JP2601558B2 - LCD projector auto focus system - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an autofocus system for a liquid crystal projector in which liquid crystal panels of three primary colors R, G, and B are built, and in particular, focuses on one liquid crystal panel as a reference. In particular, the present invention relates to an autofocus system for a liquid crystal projector incorporating a unit for aligning the positions of the other two liquid crystal panels with a reference panel.

[Prior Art] As shown in FIG. 4, a liquid crystal projector P 'includes a light source 2 with a reflector 1, a cold mirror 3, a UV / IR filter 4, dichroic mirrors 5 and 6 for color separation,
Total reflection mirrors 7, 8 and liquid crystal panels 9R, 9G for the three primary colors R, G, B,
9B, condenser lenses 10 disposed on the entire surface of the liquid crystal panels 9R, 9G, 9B, and dichroic mirrors 11, 1 for color synthesis.
2 and a projection lens 13.

Then, the projection lens 13 was provided with an automatic focus adjustment device 16 of an infrared type, an ultrasonic type, a phase difference type or the like.

This autofocus device 16 is, for example, as shown in FIG.
The infrared ray is emitted from the light emitting section 16a and reflected on the screen 17, and the reflected infrared ray is received by the light receiving section 16b, and the angle θ
Is measured, and a servo system is driven to obtain a focus by a triangulation distance measuring system.

[Problems to be Solved by the Invention] As the liquid crystal projector has a large screen and high definition, the black matrix of the liquid crystal panel has become finer and difficult to be seen from a distance, and it has become difficult to grasp the focus / just point.

There is an auto focus system to accurately grasp the focus / just point. Focus system could not be obtained easily.

The present invention has been made in view of the above points, and achieves high quality autofocus by focusing on one reference liquid crystal panel and adjusting the positions of the other two liquid crystal panels to the positions of the reference liquid crystal panels. The aim is to get the system.

[Means for Solving the Problems] In order to solve the above problems, the present invention provides a method for
In a liquid crystal projector with built-in G and B color liquid crystal panels, reference focus means for adjusting the focus of one liquid crystal panel which is a reference by the servo system of the projection lens, and detecting the focus position of the reference liquid crystal panel It is characterized by comprising tracking focus means for adjusting the focus of the liquid crystal panel by a unique servo mechanism.

[Operation] 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 adjusting device 16.

The emitted infrared light is reflected by the screen 17 and received by the light receiving unit 16b.

Then, the angle θ between the incident angle and the output angle is measured, the distance 1 is detected based on the angle θ, and the servo mechanism built in the automatic focus adjustment device 16 is driven based on the detected value,
The focus of the projection lens 13 is adjusted. Projection lens 13
Is adjusted to the focus distance of the fixed liquid crystal panel 9R.

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

[Embodiment] Next, an embodiment of an autofocus system for a liquid crystal projector according to the present invention will be described in detail with reference to FIGS.

FIG. 1 is a schematic configuration 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, a UV / IR filter 4, dichroic mirrors 5 and 6 for color separation,
Total reflection mirrors 7, 8 and liquid crystal panels 9R, 9G for the three primary colors R, G, B,
9B, a condenser lens 10 disposed on each front face of each of the liquid crystal panels 9R, 9G, 9B, and a dichroic mirror 1 for color synthesis.
1 and 12, and a projection lens 13.

The liquid crystal panels 9G and 9B have position adjustment servo mechanisms 14G and 14B.
And liquid crystal surface distance measuring sensors 15G and 15B, respectively.

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

As the light source 2, for example, a high-luminance metal halide lamp in which a metal halide is sealed is used.

Then, the light emitted from the light source 2 and the reflector 1
Is reflected only by visible light by the cold mirror 3, and the heat ray is transmitted.

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

The light transmitted through the UV / IR filter 4 is reflected only by the dichroic mirror 5 in red, and the remaining light is transmitted.

The light reflected by the dichroic mirror 5 is reflected again by the total reflection mirror 7, then condensed by the condenser lens 10, transmitted through the liquid crystal panel 9R, transmitted through the dichroic mirrors 11 and 12 for color synthesis, and projected through the projection lens 13 Out.

The light transmitted through the dichroic mirror 5 is reflected only by the blue color on the dichroic mirror 6, and the remaining light is transmitted.

The light reflected by the dichroic mirror 6 is condensed by the condenser lens 10, passes through the liquid crystal panel 9 B, is reflected by the dichroic mirror 11 for color synthesis, is synthesized with red light, and is projected through the dichroic mirror 12.
It is emitted to 13.

The green light transmitted through the dichroic mirror 6 is condensed by the condenser lens 10, transmitted through the liquid crystal panel 9G, reflected by the total reflection mirror 8, and the dichroic mirror 12 for color synthesis, and is a combined light of red light and blue light. And is emitted to the projection lens 13.

The light that has entered the projection lens 13 is emitted as colorful image light to a screen 17 (see FIG. 2).

FIG. 2 is an explanatory diagram of a distance measuring system in the automatic focus adjustment device.

In FIG. 2, the automatic focus adjustment device 16 includes an infrared light projecting unit 16a and a light receiving unit 16b.

Then, the infrared light emitted from the light emitting unit 16a is reflected by the screen 17, and the reflected infrared light is received by the light receiving unit 16b.
The distance 1 is detected by measuring the angle θ. A servo mechanism incorporating the automatic focus adjustment device 16 is driven based on the detected value, and the focus of the projection lens 13 is adjusted.

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

 The reference liquid crystal panel 9R is fixed.

In the distance measuring system described above, the infrared ray is projected on the screen 17 and the reflected light is received. However, an ultrasonic wave instead of the infrared ray may be transmitted toward the screen 17 and the reflected sound may be received.

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

In FIG. 3, a liquid crystal surface distance measuring sensor 15G, 15B such as a CCD attached to the liquid crystal panels 9G, 9B measures the light receiving angle θ 'from the screen 17 and measures the distance l'.
Is detected.

Then, the position adjustment servo mechanism 14 is used in accordance with the detected value.
G, 14B are driven to adjust the focus of the liquid crystal panels 9G, 9B.

[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 positions of the other two liquid crystal panels with the reference liquid crystal panel. Means are provided.

Therefore, a high-quality image in which the focus of the three liquid crystal panels is uniform can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an example of an embodiment of an autofocus system for a liquid crystal projector according to the present invention.
FIG. 3 is an explanatory diagram of a distance measuring system in the automatic focus adjustment device, FIG. 3 is an explanatory diagram of a distance measuring system in a liquid crystal panel other than the reference liquid crystal panel, and FIG. 4 is a schematic configuration diagram of a conventional liquid crystal projector. P, P '... LCD projector 9R, 9G, 9B ... LCD panel 13 ... Projection lens 14G, 14B ... Position adjustment servo mechanism 15G, 15B ... LCD surface distance measurement sensor 16 ... Automatic focus adjustment device

Claims (1)

(57) [Claims] 1. A liquid crystal projector in which liquid crystal panels of R, G, and B colors are built in, reference focus means for adjusting focus of one liquid crystal panel serving as a reference in a servo system of a projection lens, and a reference liquid crystal panel. An autofocus system for a liquid crystal projector, comprising: a tracking focus means for detecting a focus position of the liquid crystal panel and adjusting a focus of the liquid crystal panel by a unique servo mechanism.