JP2861315B2 - LCD projector - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal projector using a thin liquid crystal panel, and more particularly, to a liquid crystal projector capable of performing reclining projection without causing graphic distortion.

[Summary of the Invention]

The present invention relates to a liquid crystal projector using a thin liquid crystal panel, in which a reduced spatial image of the liquid crystal panel and an image near a field lens are formed and projected on a screen via a projection lens, and the field lens and the projection lens are interlocked. By making it possible to translate in the direction perpendicular to the optical axis, it is possible to raise and project at an arbitrary elevation angle without causing distortion of the figure.

[Conventional technology]

Liquid crystal projectors have been developed in which an original image is formed on a thin liquid crystal panel, and image light from the original image is projected on a screen. Such a liquid crystal projector is a CRT
Installation and adjustment can be performed easily compared to a shaped projector.

When projecting a screen on a screen using a projector, it is often desirable to install the screen at a relatively high position in parallel with a wall surface and project the projection light from the projector onto the screen with an elevation angle. However, when such a reclining projection is performed by tilting the liquid crystal projector, a problem occurs in that the screen on the screen is distorted in a trapezoidal shape.

In the case of a CRT type projector, graphic distortion can be improved electrically by superimposing a correction signal and adjusting the raster size. However, in the case of a liquid crystal projector, it is in principle impossible to electrically correct figure distortion.

In slide film projection, the fourth
As shown in FIG. 5 and FIG. 5, there has been proposed a projector which performs distortionless projection.

In FIG. 4, reference numeral 51 denotes a light source. Light from the light source 51 is converted into a parallel light beam by the condenser lens 52 and is provided to the field lens 53. Original image near field lens 53
54 are arranged. In this case, the original image 54 is a slide film. The original of the original image 54 is focused by the field lens 53 and provided by the projection lens 55. An image 56 based on the original image 54 is projected on a screen by the projection lens 55.

When performing back projection, the light source 51 and condenser lens
52, the original image 54 is moved as indicated by the broken line. That is, the light source 51
The angle of the condenser lens 52 is changed so that the light beam is directed toward the center of the pupil of the projection lens 55, and the original image is positioned such that the center of the original image 54 is positioned on the light beam directed toward the pupil center of the projection lens 55.
54 is moved. As described above, when the original image 54 is moved together with the light source 51 and the condenser lens 52, the image 56A projected without distortion is projected on the screen.

FIG. 5 shows another example of a slide film projection that enables projection without distortion.

In the example shown in FIG. 4, the original image 54 is moved together with the light source 51 and the condenser lens 52. On the contrary,
In this example, the projection lens 55 is moved together with the light source 51 and the condenser lens 52 to perform distortionless projection. That is, the projection lens 55 is moved together with the light source 51 and the condenser lens 52 such that the light flux from the light source 51 toward the center of the original image 54 is located at the center of the pupil of the projection lens 55. Thus, distortionless projection can be performed.

FIG. 6 is an example in which the principle of the distortionless projection in the slide projection described above is applied to enable the distortionless projection of the liquid crystal projector.

In FIG. 6, light from a light source 61 is a condenser lens.
The light is converted into a parallel light beam by the dichroic mirror group 63 and split into red, green, and blue light by the dichroic mirror group 63. Liquid crystal panels 64R, 64G, and 64B are respectively provided in the optical paths of red, green, and blue light. LCD panel 64R, 64G, 6
Field lenses 65R, 65G, and 65B are provided near each of 4B. The image lights of the liquid crystal panels 64R, 64G, 64B are converged by the field lenses 65R, 65G, 65B and are synthesized via the dichroic mirror group 66. Then, the combined image light is given to the projection lens 67, and the enlarged image 68 is projected on the screen.

When performing back projection, the light source 61 and the condenser lens 52 are moved as shown by the broken lines. Along with this, the light source
The dichroic mirror groups 63, 66, so that the respective centers are located on the light flux from 61 to the pupil center of the projection lens 67,
LCD panels 64R, 64G, 64B, field lenses 65R, 65G, 65B
Are moved respectively. This allows the image to be projected without distortion
68A is projected.

[Problems to be solved by the invention]

However, in the configuration shown in FIG. 6, it is necessary to change the positions of the three liquid crystal panels 64R, 64G and 64B in conjunction with the light source 61 and the condenser 62 when performing the back projection. When the positions of the three liquid crystal panels 64R, 64G, and 64B are changed as described above, there is a possibility that registration may be incorrect.

Therefore, in the configuration shown in FIG. 6, it is possible to raise the projection only at a predetermined angle for which registration adjustment has been performed in advance, and it is not possible to set an arbitrary elevation angle.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a liquid crystal projector capable of performing projection by raising at an arbitrary elevation angle without generating graphic distortion.

[Means for solving the problem]

According to the present invention, a reduced spatial image of a liquid crystal panel is formed near a field lens using a reducing lens, and the reduced spatial image of the liquid crystal panel is projected on a screen via a projection lens, and the field lens and the projection lens are linked. The liquid crystal projector is configured to be capable of moving parallel to the optical axis perpendicularly.

[Action]

A reduced aerial image is formed, and the reduced aerial image is applied to a projection lens via a field lens so as to be projected on a screen, and the field lens and the projection lens are integrally integrated in a direction perpendicular to the optical axis. When it is moved in parallel, it is possible to raise and project at an arbitrary elevation angle.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a basic configuration of a liquid crystal projector to which the present invention is applied. In FIG. 1, reference numeral 1 denotes a light source. The light from the light source 1 is converted into a parallel light beam by the condenser lens 2 and is separated by the dichroic mirror group 3 into red, green and blue light. The liquid crystal panels 4R, 4G, and 4B are provided in respective optical paths of red, green, and blue light. Field lenses 5R, 5G, and 5B are provided near the liquid crystal panels 4R, 4G, and 4B, respectively. LCD panel
The image lights of 4R, 4G, and 4B are converged by field lenses 5R, 5G, and 5B, combined through a dichroic mirror group 6, and provided to a reduction lens 7. The reduction lens 7 produces a reduced aerial image 9 in the field lens 8. Image light of the reduced spatial image 9 is condensed by the field lens 8 and supplied to the high-magnification projection lens 10. Thereby, the enlarged image 11 is projected on the screen.

The field lens 8 and the projection lens 10 can be moved in parallel with each other perpendicularly to the optical axis. When the field lens 8 and the projection lens 10 are moved up and down in conjunction with each other as shown by a broken line, an enlarged image 11A projected and raised at an arbitrary elevation angle θ is displayed.

The original image of this back projection will be described. As shown in FIG. 2 A, when the centers of the lens L ₁ of the image A ₁ at the same height, as shown in FIG. 2 A, the real image B ₁ of the image A ₁ is identical to the height Occurs. Here, as shown in FIG. 2 B, the image A ₁ is kept fixed, when moving the lens L ₁ above, real image B ₂ of the image A ₁ is issued Film moves upward. In other words, the back projection can be performed.

According to the same principle, the field lens 8 and the projection lens
When it is moved upward in conjunction with 10, the back projection can be performed.

In this example, the field lens 8 and the projection lens 10 are moved in conjunction with each other. For this reason, the central principal ray always passes through the center of the pupil of the projection lens 10, and there is no loss of the light amount. When the field lens 8 or the projection lens 10 is moved alone, the principal ray deviates from the center of the pupil of the projection lens, and the amount of light in a part of the screen decreases.

The reduction lens 7 is provided to form a reduced aerial image 9 in the field lens 8. This reduced space image 9
Is sufficiently smaller than the diameters of the field lens 8 and the projection lens 10. For this reason, even when the field lens 8 and the projection lens 10 are moved to perform reclining projection, a part of the image is not lost and a sufficient amount of light can be obtained.

The arrangement for forming a reduced aerial image by arranging a reduction lens and projecting the same has been previously proposed by the present inventor in Japanese Patent Application Laid-Open No. 1-110907.

3A and 3B are a plan cross-sectional view and a side cross-sectional view showing a specific configuration of a liquid crystal projector to which the present invention is applied.

In FIG. 3, reference numeral 21 denotes a xenon lamp, and a reflecting mirror 22 is provided behind the xenon lamp 21. Light from the xenon lamp 21 is converted into a parallel light beam via the condenser lens 23.

24 is a red and blue reflecting dichroic mirror, 25 is a red reflecting dichroic mirror, 26 and 27 are total reflecting mirrors, 28 is a red reflecting dichroic mirror, and 29 is a blue reflecting dichroic mirror. By these mirrors, the light from the xenon lamp 21 is split into three primary color lights.

30 is a liquid crystal panel on which a green original image is formed, 31 is a liquid crystal panel on which a red original image is formed, and 32 is a liquid crystal panel on which a blue original image is formed. Field lenses 33, 34, and 35 are provided near the liquid crystal panels 30, 31, and 32, respectively.

Light from the xenon lamp 24 passes through a condenser lens 23 and is provided to a dichroic mirror 24. The dichroic mirror 24 transmits the green color light l _{G and} transmits the blue color light.
l _B and red color light l _R are reflected.

The green color light l _G transmitted through the dichroic mirror 24 is
The liquid crystal which is reflected by the mirror 27 and forms a green original image via the field lens 33 is given to 30.

Color light l _B and color light l _R of the red and blue reflected by the dichroic mirror 24 is provided to the dichroic mirror 25.
The dichroic mirror 25, color light l _B blue are transmitted, the red color light l _R is reflected.

The red color light l _R reflected by the dichroic mirror 25 is
The light is applied to a liquid crystal panel 31 that forms a red original image via a field lens.

The dichroic mirror 25 color light l _B of the transmitted blue is
The light is applied to a liquid crystal panel 32 that forms a blue original image via a field lens 35.

A green original image is formed on the liquid crystal panel 30, and the green image light is focused by a field lens 33, and is reduced via a dichroic mirror 28 and a dichroic mirror 29.
Supplied to 36.

A red original image is formed on the liquid crystal panel 31, and this red image light is focused by the field lens 34, reflected by the dichroic mirror 28, and supplied to the reduction lens 36 via the dichroic mirror 29.

A blue original image is formed on the liquid crystal panel 32, and this blue image light is reflected by the mirror 26, reflected by the dichroic mirror 29, and supplied to the reduction lens 36.

Red image light, blue image light, and green image light are reduced by a reduction lens 36.
And reflected by the mirror 37. This reduction lens 36
Thus, a reduced spatial image 38 of an image in which the image lights of the three primary colors are synthesized
(FIG. 3B) results.

39 is a field lens and 40 is a projection lens. The field lens 39 and the projection lens 40 are integrated by an adapter 41. The adapter 41 has a lens moving mechanism 42
Is provided. By the lens moving mechanism 42, the field lens 39 and the projection lens 40 can be integrally moved vertically and horizontally in a direction perpendicular to the optical axis.

The reduced spatial image 38 formed by the reduction lens 36 is given to the projection lens 40 via the field lens 39, and is projected on the screen by the projection lens 40.

This liquid crystal projector is operated by a lens moving mechanism 42.
The field lens 39 and the projection lens 40 are integrally movable in a direction perpendicular to the optical axis. Field lens
When the projection lens 39 and the projection lens 40 are moved in the direction of the arrow, the projection can be performed at an arbitrary elevation angle.

〔The invention's effect〕

According to the present invention, it is possible to perform elevation projection at an arbitrary elevation angle by integrally moving the field lens and the projection lens in a direction perpendicular to the optical axis.
As described above, since the field lens and the projection lens are integrally moved, the central principal ray is located at the center of the pupil of the projection lens, and the light quantity is not insufficient. Then, a reduced spatial image is formed by the reduction lens, and the reduced spatial image is projected by the field lens and the projection lens. Therefore, even if the elevation angle is increased, there is no vignetting of the image and the brightness does not decrease.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration of a liquid crystal projector to which the present invention is applied, FIG. 2 is a schematic diagram used for describing a liquid crystal projector to which the present invention is applied, FIG. 3A and FIG.
FIG. 4 is a plan sectional view and a side sectional view showing a specific structure of a liquid crystal projector to which the present invention is applied. FIGS. 4 and 5 are schematic diagrams used to describe a conventional projection mechanism for slide film projection, and FIG. FIG. 3 is a schematic diagram used for describing a back projection mechanism of a conventional liquid crystal projector. Description of main reference numerals in the drawings 1,21: light source, 7,36: reduction lens, 8,39: field lens, 10,40: projection lens.

Claims (1)

(57) [Claims] An image of a reduced spatial image of a liquid crystal panel is formed near a field lens using a reducing lens, and the reduced spatial image of the liquid crystal panel is projected on a screen via a projection lens. A liquid crystal projector in which a lens and a liquid crystal projector can be moved parallel to the optical axis in conjunction with the lens.