JPH05949Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a projection type liquid crystal display device.

[Conventional technology]

A projection type liquid crystal display device, generally called a liquid crystal projector, is a device that allows light from a light source to enter a transmissive liquid crystal display panel, and then enlarges and projects the displayed image on the liquid crystal display panel onto a screen surface using a projection lens. Conventionally, as a display device,
There are known devices that allow light from a light source to directly enter a liquid crystal display panel.

[Problem that the invention attempts to solve]

However, in the conventional projection type liquid crystal display device described above, in which the light from the light source is directly incident on the liquid crystal display panel, about half of the light from the light source is wasted, resulting in a considerably dark image projected on the screen. I had a problem.

This is because light from a light source contains ordinary rays and extraordinary rays with different vibration directions, whereas the TN (twisted nematic) type liquid crystal display panel, which is commonly used as a liquid crystal display panel,
This is because the display is performed using only one of ordinary rays and extraordinary rays, and the light from the light source that enters the TN type liquid crystal display panel is reflected on both sides of the liquid crystal display panel. Of the two polarizing plates placed on each side, the polarizing plate on the light incident side allows light in the vibration direction that is unnecessary for display (ordinary rays for liquid crystal display panels that use extraordinary rays; The display panel cuts off abnormal rays before entering the liquid crystal display panel, so the light that actually enters the liquid crystal display panel and passes through the liquid crystal display panel, even if there is no loss of transmitted light in the liquid crystal display panel. It is half the light from the light source. Therefore, in conventional projection type liquid crystal display devices in which light directly enters the liquid crystal display panel from the light source, approximately half of the light from the light source is wasted; The amount of projected light is less than half of the amount of light from the light source, and the projected image on the screen becomes quite dark.
Moreover, the light that is cut off by the polarizing plate on the light incident side of the liquid crystal display panel is absorbed by the polarizing plate on the light incident side and raises the temperature of this polarizing plate, which leads to an increase in the temperature of the liquid crystal display panel. There was also the problem of thermal effects on the liquid crystal display panel.

This idea was created in view of the above-mentioned circumstances, and its purpose is to make it possible to project a high-brightness image onto the screen surface by utilizing the light from the light source without wasting it. It is an object of the present invention to provide a liquid crystal display device which can also prevent temperature rise of a liquid crystal display panel.

[Means to solve problems]

The liquid crystal display device of this invention includes a plurality of liquid crystal display panels that display images, a light source that inputs light to the plurality of liquid crystal display panels, and an image that is a composite of a plurality of image lights from the plurality of liquid crystal display panels. A projection means formed on a screen surface and a light separation means separate the light from the light source into an ordinary ray and an extraordinary ray having different vibration directions, and send one of the rays to at least one of the plurality of liquid crystal display panels. The present invention is characterized by comprising an optical system that allows the light beam to enter one of the plurality of liquid crystal display panels and makes the other light beam enter at least one of the plurality of liquid crystal display panels.

[Effect]

In other words, the projection type liquid crystal display device of this invention is
The light from the light source is separated into ordinary rays and extraordinary rays by a separating means, each of which is incident on a separate liquid crystal display panel, and the display images of the plurality of liquid crystal display panels are superimposed by a projection means. According to this projection type liquid crystal display device, only ordinary rays or extraordinary rays can be incident on each of multiple liquid crystal display panels. The light that has been absorbed by the polarizing plate on the light incident side of the LCD panel enters the other LCD panel and is used for display on this LCD panel, so most of the light from the light source is used for display. I can do it. Moreover, according to this projection type liquid crystal display device, since the light that enters both liquid crystal display panels is only the light beam in the vibration direction used for display, it is possible to prevent the temperature rise of the liquid crystal display panel due to absorption of unnecessary light. can.

〔Example〕

A first embodiment of the present invention will now be described with reference to the drawings, which is directed to a projection type liquid crystal display device that projects an image displayed on a liquid crystal display panel onto an external screen surface.

In FIG. 1, 1 is a case of a projection type liquid crystal display device, and two projection lenses 2a and 2b are provided side by side on the front surface of this case 1.
The projection lenses 2a and 2b are provided diagonally laterally so that their optical axes coincide with the surface of the external screen S disposed in front of the apparatus. 3a, 3b
Both projection lenses 2a are placed on the front side of the case 1,
This is a transmissive TN liquid crystal display panel that is provided almost vertically corresponding to each of the panels 2b and 2b. The liquid crystal display panels 3a and 3b are matrix display panels that display color images such as television images, and these two liquid crystal display panels 3a and 3b are designed to display the same image. has been done. Note that 5 is connected to the two liquid crystal display panels 3a and 3b, so that both liquid crystal display panels 3
a display drive circuit board for simultaneously driving a and 3b, 5
A is an LSI chip attached to this circuit board 5. Further, 6a and 6b are projecting lenses 2 in front of the two liquid crystal display panels 3a and 3b, respectively.
It is a condenser lens made of a circular Fresnel lens arranged with the same inclination angle as that of a and 2b, and the display images of both liquid crystal display panels 3a and 3b are projected by condensing lenses 4a and 4b, respectively. 2a, 2b, and these projection lenses 2a,
2b, the images are enlarged and projected onto the external screen S, and are superimposed on this screen S surface.

7 is a light source provided on the rear side of the case 1 so as to face one of the two liquid crystal display panels 3a and 3b, for example, the first liquid crystal display panel 3a;
The light source 7 includes a high-intensity light source lamp 8 such as a halogen lamp or a xenon lamp, and a reflector 9 that reflects the light from the light source lamp 8 toward the first liquid crystal display panel 3a. In addition,
The reflector 9 is a parabolic reflector that reflects the light from the light source lamp 8 as parallel light parallel to the reflector optical axis. 10 is the light source 7
A polarizing beam splitter 11 for separating light is arranged between the polarizing beam splitter 10 and the second liquid crystal display panel 3b.
It is a mirror placed diagonally facing the
The polarizing beam splitter 10 and the mirror 11 direct the light from the light source 7 to the two liquid crystal display panels 3.
An optical system is configured to cause the light to enter a and 3b.
The light separating polarizing beam splitter (also referred to as a polarizing beam splitting prism) 10 separates the light from the light source 7 into an ordinary ray and an extraordinary ray with different vibration directions, and is used to split the light from the light source 7 into two orthogonal rays with different optical axis directions. It has a structure in which triangular prisms 10a and 10b are joined. That is, this polarizing beam splitter 10
In this case, one of the ordinary rays and extraordinary rays in the light incident on the first prism 10a is transmitted through the second prism 10b as it is, and the other ray is transmitted through the junction surface with the second prism 10b. In this embodiment, the polarizing beam splitter 10
, the extraordinary ray x (light vibrating vertically along the plane of the paper in the figure) is transmitted as is, and this light is incident on the first liquid crystal display panel 3a, and the ordinary ray y
(Light that vibrates in a direction perpendicular to the plane of the paper in the figure) is reflected toward one side of the case 1. Further, the mirror 11 reflects the ordinary ray y reflected by the polarizing beam splitter 10 in a direction parallel to the optical path of the extraordinary ray x transmitted through the polarizing beam splitter 10, and directs this light to the second liquid crystal display. The light is made incident on the display panel 3b.

On the other hand, the two TN type liquid crystal display panels 3a,
3b, the first liquid crystal display panel 3a performs display using extraordinary rays, and the second liquid crystal display panel 3b performs display using ordinary rays. Both liquid crystal display panels 3a and 3b are located on the front side (light emitting side) respectively.
It is assumed that polarizing plates 4a and 4b are provided only on the two sides. The reason why the polarizing plates 4a and 4b are provided only on the front side of the liquid crystal display panels 3a and 3b is that the light from the light source 7 is protected from the abnormal rays by the optical system described above.
This is because only the extraordinary ray x is incident on the first liquid crystal display panel 3a, and only the ordinary ray y is incident on the second liquid crystal display panel 3b. Even without providing a polarizing plate on the back side (light incident side) of the liquid crystal display panels 3a, 3b, light in the same vibration direction as the light passing through the polarizing plate can be made to enter the liquid crystal display panels 3a, 3b. Therefore, it is sufficient to provide the polarizing plate only on the front side of the liquid crystal display panels 3a and 3b.

Next, the operation of the projection type liquid crystal display device configured as described above will be described. First, the light from the light source 7 is separated into an extraordinary ray x and an ordinary ray y by the polarizing beam splitter 10 for light separation. Then, the extraordinary ray x that passes straight through the polarizing beam splitter 10
is incident on the first liquid crystal display panel 3a which performs display using extraordinary rays, and the light transmitted through this first liquid crystal display panel 3a, that is, the displayed image on this liquid crystal display panel 3a, is transmitted through a condenser lens 6a. The image is enlarged and projected onto the screen S by the projection lens 2a. Further, the ordinary ray y reflected by the polarizing beam splitter 10 and separated from the extraordinary ray x enters the second liquid crystal display panel 3b that performs display using the ordinary ray, and the second liquid crystal display panel The light transmitted through the liquid crystal display panel 3b, that is, the image displayed on the liquid crystal display panel 3b, is enlarged and projected onto the screen S surface by the projection lens 2b via the condensing lens 6b, and is combined with the projected image from the first liquid crystal display panel 3a on the screen S surface. Superimpose.

That is, in this projection type liquid crystal display device, the light source 7
A light separator separates the light from
two liquid crystal display panels 3a, which display the same image on one of the rays (abnormal ray x);
The other light beam (ordinary ray y) is made incident on the second liquid crystal display panel 3b, and the displayed images on these two liquid crystal display panels 3a and 3b are Projection lens 2
a and 2b onto the screen S surface, and an image in which both images are superimposed is created on the screen S surface. According to this projection type liquid crystal display device, two liquid crystal display panels 3a , 3b, respectively. Therefore, if both liquid crystal display panels 3a and 3b are configured to display using their respective incident rays as described above, both liquid crystal display All the light incident on the panels 3a and 3b can be used for display. In this projection type liquid crystal display device, the light rays in the vibration direction unnecessary for display, which were conventionally cut by a polarizing plate on the back side (light incident side) of the liquid crystal display panel, are cut off before entering the liquid crystal display panel. Since the separated light beam is made incident on another liquid crystal display panel and used for display on this liquid crystal display panel, the light from the light beam 7 can be used without wasting it.
In addition, the image created on the screen S side is the display image of the two liquid crystal display panels 3a and 3b (same image).
Since the screen projection image is a superimposed image, the screen projection image can be a high-luminance image in which both lights transmitted through the two liquid crystal display panels 3a and 3b are superimposed. Moreover, according to this projection type liquid crystal display device, since the light incident on both liquid crystal display panels 3a and 3b is only the light beam in the vibration direction used for display, the back side that occurs in the conventional projection type liquid crystal display device is It is also possible to prevent the temperature of the liquid crystal display panel from rising due to absorption of unnecessary light by the side polarizing plates.

In the first embodiment, the first liquid crystal display panel 3a of the two liquid crystal display panels is used to perform display using extraordinary rays x, and the second liquid crystal display panel 3b is used to perform display using ordinary rays. However, both liquid crystal display panels 3a and 3b may display using light in the same vibration direction, and in that case, a polarizing beam splitter for light separation may be used. Among the extraordinary rays and ordinary rays separated in step 10, the vibration direction of the rays, which cannot be used for display on a liquid crystal display panel if the vibration direction is unchanged, is rotated by approximately 90°, and this light is used for display on a liquid crystal display panel. What is necessary is to make the light beam in the possible vibration direction enter one of the liquid crystal display panels. FIG. 2 shows a second embodiment of this invention. In this embodiment, two liquid crystal display panels 3a,
3b, both of which are displayed using extraordinary rays, and the ordinary ray y of the extraordinary ray x and the ordinary ray y separated by the polarizing beam splitter 10 for light separation. The light is rotated approximately 90 degrees by the optical rotation TN type liquid crystal panel 12 provided between the mirror 11 that reflects the light toward the second liquid crystal display panel 3b and the second liquid crystal display panel 3b, and this light is converted into an extraordinary ray x' as the second liquid crystal display panel 3b
The other configurations are the same as in the first embodiment. The TN type liquid crystal panel for optical rotation 12 is made by filling a pair of front and rear transparent plates with nematic liquid crystal with its molecules twisted at approximately 90 degrees between the two transparent plates.
The other structure is the same as a general TN type liquid crystal display panel, except that it does not have display electrodes and polarizing plates.

Further, in each of the above embodiments, the display images of the two liquid crystal display panels 3a and 3b are displayed using separate projection lenses 2.
a and 2b are projected onto the screen S surface so that both images are superimposed on the screen S surface, but the images displayed on both the liquid crystal display panels 3a and 3b are superimposed before entering the projection lens. It is also possible to project the image from the image onto the screen S surface. That is, FIG. 3 shows a third embodiment of this invention. In this embodiment, the first liquid crystal display panel 3a
A beam splitter 13 for photosynthesis is provided in front of the second liquid crystal display panel 3b, and a mirror 14 is provided in front of the second liquid crystal display panel 3b to reflect the light transmitted through the second liquid crystal display panel 3b toward the beam splitter 13 for photosynthesis. By providing this, the images displayed on both liquid crystal display panels 3a and 3b are superimposed by the beam splitter 13 for photosynthesis, and then projected onto the screen surface by the projection lens 2 via the condensing lens 6. Even in this way, an image in which the display images of both liquid crystal display panels 3a and 3b are superimposed can be created on the screen surface, and according to this embodiment, there is only one projection lens 2 and one condensing lens 6. That's all you need. In FIG. 3, the optical system for making light incident on the liquid crystal display panels 3a and 3b has the same structure as in the second embodiment, but this optical system may have the same structure as in the first embodiment. In addition, the above-mentioned photosynthesis beam splitter 1
3 is a structure in which two right triangular prisms 13a and 13b with the same optical axis direction are joined together, and the light incident on the first prism 13a passes through the second prism 13b as it is, and enters the second prism 13b. The light is reflected at the joint surface of both prisms 13a and 13b in a direction perpendicular to the direction of incidence.

In each of the above embodiments, the polarizing beam splitter 10 is used as a light separator that separates the light from the light source 7 into ordinary rays and extraordinary rays, but this light separator is not limited to a polarizing beam splitter. Furthermore, the optical rotator (TN type liquid crystal display panel 12) in the second embodiment and the photosynthesis body (photosynthesis beam splitter 13) in the third example are also limited to the TN type liquid crystal display panel and the beam splitter. isn't it. Furthermore, in each of the above embodiments, the polarizing plate 4a is provided only on the front side of the liquid crystal display panels 3a and 3b.
4b, but the liquid crystal display panels 3a, 3b
Even if there is a polarizing plate on the back side of the LCD panel, since the incident light to the liquid crystal display panels 3a and 3b is only the light in the vibration direction used for display (extraordinary rays or ordinary rays), the incident light is on the back side. Since it is not absorbed by the polarizing plate and only passes through this back side polarizing plate,
The liquid crystal display panels 3a and 3b may be provided with polarizing plates on both sides. Further, in the above embodiment, a projection type liquid crystal display device was described in which the display images of the liquid crystal display panels 3a and 3b are projected onto an external screen. Of course, the present invention can also be applied to a projection type liquid crystal display device that projects a display image on a liquid crystal display panel.

[Effect of idea]

The projection type liquid crystal display device of this invention has a plurality of liquid crystal display panels that display images, a light source that inputs light to the plurality of liquid crystal display panels, and a plurality of image lights from the plurality of liquid crystal display panels that are synthesized. A projection means forms an image on a screen surface, and a light separation means separates the light from the light source into an ordinary ray and an extraordinary ray with different vibration directions, and sends one of the rays to the plurality of liquid crystal display panels. Since it is equipped with an optical system that allows the light beam to enter at least one of the plurality of liquid crystal display panels and the other light beam to enter at least one of the plurality of liquid crystal display panels, the light from the light source is utilized without wastage to provide high brightness on the screen surface. images can be projected, and the temperature of the liquid crystal display panel can also be prevented from rising.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional plan view of a projection-type liquid crystal display device showing a first embodiment of this invention, FIG. 2 is a cross-sectional plan view of a projection-type liquid crystal display device showing a second embodiment of this invention, and FIG. The figure is a cross-sectional plan view of a projection type liquid crystal display device showing a third embodiment of this invention. 2, 2a, 2b...projection lens, 3a, 3b...
...Liquid crystal display panel, 6, 6a, 6b...Condensing lens, 7...Light source, 8...Light source lamp, 9...Reflector, 10...Polarizing beam splitter for light separation, 11...Mirror, 12... ...TN type liquid crystal display panel for optical rotation, 13...Beam splitter for photosynthesis, 14...Mirror, x, x'...Extraordinary ray, y...
...Ordinary ray, S...screen.

Claims (1)

[Claims for Utility Model Registration] (1) A plurality of liquid crystal display panels that display images, a light source that enters light into the plurality of liquid crystal display panels, and a combination of a plurality of image lights from the plurality of liquid crystal display panels. a projection means for forming an image on a screen surface, and a light separation means for separating the light from the light source into an ordinary ray and an extraordinary ray having different vibration directions, and directing one of the rays to the plurality of liquid crystal display panels. 1. A projection type liquid crystal display device comprising: an optical system that allows light to enter at least one of the plurality of liquid crystal display panels and causes the other light beam to enter at least one of the plurality of liquid crystal display panels. (2) One of the plurality of liquid crystal display panels performs display using ordinary rays, and the other one of the plurality of liquid crystal display panels performs display using extraordinary rays. A projection type liquid crystal display device according to claim 1, which is characterized in that: (3) Two of the plurality of liquid crystal display panels perform display using light in the same vibration direction, and the optical system includes ordinary rays and abnormal rays separated by the light separator. A projection type liquid crystal display according to claim 1 of the utility model registration, characterized in that a light application means is provided for applying light so that one of the light rays vibrates in the same direction as the other light rays. Device.