JP2015145972A - Lighting device and projector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lighting device, provided with multiple light sources, which is excellent in speckle reduction effects.SOLUTION: A lighting device 2G according to the present invention comprises a light source device 7 provided with a plurality of light sources including a first light source, a second light source, and a third light source which are two-dimensionally disposed, and a shift device 11 for shifting the optical paths of a plurality of beams emitted from the light source device 7 in a prescribed direction, separately in time. The distance between the second light source and the first light source and the distance between the third light source and the first light source are shorter than the distance between any of the plurality of light sources, except the second and third light sources, and the first light source. The prescribed direction is a direction linking between the first light source and the second and third light sources.

Description

  The present invention relates to a lighting device and a projector.

  A light source that emits coherent light may be used as a light source of a projector. Examples of this type of light source include a solid-state light source using a laser diode (LD), a super luminescence diode (SLD), and a short arc lamp light source. For example, since a projector using a laser light source has a narrow wavelength range of laser light, the color reproduction range can be sufficiently widened, and the size and the number of components can be reduced.

  When displaying with a projector using a coherent light source, an observer may recognize speckles. Speckle is a pattern in which bright spots and dark spots are distributed in stripes or spots due to light interference. When speckle occurs, an observer who sees the display may feel glare and feel uncomfortable.

  As one of the techniques for suppressing speckles, Patent Literature 1 discloses an illumination device including a coherent light source, a microlens array, and a light beam scanning device. In this illumination device, the light beam is irradiated onto the microlens array via the light beam scanning device, and the irradiation position of the light beam on the microlens array changes with time. At this time, regardless of the incident position of the light beam with respect to the microlens array, the light beam is irradiated to the same position on the light receiving surface, and the speckle is suppressed by being incident on the fixed irradiation region at various incident angles.

JP 2012-58711 A

  An illumination device using a plurality of light sources that emit coherent light may be used for the projector. When a plurality of coherent light sources are employed in the illumination device of Patent Document 1, the speckle reduction effect may not be obtained.

  The present invention has been made to solve the above problems. An object of one embodiment of the present invention is to provide an illumination device including a plurality of light sources and having an excellent speckle reduction effect. An object of one embodiment of the present invention is to provide a projector that includes an illumination device including a plurality of light sources and has excellent display quality by reducing speckles.

  In order to achieve the above object, an illumination device according to an aspect of the present invention includes a first light source that emits first coherent light that is two-dimensionally arranged, and a second light source that emits second coherent light. And a third light source that emits third coherent light, and a light source device that includes a plurality of light sources, and optical paths of the plurality of coherent lights emitted from the light source device are shifted in time in a predetermined direction. An optical path shift device, and a distance between the second light source and the first light source and a distance between the third light source and the first light source are the light source of the plurality of light sources, The predetermined light source is shorter than the distance between the first light source and any light source other than the second light source and the third light source, and the predetermined direction includes the first light source, the second light source, and the third light source. It is the direction that connects the area between To.

  When three light sources including the first light source, the second light source, and the third light source are two-dimensionally arranged, the direction in which the optical path of each coherent light emitted from these light sources is shifted is first. If it is the direction connecting the first light source and the second light source, the locus of the irradiation area of the first coherent light on the illumination target and the locus of the irradiation area of the second coherent light will overlap. Similarly, if the direction in which the optical path of each coherent light is shifted is the direction connecting the first light source and the third light source, the locus of the irradiation area of the first coherent light on the illumination target and the third The locus of the irradiation area of the coherent light overlaps. As a result, a difference in illuminance increases between a region where the loci of the two coherent light irradiation regions overlap and a region where they do not overlap on the illumination target, and speckles are likely to occur.

  On the other hand, in the illumination device according to one aspect of the present invention, the optical path shift device has a plurality of coherent light paths in the region between the first light source, the second light source, and the third light source. Is shifted in time in the direction connecting the two. Therefore, when the optical paths of the first coherent light, the second coherent light, and the third coherent light are temporally shifted by the optical path shift device, the locus of the irradiation region of the first coherent light and the second coherent light The overlap with the trajectory of the irradiation region of the light and the overlap of the trajectory of the irradiation region of the first coherent light and the trajectory of the irradiation region of the third coherent light are smaller than in the above case. As a result, the uniformity of the illuminance distribution on the illumination target is improved and the uniformity of the incident angle distribution is improved. As a result, speckle can be reduced.

In the illuminating device according to one aspect of the present invention, the optical path shift device includes a trajectory of the bottom of the intensity distribution of the first coherent light and the second coherent light on a reference plane perpendicular to the optical axis of the light source device. The optical paths of the plurality of coherent lights may be shifted so that the bottom traces of the intensity distributions overlap.
According to this configuration, the bottom locus of the intensity distribution of the first coherent light overlaps the bottom locus of the intensity distribution of the second coherent light. In the region where the tracks overlap, the intensities of both coherent lights are integrated. Thereby, the difference between the illuminance in the region where the loci of the tails of the intensity distributions of the two coherent lights overlap and the illuminance at the peak position of the intensity distribution is reduced. As a result, the uniformity of the illuminance distribution can be further improved.

In the illumination device according to one aspect of the present invention, the optical path shift device may include a rotatable prism.
According to this configuration, the optical path of the coherent light can be temporally shifted in a predetermined direction by rotating the prism.

In the illumination device according to one aspect of the present invention, the rotational speed of the prism may change over time.
According to this configuration, by temporally changing the rotation speed of the prism, the time-averaged illuminance distribution in the illumination target can be made uniform, and an illuminance distribution closer to the top hat shape can be obtained.

In the illumination device according to one aspect of the present invention, the rotation speed of the prism may be constant.
According to this configuration, the time-averaged illuminance is increased at the periphery of the irradiation area of the light emitted from the prism. Thereby, speckle can be reduced more effectively.

An illumination device according to an aspect of the present invention includes a collimating optical system provided in an optical path between the light source device and the optical path shift device, and a diffractive optical device in which a plurality of coherent lights incident through the optical path shift device are incident. And an element.
According to this configuration, the coherent light emitted from the light source device is collimated by the collimating optical system, and the collimated light enters the diffractive optical element via the optical path shift device. The light is diffracted by the diffractive optical element, and a predetermined area to be illuminated is illuminated.

In the illumination device according to one aspect of the present invention, the first diffracted light pattern formed by the first coherent light and the diffractive optical element is formed by the second coherent light and the diffractive optical element. It may be different from the second diffracted light pattern.
According to this configuration, speckle can be effectively reduced by the first diffracted light pattern and the second diffracted light pattern which are different from each other.

In the illumination device according to one aspect of the present invention, the first diffracted light pattern formed by the first coherent light and the diffractive optical element is formed by the second coherent light and the diffractive optical element. And a superimposing optical system that superimposes the first diffracted light pattern and the second diffracted light pattern on the illumination target.
According to this configuration, speckles can be effectively reduced by superimposing the first diffracted light pattern and the second diffracted light pattern on the object to be illuminated by the superimposing optical system.

The illumination device according to one aspect of the present invention includes a collimating optical system provided in an optical path between the light source device and the optical path shift device, and an integrator optical in which a plurality of coherent lights incident through the optical path shift device are incident. And a system.
According to this configuration, the coherent light emitted from the light source device is collimated by the collimating optical system, and the collimated light is incident on the integrator optical system via the optical path shift device. Thereby, the illuminance distribution and the incident angle distribution of the light on the illumination target are made uniform.

In the illumination device according to one aspect of the present invention, the integrator optical system includes a first lens array having a plurality of lenses and a second lens array having a plurality of lenses, and the light of the integrator optical system. A diffusion plate may be provided on the incident side.
According to this configuration, the coherent light emitted from the light source device is diffused by the diffusion plate, and light having a uniform illuminance distribution enters the first lens array. Thereby, a uniform illuminance distribution is formed on the second lens array, and speckle can be effectively reduced.

A projector according to one aspect of the present invention includes a lighting device according to one aspect of the present invention, a light modulation device that modulates light from the lighting device, and a projection optical system that projects light modulated by the light modulation device. And.
According to one aspect of the present invention, it is possible to provide a projector having excellent display quality by reducing speckles by including the above-described illumination device.

1 is a schematic configuration diagram illustrating a projector according to a first embodiment of the invention. It is a schematic block diagram which shows the illuminating device of 1st Embodiment. It is a figure for demonstrating the shift of the optical path by an optical path shift apparatus. It is the front view of the prism seen from the optical axis direction of the illuminating device. It is a figure which shows the locus | trajectory of the irradiation area | region of the light shifted on a diffractive optical element. It is the front view of the prism seen from the optical axis direction of the illuminating device of the comparative example. It is a figure which shows the locus | trajectory of the irradiation area | region of the light shifted on a diffractive optical element in the illuminating device of a comparative example. It is a figure which shows the modification of arrangement | positioning of the several light source in a light source device. It is a figure which shows the modification of arrangement | positioning of the several light source in a light source device. It is a figure which shows the modification of arrangement | positioning of the several light source in a light source device. It is a figure which shows the modification of arrangement | positioning of the several light source in a light source device. It is a figure which shows illumination intensity distribution when changing the rotational speed of a prism. It is a figure which shows illuminance distribution when the rotational speed of a prism is made constant. It is a figure which shows intensity distribution of the some light inject | emitted from the some light source. It is a schematic block diagram which shows the illuminating device of 2nd Embodiment. It is a schematic block diagram which shows the illuminating device of 3rd Embodiment. It is a schematic block diagram which shows the illuminating device of 4th Embodiment. It is a schematic block diagram which shows the illuminating device of 5th Embodiment. It is a schematic block diagram which shows the other example of an optical path shift apparatus.

[First Embodiment]
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.
The projector according to the first embodiment is an example of a liquid crystal projector including three sets of illumination devices each having a plurality of laser light sources.
FIG. 1 is a schematic configuration diagram illustrating the projector according to the first embodiment. FIG. 2 is a schematic configuration diagram illustrating the illumination device according to the first embodiment.
In the following drawings, in order to make each component easy to see, the scale of the size may be varied depending on the component.

  The projector 1 according to the first embodiment forms an image based on image data supplied from a signal source such as a DVD player or a PC, and projects the formed image onto a projection surface SC (display screen) such as a screen or a wall. .

  As shown in FIG. 1, the projector 1 includes an illumination optical system 2, an image forming optical system 3, a projection optical system 4, a control system 5, and a color synthesis optical system 6. The image forming optical system 3 forms an image from the illumination light emitted from the illumination optical system 2. The projection optical system 4 projects the image formed by the image forming optical system 3 onto the projection surface SC. The control system 5 controls each part of the projector 1. The projector 1 expresses a full-color image by individually forming red (R), green (G), and blue (B) color images and synthesizing the formed three-color images by the color synthesis optical system 6. To do. The projector 1 is a so-called three-plate projector.

  The illumination optical system 2 includes an illumination device 2R that emits red illumination light, an illumination device 2G that emits green illumination light, and an illumination device 2B that emits blue illumination light. All of these illumination devices have the same configuration, and each include a light source device 7 and an illumination optical system 8. Detailed configurations of the lighting device 2R, the lighting device 2G, and the lighting device 2B will be described later.

  The image forming optical system 3 includes an image forming apparatus 3R that forms a red image, an image forming apparatus 3G that forms a green image, and an image forming apparatus 3B that forms a blue image. Each of illumination device 2R, illumination device 2G, and illumination device 2B has a one-to-one correspondence with image forming device 3G, image forming device 3G, and image forming device 3B. Each of the image forming apparatus 3G, the image forming apparatus 3G, and the image forming apparatus 3B corresponds to the light modulation device in the claims.

  Each of the image forming apparatus 3G, the image forming apparatus 3G, and the image forming apparatus 3B forms an image of each color with illumination light from the corresponding illumination device, and emits image light corresponding to the image of each color. That is, the red image forming apparatus 3R forms a red image by the illumination light (red light) from the red illumination apparatus 2R, and emits light (image light) corresponding to the image. The green image forming apparatus 3G forms a green image with illumination light (green light) from the green illumination apparatus 2G, and emits light (image light) corresponding to the image. The blue image forming apparatus 3B forms a blue image with the illumination light (blue light) from the blue illumination apparatus 2B, and emits light (image light) corresponding to the image.

  The image light of each color emitted from the image forming optical system 3 enters the color synthesis optical system 6. The color synthesizing optical system 6 is composed of, for example, a dichroic prism. The dichroic prism includes two wavelength separation films that reflect or transmit incident light according to the wavelength of incident light. One wavelength separation film has characteristics of transmitting red light and green light and reflecting blue light. The other wavelength separation films have characteristics of transmitting green light and blue light and reflecting red light.

  The three colors of color light incident on the color synthesis optical system 6 from the image forming optical system 3 are aligned in the traveling direction depending on whether they are reflected by the wavelength separation film or transmitted through the wavelength separation film depending on the wavelength. 6 is injected. Image light emitted from the color synthesis optical system 6 enters the projection optical system 4. The projection optical system 4 includes a plurality of lenses or mirrors. The projection optical system 4 enlarges and projects the image formed by the image forming optical system 3 on the projection surface SC.

Hereinafter, each part of the projector 1 will be described in more detail.
In the first embodiment, the illumination device for each color and the image forming apparatus have the same configuration. Therefore, the configuration of the system corresponding to the green image is representatively described, and the description of the system corresponding to the other color image is omitted.

  FIG. 2 is a diagram showing the illumination device 2G, the image forming device 3G, the color synthesis optical system 6, and the projection optical system 4. The illumination device 2G illuminates a region in which a plurality of pixels in the image forming device 3G are arranged with substantially uniform brightness by a Kohler illumination method or the like. The illumination device 2G can suppress speckles from being visually recognized by temporally changing the incident angle distribution of light incident on each point of the illuminated area IR.

  The illumination device 2G includes a light source device 7 and an illumination optical system 8. The illumination optical system 8 includes a collimating optical system 10, an optical path shift device 11, a diffractive optical element 12, and a superimposing optical system 13.

The light source device 7 includes a plurality of laser light sources 15. The plurality of laser light sources 15 are two-dimensionally arranged at equal intervals in directions orthogonal to each other on a reference plane perpendicular to the direction of the optical axis AX of the light source device 7. In the example of the present embodiment, nine laser light sources 15 are arranged in three rows and three columns at equal intervals in a direction orthogonal to each other in the reference plane. The laser light source 15 emits green laser light as coherent light. As another light source, a light source that emits coherent light such as a super luminescence diode (SLD) or a short arc lamp light source can be used.
The optical axis AX of the light source device 7 is the optical axis of the light beam when a bundle of a plurality of coherent light beams emitted from the light source device 7 is regarded as one light beam.

  The collimating optical system 10 includes a plurality of lenses 16. Each of the plurality of lenses 16 constituting the collimating optical system 10 has a one-to-one correspondence with each of the plurality of laser light sources 15 constituting the light source device 7. Therefore, like the light source device 7, the plurality of lenses 16 are two-dimensionally arranged at equal intervals in directions orthogonal to each other when viewed from the direction of the optical axis AX of the light source device 7.

  The optical path shift device 11 includes a prism 17 made of, for example, a cubic transparent material that can be rotated. The prism 17 is disposed at a position where a plurality of lights emitted from the light source device 7 are incident, and transmits the plurality of lights emitted from the light source device 7. The prism 17 rotates around a rotation axis R disposed in a direction intersecting with the direction of the optical axis AX of the light source device 7. The prism 17 is rotated by torque supplied from a drive unit such as an electric motor.

  The prism 17 has the 1st surface 17a into which the light from the light source device 7 injects at a certain time, and the 2nd surface 17b parallel to the 1st surface 17a. In the present embodiment, the prism 17 has a square cross section perpendicular to the rotation axis R, and has a third surface 17c and a fourth surface 17d perpendicular to the first surface 17a and the second surface 17b. The third surface 17c and the fourth surface 17d are parallel to each other. The rotation axis R is an axis that passes through the center (center of gravity) of the prism 17 and extends in a direction parallel to each of the first surface 17a, the second surface 17b, the third surface 17c, and the fourth surface 17d.

  The diffractive optical element 12 is composed of, for example, a computer generated hologram (CGH). Although not shown, the diffractive optical element 12 has a plurality of cells arranged in an array. The CGH is a surface relief type hologram element in which a fine concavo-convex structure designed by a computer is provided on one surface of a base material made of a light transmissive material such as quartz (glass) or synthetic resin. The diffractive optical element 12 functions as a wavefront conversion element that converts the wavefront of incident light using a diffraction phenomenon.

  The diffractive optical element 12 has a plurality of concave portions having rectangular cross-sectional shapes with different depths, and a plurality of convex portions having rectangular cross-sectional shapes with different heights. In the diffractive optical element 12, the size and shape of the illuminated region and the illuminance distribution of the diffracted light can be freely adjusted by appropriately adjusting the design conditions such as the pitch of the recesses and protrusions, the depth of the recesses and the height of the protrusions Can be set to As a technique for optimizing the design conditions of the diffractive optical element 12, for example, an arithmetic technique such as an iterative Fourier method can be used.

  The superimposing optical system 13 includes a first lens 18 and a second lens 19. The superimposing optical system 13 is disposed at a position where light emitted from the diffractive optical element 12 enters. The superimposing optical system 13 superimposes light emitted from the diffractive optical element 12 and incident on different positions of the superimposing optical system 13 at each point on the image forming apparatus 3G.

  The image forming apparatus 3G is, for example, a transmissive liquid crystal light valve. The image forming apparatus 3G includes a liquid crystal panel 21 having a plurality of pixels, an incident-side polarizing plate 22 disposed on the incident side (light source device 7 side) of the liquid crystal panel 21, and the emission side (projection optical system 4) of the liquid crystal panel 21. And an exit side polarizing plate 23 arranged on the side).

  The incident-side polarizing plate 22 transmits linearly polarized light in a first direction parallel to a surface on which a plurality of pixels are arranged in the liquid crystal panel 21 and shields (absorbs) linearly polarized light in a second direction orthogonal to the first direction. The liquid crystal panel 21 is controlled by the image control device 24 and modulates the polarization state of light incident on each pixel for each pixel. The image control device 24 is, for example, a part of the control system 5 shown in FIG.

  For example, the emission side polarizing plate 23 is arranged so that the transmission axis thereof is orthogonal to the transmission axis of the incident side polarizing plate 22. The image control device 24 drives the liquid crystal panel 21 based on the image data, and controls the polarization state of the light passing through each pixel, so that the incident side polarizing plate 22, the liquid crystal panel 21, and the emission side polarizing plate 23 The transmittance is controlled for each pixel. In this way, the image forming apparatus 3G forms an image defined in the image data.

  As described with reference to FIG. 1, the image light emitted from the image forming apparatus 3 </ b> G enters the projection optical system 4 via the color synthesis optical system 6. The projection optical system 4 forms an image plane optically conjugate with the image forming apparatus 3G (object plane), and an image formed by the image forming apparatus 3G is projected on the projection plane SC arranged on the image plane. Is done.

FIG. 3 is a diagram for explaining the shift of the optical path by the optical path shift device 11.
In FIG. 3, the rotation angle of the prism 17 is the reference position when the rotation position where the light from the light source device 7 is incident on the first surface 17a from the normal direction of the first surface 17a is the reference position (0 °). The rotation angle of the prism 17 from
In FIG. 3, the direction in which the rotation axis R of the prism extends is the Y1 axis direction, and the two orthogonal directions in the plane perpendicular to the Y1 axis are the X1 axis direction and the Z1 axis direction, respectively.

  In FIG. 3, the light incident on the first surface 17 a in a state where the rotation angle is 0 ° is emitted from the second surface 17 b through the inside of the prism 17. In a state where the rotation angle is 0 °, the light incident on the first surface 17a is not refracted by the first surface 17a and the second surface 17b. Therefore, the incident side optical path to the first surface 17a (hereinafter referred to as the incident side optical path Lx1) and the emission side optical path from the second surface 17b (hereinafter referred to as the emission side optical path Lx2) are on the same straight line.

  In a state where the rotation angle is equal to or smaller than a predetermined angle (for example, 15 °), substantially all of the light from the light source device 7 is incident on the first surface 17a. The light incident on the first surface 17a is refracted by the first surface 17a and the second surface 17b and is emitted from the second surface 17b. Since the first surface 17a and the second surface 17b are parallel to each other, the incident side optical path Lx1 and the emission side optical path Lx2 are parallel to each other. Further, the position of the incident side optical path Lx1 in the direction (here, the X1 axis direction) intersecting the direction of the optical axis (Z1 axis direction) is deviated from the position of the emission side optical path Lx2 in the X1 axis direction. That is, the emission side optical path Lx2 is shifted from the incident side optical path Lx1 in the X1 axis direction.

  The shift amount d (hereinafter referred to as optical path shift amount d) between the incident side optical path Lx1 and the exit side optical path Lx2 is the refractive index of the prism 17, the distance between the first surface 17a and the second surface 17b, and the rotation of the prism 17. It depends on the corner. In other words, the optical path shift amount d changes according to the rotation angle of the prism 17, and the optical path shift amount d also changes with time as the rotation angle of the prism 17 changes with time.

  When the rotation angle becomes equal to or greater than a predetermined angle (for example, 30 °), the light from the light source device 7 enters the first surface 17a and the third surface 17c. Of the light from the light source device 7, the light incident on the first surface 17a (hereinafter referred to as the first partial light Ba) is refracted by the first surface 17a and the second surface 17b, and the emission side optical path is the first partial light. Shifting in the positive direction of the X1 axis with respect to the Ba incident side optical path. On the other hand, light incident on the third surface 17c (hereinafter referred to as second partial light Bb) out of the light from the light source device 7 is refracted by the third surface 17c and the fourth surface 17d, and the emission side optical path is the second portion. It shifts in the negative direction of the X1 axis with respect to the incident side optical path of the light Bb. The emission side optical path of the first partial light Ba and the emission side optical path of the second partial light Bb are offset from each other in the X1-axis direction, and are optical paths that do not overlap each other here.

  As the rotation angle becomes larger than a predetermined angle, the amount of light incident on the first surface 17a (the ratio of the first partial light Ba to the light from the light source device 7) decreases and enters the third surface 17c. The amount of light (the ratio of the second partial light Bb to the light from the light source device 7) increases. Here, when the rotation angle is 45 °, about half of the light from the light source device 7 is incident on the first surface 17a, and the remaining half is incident on the third surface 17c. In a state where the rotation angle is about 45 °, the emission side optical path of the first partial light Ba and the emission side optical path of the second partial light Bb are symmetrical with respect to the plane including the rotation axis R of the prism 17 and the light traveling direction. Become.

  The exit-side optical path of the first partial light Ba and the exit-side optical path of the second partial light Bb are optical paths while the rotation angle changes from 0 ° to 45 ° while the rotation angle changes from 45 ° to 90 °. The mode of change and the Y1-Z1 plane change symmetrically. For example, the emission side optical path of the first partial light Ba in a state where the rotation angle is 60 ° (45 ° + 15 °) is the emission side optical path of the first partial light Ba in a state of 30 ° (45 ° −15 °). On the other hand, it becomes symmetrical with respect to the Y1-Z1 plane. When the rotation angle reaches 90 °, the light from the light source device 7 enters the third surface 17c from the normal direction, which is the same as the state where the rotation angle is 0 °. In this way, the optical path shift device 11 temporally changes the incident position of the light emitted from the light source device 7 to the diffractive optical element 12.

  The optical path shift device 11 determines the incident position of the light emitted from the light source device 7 to the diffractive optical element 12 in the same manner as when the rotation angle changes from 0 ° to 90 ° while the rotation angle changes by 90 °. Change. While the prism 17 rotates once, the incident position changes for four periods. Therefore, when the rotation speed of the prism 17 is 6 rotations or more per second, the incident position changes 24 times or more per second (one cycle is 1/24 seconds or less), and the angle of light incident on each point in the illuminated region IR. The distribution changes with a period of 1/24 seconds or less. As a result, the speckle pattern changes at a speed higher than a human-identifiable speed (period is 1/24 seconds or less), and is less likely to be visually recognized by a viewer as a fixed pattern.

Although not shown in FIG. 2 because the drawing becomes difficult to see, actually, the rotation axis R of the prism 17 is not arranged in a direction perpendicular to the paper surface of FIG. 2 is inclined from the direction perpendicular to the paper surface. As shown in FIG. 4, when the direction in which the laser light sources 15 are arranged in the horizontal direction when viewed from the direction of the optical axis AX of the light source device 7 is taken as the X-axis direction, and the direction in which the laser light sources 15 are arranged in the vertical direction The rotation axis R of the prism 17 is arranged not in a direction parallel to the X-axis direction or the Y-axis direction but in a direction intersecting with the X-axis direction and the Y-axis direction. For example, in the example of FIG. 4, the angle θ1 formed between the rotation axis R of the prism 17 and the x-axis (negative direction) is, for example, about 60 ° to 70 °.
The rotation axis R of the prism 17 does not necessarily have to be orthogonal to the direction of the optical axis AX of the light source device 7, that is, the Z-axis direction, and may intersect with the Z-axis direction at an angle other than a right angle.

FIG. 5 shows a locus of an irradiation region of light that shifts on the diffractive optical element 12 when the prism 17 is rotated.
As described with reference to FIG. 3, the direction in which the optical paths of the plurality of lights emitted from the light source device 7 are shifted is a direction orthogonal to the rotation axis R of the prism 17. Therefore, in the case of the present embodiment, as indicated by an arrow S1 in FIG. 5, the direction in which the optical paths of the plurality of lights are shifted is a direction that intersects the X-axis direction and the Y-axis direction.

  In the state where the optical path of light is not shifted (the state where the rotation angle is 0 ° in FIG. 3), the positions of the plurality of light irradiation regions SH are the positions of the laser light source 15 when viewed from the direction of the optical axis AX of the light source device 7. Suppose that At this time, the locus K of the irradiation region SH formed by shifting the optical path of the light when the prism 17 is rotated has a shape extending elongated in a direction orthogonal to the rotation axis R of the prism 17. An angle θ2 formed by the direction in which the locus K of the light irradiation region SH extends, that is, the direction in which the light path of light shifts and the X axis (positive direction) is, for example, about 20 ° to 30 °.

  However, when a mirror or the like is disposed between the light source device 7 and the prism 17 and the optical path of the light emitted from the light source device 7 is bent, a plurality of light sources are viewed from the direction of the optical axis AX of the light source device 7. The position of the light irradiation region SH and the position of the laser light source 15 do not match. In this case, it can be considered that the optical path of light is extended linearly assuming that there is no mirror.

  Among the nine laser light sources 15 shown in FIG. 5, three laser light sources 15 arranged two-dimensionally are selected, and these three laser light sources 15 are selected as the first laser light source 15A and the second laser light source. 15B and the third laser light source 15C. At this time, the distance between the second laser light source 15B and the first laser light source 15A and the distance between the third laser light source 15C and the first laser light source 15A are the same as those of the nine laser light sources 15. Among these, the first laser light source 15A and the second laser are shorter than the distance between any one of the laser light sources 15 other than the second laser light source 15B and the third laser light source 15C and the first laser light source 15A. The light source 15B and the third laser light source 15C are selected. As an example of how to select a light source that satisfies this condition, among the nine laser light sources 15, the middle laser light source in the middle is the first laser light source 15A, and the right laser light source in the middle is the second laser light source 15B. The upper center light source is defined as a third laser light source 15C.

  When the first laser light source 15A, the second laser light source 15B, and the third laser light source 15C are selected as in the above example, the direction in which the optical path of light shifts is the first laser light source 15A and the second laser light source 15A. Any direction may be used as long as it connects the region between the laser light source 15B and the third laser light source 15C. In other words, in the above example, the angle θ2 formed by the direction in which the optical path of light shifts and the X axis (positive direction) may be an angle that is larger than 0 ° and smaller than 90 °.

  As shown in FIG. 6, it is assumed that the rotation axis R1 of the prism 117 is arranged parallel to the Y-axis direction. That is, it is assumed that the angle θ3 formed by the rotation axis R1 of the prism 117 and the X axis (negative direction) is 90 °. In this case, as indicated by an arrow S2 in FIG. 7, the direction in which the optical paths of the plurality of lights are shifted is a direction parallel to the X-axis direction. The angle formed by the X axis and the direction in which the locus K of the light irradiation region SH extends, that is, the direction in which the light path of light shifts, is 0 °.

  In this case, the trajectories K of the light irradiation areas SH from the three laser light sources 115 arranged in the X-axis direction overlap. Therefore, when viewed as a whole of the diffractive optical element 112, a region where no light is irradiated is formed between the trajectories K of the light irradiation region SH, and the unevenness of the illuminance distribution increases. On the other hand, in the case of the present embodiment, as shown in FIG. 5, the overlapping of the locus K of the light irradiation region SH is small, and there are few regions where the light is not irradiated. As described above, the unevenness of the illuminance distribution in the diffractive optical element 12 is reduced, so that the uniformity of the illuminance distribution in the image forming apparatus 3G is improved and the uniformity of the incident angle distribution is improved. Thereby, speckle can be reduced.

The direction in which the optical path of light shifts will be further described.
For example, as shown in FIG. 8, the light source adjacent to the upper side of the first laser light source 15A is the second laser light source 15B with the first laser light source 15A as the center, and is adjacent to the right side of the first laser light source 15A. The light source is a third laser light source 15C. The first laser light source 15A, the second laser light source 15B, and the third laser light source 15C are two-dimensionally arranged, and the distance between the second laser light source 15B and the first laser light source 15A and the first laser light source 15A The distance between the third laser light source 15C and the first laser light source 15A is any one of the nine laser light sources other than the second laser light source 15B and the third laser light source 15C and the first laser light source. When the first laser light source 15A and the second laser light source 15B are determined as shown in FIG. 8 in order to satisfy the condition of being shorter than the distance to the light source 15A, for example, the hatched light source is the third light source. It is not selected as the laser light source 15C.

  At this time, the direction in which the optical path of light shifts is the direction connecting the first laser light source 15A and the region between the second laser light source 15B and the third laser light source 15C. In other words, the angle θ2 formed by the direction in which the optical path of light shifts and the X axis (positive direction) is larger than 0 ° and smaller than 90 °. An example of a preferable direction as a direction in which the optical path of light shifts is indicated by a solid line arrow of S1, and an example of a direction to be avoided as a direction in which the optical path of light shifts is indicated by a dashed arrow of reference numerals B1 and B2. When the angle θ2 formed by the direction in which the optical path of the light is shifted and the X axis is 45 °, the locus of the irradiation region of the light from the first laser light source 15A is adjacent to the first laser light source 15A in an oblique direction. It overlaps with the locus of the irradiation area of the light from the matching laser light sources 15E and 15F. Even in that case, the uniformity of the illuminance distribution in the diffractive optical element 12 can be improved as compared with the case where the angle θ2 formed by the direction in which the optical path of light shifts and the X axis is 0 ° or 90 °.

  Next, as shown in FIG. 9, a laser light source group in which one row of laser light source groups composed of a plurality of light sources arranged in the horizontal direction and an upper or lower laser light source group of the laser light source groups are adjacent in the horizontal direction. Let us consider a case in which all the laser light sources are arranged in a close-packed arrangement, with a shift by a half pitch of the pitch. Also in this case, when the first laser light source 15A and the second laser light source 15B are determined as shown in FIG. 9, for example, a hatched light source is not selected as the third laser light source 15C. An example of a preferable direction as a direction in which the optical path of light shifts is indicated by a solid line arrow of S1, and an example of a direction to be avoided as a direction of shift of the optical path of light is indicated by broken line arrows of B1, B2, and B3.

For example, the pitch may be different between a plurality of laser light sources corresponding to the central portion of the light source device and a plurality of laser light sources corresponding to the peripheral portion in order to correspond to the outer shape of the lens.
The example shown in FIG. 10 is an example in which the pitch between the laser light sources for two rows on the left and the right is made smaller than the pitch between the laser light sources in the center. In this case, the first laser light source 15A, the second laser light source 15B, and the third laser light source 15C may be selected from a plurality of laser light sources corresponding to the central portion of the light source device, or a plurality of laser light sources corresponding to the peripheral portion. You may choose from. An example of a preferable direction as a direction in which the optical path of light shifts is indicated by a solid line arrow of S1, and an example of a direction to be avoided as a direction in which the optical path of light shifts is indicated by a dashed arrow of reference numerals B1 and B2.

  The example shown in FIG. 11 is an example in which the pitch between the laser light sources for one row on each of the left and right sides is made smaller than the pitch between the laser light sources in the center. In this case, the first laser light source 15A, the second laser light source 15B, and the third laser light source 15C may be selected from a plurality of laser light sources corresponding to the central portion of the light source device, or a plurality of laser light sources corresponding to the peripheral portion. You may choose from. When a plurality of laser light sources corresponding to the peripheral portion are selected, when the first laser light source 15A and the second laser light source 15B are determined as shown in FIG. 11, for example, a hatched light source is used as the third laser light source 15C. Not selected. An example of a preferable direction as a direction in which the optical path of light shifts is indicated by a solid line arrow of S1, and an example of a direction to be avoided as a direction in which the optical path of light shifts is indicated by a dashed arrow of reference numerals B1 and B2.

In the illumination device 2G of the present embodiment, the rotational speed of the prism 17 may change with time or may be constant.
When the rotational speed of the prism 17 is changed with time, the time-averaged illuminance distribution of the light L emitted from the prism 17 is constant regardless of the position emitted from the prism 17, as shown in FIG. can do. In other words, the time-averaged illuminance distribution of the light L emitted from the prism 17 can be a top hat type. Thereby, the time-averaged illuminance distribution in the illuminated area IR of the image forming apparatus 3G can be made substantially constant.

  On the other hand, when the rotation speed of the prism 17 is constant, as shown in FIG. 13, the time-averaged illuminance distribution of the light emitted from the prism 17 has an illuminance in the region corresponding to the peripheral edge of the prism 17. In the region corresponding to the central portion of the prism 17, the illuminance is low. As described above, the speckle can be more effectively reduced by increasing the time-averaged illuminance at the peripheral portion of the light irradiation region.

  In the illuminating device 2G of the present embodiment, when the light irradiation regions SH are overlapped, as shown in FIG. 14, on the reference plane perpendicular to the optical axis AX of the light source device 7, the locus of the bottom of the intensity distribution of the first light Is preferably overlapped with the bottom locus of the second light intensity distribution. In FIG. 14, in the ellipse indicating the light irradiation region SH, a portion that appears whitish indicates a portion where the light intensity is relatively high, and a portion that appears blackish indicates a portion where the light intensity is relatively low. Since the illuminance distribution of the laser light is basically a Gaussian distribution, by overlapping the bottom portions of the intensity distribution, the intensity of the overlapping portion can be brought close to the peak intensity, and the illuminance distribution can be made uniform.

[Second Embodiment]
Hereinafter, a second embodiment of the present invention will be described with reference to FIG.
In the second embodiment, the basic configuration of the projector is the same as that of the first embodiment, and the configuration of the illumination device is different from that of the first embodiment.
FIG. 15 is a schematic configuration diagram illustrating the illumination device according to the second embodiment.
In FIG. 15, the same components as those in FIG. 2 used in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 15, the illumination optical system 37 constituting the illumination device 31 </ b> G of the second embodiment includes a diffusion plate 32 and an integrator optical system 33 on the optical path between the prism 17 and the superimposing optical system 13. Yes. The diffusion plate 32 and the integrator optical system 33 are arranged in this order along the light traveling direction. As the diffusing plate 32, a material in which particles having a refractive index different from that of the base material are dispersed in the base material, or a surface in which unevenness is formed on one surface of the base material is used. The diffusion plate 32 has a function of diffusing incident light to widen the angle distribution. In order to increase the light use efficiency, it is desirable that the diffusion angle of the diffusion plate 32 is set to a size that allows the integrator optical system 33 to swallow light whose angular distribution is widened by the diffusion plate 32.

  The integrator optical system 33 includes a first lens array 34 and a second lens array 35. The first lens array 34 has a plurality of lenses 36 that are two-dimensionally arranged in two directions orthogonal to the illumination optical axis AX of the light source device 7 (X-axis direction and Y-axis direction in FIG. 15). The second lens array 35 is disposed on the light emission side of the first lens array 34 and has the same configuration as the first lens array 34. The first lens array 34 has a function of dividing light incident from the diffusion plate 32 into a plurality of light beams. The second lens array 35 has a function of transmitting each of the plurality of light beams incident from the first lens array 34 to the illumination area IR of the image forming apparatus 3G that is the same illumination area. Other configurations are the same as those of the first embodiment.

  In the case of the second embodiment, since the diffusion plate 32 is provided on the light incident side of the integrator optical system 33, light with high uniformity in illuminance distribution and angular distribution enters the first lens array 34. Therefore, the uniformity of the illuminance distribution and the angular distribution of the light irradiated to the second lens array 35 is increased, and speckle can be effectively reduced.

[Third Embodiment]
Hereinafter, a third embodiment of the present invention will be described with reference to FIG.
In the third embodiment, the basic configuration of the projector is the same as that of the first embodiment, and the configuration of the illumination device is different from that of the first embodiment.
FIG. 16 is a schematic configuration diagram illustrating the illumination device according to the third embodiment.
In FIG. 16, the same reference numerals are given to the same components as those in FIG. 2 used in the first embodiment, and detailed description thereof will be omitted.

  As shown in FIG. 16, the illumination optical system 42 constituting the illumination device 41G of the third embodiment includes an integrator optical system 33 on the optical path between the prism 17 and the superimposing optical system 13. That is, the illumination device 41G of the third embodiment is obtained by removing the diffusion plate 32 from the illumination device 31G of the second embodiment. Other configurations are the same as those of the second embodiment.

  In the case of the third embodiment, since the diffusion plate is not provided on the light incident side of the integrator optical system 33, the light source image formed on the second lens array 35 becomes discrete within a very short time. That is, when the prism 17 is at the position indicated by the solid line, the optical path of the light from the light source device 7 is shifted in the negative direction of the X axis, so that the light is directed to the lower lens 36 of the second lens array 35. Incident but not incident on the upper lens 36. When the prism 17 is at the position indicated by the two-dot chain line, the optical path of the light from the light source device 7 is shifted in the positive direction of the X axis, so that the light is the upper lens 36 in the second lens array 35. And does not enter the lower lens 36. However, the time-averaged illuminance distribution on the illuminated area IR of the image forming apparatus 3G is constant, and illuminance unevenness can be reduced.

[Fourth Embodiment]
Hereinafter, a fourth embodiment of the present invention will be described with reference to FIG.
In the fourth embodiment, the basic configuration of the projector is the same as that of the first embodiment, and the configuration of the illumination device is different from that of the first embodiment.
FIG. 17 is a schematic configuration diagram illustrating the illumination device according to the fourth embodiment.
In FIG. 17, the same components as those in FIG. 2 used in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 17, the illumination optical system 52 constituting the illumination device 51G of the fourth embodiment includes a diffractive optical element 53 on the optical path between the prism 17 and the image forming device 3G. The illumination optical system 52 of the fourth embodiment does not include a superimposing optical system. Unlike the diffractive optical element 12 of the first embodiment, the diffractive optical element 53 of the fourth embodiment generates a diffracted light pattern that differs depending on where light enters. In other words, the first diffracted light pattern formed by the first light emitted from the first laser light source 15A and the diffractive optical element 53 is diffracted from the second light emitted from the second laser light source 15B. This is different from the second diffracted light pattern formed by the optical element 53. Other configurations are the same as those of the first embodiment.

  In the case of the fourth embodiment, speckles can be effectively reduced by temporally superimposing a plurality of different diffracted light patterns on the illuminated region IR by the diffractive optical element 53.

[Fifth Embodiment]
Hereinafter, a fifth embodiment of the present invention will be described with reference to FIG.
The projector according to the fifth embodiment is an example of a projector including a digital micromirror device (DMD, registered trademark of Texas Instruments) as a light modulation device.
FIG. 18 is a schematic configuration diagram illustrating the illumination device of the fifth embodiment.
In FIG. 18, the same components as those in FIG. 2 used in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 18, the illumination optical system 62 constituting the illumination device 61G of the fifth embodiment includes a rod lens 63 between the first lens 18 and the second lens 19 constituting the superposition optical system 13. I have. The rod lens 63 has a function of emitting light with uniform intensity distribution by guiding light incident from the light incident end face inside. When the prism 17 is rotated, the incident angle of the light to the rod lens 63 changes with time, and the intensity distribution of the light emitted from the rod lens 63 is made uniform over time. The light having the uniform intensity distribution illuminates the illuminated area of the DMD 64 through the second lens 19. The light incident on the DMD 64 is reflected by a micromirror (not shown) provided for each pixel and projected on the screen by the projection optical system 4.

  Also in the illuminating device 61G of the fifth embodiment, the uniformity of the illuminance distribution and the angular distribution of light can be improved, and speckle can be effectively reduced.

The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, in the above embodiment, the rotating prism is used as the optical path shift device, but the following optical path shift device may be used instead of the rotating prism.

  FIG. 19 is a diagram showing an optical path shift device 71 according to a modification. The optical path shift device 71 includes a first mirror 72 on which light from the light source device 7 is incident, a second mirror 73 that guides light reflected by the first mirror 72 to the superposition optical system 13, and a first mirror 72. And a moving unit 74 for moving.

  The first mirror 72 is inclined such that the reflection surface forms an angle of 45 ° with respect to the light emission direction L1 from the light source device 7. The second mirror 73 is inclined such that the reflection surface forms an angle of 45 ° with respect to the optical axis AX2 of the superposition optical system 13. The 1st mirror 72 and the 2nd mirror 73 are arrange | positioned so that it may mutually become substantially parallel. The moving unit 74 moves the first mirror 72 in a direction perpendicular to the light emission direction L <b> 1 from the light source device 7.

  In this modification, the incident position on the first mirror 72 of the light emitted from the light source device 7 changes with time as the first mirror 72 is moved by the moving unit 74, and the second mirror 73. The incident position above changes with time. Therefore, even with such an optical path shift device 71, the incident position of the light incident on the superimposing optical system 13 can be temporally changed in a direction intersecting the direction of the optical axis AX2.

  The moving direction of the first mirror 72 may be parallel to or intersecting with the light emission direction L1 of the light source device 7. Further, the optical path shift device 71 may be configured to move the second mirror 73 instead of moving the first mirror 72, or may be configured to move both the first mirror 72 and the second mirror 73. . When both the first mirror 72 and the second mirror 73 are moved, the moving speed of each mirror and the relative position of both mirrors change the incident position of the light incident on the superposition optical system 13. It can be set appropriately. Further, the first mirror 72 and the second mirror 73 may not be arranged in parallel to each other. The optical path shift device 71 may be configured to shift the optical path by rotating one or both of the first mirror 72 and the second mirror 73, or may be configured to shift the optical path by both rotation and translation of the mirror. .

  In addition, specific configurations such as shapes, numbers, and arrangements of various components in the illumination device and the projector are not limited to the above-described embodiments, and can be changed as appropriate.

  DESCRIPTION OF SYMBOLS 1 ... Projector, 2R, 2G, 2B, 31G, 41G, 51G, 61G ... Illuminating device, 3R, 3G, 3B ... Image forming device, 4 ... Projection optical system, 7 ... Light source device, 10 ... Collimating optical system, 11, DESCRIPTION OF SYMBOLS 71 ... Optical path shift device, 12 ... Diffractive optical element, 15 ... Laser light source, 15A ... 1st laser light source, 15B ... 2nd laser light source, 15C ... 3rd laser light source, 17 ... Prism, 33 ... Integrator optical system 34 ... 1st lens array, 35 ... 2nd lens array, 36 ... Lens.

Claims (11)

A plurality of first light sources that emit two-dimensionally arranged first coherent light, a second light source that emits second coherent light, and a third light source that emits third coherent light. A light source device comprising a light source;
An optical path shift device that temporally shifts the optical paths of the plurality of coherent lights emitted from the light source device in a predetermined direction,
The distance between the second light source and the first light source and the distance between the third light source and the first light source are the second light source and the third light source among the plurality of light sources. Shorter than the distance between any light source other than the light source and the first light source,
The illumination device according to claim 1, wherein the predetermined direction is a direction connecting the first light source and a region between the second light source and the third light source.   In the optical path shift device, the locus of the tail of the intensity distribution of the first coherent light and the locus of the tail of the intensity distribution of the second coherent light overlap each other on a reference plane perpendicular to the optical axis of the light source device. The lighting device according to claim 1, wherein optical paths of the plurality of coherent lights are temporally shifted.   The illuminating device according to claim 1, wherein the optical path shift device includes a rotatable prism.   The lighting device according to claim 3, wherein the rotation speed of the prism changes with time.   The lighting device according to claim 3, wherein a rotation speed of the prism is constant.   A collimating optical system provided in an optical path between the light source device and the optical path shift device, and a diffractive optical element on which a plurality of coherent lights incident via the optical path shift device are further provided. The lighting device according to any one of claims 1 to 5.   The first diffracted light pattern formed by the first coherent light and the diffractive optical element is different from the second diffracted light pattern formed by the second coherent light and the diffractive optical element. The lighting device according to claim 6. The first diffracted light pattern formed by the first coherent light and the diffractive optical element is the same as the second diffracted light pattern formed by the second coherent light and the diffractive optical element. ,
The illumination apparatus according to claim 6, further comprising a superimposing optical system that superimposes the first diffracted light pattern and the second diffracted light pattern on an illumination target.   A collimating optical system provided in an optical path between the light source device and the optical path shift device, and an integrator optical system into which a plurality of coherent lights incident via the optical path shift device are provided. The lighting device according to any one of claims 1 to 5. The integrator optical system includes a first lens array having a plurality of lenses, and a second lens array having a plurality of lenses,
The illumination device according to claim 9, further comprising a diffusion plate on a light incident side of the integrator optical system. The lighting device according to any one of claims 1 to 10,
A light modulation device for modulating light from the illumination device;
A projection optical system that projects the light modulated by the light modulation device;
A projector characterized by comprising: