Light source device and projector

Abstract

To provide a light source device and a projector that can make uniform the illuminance distribution of an illumination target area.SOLUTION: A light source device of the present invention comprises: a light source unit that emits light; and a first transmissive optical element that is formed of a rotatably supported transmissive member, and has a first incidence surface on which the light emitted from the light source unit is incident, and a first emission surface that emits the light incident from the first incidence surface. The first transmissive optical element rotates about a first rotation axis that extends along a second direction intersecting a first direction that is the incidence direction of the light on the first transmissive optical element. The first incidence surface and the first emission surface are parallel to each other. Output from the light source unit changes according to the amount of displacement of the light passing through the rotating first transmissive optical element.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] A projector disclosed in Patent Document 1 below includes a light source device and a rotating prism that scans light emitted from the light source device. In this projector, the light from the light source device is displaced in a direction orthogonal to the optical axis by the rotation of the rotating prism, so that the light is scanned on a light modulation device such as a liquid crystal panel which is an illumination area.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the projector of Patent Document 1 above, since the displacement amount of the light emitted from the light source device does not linearly change according to the rotation angle of the rotating prism, there is a problem that the illuminance distribution in the illumination area becomes non-uniform.

Means for Solving the Problems

[0005] In order to solve the above problems, according to a first aspect of the present invention, there is provided a light source device including a light source unit that emits light, and a first transmissive optical element that is composed of a rotatably supported translucent member and has a first incident surface on which the light emitted from the light source unit is incident, and a first emission surface that emits the light incident from the first incident surface. The first transmissive optical element rotates about a first rotation axis extending along a second direction that intersects a first direction that is the incident direction of the light with respect to the first transmissive optical element. The first incident surface and the first emission surface are parallel to each other, and the output of the light source unit changes according to the displacement amount of the light transmitted through the rotating first transmissive optical element.

[0006] Further, according to a second aspect of the present invention, there is provided a projector including the light source device according to the first aspect, a light modulation device that modulates the light emitted from the light source device according to image information, and a projection optical device that projects the light modulated by the light modulation device.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5A

Figure 5B

Figure 5C

Figure 5D

Figure 5E

Figure 5F

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Embodiments for Carrying Out the Invention

[0008] (First Embodiment) Hereinafter, the first embodiment of the present invention will be described with reference to the drawings. The projector of this embodiment is an example of a liquid crystal projector using a liquid crystal panel as a light modulation device. In the following drawings, for the sake of easy viewing of each component, the scale of the dimensions may be shown differently depending on the component.

[0009] FIG. 1 is a plan view showing the schematic configuration of the projector 20 of this embodiment. FIG. 2 is a side view showing the schematic configuration of the projector 20. In FIG. 2, for the sake of easy viewing of the drawing, only the second light source device is shown for the optical system in the front stage of the light modulation device. FIG. 3 is a perspective view showing the configuration of the second light source device.

[0010] As shown in FIGS. 1 and 2, the projector 20 of this embodiment includes a lighting device 2, a first reflection mirror 41, a second reflection mirror 42, a light modulation device 43G, an emission-side polarizing plate 44G, a light modulation device 43B, an emission-side polarizing plate 44B, a half-wave plate 46B, a light modulation device 43R, an emission-side polarizing plate 44R, a half-wave plate 46R, an image light combining element 45, a projection optical device 23, and a control unit 100. Note that although the projector 20 of this embodiment includes half-wave plates 46B and 46R, it is not necessarily required to include them.

[0011] The lighting device 2 of this embodiment includes a first light source device 11, a second light source device 12, and a third light source device 13. Hereinafter, when collectively referring to these without particularly distinguishing the first light source device 11, the second light source device 12, and the third light source device 13, they may simply be referred to as light source devices 11, 12, and 13.

[0012] The light source devices 11, 12, and 13 emit light in different wavelength bands from each other, but have the same basic configuration. Each of the light source devices 11, 12, and 13 corresponds to the "light source device" in the claims. That is, the projector 20 of this embodiment includes three light source devices 11, 12, and 13 that emit light in different wavelength bands.

[0013] As shown in FIG. 1, the first light source device 11 includes a first light source unit 25, a transmission optical element 15, and a first rotation drive device 35. The second light source device 12 includes a second light source unit 26, a transmission optical element 16, and a second rotation drive device 36. The third light source device 13 includes a third light source unit 27, a transmission optical element 17, and a third rotation drive device 37.

[0014] Hereinafter, in the drawings, explanations will be given using the XYZ orthogonal coordinate system as necessary. The X-axis is an axis parallel to the optical axis AX2 of the second light source device 12. The optical axis AX2 of the second light source device 12 is defined as an axis along the principal ray of the second light LG, which will be described later, emitted from the second light source unit 26. The Y-axis is an axis orthogonal to the X-axis and is an axis along the rotation axis of each of the transmission optical elements 15, 16, and 17. The Z-axis is an axis orthogonal to the X-axis and the Y-axis. The optical axis AX1 of the first light source device 11 is defined as an axis along the principal ray of the first light LB, which will be described later, emitted from the first light source unit 25. The optical axis AX3 of the third light source device 13 is defined as an axis along the principal ray of the third light LR, which will be described later, emitted from the third light source unit 27. The X-axis direction in the present embodiment corresponds to the "first direction" in the claims. The Y-axis direction in the present embodiment corresponds to the "second direction" in the claims. The Z-axis direction in the present embodiment corresponds to the "third direction" in the claims.

[0015] The first light source unit 25 emits the first light LB in the first wavelength band toward the transmission optical element 15. The second light source unit 26 emits the second light LG in the second wavelength band toward the transmission optical element 16. The third light source unit 27 emits the third light LR in the third wavelength band toward the transmission optical element 17. Hereinafter, when collectively referring to the first light source unit 25, the second light source unit 26, and the third light source unit 27 without particularly distinguishing them, they may simply be referred to as the light source units 25, 26, and 27. Each of the light source units 25, 26, and 27 is arranged side by side in the Z-axis direction and emits each light toward the same side (+X side).

[0016] As described above, the basic configurations of the light source devices 11, 12, and 13 are the same. However, since the detailed configuration of the second light source device 12 is illustrated in FIGS. 2 and 3, the specific configuration will be described below by taking the second light source device 12 as an example.

[0017] As shown in FIGS. 2 and 3, the second light source unit 26 includes a plurality of second light emitting elements 26a and a substrate 26b. The second light emitting element 26a is composed of a laser diode that emits a light beam LG0 in the second wavelength band. Therefore, the light beam LG0 emitted from the second light emitting element 26a is linearly polarized light with coherence, a laser beam with a narrow light beam width and high parallelism. The second wavelength band is, for example, a green wavelength band of 530 nm ± 5 nm. That is, the light beam LG0 emitted from the second light emitting element 26a is green light.

[0018] The plurality of second light emitting elements 26a are arranged in a row at a predetermined interval from each other along the Y-axis direction. In the present embodiment, the second light source unit 26 has five second light emitting elements 26a, but the number of the second light emitting elements 26a is not particularly limited as long as the plurality of second light emitting elements 26a are arranged in a row along the Y-axis direction.

[0019] FIG. 4 is a diagram showing a cross section perpendicular to the traveling direction of the second light LG emitted from the second light source unit 26. In the case of the present embodiment, since the light beam LG0 is emitted from each of the five second light emitting elements 26a, the second light LG emitted from the second light source unit 26 is the entire light beam including the five light beams LG0 as shown in FIG. 4. Therefore, the outer edge of the second light LG is defined as the outer edge of the figure circumscribing the five light beams LG0. Further, the principal ray of the second light LG is defined as the ray passing through the center of the figure circumscribing the five light beams LG0. In this case, the cross-sectional shape perpendicular to the principal ray of the second light LG is a strip shape having a major axis extending along the Y-axis direction and a minor axis extending along the Z-axis direction. The length Lz of the minor axis of the cross-sectional shape perpendicular to the principal ray of the second light LG is somewhat shorter than the length of the minor axis extending along the Z-axis direction of the light modulation device 43G.

[0020] As shown in FIG. 1, the first light source unit 25 includes a plurality of first light emitting elements 25a and a substrate 25b. The first light emitting element 25a is composed of a laser diode that emits light in a first wavelength band. Therefore, the light emitted from the first light emitting element 25a is linearly polarized light with coherence, laser light with a narrow light beam width and high parallelism. The first wavelength band is, for example, a blue wavelength band of 450 nm ± 5 nm. That is, the light emitted from the first light emitting element 25a is blue light. In this embodiment, a laser diode is cited as the first light emitting element 25a, but it is not limited thereto. A light source such as an LED or a lamp, an optical system for adjusting the polarization direction of light, an optical system for adjusting the light beam width, a color wheel, etc. can be used, and by generating a light beam with a ratio of Lz / LVz of 1 / 2 or less, it can be replaced with a laser diode.

[0021] The plurality of first light emitting elements 25a are arranged in a row at a predetermined interval along the Y-axis direction, that is, the direction perpendicular to the plane of FIG. 1. The number of the first light emitting elements 25a is not particularly limited as long as the plurality of first light emitting elements 25a are arranged in a row along the Y-axis direction. Hereinafter, the first light LB is referred to as blue light LB.

[0022] The third light source unit 27 includes a plurality of third light emitting elements 27a and a substrate 27b. The third light emitting element 27a is composed of a laser diode that emits light in a third wavelength band. Therefore, the light emitted from the third light emitting element 27a is linearly polarized light with coherence, laser light with a narrow light beam width and high parallelism. The third wavelength band is, for example, a red wavelength band of 650 nm ± 5 nm. That is, the light emitted from the third light emitting element 27a is red light.

[0023] The plurality of third light emitting elements 27a are arranged in a row at a predetermined interval along the Y-axis direction, that is, the direction perpendicular to the plane of FIG. 1. The number of the third light emitting elements 27a is not particularly limited as long as the plurality of third light source units 27 are arranged in a row along the Y-axis direction. Hereinafter, the third light LR is referred to as red light LR.

[0024] In the present embodiment, each light source unit 25, 26, 27 in the light source devices 11, 12, 13 corresponds to the "light source unit" in the claims.

[0025] Although the basic configurations of the respective transmission optical elements 15, 16, 17 are the same, since the detailed configuration of the transmission optical element 16 is illustrated in FIGS. 2 and 3, the following will describe the specific configuration by taking the transmission optical element 16 as an example. In the present embodiment, each transmission optical element 15, 16, 17 in the light source devices 11, 12, 13 corresponds to the "first transmission optical element" in the claims. Further, the rotation axes C1, C2, C3 of the respective transmission optical elements 15, 16, 17 described later respectively correspond to the "first rotation axis" in the claims.

[0026] As shown in FIGS. 1 to 3, the transmission optical element 16 is provided on the optical axis AX2. The transmission optical element 16 is composed of a light-transmitting member that is rotatably supported. As the glass material of the light-transmitting member constituting the transmission optical element 16, for example, optical glass such as BK7 or a light-transmitting material such as resin is used. The transmission optical element 16 is rotatable about a rotation axis C2 extending along the Y-axis direction. The rotation axis C2 is connected to a second rotation driving device 36 composed of a motor or the like. The transmission optical element 16 rotates about the rotation axis C2 by the drive of the second rotation driving device 36.

[0027] As shown in FIG. 3, the transmission optical element 16 has a first surface 16a and a second surface 16b that intersect the rotation axis C2, and four side surfaces 16c that are perpendicular to the first surface 16a and the second surface 16b. That is, the shape of the transmission optical element 16 is a regular quadrangular prism having six planes including the first surface 16a, the second surface 16b, and the four side surfaces 16c. The cross-sectional shape of the transmission optical element 16 cut by a plane perpendicular to the rotation axis C2 is a square. That is, the four side surfaces 16c have the same area as each other, and two side surfaces 16c facing each other are parallel to each other.

[0028] The transmissive optical element 16 transmits the green light LG emitted from the second light source unit 26 while rotating about the rotation axis C2. Therefore, the side surface 16c on which the green light LG emitted from the second light source unit 26 is incident on the transmissive optical element 16 is not fixed to one, but changes over time. In the transmissive optical element 16, the side surface 16c on which the green light LG emitted from the second light source unit 26 is incident corresponds to the "first incident surface", and the side surface 16c that emits the green light LG incident from the first incident surface corresponds to the "first emission surface". In this case, the first incident surface and the first emission surface change over time and are any two parallel side surfaces 16c among the four side surfaces 16c.

[0029] In this specification, when two side surfaces of a transmissive optical element are referred to as being parallel to each other, considering the processing accuracy of the glass material constituting the light transmissive member, the allowable range of the parallelism of light, etc., the case where the angle formed by the two side surfaces is in the range of 0 ± 5 degrees is referred to as "parallel".

[0030] In the case of this embodiment, the transmissive optical element 16 has four side surfaces 16c, but the number of side surfaces 16c does not necessarily have to be four, and it is preferably 2 × n (n: a natural number of 2 or more). That is, the number of side surfaces 16c is preferably an even number such as 6 or 8. If the number of side surfaces 16c is an even number, each of all the side surfaces 16c is parallel to the side surface 16c facing the side surface 16c, and there is no side surface 16c that does not have a parallel pair. Thereby, the generation of stray light in the transmissive optical element 16 is reduced, and the light utilization efficiency can be increased.

[0031] The transmissive optical element 16 may be made of quartz. In the transmissive optical element 16, as the amount of light transmitted through the light-transmissive member increases, the amount of light absorbed by the light-transmissive member also increases, and thermal distortion may occur in the light-transmissive member. In this case, the polarization direction of the green light LG emitted from the second light source unit 26 is disturbed, and the linearly polarized light incident on the light-transmissive member becomes elliptically polarized light and is emitted from the light-transmissive member. As a result, when laser diodes are used for the respective light source units 25, 26, and 27 in the projector 20, the effect that a predetermined contrast can be obtained without providing an incident-side polarizing plate cannot be obtained. That is, even though laser diodes are used for the respective light source units 25, 26, and 27, it becomes necessary to use an incident-side polarizing plate for aligning the polarization directions. Therefore, in order to obtain the above-described effect, it is desirable to use a glass material having a small Young's modulus and a small coefficient of thermal expansion as a glass material with less thermal distortion, and it is desirable to use quartz as an example.

[0032] As shown in FIG. 1, the transmissive optical element 15 is provided on the optical axis AX1. The transmissive optical element 15 is composed of a light-transmissive member that is rotatably supported. The transmissive optical element 15 is rotatable about a rotation axis C1 extending along the Y-axis direction. The rotation axis C1 is connected to the first rotation driving device 35. The transmissive optical element 15 rotates about the rotation axis C1 by the driving of the first rotation driving device 35.

[0033] The transmissive optical element 15 has a first surface 15a and a second surface 15b that intersect the rotation axis C1, and four side surfaces 15c that are perpendicular to the first surface 15a and the second surface 15b. The transmissive optical element 15 transmits the blue light LB emitted from the first light source unit 25 while rotating about the rotation axis C1. In the transmissive optical element 15, the side surface 15c on which the blue light LB emitted from the first light source unit 25 is incident corresponds to the "first incident surface", and the side surface 15c that emits the blue light LB incident from the first incident surface corresponds to the "first emission surface". The first incident surface and the first emission surface change over time and are either one of two parallel side surfaces 15c among the four side surfaces 15c.

[0034] In the case of this embodiment, the transmissive optical element 15 has four side surfaces 15c, but the number of side surfaces 15c does not necessarily have to be four. The number of side surfaces 15c is desirably an even number, such as six, eight, etc. If the number of side surfaces 15c is an even number, each of all the side surfaces 15c is parallel to the side surface 15c facing the said side surface 15c, and there are no non-parallel side surfaces 15c. Thereby, the generation of stray light in the transmissive optical element 15 is reduced, and the light utilization efficiency can be enhanced.

[0035] As shown in FIG. 1, the transmissive optical element 17 is provided on the optical axis AX3. The transmissive optical element 17 is composed of a light-transmissive member supported rotatably. The transmissive optical element 17 is enabled to rotate about a rotation axis C3 extending along the Y-axis direction. The rotation axis C3 is connected to a third rotation driving device 37. The transmissive optical element 17 rotates about the rotation axis C3 by the driving of the third rotation driving device 37.

[0036] The transmissive optical element 17 has a first surface 17a and a second surface 17b intersecting the rotation axis C3, and four side surfaces 17c perpendicularly contacting the first surface 17a and the second surface 17b. While rotating about the rotation axis C3, the transmissive optical element 17 transmits the red light LR emitted from the third light source unit 27. In the transmissive optical element 17, the side surface 17c where the red light LR emitted from the third light source unit 27 is incident corresponds to the "first incident surface", and the side surface 17c that emits the red light LR incident from the first incident surface corresponds to the "first emission surface". The first incident surface and the first emission surface change over time and are any one of two parallel side surfaces 17c among the four side surfaces 17c.

[0037] In the case of this embodiment, the transmissive optical element 17 has four side surfaces 17c, but the number of side surfaces 17c does not necessarily have to be four. The number of side surfaces 17c is desirably an even number, such as six, eight, etc. If the number of side surfaces 17c is an even number, each of all the side surfaces 17c is parallel to the side surface 17c facing the said side surface 17c, and there are no non-parallel side surfaces 17c. Thereby, the generation of stray light in the transmissive optical element 17 is reduced, and the light utilization efficiency can be enhanced.

[0038] Next, the behavior when each of the colored lights LB, LG, and LR passes through each of the transmission optical elements 15, 16, and 17 will be described. Since the behaviors of the colored lights LB, LG, and LR are common to each other, here, the green light LG emitted from the second light source device 12 will be described as an example.

[0039] Figures 5A to 5F are schematic diagrams for explaining the behavior of the green light LG when the transmission optical element 16 of the second light source device 12 rotates. In this example, when viewed from the +Y side, the transmission optical element 16 rotates clockwise about the rotation axis C2, indicating a state where time has elapsed from Figure 5A to Figure 5F.

[0040] In Figures 5A to 5F, the angle formed by the straight line M passing through the rotation axis C2 and perpendicular to the side surface 16c1 of the transmission optical element 16 and the optical axis AX2 is defined as the rotation angle ω of the transmission optical element 16. Actually, the green light LG has a predetermined light beam width in the Z-axis direction, but here, attention is focused on the behavior of the light ray LG0 traveling on the optical axis AX2.

[0041] Figure 5A shows the initial state of the transmission optical element 16. That is, the transmission optical element 16 is not rotating, the straight line M and the optical axis AX2 overlap, and the rotation angle ω is 0 degrees. In this case, since the light ray LG0 is incident perpendicularly to the side surface 16c1, it travels through the inside of the transmission optical element 16 along the optical axis AX2 without refracting at the side surface 16c1. Next, the light ray LG0 is also incident perpendicularly to the side surface 16c3 parallel to the side surface 16c1. Therefore, the light ray is emitted from the transmission optical element 16 without refracting at the side surface 16c3 and travels on the optical axis AX2.

[0042] Next, as shown in FIG. 5B, when the transmissive optical element 16 rotates by a rotation angle ω, the light beam LG0 is incident on the side surface 16c1 at an incident angle equal to the rotation angle ω. Therefore, the light beam LG0 is refracted in the direction shown in the figure (+Z side) and travels inside the transmissive optical element 16. Next, since the light beam LG0 is also incident on the side surface 16c3 at a predetermined incident angle, it is refracted at the side surface 16c3 and emitted from the transmissive optical element 16. At this time, since the side surface 16c1 and the side surface 16c3 are parallel to each other, the incident angle of the light beam LG0 with respect to the side surface 16c1 is equal to the incident angle of the light beam LG0 with respect to the side surface 16c3, and the refraction angle of the light beam LG0 incident on the side surface 16c1 and the refraction angle of the light beam LG0 emitted from the side surface 16c3 have opposite signs and equal absolute values. As a result, the refraction angle at the time of incidence of the light beam LG0 on the side surface 16c1 and the refraction angle at the time of emission from the side surface 16c3 are canceled out. As a result, the light beam LG0 travels parallel to the optical axis AX2 at a position displaced by a displacement amount d from the optical axis AX2 to the +Z side.

[0043] Next, as shown in FIG. 5C, when the rotation angle ω of the transmissive optical element 16 becomes larger than that in FIG. 5B, the incident angle of the light beam LG0 becomes larger and the refraction angle becomes larger. Therefore, the displacement amount d of the light beam LG0 from the optical axis AX2 becomes larger than that in FIG. 5B. Also, the state in which the light beam LG0 travels parallel to the optical axis AX2 is always maintained. When the rotation angle ω is between 0 degrees and 45 degrees, the displacement amount d increases monotonically as the rotation angle ω increases.

[0044] Next, as shown in FIG. 5D, when the rotation angle ω of the transmissive optical element 16 exceeds 45 degrees, the incident surface of the light beam LG0 changes from the side surface 16c1 to the side surface 16c2. At this time, the light beam LG0 is refracted at the side surface 16c2, but the refraction direction changes from the period when the rotation angle ω is between 0 degrees and 45 degrees as in FIG. 5C, and is refracted in the direction shown in the figure (-Z side). The emission surface of the light beam LG0 also changes from the side surface 16c3 to the side surface 16c4, but since the side surface 16c2 and the side surface 16c4 are parallel to each other, the relationship that the refraction angle at the time of incidence of the light beam LG0 on the side surface 16c3 and the refraction angle at the time of emission from the side surface 16c4 are canceled out does not change from the period up to FIG. 5C. As a result, the light beam LG0 travels parallel to the optical axis AX2 at a position displaced by a displacement amount d from the optical axis AX2 to the -Z side.

[0045] Next, as shown in FIG. 5E, when the rotation angle ω of the transmissive optical element 16 becomes larger than that in FIG. 5D, the incident angle of the light beam LG0 becomes smaller and the refraction angle becomes smaller. Therefore, the displacement amount d of the light beam LG0 from the optical axis AX2 becomes smaller than that in FIG. 5D. Thus, when the rotation angle ω is between 45 degrees and 90 degrees, the displacement amount d decreases monotonically as the rotation angle ω increases.

[0046] Next, as shown in FIG. 5F, when the rotation angle ω of the transmissive optical element 16 reaches 90 degrees, the incident surface changes from the side surface 16c1 in the initial state to the side surface 16c2, but the behavior of the light beam LG0 becomes the same as that in the initial state shown in FIG. 5A.

[0047] Thus, if the first incident surface and the first emission surface of the transmissive optical element 16 are parallel to each other, regardless of the rotation angle ω of the transmissive optical element 16, the traveling direction of the light beam LG0 does not change, and the light beam LG0 translates in a direction parallel to the optical axis AX2 over time. Here, considering the period during which light is incident from one end to the other end of one first incident surface as one period, the rotation angle ω when light is incident on one end of the first incident surface can be considered as -45 degrees, and the rotation angle ω when light is incident on the other end of the first incident surface can be considered as 45 degrees. At this time, when the rotation angle ω is 0 degrees, the displacement amount d of the light beam LG0 is 0. When the rotation angle ω is between 0 degrees and -45 degrees, the displacement amount increases on the -Z side, and when the rotation angle ω is between 0 degrees and 45 degrees, the displacement amount d increases on the +Z side. Also, at the moment when the rotation angle ω exceeds 45 degrees, the absolute value of the displacement amount d remains the same while the direction of displacement is reversed. When the rotation angle ω is between 45 degrees and 90 degrees, the displacement amount d decreases, and when the rotation angle ω reaches 90 degrees, the displacement amount d becomes 0. After 90 degrees, the above behavior is repeated. Therefore, when the transmissive optical element 16 rotates once, the displacement amount d of the light beam LG0 repeats the above cycle four times. That is, the displacement amount of the green light LG transmitted through the rotating transmissive optical element 16 changes periodically. Note that the displacement amount of the light beam LG0 can be appropriately set by adjusting parameters such as the refractive index and size of the transmissive optical element 16.

[0048] As described above, the behavior of light has been explained by focusing only on the light beam LG0 traveling on the optical axis AX2. However, in reality, as shown in FIG. 3, the green light LG linearly extends long in the Y-axis direction orthogonal to the Z-axis direction in which the green light LG is displaced. Therefore, the green light LG is scanned within the two-dimensional illuminated area Q in the light modulation device 43G which is the illuminated surface. The blue light LB emitted from the first light source device 11 and the red light LR emitted from the third light source device 13 are also reflected by the respective reflection mirrors 41 and 42 described later, and then, like the green light LG, are scanned within the two-dimensional illuminated area Q in the light modulation devices 43B and 43R which are the illuminated surfaces. In this way, when each of the transmission optical elements 15, 16, and 17 rotates about each rotation axis C1, C2, and C3, each of the blue light LB, the green light LG, and the red light LR is scanned in the Z-axis direction orthogonal to the Y-axis direction, thereby scanning within the two-dimensional illuminated area Q on the illuminated surface. In the present embodiment, the Z-axis direction corresponds to the "first scanning direction" in the claims. Note that since the blue light LB is reflected in the -Z direction by the reflection mirror 41 as described later and enters the light modulation device 43B, the scanning direction on the light modulation area (illuminated area Q) of the light modulation device 43B becomes the X-axis direction. Further, since the red light LR is reflected in the +Z direction by the reflection mirror 42 as described later and enters the light modulation device 43R, the scanning direction on the light modulation area (illuminated area Q) of the light modulation device 43R becomes the X-axis direction.

[0049] As shown in FIG. 1, the first reflection mirror 41 reflects the blue light LB emitted from the transmission optical element 15 toward the light modulation device 43B. In this way, the first reflection mirror 41 bends the optical path of the blue light LB emitted from the transmission optical element 15 from the +X direction to the -Z direction.

[0050] The second reflection mirror 42 reflects the red light LR emitted from the transmission optical element 17 toward the light modulation device 43R. In this way, the second reflection mirror 42 bends the optical path of the red light LR emitted from the transmission optical element 17 from the +X direction to the +Z direction.

[0051] The light modulation device 43G modulates the green light LG emitted from the second light source unit 26 of the second light source device 12 according to the image information to form green image light. The light modulation device 43B modulates the blue light LB emitted from the first light source unit 25 of the first light source device 11 according to the image information to form blue image light. The light modulation device 43R modulates the red light LR emitted from the third light source unit 27 of the third light source device 13 according to the image information to form red image light. A transmissive liquid crystal panel is used for each of the light modulation devices 43G, 43B, and 43R. As the driving method of the liquid crystal panel, a twisted nematic (TN) method, a vertical alignment (VA) method, an in-plane switching (IPS) method, etc. are used and are not particularly limited.

[0052] Regarding the installation positions of the respective light modulation devices 43G, 43B, and 43R, it is desirable to consider them as follows. When the light emitted from each light emitting element of the light source unit is an ideal Gaussian beam, when five light emitting elements arranged at equal intervals are lit, as the light propagates, the combined illuminance distribution obtained by combining the illuminance distributions of the five lights gradually becomes averaged and smooth. Furthermore, when the light emitted from each light emitting element has propagated a predetermined distance, the combined illuminance distribution becomes a flat shape with almost no unevenness. Therefore, it is desirable to set the distance from each light emitting element to the illuminated surface, that is, the distance from each light emitting element to each of the light modulation devices 43G, 43B, and 43R, to be equal to the distance at which the combined illuminance distribution composed of a plurality of lights becomes a flat shape. Thereby, a uniform illuminance distribution can be obtained in each of the light modulation devices 43G, 43B, and 43R.

[0053] As shown in FIG. 1, on the light emission side of each of the light modulation devices 43G, 43B, and 43R, emission side polarizing plates 44G, 44B, and 44R are respectively provided. The emission side polarizing plates 44G, 44B, and 44R transmit linearly polarized light in a specific direction.

[0054] The image light synthesizing element 45 synthesizes image light corresponding to red light LR, green light LG, and blue light LB when image light of each color emitted from the light modulation devices 43G, 43B, and 43R is incident thereon, and emits the synthesized image light toward the projection optical device 23. For example, a cross dichroic prism is used for the image light synthesizing element 45.

[0055] A half-wave plate 46B and a half-wave plate 46R are provided between the light modulation device 43B and the image light synthesizing element 45 and between the light modulation device 43R and the image light synthesizing element 45, respectively. The half-wave plates 46B and 46R impart a phase difference of a half wavelength to the incident color light and rotate the polarization direction of linearly polarized light by 90 degrees. Thereby, the polarization direction of the green light LG incident on the image light synthesizing element 45 can be made different from the polarization directions of the blue light LB and the red light LR incident on the image light synthesizing element 45. According to this configuration, the efficiency of the image light synthesizing element 45 can be increased.

[0056] The projection optical device 23 is composed of a plurality of projection lenses. The projection optical device 23 enlarges and projects the image light emitted from the image light synthesizing element 45 toward a projection surface such as a screen. Thereby, an image is displayed on the projection surface.

[0057] The control unit 100 is constituted by, for example, a computer or an integrated circuit having a program for processing components including the light source devices 11, 12, and 13 of the illumination device 2 and each driving device for driving each of the light modulation devices 43R, 43G, and 43B. That is, the control unit 100 is, for example, a processor. The control unit 100 is connected to components including the light source devices 11, 12, and 13 of the illumination device 2 and each of the light modulation devices 43R, 43G, and 43B by a wired or wireless connection (not shown).

[0058] In the above description, when the light emitted from each of the light source units 25, 26, and 27 illuminates by scanning over each of the light modulation devices 43B, 43G, and 43R, the illuminance distribution of the light illuminating each of the light modulation devices 43B, 43G, and 43R has not been considered. However, when the light transmitted through the rotating transmissive optical element is temporally scanned on the optical modulation device as described above, unevenness usually occurs in the illuminance distribution formed on the optical modulation device. The inventor of the present invention performed simulations to examine how various parameters such as the refractive index and shape of the transmissive optical element affect the illuminance distribution in the illuminated area. The simulation results will be described below.

[0059] FIG. 6 is a schematic diagram showing a transmissive optical element 18 serving as a simulation model. The transmissive optical element may have a cross-sectional shape perpendicular to the rotation axis that is a regular n-sided polygon (n is an even number of 4 or more), but in FIG. 6, the cross-sectional shape of the transmissive optical element 18 is a square (n = 4). Further, the distance between the opposing surfaces of the transmissive optical element 18 is denoted as l, the refractive index of the external space of the transmissive optical element 18 is denoted as n1, and the refractive index of the transmissive optical element 18 is denoted as n2.

[0060] As shown in FIG. 6, the optical axis AX of a light-emitting element (not shown) that emits a light ray L1a toward the transmissive optical element 18 passes through the center of the rotation axis O of the transmissive optical element 18. The light ray L1a travels parallel to the optical axis AX, enters the first incident surface 18a of the transmissive optical element 18 at an incident angle θ1 at point P1, is refracted at a refraction angle θ2, and then is emitted from the first emission surface 18b of the transmissive optical element 18 at point P2 and travels parallel to the optical axis AX.

[0061] The light ray L1a transmitted through the rotating transmissive optical element 18 travels parallel to the optical axis AX at a position displaced by a displacement amount d corresponding to the rotation angle of the transmissive optical element 18 in a direction orthogonal (intersecting) to the optical axis AX. Therefore, the following equation (1) holds between the displacement amount d of the light ray L1a, the incident angle θ1, and the refraction angle θ2 from Snell's law.

[0062]

Equation

[0063] Further, the maximum incident angle θmax of the light ray L1a in the transmissive optical element 18 is expressed by the following equation (2).

[0064]

Number

[0065] Here, for example, regarding the formula (1), the distance l between the opposing surfaces of the transmissive optical element 18 is set to 20 mm, the refractive index n1 of the external space is 1.0 (air), the rotation angle (degrees) is taken on the horizontal axis, the displacement amount (mm) is taken on the vertical axis, and when the refractive index n2 of the transmissive optical element 18 is plotted at appropriate intervals from 1.3 to 1000, the relationship between the rotation angle and the displacement amount can be represented by a periodic function. Further, when the refractive index n2 of the transmissive optical element 18 is increased towards infinity for this periodic function, the relationship between the rotation angle and the displacement amount can be defined by an ideal sine wave with an amplitude of l.

[0066] As described above, the rotation angle of the transmissive optical element 18 is equal to the incident angle θ1. Therefore, regarding the rotation angle of the transmissive optical element 18, it suffices to consider within the range of the maximum incident angle θmax of the light ray L1a. Also, the maximum incident angle θmax of the transmissive optical element 18 is determined according to the cross-sectional shape as shown by the formula (2). That is, when the cross-sectional shape of the transmissive optical element 18 is square as shown in FIG. 6, the maximum incident angle θmax is at most 45 degrees. Therefore, when the light ray L1a traveling on the optical axis AX passing through the rotation center of the transmissive optical element 18 is displaced in the direction orthogonal to the optical axis AX by passing through the transmissive optical element 18, it was considered that it was sufficient to examine the periodic function showing the relationship between the rotation angle and the displacement amount of the transmissive optical element 18 only within the angular range of ±45 degrees.

[0067] FIG. 7 is a diagram showing the periodic function cut out in the angular range of ±45 degrees. In FIG. 7, the horizontal axis is the rotation angle (degrees), and the vertical axis is the displacement amount (mm). The graph of symbol A shows the case where the refractive index n2 is 1.3. The graph of symbol B shows the case where the refractive index n2 is 1.5. The graph of symbol C shows the case where the refractive index n2 is 1.6. The graph of symbol D shows the case where the refractive index n2 is 1.8. The graph of symbol E shows the case where the refractive index n2 is 1.8. The graph of symbol F shows the case where the refractive index n2 is 2.0. The graph of symbol G shows the case where the refractive index n2 is 3.0.

[0068] As shown in FIG. 7, although the displacement amount is a monotonically increasing graph, it was found that as the refractive index n2 of the transmissive optical element 18 increases from 1.5 to 3.0, the linearity of the graph becomes higher. Also, it was found that the closer the angular range of the rotation angle is to ±45 degrees, the higher the linearity of the graph showing the displacement amount becomes. That is, when the cross-sectional shape of the transmissive optical element 18 is square, it was found that the linearity of the graph showing the displacement amount becomes low, that is, the non-linearity becomes high.

[0069] The inventors focused on the fact that by increasing the linearity of the graph showing the displacement amount, the uniformity of the illuminance distribution of light in the illuminated area can be improved. Since it is difficult to realize forming the transmissive optical element with a material having a refractive index of 3.0 or more at the present stage, the inventors considered it difficult to increase the linearity of the displacement amount by devising the material of the transmissive optical element. As a result of intensive research, the inventors found that by adjusting the light output according to the displacement amount of light generated by the rotating transmissive optical element, the in-plane illuminance distribution of the illuminated area can be made uniform. And the projector 20 of the present embodiment was completed.

[0070] Hereinafter, a method for equalizing the in-plane illuminance distribution of the illuminated area in the projector 20 of the present embodiment will be described. Hereinafter, the case of equalizing the illuminance distribution of the green light LG emitted from the second light source unit 26 of the second light source device 12 will be described as an example. That is, a method of controlling the output of the second light source unit 26 that emits the green light LG according to the displacement amount of the green light LG generated by the rotating transmissive optical element 16 by the control unit 100 will be described. Note that the same concept also holds for the method of equalizing the illuminance distribution by the blue light LB emitted from the first light source unit 25 of the first light source device 11 and the red light LR emitted from the third light source unit 27 of the third light source device 13.

[0071] FIG. 8 is a diagram showing a graph of the relationship between the rotation angle of the transmissive optical element 16 and the displacement amount of the green light LG transmitted through the transmissive optical element 16. In FIG. 8, only the section from the rotation angle of 0 degrees to 45 degrees in which the displacement amount of the green light LG changes in the -Z direction is shown, and the section from the rotation angle of -45 degrees to 0 degrees in which the displacement amount of the green light LG changes in the opposite +Z direction is not shown. The slope per unit time in the graph shown in FIG. 8 is defined by the hypotenuse of a triangle having the rotation amount per unit time (change amount of the rotation angle) of the transmissive optical element 16 as the base and the displacement amount per unit time of the green light LG as the height. Note that the length of the unit time is arbitrarily set.

[0072] Let the rotation amount per unit time of the transmissive optical element 16 be Δθ, the displacement amount per unit time in the vicinity of the rotation angle of 0 degrees be Δd, and the slope of the graph per unit time in the vicinity of the rotation angle of 0 degrees be φ. Also, let the displacement amount per unit time in the vicinity of the rotation angle of 45 degrees be Δd´, and the slope of the graph per unit time in the vicinity of the rotation angle of 45 degrees be φ´. At this time, the displacement amount Δd can be expressed as Δθ×tanφ, and the displacement amount Δd´ can be expressed as Δθ×tanφ´. Since the graph shown in FIG. 8 has linearity, a difference occurs between the displacement amount Δd and the displacement amount Δd´.

[0073] The slope of the graph shown in FIG. 8 corresponds to the degree of change in the displacement amount of the green light LG when the transmissive optical element 16 rotates per unit time. That is, the slope of the graph shown in FIG. 8 corresponds to the speed of the green light LG scanning the illuminated area. Therefore, the greater the slope of the graph, the higher the speed of the green light LG scanning the illuminated area.

[0074] Here, we consider the case where the output of the green light LG incident on the transmissive optical element 16, that is, the emission intensity of the green light LG is constant. When the emission intensity of the green light LG is constant in this way, the greater the slope of the graph, the faster the speed of the green light LG passing through the illuminated area, and thus the smaller the integrated light amount of the green light LG per unit area of the illuminated area. That is, the integrated light amount in the region near 0 degrees where the rotation angle of the transmissive optical element 16 with a small slope of the graph is small is larger than the integrated light amount in the region near 45 degrees where the rotation angle of the transmissive optical element 16 with a large slope of the graph is large. Therefore, when the output of the green light LG incident on the transmissive optical element 16 is constant, variations occur in the uniformity of the illuminance distribution by the green light LG scanning in one direction over the illuminated area.

[0075] On the other hand, in the projector 20 of the present embodiment, the output of the second light source unit 26 is adjusted so as to cancel out the difference in the integrated light amount of the green light LG caused by the difference in the displacement amount corresponding to the height of the triangle that determines the slope of the graph shown in FIG. 8.

[0076] The output of the second light source unit 26 may be changed by the control unit 100 by controlling the current supplied to the second light source unit 26. The control unit 100 changes the emission intensity of the green light LG emitted from the second light source unit 26 by controlling the current supplied to each light emitting element 26a of the second light source unit 26. When controlling the current supplied to the second light source unit 26 in this way, bright green light LG can be stably emitted from the second light source unit 26. In addition, since the output of the second light source unit 26 can be controlled finely in a short time, the uniformity of the illuminance distribution of the illuminated area by the green light LG can be further enhanced.

[0077] Alternatively, the output of the second light source unit 26 may be changed by the control unit 100 by controlling the duty ratio of the voltage supplied to the second light source unit 26. The control unit 100 changes the emission intensity of the green light LG emitted from the second light source unit 26 by switching the ON / OFF of the voltage supplied to each light emitting element 26a of the second light source unit 26. When controlling the duty ratio of the voltage supplied to the second light source unit 26 in this way, the output control of the second light source unit 26 becomes easy even when suppressing the output of the green light LG to a low level.

[0078] The control unit 100 adjusts the output of the second light source unit 26 every time a unit time elapses. Note that the unit time at which the control unit 100 adjusts the output is adjusted to an optimal value according to the optical characteristics, rotational speed, etc. of the transmissive optical element 16 that affect the displacement amount of the green light LG.

[0079] Here, let the time when the rotation angle of the transmissive optical element 16 reaches a certain angle be the first time t1, the time after another unit time has elapsed from the first time t1 be the second time t2, and the time after another unit time has elapsed from the second time t2 be the third time t3. Note that it is assumed that the rotation angle of the transmissive optical element 16 increases in the order of the first time t1, the second time t2, and the third time t3. And, the period from the first time t1 to the second time t2 is referred to as the first period T1, and the period from the second time t2 to the third time t3 is referred to as the second period T2. That is, the first period T1 and the second period T2 are consecutive periods, and their times are equal to each other. Also, let the slope of the graph shown in FIG. 8 corresponding to the displacement amount in the first period T1 be φ 1 and the slope of the graph shown in FIG. 8 corresponding to the displacement amount in the second period T2 be φ 2 be.

[0080] When the displacement amount of the green light LG in the first period T1 is the first displacement amount Δd 1 , the first displacement amount Δd 1 =Δθtanφ 1 is expressed as. When the displacement amount of the green light LG in the second period T2 is the second displacement amount Δd 2 , Δd 2 =Δθtanφ 2 is expressed as. The second displacement amount Δd 2 is larger than the first displacement amount Δd 1 .

[0081] The output of the second light source unit 26 at the first time t1 is P 1 , the output of the second light source unit 26 at the second time t2 is P2 be set as follows. The control unit 100 sets the output P of the second light source unit 26 at the second time t2 2 to the output P of the second light source unit 26 at the first time t1 1 and multiplies it by the inverse ratio (Δd 2 / Δd 1 ) that cancels out the difference in the displacement amounts of the two, that is, P 2 =P 1 ×Δd 2 / Δd 1 and adjusts the light emission intensity of each light emitting element 26a of the second light source unit 26 accordingly. Then, the control unit 100 drives the second light source unit 26 so that the output P 2 is obtained during the second period T2. That is, the output of the second light source unit 26 in the second period T2 is made larger than the output of the light source unit 26 in the first period T1.

[0082] By adjusting the output of the second light source unit 26 in the second period T2 to P 2 in this way, the integrated light amount of the green light LG that illuminates the illuminated area in the second period T2 can be increased. Therefore, the control unit 100 can equalize the integrated light amount of the green light LG that illuminates the illuminated area between the consecutive first period T1 and second period T2.

[0083] When the incident angle of the green light LG with respect to the transmissive optical element 16 changes from the minimum incident angle (0 degrees) to the maximum incident angle (45 degrees), the control unit 100 controls the driving of the second light source unit 26 so that the output of the second light source unit 26 in the subsequent period and the output of the second light source unit 26 in the previous period satisfy the above relationship in the consecutive periods before and after.

[0084] That is, when the output of the second light source unit 26 at the nth (n is an integer of 1 or more) time is P n , the displacement amount of the green light LG from the nth time to the (n + 1)th time after the elapse of one unit time is Δd n , and the displacement amount of the green light LG from the (n + 1)th time to the (n + 2)th time after the elapse of one unit time is Δd n+1 , the output P n+1 of the second light source unit 26 at the (n + 1)th time satisfies the following equation (3).

[0085] P n+1 = P n ×Δd n+1 / Δd n …(3)

[0086] Therefore, the projector 20 of the present embodiment controls the driving of the second light source unit 26 by the control unit 100 so as to satisfy the relationship of the above formula (3). Thereby, the second light source unit 26 can improve the uniformity of the illuminance distribution in the illuminated area as described later. In the graph shown in FIG. 8, as the incident angle of the green light LG approaches the maximum incident angle (45 degrees) according to the rotation angle of the transmissive optical element 16, the displacement amount of the green light LG increases. Therefore, the control unit 100 controls the output of the second light source unit 26 to increase as the rotation angle increases. Although not shown in FIG. 8, in the section where the incident angle of the green light LG approaches the minimum incident angle (0 degrees) as the rotation angle of the transmissive optical element 18 increases, the slope of the graph showing the displacement amount of the green light LG decreases. Therefore, the control unit 100 controls the output of the second light source unit 26 to decrease as the rotation angle increases.

[0087] In the projector 20 of the present embodiment, while the transmissive optical element 16 makes one rotation, the displacement amount of the green light LG changes periodically. The projector 20 of the present embodiment is configured such that the control unit 100 periodically changes the output of the second light source unit 26 in synchronization with the displacement amount of the green light LG. According to the projector 20 of the present embodiment, by appropriately adjusting the output of the second light source unit 26 according to the displacement amount of the green light LG, the uniformity of the illuminance distribution of the green light LG that scans the light modulation area of the light modulation device 43G, which is the illuminated area, in one direction can be efficiently improved.

[0088] Further, the projector 20 of the present embodiment appropriately adjusts according to the displacement amount of the blue light LB transmitted through the transmissive optical element 15 that rotates the output of the first light source unit 25 of the first light source device 11, thereby enhancing the uniformity of the illuminance distribution of the blue light LB that scans the light modulation region of the light modulation device 43B, which is the illuminated region, in one direction. Also, the projector 20 of the present embodiment appropriately adjusts according to the displacement amount of the red light LR transmitted through the transmissive optical element 17 that rotates the output of the third light source unit 27 of the third light source device 13, thereby enhancing the uniformity of the illuminance distribution of the red light LR that scans the light modulation region of the light modulation device 43R, which is the illuminated region, in one direction.

[0089] As described above, the projector 20 of the present embodiment includes a first light source device 11, a second light source device 12, a third light source device 13, light modulation devices 43B, 43G, 43R that modulate the respective color lights LB, LG, LR emitted from the light source devices 11, 12, 13 according to image information, and a projection optical device 23 that projects the light modulated by the light modulation devices 43B, 43G, 43R.

[0090] The first light source device 11 includes a first light source unit 25 that emits blue light LB, and a transmissive optical element 16 that is configured from a light transmissive member supported rotatably, and has a first incident surface on which the blue light LB emitted from the first light source unit 25 is incident, and a first emission surface that emits the blue light LB incident from the first incident surface. The transmissive optical element 16 rotates about a rotation axis C1 extending along the Z direction, the first incident surface and the first emission surface are parallel to each other, and the output of the first light source unit 25 changes according to the displacement amount of the blue light LB transmitted through the rotating transmissive optical element 16. Further, the second light source device 12 includes a second light source unit 26 that emits green light LG, and a transmissive optical element 17 on which the green light LG emitted from the second light source unit 26 is incident and that rotates about a rotation axis C2 extending along the Z direction. The output of the second light source unit 26 changes according to the displacement amount of the green light LG transmitted through the rotating transmissive optical element 17. Further, the third light source device 13 includes a third light source unit 27 that emits red light LR, and a transmissive optical element 18 that is irradiated with the red light LR emitted from the third light source unit 27 and rotates about a rotation axis C3 extending along the Z direction. The output of the third light source unit 27 changes according to the displacement amount of the red light LR that has passed through the rotating transmissive optical element 18.

[0091] According to each of the light source devices 11, 12, and 13, as shown in FIGS. 5A to 5F, each of the blue light LB, green light LG, and red light LR is displaced in a direction orthogonal to the traveling direction of each color light LB, LG, LR while maintaining a state parallel to the respective optical axes AX1, AX2, AX3 corresponding to the respective color lights LB, LG, LR as the transmissive optical elements 15, 16, and 17 rotate. Further, since each of the color lights LB, LG, LR has an elongated shape having a major axis along the extending direction of the respective rotation axes C1, C2, C3, each of the color lights LB, LG, LR can be scanned within a two-dimensional illumination region Q on an arbitrary illumination surface, specifically, within the light modulation regions of the respective light modulation devices 43B, 43G, 43R.

[0092] Since the displacement amounts of the respective color lights LB, LG, LR have non-linearity that is not proportional to the rotation angles of the respective transmissive optical elements 15, 16, 17, the scanning speeds of the respective color lights LB, LG, LR within the light modulation regions of the respective light modulation devices 43B, 43G, 43R do not become constant. On the other hand, according to the configuration of the present embodiment, by changing the emission intensity of each of the color lights LB, LG, LR according to the displacement amount of each of the color lights LB, LG, LR, it is possible to improve the uniformity of the illuminance distribution within the light modulation regions of the respective light modulation devices 43B, 43G, 43R by each of the color lights LB, LG, LR.

[0093] In each of the light source devices 11, 12, and 13 of the above-described embodiment, a square has been given as an example of the cross-sectional shape of each of the transmissive optical elements 15, 16, and 17. However, a transmissive optical element having a cross-sectional shape with an even number of sides of 6 or more may be used. In this case, the linearity of the displacement amounts of the respective color lights LB, LG, and LR is most deteriorated when the cross-sectional shape of the transmissive optical element is square. For this reason, if a transmissive optical element having a cross-sectional shape with an even number of sides of 6 or more is used, the decrease in the non-linearity of the displacement amounts of the respective color lights LB, LG, and LR is suppressed, so that the adjustment of the emission intensities of the respective color lights LB, LG, and LR becomes easier. Therefore, the uniformity of the illuminance distribution within the light modulation regions of the respective light modulation devices 43B, 43G, and 43R can be increased more simply.

[0094] Therefore, according to the projector 20 of the present embodiment, it is possible to suppress a decrease in brightness, contrast, color unevenness, and light loss in the projection optical device 23 in the light modulation devices 43B, 43G, and 43R, and to realize a projector with excellent display quality with a simple configuration.

[0095] (Second Embodiment) Hereinafter, a second embodiment of the present invention will be described with reference to FIGS. 9 and 10. The basic configuration of the projector of the present embodiment is the same as that of the first embodiment, and the configuration of the light source device is different from that of the first embodiment. FIG. 9 is a plan view showing a schematic configuration of a projector 30 of the present embodiment. FIG. 10 is a perspective view showing the configuration of the second light source device. In FIGS. 9 and 10, the same reference numerals are given to the components common to the drawings of the first embodiment, and the description thereof is omitted.

[0096] As shown in FIG. 9, the projector 30 of this embodiment includes a lighting device 3, a first reflection mirror 41, a second reflection mirror 42, a light modulation device 43G, an emission-side polarizing plate 44G, a light modulation device 43B, an emission-side polarizing plate 44B, a half-wave plate 46B, a light modulation device 43R, an emission-side polarizing plate 44R, a half-wave plate 46R, an image light combining element 45, a projection optical device 23, and a control unit 100. Among the projector 30, the configurations other than the lighting device 3 are the same as those in the first embodiment.

[0097] The lighting device 3 of this embodiment includes a first light source device 111, a second light source device 112, and a third light source device 113. The first light source device 111 includes a first light source unit 125, a transmission optical element 15, a first rotation driving device 35, a transmission optical element 55 on the subsequent stage side, and a fourth rotation driving device 64. The second light source device 12 includes a second light source unit 126, a transmission optical element 16, a second rotation driving device 36, a transmission optical element 56 on the subsequent stage side, and a fifth rotation driving device 65. The third light source device 13 includes a third light source unit 127, a transmission optical element 17, a third rotation driving device 37, a transmission optical element 57 on the subsequent stage side, and a fifth rotation driving device 65.

[0098] The arrangements of the respective light source units 125, 126, and 127 are the same as the arrangements of the respective light source units 25, 26, and 27 in the first embodiment. That is, the first light source unit 125, the second light source unit 126, and the third light source unit 127 are arranged side by side in the Z-axis direction and emit respective color lights LB, LG, and LR toward the same side (+X side). However, while the respective light source units 25, 26, and 27 in the first embodiment include a plurality of light-emitting elements 25a, 26b, and 27c arranged in the Y-axis direction, the respective light source units 125, 126, and 127 in this embodiment include one light-emitting element 125a, 126a, and 127a. Therefore, the cross-sectional shape perpendicular to the principal rays of the respective color lights LB, LG, and LR emitted from the respective light source units 125, 126, and 127 does not necessarily have a shape with a major axis extending along the Y-axis direction.

[0099] In the case of this embodiment, unlike the first embodiment, since the respective color lights LB, LG, and LR emitted from the light source units 125, 126, and 127 do not extend long along the Y-axis direction, the length of the side of the transmissive optical elements 15, 16, and 17 in the Y-axis direction may be made smaller than the lengths of the sides in the X-axis and Z-axis directions. That is, each of the transmissive optical elements 15, 16, and 17 may have a rectangular parallelepiped shape in which the length of the side in the Y-axis direction is shorter than the lengths of the sides in the X-axis and Z-axis directions, instead of a shape close to the cube shown in FIG. 10. Thereby, these transmissive optical elements 15, 16, and 17 can be made thinner.

[0100] The transmissive optical elements 55, 56, and 57 on the subsequent stage side have the same configuration as the transmissive optical elements 15, 16, and 17, but are installed in a posture in which the transmissive optical elements 15, 16, and 17 are each rotated 90 degrees about the X-axis. Hereinafter, the transmissive optical elements 55, 56, and 57 on the subsequent stage side will be simply referred to as the transmissive optical elements 55, 56, and 57, respectively. In the light source devices 111, 112, and 113 of this embodiment, each of the transmissive optical elements 55, 56, and 57 corresponds to the "second transmissive optical element" in the claims. Also, the rotation axes C4, C5, and C6 of each of the transmissive optical elements 55, 56, and 57 described later respectively correspond to the "second rotation axis" in the claims.

[0101] The transmissive optical element 56 is provided on the light emission side (subsequent stage side) of the transmissive optical element 16 on the optical axis AX2. The transmissive optical element 56 is composed of a light transmissive member that is rotatably supported. As the glass material of the light transmissive member constituting the transmissive optical element 56, for example, optical glass such as BK7, quartz, a light transmissive material such as resin is used. The transmissive optical element 56 is rotatable about a rotation axis C5 extending along the Z-axis direction. The rotation axis C5 is connected to a fifth rotation driving device 65 composed of a motor or the like. The transmissive optical element 56 rotates about the rotation axis C5 by the drive of the fifth rotation driving device 65.

[0102] As shown in FIG. 9, the transmissive optical element 56 has a third surface 56a and a fourth surface 56b that intersect the rotation axis C5, and four side surfaces 56c that are perpendicular to the third surface 56a and the fourth surface 56b. That is, the shape of the transmissive optical element 56 is a regular quadrangular prism having six planes including the third surface 56a, the fourth surface 56b, and the four side surfaces 56c. The cross-sectional shape of the transmissive optical element 56 cut by a plane perpendicular to the rotation axis C5 is a square. That is, the four side surfaces 56c have the same area as each other, and two side surfaces 56c facing each other are parallel to each other.

[0103] The transmissive optical element 56 transmits the green light LG emitted from the transmissive optical element 16 while rotating about the rotation axis C5. Therefore, the side surface 56c through which the green light LG emitted from the transmissive optical element 16 enters the transmissive optical element 56 is not fixed to one, but changes over time. In the transmissive optical element 56, the side surface 56c through which the green light LG emitted from the transmissive optical element 16 enters corresponds to the "second incident surface", and the side surface 56c that emits the green light LG incident from the second incident surface corresponds to the "second emission surface". The second incident surface and the second emission surface change over time and are any two of the four side surfaces 56c that are parallel to each other.

[0104] In the case of this embodiment, the transmissive optical element 56 has four side surfaces 56c, but the number of side surfaces 56c does not necessarily have to be four, and it is preferably 2×p (p: a natural number of 2 or more). That is, the number of side surfaces 56c is preferably an even number such as 6 or 8. If the number of side surfaces 56c is an even number, each of all the side surfaces 56c is parallel to the side surface 56c facing the side surface 56c, and there is no non-parallel side surface 56c. Thereby, the generation of stray light in the transmissive optical element 56 is reduced, and the light utilization efficiency can be improved.

[0105] As shown in FIG. 9, the transmissive optical element 55 is provided on the light emission side (rear stage side) of the transmissive optical element 15 on the optical axis AX1. The transmissive optical element 55 is composed of a light transmissive member that is rotatably supported. The transmissive optical element 55 is rotatable about a rotation axis C4 extending along the Z-axis direction. The rotation axis C4 is connected to a fourth rotation driving device 64. The transmissive optical element 55 rotates about the rotation axis C4 by driving the fourth rotation driving device 64.

[0106] The transmissive optical element 55 has a third surface 55a and a fourth surface 55b that intersect the rotation axis C4, and four side surfaces 55c that are perpendicular to the third surface 55a and the fourth surface 55b. The transmissive optical element 55 transmits the blue light LB emitted from the transmissive optical element 15 while rotating about the rotation axis C4. In the transmissive optical element 55, the side surface 55c on which the blue light LB emitted from the transmissive optical element 15 is incident corresponds to the "second incident surface", and the side surface 55c that emits the blue light LB incident from the second incident surface corresponds to the "second emission surface". The second incident surface and the second emission surface change over time and are any one of two parallel side surfaces 55c among the four side surfaces 55c.

[0107] In the case of this embodiment, the transmissive optical element 55 has four side surfaces 55c, but the number of the fourth side surfaces 55c does not necessarily have to be four. It is desirable that the number of the side surfaces 55c is an even number, such as six or eight. If the number of the side surfaces 55c is an even number, each of all the side surfaces 55c is parallel to the side surface 55c facing it, and there is no non-parallel side surface 55c. Thereby, the generation of stray light in the transmissive optical element 55 is reduced, and the light utilization efficiency can be improved.

[0108] The transmission optical element 57 is provided on the light emission side (rear stage side) of the transmission optical element 17 on the optical axis AX3. The transmission optical element 57 is composed of a translucent member that is rotatably supported. The transmission optical element 57 is rotatable about a rotation axis C6 extending along the Z-axis direction. The rotation axis C6 is connected to a sixth rotation drive device 66. The transmission optical element 57 rotates about the rotation axis C6 by the drive of the sixth rotation drive device 66.

[0109] The transmission optical element 57 has a third surface 57a and a fourth surface 57b that intersect the rotation axis C6, and four side surfaces 57c that are perpendicular to the third surface 57a and the fourth surface 57b. While rotating about the rotation axis C6, the transmission optical element 57 transmits the red light LR emitted from the transmission optical element 17. In the transmission optical element 57, the side surface 57c on which the red light LR emitted from the transmission optical element 17 is incident corresponds to the "second incident surface", and the side surface 57c that emits the red light LR incident from the second incident surface corresponds to the "second emission surface". The second incident surface and the second emission surface change over time and are either one of two parallel side surfaces 57c among the four side surfaces 57c.

[0110] In the case of this embodiment, the transmission optical element 57 has four side surfaces 57c, but the number of side surfaces 57c does not necessarily have to be four. It is desirable that the number of side surfaces 57c be an even number, such as six or eight. If the number of side surfaces 57c is an even number, each of all the side surfaces 57c is parallel to the side surface 57c facing it, and there are no non-parallel side surfaces 57c. Thereby, less stray light is generated in the transmission optical element 57, and the light utilization efficiency can be improved.

[0111] The rotation axes C4, C5, and C6 are arranged on a straight line extending in the Z-axis direction. According to this configuration, the size of the illumination device 3 in the X-axis direction can be reduced compared to the case where the three rotation axes C4, C5, and C6 are not arranged on a straight line extending in the Z-axis direction.

[0112] In the case of this embodiment, since the respective color lights LB, LG, and LR pass through the two transmissive optical elements 15, 16, 17, 55, 56, and 57, the respective color lights LB, LG, and LR are displaced in two directions orthogonal to each other over time. Specifically, as shown in FIG. 10, the green light LG emitted from the second light source unit 126 is scanned in the Z-axis direction by the transmissive optical element 16 and is scanned in the Y-axis direction orthogonal to the Z-axis direction by the transmissive optical element 56. That is, the green light LG emitted from the second light source unit 126 is scanned within the two-dimensional illuminated region Q (light modulation device 43G) on the illuminated surface by the transmissive optical element 16 and the transmissive optical element 56. The moving speed of the green light LG scanning within the illuminated region Q changes by passing through the rotating transmissive optical elements 16 and 56. On the other hand, in the projector 30 of this embodiment, the control unit 100 appropriately adjusts the output of the second light source unit 26 according to the displacement amount of the green light LG generated by the rotating transmissive optical elements 16 and 56, thereby enhancing the uniformity of the illuminance distribution of the green light LG illuminating the illuminated region Q (light modulation device 43G).

[0113] Similarly, the blue light LB emitted from the first light source unit 125 is scanned within the two-dimensional illuminated region Q (light modulation device 43B) on the illuminated surface by the transmissive optical element 15 and the transmissive optical element 55. The moving speed of the blue light LB scanning within the illuminated region Q changes by passing through the rotating transmissive optical elements 15 and 55. On the other hand, in the projector 30 of this embodiment, the control unit 100 appropriately adjusts the output of the first light source unit 25 according to the displacement amount of the blue light LB generated by the rotating transmissive optical elements 15 and 55, thereby enhancing the uniformity of the illuminance distribution of the blue light LB illuminating the illuminated region Q (light modulation device 43B).

[0114] Similarly, the red light LR emitted from the third light source unit 127 is scanned within the two-dimensional illuminated region Q (optical modulation device 43R) on the illuminated surface by the transmissive optical element 17 and the transmissive optical element 57. The moving speed of the red light LR scanning within the illuminated region Q changes by passing through the rotating transmissive optical elements 17 and 57. On the other hand, in the projector 30 of the present embodiment, the control unit 100 appropriately adjusts the output of the third light source unit 27 according to the displacement amount of the red light LR generated by the rotating transmissive optical elements 17 and 57, thereby enhancing the uniformity of the illuminance distribution of the red light LR illuminating the illuminated region Q (optical modulation device 43R).

[0115] In the present embodiment, the Z-axis direction corresponds to the "first scanning direction" in the claims, and the Y-axis direction corresponds to the "second scanning direction" in the claims. Note that since the blue light LB is reflected in the -Z direction by the reflection mirror 41 and enters the optical modulation device 43B, it is scanned in the X-axis direction on the light modulation region (illuminated region Q) of the optical modulation device 43B. Also, since the red light LR is reflected in the +Z direction by the reflection mirror 42 and enters the optical modulation device 43R, it is scanned in the X-axis direction on the light modulation region (illuminated region Q) of the optical modulation device 43R. Other configurations of the projector 30 are the same as those in the first embodiment.

[0116] Also in the present embodiment, the same effects as those in the first embodiment can be obtained, such as the problems of reduction in brightness and contrast, generation of color unevenness, light loss in the projection optical device 23, and illuminance unevenness due to the use of a light source having coherence in the optical modulation devices 43B, 43G, and 43R can be improved.

[0117] In the present embodiment, the transmissive optical elements 55, 56, and 57 may be connected to each other along the Z-axis direction. According to this configuration, the three rotation driving devices 64, 65, and 66 can be shared, and the rotation control of each of the transmissive optical elements 55, 56, and 57 becomes easy.

[0118] (First Modification Example) Hereinafter, the first modification example of the present invention will be described. This modification example relates to a modification of the projector of the first embodiment. The basic configuration of the projector of this modification example is the same as that of the first embodiment, and the configuration including the moving mechanism for moving the projection optical device 23 is different from that of the first embodiment.

[0119] FIG. 11 is a plan view showing the schematic configuration of the projector 20A of this modification example. In FIG. 11, the same reference numerals are given to the components common to the drawings of the first embodiment, and the description thereof is omitted. As shown in FIG. 11, the projector 20A of this modification example includes an illumination device 2, a first reflection mirror 41, a second reflection mirror 42, a light modulation device 43G, an emission-side polarizing plate 44G, a light modulation device 43B, an emission-side polarizing plate 44B, a half-wave plate 46B, a light modulation device 43R, an emission-side polarizing plate 44R, a half-wave plate 46R, an image light synthesizing element 45, a projection optical device 23, a control unit 100, and a moving mechanism 123.

[0120] The moving mechanism 123 holds the projection optical device 23 so as to be movable at least in the YZ plane. The projector 20A of this modification example can adjust the position of the image projected onto the screen (the surface to be projected) from the projection optical device 23 by moving the projection optical device 23 by the moving mechanism 123.

[0121] Here, when the projection optical device 23 is moved by the moving mechanism 123, the amount of the image light synthesized by the image light synthesizing element 45 that is absorbed by the projection optical device 23 changes. Specifically, in the projection optical device 23, the amount of absorption in the peripheral portion is reduced compared to the central portion of the image light emitted from the light modulation regions of the respective light modulation devices 43B, 43G, and 43R. Therefore, when the image projection position is moved by the moving mechanism 123, uneven illuminance is more likely to occur in the image projected onto the screen.

[0122] On the other hand, when the projection optical device 23 is moved by the moving mechanism 123, each of the light source units 25, 26, 27 is configured to increase the output of the light that illuminates the outer edge of the rectangular illumination area illuminated by each color light LB, LG, LR (the outer edge of the light modulation area of the light modulation devices 43B, 43G, 43R) compared to the output of the light that illuminates the central portion of the illuminated area located inside the outer edge.

[0123] Specifically, in the projector 20A of this modification, similar to the first embodiment, the control unit 100 changes the emission intensity of each color light LB, LG, LR according to the displacement amount of each color light LB, LG, LR, thereby enhancing the uniformity of the illuminance distribution throughout the light modulation areas of the light modulation devices 43B, 43G, 43R. Further, when the projection optical device 23 is moved by the moving mechanism 123, the control unit 100 controls the output of each of the light source units 25, 26, 27 so as to make the emission intensity of each color light LB, LG, LR stronger in the section where the outer edge of the light modulation area is scanned. Here, the section where the outer edge of the light modulation area is scanned corresponds to the section in which the incident angle of the light with respect to each of the transmission optical elements 15, 16, 17 becomes around (including) the maximum incident angle during one rotation of each of the transmission optical elements 15, 16, 17.

[0124] According to the projector 20A of this modification, by increasing the amount of light at the outer edge of the light modulation areas of the light modulation devices 43B, 43G, 43R where the light absorption amount in the projection optical device 23 decreases, it is possible to suppress the occurrence of uneven illuminance in the image projected onto the screen even when the image projection position is moved by the moving mechanism 123.

[0125] (Second Modification) Hereinafter, a second modification of the present invention will be described. This modification relates to a modification of the projector of the second embodiment. The basic configuration of the projector of this modification is the same as that of the second embodiment, and the configuration including the moving mechanism for moving the projection optical device 23 is different from that of the second embodiment.

[0126] FIG. 12 is a plan view showing a schematic configuration of the projector 30A of this modified example. In FIG. 12, the same reference numerals are given to the components common to the drawings of the second embodiment, and the description thereof is omitted. As shown in FIG. 12, the projector 30A of this modified example is the same as the projector 30 of the second embodiment except that it includes the moving mechanism 123 of the first modified example.

[0127] Also in this modified example, when the projection optical device 23 is moved by the moving mechanism 123, each of the light source units 125, 126, and 127 is configured such that the output of the light illuminating the outer edge of the rectangular illuminated area (the outer edge of the light modulation area of the light modulation devices 43B, 43G, 43R) illuminated by each color light LB, LG, LR is higher than the output of the light illuminating the central portion of the illuminated area located inside the outer edge.

[0128] Specifically, in the projector 30A of this modified example, as in the second embodiment, the control unit 100 changes the emission intensity of each color light LB, LG, LR according to the displacement amount of each color light LB, LG, LR, thereby enhancing the uniformity of the illuminance distribution over the entire light modulation area of each light modulation device 43B, 43G, 43R. Further, when the projection optical device 23 is moved by the moving mechanism 123, the control unit 100 controls the output of each light source unit 125, 126, 127 so that the emission intensity of each color light LB, LG, LR is stronger in the section where the outer edge of the light modulation area is scanned. Here, the section where the outer edge of the light modulation area is scanned corresponds to the section in which the incident angle of light with respect to each of the transmission optical elements 15, 16, 17, 55, 56, 57 is around the maximum incident angle (including the maximum incident angle) during one rotation of each of the transmission optical elements 15, 16, 17, 55, 56, 57.

[0129] According to the projector 30A of this modified example, by increasing the amount of light at the outer edge of the light modulation area of the light modulation devices 43B, 43G, 43R where the absorption amount in the projection optical device 23 decreases, it is possible to suppress the occurrence of uneven illuminance in the image projected onto the screen even when the image projection position is moved by the moving mechanism 123.

[0130] (Third Modified Example) Hereinafter, a third modification example of the present invention will be described. This modification example relates to a modification of the projector of the second embodiment. The basic configuration of the projector of this modification example is the same as that of the second embodiment, and the control method of each light source unit 25, 26, 27 by the control unit 100 is different from that of the second embodiment.

[0131] In the configurations of the second embodiment and the second modification example, the outputs of the respective light source units 125, 126, 127 were controlled according to the displacement amounts of the respective color lights LB, LG, LR generated by the rotation of the respective transmissive optical elements 15, 16, 17, 55, 56, 57. However, the outputs of the respective light source units 125, 126, 127 may be controlled according to the displacement amounts of the respective color lights LB, LG, LR transmitted through one of the transmissive optical elements.

[0132] Here, for example, it is assumed that the refractive indices and shapes of the transmissive optical elements 15 and 55 through which the blue light LB sequentially passes are different from each other, and the refractive index of the transmissive optical element 15 is smaller than the refractive index of the transmissive optical element 55. As shown in the graph of FIG. 7, the smaller the refractive index of the transmissive optical element, the greater the non-linearity of the light displacement amount. That is, the non-linearity of the displacement amount by the transmissive optical element 15 becomes larger than the non-linearity of the displacement amount by the transmissive optical element 55. In such a case, the output of the light source unit 25 may be controlled so as to change according to the displacement amount of the blue light LB transmitted through the rotating transmissive optical element 15 and not to change according to the displacement amount of the blue light LB transmitted through the rotating transmissive optical element 55. According to this configuration, since the output of the light source unit 25 is controlled only when passing through the transmissive optical element 15, the output control of the light source unit 25 by the control unit 100 becomes easy. Note that when the refractive index of the transmissive optical element 55 is smaller than the refractive index of the transmissive optical element 15, the control unit 100 may change the output of the light source unit 25 only according to the displacement amount of the blue light LB transmitted through the transmissive optical element 55.

[0133] Also, in the case where the refractive index of the transmission optical element 16 through which the green light LG passes in sequence is smaller than the refractive index of the transmission optical element 56, the same applies. Also, in the case where the refractive index of the transmission optical element 17 through which the red light LR passes in sequence is smaller than the refractive index of the transmission optical element 57, the same applies. According to this configuration, since the output of the light source units 26 and 27 is controlled only when passing through one of the transmission optical elements 16 and 17, the output control of the light source units 26 and 27 by the control unit 100 becomes easy.

[0134] For example, assume that the cross-sectional shape of the transmission optical element 15 is square and the cross-sectional shape of the transmission optical element 55 is regular hexagon. As shown in the above formula (2), the larger the number of side faces of the transmission optical element, the smaller the maximum incident angle of light in the transmission optical element, and the smaller the non-linearity of the light displacement amount. That is, the non-linearity is the largest when the cross-sectional shape of the transmission optical element is square (the number of side faces is 4). Therefore, the non-linearity of the displacement amount by the transmission optical element 15 is larger than the non-linearity of the displacement amount by the transmission optical element 55. In such a case, the output of the light source unit 25 may be controlled so as to change according to the displacement amount of the blue light LB that has passed through the rotating transmission optical element 15 and not to change according to the displacement amount of the blue light LB that has passed through the rotating transmission optical element 55. According to this configuration, since the output of the light source unit 25 is controlled only when passing through the transmission optical element 15, the output control of the light source unit 25 by the control unit 100 becomes easy. In the case where the number of side faces of the transmission optical element 55 is smaller than the number of side faces of the transmission optical element 15, the control unit 100 may change the output of the light source unit 25 only according to the displacement amount of the blue light LB that has passed through the transmission optical element 55.

[0135] Also, in the transmissive optical elements 16 and 56 through which the green light LG passes in order, the same applies when the number of side surfaces of the transmissive optical element 16 is smaller than the number of side surfaces of the transmissive optical element 56. Also, in the transmissive optical elements 17 and 57 through which the red light LR passes in order, the same applies when the number of side surfaces of the transmissive optical element 17 is smaller than the number of side surfaces of the transmissive optical element 57. According to this configuration, since the output of the light source units 26 and 27 is controlled only when passing through one of the transmissive optical elements 16 and 17, the output control of the light source units 26 and 27 by the control unit 100 becomes easy.

[0136] Note that the technical scope of the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, it is also possible to use it for the purpose of arranging images projected from a plurality of projectors of the present invention on a screen to display a single large image. In such a case, since a part of the ends of two adjacent images overlap each other, it is preferable to lower the brightness of the overlapping part of the images. In this case, each projector may enhance the uniformity of the illuminance distribution except for a part within the light modulation regions of the respective light modulation devices 43B, 43G, and 43R by changing the emission intensity of each of the color lights LB, LG, and LR according to the displacement amount of each color light LB, LG, and LR. For example, each projector may control each light source unit so that the control unit 100 does not adjust the emission intensity of each of the color lights LB, LG, and LR in a section that scans the outer edge of the light modulation region of each of the light modulation devices 43B, 43G, and 43R corresponding to the end of the image that overlaps the image of another projector. As described above, in the section that scans the outer edge of the light modulation region, the incident angle of light with respect to the transmissive optical element approaches the maximum incident angle. Therefore, if the emission intensity of each of the color lights LB, LG, and LR is not adjusted, the brightness of the illuminated region will be low. For this reason, it is not necessary to compensate for the light amount of each of the color lights LB, LG, and LR that scan the outer edge of the light modulation region of each of the light modulation devices 43B, 43G, and 43R that generate the end of the image whose brightness may be low due to overlapping with the image of another projector.

[0137] According to this configuration, it is not necessary to perform output control of the light source unit for the entire light modulation region of each of the optical modulation devices 43B, 43G, and 43R, so that the output control of the light source unit by the control unit 100 becomes easy.

[0138] Further, in the light source device of the above embodiment, as the shape of the transmission optical element, an example of a polygonal prism with an even number of side surfaces was given. From the viewpoint of less generation of stray light and high light utilization efficiency, a polygonal prism with an even number of side surfaces is desirable. However, as long as it has a pair of incident surfaces and exit surfaces parallel to each other, a shape other than a polygonal prism with an even number of side surfaces may be used. In addition, the "rotation" in the embodiment of the present application can include performing similar scanning by swinging the transmission optical element.

[0139] In addition, regarding the specific descriptions of the shapes, numbers, arrangements, materials, etc. of the respective components of the light source device and the projector, the above embodiments are not restrictive, and appropriate changes can be made. Further, in the above embodiment, an example in which the light source device according to the present invention is mounted on a projector using a liquid crystal panel was shown, but the present invention is not limited to this. The light source device according to the present invention may be applied to a projector using a digital micromirror device as the optical modulation device.

[0140] Further, the light source device of the present invention may be applied to an illumination device for a barcode reader that receives light reflected by a barcode. The illumination device for a barcode reader illuminates the barcode by scanning light over time, but generally, the light amount in the peripheral portion is more likely to decrease than in the central portion of the barcode. For this reason, there is a problem that it is more difficult to read the data at the end of the barcode than the data in the central portion of the barcode for the barcode reader. If the illumination device of the present invention is used for barcode reader applications, the barcode can be illuminated uniformly, so that the reading accuracy of the barcode can be improved.

[0141] Hereinafter, a summary of the present disclosure will be appended. (Appendix 1) A light source unit that emits light, A first transmissive optical element composed of a rotatably supported translucent member, having a first incident surface on which the light emitted from the light source unit is incident, and a first emission surface that emits the light incident from the first incident surface. The first transmissive optical element rotates about a first rotation axis extending along a second direction that intersects a first direction which is the incident direction of the light with respect to the first transmissive optical element. The first incident surface and the first emission surface are parallel to each other. The output of the light source unit changes according to the displacement amount of the light transmitted through the rotating first transmissive optical element. Light source device.

[0142] According to the light source device having this configuration, the light emitted from the light source unit is displaced in a direction intersecting the traveling direction of the light while maintaining a state parallel to the optical axis of the light source unit as the first transmissive optical element rotates. For this reason, there is a risk that the speed at which the light scans in one direction within the illuminated area is not constant, causing unevenness in the illuminance distribution of the illuminated area. On the other hand, according to this configuration, the uniformity of the illuminance distribution of the illuminated area can be enhanced by adjusting the output of the light source unit according to the displacement amount of the light transmitted through the first transmissive optical element.

[0143] (Appendix 2) The light transmitted through the rotating first transmissive optical element travels parallel to the optical axis at a position where it has moved by the displacement amount corresponding to the rotation angle of the first transmissive optical element in a direction intersecting the optical axis of the light source unit. The light source device according to Appendix 1.

[0144] According to this configuration, by changing the displacement amount of the light according to the rotation angle of the first transmissive optical element as it rotates, a configuration in which the light is scanned in one direction within the illuminated area as described above can be realized.

[0145] (Appendix 3) The first transmissive optical element scans the light emitted from the light source unit in a first scanning direction by rotating about the first rotation axis. The light source device according to Appendix 1 or Appendix 2.

[0146] According to this configuration, by scanning the light emitted from the light source unit, it is possible to illuminate within a one-dimensional illuminated area.

[0147] (Appendix 4) The first transmissive optical element is made of quartz. The light source device according to any one of Appendices 1 to 3.

[0148] According to this configuration, since the Young's modulus and the coefficient of thermal expansion of quartz are small, the thermal distortion of the first transmissive optical element is small, and the disturbance of the polarization direction of light can be suppressed.

[0149] (Appendix 5) The light source unit includes a light emitting element composed of a laser diode that emits laser light. The light source device according to any one of Appendices 1 to 4.

[0150] According to this configuration, since the light emitted from the light source unit is linearly polarized laser light, when an optical modulation device such as a liquid crystal panel is arranged in the illuminated area, the incident-side polarizing plate can be omitted.

[0151] (Appendix 6) The displacement amount of the light changes periodically. The output of the light source unit changes periodically in synchronization with the displacement amount of the light. The light source device according to any one of Appendices 1 to 5.

[0152] According to this configuration, since the output of the light source unit is appropriately adjusted according to the displacement amount of the light, the uniformity of the illuminance distribution in the illuminated area can be efficiently improved.

[0153] (Appendix 7) Let the displacement amount of the light in the first period be the first displacement amount, and the displacement amount of the light in the second period different from the first period be the second displacement amount. When the second displacement amount is larger than the first displacement amount, the output of the light source unit in the second period is larger than the output of the light source unit in the first period. The light source device according to Supplementary Note 6.

[0154] According to this configuration, by increasing the integrated light amount of the light illuminating the illuminated area in the second period, the integrated light amounts of the light illuminating the illuminated area in the consecutive first period and second period can be made uniform. Therefore, as described above, the uniformity of the illuminance distribution of the illuminated area can be enhanced.

[0155] (Supplementary Note 8) The output of the light source unit changes by controlling the current value supplied to the light source unit. The light source device according to any one of Supplementary Notes 1 to 7.

[0156] According to this configuration, by controlling the supply current, bright light can be stably emitted from the light source unit. Also, since the output of the light source unit can be controlled precisely in a short time, the uniformity of the illuminance distribution of the illuminated area can be further enhanced.

[0157] (Supplementary Note 9) The output of the light source unit changes by controlling the duty ratio of the voltage supplied to the light source unit. The light source device according to any one of Supplementary Notes 1 to 7.

[0158] According to this configuration, by controlling the duty ratio of the voltage, even when suppressing the output of the light to a low level, the output control of the light source unit becomes easy.

[0159] (Supplementary Note 10) Let the output of the light source unit at the nth (n is an integer of 1 or more) time be P n , Let the displacement amount of the light from the nth time to the (n + 1)th time after the elapse of a unit time be Δd n , Let the displacement amount of the light from the (n + 1)-th moment to the (n + 2)-th moment after the elapse of a unit time be Δd. n+1 When the output P of the light source unit at the (n + 1)-th moment n+1 satisfies the following formula The light source device according to any one of Appendices 1 to 9. P n+1 = P n ×Δd n+1 / Δd n

[0160] According to this configuration, the light source unit can accurately adjust the output according to the displacement amount of the light, thereby improving the uniformity of the illuminance distribution in the illuminated area well.

[0161] (Appendix 11) The illuminated area illuminated by the light transmitted through the first transmission optical element is rectangular, and the light source unit makes the output of the light illuminating the outer edge of the illuminated area higher than the output of the light illuminating the inside of the outer edge. The light source device according to any one of Appendices 1 to 10.

[0162] According to this configuration, the brightness of the outer edge can be made brighter than that of the central part of the illuminated area. Therefore, even when the optical member that captures the light emitted from the illuminated area is moved relative to the illuminated area, a decrease in the amount of light absorbed by the optical member can be suppressed.

[0163] (Appendix 12) Further includes a second transmission optical element composed of a rotatably supported translucent member, having a second incident surface on which the light is incident and a second emission surface that emits the light incident from the second incident surface, the second incident surface and the second emission surface are parallel to each other, by rotating the second transmission optical element about a second rotation axis extending along a third direction intersecting each of the first direction and the second direction, the light is scanned in a second scanning direction intersecting the first scanning direction. The light source device described in Supplementary Note 3.

[0164] According to this configuration, by scanning the light emitted from the light source unit, it is possible to illuminate the two-dimensional illuminated area.

[0165] (Supplementary Note 13) The output of the light source unit changes according to the displacement amount of the light transmitted through the rotating second transmissive optical element. The light source device described in Supplementary Note 12.

[0166] According to this configuration, by changing the output of the light source unit according to the displacement amount of the color transmitted through the rotating second transmissive optical element, the uniformity of the illuminance distribution of the light can be further improved.

[0167] (Supplementary Note 14) When the refractive index of the first transmissive optical element is smaller than the refractive index of the second transmissive optical element, the output of the light source unit does not change according to the displacement amount of the light transmitted through the rotating second transmissive optical element. The light source device described in Supplementary Note 12 or Supplementary Note 13.

[0168] According to this configuration, since the output of the light source unit is controlled only when passing through the first transmissive optical element with high non-linearity of the displacement amount of light, it is possible to enhance the illuminance distribution of light while simplifying the output control of the light source unit.

[0169] (Supplementary Note 15) The first transmissive optical element has a first surface and a second surface that intersect the first rotation axis, and 2×m (m: a natural number of 2 or more) first side surfaces that are in contact with the first surface and the second surface. The first incident surface and the first exit surface are two of the 2×m first side surfaces that are parallel to each other. The second transmissive optical element has a third surface and a fourth surface that intersect the second rotation axis, and 2×p (p: a natural number of 2 or more) second side surfaces that are in contact with the third surface and the fourth surface. The second incident surface and the second emission surface are two of the 2×p second side surfaces that are parallel to each other. The light source device according to Supplementary Note 12.

[0170] According to this configuration, in each transmissive optical element, since there is no light incident on side surfaces that are not parallel to each other, the generation of stray light in each transmissive optical element is reduced, and the light utilization efficiency can be improved.

[0171] (Supplementary Note 16) The output of the light source unit changes according to the amount of displacement of the light transmitted through the rotating second transmissive optical element. The light source device according to Supplementary Note 12 or Supplementary Note 15.

[0172] According to this configuration, by changing the output of the light source unit according to the amount of displacement of the color transmitted through the rotating second transmissive optical element, the uniformity of the illuminance distribution of the light can be further improved.

[0173] (Supplementary Note 17) When the number of the first side surfaces of the first transmissive optical element is less than the number of the second side surfaces of the second transmissive optical element, the output of the light source unit does not change according to the amount of displacement of the light transmitted through the rotating second transmissive optical element. The light source device according to Supplementary Note 15.

[0174] According to this configuration, since the output of the light source unit is controlled only when passing through the first transmissive optical element with a high non-linearity of the amount of displacement of light, the output control of the light source unit can be simplified while improving the illuminance distribution of light.

[0175] (Supplementary Note 18) The first transmissive optical element has a square cross-sectional shape by a plane orthogonal to the first rotation axis. The light source device according to any one of Supplementary Notes 1 to 17.

[0176] According to this configuration, when controlling the output of the light source unit in the case of transmitting through the first transmission optical element having a square cross-sectional shape with the highest non-linearity of the light displacement amount, the effect of enhancing the uniformity of the illuminance distribution in the illuminated area can be most remarkably obtained.

[0177] (Appendix 19) A light source device according to any one of Appendices 1 to 18, a light modulation device that modulates the light emitted from the light source device according to image information, and a projection optical device that projects the light modulated by the light modulation device. A projector.

[0178] According to the projector of this configuration, a decrease in brightness and contrast in the light modulation device, generation of color unevenness, light loss in the projection optical device, etc. can be suppressed, and a projector with excellent display quality can be realized with a simple configuration.

Explanation of Reference Numerals

[0179] 11, 111… First light source device, 12, 112… Second light source device, 13, 113… Third light source device, 15, 16, 17… Transmission optical element (first transmission optical element), 15a, 16a, 17a… First surface, 15b, 16b, 17b… Second surface, 15c, 16c, 17c… Side surface (first side surface), 20, 20A, 30, 30A… Projector, 23… Projection optical device, 25, 125… First light source unit, 26, 126… Second light source unit, 27, 127… Third light source unit, 55, 56, 57… Transmission optical element (second transmission optical element), 25a, 125a… First light emitting element, 26a, 126a… Second light emitting element, 27a, 127a… Third light emitting element, 35, 36, 37… Rotating element (first rotating element), 43B, 43G, 43R… Light modulation device, 64, 65, 66… Rotating element (second rotating element), 55a, 56a, 57a… Third surface, 55b, 56b, 57b… Fourth surface, AX1, AX2, AX3… Optical axis, C1, C2, C3… Rotation axis (first rotation axis), C4, C5, C6… Rotation axis (second rotation axis), d… Displacement amount, t… Time, t1… First time, t2… Second time, ω… Rotation angle.

Claims

1. A light source unit that emits light, Composed of a translucent member rotatably supported, having a first incident surface on which the light emitted from the light source unit is incident, and a first emission surface that emits the light incident from the first incident surface, and a first transmissive optical element, The first transmissive optical element rotates about a first rotation axis extending along a second direction that intersects a first direction which is an incident direction of the light with respect to the first transmissive optical element, The first incident surface and the first emission surface are parallel to each other, The output of the light source unit changes according to the displacement amount of the light transmitted through the rotating first transmissive optical element, A light source device.

2. The light transmitted through the rotating first transmissive optical element travels parallel to the optical axis to a position where it has moved by the displacement amount corresponding to the rotation angle of the first transmissive optical element in a direction intersecting the optical axis of the light source unit, The light source device according to Claim 1.

3. By rotating about the first rotation axis, the first transmissive optical element scans the light emitted from the light source unit in a first scanning direction, The light source device according to Claim 1 or Claim 2.

4. The first transmissive optical element is made of quartz, The light source device according to Claim 1 or Claim 2.

5. The light source unit includes a light-emitting element composed of a laser diode that emits laser light, The light source device according to Claim 1 or Claim 2.

6. The displacement amount of the light changes periodically, The output of the light source unit changes periodically in synchronization with the displacement amount of the light, The light source device according to Claim 1 or Claim 2.

7. Taking the displacement amount of the light in the first period as the first displacement amount and the displacement amount of the light in a second period different from the first period as the second displacement amount, when the second displacement amount is larger than the first displacement amount, the output of the light source unit in the second period is larger than the output of the light source unit in the first period, The light source device according to Claim 6.

8. The output of the light source unit changes by controlling the current value supplied to the light source unit, The light source device according to Claim 1 or Claim 2.

9. The output of the light source unit changes by controlling the duty ratio of the voltage supplied to the light source unit, The light source device according to Claim 1 or Claim 2.

10. Let the output of the light source unit at the n-th (n is an integer of 1 or more) time be P ｎ , Let Δd be the displacement amount of the light from the n-th moment to the (n + 1)-th moment after the elapse of a unit time ｎ , Let Δd be the displacement amount of the light from the (n + 1)-th moment until the (n + 2)-th moment after the elapse of a unit time ｎ＋１ When this is the case The output P of the light source unit at the (n + 1)-th moment ｎ＋１ satisfies the following formula The light source device according to Claim 1 or Claim 2. P ｎ＋１ = P ｎ × Δd ｎ＋１ / Δd ｎ

11. The light transmitted through the first transmissive optical element forms a rectangular illumination area, The light source unit makes the output of the light that illuminates the outer edge of the illumination area higher than the output of the light that illuminates the area inside the outer edge. The light source device according to claim 1 or claim 2.

12. Further comprising a second transmissive optical element composed of a rotatably supported translucent member, having a second incident surface on which the light is incident, and a second emission surface that emits the light incident from the second incident surface. The second incident surface and the second emission surface are parallel to each other. By rotating the second transmissive optical element about a second rotation axis extending along a third direction intersecting each of the first direction and the second direction, the light is scanned in a second scanning direction intersecting the first scanning direction. The light source device according to claim 3.

13. The output of the light source unit changes according to the displacement amount of the light transmitted through the rotating second transmissive optical element. The light source device according to claim 12.

14. When the refractive index of the first transmissive optical element is smaller than the refractive index of the second transmissive optical element, The output of the light source unit does not change according to the displacement amount of the light transmitted through the rotating second transmissive optical element. The light source device according to claim 12.

15. The first transmissive optical element has a first surface and a second surface intersecting the first rotation axis, and 2×m (m: a natural number of 2 or more) first side surfaces in contact with the first surface and the second surface. The first incident surface and the first emission surface are two of the 2×m first side surfaces that are parallel to each other. The second transmissive optical element has a third surface and a fourth surface intersecting the second rotation axis, and 2×p (p: a natural number of 2 or more) second side surfaces in contact with the third surface and the fourth surface. The second incident surface and the second emission surface are two of the 2×p second side surfaces that are parallel to each other. The light source device according to claim 12.

16. The output of the light source unit changes according to the displacement amount of the light transmitted through the rotating second transmissive optical element. The light source device according to claim 15.

17. When the number of the first side surfaces of the first transmissive optical element is smaller than the number of the second side surfaces of the second transmissive optical element, The output of the light source unit does not change according to the displacement amount of the light transmitted through the rotating second transmissive optical element. The light source device according to claim 15.

18. The first transmissive optical element has a square cross-sectional shape by a plane orthogonal to the first rotation axis. The light source device according to claim 1 or claim 2.

19. The light source device according to claim 1 or claim 2, an optical modulation device that modulates the light emitted from the light source device according to image information, and a projection optical device that projects the light modulated by the optical modulation device. A projector.

Images