JPH04119323A - Liquid crystal projector - Google Patents

Abstract

PURPOSE:To perform projection corresponding to an external condition and the kind of screen by disposing polarizing filters which are orthogonally crossed with each other on the incident side and the exiting side of a liquid crystal panel, and allowing the polarizing filter on the exiting side to freely get in and out of an optical path. CONSTITUTION:This liquid crystal projector P is constituted of a light source 2 incorporated in a projector main body 1, the polarizing filter 3, the liquid crystal panel 4, the polarizing filter 5, a projecting lens 6 disposed on the front surface of the main body 1, a video signal processing circuit 7, a liquid crystal driving circuit 8, and a polarizing screen 10 provided with the polarizing filter 9 on its front surface. In the case of observing a video on the screen 10 provided with the polarizing filter 9, the video is projected in a state where the polarizing filter 5 on the exiting side is out of the optical path, and it is projected in a state where the filter 5 on the exiting side is allowed to advance in the optical path in the case of observing the video on an ordinary screen 10 in a dark room which is little influenced by external light. Thus, the projection corresponding to the external condition and the kind of screen 10 is performed.

Description

[Detailed Description of the Invention] [Industrial Application Features] This invention irradiates a liquid crystal panel with light from a light source and drives the liquid crystal panel with an input video signal.
The present invention relates to a liquid crystal projector that enlarges and projects emitted image light onto a screen.

[Conventional technology] In the optical system of a liquid crystal projector, dichroic
One is a type that uses a Tsukumirror to separate and combine colors, the other is a front-projection type that uses a graphical prism to perform color synthesis, and a reflective liquid crystal panel is used to project images onto a screen using three projection lenses. There is a rear projection compatible type that combines colors.

In any type of liquid crystal projector, light from a light source is irradiated onto the liquid crystal panel, the liquid crystal is driven by the input video signal, and the image light emitted from the liquid crystal panel is enlarged and projected onto the screen using a projection lens. Was.

[Problems to be Solved by the Invention] In liquid crystal projectors, a dedicated polarizing screen is generally used to suppress the influence of external light and obtain a high contrast screen.

However, in a dark room with little outside light or in the case of a relatively small screen, viewing can be done using a normal screen by placing a polarizing filter on the exit side of the liquid crystal panel that is orthogonal to the polarizing filter on the input side. be.

This invention was made in view of the above points, and in the case of a dark room with little outside light or a relatively small screen, it is possible to watch on an ordinary screen, and it is also relatively bright and is free from the influence of outside light. The purpose of the present invention is to provide a liquid crystal projector that can be viewed on a polarizing screen in certain cases.

[Means for Solving the Problems] In order to solve the above-mentioned problems, in this invention, light from a light source is transmitted through a liquid crystal panel, is emitted as image light to a projection lens, and is magnified by the projection lens and projected onto a screen. A liquid crystal projector for projecting images is characterized in that polarizing filters are disposed orthogonally to the incident side and the exiting side of the liquid crystal panel, and the polarizing filter on the exiting side is movable in and out of the optical path.

[Function] When viewing an image on the screen 10 equipped with the polarizing filter 9, the polarizing filter 5 on the exit side is removed from the optical path and projected as shown at 1121.

In addition, when viewing an ordinary screen 10''CH image in a dark room or the like where there is little influence of external light, the polarizing filter 5 on the exit side is advanced into the optical path and projected as shown in FIG.

[Embodiment 2] Next, the second embodiment of the liquid crystal projector according to the present invention will be explained.
An example will be described in detail with reference to FIG. 1 et seq.

FIG. 1 is a schematic diagram showing a first embodiment of a liquid crystal projector-P according to the present invention.

In this FIG. 1, a liquid crystal projector-P is shown.

Light source 2 and polarizing filter 3 built into projector body 1
, a liquid crystal panel 4, a polarizing filter 5, a projection lens 6 disposed on the front of the projector body 1, a video signal processing circuit 7, a liquid crystal drive circuit 8, and a polarizing screen 10 with a polarizing filter 9 disposed on the front. It consists of

As the light source 2, for example, a metal halide lamp, which is an improved version of a high-pressure mercury lamp, is used.

The polarizing filter 3 on the incident side polarizes the light emitted from the light source 2 in one direction and outputs the polarized light to the liquid crystal panel 4 .

The liquid crystal panel 4 has liquid crystal molecules 41 sealed between an input-side glass substrate 42 and an exit-side glass substrate 43, as shown in FIG.

The polarizing filter 5 on the exit side is a polarizing filter that is orthogonal to the polarizing filter 3 on the input side, and in the first embodiment, since a screen 10 with a polarizing filter 9 is used, it is removed from the optical path.

The projection lens 6 magnifies the image light emitted from the liquid crystal panel 4 and projects it onto a screen 10 equipped with a polarizing filter 9.

The video signal processing circuit 7 processes the input video signal A into a desired signal form.

The liquid crystal drive circuit 8 drives the liquid crystal molecules 41 of the liquid crystal panel 4 based on the input signal from the video processing signal circuit 7 .

Like the polarizing filter 5, the polarizing filter 9 is a polarizing filter that is orthogonal to the polarizing filter 3 on the incident side, and is combined with the screen 10 to form a polarizing screen.

Therefore, when the video signal A is input to the video signal processing circuit 7, it is processed by the video signal processing circuit 7 into a desired signal form and then output to the liquid crystal drive circuit 8.

Then, the liquid crystal molecules 41 of the liquid crystal panel 4 are driven by the liquid crystal driving circuit 8, and the polarization angle of the incident light can be changed depending on the content of the video signal A.

On the other hand, light emitted from a light source 2 such as a metal halide lamp passes through a polarizing filter 3 on the incident side, allowing only light to be polarized in one direction.The polarization angle is changed by liquid crystal molecules 41 depending on the image content, and then the projection lens screen 1 by 6
It will be enlarged and projected to 0.

The light projected onto the screen 10 passes through a polarizing filter 9 which is orthogonal to the polarizing filter 3, is reflected by the screen 10, passes through the polarizing filter 9 again, and is emitted.

As shown in FIG.
1 is sealed, and when there is no electric field, light passes through the liquid crystal molecules 41 in a state in which the liquid crystal molecules 41 are vertically switched by 900 degrees (the polarization axis is rotated by 90 degrees) as shown in FIG. 2(a).

Further, when an electric field is applied, the liquid crystal molecules 41 are aligned perpendicularly to the entrance side glass substrate 42 and the exit side glass substrate 43, as shown in FIG. 2(b), and pass through without being exposed to light.

In this way, the incident light passes through the polarizing filter 3 and then passes through the incident side glass substrate 42, the liquid crystal layer composed of liquid crystal molecules 41,
The light passes sequentially through the exit-side glass substrate 43 and is emitted to the projection lens 6 as image light.

FIG. 3 is a schematic diagram showing a second embodiment of the liquid crystal projector-P according to the present invention.

In FIG. 3, the liquid crystal projector-P includes a light source 2, a polarizing filter 3, a liquid crystal panel 4, a polarizing filter 5 built into the projector main body 1, and a polarizing filter 5 on the front surface of the projector main body 1, as in the first embodiment. A projection lens 6, a video signal processing circuit 7, a liquid crystal drive circuit 8, and a screen 10 are arranged.
' It is composed of spiky bones.

This second embodiment differs from the first embodiment in that the polarizing filter 5 is placed in the optical path and that a normal screen 10' is used instead of the screen 10 with the polarizing filter 9.

Therefore, when the video signal A is input to the video signal processing circuit 7, it is processed by the video signal processing circuit 7 into a desired signal form, and then output to the liquid crystal drive circuit 8.

Then, the liquid crystal molecules 41 of the liquid crystal panel 4 are driven by the liquid crystal driving circuit 8, and the changing angle of the incident light is changed according to the content of the input video signal A.

On the other hand, the light emitted from a light source 2 such as a metal halide lamp passes through a changing filter 3 on the incident side so that only the polarized light in one direction passes through it, and the polarization angle is changed by the liquid crystal molecules 41 of the liquid crystal panel 4 according to the image content. Polarizing filter 3 on the input side
The light is polarized by a polarizing filter 5 on the exit side, which is orthogonal to 5.
The image light is combined with the projection lens 6, and the projection lens 6
The image is enlarged and projected onto the screen 10'.

The above-mentioned liquid crystal panel 4 has liquid crystal molecules 41 between an input-side glass substrate 42 and an exit-side glass substrate 43, as shown in FIG.
is sealed, and polarizing filters 3 are installed on the entrance side and the exit side, respectively.
．． 5 is placed.

When there is no electric field, light is transmitted in a state in which the liquid crystal molecules 41 are vertically switched by 900 degrees (a state in which the polarization axis is rotated by 90 degrees) as shown in FIG. 4(a).

Furthermore, when an electric field is applied, the liquid crystal molecules 41 are aligned perpendicularly to the incident-side glass substrate 42 and the exit-side glass substrate 43, as shown in FIG. 4(b), and pass through without being exposed to light.

In this way, the incident light passes through the polarizing filter 3 on the incident side, passes through the incident side glass substrate 42, liquid crystal molecules (liquid crystal layer) 41, and exit side glass substrate 43 of the liquid crystal panel 4 in order, and then changes to the polarized light on the exit side. The light passes through the filter 5 and is emitted to the projection lens 6 as image light.

[Effects of the Invention As described above, the liquid crystal projector according to the present invention has the following effects:
Polarizing filters are disposed orthogonally to the entrance and exit sides of the liquid crystal panel, and the exit @ polarizing filter can be moved in and out of the optical path, and when a polarizing screen is used, the exit polarizing filter is removed from the optical path. When a normal screen is used, the exit filter is moved into the optical path.

Therefore, projection can be performed in accordance with external conditions and the type of screen.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing an example of implementation of the liquid crystal projector according to the present invention, FIG. 2 is an operational diagram of the liquid crystal panel, and FIG. 3 is a second example of implementation of the liquid crystal projector according to the invention. The schematic configuration diagram shown in FIG. 4 is an operational diagram of the liquid crystal panel. P・LCD projector 2・Light source Polarizing filter LCD panel Projection lens・Polarizing filter screen

Claims (1)

[Claims] (1) In a liquid crystal projector that transmits light from a light source through a liquid crystal panel, emits it as image light to a projection lens, magnifies it with the projection lens, and projects it onto a screen, the light is perpendicular to the entrance and exit sides of the liquid crystal panel. A liquid crystal projector characterized in that a polarizing filter is provided and the polarizing filter on the exit side is movable in and out of the optical path.