Projector

Abstract

To provide a projector that improves light utilization efficiency.SOLUTION: A projector comprises a light source unit, a first transmissive optical element, a first rotation element, a light modulation device, and a control unit. The light modulation device has an image forming area including a plurality of pixels. The first transmissive optical element rotates about a first rotation axis to scan light emitted from the light source on the image forming area of the light modulation device. The control unit performs light controlling control of selecting a light control target pixel on the basis of image information, and when positional coordinates of the light control target pixel are defined as (px, py), the radius in a light scanning direction on the image forming area as r, and the positional coordinates of light on the image forming area at time t as (dx(t), dy(t)), when a luminance value corresponding to the light control target pixel in image light is smaller than a light control reference value at the timing when the following conditional expression is satisfied, reduces output from the light source unit, and when the luminance value is larger than the light control reference value, increases the output from the light source unit.SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] The present invention relates to a projector. [Background technology]

[0002] Conventionally, there is a projector that illuminates a light modulation device such as a liquid crystal panel by scanning light emitted from a light-emitting element over time on the light modulation device. Patent Document 1 listed below discloses a projector that includes a light source device including a light source lamp, a liquid crystal light valve, a polygon mirror provided between the light source device and the liquid crystal light valve, and a projection lens. In this projector, the light source device emits light having an elliptical beam cross section. The polygon mirror reflects the light emitted from the light source device and scans the light in the minor axis direction of the elliptical beam cross section over the image formation area of ​​the liquid crystal light valve. [Prior art documents] [Patent documents]

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

[0004] However, when a polygon mirror is used to scan light, as in the projector of Patent Document 1, even if perfectly parallel light is incident on the polygon mirror, the parallelism of the light is lost due to the polygon mirror. In other words, because the polygon mirror reflects light while rotating, the angle of incidence of the light on the reflective surface of the polygon mirror changes over time, and the parallel light incident on the polygon mirror becomes light with a predetermined divergence angle and illuminates the image formation area of ​​the liquid crystal light valve. As a result, there is a problem in that the light emitted from the light source device cannot be used efficiently. [Means for solving the problem]

[0005] In order to solve the above-described problems, according to a first aspect of the present invention, there is provided a light source unit that emits light, a first transmissive optical element having a first entrance surface into which the light emitted from the light source unit is incident, and a first exit surface from which the light incident from the first entrance surface is emitted, a first rotating element that rotates the first transmissive optical element, a light modulation device that modulates the light emitted from the first transmissive optical element based on image information to generate image light, and a control device that controls output of the light source unit, wherein the light modulation device has an image forming area including a plurality of pixels, and the first transmissive optical element is a light-transmitting member in which the first entrance surface and the first exit surface are parallel to each other, and rotates about a first rotation axis that extends along a second direction that intersects with a first direction that is an incident direction of the light to the first transmissive optical element, The emitted light is scanned over the image forming area of ​​the light modulation device, and the control device sets a dimming reference value and a target pixel selected from the plurality of pixels based on the image information, and performs dimming control to adjust the amount of light incident on the target pixel in the image forming area by reducing the output of the light source unit if the luminance value of the image light corresponding to the target pixel is smaller than the dimming reference value, or by increasing the output of the light source unit if the luminance value is greater than the dimming reference value, when the position coordinates of the target pixel in the image forming area are (px, py), the radius of the light in the scanning direction on the image forming area is r, and the position coordinates of the light on the image forming area at time t are (dx(t), dy(t)), if the following formula is satisfied:

number

[0006] [Figure 1] FIG. 1 is a plan view showing a schematic configuration of a projector according to a first embodiment. [Figure 2] FIG. 2 is a block diagram showing the electrical configuration of the projector. [Figure 3] FIG. 2 is a perspective view showing a schematic configuration of a light source device. [Figure 4A]10A and 10B are schematic diagrams for explaining the behavior of light when a transmissive optical element rotates. [Figure 4B] FIG. 4B is a schematic diagram showing a continuation of FIG. 4A. [Figure 4C] FIG. 4C is a schematic diagram showing a continuation of FIG. 4B. [Figure 4D] FIG. 4D is a schematic diagram showing a continuation of FIG. 4C. [Figure 4E] FIG. 4B is a schematic diagram showing a continuation of FIG. 4D. [Figure 4F] FIG. 4B is a schematic diagram showing a continuation of FIG. 4E. [Figure 5] FIG. 1 is a schematic diagram showing a transmission optical element that is a simulation model. [Figure 6] FIG. 10 is a diagram illustrating a periodic function showing the relationship between the rotation angle and the displacement amount. [Figure 7] 10 is a flowchart showing the flow of each process of light adjustment control. [Figure 8] 3 is a diagram showing a configuration of a main part of an image forming area of ​​a first light modulation element. FIG. [Figure 9] FIG. 10 is an image diagram showing the trajectory of light scanning an image forming area. [Figure 10] 9 is a diagram illustrating dimming control when displaying the characters in FIG. 8. FIG. [Figure 11] 10A and 10B are diagrams showing changes in the displacement amount of a blue light spot. [Figure 12] FIG. 10 is a diagram for explaining dimming control in a second modified example. [Figure 13] FIG. 10 is a plan view showing a schematic configuration of a projector according to a second embodiment. [Figure 14] FIG. 4 is a side view showing the configuration of a second light source unit. [Figure 15] FIG. 10 is a diagram showing the state of light scanning on a light modulation device. [Figure 16] FIG. 2 is a cross-sectional view showing a configuration of a main part of an optical modulation device. DETAILED DESCRIPTION OF THE INVENTION

[0007] (First embodiment) A first embodiment of the present invention will be described below with reference to the drawings. The projector of this embodiment is an example of a liquid crystal projector that uses a liquid crystal panel as a light modulation device. In the drawings below, the dimensions of some components may be shown on different scales to make them easier to see.

[0008] FIG. 1 is a plan view showing a schematic configuration of a projector 200 according to this embodiment. As shown in FIG. 1, the projector 200 of this embodiment includes a light source device 1, a magnifying optical system 2, a color separation optical system 3, a light modulation device 30, an image light combining element 24, a projection optical device 23, and a control device CONT.

[0009] The light source device 1 of this embodiment includes a light source unit 10, a first transmissive optical element 13, a second transmissive optical element 14, a first rotating element 15, and a second rotating element 16. The light source unit 10 includes a first light source unit 101, a second light source unit 102, a third light source unit 103, and a light combining optical system 104. The driving of the light source unit 10, the first rotating element 15, and the second rotating element 16 is controlled by a control device CONT.

[0010] FIG. 2 is a block diagram showing the electrical configuration of the projector 200. As shown in FIG. 2, the control device CONT is configured by a computer or an integrated circuit that has built-in programs for processing the respective driving devices that drive the light source device 1 and the optical modulation device 30. In other words, the control device CONT is, for example, a processor. The control device CONT is connected to the light source device 1 and the optical modulation device 30 by wire or wirelessly (not shown).

[0011] The control device CONT includes a first light source driving unit CON1 that controls the driving of the first light source unit 101, a second light source driving unit CON2 that controls the driving of the second light source unit 102, a third light source driving unit CON3 that controls the driving of the third light source unit 103, a first rotation driving unit CON4 that controls the driving of the first rotating element 15, a second rotation driving unit CON5 that controls the driving of the second rotating element 16, and a panel driving unit CON6 that controls the driving of the light modulation device 30. The control device CONT of this embodiment collectively controls the dimming control of the light source unit 10, the drive control of the rotary elements 15 and 16, and the drive control of the light modulation device 30, thereby enabling simple and highly accurate control.

[0012] The following description will be given using an XYZ Cartesian coordinate system in the drawings as necessary. The X axis is an axis parallel to the optical axis AX of the light source unit 10. The optical axis AX of the light source unit 10 is defined as an axis along the chief ray of illumination light WL (described later) emitted from the light source unit 10. The optical axis AX2 of the second light source unit 102 coincides with the optical axis AX of the light source unit 10. The optical axis AX2 of the second light source unit 102 is defined as an axis along the chief ray of green light LG (described later) emitted from the second light source unit 102. The Y axis is an axis perpendicular to the X axis and parallel to the rotation axis of the first transmissive optical element 13. The Z axis is an axis perpendicular to the X axis and Y axis. The optical axis AX1 of the first light source unit 101 is defined as an axis along the chief ray of blue light LB (described later) emitted from the first light source unit 101. The optical axis AX3 of the third light source unit 103 is defined as an axis along the chief ray of red light LR (described later) emitted from the third light source unit 103. The X-axis direction in this embodiment corresponds to the "first direction" in the claims. The Y-axis direction in this embodiment corresponds to the "second direction" in the claims. The Z-axis direction in this embodiment corresponds to the "third direction" in the claims.

[0013] The first light source unit 101 is disposed such that an optical axis AX1 of the first light source unit 101 is perpendicular to an optical axis AX2 of the second light source unit 102. The third light source unit 103 is disposed such that an optical axis AX3 of the third light source unit 103 is perpendicular to the optical axis AX2 of the second light source unit 102. The first light source unit 101 emits blue light (first light) LB toward the -Z side. The third light source unit 103 emits red light (third light) LR toward the -Z side. The second light source unit 102 emits green light (second light) LG toward the +X side. In this example, the first light source unit 101 is disposed closer to the second light source unit 102, and the third light source unit 103 is disposed farther from the second light source unit 102, but the opposite may be true.

[0014] The first light source unit 101 has a first light-emitting element 25 and a substrate 29. The first light-emitting element 25 is composed of a laser diode that emits light in a first wavelength band. Therefore, the light emitted from the first light-emitting element 25 is linearly polarized light with coherence, and is laser light with a narrow beam width and high parallelism. The first wavelength band is, for example, a blue wavelength band of 450 nm±5 nm. That is, the first light-emitting element 25 emits blue light LB as the first light.

[0015] The second light source unit 102 has a second light-emitting element 26 and a substrate 29. The second light-emitting element 26 is composed of a laser diode that emits light in a second wavelength band different from the first wavelength band. The light emitted from the second light-emitting element 26 is linearly polarized light with coherence, and is laser light with a narrow beam width and high parallelism. The second wavelength band is, for example, a green wavelength band of 530 nm±5 nm. That is, the second light-emitting element 26 emits green light LG as the second light.

[0016] The third light source unit 103 has a third light-emitting element 27 and a substrate 29. The third light-emitting element 27 is composed of a laser diode that emits light in a third wavelength band different from the first wavelength band and the second wavelength band. The light emitted from the third light-emitting element 27 is coherent linearly polarized light, and is laser light with a narrow beam width and high parallelism. The third wavelength band is, for example, a red wavelength band of 650 nm±5 nm. That is, the third light-emitting element 27 emits red light LR as the third light.

[0017] In this embodiment, laser diodes are used as the light-emitting elements 25, 26, and 27, but this is not limitative. Light sources such as LEDs or lamps may also be used in combination with an optical system that adjusts the polarization direction of light, an optical system that adjusts the luminous flux width, a color wheel, etc.

[0018] The light combining optical system 104 includes a first light combining element 105 and a second light combining element 106. The first light combining element 105 is provided at a position where the optical axis AX1 and the optical axis AX2 intersect. The first light combining element 105 is composed of a dichroic mirror that transmits green light and reflects blue light. The second light combining element 106 is provided at a position where the optical axis AX2 and the optical axis AX3 intersect. The second light combining element 106 is composed of a dichroic mirror that transmits green light LG and blue light LB and reflects red light LR. The light combining optical system 104 combines the blue light LB emitted from the first light source unit 101, the green light LG emitted from the second light source unit 102, and the red light LR emitted from the third light source unit 103 to generate white light LW. As a result, the light source unit 10 emits white light LW. The white light LW is incident on the first transmissive optical element 13 without being separated by wavelength band.

[0019] The first transmissive optical element 13 is provided on the optical axis of the light source unit 10, between the light source unit 10 and the second transmissive optical element 14. The first transmissive optical element 13 is made of a rotatably supported light-transmitting member. The first transmissive optical element 13 is rotatable about a first rotation axis C1 extending along the Y-axis direction. The first rotation axis C1 is connected to a first rotation element 15 formed of a motor or the like. The first transmissive optical element 13 rotates about the first rotation axis C1 by driving the first rotation element 15.

[0020] Fig. 3 is a perspective view showing a schematic configuration of the light source device 1. In Fig. 3, the light source section 10 is omitted for ease of viewing the drawing. As shown in FIG. 3 , the first transmissive optical element 13 is made of a translucent material such as optical glass (e.g., BK7), quartz, or resin. The first transmissive optical element 13 has a first surface 13a and a second surface 13b that intersect with the first rotation axis C1, and four first side surfaces 13c that are perpendicular to the first surface 13a and the second surface 13b. That is, the shape of the first transmissive optical element 13 is a regular rectangular prism having six flat surfaces including the first surface 13a, the second surface 13b, and the four first side surfaces 13c. The cross section of the first transmissive optical element 13 cut along a plane perpendicular to the first rotation axis C1 is a square. That is, the four first side surfaces 13c have the same area, and two opposing first side surfaces 13c are parallel to each other.

[0021] The first transmissive optical element 13 transmits the white illumination light WL emitted from the light source unit 10 while rotating about the first rotation axis C1. Therefore, the first side surface 13c through which the illumination light WL emitted from the light source unit 10 enters the first transmissive optical element 13 is not fixed and changes over time. Similarly, the first side surface 13c through which the illumination light WL incident on the first transmissive optical element 13 is emitted to the external space is not fixed and changes over time. In the first transmissive optical element 13, the first side surface 13c through which the illumination light WL emitted from the light source unit 10 enters is referred to as the first incident surface. The first side surface 13c through which the illumination light WL incident from the first incident surface exits is referred to as the first exit surface. The first incident surface and the first exit surface change over time and are either of two first side surfaces 13c that are parallel to each other among the four first side surfaces 13c.

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

[0023] In this embodiment, the first transmissive optical element 13 has four first side surfaces 13c, but the number of first side surfaces 13c does not necessarily have to be four and is preferably 2×m (m: a natural number greater than or equal to 2). That is, the number of first side surfaces 13c is preferably an even number greater than or equal to 4, such as 6 or 8. If the number of first side surfaces 13c is an even number greater than or equal to 4, all of the first side surfaces 13c are parallel to the first side surface 13c opposite to the first side surface 13c, and there is no first side surface 13c that does not have a parallel pair. This reduces the generation of stray light in the first transmissive optical element 13, thereby improving light utilization efficiency.

[0024] The second transmissive optical element 14 is provided on the light-emitting side of the first transmissive optical element 13 on the optical axis AX of the light source unit 10. The second transmissive optical element 14 is made of a rotatably supported light-transmitting member. The second transmissive optical element 14 is rotatable about a second rotation axis C2 extending along the Z-axis direction. That is, the first rotation axis C1 and the second rotation axis C2 extend in directions perpendicular to each other in an imaginary plane perpendicular to the optical axis AX. The second rotation axis C2 is connected to a second rotation element 16 formed of a motor or the like. The second transmissive optical element 14 rotates about the second rotation axis C2 by driving the second rotation element 16.

[0025] The light-transmitting member constituting the second transmissive optical element 14 is substantially the same as the light-transmitting member constituting the first transmissive optical element 13. As the glass material of the light-transmitting member, for example, optical glass such as BK7, quartz, resin, or other light-transmitting materials are used. In particular, unlike the first transmissive optical element 13, the second transmissive optical element 14 receives the illumination light WL after being scanned in one direction by the first transmissive optical element 13, and therefore has a lower light density than the illumination light WL at the time of incidence on the first transmissive optical element 13. Therefore, it is more likely than the first transmissive optical element 13 that a resin material with low light resistance or low heat resistance can be used.

[0026] The second transmissive optical element 14 has a third surface 14a and a fourth surface 14b that intersect with the second rotation axis C2, and four second side surfaces 14c that are perpendicular to the third surface 14a and the fourth surface 14b. That is, the shape of the second transmissive optical element 14 is a regular rectangular prism having six flat surfaces including the third surface 14a, the fourth surface 14b, and the four second side surfaces 14c. The cross-sectional shape of the second transmissive optical element 14 taken along a plane perpendicular to the second rotation axis C2 is a square. The four second side surfaces 14c have the same area, and two opposing second side surfaces 14c are parallel to each other.

[0027] The second transmissive optical element 14 transmits the illumination light WL emitted from the first transmissive optical element 13 while rotating about the second rotation axis C2. Therefore, the second side surface through which the illumination light WL emitted from the first transmissive optical element 13 enters the second transmissive optical element 14 is not fixed and changes over time. Similarly, the second side surface through which the illumination light WL incident on the second transmissive optical element 14 is emitted to external space is not fixed and changes over time. In the second transmissive optical element 14, the second side surface through which the illumination light WL emitted from the first transmissive optical element 13 enters is referred to as the second incident surface. The second side surface through which the illumination light WL incident from the second incident surface exits is referred to as the second exit surface. In this case, the second incident surface and the second exit surface change over time and are either of two second side surfaces 14c that are parallel to each other among the four second side surfaces 14c.

[0028] In this embodiment, the second transmissive optical element 14 has four second side surfaces 14c, but the number of second side surfaces does not necessarily have to be four; it is desirable that the number be 2×n (n: a natural number greater than or equal to 2). That is, it is desirable that the number of second side surfaces be an even number, for example, 6, 8, or the like. If the number of second side surfaces is an even number, all of the second side surfaces are parallel to the second side surface opposite to the second side surface, and there are no second side surfaces that are not parallel. This reduces the generation of stray light in the second transmissive optical element 14, thereby improving light utilization efficiency.

[0029] In this embodiment, the first transmissive optical element 13 and the second transmissive optical element 14 both have the shape of a regular rectangular prism, but the first transmissive optical element 13 and the second transmissive optical element 14 may have different shapes as long as they have parallel entrance and exit surfaces.

[0030] In FIG. 2 , the first transmissive optical element 13 is shown as being the same size as the second transmissive optical element 14. However, as will be described later, the first transmissive optical element 13 scans the illumination light WL in the Z-axis direction but not in the Y-axis direction. Therefore, the length of the side in the Y-axis direction may be shorter than the lengths of the sides in the X-axis and Z-axis directions. That is, instead of the cubic shape shown in FIG. 2 , the first transmissive optical element 13 may have a rectangular parallelepiped shape in which the length of the side in the Y-axis direction is shorter than the lengths of the sides in the X-axis and Z-axis directions. This allows the first transmissive optical element 13 to be made thinner. In this case, the dimensions of the second transmissive optical element 14 are larger than those of the first transmissive optical element 13. However, as described above, since the optical density of the incident light is low in the second transmissive optical element 14, a resin material can be used. Using a resin material as the glass material for the light-transmitting member reduces the weight of the second transmissive optical element 14, thereby allowing the second rotating element 16 to be made smaller.

[0031] At least one of the first transmissive optical element 13 and the second transmissive optical element 14 may be made of quartz. In the first transmissive optical element 13 and the second transmissive optical element 14, as the amount of light transmitted through the translucent member increases, the amount of light absorbed by the translucent member also increases, which may cause thermal distortion in the translucent member. In this case, the polarization direction of the illumination light WL emitted from the light source unit 10 is disturbed, and linearly polarized light incident on the translucent member becomes elliptically polarized light before being emitted from the translucent member. As a result, the projector 200 loses the effect of achieving a predetermined contrast without an incident-side polarizing plate by using laser diodes for each light source unit 101, 102, and 103. In other words, even though laser diodes are used for each light source unit 101, 102, and 103, it becomes necessary to use an incident-side polarizing plate to align the polarization direction. Therefore, to achieve the above effect, it is desirable to use a glass material with a small Young's modulus and thermal expansion coefficient as a glass material with low thermal distortion, and quartz is a desirable example.

[0032] The following describes the behavior of the illumination light WL when it passes through the first transmissive optical element 13 and the second transmissive optical element 14. Note that the action of the first transmissive optical element 13 and the action of the second transmissive optical element 14 are similar, only the direction is different, so only the first transmissive optical element 13 will be illustrated and described below.

[0033] 4A to 4F are schematic diagrams for explaining the behavior of the illumination light WL when the first transmissive optical element 13 rotates. In this example, when viewed from the +Y side, the first transmissive optical element 13 rotates clockwise around the first rotation axis C1, and time passes from FIG. 4A to FIG. 4F.

[0034] 4A to 4F, the angle formed between the optical axis AX and a straight line M that passes through the first rotation axis C1 and is perpendicular to the first side surface 13c1 of the first transmissive optical element 13 is defined as the rotation angle ω of the first transmissive optical element 13. In reality, the illumination light WL has a predetermined luminous flux width in the Z-axis direction, but here we will focus on the behavior of the light ray WL1 that is the chief ray of the illumination light WL traveling on the optical axis AX.

[0035] 4A shows the initial state of the first transmissive optical element 13. That is, the first transmissive optical element 13 is not rotated, the straight line M and the optical axis AX overlap, and the rotation angle ω is 0 degrees. In this case, the light ray WL1 is perpendicularly incident on the first side surface 13c1 and therefore travels along the optical axis AX inside the first transmissive optical element 13 without being refracted at the first side surface 13c1. Next, the light ray WL1 is also perpendicularly incident on the first side surface 13c3, which is parallel to the first side surface 13c1. Therefore, the light ray WL1 is not refracted at the first side surface 13c3 either, and is emitted from the first transmissive optical element 13 and travels along the optical axis AX.

[0036] Next, as shown in FIG. 4B , when the first transmissive optical element 13 rotates by the rotation angle ω, the light ray WL1 is incident on the first side surface 13c1 at an incident angle equal to the rotation angle ω. Therefore, the light ray WL1 is refracted in the direction shown in the figure (toward the +Z side) and travels inside the first transmissive optical element 13. Next, the light ray WL1 is incident on the first side surface 13c3 at a predetermined incident angle, is refracted at the first side surface 13c3, and is emitted from the first transmissive optical element 13. At this time, because the first side surfaces 13c1 and 13c3 are parallel to each other, the incident angle of the light ray WL1 on the first side surface 13c1 and the incident angle of the light ray WL1 on the first side surface 13c3 are equal, and the refraction angle of the light ray WL1 incident on the first side surface 13c1 and the refraction angle of the light ray WL1 emitted from the first side surface 13c3 have opposite signs but equal absolute values. This causes the angle of refraction of light ray WL1 when it enters first side surface 13c1 to cancel out the angle of refraction when it emerges from first side surface 13c3. As a result, light ray WL1 travels parallel to the optical axis AX at a position displaced by a displacement amount d from the optical axis AX toward the +Z side.

[0037] Next, as shown in Figure 4C, when the rotation angle ω of the first transmissive optical element 13 becomes larger than that of Figure 4B, the angle of incidence of the light ray WL1 becomes larger, and the angle of refraction also becomes larger. Therefore, the displacement d of the light ray WL1 from the optical axis AX becomes larger than that in Figure 4B. Furthermore, the state in which the light ray WL1 travels parallel to the optical axis AX is always maintained. When the rotation angle ω is between 0 degrees and 45 degrees, the displacement d increases monotonically as the rotation angle ω increases.

[0038] Next, as shown in FIG. 4D, when the rotation angle ω of the first transmissive optical element 13 exceeds 45 degrees, the incident surface of the light ray WL1 changes from the first side surface 13c1 to the first side surface 13c2. At this time, the light ray WL1 is refracted at the first side surface 13c2, but the refraction direction is different from that in the period up to FIG. 4C, and the light ray WL1 is refracted in the direction shown in the figure (toward the -Z side). The exit surface of the light ray WL1 also changes from the first side surface 13c3 to the first side surface 13c4. However, because the first side surfaces 13c2 and 13c4 are parallel to each other, the refraction angle of the light ray WL1 when it enters the first side surface 13c3 and the refraction angle when it exits from the first side surface 13c4 cancel each other out, as in the period up to FIG. 4C. As a result, the light ray WL1 travels parallel to the optical axis AX at a position displaced by a displacement amount d toward the -Z side from the optical axis AX.

[0039] Next, as shown in Fig. 4E, when the rotation angle ω of the first transmissive optical element 13 becomes larger than that in Fig. 4D, the angle of incidence of the light ray WL1 becomes smaller, and the angle of refraction becomes smaller. Therefore, the displacement amount d of the light ray WL1 from the optical axis AX becomes smaller than that in Fig. 4D. In this way, when the rotation angle ω is between 45 degrees and 90 degrees, the displacement amount d decreases monotonically as the rotation angle ω increases.

[0040] Next, as shown in FIG. 4F, when the rotation angle ω of the first transmissive optical element 13 becomes 90 degrees, the incident surface changes from the first side surface 13c1 in the initial state to the first side surface 13c2, but the behavior of the light ray WL1 becomes the same as in the initial state shown in FIG. 4A.

[0041] As described above, if the first entrance surface and the first exit surface of the first transmissive optical element 13 are parallel to each other, the traveling direction of the light ray WL1 does not change regardless of the rotation angle ω of the first transmissive optical element 13, and the light ray WL1 translates in a direction parallel to the optical axis AX over time. When the rotation angle ω is 0 degrees, the displacement d of the light ray WL1 is 0. As the rotation angle ω ranges from 0 degrees to 45 degrees, the displacement d increases toward either the +Z or -Z side. As soon as the rotation angle ω exceeds 45 degrees, the displacement direction reverses while the absolute value of the displacement d remains the same. As the rotation angle ω ranges from 45 degrees to 90 degrees, the displacement d decreases. When the rotation angle ω reaches 90 degrees, the displacement d becomes 0. After the rotation angle ω reaches 90 degrees, the above behavior is repeated. Therefore, when the first transmissive optical element 13 rotates once, the displacement d of the light ray WL1 repeats the above cycle four times. The displacement amount of the light beam WL1 can be set appropriately by adjusting the parameters of the first transmissive optical element 13, such as the refractive index and size.

[0042] Although only one-directional displacement by the first transmissive optical element 13 has been described above, the light source device 1 includes the first transmissive optical element 13 and the second transmissive optical element 14 having rotation axes perpendicular to each other. Therefore, the illumination light WL is displaced in two mutually perpendicular directions over time. Specifically, as shown in FIG. 3 , the illumination light WL emitted from the light source unit 10 is scanned in the Z-axis direction by the first transmissive optical element 13, and is scanned in the Y-axis direction perpendicular to the Z-axis direction by the second transmissive optical element 14. In other words, the first transmissive optical element 13 and the second transmissive optical element 14 scan the illumination light WL within the two-dimensional illumination area Q on the illumination surface, i.e., over each of the light modulation elements 30B, 30G, and 30R.

[0043] 1, illumination light WL is incident on a magnifying optical system 2. The magnifying optical system 2 includes, for example, a concave lens 2a and a convex lens 2b. The magnifying optical system 2 enlarges the beam diameter of illumination light WL emitted from a light source device 1.

[0044] The illumination light WL that has passed through the magnifying optical system 2 enters the color separating optical system 3 . The color separation optical system 3 separates the illumination light WL emitted from the light source device 1 into red light LR, green light LG, and blue light LB, and guides them to the light modulation elements of the light modulation device 30.

[0045] The light modulation device 30 of this embodiment includes a first light modulation element 30B, a second light modulation element 30G, a third light modulation element 30R, and half-wave plates 33B and 33R.

[0046] The color separation optical system 3 includes a first dichroic mirror 7a, a second dichroic mirror 7b, a first total reflection mirror 8a, a second total reflection mirror 8b, and a third total reflection mirror 8c.

[0047] The first dichroic mirror 7a separates the illumination light WL from the light source device 1 into red light LR and light containing green light LG and blue light LB. The first dichroic mirror 7a transmits the blue light LB and reflects the light containing green light LG and red light LR. On the other hand, the second dichroic mirror 7b reflects the green light LG and transmits the red light LR. In this way, the second dichroic mirror 7b separates the light containing green light LG and red light LR into green light LG and red light LR.

[0048] The first total reflection mirror 8a is disposed in the optical path of the blue light LB and reflects the blue light LB that has passed through the first dichroic mirror 7a toward the first light modulation element 30B. Meanwhile, the second total reflection mirror 8b and the third total reflection mirror 8c are disposed in the optical path of the blue light LB and guide the red light LR that has passed through the second dichroic mirror 7b toward the third light modulation element 30R. The green light LG is reflected from the second dichroic mirror 7b toward the second light modulation element 30G.

[0049] The first light modulation element 30B has a light modulation panel 31B and an exit-side polarizing plate 32B. The second light modulation element 30G has a light modulation panel 31G and an exit-side polarizing plate 32G. The third light modulation element 30R has a light modulation panel 31R and an exit-side polarizing plate 32R.

[0050] A transmissive liquid crystal panel is used for each of the light modulation panels 31B, 31G, and 31R. The driving method for the liquid crystal panel is not particularly limited, and may be a twisted nematic (TN) method, a vertically aligned (VA) method, an in-plane switching (IPS) method, or the like. The driving of each of the light modulation panels 31B, 31G, and 31R of the light modulation elements 30B, 30G, and 30R is controlled by a control device CONT electrically connected thereto.

[0051] Each of the exit-side polarizing plates 32B, 32G, and 32R transmits linearly polarized light in a specific direction. In this embodiment, since each of the light source units 101, 102, and 103 of the light source device 1 emits laser light as blue light LB, green light LG, and red light LR, the polarizing plate on the light entrance side of each of the light modulation elements 30B, 30G, and 30R can be omitted.

[0052] The blue light LB is superimposed in time by being scanned two-dimensionally on the image forming area of ​​the first light modulation element 30B. The first light modulation element 30B modulates the blue light LB based on blue image information (first image information) input from an external device to the control device CONT, for example, to form blue image light (first image light) B.

[0053] The green light LG is temporally superimposed by being two-dimensionally scanned on the image forming area of ​​the second light modulation element 30G. The second light modulation element 30G modulates the green light LG based on green image information (second image information) input to the control device CONT from an external device, for example, to form green image light (second image light) G.

[0054] The red light LR is superimposed in time by being scanned two-dimensionally on the image forming area of ​​the third light modulation element 30R. The third light modulation element 30R forms red image light (third image light) R by modulating the red light LR based on red image information (third image information) input to the control device CONT from, for example, an external device.

[0055] The image light combining element 24 receives the image lights of the respective colors emitted from the first light modulation element 30B, the second light modulation element 30G, and the third light modulation element 30R, combines the image lights corresponding to the blue light LB, the green light LG, and the red light LR, and emits the combined image light toward the projection optical device 23. The image light combining element 24 may be, for example, a cross dichroic prism.

[0056] Half-wave plates 33B and 33R are provided between the first light modulation element 30B and the image light combiner 24, and between the third light modulation element 30R and the image light combiner 24, respectively. The half-wave plates 33B and 33R impart a phase difference of half a wavelength to the incident colored light and rotate the polarization direction of the linearly polarized light by 90 degrees. This makes it possible to make the polarization direction of the green light LG incident on the image light combiner 24 different from the polarization directions of the blue light LB and red light LR incident on the image light combiner 24. This configuration can improve the light utilization efficiency of the image light combiner 24.

[0057] 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 combining element 24 onto a projection surface such as a screen, thereby displaying an image on the projection surface.

[0058] As described above, when light transmitted through a rotating transmissive optical element is scanned over time on a light modulation element, unevenness usually occurs in the illuminance distribution formed on the light modulation element. The inventors conducted a simulation to investigate how various parameters of the transmissive optical element, such as the refractive index and shape, affect the illuminance distribution in the illuminated area. The results of the simulation are described below.

[0059] Fig. 5 is a schematic diagram showing a transmissive optical element 18 that serves as 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-polygon (n is an even number equal to or greater than 4), but in Fig. 5, the cross-sectional shape of the transmissive optical element 18 is a square (n = 4). Furthermore, the distance between the opposing surfaces of the transmissive optical element 18 is set to l, the refractive index of the external space of the transmissive optical element 18 is set to n1, and the refractive index of the transmissive optical element 18 is set to n2.

[0060] 5, the optical axis AX of a light source unit (not shown) that emits a light ray WL1 toward the transmissive optical element 18 passes through the center of the rotation axis O of the transmissive optical element 18. The light ray WL1 travels parallel to the optical axis AX, enters the first entrance surface 18a of the transmissive optical element 18 at point P1 at an incident angle θ1, is refracted at a refraction angle θ2, and then emerges from the first exit surface 18b of the transmissive optical element 18 at point P2, traveling parallel to the optical axis AX.

[0061] The light ray WL1 transmitted through the rotating transmitting optical element 18 travels parallel to the optical axis AX at a position moved in a direction perpendicular to (intersecting) the optical axis AX by a displacement amount d according to the rotation angle of the transmitting optical element 18. Therefore, the following equation (1) holds between the displacement amount d of the light ray WL1, the angle of incidence θ1, and the angle of refraction θ2 according to Snell's law.

[0062]

number

[0063] The maximum incident angle θmax of the light ray WL1 on the transmitting optical element 18 is expressed by the following equation (2).

[0064]

number

[0065] For example, in equation (1), 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 horizontal axis is the rotation angle (degrees), the vertical axis is the displacement (mm), 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 can be expressed as a periodic function. Furthermore, if the refractive index n2 of the transmissive optical element 18 is increased toward infinity for this periodic function, the relationship between the rotation angle and the displacement can be defined by an ideal sine wave with amplitude l.

[0066] Because the rotation angle and the incident angle θ1 of the transmitting optical element 18 are equal, the rotation angle of the transmitting optical element 18 should be considered within the range of the maximum incident angle θmax of the light WL1. Furthermore, the maximum incident angle θmax of the transmitting optical element 18 is determined according to the cross-sectional shape as shown in equation (2). That is, when the cross-sectional shape of the transmitting optical element 18 is square as shown in FIG. 5, the maximum incident angle θmax is at its maximum (45 degrees). Therefore, when a light ray WL1 traveling on the optical axis AX passing through the center of rotation of the transmitting optical element 18 is displaced in a direction perpendicular to the optical axis AX by passing through the transmitting optical element 18, it is considered sufficient to consider the periodic function showing the relationship between the rotation angle of the square-shaped transmitting optical element 18 and the amount of displacement within an angular range of ±45 degrees.

[0067] The inventors have noticed that the more linear the graph, the more uniform the illuminance distribution of light in the illuminated area can be improved.

[0068] FIG. 6 is a graph showing the relationship between the rotation angle and the displacement of the square-shaped transmissive optical element 18. In FIG. 6, the horizontal axis represents the rotation angle (degrees), and the vertical axis represents the displacement (mm). Graph A shows the case where the refractive index n2 is 1.63. Graph B shows the case where the refractive index n2 is 2.22. Graph C shows the case where the refractive index n2 is 2.46. Graph D shows the case where the refractive index n2 is 2.91. Graph E shows the case where the refractive index n2 is 3.05. Graph F shows the case where the refractive index n2 is 3.27. In Figure 6, the solid lines indicated by the symbols A to F are graphs showing periodic functions indicating the relationship between the rotation angle and displacement amount of the transmitting optical element 18 in an angle range from 0 degrees to 45 degrees, and the dashed lines indicated by the symbols A1 to F1 are graphs that linearly approximate the periodic functions of the symbols A to F.

[0069] As shown in Figure 6, it can be seen that the linearity of the graph increases as the refractive index n2 of the transmissive optical element 18 increases. In other words, when the cross-sectional shape of the transmissive optical element 18 is square, the linearity of the graph increases as the refractive index increases, thereby improving the uniformity of the illuminance distribution of light in the illuminated area. For example, when the refractive index of the transmissive optical element 18 is 2.91, the solid line and the dashed line overlap, so the linearity of the graph becomes sufficiently high, and it becomes possible to sufficiently improve the uniformity of the illuminance distribution of light in the illuminated area.

[0070] On the other hand, at this stage, it is not very feasible to form the transmissive optical element 18 from a material with a refractive index of 3.0 or higher, and there are limits to improving the uniformity of the illuminance distribution by devising the material of the transmissive optical element 18. In response to this, the present inventors have found that the refractive index required to improve the linearity of the graph varies depending on the shape of the transmissive optical element.

[0071] Table 1 below shows the relationship between the refractive index of a transmissive optical element and its shape (regular n-gon). In Table 1, the medium outside the transmissive optical element is air (refractive index 1.0). In Table 1, the coefficient of determination, which is the square of the correlation coefficient (denoted as R2), in the approximation formula is set to 0.995 or greater. In Table 1, the "-" indicates that any material can be used as long as the refractive index is greater than 1.0.

[0072] [Table 1]

[0073] As shown in Table 1, when the cross-sectional shape of the transmitting optical element 18 is square (n=4), if the refractive index of the transmitting optical element 18 is 1.63 or more, the coefficient of determination of the graph showing the displacement amount is 0.995, and the linearity of the graph can be improved. In contrast, when the cross-sectional shape of the transmitting optical element is a regular hexagon, the coefficient of determination of the graph can be 0.995 by setting the refractive index of the transmitting optical element 18 to 1.14. Furthermore, when the cross-sectional shape is a regular hexagon, the coefficient of determination of the graph can be 0.99995 by setting the refractive index to 2.80, and the linearity of the graph can be sufficiently improved. Therefore, when the cross-sectional shape of the transmitting optical element is a regular hexagon, the linearity of the graph can be improved while keeping the refractive index of the transmitting optical element 18 lower than when the cross-sectional shape of the transmitting optical element is square.

[0074] The inventors have found that, as shown in Table 1 above, when the cross-sectional shape of a transmissive optical element is a regular octagon, a regular decagon, or a regular dodecagon, i.e., a regular polygon with eight or more sides, the linearity of the graph can be sufficiently improved by setting the refractive index of the transmissive optical element within a general range, such as 1 to 2.73. Therefore, if the cross-sectional shape of a transmissive optical element is a regular polygon with eight or more sides, the restrictions on the refractive index of the transmissive optical element are reduced, thereby broadening the range of materials that can be used as the transmissive optical element. This makes it easier to design the optical design of the transmissive optical element.

[0075] Based on this configuration, in the projector 200 of this embodiment, the materials of the first transmissive optical element 13 and the second transmissive optical element 14 are appropriately selected to increase the uniformity of the illuminance distribution of the light that scans two-dimensionally on each of the light modulation elements 30B, 30G, and 30R.

[0076] Furthermore, the present inventors have noticed that when light scans the image forming areas of the light modulation elements 30B, 30G, and 30R, for example, light incident on black display areas of the image forming areas is not emitted from the light modulation elements 30B, 30G, and 30R, resulting in unnecessary power consumption by the light source device 1. The present inventors have then completed the projector 200 of this embodiment, which improves the power utilization efficiency of the light source device 1 by performing dimming control to adjust the brightness of the light scanning the image forming areas of the light modulation elements 30B, 30G, and 30R.

[0077] The dimming control of the projector 200 of this embodiment will be described below. FIG. 7 is a flowchart showing the flow of each process of the dimming control. 7, when the projector 200 starts operating, the control device CONT starts the dimming process. In step S1, the control device CONT reads an image frame included in image information input from an external device. The image information is composed of a single image frame or multiple image frames depending on the type of image to be displayed.

[0078] In step S2, the control device CONT determines whether the read image frame includes a light-modulating target area. The control device CONT determines whether or not a dimming target area is included in the displayed image based on image information input from an external device. In this specification, the dimming target area refers to an area including the dimming target image. The dimming target pixel is a pixel that has a luminance value higher or lower than a dimming reference value, which is a threshold for determining whether or not dimming is performed, and is subject to dimming control. In this embodiment, a case will be described in which a pixel (white display pixel) that has a luminance value higher than the dimming reference value (black display pixel) is defined as the dimming target pixel. For this reason, in step S2, the control device CONT of this embodiment determines whether or not the image to be light-modulated is included in the plurality of pixels in the image formation area.

[0079] The following describes an example of modulating the blue light LB that is color-separated from the illumination light WL emitted from the light source device 1 and scans the image forming area of ​​the first light modulation element 30B. Note that the same concept applies to a method of adjusting the luminance of the green light LG that scans the image forming area of ​​the second light modulation element 30G and the luminance of the red light LR that scans the image forming area of ​​the third light modulation element 30R.

[0080] FIG. 8 is a diagram showing the main configuration of the image forming area 50 of the first light modulation element 30B. As shown in Fig. 8, the first light modulation element 30B has an image formation area 50 formed on the light modulation panel 31B. The image formation area 50 includes a plurality of pixels 50G. Fig. 8 is an image diagram of forming an image displaying the characters "EPSON" on a black background on the image formation area 50. The image forming areas of the second light modulation element 30G and the third light modulation element 30R have the same configuration as the image forming area 50 of the first light modulation element 30B.

[0081] The image forming area 50 includes a first area A1 that forms the characters "EPSON" and a second area A2 that forms the black background. Hereinafter, the pixels 50G that form the first area A1 will be referred to as first pixels 50G1, and the pixels 50G that form the second area A2 will be referred to as second pixels 50G2.

[0082] FIG. 9 is an image diagram showing the trajectory of the blue light LB scanning the image forming area 50 of the first light modulation element 30B. 9, the blue light LB forms a substantially circular spot SP on the image forming area 50. The spots SP of the blue light LB are scanned so as to trace multiple trajectories that extend diagonally from the upper right to the lower left in the figure. Hereinafter, the trajectories that the spots SP of the blue light LB trace on the image forming area 50 may also be referred to as scanning lines.

[0083] It should be noted that the smaller the radius of the spot SP of the blue light LB, or the more scanning lines that scan the image forming area 50, the more uniform the illuminance distribution within the image forming area 50 and the more the resolution of the dimming area improve. In addition, reducing the radius r of the spot SP of the blue light LB means that the radius r becomes smaller relative to the image forming area 50 on the image forming area 50, and for example, the radius r of the spot SP may be reduced by increasing the size of the light modulation element.

[0084] The first pixel 50G1 is a pixel that displays characters, and therefore needs to transmit blue light LB. On the other hand, the second pixel 50G2 is a pixel that displays black, and therefore does not need to transmit blue light LB. If blue light LB were incident on both the first pixel 50G1 and the second pixel 50G2, the blue light LB that entered the second pixel 50G2 would be blocked by the exit-side polarizing plate 32B subsequent to the second pixel 50G2, and therefore the blue light LB that entered the second pixel 50G2 would be lost. The control device CONT treats the first region A1 of the image forming region 50 as a "dimming target area" and the first pixel 50G1 of the first region A1 as a "dimming target pixel."

[0085] That is, when the image shown in Fig. 8 is displayed in the image forming area 50, the control device CONT determines in step S2 that the image to be dimmed is included in the plurality of pixels in the image forming area (step S2: YES), and proceeds to step S3 shown in Fig. 7. In step S3, the control device CONT calculates the timing of dimming control and the dimming amount. In addition, in step S2, if the light-control target area is not included in the read image frame (step S2: NO), the control device CONT proceeds to step S7, which will be described later.

[0086] The specific processing in step S3 will be described below with reference to the drawings. Fig. 10 is a diagram illustrating dimming control when displaying the characters in Fig. 8. In Fig. 10, for ease of viewing, only the "E" of the letters "EPSON" displayed on the image forming area 50 is shown enlarged. Note that in Fig. 10, a spot SP formed on the image forming area 50 when blue light LB is actually emitted is shown by a solid line, and a virtual spot SP formed on the image forming area 50 when blue light LB is not emitted and it is assumed that blue light LB is incident is shown by a dashed line. Hereinafter, the spot SP shown by the solid line may be referred to as a real spot SP1, and the spot SP shown by the dashed line may be referred to as a virtual spot SP2.

[0087] 10, the spot SP of the blue light LB scans diagonally from the upper right to the lower left on the image forming area 50. The spot SP of the blue light LB passes through the first pixel 50G1 or the second pixel 50G2 on the image forming area 50.

[0088] In the following, when explaining the positional relationship on the image forming area 50, an xy coordinate system is set on the image forming area 50. The direction along the left and right of the image forming area 50 shown in Fig. 10 is referred to as the left-right direction x, and the direction along the top and bottom of the image forming area 50 is referred to as the top-bottom direction y.

[0089] Fig. 11 is a diagram showing the displacement of the spot SP of the blue light LB accompanying the rotation of the first transmissive optical element 13 and the second transmissive optical element 14. In Fig. 11, the horizontal axis represents time (s) and the vertical axis represents displacement (mm). Fig. 11 shows the displacement of the blue light LB in the x and y directions on the image forming area 50, with the straight lines corresponding to periods when the blue light LB is on and the broken lines corresponding to periods when the blue light LB is not on.

[0090] The control device CONT turns on the first light source unit 101 using the first-light-source driving unit CON1 shown in Fig. 2 so that the blue light LB is turned on for a period corresponding to the portion indicated by the straight line in Fig. 11 at the timing when the actual spot SP1 of the blue light LB passes through the first pixel 50G1 as shown in Fig. 10. As a result, the blue light LB irradiates the first pixel 50G1 as shown in Fig. 10.

[0091] At the timing when the virtual spot SP2 of the blue light LB passes through the second pixel 50G2 as shown in Fig. 10, the control device CONT turns off the first light source unit 101 using the first-light-source driving unit CON1 shown in Fig. 2 so as to turn off the blue light LB for a period corresponding to the broken portion of the straight line in Fig. 11. As a result, the blue light LB is not irradiated onto the second pixel 50G2 as shown in Fig. 10.

[0092] In this way, the control device CONT performs dimming control to adjust the brightness of the blue light LB so that the blue light LB is turned on in accordance with the timing at which it passes through the first pixel 50G1 and turned off in accordance with the timing at which it passes through the second pixel 50G2, thereby reducing wasted power consumption by the light source unit 10.

[0093] The timing of the dimming control will be described in more detail below. Here, if the angle of incidence of the blue light LB with respect to the first transmissive optical element 13, which is responsible for displacement in the left-right direction x on the image forming area 50, is θx(t), then θx(t) becomes a sawtooth wave with an amplitude θxmax and a period T. Therefore, when θx(t) is applied to the general formula for a sawtooth wave, the following formula (3) holds:

[0094]

number

[0095] Here, floor(x) is the floor function for real number x, and is defined as the largest integer less than or equal to x.

[0096] Since the incident angle θx(t) of the blue light LB to the first transmitting optical element 13 is expressed by the above equation (1), the displacement dx(t) of the blue light LB in the x-axis direction on the image forming area 50 of the first light modulation element 30B is expressed by the following equation (4).

[0097]

number

[0098] The incident angle of the blue light LB with respect to the second transmitting optical element 14, which is responsible for displacement in the vertical direction y on the image forming area 50, is expressed by an equation similar to the above equation (3), and the displacement amount dy(t) of the blue light LB in the y-axis direction on the first light modulation element 30B is expressed by an equation similar to the above equation (4) in which x is replaced by y.

[0099] Here, the position coordinates of the first pixel 50G1 in the image forming area 50 are (px, py), the radius of the blue light LB in the scanning direction on the image forming area 50 is r, and the position coordinates of the blue light LB on the image forming area 50 at time t are (dx(t), dy(t)).

[0100] At this time, the control device CONT increases the output of the first light source unit 101 at a timing that satisfies the following formula (5). Specifically, in this embodiment, the control device CONT adjusts the first light source unit 101 to increase the amount of blue light LB incident on the first pixel 50G1 by changing the first light source unit 101 from an off state to an on state. In this embodiment, the control device CONT sets the dimming amount of the first light source unit 101 so that the blue light LB is, for example, about 80% of its maximum luminance.

[0101]

number

[0102] The above formula (5) means that the position coordinates of the first pixel 50G1 are included within the radius r of the blue light LB. In other words, the timing indicated by the above formula (5) means the timing when the actual spot SP1 of the blue light LB overlaps at least a part of the first pixel 50G1, as shown in FIG.

[0103] After calculating the timing of dimming control and the dimming amount in step S3, the control device CONT proceeds to step S4. In step S4, the control unit CONT determines whether there are multiple pixels to be light-modulated. That is, the control unit CONT calculates the number of first pixels 50G1 included in the first area A1 of the image forming area 50.

[0104] If there are multiple first pixels 50G1 (step S4: YES), the control device CONT proceeds to step S5.

[0105] In step S5, the control device CONT determines the order in which to perform dimming control on the first pixels 50G1. Specifically, the control device CONT rearranges the order in which to perform dimming control on the first pixels 50G1 to match the order in which the blue light LB scanning over the image forming area 50 passes through each of the first pixels 50G1, and then proceeds to step S6.

[0106] In step S6, the control unit CONT performs dimming control to turn on the first light source unit 101, which emits blue light LB, at a timing that overlaps with each first pixel 50G1, according to the dimming order set in step S5, and then proceeds to step S7.

[0107] If there is one first pixel 50G1 (step S4: No), the control device CONT skips step S5 and proceeds to step S6, where it performs dimming control to turn on the first light source unit 101, which emits blue light LB, at the timing that overlaps with one first pixel 50G1, and then proceeds to step S7.

[0108] In step S7, the control device CONT determines whether or not there is a next image frame. If there is a next image frame (step S7: YES), the control device CONT returns to step S1 and repeats steps S1 to S6. That is, when the image information is made up of multiple image frames, the control device CONT performs dimming control by repeating the above processes each time an image frame is read. Specifically, the control device CONT performs dimming control on the first pixel 50G1 included in the image frame for all image frames each time an image frame is read sequentially. Then, the control device CONT ends the dimming control after completing each process for all image frames.

[0109] The control device CONT also performs the same process for controlling the dimming of the green light LG and the red light LR incident on the second light modulation element 30G and the third light modulation element 30R as for controlling the dimming of the blue light LB incident on the first light modulation element 30B.

[0110] In this way, in dimming control, the control device CONT controls the output of the first light source unit 101 based on blue image information to adjust the amount of blue light LB incident on the dimming target pixel of the first light modulation element 30B, controls the output of the second light source unit 102 based on green image information to adjust the amount of green light LG incident on the dimming target pixel of the second light modulation element 30G, and controls the output of the third light source unit 103 based on red image information to adjust the amount of red light LR incident on the dimming target pixel of the third light modulation element 30R. Each of the light modulation elements 30B, 30G, and 30R may adjust the modulation degree of each image forming area based on the brightness of each color light LB, LG, and LR adjusted by dimming control, thereby generating image light of a desired color, thereby displaying a higher quality image.

[0111] As described above, the projector 200 of this embodiment includes the light source unit 10 that emits illumination light WL, the first transmissive optical element 13 that has a first incident surface onto which the illumination light WL emitted from the light source unit 10 is incident and a first exit surface from which the light incident from the first incident surface exits, the first rotating element 15 that rotates the first transmissive optical element 13, the light modulation device 30 that modulates the illumination light WL emitted from the first transmissive optical element 13 based on image information to generate image light, and the control device CONT that controls the output of the light source unit 10. The light modulation device 30 has an image forming area 50 including a plurality of pixels 50G. The first transmissive optical element 13 is a light-transmitting member whose first incident surface and first exit surface are parallel to each other. The first transmissive optical element 13 rotates about a first rotation axis C1 that extends along the Y-axis direction that intersects with the X-axis direction, which is the direction in which the illumination light WL is incident on the first transmissive optical element 13, thereby scanning the illumination light WL emitted from the light source unit 10 over the image forming area 50 of the light modulation device 30. The control device CONT selects a first pixel 50G1 from among the multiple pixels 50G based on image information, and performs dimming control to adjust the amount of illumination light WL incident on the first pixel 50G1 by reducing the output of the light source unit 10 when the brightness value corresponding to the first pixel 50G1 in the image light is smaller than the dimming reference value at a timing that satisfies the following formula, where the position coordinates of the first pixel 50G1 in the image forming area 50 are (px, py), the radius of the illumination light WL in the scanning direction on the image forming area 50 is r, and the position coordinates of the illumination light WL on the image forming area 50 at time t are (dx(t), dy(t)).

number

[0112] According to the projector 200 of this embodiment, the control device CONT adjusts the intensity of the colored light LB, LG, and LR emitted from the light source units 101, 102, and 103 toward the first pixel 50G1 based on image information, thereby reducing the amount of light blocked by the exit-side polarizing plates 32B, 32G, and 32R arranged after the light modulation elements 30B, 30G, and 30R. This improves the light utilization efficiency of the colored light LB, LG, and LR emitted from the light source units 101, 102, and 103. Therefore, according to the projector 200 of this embodiment, it is possible to achieve low power consumption in each of the light source units 101, 102, and 103 and also to realize a projector with excellent display quality.

[0113] Furthermore, the reduction in light absorbed by the exit-side polarizing plates 32B, 32G, and 32R reduces the load on the exit-side polarizing plates 32B, 32G, and 32R, which is expected to improve the reliability of the exit-side polarizing plates 32B, 32G, and 32R and improve contrast by using polarizing plates made of organic materials.

[0114] Furthermore, according to the projector 200 of this embodiment, it is possible to illuminate the image forming area 50 of the light modulation elements 30B, 30G, and 30R in a substantially rectangular shape without using an optical system for shaping light into a rectangular shape, such as a multi-lens. Therefore, it is possible to make the overall optical path length relatively short, and by reducing the number of optical components, it is possible to reduce the number of interfaces between the optical system and air, thereby reducing light loss due to interface reflection.

[0115] Although the present embodiment has exemplified the case where square-shaped light-transmitting members are used as the first and second light-transmitting optical elements 13 and 14, it is also possible to use light-transmitting optical elements having a cross-sectional shape with a regular octagon or more, in which the number of sides is an even number of eight or more. With this configuration, even when a material having a general refractive index is used as the light-transmitting member, the linearity of the displacement amount of each of the color lights LB, LG, and LR can be improved, and therefore the uniformity of the illuminance distribution within the image formation region 50 of each of the light modulation elements 30B, 30G, and 30R can be more simply improved.

[0116] (First Modification) 2, the control device CONT may include an image processing unit CON0. The image processing unit CON0 performs predetermined image processing on image information input from the outside. The image processing unit CON0 performs image processing to correct the image information input from the outside to information corresponding to a display mode selected by a user, for example. Examples of display modes include "dynamic mode" suitable for viewing in bright environments, "living room mode" suitable for viewing in dim light, "natural mode" capable of reproducing images faithful to the input signal in dark environments, "theater mode" suitable for watching movies in dark environments, etc. For example, "dynamic mode" is a brightness-oriented mode that prioritizes image brightness over image color tone.

[0117] In this case, it is desirable that the control device CONT calculates the amount of light of each color to be incident on the first pixel 50G1 of the image forming area 50 of each light modulation element 30B, 30G, 30R, based on image information after image processing by the image processing unit CON0. According to this configuration, the control device CONT controls the dimming of each color light scanning over the image forming area 50 based on image information corresponding to the display mode, so that a high-quality image suitable for the display mode can be displayed.

[0118] (Second Modification) In the first embodiment, the dimming reference value is a black display pixel, the dimming target pixel is a white display pixel, and dimming control is performed by turning on the light source unit according to the timing when the dimming target pixel passes, but the present invention is not limited to this. For example, the dimming reference value may be a white display pixel, the dimming target pixel is a black display pixel, and dimming control may be performed by turning off the light source unit according to the timing when the dimming target pixel passes. According to this configuration, light is not incident on the light-modulation target pixel that displays black, so that the incident light is blocked at the light-modulation target pixel, and a decrease in the light utilization efficiency of the light source unit can be suppressed.

[0119] When the light source unit 10 is turned off in response to the timing of passing through a dimming target pixel, for example, assume that a dimming target pixel PG exists at the boundary between adjacent scan lines of incident light L, as shown in FIG. 12 . In this case, two adjacent spots of the dimming target pixel PG are turned off, and an area twice the radius r of the spot of the irradiated light is displayed in black. Therefore, when dimming control is performed to turn off the light source unit 10 so that light is not incident on the dimming target pixel PG that is displaying black, the area A affected by dimming overlaps with an area twice the radius r (2r) of the spot of the incident light L. In other words, in this modified example, the control device CONT can perform dimming control when the area A, which is the maximum range 2r affected by dimming, is entirely a black display area. This is because if a white display area is included in the area A affected by dimming, a display defect in the white display area will occur.

[0120] The present invention can also be applied to cases where the dimming reference value is set to an intermediate gradation between black and white display, and pixels with a brightness value higher than the intermediate gradation are selected as dimming target pixels, or pixels with a brightness value lower than the intermediate gradation are selected as dimming target pixels.

[0121] (Second embodiment) A second embodiment of the present invention will be described below with reference to the drawings. The projector of this embodiment differs from the projector of the first embodiment in that light from a light source unit is scanned on one light modulation element by a first transmissive optical element 13. Note that the same reference numerals are used for the same components as in the first embodiment, and detailed descriptions thereof will be omitted.

[0122] FIG. 13 is a plan view showing a schematic configuration of a projector 202 of this embodiment. As shown in FIG. 13, a projector 202 of this embodiment includes a light source device 110, a light modulation device 130, and a projection optical device 23.

[0123] The light source device 110 of this embodiment includes a first light source section 111, a second light source section 112, a third light source section 113, a first transmissive optical element 13, a first rotating element 15, a first optical element 16a, and a second optical element 16b.

[0124] The first light source unit 111 emits blue light LB toward the first transmissive optical element 13 (-Z side). The second light source unit 112 emits green light LG toward the first transmissive optical element 13 (+X side). The third light source unit 113 emits red light LR toward the first transmissive optical element 13 (+Z side).

[0125] The optical axis AX1 of the first light source unit 111 and the optical axis AX3 of the third light source unit 113 are positioned on the same axis. The optical axis AX2 of the second light source unit 112 is perpendicular to the optical axis AX1 of the first light source unit 111 and the optical axis AX3 of the third light source unit 113, and coincides with the optical axis AX of the light source device 110. With this configuration, for example, if each light source unit is equipped with a cooling member such as a heat sink, it is not necessary to arrange the cooling member, the flow path for cooling air, etc. at an angle. This increases the degree of freedom in the layout of the components that make up the projector 202, and enables the projector 202 to be made more compact.

[0126] Although the light source units 111, 112, and 113 have the same basic configuration, the specific configuration of the second light source unit 112 will be described below with reference to Fig. 14. In Fig. 14, the first light source unit 111, the third light source unit 113, the first optical element 16a, the second optical element 16b, etc. are not shown.

[0127] 14, the second light source unit 112 has a plurality of second light-emitting elements 26 and a substrate 29. The plurality of second light-emitting elements 26 are arranged in a row along the Y-axis direction at predetermined intervals. In the present embodiment, the second light source unit 112 includes five second light-emitting elements 26, but the number of second light-emitting elements 26 is not particularly limited as long as the plurality of second light-emitting elements 26 are arranged in a row along the Y-axis direction.

[0128] Based on this configuration, the green light LG emitted from the second light source unit 112 is composed of a light beam including multiple light rays LG0 aligned along the Y-axis direction, and therefore has a band-like shape with a major axis extending along the Y-axis direction and a minor axis extending along the Z-axis direction.

[0129] Similarly, the first light source unit 101 has a plurality of first light-emitting elements 25 and a substrate 29. The plurality of first light-emitting elements 25 are arranged in a row along the Y-axis direction at predetermined intervals. The third light source unit 113 has a plurality of third light-emitting elements 27 and a substrate 29. The plurality of third light-emitting elements 27 are arranged in a row along the Y-axis direction at predetermined intervals.

[0130] Based on this configuration, the blue light LB emitted from the first light source unit 111 is composed of a light flux including multiple light rays aligned along the Y-axis direction, and therefore has a belt-like shape with a major axis extending along the Y-axis direction and a minor axis extending along the X-axis direction. Also, the red light LR emitted from the third light source unit 113 is composed of a light flux including multiple light rays aligned along the Y-axis direction, and therefore has a belt-like shape with a major axis extending along the Y-axis direction and a minor axis extending along the X-axis direction.

[0131] 13, the first transmissive optical element 13 is provided at a position where the optical axis AX1 and the optical axis AX3 intersect with the optical axis AX2. The first transmissive optical element 13 rotates about a first rotation axis C1 by being driven by the first rotating element 15.

[0132] The first transmissive optical element 13 transmits the blue light LB, green light LG, and red light LR emitted from the light source units 111, 112, and 113, respectively, while rotating about a first rotation axis C1.

[0133] The blue light LB is incident on the first transmissive optical element 13 at a first position P11. The green light LG is incident on the first transmissive optical element 13 at a second position P12 different from the first position P11. The red light LR is incident on the first transmissive optical element 13 at a third position P13 different from the first position P11 and the second position P12. That is, the blue light LB, the green light LG, and the red light LR are incident on different positions on the first transmissive optical element 13. In particular, in the case of this embodiment, the first light source unit 101, the second light source unit 112, and the third light source unit 113 are rotated 90 degrees around the intersection of the optical axis AX1, the optical axis AX3, and the optical axis AX2. Therefore, the blue light LB, the green light LG, and the red light LR are incident on different first side surfaces 13c of the first transmissive optical element 13.

[0134] The behavior of each of the color lights LB, LG, and LR when passing through the first transmission optical element 13 is the same as the behavior shown in FIGS. 4A to 4F, and therefore a description thereof will be omitted.

[0135] In this embodiment, the green light LG extends linearly in the Y-axis direction, which is perpendicular to the Z-axis direction along which the green light LG is displaced. Therefore, the green light LG is scanned within a two-dimensional illuminated area on the illuminated surface (light modulation device 130). Although the blue light LB and the red light LR have different emission directions from the green light LG, they are reflected by the optical elements 16a and 16b (described later) and then scanned within the two-dimensional illuminated area on the illuminated surface (light modulation device 130) in the same manner as the green light LG. In this way, when the first transmissive optical element 13 rotates around the first rotation axis C1, it scans each of the blue light LB, green light LG, and red light LR in the Z-axis direction, which is perpendicular to the Y-axis direction, thereby scanning within the two-dimensional illuminated area on the illuminated surface, i.e., the light modulation device 130.

[0136] FIG. 15 is a diagram showing the state of light scanning on the light modulation device 130. In the present embodiment, as shown in FIG. 13, for example, a strip of green light LG scans the light modulation device 130 in one direction along the vertical direction y. Therefore, in the above equation (5) that defines the timing of dimming control for the dimming target pixel, the coordinates px, dx(t) in the left-right direction x always match. Therefore, in the present embodiment, the term px-dx(t) in the above equation (5) always becomes 0. Note that the blue light LB and the red light LR are also scanned in one direction along the up-down direction y on the light modulation device 130 in the same way.

[0137] Therefore, in this embodiment, the control device CONT only needs to perform dimming control on the dimming target pixel at a timing that satisfies the following formula (6).

[0138]

number

[0139] In other words, in this embodiment, the control device CONT only needs to consider the coordinate in the up-down direction y along which each color light LB, LG, and LR scans, making the dimming control process easier than when considering coordinates in two directions, the left-right direction x and the up-down direction y.

[0140] The first optical element 16a is provided on the optical path of the blue light LB emitted from the first light source unit 101 between the first light source unit 101 and the first transmissive optical element 13. The first optical element 16a is composed of a dichroic mirror that reflects red light and transmits blue light. Therefore, the first optical element 16a reflects the red light LR emitted from the first transmissive optical element 13 and transmits the blue light LB emitted from the first light source unit 101. The angle formed by the first optical element 16a and the Z axis is referred to as the tilt angle θ11 of the first optical element 16a. The tilt angle θ11 of the first optical element 16a is greater than 45 degrees.

[0141] The second optical element 16b is provided on the optical path of the red light LR emitted from the third light source unit 113 between the third light source unit 113 and the first transmissive optical element 13. The second optical element 16b is composed of a dichroic mirror that reflects blue light and transmits red light. Therefore, the second optical element 16b reflects the blue light LB emitted from the first transmissive optical element 13 and transmits the red light LR emitted from the third light source unit 113. The angle formed by the second optical element 16b and the Z axis is referred to as the tilt angle θ12 of the second optical element 16b. The tilt angle θ12 of the second optical element 16b is greater than 45 degrees.

[0142] Since the tilt angle θ12 of the second optical element 16b is set to be greater than 45 degrees, the blue light LB reflected by the second optical element 16b travels obliquely with respect to the optical axis AX2 so as to approach the optical axis AX2. Similarly, since the tilt angle θ11 of the first optical element 16a is set to be greater than 45 degrees, the red light LR reflected by the first optical element 16a travels obliquely with respect to the optical axis AX2 so as to approach the optical axis AX2.

[0143] As a result, the blue light LB reflected by the second optical element 16b, the green light LG emitted from the first transmissive optical element 13, and the red light LR reflected by the first optical element 16a are incident on the first microlens array 43, which is located upstream of the light modulation element 131, from different directions and overlap on the first microlens array 43, as will be described later. In this embodiment, the angle of incidence of the green light LG with respect to the first microlens array 43 is 0 degrees. In other words, the green light LG is incident perpendicularly on the first microlens array 43.

[0144] The light modulation device 130 of this embodiment includes a light modulation element 131 and an exit-side polarizing plate 132 . Fig. 16 is a cross-sectional view showing the configuration of the main part of a light modulation device 130 of this embodiment. Fig. 16 shows the cross-sectional configuration of a light modulation element 131, and does not show the exit-side polarizing plate 132. As shown in FIG. 16, the liquid crystal panel constituting the light modulation element 131 has an image formation region 150 in which a plurality of blue subpixels PX1, a plurality of green subpixels PX2, and a plurality of red subpixels PX3 are periodically arranged in a matrix. The blue subpixel PX1 modulates blue light LB. The green subpixel PX2 modulates green light LG. The red subpixel PX3 modulates red light LR. One pixel, which is the smallest unit of an image, is composed of one blue subpixel PX1, one green subpixel PX2, and one red subpixel PX3. A light-shielding film 155 called a black matrix is ​​provided between two adjacent subpixels.

[0145] The first microlens array 43 is provided on the light incident side of the first substrate 57 that constitutes the light modulation element 131. The first microlens array 43 has a configuration in which a plurality of first microlenses 431 are arranged in a matrix. The first microlens array 43 collects each of the blue light LB, green light LG, and red light LR and guides them to the sub-pixels PX1, PX2, and PX3 of the light modulation element 131. Each first microlens 431 is formed of a lenticular lens and is arranged across one pixel, i.e., across three sub-pixels PX1, PX2, and PX3 of different colors that are aligned in one direction. In this embodiment, the first microlens 431 is a lenticular lens, but is not limited to this. Alternatively, a microlens in which rectangular lenses are arranged in a brick-like configuration, a microlens in which lenses are arranged to correspond to sub-pixels in a delta arrangement, or a microlens array with a honeycomb structure may also be used.

[0146] As described above, the blue light LB, green light LG, and red light LR are incident on the first microlens 431 at different incident angles, and therefore travel in different directions and are collected. As a result, the blue light LB is incident on the blue subpixel PX1, the green light LG is incident on the green subpixel PX2, and the red light LR is incident on the red subpixel PX3. That is, the first microlens array 43 causes the blue light LB emitted from the second reflecting element to be incident on the blue subpixel PX1, the green light LG emitted from the transmissive optical element to be incident on the green subpixel PX2, and the red light LR emitted from the first reflecting element to be incident on the red subpixel PX3.

[0147] The second microlens array 44 is provided on the light emission side of the second substrate 158 that constitutes the light modulation element 131. The second microlens array 44 has a configuration in which a plurality of second microlenses 441 are arranged in a matrix. The second microlens array 44 collimates each color light emitted from the liquid crystal panel. The second microlens 441 is provided for each sub-pixel. Note that in the present embodiment, an example has been given in which each color light is collimated after it has been emitted from the liquid crystal panel. However, instead of this configuration, the second microlens array 44 may be disposed on the light incidence side of the liquid crystal panel, and each color light may be collimated before it enters the liquid crystal panel.

[0148] The exit-side polarizing plate 22 is provided on the optical axis AX2 between the light modulation element 131 and the projection optical device 23. The exit-side polarizing plate 22 transmits linearly polarized light in a specific direction that is exited from the light modulation element 131 toward the projection optical device 23.

[0149] According to the projector 202 of this embodiment, the control device CONT adjusts the output of each light source unit 111, 112, 113 based on image information to dim each color light LB, LG, LR that illuminates the illuminated area (the dimming target pixel of the light modulation element 131), thereby achieving the same effect as in the first embodiment, such as improving the light utilization efficiency of the light source device 110 and realizing low power consumption.

[0150] Furthermore, in the projector 202 of this embodiment, the arrangement of the light sources 111, 112, and 113, the first transmissive optical element 13, and the optical elements 16a and 16b, together with the action of the first microlens array 43 provided in the light modulation device 130, spatially separates the three colored lights LB, LG, and LR, and allows each of the colored lights LB, LG, and LR to be incident on the corresponding sub-pixels PX1, PX2, and PX3. This makes it possible to realize the projector 202 capable of displaying color images without using a color filter in the light modulation element 131 of the light modulation device 130. Furthermore, by scanning the colored lights LB, LG, and LR, each of which has a major axis in the Y-axis direction, in the Z-axis direction, the illuminated area of ​​the light modulation device 130 can be illuminated two-dimensionally. This allows only one transmissive optical element to be required, thereby simplifying and miniaturizing the device configuration.

[0151] 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, in the first embodiment, the illumination light WL obtained by combining the color lights LB, LG, and LR passes through the first transmissive optical element 13 and the second transmissive optical element 14, and then undergoes color separation to scan the light modulation elements 30B, 30G, and 30R, but the present invention is not limited to this. For example, the present invention may be applied to a configuration in which the color lights LB, LG, and LR pass through the first transmissive optical element 13 and the second transmissive optical element 14, respectively, and then scan the light modulation elements 30B, 30G, and 30R.

[0152] In the second embodiment, the color light beams LB, LG, and LR are incident on one transmissive optical element from different directions, and the color light beams LB, LG, and LR are incident on one liquid crystal panel from three directions. However, the present invention is not limited to this. For example, the present invention may be applied to a configuration having three transmissive optical elements corresponding to the strip-shaped color light beams LB, LG, and LR, and three light modulation elements corresponding to the three transmissive optical elements, and scanning the light modulation elements with the color light beams LB, LG, and LR emitted from the respective transmissive optical elements.

[0153] In addition, the specific descriptions of the shape, number, arrangement, materials, etc. of each component of the light source device and the projector are not limited to the above-described embodiment and can be modified as appropriate. Furthermore, in the above-described embodiment, an example was shown in which the light source device according to the present invention is mounted on a projector using a liquid crystal panel, but this is not limiting. The light source device according to the present invention may also be applied to a projector using a digital micromirror device as a light modulation device.

[0154] A summary of this disclosure is provided below. (Appendix 1) a light source unit that emits light; a first transmissive optical element having a first incident surface onto which the light emitted from the light source unit is incident and a first exit surface from which the light incident from the first incident surface exits; a first rotating element that rotates the first transmissive optical element; a light modulation device that modulates the light emitted from the first transmissive optical element based on image information to generate image light; a control device for controlling the output of the light source unit, the light modulation device has an image forming area including a plurality of pixels; the first transmissive optical element is a light-transmitting member in which the first incident surface and the first exit surface are parallel to each other, and rotates about a first rotation axis extending along a second direction intersecting a first direction that is an incident direction of the light to the first transmissive optical element, thereby scanning the light emitted from the light source unit over the image forming area of ​​the light modulation device; The control device selecting a pixel to be light-modulated from among the plurality of pixels based on the image information; When the position coordinates of the light-modulating pixel in the image forming area are (px, py), the radius of the light on the image forming area in the scanning direction is r, and the position coordinates of the light on the image forming area at time t are (dx(t), dy(t)), When the following condition is met: When a luminance value corresponding to the light-modulating target pixel in the image light is smaller than a light-modulating reference value, an output of the light source unit is reduced; When the luminance value is greater than the dimming reference value, the output of the light source unit is increased to adjust the amount of light incident on the dimming target pixel, thereby performing dimming control. projector.

number

[0155] With this projector, the control device adjusts the light emitted from the light source unit toward the dimming target pixel based on image information, thereby reducing the amount of light blocked by the light modulation device, thereby improving the light utilization efficiency of the light emitted from the light source unit. Therefore, with this configuration, it is possible to realize a projector that has low power consumption and excellent display quality.

[0156] (Appendix 2) When a plurality of light-modulation target pixels are set from among the plurality of pixels, the control device performs the light-modulation control in accordance with the order in which the light scanning the image forming area passes through the plurality of light-modulation target pixels. 1. The projector according to claim 1.

[0157] According to this configuration, light adjustment control can be performed at an appropriate timing when the light passes through each pixel to be light adjusted.

[0158] (Appendix 3) the image information is composed of a plurality of image frames; the control device performs the light adjustment control in accordance with timings at which the plurality of image frames are input to the light modulation device, respectively. 1. The projector according to claim 1 or 2.

[0159] According to this configuration, it is possible to perform light adjustment control for each of the multiple image frames that make up the image information.

[0160] (Appendix 4) the first transmissive optical element has a first surface and a second surface intersecting the first rotation axis, and 2×m (m: a natural number equal to or greater than 2) first side surfaces in contact with the first surface and the second surface, The first entrance surface and the first exit surface are two of the 2×m first side surfaces that are parallel to each other. 10. The projector according to claim 1, wherein the projector is a

[0161] According to this configuration, there is no light incident on the first side surfaces that are not parallel to each other, so that the generation of stray light in the first transmissive optical element is small, and light utilization efficiency can be improved.

[0162] (Appendix 5) the first transmissive optical element has a square cross section taken along a plane perpendicular to the first rotation axis, The refractive index of the first transmissive optical element is 1.63 or more. 1. The projector according to claim 4.

[0163] According to this configuration, the coefficient of determination of the graph showing the relationship between the rotation angle and the displacement amount of the first transmissive optical element is 0.995 or more. Therefore, by improving the linearity of the graph, it is possible to improve the uniformity of the illuminance distribution of light in the illuminated area.

[0164] (Appendix 6) the first transmissive optical element has a cross-sectional shape taken along a plane perpendicular to the first rotation axis that is a regular hexagon; The refractive index of the first transmissive optical element is 1.14 or more. 1. The projector according to claim 4.

[0165] With this configuration, the coefficient of determination of the graph showing the relationship between the rotation angle and the displacement amount of the first transmissive optical element is 0.995 or more. Therefore, by increasing the linearity of the graph while keeping the refractive index of the first transmissive optical element low, it is possible to improve the uniformity of the illuminance distribution of light in the illuminated area.

[0166] (Appendix 7) the first transmissive optical element has a cross-sectional shape taken along a plane perpendicular to the first rotation axis that is a regular polygon having eight or more sides; 1. The projector according to claim 4.

[0167] With this configuration, the linearity of the graph can be sufficiently improved even when the refractive index of the first transmissive optical element is set within a general range of 1 to 2.73. Therefore, restrictions on the refractive index of the first transmissive optical element are reduced, which widens the range of materials that can be used as the first transmissive optical element and makes the optical design of the first transmissive optical element easier.

[0168] (Appendix 8) The light source unit includes a light emitting element formed of a laser diode that emits laser light. 8. The projector according to claim 1, wherein the projector is a

[0169] According to this configuration, since the light emitted from the light source section is linearly polarized laser light, when a liquid crystal panel is used as the light modulation device, for example, the incident side polarizing plate can be omitted.

[0170] (Appendix 9) the control device further controls driving of the first rotating element and the light modulation device. 9. The projector according to any one of claims 1 to 8.

[0171] According to this configuration, the dimming control of the light source unit, the drive control of the first rotating element, and the drive control of the light modulation device are all controlled by the control device, which enables simple and highly accurate control.

[0172] (Appendix 10) the control device includes an image processing unit that performs predetermined image processing on the image information, calculating the amount of light to be incident on the light-modulating target pixel based on image information after image processing by the image processing unit; 10. The projector according to any one of claims 1 to 9.

[0173] According to this configuration, the control device controls the dimming of the light that scans the image forming area based on image information corresponding to the display mode, for example, so that a high-quality image that is more suitable for the display mode can be displayed.

[0174] (Appendix 11) a second transmissive optical element having a second entrance surface onto which the light is incident and a second exit surface from which the light incident from the second entrance surface exits; a second rotating element that rotates the second transmissive optical element, the second transmissive optical element is a light-transmitting member in which the second entrance surface and the second exit surface are parallel to each other, and rotates about a second rotation axis extending along a third direction intersecting the first direction and the second direction; the second rotating element rotates the second transmissive optical element about the second rotation axis, thereby scanning the light two-dimensionally over the image forming area of ​​the light modulation device; 11. The projector according to claim 1.

[0175] According to this configuration, by two-dimensionally scanning light on the image forming area using the first transmissive optical element and the second transmissive optical element, it is possible to easily realize a configuration in which the entire image forming area is illuminated.

[0176] (Appendix 12) the second transmissive optical element has a third surface and a fourth surface intersecting the second rotation axis, and 2×n (n: a natural number equal to or greater than 2) second side surfaces tangent to the third surface and the fourth surface, The second entrance surface and the second exit surface are two second side surfaces parallel to each other among the 2×n second side surfaces. 12. The projector of claim 11.

[0177] According to this configuration, there is no light incident on the second side surfaces that are not parallel to each other, so that the generation of stray light in the second transmissive optical element is small, and light utilization efficiency can be improved.

[0178] (Appendix 13) The light source unit is a first light source unit that emits first light in a first wavelength band; a second light source unit that emits second light in a second wavelength band different from the first wavelength band; a third light source unit that emits third light in a third wavelength band different from the first wavelength band and the second wavelength band, The optical modulation device a first light modulation element that modulates the first light emitted from the first transmissive optical element based on first image information to generate first image light; a second light modulation element that modulates the second light emitted from the first transmission optical element based on second image information to generate second image light; a third light modulation element that modulates the third light emitted from the first transmissive optical element based on third image information to generate third image light, In the light adjustment control, the control device controls an output of the first light source unit to adjust the amount of the first light incident on the light-adjustment target pixel of the first light modulation element based on the first image information, controls an output of the second light source unit to adjust the amount of the second light incident on the light-adjustment target pixel of the second light modulation element based on the second image information, and controls an output of the third light source unit to adjust the amount of the third light incident on the light-adjustment target pixel of the third light modulation element based on the third image information. 12. The projector according to claim 1.

[0179] According to this configuration, the light emitted from each of the first, second, and third light source units toward the dimming target pixels of the first, second, and third light modulation elements is dimmed, so the amount of light blocked by each light modulation element can be reduced, thereby improving the light utilization efficiency of the light emitted from the first, second, and third light source units. Therefore, it is possible to realize a three-panel projector that has low power consumption and excellent display quality. [Explanation of symbols]

[0180] 4, 6, 8, 10, 12, n...positive, 10, 101, 111...light source unit, 13...first transmissive optical element, 13a...first surface, 13b...second surface, 13c, 13c1, 13c2, 13c3, 13c4...first side surface, 14...second transmissive optical element, 15...first rotating element, 16...second rotating element, 16a...optical element, 18...transmissive optical element, 18a...first incident surface, 18b...first exit surface, 25...light emitting element, 30, 130...light modulation device, 30B, 131...light modulation element, 30B...first light modulation element, 30G...second light modulation element, 30R...third light modulation element, 50, 150...image forming area, 50G...pixel , 101,111...first light source unit, 102,112...second light source unit, 103,113...third light source unit, 200,202...projector, 50G1...first pixel, 50G1...first image, 50G2...second pixel, C1...first rotation axis, C2...second rotation axis, CONT...control device, CON0...image processing unit, n1,n2...refractive index, O...rotation axis, PG...pixel to be dimmed, px...coordinates, r...radius, t...time, B...blue image light (first image light), G...green image light (second image light), R...red image light (third image light), LB...blue light (first light), LG...green light (second light), LR...red light (third light).

Claims

1. a light source unit that emits light; a first transmissive optical element having a first incident surface onto which the light emitted from the light source unit is incident and a first exit surface from which the light incident from the first incident surface exits; a first rotating element that rotates the first transmissive optical element; a light modulation device that modulates the light emitted from the first transmissive optical element based on image information to generate image light; a control device for controlling the output of the light source unit, the light modulation device has an image forming area including a plurality of pixels; the first transmissive optical element has the first incident surface and the first exit surface parallel to each other, and rotates about a first rotation axis extending along a second direction intersecting a first direction that is an incident direction of the light to the first transmissive optical element, thereby scanning the light emitted from the light source unit over the image forming area of ​​the light modulation device; The control device selecting a pixel to be light-modulated from among the plurality of pixels based on the image information; When the position coordinates of the light-modulating target pixel in the image forming area are (px, py), the radius of the light on the image forming area in the scanning direction is r, and the position coordinates of the light on the image forming area at time t are (dx(t), dy(t)), When the following condition is met: When a luminance value corresponding to the light-modulating target pixel in the image light is smaller than a light-modulating reference value, an output of the light source unit is reduced; When the luminance value is greater than the dimming reference value, the output of the light source unit is increased to adjust the amount of light incident on the dimming target pixel, thereby performing dimming control. projector. [Equation 1]

2. When a plurality of light-modulation target pixels are set from among the plurality of pixels, the control device performs the light-modulation control in accordance with the order in which the light scanning the image forming area passes through the plurality of light-modulation target pixels. The projector according to claim 1 .

3. the image information is composed of a plurality of image frames; the control device performs the light adjustment control in accordance with timings at which the plurality of image frames are input to the light modulation device, respectively. The projector according to claim 1 .

4. the first transmissive optical element has a first surface and a second surface intersecting the first rotation axis, and 2×m (m: a natural number equal to or greater than 2) first side surfaces tangent to the first surface and the second surface, The first entrance surface and the first exit surface are two first side surfaces parallel to each other among the 2×m first side surfaces. The projector according to claim 1 .

5. the first transmissive optical element has a square cross section taken along a plane perpendicular to the first rotation axis, The refractive index of the first transmissive optical element is 1.63 or more. The projector according to claim 4 .

6. the first transmissive optical element has a cross-sectional shape taken along a plane perpendicular to the first rotation axis that is a regular hexagon; The refractive index of the first transmissive optical element is 1.14 or more. The projector according to claim 4 .

7. the first transmissive optical element has a cross-sectional shape taken along a plane perpendicular to the first rotation axis that is a regular polygon having eight or more sides; The projector according to claim 4 .

8. The light source unit includes a light emitting element formed of a laser diode that emits laser light. The projector according to claim 1 .

9. the control device further controls driving of the first rotating element and the light modulation device. The projector according to claim 1 .

10. the control device includes an image processing unit that performs predetermined image processing on the image information, calculating the amount of light to be incident on the light-modulating target pixel based on image information after image processing by the image processing unit; The projector according to claim 1 .

11. a second transmissive optical element having a second entrance surface onto which the light is incident and a second exit surface from which the light incident from the second entrance surface exits; a second rotating element that rotates the second transmissive optical element, the second transmissive optical element is a light-transmitting member in which the second entrance surface and the second exit surface are parallel to each other, and rotates about a second rotation axis extending along a third direction intersecting the first direction and the second direction, the second rotating element rotates the second transmissive optical element about the second rotation axis, thereby scanning the light two-dimensionally over the image forming area of ​​the light modulation device; The projector according to claim 1 .

12. the second transmissive optical element has a third surface and a fourth surface intersecting the second rotation axis, and 2×n (n: a natural number equal to or greater than 2) second side surfaces tangent to the third surface and the fourth surface, The second entrance surface and the second exit surface are two second side surfaces parallel to each other among the 2×n second side surfaces. The projector according to claim 11.

13. The light source unit is a first light source unit that emits first light in a first wavelength band; a second light source unit that emits second light in a second wavelength band different from the first wavelength band; a third light source unit that emits third light in a third wavelength band different from the first wavelength band and the second wavelength band, The optical modulation device a first light modulation element that modulates the first light emitted from the first transmissive optical element based on first image information to generate first image light; a second light modulation element that modulates the second light emitted from the first transmission optical element based on second image information to generate second image light; a third light modulation element that modulates the third light emitted from the first transmissive optical element based on third image information to generate third image light, In the light adjustment control, the control device controls an output of the first light source unit to adjust the amount of the first light incident on the light adjustment target pixel of the first light modulation element based on the first image information, controls an output of the second light source unit to adjust the amount of the second light incident on the light adjustment target pixel of the second light modulation element based on the second image information, and controls an output of the third light source unit to adjust the amount of the third light incident on the light adjustment target pixel of the third light modulation element based on the third image information. The projector according to claim 1 .

Images