JP2010044309A - Laser image projecting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser image projecting device capable of heightening light utilization efficiency by reducing a speckle noise generated from coherency of a laser. <P>SOLUTION: A light source 1 is vibrated by a vibration generation means 2 in order to reduce a speckle noise generated from coherency of the laser, and, while reducing with a speckle noise pattern averaged in time, a lens 5 is moved continuously and synchronously with vibration so as to correct deviation of an optical axis of the light source 1 generated by the vibration generation means 2, to thereby heighten the light utilization efficiency. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a laser image projector.

  The present invention relates to a laser image projector, and more particularly to a light illumination technique for a laser image projector.

  The present invention relates to a laser image projection apparatus, and particularly suitably used for irradiating a spatial light modulation element with high efficiency with laser light emitted from a light source while reducing speckle noise generated due to coherency of the laser. It can be done.

  In recent years, new color expression gamut standards such as the xvYCC color gamut have been developed due to the growing need to expand the color gamut from the conventional NTSC color gamut and display images closer to natural colors in image projection devices. is there. As a technique for complying with such a new color gamut standard, a laser having a wide single color gamut of three primary colors of light, red (hereinafter R), green (hereinafter G), and blue (hereinafter B). Attention has been focused on using light as a light source. Hereinafter, the three primary colors of light are denoted as RGB.

  However, if laser light is simply used as the light source, the image called speckle noise generated due to the coherent nature of the laser light will be glaring or random granular unevenness may occur, reducing the quality of the projected image. . Therefore, a technique for reducing speckle noise is an important technique in a laser image projector.

The illumination technology for reducing speckle noise in a conventional laser image projection apparatus is simply a light source, a spatial modulation element that spatially modulates incident light in accordance with an input signal, and illuminance on the element surface of the spatial modulation element In order to uniformly illuminate the light from the light source, the light incident on the light source is homogenized to uniformly convert the light amount distribution on the exit opening surface perpendicular to the optical axis, or the light from the light source to the integrator. Or a relay lens that adjusts the irradiation range to the surface of the spatial modulation element by refracting the light that is leveled by an integrator and refracted and emitted (for example, patent document) 1)
Japanese Patent Laid-Open No. 2005-10772

  However, in the conventional configuration, for example, the light source or the optical component is simply vibrated by the vibration generating means, and the speckle noise pattern is temporally changed to reduce the speckle noise. The problem in the conventional method when the speckle noise is reduced by vibrating is described. If the light source vibrates in the direction perpendicular to the optical axis due to the vibration of the vibration generator, the optical axes of the light source and the integrator are misaligned, and the light from the light source does not enter the integrator opening sufficiently. Accordingly, since the light quantity to the integrator changes with vibration, the light quantity illuminated on the element surface of the spatial modulation element changes with time. Eventually, the light quantity fluctuation of the projected image occurs, and the quality of the projected image is impaired.

  In addition, a problem with the conventional method in the case of reducing speckle noise by vibrating one integrator of an optical component will be described.

As mentioned above, the integrator uniformly illuminates the incident light on the element surface of the spatial modulation element as described above, so that the incident light is uniformed and the light quantity distribution is uniformly converted at the exit opening surface perpendicular to the optical axis. The light leveled by the integrator illuminates the element surface of the spatial modulation element that forms an image by spatially modulating the light according to the input signal by the relay lens.
Therefore, when the integrator vibrates, the illumination range on the element surface of the spatial modulation element changes, and when projected onto the screen, part of the information of the spatial modulation element is not projected and displayed, and the quality of the projected image is impaired.

  In order to prevent vignetting of illumination on the element surface of the spatial modulation element due to the vibration of the integrator, vignetting will theoretically occur if the area of the exit opening of the integrator is set to a size that does not generate vignetting even if the integrator vibrates. However, the problem in that case is that the integrator becomes larger, causing a variation in the amount of light on the exit aperture surface of the integrator, resulting in variations in the illuminance on the element surface of the spatial modulation element, and finally the projected image Brightness unevenness occurs.

  Furthermore, since the luminous flux density on the exit aperture surface is reduced by increasing the opening of the integrator, the luminous flux density on the element surface of the spatial modulation element is also lowered, and the projected image becomes dark.

In addition, the light from the integrator also hits the part where light does not pass on the element surface of the spatial modulation element, which causes the temperature of the spatial modulation element to rise and cause thermal damage. Problems arise such as stray light due to reflected light.
Furthermore, as the size of the integrator increases, the cost of the integrator itself increases, and the relay lens that illuminates the spatial modulation element with light from the integrator also increases, resulting in an increase in the optical unit.

  As the integration becomes larger, the vibration generating means that vibrates also increases, so that the vibration of the optical unit is transmitted to the housing and the entire set vibrates.

  As described above, when taking measures against speckles, the above-described problems are caused by vibrating the light source and the integrator.

  The present invention solves the above-mentioned conventional problems. When the light source vibrates, the lens between the light source and the integrator is vibrated to correct the light from the light source to illuminate the central part of the integrator. On the other hand, the relay lens is vibrated to always correct the optical axis so that the illumination range and the light amount on the element surface of the spatial modulation element are made constant.

  In this way, the laser image that corrects the optical axis misalignment caused by the deviation of the center axis between the optical components due to the vibration of the light source and the integrator, eliminates the vignetting of the projected image and the fluctuation of the light amount, and reduces the speckle noise. An object is to provide a projection device.

  In order to solve the above-described conventional problems, a laser image projector according to the present invention includes a light source that generates laser light, vibration generation means that vibrates the light source, and spatial modulation of light from the light source according to an input signal. A spatial modulation element that forms an image, and an exit opening that is perpendicular to the optical axis by equalizing the light incident from the light source in order to illuminate the light from the light source uniformly with the illuminance of the element surface of the spatial modulation element In a laser image projection apparatus comprising an integrator that uniformly converts a light amount distribution on a surface and a lens that illuminates the integrator with light from the light source, to the integrator that is generated when the light source is vibrated by the vibration generating means The incident position deviation of the light from the light source is corrected by vibrating the lens.

  Further, in the laser image projection device, when the light source vibrates in a direction perpendicular to the optical axis, the lens also follows the light source and vibrates in a direction perpendicular to the optical axis. It is characterized by correcting the deviation of the incident position of light.

Further, when the light source vibrates in the optical axis direction, the lens also follows the light source and vibrates in the optical axis direction or continuously in synchronization with the vibration of the light source, and from the light source to the integrator It is characterized by correcting the deviation of the incident position of the light.
Further, the lens condenses or collimates light generated from the light source with respect to the integrator.

  Furthermore, a diffusing element or diffusing means is disposed between the lens and the integrator, and the light from the light source is diffused and incident on the integrator.

  Further, in order to reduce the speckle of the laser, it is necessary to vibrate the light source by the vibration generating means at a speed faster than human eyes can see, and the vibration period is made to vibrate at 30 Hz or more. It is.

  The present invention also provides a light source that generates laser light, a spatial modulation element that spatially modulates light from the light source according to an input signal, and forms an image; and the illuminance on the element surface of the spatial modulation element is uniform. The light incident from the light source to illuminate the light from the light source, and uniformizing the light quantity distribution on the exit opening surface perpendicular to the optical axis, the vibration generating means for vibrating the integrator, and the light source In the laser image projection apparatus comprising: a lens that illuminates the integrator with the light; and a relay lens that refracts the light that has been homogenized by the integrator and adjusts the irradiation range onto the spatial modulation element surface. The incident position shift of the light from the integrator to the surface of the spatial modulation element generated when vibrating by the vibration generating means, It is obtained by and corrects vibrate the Rerenzu.

  Further, in the laser image projection apparatus, when the integrator vibrates in the direction perpendicular to the optical axis, the relay lens also follows the integrator and vibrates in the direction perpendicular to the optical axis to the element surface of the spatial modulation element. The incident position deviation of the light from the integrator is corrected.

  When the integrator vibrates in the optical axis direction, the relay lens also follows the integrator and vibrates in the optical axis direction or continuously vibrates in synchronism with the vibration of the integrator to the element surface of the spatial modulation element. The incident position deviation of the light from the integrator is corrected.

  Furthermore, in order to reduce the speckle noise of the laser beam, the integrator needs to be vibrated by the vibration generating means at a speed faster than human eyes can see, and the vibration period is made to vibrate at 30 Hz or more. It is a thing.

  Further, the light source and the integrator are configured as one unit, and the positional relationship between the light source and the integrator does not change even when the integrator vibrates by the vibration generating means.

  According to the laser image projection apparatus of the present invention, the speckle pattern generated due to the coherency of the laser is changed with time by vibrating the light source or the integrator with the vibration generating means, and the speckle noise is reduced. Alternatively, it is possible to prevent deterioration of the quality of the projection image such as vignetting of the projection image and variation in the amount of light due to the change of the optical axis due to the vibration of the integrator.

  Embodiments of a laser image projector according to the present invention will be described below in detail with reference to the drawings.

(Embodiment 1)
FIG. 1 is a schematic diagram of an optical unit of a laser image projection apparatus that vibrates a light source 1 and reduces speckle noise in Embodiment 1 of the present invention.

  The image projection apparatus is composed of R, G, and B color composition. Since the configuration of the present invention has the same configuration and function for R, G, and B, one of them is a representative example. Will be described.

In FIG. 1, vibration generating means 2 such as a motor whose rotational balance is unbalanced is attached to a light source 1, and the vibration generating means 2 is vibrated to transmit the vibration to the light source 1 to vibrate the light source 1. At that time, at least one guide 3 for restricting the vibration direction of the light source 1 and a spring 4 for restricting the vibration width are provided, and are perpendicular to the optical axis of the light source 1 or in the same direction as the optical axis (same as the optical axis). (The figure when the direction vibrates is omitted).
The vibration generating means 2 is equivalent to a voice coil motor, a piezoelectric element, and a cam mechanism, and can vibrate the light source 1. (Not shown)
In order to accurately quantify the vibration amount of the light source 1, the acceleration sensor 7 is attached to the light source 1 to constantly detect the vibration of the light source 1. The acceleration sensor is a circuit element for detecting acceleration, that is, a speed change per unit time, and is a mechanical sensor, or a sensor chip that converts acceleration detected using a semiconductor into electrostatic capacitance and electrostatic capacitance is converted into voltage. It is composed of a signal processing ASIC or a piezoresistive effect is used.

  FIG. 2 shows an optical unit of a laser image projector when the vibration generating means 2 of FIG. 1 in the first embodiment of the present invention vibrates and vibrates the light source 1 perpendicularly to the optical axis direction to reduce speckle noise. A schematic diagram is shown.

  As shown in FIG. 2, when the light source 1 vibrates by A amount in the direction A in the direction perpendicular to the optical axis due to the vibration of the vibration generating device 2, the lens 5 is moved based on the movement amount information of the light source 1 detected from the acceleration sensor 7. A voice coil motor 8 is a motor that controls the amount of working force by controlling the current flowing in the magnetic field, and corrects the optical axis in the same direction A as the vibration direction of the light source 1 by the amount B of the appropriate correction movement amount. By moving the optical axis instantaneously and correcting the optical axis to the center of the integrator 6, the vignetting light that protrudes from the aperture diameter of the integrator 6 as described above is eliminated, and the amount of light from the exit of the integrator 6 is always made constant. The amount of light applied to the surface of the spatial modulation element 10 via the lens 9 is constant.

  However, depending on the configuration of the lens 5, the optimal moving direction for correction may not be the same as the moving direction of the light source 1.

  As described with reference to FIG. 1 above, a diffuser plate or compound eye lens such as a ground glass is used to improve the light uniformity on the exit surface of the integrator 6 and to further reduce the coherency of the laser light that causes speckle. These lens arrays and / or holograms may be arranged between the lens 5 and the integrator 6 or their components may be swung or rotated.

  Further, by vibrating the light source 1 at a frequency of 30 Hz or more, the speckle noise pattern of the image formed on the retina of the human eye is temporally changed and averaged using the afterimage phenomenon of the eye. Make speckles invisible easily.

  As described above, in the first embodiment, the amount of movement of the vibrating light source 1 is detected by the acceleration sensor 7 and the lens 5 is moved, thereby reducing speckles and vignetting the light emitted from the light source 1 to the integrator 6. Without incident.

  Further, since light is incident on the integrator 6 without vignetting, the light emitted from the integrator 6 can be uniformly incident on the element surface of the spatial modulation element 18, and an image without vignetting and light amount change is projected onto the screen by the projection lens. Is done.

(Embodiment 2)
FIG. 3 is a schematic diagram of an optical unit of a laser image projection apparatus that vibrates the integrator 12 and reduces speckle noise in the second embodiment of the present invention.

  In the embodiment in which the positional relationship between the light source 11 and the integrator 12 changes, and the integrator 12 vibrates and changes its position with respect to the spatial modulation element 18, first, the light source 11 and the integrator 12 are corrected for misalignment as in the first embodiment. After adjusting the positional deviation of each, the deviation adjustment of the integrator 12 and the spatial modulation element 18 is performed. This time, the embodiment in the case where the positional relationship between the light source 11 and the integrator 12 does not change will be described with reference to FIG. I will explain. The image projection apparatus is composed of R, G, and B color composition, but since the configuration of the present invention has the same configuration and function for R, G, and B, one of them will be described as a representative example. .

  As in the first embodiment, as a means for vibrating the integrator 12 to reduce speckle noise, a vibration generating means 13 such as a motor whose rotational balance is unbalanced is attached to the integrator 12 and the vibration generating means 13 is vibrated. Then, the vibration is transmitted to the integrator 12 and the integrator 12 is vibrated. When the illumination side is viewed from the spatial modulation element 18, the speckle pattern changes with time because the light source 11 vibrates and the integrator 12 vibrates, so that the same speckle countermeasure effect can be obtained.

  When the vibration generating means 13 is vibrated, at least one guide 14 for restricting the vibration direction of the integrator 12 and a spring 15 for restricting the vibration width are provided in a direction perpendicular to the optical axis of the integrator 12 or the same as the optical axis. A random amount of movement is vibrated in the direction (not shown).

The vibration generating means 2 is equivalent to a voice coil motor, a piezoelectric element, or a cam mechanism, and can vibrate the integrator 12. (Not shown)
In order to accurately quantify the vibration amount of the integrator 12, the acceleration sensor 16 as described in the first embodiment is attached to the integrator 12, and the vibration of the integrator 12 is always detected.

  FIG. 4 is a schematic diagram of an optical unit of a laser image projector when the vibration generating means of FIG. 3 in the second embodiment of the invention vibrates and the integrator vibrates perpendicularly to the optical axis direction to reduce speckle noise. Show.

  As shown in FIG. 4, the movement amount of the integrator 12 is always detected by the acceleration sensor 16, and the relay lens 17 is moved in the same direction as the integrator 12 by the voice coil motor 19 described in the first embodiment based on the detected movement amount information. By correcting the optical axis to the center of the element surface of the spatial modulation element 18, it is possible to illuminate the element surface of the spatial modulation element 18 with a constant amount of light without vignetting, which has the disadvantage of vibrating the integrator as described above. Settled.

  However, depending on the configuration of the relay lens 17, the optimal moving direction for correction may not be the same as the moving direction of the integrator 12.

  By vibrating the integrator 12 at a frequency of 30 Hz or more, the speckle noise pattern of the image formed on the retina of the human eye is temporally changed and averaged using the afterimage phenomenon of the eye. Speckle is not visible.

  As described above, in the second embodiment, the amount of movement of the vibrating integrator 12 is detected by the acceleration sensor 16 and the relay lens 17 is moved so that the light emitted from the integrator 12 is evenly distributed on the surface of the spatial modulation element 18 without vignetting. An image having no vignetting and no change in light quantity is projected onto the screen by the projection lens.

  In the first and second embodiments, the acceleration sensor always detects vibration of the optical component only in the guide direction. However, in recent years, the guide is improved by improving the acceleration detection capability of the acceleration sensor, the response speed of the voice coil motor, and the movement accuracy. Even if it is not, if it is within a two-dimensional plane perpendicular to the optical axis and including the vibration direction of the guide, the acceleration sensor is arranged in a direction orthogonal to the two-dimensional plane, thereby eliminating the guide and making the optical component two-dimensional. It is possible to correct the optical axis. Similarly, when vibrating horizontally with respect to the optical axis, the optical axis can be corrected within a two-dimensional plane that includes the vibration direction of the guide and is horizontal to the optical axis.

  Further, by combining optical axis correction in the vertical and horizontal directions with respect to the optical axis, optical axis correction can be performed even for three-dimensional complicated vibrations.

  In the first and second embodiments, the optical unit of the LCD projector using a liquid crystal display element as a spatial modulation element has been described. However, a three-plate DLP (Digital Light Processing) using DMD (Digital Micromirror Device) for each of RGB colors and A single-plate DLP that periodically irradiates one DMD with RGB light and spatially modulates an RGB image in accordance with the irradiation period may be used. Also, the effect of the present invention can be obtained by using LCOS (reflection type liquid crystal display element) instead of DMD.

  In the first and second embodiments, the integrator may be a lot integrator in which a metal and dielectric light reflecting film is deposited on a solid cubic glass in addition to the light opening and the light emitting part. A light tunnel integrator in which glass other than the light aperture and light exit is opened and combined in a tunnel shape, or a plurality of lenses each composed of a pair of two lenses are combined in a compound eye shape. The fly eye lens integrator in which the light emitted from each of the lenses is superimposed on the surface of the spatial modulation element can also provide the effects of the present invention.

  The laser image projection apparatus according to the present invention includes ensuring optical illumination while vibrating an optical component to reduce speckle noise generated due to the coherency of a laser, and uses laser light as a light source. This is useful as an image projection apparatus.

  The laser image projection apparatus according to the present invention is an image projection using laser light as a light source, which requires ensuring optimal illumination while vibrating optical components in order to reduce speckle noise generated due to the coherency of the laser. It can also be applied to applications such as devices.

1 is a schematic diagram of an optical unit of a laser image projection device that vibrates a light source and reduces speckle noise in Embodiment 1 of the present invention. 1 is a schematic diagram of an optical unit of a laser image projector when the vibration generating means of FIG. 1 in the first embodiment of the present invention vibrates and vibrates vertically with the light source in the optical axis direction to reduce speckle noise. Schematic diagram of an optical unit of a laser image projection apparatus that vibrates an integrator and reduces speckle noise in Embodiment 2 of the present invention. 3 is a schematic diagram of an optical unit of a laser image projector when the vibration generating means of FIG. 3 according to Embodiment 2 of the present invention vibrates and the integrator is vibrated perpendicularly to the optical axis direction to reduce speckle noise.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light source 2 Vibration generation means 3 Guide 4 Spring 5 Lens 6 Integrator 7 Acceleration sensor 8 Voice coil motor 9 Relay lens 10 Spatial modulation element 11 Light source 12 Integrator 13 Vibration generation means 14 Guide 15 Spring 16 Acceleration sensor 17 Relay lens 18 Spatial modulation element 19 Voice coil motor

Claims (11)

A light source that generates laser light, vibration generating means that vibrates the light source, a spatial modulation element that spatially modulates light from the light source according to an input signal to form an image, and an illuminance on an element surface of the spatial modulation element In order to uniformly illuminate the light from the light source, an integrator that homogenizes the light incident from the light source and uniformly converts the light amount distribution on the exit opening surface perpendicular to the optical axis, and the light from the light source In a laser image projection device equipped with a lens for illuminating an integrator,
The incident position shift of the light from the light source to the integrator generated when the light source is vibrated by the vibration generating means is synchronized with the vibration of the light source following the vibration of the light source. A laser image projecting device characterized in that the image is continuously vibrated and corrected.   When the light source vibrates in a direction perpendicular to the optical axis, the lens also follows the light source and vibrates in a direction perpendicular to the optical axis or continuously in synchronization with the vibration of the light source. The laser image projection apparatus according to claim 1, wherein a deviation of an incident position of light from the light source on the light source is corrected.   When the light source vibrates in the optical axis direction, the lens also follows the light source, vibrates in the optical axis direction or continuously vibrates in synchronization with the vibration of the light source, and light from the light source to the integrator The laser image projection apparatus according to claim 1, wherein the deviation of the incident position is corrected.   The laser image projector according to claim 1, wherein the lens condenses or collimates light generated from the light source with respect to the integrator.   The laser image projection apparatus according to claim 1, wherein a diffusing element or a diffusing unit is disposed between the lens and the integrator so that light from the light source is diffused and incident on the integrator.   2. The laser image projector according to claim 1, wherein the light source is vibrated at 30 Hz or more by a vibration generating means.   A light source that generates laser light, a spatial modulation element that spatially modulates light from the light source according to an input signal, and forms an image, and illuminates light from the light source with uniform illumination on the element surface of the spatial modulation element In order to achieve this, the light incident from the light source is homogenized to uniformly convert the light amount distribution at the exit opening surface perpendicular to the optical axis, the vibration generating means for vibrating the integrator, and the light from the light source to the integrator. In the laser image projection apparatus comprising a lens that illuminates the light and a relay lens that refracts the light that has been homogenized by the integrator and adjusts the irradiation range to the surface of the spatial modulation element, the integrator vibrates by the vibration generating means. The incident position shift of the light from the integrator to the surface of the spatial modulation element generated when the relay lens is The laser image projection apparatus following the vibration of the serial integrator vibrations or in synchronization with the oscillation of the light source was continuously vibrated and correcting.   When the integrator vibrates in the direction perpendicular to the optical axis, the relay lens also vibrates in the direction perpendicular to the optical axis and continuously vibrates in synchronization with the vibration of the integrator. The laser image projection apparatus according to claim 7, wherein a deviation of an incident position of light from the integrator on an element surface of a modulation element is corrected.   When the integrator vibrates in the optical axis direction, the relay lens also follows the integrator and vibrates in the optical axis direction or continuously vibrates in synchronism with the vibration of the integrator. The laser image projector according to claim 7, wherein a deviation of an incident position of light from the integrator is corrected.   The laser image projector according to claim 7, wherein the integrator is vibrated at 30 Hz or more by a vibration generating unit.   The laser image according to claim 7, wherein the light source and the integrator are configured as one unit, and the positional relationship between the light source and the integrator does not change even when the integrator vibrates by vibration generation means. Projection device.

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