Optical module and projector

Abstract

The invention provides an optical module and a projector, which can miniaturize the device structure under the condition that an illumination optical system for scanning illumination light is adopted. This optical module is provided with: a light source that emits light; a light scanning unit that periodically scans the light emitted from the light source; and an image light generation unit that generates image light on the basis of scanning light scanned by the light scanning unit, the light scanning unit having: a diffractive optical element in which the diffraction angle of the light varies depending on the incident position of the light from the light source; and a movement mechanism that moves the diffractive optical element, the scanning light being moved by the diffractive optical element and scanning the illumination region of the image light generation unit.

Description

Technical Field

[0001] This disclosure relates to optical modules and projectors. Background Technology

[0002] As a light source device for projectors, a light source device is proposed that illuminates a light modulation device by scanning light emitted from a light-emitting element on a light modulation device such as a liquid crystal panel over time.

[0003] Patent Document 1 discloses a projector comprising a light source device including a light source lamp, a liquid crystal light valve, a multifaceted mirror disposed 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 multifaceted mirror reflects the light emitted from the light source device, scanning along the minor axis of the elliptical beam cross-section on the image forming area of ​​the liquid crystal light valve.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2007-225956

[0005] In the aforementioned projector, the use of a multi-faceted mirror to scan the illumination light presents the challenge of increasing the size of the device structure. Summary of the Invention

[0006] To address the aforementioned issues, according to one aspect of the present invention, an optical module is provided, comprising: a light source that emits light; a light scanning unit that periodically scans the light emitted from the light source; and an image light generating unit that generates image light based on the scanning light scanned by the light scanning unit, the light scanning unit comprising: a diffractive optical element whose diffraction angle varies depending on the light incident position; and a moving mechanism that moves the diffractive optical element, the scanning light scanning the image light generating unit by the movement of the diffractive optical element.

[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. Attached Figure Description

[0008] Figure 1 This is a top view showing the schematic structure of the projector according to the first embodiment.

[0009] Figure 2 This is a cross-sectional view showing the general structure of the first optical scanning section.

[0010] Figure 3A This is a diagram showing the operation of the blue illumination light in the first optical scanning section.

[0011] Figure 3B This is a diagram showing the operation of the blue illumination light in the first optical scanning section.

[0012] Figure 3C This is a diagram showing the operation of the blue illumination light in the first optical scanning section.

[0013] Figure 3D This is a diagram showing the operation of the blue illumination light in the first optical scanning section.

[0014] Figure 3E This is a diagram showing the operation of the blue illumination light in the first optical scanning section.

[0015] Figure 4 It is a timing diagram showing the correspondence between the liquid crystal panel and the first optical scanning unit.

[0016] Figure 5A This is a top view of the first optical scanning section of the deformed example observed along the Z-axis.

[0017] Figure 5B This is a top view of the first optical scanning section of the deformed example observed along the X-axis.

[0018] Figure 6 This is a cross-sectional view showing the schematic structure of the blue light image module of the second embodiment.

[0019] Figure 7A This diagram illustrates the movement of the blue illumination light emitted from the first optical scanning unit.

[0020] Figure 7B This diagram illustrates the movement of the blue illumination light emitted from the first optical scanning unit.

[0021] Figure 7C This diagram illustrates the movement of the blue illumination light emitted from the first optical scanning unit.

[0022] Figure 7D This diagram illustrates the movement of the blue illumination light emitted from the first optical scanning unit.

[0023] Figure 7E This diagram illustrates the movement of the blue illumination light emitted from the first optical scanning unit.

[0024] Label Explanation

[0025] 1: Projector; 2B: Image module (optical module) for blue light; 2G: Image module (optical module) for green light; 2R: Image module (optical module) for red light; 4: Projection optical device; 13B: First image light generating unit; 11B: First light source; 11G: Second light source; 11R: Third light source; 13G: Second image light generating unit; 13R: Third image light generating unit; 14B, 14G, 14R: Liquid crystal panel; 21, 22, 23, 120, 121, 210A: Diffraction Optical elements; 31, 32, 33, 40: moving mechanism; 111A: first light-emitting element; 111B: second light-emitting element; 111C: third light-emitting element; 120: circular plate; 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. Detailed Implementation

[0026] Hereinafter, embodiments of the present invention will be described using the accompanying drawings.

[0027] In the following figures, the scale of the dimensions is sometimes different depending on the constituent elements so as to facilitate observation of each constituent element.

[0028] Figure 1 This is a top view showing the schematic structure of the projector according to this embodiment.

[0029] like Figure 1 As shown, the projector 1 of this embodiment includes 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 combining 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 are respectively equivalent to the "optical modules" of the present invention.

[0030] The blue light image module 2B includes a first light source 11B, a first light scanning unit 12B, and a first image light generating unit 13B. The first light source 11B, for example, includes a laser light-emitting element that emits blue light LB in the 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. Details of the structure of the first light scanning unit 12B will be described later. In this embodiment, the first light source 11B, the first light scanning unit 12B, and the first image light generating unit 13B correspond to the "light source," "light scanning unit," and "image light generating unit" of the present invention, respectively.

[0031] The first image light generating unit 13B generates blue image light based on the scanning light scanned by the first light scanning unit 12B. The first image light generating unit 13B includes a liquid crystal panel 14B and an emission-side polarizer 15B. The liquid crystal panel 14B includes an image forming 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 for the driving method of the liquid crystal panel 14B, twisted nematic (TN), vertical alignment (VA), and lateral electric field (IPS) methods are used, and there is no particular limitation.

[0032] The green light image module 2G includes a second light source 11G, a second light scanning unit 12G, and a second image light generating unit 13G. The second light source 11G, for example, includes a laser light-emitting element that emits green light LG in the green wavelength band of 530nm ± 5nm. The second light scanning unit 12G periodically scans the green light LG emitted from the second light source 11G. Details of the structure of the second light scanning unit 12G will be described later. In this embodiment, the second light source 11G, the second light scanning unit 12G, and the second image light generating unit 13G correspond to the "light source," "light scanning unit," and "image light generating unit" of the present invention, respectively.

[0033] The second image light generating unit 13G generates green image light based on the scanning light scanned by the second light scanning unit 12G. The second image light generating unit 13G includes a liquid crystal panel 14G and an emission-side polarizer 15G. The liquid crystal panel 14G includes an image forming 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 for the driving method of the liquid crystal panel 14G, twisted nematic (TN) method, vertical alignment (VA) method, lateral electric field (IPS) method, etc. are used, and there is no particular limitation.

[0034] The red light image module 2R includes a third light source 11R, a third light scanning unit 12R, and a third image light generating unit 13R. The third light source 11R, for example, includes a laser light-emitting element that emits red light LR in the red wavelength band of 650 nm ± 5 nm. The third light scanning unit 12R periodically scans the red light LR emitted from the third light source 11R. Details of the structure of the third light scanning unit 12R will be described later. In this embodiment, the third light source 11R, the third light scanning unit 12R, and the third image light generating unit 13R correspond to the "light source," "light scanning unit," and "image light generating unit" of the present invention, respectively.

[0035] The third image light generating unit 13R generates red image light based on the scanning light scanned by the third light scanning unit 12R. The third image light generating unit 13R includes a liquid crystal panel 14R and an emission-side polarizer 15R. The liquid crystal panel 14R includes an image forming 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 for the driving method of the liquid crystal panel 14R, twisted nematic (TN), vertical alignment (VA), lateral electric field (IPS), etc. are used, and there is no particular limitation.

[0036] The image combining element 3 emits a full-color image light into the projection optical device 4, which is obtained by combining the image lights of each color emitted from the first image light generating unit 13B, the second image light generating unit 13G, and the third image light generating unit 13R. The image combining element 3 is, for example, a cross-shaped dichroic prism.

[0037] The projection optical device 4 consists of multiple projection lenses. The projection optical device 4 magnifies and projects the image light emitted from the image combining element 3 toward a projection surface such as a screen. As a result, a full-color image is displayed on the projection surface.

[0038] Next, the structures 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 the same structure except for the color of the scanned light. Therefore, the structure of the first optical scanning unit 12B will be described below as an example, and the description of the structures of the second optical scanning unit 12G and the third optical scanning unit 12R will be omitted or simplified.

[0039] The following description, in the accompanying drawings, will use an orthogonal XYZ coordinate system 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 orthogonal to the X-axis and 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 orthogonal to both the X-axis and Y-axis. The optical axis AX3 of the red light image module 2R coincides with the optical axis AX1 of the blue light image module 2B.

[0040] Figure 2 This is a cross-sectional view showing the schematic structure of the first optical scanning unit 12B. Figure 2 This is a cross-sectional view of the first optical scanning section 12B based on the XZ plane. Figure 2 The illustration shows a liquid crystal panel 14B, which is the illumination target of the first light scanning unit 12B, with the blue light LB at a different incident position relative to the diffractive optical element 21.

[0041] like Figure 2 As shown, 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 formed of a material that is transparent to blue light LB. Examples of such materials include quartz, optical glass, and transparent resin.

[0042] The diffraction angle of the diffraction optical element 21 varies depending on the incident position of the light. The diffraction optical element 21 is constructed from a computer-generated hologram, thus enabling high-precision control of the diffraction angle of the light.

[0043] Thus, the diffractive optical element 21 can be focused onto the central axis 21A of the diffractive optical element 21 by diffracting the light transmitted through the diffractive optical element 21 at an angle corresponding to the incident position.

[0044] More specifically, such as Figure 2 As shown, 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 converges onto the optical axis AX1 regardless of the incident position of the diffractive optical element 21. Therefore, the blue light LB transmitted through the diffractive optical element 21 is independent of the incident position, Figure 2 In the case shown, the center portion of the liquid crystal panel 14B located on the optical axis AX1 is illuminated by the blue illumination light LB1. Furthermore, as described later, the illumination position of the blue illumination light LB1 on the liquid crystal panel 14B varies depending on the position of the diffractive optical element 21 relative to the liquid crystal panel 14B.

[0045] The blue illumination light LB1 illuminating the liquid crystal panel 14B is a strip of light extending along the Y-axis. Specifically, the cross-sectional shape of the blue illumination light LB1 perpendicular to the main ray is rectangular, having a long side along the Y-axis and a short side along the Z-axis. The long side of the blue illumination light LB1 is equal to or greater than the width of the rectangular image forming area 140 of the liquid crystal panel 14B in the Y-axis direction. The short side of the blue illumination light LB1 is smaller than the width of the rectangular image forming area 140 of the liquid crystal panel 14B in the Z-axis direction.

[0046] The moving mechanism 31 is a driving device for moving the diffractive optical element 21, and may be, for example, an actuator. By moving the diffractive optical element 21 using the moving mechanism 31, the blue illumination light LB1 scans the first image light generating unit 13B. In this embodiment, the blue illumination light LB1 corresponds to an example of the "scanning light" of the present invention.

[0047] The moving mechanism 31 enables the diffractive optical element 21 to reciprocate in the Z-axis direction. That is, the moving mechanism 31 enables the diffractive optical element 21 to move relative to the liquid crystal panel 14B towards the -Z and +Z sides.

[0048] In this embodiment, the movement direction of the diffractive optical element 21 caused by the moving mechanism 31 is along the Z-axis direction of the short side of the blue illumination light LB1. The blue illumination light LB1 scans the liquid crystal panel 14B along the Z-axis direction of the short side. According to this structure, by making the elongated blue illumination light LB1 scan in the short side direction, compared with the case where the blue illumination light LB1 scans in the long side direction, it is possible to efficiently illuminate the image forming area 140 while suppressing the increase in the size of the short side of the blue illumination light LB1.

[0049] In this embodiment, the Z-axis direction corresponds to the "axial direction" of the present invention, the -Z side of the Z-axis direction corresponds to the "one side of the axial direction" of the present invention, and the +Z side of the Z-axis direction corresponds to the "other side of the axial direction" of the present invention.

[0050] Figures 3A to 3E This diagram illustrates the operation of the blue illumination light LB1 emitted from the first optical scanning unit 12B. Figures 3A to 3E This diagram illustrates the situation where the diffractive optical element 21, clamping the optical axis AX1, moves from the +Z side to the -Z side. Furthermore, in... Figures 3A to 3E In the diagram, the displacement of the blue illumination light LB1 from the optical axis AX1 is shown on the left, and the blue illumination light LB1 scans the image forming area 140 of the liquid crystal panel 14B, which is the illuminated area, on the right. When using... Figures 3A to 3E In the explanation, the +Z side is sometimes referred to as the upper side, and the -Z side as the lower side.

[0051] exist Figure 3A In the state shown, the diffractive optical element 21 is arranged such that its lower end on the -Z side is located on the optical axis AX1. Therefore, in the Z-axis direction, the lower end of the diffractive optical element 21 is located at 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 area 140 of the liquid crystal panel 14B.

[0052] As described above, the blue light LB that has passed through the diffractive optical element 21 is incident on the liquid crystal panel 14B as blue illumination light LB1 that converges on the central axis 21A of the diffractive optical element 21. Therefore, in Figure 3A In the state shown, the blue illumination light LB1 illuminates the upper end 140a of the image forming area 140.

[0053] Next, as Figure 3B As shown, when the diffractive optical element 21 is moved downward (to the -Z side) by the moving mechanism 31, the central axis 21A of the diffractive optical element 21 also moves downward (to the -Z side), thereby narrowing the gap between the central axis 21A and the optical axis AX1. Consequently, the central axis 21A of the diffractive optical element 21 moves to a position lower than the upper end 140a (to the -Z side) of the image forming area 140 of the liquid crystal panel 14B, and thus the blue illumination light LB1 illuminates the lower (to the -Z side) of the image forming area 140.

[0054] Next, as Figure 3C As shown, when the diffractive optical element 21 is moved further downward (to the -Z side) by the moving mechanism 31, the central axis 21A of the diffractive optical element 21 overlaps with the optical axis AX1. At this time, the central axis 21A of the diffractive optical element 21 overlaps with the center portion 140c of the image forming area 140 of the liquid crystal panel 14B, and the blue illumination light LB1 illuminates the center portion 140c of the image forming area 140.

[0055] Next, as Figure 3D As shown, when the diffractive optical element 21 is moved further downward (to the -Z side) by the moving mechanism 31, the central axis 21A of the diffractive optical element 21 moves away from the optical axis AX1 downward (to the -Z side), thereby increasing the distance between the central axis 21A and the optical axis AX1. Consequently, the central axis 21A of the diffractive optical element 21 moves to a position below the center portion 140c in the image forming area 140 of the liquid crystal panel 14B (to the -Z side), and therefore the blue illumination light LB1 illuminates the area below the center portion 140c in the image forming area 140 (to the -Z side).

[0056] Next, when the diffractive optical element 21 is moved further downward (to the -Z side) by the moving mechanism 31, as... Figure 3EAs shown, the central axis 21A of the diffractive optical element 21 is located at the lower end 140b of the image forming region 140 of the liquid crystal panel 14B on the -Z side. Therefore, in Figure 3E In the state shown, the blue illumination light LB1 illuminates the lower end 140b of the image forming area 140.

[0057] In this way, by using the moving mechanism 31 to move the diffractive optical element 21 from top to bottom, the first light scanning unit 12B can scan the image forming area 140 of the liquid crystal panel 14B with blue illumination light LB1 from top to bottom. Therefore, the first light scanning unit 12B can illuminate the entire rectangular image forming area 140 with blue illumination light LB1.

[0058] Next, the timing correspondence between the driving timing of the liquid crystal panel 14B and the scanning timing of the blue illumination light LB1 based on the first light scanning unit 12B will be explained. Figure 4 It is a timing diagram showing the time correspondence between the liquid crystal panel 14B and the first optical scanning unit 12B.

[0059] exist Figure 4 In this context, E1 to E5 represent the corresponding relationship of rotation efficiency at various positions in the vertical direction (Z-axis direction) of the image forming area 140 of the liquid crystal panel 14B. Here, the rotation efficiency of the liquid crystal panel 14B refers to the proportion of linearly polarized light incident on the liquid crystal layer that is converted into linearly polarized light orthogonal to that linearly polarized light.

[0060] 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 center 140c of the image forming region 140, position E2 corresponds to the area between the upper end 140a and the center 140c of the image forming region 140, and position E4 corresponds to the area between the center 140c and the lower end 140b of the image forming region 140.

[0061] exist Figure 4 In this context, ST represents the scanning period during which the blue illumination light LB1 scans the image forming area 140. That is, during the scanning period ST, the first light source 11B sets the blue light LB to an illuminated state.

[0062] like Figure 4 As shown, the liquid crystal panel 14B sequentially selects multiple scan lines via a scan line driving circuit (not shown) to generate image light in the image forming area 140. This sequential selection of multiple scan lines via the scan line driving circuit is called "vertical scanning," and the direction in which the scan lines are sequentially scanned via the vertical scanning circuit is called the "vertical scanning direction."

[0063] In the liquid crystal panel 14B of this embodiment, the Z-axis direction of the positions E1 to E5 in the image forming area 140 corresponds to vertical scanning. In this embodiment, the vertical scanning direction of the liquid crystal panel 14B is the same as the direction in which the blue illumination light LB1 scans on the image forming area 140 by moving downward (-Z side) through the diffractive optical element 21.

[0064] According to this structure, by aligning the scanning direction of the blue illumination light LB1 with the vertical scanning direction of the liquid crystal panel 14B, the scanning of the blue illumination light LB1 can be started at a timing point before the vertical scanning of the image forming area 140 ends. Therefore, compared to starting the scanning of the blue illumination light LB1 after the vertical scanning is completed, the acceleration of the diffractive optical element 21 caused by the moving mechanism 31 can be suppressed. Thus, the load on the moving mechanism 31 can be reduced, the risk of breakage or malfunction can be reduced, and the power consumption of the moving mechanism 31 can be suppressed.

[0065] The vertical scanning direction of the image forming region 140 is from the +Z side to the -Z side, so the timing of reaching 100% rotation efficiency at each position E1 to E5 is staggered. That is, the timing of reaching 100% rotation efficiency at the upstream position E1 in the vertical scanning direction is the earliest, and the timing of reaching 100% rotation efficiency at the downstream position E5 in the vertical scanning direction is the latest.

[0066] In this embodiment, during the scanning period ST, when the rotation efficiency at each position E1 to E5 of the image forming region 140 reaches 100%, the blue illumination light LB1 is started scanning the image forming region 140. Thus, the image forming region 140 can generate image light of the desired brightness by efficiently modulating the blue illumination light LB1.

[0067] In addition, Figure 4 In this context, T1 represents the vertical scanning period of the liquid crystal panel 14B, and T2 represents the scanning period based on the blue illumination light LB1 of the first light scanning unit 12B. In this embodiment, for example, T1 is 1 / 240s, T2 is 1 / 480s, and the vertical scanning period T1 is twice the scanning period T2.

[0068] In this embodiment, the blue illumination light LB1 scans 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, the diffractive optical element 21 needs to be moved back to the top. Thus, the first light scanning unit 12B needs to reciprocate the diffractive optical element 21 within one frame of the liquid crystal panel 14B.

[0069] Here, we consider the state of the first light source 11B when the diffractive optical element 21 is returned to the upward side. For example, if the first light source 11B is kept lit while the diffractive optical element 21 is moved upward side, in Figure 4 As indicated by the dashed arrow, the blue illumination light LB1 scans in the opposite direction from position E5 to position E1 in the image forming region 140. However, at the timing when the blue illumination light LB1 passes through position E5 of the image forming region 140, position E5 is the state before switching to the display of the next frame. At the timing when the blue illumination light LB1 passes through position E4 of the image forming region 140, the rotation efficiency at position E4 does not reach 100%, so it is possible that the blue illumination light LB1 may not be properly modulated, resulting in image quality degradation due to poor modulation.

[0070] In contrast, in the blue light image module 2B of this embodiment, the first light source 11B is illuminated during the period when the diffractive optical element 21 moves downward (-Z side) in the first light scanning unit 12B, and the first light source 11B is extinguished during the period when the diffractive optical element 21 moves upward (+Z side). This suppresses the power consumption of the first light source 11B and prevents image quality degradation caused by poor modulation of the blue illumination light LB1 by the liquid crystal panel 14B in a state of insufficient rotational efficiency.

[0071] 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 light scanning unit 12B that periodically scans the blue light LB emitted from the first light source 11B; and a first image light generating unit 13B that generates image light based on the blue illumination light LB1 scanned by the first light scanning unit 12B. The first light scanning unit 12B has a diffraction optical element 21 whose diffraction angle varies depending on the light incident position and a moving mechanism 31 for moving the diffraction optical element 21. The blue illumination light LB1 scans the liquid crystal panel 14B of the first image light generating unit 13B by moving the diffraction optical element 21.

[0072] 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, compared with the conventional structure that uses a multifaceted mirror to scan the illumination light, the blue illumination light LB1 can be scanned on the liquid crystal panel 14B while miniaturizing the device structure. Therefore, bright and high-quality image light can be generated in the liquid crystal panel 14B.

[0073] In the above description, the structure of the first light scanning unit 12B of the blue light image module 2B was described as an example, but the second light scanning unit 12G of the green light image module 2G and the third light scanning unit 12R of the red light image module 2R also have the same structure as the first light scanning unit 12B.

[0074] The second light 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, by moving the diffractive optical element 22 using the moving mechanism 32 of the second light scanning unit 12G, it is possible to scan the green illumination light LG1 on the image forming area 141 of the liquid crystal panel 14G while suppressing the enlargement of the device structure. Therefore, bright and high-quality image light can be generated in the liquid crystal panel 14G.

[0075] Furthermore, in this embodiment, the green light image module 2G illuminates the second light source 11G during the period when the diffraction optical element 22 moves downward (to the -Z side) in the second light scanning unit 12G, and extinguishes the second light source 11G during the period when the diffraction optical element 22 moves upward (to the +Z side). With this structure, the power consumption of the second light source 11G can be suppressed, and the image quality degradation caused by poor modulation of the green illumination light LG1 by the liquid crystal panel 14G can be suppressed.

[0076] Furthermore, the third light 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, by moving the diffractive optical element 23 using the moving mechanism 33 of the third light scanning unit 12R, it is possible to scan the red illumination light LR1 on the image forming area 142 of the liquid crystal panel 14R while suppressing the enlargement of the device structure. Therefore, bright and high-quality image light can be generated in the liquid crystal panel 14R.

[0077] Furthermore, in this embodiment, the red light image module 2R illuminates the third light source 11R during the period when the diffraction optical element 23 moves downward (to the -Z side) in the third light scanning unit 12R, and extinguishes the third light source 11R during the period when the diffraction optical element 23 moves upward (to the +Z side). With this structure, the power consumption of the third light source 11R can be suppressed, and the image quality degradation caused by poor modulation of the red illumination light LR1 by the liquid crystal panel 14R can be suppressed.

[0078] 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 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.

[0079] The projector 1 according to this embodiment is a projector that can project high-quality images while making the structure of the suppression device larger.

[0080] Variations

[0081] Next, a variation of the projector according to the above embodiment will be described. The difference between this variation and the above embodiment lies in the structure of the optical scanning unit of each image module. Hereinafter, the first optical scanning unit will be used as an example, but the same applies to the second and third optical scanning units.

[0082] Figure 5A This is a top view showing the schematic structure of the first optical scanning unit 112B in this modified example. Figure 5A This is a diagram of the first optical scanning section 112B viewed from the +Z side. Figure 5B This is a top view of the first optical scanning section 112B of this modified example, viewed along the X-axis direction of the optical axis AX1.

[0083] like Figure 5A As shown, 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 circular plate 120 and a rotation drive unit 130. The circular plate 120 is a light-transmitting substrate that supports the diffractive optical element 121. The diffractive optical element 121 is arranged circumferentially along the circular plate 120. That is, the diffractive optical element 121 is arranged in a ring shape around the rotation axis O. The rotation drive unit 130, for example, is a motor, which rotates the circular plate 120 around the rotation axis O.

[0084] like Figure 5B As shown, the first optical scanning unit 112B is arranged such that a portion of the diffractive optical element 121 overlaps with the optical axis AX1. In this modified example of the first optical scanning unit 112B, the diffractive optical element 121 is moved relative to the blue light LB by rotating the circular plate 120. As a result, the incident position of the blue light LB in the diffractive optical element 121 changes.

[0085] According to this variation, such as Figure 5B As shown, by rotating the circular plate 120, the diffractive optical element 121 moves relative to the optical axis AX1 towards the +Z side. Therefore, similar to the above embodiment, the blue illumination light LB1 that has passed through the diffractive optical element 121 can be scanned towards the -Y side on the image forming area 140 of the liquid crystal panel 14B.

[0086] In this modified example, the diffractive optical element 121 can be formed in a ring shape in the circumferential direction of the circular plate 120, or it can be constructed by dividing the circular plate 120 into multiple parts in the circumferential direction.

[0087] In this modified example, the first light source 11B can be turned off when the rotation efficiency of the liquid crystal panel 14B has not reached 100%, so that the blue light LB is not incident on the diffractive optical element 121. Alternatively, the blue light LB can be blocked by a light-shielding member provided on the light incident side of the diffractive optical element 121.

[0088] In addition, in this modified example, during the rotation of the circular plate 120, the blue illumination light LB1 can scan the image forming area 140 once or multiple times.

[0089] Implementation Method 2

[0090] Next, the projector of the second embodiment will be described. The difference between this embodiment and the previous embodiment lies in the structure of each image module. Hereinafter, the image module for blue light will be used as an example for description, but the same applies to the image modules for green light and red / blue light. Furthermore, components and structures identical to those in the previous embodiment will be labeled with the same reference numerals, and detailed descriptions will be omitted or simplified.

[0091] Figure 6 This is a cross-sectional view showing the schematic structure of the blue light image module 102B of this embodiment. (See attached image.) Figure 6 As shown, the blue light image module 102B includes a first light source 111, a first light scanning unit 210, and a first image light generating unit 13B. In this embodiment, the first light source 111 and the first light scanning unit 210 correspond to the "light source" and "light scanning unit" of the present invention, respectively.

[0092] The first light source 111 in 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 sequentially in the scanning direction of the blue illumination light LB1, i.e., from the +Z side to the -Z side.

[0093] 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 diffraction optical element 210A, a second diffraction optical element 210B, a third diffraction optical element 210C, a fourth diffraction optical element 210D, and a fifth diffraction optical element 210E arranged sequentially in the scanning direction of the blue illumination light LB1. Furthermore, the diffraction optical elements 210A to 210E of the diffraction element unit 211 can be arranged with gaps between them in the Z-axis direction, or they can be arranged in a state of mutual contact. Each diffraction optical element 210A to 210E of the diffraction element unit 211 is a computer-generated hologram (CGH) that diffracts light incident from the corresponding light-emitting element.

[0094] In this embodiment, the image forming area 140 of the liquid crystal panel 14B includes a first illumination area 241, a second illumination area 242, a third illumination area 243, a fourth illumination area 244, and a fifth illumination area 245 arranged in the scanning direction of the blue illumination light LB1.

[0095] The first diffractive optical element 210A diffracts the blue light LB incident from the first light-emitting element 111A to illuminate the first illumination area 241 of the liquid crystal panel 14B. In addition, the central axis of the first diffractive optical element 210A is aligned with the central axis of the first illumination area 241.

[0096] The second diffractive optical element 210B diffracts the blue light LB incident from the second light-emitting element 111B to illuminate the second illumination area 242 of the liquid crystal panel 14B. Furthermore, the central axis of the second diffractive optical element 210B is aligned with the central axis of the second illumination area 242.

[0097] The third diffractive optical element 210C diffracts the blue light LB incident from the third light-emitting element 111C to illuminate the third illumination area 243 of the liquid crystal panel 14B. In addition, the central axis of the third diffractive optical element 210C is aligned with the central axis of the third illumination area 243.

[0098] The fourth diffractive optical element 210D diffracts the blue light LB incident from the fourth light-emitting element 111D to illuminate the fourth illumination area 244 of the liquid crystal panel 14B. In addition, the central axis of the fourth diffractive optical element 210D is aligned with the central axis of the fourth illumination area 244.

[0099] 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. Furthermore, the central axis of the fifth diffractive optical element 210E is aligned with the central axis of the fifth illumination region 245.

[0100] The control unit CONT is composed of a computer or integrated circuit that has the processing of controlling the driving of each light-emitting element 111A to 111E built into it as a program. That is, the control unit CONT is, for example, a processor. The control unit CONT is connected to each light-emitting element 111A to 111E via a wired or wireless means (not shown). In addition to the first light source 111, the control unit CONT can also control the driving of other structural components of the projector 1.

[0101] Figures 7A to 7E This diagram illustrates the operation of the blue illumination light LB1 emitted from the first light scanning unit 112B and incident on the liquid crystal panel 14B. Figures 7A to 7E This diagram sequentially illustrates the process by which the light-emitting elements 111A to 111E of the first light source 111 switch their illumination states from the +Z side to the -Z side. Furthermore, in Figures 7A to 7E In the image, the operation of the blue illumination light LB1 as viewed from the -Y side is shown on the left, and the blue illumination light LB1 scanning the image forming area 140 of the liquid crystal panel 14B, which is the illuminated area, is shown on the right. When using... Figures 7A to 7EIn the explanation, the +Z side is sometimes referred to as the upper side, and the -Z side as the lower side.

[0102] like Figure 7A As shown, the control unit CONT only illuminates the first light-emitting element 111A in 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.

[0103] Next, as Figure 7B As shown, the control unit CONT turns off the first light-emitting element 111A and only lights up 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 area 242 located below the first illumination area 241 as blue illumination light LB1.

[0104] Next, as Figure 7C As shown, the control unit CONT turns off the second light-emitting element 111B and only lights up 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 area 243 located below the second illumination area 242 as blue illumination light LB1.

[0105] Next, as Figure 7D As shown, the control unit CONT turns off the third light-emitting element 111C and only lights up 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 area 244 located below the third illumination area 243 as blue illumination light LB1.

[0106] Next, as Figure 7E As shown, the control unit CONT turns off the fourth light-emitting element 111D and only lights up 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 region 245, which is located below the fourth illumination region 244 and at the bottom of the image forming region 140, as blue illumination light LB1.

[0107] Thus, the blue light image module 2B of this embodiment includes: a first light source 111 that emits blue light LB; a first light scanning unit 210 that periodically scans the blue light LB emitted from the first light source 111; and a first image light generating unit 13B that generates image light based on the blue illumination light LB1 scanned by the first light scanning unit 210.

[0108] 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 arranged in the scanning direction of the blue light LB.

[0109] The first optical scanning unit 210 includes: a first diffractive optical element 210A, which diffracts light incident from the first light-emitting element 111A to illuminate a first illumination region 241 of the first image light generating unit 13B; a second diffractive optical element 210B, which is disposed relative to the first diffractive optical element 210A in the scanning direction, and diffracts light incident from the second light-emitting element 111B to illuminate a second illumination region 242 of the first image light generating unit 13B; and a third diffractive optical element 210C, which is disposed relative to the second diffractive optical element 210B in the scanning direction, and diffracts light incident from the third light-emitting element 111C to illuminate a first image light generating unit 13B. The third illumination region 243 of the generation unit 13B is illuminated; the fourth diffractive optical element 210D, which is arranged in the scanning direction relative to the third diffractive optical element 210C, illuminates the fourth illumination region 244 of the first image light generation unit 13B by diffraction of light incident from the fourth light-emitting element 111D; the fifth diffractive optical element 210E, which is arranged in the scanning direction relative to the fourth diffractive optical element 210D, illuminates the fifth illumination region 245 of the first image light generation unit 13B by diffraction of light incident from the fifth light-emitting element 111E; and the control unit CONT controls the driving of each light-emitting element 111A to 111E.

[0110] The control unit CONT sequentially switches the illumination of each light-emitting element 111A to 111E, thereby illuminating each lighting area 241 to 245 in sequence with blue light LB.

[0111] According to the blue light image module 2B of this embodiment, by switching the illumination of each light-emitting element 111A to 111E of the first light source 111, blue light LB can be sequentially incident on each diffractive optical element 210A to 210E. Thus, the blue illumination light LB1 emitted from each diffractive optical element 210A to 210E can scan each illumination region 241 to 245 of the image forming region 140 of the liquid crystal panel 14B from top to bottom. With this structure, compared to the conventional structure that uses a multi-faceted mirror to scan the illumination light, the blue illumination light LB1 can be scanned on the liquid crystal panel 14B while miniaturizing the device structure. Therefore, bright and high-quality image light can be generated in the liquid crystal panel 14B.

[0112] Furthermore, in this embodiment, an example is given where the number of light-emitting elements of the first light source 111, the number of diffractive optical elements corresponding to the light-emitting elements, and the number of illumination areas of the image forming area 140 are all set to 5, but this is not a limitation. In the case of the present invention, it is sufficient to set the number of light-emitting elements of the first light source 111 and the number of diffractive optical elements corresponding to the light-emitting elements to at least 3.

[0113] In the above description, the structure of the first light scanning unit 210 of the blue light image module 102B was described as an example, but the second light scanning unit of the green light image module and the third light scanning unit of the red light image module also have the same structure as the first light scanning unit 210.

[0114] 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, it is possible to scan the green illumination light on the image forming area of ​​the liquid crystal panel 14G while suppressing the enlargement of the device structure. Thus, bright and high-quality image light can be generated in the liquid crystal panel 14G.

[0115] 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 the enlargement of the device structure. Therefore, bright and high-quality image light can be generated in the liquid crystal panel 14R.

[0116] Furthermore, according to the projector of this embodiment, by having the blue light image module 102B described above, a green light image module and a red light image module with the same structure as the blue light image module 102B, a projector that can project high-quality images while reducing the size of the suppression device structure can be realized.

[0117] The technical scope of the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

[0118] Furthermore, the specific descriptions of the shape, quantity, configuration, materials, etc. of the various components of the projector are not limited to the above-described embodiments and can be appropriately modified.

[0119] The following is a summary published in this note.

[0120] (Note 1)

[0121] An optical module includes: a light source that emits light; a light scanning unit that periodically scans the light emitted from the light source; and an image light generating unit that generates image light based on the scanned light scanned by the light scanning unit, the light scanning unit including: a diffractive optical element whose diffraction angle varies depending on the light incident position; and a moving mechanism that moves the diffractive optical element, the scanned light scanning the image light generating unit by moving the diffractive optical element.

[0122] By moving the diffractive optical element into which the light emitted from the light source is incident, the scanning light can be scanned on the image light generation unit while miniaturizing the device structure, compared to the conventional structure that uses a multifaceted mirror to scan the illumination light. Therefore, bright and high-quality image light can be generated in the image light generation unit.

[0123] (Note 2)

[0124] According to the optical module described in Appendix 1, the cross-sectional shape of the scanning light perpendicular to the main ray is a rectangle with a long side and a short side, and the scanning light scans the image light generating unit in the direction along the short side.

[0125] According to this structure, by scanning a strip of scanning light in the short side direction, compared with scanning light in the long side direction, it is possible to suppress the increase in the size of the short side of the scanning light and to efficiently illuminate the image light generation unit.

[0126] (Note 3)

[0127] According to the optical module described in Appendix 1 or 2, the moving mechanism is capable of moving the diffractive optical element to one side of the axial direction and to the other side of the axial direction, the light source is lit during the movement of the diffractive optical element to one side of the axial direction and is extinguished during the movement of the diffractive optical element to the other side of the axial direction, the image light generating unit has a liquid crystal panel, the liquid crystal panel includes an image forming area for generating the image light, and the vertical scanning direction when generating the image light in the image forming area is the same as the direction in which the scanning light scans the image forming area by moving the diffractive optical element to one side of the axial direction.

[0128] According to this structure, by aligning the scanning direction of the scanning light with the vertical scanning direction of the liquid crystal panel, scanning of the scanning light can begin at a timed interval before the vertical scanning of the image forming area ends. Therefore, compared to starting scanning after the vertical scanning is completed, the acceleration of the diffractive optical elements caused by the moving mechanism can be suppressed, thereby reducing the load on the moving mechanism, lowering the risk of breakage or malfunction, and suppressing the power consumption of the moving mechanism.

[0129] (Note 4)

[0130] According to the optical module described in Appendix 3, the vertical scanning period of the liquid crystal panel is twice the scanning period of the scanning light by the light scanning unit.

[0131] According to this structure, by moving the diffractive optical element from one side to the other within one frame of the liquid crystal panel, it is possible to realize a structure that allows scanning light to scan on the image forming area.

[0132] (Note 5)

[0133] The optical module according to any one of Annexes 1 to 4, wherein the diffractive optical element is a computer-generated hologram.

[0134] According to this structure, the diffraction angle of light can be controlled with high precision by using diffractive optical elements composed of computer-synthesized holograms.

[0135] (Note 6)

[0136] According to any one of Annexes 1 to 5, the optical module wherein the moving mechanism comprises: a circular plate that supports the diffractive optical element and is transparent; and a rotation drive that rotates the circular plate, wherein the diffractive optical element is arranged circumferentially along the circular plate.

[0137] According to this structure, by rotating the circular plate, the diffractive optical element can be moved to one side relative to the optical axis of the light. Therefore, the light that has passed through the diffractive optical element can be scanned to one side on the image light generating unit.

[0138] (Note 7)

[0139] An optical module includes: a light source that emits light; a light scanning unit that periodically scans the light emitted from the light source; and an image light generating unit that generates image light based on the scanned light scanned by the light 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 scanned light. The light scanning unit includes: a first diffractive optical element that diffracts light incident from the first light-emitting element to illuminate a first illumination area of ​​the image light generating unit; and a second diffractive optical element disposed relative to the first diffractive optical element in the scanning direction, which diffracts light incident from the second light-emitting element to illuminate a first illumination area of ​​the image light generating unit. The first light-emitting element, the second light-emitting element, and the third light-emitting element are diffracted to illuminate the second illumination area of ​​the image light generating unit; a third diffractive optical element is disposed in the scanning direction relative to the second diffractive optical element, so that the light incident from the third light-emitting element is diffracted to illuminate the third illumination area of ​​the image light generating unit; and a control unit controls the driving of the first light-emitting element, the second light-emitting element, and the third light-emitting element, and sequentially switches the illumination of the first light-emitting element, the second light-emitting element, and the third light-emitting element by the control unit, so that the scanning light sequentially illuminates the first illumination area, the second illumination area, and the third illumination area.

[0140] According to the optical module of this structure, by switching the illumination of each light-emitting element of the light source, light can be sequentially incident on each diffractive optical element. Thus, the light emitted from each diffractive optical element can sequentially scan each illumination area of ​​the image light generation unit. Therefore, according to this structure, compared to conventional structures that use multifaceted mirrors to scan the illumination light, the scanning light can be scanned on the image light generation unit while simultaneously miniaturizing the device structure. Therefore, bright and high-quality image light can be generated in the image light generation unit.

[0141] (Note 8)

[0142] A projector comprising: an optical module as described in any one of Annexes 1 to 7; and a projection optical device for projecting light emitted from the optical module.

[0143] Based on this structure, a projector can project high-quality images while suppressing the large size of the device structure.

Claims

1. An optical module having: A light source, which emits light; A light scanning unit that periodically scans the light emitted from the light source; and The image light generation unit generates image light based on the scanning light scanned by the light scanning unit. The optical scanning unit has: Diffractive optical elements, whose diffraction angle varies depending on the incident position of the light; and A moving mechanism that moves the diffractive optical element. The scanning light moves through the diffractive optical element to scan the image light generating unit.

2. The optical module according to claim 1, wherein, The cross-sectional shape of the scanning light perpendicular to the principal ray is a rectangle with a long side and a short side. The scanning light scans the image light generating unit along the direction of the short side.

3. The optical module according to claim 1, wherein, The moving mechanism enables the diffractive optical element to move to one side of the axial direction and to the other side of the axial direction. The light source illuminates while the diffractive optical element moves to one side of the axis and extinguishes while the diffractive optical element moves to the other side of the axis. The image light generating unit has a liquid crystal panel, which includes an image forming area 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 by moving the diffractive optical element to one side of the axis.

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

5. The optical module according to claim 1, wherein, The diffractive optical element is a computer-generated holographic component.

6. The optical module according to claim 1, wherein, The moving mechanism includes: a circular plate that supports the diffractive optical element and is transparent; and a rotation drive that rotates the circular plate. The diffractive optical elements are arranged circumferentially along the circular plate.

7. An optical module having: A light source, which emits light; A light scanning unit that periodically scans the light emitted from the light source; and The image light generation unit generates image light based on the scanning light scanned by the light 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 has: The first diffractive optical element diffracts light incident from the first light-emitting element to illuminate the first illumination area of ​​the image light generating unit; The second diffractive optical element is disposed in the scanning direction relative to the first diffractive optical element, so that the light incident from the second light-emitting element is diffracted to illuminate the second illumination area of ​​the image light generating unit; A third diffractive optical element, disposed relative to the second diffractive optical element in the scanning direction, illuminates the third illumination area of ​​the image light generating unit by diffraction of light incident from the third light-emitting element; and The control unit 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 sequentially illuminates the first illumination area, the second illumination area, and the third illumination area.

8. A projector comprising: The optical module according to any one of claims 1 to 7; and A projection optical device that projects light emitted from the optical module.

Images