Light source device and projector

Abstract

To provide a light source device and projector, capable of improving the uniformity of illuminance distribution in an area to be illuminated.SOLUTION: A light source device includes a light source part, a front stage side optical element and a back stage side optical element. The front stage side optical element rotating around a first rotational axis includes: a first incident plane making a part of light incident and forming a first angle to a reference plane orthogonal to the chief ray of the light; a second incident plane making the other part of the light incident and forming a second angle to the reference plane; a first emission plane emitting the light incident from the first incident plane; and a second emission plane emitting the light incident from the second incident plane. The back stage side optical element rotating around a second rotational axis includes: a third incident plane making the light from the front stage side optical element incident; and a third emission plane emitting the light incident from the third incident plane. The first incident plane and the first emission plane are parallel to each other; the second incident plane and the second emission plane are parallel to each other; and the third incident plane and the third emission plane are parallel to each other.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] Conventionally, there is a projector that illuminates a light modulation device such as a liquid crystal panel by scanning light emitted from a light-emitting element over time 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. In this projector, the light source device emits light having an elliptical beam cross section. The polygon mirror reflects the light emitted from the light source device and scans the light in the minor axis direction of the elliptical beam cross section over the image formation area of ​​the liquid crystal light valve. [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, one spot of reflected light from the polygon mirror is scanned sequentially over the image forming area of ​​the liquid crystal light valve, which causes a problem that uneven illuminance is easily noticeable within the surface of the image forming area. [Means for solving the problem]

[0005] In order to solve the above problems, according to a first aspect of the present invention, there is provided a light source unit, a front-stage optical element that transmits light emitted from the light source unit, and a rear-stage optical element that transmits the light emitted from the front-stage optical element, wherein the front-stage optical element rotates around a first rotation axis, and the rear-stage optical element rotates around a second rotation axis that intersects with the first rotation axis, and the front-stage optical element has a first entrance surface onto which a portion of the light is incident and that forms a first angle with respect to a reference plane that is orthogonal to a principal ray of the light, a second entrance surface onto which another portion of the light is incident and that forms a second angle with respect to the reference plane that is different from the first angle, and A light source device is provided, which has a first exit surface that exits a portion of the light incident from an entrance surface and a second exit surface that exits another portion of the light incident from the second entrance surface, and the rear-stage optical element has a third entrance surface into which the light exiting from the front-stage optical element is incident and a third exit surface that exits the light incident from the third entrance surface, in the front-stage optical element, the first entrance surface and the first exit surface are parallel to each other, and the second entrance surface and the second exit surface are parallel to each other, and in the rear-stage optical element, the third entrance surface and the third exit surface are parallel to each other.

[0006] According to a second aspect of the present invention, there is provided a projector comprising the light source device of the first aspect, an optical modulation device that modulates the light emitted from the light source device based on image information, and a projection optical device that projects the light emitted from the optical modulation device. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a plan view showing a schematic configuration of a projector according to a first embodiment. [Figure 2] 1 is a perspective view showing a schematic configuration of a light source device according to a first embodiment. [Figure 3A] 5A and 5B are schematic diagrams for explaining the behavior of light when the first optical member rotates. [Figure 3B] 5A and 5B are schematic diagrams for explaining the behavior of light when the first optical member rotates. [Figure 3C]5A and 5B are schematic diagrams for explaining the behavior of light when the first optical member rotates. [Figure 3D] 5A and 5B are schematic diagrams for explaining the behavior of light when the first optical member rotates. [Figure 3E] 5A and 5B are schematic diagrams for explaining the behavior of light when the first optical member rotates. [Figure 3F] 5A and 5B are schematic diagrams for explaining the behavior of light when the first optical member rotates. [Figure 4] FIG. 1 is an image diagram showing the trajectory of light that scans two-dimensionally on a light modulation device. [Figure 5A] FIG. 10 is a diagram illustrating a simulation result. [Figure 5B] FIG. 10 is a diagram illustrating a simulation result. [Figure 6] FIG. 10 is a plan view showing a schematic configuration of a projector according to a second embodiment. [Figure 7] FIG. 10 is a plan view showing a schematic configuration of a projector according to a third embodiment. [Figure 8] FIG. 10 is a perspective view showing a schematic configuration of a front optical element according to a modified example. 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 drawings below, the dimensions of some components may be shown on different scales to make them easier to see.

[0009] FIG. 1 is a plan view showing a schematic configuration of a projector according to this embodiment. As shown in FIG. 1, a projector 100 of this embodiment includes a light source device 10, a light modulation device 21, an exit-side polarizing plate 22, and a projection optical device . The light source device 10 includes a light source section 10 a, a front-stage optical element 11 , a rear-stage optical element 14 , a first rotary drive device 15 , and a second rotary drive device 16 .

[0010] The following description will be given using an XYZ Cartesian coordinate system in the drawings as necessary. The X axis is an axis parallel to the illumination optical axis AX of the light source device 10. The illumination optical axis AX of the light source device 10 is defined as an axis along the chief ray of the light L1 emitted from the light source unit 10a. The Y axis is an axis perpendicular to the X axis and parallel to the first rotation axis C1 of the front-side optical element 11. The Z axis is an axis perpendicular to the X axis and Y axis.

[0011] The light source unit 10a emits light L1 in a first wavelength band toward the upstream optical element 11. The light source unit 10a is configured with a light emitting element made of a laser diode. Therefore, the light L1 emitted from the light source unit 10a is linearly polarized light with coherence, a narrow beam width, and high parallelism. The first wavelength band is not particularly limited as long as it is within the visible light wavelength band.

[0012] The front-stage optical element 11 is disposed on the illumination optical axis AX between the light source unit 10a and the rear-stage optical element 14. The front-stage optical element 11 transmits light L1 emitted from the light source unit 10a. The front-stage optical element 11 is made of a rotatably supported light-transmitting member. The front-stage optical element 11 is rotatable about a first rotation axis C1 extending along the Y-axis direction. The first rotation axis C1 is connected to a first rotation drive device 15 formed of a motor or the like. The front-stage optical element 11 rotates about the first rotation axis C1 by being driven by the first rotation drive device 15.

[0013] FIG. 2 is a perspective view showing a schematic configuration of the light source device 10 of this embodiment. 2, the upstream optical element 11 is composed of a first optical member 12 and a second optical member 13. The first optical member 12 and the second optical member 13 are an integrated optical member. The first optical member 12 and the second optical member 13 may be integrated by bonding to form an interface therebetween, or by cutting the first optical member 12 and the second optical member 13 out of a single material, for example. In this embodiment, the first rotation drive device (rotation drive device) 15 rotates the first optical member 12 and the second optical member 13 together around the first rotation axis C1, which allows the number of parts of the light source device 10 to be reduced.

[0014] The first optical member 12 and the second optical member 13 have the same shape and are each made of a plate-like, light-transmitting member with a square planar shape. The glass material of the optical members that make up the upstream optical element 11, including the first optical member 12 and the second optical member 13, is, for example, optical glass such as BK7, quartz, resin, or other light-transmitting materials. Because the first optical member 12 and the second optical member 13 are made of the same material, the refractive index of the first optical member 12 and the refractive index of the second optical member 13 are equal. Therefore, the refraction angles of light passing through the first optical member 12 and the second optical member 13 can be easily aligned. This makes it easy to adjust the optical path of light passing through the upstream optical element 11.

[0015] The first optical member 12 and the second optical member 13 are arranged in a stacked state in a direction along the first rotation axis C1. The first optical member 12 and the second optical member 13 are arranged so that their respective centers overlap on the first rotation axis C1. When viewed in a direction along the first rotation axis C1, the first optical member 12 and the second optical member 13 are positioned at different positions around the axis. Therefore, if one of the first optical member 12 and the second optical member 13 rotates around the first rotation axis C1, the first optical member 12 and the second optical member 13 will overlap each other.

[0016] The first optical member 12 has a first surface 12a and a second surface 12b that intersect with the first rotation axis C1, and four first side surfaces 12c1, 12c2, 12c3, and 12c4 that are perpendicular to the first surface 12a and the second surface 12b. The four first side surfaces 12c1, 12c2, 12c3, and 12c4 have the same area, and two opposing first side surfaces are parallel to each other. The first surface 12a faces the +Y side and corresponds to the surface 11a of the front-side optical element 11. The second surface 12b faces the -Y side and is integrated with the second optical member .

[0017] The second optical member 13 has a third surface 13a and a fourth surface 13b that intersect with the first rotation axis C1, and four second side surfaces 13c1, 13c2, 13c3, and 13c4 that are perpendicular to the third surface 13a and the fourth surface 13b. The four second side surfaces 13c1, 13c2, 13c3, and 13c4 have the same area, and two opposing second side surfaces are parallel to each other. The third surface 13a faces the -Y side and corresponds to the back surface 11b of the front-side optical element 11. The fourth surface 13b faces the +Y side and is integrated with the second surface 12b of the first optical member 12.

[0018] The upstream optical element 11 transmits light L1 emitted from the light source unit 10a. The light L1 is incident on the upstream optical element 11 so as to straddle the boundary between the first optical member 12 and the second optical member 13 in the Y direction, which is the stacking direction of the first optical member 12 and the second optical member 13. In this embodiment, the chief ray of the light L1 coincides with the boundary between the first optical member 12 and the second optical member 13.

[0019] Therefore, a first component L11, which is a part of the light L1 emitted from the light source unit 10a, is incident on the first optical member 12, and a second component L12, which is another part of the light L1 emitted from the light source unit 10a, is incident on the second optical member 13. In the present embodiment, the first component L11 and the second component L12 are each light obtained by splitting the light L1 in half, and have the same brightness.

[0020] The front-side optical element 11 transmits the light L1 while rotating around the first rotation axis C1. Therefore, the first side surface from which the first component L11 of the light L1 enters the first optical member 12 is not fixed to one, but changes over time. Similarly, the first side surface from which the first component L11 entering the first optical member 12 is emitted into external space is not fixed to one, but changes over time.

[0021] Furthermore, the second side surface through which the second component L12 of the light L1 enters the second optical member 13 is not fixed to one, but changes over time. Similarly, the second side surface through which the second component L12 that has entered the second optical member 13 is emitted into the external space is not fixed to one, but changes over time.

[0022] Here, in the first optical member 12, the first side surface onto which the first component L11 is incident is referred to as the first incident surface. The first side surface from which the first component L11 incident from the first incident surface exits is referred to as the first exit surface. In addition, in the second optical member 13, the second side surface onto which the second component L12 is incident is referred to as the second incident surface. The second side surface from which the second component L12 incident from the second incident surface exits is referred to as the second exit surface.

[0023] In this case, the first entrance surface and the first exit surface change over time and are either of two parallel first side surfaces among the four first side surfaces 12c1, 12c2, 12c3, and 12c4. Similarly, the second entrance surface and the second exit surface change over time and are either of two parallel second side surfaces among the four second side surfaces 13c1, 13c2, 13c3, and 13c4.

[0024] In FIG. 2, an imaginary plane orthogonal to the principal ray along the optical axis of the light L1 emitted from the light source unit 10a and incident on the upstream optical element 11 is defined as a reference plane RP. In Fig. 2, the first side surface 12c1 of the four first side surfaces 12c1, 12c2, 12c3, and 12c4 of the first optical member 12 corresponds to the first incident surface, and the second side surface 13c1 of the four second side surfaces 13c1, 13c2, 13c3, and 13c4 of the second optical member 13 corresponds to the second incident surface. Also, in Fig. 2, the angle that the first side surface 12c1, which is the first incident surface, makes with respect to the reference plane RP is defined as a first angle θ1, and the angle that the second side surface 13c1, which is the second incident surface, makes with respect to the reference plane RP is defined as a second angle θ2. In Fig. 2, the first side surface 12c1 coincides with the reference plane RP, and the second side surface 13c1 is inclined toward the -X side with respect to the reference plane RP.

[0025] As such, the front-stage optical element 11 of this embodiment has a first incident surface onto which the first component L11 of light L1 is incident and which forms a first angle θ1 with respect to the reference plane RP, a second exit surface onto which the second component L12 of light L1 is incident and which forms a second angle θ2 with respect to the reference plane RP, a first exit surface from which the first component L11 of light L1 incident from the first incident surface exits, and a second exit surface from which the second component L12 of light L1 incident from the second incident surface exits. The magnitudes of the first angle θ1 and the second angle θ2 change as the upstream optical element 11 rotates, but the magnitudes of the first angle θ1 and the second angle θ2 are always different and never coincident.

[0026] In this specification, when two surfaces of an optical element 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 optical element, the allowable range of parallelism of light, etc.

[0027] In this embodiment, the first optical member 12 has four first side surfaces 12c1, 12c2, 12c3, and 12c4, and the second optical member 13 has four second side surfaces 13c1, 13c2, 13c3, and 13c4. However, the number of first and second side surfaces does not necessarily have to be four; it is preferable that the number be 2 × m (m: a natural number greater than or equal to 2). That is, it is preferable that the number of first and second side surfaces be an even number, such as 6 or 8. If the number of first and second side surfaces is an even number, all first and second side surfaces are parallel to the first and second side surfaces facing the first and second side surfaces, and there are no first and second side surfaces that are not parallel. This reduces the generation of stray light in the first optical member 12 and the second optical member 13, thereby improving light utilization efficiency.

[0028] The rear-stage optical element 14 is disposed on the light-emitting side of the front-stage optical element 11 on the illumination optical axis AX. The rear-stage optical element 14 transmits the light L1 emitted from the front-stage optical element 11. The rear-stage optical element 14 is made of a rotatably supported light-transmitting member. The rear-stage optical element 14 is rotatable about a second rotation axis C2 extending along the Z-axis direction. That is, the first rotation axis C1 and the second rotation axis C2 extend in directions perpendicular to each other in a plane perpendicular to the illumination optical axis AX. The second rotation axis C2 is connected to a second rotation drive device 16 formed of a motor or the like. The rear-stage optical element 14 rotates about the second rotation axis C2 by being driven by the second rotation drive device 16.

[0029] The light-transmitting member that constitutes the rear-stage optical element 14 is substantially the same as the light-transmitting member that constitutes the front-stage optical element 11. As the glass material of the light-transmitting member, for example, optical glass such as BK7, quartz, resin, or other light-transmitting materials are used. In particular, in the case of the rear-stage optical element 14, unlike the front-stage optical element 11, light L1 enters the rear-stage optical element 14 after being scanned in one direction by the front-stage optical element 11, and therefore the light density is lower than that of light L1 at the time of entering the front-stage optical element 11. Therefore, it is more likely that a resin material with low light resistance and heat resistance can be used than for the front-stage optical element 11.

[0030] The rear-stage optical element 14 has a fifth surface 14a and a sixth surface 14b that intersect with the second rotation axis C2, and four third side surfaces 14c1, 14c2, 14c3, and 14c4 that are perpendicular to the fifth surface 14a and the sixth surface 14b. That is, the shape of the rear-stage optical element 14 is a regular rectangular prism having six flat surfaces including the fifth surface 14a, the sixth surface 14b, and the four third side surfaces 14c1, 14c2, 14c3, and 14c4. The cross-sectional shape of the rear-stage optical element 14 cut along a plane perpendicular to the second rotation axis C2 is a square. That is, the four third side surfaces 14c1, 14c2, 14c3, and 14c4 have the same area, and the two opposing second side surfaces are parallel to each other.

[0031] The rear-side optical element 14 transmits the light L1 emitted from the front-side optical element 11 while rotating about the second rotation axis C2. Therefore, the third side surface through which the light L1 emitted from the front-side optical element 11 enters the rear-side optical element 14 is not fixed and changes over time. Similarly, the third side surface through which the light L1 incident on the rear-side optical element 14 is emitted to external space is not fixed and changes over time. In the rear-side optical element 14, the third side surface through which the light L1 emitted from the front-side optical element 11 enters is referred to as the fourth incident surface. The third side surface through which the light L1 incident from the third incident surface exits is referred to as the third exit surface. In this case, the third incident surface and the third exit surface change over time and are any two of the four third side surfaces 14c1, 14c2, 14c3, and 14c4 that are parallel to each other.

[0032] In this embodiment, the rear-side optical element 14 has four third side surfaces 14c1, 14c2, 14c3, and 14c4, but the number of third side surfaces does not necessarily have to be four; it is desirable that the number be 2×n (n: a natural number greater than or equal to 2). That is, it is desirable that the number of third side surfaces be an even number, for example, 6, 8, or the like. If the number of third side surfaces is an even number, each of the third side surfaces is parallel to the third side surface opposite to that third side surface, and there are no third side surfaces that are not parallel. This reduces the generation of stray light in the rear-side optical element 14, thereby improving light utilization efficiency.

[0033] In this embodiment, an example is given in which the number of first and second sides of each optical member of the front-stage optical element 11 and the number of third sides of the rear-stage optical element 14 are both four, but the number of first and second sides and the number of third sides of the rear-stage optical element 14 may be different.

[0034] At least one of the upstream optical element 11 and the downstream optical element 14 may be made of quartz. In the upstream optical element 11 and the downstream optical element 14, as the amount of light passing 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 L1 emitted from the light source unit 10a is disturbed, and linearly polarized light incident on the translucent member becomes elliptically polarized light before being emitted from the translucent member. As a result, the projector 100 loses the effect of achieving a predetermined contrast without an incident-side polarizer by using a laser diode for the light source unit 10a. In other words, even if the light source unit 10a uses a laser diode, an incident-side polarizer 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 low thermal distortion, such as quartz.

[0035] The following describes the behavior of light L1 when it passes through the front-side optical element 11 and the rear-side optical element 14. Note that the action of the front-side optical element 11 and the action of the rear-side optical element 14 are similar, only the direction is different, and therefore the following describes the behavior of light L1 when it passes through the front-side optical element 11. Note that the behavior of the first component L11 in the first optical member 12 and the behavior of the second component L12 in the second optical member 13 are similar, only the timing of displacement in the Z-axis direction is different, and therefore the following describes the behavior of the first component L11 by the first optical member 12, using illustrations.

[0036] 3A to 3F are schematic diagrams illustrating the behavior of light L1 when passing through the rotating first optical member 12. In this example, when viewed from the +Y side, the first optical member 12 is rotating clockwise around the first rotation axis C1, and time is shown passing from FIG. 3A to FIG. 3F.

[0037] 3A to 3F, the angle between the illumination optical axis AX and a straight line M that passes through the first rotation axis C1 and is perpendicular to the first side surface 12c1 of the first optical member 12 is defined as the rotation angle ω of the first optical member 12. In reality, the light L1 has a predetermined luminous flux width in the Z-axis direction, but here we will focus on the behavior of the light ray L1a, which is the chief ray traveling on the illumination optical axis AX.

[0038] 3A shows the initial state of the first optical member 12. That is, the first optical member 12 is not rotated, the line M and the illumination optical axis AX overlap, and the rotation angle ω is 0 degrees. In this case, the light ray L1a is perpendicularly incident on the first side surface 12c1 and therefore travels along the illumination optical axis AX inside the first optical member 12 without being refracted at the first side surface 12c1. Next, the light ray L1a is also perpendicularly incident on the first side surface 12c3, which is parallel to the first side surface 12c1. Therefore, the light ray is emitted from the first optical member 12 and travels along the illumination optical axis AX without being refracted at the first side surface 12c3 either.

[0039] Next, as shown in FIG. 3B , when the first optical member 12 rotates by the rotation angle ω, the light ray L1a is incident on the first side surface 12c1 at an incident angle equal to the rotation angle ω. Therefore, the light ray L1a is refracted in the direction shown in the figure (toward the +Z direction) and travels inside the first optical member 12. Next, the light ray L1a is incident on the first side surface 12c3 at a predetermined incident angle, is refracted at the first side surface 12c3, and is emitted from the first optical member 12. At this time, because the first side surfaces 12c1 and 12c3 are parallel to each other, the incident angle of the light ray L1a on the first side surface 12c1 and the incident angle of the light ray L1a on the first side surface 12c3 are equal. Therefore, the refraction angle of the light ray L1a incident on the first side surface 12c1 and the refraction angle of the light ray L1a emitted from the first side surface 12c3 have opposite signs but equal absolute values. This causes the refraction angle of light ray L1a when it enters first side surface 12c1 to cancel out the refraction angle when it emerges from first side surface 12c3. As a result, light ray L1a travels parallel to illumination optical axis AX at a position displaced by displacement amount d from illumination optical axis AX toward the +Z side.

[0040] Next, as shown in Figure 3C, when the rotation angle ω of the first optical member 12 becomes larger than that shown in Figure 3B, the angle of incidence of the light ray L1a becomes larger, and the angle of refraction also becomes larger. Therefore, the displacement d of the light ray L1a from the illumination optical axis AX becomes larger than that shown in Figure 3B. Furthermore, the state in which the light ray L1a 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.

[0041] Next, as shown in FIG. 3D, when the rotation angle ω of the first optical member 12 exceeds 45 degrees, the incident surface of the light ray L1a changes from the first side surface 12c1 to the first side surface 12c2. At this time, the light ray L1a is refracted at the first side surface 12c2, but the refraction direction is different from that in the period up to FIG. 3C, and the light ray L1a is refracted in the direction shown in the figure (toward the -Z side). The exit surface of the light ray L1a also changes from the first side surface 12c3 to the first side surface 12c4. However, because the first side surfaces 12c2 and 12c4 are parallel to each other, the refraction angle of the light ray L1a when it enters the first side surface 12c3 and the refraction angle when it exits from the first side surface 12c4 cancel each other out, as in the period up to FIG. 3C. As a result, the light ray L1a 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.

[0042] Next, as shown in Fig. 3E, when the rotation angle ω of the first optical member 12 becomes larger than that shown in Fig. 3D, the angle of incidence of the light ray L1a becomes smaller, and the angle of refraction also becomes smaller. Therefore, the displacement d of the light ray L1a from the illumination optical axis AX becomes smaller than that shown in Fig. 3D. Thus, when the rotation angle ω is between 45 degrees and 90 degrees, the displacement d monotonically decreases as the rotation angle ω increases.

[0043] Next, as shown in FIG. 3F, when the rotation angle ω of the first optical member 12 becomes 90 degrees, the incident surface changes from the first side surface 12c1 in the initial state to the first side surface 12c2, but the behavior of the light ray L1a becomes the same as in the initial state shown in FIG. 3A.

[0044] As described above, if the first entrance surface and the first exit surface of the first optical member 12 are parallel to each other, the traveling direction of the light ray L1a does not change regardless of the rotation angle ω of the first optical member 12. Instead, the light ray L1a translates in a direction parallel to the illumination optical axis AX over time. When the rotation angle ω is 0°, the displacement d of the light ray L1a is 0. As the rotation angle ω ranges from 0° to 45°, the displacement d increases toward either the +Z or -Z direction. As soon as the rotation angle ω exceeds 45°, the displacement direction reverses while the absolute value of the displacement d remains the same. 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 the rotation angle ω reaches 90°, the above behavior is repeated. Therefore, when the first optical member 12 rotates once, the displacement d of the light ray L1a repeats the above cycle four times. The displacement amount of the light ray L1a can be set appropriately by adjusting the parameters of the first optical member 12, such as the refractive index and size.

[0045] The displacement amount d of the first component L11 accompanying the rotation of the first optical member 12 has been described above, but the same can be said for the displacement amount of the second component L12 accompanying the rotation of the second optical member 13. In the front-stage optical element 11 of this embodiment, the first optical member 12 and the second optical member 13 are displaced from each other around the rotation axis. That is, the angle that the first incident surface of the first optical member 12 makes with respect to the reference plane RP is different from the angle that the second incident surface of the second optical member 13 makes with respect to the reference plane RP. Therefore, even if the rotation angles of the first optical member 12 and the second optical member 13 are the same, the incident angle of the first component L11 with respect to the first incident surface of the first optical member 12 is different from the incident angle of the second component L12 with respect to the second incident surface of the second optical member 13. Therefore, the displacement amount of the first component L11 caused by the first optical member 12 is different from the displacement amount of the second component L12 caused by the second optical member 13.

[0046] Therefore, the light L1 emitted from the light source unit 10a is separated into a first component L11 and a second component L12 by the front-side optical element 11 and then enters the rear-side optical element 14. The first component L11 and the second component L12 scan the light incident surface of the rear-side optical element 14 in the Z-axis direction while being spaced apart in the Z-axis direction and the Y-axis direction.

[0047] Because the second rotation axis C2 of the rear-side optical element 14 and the first rotation axis C1 of the front-side optical element 11 are perpendicular to each other, the light L1, which includes the first component L11 and the second component L12 and is emitted from the front-side optical element 11, is scanned in the Y-axis direction by the rear-side optical element 14. The front-side optical element 11 and the rear-side optical element 14 scan the light L1 over a two-dimensional illuminated region Q on the illuminated surface, specifically, over the image formation region of the light modulation device 21.

[0048] As shown in FIG. 1, the light modulation device 21 modulates the light L1 emitted from the light source device 10 in accordance with image information to form image light. A transmissive liquid crystal panel is used for the light modulation device 21. 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.

[0049] The exit-side polarizing plate 22 is provided on the illumination optical axis AX between the light modulation device 21 and the projection optical device 23. The exit-side polarizing plate 22 transmits linearly polarized light in a specific direction that is emitted from the light modulation device 21 toward the projection optical device 23. In the case of this embodiment, a laser diode is used in the light source unit 10a, so linearly polarized light is emitted from the light source device 10. Therefore, an entrance-side polarizing plate provided on the light entrance side of the light modulation device 21 is not necessary.

[0050] The projection optical device 23 is composed of a plurality of projection lenses, and projects the image light modulated by the light modulation device 21 onto a projection surface such as a screen in an enlarged scale. As a result, an image is displayed on a projection surface such as a screen.

[0051] FIG. 4 is an image diagram showing the trajectory of light that scans the light modulation device 21 two-dimensionally. 4, the light L1 scans the image forming area 21a of the light modulation device 21 so as to trace multiple trajectories that extend obliquely from the upper right to the lower left of the figure. Hereinafter, the trajectories that the light L1 traces on the image forming area 21a may also be referred to as scanning lines SL.

[0052] In the light source device 10 of this embodiment, the light L1 emitted from the light source section 10a is separated into a first component L11 and a second component L12 by a front-stage optical element 11 consisting of a first optical member 12 and a second optical member 13, and the first component L11 and the second component L12 are scanned over the image forming area 21a of the light modulation device 21.

[0053] The more scanning lines SL that scan the image forming area 21a, the more uniform the illuminance distribution in the image forming area 21a becomes in the light modulation device 21. For example, if the scanning lines SL based on the first component L11 and the scanning lines SL based on the second component L12 do not overlap on the image forming area 21a, the number of scanning lines SL that scan the image forming area 21a will double.

[0054] The present inventor has found that when the positional relationship between the first optical member 12 and the second optical member 13 constituting the upstream optical element 11 is arranged so as to satisfy a predetermined condition, the scanning lines of the first component L11 and the second component L12 do not overlap on the image forming area 21a, and the number of scanning lines on the image forming area 21a can be doubled.The present inventor has then completed the configuration of the light source device 10 of this embodiment.

[0055] Hereinafter, a description will be given of the conditions that the positional relationship between the first optical member 12 and the second optical member 13 must satisfy in order to prevent the scanning lines SL from overlapping each other. In the front-stage optical element 11 shown in Fig. 2, the angle formed between the first incident surface of the first optical member 12 and the second incident surface of the second optical member 13 is defined as θ. The angle θ is defined as the difference between the first angle θ1 and the second angle θ2 shown in Fig. 2. Furthermore, the rotation period of the front-stage optical element 11 by the first rotary drive device 15 is defined as T1, and the rotation period of the rear-stage optical element 14 by the second rotary drive device 16 is defined as T2. The rotation period corresponds to the time it takes for each optical element to make one rotation by the rotary drive device.

[0056] The inventors have confirmed through the simulation described below that the number of scanning lines in the image forming area 21a can be doubled by setting the angle θ between the first incident surface of the first optical member 12 and the second incident surface of the second optical member 13 to the value shown in the following equation (1).

[0057]

number

[0058] In the above formula (1), (T1-T2) / 2 corresponds to half the difference in rotation period between the front-side optical element 11 and the rear-side optical element 14. In other words, the angle θ shown in formula (1) corresponds to an angle shifted by half the difference in rotation period between the front-side optical element 11 and the rear-side optical element 14. In equation (1), r1 is the rotation speed (unit: rps) of the upstream optical element 11. Here, if the scanning frequency of the upstream optical element 11 is f1 and the number of first incident surfaces of the first optical member 12 and second incident surfaces of the second optical member 13 is n1, then the relationship f1 = n1 × r1 is satisfied. Furthermore, the scanning period T1 of the upstream optical element 11 is expressed as the reciprocal of the scanning frequency f1 (T1 = 1 / f1).

[0059] Therefore, the above formula (1) becomes the following formula (2).

number

[0060] For example, if the period (in-plane scanning frequency: 40 Hz) required to complete scanning of the entire image forming area 21a is 0.025 seconds, T1 = 1 / 240 seconds, and T2 = 1 / 200 seconds, then the number n1 of first and second incident surfaces is 4, i.e., the angle θ formed by the square first and second optical members 12 and 13 as in this embodiment is 9 degrees (deg) according to the above formula (2). Furthermore, if the number n1 of first and second incident surfaces is 6, i.e., the angle θ formed by the regular hexagonal first and second optical members is 6 degrees (deg).

[0061] The inventors created several models in which the angle θ between the first optical element 12 and the second optical element 13 was shifted by half the difference in rotational period between the front-stage optical element 11 and the rear-stage optical element 14, and examined the position of the scanning line formed on the image forming area 21a for each model.

[0062] Figures 5A and 5B show the results of this simulation. In this simulation, a model was used in which the in-plane scanning frequency was 40 Hz, T1 = 1 / 240 seconds, T2 = 1 / 200 seconds, and the number of first and second entrance surfaces, n1, was 6. Figure 5A shows the simulation results when the angle θ was set to 0 degrees, 6 degrees, 12 degrees, and 18 degrees, and Figure 5B shows the simulation results when the angle θ was set to 24 degrees, 30 degrees, 36 degrees, and 42 degrees.

[0063] The graphs shown in the upper parts of Figures 5A and 5B are diagrams showing the displacement on the image forming area 21a of the light (second component) transmitted through the second optical member 13 when the angle θ of the second optical member 13 with respect to the first optical member 12 is set to various values. The lower parts of Figures 5A and 5B are diagrams showing the positions of the scanning lines formed on the image forming area 21a when the angle θ is set to various values.

[0064] 5A and 5B, the horizontal axis represents time (s) and the vertical axis represents displacement (mm). An x-y coordinate system was established, with the left-right direction of image forming area 21a as the x-direction, the up-down direction of image forming area 21a as the y-direction, and the origin O as the center coordinate of image forming area 21a. The graphs show the displacement of light on image forming area 21a and the positions of scanning lines formed in response to the displacement. In these graphs, the displacement in the x-direction is indicated by a thick line, and the displacement in the y-direction is indicated by a thin line.

[0065] Note that an angle θ of 0 degrees means that the upstream optical element is composed of a single optical member, and the first and second incident surfaces are composed of the same surface. Furthermore, an angle θ of 6 degrees corresponds to one-half the rotational period difference, an angle θ of 12 degrees corresponds to two-half the rotational period difference, and an angle θ of 18 degrees corresponds to three-half the rotational period difference. Similarly, in Figure 5B, an angle θ of 24 degrees corresponds to four-half the rotational period difference, an angle θ of 30 degrees corresponds to five-half the rotational period difference, an angle θ of 36 degrees corresponds to six-half the rotational period difference, and an angle θ of 42 degrees corresponds to seven-half the rotational period difference.

[0066] 5A and 5B, when the angle θ of the second optical member 13 relative to the first optical member 12, i.e., the angle θ between the first and second incident surfaces, is set to an even multiple (2, 4, 6, etc.) of half the rotational period difference, the scanning line SL is formed so as to pass through the origin O at the timing surrounded by symbol A where the displacement amounts in the x and y directions become 0 during one period of scanning the entire image forming area 21a. In other words, when the angle θ between the first and second incident surfaces is set to an even multiple of half the rotational period difference, the second component L12 separated from the first component L11 in the upstream-side optical element 11 forms the scanning line SL on the image forming area 21a at the same position as when the upstream-side optical element is configured from a single optical member. Therefore, when the angle θ is an even multiple of half the rotation period difference, the scanning lines SL formed on the image forming area 21a by the first component L11 and the second component L12 emitted from the upstream optical element 11 overlap with each other. Therefore, the number of scanning lines SL formed on the image forming area 21a remains the same as when the upstream optical element 11 is configured from a single light-transmitting member.

[0067] In contrast, when the angle θ of the second optical member 13 with respect to the first optical member 12 is set to an odd multiple (1, 3, 5, 7, etc.) of half the rotational period difference, there is no timing when the displacement amounts in the x and y directions become 0 during one period of scanning the entire image forming area 21a, and the scanning line SL is formed so as not to pass through the origin O. In other words, when the angle θ formed by the first incident surface and the second incident surface is set to an odd multiple of half the rotational period difference, the second component L12 separated from the first component L11 in the upstream optical element 11 forms the scanning line SL at a position that does not pass through the origin O of the image forming area 21a. On the other hand, the first component L11 forms a scanning line that passes through the origin of the image forming area 21a.

[0068] Therefore, as shown in the following equation (3), by setting the angle θ of the second optical member 13 relative to the first optical member 12 to an odd multiple (1x, 3x, 5x, 7x, etc.) of half the rotational period difference, the first component L11 and the second component L12 will trace trajectories at different positions on the image forming area 21a, thereby doubling the number of scanning lines formed on the image forming area 21a.

[0069]

number

[0070] The light source device 10 of this embodiment includes a light source unit 10a, a front-stage optical element 11 that transmits light L1 emitted from the light source unit 10a, and a rear-stage optical element 14 that transmits light L1 emitted from the front-stage optical element 11. The front-stage optical element 11 rotates about a first rotation axis C1, and the rear-stage optical element 14 rotates about a second rotation axis C2 that intersects with the first rotation axis C1. The front-side optical element 11 has a first incident surface onto which a first component L11, which is a part of the light L1, is incident and which forms a first angle θ1 with respect to a reference plane RP that is orthogonal to the principal ray of the light L1, a second incident surface onto which a second component L12, which is another part of the light L1, is incident and which forms a second angle θ2 with respect to the reference plane RP that is different from the first angle θ1, a first exit surface from which the first component L11 incident from the first incident surface exits, and a second exit surface from which the second component L12 incident from the second incident surface exits. The rear-side optical element 14 has a third incident surface onto which the light L1 emitted from the front-side optical element 11 is incident and a third exit surface from which the light L1 incident from the third incident surface exits. In the front-stage optical element 11, the first entrance surface and the first exit surface are parallel to each other, and the second entrance surface and the second exit surface are parallel to each other, and in the rear-stage optical element 14, the third entrance surface and the third exit surface are parallel to each other.

[0071] According to the light source device 10 of this embodiment, the front-side optical element 11 separates the light L1 incident from the light source unit 10a, and the separated first component L11 and second component L12 are incident on the rear-side optical element 14. This allows the first component L11 and the second component L12 to be scanned two-dimensionally on the illuminated area. Therefore, when scanning one light two-dimensionally on the illuminated area, the number of scanning lines of light formed on the illuminated area can be doubled. Therefore, according to the light source device 10, the uniformity of the illuminance distribution of light in the illuminated area can be improved, making uneven illuminance in the illuminated area less noticeable.

[0072] Therefore, according to the projector 100 of this embodiment, by using the light source device 10 to increase the uniformity of the illuminance distribution within the image forming area 21a of the light modulation device 21, it is possible to suppress the decrease in brightness and contrast and the occurrence of color unevenness in the light modulation device 21, thereby realizing a projector with excellent display quality.

[0073] (Second embodiment) A second embodiment of the present invention will be described below with reference to FIG. The projector of this embodiment is a three-panel projector that uses three liquid crystal panels as a light modulation device, and differs from the first embodiment, which is a single-panel projector that uses one liquid crystal panel. Note that the same reference numerals are used for components that are common to the first embodiment, and detailed descriptions will be omitted.

[0074] FIG. 6 is a plan view showing a schematic configuration of a projector 200 according to this embodiment. As shown in FIG. 6, the projector 200 of this embodiment includes a light source device 201, a magnifying optical system 202, a color separation optical system 203, a light modulation device 30, an image light combining element 24, and a projection optical device 23.

[0075] The light source device 201 of this embodiment includes a light source unit 210, a front-stage optical element 11, a rear-stage optical element 14, a first rotary drive device 15, and a second rotary drive device 16. The light source unit 210 includes a first light source unit 101, a second light source unit 102, a third light source unit 103, and a light combining optical system 104.

[0076] The first light source unit 101 is disposed such that the optical axis AX1 of the first light source unit 101 is perpendicular to the optical axis AX2 of the second light source unit 102. The third light source unit 103 is disposed such that the optical axis AX3 of the third light source unit 103 is perpendicular to the optical axis AX2 of the second light source unit 102. The first light source unit 101 emits blue light LB toward the -Z side. The third light source unit 103 emits red light LR toward the -Z side. The second light source unit 102 emits green light LG toward the +X side. In this example, the first light source unit 101 is disposed closer to the second light source unit 102, and the third light source unit 103 is disposed farther from the second light source unit 102, but the opposite may also be true.

[0077] The first light source unit 101 has a first light-emitting element 25 and a substrate 29. The first light-emitting element 25 is composed of a laser diode that emits light in a first wavelength band. Therefore, the light emitted from the first light-emitting element 25 is linearly polarized light with coherence, and is laser light with a narrow beam width and high parallelism. The first wavelength band is, for example, a blue wavelength band of 450 nm±5 nm. That is, the first light-emitting element 25 emits blue light LB as the first light.

[0078] The second light source unit 102 has a second light-emitting element 26 and a substrate 29. The second light-emitting element 26 is composed of a laser diode that emits light in a second wavelength band different from the first wavelength band. The light emitted from the second light-emitting element 26 is linearly polarized light with coherence, and is laser light with a narrow beam width and high parallelism. The second wavelength band is, for example, a green wavelength band of 530 nm±5 nm. That is, the second light-emitting element 26 emits green light LG as the second light.

[0079] The third light source unit 103 has a third light-emitting element 27 and a substrate 29. The third light-emitting element 27 is composed of a laser diode that emits light in a third wavelength band different from the first wavelength band and the second wavelength band. The light emitted from the third light-emitting element 27 is coherent linearly polarized light, and is laser light with a narrow beam width and high parallelism. The third wavelength band is, for example, a red wavelength band of 650 nm±5 nm. That is, the third light-emitting element 27 emits red light LR as the third light.

[0080] The light combining optical system 104 includes a first light combining element 105 and a second light combining element 106. The first light combining element 105 is provided at a position where the optical axis AX1 and the optical axis AX2 intersect. The first light combining element 105 is composed of a dichroic mirror that transmits the green light LG and reflects the blue light LB. The second light combining element 106 is provided at a position where the optical axis AX2 and the optical axis AX3 intersect. The second light combining element 106 is composed of a dichroic mirror that transmits the green light LG and the blue light LB and reflects the red light LR. The light combining optical system 104 combines the blue light LB emitted from the first light source unit 101, the green light LG emitted from the second light source unit 102, and the red light LR emitted from the third light source unit 103 to generate white illumination light WL. As a result, the light source unit 210 emits illumination light WL. The illumination light WL is incident on the upstream optical element 11 without being separated by wavelength band.

[0081] In the light source device 201 of this embodiment, when the illumination light WL is scanned within a two-dimensional illuminated area on the illuminated surface, i.e., on each of the light modulation elements 30B, 30G, and 30R, the uniformity of the illuminance distribution can be improved by increasing the number of scanning lines of the light.

[0082] The illumination light WL is incident on the magnifying optical system 202. The magnifying optical system 202 includes, for example, a concave lens 2a and a convex lens 2b. The magnifying optical system 202 magnifies the beam diameter of the illumination light WL emitted from the light source device 201.

[0083] The illumination light WL that has passed through the magnifying optical system 202 enters the color separating optical system 203 . The color separation optical system 203 separates the illumination light WL emitted from the light source device 201 into red light LR, green light LG, and blue light LB, and guides them to the light modulation elements of the light modulation device 30.

[0084] The light modulation device 30 of this embodiment includes a first light modulation element 30B, a second light modulation element 30G, a third light modulation element 30R, and half-wave plates 33B and 33R.

[0085] The color separation optical system 3 includes a first dichroic mirror 7a, a second dichroic mirror 7b, a first total reflection mirror 8a, a second total reflection mirror 8b, and a third total reflection mirror 8c.

[0086] The first dichroic mirror 7a separates the illumination light WL from the light source device 201 into red light LR and light containing green light LG and blue light LB. The first dichroic mirror 7a transmits the blue light LB and reflects the light containing green light LG and red light LR. On the other hand, the second dichroic mirror 7b reflects the green light LG and transmits the red light LR. In this way, the second dichroic mirror 7b separates the light containing green light LG and red light LR into green light LG and red light LR.

[0087] The first total reflection mirror 8a is disposed in the optical path of the blue light LB and reflects the blue light LB that has passed through the first dichroic mirror 7a toward the first light modulation element 30B. Meanwhile, the second total reflection mirror 8b and the third total reflection mirror 8c are disposed in the optical path of the blue light LB and guide the red light LR that has passed through the second dichroic mirror 7b toward the third light modulation element 30R. The green light LG is reflected from the second dichroic mirror 7b toward the second light modulation element 30G.

[0088] The first light modulation element 30B has a light modulation panel 31B and an exit-side polarizing plate 32B. The second light modulation element 30G has a light modulation panel 31G and an exit-side polarizing plate 32G. The third light modulation element 30R has a light modulation panel 31R and an exit-side polarizing plate 32R.

[0089] A transmissive liquid crystal panel is used for each of the light modulation panels 31B, 31G, and 31R. The driving method for the liquid crystal panel is not particularly limited, and may be a twisted nematic (TN) method, a vertically aligned (VA) method, an in-plane switching (IPS) method, or the like. The driving of each of the light modulation panels 31B, 31G, and 31R of the light modulation elements 30B, 30G, and 30R is controlled by a control device electrically connected thereto.

[0090] Each of the exit-side polarizing plates 32B, 32G, and 32R transmits linearly polarized light in a specific direction. In this embodiment, since each of the light source units 101, 102, and 103 of the light source device 201 emits laser light as blue light LB, green light LG, and red light LR, the polarizing plate on the light entrance side of each of the light modulation elements 30B, 30G, and 30R can be omitted.

[0091] The light source device 201 superimposes the blue light LB in time by two-dimensionally scanning it over the image formation area of ​​the first light modulation element 30B. The first light modulation element 30B modulates the blue light LB based on blue image information to generate blue image light B. The light source device 201 temporally superimposes the green light LG by two-dimensionally scanning it over the image formation area of ​​the second light modulation element 30G. The second light modulation element 30G modulates the green light LG based on green image information to generate green image light G. The light source device 201 superimposes the red light LR in time by two-dimensionally scanning the image formation area of ​​the third light modulation element 30R. The third light modulation element 30R modulates the red light LR based on red image information to generate red image light R.

[0092] The image light combining element 24 combines the image light of each color B, G, R emitted from the first light modulation element 30B, the second light modulation element 30G, and the third light modulation element 30R to generate full-color image light, and emits the combined full-color image light toward the projection optical device 23. The image light combining element 24 may be, for example, a cross dichroic prism.

[0093] Half-wave plates 33B and 33R are provided between the first light modulation element 30B and the image light combiner 24, and between the third light modulation element 30R and the image light combiner 24, respectively. The half-wave plates 33B and 33R impart a phase difference of half a wavelength to the incident color light and rotate the polarization direction of the linearly polarized light by 90 degrees. This makes it possible to make the polarization direction of the green image light G incident on the image light combiner 24 different from the polarization directions of the blue image light B and red image light R incident on the image light combiner 24. This configuration can improve the light utilization efficiency of the image light combiner 24. The projection optical device 23 enlarges and projects the image light emitted from the image light synthesizing element 24 onto a projection surface such as a screen, thereby displaying an image on the projection surface.

[0094] In the projector 200 of this embodiment, by increasing the uniformity of the illuminance distribution within the image forming area of ​​each light modulation element 30B, 30G, 30R, it is possible to suppress the decrease in brightness and contrast and the occurrence of color unevenness in each light modulation element 30B, 30G, 30R, thereby realizing a three-plate projector with excellent display quality.

[0095] (Third embodiment) A third embodiment of the present invention will be described below with reference to FIG. The projector of this embodiment is a three-panel projector that uses three liquid crystal panels as a light modulation device, and the configuration of the light source device, etc. is different from that of the second embodiment. Note that the same reference numerals are used for components that are common to the first and second embodiments, and detailed descriptions thereof will be omitted.

[0096] FIG. 7 is a plan view showing a schematic configuration of a projector 300 of this embodiment. 7, the projector 300 of this embodiment includes a light source device 301, a first reflecting mirror 41, a second reflecting mirror 42, a light modulation device 30, an image light combining element 24, and a projection optical device 23. The configuration of the projector 300 other than the light source device 301 is the same as that of the first embodiment.

[0097] The light source device 301 of this embodiment includes a first light source unit 101, a second light source unit 102, a third light source unit 103, a front-stage optical element 11, a first rotary drive device 15, a first rear-stage optical element (rear-stage optical element) 121, a second rear-stage optical element (rear-stage optical element) 122, a third rear-stage optical element (rear-stage optical element) 123, a second rotary drive device 16, a first wavelength-selective reflecting element 71, and a second wavelength-selective reflecting element 72.

[0098] In this embodiment, as in the second embodiment, each of the light source units 101, 102, and 103 includes one light-emitting element 25, 26, and 27. The first light source unit 101 emits blue light LB toward the -Z side. The second light source unit 102 emits green light LG toward the +X side. The third light source unit 103 emits red light LR toward the +Z side. That is, the first light source unit 101 and the third light source unit 103 are disposed opposite each other and emit light in opposite directions. Furthermore, the optical axis AX1 and the optical axis AX3 are located on the same axis and are perpendicular to the optical axis AX2.

[0099] The first wavelength-selective reflecting element 71 is provided on the optical path of the red light LR emitted from the third light source unit 103 between the third light source unit 103 and the upstream optical element 11. The first wavelength-selective reflecting element 71 is composed of a dichroic mirror that reflects blue light and transmits red light.

[0100] The second wavelength-selective reflecting element 72 is provided on the optical path of the blue light LB emitted from the second light source unit 102 between the second light source unit 102 and the upstream optical element 11. The second wavelength-selective reflecting element 72 is composed of a dichroic mirror that transmits blue light and reflects red light.

[0101] The configuration of the front-stage optical element 11 is the same as that of the front-stage optical element 11 in the first embodiment. In this embodiment, multiple colored lights having different wavelength bands are incident on the upstream optical element 11. In this case, it is desirable to use a glass material with small wavelength dispersion, i.e., a glass material with a large Abbe number, as the glass material for the light-transmitting member. Green light LG, blue light LB, and red light LR are emitted from the upstream optical element 11.

[0102] The first rear-stage optical element 121, the second rear-stage optical element 122, and the third rear-stage optical element 123 have the same configuration as the rear-stage optical element 14 of the first embodiment. The first rear-stage optical element 121 is made of a rotatably supported light-transmitting member. The first rear-stage optical element 121 is rotatable about a third rotation axis C3 extending along the Z-axis direction. The shape and size of the first rear-stage optical element 121 are the same as the shape and size of the rear-stage optical element 14. The first rear-side optical element 121 has a seventh surface 121a and an eighth surface 121b that intersect with the third rotation axis C3, and four side surfaces 121c that are perpendicular to the seventh surface 121a and the eighth surface 121b. That is, the shape of the first rear-side optical element 121 is a regular quadrangular prism with six flat surfaces.

[0103] The second rear-stage optical element 122 is made of a rotatably supported light-transmitting member. The second rear-stage optical element 122 is rotatable about a fourth rotation axis C4 extending along the Z-axis direction. The shape and size of the second rear-stage optical element 122 are the same as the shape and size of the first rear-stage optical element 121. The second rear-side optical element 122 has a ninth surface 122a and a tenth surface 122b that intersect with the fourth rotation axis C4, and four side surfaces 122c that are perpendicular to the ninth surface 122a and the tenth surface 122b. That is, the shape of the second rear-side optical element 122 is a regular quadrangular prism with six flat surfaces.

[0104] The third rear-stage optical element 123 is made of a rotatably supported light-transmitting member. The third rear-stage optical element 123 is rotatable about a fifth rotation axis C5 extending along the Z-axis direction. The shape and size of the third rear-stage optical element 123 are the same as the shapes and sizes of the first rear-stage optical element 121 and the second rear-stage optical element 122. The third rear-side optical element 123 has an eleventh surface 123a and a twelfth surface 123b that intersect with the fifth rotation axis C5, and four side surfaces 123c that are perpendicular to the eleventh surface 123a and the twelfth surface 123b. That is, the shape of the third rear-side optical element 123 is a regular quadrangular prism with six flat surfaces.

[0105] The green light LG emitted from the front-stage optical element 11 is incident on the second rear-stage optical element 122. The blue light LB emitted from the front-stage optical element 11 and reflected by the first wavelength-selective reflecting element 71 is incident on the third rear-stage optical element 123. The red light LR emitted from the front-stage optical element 11 and reflected by the second wavelength-selective reflecting element 72 is incident on the first rear-stage optical element 121.

[0106] In the first rear-side optical element 121, the side surface onto which the blue light LB emitted from the front-side optical element 11 is incident is referred to as the fourth entrance surface. The side surface from which the blue light LB incident from the fourth entrance surface is emitted is referred to as the fourth exit surface. The fourth entrance surface and the fourth exit surface change over time and are either of two parallel fourth side surfaces among the four side surfaces 121c. In other words, the fourth entrance surface and the fourth exit surface are parallel to each other.

[0107] In the second rear-side optical element 122, the side surface onto which the green light LG emitted from the front-side optical element 11 is incident is referred to as the fifth entrance surface. The side surface from which the green light LG incident from the fifth entrance surface is emitted is referred to as the fifth exit surface. The fifth entrance surface and the fifth exit surface change over time and are either of two parallel fifth side surfaces among the four side surfaces 122c. In other words, the fifth entrance surface and the fifth exit surface are parallel to each other.

[0108] In the third rear-side optical element 123, the side surface onto which the red light LR emitted from the front-side optical element 11 is incident is referred to as the sixth entrance surface. The side surface from which the red light LR incident from the sixth entrance surface is emitted is referred to as the sixth exit surface. The sixth entrance surface and the sixth exit surface change over time and are either of two sixth side surfaces among the four side surfaces 123c that are parallel to each other. In other words, the sixth entrance surface and the sixth exit surface are parallel to each other.

[0109] The third rotation axis C3 of the first rear-stage optical element 121, the fourth rotation axis C4 of the second rear-stage optical element 122, and the fifth rotation axis C5 of the third rear-stage optical element 123 are located on the same axis. In this embodiment, the first rear-stage optical element 121, the second rear-stage optical element 122, and the third rear-stage optical element 123 are connected to the second rotation drive device 16 via a common shaft. This configuration allows for a reduction in the number of rotation drive devices and a simplification of the device configuration compared to when a rotation drive device is provided for each transmissive optical element. Furthermore, there is no need to synchronize conditions such as the rotation speed and phase of the three optical elements 121, 122, and 123, making rotation control easier. Furthermore, scroll noise caused by missynchronization of rotation can be reduced.

[0110] 7, the optical elements 121, 122, and 123 are each made of a separate light-transmitting member, but instead of this configuration, the optical elements 121, 122, and 123 may be made of a single light-transmitting member. With this configuration, gaps between adjacent transmissive optical elements can be eliminated, thereby enabling the size of the transmissive optical elements to be reduced. In addition, the effects of facilitating rotation control and reducing scroll noise can be obtained.

[0111] The first reflecting mirror 41 reflects the blue light LB emitted from the first subsequent optical element 121 toward the first light modulation element 30B. In this way, the first reflecting mirror 41 bends the optical path of the blue light LB emitted from the first subsequent optical element 121 from the +X direction to the -Z direction.

[0112] The second reflecting mirror 42 reflects the red light LR emitted from the third subsequent optical element 123 toward the third light modulation element 30R. In this way, the second reflecting mirror 42 bends the optical path of the red light LR emitted from the third subsequent optical element 123 from the +X direction to the +Z direction.

[0113] In the projector 300 of this embodiment, by increasing the uniformity of the illuminance distribution within the image forming area of ​​each light modulation element 30B, 30G, 30R, the same effects as in the second embodiment can be obtained, such as suppressing a decrease in brightness and contrast and the occurrence of color unevenness in each light modulation element 30B, 30G, 30R, and a projector 300 capable of displaying color images can be realized.

[0114] 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.

[0115] For example, in the above embodiment, the first optical member 12 and the second optical member 13 constituting the upstream optical element 11 are an integrated optical member, but the first optical member 12 and the second optical member 13 may also be constructed as separate optical members.

[0116] FIG. 8 is a perspective view showing a schematic configuration of a front optical element 111 according to a modified example. 8 is configured such that the first optical member 112 and the second optical member 113 are separate optical members. The rotation drive device 150 that rotates the front optical element 111 includes a first rotating element 151 that rotates the first optical member 112 about a first rotation axis C1, and a second rotating element 152 that rotates the second optical member 113 about the first rotation axis C1. That is, in this modified example, the first optical member 112 and the second optical member 113 are held by rotation elements 151 and 152 that rotate them, respectively.

[0117] According to the configuration of this modified example, the rotation angles of the first optical member 112 and the second optical member 113 can be adjusted individually by the rotation drive device 150, and therefore the angle θ formed between the first incident surface of the first optical member 112 and the second incident surface of the second optical member 113 can be adjusted arbitrarily. Therefore, by appropriately adjusting the angle θ, it is possible to realize a high-value-added light source device that can reduce uneven illuminance in the illuminated area under any driving conditions.

[0118] In addition, the specific descriptions of the shape, number, arrangement, materials, etc. of each component of the light source device and the projector are not limited to the above-described embodiment and can be modified as appropriate. Furthermore, in the above-described embodiment, an example was shown in which the light source device according to the present invention is mounted on a projector using a liquid crystal panel, but this is not limiting. The light source device according to the present invention may also be applied to a projector using a digital micromirror device as a light modulation device.

[0119] A summary of this disclosure is provided below. (Appendix 1) A light source unit; a front-stage optical element that transmits light emitted from the light source unit; a rear-stage optical element that transmits the light emitted from the front-stage optical element; Equipped with the front-stage optical element rotates around a first rotation axis, the rear-stage optical element rotates about a second rotation axis that intersects with the first rotation axis, The front-stage optical element is a first incident surface onto which a portion of the light is incident and which forms a first angle with respect to a reference plane orthogonal to a chief ray of the light; a second incident surface onto which another portion of the light is incident and which forms a second angle with respect to the reference surface that is different from the first angle; a first exit surface that exits a portion of the light incident from the first entrance surface; a second exit surface that exits another portion of the light incident from the second entrance surface, The rear-stage optical element is a third entrance surface onto which the light emitted from the front-stage optical element is incident; a third exit surface that emits the light incident from the third entrance surface, In the front-side optical element, the first entrance surface and the first exit surface are parallel to each other, and the second entrance surface and the second exit surface are parallel to each other; In the rear-stage optical element, the third entrance surface and the third exit surface are parallel to each other. Light source device.

[0120] According to the light source device having this configuration, the front-stage optical element can split the light incident from the light source unit into two beams that are then incident on the rear-stage optical element. This allows the two split beams to be scanned two-dimensionally on the illuminated area. Therefore, when the light emitted from the light source unit is scanned two-dimensionally on the illuminated area for illumination, the number of scanning lines of light formed on the illuminated area can be doubled. Therefore, with the light source device having this configuration, the uniformity of the illuminance distribution of light in the illuminated area can be improved, making uneven illuminance in the illuminated area less noticeable.

[0121] (Appendix 2) the upstream optical element has a front surface and a back surface that intersect with the first rotation axis, 2×m (m: a natural number equal to or greater than 2) first side surfaces that are in contact with the front surface, and 2×m (m: a natural number equal to or greater than 2) second side surfaces that are in contact with the back surface, the first entrance surface and the first exit surface are two of the 2×m first side surfaces that are parallel to each other, The second entrance surface and the second exit surface are two second side surfaces parallel to each other among the 2×m second side surfaces. 10. The light source device of claim 1.

[0122] With this configuration, since there are an even number of first and second side surfaces, all of the first and second side surfaces are parallel to the first and second side surfaces facing them, and no first and second side surfaces are non-parallel, which reduces the generation of stray light in the first and second optical members and improves light utilization efficiency.

[0123] (Appendix 3) the upstream optical element is composed of a first optical member having the first entrance surface and the first exit surface, and a second optical member having the second entrance surface and the second exit surface; 10. The light source device according to claim 1 or 2.

[0124] According to this configuration, the upstream optical element is configured using the first optical member and the second optical member, which makes it easier to manufacture the upstream optical element.

[0125] (Appendix 4) the first optical member and the second optical member are an integral optical member, further comprising a rotation drive device that rotates the first optical member and the second optical member together around the first rotation axis; 4. The light source device according to claim 3.

[0126] According to this configuration, the number of parts in the light source device can be reduced.

[0127] (Appendix 5) the first optical member and the second optical member are separate optical members, the rotary drive device that rotates the front-stage optical element includes a first rotary element that rotates the first optical member around the first rotation axis, and a second rotary element that rotates the second optical member around the first rotation axis; 4. The light source device according to claim 3.

[0128] With this configuration, the rotation angles of the first optical member and the second optical member can be adjusted individually by the rotary drive device, so the angle formed between the first incident surface of the first optical member and the second incident surface of the second optical member can be adjusted as desired. Therefore, by appropriately adjusting the formed angle, it is possible to realize a high-value-added light source device that can reduce uneven illuminance in the illuminated area under any driving conditions.

[0129] (Appendix 6) In the upstream optical element, the refractive index of the first optical member is equal to the refractive index of the second optical member. 4. The light source device according to claim 3.

[0130] According to this configuration, the refraction angles of the light transmitted through the first optical member and the second optical member can be easily aligned, which makes it easy to adjust the optical path of the light transmitted through the upstream optical element.

[0131] (Appendix 7) The angle between the first incident surface and the second incident surface is θ, The rotation period of the front-stage optical element is T1, The rotation period of the rear-stage optical element is T2, When the number of the first side surfaces and the second side surfaces is n1, Satisfy the following formula: 10. The light source device according to claim 2.

number

[0132] This configuration makes it possible to double the number of scanning lines of light formed on the illuminated area.

[0133] (Appendix 8) a light source device according to any one of Supplementary Note 1 to Supplementary Note 7; a light modulation device that modulates the light emitted from the light source device based on image information; a projection optical device that projects the light emitted from the light modulation device, projector.

[0134] With a projector of this configuration, the light source device increases the uniformity of the illuminance distribution in the light modulation device, thereby suppressing the reduction in brightness and contrast and the occurrence of color unevenness in the light modulation device, thereby realizing a projector with excellent display quality. [Explanation of symbols]

[0135] 21, 30... light modulation device, 10, 201, 301... light source device, 10a, 101, 210... light source section, 11... front-stage optical element, 11a... front surface, 11b... rear surface, 12, 112... first optical member, 13, 113... second optical member, 14... rear-stage optical element, 100, 200, 300... projector, 15... first rotation drive device (rotation drive device), 23... projection optical device, 121... first rear-stage optical element Child (rear-stage optical element), 121c, 122c, 123c...side surface, 12c1, 12c2, 12c3, 12c4...first side surface, 13c1, 13c2, 13c3, 13c4...second side surface, 150...rotational drive device, 151...first rotating element, 152...second rotating element, C1...first rotation axis, C2...second rotation axis, L1...light, L1a...light ray (chief ray), RP...reference plane, θ1...first angle, θ2...second angle.

Claims

1. a light source unit; a front-stage optical element that transmits light emitted from the light source unit; a rear-stage optical element that transmits the light emitted from the front-stage optical element; Equipped with the front-stage optical element rotates around a first rotation axis, the rear-stage optical element rotates about a second rotation axis that intersects with the first rotation axis, The front-stage optical element is a first incident surface onto which a portion of the light is incident and which forms a first angle with respect to a reference plane orthogonal to a chief ray of the light; a second incident surface onto which another portion of the light is incident and which forms a second angle with respect to the reference plane that is different from the first angle; a first exit surface that exits a portion of the light incident from the first entrance surface; a second exit surface that exits another portion of the light incident from the second entrance surface, The rear-stage optical element is a third entrance surface onto which the light emitted from the front-stage optical element is incident; a third exit surface that emits the light incident from the third entrance surface, In the front-side optical element, the first incident surface and the first exit surface are parallel to each other, and the second incident surface and the second exit surface are parallel to each other; In the rear-side optical element, the third entrance surface and the third exit surface are parallel to each other. Light source device.

2. the upstream optical element has a front surface and a back surface that intersect with the first rotation axis, 2×m (m: a natural number equal to or greater than 2) first side surfaces that are in contact with the front surface, and 2×m (m: a natural number equal to or greater than 2) second side surfaces that are in contact with the back surface, the first entrance surface and the first exit surface are two of the 2×m first side surfaces that are parallel to each other, The second entrance surface and the second exit surface are two second side surfaces parallel to each other among the 2×m second side surfaces. The light source device according to claim 1 .

3. the upstream optical element is composed of a first optical member having the first entrance surface and the first exit surface, and a second optical member having the second entrance surface and the second exit surface; The light source device according to claim 1 .

4. the first optical member and the second optical member are an integral optical member, a rotation drive device that rotates the first optical member and the second optical member together around the first rotation axis, The light source device according to claim 3 .

5. the first optical member and the second optical member are separate optical members, the rotary drive device that rotates the front-stage optical element includes a first rotary element that rotates the first optical member around the first rotation axis, and a second rotary element that rotates the second optical member around the first rotation axis, The light source device according to claim 3 .

6. In the upstream optical element, the refractive index of the first optical member and the refractive index of the second optical member are equal. The light source device according to claim 3 .

7. The angle between the first incident surface and the second incident surface is θ, The rotation period of the front-stage optical element is T １ , The rotation period of the rear-stage optical element is T ２ , The number of the first side surfaces and the second side surfaces is n １ When Satisfy the following formula: The light source device according to claim 2 . [Equation 1]

8. The light source device according to any one of claims 1 to 7, a light modulation device that modulates the light emitted from the light source device based on image information; a projection optical device that projects the light emitted from the light modulation device, projector.

Images