JPH0943561A - Liquid crystal projection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce cost by constituting a device with a projector main body holding and including a light source, first polarizing plates, liquid crystal, a half mirror group a second polarizing plate, a projection lens to eliminate two sheets of polarizing plates and to improve contrast by applying a polarization at the final stage of a device. SOLUTION: This projection device of a front system is composed of a projection lens 1, field lenses 2, liquid crystal 3 incident side polarizing plates 4, mirrors 5, a light source 6, one sheet of light-emitting side polarizing plate 7 and a main body cover 8. Then, three sheets of incident side polarizing plates 4 are provided only at incident sides in three sheets of liquid crystal 3 groups and one sheet of a light emitting-side polarizing plate 7 is provided in front of or at the rear of the projection lens 1. In this liquid crystal projection device of the front system, the reducing of cost is attained because two sheets of polarizing plates are eliminated and the contrast is improved by applying the polarization at the final stage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal projection device for enlarging and projecting images on liquid crystal panels.

[0002]

2. Description of the Related Art Conventionally, devices for enlarging and projecting an image on a liquid crystal panel using a light source such as a metal halide have been put on the market. In this, light emitted from a light source is condensed on a liquid crystal panel via a mirror or the like and is projected on a screen through a projection lens. There are two types: a front type in which the screen and the projector main body are separated from each other, and a rear type in which a screen, a liquid crystal panel, a light source, a mirror and the like are integrally formed and image light is transmitted through the screen. In both cases, the light emitted from the projection lens is a polarized wave, and generally, only the polarized wave in the vertical direction often appears on the screen surface. In general, a rear type liquid crystal projection device has a projection lens 21,
Field lens 22, liquid crystal 23, incident side polarization plate 24,
The output side polarization plate 25, mirrors 26, a light source 27, a screen 28, a reflection mirror 35, and a cabinet 29. Similarly, the front type also has a projection lens 21, a field lens 22, a liquid crystal 23, an incident side polarization plate 24, an emission side polarization plate 25, mirrors 26, and a light source 2 as shown in FIG.
7 and the main body cover 30.

Further, as shown in FIG. 8, a liquid crystal projection device using a single-plate type liquid crystal is also composed of a light source 31, an incident side polarization plate 32, a liquid crystal 33, and an emission side polarization plate 34, and a reflection type screen 35. Project the image. Further, as in the conventional Japanese Patent Laid-Open No. 3-294817, there is a proposal that a polarizing plate or a phase plate is arranged on the rear surface of each of three liquid crystals to combine polarized waves, and as in Japanese Patent Laid-Open No. 4-151193, the phase is changed. A structure has been proposed in which polarized waves are vertically aligned by a plate, but three plates are arranged behind each liquid crystal.

[0004]

As described above, the conventional liquid crystal projection device has three types of liquid crystal, one of which is a rear type and the other of which is a front type. It is characterized by a method of controlling the optical rotation angle of each pixel by controlling the electric potential to and changing the transmittance of light passing through the emission side polarization plate. With this, RGB
Is a method of outputting an image by changing the brightness of each pixel. In this case, usually, one panel corresponds to each of the two polarizing plates on the entrance and exit sides, resulting in an increase in cost.
Further, when the polarized waves that have passed through the exit side polarization plate are combined, they pass through the mirrors 26, the lens 21 and the like, which not only results in complete polarized waves, but also causes a decrease in contrast. Further, in the case of a rear type projection device, it was common to use a polarizing screen in which the polarization axis is aligned with the transmission axis direction of the light of the projector in order to improve the external light contrast. It has the same function but the loss of transmittance due to the film is 15
%, Which caused the brightness to decrease. These were the same for the single plate type and the three plate type. Further, since the liquid crystal panel is affected by the temperature rise of the emission side polarizing plate, it is difficult to cool it when using a high brightness lamp. Furthermore, there has been no system that divides the image projected on the screen into those who can see it and those who cannot see it, and the system that only sees the image on glasses with polarizing plates.

In view of the above problems, the present invention is shown in FIG.
As shown in FIG. 2, for example, in a liquid crystal type front type or rear type projector, a projection device is provided in which three emission side polarization plates are removed and another polarization plate is configured. To do. Further, in the rear type projector main body, all the polarizing plates on the emission side are deleted, and a system for viewing an image on a reflective polarizing screen (polarizing screen) is provided.
This also applies to the single plate type. Furthermore, the present invention provides a system in which the polarizing plate on the output side is deleted and the image can be viewed only with glasses having polarizing plates.

[0006]

A liquid crystal projection device according to the present invention comprises a light source, three liquid crystals for controlling the transmission of light from the light source, and a uniaxial direction arranged on the light incident side of the liquid crystal. Three first polarizing plates that transmit the polarized waves of, a half mirror group that color-separates and color-combines the light from the light source, and a second sheet that is arranged after the half-mirror group is combined. And a projection lens for enlarging / reducing the transmitted light image by the liquid crystal group, a light source, a first polarization plate, the liquid crystal, the half mirror group, a second polarization plate, and a projection lens. The projector is composed of a main body and a projector.

Further, the liquid crystal projection apparatus of the present invention includes a light source, three liquid crystals for controlling the transmission of light from the light source, and a uniaxial polarized wave which is arranged on the light incident side of the liquid crystal. A holding member that holds the three light-transmitting first polarizing plates, a half mirror group that color-separates and synthesizes light from the light source, a light source, the liquid crystal, the first polarizing plate, and the half mirror group. A member, a polarizing screen located near the image light image plane of the polarized light and controlling transmission and absorption depending on the degree of polarization of the polarized light; a mirror for reflecting the image light; the polarizing screen; and the mirror. It is composed of a cabinet body to be held.

Further, the liquid crystal projection device of the present invention includes a light source, a single polarizing plate arranged on the incident side of the light from the light source to generate a polarized wave, and a polarizing axis that transmits the polarized wave and twists the polarization axis. The projector main body is composed of a liquid crystal to be controlled, a projection lens for enlarging and reducing a transmitted light beam image by the liquid crystal, and a polarizing screen for controlling transmission and absorption according to the degree of polarization of the polarized wave.

Further, the liquid crystal projection device of the present invention includes a light source, a single polarizing plate arranged on the incident side of the light from the light source to generate a polarized wave, and a polarizing axis which transmits the polarized wave and twists the polarization axis. A projector main body composed of a liquid crystal to be controlled, a projection lens for enlarging or reducing a transmitted light beam image by the liquid crystal, and polarizing glasses fixing a polarizing plate that transmits only polarized light in a uniaxial direction to both eyes with respect to the polarization degree of the polarized wave. It is configured with.

[0010]

According to the liquid crystal projection device of the present invention,
In the front method, two polarizing plates can be deleted, which reduces cost and improves contrast by polarizing at the final stage. Further, in the rear method, the use of a polarizing screen is utilized to eliminate the cost of three polarizing plates, and the brightness can be improved by about 15%. further,
Since all the polarizing plates on the output side are removed by the front method, it is not possible to see images on a normal screen, but it is possible to provide a system that allows you to see images if you use a polarizing screen that matches the transmission axis of polarized waves. Further, similarly, it is possible to provide a system in which an image can be viewed only when glasses are fitted with the transmission axes of polarized waves.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A liquid crystal projection device according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a main part of a front type liquid crystal projection apparatus according to an embodiment of the present invention. FIG. 2 is a sectional view of an essential part of a liquid crystal projection device in which FIG. 1 is incorporated in a cabinet to form a rear system.

As shown in FIG. 1, the front type liquid crystal projection device has a projection lens 1, a field lens 2, a liquid crystal 3, an incident side polarization plate 4, mirrors 5, a light source 6, and one emission side polarization plate 7. , The main body cover 8. The exit side polarization plate 7 may be arranged in front of the projection lens 1. Similarly, the rear type liquid crystal projection device
The projection lens 1, the field lens 2, the liquid crystal 3, the incident side polarization plate 4, the mirrors 5, the light source 6, the reflection mirror 11, and the polarization screen 9 in which the polarization axis is aligned with the light emitted from the projector,
It is composed of a cabinet 10 that supports them.

FIG. 3 is a model diagram of a single plate type liquid crystal projection device. Similar to FIGS. 1 and 2, the projection lens 1, the field lens 2, the liquid crystal 3, the incident side polarization plate 4, and the light source 6 are included. In the case of FIG. 3, the reflection type polarization screen 12 is used for both the rear type (not shown) and the front type. The polarization axis of the incident side polarization plate 4 is horizontal as shown in FIG. 3 and is vertical after passing through the liquid crystal, and the polarizing screen is also of vertical reflection type.

Further, another embodiment is shown in FIG. In this case, a system for viewing an image formed by projecting the teeth having the configuration shown in FIG. 3 on a normal screen and using a pair of glasses configured with a polarizing film 13 having a polarization axis stuck in the ↑ direction and a frame 14 holding them. Examples are also given. FIG. 5 shows the relationship between the incoming and outgoing polarizing plates 4 and 7 and the liquid crystal 3. Generally, light is transmitted through the incident side polarizing plate 4 in the direction of arrow ← → in the figure, and the liquid crystal 3
At 90 °, it was shown that only 90 ° polarized light component was generated in the vertical direction. If the emission-side polarization plate 7 is configured to pass only the component in the vertical direction, the light incident in the horizontal direction in FIG. 5 is emitted in the vertical direction. Therefore, the light passing through the three liquid crystal layers can be converted into a uniaxial polarization component by using one polarizing plate before or after entering the projection lens 1 even if the outgoing polarizing plate is omitted. It can output light.

In the case of the rear type, its output side polarizing plate 7
If the function of is performed by the polarizing screen 9 having a polarizing film attached, an image can be captured by the light component (↑) in the uniaxial direction. Further, in the case of the front system, when a projector without an emission side polarization plate is used, an image can be projected on the reflection type polarization screen 12, and in the case of an ordinary screen which does not use the polarization screen, glasses 13 with a polarization film are attached. , 14 can see the image clearly.

[0016]

As described above, according to the liquid crystal projection device of the present invention, in the front system, two polarizing plates can be eliminated, so that the cost can be reduced and the contrast can be improved by polarizing at the final stage. Further, in the rear method, the use of a polarizing screen is utilized to eliminate the cost of three polarizing plates, and the brightness can be improved by about 15%. In addition, the liquid crystal panel can be prevented from being affected by the temperature due to the emitting side polarization plate. Furthermore, since all polarizing plates on the output side are removed by the front method, it is possible to provide a system in which an image cannot be viewed on a normal screen, but a polarizing screen with a transmission axis of polarized waves can be used to view the image. . Similarly, it is possible to have a system in which the image can be viewed only when glasses are fitted with the transmission axis of polarized waves, and it is possible to create a situation where a secret document is presented or a person who is not wearing glasses cannot see the image. Therefore, it can be used for image projection equipment in amusement facilities.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part of a liquid crystal projection device according to an embodiment of the present invention.

FIG. 2 is a sectional view of an essential part of a liquid crystal projection device according to an embodiment of the present invention.

FIG. 3 is a model diagram of a single plate type of a liquid crystal projection device according to an embodiment of the present invention.

FIG. 4 is a principle diagram of a liquid crystal projection device according to an embodiment of the present invention.

FIG. 5 is a schematic diagram of an input / output polarizing plate 4 according to an embodiment of the present invention.
5 is a perspective view showing the relationship between the liquid crystal 5 and the liquid crystal 3.

FIG. 6 is a sectional view of a main part of a conventional liquid crystal projection device.

FIG. 7 is a sectional view of a main part of a conventional liquid crystal projection device.

FIG. 8 is a principle diagram of a conventional liquid crystal projection device.

[Explanation of symbols]

 1 Projection Lens 2 Field Lens 3 Liquid Crystal 4 Incident Side Polarizing Plate 5 Mirror 6 Light Source 7 Emitting Side Polarizing Plate 9 Polarizing Screen 12 Reflective Polarizing Screen 13 Polarizing Film

Claims (4)

[Claims] 1. A light source, a liquid crystal that controls transmission of light from the light source, first polarizing plates that are respectively disposed on the light incident side of the liquid crystal and that transmit uniaxial polarized waves, and the light source. A half mirror group for color-separating and synthesizing colors of light from the above, a second polarizing plate disposed after the light is synthesized by the half mirror group, a projection lens for enlarging or reducing a transmitted light beam image by the liquid crystal group, A liquid crystal projection device comprising a light source, a first polarizing plate, the liquid crystal, the half mirror group, a second polarizing plate, and a main body of a projector which holds and encloses the projection lens. 2. A light source, a liquid crystal that controls transmission of light from the light source, first polarizing plates that are respectively disposed on the light incident side of the liquid crystal and that transmit only uniaxial polarized waves, and the light source. A group of half mirrors that color-separates and synthesizes light from
A holding member that holds the light source, the liquid crystal, the first polarizing plate, the half mirror group, and a transmission member that is located in the vicinity of the image light image forming surface of the polarized light and controls transmission and absorption depending on the polarization degree of the polarized light. A liquid crystal projection device comprising a polarizing screen, a mirror that reflects the image light, and a cabinet body that holds the polarizing screen and the mirror. 3. A light source, a single polarizing plate arranged on an incident side of light from the light source to generate a polarized wave, a liquid crystal which transmits the polarized wave and controls a twisting direction of a polarization axis, and the liquid crystal A liquid crystal projection device comprising: a projector main body including a projection lens for enlarging or reducing a transmitted light beam image; and a polarizing screen for controlling transmission / absorption according to a polarization degree of the polarized wave. 4. A light source, a single polarizing plate arranged on the incident side of light from the light source to generate a polarized wave, a liquid crystal that transmits the polarized wave and controls the twist direction of the polarization axis, and the liquid crystal A projector main body configured with a projection lens for enlarging / reducing a transmitted light beam image, and polarizing glasses for fixing a polarizing plate that transmits only polarized light in a uniaxial direction to both eyes with respect to the polarization degree of the polarized wave. Liquid crystal projection device.