JP2013057785A - Laser source device and image projection apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser source device that allows the sufficient reduction of speckle noise, and to provide an image projection apparatus that reliably reduces sighting of speckle noise on a projection screen, and with which a projection image of reduced temporal variations in brightness is obtained.SOLUTION: The laser source device comprises a laser source and a reflection mechanism rotatable around an optical axis of an incident laser beam as a rotational axis thereof. The reflection mechanism includes a first reflecting mirror that is disposed on the rotational axis so as to reflect light travelling on the rotational axis, toward the orthogonal direction thereto, and a second reflecting mirror that reflects the reflected light from the first reflecting mirror. The reflection mechanism has a configuration where the reflected light from the second reflecting mirror is emitted so as to be condensed on a single point on the rotational axis. An image projection apparatus comprises the laser source device and an integrator of which an optical axis is identical with the rotational axis of the reflection mechanism, and of which an irradiated surface is disposed on a condensed position of the reflected light from the second reflecting mirror.

Description

  The present invention relates to a laser light source device and an image projection device such as a projector device provided with the laser light source device.

  Currently, for example, a projector apparatus is widely used as an image projection apparatus using a liquid crystal panel or a DMD (registered trademark) element, but in recent years, development of a technique using a laser beam as a light source used in the projector apparatus. Is underway.

  However, when a laser light source device is used as a light source in the projector device, it is observed that a glaring flicker called “speckle noise” occurs on the screen. This phenomenon occurs when image light is observed by projecting laser light, which is coherent light, onto a screen or the like, and light in phase is interfered to cause intensity of light on the retina.

Various methods have been proposed so far for reducing speckle noise. For example, in Japanese Patent No. 4379482 of Patent Document 1, an optical path conversion unit that converts an optical path of laser light emitted from a laser light source and makes it incident on a superimposing illumination element is moved by a moving unit to be superimposed from the laser light source device. A method for reducing speckle noise by temporally changing an optical path to an illumination element (for example, an integrator) is described.
Further, for example, in Japanese Patent Application Laid-Open No. 2008-175869 of Patent Document 2, the laser light incident surface is formed perpendicular to the optical axis of the laser light and the laser light emission surface is directed to the optical axis of the laser light. By rotating the photorefractive element formed tilted about the optical axis of the laser light as a central axis, the traveling direction of the laser light is set within a predetermined angle range with respect to the emitting direction of the laser light emitted from the laser light source. There has been proposed a method of projecting a leveled interference pattern on a screen through a condenser lens and an appropriate optical element.

Japanese Patent No. 4379482 JP 2008-175869 A

However, in the method described in Patent Document 1, the optical distance from the laser light source device to the superimposed illumination element such as an integrator is changed, and the light capture rate in the integrator changes with time. Thus, there arises a problem that a temporal change in brightness in the projected image gives a visually uncomfortable feeling.
In the method described in Patent Document 2, for example, red laser light emitted from a red laser light source, green laser light emitted from a green laser light source, and blue laser light emitted from a blue laser light source are synthesized. When projecting a color image on the screen, the refractive indices of the red, blue, and green laser beams that are collected by the integrator are different from each other. Causes chromatic aberration, which causes problems such as a reduction in light utilization and flickering. Furthermore, in such a method, in order to reliably suppress the recognition of image noise by the observer, the locus of the incident position where the laser light emitted from the photorefractive element is incident on the incident surface of the condenser lens is a circle, Since the traveling direction of the laser beam is changed by continuously moving it in a wide range so as to draw an ellipse, there is a problem that a condenser lens having a large aperture is required.

  The present invention has been made based on the circumstances as described above, and a laser light source device capable of sufficiently reducing speckle noise, and the visual recognition of speckle noise on a projection screen is reliably reduced. Another object of the present invention is to provide an image projection apparatus that can obtain a projection image with reduced temporal change in brightness.

The laser light source device of the present invention comprises a laser light source and a reflection mechanism configured to be rotatable about the optical axis of the laser light incident from the laser light source as a rotation center axis.
The reflection mechanism includes a first reflecting mirror disposed on the rotation center axis so that light traveling on the rotation center axis is reflected in a direction orthogonal to the rotation center axis, and the first reflection A second reflecting mirror that reflects light reflected by the mirror;
The reflected light from the second reflecting mirror is emitted so as to be condensed at one point on the rotation center axis.

  In the laser light source device of the present invention, it is preferable that the reflection mechanism is configured to be rotated at a frequency of 10 Hz or more.

The laser light source device of the present invention comprises a laser light source and a reflection mechanism that reflects the laser light from the laser light source,
The reflection mechanism includes a first reflecting mirror arranged on the optical axis of the laser light incident from the laser light source so that light traveling on the optical axis is reflected in a direction orthogonal to the optical axis; And a second reflecting mirror that has a reflecting surface that is rotationally symmetric with respect to the optical axis and that is fixedly disposed so as to surround the first reflecting mirror and that reflects light reflected by the first reflecting mirror. The first reflecting mirror is configured to be rotatable about the optical axis as a rotation center axis.
The reflected light from the second reflecting mirror is emitted so as to be collected at one point on the optical axis.

  In the laser light source device of the present invention, it is preferable that the first reflecting mirror is rotated at a frequency of 10 Hz or more.

An image projection device of the present invention comprises the above laser light source device and an integrator that emits laser light incident from the laser light source device as light of uniform intensity,
The integrator is arranged such that an optical axis coincides with the rotation center axis of the laser light source device, and a light incident surface is disposed at a position where the reflected light from the second reflecting mirror in the laser light source device is condensed. It is characterized by being.

According to the laser light source device of the present invention, the laser light source device includes a reflection mechanism configured to be rotatable about the optical axis of the laser light incident from the laser light source, and the reflection mechanism is on the rotation center axis. A first reflecting mirror disposed so that light traveling on the rotation center axis is reflected in a direction orthogonal to the rotation center axis, and a second reflecting mirror that reflects the light reflected by the first reflecting mirror; The reflected light from the second reflecting mirror is emitted so that the reflected light from the second reflecting mirror is collected at one point on the rotation center axis. Thus, only the incident direction is changed in a state where the incident angle is constant. As a result, the position of the interference pattern due to the laser beam emitted from the laser light source device is shifted in time (a large number of different interference patterns are superimposed), so that the interference pattern is averaged. Can be reliably reduced.
In addition, a second reflecting mirror having a reflecting surface that is rotationally symmetric with respect to the optical axis of the incident laser beam is used, and the second reflecting mirror is fixedly disposed so as to surround the first reflecting mirror. The above effect can also be obtained by a laser light source device having a reflection mechanism in which only one reflecting mirror is rotated with the optical axis of the incident laser light as the rotation center axis.

  Therefore, according to the image projection apparatus including the laser light source device, the visual recognition of speckle noise on the projection screen is reliably reduced, and the optical distance from the laser light source device to the integrator is made constant. Therefore, the light capture rate in the integrator does not change with time, and a projection image with reduced change in brightness can be obtained. In addition, since the laser light source device has a configuration in which light incident from the laser light source is collected by a reflecting mirror, light caused by chromatic aberration generated in a configuration in which the light is collected by an optical member having a light collecting function. It is possible to avoid the occurrence of problems such as a decrease in utilization rate and occurrence of flicker.

It is explanatory drawing which shows the outline of a structure in an example of the projector apparatus which concerns on the image projector of this invention. It is a perspective view which shows the outline of a structure in an example of the reflection mechanism which comprises the laser light source apparatus in the projector apparatus shown in FIG. It is sectional drawing along the optical axis of the incident laser beam of the reflection mechanism shown in FIG. FIG. 4 is a conceptual diagram showing ray tracing lines by the reflection mechanism shown in FIGS. 2 and 3. It is an idea figure which shows the other structural example of the reflection mechanism in the laser light source apparatus of this invention with a ray tracing line. It is sectional drawing along the optical axis of the incident laser beam which shows schematically the further another structural example of the reflection mechanism in the laser light source apparatus of this invention. It is an idea figure which shows the ray tracing line by the reflection mechanism shown in FIG.

Hereinafter, embodiments of the present invention will be described in detail.
FIG. 1 is an explanatory diagram showing an outline of the configuration of an example of a projector apparatus according to an image projection apparatus of the present invention.
This projector device controls a laser light source device 10, a rod-shaped integrator 50 that emits light incident from the laser light source device 10 as light of uniform intensity, and a spread angle of the laser light emitted from the integrator 50. A collimator lens 51 that is incident on a spatial modulation element 52 such as DMD (registered trademark), and a projection lens 53 that enlarges and projects video light modulated by the spatial modulation element 52 onto the screen S. .

  The laser light source device 10 includes a laser light emitting mechanism 20 and a reflecting mechanism 30 that reflects the laser light emitted from the laser light emitting mechanism 20.

The laser light emitting mechanism 20 includes a plurality of laser light sources, specifically, a blue laser light source 21A that emits blue laser light (wavelength 460 nm), a green laser light source 21B that emits green laser light (wavelength 530 nm), and red laser light. The red laser light source 21C that emits light (for example, wavelength 640 nm) and the condensing lenses 22A, 22B, and 22C that are arranged at positions on the front side in the light emission direction of the respective laser light sources 21A, 21B, and 21C A different plate-like first dichroic mirror 28A, a plate-like second dichroic mirror 28B, and a plate-like third dichroic mirror 28C are provided.
Each of the laser light sources 21A, 21B, and 21C is arranged so that the optical axes of the emitted laser beams extend in parallel to each other. Each condensing lens 22A, 22B, 22C is arrange | positioned with the attitude | position in which the optical axis is extended along the light emission direction of a corresponding laser light source. The dichroic mirrors 28A, 28B, and 28C are arranged in parallel with each other in a direction perpendicular to the optical axis in a state where the light emission surface is inclined with respect to the optical axis of the laser light emitted from the laser light source. Has been.

  As each of the laser light sources 21A, 21B, and 21C, for example, a semiconductor laser can be used.

  As shown in FIGS. 2 and 3, the reflecting mechanism 30 according to this embodiment includes a first reflecting mirror 35 and a second reflecting mirror 36 that reflects light reflected by the first reflecting mirror 35. The outer shape thus formed includes a cylindrical machine casing 31. The machine casing 31 has a central axis extending along the optical axis C of the laser light L from the laser light emitting mechanism 20 that is incident on the reflecting mechanism 30, specifically, the optical axis of the incident laser light. Therefore, in this example, the center axis of the machine casing 31 that coincides with the optical axis C of the incident laser beam is the center of rotation of the reflection mechanism 30, as will be described later. It is set as the axis R. 32 is a light entrance window, and 33 is a light exit window.

  The first reflecting mirror 35 is composed of, for example, a plane mirror, and light traveling on the rotation center axis R of the incident laser light L is reflected in a direction orthogonal to the rotation center axis R at a position on the rotation center axis R. Thus, the light reflecting surface 35A is arranged in a state of being inclined with respect to the rotation center axis R (the center axis of the machine casing 31).

  The second reflecting mirror 36 is made of, for example, a plane mirror, and is disposed in a state where the light reflecting surface 36 </ b> A faces the light reflecting surface 35 </ b> A of the first reflecting mirror 35.

  Reference numeral 40 in FIGS. 2 and 3 is a substantially cylindrical bearing member having a flange portion 41 protruding radially inward at one end, and the machine frame 31 has a circumferential side surface and an inner circumferential surface of the bearing member 40. For example, a bearing is interposed between the bearing member 40 and the machine frame 31 so as to be rotatable about the rotation center axis R.

Reference numeral 45 in FIGS. 2 and 3 denotes a drive motor for rotating the machine casing 31, and a driven gear 46 fixed to a drive shaft extending along the rotation center axis R is provided on the machine casing 31. Accordingly, the entire reflection mechanism 30 is configured to be rotatable about the rotation center axis R.
The reflection mechanism 30 is preferably driven to rotate at a frequency of, for example, 10 Hz or more (the number of rotations during the time of 1 second is 10 or more). Thereby, the speckle noise reduction effect can be acquired reliably.

  In the projector device described above, the light emitted from the laser light emitting mechanism 20 in the laser light source device 10 is reflected by the rotating reflecting mechanism 30 and is collected and incident on the light incident surface 50A of the integrator 50. Specifically, in the laser light emitting mechanism 20 of the laser light source device 10, the blue laser light emitted from the blue laser light source 21A is condensed by the condenser lens 22A and applied to the first dichroic mirror 28A. The reflected light reflected by the first dichroic mirror 28A is condensed by the condenser lens 22B to the transmitted light that has passed through the second dichroic mirror 28B, and is emitted to the second dichroic mirror 28B. The green laser light emitted from the second dichroic mirror 28B is combined with the reflected light, and the combined blue laser light and green laser light combined with the second dichroic mirror 28B is the third light. The transmitted light that has passed through the dichroic mirror 28C is added to the condenser lens 22. The third dichroic mirror 28C red laser light emitted from the red laser light source 21C to be irradiated to the light reflected is emitted are combined by the third dichroic mirror 28C is condensed by. As shown in FIG. 4, the laser light emitted from the laser light emitting mechanism 20 (indicated by a two-dot chain line in FIG. 4) is the first in the reflecting mechanism 30 rotated about the rotation center axis R. The light enters the reflection mirror 35 along the rotation center axis R. The light reflected by the first reflecting mirror 35 is reflected by the second reflecting mirror 36 rotated around the rotation center axis R in a state where the positional relationship with the first reflecting mirror 35 is maintained, and is reflected by the integrator 50. The light is collected at a position on the rotation center axis R (the optical axis of the integrator 50) on the light incident surface 50A. Here, the incident angle of the light reflected by the second reflecting mirror 36 with respect to the light incident surface 50A of the integrator 50 (the light reflected by the second reflecting mirror 36 with respect to the light traveling on the rotation center axis R). The incident angle (α) with respect to the light incident surface 50A is selected so that the incident light is within the range of the light beam angle that can be used by the projector, and is preferably as large as possible within the range of 0 to 25 °, for example.

  Then, the laser light whose intensity is made uniform by the integrator 50 is emitted at the same emission angle as the incident angle with respect to the integrator 50, and the image light formed by being modulated by the spatial modulation element 52 is passed through the projection lens 53. An enlarged projection is made on the screen S.

Thus, the laser light source device 10 having the above-described configuration includes the reflection mechanism 30 configured to be rotatable about the optical axis C of the laser light incident from the laser light emitting mechanism 20 as the rotation center axis R. A reflection mechanism 30 disposed on the rotation center axis R so that light traveling on the rotation center axis R is reflected in a direction perpendicular to the rotation center axis R; And the second reflecting mirror 36 that reflects the reflected light of the second reflecting mirror 35, and the reflected light by the second reflecting mirror 36 is condensed at a position on the rotation center axis R on the light incident surface 50 </ b> A of the integrator 50. With this configuration, the reflected light from the second reflecting mirror 36 is in a state in which the incident angle is set to a constant magnitude with respect to the condensing position on the light incident surface 50A of the integrator 50. And only the incident direction is And thus incident on the integrator 50 is of. Thereby, since the interference pattern is averaged when the position of the interference pattern formed on the screen S is shifted in time, speckle noise can be reliably reduced.
Therefore, according to the projector device provided with the laser light source device 10, the speckle noise on the screen S is reliably reduced and the light incident surface of the integrator lens 50 from the laser light emitting mechanism 20 in the laser light source device 10 is reduced. Since the optical distance up to 50A is constant, the light capture rate of the integrator lens 50 does not change with time, and a projection image with reduced brightness change can be obtained. .
Further, since the laser light source device 10 is configured to condense light incident from the laser light source using a reflecting mirror, the chromatic aberration generated in the configuration configured to condense by an optical member having a condensing function. It can be avoided that a problem such as a decrease in the light utilization rate occurs.

As mentioned above, although one Embodiment of this invention was described, this invention is not limited to said embodiment, A various change can be added.
For example, the configuration of the reflecting mechanism is not limited to that according to the above-described embodiment. For example, as shown in FIG. 5, in the configuration shown in FIGS. 2 and 3, the second reflecting mirror 36 is a plane mirror. Alternatively, it may be an elliptical mirror. In the reflecting mechanism 30, the second reflecting mirror 36 has a first focal point located on the reflecting surface 35 </ b> A of the first reflecting mirror 35 and a second focal point located on the light incident surface 50 </ b> A of the integrator 50. The incident laser light (indicated by a two-dot chain line in FIG. 5) is reflected by the first reflecting mirror 35, and the reflected light is reflected by the second reflecting mirror 36. Thus, the light is condensed at one point on the rotation center axis R on the light incident surface 50A of the integrator lens 50. Even in the laser light source device including the reflection mechanism 30 having such a configuration, the same effect as described above can be obtained.

  In the above description, the structure in which the incident direction of the laser light with respect to the light incident surface 50A of the integrator 50 is changed by rotating the entire reflection mechanism 30 with the optical axis C of the incident laser light as the rotation center axis R will be described. However, it is not necessary that the entire reflection mechanism 30 is rotated.

FIG. 6 schematically shows another configuration example of the reflection mechanism in the laser light source device of the present invention, and is a cross-sectional view along the optical axis of the incident laser light, and FIG. 7 is based on the reflection mechanism shown in FIG. It is an idea figure which shows a ray tracing line.
The reflecting mechanism 60 in this laser light source device includes a first reflecting mirror 61 made of, for example, a plane mirror disposed on the optical axis C of incident laser light L (indicated by a two-dot chain line in FIG. 7), A second reflecting mirror 62 having a reflecting surface rotationally symmetric with respect to the optical axis C of the incident laser beam L, which is fixed to a machine frame (not shown) so as to surround the first reflecting mirror 61; It has. In the first reflecting mirror 61, the light reflecting surface 61A has an optical axis C so that light traveling on the optical axis C of the laser light incident from the laser light emitting mechanism is reflected in a direction orthogonal to the optical axis C. It is arrange | positioned in the state inclined with respect to.
The second reflecting mirror 62 is constituted by, for example, an elliptical mirror having a reflecting surface 62A made of a spheroid with the optical axis C as the center. The second reflecting mirror 62 is arranged in a state where the first focal point is located on the reflecting surface 61A of the first reflecting mirror and the second focal point is located on the light incident surface 50A of the integrator 50. .

  Reference numeral 65 in FIG. 6 denotes a reflecting mirror holding member that holds the first reflecting mirror 61, and a substantially cylindrical shaft portion 66 that extends along the optical axis C of the incident laser light L and the shaft portion 66. One end (lower end in FIG. 6) has a flange portion 67 formed over the entire circumference, and the first reflecting mirror 61 is held and fixed at the other end (upper end in FIG. 6) of the shaft portion 66. Reference numeral 68 denotes a light transmission window.

  Reference numeral 70 in FIG. 6 denotes a cylindrical bearing member. The shaft portion 66 of the reflecting mirror holding member 65 is a bearing in a state in which, for example, a bearing is interposed between the outer peripheral surface and the inner peripheral surface of the bearing member 70. The reflecting mirror holding member 65 is inserted into the member 70 so that the reflecting mirror holding member 65 is rotatably held with the optical axis C of the incident laser light as the rotation center axis R.

Reference numeral 45 in FIG. 6 denotes a drive motor for rotating the reflecting mirror holding member 65, and the drive gear 46 fixed to the driving shaft extending along the rotation center axis R is a flange portion 67 of the reflecting mirror holding member 65. Therefore, only the first reflecting mirror 61 is configured to be rotatable around the rotation center axis R.
The first reflecting mirror 61 is preferably rotationally driven, for example, at a frequency of 10 Hz or more (the number of rotations is 10 times or more during the time of 1 second). Thereby, the speckle noise reduction effect can be acquired reliably.

  In this laser light source device, the light emitted from the laser light emitting mechanism is along the rotation center axis R with respect to the first reflecting mirror 61 rotated around the rotation center axis R, as shown in FIG. Is incident. The reflected light from the first reflecting mirror 61 is reflected by the second reflecting mirror 62, and the reflected light is condensed at a position on the rotation center axis R (the optical axis of the integrator 50) on the light incident surface 50A of the integrator 50. Is emitted. Here, the incident angle α of the light reflected by the second reflecting mirror 62 with respect to the light incident surface 50A of the integrator 50 is selected so that the incident light is within the range of the light beam angle that can be used by the projector. It is desirable that the value be as large as possible within the range of °.

  Also in the laser light source device including the reflection mechanism 60 having such a configuration, the same effect as described above can be obtained.

DESCRIPTION OF SYMBOLS 10 Laser light source device 20 Laser light emission mechanism 21A Blue laser light source 21B Green laser light source 21C Red laser light source 22A, 22B, 22C Condensing lens 28A 1st dichroic mirror 28B 2nd dichroic mirror 28C 3rd dichroic mirror 30 Reflection mechanism DESCRIPTION OF SYMBOLS 31 Machine frame 32 Light entrance window 33 Light exit window 34 Driven gear 35 First reflective mirror 35A Light reflective surface 36 Second reflective mirror 36A Light reflective surface 40 Bearing member 41 Flange part 45 Driving motor 46 Drive gear 50 Integrator 50A Light incident surface 51 Collimator lens 52 Spatial modulation element 53 Projection lens 60 Reflection mechanism 61 First reflecting mirror 61A Light reflecting surface 62 Second reflecting mirror 62A Light reflecting surface 65 Reflecting mirror holding member 66 Shaft portion 67 Flange portion 68 Light transmission Window 70 Bearing member C Optical axis of laser light incident on reflection mechanism R Rotation center axis S Screen

Claims (5)

Comprising a laser light source and a reflection mechanism configured to be rotatable about the optical axis of the laser light incident from the laser light source,
The reflection mechanism includes a first reflecting mirror disposed on the rotation center axis so that light traveling on the rotation center axis is reflected in a direction orthogonal to the rotation center axis, and the first reflection A second reflecting mirror that reflects light reflected by the mirror;
The laser light source device characterized in that the light reflected by the second reflecting mirror is emitted so as to be condensed at one point on the rotation center axis.   The laser light source device according to claim 1, wherein the reflection mechanism is rotated at a frequency of 10 Hz or more. Comprising a laser light source and a reflection mechanism for reflecting the laser light from the laser light source;
The reflection mechanism includes a first reflecting mirror arranged on the optical axis of the laser light incident from the laser light source so that light traveling on the optical axis is reflected in a direction orthogonal to the optical axis; And a second reflecting mirror that has a reflecting surface that is rotationally symmetric with respect to the optical axis and that is fixedly disposed so as to surround the first reflecting mirror and that reflects light reflected by the first reflecting mirror. The first reflecting mirror is configured to be rotatable about the optical axis as a rotation center axis.
The laser light source device characterized in that the light reflected by the second reflecting mirror is emitted so as to be condensed at one point on the optical axis.   The laser light source device according to claim 3, wherein the first reflecting mirror is rotated at a frequency of 10 Hz or more. The laser light source device according to any one of claims 1 to 4, and an integrator that emits laser light incident from the laser light source device as light of uniform intensity,
The integrator is arranged such that an optical axis coincides with the rotation center axis of the laser light source device, and a light incident surface is disposed at a position where the reflected light from the second reflecting mirror in the laser light source device is condensed. An image projection apparatus characterized by comprising:

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