Image Projection Device

Abstract

To provide an image projection device which can suppress color unevenness generated in a miniaturized light source device.SOLUTION: An image projection device comprises: a first light source which emits first excitation light in a specific wavelength; a second light source which emits second excitation light in a specific wavelength; a first wavelength conversion element which converts the first excitation light into light in a different prescribed wavelength and has a planar shape; and a second wavelength conversion element which converts the second excitation light into light in a prescribed wavelength different from that by the first wavelength conversion element and has the planar shape. The first wavelength conversion element and the second wavelength conversion element are arranged at positions where the surfaces thereof vertically intersect each other. The optical path length of the light emitted from the first wavelength conversion element and the optical path length of the light emitted from the second wavelength conversion element are equal to each other. At least one of the optical axis of the first excitation light and the optical axis of the second excitation light is arranged on the outside of the same plane as the surface formed by the optical axis of the light emitted from the first wavelength conversion element and the optical axis of the light emitted from the second wavelength conversion element.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an image projection device. [Background technology]

[0002] Light source devices that use LD light sources have the technology to emit three colors of light using multiple LD light sources and phosphors. If a light source device that emits three colors of light uses a transmissive phosphor, the light conversion efficiency of the phosphor is low, resulting in low projector output. For this reason, light source devices that emit three colors of light generally use a reflective phosphor.

[0003] Furthermore, Patent Document 1 discloses a technique for uniforming the fluorescent light path of fluorescence emitted by a phosphor in order to maintain the phosphor's luminous efficiency at an optimum state. Furthermore, Patent Document 2 discloses a configuration for uniforming the fluorescent light path of fluorescence emitted by a phosphor in order to maintain a good color balance between red light and blue light, regardless of variations in the emission luminance of the excitation light source and variations in luminance due to the lifespan of the excitation light source. Summary of the Invention [Problem to be solved by the invention]

[0004] However, light source devices using reflective phosphors often have a symmetrical configuration to ensure that the fluorescent light path lengths of each color of light are equal, which can make cooling the LD light source difficult or require additional optical elements to accommodate cooling, resulting in larger size. Therefore, in compact light source devices, it is difficult to equalize the lengths of multiple fluorescent light paths, resulting in noticeable color unevenness. Furthermore, the technology described in Patent Document 1 makes it difficult to equalize the fluorescent light paths in optical systems using reflective phosphors with high conversion efficiency. Furthermore, the technology described in Patent Document 2 makes it difficult to equalize the fluorescent light paths in optical systems using multiple light sources to increase output.

[0005] The present invention has been made in view of the above, and has an object to provide an image projection device that can suppress color unevenness that occurs in a compact light source device. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the object, the present invention provides a wavelength conversion element including a first light source that emits first excitation light of a specific wavelength, a second light source that emits second excitation light of a specific wavelength, a planar first wavelength conversion element that converts the first excitation light to a different predetermined wavelength, and a planar second wavelength conversion element that converts the second excitation light to a different predetermined wavelength from that of the first wavelength conversion element. The first wavelength conversion element and the second wavelength conversion element are arranged at positions independent of each other. The first wavelength conversion element and the second wavelength conversion element are arranged at a position where their surfaces intersect perpendicularly. The optical path length of the light emitted from the first wavelength conversion element and the optical path length of the light emitted from the second wavelength conversion element are equal. At least one of the optical axis of the first excitation light and the optical axis of the second excitation light is arranged outside the plane formed by the optical axis of the light emitted from the first wavelength conversion element and the optical axis of the light emitted from the second wavelength conversion element. [Effects of the Invention]

[0007] The present invention provides an effect of suppressing color unevenness that occurs in a compact light source device. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of an image projection device according to this embodiment. [Figure 2] FIG. 2 is a diagram showing an example of the configuration of a light source device included in the image projection device according to this embodiment. [Figure 3] FIG. 3 is a diagram illustrating an example of a specific configuration of the light source device included in the image projection device according to the present embodiment. [Figure 4]FIG. 4 is a diagram illustrating an example of the configuration of the light source device according to the first embodiment. [Figure 5] FIG. 5 is a diagram illustrating an example of the configuration of the light source device according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an image projection device will be described in detail below with reference to the accompanying drawings.

[0010] Fig. 1 is a diagram showing an example of the configuration of an image projection device according to this embodiment. As shown in Fig. 1, the image projection device according to this embodiment includes a light source device 1, an image display element 2, an illumination optical system 3, a projection optical system 4, etc.

[0011] The image display element 2 is an example of an image display element that forms an image. The illumination optical system 3 is an example of an illumination optical system that guides light emitted from the light source device 1 to the image display element 2. The projection optical system 4 is an example of a projection optical system that enlarges the image formed on the image display element 2 and projects it onto a display unit such as a screen.

[0012] 2 is a diagram showing an example of the configuration of a light source device included in an image projection device according to this embodiment. Light source device 1 is an example of a light source device that emits (emits) light of three colors, and is a compact light source device that uses two reflective phosphors with high light conversion efficiency, making the optical path lengths of the light emitted from the two phosphors equal.

[0013] 1, the light source device 1 is a light source device that uses three laser light sources 101 to 103. The first laser light source 101 emits blue excitation light, which is reflected by a dichroic mirror 104 and guided directly to a light tunnel LT.

[0014] The second laser light source 102 (an example of a first light source) emits blue excitation light (an example of first excitation light of a specific wavelength), which is reflected by a dichroic mirror 105 and irradiated onto a phosphor (red) 106. The red phosphor 106 (an example of a first wavelength conversion element) is a planar wavelength conversion element that converts the blue excitation light into red light (an example of light of a predetermined wavelength) which has a different wavelength from the blue excitation light, and guides the red light to the light tunnel LT.

[0015] The third laser light source 103 (an example of a second light source) emits blue excitation light (an example of second excitation light of a specific wavelength), which is reflected by a dichroic mirror 107 and irradiated onto a phosphor (green) 108. The green phosphor 108 (an example of a second wavelength conversion element) is a planar wavelength conversion element that converts the light into green light (an example of light of a predetermined wavelength) which has a different wavelength from that of the phosphor 106, and reflects the green light off a dichroic mirror 105 and guides it to a light tunnel LT.

[0016] In the light source device 1 having this configuration, the lengths (optical path lengths) of the light (fluorescence) converted by the phosphors 106 and 108 to the light tunnel LT (hereinafter referred to as the fluorescent light path) are equal. That is, the optical path length of the red light emitted from the phosphor 106 is equal to the optical path length of the green light emitted from the phosphor 108. The phosphors 106 and 108 are disposed in positions independent of each other, and are disposed in a position where their surfaces intersect perpendicularly. The dichroic mirror 105 may be configured so that the upper and lower portions transmit and reflect different wavelength ranges. For example, the dichroic mirror 105 may have a red reflective coating and a blue reflective coating in the upper portion and only a blue reflective coating in the lower portion, thereby changing the wavelength range. The dichroic mirror 105 transmits excitation light emitted from the laser light source 103 (light source) in the upper portion, converts the excitation light into green fluorescence by the phosphor 108, and reflects the green fluorescence. Furthermore, the dichroic mirror 105 reflects the excitation light emitted from the laser light source 102 (light source) at its bottom, converts it into red fluorescence by the phosphor 106, and transmits the red fluorescence. This enables the light source device 1 to guide three colors of light to the illumination optical system 3. The dichroic mirror 107 has a configuration in which there is no mirror in the optical path that transmits the light.

[0017] FIG. 3 is a diagram illustrating an example of a specific configuration of a light source device included in an image projection device according to this embodiment. As shown in FIG. 3, a three-dimensional configuration for miniaturizing the light source device 1 involves arranging the optical axis of the excitation light emitted from at least one of the laser light sources 102 and 103 (e.g., laser light source 102) outside the plane formed by the optical axes of the two fluorescent lights (red and green) emitted (reflected) from the two phosphors 106 and 108. This configuration allows for a single dichroic mirror to guide the fluorescent light to the illumination system, reducing the number of optical components, compared to a configuration in which the optical axis of the excitation light emitted from the laser light source 102 is arranged on the plane formed by the optical axes of the two fluorescent lights emitted from the two phosphors 106 and 108. As a result, a light source device 1 can be realized that is capable of emitting three colors of light, has high output, is free from color unevenness, and is compact. At this time, any misalignment of the laser light sources 102 and 103 is corrected by optical elements that guide the laser light sources 102 and 103 to the phosphors 106 and 108 .

[0018] As described above, in the image projection device according to the present embodiment, the optical axis of the excitation light emitted from at least one of the laser light sources 102 and 103 is arranged outside the plane formed by the optical axes of the fluorescence, which is the two lights emitted from the two phosphors 106 and 108. This allows for the use of only one dichroic mirror for guiding the fluorescence to the illumination system, compared to a configuration in which the optical axis of the excitation light emitted from the laser light source 102 is arranged on the plane formed by the optical axes of the two fluorescence emitted from the two phosphors 106 and 108. This reduces the number of optical components. As a result, a light source device 1 can be realized that has high output, is free from color unevenness, is compact, and is capable of emitting light of three colors.

[0019] Example 1 In this embodiment, the axis of the first rotating body on which the first wavelength conversion element is arranged is arranged on the same side as the second wavelength conversion element from the position where the excitation light is incident, and the axis of the second rotating body on which the second wavelength conversion element is arranged is arranged on the opposite side from the light source of the excitation light from the position where the excitation light is incident.

[0020] 4 is a diagram for explaining an example of the configuration of the light source device according to Example 1. In this example, the phosphor 106 is a phosphor layer disposed on a rotating body 401 (an example of a first rotating body). In addition, in this example, the phosphor 108 is a phosphor layer disposed on a rotating body 402 (an example of a second rotating body).

[0021] The axis (rotation axis) 403 of the rotating body on which the phosphor 106 is arranged is disposed on the same side as the phosphor 108, relative to the position where the blue excitation light is incident from the laser light source 102. The axis (rotation axis) 404 of the rotating body on which the phosphor 108 is arranged is disposed on the opposite side to the laser light source 103 that emits the blue excitation light, relative to the position where the blue excitation light is incident from the laser light source 103. As a result, even if the output of the light source device 1 increases and the sizes of the phosphors 106 and 108 increase, the increase in size of the light source device 1 can be accommodated, and the increase in size of the phosphors 106 and 108 can be suppressed.

[0022] Example 2 This embodiment is an example in which the plane formed by the axis of the first rotating body on which the first wavelength conversion element is arranged and the axis of the second rotating body on which the second wavelength conversion element is arranged is parallel to the plane formed by the optical axis of the light emitted from the first wavelength conversion element and the optical axis of the light emitted from the second wavelength conversion element.

[0023] Fig. 5 is a diagram for explaining an example of the configuration of a light source device according to Example 2. In this example, when phosphor 106 is arranged on rotating body 401 and phosphor 108 is arranged on rotating body 402, as shown in Fig. 5, a plane formed by rotation axis 403 of rotating body 401 and rotation axis 404 of rotating body 402 is arranged parallel to a plane formed by the optical axis of the fluorescence emitted from phosphor 106 and the optical axis of the fluorescence emitted from phosphor 108. This allows the heights of rotating bodies 401 and 402 (wheels) on which phosphors 106 and 108 are formed to be the same, thereby minimizing the impact on the size of the entire light source device 1 in the height direction. [Explanation of symbols]

[0024] 1 Light source device 2. Image display element 3 Illumination optical system 4 Projection optical system 101, 102, 103 Laser light source 104, 105, 107 Dichroic mirror 106,108 Phosphors 401,402 Rotating body 403,404 Rotation axis LT Light Tunnel [Prior art documents] [Patent documents]

[0025] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-141411 [Patent Document 2] Japanese Patent Application Laid-Open No. 2011-145681

Claims

1. a first light source that emits first excitation light of a specific wavelength; a second light source that emits second excitation light of a specific wavelength; a first wavelength conversion element having a planar shape that converts the first excitation light into a different predetermined wavelength; a planar second wavelength conversion element that converts the second excitation light into a predetermined wavelength different from that of the first wavelength conversion element; the first wavelength conversion element and the second wavelength conversion element are arranged at positions independent from each other, The first wavelength conversion element and the second wavelength conversion element are disposed at positions where their surfaces intersect perpendicularly, an optical path length of the light emitted from the first wavelength conversion element and an optical path length of the light emitted from the second wavelength conversion element are equal to each other; an image projection device, wherein at least one of the optical axis of the first excitation light and the optical axis of the second excitation light is positioned outside the same plane as a plane formed by the optical axis of the light emitted from the first wavelength conversion element and the optical axis of the light emitted from the second wavelength conversion element.

2. the first wavelength conversion element is a phosphor layer disposed on a first rotating body; the second wavelength conversion element is a phosphor layer disposed on a second rotating body; an axis of the first rotor is disposed on the same side as the second wavelength conversion element with respect to a position where the first excitation light is incident, The image projection device according to claim 1 , wherein the axis of the second rotating body is disposed on the opposite side of the second light source from the position where the second excitation light is incident.

3. an image display element for forming an image; an illumination optical system that guides the first excitation light and the second excitation light to the image display element; a projection optical system that enlarges an image of the image display element; 3. The image projection device according to claim 1, further comprising:

4. the first wavelength conversion element is a phosphor layer disposed on a first rotating body; the second wavelength conversion element is a phosphor layer disposed on a second rotating body; An image projection device as described in any one of claims 1 to 3, wherein the plane formed by the axis of the first rotating body and the axis of the second rotating body is parallel to the plane formed by the optical axis of the light emitted from the first wavelength conversion element and the optical axis of the light emitted from the second wavelength conversion element.

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