JP2009048042A - Projection video display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projection video display device which can alleviate or reduce a speckle noise peculiar to a laser beam, and also, which is advantageous from the view point of light use efficiency. <P>SOLUTION: In the projection video display device wherein the laser is used as an illumination light source, and the laser beams emitted from the laser beam sources 1r, 1g and 1b are modulated and projected through an optical system on the basis of a video signal, then, the video is enlarged and displayed, the projection type video display device includes an oscillating means (oscillation driving part 6) for oscillating the prescribed optical element (relay lens 42) constituting the optical system at high speed in an optical axis direction. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a projection display apparatus using a laser as a light source for illumination, and more particularly to reduction of laser speckle noise.

  In projection image display devices such as liquid crystal projectors, discharge lamps such as ultra-high pressure mercury lamps and metal halide lamps are generally used as illumination light sources. Instead, monochromatic light with high coherence and directivity is used. A projection-type image display device has been proposed that displays an enlarged image by using a laser of the above as an illumination light source, and modulating and projecting laser light emitted from the laser light source through an optical system based on an image signal. Yes.

  When a laser is used as a light source for illumination, even if a light beam is superimposed using a rod integrator, which is a light beam superimposing optical element, due to its high coherence, it is a visual problem called speckle noise on the projection screen. A very stimulating glare noise is observed.

  As a means for alleviating this phenomenon, a method of wobbling the projection screen itself has been proposed, but it is not realistic to wobble the front projection screen at high speed.

Patent Document 1 discloses a laser light source, a diffusion plate that diffuses light, an illumination optical system that irradiates the diffusion plate with light from the laser light source, and a diffusion plate swinging unit that swings the diffusion plate. And a spatial light modulator that modulates the light from the laser light source that is installed in the vicinity of the diffusion plate and diffused by the diffusion plate. Have been proposed that can be swung at a speed satisfying the relationship of V> d × 30 (millimeter / second) established between the particle size d and the swing speed V of the diffusion plate. Thus, according to the description in paragraph 0037 in the specification of Patent Document 1, speckle noise is suppressed by swinging the diffusion plate using the diffusion plate swinging portion. That is, the speckle pattern moves in parallel with the spatial light modulator due to the swinging of the diffusion plate, and the speckles in the observation image are averaged.
Table 2005/008330 (International Publication Number WO2005 / 008330)

  However, as described in Patent Document 1, in the method in which the optical element is swung in parallel with a plane orthogonal to the optical axis, there is a concern that the edge of the screen may become dark and chipped, and the light utilization efficiency may be increased. It is disadvantageous from the point of view.

  Accordingly, the present invention has been made to solve such problems, and can realize reduction / reduction of speckle noise peculiar to laser light, and is also advantageous from the viewpoint of light utilization efficiency. The object is to provide an apparatus.

  In order to achieve the above object, the invention according to claim 1 of the present application uses a laser as an illumination light source, and modulates laser light emitted from the laser light source based on a video signal through an optical system. In a projection type image display apparatus that displays an enlarged image by projecting, a swinging means for swinging a predetermined optical element constituting the optical system at a high speed in the optical axis direction is provided. It is.

  According to a second aspect of the present invention, in the optical axis direction, the oscillating means moves the optical element of the condensing / relay optical system installed between the laser light source and the superimposing optical element that superimposes the laser beam. The optical axis distance between the optical elements is changed at high speed by swinging at high speed.

  The invention according to claim 3 is a projection type for enlarging and displaying an image by using a laser as a light source for illumination and modulating and projecting laser light emitted from the laser light source based on an image signal through an optical system. The video display device is characterized in that it includes swinging means for swinging the laser light source at high speed in the optical axis direction.

  According to the first aspect of the present invention, the speckle noise peculiar to the laser beam can be reduced by providing the swinging means for swinging the predetermined optical element constituting the optical system at high speed in the optical axis direction. Reduction can be realized, and the oscillation direction is not parallel to the plane orthogonal to the optical axis but the optical axis direction, which is advantageous from the viewpoint of light utilization efficiency.

  Further, according to the second aspect of the invention, the oscillating means includes the optical element of the condensing / relay optical system disposed between the laser light source and the superimposing optical element for superimposing the laser beam on the optical axis. Since the optical axis distance between the optical elements is changed at a high speed by swinging in the direction at high speed, the inclination of the laser light incident on the superimposing optical element changes, and the superposition state of the laser beam changes. The cooperation with the superimposing optical element having a speckle noise mitigation function by superimposing the laser beam can efficiently realize the mitigation / reduction of speckle noise peculiar to the laser beam.

  On the other hand, by providing a swinging means for swinging the laser light source at high speed in the optical axis direction as in the invention described in claim 3, speckle noise peculiar to laser light can be reduced and reduced, and the swinging can be achieved. Since the moving direction is not parallel to the plane perpendicular to the optical axis but the optical axis direction, it is advantageous from the viewpoint of light utilization efficiency.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a configuration diagram showing a main part of a single-plate liquid crystal projector which is an embodiment of a projection display apparatus according to the present invention.

  The single-plate liquid crystal projector 100 of the present embodiment includes laser light sources 1r, 1g, and 1b, spherical combine lenses 2r, 2g, and 2b, a cross prism 3, relay lenses 41 and 42, a swing drive unit 6, The rod integrator 7, the condenser lens 8, the micro display 9, and the projection lens 10 are configured.

  The light sources 1r, 1g, and 1b are each composed of a semiconductor laser or the like that is a monochromatic laser with high coherence and directivity, and is provided for each of RGB colors (red, green, and blue).

  The combine lenses 2r, 2g, and 2b convert the laser beams from the laser light sources 2r, 2g, and 2b, which are point light sources, into diffused light of about ± 10 °, respectively.

  The cross prism 3 synthesizes the laser beams for the respective colors from the combine lenses 3r, 3g, 3b, and may be a cross mirror.

  The relay lenses 41 and 42 constitute a condensing / relay optical system 5 that condenses and guides the laser beam synthesized by the cross prism 3 to the incident surface of the rod integrator 7.

  The swing drive unit 6 swings the relay lens 42 in the optical axis direction at a high speed (wobbling), and can be realized by using a piezoelectric bimorph element or the like.

  The rod integrator 7 has an inner surface that is a reflection surface, and superimposes the incident light beam from the relay lens 42 while totally reflecting it, so that the illuminance of the laser light applied to the micro display 9 is made uniform over the entire surface.

  The condenser lens 8 condenses the laser beam emitted from the rod integrator 7 on the micro display 9.

  The micro display 9 is composed of a liquid crystal panel and generates image light by optically modulating laser light based on a video signal. The micro display 9 is synchronized with the laser light sources 1r, 1g, and 1b for each of the RGB colors. Split control is performed.

  The projection lens 10 projects and magnifies the image light generated by the microdisplay 9 on a screen (not shown).

  In the above configuration, the laser light emitted from the laser light sources 1r, 1g, and 1b for each color of RGB is converted into diffused light of around ± 10 ° by the combine lenses 2r, 2g, and 2b, respectively, and the cross prism 3 and the relay The light enters the rod integrator 7 through the lenses 41 and 42.

  At this time, the relay lens 42 arranged in the front stage of the rod integrator 7 is slightly swung at high speed in the optical axis direction by the swing driving unit 6, so that the optical axis distance between the relay lens 42 and the rod integrator 7 is high speed. The incident angle of the laser beam incident on the rod integrator 7 changes at a high speed.

  The laser beam incident on the rod integrator 7 is superimposed while being totally reflected in the rod integrator 7, but as described above, since the incident angle of the laser beam changes at a high speed, the superposition state also changes at a high speed.

  The laser beam superimposed and emitted by the rod integrator 7 is irradiated onto the micro display 9 by the condenser lens 8, where it is optically modulated based on the video signal to generate video light.

  The image light generated by the micro display 9 is projected on a screen (not shown) by the projection lens 10 and displayed in an enlarged manner.

  As described above, in the present embodiment, by providing the swing drive unit 6 that swings the relay lens 42 at high speed in the optical axis direction, it is possible to reduce and reduce speckle noise peculiar to laser light, Compared to the conventional method in which the optical element is oscillated parallel to a plane orthogonal to the optical axis, from the viewpoint of light utilization efficiency, it is more so-called to oscillate in the optical axis direction as in this embodiment. This is advantageous in that there is little occurrence of cracking.

  Further, the oscillation drive unit 6 moves the relay lens 42 of the condensing / relay optical system 5 installed between the laser light sources 1r, 1g, and 1b and the rod integrator 7 that superimposes the laser beam in the optical axis direction. Since the optical axis distance between the relay lens 42 and the rod integrator 7 is changed at high speed by oscillating at high speed, the inclination of the laser light incident on the rod integrator 7 changes and the superposition state of the laser beam changes. Therefore, the speckle noise peculiar to the laser beam can be efficiently reduced and reduced by the cooperative action with the rod integrator 7 having the speckle noise mitigation function by superimposing the laser beam.

  In this embodiment, the optical element (here, the relay lens 42) arranged at the rear stage of the RGB combining cross prism 3 is swung at high speed in the optical axis direction. The cost can be reduced because the unit 6 is sufficient.

  In the above embodiment, the relay lens 42 is slightly swung at high speed in the optical axis direction. However, the other optical elements constituting the optical system and the laser light sources 1r, 1g, 1b themselves are moved in the optical axis direction. Even if it is slightly swung at high speed, it is possible to expect almost the same effect as described above.

  FIG. 2 is a configuration diagram showing a main part of a three-plate liquid crystal projector which is another embodiment of the projection display apparatus according to the present invention.

  Since the liquid crystal projector 200 of the present embodiment is of a three-plate type, it has microdisplays (liquid crystal panels) 9r, 9g, and 9b for each of RGB colors, and the RGB prism cross prism 3 described above is arranged in the subsequent stage, Each RGB color is provided with an optical system from laser light sources 1r, 1g, 1b to condenser lenses 8r, 8g, 8b.

  Also in the above-described three-plate liquid crystal projector 200, the relay lenses 42r, 42g, and 42b for each of the RGB colors are provided with the swing driving units 6r, 6g, and 6b, and are swung slightly at high speed in the optical axis direction. It is possible to obtain substantially the same operation and effect as the single-plate liquid crystal projector 100 described above.

  The projection image display apparatus according to the present invention is not limited to a liquid crystal projector using a liquid crystal panel as a micro display as a light modulation means, but also in a projection image display apparatus having another image light generation system. Can be applied. That is, the present invention can be applied not only to the front projection type but also to the rear projection type image display device. The present invention can also be applied to projectors such as DLP (Digital Light Processing; registered trademark of Texas Instruments (TI)).

The block diagram which shows the principal part of the single-plate-type liquid crystal projector which is one Embodiment of the projection type video display apparatus concerning this invention. The block diagram which shows the principal part of the 3 plate-type liquid crystal projector which is other embodiment of the projection type video display apparatus concerning this invention.

Explanation of symbols

1r, 1g, 1b Laser light source 2r, 2g, 2b Combine lens 3 Cross prism 41, 42, 41r, 41g, 41b, 42r, 42g, 42b Relay lens 5, 5r, 5g, 5b Condensing / relay optical system 6, 6r , 6g, 6b Oscillating drive unit 7, 7r, 7g, 7b Rod integrator 8, 8r, 8g, 8b Condenser lens 9, 9r, 9g, 9b Micro display 10 Projection lens

Claims (3)

In a projection-type image display apparatus that displays an enlarged image by using a laser as a light source for illumination and modulating and projecting laser light emitted from the laser light source based on an image signal through an optical system,
A projection-type image display apparatus comprising a swinging means for swinging a predetermined optical element constituting the optical system at high speed in the optical axis direction.   The oscillating means oscillates the optical element of the condensing / relay optical system installed between the laser light source and the superimposing optical element for superimposing the laser beam at high speed in the optical axis direction, The projection display apparatus according to claim 1, wherein the optical axis distance between the elements is changed at high speed. In a projection-type image display apparatus that displays an enlarged image by using a laser as a light source for illumination and modulating and projecting laser light emitted from the laser light source based on an image signal through an optical system,
A projection-type image display apparatus comprising swing means for swinging the laser light source at high speed in the optical axis direction.