JPH02287586A - Liquid crystal projector - Google Patents

Abstract

PURPOSE:To eliminate the Keystone distortion of an image on a screen by arranging a relay lens vertically movably at right angles to the optical axis of an image formation optical system and varying the angle between the optical axis of a projection lens and the normal of the screen. CONSTITUTION:The projection lens 17, a field lens 18, and relay lens 19 are provided in a lens barrel 16 from the front. A frame body 20 which holds the lens 19 is vertically movable in the lens barrel 16 through a relay lens moving means 21. Further, the recessed part 20b of the frame body 20 engages the rib 16b of the lens barrel 16 and serves to guide the frame body 20 in its movement. Here, when the handle 24 of the moving means 21 is moved in a specific direction to shift the frame body 20, the lens 19 moves vertically at right angles to the optical axis C1 of the image formation optical system. This movement quantity is made variable to easily eliminate the Keystone distortion of the image on the screen.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a liquid crystal projector using a liquid crystal panel.

[Summary of the Invention] The present invention provides a liquid crystal projector in which a liquid crystal panel and a projection lens for projecting image light from the liquid crystal panel onto a screen via a relay lens are disposed on the optical axis of an imaging optical system. By arranging the relay lens so as to be movable in the vertical direction orthogonal to the optical axis, the angle formed by the optical axis of the projection lens and the normal to the screen on which this optical axis hits (hereinafter referred to as the projection angle) can be varied. This makes it possible to eliminate keystone distortion (trapezoidal distortion) of images on the screen.

[Conventional technology] CRT type projectors are generally known.

To explain this simply using Fig. 5, 30 is CR
It is a T-type projector, and this projector is 300C.
The optical axis C1 of the projection lens 32 that projects the image obtained on the RT 31 onto the screen S does not coincide with the normal C2 of the screen 22, which the front axis C1 hits, and the predetermined projection angle α (α
-5 to 15°). Therefore, C.R.T.
The image on screen 31 is made into a trapezoidal shape in advance, and an electric circuit or the like is used to correct it so that it becomes a regular square on screen S.

However, since the CRT 31 is large, a small liquid crystal projector using a thin liquid crystal panel has recently been developed in order to reduce the size of the projector 30 (for example, Japanese Patent Laid-Open No. 62-239678 etc.).

[Problem to be solved by the invention] In the liquid crystal projector using the above liquid crystal panel,
The outer shape of the image area on the above-mentioned liquid crystal panel that has a light valve function is rectangular, so it is extremely difficult to make it into a trapezoid, and the optical axis of the projection lens and the normal of the screen that this optical axis hits The angle formed by the projector (projection angle α) must be zero in order to eliminate trapezoidal distortion on the screen surface, but in this usage, the projector body gets in the way of the viewer, which is inconvenient.

Therefore, the present invention provides a liquid crystal projector that can vary the projection angle and cause keystone distortion of images on a screen.

[Means for Solving the Problems] A liquid crystal projector in which a liquid crystal panel and a projection lens for projecting image light from the liquid crystal panel onto a screen via a relay lens are arranged on the optical axis of an imaging optical system. The relay lens is arranged to be movable in the vertical direction perpendicular to the optical axis.

[Function] When the relay lens is moved in the vertical direction perpendicular to the optical axis of the imaging optical system, the angle formed by the optical axis of the projection lens and the normal to the screen that the front axis of this lens hits is changed, and the image on the screen is changed. keystone distortion is eliminated.

[Example] Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

1st. In Figure 4, l is a liquid crystal projector,
A condenser lens 4. The red light, blue light, and green light separated by the red reflective dichroic mirror 6 through the first polarizing plate 5 are transmitted to the mirror 7, the liquid crystal panel 8 for red color, and a pair of blue reflective dichroic mirrors 9.10. ．． Blue LCD panel 11
and a green liquid crystal panel 12. Mirror 13. After passing through the green reflecting dichroic mirror 14 and the second polarizing plate 15 into red image light, blue image light, and green image light, respectively, the light is transmitted to the screen S through the lens barrel 16 on the optical axis C of the imaging optical system. It is something that is synthesized.

The centers of the liquid crystal panels 8, 11, and 12 are located on the optical axis C of the imaging optical system.

Inside the lens barrel 16, a projection lens 1 is installed in order from the front.
7. It has a field lens 18, a relay lens 19, etc. Frame body 2 holding this relay lens 19
0 is connected to the lens barrel 1 via the relay lens movable means 21.
It is movable up and down within 6. The relay lens movable means 21 is rotatably supported on the outer side of a side wall 16a having a U-shaped cross section and projecting from one side of the lens barrel 16 via a shaft 23 having a bevel gear 22 at the tip. A shaft 26 having a handle 24 and a bevel gear 25 that meshes with the bevel gear 22 between the front and rear sides of the side wall 16a.
The rack 28 is provided in one of the recesses 20a and 20b formed on both sides of the frame body 20 and meshes with the pinion 27. ing.

Note that the projection lens 17. As the relay lens 19, a lens with a wide angle of view is used. The other concave portion 20b of the frame 20 is formed to protrude inside the other side of the lens barrel 16 and engages with the rib 16b, so that the frame 20 is attached to the lens barrel 1.
It serves as a guide when moving in the vertical direction of 6.

According to the liquid crystal projector l of the embodiment described above, normally the center of the liquid crystal panel 8, etc., the optical axis C1 of the relay lens 19 and the projection lens are in a straight line, and the center of the image on the screen S is also on the optical axis C1 of the projection lens. It is in. Here, when the handle 24 of the relay lens movable means 21 is rotated in a predetermined direction and the frame body 20 holding the relay lens I9 is shifted downward, that is, as shown in the principle diagram of FIG. When shifted downward in the vertical direction perpendicular to the optical axis C of the imaging optical system, the red color of each liquid crystal panel 8, 11, and 12 passes through the relay lens 19.

The blue and green image lights are focused below the optical axis C.

This image is formed again by the field lens 18. Projection lens 17
If the projection image is projected through the optical axis C, the projected image will be located above the optical axis C. Optical axis C of the projection lens 17 at this time
9 and the projection angle formed by the normal C2 of the screen S that this optical axis CI hits is α, then the center of the image is as if the projection angle α
It will be projected.

In this way, the projection angle α can be changed by a simple operation of moving the relay lens 19 in the vertical direction perpendicular to the optical axis C. By varying this projection angle α, even if the liquid crystal projector l is placed diagonally in front of the screen A and an image is projected onto the screen S, keystone distortion (trapezoidal distortion) of the image can be easily eliminated, and the projector The main body 2 does not get in the way of the viewer.

According to the embodiment, the relay lens 19 is made movable in the vertical direction perpendicular to the optical axis, but the projection angle α may be varied by making the projection lens 17 movable in the same direction.

Furthermore, although a case has been described in which three liquid crystal panels for red, blue, and green are used, it goes without saying that the relay lens may be made movable in a configuration using one liquid crystal panel.

[Effects of the Invention] As described above, according to the present invention, the relay lens is disposed so as to be movable in the vertical direction perpendicular to the optical axis of the imaging optical system, so that the optical axis of the projection lens and the forward axis thereof are aligned. It is possible to change the angle formed by the normal line of the screen, and
Keystone distortion in images on the screen can be eliminated.

[Brief explanation of the drawing]

FIG. 1 is a schematic plan view of a liquid crystal projector showing an embodiment of the present invention, and FIG. 2 is a plan view of the main parts of the projector.
FIG. 3 is a side view of the main parts of the projector, FIG. 4 is a principle diagram of the projector, and FIG. 5 is a schematic explanatory diagram of a conventional example. DESCRIPTION OF SYMBOLS 1...Liquid crystal projector, 8.11.12...Liquid crystal panel, 17...Projection lens, 19...Relay lens, C...Optical axis of imaging optical system, S...Screen. Figure 3

Claims (1)

[Claims] (1) In a liquid crystal projector in which a liquid crystal panel and a projection lens for projecting the image light of the liquid crystal panel onto the screen via a relay lens are arranged on the optical axis of the imaging optical system, A liquid crystal projector characterized by being arranged so as to be movable in the vertical direction perpendicular to the axis.