prism 22, and the S wave refers to light in a linear polarization state vibrating in a direction perpendicular to the bottom of P.

As such, the light incident into the resonator 4 through the pinhole is reflected inside the resonator and then exits again through the pinhole 19 to the outside of the resonator, and the polarization state of the emitted light loses its original linear polarization state due to multiple reflections.

This non-polarized light is reincident to the polarization splitting prism 22 to repeat the process of reflection and transmission described above.

Similarly, the green light is irradiated to the liquid crystal panel 15c which controls the green color, and the liquid crystal panel receives an electric signal of the green image and adjusts light for each pixel on the panel surface to display an image.

The red light is irradiated to the liquid crystal panel 15b for controlling red color, and the liquid crystal panel receives an electric signal of the red image to adjust the light for each pixel on the panel surface to display an image.

Light having image information for each color by the three liquid crystal panels is synthesized by the color synthesizing prism 17 'and is projected on the screen 23 by being enlarged by the projection lens 18.

4 is an embodiment of an optical system using a polarization splitting prism (PBS) and a reflective liquid crystal panel, and includes a light source 1, a reflector 2, a resonator 4, a pinhole 19, and a color filter 5, 6, 7), the operation principle up to the lens 20 is the same as in the case of FIG. 3 described above, the operation after that is as follows.

The separated blue, green, and small are separated into P waves and S Ra by the polarization splitting prism 22, respectively, as shown in FIG.

Here, P wave means light of linearly polarized state vibrating in the same direction as the boundary surface of the polarization split prism 22, and S wave means light of linearly polarized state vibrating in the direction perpendicular to the boundary surface of the canine separation prism 22 it means.

S wave reflected by the polarization split prism 22 is incident on the reflective liquid crystal panel 24 and the polarization state is changed and reflected due to the electric field applied to the liquid crystal panel.

The lower figure of FIG. 9 shows a process of changing the polarization state in the absence of an electric field, and causes a phase difference of one wavelength in the process of being reflected back after being irradiated by the liquid crystal panel with the S wave state. It means converted to P wave state.

That is, the S-wave passing through the liquid crystal upper plate 24a is a circularly polarized state in the clockwise direction and is reflected from the liquid crystal lower panel 24c to return to the counterclockwise circularly polarized state. After reaching the liquid crystal upper layer, the P wave is changed.

The light of the P wave state becomes the light of the image information reaching the screen through the color synthesizing prism 17 'and the projection lens 18.

When the electric field is sufficiently applied to the liquid crystal panel, the S wave is maintained without changing the polarization state, and is reflected back by the polarization separation prism 22 to reflect the reflector 21, the lens 20, the color filter 5, and the pinhole 19. Through the incident to the resonator (4).

The light incident into the resonator 4 is reflected inside the resonator and then exits through the pinhole 5 to the outside of the resonator. The polarized state of the emitted light loses its original linear polarized state by multiple reflections.

This non-polarized light is reincident to the polarization splitting prism 22 to repeat the process of reflection and transmission described above.

Likewise, the P wave transmitted through the polarization split prism 22 is reflected by the reflector 21 and is retransmitted through the polarization split prism 22 without changing the polarization state and is directed into the resonator.

Thereafter, an image is formed on each liquid crystal panel by the image information in the liquid crystal panel, and the images of each formed color are synthesized by the color synthesizing prism 17 ', and then the image on the liquid crystal panel by the projection lens 18. This is magnified and projected on the screen.

5 is a diagram illustrating an optical system using an optical fiber bundle.

Each light transmitted through the light source 1, the reflector 2, the resonator 4, the blue filter 5, the green filter 6, and the red filter 7 is transmitted by the optical fiber bundle 10. The transmitted light is converted into light whose path of light is close to parallel light by the microlens group 11, and the light is readjusted to suit the size of the liquid crystal panel by the two lenses 12 and 13.

The operation principle thereafter is the same as that of FIG. 1, and the operation from the resonator 4 to the lens 12 will be described in detail as follows.

The optical fiber bundle on the resonator side is composed of a plurality of optical fibers in its cross section as shown in the sixth diagram. The optical fiber core 10a transmits light and the cover 10b is reflected.

The outer periphery 9 of the bundle prevents light leakage by screws or other means to engage the resonator.

The shape of the optical fiber may be various, and what is shown here is a general shape.

In some cases, a mask such as the cross-sectional size of the optical fiber bundle may be brought into contact with the front end of the optical fiber.

However, the size of each component of the mask is equal to the size of each optical fiber core of the optical fiber bundle and faces one-to-one, and the other parts are to reflect light.

The optical fiber bundle cross section at the lens side is such that the end of each optical fiber and the micro lens group 11 face each other as shown in the seventh diagram.

The focal length of the microlens group 11 is equal to the distance from the microlens group to the end of the optical fiber so that light transmitted through the microlens becomes parallel light.

This parallel light is adjusted to the parallel light width by using two lenses so that the size of the liquid crystal panel.

As described above, the liquid crystal projection image display device of the present invention can improve light parallelism by using a combination of a resonator, a pinhole, a combination of a resonator, an optical fiber bundle, and a microlens, and absorbs about 60% of light by a conventional polarizing plate. By compensating for the loss caused by a combination of a transmissive liquid crystal panel, a polarization separation prism and an optical fiber, or a combination of a reflective liquid crystal panel, a polarization prism and a mirror, an optical system that realizes a high level of light efficiency can be constructed. It is possible to construct an efficient optical system that is four times brighter than the liquid crystal projector brightness.

Claims (7)

The light emitted from the light source is separated to have a uniform intensity and a specific spectrum of red, green, and blue, respectively, and the light emitting means for reflecting the light in other colors and the red, green emitted from the light emitting means And image forming means configured to parallelize and polarize the blue light to form a bright spot for each color, and to polarize, synthesize, and enlarge the image for each color to be projected onto the screen. The light source of claim 1, wherein the light emitting means is a light source for generating white light, and reflects only a specific spectrum region of the white light emitted from the light source, and diffuses the light emitted directly and reflected from the light source and the reflector. A resonator for equal distribution of the light through three holes, and selectively transmitting one of red, green, and blue light from the light attached to each hole of the resonator and emitted through the respective hole, and remaining light A liquid crystal projection type image display device comprising a color filter which reflects silver. According to claim 1, wherein the image forming means is an optical transmission means for transmitting the red, green, blue light emitted by the polarized parallel light, the red, green, blue light transmitted by the light transmission means for each color A liquid crystal panel for forming an image, a polarizing plate for polarizing an image for each color formed in the liquid crystal panel, and an image for each color polarized and incident on the polarizing plate, and synthesizing the color synthesis image to enlarge the screen. And a color synthesizing means for projecting onto the liquid crystal projection type image display apparatus. 4. The optical transmission apparatus according to claim 3, wherein the optical transmission means comprises: an optical fiber bundle for transmitting emitted red, green, and blue light, a microlens group for proximity of the light transmitted from the optical fiber bundle with parallel light, and transmission from the microlens group A liquid crystal projection type image display device, comprising: a polarizing plate for polarizing polarized light. 4. The liquid crystal projection type image according to claim 3, wherein the optical transmission means comprises a lens for converting emitted red, green, and blue light into parallel light, and a polarizing plate for polarizing light incident through the lens. Display. The optical transmission device of claim 3, wherein the optical transmission means comprises: a lens for converting the red, green, and blue light emitted into parallel light, a polarization separation prism for transmitting and reflecting the light whose path is converted by projecting the lens; And a mirror for reflecting back the light reflected by the polarization splitting prism. According to claim 1, wherein the image forming means is a light transmission unit for transmitting the emitted red, green, blue light polarized parallel light, and polarized light for transmitting and reflecting the red, green, blue light transmitted by the light transmission unit A reflection type liquid crystal that separates a separation prism, a mirror reflecting light transmitted through the polarization separation prism, and light reflected from the polarization separation prism to form an image for each color, and reflects the image for each formed color And a color combining unit for synthesizing an image for each color reflected and incident on the reflective liquid crystal panel and enlarging the color combining image and projecting the image on the screen.