Optical modules and projectors

Abstract

The present invention provides an optical module and projector that enable miniaturization of the device configuration when employing an illumination optical system that scans the illumination light. [Solution] The optical module of the present invention comprises a light source that emits light, an optical scanning unit that periodically scans the light emitted from the light source, and an image light generation unit that generates image light from the scanning light scanned by the optical scanning unit. The optical scanning unit has a diffractive optical element whose diffraction angle of light differs depending on the position of light incidence from the light source, and a moving mechanism that moves the diffractive optical element. The scanning light scans the illumination area of ​​the image light generation unit as the diffractive optical element moves.

Description

Technical Field

[0001] The present invention relates to an optical module and a projector.

Background Art

[0002] As a light source device used in a projector, there has been proposed a light source device that illuminates a light modulation device by temporally scanning light emitted from a light emitting element on the light modulation device such as a liquid crystal panel.

[0003] Patent Document 1 below discloses a projector including 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 light beam cross section. The polygon mirror reflects the light emitted from the light source device and scans in the short-axis direction of the elliptical light beam cross section on the image formation region of the liquid crystal light valve.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the above projector, since a configuration in which illumination light is scanned using a polygon mirror is adopted, there is a problem that the device configuration becomes large.

Means for Solving the Problems

[0006] To solve the above problems, according to one aspect of the present invention, an optical module is provided comprising: a light source that emits light; an optical scanning unit that periodically scans the light emitted from the light source; and an image light generation unit that generates image light from the scanning light scanned by the optical scanning unit, wherein the optical scanning unit has a diffractive optical element whose diffraction angle of the light differs depending on the position of light incidence from the light source, and a moving mechanism that moves the diffractive optical element, and the scanning light scans the illumination area of ​​the image light generation unit as the diffractive optical element moves.

[0007] Furthermore, according to another aspect of the present invention, a projector is provided comprising an optical module as described above and a projection optical device that projects light emitted from the optical module. [Brief explanation of the drawing]

[0008] [Figure 1] This is a plan view showing the schematic configuration of the projector according to the first embodiment. [Figure 2] This is a cross-sectional view showing the schematic configuration of the first optical scanning unit. [Figure 3A] This figure shows the behavior of the blue illumination light produced by the first optical scanning unit. [Figure 3B] This figure shows the behavior of the blue illumination light produced by the first optical scanning unit. [Figure 3C] This figure shows the behavior of the blue illumination light produced by the first optical scanning unit. [Figure 3D] This figure shows the behavior of the blue illumination light produced by the first optical scanning unit. [Figure 3E] This figure shows the behavior of the blue illumination light produced by the first optical scanning unit. [Figure 4] This is a timing chart showing the correspondence between the liquid crystal panel and the first optical scanning unit. [Figure 5A] This is a plan view of the first optical scanning unit of the modified example, viewed in the Z-axis direction. [Figure 5B] This is a plan view of the first optical scanning unit of a modified example, viewed in the X-axis direction. [Figure 6]This is a cross-sectional view showing the schematic configuration of the blue light imaging module of the second embodiment. [Figure 7A] This figure shows the behavior of the blue illumination light emitted from the first optical scanning unit. [Figure 7B] This figure shows the behavior of the blue illumination light emitted from the first optical scanning unit. [Figure 7C] This figure shows the behavior of the blue illumination light emitted from the first optical scanning unit. [Figure 7D] This figure shows the behavior of the blue illumination light emitted from the first optical scanning unit. [Figure 7E] This figure shows the behavior of the blue illumination light emitted from the first optical scanning unit. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described below with reference to the drawings. In the following drawings, the dimensions of each component may be shown on a different scale to make them easier to see.

[0010] Figure 1 is a plan view showing the schematic configuration of the projector according to this embodiment. As shown in Figure 1, the projector 1 of this embodiment comprises a blue light image module (optical module) 2B, a green light image module (optical module) 2G, a red light image module (optical module) 2R, an image synthesis element 3, and a projection optical device 4. In this embodiment, the blue light image module 2B, the green light image module 2G, and the red light image module 2R each correspond to the "optical module" of the present invention.

[0011] The blue light image module 2B includes a first light source 11B, a first light scanning unit 12B, and a first image light generation unit 13B. The first light source 11B includes, for example, a laser light emitting element that emits blue light LB in a blue wavelength band of 450 nm ± 5 nm. The first light scanning unit 12B periodically scans the blue light LB emitted from the first light source 11B. The details of the configuration of the first light scanning unit 12B will be described later. The details of the configuration of the second light scanning unit 12G will be described later. In the present embodiment, the first light source 11B, the first light scanning unit 12B, and the first image light generation unit 13B respectively correspond to the "light source", "light scanning unit", and "image light generation unit" of the present invention.

[0012] The first image light generation unit 13B generates blue image light from the scanning light scanned by the first light scanning unit 12B. The first image light generation unit 13B includes a liquid crystal panel 14B and an emission-side polarizing plate 15B. The liquid crystal panel 14B includes an image formation region 140 that modulates the blue light LB scanned by the first light scanning unit 12B according to image information to form blue image light. As the driving method of the liquid crystal panel 14B, a twisted nematic (TN) method, a vertical alignment (VA) method, an in-plane switching (IPS) method, etc. are used, and it is not particularly limited.

[0013] The green light image module 2G includes a second light source 11G, a second light scanning unit 12G, and a second image light generation unit 13G. The second light source 11G includes, for example, a laser light emitting element that emits green light LG in a green wavelength band of 530 nm ± 5 nm. The second light scanning unit 12G periodically scans the green light LG emitted from the second light source 11G. The details of the configuration of the second light scanning unit 12G will be described later. In the present embodiment, the second light source 11G, the second light scanning unit 12G, and the second image light generation unit 13G respectively correspond to the "light source", "light scanning unit", and "image light generation unit" of the present invention.

[0014] The second image light generation unit 13G generates green image light from the scanning light scanned by the second light scanning unit 12G. The second image light generation unit 13G includes a liquid crystal panel 14G and an emission side polarizing plate 15G. The liquid crystal panel 14G includes an image formation region 141 that modulates the green light LG scanned by the second light scanning unit 12G according to image information to form green image light. As the driving method of the liquid crystal panel 14G, a twisted nematic (TN) method, a vertical alignment (VA) method, an in-plane switching (IPS) method, etc. are used, and it is not particularly limited.

[0015] The red light image module 2R includes a third light source 11R, a third light scanning unit 12R, and a third image light generation unit 13R. The third light source 11R includes a laser light emitting element that emits red light LR in a red wavelength band of, for example, 650 nm ± 5 nm. The third light scanning unit 12R periodically scans the red light LR emitted from the third light source 11R. The details of the configuration of the third light scanning unit 12R will be described later. In the present embodiment, the second light source 11G, the second light scanning unit 12G, and the second image light generation unit 13G respectively correspond to the "light source", "light scanning unit", and "image light generation unit" of the present invention.

[0016] The third image light generation unit 13R generates red image light from the scanning light scanned by the third light scanning unit 12R. The third image light generation unit 13R includes a liquid crystal panel 14R and an emission side polarizing plate 15R. The liquid crystal panel 14R includes an image formation region 142 that modulates the red light LR scanned by the third light scanning unit 12R according to image information to form red image light. As the driving method of the liquid crystal panel 14R, a twisted nematic (TN) method, a vertical alignment (VA) method, an in-plane switching (IPS) method, etc. are used, and it is not particularly limited.

[0017] The image synthesizing element 3 emits full-color image light synthesized from the image lights of respective colors emitted from the first image light generation unit 13B, the second image light generation unit 13G, and the third image light generation unit 13R toward the projection optical device 4. For example, a cross dichroic prism is used for the image synthesizing element 3.

[0018] The projection optical device 4 is composed of multiple projection lenses. The projection optical device 4 magnifies and projects the image light emitted from the image synthesis element 3 toward a projection surface such as a screen. As a result, a full-color image is displayed on the projection surface.

[0019] Next, the configurations of the first optical scanning unit 12B, the second optical scanning unit 12G, and the third optical scanning unit 12R will be described. The first optical scanning unit 12B, the second optical scanning unit 12G, and the third optical scanning unit 12R have similar configurations except for the color of the light they scan. Therefore, in the following, the configuration of the first optical scanning unit 12B will be used as an example, and the configurations of the second optical scanning unit 12G and the third optical scanning unit 12R will be omitted or simplified.

[0020] In the following explanation, the XYZ Cartesian coordinate system will be used in the diagrams as needed. The X-axis is parallel to the optical axis AX1 of the blue light image module 2B. Optical axis AX1 is the axis along the principal ray of the blue light LB emitted from the first light source 11B. The Y-axis is perpendicular to the X-axis and is parallel to the optical axis AX2 of the green light image module 2G. Optical axis AX2 is the axis along the principal ray of the green light LG emitted from the second light source 11G. The Z-axis is perpendicular to the X and Y axes. The optical axis AX3 of the red light image module 2R coincides with the optical axis AX1 of the blue light image module 2B.

[0021] Figure 2 is a cross-sectional view showing the schematic configuration of the first optical scanning unit 12B. Figure 2 is a cross-sectional view of the first optical scanning unit 12B in the XZ plane. In Figure 2, the liquid crystal panel 14B, which is the object to be illuminated by the first optical scanning unit 12B, is shown, and the incident position of the blue light LB on the diffractive optical element 21 is varied.

[0022] As shown in Figure 2, the first optical scanning unit 12B includes a diffractive optical element 21 and a moving mechanism 31. Specifically, the diffractive optical element 21 in this embodiment is a computer-generated hologram (CGH). The diffractive optical element 21 is made of a material that is transparent to blue light LB. Examples of such materials include quartz, optical glass, and transparent resin.

[0023] The diffraction angle of the diffractive optical element 21 varies depending on the position of the incident light. Since the diffractive optical element 21 is composed of a computer-generated hologram, the diffraction angle of light can be controlled with high precision. As a result, the diffractive optical element 21 can concentrate the light that has passed through it onto the central axis 21A of the diffractive optical element 21 by diffracting it at an angle corresponding to the incident position. More specifically, as shown in Figure 2, when the central axis 21A of the diffractive optical element 21 is positioned on the optical axis AX1, the blue light LB transmitted through the diffractive optical element 21 is focused on the optical axis AX1 regardless of the incident position on the diffractive optical element 21. Therefore, the blue light LB transmitted through the diffractive optical element 21 illuminates the center of the liquid crystal panel 14B located on the optical axis AX1 as blue illumination light LB1, as shown in Figure 2, regardless of the incident position. Note that the illumination position of the liquid crystal panel 14B by the blue illumination light LB1 changes depending on the position of the diffractive optical element 21 relative to the liquid crystal panel 14B, as will be described later.

[0024] The blue illumination light LB1 that illuminates the liquid crystal panel 14B is a band-shaped light extending in the Y-axis direction. Specifically, the cross-sectional shape perpendicular to the principal ray of the blue illumination light LB1 is rectangular, having a longitudinal side along the Y-axis direction and a transverse side along the Z-axis direction. The longitudinal side of the blue illumination light LB1 is equal to or greater than the Y-axis width of the rectangular image-forming region 140 of the liquid crystal panel 14B. The transverse side of the blue illumination light LB1 is smaller than the Z-axis width of the rectangular image-forming region 140 of the liquid crystal panel 14B.

[0025] The moving mechanism 31 is a drive device that moves the diffractive optical element 21, and is composed of, for example, an actuator. The blue illumination light LB1 scans the first image light generation unit 13B as the diffractive optical element 21 moves due to the moving mechanism 31. In this embodiment, the blue illumination light LB1 corresponds to an example of the "scanning light" of the present invention.

[0026] The moving mechanism 31 is capable of reciprocating the diffractive optical element 21 in the Z-axis direction. In other words, the moving mechanism 31 is capable of moving the diffractive optical element 21 in both the -Z and +Z directions relative to the liquid crystal panel 14B. In this embodiment, the direction of movement of the diffractive optical element 21 by the moving mechanism 31 is the Z-axis direction along the short side of the blue illumination light LB1. The blue illumination light LB1 scans the liquid crystal panel 14B in the Z-axis direction along the short side. With this configuration, by scanning the elongated blue illumination light LB1 in the short-side direction, the image forming area 140 can be illuminated efficiently while suppressing the increase in the short-side dimension of the blue illumination light LB1 compared to scanning the blue illumination light LB1 in the longitudinal direction. In this embodiment, the Z-axis direction corresponds to the "axis direction" of the present invention, the -Z side of the Z-axis direction corresponds to the "one side of the axis direction" of the present invention, and the +Z side of the Z-axis direction corresponds to the "one side of the axis direction" of the present invention.

[0027] Figures 3A to 3E illustrate the behavior of the blue illumination light LB1 emitted from the first optical scanning unit 12B. Figures 3A to 3E show the case where the diffractive optical element 21 moves from the +Z side to the -Z side with respect to the optical axis AX1. In Figures 3A to 3E, the left side shows the displacement of the blue illumination light LB1 from the optical axis AX1, and the right side illustrates how the blue illumination light LB1 scans the image forming area 140 of the liquid crystal panel 14B, which is the illuminated area. In the explanation using Figures 3A to 3E, the +Z side may be referred to as the upper side and the -Z side as the lower end.

[0028] In the state shown in Figure 3A, the diffractive optical element 21 is positioned such that its lower end on the -Z side lies on the optical axis AX1. Therefore, in the Z-axis direction, the lower end of the diffractive optical element 21 is located in the center of the liquid crystal panel 14B, and the central axis 21A of the diffractive optical element 21 is located at the upper end 140a on the +Z side of the image forming region 140 of the liquid crystal panel 14B.

[0029] As described above, the blue light LB that passes through the diffractive optical element 21 is incident on the liquid crystal panel 14B as blue illumination light LB1 that is focused on the central axis 21A of the diffractive optical element 21. Therefore, in the state shown in Figure 3A, the blue illumination light LB1 illuminates the upper end portion 140a of the image forming region 140.

[0030] Next, as shown in Figure 3B, when the diffractive optical element 21 moves downward (-Z side) by the movement mechanism 31, the central axis 21A of the diffractive optical element 21 also moves downward (-Z side), narrowing the distance between the central axis 21A and the optical axis AX1. As a result, the central axis 21A of the diffractive optical element 21 moves below (-Z side) the upper edge 140a of the image forming region 140 of the liquid crystal panel 14B, so the blue illumination light LB1 illuminates below (-Z side) the upper edge 140a of the image forming region 140.

[0031] Next, as shown in Figure 3C, when the diffractive optical element 21 moves further downward (towards the -Z side) by the movement mechanism 31, the central axis 21A of the diffractive optical element 21 coincides with the optical axis AX1. At this time, the central axis 21A of the diffractive optical element 21 coincides with the central part 140c of the image forming region 140 of the liquid crystal panel 14B, and the blue illumination light LB1 illuminates the central part 140c of the image forming region 140.

[0032] Next, as shown in Figure 3D, when the diffractive optical element 21 moves further downward (towards the -Z side) by the movement mechanism 31, the central axis 21A of the diffractive optical element 21 moves downward (towards the -Z side) from the optical axis AX1, increasing the distance between the central axis 21A and the optical axis AX1. As a result, the central axis 21A of the diffractive optical element 21 moves downward (towards the -Z side) from the center 140c of the image forming region 140 of the liquid crystal panel 14B, and the blue illumination light LB1 illuminates the area below the center 140c of the image forming region 140 (towards the -Z side).

[0033] Next, as the diffractive optical element 21 moves further downward (towards the -Z side) by the movement mechanism 31, the central axis 21A of the diffractive optical element 21 is located at the lower end 140b on the -Z side of the image forming region 140 of the liquid crystal panel 14B, as shown in Figure 3E. Therefore, in the state shown in Figure 3E, the blue illumination light LB1 illuminates the lower end 140b of the image forming region 140.

[0034] In this way, the first optical scanning unit 12B can scan the blue illumination light LB1 from top to bottom within the image forming region 140 of the liquid crystal panel 14B by moving the diffractive optical element 21 from top to bottom using the moving mechanism 31. Therefore, the first optical scanning unit 12B can illuminate the entire rectangular image forming region 140 with the blue illumination light LB1.

[0035] Next, we will explain the temporal correspondence between the driving timing of the liquid crystal panel 14B and the scanning timing of the blue illumination light LB1 by the first optical scanning unit 12B. Figure 4 is a timing chart showing the temporal correspondence between the liquid crystal panel 14B and the first optical scanning unit 12B.

[0036] In Figure 4, E1 to E5 show the correspondence between the rotational efficiency at each position in the vertical direction (Z-axis direction) of the image forming region 140 of the liquid crystal panel 14B. Here, the rotational efficiency of the liquid crystal panel 14B refers to the rate at which linearly polarized light incident on the liquid crystal layer is converted to linearly polarized light orthogonal to that linear polarization.

[0037] Specifically, position E1 corresponds to the upper end 140a of the image forming region 140, position E5 corresponds to the lower end 140b of the image forming region 140, position E3 corresponds to the central part 140c of the image forming region 140, position E2 corresponds to the area between the upper end 140a and the central part 140c of the image forming region 140, and position E4 corresponds to the area between the central part 140c and the lower end 140b of the image forming region 140.

[0038] In Figure 4, ST indicates the scanning period during which the blue illumination light LB1 scans the image forming region 140. In other words, during the scanning period ST, the first light source 11B is in the state of illuminating the blue light LB.

[0039] As shown in Figure 4, the liquid crystal panel 14B generates image light in the image forming region 140 by sequentially selecting multiple scan lines using a scan line driving circuit (not shown). This process of sequentially selecting multiple scan lines by the scan line driving circuit is called "vertical scanning," and the direction in which the scan lines are sequentially scanned by the vertical scanning of the scan line driving circuit is called the "vertical scanning direction." In the liquid crystal panel 14B of this embodiment, the Z-axis direction in which positions E1 to E5 in the image forming region 140 are aligned corresponds to vertical scanning. In this embodiment, the vertical scanning direction of the liquid crystal panel 14G is the same as the direction in which the blue illumination light LB1 scans the image forming region 140 as the diffractive optical element 21 moves downward (-Z side).

[0040] With this configuration, by aligning the scanning direction of the blue illumination light LB1 with the vertical scanning direction of the liquid crystal panel 14G, the scanning of the blue illumination light LB1 can be started before the vertical scanning of the image forming region 140 is completed. Therefore, the acceleration of the diffractive optical element 21 by the moving mechanism 31 can be reduced compared to when the scanning of the blue illumination light LB1 is started after the completion of the vertical scanning, thereby reducing the load on the moving mechanism 31, reducing the risk of damage or failure, and also reducing the power consumption of the moving mechanism 31.

[0041] Because the vertical scanning direction of the image forming region 140 is from the +Z side to the -Z side, the timing at which the rotation efficiency reaches 100% at each position E1 to E5 is staggered. In other words, position E1, which is located furthest upstream in the vertical scanning direction, reaches 100% rotation efficiency the earliest, while position E5, which is located furthest downstream in the vertical scanning direction, reaches 100% rotation efficiency the latest.

[0042] In this embodiment, when the rotation efficiency at each position E1 to E5 of the image forming region 140 reaches 100%, a scanning period ST is started in which the blue illumination light LB1 is scanned over the image forming region 140. As a result, the image forming region 140 can efficiently modulate the blue illumination light LB1 to generate image light of the desired brightness.

[0043] Furthermore, in Figure 4, T1 represents the vertical scanning period of the liquid crystal panel 14B, and T2 represents the scanning period of the blue illumination light LB1 by the first optical scanning unit 12B. In this embodiment, for example, T1 is 1 / 240 s and T2 is 1 / 480 s, so the vertical scanning period T1 is twice the scanning period T2.

[0044] In this embodiment, the blue illumination light LB1 is scanned within the image forming region 140 by moving the diffractive optical element 21 from top to bottom within one frame of the liquid crystal panel 14B as described above. Therefore, after the blue illumination light LB1 scans the image forming region 140 from top to bottom once, it is necessary to return the diffractive optical element 21 to the top again. For this reason, the first optical scanning unit 12B needs to move the diffractive optical element 21 back and forth within one frame of the liquid crystal panel 14B.

[0045] Here, we consider the state of the first light source 11B when the diffractive optical element 21 is returned to the upper position. For example, if the diffractive optical element 21 is moved upward while the first light source 11B remains lit, the blue illumination light LB1 will scan in the reverse direction from position E5 to position E1 in the image forming region 140 at the timing indicated by the dashed arrow in Figure 4. However, at the timing when the blue illumination light LB1 passes position E5 in the image forming region 140, position E5 is in the state before switching to display for the next frame, and at the timing when the blue illumination light LB1 passes position E4 in the image forming region 140, the rotation efficiency of position E4 has not reached 100%, so the blue illumination light LB1 cannot be modulated properly, which may lead to a decrease in image quality due to modulation failure.

[0046] In contrast, in the blue light image module 2B of this embodiment, the first light source 11B is turned on while the diffractive optical element 21 is moving downward (-Z side) in the first optical scanning unit 12B, and turned off while the diffractive optical element 21 is moving upward (+Z side). This suppresses the power consumption of the first light source 11B while also preventing a decrease in image quality due to poor modulation of the blue illumination light LB1 by the liquid crystal panel 14B when its rotation efficiency is insufficient.

[0047] As described above, the blue light image module 2B of this embodiment includes a first light source 11B that emits blue light LB, a first optical scanning unit 12B that periodically scans the blue light LB emitted from the first light source 11B, and a first image light generation unit 13B that generates image light from the blue illumination light LB1 scanned by the first optical scanning unit 12B. The first optical scanning unit 12B has a diffractive optical element 21 with a diffraction angle that differs depending on the light incidence position, and a moving mechanism 31 that moves the diffractive optical element 21. The blue illumination light LB1 scans the liquid crystal panel 14B of the first image light generation unit 13B as the diffractive optical element 21 moves.

[0048] According to the blue light image module 2B of this embodiment, by moving the diffractive optical element 21 into which the blue light LB emitted from the first light source 11B is incident, the device configuration can be made smaller compared to the conventional configuration that scans the illumination light using a polygon mirror, while still allowing the blue illumination light LB1 to be scanned on the liquid crystal panel 14B. Therefore, bright and high-quality image light can be generated on the liquid crystal panel 14B.

[0049] In the above explanation, the configuration of the first optical scanning unit 12B of the blue light image module 2B was used as an example, but the second optical scanning unit 12G of the green light image module 2G and the third optical scanning unit 12R of the red light image module 2R have the same configuration as the first optical scanning unit 12B.

[0050] The second optical scanning unit 12G includes a diffractive optical element 22 and a moving mechanism 32. According to the green light image module 2G of this embodiment, the diffractive optical element 22 is moved by the moving mechanism 32 of the second optical scanning unit 12G, thereby enabling scanning of the green illumination light LG1 on the image forming area 141 of the liquid crystal panel 14G while suppressing an increase in the size of the device configuration. Therefore, bright and high-quality image light can be generated on the liquid crystal panel 14G.

[0051] Furthermore, in this embodiment, the green light image module 2G lights up the second light source 11G while the diffractive optical element 22 is moving downward (-Z side) in the second optical scanning unit 12G, and turns it off while the diffractive optical element 22 is moving upward (+Z side). With this configuration, the power consumption of the second light source 11G can be reduced while suppressing the deterioration of image quality due to modulation defects of the green illumination light LG1 by the liquid crystal panel 14G.

[0052] Furthermore, the third optical scanning unit 12R includes a diffractive optical element 23 and a moving mechanism 33. According to the red light image module 2R of this embodiment, the diffractive optical element 23 is moved by the moving mechanism 33 of the third optical scanning unit 12R, thereby enabling scanning of the red illumination light LR1 on the image forming area 142 of the liquid crystal panel 14R while suppressing an increase in the size of the device configuration. As a result, bright and high-quality image light can be generated on the liquid crystal panel 14R.

[0053] Furthermore, in this embodiment, the red light image module 2R lights up the third light source 11R while the diffractive optical element 23 is moving downward (-Z side) in the third optical scanning unit 12R, and turns it off while the diffractive optical element 23 is moving upward (+Z side). With this configuration, the power consumption of the third light source 11R can be reduced while suppressing the deterioration of image quality due to modulation defects of the red illumination light LR1 by the liquid crystal panel 14R.

[0054] Furthermore, the projector 1 of this embodiment includes a blue light image module 2B, a green light image module 2G, and a red light image module 2R, and a projection optical device 4 that projects the image light of each color emitted from the blue light image module 2B, the green light image module 2G, and the red light image module 2R.

[0055] According to the projector 1 of this embodiment, it is possible to realize a projector that projects high-quality images while suppressing an increase in the size of the device configuration.

[0056] (modified version) Next, a modified example of the projector according to the above embodiment will be described. The difference between this modified example and the above embodiment lies in the configuration of the optical scanning unit of each image module. The first optical scanning unit will be used as an example below, but the same applies to the second and third optical scanning units.

[0057] Figure 5A is a plan view showing the schematic configuration of the first optical scanning unit 112B of this modified example. Figure 5A is a view of the first optical scanning unit 112B from the +Z side. Figure 5B is a plan view of the first optical scanning unit 112B of this modified example viewed in the X-axis direction along the optical axis AX1.

[0058] As shown in Figure 5A, the first optical scanning unit 112B includes a diffractive optical element 121 and a moving mechanism 40. In this modified example, the moving mechanism 40 includes a disk 120 and a rotation drive unit 130. The disk 120 is a translucent substrate that supports the diffractive optical element 121. The diffractive optical element 121 is arranged along the circumferential direction of the disk 120. That is, the diffractive optical element 121 is provided in an annular shape around the rotation axis O. The rotation drive unit 130 is composed of, for example, a motor, and rotates the disk 120 about the rotation axis O.

[0059] As shown in Figure 5B, the first optical scanning unit 112B is positioned such that a portion of the diffractive optical element 121 overlaps with the optical axis AX1. In this modified example, the first optical scanning unit 112B moves relative to the blue light LB by rotating the disk 120. As a result, the incident position of the blue light LB on the diffractive optical element 121 changes.

[0060] According to this modified example, as shown in Figure 5B, the rotation of the disc 120 causes the diffractive optical element 121 to move to the +Z side with respect to the optical axis AX1. Therefore, similar to the above embodiment, the blue illumination light LB1 transmitted through the diffractive optical element 121 can be scanned to the -Y side on the image forming area 140 of the liquid crystal panel 14B.

[0061] In this modified example, the diffractive optical element 121 may be formed in a ring shape in the circumferential direction of the disk 120, or it may be a structure divided into multiple parts in the circumferential direction of the disk 120. In this modified example, the first light source 11B may be turned off to prevent blue light LB from entering the diffractive optical element 121 when the rotation efficiency of the liquid crystal panel 14B has not reached 100%, or the blue light LB may be blocked by a light-shielding member provided on the light-incident side of the diffractive optical element 121. Furthermore, in this modified example, the blue illumination light LB1 may scan the image forming region 140 once or multiple times while the disk 120 rotates once.

[0062] (Second Embodiment) Next, a projector according to the second embodiment will be described. The difference between this embodiment and the above embodiment lies in the configuration of each image module. The following description will use the blue light image module as an example, but the same applies to the green light image module and the red-blue light image module. In addition, the same reference numerals are used for components and configurations common to the above embodiment, and details are omitted or simplified.

[0063] Figure 6 is a cross-sectional view showing the schematic configuration of the blue light image module 102B of this embodiment. As shown in Figure 6, the blue light image module 102B comprises a first light source 111, a first optical scanning unit 210, and a first image light generation unit 13B. In this embodiment, the first light source 111 and the first optical scanning unit 210 correspond to the "light source" and "optical scanning unit" of the present invention, respectively.

[0064] The first light source 111 of this embodiment includes a first light-emitting element 111A, a second light-emitting element 111B, a third light-emitting element 111C, a fourth light-emitting element 111D, and a fifth light-emitting element 111E. Each light-emitting element 111A to 111E is arranged in this order in the direction from the +Z side to the -Z side, which is the scanning direction of the blue illumination light LB1.

[0065] The first optical scanning unit 210 includes a diffraction element unit 211 and a control unit CONT. The diffraction element unit 211 has a first diffractive optical element 210A, a second diffractive optical element 210B, a third diffractive optical element 210C, a fourth diffractive optical element 210D, and a fifth diffractive optical element 210E arranged in this order in the scanning direction of the blue illumination light LB1. Note that each of the diffractive optical elements 210A to 210D of the diffraction element unit 211 may be arranged with a gap in the Z-axis direction, or may be arranged in contact with each other. Each of the diffractive optical elements 210A to 210D of the diffraction element unit 211 is a computer-generated hologram (CGH) and diffracts the light incident from the corresponding light-emitting element.

[0066] In this embodiment, the image forming region 140 of the liquid crystal panel 14B includes a first illumination region 241, a second illumination region 242, a third illumination region 243, a fourth illumination region 244, and a fifth illumination region 245, which are aligned in the scanning direction of the blue illumination light LB1.

[0067] The first diffractive optical element 210A diffracts the blue light LB incident from the first light-emitting element 111A to illuminate the first illumination region 241 of the liquid crystal panel 14B. The central axis of the first diffractive optical element 210A coincides with the central axis of the first illumination region 241.

[0068] The second diffractive optical element 210B diffracts the blue light LB incident from the second light-emitting element 111B to illuminate the second illumination region 242 of the liquid crystal panel 14B. The central axis of the second diffractive optical element 210B coincides with the central axis of the second illumination region 242.

[0069] The third diffractive optical element 210C diffracts the blue light LB incident from the third light-emitting element 111C to illuminate the third illumination region 243 of the liquid crystal panel 14B. The central axis of the third diffractive optical element 210C coincides with the central axis of the third illumination region 243.

[0070] The fourth diffractive optical element 210D diffracts the blue light LB incident from the fourth light-emitting element 111D to illuminate the fourth illumination region 244 of the liquid crystal panel 14B. The central axis of the fourth diffractive optical element 210D coincides with the central axis of the fourth illumination region 244.

[0071] The fifth diffractive optical element 210E diffracts the blue light LB incident from the fifth light-emitting element 111E to illuminate the fifth illumination region 245 of the liquid crystal panel 14B. The central axis of the fifth diffractive optical element 210E coincides with the central axis of the fifth illumination region 245.

[0072] The control unit CONT is composed of a computer or integrated circuit that has a built-in program for controlling the driving of each light-emitting element 111A to 111E. In other words, the control unit CONT is, for example, a processor. The control unit CONT is connected to each light-emitting element 111A to 111E by wired or wireless means (not shown). In addition to the first light source 111, the control unit CONT may also control the driving of other components of the projector 1.

[0073] Figures 7A to 7E illustrate the behavior of the blue illumination light LB1 emitted from the first optical scanning unit 112B and incident on the liquid crystal panel 14B. Figures 7A to 7E sequentially show the process by which each light-emitting element 111A to 111E of the first light source 111 switches its lighting state from the +Z side to the -Z side. In Figures 7A to 7E, the left side shows the behavior of the blue illumination light LB1 as viewed from the -Y side, and the right side shows how the blue illumination light LB1 scans the image forming area 140 of the liquid crystal panel 14B, which is the illuminated area. In the explanation using Figures 7A to 7E, the +Z side may be referred to as the upper side and the -Z side as the lower end.

[0074] As shown in Figure 7A, the control unit CONT lights up only the first light-emitting element 111A of the first light source 111. The blue light LB emitted from the first light-emitting element 111A is incident on the first diffractive optical element 210A and illuminates the first illumination area 241 located at the uppermost end of the image forming area 140 as blue illumination light LB1.

[0075] Next, as shown in Figure 7B, the control unit CONT turns off the first light-emitting element 111A and lights up only the second light-emitting element 111B. The blue light LB emitted from the second light-emitting element 111B is incident on the second diffractive optical element 210B and illuminates the second illumination region 242 located below the first illumination region 241 as blue illumination light LB1.

[0076] Next, as shown in Figure 7C, the control unit CONT turns off the second light-emitting element 111B and lights up only the third light-emitting element 111C. The blue light LB emitted from the third light-emitting element 111C is incident on the third diffractive optical element 210C and illuminates the third illumination region 243, which is located below the second illumination region 242, as blue illumination light LB1.

[0077] Next, as shown in Figure 7D, the control unit CONT turns off the third light-emitting element 111C and lights up only the fourth light-emitting element 111D. The blue light LB emitted from the fourth light-emitting element 111D is incident on the fourth diffractive optical element 210D and illuminates the fourth illumination region 244, which is located below the third illumination region 243, as blue illumination light LB1.

[0078] Next, as shown in Figure 7E, the control unit CONT turns off the fourth light-emitting element 111D and lights up only the fifth light-emitting element 111E. The blue light LB emitted from the fifth light-emitting element 111E is incident on the fifth diffractive optical element 210E and illuminates the fifth illumination area 245, which is located below the fourth illumination area 244 and at the bottom of the image forming area 140, as blue illumination light LB1.

[0079] As described above, the blue light image module 2B of this embodiment includes a first light source 111 that emits blue light LB, a first optical scanning unit 210 that periodically scans the blue light LB emitted from the first light source 111, and a first image light generation unit 13B that generates image light from the blue illumination light LB1 scanned by the first optical scanning unit 210. The first light source 111 includes a first light-emitting element 111A, a second light-emitting element 111B, a third light-emitting element 111C, a fourth light-emitting element 111D, and a fifth light-emitting element 111E, which are arranged in line in the scanning direction of the blue light LB. The first optical scanning unit 210 includes a first diffracting optical element 210A that diffracts light incident from the first light-emitting element 111A to illuminate the first illumination area 241 of the first image light generation unit 13B, a second diffracting optical element 210B positioned in the scanning direction relative to the first diffracting optical element 210A that diffracts light incident from the second light-emitting element 111B to illuminate the second illumination area 242 of the first image light generation unit 13B, and a third diffracting optical element 210B positioned in the scanning direction relative to the second diffracting optical element 210B that diffracts light incident from the third light-emitting element 111C to illuminate the third illumination area 24 of the first image light generation unit 13B. The system includes a third diffractive optical element 210C that illuminates 3, a fourth diffractive optical element 210D positioned in the scanning direction relative to the third diffractive optical element 210C and diffracting light incident from the fourth light-emitting element 111D to illuminate the fourth illumination area 244 of the first image light generation unit 13B, a fifth diffractive optical element 210E positioned in the scanning direction relative to the fourth diffractive optical element 210D and diffracting light incident from the fifth light-emitting element 111E to illuminate the fifth illumination area 245 of the first image light generation unit 13B, and a control unit CONT that controls the driving of each light-emitting element 111A to 111E. The control unit CONT sequentially switches the illumination of each light-emitting element 111A to 111E, causing the blue light LB to illuminate each illumination area 241 to 245 in sequence.

[0080] According to the blue light image module 2B of this embodiment, blue light LB can be sequentially incident on each diffractive optical element 210A to 210E by switching the illumination of each light-emitting element 111A to 111E of the first light source 111. As a result, the blue illumination light LB1 emitted from each diffractive optical element 210A to 210E can scan each illumination area 241 to 245 of the image forming area 140 of the liquid crystal panel 14B from top to bottom. With this configuration, the device configuration can be made smaller compared to the conventional configuration that scans illumination light using a polygon mirror, while still allowing the blue illumination light LB1 to be scanned on the liquid crystal panel 14B. Therefore, bright and high-quality image light can be generated on the liquid crystal panel 14B.

[0081] In this embodiment, the number of light-emitting elements in the first light source 111, the number of diffractive optical elements arranged in correspondence with the light-emitting elements, and the number of illumination areas in the image forming area 140 are given as examples, but the invention is not limited to this. In the present invention, it is sufficient to set the number of light-emitting elements in the first light source 111 and the number of diffractive optical elements arranged in correspondence with the light-emitting elements to at least three or more.

[0082] In the above explanation, the configuration of the first optical scanning unit 210 of the blue light image module 102B was used as an example, but the second optical scanning unit of the green light image module and the third optical scanning unit of the red light image module have the same configuration as the first optical scanning unit 210. Therefore, according to the green light image module of this embodiment, by switching the illumination of each light-emitting element of the second light source, the green illumination light can be scanned over the image forming area of ​​the liquid crystal panel 14G while suppressing an increase in the size of the device configuration. Thus, bright and high-quality image light can be generated on the liquid crystal panel 14G. Furthermore, according to the red light image module of this embodiment, by switching the illumination of each light-emitting element of the third light source, it is possible to scan the red illumination light on the image forming area of ​​the liquid crystal panel 14R while suppressing an increase in the size of the device configuration. Therefore, bright and high-quality image light can be generated on the liquid crystal panel 14R.

[0083] Furthermore, according to the projector of this embodiment, by including the blue light image module 102B, a green light image module and a red light image module having the same configuration as the blue light image module 102B, it is possible to realize a projector that projects high-quality images while suppressing an increase in the size of the device configuration.

[0084] The technical scope of the present invention is not limited to the embodiments described above, and various modifications can be made without departing from the spirit of the invention. Furthermore, the specific details regarding the shape, number, arrangement, and materials of each component of the projector are not limited to the above embodiment and can be modified as appropriate.

[0085] A summary of this disclosure is provided below.

[0086] (Note 1) A light source that emits light, A light scanning unit that periodically scans the light emitted from the light source, The system includes an image light generation unit that generates image light from scanning light scanned by the optical scanning unit, The optical scanning unit is A diffractive optical element whose diffraction angle differs depending on the position of light incidence, It has a moving mechanism for moving the diffractive optical element, The scanning light scans the image light generation unit as the diffractive optical element moves. Optical module.

[0087] With this optical module configuration, by moving the diffractive optical element into which the light emitted from the light source is incident, the device configuration can be miniaturized compared to conventional configurations that scan illumination light using polygon mirrors, while still allowing scanning light to be scanned on the image light generation unit. Therefore, bright and high-quality image light can be generated in the image light generation unit.

[0088] (Note 2) The cross-sectional shape perpendicular to the principal ray of the scanning light is rectangular, having a long side and a short side. The scanning light scans the image light generation unit in a direction along the shorter side. The optical module described in Appendix 1.

[0089] With this configuration, by scanning the elongated scanning beam in the shorter direction, the image light generation unit can be efficiently illuminated while suppressing the increase in the shorter dimension of the scanning beam compared to scanning the scanning beam in the longitudinal direction.

[0090] (Note 3) The moving mechanism is capable of moving the diffractive optical element to one side in the axial direction and to the other side in the axial direction. The light source is turned on while the diffractive optical element is moving to one side in the axial direction, and turned off while the diffractive optical element is moving to the other side in the axial direction. The image light generation unit has a liquid crystal panel including an image forming region for generating the image light, The vertical scanning direction when generating the image light in the image forming region is the same as the direction in which the scanning light scans the image forming region as the diffractive optical element moves to one side in the axial direction. The optical module described in Appendix 1 or Appendix 2.

[0091] With this configuration, by aligning the scanning direction of the scanning light with the vertical scanning direction of the liquid crystal panel, the scanning of the scanning light can be started before the vertical scanning of the image forming area is completed. Therefore, the acceleration of the diffractive optical element by the moving mechanism can be reduced compared to when scanning is started after the completion of vertical scanning, thereby reducing the load on the moving mechanism, reducing the risk of damage or failure, and also reducing the power consumption of the moving mechanism.

[0092] (Note 4) The vertical scanning period of the liquid crystal panel is twice the scanning period of the scanning light by the optical scanning unit. The optical module described in Appendix 3.

[0093] This configuration allows for scanning of the scanning light across the image-forming region by moving the diffractive optical element from one side to the other within a single frame of the liquid crystal panel.

[0094] (Note 5) The diffractive optical element is a computer-generated hologram. The optical module described in any one of the appendices 1 through 4.

[0095] With this configuration, the diffraction angle of light can be controlled with high precision by a diffractive optical element composed of computer-generated holograms.

[0096] (Note 6) The moving mechanism comprises a light-transmitting disc that supports the diffractive optical element, and a rotational drive unit that rotates the disc. The diffractive optical element is arranged along the circumferential direction of the disk. The optical module described in any one of the appendices 1 through 5.

[0097] With this configuration, the rotation of the disk allows the diffractive optical element to be moved to one side relative to the optical axis of light. Therefore, the light that has passed through the diffractive optical element can be scanned in one direction on the image light generation unit.

[0098] (Note 7) A light source that emits light, A light scanning unit that periodically scans the light emitted from the light source, The system includes an image light generation unit that generates image light from scanning light scanned by the optical scanning unit, The light source includes a first light-emitting element, a second light-emitting element, and a third light-emitting element arranged in the scanning direction of the scanning light, The optical scanning unit is A first diffractive optical element that diffracts light incident from the first light-emitting element to illuminate the first illumination region of the image light generation unit, A second diffractive optical element is positioned in the scanning direction relative to the first diffractive optical element and diffracts light incident from the second light-emitting element to illuminate the second illumination area of ​​the image light generation unit, A third diffractive optical element is positioned in the scanning direction relative to the second diffractive optical element and diffracts the light incident from the third light-emitting element to illuminate the third illumination region of the image light generation unit, Includes a control unit that controls the driving of the first light-emitting element, the second light-emitting element, and the third light-emitting element, The control unit sequentially switches the illumination of the first light-emitting element, the second light-emitting element, and the third light-emitting element so that the scanning light illuminates the first illumination area, the second illumination area, and the third illumination area in sequence. Optical module.

[0099] With this optical module configuration, light can be sequentially incident on each diffractive optical element by switching the illumination of each light-emitting element in the light source. This allows the light emitted from each diffractive optical element to sequentially scan each illumination area of ​​the image light generation unit. Therefore, this configuration allows for a smaller device configuration compared to conventional configurations that use polygon mirrors to scan illumination light, while still enabling scanning light to be scanned on the image light generation unit. As a result, bright and high-quality image light can be generated in the image light generation unit.

[0100] (Note 8) An optical module described in any one of the appendices 1 through 7, The system comprises a projection optical device that projects light emitted from the optical module, projector.

[0101] This projector configuration makes it possible to create a projector that projects high-quality images while keeping the overall size of the device down. [Explanation of Symbols]

[0102] 1…Projector, 2B…Blue light image module (optical module), 2G…Green light image module (optical module), 2R…Red light image module (optical module), 4…Projection optical device, 13B…First image light generation unit (image light generation unit), 11B…First light source (light source), 11G…Second light source (light source), 11R…Third light source (light source), 13G…Second image light generation unit (image light generation unit), 13R…Third image light generation unit (image light generation unit), 14B,14G,14R…Liquid crystal panel, 21,22,23,120 ,121,210A...Diffractive optical elements, 31,32,33,40...Moving mechanism, 111A...First light-emitting element, 111A...Light-emitting element, 111B...Second light-emitting element, 111C...Third light-emitting element, 120...Disk, 130...Rotation drive unit, 140,141,142...Image forming area, 210A...First diffractive optical element, 210B...Second diffractive optical element, 210C...Third diffractive optical element, 241...Illumination area, 241...First illumination area, 242...Second illumination area, 243...Third illumination area, LB1...Blue illumination light (scanning light), CONT...Control unit.

Claims

1. A light source that emits light, A light scanning unit that periodically scans the light emitted from the light source, The system includes an image light generation unit that generates image light from scanning light scanned by the optical scanning unit, The optical scanning unit is A diffractive optical element whose diffraction angle differs depending on the position of light incidence, It has a moving mechanism for moving the diffractive optical element, The scanning light scans the image light generation unit as the diffractive optical element moves. Optical module.

2. The cross-sectional shape perpendicular to the principal ray of the scanning light is rectangular, having a long side and a short side. The scanning light scans the image light generation unit in a direction along the shorter side. The optical module according to claim 1.

3. The moving mechanism is capable of moving the diffractive optical element to one side in the axial direction and to the other side in the axial direction. The light source is turned on while the diffractive optical element is moving to one side in the axial direction, and turned off while the diffractive optical element is moving to the other side in the axial direction. The image light generation unit has a liquid crystal panel including an image forming region for generating the image light, The vertical scanning direction when generating the image light in the image forming region is the same as the direction in which the scanning light scans the image forming region as the diffractive optical element moves to one side in the axial direction. The optical module according to claim 1.

4. The vertical scanning period of the liquid crystal panel is twice the scanning period of the scanning light by the optical scanning unit. The optical module according to claim 3.

5. The diffractive optical element is a computer-generated hologram. The optical module according to claim 1.

6. The moving mechanism comprises a light-transmitting disc that supports the diffractive optical element, and a rotational drive unit that rotates the disc. The diffractive optical element is arranged along the circumferential direction of the disk. The optical module according to claim 1.

7. A light source that emits light, A light scanning unit that periodically scans the light emitted from the light source, The system includes an image light generation unit that generates image light from scanning light scanned by the optical scanning unit, The light source includes a first light-emitting element, a second light-emitting element, and a third light-emitting element arranged in the scanning direction of the scanning light, The optical scanning unit is A first diffractive optical element that diffracts light incident from the first light-emitting element to illuminate the first illumination region of the image light generation unit, A second diffractive optical element is positioned in the scanning direction relative to the first diffractive optical element and diffracts light incident from the second light-emitting element to illuminate the second illumination area of ​​the image light generation unit, A third diffractive optical element is positioned in the scanning direction relative to the second diffractive optical element and diffracts the light incident from the third light-emitting element to illuminate the third illumination region of the image light generation unit, Includes a control unit that controls the driving of the first light-emitting element, the second light-emitting element, and the third light-emitting element, The control unit sequentially switches the illumination of the first light-emitting element, the second light-emitting element, and the third light-emitting element so that the scanning light illuminates the first illumination area, the second illumination area, and the third illumination area in sequence. Optical module.

8. An optical module according to any one of claims 1 to 7, The system comprises a projection optical device that projects light emitted from the optical module, projector.

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