JP2837919B2 - LCD projector - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal projection device for enlarging and projecting an image formed on a liquid crystal panel using a zoom lens.

[Related Art] A liquid crystal projection device such as a liquid crystal projector is a device for optically enlarging an image projected on a liquid crystal and projecting it on a screen, and is used as a device capable of forming a large image.

A conventional liquid crystal projection device will be described with reference to the drawings. Third
FIG. 4 shows a prior art, FIG. 3 is a conceptual diagram showing a schematic configuration of the entire liquid crystal projection device, and FIG. 4 is a partially enlarged plane near a green liquid crystal panel located at the center of FIG. FIG.

3, reference numeral 1 denotes a screen for projecting projected image light, 7 denotes a liquid crystal panel for blue (B), 8 denotes a liquid crystal panel for green (G), and 9 denotes a liquid crystal panel for red (R). It is. The liquid crystal panels 7 to 9 of the respective colors form images based on image signals (R, G, B signals) from an image signal source (not shown). Reference numeral 6 denotes a dichroic prism arranged on the front of the liquid crystal panels 7 to 9, which is used for performing color synthesis. Instead of the dichroic prism 6, a dichroic mirror can be used. Ten
Denotes an imaging optical zoom unit (projection lens) in which the imaging optical system and the zoom unit are integrated. The imaging optical zoom unit 10 serves to optically magnify the image synthesized by the dichroic prism 6 and display the image on a screen. In addition, well-known backlights (projection light sources) are disposed on the back sides of the liquid crystal panels 7 to 9, respectively.

The operation of the prior art shown in FIG. 3 configured as described above will be described below.

Based on the image signals, the liquid crystal panels 7 to 9 form images of respective tones, project the images with a backlight,
Color synthesis is performed by the dichroic prism 6 arranged on the front of each liquid crystal panel. The image color-combined by the dichroic prism 6 is then optically enlarged by the imaging optical zoom unit 10 and is displayed on a screen.

[Problems to be Solved by the Invention] However, in the above-described liquid crystal projection device of the related art, the dichroic prism 6 must be disposed between the liquid crystal panels 7 to 9 and the imaging optical zoom unit 10, so As shown in the figure, the distance from the final surface of the imaging optical zoom unit 10 to the liquid crystal panel 8 (back focus, BF)
Therefore, there is a problem that it is difficult to shorten the focal length f of the imaging optical zoom unit 10. Also, the final surface of the imaging optical zoom unit 10 and the liquid crystal panel 7
Arranging a component for color synthesis (for example, the dichroic prism 6) between the components 9 to 9 requires that the component for color synthesis pass a light flux that covers the effective display area of the liquid crystal panels 7 to 9, There was also a problem that the components for color synthesis had to be enlarged.

An object of the present invention is to solve such a conventional problem, and an object of the present invention is to provide a liquid crystal projection device having a short focal length and a reduced size of a component for color synthesis.

[Means for Solving the Problems] In order to achieve the above object, a liquid crystal projection device of the present invention comprises:
At least red, which forms an image corresponding to the R, G, B color signals,
Liquid crystal panels for green and blue, an imaging optical system arranged on the front of each liquid crystal panel and corresponding to each color image of each liquid crystal panel, and a color for synthesizing image light passing through each imaging optical system A combination dichroic prism and an afocal zoom unit for enlarging color-combined image light are provided.

[Operation] According to the configuration of the present invention described above, at least the image forming optical system corresponding to each color image of each of the liquid crystal panels for red, green, and blue is converted into an image passing through these liquid crystal panels and the image forming optical system. Between the projection lens of the imaging optical system and the liquid crystal panel because it is arranged between the liquid crystal panel and the color synthesizing dichroic prism for synthesizing the colors of
The back focus (BF) of the projection lens of the imaging optical system can be reduced, and the focal length (f) of the projection lens of the imaging optical system can be easily reduced. As a result, it is possible to provide a liquid crystal projector in which optical components for color synthesis are miniaturized.

[Embodiment] Hereinafter, a liquid crystal projection device according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a plan view showing a schematic configuration of a liquid crystal projection device according to one embodiment of the present invention, and FIG. 2 is a partially enlarged plan view showing a portion near a green liquid crystal panel located at the center of FIG.

In FIG. 1, 1 is a screen for projecting a projected image, 7 is a liquid crystal panel for blue (B), 8 is a liquid crystal panel for green (G), and 9 is a liquid crystal panel for red (R). is there. In the liquid crystal panels 7 to 9 of each color,
An image is formed based on the R, G, and B image signals.
Reference numeral 3 denotes an imaging optical system arranged on the front surface of the blue liquid crystal panel 7 and corresponding to blue image light of the liquid crystal panel 7. 4
Reference numeral denotes an image forming optical system which is disposed on the front surface of the liquid crystal panel 8 for green and corresponds to green image light of the liquid crystal panel 8. Reference numeral 5 denotes an image forming optical system which is arranged on the front surface of the liquid crystal panel 9 for red and corresponds to the red image light of the liquid crystal panel 9. 11R, 1
1G and 11B are backlights for projecting images formed on the liquid crystal panels 7 to 9, respectively.

Next, reference numeral 6 denotes a color synthesizing dichroic prism arranged on the front surface of the imaging optical systems 3 to 5, and is used for performing color synthesis. Reference numeral 2 denotes an afocal zoom unit, which optically magnifies the image synthesized by the dichroic prism 6,
Plays the role of projecting on the screen. The afocal zoom unit 2 refers to an optical system that emits light in parallel and emits light in parallel, and has a zoom function. And
An optical system that enters light in parallel and emits light in parallel refers to an optical system that does not form an image inside the optical system, such as when a person looks at a distant object with binoculars.

The operation of the configuration of the embodiment of the present invention will be described below.

That is, the image light output from the three liquid crystal panels 7, 8, and 9 of R, G, and B is an image forming optical system corresponding to each of R, G, and B.
The light enters 3, 4 and 5 and is converted into parallel light, and then enters a dichroic prism 6 for color synthesis. The dichroic prism 6 combines the R, G, and B lights. The synthesized light enters the afocal zoom unit 2, where the light flux is converted and projected on the screen 1.

For example, in the light path for green, light that has exited the liquid crystal panel 8 for green enters the imaging optical system 4 for green, becomes parallel light, and enters the dichroic prism 6 for color synthesis. The green light is transmitted through the dichroic prism 6 and the afocal zoom unit 2
The light flux is converted and projected on the screen 1.

Similarly, in the blue light path, the light that has exited the blue liquid crystal panel 7 enters the blue imaging optical system 3, becomes parallel light, and enters the color synthesizing dichroic prism 6. The blue light is reflected by the dichroic prism 6, enters the afocal zoom unit 2, converts the light beam, and projects the light beam on the screen 1.

Similarly, in the light path for red, the light that has exited the liquid crystal panel 9 for red enters the imaging optical system 5 for red, becomes parallel light, and enters the dichroic prism 6 for color synthesis. The red light is reflected by the dichroic prism 6 and the afocal zoom unit 2
The light flux is converted and projected on the screen 1.

According to the liquid crystal projector of one embodiment of the present invention described above,
Since there is no need to dispose essential components between the liquid crystal panels 7 to 9 and the imaging optical systems 3 to 5, as shown in FIG. (Back focus, BF) can be made short, and the focal length f of the imaging optical system 4 can be shortened. In addition, since it is not necessary to dispose essential components between the final surfaces of the imaging optical systems 3 to 5 and the liquid crystal panels 7 to 9, a liquid crystal projection device in which color synthesizing components (the dichroic prism 6) are miniaturized. It can be.

As described above, since the position of the dichroic prism 6 is close to the stop of the projection lens, the light beam is thin, and the size of the dichroic prism can be reduced.

[Effects of the Invention] According to the present invention, at least liquid crystal panels for red, green, and blue, an imaging optical system arranged on the front surface of each liquid crystal panel, and corresponding to each color image of each liquid crystal panel; It has a dichroic prism for color synthesis for synthesizing the color of the image that has passed through the image optical system, and an afocal zoom unit for enlarging the color synthesized image. The back focus (BF) of the projection lens of the imaging optics because the space between the panels is freely determined
And the focal length of the projection lens of the imaging optical system (f)
It is easy to reduce the size of the liquid crystal projection device, and it is possible to achieve an excellent effect that a liquid crystal projection device in which components for color synthesis can be downsized.

[Brief description of the drawings]

FIG. 1 is a plan view showing a schematic configuration of a liquid crystal projection device according to one embodiment of the present invention, FIG. 2 is a partially enlarged plan view near a liquid crystal panel located at the center of FIG. 1, and FIG. FIG. 4 is a plan view showing a schematic configuration of the entire device, and FIG. 4 is a partially enlarged plan view near a liquid crystal panel located at the center of FIG. 1 ... Screen, 2 ... Afocal zoom section, 3 ...
... blue imaging optical system, 4 ... green imaging optical system, 5 ... red imaging optical system, 6 ... color combining dichroic prism,
7 ... Blue liquid crystal panel, 8 ... Green liquid crystal panel, 9 ...
LCD panel for red, 11 ... Backlight.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI G09F 9/00 360 H04N 5/74 A H04N 5/74 K G02B 7/04 Z

Claims (1)

(57) [Claims] 1. A liquid crystal projection device for enlarging an image formed on a liquid crystal panel based on a video signal from a video signal source and projecting the enlarged image onto a screen, wherein a color signal from the video signal source is supplied to each color signal. A liquid crystal panel for at least red, green, and blue on which a corresponding image is formed, and an optical image projected by light from a light source disposed on the front side of each of the liquid crystal panels and disposed on the back side of the liquid crystal panel. An image forming optical system for forming an image, a color synthesizing dichroic prism for synthesizing optical signals corresponding to the respective colors passing through the image forming optical systems, and an amplifying device for enlarging the color synthesized image light signal. A liquid crystal projection device comprising a focal zoom unit.