Light source device and projection-type video display device

Abstract

This light source device comprises: a first light source that outputs first light, which is laser light of a first color; a second light source that outputs second light that is laser light of a second color and has an etendue smaller than the etendue of the first light; a first diffusing element on which the second light from the second light source is incident; and a first combining element that combines the first light from the first light source with the second light from the second light source that has been diffused by the diffusing element.

Description

Light source device and projection-type image display device

[0001] The present invention relates to a light source device and a projection-type image display device.

[0002] Conventionally, in a light source device used for a projection-type image display device, white light is formed using blue light and red light generated by using a semiconductor laser element.

[0003] In the projection-type image display device of Patent Document 1, red laser light, blue laser light, and green laser light are generated, and the respective laser lights are combined to form combined light. When laser light is projected onto a screen, it generates speckle noise which are bright spots, so it is diffused using a diffusion plate or the like. If diffusion is insufficient, speckle noise will remain; on the other hand, if diffusion is excessive, a decrease in optical efficiency will occur.

[0004] Japanese Patent Application Laid-Open No.2017-142904

[0005] However, when the beam diameter, spread angle, and etendue of the laser light of each color are not uniform, appropriate diffusion of the laser light of each color cannot be performed, resulting in the occurrence of speckle noise and a decrease in optical efficiency.

[0006] The present disclosure aims to provide a light source device and a projection-type image display device that suppress a decrease in optical efficiency and speckle noise.

[0007] The light source device according to the present disclosure includes: a first light source that outputs first light which is laser light of a first color; a second light source that has an etendue smaller than that of the first light and outputs second light which is laser light of a second color; a first diffusion element on which the second light from the second light source is incident; and a first combining element that combines the first light from the first light source and the second light from the second light diffused by the diffusion element.

[0008] The light source device according to the present disclosure includes: a red light source that outputs first light which is red laser light; a blue light source that outputs second light which is blue laser light; a first diffusion element on which the second light from the blue light source is incident; and a first combining element that combines the first light and the second light diffused by the first diffusion element.

[0009] The projection-type image display device according to this disclosure comprises the above-described light source device, an optical modulation unit that generates image light using light emitted from the light source device, and a projection optical system that projects the image light.

[0010] This disclosure provides a light source device and a projection-type image display device that suppress the reduction in optical efficiency and speckle noise.

[0011] Overall diagram showing the configuration of a projection-type image display device according to Embodiment 1. Explanatory diagram showing the angular distribution of light beams in a cross section perpendicular to the optical axis of blue and green light. Explanatory diagram showing the angular distribution of light beams in a cross section perpendicular to the optical axis of red light. Explanatory diagram showing the angular distribution of the red light beam and the angular distribution of the blue and green light beams after passing through a diffusion element. Explanatory diagram showing the angular distribution of the red light beam and the angular distribution of blue and green light after passing through a diffusion element with different diffusion angles in the X direction and Y direction. Explanatory diagram showing a diffusion element with different diffusion angle distributions in the X direction and Y direction. Overall diagram showing the configuration of a projection-type image display device according to a modified example of Embodiment 1. Explanatory diagram showing the diffusion angle distribution of a diffusion element for red light and the diffusion angle distribution of diffusion elements for blue and green light. Explanatory diagram showing the angular distribution of the red light beam after passing through a diffusion element and the angular distribution of the blue and green light beams after passing through a diffusion element. Overall diagram showing the configuration of a projection-type image display device according to Embodiment 2.

[0012] The embodiments will be described in detail below, with reference to the drawings as appropriate. However, unnecessary details may be omitted. For example, detailed explanations of already well-known matters or redundant explanations of substantially identical configurations may be omitted. This is to avoid the following explanation becoming unnecessarily verbose and to facilitate understanding for those skilled in the art. The accompanying drawings and the following explanation are provided to enable those skilled in the art to fully understand this disclosure and are not intended to limit the subject matter described in the claims.

[0013] (Embodiment 1) [1-1. Configuration of Projection-Type Image Display Device] The projection-type image display device 1 of Embodiment 1 will be described with reference to Figure 1. Figure 1 is an overall diagram showing the configuration of the projection-type image display device 1 according to Embodiment 1. Note that "image" includes still images and moving images.

[0014] As shown in Figure 1, the projection-type image display device 1 comprises a light source device 10, a relay optical system 20, a light modulation unit 30, and a projection lens unit 40 as a projection optical system. The light source device 10 emits a first laser beam that is red, a second laser beam that is blue (different from red), and a third laser beam that is green (different from red and blue). The relay optical system 20 homogenizes the white light, which is a composite of the blue, green, and red laser beams from the light source device 10, and propagates it to the light modulation unit 30. The light modulation unit 30 modulates the light from the relay optical system 20 according to an image signal input from the outside to generate image light. The projection lens unit 40 magnifies and projects the image light emitted from the light modulation unit 30 onto the projection target.

[0015] The light source device 10 includes a red laser light source 11 that emits red laser light (hereinafter referred to as red light), a blue laser light source 12 that emits blue laser light (hereinafter referred to as blue light), and a green laser light source 13 that emits green laser light (hereinafter referred to as green light). The red laser light source 11 has a plurality of red laser diodes, the blue laser light source 12 has a plurality of blue laser diodes, and the green laser light source 13 has a plurality of green laser diodes.

[0016] The relay optical system 20 includes a condensing lens 121, a diffuser plate 122, a rod integrator 123, a lens 124, a mirror 125, and a field lens 126.

[0017] The focusing lens 121 focuses the white light incident from the light source device 10 onto the rod integrator 123. A diffuser plate 122 is placed between the focusing lens 121 and the rod integrator 123. The diffuser plate 122 homogenizes the white light as it passes through it.

[0018] The rod integrator 123 is a solid rod made of a transparent material such as glass. The rod integrator 123 homogenizes the light intensity distribution by reflecting the incident white light multiple times inside. The rod integrator 123 may also be a hollow rod whose inner wall is made of a mirror surface. The homogenized white light passes through the lens 124, is reflected by the mirror 125, passes through the field lens 126, and then enters the internal total internal reflection prism (TIR prism) 131 as illumination light.

[0019] The optical modulation unit 30 includes an internal total reflection prism 131 and an optical modulation element 134.

[0020] The internal total internal reflection prism 131 has a first prism 132 and a second prism 133, with a small gap (air gap) maintained between the first prism 132 and the second prism 133. Light incident on the internal total internal reflection prism 131 enters the minute gap at an angle greater than the total internal reflection angle, and is reflected by the first prism 132, changing the direction of light propagation before being incident on the light modulation element 134.

[0021] The optical modulation element 134 changes the direction of light propagation by changing the orientation of a minute mirror in response to a signal from a video circuit (not shown) and emits the light. The optical modulation element 134 is, for example, a digital micromirror device (DMD). The light whose propagation direction has been changed in response to the video signal by the optical modulation element 134 enters the internal total internal reflection prism 131, and by entering the minute gap of the internal total internal reflection prism 131 at an angle less than or equal to the total internal reflection angle, it passes through and enters the projection lens unit 40, and is projected onto a screen (not shown).

[0022] [1-2. Configuration of the Light Source Device] Next, the light source device 10 will be described in detail. The number of red laser diodes 14 in the red laser light source 11, the number of blue laser diodes 15 in the blue laser light source 12, and the number of green laser diodes 16 in the green laser light source 13 are all different. However, as shown in Figure 1, the number of blue laser diodes 15 in the blue laser light source 12 and the number of green laser diodes 16 in the green laser light source 13 may be the same.

[0023] Therefore, the total luminous beam diameter of the red light output from the red laser light source 11 is different from the total luminous beam diameter of the blue light output from the blue laser light source 12 and the total luminous beam diameter of the green light output from the green laser light source 13. Also, the divergence angle of the red light output from the red laser light source 11 is different from the divergence angle of the blue light output from the blue laser light source 12 and the divergence angle of the green light output from the green laser light source 13.

[0024] When using laser diodes currently available on the market, the divergence angle of red light is greater than that of blue and green light. Furthermore, in the light source device 10, in order to make the brightness of red light the same as that of blue and green light, the number of red laser diodes 14 is greater than the number of blue and green laser diodes 15 and 16. Therefore, the total luminous beam diameter of red light is greater than that of blue and green light. The product of the luminous beam diameter and divergence angle of laser light is called etendue. The etendue of red light is greater than that of blue and green light. In this state where the etendue of laser light differs, when the laser light is diffused, there will be an excess or deficiency of diffusion, resulting in the generation of speckle noise and a decrease in optical efficiency.

[0025] Therefore, by bringing the etendues for blue and green light closer to the etendues for red light, it is possible to suppress the decrease in optical efficiency and the generation of speckle noise.

[0026] The light source device 10 further includes a mirror 51, a combining element 52, a diffusion element 53, a light beam diameter conversion unit 54, and a combining element 55.

[0027] The mirror 51 totally reflects the green light output from the green laser light source 13 toward the composite element 52.

[0028] The combining element 52 combines the blue light output from the blue laser light source 12 with the green light reflected by the mirror 51. The combining element 52 is, for example, a dichroic mirror with a coating on its surface that transmits blue light and reflects green light.

[0029] The diffusion element 53 expands the divergence angle of the combined blue and green light. The diffusion element 53 is, for example, a diffuser plate. The diffusion angle of the diffuser plate is set so that the divergence angles of the blue and green light approach the divergence angle of the red light. The diffusion angle can be adjusted by the uneven surface shape of the diffuser plate. In the case of a diffuser plate with a small lens array, the diffusion angle can be adjusted by adjusting the curvature of the lenses.

[0030] The combined light of blue and green light, whose divergence angle has been widened by the diffusion element 53, enters the combining element 55.

[0031] Next, the path of the red light will be described. The light beam diameter conversion unit 54 converts the overall light beam diameter of the red light output from the red laser light source 11. The light beam diameter conversion unit 54 includes a convex lens 61, a mirror 62, and a concave lens 63.

[0032] The red light emitted from the red laser light source 11 passes through the convex lens 61 and undergoes total internal reflection towards the concave lens 63 by the mirror 62. As the red light emitted from the red laser light source 11 passes through the convex lens 61 and the concave lens 63, its beam diameter is reduced, and it is further shaped into parallel light before being incident on the composite element 55. The curvature of the convex lens 61 and the distance between the convex lens 61 and the concave lens 63 are set so that the total beam diameter of the red light emitted from the red laser light source 11 approaches the total beam diameters of the blue and green light, respectively.

[0033] The combining element 55 combines the incident red light with the combined blue and green light to form white light Lw, which is then emitted toward the condensing lens 121 of the relay optical system 20. The combining element 55 is, for example, a dichroic mirror, and its surface is coated to reflect the combined blue and green light and transmit the red light.

[0034] Next, the angular distribution of the luminous beam of each color of light will be explained with reference to Figures 2 to 4. Figure 2 is an explanatory diagram showing the angular distribution of the luminous beam in a cross section perpendicular to the optical axis of blue and green light. Figure 3 is an explanatory diagram showing the angular distribution of the luminous beam in a cross section perpendicular to the optical axis of red light. Figure 4 is an explanatory diagram showing the angular distribution of the luminous beam of red light and the angular distribution of the luminous beams of blue and green light after passing through the diffusion element 53. In each figure, the XY plane is a plane perpendicular to the optical axis of each color of light. The X axis and Y axis are orthogonal to each other.

[0035] As shown in Figures 2 and 3, the angular distribution Bd1 of the blue light output from the blue laser light source 12 and the angular distribution Rd1 of the red light output from the red laser light source 11 are significantly different. However, the angular distribution Bd1 of the blue light output from the blue laser light source 12 and the angular distribution Gd1 of the green light output from the green laser light source 13 are almost the same size.

[0036] To achieve both optical efficiency and speckle noise suppression, it is necessary to increase the degree of diffusion for light with a small divergence angle and decrease the degree of diffusion for light with a small divergence angle, thereby bringing the divergence angles of each type of light closer together. Therefore, by increasing the divergence angles of blue and green light using the diffusion element 53, as shown in Figure 4, the angular distribution Bd2 of blue light and the angular distribution Gd2 of green light after passing through the diffusion element 53 are expanded, and the angular distribution Rd1 of red light and the divergence angle can be brought closer together. Furthermore, the rod integrator 123 of the subsequent relay optical system 20 homogenizes the illuminance distribution of red, blue, and green light.

[0037] In the example shown in Figure 4, the diffusion angle in the X direction and the diffusion angle in the Y direction of the diffusion element 53 were the same, but the diffusion element 53 may have different diffusion angles in the X direction and the Y direction. For example, as shown in Figure 6, a diffusion element 53a with different diffusion angle distributions in the X direction and the Y direction may be used. For example, since the diffusion angle in the X direction of the diffusion element 53a is larger than the diffusion angle in the Y direction, the angular distribution Bd3 of blue light and the angular distribution Gd3 of green light transmitted through the diffusion element 53a can be made closer to the angular distribution Bd1 of red light, as shown in Figure 5.

[0038] Next, a modified example of Embodiment 1 will be described with reference to Figure 7. In the projection-type image display device 1A of Modification 7 of Embodiment 1, the light source device 10A further includes a diffusion element 64 in the configuration of the projection-type image display device 1.

[0039] The diffusion element 64 expands the divergence angle of the red light output from the red laser light source 11. The diffusion element 64 is, for example, a diffusion plate. The diffusion angle can be adjusted by the uneven surface shape of the diffusion plate. In the case of a diffusion plate with a small lens array, the diffusion angle can be adjusted by adjusting the curvature of the lenses.

[0040] In the modified example, the diffusion angle of the diffusion element 53 is set so that the diffusion angles of the blue and green light approach the diffusion angle of the diffused red light. That is, the diffusion angle of the diffusion element 53 is larger than the diffusion angle of the diffusion element 64.

[0041] Refer to Figure 8. Figure 8 is an explanatory diagram showing the diffusion angle distribution of the red light diffusion element 64 and the diffusion angle distribution of the blue and green light diffusion elements 53. The diffusion angle distribution of the blue and green light diffusion elements 53 has a wider area than the diffusion angle distribution of the red light diffusion element 64, so the diffusion angle of blue and green light is larger than that of red light.

[0042] Refer to Figure 9. Figure 9 is an explanatory diagram showing the angular distribution of the red light beam after passing through the diffusion element 64, and the angular distribution of the blue and green light beams after passing through the diffusion element 53. For red light as well, the angular distribution Rd2 of the red light after passing through the diffusion element 64 is expanded, but since the diffusion angle of the diffusion element 53 for blue and green light is larger than that of the diffusion element 64 for red light, the angular distributions Bd2 and Gd2 of the blue and green light can be brought closer to the angular distribution Rd2 of the red light.

[0043] [1-3. Effects, etc.] As described above, in Embodiment 1, the light source device 10 includes a red laser light source 11 that outputs red light, which is red laser light; a blue laser light source 12 that outputs blue light, which is blue laser light; a diffusion element 53 into which the blue light from the blue laser light source 12 is incident; and a combining element 55 that combines the red light from the red laser light source 11 and the blue light from the blue laser light source 12 that has been diffused by the diffusion element 53.

[0044] For blue light having both a small beam diameter and a small divergence angle, the diffusion element 53 enlarges the divergence angle of the blue light, and the blue light with the enlarged divergence angle is combined with red light having both a larger beam diameter and a larger divergence angle than the blue light, thereby suppressing a decrease in optical efficiency and the occurrence of speckle noise.

[0045] Further, the light source device 10 includes a green laser light source 13 that outputs green light which is green laser light. The green light from the green laser light source 13 is incident on the diffusion element 53, and the combining element 55 combines the red light with the blue light and the green light diffused by the diffusion element 53.

[0046] Even for green light having both a small beam diameter and a small divergence angle, the diffusion element 53 enlarges the divergence angle of the green light, and the blue light and green light with enlarged divergence angles are combined with red light having both a larger beam diameter and a larger divergence angle than the blue light and the green light, whereby the etendue of each color light included in the combined white light can be made close to each other, and a decrease in optical efficiency and the occurrence of speckle noise can be suppressed.

[0047] Further, the light source device 10 includes a combining element 52 that combines the blue light from the blue laser light source 12 and the green light from the green laser light source 13. By forming combined light in which blue light and green light are combined in advance, the diffusion of blue light and green light can be made uniform.

[0048] Further, the light source device 10A includes a diffusion element 64 on which the red light from the red laser light source 11 is incident. The diffusion angle of the diffusion element 53 is larger than the diffusion angle of the diffusion element 64, and the combining element 55 combines the red light diffused by the diffusion element 64 and the blue light diffused by the diffusion element 53.

[0049] For red light, the diffusion element 64 is also used to enlarge the divergence angle, so that the angular distribution of red light approaches that of blue light, and appropriate diffusion can be achieved. This can suppress a decrease in optical efficiency and the occurrence of speckle noise.

[0050] Further, the projection type image display apparatus 1 includes the light source device 10, a light modulation unit 30 that generates image light using light emitted from the light source device 10, and a projection lens unit 40 that projects the image light.

[0051] The light of each color emitted from the light source device 10 is appropriately diffused, and since the image light is generated using appropriately diffused light, it is possible to suppress speckle noise in the image light projected from the projection-type image display device 1 while preventing a decrease in efficiency due to diffusion.

[0052] (Embodiment 2) Next, with reference to Figure 10, the projection-type image display device 1B of Embodiment 2 will be described. This is an overall diagram showing the configuration of the projection-type image display device according to Embodiment 2.

[0053] The projection-type image display device 1 according to Embodiment 1 was equipped with a red laser light source 11 that outputs red light, a blue laser light source 12 that outputs blue light, and a green laser light source 13 that outputs green light. However, the projection-type image display device 1B according to Embodiment 2 is equipped only with a red laser light source 11 that outputs red light and a blue laser light source 12 that outputs blue light. Furthermore, the projection-type image display device 1 of Embodiment 1 had a 1-chip digital micromirror device, while the projection-type image display device 1B according to Embodiment 2 has a 3-chip digital micromirror device. Apart from these points and the points described below, the projection-type image display device 1 according to Embodiment 1 and the projection-type image display device 1B according to Embodiment 2 have common configurations.

[0054] The light source device 10B of Embodiment 2 does not include the light beam diameter conversion unit 54 of the light source device 10 of Embodiment 1. The light source device 10B includes a red laser light source 11B, blue laser light sources 12 and 12B, a diffusion element 53, a combining element 55B, a convex lens 71, a diffusion plate 72, a convex lens 73, a mirror 74, a dichroic mirror 75, a condenser lens 76, a phosphor wheel 77, and a diffusion element 78.

[0055] The light source device 10B of the second embodiment includes two blue laser light sources 12 and 12B. The blue light output from the blue laser light source 12 has its divergence angle expanded by the diffusion element 53. The expanded blue light is incident on the combining element 55B. The red light output from the red laser light source 11B is incident on the combining element 55B.

[0056] The composite element 55B is, for example, a dichroic mirror with a coating on its surface that transmits blue light and reflects red light. Blue light and red light are combined in the composite element 55B, the combined light is focused onto the diffuser plate 72 by the convex lens 71, and the combined light of the red and blue light that has passed through the diffuser plate 72 is formed into parallel light by the convex lens 73.

[0057] The combined light that passes through the convex lens 73 is totally reflected by the mirror 74 and incident on the dichroic mirror 75.

[0058] The Dichroic Mirror 75 has a coating on its surface that transmits blue and red light and reflects yellow light.

[0059] The blue light emitted from the blue laser light source 12B has its divergence angle expanded by a diffusion element 78 having the same configuration as the diffusion element 53. The blue light with the expanded divergence angle passes through the dichroic mirror 75 and is focused onto the phosphor wheel 77 by the condenser lens 76.

[0060] The phosphor wheel 77 converts the incident blue light into yellow light and reflects it. The yellow light converted by the phosphor wheel 77 is formed into parallel light by the condenser lens 76, reflected by the dichroic mirror 75, and further combined with the blue and red light to form white light. The white light is emitted from the dichroic mirror 75 to the relay optical system 20B.

[0061] The relay optical system 20B has a configuration in which the diffuser plate 122 is omitted from the relay optical system 20 of Embodiment 1. The white light emitted from the light source device 10B is made uniform and emitted to the internal total internal reflection prism 131 of the light modulation unit 30B.

[0062] The light modulation unit 30B comprises an internal total internal reflection prism 131, a color prism 135, and light modulation elements 136, 137, and 138. The color prism 135 separates the white light incident from the internal total internal reflection prism 131 into three colors: blue, green, and red. It also combines the three colors of light from the light modulation elements 136, 137, and 138 and emits the resulting image light through the internal total internal reflection prism 131 to the projection lens unit 180.

[0063] The optical modulators 136, 137, and 138 are, for example, digital micromirror devices. The red light separated by the color prism 135 enters optical modulator 136, the blue light enters optical modulator 137, and the green light enters optical modulator 138. These lights are modulated based on an external signal as they are reflected by their respective optical modulators 136, 137, and 138. The modulated light of each color is then combined again by the color prism 135 and emitted.

[0064] In the light source device 10B of Embodiment 2, similar to Embodiment 1, the diffusion element 53 expands the divergence angle of blue light, which has a small divergence angle, and the expanded blue light is combined with red light, which has a larger divergence angle than blue light. This brings the etendue of the combined blue light and red light closer together, thereby suppressing a decrease in optical efficiency and the generation of speckle noise.

[0065] (Other Embodiments) In the embodiments described above, digital micromirror devices were used as the optical modulation elements 134, 136, 137, and 138, but the invention is not limited to these. For example, a liquid crystal panel may be used as the optical modulation element.

[0066] As described above, embodiments have been explained as examples of the technology in this disclosure. For this purpose, attached drawings and a detailed description have been provided. Therefore, among the components described in the attached drawings and detailed description, there may be not only components that are essential for solving the problem, but also components that are not essential for solving the problem, in order to illustrate the above technology. Therefore, the mere fact that these non-essential components are described in the attached drawings and detailed description should not be immediately assumed to mean that these non-essential components are essential.

[0067] (Outline of Embodiments) (1) The light source device of the present disclosure comprises: a first light source that outputs first light which is laser light of a first color; a second light source that has an etendue smaller than the etendue of the first light and outputs second light which is laser light of a second color; a first diffusion element into which the second light from the second light source is incident; and a first combining element that combines the first light from the first light source and the second light from the second light source that has been diffused by the diffusion element.

[0068] By using the first diffusing element to expand the divergence angle of the second light, which has a small etendue, the etendue of the second light is increased. By combining this second light with the first light, the etendues of the combined first and second lights become equal, thereby suppressing a decrease in optical efficiency and the generation of speckle noise.

[0069] (2) The light source device of (1) includes a third light source that has an etendue smaller than that of the first light and outputs a third light which is a laser light of a third color. The third light from the third light source is incident on the diffusion element, and the first combining element combines the first light with the second and third light diffused by the diffusion element.

[0070] (3) The light source device of (2) includes a second combining element that combines the second light from the second light source and the third light from the third light source.

[0071] (4) Any one of the light source devices from (1) to (3) includes a second diffusion element into which first light from the first light source is incident. The diffusion angle of the first diffusion element is greater than the diffusion angle of the second diffusion element, and the first combining element combines the first light diffused by the second diffusion element with the second light diffused by the first diffusion element.

[0072] (5) The light source device of the present disclosure comprises a red light source that outputs a first light which is red laser light, a blue light source that outputs a second light which is blue laser light, a first diffusion element into which the second light from the blue light source is incident, and a first combining element that combines the first light and the second light diffused by the first diffusion element.

[0073] By using a first diffusing element to expand the divergence angle of the second blue light, which has both a small beam diameter and divergence angle, and then combining the expanded second light with the first red light, which has both a larger beam diameter and divergence angle, the etendues of the combined first and second lights are aligned, thereby suppressing a decrease in optical efficiency and the generation of speckle noise.

[0074] (6) The light source device of (5) includes a green light source that outputs a third light, which is a green laser light. The third light from the green light source is incident on the diffusion element, and the first combining element combines the first light with the second light and the third light that have been diffused by the diffusion element.

[0075] (7) The light source device of (6) includes a second combining element that combines the second light from the blue light source and the third light from the green light source.

[0076] (8) Any one of the light source devices from (5) to (7) includes a second diffusion element into which the first light from the red light source is incident. The diffusion angle of the first diffusion element is greater than the diffusion angle of the second diffusion element, and the first combining element combines the first light diffused by the second diffusion element with the second light diffused by the first diffusion element.

[0077] (9) The projection-type image display device of the present disclosure comprises one of the light sources (1) to (8), an optical modulation unit that generates image light using light emitted from the light source, and a projection optical system that projects the image light.

[0078] The light of each color emitted from the light source device is appropriately diffused, and since the image light is generated using appropriately diffused light, it is possible to suppress speckle noise in the image light projected from the projection-type image display device 1 while preventing efficiency degradation due to diffusion.

[0079] This disclosure is applicable to a light source device that generates light of different colors, and to a projection-type image display device equipped with a light source device.

[0080] 1, 1A, 1B Projection-type image display device 10, 10A, 10B Light source device 11, 11B Red laser light source 12, 12B Blue laser light source 13 Green laser light source 20, 20B Relay optical system 121 Focusing lens 122 Diffuser plate 123 Rod integrator 124 Lens 125 Mirror 126 Field lens 30, 30B Optical modulation unit 131 Internal total internal reflection prism (TIR prism) 132 First prism 133 Second prism 134 Optical modulation element 135 Color prism 136, 137, 138 Optical modulation element 40 Projection lens unit 51 Mirror 52 Composite element 53, 53a Diffuser element 54 Optical beam diameter conversion unit 55, 55B Composite element 61 Convex lens 62 Mirror 63 Concave lens 64 Diffuser 64b Diffusion angle distribution 71 Convex lens 72 Diffuser plate 73 Convex lens 74 Mirror 75 Dichroic mirror 76 Condenser lens 77 Phosphor wheel Bd1 Angle distribution of blue light beam Gd1 Angle distribution of green light beam Rd1 Angle distribution of red light beam Bd2 Angle distribution of blue light beam after passing through the diffuser Gd2 Angle distribution of green light beam after passing through the diffuser Rd2 Angle distribution of red light beam after passing through the diffuser

Claims

1. A light source device comprising: a first light source that outputs a first light which is a laser beam of a first color; a second light source that has an etendue smaller than the etendue of the first light and outputs a second light which is a laser beam of a second color; a first diffusion element into which the second light from the second light source is incident; and a first combining element that combines the first light from the first light source and the second light from the second light source that has been diffused by the diffusion element.

2. The light source device according to claim 1, comprising a third light source that has an etendue smaller than that of the first light and outputs a third light which is a laser light of a third color, wherein the third light from the third light source is incident on the diffusion element, and the first combining element combines the first light with the second light and the third light diffused by the diffusion element.

3. The light source device according to claim 2, further comprising a second combining element for combining the second light from the second light source and the third light from the third light source.

4. The light source device according to claim 1, further comprising a second diffusion element into which the first light from the first light source is incident, wherein the diffusion angle of the first diffusion element is greater than the diffusion angle of the second diffusion element, and the first combining element combines the first light diffused by the second diffusion element with the second light diffused by the first diffusion element.

5. A light source device comprising: a red light source that outputs a first light which is a red laser beam; a blue light source that outputs a second light which is a blue laser beam; a first diffusion element into which the second light from the blue light source is incident; and a first combining element that combines the first light and the second light diffused by the first diffusion element.

6. The light source device according to claim 5, comprising a green light source that outputs a third light which is a green laser beam, the third light from the green light source is incident on the diffusion element, and the first combining element combines the first light with the second light and the third light which have been diffused by the diffusion element.

7. The light source device according to claim 6, further comprising a second combining element for combining the second light from the blue light source and the third light from the green light source.

8. The light source device according to claim 5, further comprising a second diffusion element into which the first light from the red light source is incident, wherein the diffusion angle of the first diffusion element is greater than the diffusion angle of the second diffusion element, and the first combining element combines the first light diffused by the second diffusion element with the second light diffused by the first diffusion element.

9. A projection-type image display device comprising: a light source device according to any one of claims 1 to 8; a light modulation unit that generates image light using light emitted from the light source device; and a projection optical system that projects the image light.

Images