JP3037028B2 - Image projection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image projection apparatus such as a liquid crystal projector, and more particularly to an image projection apparatus using a reflection type liquid crystal panel.

[0002]

2. Description of the Related Art An image projection apparatus of this kind has already been disclosed in
-13385 and the like. Here, the illumination light projection direction and the reflected light emission direction from the liquid crystal panel are the same,
The illumination light and the reflected light were separated by a beam splitter.

[0003]

However, in the above-mentioned conventional example, since a prism processed product such as a beam splitter is used, there is a drawback that the cost becomes extremely high.

[0004]

According to the present invention, there is provided an image projection apparatus using a reflection type liquid crystal panel.
Optical axis of illumination system for illuminating light and reflected light from liquid crystal panel
The optical axis of the projection system for projecting the form a predetermined angle, and the viewing angle characteristics of the liquid crystal panel in a direction along a plane containing the optical axis of the projection system and the optical axis of the <br/> illumination system and wide direction matches
And said that you are.

[0005]

FIG. 1 shows a basic configuration of an embodiment of the present invention. Here, reference numeral 2 denotes a light source composed of a lamp 2a and a reflector 2b, which illuminates the reflective liquid crystal panel 1. The liquid crystal panel 1 reflects image light by controlling the reflected light of each pixel according to an image signal and a video signal, and reflects the reflected light (image light) through a projection lens 3 to a screen or the like (not shown). The projection is enlarged.

FIG. 2 is a top view of the liquid crystal panel 1, and 6 schematically shows liquid crystal molecules therein. This liquid crystal panel is a reflection type liquid crystal panel using TN liquid crystal, and its liquid crystal molecules 6 are tilted as shown in FIG. Arrows EF and GH indicate the directions of the polarization axes of the upper and lower deflecting plates, respectively, and arrows AB and CD indicate the horizontal and vertical directions of the panel 1, respectively. Further, a reflection plate is provided further below the lower polarizing plate.

FIGS. 3 and 4 show viewing angle characteristics of the liquid crystal panel 1 in the AB and CD directions, respectively. In the case of tilting liquid crystal molecules as described above, a wider viewing angle characteristic can be obtained in the CD direction. Here, the viewing angle characteristic refers to the relationship between the incident angle of illumination light and the contrast, and the case where the incident angle indicates a negative value means that the incident side and the reflection side are reversed.

In this embodiment, as shown in FIG. 1, the CD direction of the liquid crystal panel 1 having a wide viewing angle characteristic coincides with the direction along the plane formed by the illumination light optical axis 4 and the reflected light optical axis 5. It is composed. Therefore, in this example, a projected image with high contrast is obtained even though the illumination light optical axis 4 and the reflected light optical axis 5 have a predetermined angle. In this embodiment, the incident angle of the illumination light is preferably equal to or less than 20 ° as shown in FIG.

By the way, in this embodiment, it is possible to cope with full color by using a liquid crystal panel provided with a mosaic color filter. The use of a monochrome liquid crystal panel and a color separation / color synthesis optical system can also support full color.

The reflection type liquid crystal panel that can be used here is not limited to the TN liquid crystal used in the present embodiment, but may be an HFE mode liquid crystal, a ferroelectric liquid crystal, or the like.

[0011]

As described above, according to the first aspect of the present invention,
According to Ming, the plane containing the optical axis of the illumination system and the optical axis of the projection system
The direction along which the viewing angle characteristics of the reflective LCD panel
The match provides the desired contrast.
The angle between the optical axis of the illumination light and the optical axis of the reflected light
Can be used to separate illumination and reflected light.
A prism-processed product such as a beam splitter is not required, and an image projection device with good image quality can be configured at low cost.

[Brief description of the drawings]

FIG. 1 is a basic configuration diagram showing an embodiment of an image projection apparatus according to the present invention.

FIG. 2 is a top view of the reflective liquid crystal panel of FIG.

FIG. 3 is a diagram showing viewing angle characteristics of a reflective liquid crystal panel.

FIG. 4 is a diagram showing viewing angle characteristics of a reflective liquid crystal panel.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Reflective liquid crystal panel 2 ... Light source 3 ... Projection lens 4 ... Illumination optical axis 5 ... Reflection optical axis 6 ... Liquid crystal molecules

Claims (1)

(57) [Claims] 1. An image projection apparatus using a reflection type liquid crystal panel, wherein an optical axis of an illumination system for illuminating the liquid crystal panel is in front of the optical axis.
The optical axis of the projection system that projects the reflected light from the liquid crystal panel is
Forms a constant angle, and that the broad direction matches the viewing angle characteristics of the liquid crystal panel in a direction along a plane including the <br/> optical axis of the projection system and the optical axis of the illumination system Characteristic image projection device.