Light source device, image projection device, and display device

Abstract

To improve the light conversion efficiency of a wavelength conversion unit by efficiently converting excitation light into fluorescent light in a wavelength conversion unit.SOLUTION: A light source device comprises: a plurality of light sources which emit first color light in which the divergence angle in the first direction is larger than the divergence angle in the second direction orthogonal to the first direction; a wavelength conversion unit which converts a portion of the incident first color light into second color light in a wavelength different from the first color light; a first optical system which is arranged on an optical path of the first color light between the light source and the wavelength conversion unit; and a second optical system which is arranged on the optical path of the first color light between the first optical system and the wavelength conversion unit and emits the first color light to the wavelength conversion unit. The first optical system includes an optical element in which a plurality of optical elements having the refractive power in the first direction being the direction with the larger divergence angle of the light source stronger than the refractive power in the second direction are arrayed in the first direction. The first optical system causes the optical element to converge the light flux of the first color light in the direction approaching an optical axis of the first optical system and emits the converged light flux to the second optical system.SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] The present invention relates to a light source device, an image projection device, and a display device. [Background technology]

[0002] Projectors (image projection devices) that enlarge and project various images are widely used today. A projector is a device that focuses light emitted from a light source onto a spatial light modulation element (image display element) such as a DMD (Digital Mirror Device) or a liquid crystal display element, and displays the emitted light (reflected light) from the spatial light modulation element modulated based on a video signal as a color image on a screen.

[0003] In recent years, there has been a growing demand for projectors with higher efficiency in light source optical systems and smaller device sizes. Higher efficiency in light source optical systems requires increasing the light conversion efficiency of wavelength conversion elements that convert excitation light (first colored light) into fluorescent light (second colored light). The light conversion efficiency of wavelength conversion elements varies depending on the energy density of excitation light incident on the wavelength conversion element. Specifically, when the energy density incident on the wavelength conversion element is high, the temperature rises and the number of excitable electrons in the wavelength conversion layer decreases, resulting in a decrease in the light conversion efficiency of the wavelength conversion element. Therefore, efforts are being made to improve the light conversion efficiency of wavelength conversion elements by reducing the energy density.

[0004] On the other hand, if the spot size of the excitation light on the wavelength conversion element is increased in order to reduce the energy density of the excitation light on the wavelength conversion element, the light vignetting in the downstream optical system, etc. will increase, and the light utilization efficiency of the entire projector will decrease.

[0005] Patent Document 1 discloses a technique in which a diffusion plate is inserted in the optical path between the excitation light source and the phosphor, thereby mixing the excitation light source and obtaining a uniform spot on the phosphor. Summary of the Invention [Problem to be solved by the invention]

[0006] However, the conventional technology has had problems such as a decrease in the light conversion efficiency of a wavelength conversion element that converts excitation light (first colored light) into fluorescent light (second colored light).

[0007] The present invention has been made in consideration of the above, and aims to efficiently convert excitation light (first colored light) into fluorescent light (second colored light) in a wavelength conversion section, thereby improving the light conversion efficiency of the wavelength conversion section. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems and achieve the object, the present invention provides an optical system including: a plurality of light sources that emit first color light having a divergence angle in a first direction that is larger than the divergence angle in a second direction that is perpendicular to the first direction; a wavelength conversion unit that converts a portion of the incident first color light into second color light having a wavelength different from that of the first color light; a first optical system that is disposed on an optical path of the first color light between the light sources and the wavelength conversion unit; and a second optical system that is disposed on the optical path of the first color light between the first optical system and the wavelength conversion unit and emits the first color light to the wavelength conversion unit, wherein the first optical system includes an optical element in which a plurality of optical elements are arranged in the first direction, the refractive power of which in the first direction is stronger than the refractive power in the second direction, and the first optical system is ,before The first color light beam is converged in a direction approaching the optical axis of the first optical system and emitted to the second optical system. the plurality of light sources include at least three light sources arranged in the first direction, and among the plurality of optical elements included in the optical element, a refractive power in the first direction of an optical element closest to an optical axis of the first optical system is different from a refractive power in the first direction of other optical elements; It is characterized by: [Effects of the Invention]

[0009] According to the present invention, it is possible to efficiently convert excitation light (first colored light) into fluorescent light (second colored light) in the wavelength conversion section, thereby improving the light conversion efficiency of the wavelength conversion section. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic configuration diagram showing a projector according to a first embodiment. [Figure 2] FIG. 2 is a diagram showing an example of the configuration of a color wheel. [Figure 3] FIG. 3 is a schematic diagram showing the configuration of the light source unit. [Figure 4] FIG. 4 is a diagram illustrating an example of the configuration of a laser light source. [Figure 5] FIG. 5 is a diagram schematically showing the divergence angles of the light beams emitted from the respective light sources of the laser light source. [Figure 6] FIG. 6 is a diagram showing the relationship between each light source of the laser light source and the collimator lens. [Figure 7] FIG. 7 is a plan view showing an example of the configuration of a wavelength conversion element. [Figure 8] FIG. 8 is a diagram showing a cross section of a wavelength conversion element. [Figure 9] FIG. 9 is a diagram illustrating an example of spots formed on the surface of a wavelength conversion element. [Figure 10] FIG. 10 is a schematic diagram showing a light beam in an optical system from a laser light source to a wavelength conversion element. [Figure 11] FIG. 11 is a schematic diagram showing the optical paths of the light rays emitted from each light source of the laser light source. [Figure 12] FIG. 12 is a schematic diagram showing the optical paths of the light rays emitted from each light source of the laser light source. [Figure 13] FIG. 13 is a diagram illustrating an example of a cylindrical lens array. [Figure 14] FIG. 14 is a diagram showing an example of spots based on differences in the distance between the vertices of the cylindrical surfaces of a cylindrical lens array. [Figure 15] FIG. 15 is a diagram illustrating an example of the state of the spot on the wavelength conversion element. [Figure 16] FIG. 16 is a schematic diagram showing the optical paths of the light rays emitted from each light source of the laser light source according to the first modification. [Figure 17] FIG. 17 is a schematic diagram showing the optical paths of the light rays emitted from each light source of the laser light source according to the first modification. [Figure 18]FIG. 18 is a diagram illustrating an example of a cylindrical lens array according to the first modification. [Figure 19] FIG. 19 is a schematic diagram showing the optical paths of the light rays emitted from each light source of the laser light source according to the second modification. [Figure 20] FIG. 20 is a schematic diagram showing the optical paths of the light rays emitted from each light source of the laser light source according to the second modification. [Figure 21] FIG. 21 is a diagram illustrating an example of a cylindrical lens array according to the second modification. [Figure 22] FIG. 22 is a schematic diagram showing the configuration of a light source unit according to the third modification. [Figure 23] FIG. 23 is a plan view showing an example of the configuration of a wavelength conversion element according to the fourth modification. [Figure 24] FIG. 24 is a diagram showing a cross section of a wavelength conversion element according to the fourth modification. [Figure 25] FIG. 25 is a schematic diagram showing the configuration of a light source unit according to the fifth modification. [Figure 26] FIG. 26 is a plan view showing an example of the configuration of a wavelength conversion element according to the fifth modification. [Figure 27] FIG. 27 is a diagram showing a cross section of a wavelength conversion element according to the fifth modification. [Figure 28] FIG. 28 is a schematic diagram showing the optical path of a light ray in an optical system from a laser light source to a wavelength conversion element according to the second embodiment. [Figure 29] FIG. 29 is a schematic diagram showing the optical path of a light ray in an optical system from a laser light source to a wavelength conversion element. [Figure 30] FIG. 30 is a diagram illustrating an example of the state of spots on a wavelength conversion element. [Figure 31] FIG. 31 is a schematic diagram showing the configuration of a light source unit according to the third embodiment. [Figure 32] FIG. 32 is a schematic diagram showing a light beam in an optical system from a laser light source to a wavelength conversion element. [Figure 33] FIG. 33 is a schematic diagram showing the configuration of a light source unit according to the sixth modification. [Figure 34]FIG. 34 is a schematic diagram showing the optical paths of the light rays emitted from each light source of the laser light source according to the fourth embodiment. [Figure 35] FIG. 35 is a schematic diagram showing the optical paths of the light rays emitted from each light source of the laser light source according to the fourth embodiment. [Figure 36] FIG. 36 is a block diagram illustrating an example of the overall configuration of a display device according to the fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a light source device, an image projection device, and a display device will be described in detail with reference to the accompanying drawings.

[0012] (First embodiment) FIG. 1 is a schematic diagram showing the configuration of a projector 1 according to the first embodiment.

[0013] The projector (image projection device) 1 has a housing 10, a light source device 20, a light uniformizing element 30, an illumination optical system 40, an image forming element (image display element) 50, a projection optical system 60, a control device 80, and a color wheel 90. Schematically, the projector (image projection device) 1 uniformizes the light emitted from the light source device 20 by mixing it with the light uniformizing element 30. The projector (image projection device) 1 then uses the illumination optical system 40 to substantially uniformly illuminate the image forming element (image display element) 50, and enlarges and projects the image formed by the image forming element (image display element) 50 onto a screen (irradiated member) 70 using the projection optical system 60.

[0014] The housing 10 houses a light source device 20, a light uniformizing element 30, an illumination optical system 40, an image forming element 50, a projection optical system 60, a control device 80, and a color wheel 90.

[0015] The light source device 20 emits light containing wavelengths corresponding to the respective colors of RGB, for example. The light source device 20 has a light source unit 20A, a light source unit 20B, and a light path combining element 20C, which is a combining unit. The light source unit 20A and the light source unit 20B have the same structure and emit light beams of a predetermined shape. The internal configurations of the light source unit 20A and the light source unit 20B will be described in detail later. The light beams emitted from the light source unit 20A and the light source unit 20B are deflected by the light path combining element 20C, respectively, and enter the incident side surface of the light uniformizing element 30. In this embodiment, a prism is shown as an example of the light path combining element 20C, but the present invention is not limited to this.

[0016] As shown in FIG. 1, in the projector 1, the light beams output from the light source unit 20A and the light source unit 20B in the middle of being focused are reflected and deflected by two reflecting units (light path combining element 20C in FIG. 1) that are at an angle of approximately 90 degrees to each other, and are reflected in the same direction, and the focused light beams are combined by being adjacent to each other or partially overlapping each other, and are simultaneously incident on the light uniformizing element 30.

[0017] In this embodiment, the light source device 20 is shown as an example using two light source units 20A and 20B, but this is not limited to this, and the light source device 20 may be configured to use two or more light source units, for example, four light source units, and combine them.

[0018] The light uniformizing element 30 uniformizes the light emitted from the light source device 20 by mixing it. More specifically, the light uniformizing element 30 transmits a light beam incident from the incident side surface while repeatedly reflecting it inside and then emits it from the emission surface. The light uniformizing element 30 forms a uniform surface light source on the emission surface by reflecting the light beam incident from the incident side surface multiple times inside. Examples of the light uniformizing element 30 include a light tunnel with a hollow interior and four mirrors on the inner surface, a rod integrator formed into a rectangular pillar made of a transparent material such as glass, and a fly's eye lens. For example, when a light tunnel is used as the light uniformizing element 30, the aspect ratio of the light tunnel is made approximately the same as that of the image forming element 50, and the shape of the light tunnel exit is projected onto the surface of the image forming element 50, thereby enabling efficient illumination of the surface of the image forming element 50 without waste.

[0019] The illumination optical system 40 substantially uniformly illuminates the image forming element 50 with the light homogenized by the light homogenizing element 30. The illumination optical system 40 has, for example, one or more lenses and one or more reflecting surfaces.

[0020] The image forming element 50 has a light valve such as a digital micromirror device (DMD), a transmissive liquid crystal panel, or a reflective liquid crystal panel. The image forming element 50 forms image light by modulating light illuminated by the illumination optical system 40 (light from the light source optical system of the light source device 20). Note that, although an example of a projector (image projection device) 1 using a digital micromirror device (DMD) is shown in this embodiment, the present invention is not limited to this.

[0021] The control device 80 switches the surface of the image forming element 50 pixel by pixel by reflecting or transmitting the illumination light irradiated onto the image forming element 50 according to the input image, and guides the light to the projection optical system 60 .

[0022] The projection optical system 60 enlarges and projects the image light formed by the image forming element 50 onto a screen (irradiated member) 70. The projection optical system 60 has, for example, one or more lenses. The projection optical system 60 has a conjugate relationship such that an image on the surface of the image forming element 50 is formed as an enlarged image at a desired position on the screen (irradiated member) 70, and therefore, the spatially modulated image light is enlarged and projected onto the surface of the image forming element 50.

[0023] Additionally, a color wheel 90 is provided at the light exit of the light uniforming element 30. The color wheel 90 has color filters that switch between colors to extract at least blue, green, and red light components. The color wheel 90 is equipped with color filters that extract desired color components from the fluorescent light. The color wheel 90 synchronizes the rotation of the wavelength conversion element 26 (see FIG. 3, etc.), which is a wavelength conversion unit used in each of the light source units 20A and 20B, with the rotation of the color wheel 90 to synchronously drive the color filter switching. Monochromatic images are displayed sequentially by displaying images on the surface of the image forming element 50 according to the switching timing. Because this switching time is faster than the response speed of the human eye, the images are perceived as color images.

[0024] More specifically, the color wheel 90 extracts necessary color components, such as green and red components, from the fluorescent light in a time-division manner by sequentially switching between color filters. To switch between color filters in this manner, a segment is provided for each color filter, and the segments are rotated by a rotary motor to sequentially switch between the desired color filters.

[0025] 2 is a diagram showing an example of the configuration of the color wheel 90. As shown in Fig. 2, the color wheel 90 is divided into four regions: a blue region B, a yellow region Y, a red region R, and a green region G. The blue region B corresponds to the blue reflection region A3 (see Fig. 7) of the wavelength conversion element 26, and the yellow region Y, the red region R, and the green region G are synchronized so as to correspond to the phosphor regions A1 and A2 (see Fig. 7) of the wavelength conversion element 26, respectively.

[0026] In the blue region B, by disposing a transmissive diffuser plate, it is possible to reduce the coherence of the laser light source and reduce speckles on the screen (irradiated member) 70. The yellow region Y transmits light in the yellow wavelength region emitted from the phosphor region of the wavelength conversion element 26 as is. In addition, by using dichroic mirrors in each of the red region R and green region G, light in unnecessary wavelength regions is reflected from the light in the yellow wavelength region, thereby obtaining light of a highly pure color.

[0027] Each color produced by the color wheel 90 is guided to the image forming element 50 through the illumination optical system 40. The image forming element 50 forms an image corresponding to each color. The image formed by the image forming element 50 is then enlarged and projected onto a screen (irradiated member) 70 by the projection optical system 60.

[0028] 3 is a schematic diagram showing the configuration of the light source unit 20A. The light source unit 20B has a similar configuration.

[0029] The light source unit 20A (20B) includes, arranged in order in the light propagation direction, laser light sources (excitation light sources) 21, collimator lenses 22 provided corresponding to each light source constituting the laser light sources (excitation light sources) 21, a first optical system 23, a polarizing beam splitter 24 serving as a light path branching element, a quarter-wave plate 37, a second optical system (light-collecting optical system) 25, a wavelength conversion element 26 serving as a wavelength conversion plate, and a third optical system 27. The first optical system 23 includes a positive lens 23a, a negative lens 23b, a cylindrical lens array 28, and a cylindrical lens 29. The second optical system 25, which outputs blue laser light (first colored light) emitted from each light source of the laser light sources 21 to the wavelength conversion element 26, includes two positive lenses 25a and 25b. For example, the components of the light source device 20 excluding the laser light sources 21 and the wavelength conversion element 26 constitute a "light source optical system." In the light source unit 20A (20B), the above-mentioned components are arranged in the order of propagation of blue laser light (first color light) which is excitation light emitted from the laser light source .

[0030] The laser light source 21 has multiple light sources (light-emitting points). Laser diodes with light-emitting points arranged in a two-dimensional array are used as the laser light source 21. Here, FIG. 4 is a diagram showing an example of the configuration of the laser light source 21, and FIG. 5 is a diagram showing a schematic diagram of the divergence angle of light emitted from each light source of the laser light source 21. While FIG. 3 depicts four light sources arranged vertically, in reality, as shown in FIG. 4, the four light sources are arranged in five rows in the direction perpendicular to the paper surface (depth direction), resulting in a two-dimensional array of 4 × 5 = 20 light sources. Each light source of the laser light source 21 emits, for example, light in the blue band (blue laser light) with a center wavelength of 455 nm in emission intensity as excitation light for exciting the phosphor included in the wavelength conversion element 26. The laser light source 21 may be arranged in a honeycomb or annular shape, instead of a rectangular shape.

[0031] As shown in Fig. 5, each light source of the laser light source 21 has a different divergence angle in two orthogonal directions. As shown in Fig. 5, the direction in which the divergence angle is maximum is the X direction (first direction), and the direction in which it is minimum is the Y direction (second direction), and the divergence angles in each direction are θx and θy. As shown in Fig. 5, when an image is formed from a light source having different divergence angles in two orthogonal directions, such as a semiconductor laser, the spot shape reflects the near-field pattern and is an ellipse or rectangle with the direction in which the divergence angle is large as the minor axis.

[0032] The light source may be, for example, a metal block with laser diodes arranged on it, or a multi-chip product with laser diode chips arranged in an array on a single substrate. Note that, although this embodiment describes the use of a multi-chip product as the light source, this is not limiting, and it is also possible to use an array of CAN-type lasers, for example.

[0033] The blue laser light (first colored light) emitted from each light source of the laser light source 21 is linearly polarized light with a fixed polarization state, and is arranged to be S-polarized with respect to the polarizing beam splitter 24. Here, the light is made incident so as to be S-polarized, but it may be P-polarized or have another polarization state. The blue laser light emitted from each light source of the laser light source 21 is coherent light. Furthermore, the excitation light emitted from each light source of the laser light source 21 may be light of a wavelength that can excite the phosphor provided in the wavelength conversion element 26, and is not limited to light in the blue band.

[0034] Although the laser light source 21 uses a plurality of light sources in this example, it may use a single laser light source. Also, the laser light source 21 may use light source units arranged in an array on a substrate, but is not limited to this.

[0035] Twenty collimator lenses 22 are provided corresponding to the 20 light sources of the laser light source 21. Each collimator lens 22 adjusts the excitation light emitted by each light source of the laser light source 21 to become approximately parallel light. The number of collimator lenses 22 only needs to correspond to the number of light sources of the laser light source 21, and can be increased or decreased according to an increase or decrease in the number of light sources of the laser light source 21.

[0036] 6 is a diagram showing the relationship between each light source of the laser light source 21 and the collimator lens 22. When the distance to the incident surface of the collimator lens 22 is L and the direction of the maximum divergence angle among the divergence angles of the light sources of the laser light source 21 is the X direction, the divergence angle in the X direction is θx and the pitch of the light emitting points in the X direction is Px.

[0037] The excitation light emitted from the multiple laser light sources 21 is converted into approximately parallel light by collimator lenses 22 corresponding to each laser light source 21. The approximately parallel excitation light enters a first optical system 23. The optical axis of the first optical system 23 is arranged to pass through the center of the array of laser light sources 21. In other words, the chief ray coincides with the optical axis of the first optical system 23. The beam of excitation light is reduced by the first optical system 23 and guided to a polarizing beam splitter 24 arranged at an angle of 45 degrees with respect to the optical axis of the first optical system 23.

[0038] In this embodiment, the polarizing beam splitter 24 is disposed at an angle of 45 degrees, but may be disposed at other angles.

[0039] The polarizing beam splitter 24 guides the excitation light (first color light) emitted from the first optical system 23 to the second optical system 25. The polarizing beam splitter 24 also transmits the fluorescent light (second color light) emitted from the wavelength conversion element 26. More specifically, the polarizing beam splitter 24 is a parallel-flat glass plate. The polarizing beam splitter 24 has a coating on the incident surface that reflects S-polarized light (first polarization component) in the wavelength band of the excitation light guided from the first optical system 23 and transmits P-polarized light (second polarization component) in the wavelength band of the excitation light guided from the first optical system 23 and the fluorescent light (second color light) from the wavelength conversion element 26.

[0040] The polarizing beam splitter 24 has its center shifted with respect to the optical axis of the second optical system 25, and the excitation light is incident at an angle with respect to the normal to the wavelength conversion element 26. In other words, the excitation light emitted from the first optical system 23 is folded back by the polarizing beam splitter 24.

[0041] In this embodiment, a flat polarizing beam splitter 24 is used as the reflective optical element, but a prism type may also be used. Also, in this embodiment, the polarizing beam splitter 24 reflects S-polarized light in the wavelength band of the excitation light and transmits P-polarized light, but the polarizing beam splitter 24 may be configured to reflect P-polarized light in the wavelength band of the excitation light and transmit S-polarized light. Also, the reflective optical element may be a simple mirror with wavelength characteristics like a dichroic mirror, or a diffractive optical element such as a DOE.

[0042] As shown in FIG. 3, the excitation light reflected by the polarizing beam splitter 24 is converted into circularly polarized light by the quarter-wave plate 37. The light converted into circularly polarized light enters the second optical system 25, which is a focusing optical system. The excitation light passing through the second optical system 25 is guided to the wavelength conversion element 26. The excitation light is incident on the wavelength conversion element 26, thereby forming a desired focused spot on the wavelength conversion element 26. The excitation light reflected by the blue reflection region A3 (see FIG. 7) of the wavelength conversion element 26 passes through the second optical system 25 again, then enters the quarter-wave plate 37 and is converted into P-polarized light. The excitation light converted into P-polarized light passes through the polarizing beam splitter 26, then passes through the third optical system 27, is deflected by the light path combining element 20C, and enters the light uniformizing element 30. The light uniformizing element 30 uniformizes the incident light.

[0043] As shown in FIG. 3, when excitation light is incident on the phosphor regions (yellow phosphor region A1 and green phosphor region A2: see FIG. 7) of the wavelength conversion element 26, the phosphor regions (yellow phosphor region A1 and green phosphor region A2) receive the excitation light and emit wavelength-converted fluorescent light 360 degrees around the fluorescent molecules. The fluorescent light emitted from the phosphor regions of the wavelength conversion element 26 contains a yellow or green component. The excitation light reflected by the surface (substrate surface) of the substrate 26a (see FIG. 8) of the wavelength conversion element 26 passes through the phosphor regions (yellow phosphor region A1 and green phosphor region A2) again and emits fluorescent light with a Lambertian distribution on the surface side of the phosphor regions (yellow phosphor region A1 and green phosphor region A2). The fluorescent light emitted from the phosphor regions (yellow phosphor region A1 and green phosphor region A2) of the wavelength conversion element 26 is guided to the light uniformizing element 30 via the light path combining element 20C (omitted in FIG. 3). More specifically, the fluorescent light is converted into approximately parallel light by the second optical system 25, passes through the quarter-wave plate 37, is refracted by the third optical system 27 so as to be focused near the light uniformizing element 30, is deflected by the light path combining element 20C, and enters the light uniformizing element 30.

[0044] Fig. 7 is a plan view showing an example of the configuration of the wavelength conversion element 26. As shown in Fig. 7, the wavelength conversion element 26 according to this embodiment is disk-shaped. The wavelength conversion element 26 is a wavelength conversion plate in which three segments, namely, a yellow phosphor region (first wavelength conversion region) A1 which is a conversion region including a wavelength conversion member (phosphor) 26f, a green phosphor region (second wavelength conversion region) A2 which is a conversion region including a wavelength conversion member (phosphor) 26g, and a blue reflection region A3 which reflects light emitted from the laser light source (excitation light source) 21 (in other words, a non-conversion region which emits light received from the laser light source (excitation light source) 21 without converting the wavelength of the light), are formed in strips around the periphery of the disk-shaped plate at desired angles.

[0045] The yellow phosphor region A1 is formed of, for example, yellow phosphor 26f that receives blue laser light as excitation light and emits fluorescent light in a yellow wavelength band, and the green phosphor region A2 is formed of, for example, green phosphor 26g that receives blue laser light as excitation light and emits fluorescent light in a green wavelength band.

[0046] In this embodiment, two types of phosphors, the yellow phosphor region A1 and the green phosphor region A2, are used, but this is not limiting. For example, only the yellow phosphor region A1 may be used, or a red phosphor region may be added. Furthermore, the wavelength conversion element 26 may be provided with a plurality of blue reflection regions A3.

[0047] The disk-shaped wavelength conversion element 26 can be rotated at high speed by a drive unit controlled by the control device 80, thereby cyclically moving sequentially between the yellow phosphor region A1, the green phosphor region A2, and the blue reflection region A3. The drive unit is usually preferably a rotary motor M. As wavelength conversion element 26 is rotated by the drive unit, the yellow phosphor region A1, the green phosphor region A2, and the blue reflection region A3 are switched at the light-focusing spot, which is the position where light is irradiated from the laser light source (excitation light source) 21, and light of different wavelengths is emitted in a time-division manner.

[0048] By rotating the disk-shaped wavelength conversion element 26 in this way, it is possible to prevent burning or the like caused by continuous irradiation of excitation light at one point, and by driving it, it is possible to cool the phosphor.

[0049] In addition, the light source unit 20A (20B) places a light absorbing or reflecting member on the wheel of the wavelength conversion element 26 or on the member that supports and rotates the wheel, and detects it with a photocoupler, etc., to make the rotation speeds of the two wavelength conversion elements 26 the same.

[0050] 8 is a diagram showing a cross section of the wavelength conversion element 26. A transparent substrate or a metal substrate such as aluminum can be used as the substrate 26a of the wavelength conversion element 26. However, the substrate 26a of the wavelength conversion element 26 is not limited to a metal substrate.

[0051] In the blue reflection region A3 that reflects the excitation light, for example, a reflective coating 26b having a higher reflectance for the excitation light may be formed on the substrate 26a, or the reflective region can be formed by using a metal substrate as described above.

[0052] The phosphor regions (yellow phosphor region A1 and green phosphor region A2) are provided with, in order on substrate 26a, reflective coating 26b that reflects light in the wavelength region of light emitted from phosphors 26f and 26g, phosphors 26f and 26g, and anti-reflection coating (AR coating) 26c that reduces reflection on the phosphor surfaces. However, the configuration of the phosphor regions (yellow phosphor region A1 and green phosphor region A2) is not limited to this. If substrate 26a is a metal substrate, reflective coating 26b may be omitted.

[0053] The phosphors 26f and 26g may be a phosphor material dispersed in an organic or inorganic binder, or a phosphor material crystal formed directly. The phosphor material may be a rare earth phosphor such as Ce:YAG, but is not limited to this. Phosphors or nonlinear optical crystals may also be used.

[0054] The wavelength band of the fluorescent light emitted from the phosphor can be, for example, yellow, blue, green, or red wavelength bands, but this embodiment shows the case where fluorescent light having yellow wavelength bands and green wavelength bands is used.

[0055] Next, the cylindrical lens array 28 and the cylindrical lens 29 included in the first optical system 23 will be described.

[0056] 9 is a diagram illustrating an example of spots formed on the surface of the wavelength conversion element 26. As described in FIG. 5, when a plurality of light sources having different divergence angles in two mutually orthogonal directions are used in the laser light source 21, if the light sources are arranged in the direction with the larger divergence angle, it is necessary to arrange them so that the light beams and the collimator lenses 22 do not interfere with each other, and therefore it is necessary to increase the interval between the light sources of the laser light source 21. Therefore, as shown in FIG. 9(a), the spots formed on the surface of the wavelength conversion element 26 become scattered spots. Note that FIG. 1 shows an example in which four light sources are arranged in each of the X direction and the Y direction, but the present invention is not limited to this.

[0057] Therefore, in this embodiment, a cylindrical lens array 28, which is an optical element having optical elements (spherical lenses) that have different curvatures in the X and Y directions and are arranged in an array in the X direction, is formed between the laser light source 21 and the second optical system 25, so that the spot on the wavelength conversion element 26 is spread in the X direction, as shown in Fig. 9(b). This makes it possible to form a more uniform spot on the wavelength conversion element 26, thereby improving the wavelength conversion efficiency of the wavelength conversion element 26 and preventing burning, etc.

[0058] Here, Fig. 10 is a schematic diagram showing a light beam in the optical system from the laser light source 21 to the wavelength conversion element 26. Note that Fig. 10 shows an optical system arranged in a straight line, but it goes without saying that in practice, as shown in Fig. 3 etc., a polarized beam splitter 26 is disposed to fold the light.

[0059] As shown in FIG. 10, the first optical system 23 is composed of, from the excitation light incident side, a positive lens 23a, a negative lens 23b, a cylindrical lens array 28, and a cylindrical lens 29. The cylindrical lens array 28 has a curvature (refractive power) in the X direction (see FIG. 4) where the divergence angle of each light source of the laser light source 21 is large, and is a cylindrical lens array arranged in the X direction. The cylindrical lens array 28 has a cylindrical surface where multiple optical elements (spherical lenses) with stronger refractive power in the X direction than in the Y direction are arranged in the X direction. The cylindrical lens 29 is a cylindrical lens with a curvature (refractive power) in the Y direction where the divergence angle of each light source of the laser light source 21 is small. By arranging the cylindrical lens 29, it is possible to adjust the spot size in the Y direction on the wavelength conversion element 26.

[0060] As shown in FIG. 10, the second optical system 25 is composed of a positive lens 25a which is an aspherical lens having positive power (refractive power), and a positive lens 25b which is a plano-convex lens having positive power (refractive power).

[0061] In this embodiment, the first optical system 23 is configured using one positive lens and one negative lens, but it may also be configured using one positive lens, or the number of lenses may be increased as appropriate.

[0062] In this embodiment, the cylindrical lens array 28 and the cylindrical lenses 29 are arranged in the first optical system 23, but the present invention is not limited to this and may be arranged, for example, immediately after the collimator lens 22, between the positive lens 23a and the negative lens 23b. The cylindrical lens array 28 and the cylindrical lenses 29 may be arranged closer to the wavelength conversion element 26 than the center position of the first optical system 23 in the optical axis direction (on the wavelength conversion element 26 side in the optical path of the excitation light from the laser light source 21 to the wavelength conversion element 26). Arranging the cylindrical lens array 28 and the cylindrical lenses 29 in this manner enables miniaturization.

[0063] In this embodiment, the cylindrical lens array 28 and the cylindrical lenses 29 are arranged closest to the wavelength conversion element 26 in the first optical system 23. By arranging the cylindrical lens array 28 and the cylindrical lenses 29 closest to the wavelength conversion element 26 in this way in the first optical system 23, it is possible to reduce the size of the cylindrical lens array 28, thereby enabling cost reduction and miniaturization of the optical system.

[0064] As shown in Figure 10, when a light ray parallel to the optical axis of the first optical system 23 enters the first optical system 23, the light emitted from the first optical system 23 propagates toward the optical axis of the first optical system 23 and enters the second optical system 25. This allows a focal point to be formed on the laser light source 21 side of the wavelength conversion element 26, making it possible to blur the spot on the wavelength conversion element 26. Here, the optical axis refers to the line connecting the centers of multiple lenses. In this way, by forming the focal point upstream in the emission direction of the blue laser light (first colored light) from the wavelength conversion element 26, it is possible to obtain a uniform spot shape on the wavelength conversion element 26.

[0065] 11 and 12 are schematic diagrams showing the optical paths of the light rays emitted from each light source of the laser light source 21. Fig. 11 shows the XZ plane, and Fig. 12 shows the YZ plane.

[0066] 11, the laser light sources 21 are arranged so that the divergence angle of each light source is large in the X direction. As shown in Fig. 11, the light beams emitted from each light source of the laser light source 21 pass through a positive lens 23a and a negative lens 23b of the first optical system 23, and then enter an array-shaped cylindrical lens array 28 having positive power (refractive power) corresponding to each light source, and are converged in a direction approaching the optical axis of the first optical system 23.

[0067] In this embodiment, the cylindrical lens array 28 has a cylindrical surface, but it may have an anamorphic surface.

[0068] Furthermore, in this embodiment, the cylindrical lens array 28 is configured with optical elements (spherical lenses) having cylindrical surfaces arranged in the X direction. However, the optical elements may also be aspherical. In this case, the cylindrical lens array 28 may have an aspherical shape with a stronger negative power (refractive power) in the periphery than in the vicinity of the optical axis, thereby making the edges of the spots on the wavelength conversion element 26 sharper. That is, by making the optical elements arranged in an array on the cylindrical surface of the cylindrical lens array 28 aspherical, the negative power (refractive power) is stronger in the periphery than in the center, thereby reducing the amount of blurring in the periphery of the spots on the wavelength conversion element 26. This makes it possible to minimize vignetting in the subsequent optical system, thereby enabling high efficiency and miniaturization.

[0069] Furthermore, although the cylindrical lens array 28 is a lens in this embodiment, it may also be a curved mirror.Furthermore, although the cylindrical lens array 28 is a lens in this embodiment, it may also be a curved mirror.

[0070] The light rays converged by the cylindrical lens array 28 in a direction approaching the optical axis of the first optical system 23 pass through a cylindrical lens 29 that has no power (refractive power) in the X direction and enter the second optical system 25. Each light ray forms a focal point within the second optical system 25 and enters the wavelength conversion element 26.

[0071] 12 shows the optical path of each light source of the laser light source 21 on the side where the divergence angle is smaller, that is, in the Y direction. As shown in FIG. 12, the light beams emitted from each light source of the laser light source 21 pass through the positive lens 23a and the negative lens 23b of the first optical system 23, enter the cylindrical lens array 28 that has no power (refractive power) in the Y direction, and are converged in a direction approaching the optical axis of the first optical system 23. Thereafter, the light beams pass through the cylindrical lens 29 that has positive power (refractive power), and enter the second optical system 25. Each light beam forms a focal point in the second optical system 25 and enters the wavelength conversion element 26.

[0072] In this embodiment, the spot size on the wavelength conversion element 26 is optimized by optimizing the distance between the positive lens 23a and the negative lens 23b that constitute the first optical system 23 and the curvature of the cylindrical lens array 28.

[0073] Here, Fig. 13 is a diagram illustrating an example of the cylindrical lens array 28. As shown in Fig. 13, the radius of curvature of the optical elements (spherical lenses) closest to the optical axis of the first optical system 23, i.e., the two optical elements (spherical lenses) at the center of the cylindrical surface of the cylindrical lens array 28, is defined as R1, and the radius of curvature of the peripheral optical elements (spherical lenses) is defined as R2. R1 is set to be smaller than R2. Furthermore, the distance between the vertices of the two central cylindrical surfaces of the cylindrical lens array 28 is defined as P1, and the distance between the vertices of the peripheral cylindrical surfaces is defined as P2. P1 is set to be larger than P2.

[0074] The amount of blurring of the spot on the wavelength conversion element 26 increases for light sources other than the light source closest to the plane that includes the optical axis of the first optical system 23 and is perpendicular to the X direction. Therefore, in this embodiment, the radius of curvature of the optical element (spherical lens) closest to the optical axis of the first optical system 23 is made smaller than the radius of curvature of the other optical elements (spherical lenses), thereby increasing the amount of blurring of the light source closest to the plane that includes the optical axis of the first optical system 23 and is perpendicular to the X direction, and uniforming the spot on the wavelength conversion element 26.

[0075] 14 is a diagram showing an example of spots based on differences in the distance between the vertices of the cylindrical surfaces of the cylindrical lens array 28. Due to the aberration of the second optical system 25, the distance between spots on the wavelength conversion element 26 of the light source that is closest to a plane that includes the optical axis of the first optical system 23 and is perpendicular to the X direction becomes shorter. Therefore, in this embodiment, as shown in FIG. 14(b), overlapping of spots can be reduced by changing the pitch of the optical elements (spherical lenses) arranged in an array on the cylindrical lens array 28, thereby making the energy density more uniform.

[0076] Furthermore, by decentering the cylindrical lens array 28 with respect to each light source of the laser light source 21, the excitation light is made incident on the optical elements (spherical lenses) arranged in an array on the cylindrical lens array 28 at an angle with respect to the optical axis of the first optical system 23. This makes it possible to deflect the spot shape, thereby reducing the amount of overlap of each spot on the wavelength conversion element 26 and making it possible to achieve greater uniformity.

[0077] Here, Fig. 15 is a diagram showing an example of the state of spots on the wavelength conversion element 26. Fig. 15(a) shows the case where the cylindrical lens array 28 is not used, and Fig. 15(b) shows the case where the cylindrical lens array 28 is used. In Fig. 15, white parts indicate areas with high intensity, and black parts indicate areas with low intensity. Note that the intensity ranges in Fig. 15(a) and Fig. 15(b) are the same.

[0078] 15(a), when the cylindrical lens array 28 is not used, a profile reflecting the arrangement of each light source of the laser light source 21 is shown, and the intensity is not sufficiently uniform. In contrast, as shown in Fig. 15(b), when the cylindrical lens array 28 is used, the profile of each light source of the laser light source 21 is blurred, and an overall uniform profile is obtained, making it possible to improve the wavelength conversion efficiency of the wavelength conversion element 26.

[0079] In this way, the cylindrical lens array 28 has at least three light sources in the X direction, and among the vertices of the cylindrical surfaces of the cylindrical lens array 28 arranged in an array in the X direction, the optical element (spherical lens) closest to the optical axis of the first optical system 23 and the other optical elements (spherical lenses) have different powers (refractive powers). As a result, the spot on the wavelength conversion element 26 of the light source closest to the plane containing the optical axis of the first optical system 23 and perpendicular to the X direction among the three light sources arranged in the X direction is affected by the aberration of the second optical system 25 and has a different amount of blur. By making the radii of curvature different, the amount of blur on the wavelength conversion element 26 of the light source close to the optical axis and the surrounding light sources can be made to be the desired amount of blur, making it possible to make the blur more uniform and improving the wavelength conversion efficiency of the wavelength conversion element 26.

[0080] Furthermore, by increasing the power (refractive power) of the optical element (spherical lens) closest to the optical axis of the first optical system 23 compared to the others, the amount of blurring of the light source closest to the plane that includes the optical axis of the first optical system 23 and is perpendicular to the X direction can be increased, and the spot on the wavelength conversion element 26 can be made uniform.

[0081] Furthermore, the optical elements (spherical lenses) arranged in an array on the cylindrical surface of the cylindrical lens array 28 have no power (refractive power) in the Y direction, which allows for cost reduction.

[0082] Furthermore, when there are at least four light sources in the X direction, among the optical elements (spherical lenses) arranged in an array on the cylindrical surface of the cylindrical lens array 28, the distance P2 between the peripheral optical elements (spherical lenses) is set shorter than the distance P1 between the optical elements (spherical lenses) closest to the optical axis. This is because, due to aberration of the second optical system 25, the distance between spots on the wavelength conversion element 26 of the light source closest to the plane containing the optical axis of the first optical system 23 and perpendicular to the X direction becomes shorter. In this way, by changing the pitch of the optical elements (spherical lenses) arranged in an array, spot overlap can be reduced, resulting in more uniform energy density. Furthermore, by decentering the optical elements with respect to the light source, the spot shape can be deviated, thereby reducing the amount of overlap between the spots and enabling more uniformity.

[0083] Furthermore, the optical elements (spherical lenses) arranged in an array on the cylindrical surface of the cylindrical lens array 28 have positive power (refractive power), which allows the first optical system 23, which is made to enter the second optical system 25 as convergent light, to have positive power (refractive power), thereby enabling blurring.

[0084] According to this embodiment, by making the excitation light incident on the second optical system 25 as convergent light, the spot on the wavelength conversion element 26 is blurred, and the excitation light (first color light) is efficiently converted into fluorescent light (second color light) in the wavelength conversion element 26, thereby improving the light utilization efficiency.

[0085] Next, some modified examples will be described.

[0086] (Variation 1) First, Modification 1 will be described. Fig. 16 and Fig. 17 are schematic diagrams showing the optical paths of the light rays emitted from each light source of the laser light source 21 according to Modification 1. Fig. 16 shows the XZ plane, and Fig. 17 shows the YZ plane. As shown in Fig. 16 and Fig. 17, Modification 1 has three rows of light sources arranged in the X direction of the laser light source 21. As shown in Fig. 16, the number of light sources in the X direction of the laser light source 21 is three, and therefore the number of arrays of the cylindrical lens array 28 is three.

[0087] 18 is a diagram illustrating an example of a cylindrical lens array 28 according to Modification 1. As shown in FIG. 18, the radius of curvature of the optical elements (spherical lenses) closest to the optical axis of the first optical system 23, i.e., the two central optical elements (spherical lenses) of the cylindrical surface of the cylindrical lens array 28, is defined as R1, and the radius of curvature of the peripheral optical elements (spherical lenses) is defined as R2. R1 is set to be smaller than R2. Furthermore, the distance between the vertices of the optical elements (spherical lenses) of the cylindrical surface of the cylindrical lens array 28 is defined as P1. This also makes it possible to uniformize the profile on the wavelength conversion element 26.

[0088] (Variation 2) Next, Modification 2 will be described. Fig. 19 and Fig. 20 are schematic diagrams showing the optical paths of the light rays emitted from each light source of the laser light source 21 according to Modification 2. Fig. 19 shows the XZ plane, and Fig. 20 shows the YZ plane. As shown in Fig. 19 and Fig. 20, Modification 2 has two rows of light sources arranged in the X direction of the laser light source 21. And, as shown in Fig. 19, since the number of light sources in the X direction of the laser light source 21 is two, the number of arrays of the cylindrical lens array 28 is two.

[0089] Fig. 21 is a diagram illustrating an example of a cylindrical lens array 28 according to Modification 2. As shown in Fig. 21, the radius of curvature of each of the two optical elements (spherical lenses) on the cylindrical surface of the cylindrical lens array 28 is R1. The distance between the vertices of the optical elements (spherical lenses) on the cylindrical surface of the cylindrical lens array 28 is P1. This also makes it possible to uniformize the profile on the wavelength conversion element 26.

[0090] (Variation 3) Next, Modification 3 will be described. Fig. 22 is a schematic diagram showing the configuration of a light source section 20A according to Modification 3. The light source section 20B has a similar configuration. As shown in Fig. 22, in Modification 3, each light source of the laser light source 21 is arranged so that the emitted excitation light (first color light) becomes P-polarized with respect to the polarized beam splitter 24. The polarized beam splitter 24 is configured to reflect fluorescent light and transmit excitation light.

[0091] 22 , the excitation light transmitted through the polarizing beam splitter 24 is guided to the wavelength conversion element 26 via the quarter-wave plate 37 and the second optical system 25. The excitation light reflected from the wavelength conversion element 26 and the fluorescent light converted by the excitation light are reflected by the polarizing beam splitter 24 and guided to the third optical system 27.

[0092] (Variation 4) Next, Modification 4 will be described. Fig. 23 is a plan view showing an example of the configuration of a wavelength conversion element 26 according to Modification 4, and Fig. 24 is a view showing a cross section of the wavelength conversion element 26 according to Modification 4. As shown in Fig. 23, the wavelength conversion element 26 of the modification is not divided into regions, and has a single phosphor region A4 in the circumferential direction.

[0093] As shown in FIG. 24, the wavelength conversion element 26 includes a substrate 26a, a reflective coating 26b that reflects the wavelength ranges of the fluorescent light and the excitation light, a phosphor 26f, and a reflective coating 26d that reflects a portion of the excitation light and transmits a portion of the fluorescent light and the excitation light. The phosphor 26f may be a phosphor material dispersed in an organic or inorganic binder, or a phosphor material crystal formed directly. The phosphor material may be, but is not limited to, a rare-earth phosphor such as Ce:YAG. The wavelength band of the light emitted by the phosphor may be, for example, yellow, and by combining it with the blue excitation light, white light can be obtained. In this embodiment, the incident side is coated with a reflective coating 26d, but a diffusing surface may also be used.

[0094] The excitation light reflected by the reflective coating 26b of the wavelength conversion element 26 passes through the second optical system 25 again, and the excitation light emitted from the second optical system 25 enters the quarter-wave plate 37 and is converted into P-polarized light. The excitation light converted into P-polarized light passes through the polarizing beam splitter 24 and enters the subsequent illumination optical system.

[0095] In addition, the fluorescent light emitted when excitation light is incident on the phosphor 26f of the wavelength conversion element 26 is converted into approximately parallel light by the second optical system 25, passes through the quarter-wave plate 37 and the polarizing beam splitter 24, and enters the subsequent illumination optical system.

[0096] As described above, according to this embodiment, it is possible to omit the color wheel 90 and the third optical system 27. Even with an inexpensive configuration in which the number of parts is reduced in this way, it is possible to form an image of a uniform spot on the wavelength conversion element 26, and it is possible to improve the light conversion efficiency of the wavelength conversion element 26.

[0097] (Variation 5) Next, Modification 5 will be described. Fig. 25 is a schematic diagram showing the configuration of a light source unit 20A according to Modification 5. Note that a light source unit 20B has a similar configuration. As shown in Fig. 25, Modification 5 includes a dichroic mirror 31 instead of the polarizing beam splitter 24, a light source 32 which is a laser light source of a solid-state light source, and a fourth optical system 33. Note that although light source 32 is a laser light source here, it is also possible to use a light-emitting diode or the like.

[0098] The excitation light that has passed through the first optical system 23 is guided to the dichroic mirror 31. The dichroic mirror 31 is coated to reflect light in the wavelength band of the excitation light and light in the wavelength range of the light source 32, and to transmit fluorescent light generated by the phosphor of the wavelength conversion element 26. Note that, although the dichroic mirror 31 reflects the excitation light and transmits the fluorescent light in the fifth modification, it may also be coated to reflect the fluorescent light and transmit the excitation light.

[0099] The excitation light reflected by the dichroic mirror 31 is guided to the wavelength conversion element 26 by the second optical system 25 .

[0100] Fig. 26 is a plan view showing an example of the configuration of a wavelength conversion element 26 according to Modification 5, and Fig. 27 is a view showing a cross section of the wavelength conversion element 26 according to Modification 5. As shown in Fig. 26, the wavelength conversion element 26 of the modification is not divided into regions, and has a single phosphor region A4 in the circumferential direction.

[0101] As shown in Figure 27, the wavelength conversion element 26 has a reflective coating 26b that reflects the wavelength ranges of fluorescent light and excitation light, a phosphor 26f, and an anti-reflection coating (AR coating) 26c that reduces reflection on the phosphor surface formed on a substrate 26a.

[0102] The fluorescent light emitted by the fluorescent material of the wavelength conversion element 26 when excitation light is incident thereon is converted into substantially parallel light by the second optical system 25, passes through the dichroic mirror 31, and enters the illumination optical system.

[0103] Furthermore, light in the blue wavelength range, for example, is emitted from a light source 32 prepared separately from the excitation light, and is converted into substantially parallel light by a fourth optical system 33 and enters the dichroic mirror 31. The light emitted from the light source 32 is then reflected by the dichroic mirror 31 and enters the illumination optical system.

[0104] (Second embodiment) Next, a second embodiment will be described.

[0105] The second embodiment differs from the first embodiment in that a diffuser plate is inserted in the first optical system 23. In the following description of the second embodiment, the same parts as those in the first embodiment will be omitted, and only the parts that differ from the first embodiment will be described.

[0106] 28 and 29 are schematic diagrams showing the optical path of a light ray in the optical system from the laser light source 21 to the wavelength conversion element 26 according to the second embodiment. Fig. 28 shows the XZ plane, and Fig. 29 shows the YZ plane.

[0107] 28 and 29, in this embodiment, the first optical system 23 includes a diffuser 34, which is a diffusing member with a half-width of 1 degree, between the negative lens 23b and the cylindrical lens array 28. In this embodiment, the diffusion angle of the diffuser 34 is set to 1 degree, but if the incident excitation light is to be strengthened, the diffusion angle can be further increased to about 3.5 degrees, which makes it possible to balance the decrease in efficiency of the phosphor and the vignetting in the subsequent optical system, thereby improving the efficiency of the entire projector 1.

[0108] The inventors of the present patent application have found that if the half-width of the diffusion angle of the diffuser 34 exceeds 3.5 degrees, the wavelength conversion efficiency of the wavelength conversion element 26 improves due to uniformity, but vignetting in the subsequent optical system increases, reducing the overall efficiency of the projector 1. Also, if the half-width is 0.5 degrees or less, it is difficult to manufacture the diffuser 34.

[0109] Therefore, in this embodiment, when the half width of the diffusion angle of the diffuser 34 is θd, the following conditional expression (1) is satisfied. 0.5 < θd < 3.5 (1)

[0110] By disposing the diffuser 34 in this way, the amount of blur can be increased, and the efficiency can be improved. If the upper limit of conditional expression (1) is exceeded, the spot on the wavelength conversion element 26 can be made more uniform, but the amount of blur of the spot increases, causing vignetting in the subsequent optical system, resulting in a decrease in the efficiency of the entire projector. If the lower limit of conditional expression (1) is exceeded, it is possible to suppress vignetting in the subsequent optical system, but the diffusion effect becomes insufficient.

[0111] In addition, in this embodiment, when the direction in which the divergence angle of the excitation light source is maximum is the X direction, the divergence angle in the X direction is θx, the pitch of the light emitting points of the excitation light source in the X direction is Px, and the distance between the collimator lens 22 and the emission side surface of the laser light source 22 is L, the following conditional formula (2) is satisfied. 0.5 <Px / Ltanθx<2 ··· (2) By satisfying the above conditional formula (2), the distance between the profiles of each light-emitting point becomes small, so that the overall profile becomes dense, and a uniform profile can be obtained when reduced onto the phosphor, thereby improving the wavelength conversion efficiency of the wavelength conversion element 26.

[0112] If the upper limit of conditional formula (2) is exceeded, the distance between the light-emitting points increases, which increases the distance between the profiles of the light-emitting points, and the reduction ratio increases when a desired spot size is desired on the wavelength conversion member 26, which reduces the image of each light-emitting point and increases the light-collection density on the wavelength conversion member 26, resulting in a decrease in wavelength conversion efficiency. On the other hand, if the lower limit of conditional formula (2) is exceeded, it is easy to obtain a uniform profile on the wavelength conversion member 26, but light from each light-emitting point enters the adjacent collimator lens 22, and some of the light rays travel in a direction other than the direction of wear, which not only generates stray light but also reduces the efficiency of the optical system.

[0113] Here, Fig. 30 is a diagram showing an example of the state of spots on the wavelength conversion element 26. Fig. 30(a) shows the case where only the cylindrical lens array 28 is used, and Fig. 30(b) shows the case where both the diffuser plate 34 and the cylindrical lens array 28 are used. In Fig. 30, white parts indicate areas with high intensity, and black parts indicate areas with low intensity. Note that the intensity ranges in Fig. 30(a) and Fig. 30(b) are the same.

[0114] 30(a), when only the cylindrical lens array 28 is used, the profile of each light source of the laser light source 21 is blurred, thereby obtaining an overall uniform profile and making it possible to improve the wavelength conversion efficiency of the wavelength conversion element 26. On the other hand, when the diffusion plate 34 and the cylindrical lens array 28 are used, as shown in FIG. 30(b), the amount of blurring can be further increased, making it possible to further improve the wavelength conversion efficiency of the wavelength conversion element 26.

[0115] As described above, according to this embodiment, the wavelength conversion efficiency of the wavelength conversion element 26 can be further improved.

[0116] (Third embodiment) Next, a third embodiment will be described.

[0117] The third embodiment differs from the first and second embodiments in that the cylindrical lens array 28 is decentered with respect to each light source of the laser light source 21. In the following description of the third embodiment, the description of the same parts as those in the first and second embodiments will be omitted, and only the parts that differ from the first and second embodiments will be described.

[0118] Here, Fig. 31 is a schematic diagram showing the configuration of a light source unit 20A according to the third embodiment. The light source unit 20B has a similar configuration. Fig. 32 is a schematic diagram showing a light beam in an optical system from the laser light source 21 to the wavelength conversion element 26. Note that Fig. 32 shows an optical system arranged in a straight line, but as shown in Fig. 31, in reality, the configuration bends light.

[0119] 32, in the third embodiment, the optical axis of the first optical system 23 and the optical axis of the second optical system 25 are vertically decentered, and the excitation light is arranged to enter from one side of the second optical system 25. However, in the third embodiment, when the optical axes of the first optical system 23 and the second optical system 25 are aligned, the behavior of light is the same as in the first embodiment.

[0120] Furthermore, the light source section 20A according to this embodiment includes a dichroic mirror 35, which is an optical path branching element, instead of the polarizing beam splitter 24. The dichroic mirror 35 reflects the excitation light and transmits the fluorescent light.

[0121] In the first embodiment, the polarization direction of light is determined by the quarter-wave plate 37, but in this embodiment, it may be disposed in any direction. The light emitted from the laser light source 21 is collimated into parallel beams by the collimator lens 22, passes through the first optical system 23, is reflected by the dichroic mirror 35, and is guided to the second optical system 25.

[0122] In this embodiment, as shown in Fig. 32, the first optical system 23 is disposed so as to be decentered with respect to the second optical system 25. As a result, the excitation light enters one side of the second optical system 25 and is obliquely incident on the wavelength conversion element 26. The excitation light incident on the phosphor region of the wavelength conversion element 26 is converted into fluorescent light, and enters the third optical system 27 without passing through the dichroic mirror 35, and is then guided to the subsequent optical system. On the other hand, the excitation light incident on the reflective region of the wavelength conversion element 26 is specularly reflected, and therefore, as shown in Fig. 31, passes through the side opposite to the side on which it entered the second optical system 25 and exits from the second optical system 25.

[0123] In this embodiment, the excitation light reflected by the wavelength conversion element 26 does not pass through the dichroic mirror 35. However, it is also possible to enlarge the dichroic mirror 35 and coat half of the surface with a property of reflecting excitation light and transmitting fluorescent light, while the remaining half has a property of transmitting both excitation light and fluorescent light.

[0124] As described above, according to this embodiment, the wavelength conversion efficiency of the wavelength conversion element 26 can be further improved.

[0125] Next, a modified example of the third embodiment will be described.

[0126] (Variation 6) Here, Modification 6 will be described. Fig. 33 is a schematic diagram showing the configuration of a light source section 20A according to Modification 6. The light source section 20B has a similar configuration. As shown in Fig. 33, the light source section 20A of Modification 6 includes a plurality of laser light sources 21a and 21b as the laser light source 21. Furthermore, the light source section 20A of Modification 6 includes collimator lenses 22a and 22b corresponding to the laser light sources 21a and 21b as the collimator lens 22. Furthermore, the light source section 20A of Modification 6 includes a combining optical system 36. The combining optical system 36 includes a polarizing beam splitter 36a, a mirror 36b, and a half-wave plate 36c.

[0127] 28, in the light source unit 20A of the sixth modification, the light beams emitted from the two light sources, the laser light sources 21a and 21b, are combined using a polarized beam splitter 36a of the combining optical system 36. The two light sources, the laser light sources 21a and 21b, each emit P-polarized light.

[0128] More specifically, the light emitted from laser light source 21b passes through half-wave plate 36c of combining optical system 36, where it is converted into S-polarized light, and is reflected by mirror 36b of combining optical system 36. The S-polarized light is reflected by polarized beam splitter 36a of combining optical system 36, and enters first optical system 23. In addition, the light emitted from laser light source 21a passes through polarized beam splitter 36a of combining optical system 36, and enters first optical system 23.

[0129] This makes it possible to use this configuration in a projector with higher brightness.

[0130] (Fourth embodiment) Next, a fourth embodiment will be described.

[0131] The fourth embodiment differs from the first to third embodiments in that the positive lens 23a or the negative lens 23b of the first optical system 23 has a cylindrical lens array function. In the following description of the third embodiment, the description of the same parts as those of the first to third embodiments will be omitted, and only the parts that differ from the first to third embodiments will be described.

[0132] Figures 34 and 35 are schematic diagrams showing the optical paths of the light rays emitted from each light source of laser light source 21 according to the fourth embodiment. Figure 34 shows the XZ plane, and Figure 35 shows the YZ plane. Note that although Figures 34 and 35 depict optical systems arranged in a straight line, it goes without saying that in practice, as shown in Figure 3 and other figures, a polarizing beam splitter 26 or the like is disposed to bend the light.

[0133] As shown in FIGS. 34 and 35, in the light source section 20 of this embodiment, instead of the cylindrical lens array 28, a cylindrical array surface 39 is formed on the incident surface side of the positive lens 23a of the first optical system 23.

[0134] As shown in Fig. 34, the positive lens 23a of the first optical system 23 forms a cylindrical array surface 39 in the X direction on the lens surface, which has optical elements (spherical lenses) arranged in an array in the X direction. On the other hand, as shown in Fig. 35, the positive lens 23a of the first optical system 23 does not have a cylindrical array surface 39 in the Y direction, and has a curvature with a radius of curvature for focusing light.

[0135] In this embodiment, the cylindrical lens array surface 39 is formed on the incident surface side of the positive lens 23a of the first optical system 23, but this is not limited to this, and the cylindrical lens array surface 39 may also be formed on the surface of the negative lens 23b of the first optical system 23.

[0136] As described above, according to this embodiment, the wavelength conversion efficiency of the wavelength conversion element 26 can be further improved.

[0137] Furthermore, the cylindrical array surface 39, which is an array of optical elements (spherical lenses), may be integrated with the cylindrical lens 29 or the diffuser plate 34. Furthermore, the cylindrical array surface 39, which is an array of optical elements (spherical lenses), may be formed on the collimator lens 22.

[0138] (Fifth embodiment) Next, a fifth embodiment will be described.

[0139] The fifth embodiment differs from the first to fourth embodiments in that the projector 1, which is an example of the image projection device described in the first to fourth embodiments, is applied to a display device that allows a user to visually recognize a three-dimensional image. In the following description of the fifth embodiment, descriptions of the same parts as the first to fourth embodiments will be omitted, and only differences from the first to fourth embodiments will be described.

[0140] 36 is a block diagram showing an example of the overall configuration of a display device 100 according to the fifth embodiment. The display device 100 is also called a stereoscopic display that allows a user to visually recognize a three-dimensional image. Here, a three-dimensional image refers to a stereoscopic image that is displayed in three-dimensional space and has a volume that can be visually recognized by humans.

[0141] As shown in FIG. 36, the display device 100 includes an information processing unit 110, a projector 1, a screen 70 which is a spiral screen, a motor 140, and a motor control unit 141.

[0142] The display device 100 receives the three-dimensional model data 901 and allows a user of the display device 100 to visually recognize a three-dimensional image. The three-dimensional model data 901 is data indicating a three-dimensional model for allowing a user to visually recognize a three-dimensional image, and is, for example, data indicating pixel values ​​for each three-dimensional voxel. Specifically, the three-dimensional model data 901 is input to the information processing unit 110.

[0143] The information processing unit 110 generates image information 903 based on the input three-dimensional model data 901. Specifically, the information processing unit 110 transmits a rotation instruction signal 201 to the motor control unit 141 to instruct the motor control unit 141 to start rotation. Upon receiving the instruction, the motor control unit 141 transmits a rotation control signal 202 to drive the motor 140 so as to rotate the screen 70 at, for example, a specified substantially constant speed.

[0144] The screen 70 is an example of an irradiated member that includes a spiral shape, the cross section of which, cut along a plane perpendicular to the spiral axis, is curved.

[0145] The motor 140 is a drive unit that rotates the screen 70 around the spiral axis. The motor 140 may be a stepping motor, a DC (Direct Current) motor, an AC (Alternating Current) motor, or the like.

[0146] A rotary encoder is attached to the motor 140. The rotary encoder transmits an encoder signal 203 indicating the rotation angle of the rotation shaft of the motor 140 to the motor control unit 141. The motor control unit 141 generates rotation angle information 904 indicating the rotation angle of the screen 70 based on the received encoder signal 203, and transmits the information processing unit 110.

[0147] Based on the received rotation angle information 904, the information processing unit 110 generates image information 903 according to the rotation angle of the screen 70, and transmits it to the projector 1. The image information 903 is information representing a two-dimensional image.

[0148] The projector 1 irradiates the rotating screen 70 with image light L. The projector 1 can irradiate the screen 70 with image light L based on image information 903 output from the information processing unit 110. In other words, the projector 1 can irradiate the screen 70 with image light L generated based on the position of the rotating screen 70.

[0149] The display device 100 can allow the user to view a color three-dimensional image by utilizing the afterimage effect of the light reflected by the screen 70, out of the image light L irradiated onto the screen 70 which is rotating at high speed.

[0150] The irradiated member is not limited to the screen 70, but may be anything that vibrates the screen as long as it displays an image using the afterimage effect.

[0151] The optical elements in each embodiment may be of any shape as long as they have substantial optical power (refractive power). For example, cylindrical lenses, anamorphic lenses, Fresnel lenses, diffractive lenses, and the like are naturally applicable to the scope of the present invention. Furthermore, because uniformity can be achieved with a simple configuration, it is possible to prevent a decrease in efficiency due to optical elements, costs, and an increase in the size of the optical system.

[0152] As described above, the present invention is not limited to the contents described in the present embodiment, and can be modified as appropriate within the scope of the gist of the present invention.

[0153] In particular, the specific shapes and numerical values ​​of each part illustrated in the embodiments are merely examples of embodiments that may be made when implementing the present invention, and the technical scope of the present invention should not be interpreted in a limited manner based on these. [Explanation of symbols]

[0154] 1. Image projection device 20 Light source device 21 Light source 22 Collimator lens 23 First Optical System 24,35 Optical path branching element 25 Second Optical System 26 Wavelength conversion unit 28 Optical Elements 29 Lenses 30 Light uniformizing element 34 Diffusion element 40 Illumination optical system 50 Image forming element 60 Projection optical system 70 Irradiated member 100 display device [Prior art documents] [Patent documents]

[0155] [Patent Document 1] Patent No. 6090875

Claims

1. a plurality of light sources that emit first color light whose divergence angle in a first direction is larger than the divergence angle in a second direction orthogonal to the first direction; a wavelength conversion unit that converts a part of the incident first color light into a second color light having a wavelength different from that of the first color light; a first optical system disposed on an optical path of the first color light between the light source and the wavelength converting unit; a second optical system disposed on an optical path of the first color light between the first optical system and the wavelength converting unit, the second optical system outputting the first color light to the wavelength converting unit; Equipped with The first optical system includes: an optical element including a plurality of optical elements arranged in the first direction, the optical elements having a refractive power stronger in the first direction than in the second direction, the refractive power being a direction in which the divergence angle of the light source is large; The first optical system includes: a light beam of the first color light is converged in a direction approaching an optical axis of the first optical system and emitted to the second optical system; the plurality of light sources includes at least three light sources arranged in the first direction; Among the plurality of optical elements included in the optical element, the refractive power in the first direction of the optical element closest to the optical axis of the first optical system is different from the refractive power in the first direction of the other optical elements. A light source device characterized by:

2. a refractive power in the first direction of an optical element closest to an optical axis of the first optical system is greater than a refractive power in the first direction of the other optical elements; 2. The light source device according to claim 1.

3. A plurality of light sources emitting first color light whose divergence angle in a first direction is greater than the divergence angle in a second direction perpendicular to the first direction; a wavelength conversion unit that converts a part of the incident first color light into a second color light having a wavelength different from that of the first color light; a first optical system disposed on an optical path of the first color light between the light source and the wavelength converting unit; a second optical system disposed on an optical path of the first color light between the first optical system and the wavelength converting unit, the second optical system outputting the first color light to the wavelength converting unit; Equipped with The first optical system includes: an optical element including a plurality of optical elements arranged in the first direction, the optical elements having a refractive power stronger in the first direction than in the second direction, the refractive power being a direction in which the divergence angle of the light source is large; The first optical system includes: a light beam of the first color light is converged in a direction approaching an optical axis of the first optical system and emitted to the second optical system; the plurality of light sources includes at least four light sources arranged in the first direction, an even number of light sources being equal to or greater than four; the plurality of optical elements is the even number of optical elements, Among the even number of optical elements, a distance P1 between adjacent optical elements on the optical axis is larger than a distance P2 between adjacent other optical elements. A light source device characterized by:

4. A plurality of light sources emitting first color light whose divergence angle in a first direction is greater than the divergence angle in a second direction perpendicular to the first direction; a wavelength conversion unit that converts a part of the incident first color light into a second color light having a wavelength different from that of the first color light; a first optical system disposed on an optical path of the first color light between the light source and the wavelength converting unit; a second optical system disposed on an optical path of the first color light between the first optical system and the wavelength converting unit, the second optical system outputting the first color light to the wavelength converting unit; Equipped with The first optical system includes: an optical element including a plurality of optical elements arranged in the first direction, the optical elements having a refractive power stronger in the first direction than in the second direction, the refractive power being a direction in which the divergence angle of the light source is large; The first optical system includes: a light beam of the first color light is converged in a direction approaching an optical axis of the first optical system and emitted to the second optical system; the plurality of optical elements are aspherical; a refractive power of a central portion of each of the plurality of optical elements in the first direction being greater than a refractive power of a peripheral portion thereof; A light source device characterized by:

5. A plurality of light sources emitting first color light whose divergence angle in a first direction is greater than the divergence angle in a second direction perpendicular to the first direction; a wavelength conversion unit that converts a part of the incident first color light into a second color light having a wavelength different from that of the first color light; a first optical system disposed on an optical path of the first color light between the light source and the wavelength converting unit; a second optical system disposed on an optical path of the first color light between the first optical system and the wavelength converting unit, the second optical system outputting the first color light to the wavelength converting unit; Equipped with The first optical system includes: an optical element including a plurality of optical elements arranged in the first direction, the optical elements having a refractive power stronger in the first direction than in the second direction, the refractive power being a direction in which the divergence angle of the light source is large; The first optical system includes: a light beam of the first color light is converged in a direction approaching an optical axis of the first optical system and emitted to the second optical system; the first color light emitted from the first optical system forms a light-condensing point on an optical path of the first color light between an optical surface closest to the first optical system and the wavelength converting unit; A light source device characterized by:

6. A plurality of light sources emitting first color light whose divergence angle in a first direction is greater than the divergence angle in a second direction perpendicular to the first direction; a wavelength conversion unit that converts a part of the incident first color light into a second color light having a wavelength different from that of the first color light; a first optical system disposed on an optical path of the first color light between the light source and the wavelength converting unit; a second optical system disposed on an optical path of the first color light between the first optical system and the wavelength converting unit, the second optical system outputting the first color light to the wavelength converting unit; Equipped with The first optical system includes: an optical element including a plurality of optical elements arranged in the first direction, the optical elements having a refractive power stronger in the first direction than in the second direction, the refractive power being a direction in which the divergence angle of the light source is large; The first optical system includes: a light beam of the first color light is converged in a direction approaching an optical axis of the first optical system and emitted to the second optical system; the first optical system includes a diffusing member having a diffusing surface that diffuses the first color light, When the half width of the diffusion angle of the first color light on the diffusion surface is θd, 0.5°<θd<3.5° Satisfy the A light source device characterized by:

7. A plurality of light sources emitting first color light whose divergence angle in a first direction is greater than the divergence angle in a second direction perpendicular to the first direction; a wavelength conversion unit that converts a part of the incident first color light into a second color light having a wavelength different from that of the first color light; a first optical system disposed on an optical path of the first color light between the light source and the wavelength converting unit; a second optical system disposed on an optical path of the first color light between the first optical system and the wavelength converting unit, the second optical system outputting the first color light to the wavelength converting unit; Equipped with The first optical system includes: an optical element including a plurality of optical elements arranged in the first direction, the optical elements having a refractive power stronger in the first direction than in the second direction, the refractive power being a direction in which the divergence angle of the light source is large; The first optical system includes: a light beam of the first color light is converged in a direction approaching an optical axis of the first optical system and emitted to the second optical system; the optical element is formed on a positive lens or a negative lens that constitutes the first optical system; A light source device characterized by:

8. the optical element has no refractive power in the second direction; 8. The light source device according to claim 1, wherein the light source device is a light source unit.

9. the plurality of optical elements have positive refractive power in the first direction; 9. The light source device according to claim 1, wherein the light source device is a light source unit.

10. the first optical system includes a cylindrical lens having a refractive power in the second direction; 10. The light source device according to claim 1, wherein the light source device is a light source unit.

11. the plurality of light sources are two-dimensionally arranged in the first direction and the second direction, and a collimator lens is provided on an exit side of each of the plurality of light sources; When an arrangement pitch of the plurality of light sources in the first direction is Px, a divergence angle of the plurality of light sources in the first direction is θx, and a distance between a surface of the collimator lens facing the plurality of light sources and the plurality of light sources is L, 0.5<Px / (L×tanθx)<2 fulfill, 11. The light source device according to claim 1.

12. the wavelength converting unit further includes a driving unit that drives the wavelength converting unit so that a position of the wavelength converting unit onto which the first color light is incident moves relatively over time.

12. The light source device according to claim 1.

13. further comprising an optical path branching element that guides the first color light emitted from the first optical system to the second optical system; the optical path branching element transmits the second color light emitted from the wavelength conversion unit; 13. The light source device according to claim 1.

14. the optical element is located closer to the wavelength converting unit than a center position along the optical path of the first optical system; 14. The light source device according to claim 1, wherein the light source device is a light source unit.

15. the first color light incident on the optical element of the optical device is incident at an angle with respect to the optical axis of the first optical system; 15. The light source device according to claim 1.

16. The light source device according to any one of claims 1 to 15, an image forming element that receives light emitted from the light source device and emits image light; a projection optical system that projects the image light emitted by the image forming element onto an irradiated member; An image projection device comprising:

17. The image projection device according to claim 16; an irradiated member onto which image light from the image projection device is irradiated; Equipped with a three-dimensional image is displayed by rotating or vibrating the irradiated member onto which the image light is irradiated; A display device characterized by:

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