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; a first transmissive optical element having 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; and a first rotation element that rotates the first transmissive optical element. The first incidence surface and the first emission surface of the first transmissive optical element are formed of transmissive materials parallel to each other. 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 light on the first transmissive optical element. The rotation speed of the first transmissive optical element rotated by the first rotation element changes according to the rotation angle of the 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] The projector disclosed in Patent Document 1 below includes a light source device and a rotating prism that scans the 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, 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 light source device further includes a first transmission optical element having the first incident surface and the first emission surface, and a first rotation element that rotates the first transmission optical element. The first transmission optical element is formed of a translucent member in which the first incident surface and the first emission surface are parallel to each other. The first transmission 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 transmission optical element. The rotation speed of the first transmission optical element by the first rotation element changes according to the rotation angle of the first transmission 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 8A

Figure 8B

Figure 9

Figure 10

Figure 11

Figure 12

Mode 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, in order to make each component easy to see, the scale of the dimensions may be made different 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, only the second light source device is shown for the optical system in the front stage of the light modulation device in order to make the drawing easy to see. 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 the present 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 synthesizing element 45, a projection optical device 23, and a control unit 100. Note that although the projector 20 of the present embodiment includes half-wave plates 46B and 46R, it is not necessarily required to include them.

[0011] The lighting device 2 of the present embodiment includes a first light source device 11, a second light source device 12, and a third light source device 13. Hereinafter, when these are collectively referred to without particularly distinguishing the first light source device 11, the second light source device 12, and the third light source device 13, they may be simply 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 the present 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 rotation element 35. The second light source device 12 includes a second light source unit 26, a transmission optical element 16, and a rotation element 36. The third light source device 13 includes a third light source unit 27, a transmission optical element 17, and a rotation element 37.

[0014] Hereinafter, in the drawings, the XYZ orthogonal coordinate system will be used for explanation 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 of the present embodiment corresponds to the "first direction" in the claims. The Y-axis direction of the present embodiment corresponds to the "second direction" in the claims. The Z-axis direction of 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 these are collectively referred to without particularly distinguishing the first light source unit 25, the second light source unit 26, and the third light source unit 27, 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 having coherence, and is laser light having 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 the 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 an Lz / LVz ratio of 1 / 2 or less, it can also 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 the 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 specific configuration will be described below 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 correspond to the "first rotation axis" in the claims. Further, each rotation element 35, 36, 37 that rotates the respective transmission optical elements 15, 16, 17 corresponds to the "first rotation element" 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 the rotation element 36. The transmission optical element 16 rotates about the rotation axis C2 by driving the rotation element 36. The rotation element 36 of the present embodiment is a stepping motor. By using a stepping motor, it becomes easy to control the rotation speed of the rotation element 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 of the four side surfaces 16c that are parallel to each other.

[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 it, 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 improved.

[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 rotation element 35. The transmissive optical element 15 rotates about the rotation axis C1 by driving the rotation element 35. The rotation element 35 of the present embodiment is a stepping motor. By using a stepping motor, it becomes easy to control the rotation speed of the rotation element 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 where 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 any two of the four side surfaces 15c that are parallel to each other.

[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 or eight. 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 it, 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 increased.

[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 that is rotatably supported. The transmissive optical element 17 is rotatable about a rotation axis C3 that extends along the Y-axis direction. The rotation axis C3 is connected to the rotation element 37. The transmissive optical element 17 rotates about the rotation axis C3 by the drive of the rotation element 37. The rotation element 37 in this embodiment is a stepping motor. By using a stepping motor, the control of the rotation speed of the rotation element 37 becomes easy.

[0036] The transmissive optical element 17 has a first surface 17a and a second surface 17b that intersect the rotation axis C3, and four side surfaces 17c that are perpendicular to the first surface 17a and the second surface 17b. The transmissive optical element 17 transmits the red light LR emitted from the third light source unit 27 while rotating about the rotation axis C3. 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 either 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 or eight. 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 it, 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 increased.

[0038] Hereinafter, the behavior when each color light LB, LG, LR passes through each transmissive optical element 15, 16, 17 will be described. Since the behaviors of the color lights LB, LG, 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] Figs. 5A to 5F are schematic diagrams for explaining the behavior of the green light LG when the transmissive optical element 16 of the second light source device 12 rotates. In this example, when viewed from the +Y side, the transmissive optical element 16 rotates clockwise about the rotation axis C2, showing a state where time has passed from Fig. 5A to Fig. 5F.

[0040] In FIGS. 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 transmissive optical element 16 and the optical axis AX2 is defined as the rotation angle ω of the transmissive optical element 16. Actually, the green light LG has a predetermined light beam width in the Z-axis direction, but here we focus on the behavior of the light ray LG0 traveling on the optical axis AX2.

[0041] FIG. 5A shows the initial state of the transmissive optical element 16. That is, the transmissive optical element 16 is not rotated, 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 transmissive 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 transmissive 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 the rotation angle ω, the light ray LG0 is incident on the side surface 16c1 at an incident angle equal to the rotation angle ω. Therefore, the light ray LG0 refracts in the direction shown in the figure (+Z side) and travels through the inside of the transmissive optical element 16. Next, since the light ray LG0 is also incident on the side surface 16c3 at a predetermined incident angle, it refracts at the side surface 16c3 and is 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 ray LG0 with respect to the side surface 16c1 is equal to the incident angle of the light ray LG0 with respect to the side surface 16c3, and the refraction angle of the light ray LG0 incident on the side surface 16c1 and the refraction angle of the light ray 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 ray 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 ray LG0 travels parallel to the optical axis AX2 at a position displaced by the 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 increases, and the refraction angle increases. 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 where the light beam LG0 travels parallel to the optical axis AX2 is always maintained. Between the rotation angle ω of 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 until FIG. 5C, and it 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 incidence of the light beam LG0 on the side surface 16c3 and the refraction angle at the emission from the side surface 16c4 cancel each other out does not change from the period until FIG. 5C. As a result, the light beam LG0 travels parallel to the optical axis AX2 at a position displaced by the 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 decreases, and the refraction angle decreases. Therefore, the displacement amount d of the light beam LG0 from the optical axis AX2 becomes smaller than that in FIG. 5D. Thus, between the rotation angle ω of 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 becomes 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 exit 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. 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 d increases on either the +Z side or the -Z side. 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 the displacement reverses. 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 repeats. Therefore, when the transmissive optical element 16 makes one full rotation, 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] Above, the behavior of light has been described by focusing only on the light ray 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 region Q in the light modulation device 43G which is the illuminated surface. Regarding 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, after being reflected by the respective reflection mirrors 41 and 42 described later, similar to the green light LG, they are scanned within the two-dimensional illuminated region Q in the light modulation devices 43B and 43R which are the illuminated surfaces. In this way, each of the transmission optical elements 15, 16, and 17 is rotated about the respective rotation axes C1, C2, and C3 by the respective rotation elements 35, 36, and 37, thereby scanning each of the blue light LB, the green light LG, and the red light LR in the Z-axis direction orthogonal to the Y-axis direction and scanning within the two-dimensional illuminated region 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 is incident on the light modulation device 43B, the scanning direction on the light modulation region (illuminated region Q) of the light modulation device 43B becomes the X-axis direction. Also, since the red light LR is reflected in the +Z direction by the reflection mirror 42 as described later and is incident on the light modulation device 43R, the scanning direction on the light modulation region (illuminated region 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 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 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 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 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 synthesizing the illuminance distributions of the five lights gradually becomes averaged and smooth. Further, 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 match 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 lights corresponding to red light LR, green light LG, and blue light LB when the image lights of respective colors emitted from the light modulation devices 43G, 43B, and 43R are 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 the 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 enhanced.

[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 is not considered. However, when the light transmitted through the rotating transmissive optical element as described above is temporally scanned on the optical modulation device, unevenness usually occurs in the illuminance distribution formed on the optical modulation device. The inventor of the present invention conducted a simulation 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 that is a model for the simulation. 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).

[0060] Assuming that the incident angle of the light ray L1a on the transmissive optical element 18 is θ1(t), θ1(t) is a sawtooth wave with an amplitude θmax and a period T. Therefore, when θ1(t) is applied to the general formula of the sawtooth wave, the following equation (1) holds.

[0061]

Equation

[0062] Here, floor(x) is the floor function for the real number x and is defined as the largest integer less than or equal to x. In FIG. 6, the optical axis AX of the light-emitting element (not shown) that emits the 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 the incident angle θ1 at point P1, is refracted at the 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.

[0063] The light ray L1a that has passed through the rotating transmissive optical element 18 travels parallel to the optical axis AX at a position that has been displaced by an amount d corresponding to the rotation angle of the transmissive optical element 18 in a direction orthogonal (intersecting) to the optical axis AX. In FIG. 6, if the distance between the opposing surfaces of the transmissive optical element 18 is l, the refractive index of the external space of the transmissive optical element 18 is n1, and the refractive index of the transmissive optical element 18 is n2, then the following equation (2) holds between the displacement amount d of the light ray L1a, the incident angle θ1, and the refraction angle θ2, based on Snell's law.

[0064] [Number]

[0065] Since the incident angle θ1 of the light ray L1a on the transmissive optical element 18 is represented by the above equation (1), the displacement amount d of the light ray L1a on the optical modulation device can be represented by the following equation (3).

[0066] [Number]

[0067] Also, the maximum incident angle θmax of the light ray L1a in the transmissive optical element 18 is represented by the following equation (4).

[0068] [Number]

[0069] Here, for example, regarding equation (3), if the distance l between the opposing surfaces of the transmissive optical element 18 is 20 mm, the refractive index of the external space n1 = 1.0 (air), the rotation angle (degrees) is taken on the horizontal axis, the displacement amount (mm) is taken on the vertical axis, and 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 becomes a periodic function. Also, when the refractive index n2 of the transmissive optical element 18 is increased infinitely large 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.

[0070] As described above, since the rotation angle of the transmissive optical element 18 is equal to the incident angle θ1, it suffices to consider the rotation angle of the transmissive optical element 18 within the range of the maximum incident angle θmax of the light ray L1a. Further, the maximum incident angle θmax of the transmissive optical element 18 is determined according to the cross-sectional shape corresponding to the value of n as shown by equation (4). That is, as shown in FIG. 6, when the cross-sectional shape of the transmissive optical element 18 is square, 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 can be considered 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.

[0071] FIG. 7 is a diagram showing a periodic function cut out in the angular range of ±45 degrees. In FIG. 7, the horizontal axis represents the rotation angle (degrees), and the vertical axis represents the displacement amount (mm). The graph of reference sign A shows the case where the refractive index n2 is 1.3. The graph of reference sign B shows the case where the refractive index n2 is 1.5. The graph of reference sign C shows the case where the refractive index n2 is 1.6. The graph of reference sign D shows the case where the refractive index n2 is 1.8. The graph of reference sign E shows the case where the refractive index n2 is 1.8. The graph of reference sign F shows the case where the refractive index n2 is 2.0. The graph of reference sign G shows the case where the refractive index n2 is 3.0.

[0072] 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. It was also 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, it was found that when the cross-sectional shape of the transmissive optical element 18 is square, the linearity of the graph showing the displacement amount becomes lower, that is, the non-linearity becomes higher.

[0073] The inventors of the present invention 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 region can be improved. Since it is currently difficult to form a transmissive optical element with a material having a refractive index of 3.0 or more, the inventors considered it difficult to enhance the linearity of the displacement amount by devising the material of the transmissive optical element. As a result of intensive research, the inventors have found that the in-plane illuminance distribution of the illuminated area can be made uniform by adjusting the rotation speed of the transmissive optical element according to the rotation angle of the transmissive optical element that changes the displacement amount of light. Then, the projector 20 of the present embodiment was completed.

[0074] Hereinafter, a method for equalizing the in-plane illuminance distribution in the illuminated area in the projector 20 of the present embodiment will be described. Hereinafter, a case where the illuminance distribution of the green light LG emitted from the second light source unit 26 of the second light source device 12 is made uniform will be described as an example. That is, a method in which the control unit 100 controls the rotation speed of the transmissive optical element 16 by the rotation element 36 according to the rotation angle of the transmissive optical element 16 will be described. Note that the same concept applies to a method for 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.

[0075] When the rotation frequency of the transmissive optical element 16 in the second light source device 12 is f (Hz), the angular velocity W (rad / s) of the transmissive optical element 16 is expressed as ω = 2πf = 2π / T. Further, the rotation angle θ (rad) at a certain time t is expressed as θ = 2πft = 2πf / T. Therefore, when a graph is drawn with the time t on the horizontal axis in the range of -1 / (8f) ≤ t ≤ 1 / (8f), it coincides with the graph of -45 degrees ≤ θ1 ≤ 45 degrees shown in FIG. 7.

[0076] Here, the slope of the tangent line of the graph at a certain time t corresponds to the displacement speed of the light beam, that is, the moving speed of the light scanning on the illuminated area. Generally speaking, in the case of a transmissive optical element of a regular n-sided polygon (n is an even number of 4 or more), the range of -1 / (2nf) ≤ t ≤ 1 / (2nf) on the time axis coincides with the graph of -180 / n ≤ θ1 ≤ 180 / n on the angle axis.

[0077] Therefore, if the transmissive optical element can be rotated at a rotational speed defined by a rotational angular velocity W(θ1) such that Equation (3) becomes a linear displacement according to the rotational angle θ1 within the angular range represented by Equation (4) above, it is possible to equalize the in-plane distribution of the illumination light. In the projector 20 of the present embodiment, by controlling the rotational speed of the rotating element 36 composed of a stepping motor as described later, it is possible to enhance the uniformity of the illuminance distribution by the green light LG transmitted through the transmissive optical element 16.

[0078] Hereinafter, a method for controlling the rotating element 36 will be described. FIG. 8A is a graph showing the relationship between the rotation angle θ of the transmissive optical element 16 and the displacement amount d of the green light LG. FIG. 8B is a graph obtained by replacing the graph of FIG. 8A with another coordinate system.

[0079] First, as shown in FIG. 8A, when the rotation angle θ of the transmissive optical element 16 rotated by the rotating element 36 coincides with the maximum incident angle θmax represented by Equation (4), the displacement amount of the green light LG is dmax, the incident angle of the green light LG with respect to the transmissive optical element 16 is θ, and the displacement amount of the green light LG at that time is d. Consider a straight line L passing through (θ, d) = (0, 0) and (θmax, dmax). Note that the displacement amount of the green light LG in the range where the incident angle is from 0 to -θmax changes in the same manner as in the range where the incident angle is from 0 to θmax, except that the displacement direction is reversed. For this reason, in the graph of FIG. 8A, the horizontal axis is shown in the range of 0 ≦ θ ≦ θmax, and the vertical axis is shown in the range of 0 ≦ d ≦ dmax.

[0080] Subsequently, when the rotation angle θ(t) is taken on the horizontal axis and the displacement amount d is taken on the vertical axis, the displacement amount d at a certain time t is expressed as d = f(θ) from the above Equation (3). Here, a function d = g(θ) that is symmetric to d = f(θ) with respect to the straight line L is newly considered.

[0081] Then, replace the horizontal axis θ (0 ≤ θ ≤ θmax) and the vertical axis d (0 ≤ d ≤ dmax) in FIG. 8A with the horizontal axis X (0 ≤ X ≤ 1) and the vertical axis Y (0 ≤ Y ≤ 1) in FIG. 8B, respectively, and replace the above d = f(θ) with Y = F(X) and d = g(θ) with Y = G(X). Here, f(θ) and F(X), g(θ) and G(X) are function names in the θ-d coordinate system and the X-Y coordinate system, respectively, and substantially represent the same function. For this reason, the straight line L exists on Y = X, and Y = F(X) and Y = G(X) are symmetric with respect to the straight line L, that is, the straight line Y = X, so they are in an inverse function relationship with each other.

[0082] Here, as a comparative example of the projector 20 of the present embodiment, the case where the rotation speed of the transmissive optical element 16, that is, the rotation speed of the rotating element 36, is constant is considered. When the rotation speed of the transmissive optical element 16 is thus made constant, the displacement amount of the green light LG moving on the illuminated area is defined by the function d = f(θ) in FIG. 8A or the function Y = F(X) in FIG. 8B. That is, the graph defining the displacement amount of the green light LG has non-linearity. Here, the greater the slope of the graph defining the displacement amount of the green light LG, the faster the speed of the green light LG passing through the illuminated area, so the integrated light amount of the green light LG per unit area of the illuminated area decreases. On the other hand, the smaller the slope of the graph defining the displacement amount of the green light LG, the slower the speed of the green light LG passing through the illuminated area, so the integrated light amount of the green light LG per unit area of the illuminated area increases. 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 graph slope 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 graph slope is large. Therefore, when the output of the green light LG incident on the transmissive optical element 16 is constant, the uniformity of the illuminance distribution by the green light LG scanning in one direction on the illuminated area varies.

[0083] On the other hand, in the projector 20 of the present embodiment, the rotation speed of the rotation element 36 that rotates the transmissive optical element 16 is controlled so that the displacement amount of the green light LG that changes corresponding to the rotation angle of the transmissive optical element 16 satisfies the relationship of the straight line L shown in FIG. 8A. That is, the rotation element 36 dynamically changes the rotation speed of the rotation element 36 with time t.

[0084] The control unit 100 controls the rotational angular velocity of the rotation element 36 so that the moving speed of the green light LG scanning on the optical modulation device 43G at a certain time t is the slope of the function G(X), that is, the value obtained by differentiating G(X) with respect to X. Specifically, the control unit 100 re-converts the slope of G(X) (the value obtained by differentiating G(X) with respect to X) obtained in the above X-Y coordinate system into the slope of g(θ) in the d-θ coordinate system (the value obtained by differentiating g(θ) with respect to θ), and calculates the rotational angular velocity at which the scanning speed of the green light LG on the optical modulation device 43B becomes the differential value of g(θ) from the relational expressions of equations (3) and θ = ωt = 2πft = 2πt / T. By rotating the transmissive optical element 16 at the rotation speed obtained from the rotational angular velocity calculated in this way, the rotation angle of the transmissive optical element 16 and the displacement amount of the green light LG satisfy the relationship of the straight line L shown in FIG. 8A. That is, it becomes possible to rotate the transmissive optical element 16 so that the relationship between the rotation angle of the transmissive optical element 16 and the displacement amount of the green light LG has linearity.

[0085] Here, for example, let the time when the rotation angle of the transmissive optical element 16 is 0 degrees be the first time t1, and the time after one unit time has elapsed from the first time t1 be the second time t2. Let the incident angle of the green light LG with respect to the transmissive optical element 16 at the first time t1 be the first incident angle, the incident angle of the green light LG with respect to the transmissive optical element 16 at the second time t2 be the second incident angle, and assume that the second incident angle is larger than the first incident angle.

[0086] Normally, as the incident angle increases, the moving speed (scanning speed) of light on the illuminated area increases. In contrast, the control unit 100 controls the rotation element 36 so that the rotation speed of the transmissive optical element 16 at the second time t2 is smaller than the rotation speed of the transmissive optical element 16 at the first time t1.

[0087] In this embodiment, 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 rotation speed of the rotary element 36 so as to satisfy the above relationship. Thereby, the control unit 100 can suppress the increase in the moving speed of the green light LG on the illuminated area as the incident angle increases.

[0088] As described above, according to the projector 20 of this embodiment, by changing the rotation speed of the rotary element 36 with time by the control unit 100, the moving speed of the green light LG that scans the illuminated area can be made constant regardless of the rotation angle of the transmissive optical element 16. Therefore, the integrated light amount per unit time of the green light LG that scans the illuminated area can be made uniform. Therefore, when the output of the green light LG incident on the transmissive optical element 16 is constant, the illuminance distribution by the green light LG that scans the illuminated area in one direction can be made uniform.

[0089] As described above, according to the projector 20 of this embodiment, by changing the rotation speed of the rotary element 36 according to the rotation angle of the transmissive optical element 16, 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.

[0090] Further, in the projector 20 of this embodiment, the control unit 100 changes the rotation speed of the rotary element 35 of the first light source device 11 according to the rotation angle of the transmissive optical element 15, thereby improving the uniformity of the illuminance distribution of the blue light LB that scans the light modulation area of the light modulation device 43B, which is the illuminated area, in one direction. Also, in the projector 20 of this embodiment, the control unit 100 changes the rotation speed of the rotary element 37 of the third light source device 13 according to the rotation angle of the transmissive optical element 17, thereby improving the uniformity of the illuminance distribution of the red light LR that scans the light modulation area of the light modulation device 43R, which is the illuminated area, in one direction.

[0091] 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.

[0092] The first light source device 11 includes a first light source unit 25 that emits blue light LB, a rotating element 35, and a transmissive optical element 15 that is configured by a transmissive member rotatably supported by the rotating element 35 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 rotation speed of the transmissive optical element 15 by the rotating element 35 changes according to the rotation angle of the transmissive optical element 15. Further, the second light source device 12 includes a second light source unit 26 that emits green light LG, a rotating element 36, and a transmissive optical element 17 that is rotatably supported by the rotating element 36 and on which the green light LG emitted from the second light source unit 26 is incident and rotates about a rotation axis C2 extending along the Z direction. The rotation speed of the transmissive optical element 16 by the rotating element 36 changes according to the rotation angle of the transmissive optical element 16. Further, the third light source device 13 includes a third light source unit 27 that emits red light LR, a rotating element 37, and a transmissive optical element 18 that is rotatably supported by the rotating element 37 and on which the red light LR emitted from the third light source unit 27 is incident and rotates about a rotation axis C3 extending along the Z direction. The rotation speed of the transmissive optical element 17 by the rotating element 37 changes according to the rotation angle of the transmissive optical element 17.

[0093] 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, the green light LG, and the red light LR is displaced in a direction orthogonal to the traveling direction of each of the colored lights LB, LG, and LR while maintaining a state parallel to the respective optical axes AX1, AX2, and AX3 corresponding to the colored lights LB, LG, and LR as the transmission optical elements 15, 16, and 17 rotate. Further, since each of the colored lights LB, LG, and LR has an elongated shape having a major axis along the extending direction of each of the rotation axes C1, C2, and C3, each of the colored lights LB, LG, and LR can be scanned within a two-dimensional illumination region Q on an arbitrary illumination surface, specifically, within the light modulation regions of the light modulation devices 43B, 43G, and 43R.

[0094] According to the configuration of the present embodiment, by changing the rotation speed of the transmission optical elements 15, 16, and 17 by the rotation elements 35, 36, and 37 according to the rotation angle of the transmission optical elements 15, 16, and 17, it is possible to enhance the uniformity of the illuminance distribution within the light modulation regions of the light modulation devices 43B, 43G, and 43R by the respective colored lights LB, LG, and LR.

[0095] In each of the light source devices 11, 12, and 13 of the above embodiment, an example of the cross-sectional shape of each of the transmission optical elements 15, 16, and 17 is a square, but a transmission optical element having a cross-sectional shape in which the number of sides is an even number of 6 or more may be used. In this case, the linearity of the displacement amount of each of the colored lights LB, LG, and LR is most reduced when the cross-sectional shape of the transmission optical element is a square. Therefore, if a transmission optical element having a cross-sectional shape in which the number of sides is an even number of 6 or more is used, the non-linearity of the displacement amount of each of the colored lights LB, LG, and LR is reduced, and thus the adjustment of the rotation speed of the transmission optical elements 15, 16, and 17 by the rotation elements 35, 36, and 37 becomes easy. Therefore, the uniformity of the illuminance distribution within the light modulation regions of the light modulation devices 43B, 43G, and 43R can be enhanced more simply.

[0096] Therefore, according to the projector 20 of the present embodiment, it is possible to suppress a decrease in brightness and contrast in the light modulation devices 43B, 43G, and 43R, the occurrence of color unevenness, light loss in the projection optical device 23, etc., and realize a projector with excellent display quality with a simple configuration.

[0097] (Second Embodiment) Hereinafter, the second embodiment of the present invention will be described with reference to FIGS. 9 and 10. The basic configuration of the projector in this 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 the projector 30 in this 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.

[0098] As shown in FIG. 9, the projector 30 in this embodiment includes an illumination 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 illumination device 3 are the same as those of the first embodiment.

[0099] The illumination device 3 in 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 rotation element 35, a transmission optical element 55 on the subsequent stage side, and a rotation element 64. The second light source device 12 includes a second light source unit 126, a transmission optical element 16, a rotation element 36, a transmission optical element 56 on the subsequent stage side, and a rotation element 65. The third light source device 13 includes a third light source unit 127, a transmission optical element 17, a rotation element 37, a transmission optical element 57 on the subsequent stage side, and a rotation element 66.

[0100] The arrangements of the light source units 125, 126, and 127 are the same as those of the 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 each of the light source units 25, 26, and 27 in the first embodiment includes a plurality of light-emitting elements 25a, 26b, and 27c arranged in the Y-axis direction, each of the light source units 125, 126, and 127 in this embodiment includes 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 each of the light source units 125, 126, and 127 does not necessarily have to be a shape having a major axis extending along the Y-axis direction.

[0101] 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 direction and the Z-axis direction. 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 direction and the Z-axis direction, 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.

[0102] 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 postures 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 are simply referred to as 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. Also, each of the rotation elements 64, 65, and 66 that rotate each of the transmissive optical elements 55, 56, and 57 described later respectively corresponds to the "second rotation element" in the claims.

[0103] The transmissive optical element 56 is provided on the light emission side (rear stage side) of the transmissive optical element 16 on the optical axis AX2. The transmissive optical element 56 is composed of a rotatably supported light-transmissive member. As the glass material of the light-transmissive member constituting the transmissive optical element 56, for example, optical glass such as BK7, quartz, light-transmissive materials such as resin are 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 rotation element 65 composed of a motor or the like. The transmissive optical element 56 rotates about the rotation axis C5 by driving of the rotation element 65.

[0104] 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.

[0105] 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 on which the green light LG emitted from the transmissive optical element 16 is incident on the transmissive optical element 56 is not fixed to one, but changes over time. In the transmissive optical element 56, the side surface 56c on which the green light LG emitted from the transmissive optical element 16 is incident 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 of two parallel side surfaces 56c among the four side surfaces 56c.

[0106] 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×m (m: a natural number of 2 or more). That is, the number of side surfaces 56c is preferably an even number such as six, eight, etc. 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 said 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.

[0107] 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 the rotation element 64. The transmissive optical element 55 rotates about the rotation axis C4 by driving of the rotation element 64.

[0108] 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 perpendicularly in contact with 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 either one of two parallel side surfaces 55c among the four side surfaces 55c.

[0109] In the case of this embodiment, the transmissive optical element 55 has four side surfaces 55c, but the number of the side surfaces 55c does not necessarily have to be four. The number of the side surfaces 55c is desirably an even number, such as six, eight, etc. 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 the side surface 55c, and there is no non-parallel side surface 55c. Thereby, generation of stray light in the transmissive optical element 55 is reduced, and the light utilization efficiency can be enhanced.

[0110] The transmissive optical element 57 is provided on the light emission side (rear stage side) of the transmissive optical element 17 on the optical axis AX3. The transmissive optical element 57 is composed of a light transmissive member that is rotatably supported. The transmissive optical element 57 is rotatable about a rotation axis C6 extending along the Z-axis direction. The rotation axis C6 is connected to a rotation element 66. The transmissive optical element 57 rotates about the rotation axis C6 by driving of the rotation element 66.

[0111] The transmissive 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 perpendicularly in contact with the third surface 57a and the fourth surface 57b. While rotating about the rotation axis C6, the transmissive optical element 57 transmits the red light LR emitted from the transmissive optical element 17. In the transmissive optical element 57, the side surface 57c on which the red light LR emitted from the transmissive 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 any one of two parallel side surfaces 57c among the four side surfaces 57c.

[0112] In the case of this embodiment, the transmissive 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, eight, etc. If the number of side surfaces 57c is an even number, each of all the side surfaces 57c will be parallel to the side surface 57c facing it, and there will be no non-parallel side surfaces 57c. As a result, less stray light is generated in the transmissive optical element 57, and the light utilization efficiency can be increased.

[0113] 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 as compared with the case where the three rotation axes C4, C5, and C6 are not arranged on a straight line extending in the Z-axis direction.

[0114] 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 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 (optical 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 within the illuminated region Q changes according to the rotation angles of the transmissive optical elements 16 and 56. On the other hand, in the projector 30 of this embodiment, the control unit 100 appropriately adjusts the rotation speeds of the transmissive optical elements 16 and 56 by the rotation elements 36 and 65 according to the rotation angles of the transmissive optical elements 16 and 56, thereby enhancing the uniformity of the illuminance distribution of the green light LG illuminating the illuminated region Q (optical modulation device 43G).

[0115] 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 within the illuminated region Q changes according to the rotation angles of the transmissive optical elements 15 and 55. In contrast, in the projector 30 of the present embodiment, the control unit 100 appropriately adjusts the rotation speeds of the transmissive optical elements 15 and 55 by the rotation elements 35 and 64 according to the rotation angles of the transmissive optical elements 15 and 55, thereby enhancing the uniformity of the illuminance distribution of the blue light LB that illuminates the illuminated region Q (light modulation device 43B).

[0116] Similarly, the red light LR emitted from the third light source unit 127 is scanned within the two-dimensional illuminated region Q (light 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 within the illuminated region Q changes according to the rotation angles of the transmissive optical elements 17 and 57. In contrast, in the projector 30 of the present embodiment, the control unit 100 appropriately adjusts the rotation speeds of the transmissive optical elements 17 and 57 by the rotation elements 37 and 66 according to the rotation angles of the transmissive optical elements 17 and 57, thereby enhancing the uniformity of the illuminance distribution of the red light LR that illuminates the illuminated region Q (light modulation device 43R).

[0117] 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 light modulation device 43B, it is scanned in the X-axis direction on the light modulation region (illuminated region Q) of the light modulation device 43B. Also, since the red light LR is reflected in the +Z direction by the reflection mirror 42 and enters the light modulation device 43R, it is scanned in the X-axis direction on the light modulation region (illuminated region Q) of the light modulation device 43R. Other configurations of the projector 30 are the same as those in the first embodiment.

[0118] Also in the present embodiment, the same effects as those of the first embodiment can be obtained, such as problems such as a decrease in brightness and contrast in the optical modulation devices 43B, 43G, and 43R, color unevenness, light loss in the projection optical device 23, and illuminance unevenness due to the use of a light source having coherence can be improved.

[0119] In the present embodiment, the transmission optical elements 55, 56, and 57 may be connected to each other along the Z-axis direction. According to this configuration, the three rotation elements 64, 65, and 66 can be shared, and the control of the rotation of each of the transmission optical elements 55, 56, and 57 becomes easy.

[0120] (First Modification Example) Hereinafter, a first modification example of the present invention will be described. This modification example relates to a modification example 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.

[0121] FIG. 11 is a plan view showing a schematic configuration of a projector 20A according to 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 according to this modification example includes an illumination device 2, a first reflection mirror 41, a second reflection mirror 42, an optical modulation device 43G, an emission-side polarizing plate 44G, an optical modulation device 43B, an emission-side polarizing plate 44B, a half-wave plate 46B, an optical 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, a control unit 100, and a moving mechanism 123.

[0122] The moving mechanism 123 holds the projection optical device 23 so as to be movable at least in the YZ plane. The projector 20A according to this modification example can adjust the position of the image projected from the projection optical device 23 onto the screen (projection surface) by moving the projection optical device 23 by the moving mechanism 123.

[0123] Here, when the projection optical device 23 is moved by the moving mechanism 123, the amount of the image light synthesized by the image synthesizing element 45 that is drawn into the projection optical device 23 changes. Specifically, in the projection optical device 23, the amount of light drawn in at the peripheral portion is less than that at the central portion of the image light emitted from the light modulation regions of the respective light modulation devices 43B, 43G, and 43R. For this reason, when the image projection position is moved by the moving mechanism 123, uneven illuminance is more likely to occur in the image projected on the screen.

[0124] 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, and 27 increases the output of the light that illuminates the outer edge of the rectangular illumination region (the outer edge of the light modulation regions of the light modulation devices 43B, 43G, and 43R) illuminated by the respective color lights LB, LG, and LR, as compared with the output of the light that illuminates the central portion of the illuminated region located inside the outer edge.

[0125] Specifically, in the projector 20A of this modification example, as in the first embodiment, the control unit 100 changes the rotation speeds of the transmission optical elements 15, 16, and 17 by the respective rotation elements 35, 36, and 37 according to the rotation angles of the transmission optical elements 15, 16, and 17, thereby enhancing the uniformity of the illuminance distribution over the entire light modulation regions of the respective light modulation devices 43B, 43G, and 43R. Further, when the projection optical device 23 is moved by the moving mechanism 123, the control unit 100 controls the outputs of the respective light source units 25, 26, and 27 so that the emission intensities of the respective color lights LB, LG, and LR are stronger in the section where the outer edge of the light modulation region is scanned. Here, the section where the outer edge of the light modulation region 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, and 17 is around (including) the maximum incident angle within the section where each of the transmission optical elements 15, 16, and 17 makes one rotation.

[0126] According to the projector 20A of this modification example, by increasing the amount of light at the outer edge of the light modulation regions of the light modulation devices 43B, 43G, and 43R where the amount of light drawn in by the projection optical device 23 decreases, it is possible to suppress the occurrence of uneven illuminance in the image projected on the screen even when the image projection position is moved by the moving mechanism 123.

[0127] (Second Modified Example) Hereinafter, a second modified example of the present invention will be described. This modified example relates to a modified example of the projector of the second embodiment. The basic configuration of the projector of this modified example 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.

[0128] 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.

[0129] 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 to have a higher light output for illuminating the outer edge of the rectangular illuminated 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) than the light output for illuminating the central portion of the illuminated area located inside the outer edge.

[0130] Specifically, in the projector 30A of this modified example, similar to the second embodiment, the control unit 100 changes the rotation speeds of the transmissive optical elements 15, 16, 17, 55, 56, 57 by the respective rotation elements 35, 36, 37, 64, 65, 66 according to the rotation angles of the transmissive optical elements 15, 16, 17, 55, 56, 57, thereby enhancing the uniformity of the illuminance distribution throughout the light modulation regions of the respective light modulation devices 43B, 43G, 43R. Further, when the projection optical device 23 is moved by the movement mechanism 123, the control unit 100 controls the outputs of the respective light source units 125, 126, 127 so as to make the emission intensities of the respective color lights LB, LG, LR stronger in the section where the outer edge of the light modulation region is scanned. Here, the section where the outer edge of the light modulation region is scanned corresponds to the section in which the incident angle of the light with respect to each of the transmissive optical elements 15, 16, 17, 55, 56, 57 is around the maximum incident angle (including the maximum incident angle) within the section where each of the transmissive optical elements 15, 16, 17, 55, 56, 57 makes one rotation.

[0131] According to the projector 30A of this modified example, by strengthening the light amount at the outer edge of the light modulation regions 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 movement mechanism 123.

[0132] (Third Modified Example) Hereinafter, a third modified example of the present invention will be described. This modified example relates to a modified example of the projector of the second embodiment. The basic configuration of the projector of this modified 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.

[0133] In the configurations of the second embodiment and the second modified example, the rotation speeds of the transmissive optical elements 15, 16, 17, 55, 56, 57 by the respective rotation elements 35, 36, 37, 64, 65, 66 were changed according to the rotation angles of the 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.

[0134] Here, for example, the refractive indices and shapes of the transmissive optical elements 15 and 55 through which blue light LB sequentially passes are different from each other, and it is assumed that 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 is greater than the non-linearity of the displacement amount by the transmissive optical element 55. In such a case, the control unit 100 may control so as to change the rotation speed of the transmissive optical element 15 by the rotation element 35 according to the rotation angle of the transmissive optical element 15, and not change the rotation speed of the transmissive optical element 55 by the rotation element 64 according to the rotation angle of the transmissive optical element 55. According to this configuration, since it is only necessary to perform control in which only the rotation speed of the transmissive optical element 15 is variable, the configuration of the control unit 100 can be further simplified. In addition, 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 rotation speed of the transmissive optical element 55 by the rotation element 64 according to the rotation angle of the transmissive optical element 55, and keep the rotation speed of the transmissive optical element 15 constant without changing it.

[0135] The same also applies to the case where the refractive index of the transmissive optical element 16 is smaller than the refractive index of the transmissive optical element 56 in the transmissive optical elements 16 and 56 through which green light LG sequentially passes. The same also applies to the case where the refractive index of the transmissive optical element 17 is smaller than the refractive index of the transmissive optical element 57 in the transmissive optical elements 17 and 57 through which red light LR sequentially passes. According to this configuration, since it is only necessary to perform control in which only the rotation speeds of the rotation elements 36 and 37 that rotate one of the transmissive optical elements 16 and 17 are variable, the configuration of the control unit 100 can be further simplified.

[0136] For example, assume that the cross-sectional shape of the transmissive optical element 15 is square and the cross-sectional shape of the transmissive optical element 55 is regular hexagon. As shown in the above formula (2), as the number of side surfaces of the transmissive optical element increases, the maximum incident angle of light in the transmissive optical element decreases, and the non-linearity of the light displacement amount decreases. That is, the non-linearity is the largest when the cross-sectional shape of the transmissive optical element is square (the number of side surfaces is four). Therefore, the non-linearity of the displacement amount caused by the transmissive optical element 15 is larger than the non-linearity of the displacement amount caused by the transmissive optical element 55.

[0137] In such a case, it may be controlled such that the rotation speed of the transmissive optical element 15 by the rotation element 35 is changed according to the rotation angle of the transmissive optical element 15, and the rotation speed of the transmissive optical element 55 by the rotation element 64 is not changed according to the rotation angle of the transmissive optical element 55. According to this configuration, since it is only necessary to control the rotation speed of only the rotation element 35 side that rotates the transmissive optical element 15 to be variable and the rotation speed of the rotation element 64 side to be constant, the configuration of the control unit 100 can be further simplified. In addition, when the number of side surfaces of the transmissive optical element 55 is smaller than the number of side surfaces of the transmissive optical element 15, the control unit 100 may perform control to change only the rotation speed of the rotation element 64 that rotates the transmissive optical element 55.

[0138] The same also applies to the case where 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 in the transmissive optical elements 16 and 56 through which the green light LG passes in order. The same also applies to the case where 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 in the transmissive optical elements 17 and 57 through which the red light LR passes in order. According to this configuration, since it is only necessary to perform control to make only the rotation speeds of the rotation elements 36 and 37 that rotate one of the transmissive optical elements 16 and 17 variable, the configuration of the control unit 100 can be further simplified.

[0139] Note that the technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, it is also possible to use it for the purpose of arranging the 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 region of each of the light modulation devices 43B, 43G, 43R by changing the rotation speed of the transmission optical element by the rotation element according to the rotation angle of the transmission optical element. For example, each projector may be controlled by the control unit 100 so that the rotation speed of the rotation element is constant in a section where the outer edge of the light modulation region of each of the light modulation devices 43B, 43G, 43R corresponding to the end of the image overlapping with the image of another projector is scanned. As described above, in the section where the outer edge of the light modulation region is scanned, the incident angle of light with respect to the transmission optical element approaches the maximum incident angle. Therefore, if the rotation speed of the rotation element is constant, the brightness of the illuminated region becomes low. For this reason, it is not necessary to adjust the moving speed of each of the color lights LB, LG, LR that scan the outer edge of the light modulation region of each of the light modulation devices 43B, 43G, 43R that generate the end of the image where the brightness may be low by overlapping with the image of another projector.

[0140] According to this configuration, it is not necessary to perform control to make the rotation speed of the rotation element variable with respect to the entire light modulation region of each of the light modulation devices 43B, 43G, 43R, so the configuration of the control unit 100 can be simplified more.

[0141] Further, in the light source device of the above embodiment, as an example of the shape of the transmission optical element, a polygonal prism with an even number of side faces 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 faces is desirable. However, as long as it has a pair of incident surfaces and emission surfaces parallel to each other, a shape other than a polygonal prism with an even number of side faces may be used. Also, the "rotation" in the embodiment of the present application can include performing similar scanning by swinging the transmission optical element.

[0142] In addition, specific descriptions of the shapes, numbers, arrangements, materials, etc. of the components of the light source device and the projector are not limited to the above embodiments and can be changed as appropriate. Further, in the above embodiments, an example in which the light source device according to the present invention is mounted on a projector using a liquid crystal panel has been shown, but the present invention is not limited thereto. The light source device according to the present invention may be applied to a projector using a digital micromirror device as an optical modulation device.

[0143] 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 in time, but generally, the amount of light in the peripheral portion is more likely to decrease than in the central portion of the barcode. For this reason, the barcode reader is likely to have a problem that it is more difficult to read the data at the end of the barcode than the data at the center of the barcode. 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.

[0144] The summary of the present disclosure is appended below. (Appendix 1) A light source unit that emits light, A first transmissive optical element 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, A first rotation element that rotates the first transmissive optical element, The first transmissive optical element is made of a light-transmissive member in which the first incident surface and the first emission surface are parallel to each other, 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 rotation speed of the first transmissive optical element by the first rotation element changes according to the rotation angle of the first transmissive optical element. Light source device.

[0145] According to the light source device of 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 transmission optical element rotates. Therefore, 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, by adjusting the rotation speed of the first transmission optical element by the first rotation element according to the rotation angle of the first transmission optical element, the uniformity of the illuminance distribution of the illuminated area can be enhanced.

[0146] (Appendix 2) The light that has passed through the rotating first transmission optical element travels parallel to the optical axis at a position where it has moved by a displacement amount corresponding to the rotation angle of the first transmission optical element in a direction intersecting the optical axis of the light source unit. The light source device according to Appendix 1.

[0147] According to this configuration, by changing the displacement amount of the light according to the rotation angle of the first transmission 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.

[0148] (Appendix 3) The first rotation element rotates the first transmission optical element around the first rotation axis, thereby scanning the light emitted from the light source unit in the first scanning direction. The light source device according to Appendix 1 or Appendix 2.

[0149] According to this configuration, by scanning the light emitted from the light source unit, the one-dimensional illuminated area can be illuminated.

[0150] (Appendix 4) The first transmission optical element is made of quartz. The light source device according to any one of Appendices 1 to 3.

[0151] 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 transmission optical element is small, and the disturbance of the polarization direction of the light can be suppressed.

[0152] (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.

[0153] According to this configuration, since the light emitted from the light source unit is linearly polarized laser light, when a light modulation device such as a liquid crystal panel is arranged in the illuminated area, the incident side polarizing plate can be omitted.

[0154] (Appendix 6) Let the incident angle of the light with respect to the first incident surface at the first time be the first incident angle, and the incident angle of the light with respect to the first incident surface at the second time different from the first time be the second incident angle. When the second incident angle is larger than the first incident angle, the rotation speed of the first transmission optical element at the second time is smaller than the rotation speed of the first rotation element at the first time. The light source device according to any one of Appendices 1 to 5.

[0155] 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 first period and the second period can be made uniform. Therefore, as described above, the uniformity of the illuminance distribution in the illuminated area can be enhanced.

[0156] (Appendix 7) The first rotation element is a stepping motor. The light source device according to any one of Appendices 1 to 6.

[0157] According to this configuration, since the control of the rotation speed of the first rotation element becomes easy, the uniformity of the illuminance distribution in the illuminated area can be accurately enhanced.

[0158] (Appendix 8) The light transmitted through the first transmission 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 any one of Appendices 1 to 7.

[0159] 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.

[0160] (Appendix 9) A second transmissive optical element 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; Further comprising a second rotation element that rotates the second transmissive optical element; The second transmissive optical element is made of a translucent member in which the second incident surface and the second emission surface are parallel to each other; The second transmissive optical element rotates about a second rotation axis extending along a third direction intersecting each of the first direction and the second direction; The second rotation element scans the light in a second scanning direction intersecting the first scanning direction by rotating the second transmissive optical element about the second rotation axis. The light source device according to Appendix 3.

[0161] According to this configuration, the two-dimensional illuminated area can be illuminated by scanning the light emitted from the light source unit.

[0162] (Appendix 10) The rotation speed of the second transmissive optical element by the second rotation element changes according to the rotation angle of the second transmissive optical element. The light source device according to Appendix 9.

[0163] According to this configuration, by changing the rotation speed of the second transmissive optical element by the second rotating element according to the rotation angle of the second transmissive optical element, the uniformity of the illuminance distribution within the two-dimensional illuminated area can be further enhanced.

[0164] (Appendix 11) When the refractive index of the first transmissive optical element is smaller than the refractive index of the second transmissive optical element, the rotation speed of the second transmissive optical element by the second rotating element does not change according to the rotation angle of the second transmissive optical element. The light source device according to Appendix 9.

[0165] According to this configuration, in order to change the rotation speed of the first transmissive optical element by the first rotating element according to the rotation angle of the first transmissive optical element where the non-linearity of the light displacement amount becomes high, the illuminance distribution of the light can be enhanced while simplifying the control method of the device.

[0166] (Appendix 12) The first transmissive optical element has a first surface and a second surface that intersect the first rotation axis, and 2×n (n: 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×n 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×m (m: 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 exit surface are two of the 2×m second side surfaces that are parallel to each other. The light source device according to Appendix 9.

[0167] 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 small, and the light utilization efficiency can be enhanced.

[0168] (Appendix 13) The rotation speed of the second transmissive optical element by the second rotating element changes according to the rotation angle of the second transmissive optical element. The light source device according to Supplementary Note 12.

[0169] According to this configuration, by changing the rotation speed of the second transmissive optical element by the second rotating element according to the rotation angle of the second transmissive optical element, the uniformity of the illuminance distribution in the two-dimensional illuminated area can be further enhanced.

[0170] (Supplementary Note 14) 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 rotation speed of the second transmissive optical element by the second rotating element does not change according to the rotation angle of the second transmissive optical element. The light source device according to Supplementary Note 12.

[0171] According to this configuration, since the rotation speed of the first transmissive optical element by the first rotating element is changed according to the rotation angle of the first transmissive optical element where the non-linearity of the light displacement amount becomes high, the illuminance distribution of the light can be enhanced while simplifying the control method of the device.

[0172] (Supplementary Note 15) 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 14.

[0173] According to this configuration, since the rotation speed of the first rotating element is changed according to the rotation angle of the first transmissive optical element having a square cross-sectional shape where the non-linearity of the light displacement amount is the highest, the effect of enhancing the uniformity of the illuminance distribution in the illuminated area can be obtained most remarkably.

[0174] (Supplementary Note 16) The light source device according to any one of Supplementary Notes 1 to 15, and an optical modulation device that modulates the light emitted from the light source device according to image information. A projection optical device that projects the light modulated by the light modulation device, and a projector.

[0175] According to the projector of this configuration, it is possible to suppress a decrease in brightness and contrast in the light modulation device, the occurrence of color unevenness, light loss in the projection optical device, etc., and realize a projector with excellent display quality with a simple configuration.

Explanation of Signs

[0176] 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, a first transmission optical element 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, a first rotation element that rotates the first transmission optical element, wherein the first transmission optical element is made of a translucent member in which the first incident surface and the first emission surface are parallel to each other, the first transmission 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 transmission optical element, a rotation speed of the first transmission optical element by the first rotation element changes according to a rotation angle of the first transmission optical element, A light source device.

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

3. The first rotation element scans the light emitted from the light source unit in a first scanning direction by rotating the first transmission optical element about the first rotation axis. The light source device according to claim 1 or claim 2.

4. The first transmission 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. Let the incident angle of the light with respect to the first incident surface at a first time be a first incident angle, and the incident angle of the light with respect to the first incident surface at a second time different from the first time be a second incident angle. When the second incident angle is larger than the first incident angle, the rotation speed of the first transmission optical element at the second time is smaller than the rotation speed of the first rotation element at the first time. The light source device according to claim 1 or claim 2.

7. The first rotation element is a stepping motor. The light source device according to claim 1 or claim 2.

8. The light that has passed through the first transmission optical element forms a rectangular illumination area, the light source unit increases the output of the light that illuminates the outer edge of the illumination area compared to the output of the light that illuminates the inside of the outer edge. The light source device according to claim 1 or claim 2.

9. A second transmissive optical element having a second incident surface on which the light is incident and a second emission surface for emitting the light incident from the second incident surface; Further comprising a second rotating element for rotating the second transmissive optical element; The second transmissive optical element is made of a translucent member in which the second incident surface and the second emission surface are parallel to each other; The second transmissive optical element rotates about a second rotation axis extending along a third direction intersecting each of the first direction and the second direction; The second rotating element scans the light in a second scanning direction intersecting the first scanning direction by rotating the second transmissive optical element about the second rotation axis; The light source device according to claim 3.

10. The rotation speed of the second transmissive optical element by the second rotating element changes according to the rotation angle of the second transmissive optical element; The light source device according to claim 9.

11. When the refractive index of the first transmissive optical element is smaller than the refractive index of the second transmissive optical element, The rotation speed of the second transmissive optical element by the second rotating element does not change according to the rotation angle of the second transmissive optical element; The light source device according to claim 9.

12. The first transmissive optical element has a first surface and a second surface intersecting the first rotation axis, and 2×n (n: 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×n 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×m (m: 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×m second side surfaces that are parallel to each other; The light source device according to claim 9.

13. The rotation speed of the second transmissive optical element by the second rotating element changes according to the rotation angle of the second transmissive optical element; The light source device according to claim 12.

14. 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 rotation speed of the second transmissive optical element by the second rotating element does not change according to the rotation angle of the second transmissive optical element; The light source device according to claim 12.

15. 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.

16. The light source device according to claim 1 or claim 2, 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.

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