Light source device and projector

Abstract

To provide a light source device and a projector capable of generating rectangular illumination light extending in one direction.SOLUTION: A light source apparatus according to an aspect of the invention includes a light source section, a first optical element that diffuses light outputted from the light source section along a first axis perpendicular to an optical axis of the light to produce strip-shaped illumination light extending along the first axis, and a second optical element that parallelizes the illumination light outputted from the first optical element in a direction along the first axis, and the first optical element moves in a plane perpendicular to the optical axis.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a light source device and a projector. [Background technology]

[0002] As a light source device for use in a projector, a light source device has been proposed that illuminates a light modulation device such as a liquid crystal panel by temporally scanning light emitted from an optical element on the light modulation device. Patent Document 1 listed below discloses a projector that includes a light source device including a light source lamp, a liquid crystal light valve, a polygon mirror provided between the light source device and the liquid crystal light valve, and a projection lens. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-225956 Summary of the Invention [Problem to be solved by the invention]

[0004] In the projector of Patent Document 1, the polygon mirror reflects the light emitted from the light source device and focuses it onto the liquid crystal light valve, making it difficult to make the illumination light that extends in a strip shape in a direction perpendicular to the scanning direction incident on the liquid crystal light valve. [Means for solving the problem]

[0005] In order to solve the above problem, according to a first aspect of the present invention, there is provided a light source device comprising: a light source unit; a first optical element that diffuses light emitted from the light source unit along a first axis perpendicular to the optical axis of the light to generate a band-shaped illumination light extending along the first axis; and a second optical element that collimates the illumination light emitted from the first optical element in a direction along the first axis, wherein the first optical element moves in a plane perpendicular to the optical axis.

[0006] According to a second aspect of the present invention, there is provided a projector comprising the light source device of the first aspect, a light modulation device that modulates light incident from the light source device in accordance with image information, and a projection optical device that projects the light modulated by the light modulation device. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 2 is a plan view of the projector of the first embodiment as viewed from the +Y side. [Figure 2A] 10A and 10B are diagrams for explaining the behavior of illumination light when a transmissive optical element rotates. [Figure 2B] 10A and 10B are diagrams for explaining the behavior of illumination light when a transmissive optical element rotates. [Figure 2C] 10A and 10B are diagrams for explaining the behavior of illumination light when a transmissive optical element rotates. [Figure 2D] 10A and 10B are diagrams for explaining the behavior of illumination light when a transmissive optical element rotates. [Figure 2E] 10A and 10B are diagrams for explaining the behavior of illumination light when a transmissive optical element rotates. [Figure 2F] 10A and 10B are diagrams for explaining the behavior of illumination light when a transmissive optical element rotates. [Figure 3] FIG. 1 is a diagram illustrating the principle of reducing speckle noise. [Figure 4] 10 is a plan view showing a schematic configuration of a first optical element of a first modified example as viewed from the +Y side. FIG. [Figure 5] FIG. 10 is a plan view showing a schematic configuration of a first optical element of a second modified example as viewed from the −X side. [Figure 6] FIG. 10 is a diagram showing a schematic configuration of a first optical element of a third modified example. [Figure 7] FIG. 10 is a perspective view showing a schematic configuration of a light source device according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] (First embodiment) A first embodiment of the present invention will be described below with reference to the drawings. The projector of this embodiment is an example of a liquid crystal projector that uses a liquid crystal panel as a light modulation device. In the following drawings, the dimensions of some components may be shown at different scales to make them easier to see. In the following drawings, an XYZ Cartesian coordinate system will be used as necessary. The X axis is an axis parallel to the illumination optical axis of the light source device. The illumination optical axis is defined as the axis along the chief ray of the illumination light emitted from the light source device. The Z axis is an axis perpendicular to the X axis and is an axis along the rotation axis O of the transmitting optical element 41. The Y axis is an axis perpendicular to the X axis and Z axis. The Z axis in this embodiment corresponds to an example of the "first axis" in the present invention, and the Y axis in this embodiment corresponds to an example of the "second axis" in the present invention.

[0009] Hereinafter, when describing the configuration and arrangement of each component, one side (+X side) and the other side (-X side) along the X axis may be collectively referred to as the "X-axis direction," one side (+Y side) and the other side (-Y side) along the Y axis may be collectively referred to as the "Y-axis direction," and one side (+Z side) and the other side (-Z side) along the Z axis may be collectively referred to as the "Z-axis direction."

[0010] FIG. 1 is a plan view showing a schematic configuration of a projector according to this embodiment as viewed from the +Y side. As shown in FIG. 1, a projector 100 of this embodiment includes a light source device 1, a light modulation device 2, an incident-side polarizing plate 3a, an exit-side polarizing plate 3b, and a projection optical device 4.

[0011] The light source device 1 includes a light source section 10, a first optical element 20, a moving section 30, a second optical element 22, and a light scanning section . The light source unit 10 has a laser light emitting element 10a and a collimating lens 10b that collimates the light L made of laser light emitted from the laser light emitting element 10a. Therefore, the light source unit 10 emits high-intensity white light L made of laser light as parallel light. In this embodiment, the cross-sectional shape perpendicular to the principal ray of the light L emitted by the light source unit 10 is, for example, approximately square.

[0012] The first optical element 20 converts the light L emitted from the light source unit 10 into strip-shaped illumination light WL. The first optical element 20 diffuses the light L emitted from the light source unit 10 along the Z axis to generate a strip-shaped illumination light WL extending along the Z axis. That is, the first optical element 20 diffuses the light L in the Z axis direction perpendicular to the optical axis L1 of the light L, thereby expanding the luminous flux width of the light L in the Z axis direction. In this embodiment, the optical axis L1 of the light L emitted from the light source unit 10 coincides with the illumination optical axis AX of the light source device 1.

[0013] The first optical element 20 of this embodiment is a lenticular lens. The first optical element 20 includes multiple lenses 21 arranged in the Z-axis direction. Each lens 21 is a cylindrical convex lens that has positive power in the Z-axis direction and no power in the Y-axis direction. Therefore, each lens 21 splits the light L incident from the light source unit 10 into multiple ray bundles in the Z-axis direction. Each ray bundle is focused at a lens focus and then diverges in the Z-axis direction. The light L incident from the light source unit 10 passes through each lens 21 without changing its traveling direction in the Y-axis direction, which has no power. In this way, the first optical element 20 diffuses the light L emitted from the light source unit 10 in the Z-axis direction, generating a strip-shaped illumination light WL that is elongated in the Z-axis direction.

[0014] The second optical element 22 collimates, in the Z-axis direction, the illumination light WL emitted from the first optical element 20. The second optical element 22 is a cylindrical convex lens that has positive power in the Z-axis direction and no power in the Y-axis direction.

[0015] Light L emitted from the light source unit 10 passes through the first optical element 20 and the second optical element 22, and is converted into illumination light WL consisting of parallel light whose beam width in the Z-axis direction is expanded compared to before it entered the first optical element 20. The rate of change (degree of diffusion) of the beam width in the Z-axis direction in the first optical element 20 can be adjusted by adjusting the optical characteristics such as the curvature and refractive index of each lens 21 that constitutes the lenticular lens, for example.

[0016] The first optical element 20 is movable within a YZ plane perpendicular to the optical axis L1 and the illumination optical axis AX. In the light source device 1 of this embodiment, the moving unit 30 moves the first optical element 20 in the Z-axis direction. In this embodiment, the moving unit 30 is a voice coil motor. This allows the first optical element 20 to smoothly oscillate back and forth along the Z-axis. By oscillating the first optical element 20 in the Z-axis direction, the light source device 1 of this embodiment can reduce interference fringes and speckle noise in the illumination light WL, as described below.

[0017] The optical scanning unit 40 scans the illumination light WL incident from the second optical element 22 in the Y-axis direction in the illuminated region. Specifically, the optical scanning unit 40 scans the strip-shaped illumination light WL extending in the Z-axis direction in the light modulation region 2a of the light modulation device 2 arranged in the illuminated region in the Y-axis direction. Therefore, the optical scanning unit 40 can efficiently illuminate the entire light modulation region 2a by scanning the strip-shaped illumination light WL in the short-side direction.

[0018] In this embodiment, the optical scanning unit 40 scans the illumination light WL on the optical modulation device 2 along the short side direction of the illumination light WL. With this configuration, the illumination light WL and the optical modulation region 2a of the optical modulation device 2 can be aligned based on the longitudinal direction of the illumination light WL, which makes it easy to align the optical scanning unit 40 that emits the illumination light WL with the optical modulation device 2. This improves the combinability of the light source device 1.

[0019] The optical scanning unit 40 includes a transmissive optical element 41 and a rotation driving unit 45 . The transmissive optical element 41 is made of a rotatably supported light-transmitting member. The transmissive optical element 41 is rotatable about a rotation axis O extending along the Z-axis direction. The transmissive optical element 41 is connected to a rotation drive unit 45 formed of a motor or the like. The transmissive optical element 41 rotates about the rotation axis O by being driven by the rotation drive unit 45.

[0020] The transmissive optical element 41 is made of a transmissive material such as optical glass (e.g., BK7), quartz, or resin. The transmissive optical element 41 of this embodiment has a first surface 41a and a second surface 41b that intersect with the rotation axis O, and four side surfaces 41c that are perpendicular to the first surface 41a and the second surface 41b. That is, the shape of the transmissive optical element 41 is a regular rectangular prism having six flat surfaces, including the first surface 41a, the second surface 41b, and the four side surfaces 41c. The cross-sectional shape of the transmissive optical element 41 cut along a plane perpendicular to the rotation axis O is a square. That is, the four side surfaces 41c have the same area, and two opposing side surfaces are parallel to each other. The rotation axis O coincides with the center of the square-shaped transmissive optical element 41.

[0021] The transmissive optical element 41 rotates about the rotation axis O and transmits the illumination light WL emitted from the second optical element 22. Therefore, the side surface onto which the illumination light WL emitted from the second optical element 22 enters the transmissive optical element 41 is not fixed, but changes over time. Similarly, the side surface onto which the illumination light WL incident on the transmissive optical element 41 is emitted into external space is not fixed, but changes over time. In the transmissive optical element 41, the side surface onto which the illumination light WL emitted from the second optical element 22 enters is referred to as the "incident surface." The side surface from which the illumination light WL incident from the incident surface exits is referred to as the "exit surface." In this case, the incident surface and the exit surface change over time and are either two of the four side surfaces 41c that are parallel to each other.

[0022] In this specification, when two surfaces of the transmissive optical element 41 are said to be parallel to each other, the angle between the two surfaces is said to be in the range of 0±5 degrees, taking into consideration the processing accuracy of the glass material that makes up the translucent member, the allowable range of parallelism of light, etc.

[0023] In this embodiment, the transmissive optical element 41 has four side surfaces 41c, but the number of side surfaces does not necessarily have to be four, and is preferably 2×m (m: a natural number greater than or equal to 2). That is, the number of side surfaces is preferably an even number, such as 6 or 8. If the number of side surfaces is an even number, each of the side surfaces is parallel to the side surface opposite it, and there are no non-parallel side surfaces. This reduces the generation of stray light in the transmissive optical element 41, and improves light utilization efficiency.

[0024] The light modulation device 2 is provided on the light emission side of the second optical element 22 on the illumination optical axis AX. The light modulation device 2 modulates the illumination light WL emitted from the second optical element 22 in accordance with image information to form image light. A transmissive liquid crystal panel is used for the light modulation device 2. The liquid crystal panel may or may not include a color filter. If the liquid crystal panel includes a color filter, a projector 100 capable of color display can be realized. If the liquid crystal panel does not include a color filter, a projector 100 capable of monochrome display can be realized. The liquid crystal panel can be driven by any method, including twisted nematic (TN), vertical alignment (VA), and in-plane switching (IPS) methods, without any particular limitation.

[0025] The incident-side polarizing plate 3a is disposed on the light incident side of the light modulation device 2 along the illumination optical axis AX. The exit-side polarizing plate 3b is disposed on the light exit side of the light modulation device 2 along the illumination optical axis AX. The transmission axes of the incident-side polarizing plate 3a and the exit-side polarizing plate 3b are perpendicular to each other.

[0026] The incident-side polarizing plate 3a transmits a linearly polarized component of the illumination light WL emitted from the light source unit 10 in a specific direction toward the light modulation device 2. The exit-side polarizing plate 3b transmits the linearly polarized component of the illumination light WL in a specific direction toward the projection optical device 4. In this embodiment, the light source unit 10 uses a laser light-emitting element 10a, so the light L incident from the light source unit 10 is linearly polarized. However, in the transmissive optical element 41, as the amount of light transmitted through the translucent member increases, the amount of light absorbed by the translucent member also increases, which may cause thermal distortion in the translucent member. In this case, the polarization direction of the light L emitted from the light source unit 10 is disturbed, and the linearly polarized light incident on the translucent member becomes elliptically polarized and exits the translucent member. In this embodiment, the provision of the incident-side polarizing plate 3a allows the linearly polarized component in a specific direction to enter the light modulation device 2 even when the polarization direction of the light L is disturbed. In addition, if quartz, a glass material with a small Young's modulus and thermal expansion coefficient, is used as the transmitting optical element 41, it is less likely to cause disturbance in the polarization direction, so the incident-side polarizing plate 3a provided on the light incident side of the light modulation device 2 can be omitted.

[0027] The projection optical device 4 is composed of multiple projection lenses. The projection optical device 4 enlarges and projects the image light modulated by the light modulation device 2 onto a projection surface such as a screen, thereby displaying an image on the projection surface.

[0028] Next, the behavior of the illumination light WL by the transmissive optical element 41 of the optical scanning unit 40 will be described. 2A to 2F are schematic diagrams for explaining the behavior of the illumination light WL when the transmissive optical element 41 rotates. In this example, when viewed from the +Z side, the transmissive optical element 41 rotates clockwise around the rotation axis O, and time passes from FIG. 2A to FIG. 2F. The rotation driver 45 is not shown in FIGS. 2A to 2F.

[0029] 2A to 2F, the angle formed between the illumination optical axis AX and a straight line M that passes through the rotation axis O and is perpendicular to the side surface 41c1 of the transmissive optical element 41 is defined as the rotation angle ω of the transmissive optical element 41. In reality, the illumination light WL has a predetermined luminous flux width in the Z-axis direction, but here we will focus on the behavior of the light ray WL1, which is the chief ray traveling on the illumination optical axis AX.

[0030] 2A shows the initial state of the transmissive optical element 41. That is, the transmissive optical element 41 is not rotated, the straight line M and the illumination optical axis AX overlap, and the rotation angle ω is 0 degrees. In this case, the light ray WL1 is incident perpendicularly on the side surface 41c1, and therefore travels along the illumination optical axis AX inside the transmissive optical element 41 without being refracted at the side surface 41c1. Next, the light ray WL1 is also incident perpendicularly on the side surface 41c3 that is parallel to the side surface 41c1. Therefore, the light ray WL1 is emitted from the transmissive optical element 41 without being refracted at the side surface 41c3 either, and travels along the illumination optical axis AX.

[0031] Next, as shown in FIG. 2B , when the transmissive optical element 41 rotates by a rotation angle ω, the light ray WL1 is incident on the side surface 41c1 at an incident angle equal to the rotation angle ω. Therefore, the light ray WL1 is refracted in the direction shown in the figure (toward the +Z side) and travels inside the transmissive optical element 41. Next, the light ray WL1 is incident on the side surface 41c3 at a predetermined incident angle, so it is refracted at the side surface 41c3 and is emitted from the transmissive optical element 41. At this time, because the side surfaces 41c1 and 41c3 are parallel to each other, the incident angle of the light ray WL1 with respect to the side surface 41c1 and the incident angle of the light ray WL1 with respect to the side surface 41c3 are equal, and the refraction angle of the light ray WL1 incident on the side surface 41c1 and the refraction angle of the light ray WL1 emitted from the side surface 41c3 have opposite signs but equal absolute values. This causes the refraction angle of light ray WL1 when it enters side surface 41c1 to cancel out the refraction angle when it emerges from side surface 41c3. As a result, light ray WL1 travels parallel to the illumination optical axis AX at a position displaced by a displacement amount d from the illumination optical axis AX toward the +Z side.

[0032] Next, as shown in Figure 2C, when the rotation angle ω of the transmissive optical element 41 becomes larger than that of Figure 2B, the angle of incidence of the light ray WL1 becomes larger, and the angle of refraction also becomes larger. Therefore, the displacement d of the light ray WL1 from the illumination optical axis AX becomes larger than that of Figure 2B. Furthermore, the state in which the light ray WL1 travels parallel to the illumination optical axis AX is always maintained. When the rotation angle ω is between 0 degrees and 45 degrees, the displacement d increases monotonically as the rotation angle ω increases.

[0033] Next, as shown in FIG. 2D, when the rotation angle ω of the transmissive optical element 41 exceeds 45 degrees, the incident surface of the light ray WL1 changes from the side surface 41c1 to the side surface 41c2. At this time, the light ray WL1 is refracted at the side surface 41c2, but the refraction direction is different from that in the period up to FIG. 2C, and the light ray WL1 is refracted in the direction shown in the figure (toward the -Z side). The exit surface of the light ray WL1 also changes from the side surface 41c3 to the side surface 41c4. However, because the side surfaces 41c2 and 41c4 are parallel to each other, the refraction angle of the light ray WL1 when it enters the side surface 41c3 and the refraction angle when it exits the side surface 41c4 cancel each other out, as in the period up to FIG. 2C. As a result, the light ray WL1 travels parallel to the illumination optical axis AX at a position displaced by a displacement amount d toward the -Z side from the illumination optical axis AX.

[0034] Next, as shown in Fig. 2E, when the rotation angle ω of the transmissive optical element 41 becomes larger than that of Fig. 2D, the angle of incidence of the light ray WL1 becomes smaller, and the angle of refraction also becomes smaller. Therefore, the displacement d of the light ray WL1 from the illumination optical axis AX becomes smaller than that in Fig. 2D. In this way, when the rotation angle ω is between 45 degrees and 90 degrees, the displacement d monotonically decreases as the rotation angle ω increases.

[0035] Next, as shown in FIG. 2F, when the rotation angle ω of the transmissive optical element 41 reaches 90 degrees, the incident surface changes from the side surface 41c1 in the initial state to the side surface 41c2, but the behavior of the light ray WL1 becomes the same as in the initial state shown in FIG. 2A.

[0036] As described above, if the incident and exit surfaces of the transmissive optical element 41 are parallel to each other, the direction of travel of the light ray WL1 does not change regardless of the rotation angle ω of the transmissive optical element 41. Instead, the light ray WL1 translates parallel to the illumination optical axis AX over time. When the rotation angle ω is 0°, the displacement d of the light ray WL1 is 0. As the rotation angle ω ranges from 0° to 45°, the displacement d increases toward either the +Z or −Z direction. The moment the rotation angle ω exceeds 45°, the absolute value of the displacement d remains the same, but the direction of the displacement reverses. As the rotation angle ω ranges from 45° to 90°, the displacement d decreases. When the rotation angle ω reaches 90°, the displacement d becomes 0. After 90°, the above behavior is repeated. Therefore, when the transmissive optical element 41 rotates once, the displacement d of the light ray WL1 repeats the above cycle four times. The displacement of the light ray WL1 can be appropriately set by adjusting parameters such as the refractive index and size of the transmissive optical element 41.

[0037] The illumination light WL incident from the optical scanning unit 40 illuminates the light modulation region 2a of the light modulation device 2 so as to scan in the Y-axis direction. Therefore, the illumination light WL overlaps with each other in the Y-axis direction, which can improve the uniformity of the intensity distribution in the light modulation region 2a.

[0038] As described above, in the light source device 1 of this embodiment, the first optical element 20, which is made of a lenticular lens, includes a plurality of lenses 21. Since each lens 21 has the same shape, the first optical element 20 has a regular uneven structure. It is known that light that has passed through a regular uneven structure interferes with each other, causing interference fringes, and if such interference fringes appear in a projected image, the image quality of the viewed image will be significantly reduced.

[0039] In contrast, in the light source device 1 of this embodiment, the first optical element 20 is swung in the Z-axis direction by the moving unit 30. When the first optical element 20 moves in the Z-axis direction, the position at which the light L emitted from the light source unit 10 passes through the first optical element 20 changes over time. As a result, the interference fringes of the light L that has passed through the first optical element 20 change over time.

[0040] In the present embodiment, the first optical element 20 moves in the arrangement direction of the lenses 21, which efficiently changes the uneven structure through which the light L passes, thereby making it possible to increase the temporal change in the light L. Therefore, the interference fringes of the illumination light WL are time-averaged, making it possible to make the interference fringes in the projected image less visible.

[0041] Furthermore, in the light source device 1 of this embodiment, the light L emitted from the light source unit 10 is coherent light, which may cause speckles to appear in the projected image. Conventionally, a method for reducing speckle noise in a projected image by shaking the screen surface onto which the image is projected by the projector is known. However, because screens are generally large, it can be said that it is very difficult to realize a configuration that shakes the screen surface.

[0042] In contrast, in the light source device 1 of this embodiment, the first optical element 20 is swung, thereby making it possible to reduce speckle noise in the projected image. Here, the principle of reducing speckle noise by swinging the first optical element 20 will be described with reference to FIG.

[0043] When the position at which light L emitted from the light source unit 10 passes through the first optical element 20 changes over time, the image formed by the light L passing through the first optical element 20 changes over time, as shown in FIG. 3. The image of light L passing through the first optical element 20 is optically conjugate with the pupil image of the projection optical device 4. In other words, when the first optical element 20 moves, the pupil image of the projection optical device 4 changes over time. When the pupil image of the projection optical device 4 changes, the variation in the angle of light incident on the screen SCR changes, and the speckle pattern formed on the screen SCR also changes. It has been known that the more speckle patterns formed on the screen SCR there are, the more speckle noise can be reduced. As described above, according to the light source device 1 of this embodiment, by moving the first optical element 20, different speckle patterns are sequentially formed on the screen SCR, thereby reducing speckle noise.

[0044] As described above, the light source device 1 of this embodiment includes the light source unit 10, the first optical element 20 that diffuses the light L emitted from the light source unit 10 along the Z axis perpendicular to the optical axis L1 to generate strip-shaped illumination light WL extending along the Z axis, and the second optical element 22 that collimates the illumination light WL emitted from the first optical element 20 in the direction along the Z axis. The first optical element 20 is movable within the YZ plane perpendicular to the optical axis L1.

[0045] According to the light source device 1 of this embodiment, the first optical element 20 and the second optical element 22 can convert the light L emitted from the light source section 10 into strip-shaped illumination light WL that is elongated in the Z-axis direction. The illumination light WL extends in a strip-like shape in a direction perpendicular to the optical scanning direction by the optical scanning section 40. Therefore, the optical scanning section 40 can efficiently illuminate the entire light modulation region 2a of the light modulation device 2 with the illumination light WL.

[0046] The first optical element 20 of this embodiment has a regular uneven structure, which causes interference fringes in the illumination light WL, but in the light source device 1 of this embodiment, the first optical element 20 is swung by the moving unit 30, which makes it possible to change over time the interference fringes of the light L that has passed through the first optical element 20. This makes it possible to make the interference fringes in the projected image less visible by averaging the interference fringes of the illumination light WL over time.

[0047] Furthermore, in this embodiment, the light L emitted from the light source unit 10 is coherent light, which may cause speckles in the projected image. However, the light source device 1 of this embodiment can reduce speckle noise in the projected image by oscillating the first optical element 20.

[0048] According to the projector 100 of this embodiment, the illumination light WL emitted from the light source device 1 efficiently illuminates the light modulation area 2a of the light modulation device 2, so that it is possible to project a bright image. Furthermore, it is possible to project a high-quality image in which interference fringes and speckle noise in the projected image are suppressed.

[0049] (First Modification) A first modification of the first embodiment will be described below. This modified example differs from the first embodiment in the configuration of the first optical element. Note that the same reference numerals are used for members that are common to the first embodiment, and detailed descriptions thereof will be omitted.

[0050] Fig. 4 is a plan view showing a schematic configuration of the first optical element 120 of this modified example as viewed from the +Y side. As shown in Fig. 4, the first optical element 120 of this modified example has a plurality of first lens groups 121 and a plurality of second lens groups 122 arranged alternately in the Z axis direction. The first lens group 121 includes a plurality of first lenses 121a. Each of the first lenses 121a is a cylindrical convex lens that has positive power in the Z-axis direction and no power in the Y-axis direction. The second lens group 122 includes a plurality of second lenses 122a. Each of the second lenses 122a is a cylindrical convex lens that has positive power in the Z-axis direction and no power in the Y-axis direction.

[0051] First lens 121a has a first curvature in the Z-axis direction, and second lens 122a has a second curvature in the Z-axis direction that is different from the first curvature. In this modification, the first curvature of first lens 121a is smaller than the second curvature of second lens 122a. Furthermore, the first arrangement pitch P1 of adjacent first lenses 121a is narrower than the second arrangement pitch P2 of adjacent second lenses 122a.

[0052] The curvatures of first lens 121a and second lens 122a are adjusted so that the diffusion angle of light L transmitted through each first lens 121a and the diffusion angle of light L transmitted through each second lens 122a are constant.

[0053] In the first optical element 120 of this modification, the first lens group 121 and the second lens group 122 each have a regular concave-convex structure, and therefore, the light L that has passed through the first lens group 121 and the second lens group 122 generates interference fringes. In this modification as well, by swinging the first optical element 120 in the Z-axis direction, the interference fringes of the light L that has passed through the first optical element 120 can be changed over time.

[0054] In this modified example, the first lens group 121 and the second lens group 122 have different arrangement pitches P1, P2, and therefore the interference fringes caused by the first lens group 121 and the second lens group 122 are different from each other. Therefore, according to this modified example, by increasing the degree of change over time in the interference fringes of the light L that has passed through the first optical element 120, it is possible to make the interference fringes less visible in the projected image.

[0055] Also, in the first optical element 120 of this modified example, by swinging the first optical element 120, it is possible to reduce speckle noise in the projected image.

[0056] (Second Modification) A second modification of the first embodiment will now be described. This modified example differs from the first embodiment in the configuration of the first optical element. Note that the same reference numerals are used for members that are common to the first embodiment, and detailed descriptions thereof will be omitted.

[0057] Fig. 5 is a plan view showing a schematic configuration of the first optical element 220 of this modified example as viewed from the -X side. As shown in Fig. 5, the first optical element 220 of this modified example has a third lens group 223 and a fourth lens group 224 arranged side by side in the Y axis direction. The third lens group 223 includes a plurality of third lenses 223a. Each of the third lenses 223a is a cylindrical convex lens that has positive power in the Z-axis direction and no power in the Y-axis direction. The fourth lens group 224 includes a plurality of fourth lenses 224a. Each fourth lens 224a is a cylindrical convex lens that has positive power in the Z-axis direction and no power in the Y-axis direction.

[0058] The third lens 223a has a third curvature in the Z-axis direction, and the fourth lens 224a has a fourth curvature in the Z-axis direction that is different from the third curvature. In this modification, the third curvature of the third lens 223a is smaller than the fourth curvature of the fourth lens 224a. The third arrangement pitch P3 of adjacent third lenses 223a is narrower than the fourth arrangement pitch P4 of adjacent fourth lenses 224a.

[0059] The curvatures of the third lens 223a and the fourth lens 224a are adjusted so that the diffusion angle of the light L transmitted through each third lens 223a and the diffusion angle of the light L transmitted through each fourth lens 224a are constant.

[0060] In the first optical element 220 of this modification, the third lens group 223 and the fourth lens group 224 each have a regular concave-convex structure, and therefore, light L that has passed through the third lens group 223 and the fourth lens group 224 generates interference fringes. In this modification as well, by swinging the first optical element 220 in the Z-axis direction, it is possible to change the interference fringes of the light L that has passed through the first optical element 220 over time. In addition, it is possible to reduce speckle noise in the projected image.

[0061] The third lens group 223 and the fourth lens group 224 have different arrangement pitches P3 and P4, and therefore the interference fringes produced by the third lens group 223 and the fourth lens group 224 are different from each other. Therefore, according to this modification, by increasing the degree of change over time in the interference fringes of the light L transmitted through the first optical element 220, it is possible to make the interference fringes less visible in the projected image.

[0062] Furthermore, the first optical element 220 of this modified example can be easily manufactured by bonding together the lenticular lens made up of the third lens group 223 and the lenticular lens made up of the fourth lens group 224 in the Y-axis direction.

[0063] In addition, when different lens groups are arranged in the Y-axis direction as in the first optical element 220 of this modified example, the first optical element 220 may be moved, for example, in the Y-axis direction rather than the Z-axis direction within the YZ plane perpendicular to the optical axis L1.

[0064] (Third Modification) A third modified example of the first embodiment will be described below. This modified example differs from the first embodiment in the configuration of the first optical element. Note that the same reference numerals are used for members that are common to the first embodiment, and detailed descriptions thereof will be omitted.

[0065] Fig. 6 is a diagram showing a schematic configuration of the first optical element 320 of this modified example. The upper part of Fig. 6 is a plan view of the first optical element 320 viewed from the +Y side, and the lower part of Fig. 6 is a plan view of the first optical element 320 viewed from the -Z side.

[0066] 6, the first optical element 320 of this modification includes a plurality of lenses 321 arranged in the Z-axis direction. Each lens 321 is a toric lens that has positive power in both the Y-axis direction and the Z-axis direction and has different powers in the Y-axis direction and the Z-axis direction.

[0067] Each lens 321 splits the light L incident from the light source unit 10 into multiple bundles of rays in the Z-axis direction. Each bundle of rays is collected at the lens focal point and then diverges in the Z-axis direction and the Y-axis direction. The first optical element 320 diffuses the light L emitted from the light source unit 10 in the Y-axis direction in addition to the Z-axis direction.

[0068] The first optical element 320 of this modification has a first diffusion angle along the Z-axis direction and a second diffusion angle along the Y-axis direction, the second diffusion angle being smaller than the first diffusion angle. In this modification, the curvature of each lens 321 in the Z-axis direction is smaller than the curvature in the Y-axis direction. For this reason, the first optical element 320 of this modification diffuses the light L emitted from the light source unit 10 largely in the Z-axis direction and less in the Y-axis direction than in the Z-axis direction, generating strip-shaped illumination light WL that is elongated in the Z-axis direction. The illumination light WL generated in this modification has a strip-like shape with a smaller difference between the long side and the short side compared to the first embodiment.

[0069] In this modification, the first optical element 320 moves in two directions along the Z axis and the Y axis. In this modification, the moving section 30 swings the first optical element 320 in two directions, along the Z axis and the Y axis.

[0070] According to the first optical element 320 of this modification, by moving it in two directions, the Z-axis direction and the Y-axis direction, it is possible to further increase the change over time in the interference fringes of the light L transmitted through the first optical element 320. Therefore, it is possible to more effectively reduce the interference fringes and speckle noise in the projected image.

[0071] (Second embodiment) A second embodiment of the present invention will now be described. The configuration of the light source device in this embodiment is different from that in the first embodiment. Note that the same reference numerals are used for the members common to the first embodiment, and detailed descriptions thereof will be omitted.

[0072] 7 is a perspective view showing a schematic configuration of a light source device 201 of this embodiment. As shown in FIG. 7, the light source device 201 of this embodiment has a light source unit 10, a first optical element 420, a substrate 421, a drive unit 430, a second optical element 22, and an optical scanning unit 40.

[0073] The first optical element 420 is disposed on a substrate 421, which is a circular plate. The first optical element 420 is disposed in an annular (ring-shaped) shape along the circumferential direction of the substrate 421. The first optical element 420 is a lenticular lens, and includes a plurality of lenses 420a arranged in the circumferential direction of the substrate 421. Each lens 420a is a cylindrical convex lens that has positive power in the circumferential direction and no power in the radial direction. Each lens 420a has a substantially trapezoidal planar shape when viewed in a plane in the X-axis direction. The driving unit 430 is a motor that rotates the substrate 421 around the center 421C of the substrate 421 as the rotation axis.

[0074] Here, the closer the first optical element 420 is positioned to the center 421C of the substrate 421, the smaller the curvature of the first optical element 420. As a result, the light L diffused by passing through each lens 420a of the first optical element 420 is distorted into a U-shape, and the distortion of the illumination light WL also increases.

[0075] In contrast, the first optical element 420 of this embodiment is disposed closer to the outer circumferential edge 421a in the radial direction of the substrate 421 than the midpoint P between the center 421C of the substrate 421 and the outer circumferential edge 421a of the substrate 421. With this configuration, the curvature of the first optical element 420 can be increased, thereby reducing distortion that occurs in the light L that has passed through each lens 420a of the first optical element 420. Therefore, it is possible to generate illumination light WL that extends in a band shape in the Z-axis direction with reduced distortion.

[0076] As described above, according to the light source device 201 of this embodiment, the light L emitted from the light source unit 10 is diffused along the Z axis by the first optical element 420, thereby generating a strip-shaped illumination light WL extending along the Z axis. Furthermore, the light source device 201 rotates the substrate 421 to move the first optical element 420 circumferentially within a plane perpendicular to the optical axis L1. This causes the position at which the light L emitted from the light source unit 10 passes through the first optical element 420 to change over time, thereby changing the interference fringes of the light L over time. In this embodiment, the first optical element 420 rotates in the arrangement direction of the lenses 420a, thereby efficiently changing the concavo-convex structure through which the light L passes, thereby increasing the temporal change in the light L. Therefore, by averaging the interference fringes of the illumination light WL over time, the interference fringes in the projected image can be made less visible. Furthermore, in the light source device 201 of this embodiment, by rotating the first optical element 420, speckle noise in the projected image can also be reduced.

[0077] The technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. In addition, the specific descriptions of the shape, number, arrangement, material, etc. of each component of the light source device and projector are not limited to the above-described embodiments and can be changed as appropriate.

[0078] For example, in the first embodiment, a lenticular lens is used as the first optical element 20 that diffuses the light L emitted from the light source unit 10 in the Z-axis direction, but the first optical element of the present invention may also be a diffusion plate that has anisotropic diffusion characteristics, having diffusion properties in the Z-axis direction but not light diffusion properties in the Y-axis direction.

[0079] A summary of this disclosure is provided below.

[0080] (Appendix 1) A light source unit; a first optical element that diffuses the light emitted from the light source unit along a first axis perpendicular to an optical axis of the light, and generates a strip-shaped illumination light extending along the first axis; a second optical element that collimates the illumination light emitted from the first optical element in a direction along the first axis, the first optical element moves in a plane perpendicular to the optical axis; Light source device.

[0081] According to the light source device having this configuration, the first optical element and the second optical element can convert the light emitted from the light source unit into a strip-shaped illumination light that is long in the first axis direction. The first optical element has a regular uneven structure that generates interference fringes in the illumination light, but in the light source device having this configuration, by moving the first optical element, the interference fringes of the light that has passed through the first optical element can be changed over time. This makes it possible to make the interference fringes less visible by averaging the interference fringes of the illumination light over time.

[0082] (Appendix 2) The first optical element is a lenticular lens. 10. The light source device of claim 1.

[0083] According to this configuration, it is possible to effectively generate a strip-shaped illumination light that is long in the first axis direction.

[0084] (Appendix 3) the first optical element includes a first lens group including a plurality of first lenses having a first curvature, and a second lens group including a plurality of second lenses having a second curvature different from the first curvature; the first lens group and the second lens group are arranged in a direction along the first axis, an arrangement pitch of the plurality of first lenses in the first lens group is different from an arrangement pitch of the plurality of second lenses in the second lens group; 10. The light source device according to claim 2.

[0085] With this configuration, the first lens group and the second lens group have different arrangement pitches, and therefore the interference fringes produced by the first lens group and the second lens group are different from each other. Therefore, by increasing the degree of temporal change in the interference fringes of the light transmitted through the first optical element, it is possible to make the interference fringes of the illumination light less visible.

[0086] (Appendix 4) the first optical element also diffuses the light emitted from the light source unit in a direction along a second axis perpendicular to the first axis, the first optical element has a first diffusion angle along the first axis and a second diffusion angle along the second axis; The second diffusion angle is smaller than the first diffusion angle. 10. The light source device according to claim 1 or 2.

[0087] According to this configuration, the light emitted from the light source section is diffused in two directions, thereby generating a desired strip-shaped illumination light.

[0088] (Appendix 5) the first optical element moves in two directions along the first axis and the second axis; 5. The light source device according to claim 4.

[0089] According to this configuration, by oscillating the first optical element in two directions, it is possible to increase the temporal change in the interference fringes of the light transmitted through the first optical element, thereby making the interference fringes less visible.

[0090] (Appendix 6) The light source unit includes a laser light emitting element. 6. A light source device according to any one of claims 1 to 5.

[0091] According to this configuration, the light source section can emit light with high brightness.

[0092] (Appendix 7) further comprising a moving unit that moves the first optical element; The moving part is a voice coil motor. 7. A light source device according to any one of claims 1 to 6.

[0093] According to this configuration, the first optical element can be smoothly oscillated in one axial direction by the voice coil motor.

[0094] (Appendix 8) the first optical element includes a third lens group including a plurality of third lenses having a third curvature, and a fourth lens group including a plurality of fourth lenses having a fourth curvature different from the third curvature, the third lens group and the fourth lens group are arranged side by side in a direction perpendicular to the first axis and the optical axis, an arrangement pitch of the plurality of third lenses in the third lens group is different from an arrangement pitch of the plurality of fourth lenses in the fourth lens group; 10. The light source device according to claim 2.

[0095] With this configuration, the third lens group and the fourth lens group have different arrangement pitches, so the interference fringes produced by the third lens group and the fourth lens group are different from each other. Therefore, by increasing the degree of temporal change in the interference fringes of the light transmitted through the first optical element, the interference fringes of the illumination light can be made less visible. Furthermore, by bonding the third lens group and the fourth lens group together, the first optical element can be easily manufactured.

[0096] (Appendix 9) a substrate on which the first optical element is disposed; a drive unit that rotates the substrate around the center of the substrate as a rotation axis, 10. The light source device according to claim 1 or 2.

[0097] According to this configuration, by rotating the substrate, it is possible to move the first optical element within a plane perpendicular to the optical axis.

[0098] (Appendix 10) the substrate is a disk; the first optical element is arranged annularly along the circumferential direction of the substrate; 10. The light source device according to claim 9.

[0099] According to this configuration, the first optical element can be moved in the circumferential direction of the substrate within a plane perpendicular to the optical axis. This causes the position at which the light emitted from the light source passes through the first optical element to change over time, thereby changing the interference fringes of the light over time. This makes it possible to make the interference fringes less visible by averaging the interference fringes of the illumination light over time.

[0100] (Appendix 11) the first optical element is disposed on the outer periphery side of the substrate relative to a midpoint between the center of the substrate and the outer periphery in the radial direction of the substrate; 11. The light source device of claim 10.

[0101] With this configuration, the curvature of the first optical element can be increased, thereby reducing distortion in the light transmitted through the first optical element, thereby effectively generating illumination light that extends in a strip shape in the first axis direction with reduced distortion.

[0102] (Appendix 12) further comprising a light scanning unit that scans the illumination light incident from the second optical element in a direction perpendicular to the first axis and the optical axis; 12. A light source device according to any one of claims 1 to 11.

[0103] With this configuration, the optical scanning unit can scan the illuminated area with a strip-shaped illumination light. The illumination light extends in a strip-like shape in a direction perpendicular to the optical scanning direction of the optical scanning unit. Therefore, the optical scanning unit can efficiently illuminate the rectangular illuminated area with the strip-shaped illumination light.

[0104] (Appendix 13) a light source device according to any one of Supplementary Note 1 to Supplementary Note 12; a light modulation device that modulates the light incident from the light source device in accordance with image information; a projection optical device that projects the light modulated by the light modulation device; Equipped with projector.

[0105] With this configuration, the projector can project bright images because the illumination light emitted from the light source device efficiently illuminates the light modulation device, and can also project high-quality images with reduced interference fringes and speckle noise. [Explanation of symbols]

[0106] 1,201,401...light source device, 2...light modulation device, 4...projection optical device, 10...light source section, 10a...laser light emitting element, 20,120,220,320,420...first optical element, 21,321,421...lens, 22...second optical element, 30...moving section, 40...light scanning section, 100...projector, 121...first lens group, 121a...first lens, 122...second lens group, 122a...second lens, 223...third lens group, 223a...third lens, 224...fourth lens group, 224a...fourth lens, 421...substrate, 421a...outer edge, 421C...center, 430...drive section, L...light, L1...optical axis, O...rotation axis, P...midpoint, P1...pitch, WL...illumination light.

Claims

1. A light source unit; a first optical element that diffuses the light emitted from the light source unit along a first axis perpendicular to an optical axis of the light, and generates a strip-shaped illumination light extending along the first axis; a second optical element that collimates the illumination light emitted from the first optical element in a direction along the first axis, the first optical element moves in a plane perpendicular to the optical axis; Light source device.

2. The first optical element is a lenticular lens. The light source device according to claim 1 .

3. the first optical element includes a first lens group including a plurality of first lenses having a first curvature, and a second lens group including a plurality of second lenses having a second curvature different from the first curvature; the first lens group and the second lens group are arranged in a direction along the first axis, an arrangement pitch of the plurality of first lenses in the first lens group is different from an arrangement pitch of the plurality of second lenses in the second lens group; The light source device according to claim 2 .

4. the first optical element also diffuses the light emitted from the light source unit in a direction along a second axis perpendicular to the first axis, the first optical element has a first diffusion angle along the first axis and a second diffusion angle along the second axis; The second diffusion angle is smaller than the first diffusion angle. The light source device according to claim 1 .

5. the first optical element moves in two directions along the first axis and the second axis; The light source device according to claim 4 .

6. The light source unit includes a laser light emitting element.

3. The light source device according to claim 1.

7. a moving unit that moves the first optical element, The moving part is a voice coil motor.

3. The light source device according to claim 1.

8. the first optical element includes a third lens group including a plurality of third lenses having a third curvature, and a fourth lens group including a plurality of fourth lenses having a fourth curvature different from the third curvature, the third lens group and the fourth lens group are arranged side by side in a direction perpendicular to the first axis and the optical axis, an arrangement pitch of the plurality of third lenses in the third lens group is different from an arrangement pitch of the plurality of fourth lenses in the fourth lens group; The light source device according to claim 2 .

9. a substrate on which the first optical element is disposed; a drive unit that rotates the substrate around the center of the substrate as a rotation axis, 3. The light source device according to claim 1.

10. the substrate is a disk; the first optical element is arranged annularly along the circumferential direction of the substrate; The light source device according to claim 9 .

11. the first optical element is disposed on the outer periphery side of the substrate relative to a midpoint between the center of the substrate and the outer periphery of the substrate in a radial direction of the substrate; The light source device according to claim 10.

12. further comprising a light scanning unit that scans the illumination light incident from the second optical element in a direction perpendicular to the first axis and the optical axis; 3. The light source device according to claim 1.

13. The light source device according to claim 1 or 2; a light modulation device that modulates the light incident from the light source device in accordance with image information; a projection optical device that projects the light modulated by the light modulation device; Equipped with projector.

Images