Light source device and projector

Abstract

To provide a light source device and a projector capable of generating illumination light having a predetermined aspect ratio.SOLUTION: A light source device according to an aspect of the invention includes a light source section, a light conversion section adapted to convert light emitted from the light source section into illumination light having a rectangular shape, and a light scanning section adapted to scan the illumination light in an illumination target area. A second optical system that changes a luminous flux width of the light in a second direction orthogonal to the first direction, the first optical system including a first optical element that expands the light emitted from the light source unit in the first direction and a second optical element that collimates the light emitted from the first optical element in the first direction; The second optical system includes a third optical element that enlarges the light outputted from the light source section in the second direction and a fourth optical element that parallelizes the light outputted from the third optical element in the second direction, and the second optical system is disposed between the first optical element and the second optical element.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 on the liquid crystal light valve, making it difficult to make illumination light with the desired aspect ratio incident on the light modulation area of ​​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 light conversion unit that converts light emitted from the light source unit into rectangular illumination light; and a light scanning unit that scans the illumination light over an illuminated area, wherein the light conversion unit has a first optical system that changes a beam width of the light emitted from the light source unit in a first direction that is perpendicular to the direction in which the light source unit emits the light; and a second optical system that changes a beam width of the light emitted from the light source unit in a second direction that is perpendicular to the first direction, wherein the first optical system includes a first optical element that expands the light emitted from the light source unit in the first direction and a second optical element that collimates the light emitted from the first optical element in the first direction, wherein the second optical system includes a third optical element that expands the light emitted from the light source unit in the second direction and a fourth optical element that collimates the light emitted from the third optical element in the second direction, and the second optical system is disposed between the first optical element and the second optical element.

[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 2] FIG. 2 is a plan view of the projector of the first embodiment as viewed from the +Z side. [Figure 3] 10 is a simulation result showing the intensity distribution of light emitted from the optical conversion unit. [Figure 4A] 10A and 10B are diagrams for explaining the behavior of illumination light when a transmissive optical element rotates. [Figure 4B] 10A and 10B are diagrams for explaining the behavior of illumination light when a transmissive optical element rotates. [Figure 4C] 10A and 10B are diagrams for explaining the behavior of illumination light when a transmissive optical element rotates. [Figure 4D] 10A and 10B are diagrams for explaining the behavior of illumination light when a transmissive optical element rotates. [Figure 4E] 10A and 10B are diagrams for explaining the behavior of illumination light when a transmissive optical element rotates. [Figure 4F] 10A and 10B are diagrams for explaining the behavior of illumination light when a transmissive optical element rotates. [Figure 5A] FIG. 10 is a plan view of the light conversion unit according to the second embodiment, viewed from the +Y side. [Figure 5B] FIG. 10 is a plan view of the optical conversion unit according to the second embodiment, viewed from the +Z side. [Figure 6A] FIG. 11 is a plan view of the light conversion unit according to the third embodiment, viewed from the +Y side. [Figure 6B] FIG. 11 is a plan view of the optical conversion unit according to the third embodiment, viewed from the +Z side. 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 13. The Y axis is an axis perpendicular to the X axis and the Z axis. The Z-axis direction in this embodiment corresponds to an example of the "first direction" in the present invention, and the Y-axis direction in this embodiment corresponds to an example of the "second direction" in the present invention.

[0009] Fig. 1 is a plan view showing a schematic configuration of a projector of this embodiment when viewed from the +Y side, and Fig. 2 is a plan view showing a schematic configuration of a projector of this embodiment when viewed from the +Z side. As shown in FIGS. 1 and 2, a projector 100 of this embodiment includes a light source device 1, a light modulation device 2, an exit-side polarizing plate 3, and a projection optical device 4.

[0010] The light source device 1 includes a light source unit 10 , a light conversion unit 11 , and a light scanning unit 12 . The light source unit 10 emits white light L as parallel light. The light source unit 10 is a laser light emitting element. Therefore, the light source unit 10 can emit high-intensity light L. In this embodiment, the cross section perpendicular to the principal ray of the light L emitted by the light source unit 10 is approximately square.

[0011] The light conversion unit 11 converts the light L emitted from the light source unit 10 into rectangular illumination light WL. The light conversion unit 11 has a first optical system 20 and a second optical system 30. The first optical system 20 changes the beam width of the light L emitted from the light source unit 10 in the Z-axis direction. The second optical system 30 changes the beam width of the light L emitted from the light source unit 10 in the Z-axis direction, which is perpendicular to the Y-axis direction.

[0012] The first optical system 20 includes a first optical element 21 and a second optical element 22 . The first optical element 21 expands the light L emitted from the light source unit 10 in the Z-axis direction. The first optical element 21 in this embodiment is a Powell lens. A Powell lens is an aspheric cylindrical lens that has positive power in the Z-axis direction but no power in the Y-axis direction. Therefore, as shown in FIG. 1, the first optical element 21 made of a Powell lens diverges the light L incident from the light source unit 10 in a fan shape in the Z-axis direction and converts it into light having a highly uniform light intensity distribution. Note that, as shown in FIG. 2, the light L emitted from the first optical element 21 does not change its traveling direction in the Y-axis direction, which has no power.

[0013] The second optical element 22 collimates the light L emitted in a divergent state from the first optical element 21 in the Z-axis direction. The second optical element 22 of this embodiment is a cylindrical lens, more specifically, a cylindrical convex lens. The second optical element 22, which is made of a cylindrical convex lens, has no power in the Y-axis direction and positive power in the Z-axis direction. Therefore, the second optical element 22 collimates the light L emitted from the first optical element 21 in the Z-axis direction. Note that, as shown in FIG. 2, the light L incident from the first optical element 21 passes through the second optical element 22 without changing its traveling direction in the Y-axis direction, which has no power.

[0014] The second optical system 30 is disposed between the first optical element 21 and the second optical element 22. The second optical system 30 includes a third optical element 31 and a fourth optical element 32. The third optical element 31 expands the light L emitted from the light source unit 10 in the Y-axis direction. The third optical element 31 of this embodiment is a Powell lens, which has positive power in the Y-axis direction but no power in the Z-axis direction. In other words, the third optical element 31 and the first optical element 21 have a relationship in which the directions of lens power are perpendicular to each other. Therefore, as shown in FIG. 2, the third optical element 31 diverges the light L incident from the first optical element 21 in a fan-like manner in the Y-axis direction and converts it into light having a highly uniform light intensity distribution. Note that, as shown in FIG. 1, the light L emitted from the third optical element 31 passes through the third optical element 31 without changing its traveling direction in the Z-axis direction, which has no power.

[0015] The fourth optical element 32 collimates the light L emitted from the third optical element 31 in a divergent state in the Z-axis direction. The fourth optical element 32 of this embodiment is a cylindrical lens, more specifically a cylindrical convex lens, which has no power in the Z-axis direction and positive power in the Y-axis direction. Therefore, the fourth optical element 32 collimates the light L emitted from the third optical element 31 in the Y-axis direction. Note that, as shown in FIG. 1 , the light L incident from the third optical element 31 passes through the fourth optical element 32 without changing its traveling direction in the Z-axis direction, which has no power.

[0016] The light L emitted from the light source unit 10 passes through the first optical element 21 and the second optical element 22 of the first optical system 20, so that the beam width before entering the first optical system 20 is expanded in the Z-axis direction and the light is collimated in the Z-axis direction. The rate of change of the beam width in the Z-axis direction in the first optical system 20 can be adjusted by adjusting the optical properties such as the focal length and refractive index of the first optical element 21 and the second optical element 22, for example.

[0017] Furthermore, the light L emitted from the light source unit 10 passes through the third optical element 31 and the fourth optical element 32 of the second optical system 30, so that the width of the light beam before entering the second optical system 30 is expanded in the Y-axis direction and the light is collimated in the Y-axis direction. The rate of change of the light beam width in the Y-axis direction in the second optical system 30 can be adjusted by adjusting the optical properties such as the focal length and refractive index of the third optical element 31 and the fourth optical element 32, for example.

[0018] In this specification, the aspect ratio is the ratio of the longitudinal length to the lateral length of the cross-section of light perpendicular to the optical axis. Therefore, light with a large aspect ratio has a more elongated cross-sectional beam shape than light with a small aspect ratio.

[0019] As described above, the cross section perpendicular to the principal ray of the light L emitted from the light source unit 10 is approximately square, and the light beam width in the Y-axis direction and the light beam width in the Z-axis direction of the light L when emitted from the light source unit 10 are equal to each other.

[0020] In the light converting unit 11 of this embodiment, the rate of change of the light flux width in the Y-axis direction in the second optical system 30 is smaller than the rate of change of the light flux width in the Z-axis direction in the first optical system 20. Therefore, the illumination light WL whose light flux width has been converted by the light converting unit 11 becomes light having an aspect ratio in which the light flux width in the Z-axis direction is larger than the light flux width in the Y-axis direction. In other words, the light converting unit 11 converts the light L incident from the light source unit 10 into illumination light WL with a large aspect ratio.

[0021] Here, the distance between the first optical element 21 and the second optical element 22 that constitute the first optical system 20, which has a large rate of change of the light beam width, is shorter than the distance between the third optical element 31 and the fourth optical element 32 that constitute the second optical system 30, which has a small rate of change of the light beam width. In the light conversion unit 11 of this embodiment, the second optical system 30 is disposed between the first optical element 21 and the second optical element 22, and therefore the gap generated between the first optical element 21 and the second optical element 22 can be effectively utilized as installation space for the second optical system 30. Therefore, according to the light conversion unit 11 of this embodiment, it is possible to reduce the space required in the direction along the illumination optical axis AX compared to when the first optical system 20 and the second optical system 30 are disposed in series, thereby making it possible to miniaturize the device configuration.

[0022] 3 shows the results of a simulation illustrating changes in the intensity distribution of light emitted from the optical conversion unit 11. FIG. 3 illustrates intensity distributions corresponding to a first position P1, a second position P2, a third position P3, and a fourth position P4 in FIGS. 1 and 2. The first position P1 corresponds to the light L before it enters the optical conversion unit 11, the second position P2 corresponds to the light L between the third optical element 31 and the fourth optical element 32, the third position P3 corresponds to the light L between the fourth optical element 32 and the second optical element 22, and the fourth position P4 corresponds to the illumination light WL emitted from the optical conversion unit 11. The intensity distribution along the Z-axis direction is shown to the right of the intensity distributions at each of the positions P1 to P4, and the intensity distribution along the Y-axis direction is shown below the intensity distributions at each of the positions P1 to P4.

[0023] As shown in Figure 3, according to a simulation conducted by the inventor, the cross-sectional shape of the light is square at the first position P1, which is the stage before it enters the optical conversion unit 11, but as it moves to the second position P2 and the third position P3, the cross-sectional shape of the light changes to a shape elongated in the Z-axis direction, and it was confirmed that the light becomes rectangular with a predetermined aspect ratio at the fourth position P4 after being emitted from the optical conversion unit 11.

[0024] In this way, according to the light conversion unit 11 of this embodiment, the light L emitted from the light source unit 10 can be converted into rectangular illumination light WL having a predetermined aspect ratio by expanding the luminous flux width in the Y-axis and Z-axis directions and collimating it.

[0025] The optical scanning unit 12 is provided on the illumination optical axis AX between the optical conversion unit 11 and the optical modulation device 2. The optical scanning unit 12 scans the illumination light WL incident from the optical conversion unit 11 over the illuminated region. Specifically, the optical scanning unit 12 scans the rectangular illumination light WL extending in the Y-axis direction in the Z-axis direction in the optical modulation region 2c of the optical modulation device 2 arranged in the illuminated region. Therefore, the optical scanning unit 12 can irradiate the entire optical modulation region 2c by scanning the rectangular illumination light WL in one axial direction. In this embodiment, the optical scanning unit 12 scans the illumination light WL along the direction of the short side of the aspect ratio of the illumination light WL. With this configuration, the illumination light WL can be aligned with the optical modulation region 2c of the optical modulation device 2 based on the direction of the long side of the aspect ratio of the illumination light WL, making it easy to align the optical scanning unit 12 that emits the illumination light WL with the optical modulation device 2. This improves the combinability of the light source device 1.

[0026] The light modulation device 2 is provided on the light emission side of the light source device 1 on the illumination optical axis AX. The light modulation device 2 modulates the illumination light WL emitted from the light source device 1 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.

[0027] The exit-side polarizing plate 3 is provided on the illumination optical axis AX between the light modulation device 2 and the projection optical device 4. The exit-side polarizing plate 3 transmits linearly polarized light in a specific direction that is emitted from the light modulation device 2 toward the projection optical device 4. In the case of this embodiment, a laser light-emitting element is used as the light source unit 10, so linearly polarized light is emitted from the light source device 1. Therefore, the entrance-side polarizing plate that is provided on the light entrance side of the light modulation device 2 can be omitted.

[0028] 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.

[0029] The optical scanning unit 12 includes a transmission optical element 13 and a rotation driving unit 14 . The transmitting optical element 13 is composed of a rotatably supported light-transmitting member. The transmitting optical element 13 is rotatable about a rotation axis O extending along the Z-axis direction. The transmitting optical element 13 is connected to a rotation drive unit 14 formed of a motor or the like. The transmitting optical element 13 rotates about the rotation axis O by being driven by the rotation drive unit 14.

[0030] The transmissive optical element 13 is made of a transmissive material such as optical glass (e.g., BK7), quartz, or resin. The transmissive optical element 13 of this embodiment has a first surface 13a and a second surface 13b that intersect with the rotation axis O, and four side surfaces 13c that are perpendicular to the first surface 13a and the second surface 13b. That is, the shape of the transmissive optical element 13 is a regular rectangular prism having six flat surfaces, including the first surface 13a, the second surface 13b, and the four side surfaces 13c. The cross-sectional shape of the transmissive optical element 13 cut along a plane perpendicular to the rotation axis O is a square. That is, the four side surfaces 13c 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 13.

[0031] The transmissive optical element 13 rotates around the rotation axis O and transmits the illumination light WL emitted from the light conversion unit 11. Therefore, the side surface onto which the illumination light WL emitted from the light conversion unit 11 enters the transmissive optical element 13 is not fixed, but changes over time. Similarly, the side surface onto which the illumination light WL incident on the transmissive optical element 13 is emitted into external space is not fixed, but changes over time. In the transmissive optical element 13, the side surface onto which the illumination light WL emitted from the light conversion unit 11 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 13c that are parallel to each other.

[0032] In this specification, when two surfaces of the transmissive optical element 13 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.

[0033] In this embodiment, the transmissive optical element 13 has four side surfaces 13c, 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, for example, 6, 8, or the like. 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 13, and improves light utilization efficiency.

[0034] The transmissive optical element 13 may be made of quartz. In the transmissive optical element 13, as the amount of light transmitted through the light-transmitting member increases, the amount of light absorbed by the light-transmitting member also increases, which may cause thermal distortion in the light-transmitting member. In this case, the polarization direction of the light L emitted from the light source unit 10 is disturbed, and linearly polarized light incident on the light-transmitting member becomes elliptically polarized light and is emitted from the light-transmitting member. As a result, the effect of obtaining a predetermined contrast without an incident-side polarizing plate by using a laser light-emitting element in the light source unit 10 of the projector 100 is lost. In other words, even though the light source unit 10 uses a laser diode, an incident-side polarizing plate is required to align the polarization direction. Therefore, to achieve the above effect, it is desirable to use a glass material with a small Young's modulus and thermal expansion coefficient as a glass material with little thermal distortion, and quartz is a desirable example.

[0035] The behavior of the illumination light WL when it passes through the transmission optical element 13 will be described below. 4A to 4F are schematic diagrams for explaining the behavior of the illumination light WL when the transmissive optical element 13 rotates. In this example, when viewed from the +Z side, the transmissive optical element 13 rotates clockwise around the rotation axis O, and the state shown is one in which time has passed from FIG. 4A to FIG. 4F. The rotation driver 14 is not shown in FIGS. 4A to 4F.

[0036] 4A to 4F, the angle 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 13c1 of the transmissive optical element 13 is defined as the rotation angle ω of the transmissive optical element 13. 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.

[0037] 4A shows the initial state of the transmissive optical element 13. That is, the transmissive optical element 13 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 13c1, and therefore travels along the illumination optical axis AX inside the transmissive optical element 13 without being refracted at the side surface 13c1. Next, the light ray WL1 is also incident perpendicularly on the side surface 13c3, which is parallel to the side surface 13c1. Therefore, the light ray WL1 is emitted from the transmissive optical element 13 without being refracted at the side surface 13c3 either, and travels along the illumination optical axis AX.

[0038] Next, as shown in FIG. 4B , when the transmissive optical element 13 rotates by a rotation angle ω, the light ray WL1 is incident on the side surface 13c1 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 13. Next, the light ray WL1 is incident on the side surface 13c3 at a predetermined incident angle, so it is refracted at the side surface 13c3 and is emitted from the transmissive optical element 13. At this time, because the side surfaces 13c1 and 13c3 are parallel to each other, the incident angle of the light ray WL1 with respect to the side surface 13c1 and the incident angle of the light ray WL1 with respect to the side surface 13c3 are equal, and the refraction angle of the light ray WL1 incident on the side surface 13c1 and the refraction angle of the light ray WL1 emitted from the side surface 13c3 have opposite signs but equal absolute values. This cancels out the refraction angle of light ray WL1 when it enters side surface 13c1 and the refraction angle when it emerges from side surface 13c3. 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.

[0039] Next, as shown in Figure 4C, when the rotation angle ω of the transmissive optical element 13 becomes larger than that of Figure 4B, 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 in Figure 4B. 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.

[0040] Next, as shown in FIG. 4D, when the rotation angle ω of the transmissive optical element 13 exceeds 45 degrees, the incident surface of the light ray WL1 changes from the side surface 13c1 to the side surface 13c2. At this time, the light ray WL1 is refracted at the side surface 13c2, but the refraction direction is different from that in the period up to FIG. 4C, 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 13c3 to the side surface 13c4. However, because the side surfaces 13c2 and 13c4 are parallel to each other, the refraction angle of the light ray WL1 when it enters the side surface 13c3 and the refraction angle when it exits the side surface 13c4 cancel each other out, as in the period up to FIG. 4C. 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.

[0041] Next, as shown in Fig. 4E, when the rotation angle ω of the transmissive optical element 13 becomes larger than that of Fig. 4D, 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. 4D. 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.

[0042] Next, as shown in FIG. 4F, when the rotation angle ω of the transmissive optical element 13 reaches 90 degrees, the incident surface changes from the side surface 13c1 in the initial state to the side surface 13c2, but the behavior of the light ray WL1 becomes the same as in the initial state shown in FIG. 4A.

[0043] As described above, if the incident and exit surfaces of the transmissive optical element 13 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 13. 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 13 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 13.

[0044] The illumination light WL incident from the optical scanning unit 12 illuminates the light modulation region 2c of the light modulation device 2 so as to be superimposed in the Y-axis direction, thereby improving the uniformity of the intensity distribution in the light modulation region 2c in the Y-axis direction. Therefore, when generating rectangular illumination light WL, the optical conversion unit 11 may be designed so that the light intensity distribution in the Y-axis direction, the uniformity of which is improved by the optical scanning unit 12, is lower in advance than the light intensity distribution in the Z-axis direction. With this configuration, the optical conditions related to the light intensity distribution in the Z-axis direction in the optical conversion unit 11 are relaxed, making the optical design of the optical conversion unit 11 easier.

[0045] As described above, the light source device 1 of this embodiment includes the light source unit 10, the light conversion unit 11 that converts the light L emitted from the light source unit 10 into rectangular illumination light WL, and the light scanning unit 12 that scans the illumination light WL over the light modulation region 2c, which is the illuminated region. The light conversion unit 11 includes a first optical system 20 that changes the beam width of the light L emitted from the light source unit 10 in the Z-axis direction, and a second optical system 30 that changes the beam width of the light L emitted from the light source unit 10 in the Y-axis direction. The first optical system 20 includes a first optical element 21 that expands the light L emitted from the light source unit 10 in the Z-axis direction, which is perpendicular to the direction in which the light source unit 10 emits the light L, and a second optical element 22 that collimates the light L emitted from the first optical element 21 in the Z-axis direction. The second optical system 30 includes a third optical element 31 that expands the light L emitted from the light source unit 10 in the Y-axis direction, and a fourth optical element 32 that collimates the light L emitted from the third optical element 31 in the Y-axis direction. The second optical system 30 is disposed between the first optical element 21 and the second optical element 22.

[0046] According to the light source device 1 of this embodiment, the first optical system 20 and the second optical system 30 of the light conversion unit 11 can appropriately change the beam width of the light L emitted from the light source unit 10 in each of the Z-axis direction and the Y-axis direction. Therefore, the light source device 1 can scan the illumination light WL having a desired aspect ratio over the illuminated area. Therefore, the light source device 1 can efficiently make the illumination light WL incident on the light modulation area 2c, which is the illuminated area.

[0047] According to the projector 100 of this embodiment, the illumination light WL emitted from the light source device 1 can be efficiently incident on the light modulation area 2c of the light modulation device 2. Therefore, the projector 100 of this embodiment can project a bright image.

[0048] Furthermore, in the light source device 1 of this embodiment, the first optical element 21 and the third optical element 31, which are made up of Powell lenses, are used to expand the luminous flux width of the light L, thereby improving the uniformity of the light intensity distribution of the illumination light WL. Therefore, the light source device 1 of this embodiment can uniformly illuminate the light modulation region 2c of the light modulation device 2. As a result, the projector 100 of this embodiment can project bright, uniform, high-quality images.

[0049] (Second embodiment) A second embodiment of the present invention will now be described. In this embodiment, the configuration of the light conversion unit of the light source device is different from that of the projector of Embodiment 1. Note that the same reference numerals are used for members common to the first embodiment, and detailed descriptions thereof will be omitted.

[0050] Fig. 5A is a plan view showing a schematic configuration of the optical conversion unit 211 of this embodiment when viewed from the +Y side. Fig. 5B is a plan view showing a schematic configuration of the optical conversion unit 211 of this embodiment when viewed from the +Z side. As shown in FIGS. 5A and 5B, the light conversion section 211 of this embodiment has a first optical system 220 and a second optical system 230.

[0051] The first optical system 220 includes a first optical element 221 and a second optical element 222 . The first optical element 221 expands the light L emitted from the light source unit 10 in the Z-axis direction. The first optical element 221 of this embodiment is a cylindrical lens with negative power. The first optical element 221 is a plano-concave cylindrical lens that has negative power in the Z-axis direction and no power in the Y-axis direction. Therefore, as shown in FIG. 5A, the first optical element 221 diverges the light L incident from the light source unit 10 in the Z-axis direction. Note that, as shown in FIG. 5A, the traveling direction of the light L emitted from the first optical element 221 does not change in the Y-axis direction, which has no power.

[0052] The second optical element 222 collimates the light L emitted in a divergent state from the first optical element 221 in the Z-axis direction. The second optical element 222 of this embodiment is a cylindrical lens having positive power. The second optical element 222 is a plano-convex cylindrical lens having no power in the Y-axis direction and positive power in the Z-axis direction. Therefore, the second optical element 222 collimates the light L emitted from the first optical element 221 in the Z-axis direction. Note that, as shown in FIG. 5B , the light L incident from the first optical element 221 passes through the second optical element 222 without changing its traveling direction in the Y-axis direction, which has no power.

[0053] The second optical system 230 is disposed between the first optical element 221 and the second optical element 222. The second optical system 230 includes a third optical element 231 and a fourth optical element 232. The third optical element 231 expands the light L emitted from the light source unit 10 in the Y-axis direction. The third optical element 231 of this embodiment is a cylindrical lens having negative power. The third optical element 231 is a plano-concave cylindrical lens having negative power in the Y-axis direction and no power in the Z-axis direction. Therefore, as shown in FIG. 5B, the third optical element 231 diverges the light L incident from the light source unit 10 in the Y-axis direction. Note that, as shown in FIG. 5A, the light L emitted from the third optical element 231 passes through the third optical element 231 without changing its traveling direction in the Z-axis direction, which has no power.

[0054] The fourth optical element 232 collimates the light L emitted from the third optical element 231 in a divergent state in the Y-axis direction. The fourth optical element 232 of this embodiment is a cylindrical lens having positive power. The fourth optical element 232 is a plano-convex cylindrical lens that has no power in the Z-axis direction and positive power in the Y-axis direction. Therefore, the fourth optical element 232 collimates the light L emitted from the third optical element 231 in the Y-axis direction. Note that, as shown in FIG. 5A , the light L incident from the third optical element 231 passes through the fourth optical element 232 without changing its traveling direction in the Z-axis direction, which has no power.

[0055] In this way, in the light conversion unit 211 of this embodiment, the light L emitted from the light source unit 10 can be converted into rectangular illumination light WL having a predetermined aspect ratio by expanding the luminous flux width in the Y-axis and Z-axis directions and collimating it.

[0056] Here, in the optical conversion section 11 of the first embodiment, the light L is condensed and then diverged inside the first optical element 21 and the third optical element 31, which are made up of Powell lenses, so the temperatures of the first optical element 21 and the third optical element 31 rise, causing thermal distortion and potentially disrupting the polarization direction of the linearly polarized light light L.

[0057] In contrast, the light conversion unit 211 of this embodiment uses the first optical element 221 and the third optical element 231 made of plano-concave cylindrical lenses, and therefore the light L is not condensed inside the first optical element 221 and the third optical element 231, making it possible to prevent polarization disturbance caused by thermal distortion of the first optical element 221 and the third optical element 231. Therefore, with the light source device using the light conversion unit 211 of this embodiment, light L without disturbance in polarization direction can be made incident on the light modulation region 2c of the light modulation device 2. Therefore, with the projector of this embodiment, no light loss occurs due to polarization disturbance of the illumination light WL incident on the light modulation device 2, and therefore it is possible to provide a projector that has high light utilization efficiency and projects bright images.

[0058] (Third embodiment) A third embodiment of the present invention will now be described. In this embodiment, the configuration of the light conversion unit of the light source device is different from that of the projector of Embodiment 1. Note that the same reference numerals are used for members common to the first embodiment, and detailed descriptions thereof will be omitted.

[0059] Fig. 6A is a plan view showing a schematic configuration of the optical conversion unit 311 of this embodiment when viewed from the +Y side. Fig. 6B is a plan view showing a schematic configuration of the optical conversion unit 311 of this embodiment when viewed from the +Z side. As shown in FIGS. 6A and 6B, the light converting section 311 of this embodiment has a first optical system 320 and a second optical system 330.

[0060] The first optical system 320 includes a first optical element 321 and a second optical element 322 . The first optical element 321 expands the light L emitted from the light source unit 10 in the Z-axis direction. The first optical element 321 of this embodiment is a diffuser plate that diffuses light in one direction. The first optical element 321 is a diffusing element that has anisotropic diffusion characteristics, ie, it diffuses light in the Z-axis direction but does not diffuse light in the Y-axis direction. Therefore, the first optical element 321 diverges the light L incident from the light source unit 10 in the Z-axis direction and transmits the light L in the Y-axis direction without changing its traveling direction.

[0061] The second optical element 322 collimates the light L emitted in a diffused state from the first optical element 321 in the Z-axis direction. The second optical element 322 of this embodiment is a cylindrical lens having positive power. The second optical element 322 is a plano-convex cylindrical lens that has no power in the Y-axis direction and positive power in the Z-axis direction. Therefore, the second optical element 322 collimates the light L emitted from the first optical element 321 in the Z-axis direction. Note that, as shown in FIG. 6B , the light L incident from the first optical element 321 passes through the second optical element 322 without changing its traveling direction in the Y-axis direction, which has no power.

[0062] The second optical system 330 is disposed between the first optical element 321 and the second optical element 322. The second optical system 330 includes a third optical element 331 and a fourth optical element 332. The third optical element 331 expands the light L emitted from the light source unit 10 in the Y-axis direction. The third optical element 331 of this embodiment is a diffuser plate that diffuses light in one direction. The third optical element 331 is a diffusing element that has anisotropic diffusion characteristics, ie, it diffuses light in the Y-axis direction but does not diffuse light in the Z-axis direction. Therefore, the third optical element 331 diverges the light L incident from the light source unit 10 in the Y-axis direction and transmits the light L in the Z-axis direction without changing its traveling direction.

[0063] The fourth optical element 332 collimates the light L emitted from the third optical element 331 in a divergent state in the Y-axis direction. The fourth optical element 332 of this embodiment is a cylindrical lens having positive power. The fourth optical element 332 is a plano-convex cylindrical lens that has no power in the Z-axis direction and positive power in the Y-axis direction. Therefore, the fourth optical element 332 collimates the light L emitted from the third optical element 331 in the Y-axis direction. Note that, as shown in FIG. 6A , the light L incident from the third optical element 331 passes through the fourth optical element 332 without changing its traveling direction in the Z-axis direction, which has no power.

[0064] In this way, in the light conversion unit 311 of this embodiment, the light L emitted from the light source unit 10 can be converted into rectangular illumination light WL having a predetermined aspect ratio by expanding the luminous flux width in the Y-axis and Z-axis directions and collimating the light.

[0065] According to the light conversion unit 311 of this embodiment, the first optical element 321 of the first optical system 320 and the third optical element 331 of the second optical system 330 are configured as diffusers, and therefore there is no need to align the illumination optical axis AX with the optical axes of the first optical element 321 and the third optical element 331. Therefore, compared to a configuration in which the four optical axes of the first optical element, the second optical element, the third optical element, and the fourth optical element are aligned with the illumination optical axis AX, the combinability of the light source device can be improved. Therefore, according to the projector of this embodiment, a light modulation device with excellent combinability is provided, and therefore a projector with reduced assembly costs can be provided.

[0066] 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 description of the shape, number, arrangement, material, etc. of each component of the projector is not limited to the above embodiment and can be changed as appropriate.

[0067] A summary of this disclosure is provided below.

[0068] (Appendix 1) A light source unit; a light conversion unit that converts the light emitted from the light source unit into rectangular illumination light; a light scanning unit that scans the illumination light over an illuminated area, The optical conversion unit is a first optical system that changes a beam width in a first direction of the light emitted from the light source unit; a second optical system that changes a beam width of the light emitted from the light source unit in a second direction perpendicular to the first direction, The first optical system is a first optical element that expands the light emitted from the light source unit in the first direction; a second optical element that collimates the light emitted from the first optical element in the first direction, The second optical system is a third optical element that expands the light emitted from the light source unit in the second direction; a fourth optical element that collimates the light emitted from the third optical element in the second direction, the second optical system is disposed between the first optical element and the second optical element. Light source device.

[0069] According to the light source device having this configuration, the light beam width of the light emitted from the light source unit can be appropriately changed in each of the first and second directions by the optical conversion unit. Therefore, the illumination light having a desired aspect ratio can be scanned over the illuminated area. Therefore, according to the light source device having this configuration, the illumination light can be efficiently incident on the illuminated area.

[0070] (Appendix 2) a rate of change of the beam width in the second direction in the second optical system is smaller than a rate of change of the beam width in the first direction in the first optical system; 10. The light source device of claim 1.

[0071] Here, the distance between the first optical element and the second optical element constituting the first optical system, which has a large rate of change in the beam width, is shorter than the distance between the third optical element and the fourth optical element constituting the second optical system, which has a small rate of change in the beam width. This configuration allows the gap between the first optical element and the second optical element to be effectively used as installation space for the second optical system. Therefore, compared to when the first optical system and the second optical system are arranged in series, space can be saved along the illumination optical axis, thereby enabling the device configuration to be more compact.

[0072] (Appendix 3) the first optical element and the third optical element are Powell lenses; the second optical element and the fourth optical element are cylindrical lenses; 10. The light source device according to claim 1 or 2.

[0073] According to this configuration, the beam width of the light is expanded using the first optical element and the third optical element, which are Powell lenses, thereby increasing the uniformity of the light intensity distribution of the illumination light, thereby enabling the illuminated area to be illuminated uniformly.

[0074] (Appendix 4) the first optical element and the third optical element are cylindrical lenses having negative power, the second optical element and the fourth optical element are cylindrical lenses having positive power; 10. The light source device according to claim 1 or 2.

[0075] With this configuration, since light is not condensed inside the first optical element and the third optical element, it is possible to prevent the occurrence of polarization disturbance due to thermal distortion of the first optical element and the third optical element, and therefore it is possible to irradiate the illuminated area with light whose polarization direction is not disturbed.

[0076] (Appendix 5) the first optical element and the third optical element are diffusion plates that diffuse light in one direction, the second optical element and the fourth optical element are cylindrical lenses; 10. The light source device according to claim 1 or 2.

[0077] According to this configuration, since the first optical element of the first optical system and the third optical element of the second optical system are configured as diffusers, it is not necessary to align the illumination optical axis of the light source device with the optical axes of the first optical element and the third optical element. Therefore, the combinability of the light source device can be improved compared to a configuration in which the four optical axes of the first optical element, the second optical element, the third optical element, and the fourth optical element are aligned with the illumination optical axis.

[0078] (Appendix 6) The light source unit has a laser light emitting element. 6. A light source device according to any one of claims 1 to 5.

[0079] According to this configuration, the light source section can emit light with high brightness.

[0080] (Appendix 7) The optical scanning unit a transmissive optical element including an incident surface onto which the illumination light emitted from the light conversion unit is incident, and an exit surface that is parallel to the incident surface and through which the illumination light incident from the incident surface exits; a rotation drive unit that rotates the transmissive optical element around a rotation axis along the first direction, 7. A light source device according to any one of claims 1 to 6.

[0081] According to this configuration, the incident surface and the exit surface change as the transmitting optical element rotates, so that the rectangular illumination light can be scanned over the illuminated area.

[0082] (Appendix 8) the optical scanning unit scans the illumination light along a direction of a short side of an aspect ratio of the illumination light; 8. A light source device according to any one of claims 1 to 7.

[0083] According to this configuration, the illumination light and the light modulation device can be aligned based on the long side direction of the aspect ratio of the illumination light, which makes it easy to align the light scanning unit that emits the illumination light with the light modulation device, thereby improving the combinability of the light source device.

[0084] (Appendix 9) a light source device according to any one of Supplementary Note 1 to Supplementary Note 8; 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.

[0085] According to a projector having this configuration, the illumination light emitted from the light source device can be made to efficiently enter the light modulation device, so that a bright image can be projected. [Explanation of symbols]

[0086] 1...light source device, 2...light modulation device, 4...positive, 4...projection optical device, 10...light source section, 11,211,311...light conversion section, 12...light scanning section, 13...transmitting optical element, 14...rotation drive section, 20,220,320...first optical system, 21,221,321...first optical element, 22,222,322...second optical element, 30,230,330...second optical system, 31,231,331...third optical element, 32,232,332...fourth optical element, 100...projector, L...light, O...rotation axis, WL...illumination light.

Claims

1. A light source unit; a light conversion unit that converts the light emitted from the light source unit into rectangular illumination light; a light scanning unit that scans the illumination light over an illuminated area, The optical conversion unit is a first optical system that changes a beam width of the light emitted from the light source unit in a first direction that is perpendicular to a direction in which the light source unit emits the light; a second optical system that changes a luminous flux width of the light emitted from the light source unit in a second direction perpendicular to the first direction, The first optical system is a first optical element that expands the light emitted from the light source unit in the first direction; a second optical element that collimates the light emitted from the first optical element in the first direction, The second optical system is a third optical element that expands the light emitted from the light source unit in the second direction; a fourth optical element that collimates the light emitted from the third optical element in the second direction, the second optical system is disposed between the first optical element and the second optical element. Light source device.

2. a rate of change of the beam width in the second direction in the second optical system is smaller than a rate of change of the beam width in the first direction in the first optical system; The light source device according to claim 1 .

3. the first optical element and the third optical element are Powell lenses; the second optical element and the fourth optical element are cylindrical lenses; 3. The light source device according to claim 1.

4. the first optical element and the third optical element are cylindrical lenses having negative power, the second optical element and the fourth optical element are cylindrical lenses having positive power; 3. The light source device according to claim 1.

5. the first optical element and the third optical element are diffusion plates that diffuse light in one direction, the second optical element and the fourth optical element are cylindrical lenses; 3. The light source device according to claim 1.

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

3. The light source device according to claim 1.

7. The optical scanning unit a transmissive optical element including an incident surface onto which the illumination light emitted from the light conversion unit is incident, and an exit surface that is parallel to the incident surface and through which the illumination light incident from the incident surface exits; a rotation drive unit that rotates the transmissive optical element around a rotation axis along the first direction, 3. The light source device according to claim 1.

8. the optical scanning unit scans the illumination light along a direction of a short side of an aspect ratio of the illumination light; 3. The light source device according to claim 1.

9. 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