JPH0480736A - Automatic focusing system for liquid crystal projector - Google Patents

Abstract

PURPOSE:To obtain a high-definition image by taking focus by one sheet of reference liquid crystal panel and aligning the positions of the other two sheets of liquid crystal panels with the position of the reference liquid crystal panel. CONSTITUTION:A means which takes the focus of one sheet of the reference liquid crystal panel and aligns the positions of the other two sheets of liquid crystal panels with the reference liquid crystal panel is provided. That means, infrared rays projected from a light projection part 16a are reflected on a screen 17 and the reflected infrared rays are received by a light receiving part 16b. Then, the angle (theta) thereof is measured and the distance (l) thereof is detected. According to the detected value, a servo mechanism incorporated in an automatic focusing device 16 is driven and the focus of a projection lens 13 is adjusted. The focus of the lens 13 is adjusted to the focusing distance of the reference liquid crystal panel 9R. Thus, the high-definition image that the focus of three sheets of liquid crystal panels is aligned.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an autofocus system for a liquid crystal projector that has built-in liquid crystal panels for three primary colors R, G, and B, and in particular, it relates to an autofocus system for a liquid crystal projector that has built-in liquid crystal panels for three primary colors R, G, and B. The present invention relates to an autofocus system for a liquid crystal projector incorporating a means for aligning two other liquid crystal panels with a reference panel.

[Background Art] As shown in FIG. 4, a liquid crystal projector P' includes a light source 2 with a reflector 1, a cold mirror 3,
R filter 4 and dichroic mirror 5 for color separation.
6, a total reflection mirror 7.8, liquid crystal panels 9R, 9G, and 9B for the three primary colors R, G, and B, and a liquid crystal panel 9R.
, 9G, and 9B, and dichroic mirrors 11 and 12 for color synthesis.
and a projection lens 13.

The projection lens 13 was equipped with an automatic focus adjustment device 16 using an infrared method, an ultrasonic method, a phase difference method, or the like.

This automatic focusing device [16, for example, as shown in FIG.
Infrared rays are emitted from the light emitter 16a and reflected on the screen 17, the reflected infrared rays are received by the light receiver 16b, the angle θ is measured, the servo system is driven, and the focus is taken before distance measurement for triangulation. It depends on the system.

[Question H that the invention aims to solve] As liquid crystal projectors have become larger and higher in definition, the black matrix of the liquid crystal panel has become finer, making it difficult to see from a distance, making it difficult to find the right focus point. .

Focus Autofocus is used to accurately find the right point, but due to variations in the position of the three primary color LCD panels in LCD projectors, variations in the back focus of the projection lens, and variations in the tolerances of the autofocus system, high-quality autofocus is required. The focus system was difficult to obtain.

This invention was made in view of the above points, and it achieves high-quality autofocus by taking focus with one reference liquid crystal panel and aligning the positions of the other two liquid crystal panels with the position of the reference liquid crystal panel. The purpose is to obtain a system.

[Means for solving the problem] In order to solve the above problems, in this invention, R,
In a liquid crystal projector with a built-in liquid crystal panel for G and B colors, there is a reference focusing means that adjusts the focus of one liquid crystal panel that serves as a reference in the servo system of the projection lens, and a reference focusing means that detects the focus position of the reference liquid crystal panel. This is characterized by comprising a follow-up focus means for adjusting the focus of the liquid crystal panel using a unique servo mechanism.

[Function] In FIGS. 1 to 3 showing the embodiment, infrared rays are projected toward the screen 17 from the light projecting section 16a of the automatic focus adjustment device 16.

The projected infrared rays are reflected by the screen 17 and received by the light receiving section 16b.

Then, the angle θ formed by the incident angle and the exit angle is measured, and the distance 9 is detected based on the angle θ, and the servo mechanism built in the automatic focus adjustment device 16 is driven by the detected value.
The focus of the projection lens 13 is adjusted. The focus of the projection lens 13 is adjusted to the focus distance of the fixed liquid crystal panel 9R.

Further, the angle of light reception θ' from the screen 17 is measured by sensors 15G and 15B of the liquid crystal surface distance measuring instruments attached to the liquid crystal panels 9G and 9B, and the distance Ω' is detected. The position adjustment servo mechanisms 14G and 14B are driven by the detected value, and the scum of the liquid crystal panels 9G and 9B is adjusted.

[Example] Next, an example of the implementation of the autofocus system for a liquid crystal projector according to the present invention will be described with reference to FIGS. 1 to 3.
This will be explained in detail with reference to the figures.

FIG. 1 is a schematic diagram of a liquid crystal projector incorporating an autofocus system according to the present invention.

In FIG. 1, a liquid crystal projector-P includes a light source 2 with a reflector 1, a cold mirror 3, and a UV/IR
Filter 4 and dichroic mirror 5.6 for color separation
, a total reflection mirror 7.8, liquid crystal panels 9R, 9G, and 9B for primary colors R, G, and B, and each liquid crystal panel 9R7.
Condenser lens 10 placed on each front of 9G and 9B
, dichroic mirrors 11 and 12 for color synthesis, and a projection lens 13.

The liquid crystal panels 9G and 9B have a position adjustment servo mechanism 14.
G, 14B and LCD surface distance measuring sensor 15G, 15B
are attached to each.

Further, the projection lens 13 is equipped with an automatic focus adjustment device 16.

As the light source 2, for example, a high-intensity metal halide lamp containing a metal halide is used.

Of the light emitted from the light 2112 and the light reflected by the reflector 1, only the visible light is reflected by the cold mirror 3, and the heat rays are transmitted.

The UV/IR filter 4 removes ultraviolet rays and infrared rays from the light reflected by the cold mirror 3.

After passing through the UV/IR filter 4, only the red light is reflected by the clock mirror 5, and the remaining light is transmitted.

The light reflected by the dichroic mirror 5 is reflected again by the total reflection mirror 7, condensed by the condenser lens 10, transmitted through the liquid crystal panel 9R, and transmitted through the dichroic mirror 1112 for color synthesis to the projection lens 13. Emits light.

It was. The light transmitted through the dichroic mirror 5 is reflected only in blue by the dichroic mirror 6, and the remaining light is transmitted.

The light reflected by the dichroic riff mirror 6 is a condenser g
The light is collected by a lens 10, transmitted through a liquid crystal panel 9B, reflected by a dichroic mirror 11 for color synthesis, combined with red light, transmitted through a dichroic mirror 12, and outputted by a projection lens 13.

The colored light transmitted through the dichroic mirror 6 is condensed by a condenser lens 10, passes through a liquid crystal panel 9G, and then passes through a total reflection mirror 8 and a dichroic mirror 1 for color synthesis.
2, is combined with a composite light of red light and blue light, and is emitted to the projection lens 13.

The light incident on the projection lens 13 passes through the screen 17 (second
(see figure) is emitted as colorful image light.

FIG. 2 is an explanatory diagram of the pre-rangefinding system in the automatic focus adjustment device.

In FIG. 2, the automatic focus adjustment device 16 is equipped with an infrared light projecting section 16a and a light receiving section 16b.

The infrared rays projected from the light projecting section 16a are reflected by the screen 7, the reflected infrared rays are received by the light receiving section 16b, and the distance NQ is detected by measuring the angle θ. The detected value drives a servo mechanism built into the automatic focus adjustment device 16 to adjust the focus of the projection lens 13.

The focus of this projection lens 13 is adjusted to the focus distance of the reference liquid crystal panel 9R.

This reference liquid crystal panel 9R is fixed.

In the above-mentioned pre-distance measurement system, infrared rays are emitted onto the scree shear and the reflected light is received, but instead of infrared rays, ultrasonic waves may be emitted toward the screen 17 and the reflected sound may be received. .

FIG. 3 is an explanatory diagram of a pre-distance measurement system in a liquid crystal panel other than the reference liquid crystal panel.

In FIG. 3, a distance 9' is detected by measuring the angle θ' of light reception from the screen 17 with a CCDCD isometric liquid crystal surface layer distance sensor 15G5B attached to the panel surface of the liquid crystal panels 9G, 9B.

Then, based on the detected value, the position adjustment servo mechanism 14
G and 14B are driven to adjust the focus of the liquid crystal panel 909B.

[Effects of the Invention] As described above, the autofocus system for a liquid crystal projector according to the present invention focuses on one reference liquid crystal panel and aligns the other two liquid crystal panels to the reference liquid crystal panel. A means for matching is provided.

Therefore, a high-quality image with the three liquid crystal panels in focus can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing an example of implementation of an autofocus system for a liquid crystal projector according to the present invention, and FIG.
The figure is an explanatory diagram of the pre-distance measurement system in the automatic focus adjustment device, Figure 3 is an explanatory diagram of the pre-distance measurement system in liquid crystal panels other than the standard liquid crystal panel, and the fourth section is a schematic configuration diagram of a conventional liquid crystal projector. be. P, P' 9R, 9G, 9B 14G, 14B 15G, 15B ・LCD projector - Servo mechanism for adjusting the position of the LCD panel projection lens.LCD surface distance measurement limit month sensor automatic focus adjustment device!

Claims (1)

[Claims] (1) In a liquid crystal projector with a built-in liquid crystal panel for each color of R, G, and B, there is a reference focusing means for adjusting the focus of one liquid crystal panel that serves as a reference in the servo system of the projection lens, and a focus of the reference liquid crystal panel. An autofocus system for a liquid crystal projector comprising a follow-up focus means that detects the position and adjusts the focus of the liquid crystal panel using a unique servo mechanism.