Light source device, and projection display device

Abstract

To provide a compact light source device with a wide color gamut capable of ensuring uniformity of projected images even when the luminous flux sizes of the red, green, and blue solid-state light sources are different.SOLUTION: The light source device includes: multiple solid-state light sources in red, green, and blue; a polarizing mirror that combines colored light from the solid-state light sources; and a plural beam splitter elements for splitting the light beam from the blue solid-state light source. The beam splitter elements are mirrors that split the blue light into approximately 50% transmission and reflection, and transmit or reflect more than 90% of green and red light. The projection display device uses the light source device.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a projection display device that irradiates an image formed on an image forming element with illumination light and enlarges and projects it onto a screen by a projection lens.

Background Art

[0002] As light sources for projection display devices using image forming elements such as mirror deflection type digital micromirror devices (DMDs) and liquid crystal panels, many light source devices using solid light sources such as semiconductor lasers and light emitting diodes with long lifetimes have been disclosed. Among them, a small-sized and wide color gamut light source device using solid light sources of red, green, and blue has been disclosed (Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Red, green, and blue laser light sources have different light outputs, efficiencies, and wavelengths. Therefore, in a projection display device, in order to obtain a desired brightness and white chromaticity, the required number of red, green, and blue laser light sources is different. In order to ensure high uniformity by eliminating luminance unevenness and color unevenness in the projected image, in the configuration of a conventional light source device, when the beam sizes of red, green, and blue light are different, a beam splitting element that splits the light beam from the laser light source equalizes the beam sizes of each color light. As the beam splitting element, it is configured using a prism array or a mirror array, and after splitting one color light, it is combined with other color light by a dichroic mirror, so the light source device becomes slightly larger. For this reason, even when the beam sizes are different due to the difference in the number of laser elements for each color light, there has been a demand for a light source device that is significantly miniaturized while ensuring high uniformity of the projected image, and a projection display device using such a light source device.

Means for Solving the Problems

[0005] The light source device of the present disclosure includes a plurality of solid light sources of red, green, and blue, a polarization mirror that synthesizes color light from the solid light sources, and a beam splitting element that splits the light beam from the blue solid light source. The beam splitting element is a mirror that splits blue light into transmission and reflection at approximately 50% each, and transmits or reflects green light and red light at approximately 90% or more.

Advantages of the Invention

[0006] According to the present disclosure, a plurality of solid light sources of red, green, and blue, a polarization mirror that synthesizes color light from the solid light sources, and a beam splitting element that splits the light beam from the blue solid light source and synthesizes a plurality of color lights equalize the beam sizes of the laser lights of each color light. In order to synthesize a plurality of color lights, it is possible to configure a wide color gamut light source device that is significantly miniaturized while eliminating a decrease in image uniformity caused by the beam size of each color light. For this reason, a small, wide color gamut, and high brightness projection display device can be realized.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Mode for Carrying Out the Invention

[0008] Hereinafter, embodiments for carrying out the present disclosure will be described with reference to the drawings. (Embodiment 1) FIG. 1 is a configuration diagram of a first light source device 46 showing an embodiment of the present disclosure.

[0009] The first light source device 46 includes a red laser light source 22 composed of a red semiconductor laser substrate 20 on which a plurality of red semiconductor laser elements are arranged and a collimating lens array 21, a red laser light source 26 composed of a red semiconductor laser substrate 24 on which a plurality of red semiconductor laser elements are arranged and a collimating lens array 25, a first polarization mirror 28, a filter 29 that transmits red and reflects green, a quarter-wave plate 30 that is a retardation plate, a second polarization mirror 31, a green laser light source 34 composed of a green semiconductor laser substrate 32 on which a plurality of green semiconductor laser elements are arranged and a collimating lens array 33, a green laser light source 38 composed of a green semiconductor laser substrate 36 on which a plurality of green semiconductor laser elements are arranged and a collimating lens array 37, a blue laser light source 44 composed of a blue semiconductor laser substrate 42 on which a plurality of blue semiconductor laser elements are arranged and a collimating lens array 43, a beam splitting element 40, a dichroic mirror 41 that reflects blue, and heat sinks 23, 27, 35, 39, 45. In the figure, the polarization directions of the light emitted from the laser light sources are shown.

[0010] The red laser light source 22 is composed of a red semiconductor laser substrate 20 on which 24 (6×4) red semiconductor laser elements are two-dimensionally arranged at regular intervals and a collimating lens array 21. The red semiconductor laser substrate 20 emits red-colored light with a wavelength width of 640±8 nm and emits light that becomes P-polarized light with respect to the first polarization mirror 28. The light emitted from the red semiconductor laser substrate 20 is condensed by the corresponding collimating lens array 21 and converted into a parallel light beam. The heat sink 23 cools the red semiconductor laser substrate 20. The red laser light source 26 is composed of a red semiconductor laser substrate 24 on which 24 (6×4) red semiconductor laser elements are two-dimensionally arranged at regular intervals and a collimating lens array 25. The red semiconductor laser substrate 24 emits red-colored light with a wavelength width of 640±8 nm and emits light that becomes S-polarized light with respect to the first polarization mirror 28. The light emitted from the red semiconductor laser substrate 24 is condensed by the corresponding collimating lens array 25 and converted into a parallel light beam. The heat sink 27 cools the red semiconductor laser substrate 24.

[0011] The laser light from the red laser light sources 22 and 26 is incident on the first polarization mirror 28 with P polarization and S polarization respectively. The first polarization mirror 28 is arranged at an incident angle of 45 degrees. The first polarization mirror 28 transmits more than 95% of the red laser light with P polarization and reflects more than 95% of the red laser light with S polarization. The combined light from the plurality of red laser light sources 22 and 26 passes through the red-transmitting and green-reflecting filter 29 and then is incident on the quarter-wave plate 30.

[0012] The green laser light source 34 is composed of a green semiconductor laser substrate 32 in which 24 (6×4) green semiconductor laser elements are two-dimensionally arranged at regular intervals and a collimating lens array 33. The green semiconductor laser substrate 32 emits green-colored light with a wavelength width of 525±8 nm and emits light that becomes S polarization with respect to the second polarization mirror 31. The light emitted from the green semiconductor laser substrate 32 is condensed by the corresponding collimating lens array 33 and converted into parallel light beams respectively. The heat sink 35 is for cooling the green semiconductor laser substrate 32. The green laser light source 38 is composed of a green semiconductor laser substrate 36 in which 24 (6×4) green semiconductor laser elements are two-dimensionally arranged at regular intervals and a collimating lens array 37. The green semiconductor laser substrate 36 emits green-colored light with a wavelength width of 525±8 nm and emits light that becomes S polarization with respect to the second polarization mirror 31. The light emitted from the green semiconductor laser substrate 36 is condensed by the corresponding collimating lens array 37 and converted into parallel light beams respectively. The heat sink 39 is for cooling the green semiconductor laser substrate 36. The laser light from the green laser light sources 34 and 38 is incident on the second polarization mirror 31 with S polarization respectively. The second polarization mirror 31 is arranged at an incident angle of 45 degrees.

[0013] Figure 2 shows the spectral characteristics of the second polarizing mirror 31. The spectral characteristics indicate the spectral transmittance of P-polarized light and S-polarized light at an incident angle of 45 degrees. The spectral characteristics are a designed example in which a 72-layer optical thin film is formed by alternately depositing a high refractive index material such as TiO2 and a low refractive index material such as SiO2 on the glass substrate of the second polarizing mirror. The second polarizing mirror 31 acts as a polarizing beam splitter for green laser light and as a red-transmitting dichroic mirror for red laser light. The second polarizing mirror 31 transmits more than 95% of the P-polarized green laser light, the P-polarized and S-polarized red laser lights, and reflects more than 95% of the S-polarized green laser light.

[0014] The S-polarized light from the green laser light source 38 is reflected by the second polarizing mirror 31 and then enters the quarter-wave plate 30. The quarter-wave plate 30 is a retardation plate with a retardation of 1 / 4 wavelength near the emission center wavelength of the green laser light source 38. When the P-polarization direction in the figure is 0 degrees, the quarter-wave plate 30 has its optical axis arranged at 45 degrees. The quarter-wave plate 30 is a thin-film retardation plate that utilizes birefringence caused by oblique evaporation of a dielectric material. The thin-film retardation plate is composed of an inorganic material and is excellent in durability and reliability like an inorganic optical crystal such as quartz. The green laser light transmitted through the quarter-wave plate 30 and converted into circularly polarized light enters a red-transmitting and green-reflecting filter 29 that forms a reflective film such as a dielectric multilayer film, transmits red laser light, and reflects green laser light. The green laser light reflected by the red-transmitting and green-reflecting filter 29 has its phase reversed and becomes counterclockwise circularly polarized light, passes through the quarter-wave plate 30, and is converted into P-polarized light. The P-polarized light with its polarization direction converted by the quarter-wave plate 30 enters the second polarizing mirror 31 again and is transmitted.

[0015] Also, the S-polarized light from the green laser light source 34 is reflected by the second polarization mirror 31. In this way, the lights of the plurality of green laser light sources 34 and 38 are combined. The P-polarized and S-polarized red lights from the plurality of red laser light sources 22 and 26 each change in phase by a quarter-wave plate 30 to become elliptically polarized light, and after passing through, they transmit through the second polarization mirror 31 at 95% or more. In this way, the light from the plurality of red laser light sources and the light from the plurality of green laser light sources are combined.

[0016] The blue laser light source 44 is composed of a blue semiconductor laser substrate 42 in which 12 (6×2) blue semiconductor laser elements are two-dimensionally arranged at regular intervals and a collimating lens array 43. The blue semiconductor laser substrate 42 emits blue-colored light with a wavelength width of 465±8 nm and emits light that becomes S-polarized light to the beam splitting element 40. Since the blue semiconductor laser has high luminous efficiency and a small optical output required for a desired white light chromaticity compared to red and green semiconductor lasers, it is composed of about a quarter of the number of semiconductor lasers. The light emitted from the blue semiconductor laser substrate 42 is collected by the corresponding collimating lens array 43 and converted into parallel light beams. The heat sink 45 is for cooling the blue semiconductor laser substrate 42. The light from the blue laser light source 44 is incident on the beam splitting element 40. The beam splitting element 40 is arranged at an incident angle of 45 degrees.

[0017] Fig. 3 shows the spectral characteristics of the beam splitting element. The spectral characteristics indicate the spectral transmittance of P-polarized light and S-polarized light at an incident angle of 45 degrees. The spectral characteristics are a designed example in which 57 optical thin films are formed by alternately depositing a high refractive index material such as TiO2 and a low refractive index material such as SiO2 on the glass substrate of the beam splitting element. The beam splitting element 40 splits S-polarized blue light into transmitted light and reflected light at approximately 50% each, and transmits P-polarized and S-polarized green and red light at 90% or more including tolerances. The characteristics of transmitting and reflecting blue light at approximately 50% each are characteristics of transmitting at 40% to 60% and reflecting at 60% to 40% including tolerances. The blue light transmitted through the beam splitting element 40 is incident on the blue-reflecting dichroic mirror 41. The blue-reflecting dichroic mirror 41 is arranged at an incident angle of 45 degrees. The blue-reflecting dichroic mirror 41 reflects blue light at 95% or more and transmits green and red light at 95% or more. The beam splitting element 40 and the blue-reflecting dichroic mirror 41 equalize the beam sizes of light from the red and green laser light sources and the beam size of light from the blue laser light source, and combine them with high efficiency. In this way, light from the blue, green, and red laser light sources is combined in a small size and with high efficiency to emit white light.

[0018] Although the 1 / 4 wavelength plate 30 has been described using a thin film retardation plate, a microstructure retardation plate utilizing birefringence generated by a fine periodic structure smaller than the wavelength of light may also be used.

[0019] Although the green laser light source, the red laser light source, and the blue laser light source have been shown in a configuration in which 48, 48, and 12 semiconductor laser elements are arranged respectively, for higher brightness, a larger number of semiconductor laser elements may be used for each configuration.

[0020] Although the laser light sources 22 and 26 have been described as red laser light sources and the laser light sources 34 and 38 have been described as green laser light sources, by changing the characteristics of the first and second polarizing mirrors, filters, retardation plates, etc., they may be used as green laser light sources and red laser light sources respectively.

[0021] As described above, the light source device of the present disclosure includes a blue, green, and red laser light source, a polarization mirror, a retardation plate and a filter, and a beam splitting element, thereby equalizing the beam sizes of the laser lights of each color light. Therefore, it is possible to configure a small and highly efficient light source device while ensuring high uniformity by eliminating luminance unevenness and color unevenness in the image. (Embodiment 2) FIG. 4 is a configuration diagram of a second light source device 75 showing an embodiment of the present disclosure.

[0022] The second light source device 75 includes a red laser light source 52 composed of a red semiconductor laser substrate 50 on which a plurality of red semiconductor laser elements are arranged and a collimating lens array 51, a red laser light source 56 composed of a red semiconductor laser substrate 54 on which a plurality of red semiconductor laser elements are arranged and a collimating lens array 55, a first polarization mirror 58, a dichroic mirror 59 that reflects green, a second polarization mirror 64, a green laser light source 62 composed of a green semiconductor laser substrate 60 on which a plurality of green semiconductor laser elements are arranged and a collimating lens array 61, a green laser light source 67 composed of a green semiconductor laser substrate 65 on which a plurality of green semiconductor laser elements are arranged and a collimating lens array 66, a blue laser light source 73 composed of a blue semiconductor laser substrate 71 on which a plurality of blue semiconductor laser elements are arranged and a collimating lens array 72, a beam splitting element 69, a dichroic mirror 70 that reflects blue, and heat sinks 53, 57, 63, 68, 74. In the figure, the polarization direction of the light emitted from the laser light source is shown. The difference from the embodiment of FIG. 1 is the characteristics of the second polarization mirror, and the fact that it does not include a filter or a retardation plate, but includes a dichroic mirror that reflects green.

[0023] The red laser light source 52 is composed of a red semiconductor laser substrate 50 in which 24 (6×4) red semiconductor laser elements are two-dimensionally arranged at regular intervals and a collimating lens array 51. The red semiconductor laser substrate 50 emits red-colored light with a wavelength width of 640±8 nm and emits light that becomes P-polarized light with respect to the first polarization mirror 58. The light emitted from the red semiconductor laser substrate 50 is condensed by the corresponding collimating lens array 51 and converted into a parallel light beam. The heat sink 53 cools the red semiconductor laser substrate 50. The red laser light source 56 is composed of a red semiconductor laser substrate 54 in which 24 (6×4) red semiconductor laser elements are two-dimensionally arranged at regular intervals and a collimating lens array 55. The red semiconductor laser substrate 54 emits red-colored light with a wavelength width of 640±8 nm and emits light that becomes S-polarized light with respect to the first polarization mirror 58. The light emitted from the red semiconductor laser substrate 54 is condensed by the corresponding collimating lens array 55 and converted into a parallel light beam. The heat sink 57 cools the red semiconductor laser substrate 54. The laser light from the red laser light sources 52 and 56 enters the first polarization mirror 58 with P-polarized light and S-polarized light, respectively. The first polarization mirror 58 is arranged such that the incident angle is 45 degrees. The first polarization mirror 58 transmits more than 95% of the red laser light with P-polarized light and reflects more than 95% of the red laser light with S-polarized light. The light from a plurality of red laser light sources is synthesized by the first polarization mirror 58 and then enters the dichroic mirror 59 with green reflection.

[0024] The green laser light source 62 is composed of a green semiconductor laser substrate 60 in which 24 (6×4) green semiconductor laser elements are two-dimensionally arranged at regular intervals and a collimating lens array 61. The green semiconductor laser substrate 60 emits green-colored light with a wavelength width of 525±8 nm, and emits light that becomes P-polarized light with respect to the green reflection dichroic mirror 59. The light emitted from the green semiconductor laser substrate 60 is condensed by the corresponding collimating lens array 61 and converted into parallel light beams. The heat sink 63 is for cooling the green semiconductor laser substrate 60. The green reflection dichroic mirror 59 is arranged at an incident angle of 45 degrees. The green reflection dichroic mirror 59 reflects 95% or more of the P-polarized green laser light and transmits 95% or more of the P-polarized and S-polarized red laser light. The light from the red laser light sources 52 and 56 and the light from the green laser light source 62 are combined by the green reflection dichroic mirror 59 and then enter the second polarizing mirror 64.

[0025] The green laser light source 67 is composed of a green semiconductor laser substrate 65 in which 24 (6×4) green semiconductor laser elements are two-dimensionally arranged at regular intervals and a collimating lens array 66. The green semiconductor laser substrate 65 emits green-colored light with a wavelength width of 525±8 nm, and emits light that becomes S-polarized light with respect to the second polarizing mirror 64. The light emitted from the green semiconductor laser substrate 65 is condensed by the corresponding collimating lens array 66 and converted into parallel light beams. The heat sink 68 is for cooling the green semiconductor laser substrate 65.

[0026] The laser light from the green laser light source 67 is S-polarized and enters the second polarizing mirror 64. The second polarizing mirror 64 is arranged at an incident angle of 45 degrees. The second polarizing mirror 64 acts as a polarization beam splitter for the green laser light and acts as a red transmission dichroic mirror for the red laser light. The second polarizing mirror 64 transmits 95% or more of the P-polarized green laser light and the P-polarized and S-polarized red laser light, and reflects 95% or more of the S-polarized green laser light.

[0027] The light from the red laser light sources 52 and 56 and the light from the green laser light source 62 pass through the second polarization mirror 64 with a transmittance of 95% or more. The light from the green laser light source 67 is reflected by the second polarization mirror 64 with a reflectance of 95% or more. In this way, the light from the plurality of red laser light sources and the light from the plurality of green laser light sources are combined.

[0028] The blue laser light source 73 is composed of a blue semiconductor laser substrate 71 in which 12 (6×2) blue semiconductor laser elements are two-dimensionally arranged at regular intervals and a collimating lens array 72. The blue semiconductor laser substrate 71 emits blue-colored light with a wavelength width of 465±8 nm and emits light that becomes S-polarized light with respect to the beam splitting element 69. The blue semiconductor laser has a high emission efficiency and a small optical output required for a desired white light chromaticity compared to red and green semiconductor lasers, so it is composed of about one-fourth the number of semiconductor lasers. The light emitted from the blue semiconductor laser substrate 71 is collected by the corresponding collimating lens array 72 and converted into parallel light beams. The heat sink 74 is for cooling the blue semiconductor laser substrate 71. The light from the blue laser light source 73 is incident on the beam splitting element 69. The beam splitting element 69 is arranged with an incident angle of 45 degrees. The beam splitting element 69 divides the S-polarized blue light into transmitted light and reflected light at approximately 50% each, and transmits the P-polarized and S-polarized green and red light with a transmittance of 95% or more. The blue light transmitted through the beam splitting element 69 is incident on the blue-reflecting dichroic mirror 70. The blue-reflecting dichroic mirror 70 is arranged with an incident angle of 45 degrees. The blue-reflecting dichroic mirror 70 reflects the blue light with a reflectance of 95% or more and transmits the green and red light with a reflectance of 95% or more. The beam splitting element 69 and the blue-reflecting dichroic mirror 70 make the beam sizes of the light from the red and green laser light sources and the beam size of the light from the blue laser light source substantially equal and combine them with high efficiency. In this way, blue, green, and red laser lights are combined in a small size and with high efficiency to emit white light.

[0029] For the light source device shown in FIG. 1, instead of arranging a quarter-wave plate, a dichroic mirror for green reflection is arranged, so it becomes slightly larger. However, since an expensive quarter-wave plate is not arranged, an inexpensive light source device can be configured.

[0030] The green laser light source, the red laser light source, and the blue laser light source are shown with configurations in which 48, 48, and 12 semiconductor laser elements are arranged respectively. However, for higher brightness, they may be configured using a larger number of semiconductor laser elements respectively.

[0031] Although the laser light sources 52 and 56 have been described as red laser light sources, and the laser light sources 62 and 67 have been described as green laser light sources, by changing the characteristics of the first and second polarizing mirrors, the dichroic mirror for green reflection, etc., they may be used as green laser light sources and red laser light sources respectively.

[0032] As described above, the light source device of the present disclosure includes a blue, green, and red laser light source, a polarizing mirror, a dichroic mirror, and a beam splitting element, thereby equalizing the beam sizes of the laser lights of each color light. For this reason, a small and highly efficient light source device can be configured while ensuring high uniformity. (Embodiment 3) FIG. 5 is a configuration diagram of a third light source device 87 showing an embodiment of the present disclosure.

[0033] The third light source device 87 includes a red laser light source 22, 26, a green laser light source 34, 38, a light source optical system 76 composed of an optical system that synthesizes red laser light and green laser light, a blue semiconductor laser substrate 80 on which a plurality of blue semiconductor laser elements are arranged, a blue laser light source 82 including a collimating lens array 81, a dichroic mirror 84 that transmits blue light, a beam splitting element 85, a dichroic mirror 86 that reflects blue light, and a heat sink 83.

[0034] The light source optical system 76 specifically includes a plurality of red laser light sources 22, 26, green laser light sources 34, 38, heat sinks 23, 27, 35, 39 for each laser light source, a first polarizing mirror 28, a filter 29, a quarter-wave plate 30, and a second polarizing mirror 31. The configuration of the optical system that combines these red laser light and green laser light is the same as that of the first light source device 46 in the first embodiment shown in FIG. 1. Also, for the purpose of increasing brightness, a plurality of red and green laser light sources and optical systems that combine the light from each red and green laser light source are used in combination. In this embodiment, two light source optical systems 76 are provided. In the figure, the polarization directions of the light emitted from the laser light sources are shown.

[0035] The red laser light and the green laser light incident on the blue-transmissive dichroic mirror 84 are reflected by the blue-transmissive dichroic mirror 84 and then incident on the beam splitting element 85. The blue-transmissive dichroic mirror 84 is arranged at an incident angle of 45 degrees. The blue-transmissive dichroic mirror 84 reflects red light and green light by 95% or more and transmits blue light by 95% or more.

[0036] The red laser light and the green laser light incident on the blue-reflective dichroic mirror 86 pass through the blue-reflective dichroic mirror 86. The blue-reflective dichroic mirror 86 is arranged at an incident angle of 45 degrees. The blue-reflective dichroic mirror 86 transmits red light and green light by 95% or more and reflects blue light by 95% or more.

[0037] The blue laser light source 82 is composed of a blue semiconductor laser substrate 80 on which 24 (6×4) blue semiconductor laser elements are two-dimensionally arranged at regular intervals and a collimating lens array 81. The blue semiconductor laser substrate 80 emits blue-colored light with a wavelength width of 465±8 nm and emits light that becomes S-polarized light with respect to the beam splitting element 85. The blue semiconductor laser is composed of about one-fourth the number of semiconductor lasers because it has high luminous efficiency and a small optical output required for a desired white light chromaticity compared to red and green semiconductor lasers. The light emitted from the blue semiconductor laser substrate 80 is condensed by the corresponding collimating lens array 81 and converted into parallel light beams. The heat sink 83 is for cooling the blue semiconductor laser substrate 80. The light from the blue laser light source 82 passes through the blue-transmissive dichroic mirror 84 and enters the beam splitting element 85.

[0038] Fig. 6 shows the spectroscopic characteristics of the beam splitting element. The spectroscopic characteristics show the spectroscopic transmittance of P-polarized light and S-polarized light at an incident angle of 45 degrees. The spectroscopic characteristics are a designed example in which 59 optical thin films of high refractive index materials such as TiO2 and low refractive index materials such as SiO2 are alternately formed on the glass substrate of the beam splitting element. The beam splitting element 85 splits the S-polarized blue light into transmission and reflection at approximately 50% each, and reflects the P-polarized and S-polarized green light and red light at 90% or more including the tolerance. The characteristics of transmitting and reflecting the blue light at approximately 50% each are characteristics of transmitting at 40 to 60% and reflecting at 60% to 40% including the tolerance. The beam splitting element 85 reflects approximately 50% of the blue light and the green light and red light reflected by the blue-transmissive dichroic mirror 84. Approximately 50% of the blue light transmitted through the beam splitting element 85 is reflected by the blue-reflective dichroic mirror 86 and synthesized with the green light and red light transmitted through the blue-reflective dichroic mirror 86.

[0039] The beam splitting element 85 and the blue-reflective dichroic mirror 86 substantially equalize the beam sizes of the light from the red and green laser light sources and the beam size of the light from the blue laser light source and synthesize them with high efficiency. In this way, the blue, green, and red laser lights are synthesized in a small size and with high efficiency to emit white light.

[0040] Compared with the light source device of Embodiment 1 shown in FIG. 1, since a larger number of laser elements are used than the number of laser elements of the red, green, and blue laser light sources, the brightness can be increased. In addition, since a plurality of optical systems for synthesizing the red laser light source and the green laser light are used, the cost can be reduced while increasing the brightness.

[0041] As described above, the light source device of the present disclosure includes a blue, green, and red laser light source, a polarization mirror, a retardation plate, a filter, and a beam splitting element, thereby equalizing the beam sizes of the laser lights of each color light. For this reason, a small and highly efficient light source device can be configured while ensuring high uniformity. (Embodiment 4) FIG. 7 is a first projection display device showing an embodiment of the present disclosure. As an image forming means, an active matrix type transmissive liquid crystal panel in which a thin film transistor is formed in a pixel region and which is in a TN mode or a VA mode is used. The light source device 46 is the light source device of Embodiment 1 of the present disclosure.

[0042] In addition to the light source device 46, the first projection display device includes condenser lenses 100 and 106, a diffusion plate 101, a reflection mirror 102, a rotating diffusion plate 105 which is a dynamic diffusion plate, a first lens array plate 200, a second lens array plate 201, a polarization conversion element 202, a superimposing lens 203, a dichroic mirror 204 for blue reflection, a dichroic mirror 205 for green reflection, reflection mirrors 206, 207, and 208, relay lenses 209 and 210, field lenses 211, 212, and 213, incident side polarizing plates 214, 215, and 216, liquid crystal panels 217, 218, and 219, exit side polarizing plates 220, 221, and 222, a color synthesis prism 223 composed of a dichroic mirror for red reflection and a dichroic mirror for blue reflection, and a projection lens 224.

[0043] The blue, green, and red laser lights emitted from the light source device 46 pass through and are reflected by the condenser lens 100, the diffuser plate 101, and the reflection mirror 102, and then are focused on the rotating diffuser plate 105. The diffuser plate 101 is formed by arranging fine microlenses on a glass substrate in an array to form a diffusing surface, which diffuses the incident light. The diffusion angle, which is the half-value angle width at 50% of the maximum intensity of the diffused light, is approximately 2 degrees, and the degree of diffusion is reduced to suppress the loss due to diffusion. The rotating diffuser plate 105 includes a circular diffuser plate 104 having a diffusing layer with a fine uneven shape formed on one surface of a glass substrate and a motor 103 at the center, and its rotation can be controlled. The diffusion angle of the rotating diffuser plate 105 is approximately 10 degrees. The rotating diffuser plate 105 can cause the random interference pattern on the screen caused by the laser light to vary rapidly in time and space, thereby eliminating the speckle noise. Also, in combination with the diffuser plate 101, the minute luminance unevenness caused by the minute light emission size and the number of light emissions of the laser light source can be reduced. The light diffused by the rotating diffuser plate 105 is focused by the condenser lens 106 and converted into approximately parallel light. The approximately parallel light is incident on the first lens array plate 200 composed of a plurality of lens elements.

[0044] The light beam incident on the first lens array plate 200 is divided into a number of light beams. The divided number of light beams converge on the second lens array plate 201 composed of a plurality of lenses. The lens elements of the first lens array plate 200 have an aperture shape similar to that of the liquid crystal panels 217, 218, and 219. The focal lengths of the lens elements of the second lens array plate 201 are determined such that the first lens array plate 200 and the liquid crystal panels 217, 218, and 219 are in a substantially conjugate relationship. The divided light from the second lens array plate 201 is incident on the polarization conversion element 202. The polarization conversion element 202 is composed of a polarization beam splitter prism and a half-wave plate. The polarization conversion element 202 converts the incident P-polarized light into S-polarized light and emits the incident S-polarized light as S-polarized light. The light emitted from the polarization conversion element 202 is incident on the superimposing lens 203. The superimposing lens 203 is a lens for superimposing and illuminating the light emitted from each lens element of the second lens array plate 201 onto the liquid crystal panels 217, 218, and 219. The first and second lens array plates 200 and 201 and the superimposing lens 203 constitute an illumination optical system. The light from the superimposing lens 203 is separated into blue, green, and red color lights by the dichroic mirrors 204 for blue reflection and 205 for green reflection, which are color separation means. The green color light passes through the field lens 211 and the incident-side polarizing plate 214 and is incident on the liquid crystal panel 217. The blue color light is reflected by the reflection mirror 206 and then passes through the field lens 212 and the incident-side polarizing plate 215 and is incident on the liquid crystal panel 218. The red color light passes through and is refracted and reflected by the relay lenses 209 and 210 and the reflection mirrors 207 and 208, passes through the field lens 213 and the incident-side polarizing plate 216, and is incident on the liquid crystal panel 219. The three liquid crystal panels 217, 218, and 219 change the polarization state of the incident light by controlling the applied voltage to the pixels according to the video signal, and combine the incident-side polarizing plates 214, 215, and 216 and the exit-side polarizing plates 220, 221, and 222 arranged such that the transmission axes are orthogonal to each other on both sides of each of the liquid crystal panels 217, 218, and 219 to modulate the light and form green, blue, and red images.The light of each color that has passed through the exit-side polarizing plates 220, 221, and 222 is reflected by a dichroic mirror for red reflection and a dichroic mirror for blue reflection for the red and blue light of each color by the color-combining prism 223, combined with the green light, and incident on the projection lens 224. The light incident on the projection lens 224 is enlarged and projected onto a screen (not shown).

[0045] The rotating diffuser plate 105 may be a dynamic diffuser plate that sways or vibrates instead of rotating.

[0046] Since the image forming means uses three liquid crystal panels that utilize polarization instead of the time-division method, there is no color breaking, color reproduction is good, and a bright and high-definition projection image can be obtained. Also, compared to the case of using three DMD elements, a total reflection prism is not required, and the prism for color combination becomes a small prism with a 45-degree incidence, so the projection display device can be configured to be small. As the light source device, the light source device 75 of the second embodiment or the light source device 87 of the third embodiment may be used.

[0047] As described above, the first projection display device of the present disclosure uses a light source device that is highly uniform and miniaturized by a blue, green, and red laser light source, a polarization mirror, and a beam splitting element. Also, the light from the light source device is passed through a dynamic diffuser plate to eliminate speckle noise. Therefore, a small, highly efficient projection display device with high uniformity can be configured while eliminating speckle noise and brightness unevenness.

[0048] As the image forming means, a transmissive liquid crystal panel is used, but it may be configured using a reflective liquid crystal panel. By using a reflective liquid crystal panel, a smaller and higher-definition projection display device can be configured. (Embodiment 5) FIG. 8 is a second projection display device showing an embodiment of the present disclosure. As the image forming means, three DMDs are used. The light source device is the light source device 46 shown in Embodiment 1 of the present disclosure.

[0049] The second projection display device includes, in addition to the light source device 46, a condenser lens 110, a diffusion plate 111, a reflection mirror 112, a rotating diffusion plate 115 which is a dynamic diffusion plate, a rod 301, a relay lens 302, a reflection mirror 303, a field lens 304, a total reflection prism 305, an air layer 306, a color prism 307 formed of three prisms in which a dichroic mirror 308 that reflects blue light and a dichroic mirror 309 that reflects red light are formed, DMDs 310, 311, 312, and a projection lens 313.

[0050] The blue, green, and red laser lights emitted from the light source device 46 pass through the condenser lens 110, are diffused by the diffusion plate 111, reflected by the reflection mirror 112, and then condensed onto the rotating diffusion plate 115. The rotating diffusion plate 115 is a circular diffusion plate 114 having a diffusion layer formed on one surface of a glass substrate and a motor 113 provided at the center, and is capable of rotation control. The diffusion angle of the rotating diffusion plate 115 is approximately 10 degrees. By the rotating diffusion plate 115, the random interference pattern on the screen caused by the laser light fluctuates rapidly in time and space, and the speckle noise can be eliminated. Also, in combination with the diffusion plate 111, the minute luminance unevenness caused by the minute light emission size and the number of light emissions of the laser light source can be reduced. The light diffused by the rotating diffusion plate 115 enters the rod 301.

[0051] The incident light on the rod 301 is reflected multiple times inside the rod, and the light intensity distribution is equalized and then emitted. The light emitted from the rod 301 is condensed by the relay lens 302, reflected by the reflection mirror 303, then transmitted through the field lens 304, and incident on the total reflection prism 305. The total reflection prism 305 is composed of two prisms, and a thin air layer 306 is formed on the adjacent surfaces of the prisms. The air layer 306 totally reflects the light incident at an angle greater than the critical angle. The light from the field lens 304 is reflected by the total reflection surface of the total reflection prism 305 and incident on the color prism 307. The color prism 307 consists of three prisms, and a dichroic mirror 308 for blue reflection and a dichroic mirror 309 for red reflection are formed on the adjacent surfaces of the respective prisms. The dichroic mirror 308 for blue reflection and the dichroic mirror 309 for red reflection of the color prism 307 separate the light into blue, red, and green color lights, which are respectively incident on the DMDs 310, 311, and 312. The DMDs 310, 311, and 312 deflect the micromirrors according to the video signal, and reflect the light incident on the projection lens 313 and the light that travels outside the effective range of the projection lens 313. The light reflected by the DMDs 310, 311, and 312 passes through the color prism 307 again. In the process of passing through the color prism 307, the separated blue, red, and green color lights are synthesized and incident on the total reflection prism 305. Since the light incident on the total reflection prism 305 is incident on the air layer 306 at an angle less than the critical angle, it is transmitted and incident on the projection lens 313. In this way, the image light formed by the DMDs 310, 311, and 312 is enlarged and projected onto a screen (not shown). The rotating diffusion plate 115 may be a dynamic diffusion plate that sways or vibrates instead of rotating.

[0052] Since the DMD is used in the image forming means, a projection display device with high light resistance and heat resistance can be configured compared to the image forming means using liquid crystal. Furthermore, since three DMDs are used, good color reproduction can be achieved, and a bright and high-definition projection image can be obtained. As the light source device, the light source device 75 of the second embodiment or the light source device 87 of the third embodiment may be used.

[0053] As described above, the second projection display device of the present disclosure uses a light source device that is highly uniform and miniaturized by a blue, green, and red laser light source, a polarization mirror, and a beam splitting element. Further, the light from the light source device is passed through a dynamic diffuser to eliminate speckle noise. Therefore, it is possible to configure a small and highly efficient projection display device while eliminating speckle noise and luminance unevenness.

Industrial Applicability

[0054] The present disclosure relates to a projection display device using an image forming means.

Explanation of Signs

[0055] 20, 24, 50, 54 Red semiconductor laser substrate 21, 25, 33, 37, 43, 51, 55, 61, 66, 72, 81 Collimator lens array 22, 26, 52, 56 Red laser light source 23, 27, 35, 39, 45, 53, 57, 63, 68, 74, 83 Heat sink 28, 58 First polarization mirror 29 Red-transmitting, green-reflecting filter 30 Quarter-wave plate 31, 64 Second polarization mirror 32, 36, 60, 65 Green semiconductor laser substrate 34, 38, 62, 67 Green laser light source 40, 69, 85 Beam splitting element 41, 70, 86, 204, 308 Blue-reflecting dichroic mirror 42, 71, 80 Blue semiconductor laser substrate 44, 73, 82 Blue laser light source 46, 75, 87 Light source device 84 Blue-transmitting dichroic mirror 100, 106, 110 Condenser lens 101, 111 Diffuser 102, 112, 206, 207, 208, 303 Reflecting mirror 103, 113 Motor 104 and 114 circular diffusion plates 105 and 115 rotating diffusion plates 200 First lens array plate 201 Second lens array plate, 202 Polarization conversion element 203 Superposition lens 59 and 205 Green-reflecting dichroic mirror 209, 210, and 302 Relay lenses 214, 215, and 216 Incident-side polarizing plates 217, 218, and 219 Liquid crystal panels 220, 221, and 222 Exit-side polarizing plates 223 Color-combining prism 224 and 313 Projection lenses 301 Rod 211, 212, 213, and 304 Field lenses 305 Total reflection prism 306 Air layer 307 Color prism 309 Red-reflecting dichroic mirror 310, 311, and 312 DMD

Claims

1. A plurality of red, green, and blue solid-state light sources; a polarizing mirror that combines the colored light from the solid-state light sources; a beam splitting element for splitting a light beam from the blue solid-state light source; The beam splitting element is a mirror that splits blue light into a transmitted light and a reflected light at approximately 50% each, and transmits or reflects green light and red light at approximately 90% or more.

2. 2. The light source device according to claim 1, wherein the polarizing mirror is a mirror having a property of a polarizing beam splitter.

3. 2. The light source device according to claim 1, further comprising a phase difference plate for converting the linearly polarized light from the solid-state light source reflected by the polarizing mirror into circularly polarized light, and a filter for inverting the phase of the light from the phase difference plate and reflecting it.

4. 2. The light source device according to claim 1, wherein the light emitted from said solid-state light source is linearly polarized light.

5. A light source; a dynamic diffuser that receives the combined light from the light sources and reduces speckle noise in the light from the light sources; an illumination optical system that collects light from the dynamic diffuser plate and illuminates an illumination area; an image forming element that forms an image in response to a video signal; a projection lens for enlarging and projecting an image formed by the image forming element; 2. A projection display device, wherein said light source is the light source device according to claim 1.

6. 6. A projection display device according to claim 5, wherein said dynamic diffuser plate is a circular diffuser plate having a minute uneven shape or a lens shape formed in a circular shape on the surface of a glass substrate, and a rotating diffuser plate provided with a motor.

7. 6. A projection display device according to claim 5, wherein said image forming element is a liquid crystal panel.

8. 6. A projection display device according to claim 5, wherein the image forming element is a mirror deflection type digital micromirror device (DMD).

Images