Light source device and projection display device

Abstract

To provide a light source device and a projection display device which suppress a deterioration in luminous efficiency of a phosphor by suppressing the heating of the phosphor.SOLUTION: A light source device 10 includes: a solid light source unit 23 for emitting a blue laser beam; a first dichroic mirror 30; a first phosphor element 40 for generating green fluorescence by receiving the light from the light source; and a second phosphor element 46 for generating yellow fluorescence by receiving the light from the light source. The first dichroic mirror 30 has such characteristics that the yellow fluorescence is transmitted and the green fluorescence is reflected.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a light source device and a projection display device, and more particularly to a light source device including a phosphor and a projection display device including the light source device.

Background Art

[0002] In recent years, projection display devices using solid light sources such as semiconductor lasers and light emitting diodes have been known as light sources for projection display devices using an image light forming section of a liquid crystal panel or a mirror deflection type DMD (Digital Micromirror Device) (see, for example, Patent Document 1).

[0003] The light source device of Patent Document 1 includes a light source, a light separation element, a phosphor, a first reflection element, a quarter-wave plate, a diffusion plate, and a second reflection element. The light source outputs excitation light having a wavelength in the visible light region. The light separation element is set to have a cut-off wavelength so as to have a high reflection characteristic for S-polarized light and a high transmission characteristic for P-polarized light among lights having wavelengths in the visible light region, and separates the light from the light source. One of the lights separated by the light separation element is irradiated onto the phosphor. The first reflection element reflects the light emitted by the phosphor to the light separation element. The quarter-wave plate adjusts the polarization of the other light among the lights separated by the light separation element. The diffusion plate diffuses the other light among the lights separated by the light separation element and can maintain the polarization direction of the other light. The second reflection element guides the other light transmitted through the quarter-wave plate to the light separation element via the quarter-wave plate. Thereby, a long-life light source device is configured.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, when the laser light is condensed on the phosphor, there is a problem that the phosphor generates heat due to the high energy density of the laser light, and the luminous efficiency of the phosphor deteriorates. In particular, when trying to increase the output of the light source device, this problem becomes prominent, which may lead to output saturation of the light source device and the projection display device including this light source device.

[0006] In view of such circumstances, the present disclosure has been made, and an object thereof is to provide a light source device and a projection display device capable of suppressing a decrease in the luminous efficiency of a phosphor by suppressing heat generation of the phosphor.

Means for Solving the Problems

[0007] In order to achieve the above object, a light source device according to an aspect of the present disclosure includes a light source, a first light separation element, a first phosphor, and a second phosphor. The first light separation element transmits light having a first polarization direction among the light from the light source, and reflects light having a second polarization direction different from the first polarization direction. The first phosphor is irradiated with the light transmitted through the first light separation element and emits light in a first wavelength range. The second phosphor is irradiated with the light reflected by the first light separation element and emits light in a second wavelength range different from the first wavelength range. The first light separation element transmits one of the light in the first wavelength range and the light in the second wavelength range and reflects the other.

[0008] A projection display device according to an aspect of the present disclosure includes the light source device.

Effects of the Invention

[0009] According to the above configuration, it is possible to provide a light source device and a projection display device capable of suppressing a decrease in the luminous efficiency of a phosphor by suppressing heat generation of the phosphor.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiment for Carrying Out the Invention

[0011] Hereinafter, embodiments will be described in detail with reference to the drawings as appropriate. However, a more detailed description than necessary may be omitted. For example, detailed descriptions of well-known matters and duplicate descriptions of substantially the same configurations may be omitted. This is to avoid making the following description unnecessarily redundant and to facilitate understanding by those skilled in the art.

[0012] Note that the inventors provide the accompanying drawings and the following description in order for those skilled in the art to fully understand the present disclosure, and do not intend to limit the subject matter described in the claims thereby.

[0013] (Embodiment) [1. Outline of the Configuration of the Light Source Device] Hereinafter, embodiments for carrying out the present disclosure will be described with reference to FIGS. 1 to 3.

[0014] FIG. 1 is a configuration diagram of a light source device 10 according to an embodiment.

[0015] The light source device 10 includes a solid light source unit 23, a first dichroic mirror 30, a first phosphor element 40, a second phosphor element 46, a second dichroic mirror 32, a quarter-wave plate 36 corresponding to a first retardation plate, a quarter-wave plate 34 corresponding to a second retardation plate, and a reflector 38 (reflective element).

[0016] The solid-state light source unit 23 includes a semiconductor laser 20 which is a solid-state light source, a heat sink 21, and a collimating lens 22. In the configuration of the present embodiment, the semiconductor laser 20 is disposed on the heat sink 21, and the collimating lens 22 is disposed at a position to receive the light beam emitted from the semiconductor laser 20.

[0017] The semiconductor laser 20 emits linearly polarized blue light with a wavelength range of 440 nm or more and 455 nm or less. In the present embodiment, 24 semiconductor lasers 20 are arranged in a 6×4 rectangular shape in a two-dimensional manner at regular intervals.

[0018] Also, the number and arrangement method of the semiconductor lasers 20 are not limited to the present embodiment. The number and arrangement method of the semiconductor lasers 20 may be, for example, a form in which only one semiconductor laser 20 is arranged and a form in which 16 semiconductor lasers 20 are arranged in a 4×4 square shape.

[0019] The heat sink 24 is fixed to the heat sink 21 by screwing. The heat generated with the output of the semiconductor laser 20 is cooled by the heat sink 24 via the heat sink 21.

[0020] The diffuser plate 61 is disposed at a position to receive the light that has passed through the collimating lens 22. The surface of the diffuser plate 61 has a structure that diffuses light due to a fine uneven shape. Also, the diffuser plate 61 uses one with a sufficiently small diffusion angle value so that the polarization characteristics of the passed light are maintained.

[0021] The second dichroic mirror 32 is disposed at a position to receive the light that has passed through the diffuser plate 61. The second dichroic mirror 32 is an optical separation element that separates the light from the semiconductor laser 20 in two directions according to the spectroscopic characteristics. The cut-off wavelength of the second dichroic mirror 32 is set to be approximately equal to the wavelength range of the light emitted from the semiconductor laser 20.

[0022] Figure 2 is a graph showing the spectral characteristics of the second dichroic mirror 32. Figure 2 shows the transmittance of the second dichroic mirror 32 with respect to the wavelength of the light incident on the second dichroic mirror 32. The second dichroic mirror 32 transmits light with P polarization with a high transmittance with respect to light with S polarization in the wavelength range of 440 nm or more and 455 nm or less, which is the wavelength range of the light output by the semiconductor laser 20, and reflects light with S polarization with a high reflectance with respect to light with P polarization. Also, the second dichroic mirror 32 has the characteristic of transmitting both light with P polarization and light with S polarization in the wavelength range of 500 nm or more. That is, the second dichroic mirror 32 is an element that reflects or transmits blue light according to the polarization characteristics and transmits green light and red light regardless of the polarization characteristics.

[0023] Returning to the description of FIG. 1, the quarter-wave plate 34 is disposed at a position where it receives the light reflected by the second dichroic mirror 32. The quarter-wave plate 34 is a quarter-wave plate having a phase difference of a quarter wavelength near the emission wavelength of the semiconductor laser 20. The quarter-wave plate 34 is installed so that the incident light with S polarization is converted into circular polarization by the quarter-wave plate 34.

[0024] The first dichroic mirror 30 is disposed at a position where it receives the light that has passed through the quarter-wave plate 34, and is an optical separation element that separates the light adjusted to circular polarization by the quarter-wave plate 34 into two directions according to the spectral characteristics of the first dichroic mirror 30. The first dichroic mirror 30 has a characteristic of having a higher reflectance for light with S polarization than for light with P polarization and a higher transmittance for light with P polarization than for light with S polarization in the light output from the semiconductor laser 20 and converted into circular polarization by the quarter-wave plate 34. As will be described later in the description of FIG. 3, the first dichroic mirror 30 further has the characteristic of reflecting or transmitting the incident light according to the wavelength.

[0025] Figure 3 is a graph showing the spectral characteristics of the first dichroic mirror 30. The first dichroic mirror 30 transmits P-polarized light with a high transmittance with respect to S-polarized light in semiconductor laser light having a wavelength range from around 440 nm to around 455 nm, which is the wavelength range of the light output by the semiconductor laser 20, and reflects S-polarized light with a high reflectance with respect to P-polarized light. Further, the first dichroic mirror 30 has the characteristic of transmitting light in both P-polarized and S-polarized directions in the range from around 470 nm to around 585 nm in wavelength. Also, the first dichroic mirror 30 has the characteristic of reflecting light in both P-polarized and S-polarized directions in a wavelength range of 585 nm or more. That is, the first dichroic mirror 30 has the characteristic of reflecting or transmitting blue light according to the polarization characteristics, transmitting light from green to yellow regardless of the polarization direction, and reflecting red light regardless of the polarization direction.

[0026] Returning to the description of FIG. 1, the first condenser lens group 62 is a first condensing element. The first condenser lens group 62 is disposed at a position where it receives the light transmitted through the first dichroic mirror 30. The first condenser lens group 62 condenses the light transmitted through the first dichroic mirror 30 and makes it incident on a first phosphor element 40 described later.

[0027] The first phosphor element 40 includes a first phosphor layer 41, a reflective layer 42, a heat sink 43, and a heat sink 45.

[0028] The first phosphor layer 41 is a phosphor that is excited by blue light having a wavelength range of 440 nm or more and 455 nm or less, which is the wavelength range of the semiconductor laser 20, and emits green light. The first phosphor layer 41 is formed of a Ce-activated LuAG-based phosphor, and a typical chemical composition of this crystal matrix is Lu3Al5O 12 is. The first phosphor layer 41 is irradiated with the light transmitted through the first dichroic mirror 30, which is a light separation element, and emits light in the green wavelength range.

[0029] The reflective layer 42 is provided on a second surface 412 that faces a first surface 411 irradiated with the light transmitted through the first dichroic mirror 30 in the first phosphor layer 41. The reflective layer 42 is a metal film that reflects visible light. The reflective layer 42 reflects the green light emitted by the incident first phosphor layer 41 in the direction of the first dichroic mirror 30. As a result, the light emitted by the first phosphor layer 41 is emitted in the direction of the first dichroic mirror 30. The light emitted from the first phosphor layer 41 is condensed by the first condenser lens group 62 and irradiated as a light beam parallel to the first dichroic mirror 30.

[0030] The heat sink 45 is connected to the first phosphor layer 41 via the heat dissipation plate 43. The heat sink 45 is for cooling the first phosphor layer 41. Since the heat generated by the excitation light in the first phosphor layer 41 is transmitted from the first phosphor layer 41 to the heat sink 45, the temperature rise of the first phosphor layer 41 due to the excitation light is suppressed. Thereby, the first phosphor element 40 can stably maintain the fluorescence conversion efficiency of the first phosphor layer 41.

[0031] The second condenser lens group 63 is a second condenser element. The second condenser lens group 63 is disposed at a position that receives the light reflected by the first dichroic mirror 30. The second condenser lens group 63 condenses the light reflected by the first dichroic mirror 30 and makes it incident on a second phosphor element 46 described later.

[0032] The second phosphor element 46 includes a second phosphor layer 47, a reflective layer 48, a heat dissipation plate 49, and a heat sink 51.

[0033] The second phosphor layer 47 is a phosphor that is excited by blue light in a wavelength range of 440 nm or more and 455 nm or less, which is the wavelength range of the semiconductor laser 20, and mainly emits yellow light. The second phosphor layer 47 is formed of a Ce-activated YAG-based phosphor, and a typical chemical composition of this crystal matrix is Y3Al5O 12The second phosphor layer 47 is irradiated with the light reflected by the first dichroic mirror 30 which is a light separation element, and emits light in the yellow wavelength range.

[0034] The reflective layer 48 is provided on a second surface 472 opposite to a first surface 471 irradiated with the light reflected by the first dichroic mirror 30 in the second phosphor layer 47. The reflective layer 48 is a metal film that reflects visible light. The reflective layer 48 reflects the yellow light emitted by the incident second phosphor element 46 in the direction of the first dichroic mirror 30. Thereby, the light emitted by the second phosphor layer 47 is emitted in the direction of the first dichroic mirror 30. The light emitted from the second phosphor layer 47 is condensed by the second condenser lens group 63 and irradiated as a light beam parallel to the first dichroic mirror 30.

[0035] The heat sink 51 is connected to the second phosphor layer 47 via the heat radiating plate 49. The heat sink 51 is for cooling the second phosphor layer 47. Since the heat generated by the excitation light in the second phosphor layer 47 is transmitted from the second phosphor layer 47 to the heat sink 51, the temperature rise of the second phosphor layer 47 due to the excitation light is suppressed. Thereby, the second phosphor element 46 can stably maintain the fluorescence conversion efficiency of the second phosphor layer 47.

[0036] The condenser lens 64 is a third condensing element. The light incident on the condenser lens 64 condenses the light transmitted through the second dichroic mirror 32 and forms a condensing spot in the vicinity of a reflecting plate 38 described later.

[0037] The quarter-wave plate 36 which is the second retardation plate is composed of a crystal, a stretched film, etc., and is arranged at a position receiving the light condensed by the condenser lens 64. The quarter-wave plate 36 adjusts the P-polarized blue light transmitted through the second dichroic mirror 32 into circularly polarized light.

[0038] The reflector 38 is a reflective element composed of a mirror or the like. The reflector 38 is configured to guide the light transmitted through the quarter-wave plate 36 to the second dichroic mirror 32 via the quarter-wave plate 36.

[0039] [2. Details of the configuration and operation of the light source device] Hereinafter, the details of the configuration and operation of the light source device 10 will be described.

[0040] The semiconductor laser 20 emits linearly polarized blue light with a wavelength range of 440 nm or more and 455 nm or less. The polarization direction of the blue light emitted from the semiconductor laser 20 is adjusted and installed so as to be incident at an azimuth angle at a desired angle with respect to the transmission axis of the second dichroic mirror 32. In the present embodiment, the polarization of the light emitted from the semiconductor laser 20 is adjusted so that about 20% is P-polarized light and about 80% is S-polarized light with respect to the incident surface of the second dichroic mirror 32.

[0041] The blue light emitted from the semiconductor laser 20 is diffused by the diffuser plate 61 and enters the second dichroic mirror 32. In the present embodiment, the separation ratio of the light at the second dichroic mirror 32 is adjusted by adjusting the polarization direction of the polarization of the light emitted from the semiconductor laser 20, but the separation ratio may be adjusted by installing a retardation plate between the semiconductor laser 20 and the diffuser plate 61.

[0042] The light incident on the second dichroic mirror 32 is split by transmitting or reflecting according to the spectroscopic characteristics shown in FIG. 2. The second dichroic mirror 32 has the characteristic of transmitting P-polarized light of semiconductor laser light near a wavelength of 455 nm with a high transmittance and reflecting S-polarized light with a high reflectance. Therefore, among the blue light with a wavelength range of 440 nm or more and 455 nm or less emitted from the semiconductor laser 20, the P-polarized light passes through the second dichroic mirror 32 and enters the condenser lens 64. On the other hand, among the blue light with a wavelength range of 440 nm or more and 455 nm or less emitted from the semiconductor laser 20, the S-polarized light is reflected by the second dichroic mirror 32 and enters the quarter-wave plate 34 corresponding to the first retardation plate.

[0043] The blue light of S polarization incident on the quarter-wave plate 34, which is the first retardation plate, is converted by the quarter-wave plate 34 into circularly polarized light containing approximately 50% each of the P polarization component and the S polarization component. The light transmitted through the quarter-wave plate 34 is incident on the first dichroic mirror 30.

[0044] The P-polarized light transmitted through the second dichroic mirror 32 is condensed by the condenser lens 64, which is a condensing element, to form a condensing spot near the reflector 38. At this time, the P-polarized light is converted into circularly polarized light by the quarter-wave plate 36 corresponding to the second retardation plate disposed between the condenser lens 64 and the reflector 38.

[0045] The blue light condensed by the condenser lens 64 and converted into circularly polarized light by the quarter-wave plate 36 is reflected by the reflector 38. The reflected light has its circular polarization phase reversed and is incident on the quarter-wave plate 36 again. The light incident on the quarter-wave plate 36 is converted from circularly polarized light into S-polarized light and is condensed again by the condenser lens 64.

[0046] The P-polarized blue light transmitted through the first dichroic mirror 30 is condensed by the first condenser lens group 62, which is a condensing element. The condensed light is superimposed on spot light having a diameter of 1 mm or more and 2 mm or less and a light intensity of 13.5% with respect to the peak intensity, and is incident on the first phosphor element 40. The diffuser plate 61 diffuses the light so that the diameter of the spot light becomes a desired diameter, reduces minute light intensity unevenness in the spot light caused by the two-dimensionally arranged semiconductor laser 20, and suppresses local temperature rise of the phosphor.

[0047] The first phosphor layer 41 irradiated with blue light emits green excitation light. The green light emitted by the first phosphor layer 41 is incident on the first condenser lens group 62 directly or after being reflected by the reflection layer 42.

[0048] The green light incident on the first condenser lens group 62 is condensed by the first condenser lens group 62, converted into substantially parallel light, and then incident on the first dichroic mirror 30.

[0049] The S-polarized light reflected by the first dichroic mirror 30 will be described. The S-polarized light reflected by the first dichroic mirror 30 is condensed by the second condenser lens group 63 which is a condensing element. The condensed light is superimposed on a spot light with a diameter of 1 mm or more and 2 mm or less and a light intensity of 13.5% with respect to the peak intensity, and is incident on the second phosphor element 46.

[0050] The second phosphor layer 47 irradiated with blue light emits yellow light. The yellow light emitted by the second phosphor layer 47 is directly or reflected by the reflection layer 48 and is incident on the second condenser lens group 63.

[0051] The yellow light incident on the second condenser lens group 63 is condensed by the second condenser lens group 63, converted into substantially parallel light, and then incident on the first dichroic mirror 30.

[0052] Next, the green light emitted by the first phosphor layer 41 and the yellow light emitted by the second phosphor layer 47, which are incident on the first dichroic mirror 30, will be described.

[0053] The green light emitted by the first phosphor layer 41 and incident on the first dichroic mirror 30 passes through the first dichroic mirror 30 according to the spectral characteristics of the first dichroic mirror 30 shown in FIG. 3.

[0054] The yellow light incident on the first dichroic mirror 30 is split by transmitting or reflecting according to the spectroscopic characteristics of the first dichroic mirror 30 shown in FIG. 3. Specifically, the red component on the long wavelength side (wavelength 585 nm or more) is reflected by the first dichroic mirror 30, and the green component on the short wavelength side (wavelength less than 585 nm) passes through the first dichroic mirror 30. Thereby, red light can be extracted from the yellow light.

[0055] The red light emitted from the second phosphor layer 47 and reflected by the first dichroic mirror 30 and the green light emitted by the first phosphor layer 41 and passing through the first dichroic mirror 30 pass through the quarter-wave plate 34 and are incident on the second dichroic mirror 32.

[0056] The red light and green light incident on the second dichroic mirror 32 pass through according to the characteristics of the second dichroic mirror 32 shown in FIG. 2. On the other hand, the blue light reflected by the reflector 38 and incident on the second dichroic mirror 32 is converted into S-polarized light by the quarter-wave plate 36, and thus is reflected according to the characteristics of the second dichroic mirror 32.

[0057] By the above operation, in the light source device 10 of the present embodiment, the S-polarized blue light reflected by the second dichroic mirror 32, the red light transmitted through the second dichroic mirror 32, and the green light transmitted through the second dichroic mirror 32 are combined to generate white light.

[0058] The white light composed of the fluorescent green light and red light and the blue light of the semiconductor laser 20 can obtain good white balance emission characteristics, and this emission spectrum characteristic can obtain monochromatic light with a desired chromaticity coordinate even when separated into three primary color lights of blue, green, and red by the optical system of the projection display device 225 (see FIG. 4).

[0059] The light source device 10 uses a quarter-wave plate 34 and a first dichroic mirror 30 to polarization-separate the light reflected by the second dichroic mirror 32, and excite two phosphor elements, namely a first phosphor element 40 and a second phosphor element 46, to generate green light and yellow light respectively. That is, the light source device 10 according to the present embodiment can suppress the radiation amount of the excitation light incident on the phosphor as compared with the case of using one phosphor element.

[0060] In addition, as is well known in general, when condensing excitation light on a phosphor, the phosphor generates heat as the energy density of the excitation light increases, and the light emission efficiency of the phosphor decreases. In the light source device 10 according to the present embodiment, the first phosphor layer 41 and the second phosphor layer 47 can generate white light with high light emission efficiency as compared with the case of using one phosphor element because the radiation amount of the incident excitation light is suppressed.

[0061] (Modification of the embodiment) In the present embodiment, a yellow phosphor that emits yellow light when excited by blue light is used as the second phosphor layer 47. However, as a modification of the present embodiment, the second phosphor layer 47 may use, for example, a red phosphor that emits red light when excited by blue light. In this case, for example, a Eu-activated nitrogen-based phosphor is used for the second phosphor layer 47, and the chemical composition is (Sr,Ca)AlSiN3.

[0062] Also, in FIG. 1, one solid light source unit 23 is used, but a plurality of solid light source units 23 may be combined with mirrors and used. Although the second dichroic mirror 32 has been described by taking as an example the characteristic of transmitting P-polarized blue light, reflecting S-polarized blue light, and transmitting green light and red light, it may have the characteristic of reflecting green light and red light. In this case, it is set so that about 80% of the laser light is the P polarization and about 20% is the S polarization component.

[0063] Also, the first dichroic mirror 30 was described by taking as an example the characteristic of transmitting P-polarized blue light, reflecting S-polarized blue light, transmitting green light, and reflecting red light. However, it may also have the characteristic of reflecting green light and transmitting red light. In this case, a yellow phosphor or a red phosphor is used for the first phosphor element 40, and a green phosphor is used for the second phosphor element 46.

[0064] [3. Configuration and Operation of Projection Display Device Equipped with Light Source Device According to Present Embodiment] Regarding the detailed configuration of the projection display device equipped with the light source device according to the present embodiment, it will be described below with reference to the drawings. FIG. 4 is a configuration diagram of a projection display device 225 equipped with the light source device 10 according to the present embodiment.

[0065] The projection display device 225 in the present embodiment includes a light source device 10, an image light forming unit 200, and a light guide unit 210.

[0066] The driving method of the image light forming unit 200 is a TN (Twisted Nematic) mode or a VA (Vertical Alignment) mode. The image light forming unit 200 uses an active matrix type transmissive liquid crystal panel in which thin film transistors are formed in a pixel region.

[0067] The image light forming unit 200 includes three liquid crystal panels 117, 118, and 119, and forms image light by the three liquid crystal panels 117, 118, and 119. The image light forming unit 200 further includes a color synthesis prism 123. The color synthesis prism 123 has a base material, a dichroic film that reflects red light, and a dichroic film that reflects blue light. The above two dichroic films are provided on the base material. The image light color-synthesized by the color synthesis prism 123 is projected through a projection lens 124.

[0068] The light guide unit 210 includes a first lens array plate 100, a second lens array plate 101, a polarization conversion optical element 102, a superimposing lens 103, a third dichroic mirror 104, and a fourth dichroic mirror 105. The light guide unit 210 includes a first reflection mirror 106, a second reflection mirror 107, a third reflection mirror 108, a first relay lens 109, a second relay lens 110, a first field lens 111, a second field lens 112, and a third field lens 113. The light guide unit 210 guides the light from the light source device 10 to the image light forming unit 200.

[0069] The first lens array plate 100 is disposed at a position where it receives the white light emitted from the light source device 10. The lens elements of the first lens array plate 100 have an aperture shape that is similar to those of the first liquid crystal panel 117, the second liquid crystal panel 118, and the third liquid crystal panel 119, which will be described later.

[0070] The second lens array plate 101 is disposed at a position where it receives the light emitted from the first lens array plate 100. The second lens array plate 101 is made of, for example, glass. The focal length of the lens elements of the second lens array plate 101 is disposed at a position where the first lens array plate 100 and the liquid crystal panels 117, 118, and 119 are substantially in a conjugate relationship.

[0071] The polarization conversion optical element 102 is disposed at a position where it receives the light emitted from the second lens array plate 101. The polarization conversion optical element 102 has a polarization splitting prism and a 1 / 2 retardation plate, and converts the light from the light source device 10 into light in one polarization direction (S polarization). The light from the polarization conversion optical element 102 is incident on the superimposing lens 103.

[0072] The superposition lens 103 is disposed at a position to receive the light from the polarization conversion optical element 102. The light from the polarization conversion optical element 102 is superposed on the liquid crystal panels 117, 118, and 119 by passing through the superposition lens 103. The white light emitted from the light source device 10 is used with the first lens array plate 100, the second lens array plate 101, and the superposition lens 103, so that the illuminance distribution on the first liquid crystal panel 117, the second liquid crystal panel 118, and the third liquid crystal panel 119 is made uniform.

[0073] The third dichroic mirror 104 is disposed at a position to receive the light transmitted through the superposition lens 103. The third dichroic mirror 104 has the property of reflecting light in the blue wavelength range and transmitting light in other wavelength ranges. The blue light reflected by the third dichroic mirror 104 enters the first reflection mirror 106.

[0074] The fourth dichroic mirror 105 is disposed at a position to receive the light transmitted through the third dichroic mirror 104. The fourth dichroic mirror 105 has the property of reflecting light in the green wavelength range and transmitting light in other wavelength ranges. The green light reflected by the fourth dichroic mirror 105 enters the first field lens 111.

[0075] The first relay lens 109 is disposed at a position to receive the light transmitted through the fourth dichroic mirror 105. The first relay lens 109 has the property of compensating for the loss of light in the red wavelength range due to the optical path length of the light in the red wavelength range being longer than the optical path lengths of the light in the blue and green wavelength ranges. Also, the light transmitted through the first relay lens 109 enters the second reflection mirror 107.

[0076] The first reflection mirror 106 is disposed at a position to receive the light reflected by the third dichroic mirror 104. The first reflection mirror 106 is a general total reflection mirror such as an aluminum-coated mirror. The light reflected by the first reflection mirror 106 enters the second field lens 112.

[0077] The second reflection mirror 107 is disposed at a position to receive the light that has passed through the first relay lens 109. Similar to the first reflection mirror 106, the second reflection mirror 107 is a general total reflection mirror such as, for example, an aluminum film deposition mirror. The light reflected by the second reflection mirror 107 enters the second relay lens 110.

[0078] The second relay lens 110 is disposed at a position to receive the light reflected by the second reflection mirror 107. Similar to the first relay lens 109, the second relay lens 110 has the characteristic of compensating for the loss of light in the red wavelength range.

[0079] The third reflection mirror 108 is disposed at a position to receive the light that has passed through the second relay lens 110. Similar to the first reflection mirror 106, the second reflection mirror 107 is a general total reflection mirror such as, for example, an aluminum film deposition mirror. The light reflected by the third reflection mirror 108 enters the third field lens 113.

[0080] The first field lens 111 is disposed at a position to receive the light reflected by the fourth dichroic mirror 105. The first field lens 111 has the characteristic of parallelizing the incident light. The light that has passed through the first field lens 111 enters the first incident-side polarizing plate 114 that constitutes the image light forming unit 200.

[0081] The second field lens 112 is disposed at a position to receive the light reflected by the first reflection mirror 106. Similar to the first field lens 111, the second field lens 112 has the characteristic of parallelizing the incident light. The light that has passed through the second field lens 112 enters the second incident-side polarizing plate 115 that constitutes the image light forming unit 200.

[0082] The third field lens 113 is disposed at a position to receive the light reflected by the third reflecting mirror 108. The third field lens 113 has the property of collimating the incident light in the same manner as the first field lens 111. The light transmitted through the third field lens 113 is incident on the third incident-side polarizing plate 116 that constitutes the image light forming unit 200.

[0083] Next, the configuration of the image light forming unit 200 will be described. The image light forming unit 200 includes a first incident-side polarizing plate 114, a second incident-side polarizing plate 115, a third incident-side polarizing plate 116, a first liquid crystal panel 117, a second liquid crystal panel 118, a third liquid crystal panel 119, a first exit-side polarizing plate 120, a second exit-side polarizing plate 121, and a third exit-side polarizing plate 122.

[0084] The first incident-side polarizing plate 114 is disposed at a position to receive the light transmitted through the first field lens 111 such that the polarization direction of the incident light is parallel to the transmission axis. The first incident-side polarizing plate 114 has the property of aligning the polarization direction of the passing light. The light transmitted through the first incident-side polarizing plate 114 is incident on the first liquid crystal panel 117.

[0085] The first liquid crystal panel 117 changes the polarization state of the incident light by controlling the voltage applied to the pixels according to the video signal. The light passed through the first liquid crystal panel 117 is incident on the first exit-side polarizing plate 120.

[0086] The first exit-side polarizing plate 120 is disposed at a position to receive the light passed through the first liquid crystal panel 117. Also, the first exit-side polarizing plate 120 is disposed such that its transmission axis is orthogonal to that of the first incident-side polarizing plate 114. By arranging it in this way, only the light whose polarization state has changed in the first liquid crystal panel 117 can pass through the first exit-side polarizing plate 120, and an image in the green wavelength range is formed. The light passed through the first exit-side polarizing plate 120 is incident on the color synthesis prism 123.

[0087] The second incident-side polarizing plate 115 is arranged at a position where it receives the light that has passed through the second field lens 112 such that the polarization direction of the incident light is parallel to the transmission axis. The second incident-side polarizing plate 115 has the property of aligning the polarization directions of the light passing therethrough, similar to the first incident-side polarizing plate 114. The light that has passed through the second incident-side polarizing plate 115 is incident on the second liquid crystal panel 118.

[0088] The second liquid crystal panel 118 changes the polarization state of the incident light by controlling the voltage applied to the pixels according to the video signal, similar to the first liquid crystal panel 117. The light that has passed through the second liquid crystal panel 118 is incident on the second exit-side polarizing plate 121.

[0089] The second exit-side polarizing plate 121 is arranged at a position where it receives the light that has passed through the second liquid crystal panel 118 such that the transmission axis is orthogonal to the second incident-side polarizing plate 115. Therefore, only the light whose polarization state has been changed by the second liquid crystal panel 118 can pass through the second exit-side polarizing plate 121, and an image in the blue wavelength range is formed. The light that has passed through the second exit-side polarizing plate 121 is incident on the color-combining prism 123.

[0090] The third incident-side polarizing plate 116 is arranged at a position where it receives the light that has passed through the third field lens 113 such that the polarization direction of the incident light is parallel to the transmission axis. The third incident-side polarizing plate 116 has the property of aligning the polarization directions of the light passing therethrough, similar to the first incident-side polarizing plate 114. The light that has passed through the third incident-side polarizing plate 116 is incident on the third liquid crystal panel 119.

[0091] The third liquid crystal panel 119 changes the polarization state of the incident light by controlling the voltage applied to the pixels according to the video signal, similar to the first liquid crystal panel 117. The light that has passed through the third liquid crystal panel 119 is incident on the third exit-side polarizing plate 122.

[0092] The third exit-side polarizing plate 122 is arranged at a position where it receives the light that has passed through the third liquid crystal panel 119 such that the third incident-side polarizing plate 116 and the transmission axis are orthogonal. Therefore, only the light whose polarization state has been changed by the third liquid crystal panel 119 can pass through the third exit-side polarizing plate 122, and an image in the red wavelength range is formed. The light that has passed through the third exit-side polarizing plate 122 is incident on the color-combining prism 123.

[0093] The color-combining prism 123 combines the light that has passed through the first exit-side polarizing plate 120, the light that has passed through the second exit-side polarizing plate 121, and the light that has passed through the third exit-side polarizing plate 122. The light that has passed through the second exit-side polarizing plate 121 and is incident on the color-combining prism 123 is incident on a dichroic film that reflects blue light (not shown). The dichroic film that reflects blue light is adjusted so as to reflect the incident blue light in the direction of the light that has passed through the first exit-side polarizing plate 120. On the other hand, the light that has passed through the third exit-side polarizing plate 122 and is incident on the color-combining prism 123 is incident on a dichroic film that reflects red light (not shown). The dichroic film that reflects red light is adjusted so as to reflect the incident red light in the direction of the light that has passed through the first exit-side polarizing plate 120.

[0094] The projection lens 124 is arranged at a position where it receives the light that has passed through the color-combining prism 123. The red light, green light, and blue light combined by the color-combining prism 123 are incident on the projection lens 124 as image light formed by the liquid crystal panel. The image light incident on the projection lens 124 is enlarged and projected onto a screen (not shown).

[0095] In the present embodiment, a transmissive liquid crystal panel is used as the image light forming unit 200, but a reflective liquid crystal panel may be used. By using a reflective liquid crystal panel, a smaller and higher-definition projection display device 225 can be configured.

[0096] Alternatively, the projection display device 225 may be configured using a 3-chip DLP method that uses three DMDs as the image light forming unit 200. By using a DMD for the image light forming unit 200, a projection display device 225 with high light resistance and heat resistance can be configured compared to the case of using liquid crystals. Furthermore, since three DMDs are used, good color reproduction can be achieved, and bright and high-definition projection image light can be obtained.

[0097] As described above, the projection display device 225 in the present embodiment includes a light source device 10. The light source device 10 includes a semiconductor laser 20, a second dichroic mirror 32, a quarter-wave plate 34, a first dichroic mirror 30, a first phosphor element 40, a second phosphor element 46, a quarter-wave plate 36, and a reflector 38. The semiconductor laser 20 outputs excitation light having a wavelength in the visible light region. The second dichroic mirror 32 is an optical separation element in which the cut-off wavelength is set so as to have a high reflection characteristic for S-polarized light in the wavelength range of the light output from the semiconductor laser 20 and a high transmission characteristic for P-polarized light, and separates the light from the semiconductor laser 20. The quarter-wave plate 34 is a first quarter-wave plate that adjusts the polarization of the incident light when one of the lights separated by the second dichroic mirror 32 is incident. The first dichroic mirror 30 has a cut-off wavelength set so as to have a high reflection characteristic for S-polarized light among the light emitted from the quarter-wave plate 34 and a high transmission characteristic for P-polarized light, and has a high transmission characteristic for green light to yellow light and a high reflection characteristic for red light. It is an optical separation and synthesis element. The first phosphor element 40 is a phosphor element irradiated with the light transmitted through the first dichroic mirror 30. The second phosphor element 46 is a phosphor element irradiated with the light reflected by the first dichroic mirror 30. The quarter-wave plate 36 is a second quarter-wave plate that adjusts the polarization of the other light among the lights separated by the second dichroic mirror 32. The reflector 38 is a reflecting element that guides the other light that has passed through the quarter-wave plate 36 to the second dichroic mirror 32 via the quarter-wave plate 36. As a result, compared with the case where one phosphor element is used, white light can be obtained with high efficiency by increasing the conversion efficiency of the phosphor. Therefore, a highly efficient projection display device 225 can be configured.

[0098] (Overview) The following aspects are disclosed in this specification.

[0099] The light source device (10) according to the first aspect includes a light source (semiconductor laser 20), a first optical separation element (first dichroic mirror 30), a first phosphor (first phosphor layer 41), and a second phosphor (second phosphor layer 47). The first separation element transmits light having a first polarization direction among the light from the light source and reflects light having a second polarization direction different from the first polarization direction. The first phosphor is irradiated with the light transmitted through the first optical separation element and emits light in a first wavelength range. The second phosphor is irradiated with the light reflected by the first optical separation element and emits light in a second wavelength range different from the first wavelength range. The first optical separation element has a property of transmitting one of the light in the first wavelength range and the light in the second wavelength range and reflecting the other.

[0100] According to the light source device (10) according to the first aspect, it is possible to generate light with high luminous efficiency as compared with the case where one phosphor element is used.

[0101] In the light source device (10) according to the second aspect, in the first aspect, the first optical separation element (first dichroic mirror 30) transmits or reflects according to the polarization direction of the incident light and the wavelength of the incident light.

[0102] The light source device (10) according to the third aspect further includes a second optical separation element (second dichroic mirror 32) in the first or second aspect. The second optical separation element transmits light having a first polarization direction among the light from the light source (semiconductor laser 20) and reflects light having a second polarization direction different from the first polarization direction. The light transmitted or reflected by the second optical separation element is incident on the first optical separation element (first dichroic mirror 30).

[0103] The light source device (10) according to the fourth aspect further includes a first retardation plate (quarter-wave retardation plate 34) in the third aspect. The first retardation plate converts the incident light into circularly polarized light. The light transmitted or reflected by the second optical separation element (second dichroic mirror 32) is incident on the first retardation plate and then incident on the first optical separation element (first dichroic mirror 30).

[0104] The light source device (10) according to the fifth aspect further includes, in the fourth aspect, a second retardation plate (quarter-wave retardation plate 34) and a reflection element (reflector 38). The second retardation plate converts incident light into circularly polarized light. The reflection element causes the light from the second retardation plate to be incident on the second retardation plate again. Of the light transmitted by the second light separation element (second dichroic mirror 32) and the light reflected by the second light separation element, one is incident on the first retardation plate (quarter-wave retardation plate 36), and the other is incident on the second retardation plate.

[0105] In the light source device (10) according to the sixth aspect, in the fifth aspect, the light transmitted and reflected by the first light separation element (first dichroic mirror 30) is incident on the second light separation element (second dichroic mirror 32).

[0106] In the light source device (10) according to the seventh aspect, in the sixth aspect, the second light separation element (second dichroic mirror 32) has a function of selecting transmission or reflection according to the polarization direction and wavelength of the incident light. The light in the first wavelength range and the light in the second wavelength range incident on the second light separation element (second dichroic mirror 32), and the light reflected by the reflection element (reflector 38) and incident on the second light separation element (second dichroic mirror 32) again are transmitted or reflected by the second light separation element and output to an image light forming unit that forms image light.

[0107] In the light source device (10) according to the eighth aspect, in the seventh aspect, the light transmitted or reflected by the second light separation element (second dichroic mirror 32) and output to the image light forming unit is white light.

[0108] In the light source device (10) according to the ninth aspect, in any one of the first to eighth aspects, the light source (semiconductor laser 20) is a light source that emits blue light.

[0109] In the light source device (10) according to the tenth aspect, in any one of the first to ninth aspects, the first polarization direction is P polarization, and the second polarization direction is S polarization.

[0110] In the light source device (10) according to the eleventh aspect, in the tenth aspect, the first light separation element (the first dichroic mirror 30) transmits P-polarized light having a wavelength of less than 585 nm and reflects P-polarized light having a wavelength of 585 nm or more. The first light separation element transmits S-polarized light having a wavelength of 470 nm or more and less than 585 nm and reflects S-polarized light having a wavelength of less than 470 nm or 585 nm or more.

[0111] In the light source device (10) according to the twelfth aspect, in any one of the first to eleventh aspects, the first phosphor (the first phosphor layer 41) is a phosphor that emits green light, and the second phosphor (the second phosphor layer 47) is a phosphor that emits yellow light.

[0112] In the light source device (10) according to the thirteenth aspect, in any one of the first to eleventh aspects, the first phosphor (the first phosphor layer 41) is a phosphor that emits green light, and the second phosphor (the second phosphor layer 47) is a phosphor that emits red light.

[0113] In the light source device (10) according to the fourteenth aspect, in the twelfth aspect, the light irradiated from the second phosphor (the second phosphor layer 47) that emits yellow light is separated into red light and green light by the first light separation element (the first dichroic mirror 30). The first light separation element transmits one of the red light and the green light and reflects the other.

[0114] In the light source device (10) according to the 15th aspect, in any one of the 2nd to 14th aspects, a second light separation element (second dichroic mirror 32) is further provided. The second light separation element transmits light having a first polarization direction among the light from the light source (semiconductor laser 20) and reflects light having a second polarization direction different from the first polarization direction. The first light separation element (first dichroic mirror 30) and the second light separation element are dichroic mirrors.

[0115] In the light source device (10) according to the 16th aspect, in the 5th or 6th aspect, the first retardation plate (quarter-wave retardation plate 36) and the second retardation plate (quarter-wave retardation plate 34) are quarter-wave plates.

[0116] The projection display device (225) according to the 17th aspect includes the light source device (10) according to any one of the 1st to 16th aspects.

[0117] According to the projection display device (225) according to the 17th aspect, when one phosphor element is used, high-efficiency light can be obtained by increasing the conversion efficiency of the phosphor. Therefore, a highly efficient projection display device can be configured.

[0118] The projection display device (225) according to the 18th aspect further includes an image light forming unit (200) in the 17th aspect. The image light forming unit (200) forms image light using the light from the light source device (10).

[0119] The projection display device (225) according to the 19th aspect further includes a light guide unit (210) in the 18th aspect. The light guide unit (210) guides the light from the light source device (10) to the image light forming unit (200).

Description of Reference Numerals

[0120] 10 Light source device 20 Semiconductor laser (light source) 21 Heat sink 22 Collimating lens 23 Solid light source unit 24 Heat sink 30 First dichroic mirror (first optical beam splitter element) 32 Second dichroic mirror (second optical beam splitter element) 34 Quarter-wave plate (second quarter-wave plate) 36 Quarter-wave plate (first quarter-wave plate) 38 Reflector (reflective element) 40 First phosphor element 41 First phosphor layer (first phosphor) 42, 48 Reflective layer 43, 49 Heat dissipation plate 45, 51 Heat sink 46 Second phosphor element 47 Second phosphor layer (second phosphor) 61 Diffuser plate 62 First condenser lens group 63 Second condenser lens group 64 Condenser lens 100 First lens array plate 101 Second lens array plate 102 Polarization conversion optical element 103 Superposition lens 104 Third dichroic mirror 105 Fourth dichroic mirror 106 First reflecting mirror 107 Second reflecting mirror 108 Third reflecting mirror 109 First relay lens 110 Second relay lens 111 First field lens 112 Second field lens 113 Third field lens 114 First incident-side polarizer 115 Second incident-side polarizer 116 Third incident-side polarizer 117 First liquid crystal panel 118 Second liquid crystal panel 119 Third liquid crystal panel 120 First emission-side polarizing plate 121 Second emission-side polarizing plate 122 Third emission-side polarizing plate 123 Color-combining prism 124 Projection lens 200 Image light forming unit 210 Light guide unit 225 Projection display device

Claims

1. A light source, a first optical separation element that transmits light having a first polarization direction among the light from the light source and reflects light having a second polarization direction different from the first polarization direction, a first phosphor that is irradiated with the light transmitted through the first optical separation element and emits light in a first wavelength range, a second phosphor that is irradiated with the light reflected by the first optical separation element and emits light in a second wavelength range different from the first wavelength range, a second optical separation element that transmits light having the first polarization direction among the light from the light source and reflects light having the second polarization direction, a condenser lens into which the light transmitted through the second optical separation element is incident, a first retardation plate into which the light condensed by the condenser lens is incident, a reflection element that causes the light from the first retardation plate to be incident on the first retardation plate again, a second retardation plate into which the light reflected by the second optical separation element is incident, and the first optical separation element has a property of transmitting light in the first wavelength range and reflecting light in the second wavelength range, the light reflected by the second optical separation element passes through the second retardation plate and is incident on the first optical separation element, the light in the first wavelength range and the light in the second wavelength range that have passed through or been reflected by the first optical separation element pass through the second retardation plate and pass through the second optical separation element, the light that has passed through the first retardation plate again from the reflection element is reflected by the second optical separation element, A light source device.

2. The first optical separation element transmits or reflects according to the polarization direction of the incident light and the wavelength of the incident light, The light source device according to Claim 1.

3. The second retardation plate has a property of converting the incident light into circularly polarized light, The light source device according to Claim 1.

4. The second optical separation element has a function of selecting transmission or reflection according to the polarization direction of the incident light and the wavelength of the incident light, the light in the first wavelength range and the light in the second wavelength range pass through the second optical separation element, are reflected by the reflection element, and the light that is incident on the second optical separation element again is reflected by the second optical separation element and output to an image light forming unit that forms image light, The light source device according to Claim 1.

5. The light transmitted or reflected by the second optical separation element and output to the image light forming unit is white light, The light source device according to Claim 4.

6. The light source is a light source that emits blue light. The light source device according to any one of claims 1 to 5.

7. The first polarization direction is P polarization, The second polarization direction is S polarization, The light source device according to any one of claims 1 to 6.

8. The first light separation element Transmits light with P polarization having a wavelength of less than 585 nm, Reflects light with P polarization having a wavelength of 585 nm or more, Transmits light with S polarization having a wavelength of 470 nm or more and less than 585 nm, Reflects light with S polarization having a wavelength of less than 470 nm or 585 nm or more, The light source device according to claim 7.

9. The first phosphor is a phosphor that emits green light, The second phosphor is a phosphor that emits yellow light, The light source device according to any one of claims 1 to 8.

10. The first phosphor is a phosphor that emits green light, The second phosphor is a phosphor that emits red light, The light source device according to any one of claims 1 to 8.

11. The light emitted from the second phosphor that emits yellow light is separated into red light and green light by the first light separation element, The first light separation element transmits one of red light and green light and reflects the other. The light source device according to claim 9.

12. The first light separation element and the second light separation element are dichroic mirrors. The light source device according to any one of claims 1 to 11.

13. The first retardation plate and the second retardation plate are quarter-wave plates. The light source device according to claim 1.

14. Comprising the light source device according to any one of claims 1 to 13, Projection display device.

15. Further comprising an image light forming unit that forms image light using the light from the light source device, The projection display device according to claim 14.

16. Further comprising a light guide unit that guides the light from the light source device to the image light forming unit, The projection display device according to claim 15.

Images