Light source device and projection type image display device

Abstract

This light source device comprises: a first light source unit that emits first linearly polarized light; a half mirror that separates the light emitted from the first light source into a first light that advances in a first light path, and a second light that advances in a second light path; a polarized-light-combining mirror that combines the first light and the second light; a light path change element that is positioned in the second light path, the light path change element reflecting the second light and guiding the second light to the polarized-light-combining mirror; and a phase difference plate that is positioned in the second light path, the phase difference plate converting the second light into second linearly polarized light that is inclined relative to the first linearly polarized light. The light path change element is positioned such that a point image of the first light and a point image of the second light in the polarized-light-combining mirror are alternately positioned in the minor-axis direction of the point images.

Description

Technical Field

[0001] The present disclosure relates to, for example, a light source device and a projection type image display device including the light source device.

Background Art

[0002] Conventionally, since the linearly polarized light emitted from a plurality of solid light source elements, for example, laser light sources, is coherent light, an interference pattern called a speckle pattern in which bright spots and dark spots are randomly distributed may appear.

[0003] In Patent Document 1, the light emitted from one light source is split according to the type of polarization, and the generation of speckles is reduced by polarization multiplexing in which the further split light is combined.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

[0005] However, when a solid light source element is used, since the polarization of the light emitted from the light source is uniform, the ratio of the split light beams is greatly different, and the advantage of splitting according to the type of polarization is impaired.

[0006] An object of the present disclosure is to provide a light source device and a projection type image display device that reduce speckles.

[0007] The light source device of the present disclosure includes a first light source unit having a plurality of solid light source elements two-dimensionally arranged at a predetermined pitch and emitting light of first linearly polarized light, a half mirror that reflects and transmits the emitted light from the first light source unit and separates it into first light traveling in a first optical path and second light traveling in a second optical path, a polarization synthesis mirror that transmits and reflects light according to the type of polarization and synthesizes the first light and the second light, an optical path changing element disposed on the second optical path that reflects the second light and guides it to the polarization synthesis mirror, and a retardation plate disposed on the second optical path that converts the second light into second linearly polarized light that is inclined with respect to the first linearly polarized light. The optical path changing element is arranged such that the point image of the first light and the point image of the second light in the polarization synthesis mirror are alternately arranged in the minor axis direction of the point image of the first light and the point image of the second light.

[0008] The light source device of the present disclosure further includes a second light source unit having a plurality of solid light source elements two-dimensionally arranged at a predetermined pitch and emitting light of first linearly polarized light. The half mirror reflects and transmits the emitted light from the second light source unit and separates it into third light traveling in the first optical path and fourth light traveling in the second optical path. The polarization synthesis mirror synthesizes the first light, the second light, the third light, and the fourth light. The optical path changing element reflects the fourth light and guides it to the polarization synthesis mirror. The retardation plate converts the fourth light into second linearly polarized light. The first light source unit and the second light source unit are arranged such that the point image of the emitted light from the first light source unit and the point image of the emitted light from the second light source unit in the half mirror are alternately arranged in the major axis direction of the point image of the emitted light from the first light source unit and the point image of the emitted light from the second light source unit. The optical path changing element is arranged such that the point image of the third light and the point image of the fourth light in the polarization synthesis mirror are alternately arranged in the minor axis direction of the point image of the third light and the point image of the fourth light.

[0009] The projection type image display device of the present disclosure includes the above-described light source device, a light modulation element that modulates the light incident from the light source device based on an external signal, and a projection lens that magnifies and projects the light modulated by the light modulation element.

[0010] The light source device and the projection type image display device in the present disclosure can provide a light source device and a projection type image display device with reduced speckle.

Brief Description of the Drawings

[0011]

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Modes for Carrying Out the Invention

[0012] Hereinafter, embodiments will be described in detail with appropriate reference to the drawings. However, a more detailed description than necessary may be omitted. For example, a detailed description of well-known matters or a redundant description of substantially the same configuration may be omitted. This is to avoid making the following description unnecessarily redundant and to facilitate the understanding of those skilled in the art.

[0013] Note that the inventor(s) provide the accompanying drawings and the following description so that those skilled in the art can fully understand the present disclosure, and do not intend to limit the subject matter described in the claims thereby.

[0014] (Embodiment 1) Hereinafter, Embodiment 1 will be described with reference to FIGS. 1 and 2.

[0015] [1-1. Configuration] FIG. 1 is a schematic diagram showing the configuration of the light source device 1 and the point image of the laser light in Embodiment 1 of the present disclosure. FIG. 2 is a schematic diagram showing the configuration of the first light source unit 3. For the convenience of the following description, in FIG. 1, an XYZ orthogonal coordinate system shown in the figure is adopted. In addition, the emitted light emitted from the first light source unit 3 will be described using the abc orthogonal coordinate system shown in the figure.

[0016] The light source device 1 includes a first light source unit 3, a half mirror 5, a first polarization combining mirror 7, a mirror 9 (an example of a first mirror), a mirror 11 (an example of a second mirror), and a retardation plate 13.

[0017] The first light source unit 3 is, for example, a light source array having a plurality of solid light source elements 3a arranged in a two-dimensional direction determined by the Y direction and the Z direction, and collimating lenses arranged corresponding to the respective solid light source elements 3a. That is, the plurality of solid light source elements 3a are two-dimensionally arranged as shown in FIG. 2. Each solid light source element 3a is arranged at a predetermined pitch. In Embodiment 1, for example, 24 solid light source elements 3a of 4 rows × 6 columns are arranged. The solid light source element 3a is, for example, a semiconductor laser. The optical axes of the respective lights emitted from the respective solid light source elements 3a are parallel. Each first emitted light Lt1 emitted from each solid light source element 3a is, as a first linearly polarized light, for example, laser light of P polarization, and has an elliptical shape having a minor axis Db and a major axis Dc.

[0018] The half mirror 5 reflects and transmits the first emitted light Lt1 emitted from the first light source unit 3, and separates it into a first light Lh1 that travels along the first optical path Lp1 and a second light Lh2 that travels along the second optical path Lp2. The first optical path Lp1 is a straight-ahead optical path from the half mirror 5 to the first polarization combining mirror 7. The second optical path Lp2 is a detour optical path that is longer in distance than the first optical path Lp1. The second optical path Lp2 is, for example, an optical path that extends from the half mirror 5 through the mirrors 9 and 11 and the retardation plate 13 to the first polarization combining mirror 7. Note that the half mirror 5 is a mirror whose transmission and reflection ratios of incident light rays are adjusted, and is a mirror that transmits part of the incident light rays and reflects part of them. In that sense, it is not necessary for the transmission and reflection ratios to be 1:1, and the ratios can be adjusted as appropriate.

[0019] The mirrors 9 and 11 as optical path changing elements are disposed on the second optical path Lp2, and reflect the second light Lh2 and guide it to the first polarization combining mirror 7. The direction of the second optical path Lp2 is changed by the mirrors 9 and 11.

[0020] The retardation plate 13 is disposed on the second optical path Lp2, and converts the transmitted second light Lh2 into S-polarized light that is inclined with respect to P-polarized light. The retardation plate 13 is, for example, a half-wave plate (λ / 2 plate). In FIG. 1, the retardation plate 13 is disposed between the mirror 11 and the polarization combining mirror, but may be disposed at other locations as long as it is on the second optical path Lp2. For example, the retardation plate 13 may be disposed between the half mirror 5 and the mirror 9, or between the mirror 9 and the mirror 11.

[0021] The first polarization combining mirror 7 transmits and reflects according to the type of polarization, and combines the first light Lh1 and the second light Lh2. The first polarization combining mirror 7 is, for example, a polarization beam splitter. The first polarization combining mirror 7 has, for example, the property of transmitting P-polarized light and reflecting S-polarized light. Therefore, the first light Lh1 that travels along the first optical path Lp1 passes through the first polarization combining mirror 7. Also, the second light Lh2 that travels along the second optical path Lp2 is reflected by the first polarization combining mirror 7 in the traveling direction of the first light Lh1. In this way, the first light Lh1 and the second light Lh2 are combined.

[0022] The light source device 1 further includes a lens 15, a diffusion plate 17, a lens 19, and a diffusion plate 21. The diffusion plate 21 is capable of vibrating in a plane direction (YZ plane) perpendicular to the optical axis. Thereby, speckle can be further reduced. The combined light Lm1 combined by the first polarization combining mirror 7 is emitted to the outside through the lens 15, the diffusion plate 17, the lens 19, and the diffusion plate 21.

[0023] Next, it is explained that the number of light beams is increased by separation and combination for the first emitted light Lt1 emitted from the first light source unit 3. The first emitted light Lt1 emitted from the first light source unit 3 is a P-polarized laser beam, and a light beam corresponding to the arrangement pitch of the solid light source elements 3a is irradiated onto the half mirror 5.

[0024] The half mirror 5 is arranged to be inclined at approximately 45° with respect to the first emitted light Lt1. Thereby, the point image of each first emitted light Lt1 irradiated on the half mirror 5 spreads in the minor axis Db direction more than the first emitted light Lt1 traveling in space.

[0025] The first emitted light Lt1 is separated by the half mirror 5 into a first light Lh1 that passes through the half mirror 5 and travels straight and a second light Lh2 that is reflected by the half mirror 5 and detours.

[0026] The pitch of each light beam of the first light Lh1 traveling in the first optical path Lp1 is the same as the pitch of each light beam of the first emitted light Lt1. The first light Lh1 enters the first polarization combining mirror 7.

[0027] The pitch of each light beam of the second light Lh2 traveling from the half mirror 5 along the second optical path Lp2 is the same as the pitch of each light beam of the first output light Lt1. The second light Lh2 is reflected by the mirrors 9 and 11, and its traveling direction changes. Also, the mirrors 9 and 11 are arranged on the first polarization combining mirror 7 such that the centers of the point images of the first light Lh1 and the centers of the point images of the second light Lh2 do not overlap. The mirrors 9 and 11 are arranged such that the point images of the first light Lh1 and the point images of the second light are alternately arranged in the first polarization combining mirror 7. For example, on the first polarization combining mirror 7, in the minor axis Db direction (Y direction) of the light beam of the first light Lh1, the point images of the light beams of the second light Lh2 are positioned between the point images of the respective light beams of the first light Lh1. Here, as shown in FIG. 1, each of the point images of the first light Lh1 and the second light Lh2 has an elliptical shape. This elliptical shape has a minor axis and a major axis that are perpendicular to each other.

[0028] Therefore, the combined light Lm1 combined from the first light Lh1 and the second light Lh2 in the first polarization combining mirror 7 has twice the number of light beams of the first output light Lt1. Also, regarding the pitch of each light beam of the combined light Lm1, with respect to the first output light Lt1, the pitch in the major axis Dc direction of the light beam is the same, but the pitch in the minor axis Db direction is half the length. In this way, the number of solid light source elements 3a can be virtually doubled, and the number of light beams can be increased, so speckle can be suppressed.

[0029] [1-2. Effects, etc.] As described above, the light source device 1 according to Embodiment 1 includes a first light source unit 3 having a plurality of solid light source elements 3a arranged at predetermined pitches Py and Pz and emitting light of P-polarization as first linearly polarized light, and a half mirror 5 that reflects and transmits the first emitted light Lt1 from the first light source unit 3 and separates it into a first light Lh1 traveling along a first optical path Lp1 and a second light Lh2 traveling along a second optical path Lp2. Further, the light source device 1 includes a first polarization combining mirror 7 that transmits and reflects according to the type of polarization and combines the first light Lh1 and the second light Lh2, and mirrors 9 and 11 as optical path changing elements that are disposed on the second optical path Lp2 and reflect the second light Lh2 to guide it to the first polarization combining mirror 7. Furthermore, the light source device 1 includes a retardation plate 13 that is disposed on the second optical path Lp2 and converts the second light Lh2 into S-polarization as a second linearly polarized light inclined with respect to P-polarization, and the mirrors 9 and 11 are disposed such that the point image of the first light Lh1 and the point image of the second light Lh2 in the first polarization combining mirror 7 are alternately arranged.

[0030] The half mirror 5 divides the first emitted light Lt1, and on the first polarization combining mirror 7, by alternately arranging the point image of the light beam of the first light Lh1 that has traveled along the straight-ahead optical path and the point image of the light beam of the second light Lh2 that has traveled along the detour optical path, light source multiplexing can be realized and speckle reduction can be achieved.

[0031] (Embodiment 2) Hereinafter, Embodiment 2 will be described with reference to FIG. 3.

[0032] [2-1. Configuration] FIG. 3 is a schematic diagram showing the configuration of a light source device 1A according to Embodiment 2 of the present disclosure.

[0033] The light source device 1A of Embodiment 2 has a configuration in which another light source unit is added to the light source device 1 of Embodiment 1. The configurations of the light source device 1A of Embodiment 2 and the light source device 1 of Embodiment 1 are common except for this point and the points described below.

[0034] The light source device 1A includes a first light source unit 3, a half mirror 5, a first polarization combining mirror 7, a mirror 9, a mirror 11, and a retardation plate 13, similarly to the light source device 1, and further includes a second light source unit 23.

[0035] The second light source unit 23 is, for example, a light source array having a plurality of solid light source elements 3a arranged in a two-dimensional direction determined by the X direction and the Z direction, and collimating lenses arranged corresponding to the respective solid light source elements 3a. Each solid light source element 3a of the second light source unit 23 is arranged at the same pitch as the solid light source elements 3a of the first light source unit 3. Each second emitted light Lt2 emitted from the solid light source element 3a of the second light source unit 23 is, as the first linearly polarized light, for example, a laser beam of P polarization, and has an elliptical shape having a minor axis Db and a major axis Dc. The first emitted light Lt1 and the second emitted light Lt2 are orthogonal to each other, and a half mirror 5 is arranged on the orthogonal plane.

[0036] Each solid light source element 3a of the second light source unit 23 is arranged such that the point images of the respective light beams of the first emitted light Lt1 and the point images of the respective light beams of the second emitted light Lt2 do not overlap on the plane where the first emitted light Lt1 and the second emitted light Lt2 are orthogonal to each other, that is, on the half mirror 5. For example, on the half mirror 5, the first light source unit 3 and the second light source unit 23 are arranged such that the point images of the respective light beams of the first emitted light Lt1 and the point images of the respective light beams of the second emitted light Lt2 are shifted by a half pitch in the major axis Dc direction (Z direction) of the point image.

[0037] The half mirror 5 reflects and transmits the second emitted light Lt2 emitted from the second light source unit 23, similarly to the first emitted light Lt1, and separates it into a third light Lh3 traveling in the first optical path Lp1 and a fourth light Lh4 traveling in the second optical path Lp2. Therefore, in the first optical path Lp1, the light synthesized by the first light Lh1 and the third light Lh3 travels, and in the second optical path Lp2, the light synthesized by the second light Lh2 and the fourth light Lh4 travels.

[0038] The mirror 9 and the mirror 11 reflect the fourth light Lh4, similarly to the second light Lh2, and guide it to the first polarization combining mirror 7.

[0039] The retardation plate 13 converts the fourth light beam Lh4 into S-polarized light that is inclined with respect to P-polarized light, similar to the second light beam Lh2.

[0040] The first polarization combining mirror 7 transmits and reflects according to the type of polarization, and combines the first light beam Lh1, the second light beam Lh2, the third light beam Lh3, and the fourth light beam Lh4. The first light beam Lh1 and the third light beam Lh3 traveling along the first optical path Lp1 pass through the first polarization combining mirror 7. Also, the second light beam Lh2 and the fourth light beam Lh4 traveling along the second optical path Lp2 are reflected by the first polarization combining mirror 7 in the traveling direction of the first light beam Lh1 and the third light beam Lh3. In this way, the first light beam Lh1 to the fourth light beam Lh4 are combined.

[0041] Next, the second emitted light beam Lt2 will be described in terms of the increase in the number of light beams by separation and combination. The second emitted light beam Lt2 emitted from the second light source unit 23 is a P-polarized laser beam, and light beams corresponding to the array pitch of the solid light source elements 3a are irradiated onto the half mirror 5.

[0042] The half mirror 5 is arranged to be inclined at approximately 45° with respect to the second emitted light beam Lt2. As a result, the point image of each second emitted light beam Lt2 irradiated onto the half mirror 5 spreads in the minor axis Db direction more than the second emitted light beam Lt2 traveling in space.

[0043] The second emitted light beam Lt2 is separated by the half mirror 5 into the third light beam Lh3 that is reflected and travels along the first optical path Lp1 and the fourth light beam Lh4 that passes through the half mirror 5 and travels along the second optical path Lp2, which is a detour path.

[0044] The pitch of each light beam of the third light beam Lh3 traveling along the first optical path Lp1 is the same as the pitch of each light beam of the second emitted light beam Lt2. The third light beam Lh3 enters the first polarization combining mirror 7 together with the first light beam Lh1.

[0045] The pitch of each light beam of the second light Lh2 traveling from the half mirror 5 along the second optical path Lp2 is the same as the pitch of each light beam of the first emitted light Lt1. The second light Lh2 is reflected by the mirrors 9 and 11, causing a change in its traveling direction. Also, the mirrors 9 and 11 are arranged on the first polarization combining mirror 7 such that the centers of the point images of the first light Lh1 and the centers of the point images of the second light Lh2 do not overlap. The mirrors 9 and 11 are arranged such that the point images of the first light Lh1 and the point images of the second light are alternately arranged in the first polarization combining mirror 7. For example, on the first polarization combining mirror 7, in the minor axis Db direction (Y direction) of the light beams of the first light Lh1, the point images of the light beams of the second light Lh2 are positioned between the point images of each light beam of the first light Lh1.

[0046] Therefore, the combined light Lm2 synthesized from the first light Lh1 to the fourth light Lh4 in the first polarization combining mirror 7 has light beams emitted from a number of light source units equivalent to twice the original number. Also, regarding the pitch of each light beam of the combined light Lm2, for each of the first emitted light Lt1 and the second emitted light Lt2, the pitch in the major axis Dc direction and the minor axis Db direction of the light beam is half the original length. In this way, the number of light source units can be seemingly quadrupled, increasing the number of light beams, and thus speckle can be suppressed.

[0047] [2-2. Effects, etc.] As described above, the light source device 1A in Embodiment 2 includes a first light source unit 3 having a plurality of solid light source elements 3a arranged in a two-dimensional direction at predetermined pitches Py and Pz and emitting light polarized in the P-polarization direction as the first linearly polarized light, and a second light source unit 23 having a plurality of solid light source elements 3a arranged in a two-dimensional direction at predetermined pitches Py and Pz and emitting light of the first linearly polarized light. Further, the light source device 1A includes a half mirror 5 that reflects and transmits the first emitted light Lt1 from the first light source unit 3 and separates it into a first light Lh1 traveling along a first optical path Lp1 and a second light Lh2 traveling along a second optical path Lp2. The half mirror 5 reflects and transmits the emitted light from the second light source unit 23 and separates it into a third light Lh3 traveling along the first optical path Lp1 and a fourth light Lh4 traveling along the second optical path Lp2. Further, the light source device 1A includes a first polarization synthesis mirror 7 that transmits and reflects according to the type of polarization and synthesizes the first light Lh1, the second light Lh2, the third light Lh3, and the fourth light Lh4, and mirrors 9 and 11 as optical path changing elements that are disposed on the second optical path Lp2 and reflect the second light Lh2 and the fourth light Lh4 and guide them to the first polarization synthesis mirror 7. Further, the light source device 1 includes a retardation plate 13 that is disposed on the second optical path Lp2 and converts the second light Lh2 and the fourth light Lh4 into S-polarized light, which is a second linearly polarized light inclined with respect to the P-polarized light. The first light source unit 3 and the second light source unit 23 are arranged such that the point image of the first emitted light Lt1 from the first light source unit 3 and the point image of the emitted light Lt2 from the second light source unit 23 in the half mirror 5 are alternately arranged in the major axis Dc direction of the point image.

[0048] The half mirror 5 divides the first emitted light Lt1 and the second emitted light Lt2, and on the first polarization synthesis mirror 7, the point images of the respective light beams of the first light Lh1 and the third light Lh3 that have traveled along the straight-ahead optical path and the point images of the respective light beams of the second light Lh2 and the fourth light Lh4 that have traveled along the detour optical path are alternately arranged, whereby light source multiplexing can be realized and speckle reduction can be achieved.

[0049] (Embodiment 3) Hereinafter, Embodiment 3 will be described with reference to FIG. 4.

[0050] [3-1. Configuration] FIG. 4 is a schematic diagram showing the configuration of the light source device 1B in Embodiment 3 of the present disclosure.

[0051] The light source device 1B of Embodiment 3 has a configuration in which another light source unit is added to the light source device 1A of Embodiment 2. The configurations of the light source device 1B of Embodiment 3 and the light source device 1A of Embodiment 2 are common except for this point and the points described below.

[0052] The light source device 1B includes a first light source unit 3, a second light source unit 23, a third light source unit 31, a fourth light source unit 33, and a fifth light source unit 35. The light source device 1B also includes a half mirror 5, a retardation plate 13, a first dichroic mirror 9A, a second dichroic mirror 11A, a second polarization combining mirror 7A, and a third polarization combining mirror 37.

[0053] Each solid light source element 3a of the first light source unit 3 and the second light source unit 23 emits, for example, green laser light. The laser light emitted from the first light source unit 3 and the second light source unit 23 is light that is P-polarized light, respectively.

[0054] The optical path from the half mirror 5 directly to the second polarization combining mirror 7A is the first optical path Lp1, and the optical path that detours from the half mirror 5 through, for example, the first dichroic mirror 9A and the second dichroic mirror 11A to the second polarization combining mirror 7A is the second optical path Lp2.

[0055] The third light source unit 31 has the same configuration as the first light source unit 3, and each solid light source element 3a of the third light source unit 31 emits, for example, blue laser light. The emitted blue laser light travels toward the first dichroic mirror 9A.

[0056] The first dichroic mirror 9A is arranged in parallel with the half mirror 5. The first dichroic mirror 9A reflects the light incident from the half mirror 5 and transmits the light incident from the third light source unit 31. The first dichroic mirror 9A reflects, for example, green laser light and transmits blue laser light. Thereby, the green second light Lh2 traveling in the second optical path and the blue light are combined. The combined light of green and blue travels toward the second dichroic mirror 11A.

[0057] The second dichroic mirror 11A reflects the light incident from the first dichroic mirror and transmits the light from the second polarization combining mirror.

[0058] Both the fourth light source unit 33 and the fifth light source unit 35 emit laser light of the same color. Each solid light source element 3a of the fifth light source unit 35 is arranged so that the polarization of the emitted light is shifted by 90° from the polarization of the emitted light from each solid light source element 3a of the fourth light source unit 33. Each solid light source element 3a of the fifth light source unit 35 is arranged, for example, in a state rotated 90 degrees with respect to the emission direction of each solid light source element 3a of the fourth light source unit 33. In this way, for example, red laser light of P polarization is emitted from the fourth light source unit 33, and red laser light of S polarization is emitted from the fifth light source unit 35.

[0059] The third polarization combining mirror 37 transmits the light emitted from the fourth light source unit 33 and reflects the light emitted from the fifth light source unit 35. In this way, the respective emitted lights emitted from the fourth light source unit 33 and the fifth light source unit 35 are combined by the third polarization combining mirror 37 and emitted toward the second dichroic mirror 11A. The third polarization combining mirror 37 transmits, for example, laser light of P polarization and reflects laser light of S polarization.

[0060] The second dichroic mirror 11A transmits, for example, red laser light and reflects green and blue laser light. Therefore, by reflecting the green and blue laser light incident from the first dichroic mirror 9A and transmitting the red laser light incident from the third polarization combining mirror 37, the green, blue, and red laser lights are combined. The combined laser light is emitted toward the second polarization combining mirror 7A.

[0061] In the second polarization combining mirror 7A, the green first light Lh1 traveling along the first optical path Lp1, the green second light Lh2 traveling along the second optical path Lp2, the blue light, and the light obtained by combining the red light are combined. The combined three-color light is emitted from the second polarization combining mirror 7A toward the lens 15.

[0062] [3-2. Effects, etc.] As described above, in the light source device 1B according to the third embodiment, since one of the three-color lights is split by the half mirror 5 and the number of light beams increases, speckle can be reduced.

[0063] (Embodiment 4) Hereinafter, Embodiment 4 will be described with reference to FIG. 5.

[0064] [4-1. Configuration] FIG. 5 is a schematic diagram showing the configuration of the light source device 1C in the third embodiment of the present disclosure.

[0065] The light source device 1C of the fourth embodiment has a configuration in which another light source unit is added to the light source device 1A of the second embodiment in the same manner as in the third embodiment. The configuration of the light source device 1C of the fourth embodiment is common to the light source device 1A of the second embodiment or the light source device 1B of the third embodiment except for this point and the points described below.

[0066] The light source device 1C includes a first light source unit 3A, a second light source unit 23A, a third light source unit 31, a sixth light source unit 39, and a seventh light source unit 41. The light source device 1C also includes a half mirror 5, a mirror 9, a retardation plate 13, a third dichroic mirror 11B, a fourth polarization combining mirror 7B, a fourth dichroic mirror 43, and a third polarization combining mirror 37.

[0067] The first light source unit 3A corresponds to the first light source unit 3, and the second light source unit 23A corresponds to the second light source unit 23. The first light source unit 3A and the second light source unit 23 emit laser light of the same color, for example, red laser light.

[0068] The light emitted from the first light source unit 3A is split into a first light Lh1 that travels along the first optical path Lp1 by passing through the half mirror 5 and a second light Lh2 that travels along the second optical path Lp2 by being reflected by the half mirror 5. The first light Lh1 traveling along the first optical path Lp1, which is a straight - through optical path, enters the fourth polarization combining mirror 7B. The second light Lh2 traveling along the second optical path Lp2, which is a detour optical path, is reflected by the mirror 9, bends the optical path by about 90°, and travels toward the third dichroic mirror 11B.

[0069] The retardation plate 13 is disposed between the mirror 9 and the third dichroic mirror 11B. The second light Lh2 reflected by the mirror 9 has its phase tilted by 90° by passing through the retardation plate 13. For example, the second light Lh2, which was P - polarized before entering the retardation plate 13, is converted to S - polarized light when passing through the retardation plate 13.

[0070] The third dichroic mirror 11B transmits the light emitted from the third light source unit 31 and reflects the light from the mirror 9. The third light source unit 31 and the first light source unit 3A emit light in different wavelength ranges. The third light source unit 31 emits, for example, blue laser light. The third dichroic mirror 11B combines the blue light from the third light source unit 31 and the red second light Lh2 from the mirror 9. The combined light travels from the third dichroic mirror 11B toward the fourth polarization combining mirror 7B.

[0071] The fourth polarization combining mirror 7B transmits the light from the half mirror 5 and reflects the light from the third dichroic mirror 11B, thereby combining the red first light Lh1, the red second light Lh2, and the blue light. The combined light travels toward the fourth dichroic mirror 43.

[0072] The sixth light source unit 39 and the seventh light source unit 41 emit laser lights of the same color with different polarizations. For example, the sixth light source unit 39 emits a green P-polarized laser light, and the seventh light source unit 41 emits a green S-polarized laser light. The solid light source element 3a of the seventh light source unit 41 is arranged in a state rotated by 90° with respect to the solid light source element of the sixth light source unit 39, respectively.

[0073] The third polarization combining mirror 37 combines both lights by transmitting the light of one polarization and reflecting the light of the other polarization of a different type. The third polarization combining mirror 37 combines both green lights, for example, by transmitting the P-polarized green light from the sixth light source unit 39 and reflecting the S-polarized green light from the seventh light source unit 41. The combined green light is emitted toward the fourth dichroic mirror 43.

[0074] The dichroic mirror 43 combines three colors of light by transmitting one color of light and reflecting the other two colors of light. The dichroic mirror 43 reflects, for example, the red light and the blue light incident from the fourth polarization combining mirror 7B and transmits the green light from the third polarization combining mirror 37. Thereby, the combined three colors of light are emitted toward the lens 15.

[0075] [4-2. Effects, etc.] As described above, in the light source device 1C according to the fourth embodiment, since one color of light among the three colors of light is split by the half mirror 5 and the number of light beams increases, speckle can be reduced.

[0076] (Embodiment 5) Hereinafter, Embodiment 5 will be described with reference to FIG. 6.

[0077] [5-1. Configuration] FIG. 6 is a schematic diagram showing the configuration of the light source device 1D in Embodiment 5 of the present disclosure.

[0078] The light source device 1D of Embodiment 5 combines the light source device 1B of Embodiment 3 and the light source device 1C of Embodiment 4, includes one light source device for each color, and is configured to form a detour path for two of the three colors of light to generate combined light. The configuration of the light source device 1D of Embodiment 5 is common to the light source device 1B of Embodiment 3 and the light source device 1C of Embodiment 4 except for this point and the points described below.

[0079] The light source device 1D includes a first light source unit 3, a third light source unit 31, and a fourth light source unit 33. The light source device 1D also includes a half mirror 5, a second polarization combining mirror 7A, a retardation plate 13, a first dichroic mirror 9A, and a second dichroic mirror 11A, and forms a first optical path Lp1 and a second optical path Lp2 for one color of light with these configurations. The light source device 1D further includes a half mirror 5A, mirrors 9 and 11, a retardation plate 13A, and a first polarization combining mirror 7, and forms a first optical path Lp1 and a second optical path Lp2 for another color of light with these configurations.

[0080] Three laser lights having different wavelength regions are emitted from the three light source units of the first light source unit 3, the third light source unit 31, and the fourth light source unit 33. For example, a green P-polarized laser light is emitted from the first light source unit 3, a blue laser light is emitted from the third light source unit 31, and a red P-polarized laser light is emitted from the fourth light source unit 33.

[0081] Similar to Embodiment 3, the green emitted light emitted from the first light source unit 3 is split by the half mirror 5 into a first green light Lh1 and a second green light Lh2, and enters the second polarization combining mirror 7A through the first optical path Lp1 and the second optical path Lp2, respectively. Also, the blue emitted light emitted from the third light source unit 31 also passes through the first dichroic mirror 9A, is reflected by the second dichroic mirror 11A, and enters the second polarization combining mirror 7A.

[0082] Similar to Embodiment 1, the red emitted light emitted from the fourth light source unit 33 is split by the half mirror 5A into a first red light Lh1 and a second red light Lh2, and enters the second polarization combining mirror 7A through the first optical path Lp1 and the second optical path Lp2, respectively. In the second polarization combining mirror 7A, the first light Lh1 and the second light Lh2 in different polarization states are combined and emitted toward the second dichroic mirror 11A in a state where the number of light beams is doubled. In the second dichroic mirror 11A, the second green light Lh2, the blue light, and the red light with the doubled number of light beams are combined.

[0083] In the second polarization combining mirror 7A, the first green light Lh1 and the second light Lh2 in different polarization states are combined, and the number of light beams is doubled. Further, the green light with the doubled number of light beams, the blue light, and the red light with the doubled number of light beams are combined and emitted from the second polarization combining mirror 7A.

[0084] [5-2. Effects, etc.] As described above, the light source device 1D according to Embodiment 5 can double the number of light beams of two of the three colors. Therefore, although it has three light sources, it can obtain the number of light beams obtained from five light sources and can reduce speckle.

[0085] (Embodiment 6) Hereinafter, Embodiment 6 will be described with reference to FIG. 7.

[0086] [6-1. Configuration] FIG. 7 is a schematic diagram showing the configuration of the light source device 1E in Embodiment 6 of the present disclosure.

[0087] The light source device 1E of Embodiment 6 combines the light source device 1B of Embodiment 3 and the light source device 1C of Embodiment 4, includes two two-color light source units each, and forms a detour path for two of the three colors of light to generate combined light. The configuration of the light source device 1E of Embodiment 6 is common to the light source device 1B of Embodiment 3 and the light source device 1C of Embodiment 4 except for this point and the points described below.

[0088] The light source device 1F includes a first light source unit 3, a second light source unit 23, a third light source unit 31, a fourth light source unit 33A, and a fifth light source unit 35A. The fourth light source unit 33A and the fifth light source unit 35A of the light source device 1F respectively correspond to the first light source unit 3A and the second light source unit 23A of Embodiment 4. Further, the light source device 1F includes a half mirror 5, a second polarization combining mirror 7A, a retardation plate 13, a first dichroic mirror 9A, and a second dichroic mirror 11A, and forms a first optical path Lp1 and a second optical path Lp2 for one color of light with these configurations. Also, the light source device 1D includes a half mirror 5A, mirrors 9 and 11, a retardation plate 13A, and a first polarization combining mirror 7, and forms a first optical path Lp1 and a second optical path Lp2 for another color of light with these configurations.

[0089] [6-2. Effects, etc.] As described above, the light source device 1E according to Embodiment 6 can double the number of light beams of two colors out of three colors. Therefore, although it has five light sources, it can obtain the number of light beams obtained from seven light sources, and can reduce speckle.

[0090] (Embodiment 7) Hereinafter, Embodiment 7 will be described with reference to FIG. 8.

[0091] [7-1. Configuration] FIG. 8 is a schematic diagram showing a light source device 1F according to Embodiment 7 of the present disclosure.

[0092] The light source device 1F of Embodiment 6 has a configuration in which a reflection module 45 for further increasing the number of light beams is further provided in the light source device 1 of Embodiment 1. The configuration of the light source device 1F of Embodiment 6 is common to the light source device 1 of Embodiment 1 except for this point and the points described below.

[0093] The light source device 1F includes a reflection module 45 in addition to the light source device 1. The reflection module 45 is disposed on the optical path so that the light emitted from the first polarization combining mirror 7 is incident thereon. The reflection module 45 includes a first reflection mirror 47 that reflects a part of the incident light and transmits the rest, and a second reflection mirror 49 that totally reflects a part of the incident light. The second reflection mirror 49 is disposed behind the first reflection mirror 47 in parallel with the first reflection mirror 47. The light transmitted through the first reflection mirror 47 is totally reflected by the second reflection mirror 49.

[0094] As shown in FIG. 9, the first reflection mirror 47 may employ a mirror coated with a half mirror. The distance d between the first reflection mirror 47 and the second reflection mirror 49 is adjusted so that the incident light beam becomes twice as dense. Further, instead of the mirror coated with a half mirror, the first reflection mirror 47 may employ a slit mirror in which strip-shaped mirrors are arranged at intervals.

[0095] Also, as shown in FIG. 10, the first reflection mirror 47 may employ a mirror having, for example, a 30% reflection coating formed on the incident surface of the combined light. The distance d between the first reflection mirror 47 and the second reflection mirror 49 is adjusted so that the incident light beam becomes three times or more.

[0096] Note that the reflection module 45 can be combined not only with the light source device 1 of the first embodiment but also with the light source devices 1A to 1F of the second to sixth embodiments, respectively.

[0097] [7-2. Effects, etc.] As described above, the light source device 1F according to the sixth embodiment can further increase the number of light beams of the light synthesized by traveling through the straight-ahead optical path and the detour optical path, respectively, by the reflection module 45, so that the speckle can be further reduced.

[0098] (Embodiment 8) Hereinafter, Embodiment 8 will be described with reference to FIG. 11.

[0099] FIG. 11 is a schematic diagram showing the configuration of the projection type image display device according to Embodiment 8 of the present disclosure.

[0100] The projection type image display device 100 according to Embodiment 8 includes, for example, the light source device 1B according to Embodiment 2, a light guide unit 140 that guides the light incident from the light source device 1B to the light modulation device 150, a light modulation device 150 that modulates the incident light based on an external signal, and a projection lens unit 180 that enlarges and projects the light modulated by the light modulation device 150. Note that the projection type image display device 100 may use any one of the light source devices 1C to 1G instead of the light source device 1B. The projection type image display device 100 is a so-called DLP (Digital Light Processing: registered trademark) method.

[0101] The light emitted from the light source device 1B enters the light guide unit 140. The light guide unit 140 includes a rod integrator 141, a lens 143, a mirror 144, and a lens 145. The three-color light emitted from the diffusion plate 21 enters the rod integrator 141 and becomes white light, and then enters the light modulation device 150 through the lens 143, the mirror 144, and the lens 145.

[0102] The light modulation device 150 includes a light guide prism 149, prisms 151a, 151b, 151c, and light modulation elements 152, 153, 154. The light guide prism 149 guides the light from the lens 145 to the prism 151a. The prism 151a has a film 151d having a function of a dichroic mirror that separates the incident white light into three colors of blue, green, and red, and also synthesizes the light of each of the three colors reflected by the light modulation elements 152, 153, 154 and emits it as image light to the projection lens unit 180.

[0103] The film 151d separates the incident white light into, for example, red light, green light, and blue light. Since white light is generated using three-color laser light, there is no light loss even when the light is separated into light in a relatively narrow wavelength range as compared with the case where white light is generated using a rotating phosphor.

[0104] The light modulation elements 152, 153, and 154 are, for example, digital micromirror devices (DMDs). The red light separated by the prism 151 enters the light modulation element 152, the blue light enters the light modulation element 153, and the green light enters the light modulation element 154. When these lights are reflected by the light modulation elements 152, 153, and 154, they are modulated based on an external signal. The modulated light of each color is recombined by the prism 151 and emitted.

[0105] The projection lens unit 180 magnifies the image light emitted from the light modulation device 150 and projects it, for example, onto a screen.

[0106] (Other embodiments) As described above, the above embodiment has been described as an example of the technology disclosed in this application. However, the technology in this disclosure is not limited to this, and can be applied to embodiments in which modifications, substitutions, additions, omissions, etc. are made. In addition, it is also possible to combine the components described in the above embodiment to create a new embodiment.

[0107] As described above, the embodiment has been described as an example of the technology in the present disclosure. For this purpose, the attached drawings and detailed description have been provided. Therefore, among the components described in the attached drawings and detailed description, not only components essential for solving the problem but also components that are not essential for solving the problem in order to exemplify the above technology may be included. Therefore, the fact that these non-essential components are described in the attached drawings or detailed description should not be used to immediately determine that these non-essential components are essential.

[0108] In addition, since the above-described embodiments are for exemplifying the technology in the present disclosure, various changes, replacements, additions, omissions, etc. can be made within the scope of the claims or their equivalents. For example, as shown in FIG. 12, the light source device 1 according to Embodiment 1 may further include an actuator 22 that vibrates the diffusion plate 17. Thereby, speckle can be further reduced.

[0109] (Summary of Embodiment) (1) The light source device of the present disclosure includes a first light source unit having a plurality of solid light source elements arranged in a two-dimensional direction at a predetermined pitch and emitting light of first linearly polarized light, a half mirror that reflects and transmits the emitted light from the first light source unit and separates it into a first light traveling in a first optical path and a second light traveling in a second optical path, a polarization synthesis mirror that transmits and reflects according to the type of polarization and synthesizes the first light and the second light, an optical path changing element disposed on the second optical path that reflects the second light and guides it to the polarization synthesis mirror, and a retardation plate disposed on the second optical path that converts the second light into second linearly polarized light inclined with respect to the first linearly polarized light. The optical path changing element is arranged such that the point image of the first light and the point image of the second light in the polarization synthesis mirror are alternately arranged in the minor axis direction of the point image.

[0110] With these configurations, the half mirror divides the emitted light, and on the first polarization synthesis mirror, the point images of the light beams of the first light traveling in the first optical path and the point images of the light beams of the second light traveling in the second optical path are alternately arranged, thereby realizing light source multiplexing. As a result, a light source device with reduced speckle can be provided.

[0111] (2) In the light source device of (1), a second light source unit is provided, which has a plurality of solid light source elements arranged in a two-dimensional direction at a predetermined pitch and emitting light of first linearly polarized light. The half mirror reflects and transmits the emitted light from the second light source unit, and separates it into a third light traveling in a first optical path and a fourth light traveling in a second optical path. The polarization combining mirror combines the first light, the second light, the third light, and the fourth light, and the optical path changing element reflects the fourth light and guides it to the polarization combining mirror. The retardation plate converts the fourth light into a second linearly polarized light inclined with respect to the first linearly polarized light. The first light source unit and the second light source unit are arranged such that the point images of the emitted light from the first light source unit and the point images of the emitted light from the second light source unit in the half mirror are alternately arranged in the major axis direction of the point image. The optical path changing element is arranged such that the point image of the third light and the point image of the fourth light in the polarization combining mirror are alternately arranged in the minor axis direction of the point image.

[0112] With these configurations, the half mirror divides the emitted light from the first light source unit and the second light source unit respectively, and on the polarization combining mirror, the point images of the light beams of the first light and the third light that have traveled in the first optical path and the point images of the light beams of the second light and the fourth light that have traveled in the second optical path are alternately arranged, so that source multiplexing can be realized. As a result, a light source device with reduced speckle can be provided.

[0113] (3) In the light source device of (1) or (2), a diffusion plate through which the light combined by the polarization combining mirror passes is provided.

[0114] (4) In the light source device of (3), the diffusion plate is vibratable.

[0115] (5) In the light source device of (1) to (4), it has a slit mirror into which the combined light is incident, and a reflection mirror arranged in parallel with the slit mirror behind the slit mirror.

[0116] (6) In the light source device according to (1) to (4), a reflection film that reflects a partial ratio of the synthesized light includes a first reflection mirror formed on the incident surface of the synthesized light, and a second reflection mirror disposed in parallel with the first reflection mirror behind the first reflection mirror.

[0117] (7) In the light source device according to (1) to (6), it includes an optical modulation element that modulates the light incident from the light source device based on an external signal, and a projection lens unit that enlarges and projects the light modulated by the optical modulation element.

Industrial Applicability

[0118] The present disclosure is applicable to projection type image display devices such as light source devices or projection type image display devices.

Explanation of Signs

[0119] 1, 1A, 1B, 1C, 1D, 1E, 1F Light source device 3, 3A First light source unit 3a Solid light source element 5, 5A Half mirror 7 First polarization synthesis mirror 7A Second polarization synthesis mirror 7B Fourth polarization synthesis mirror 9 Mirror 9A First dichroic mirror 11 Mirror 11A Second dichroic mirror 11B Third dichroic mirror 13, 13A Phase difference plate 15 Lens 17 Diffusion plate 19 Lens 21 Diffusion plate 22 Actuator 23 Second light source unit 31 Third light source unit 33, 33A Fourth light source unit 35, 35A Fifth light source unit 37 Third polarization synthesis mirror 39 Sixth light source unit 41 Seventh light source unit 43 Fourth dichroic mirror 45 Reflection module 47 First reflection mirror 49 Second reflection mirror 100 Projection type image display device 140 Light guide unit 141 Rod integrator 143 Lens 144 Mirror 145 Lens 150 Optical modulation device 151a, 151b, 151c Prism 151d Film 152 Optical modulation element 153 Optical modulation element 154 Optical modulation element 180 Projection lens unit Lt1 First emitted light Lt2 Second emitted light Lh1 First light Lh2 Second light Lh3 Third light Lh4 Fourth light Lm1, Lm2 Combined light Lp1 First optical path Lp2 Second optical path

Claims

1. A first light source unit having a plurality of solid light source elements arranged two-dimensionally at a predetermined pitch and emitting light of first linearly polarized light; A half mirror that reflects and transmits the emitted light from the first light source unit and separates it into a first light traveling in a first optical path and a second light traveling in a second optical path; A polarization synthesis mirror that transmits and reflects light according to the type of polarization and synthesizes the first light and the second light; An optical path changing element disposed on the second optical path, reflecting the second light and guiding it to the polarization synthesis mirror; A retardation plate disposed on the second optical path, converting the second light into a second linearly polarized light inclined with respect to the first linearly polarized light, comprising: The optical path changing element is arranged such that the point image of the first light and the point image of the second light in the polarization synthesis mirror are alternately arranged in the minor axis direction of the point image of the first light and the point image of the second light; A light source device.

2. Further comprising a second light source unit having a plurality of solid light source elements arranged two-dimensionally at a predetermined pitch and emitting light of first linearly polarized light; The half mirror reflects and transmits the emitted light from the second light source unit and separates it into a third light traveling in the first optical path and a fourth light traveling in the second optical path; The polarization synthesis mirror synthesizes the first light, the second light, the third light, and the fourth light; The optical path changing element reflects the fourth light and guides it to the polarization synthesis mirror; The retardation plate converts the fourth light into the second linearly polarized light; The first light source unit and the second light source unit are arranged such that the point image of the emitted light from the first light source unit and the point image of the emitted light from the second light source unit in the half mirror are alternately arranged in the major axis direction of the point image of the emitted light from the first light source unit and the point image of the emitted light from the second light source unit; The optical path changing element is arranged such that the point image of the third light and the point image of the fourth light in the polarization synthesis mirror are alternately arranged in the minor axis direction of the point image of the third light and the point image of the fourth light; The light source device according to claim 1.

3. Further comprising a diffusion plate through which the light synthesized in the polarization synthesis mirror passes; The light source device according to claim 1 or 2.

4. The diffusion plate is vibratable; The light source device according to claim 3.

5. Further comprising an actuator for vibrating the diffusion plate; The light source device according to claim 3.

6. A slit mirror onto which the light synthesized by the polarization combining mirror is incident, and a reflection mirror arranged in parallel with the slit mirror behind the slit mirror, further comprising: The light source device according to any one of claims 1 to 5.

7. A first reflection mirror having a reflection film that reflects a part of the light synthesized by the polarization combining mirror on the incident surface of the synthesized light, and a second reflection mirror arranged in parallel with the first reflection mirror behind the first reflection mirror, further comprising: The light source device according to any one of claims 1 to 5.

8. The optical path changing element includes a first mirror that reflects the second light reflected by the half mirror, and a second mirror that reflects the second light reflected by the first mirror and guides it to the polarization combining mirror. The light source device according to any one of claims 1 to 7.

9. further comprising a third light source unit that emits light of a color different from the color of the light emitted by the first light source unit, wherein the first mirror is a dichroic mirror, and the third light source unit is arranged such that the light emitted by the third light source unit passes through the first mirror and is reflected by the second mirror. The light source device according to claim 8.

10. further comprising a fourth light source unit that emits light of a color different from the color of the light emitted by the first light source unit, wherein the second mirror is a dichroic mirror, and the fourth light source unit is arranged such that the light emitted by the fourth light source unit passes through the second mirror and is guided to the polarization combining mirror. The light source device according to claim 8 or 9.

11. The light source device according to any one of claims 1 to 10, an optical modulation element that modulates the light incident from the light source device based on an external signal, and a projection lens unit that enlarges and projects the light modulated by the optical modulation element. A projection type image display device comprising:

Images