Projector light source

Abstract

This invention provides a light source for projectors that can broaden the color gamut of projected images and improve color reproduction. [Solution] The spectroscopic element 4 spectrally separates the red laser light R, green laser light G, and blue laser light B emitted from the red laser light source 1R, green laser light source 1G, and blue laser light source 1B, respectively, and emits them in different directions. The diffusion member 62 is formed in one region of the base member 61 and diffuses and reflects the incident red laser light R and green laser light G. The fluorescent / diffusing member 63 is formed in another region of the base member 61 and includes a phosphor that is excited by a portion of the incident blue laser light B to emit yellow light Y, and a diffusion material that diffuses and reflects the other portion of the blue laser light B. The focusing element 5 mixes the red laser light R and green laser light G reflected by the diffusion member 62, the yellow light Y emitted from the fluorescent / diffusing member 63, and the blue laser light B reflected by the fluorescent / diffusing member 63 and emits it as white light W.

Description

Technical Field

[0001] The present invention relates to a light source for a projector.

Background Art

[0002] As described in Patent Document 1, a projector may use a light source for a projector that obtains white light by combining blue laser light emitted from a blue laser light source and yellow excitation light obtained by irradiating a phosphor with the blue laser light.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] Since the conventional light source for a projector described in Patent Document 1 includes only a blue laser light source, the color gamut that can be represented by the projected image projected by the projector is narrow, and the color reproducibility is not so good. An object of the present invention is to provide a light source for a projector that can widen the color gamut of the projected image and improve the color reproducibility.

Means for Solving the Problems

[0005] The present invention comprises a laser light source including a red laser light source, a green laser light source, and a blue laser light source; a spectroscopic element that spectrally separates the red laser light, green laser light, and blue laser light emitted from the red laser light source, the green laser light source, and the blue laser light source, respectively, and emits them in different directions; a base member formed of a reflective material; a diffusion member formed in one region of the base member, into which the red laser light and the green laser light are incident and which diffuses the red laser light and the green laser light; and a diffusion member formed in another region of the base member, into which the blue laser light is incident and which diffuses the blue laser A light source for a projector is provided, comprising a fluorescent-diffusing member comprising a phosphor that is excited by a portion of the light and emits yellow light, and a diffusing material that diffuses the other portion of the blue laser light, and a focusing element that focuses the red laser light and the green laser light emitted from the spectroscopic element onto the diffusing member, focuses the blue laser light emitted from the spectroscopic element onto the fluorescent-diffusing member, and mixes the red laser light and the green laser light reflected by the diffusing member with the yellow light emitted from the fluorescent-diffusing member and the blue laser light reflected by the fluorescent-diffusing member to emit white light. [Effects of the Invention]

[0006] According to the present invention, the light source for projectors can broaden the color gamut of the projected image and improve color reproduction. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 shows a light source for a projector according to the first embodiment. [Figure 2] Figure 2 is a plan view showing a preferred configuration example of the optical components included in the projector light source according to the first embodiment. [Figure 3] Figure 3 shows a preferred configuration of the optical component shown in Figure 2. [Figure 4] Figure 4 shows a light source for a projector according to the second embodiment. [Figure 5]Figure 5 is an enlarged view of the optical component included in the projector light source according to the second embodiment. [Figure 6] Figure 6 is a characteristic diagram showing the spectral characteristics of the wavelength separation layer of the optical component shown in Figure 5. [Modes for carrying out the invention]

[0008] The projector light sources according to each embodiment will be described below with reference to the attached drawings. The projector light source 100 according to the first embodiment will be described using Figures 1 to 3, and the projector light source 200 according to the second embodiment will be described using Figures 4 to 6.

[0009] <First Embodiment> As shown in Figure 1, the projector light source 100 comprises a laser light source 1, a collimating lens 2, a polarizer 3, a spectroscopic element 4, a light-gathering element 5, and an optical component 6.

[0010] In Figure 1, the laser light source 1 includes a red laser light source 1R, a green laser light source 1G, and a blue laser light source 1B. The red laser light source 1R, green laser light source 1G, and blue laser light source 1B are composed of semiconductor lasers (laser diodes). The red laser light R, green laser light G, and blue laser light B emitted from the red laser light source 1R, green laser light source 1G, and blue laser light source 1B, respectively, are incident on the collimating lens 2. The red laser light R, green laser light G, and blue laser light B are shown as straight lines, dashed lines, and dotted lines, respectively.

[0011] The collimating lens 2 converts the red laser light R, green laser light G, and blue laser light B into collimated light. While the inclusion of the collimating lens 2 is not mandatory, it is preferable.

[0012] The collimated light emitted from the collimating lens 2 is white light W, and the white light W is incident on the polarizer 3. As an example, the polarizer 3 is a wire grid polarizer. The polarizer 3 is positioned at a 45-degree angle with respect to the direction of propagation of the white light W. The polarizer 3 may be provided on a glass substrate, which is a base member. The polarizer 3 reflects the first polarization of the two polarizations contained in the collimated light and transmits the second polarization. Here, the first polarization is denoted as S polarization and the second polarization as P polarization.

[0013] The S-polarized light reflected by polarizer 3 is bent at a 90-degree angle to the direction of propagation of the white light W and enters the spectroscopic element 4. The white light W reflected by polarizer 3 and entering the spectroscopic element 4 is almost entirely S-polarized. While the polarizer 3 is not essential, its inclusion is preferable.

[0014] The spectroscopic element 4 may be a diffraction grating or a prism. The spectroscopic element 4 spectrally separates white light W into red laser light R, green laser light G, and blue laser light B, and emits them in different directions. The red laser light R, green laser light G, and blue laser light B are focused by the focusing element 5 and incident on different positions on the optical member 6. The focusing element 5 may be a cylindrical lens or a metalens.

[0015] The optical component 6 comprises a base member 61 formed of a reflective material such as aluminum, and a diffusion member 62 and a fluorescent / diffusing member 63 provided on the base member 61. The diffusion member 62 and the fluorescent / diffusing member 63 are provided at different positions in the planar direction on the base member 61. That is, the diffusion member 62 is formed in one region of the base member 61, and the fluorescent / diffusing member 63 is formed in a different region of the base member 61. Red laser light R and green laser light G are incident on the diffusion member 62. The diffusion member 62 is composed of a diffusion material that diffuses the red laser light R and green laser light G.

[0016] Blue laser light B is incident on the fluorescence / diffusion member 63. The fluorescence / diffusion member 63 includes a phosphor that is excited by a part of the incident blue laser light B and emits yellow light Y, and a diffusion material that diffuses the blue laser light and the yellow light Y. The yellow light Y is indicated by a dotted line.

[0017] The condensing element 5 condenses the red laser light R and the green laser light G emitted from the spectroscopic element 4 onto the diffusion member 62. The condensing element 5 condenses the blue laser light B emitted from the spectroscopic element 4 onto the fluorescence / diffusion member 63. The condensing element 5 mixes the red laser light R and the green laser light G reflected by the diffusion member 62, the yellow light Y emitted from the fluorescence / diffusion member 63, and the blue laser light B reflected by the fluorescence / diffusion member 63, and emits them as white light W.

[0018] The red laser light R, the green laser light G, and the blue laser light B are diffused and reflected by the optical member 6, so that a part of the S-polarized light is converted into P-polarized light and emitted. Therefore, the white light W emitted from the condensing element 5 includes P-polarized light and S-polarized light. A part of the white light W emitted from the condensing element 5 is incident on the polarizer 3. The P-polarized light included in the white light W incident on the polarizer 3 passes through the polarizer 3 and is emitted, and the S-polarized light included in the white light W is reflected by the polarizer 3.

[0019] As described above, the projector light source 100 includes not only the blue laser light source 1B but also the red laser light source 1R and the green laser light source 1G. Therefore, according to the projector light source 100, the color gamut of the projected image can be widened and the color reproducibility can be improved. Since the projector light source 100 includes the diffusion member 62 and the fluorescence / diffusion member 63, it also has a secondary effect of reducing speckle noise in a spot shape.

[0020] Figure 2 shows a preferred configuration example of the optical member 6. The optical member 6 shown in Figure 2 is formed in a circular shape. The optical member 6 includes a circular base member 61, and a diffusion member 62 and a fluorescence / diffusion member 63 are provided on the common base member 61. The diffusion member 62 and the fluorescence / diffusion member 63 are formed circumferentially at different positions in the radial direction from the center of the base member 61. The diffusion member 62 is arranged on the inner peripheral side, and the fluorescence / diffusion member 63 is arranged on the outer peripheral side.

[0021] The optical member 6 shown in Figure 2 is rotated by a rotation mechanism (not shown). Therefore, since the positions of the red laser light R and the green laser light G irradiated on the diffusion member 62 and the position of the blue laser light B irradiated on the fluorescence / diffusion member 63 are constantly changing, the lifetimes of the diffusion member 62 and the fluorescence / diffusion member 63, particularly the lifetime of the phosphor contained in the fluorescence / diffusion member 63, can be extended.

[0022] The size of the condensing point of the red laser light R and the green laser light G irradiated on the diffusion member 62 and the size of the condensing point of the blue laser light B irradiated on the fluorescence / diffusion member 63 are adjusted to an optimal size by the condensing element 5. In particular, by setting the size of the condensing point of the blue laser light B to an optimal size, the conversion efficiency of the phosphor into yellow light Y can be maximized.

[0023] As shown in Figure 3, the optical member 6 has the characteristic that the thermal resistance in the thickness direction varies according to the distance from the center. On the other hand, when a part of the blue laser light B is converted into light with a low-energy wavelength, extra energy becomes heat and it tends to become high temperature. Therefore, it is preferable to provide the fluorescence / diffusion member 63 in the region with the smallest thermal resistance in the radial direction of the optical member 6. If the thermal resistance is small, it is easy to transfer the heat generated by the irradiation of the blue laser light B to the surroundings, and the state of becoming high temperature can be made for a short time. Therefore, the lifetime of the phosphor can be extended.

[0024] The projector light source 100 described above has a configuration different from the light source including a red laser light source, a green laser light source, and a blue laser light source described in Patent Document 2.

[0025] <Second Embodiment> As shown in Figure 4, the projector light source 200 comprises a laser light source 1, a polarizer 3, a light-gathering element 5, and an optical component 7. Components substantially identical to those in the projector light source 100 shown in Figure 1 are given the same reference numerals, and their descriptions are omitted.

[0026] In Figure 4, the polarizer 3 reflects the first polarization contained in the red laser light R, green laser light G, and blue laser light B emitted from the red laser light source 1R, green laser light source 1G, and blue laser light source 1B, respectively, and transmits the second polarization. Here again, the first polarization is S polarization and the second polarization is P polarization. Although the polarizer 3 is not essential, it is preferable to include it.

[0027] The light-gathering element 5 focuses the red laser light R, green laser light G, and blue laser light B reflected by the polarizer 3 onto the optical member 7. As shown in the enlarged view of the optical member 7 in Figure 5, the optical member 7 comprises a diffusion layer 72, a wavelength separation layer 73, and a phosphor layer 74 in the thickness direction. The diffusion layer 72, wavelength separation layer 73, and phosphor layer 74 are formed in this order on a base member 71 which is made of a reflective material such as aluminum.

[0028] The diffusion layer 72 is composed of a diffusing material that diffuses red laser light R and green laser light G. The wavelength separation layer 73, which reflects the red laser light R and green laser light G, transmits a portion of the blue laser light B and reflects the other portion. The phosphor layer 74 is excited by the blue laser light B that has passed through the wavelength separation layer 73 and emits yellow light Y. The wavelength separation layer 73 transmits the yellow light Y and allows it to enter the diffusion layer 72. The diffusion layer 72 diffuses the blue laser light B that has been reflected by the wavelength separation layer 73 and entered the diffusion layer 72, as well as the yellow light Y that has entered the diffusion layer 72.

[0029] Figure 6 shows the spectral characteristics of the wavelength separation layer 73. As shown in Figure 6, the wavelength separation layer 73 has different reflectances for each wavelength. The wavelength separation layer 73 has a reflectance of 50% around 450 nm, which corresponds to blue light. The wavelength separation layer 73 has a high reflectance at wavelengths of 500 nm to 550 nm, which corresponds to green light. The wavelength separation layer 73 has an extremely low reflectance at wavelengths of 560 to 570 nm, which corresponds to yellow light. The wavelength separation layer 73 has a high reflectance around 650 nm, which corresponds to red light.

[0030] Returning to Figure 4, the focusing element 5 mixes the red laser light R, green laser light G, blue laser light B, and yellow light Y emitted from the optical element 7 and emits white light W. Similar to the projector light source 100, the white light W emitted from the focusing element 5 contains a lot of P-polarized light and a small amount of S-polarized light. A portion of the white light W emitted from the focusing element 5 is incident on the polarizer 3. The P-polarized light contained in the white light W incident on the polarizer 3 is transmitted through the polarizer 3 and emitted, while the S-polarized light contained in the white light W is reflected by the polarizer 3.

[0031] As described above, the projector light source 200 includes not only a blue laser light source 1B, but also a red laser light source 1R and a green laser light source 1G. Therefore, the projector light source 200 can broaden the color gamut of the projected image and improve color reproduction. The projector light source 200 also has the secondary effect of reducing speckle noise because it is equipped with a diffusion layer 72.

[0032] The projector light source 200 described above has a different configuration from the light source described in Patent Document 2, which includes a red laser light source, a green laser light source, and a blue laser light source.

[0033] The present invention is not limited to the first or second embodiments described above, and can be modified in various ways without departing from the spirit of the invention. In the first embodiment, red laser light R, green laser light G, and blue laser light B are mixed in a collimating lens 2 to form white light W, which is then incident on the polarizer 3. In the second embodiment, red laser light R, green laser light G, and blue laser light B are directly incident on the polarizer 3. Regarding the configuration for inducing light on the polarizer 3, the configurations of the first and second embodiments may be reversed. That is, in the first embodiment, red laser light R, green laser light G, and blue laser light B may be directly incident on the polarizer 3. In the second embodiment, red laser light R, green laser light G, and blue laser light B may be converted into white light W and then incident on the polarizer 3. [Explanation of Symbols]

[0034] 1. Laser light source 1B Blue Laser Light Source 1G Green Laser Light Source 1R Red Laser Light Source 2. Collimating lenses 3 Polarizer 4 Spectroscopic elements 5. Light-gathering element 6,7 Optical components 61,71 Base members 62 Diffusion member 63 Fluorescent and Diffusing Materials 72 Diffusion layer 73 Wavelength separation layer 74 Phosphor layer 100,200 Projector Light Sources

Claims

1. Laser light sources including red laser light sources, green laser light sources, and blue laser light sources, A spectroscopic element that spectrally separates the red laser light, green laser light, and blue laser light emitted from the red laser light source, the green laser light source, and the blue laser light source, respectively, and emits them in different directions from each other. A base member formed of a reflective material, A diffusion member is formed in one region of the base member and includes a diffusion material that is incident on the red laser light and the green laser light and diffuses the red laser light and the green laser light, A fluorescent / diffusing member comprising a phosphor formed in a separate region of the base member, which is incident on the blue laser light and excited by a portion of the blue laser light to emit yellow light, and a diffusing material that diffuses the other portion of the blue laser light, A focusing element that focuses the red laser light and the green laser light emitted from the spectroscopic element onto the diffusing member, focuses the blue laser light emitted from the spectroscopic element onto the fluorescent / diffusing member, mixes the red laser light and the green laser light reflected by the diffusing member with the yellow light emitted from the fluorescent / diffusing member and the blue laser light reflected by the fluorescent / diffusing member, and emits white light. A projector light source equipped with the following features.

2. A collimating lens that converts the red laser light, the green laser light, and the blue laser light emitted from the red laser light source, the green laser light source, and the blue laser light source, respectively, into collimated light, A polarizer that causes the first polarization of the two polarizations contained in the collimated light to be incident on the spectroscopic element, The projector light source according to claim 1, further comprising:

3. The optical member comprises the aforementioned diffusion member and the aforementioned fluorescence-diffusion member, which are provided on a common base member. The diffusing member and the fluorescent / diffusing member are formed circumferentially at different radial positions from the center of the optical member. A light source for a projector according to claim 1 or 2.

4. The light source for a projector according to claim 3, wherein the fluorescent / diffusing member is provided in the region of the optical member where the radial thermal resistance is smallest.

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