Pixel shift device and projector

Abstract

To provide a pixel shift device and a projector capable of simultaneously realizing a display quality and securing rigidity.SOLUTION: A pixel shift device includes: a base; a first frame configured to oscillate around a first oscillation axis against the base; an optical member supported by the first frame; a first oscillation shaft formation part configured to connect the first frame and the base at a position holding both sides of the first frame in a direction along the first oscillation axis; and a first actuator configured to oscillate the first frame against the base. The first oscillation shaft formation part includes a first shaft member and a first bearing member. The first bearing member includes: a first inner ring bearing ring fixed to the first shaft member; a first outer ring bearing ring; and a plurality of first rolling elements arranged between the first inner ring bearing ring and the first outer ring bearing ring.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a pixel shifting device and a projector. [Background technology]

[0002] Conventionally, there are projectors equipped with a pixel shift device that shifts the optical path of image light emitted from a light modulation device such as a liquid crystal panel. For example, the pixel shift device disclosed in Patent Document 1 below includes a first frame that holds an optical member, a second frame that is arranged around and connects the first frame, a base member that is arranged around and connects the second frame, a first actuator that swings the first frame relative to the second frame about a first swing axis, and a second actuator that swings the second frame about a second swing axis relative to the base member. In other words, the pixel shift device disclosed in Patent Document 1 below has a configuration that allows the optical member to swing about two axes.

[0003] Furthermore, the pixel shift device disclosed in Patent Document 2 below includes a frame that holds an optical member, a base member that is disposed around the frame and connects the frames, and an actuator that swings the frame around a swing axis relative to the base member. In other words, the pixel shift device disclosed in Patent Document 2 below has a configuration that allows the optical member to swing on one axis. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-91343 [Patent Document 2] Japanese Patent Publication No. 2020-85924 Summary of the Invention [Problem to be solved by the invention]

[0005] In the pixel shift device described above, the shaft that connects the frame and the base member to allow the shaft to oscillate is made of a metal plate, so applying too much pressure to the shaft can cause plastic deformation and lead to malfunction. In response to this, if the actuator output is reduced so that pressure is applied to the shaft within a range of elastic deformation that will not cause fatigue fracture in order to ensure the rigidity of the shaft, the optical member cannot be oscillated significantly, and the amount of shift of the image light becomes small.

[0006] Therefore, it is conceivable to increase the thickness of the glass plates that make up the optical member to increase the amount of shift of the light that passes through the optical member, thereby suppressing the oscillation angle of the optical member and increasing the amount of shift of the image light. However, if the glass plates are made thicker, the weight of the optical member increases, which makes it necessary to increase the output of the actuator, making it difficult to ensure the rigidity of the shaft.

[0007] It is also possible to increase the shift amount of the image light by using a material with a higher refractive index for the glass plates that make up the optical member, thereby increasing the shift amount due to the refraction of light when passing through the optical member, while suppressing the rocking angle of the optical member. However, when a material with a high refractive index is used for the glass plates, the weight of the optical member does not increase, but the use of a high refractive index material causes a decrease in display quality due to chromatic aberration, etc.

[0008] Given this background, there was a need for a new technology that could ensure both the rigidity of the axis and the display quality achieved by image shifting. [Means for solving the problem]

[0009] In order to solve the above problem, according to one aspect of the present invention, there is provided a pixel shift device comprising: a base; a first frame that oscillates relative to the base around a first oscillation axis; an optical element supported by the first frame; a first oscillation axis forming part that connects the first frame and the base at a position that sandwiches both sides of the first frame in a direction along the first oscillation axis; and a first actuator that oscillates the first frame relative to the base, wherein the first oscillation axis forming part has a first shaft member and a first bearing member, and the first bearing member is composed of a first inner ring raceway fixed to the first shaft member, a first outer ring raceway, and a plurality of first rolling elements arranged between the first inner ring raceway and the first outer ring raceway.

[0010] According to another aspect of the present invention, an image generating unit including a light modulation device that generates image light; There is provided a projector comprising: a projection optical system that projects the image light; and an image shifting device of the above aspect that is arranged between the image generation unit and the projection optical system and shifts the optical path of the image light from the image generation unit. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram illustrating a schematic configuration of a projector according to an embodiment. [Figure 2] FIG. 1 is an explanatory diagram showing the principle of increasing the resolution of an image using a pixel shift device. [Figure 3] FIG. 2 is a plan view of a pixel shifting device. [Figure 4] FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. [Figure 5] FIG. 4 is a cross-sectional view taken along line VV in FIG. [Figure 6] FIG. 4 is a cross-sectional view taken along line VI-VI in FIG. [Figure 7A] FIG. 10 is a view showing a state in which pressure is applied to the first inner raceway ring. [Figure 7B] FIG. 10 is a diagram showing a state in which pressure is applied to the first outer ring raceway. [Figure 8]FIG. 10 is a side view showing a schematic configuration of a pixel shift device according to a first modified example. [Figure 9] FIG. 10 is a side view showing a schematic configuration of a pixel shift device according to a second modified example. [Figure 10] FIG. 11 is a plan view showing a schematic configuration of a pixel shift device according to a third modified example. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. Note that the drawings used in the following description may show characteristic portions enlarged for convenience in order to make the characteristics easier to understand, and the dimensional ratios of the respective components may not necessarily be the same as those in reality.

[0013] FIG. 1 is a diagram showing a schematic configuration of a projector according to this embodiment. As shown in FIG. 1, a projector 1 of this embodiment includes a light source 2, a color separation optical system 3, an image generation unit 4, a projection optical system 6, and a pixel shift device 10.

[0014] Hereinafter, the positional relationship of each component may be explained using the XYZ coordinate system shown in the drawings. In each drawing, the Y axis is the axis along the projection direction of the image light LT onto the screen SCR in the projector 1. The X axis is the axis perpendicular to the Y axis and along the width direction of the screen SCR. The Z axis is the axis perpendicular to the X axis and Y axis and along the up-down direction of the screen SCR.

[0015] In this embodiment, for example, both directions along the Z axis are collectively referred to as the "up-down direction Z" in the projector 1, the direction toward the +Z direction is referred to as the "upper side," and the direction toward the -Z direction is referred to as the "lower side." Furthermore, both directions along the X axis are collectively referred to as the "left-right direction X" in the projector 1, the direction toward the +X direction is referred to as the "right side," and the direction toward the -X direction is referred to as the "left side." Furthermore, both directions along the Y axis are collectively referred to as the "front-rear direction Y" in the projector 1, the direction toward the +Y direction is referred to as the "front side," and the direction toward the -Y direction is referred to as the "rear side." The vertical direction Z, horizontal direction X, and front-rear direction Y are names used simply to explain the positional relationship of the components of the projector 1, and do not define the actual installation posture or orientation of the projector 1.

[0016] The light source 2 has a configuration including, for example, a laser light source, a wavelength conversion element, etc. The light source 2 collects blue laser light emitted from the laser light source using a condenser lens as excitation light, and causes it to enter a wavelength conversion element containing a phosphor, thereby emitting white light WL consisting of the blue laser light and yellow fluorescence. Note that the light source 2 is not limited to a configuration using a laser light source and a wavelength conversion element, and may also be configured to use, for example, a laser light source alone, or a configuration using an LED (Light Emitting Diode) or a discharge-type light source lamp.

[0017] The image generation unit 4 has a light modulation device 4R that emits red image light, a light modulation device 4G that emits green image light, a light modulation device 4B that emits blue image light, and a light combining element 5. The image generation unit 4 modulates the light emitted from the light source 2 based on image information to generate image light LT.

[0018] The color separation optical system 3 includes a first dichroic mirror 7a, a second dichroic mirror 7b, a first reflecting mirror 8a, a second reflecting mirror 8b, a third reflecting mirror 8c, and relay lenses 9a and 9b. The color separation optical system 3 separates the white light WL emitted from the light source 2 into red light LR, green light LG, and blue light LB.

[0019] The first dichroic mirror 7a separates the white light WL emitted from the light source 2 into red light LR, green light LG, and blue light LB. The first dichroic mirror 7a transmits the red light LR and reflects the green light LG and blue light LB. The second dichroic mirror 7b separates the mixed light of the green light LG and blue light LB into the green light LG and blue light LB. The second dichroic mirror 7b reflects the green light LG and transmits the blue light LB.

[0020] The first reflecting mirror 8a is disposed in the optical path of the red light LR. The first reflecting mirror 8a reflects the red light LR transmitted by the first dichroic mirror 7a toward the optical modulation device 4R. The second reflecting mirror 8b and the third reflecting mirror 8c are disposed in the optical path of the blue light LB. The second reflecting mirror 8b and the third reflecting mirror 8c guide the blue light LB transmitted by the second dichroic mirror 7b to the optical modulation device 4B.

[0021] The light modulation device 4G is composed of a green liquid crystal panel 4GP and polarizing plates (not shown) provided on the entrance and exit sides of the green liquid crystal panel 4GP. The light modulation device 4R is composed of a red liquid crystal panel 4RP and polarizing plates (not shown) provided on the entrance side and exit side of the red liquid crystal panel 4RP. The light modulation device 4B is composed of a blue liquid crystal panel 4BP and polarizing plates (not shown) provided on the entrance side and exit side of the blue liquid crystal panel 4BP. Hereinafter, the red liquid crystal panel 4RP, the green liquid crystal panel 4GP, and the blue liquid crystal panel 4BP may be collectively referred to as the liquid crystal panels 4RP, 4GP, and 4BP, respectively.

[0022] The light modulation device 4R modulates the red light LR of the white light WL emitted from the light source 2 using a red liquid crystal panel 4RP in accordance with an image signal. The light modulation device 4G modulates the green light LG of the white light WL emitted from the light source 2 using a green liquid crystal panel 4GP in accordance with an image signal. The light modulation device 4B modulates the blue light LB of the white light WL emitted from the light source 2 using a blue liquid crystal panel 4BP in accordance with an image signal. As a result, each of the light modulation devices 4R, 4G, and 4B generates image light corresponding to each color light.

[0023] A field lens 11R that collimates the red light LR that is incident on the light modulation device 4R is disposed on the light incident side of the light modulation device 4R. A field lens 11G that collimates the green light LG that is incident on the light modulation device 4G is disposed on the light incident side of the light modulation device 4G. A field lens 11B that collimates the blue light LB that is incident on the light modulation device 4B is disposed on the light incident side of the light modulation device 4B.

[0024] The light combining element 5 is configured by a substantially cubic cross dichroic prism. The light combining element 5 combines the color lights emitted from the light modulation devices 4R, 4G, and 4B to generate image light LT.

[0025] The projection optical system 6 is composed of multiple projection lenses. The projection optical system 6 enlarges and projects the image light LT synthesized by the image generation unit 4 onto the screen SCR. As a result, a color image is displayed on the screen SCR.

[0026] The pixel shift device 10 is disposed on the optical path of the image light LT between the light combining element 5 of the image generation unit 4 and the projection optical system 6. The projector 1 shifts the optical path of the image light LT using the pixel shift device 10, causing a so-called pixel shift, thereby enabling an image with a higher resolution than the resolution of each of the liquid crystal panels 4RP, 4GP, and 4BP to be displayed on the screen SCR. For example, if each of the liquid crystal panels 4RP, 4GP, and 4BP is a full high-definition compatible liquid crystal panel, a 4K image can be displayed.

[0027] Here, the principle of increasing the resolution by shifting the optical path will be briefly explained with reference to Fig. 2. Fig. 2 is an explanatory diagram showing the principle of increasing the resolution by shifting the optical path of the image light LT. As will be described later, the pixel shift device 10 has an optical element 20, which is a light-transmitting substrate that transmits the image light LT, and by changing the posture of this optical element 20, the optical path of the image light LT is shifted using refraction.

[0028] The pixel shift device 10 swings the optical element 20 in two directions: a first swing direction about a first swing axis intersecting the optical axis AX; and a second swing direction about a second swing axis intersecting the optical axis AX and the first swing axis. When the optical element 20 swings in the first swing direction, the optical path of light incident on the optical element 20 shifts in a first direction F1 shown in FIG. 2. When the optical element 20 swings in the second swing direction, the optical path of light incident on the optical element 20 shifts in a second direction F2 intersecting the first direction F1 shown in FIG. 2. As a result, pixels Px displayed on the screen SCR are displayed at positions shifted in the first direction F1 and the second direction F2 intersecting the first direction F1. In this embodiment, the first direction F1 corresponds to the left-right direction X, and the second direction F2 corresponds to the up-down direction Z.

[0029] By combining the shift of the optical path in the first direction F1 and the shift of the optical path in the second direction F2, the projector 1 increases the apparent number of pixels and increases the resolution of the image light LT projected onto the screen SCR. For example, as shown in FIG. 2, the projector 1 shifts the pixel Px to a position shifted by 1 / 2 pixel in both the first direction F1 and the second direction F2. This allows the image display position on the screen SCR to be shifted to an image display position P2 shifted by 1 / 2 pixel along the first direction F1 from the image display position P1, to an image display position P3 shifted by 1 / 2 pixel along the first direction F1 and the second direction F2 from the image display position P1, and to an image display position P4 shifted by 1 / 2 pixel along the second direction F2 from the image display position P1. FIG. 2 focuses on a 1 / 4 region of the pixel Px and shows the flow of the shift operation from A to B to C to D.

[0030] As shown in Figure 2, an optical path shift operation is performed to display images at image display positions P1, P2, P3, and P4 for a fixed period of time, and the display content on each liquid crystal panel 4RP, 4GP, and 4BP is changed in synchronization with the optical path shift operation. This allows pixels A, B, C, and D, which appear to be smaller than pixel Px, to be displayed. For example, if pixels A, B, C, and D are displayed at an overall frequency of 60 Hz, each liquid crystal panel 4RP, 4GP, and 4BP must display at four times the normal speed for image display positions P1, P2, P3, and P4. In other words, the frame rate, which is the frequency at which images are displayed on each liquid crystal panel 4RP, 4GP, and 4BP, is 240 Hz.

[0031] In the example shown in FIG. 2, the first direction F1 and the second direction F2 are mutually orthogonal directions, and are the arrangement directions of the pixels Px displayed in a matrix on the screen SCR. Alternatively, the first direction F1 and the second direction F2 do not have to be mutually orthogonal directions, and may be inclined with respect to the arrangement direction of the pixels Px. Even in such a shift direction, by appropriately combining pixel shifts in the first direction F1 and the second direction F2, the pixels Px can be moved to the image display positions P1, P2, P3, and P4 shown in FIG. 2. Furthermore, the amount of shift of the image display position is not limited to 1 / 2 pixel, and may be, for example, 1 / 4 or 3 / 4 of the pixel Px.

[0032] Next, we will explain the configuration of the pixel shift device 10. Fig. 3 is a plan view of the pixel shift device 10. Fig. 3 is a plan view of the pixel shift device 10 viewed from the -Y side toward the +Y side. As shown in FIG. 3, the pixel shift device 10 includes an optical member 20, a first frame 21, a second frame 22, a base 23, a pair of first oscillation axis forming portions 24, a pair of first actuators 25, a pair of second actuators 26, and a pair of second oscillation axis forming portions 27. FIG. 3 shows a state in which the pixel shifting device 10 does not change the attitude of the optical member 20, that is, a state in which the pixel shifting device 10 is not operating.

[0033] The pixel shift device 10 shifts the optical path of the image light LT according to the attitude of the optical member 20 onto which the image light LT is incident from the image generation unit 4. As shown in FIG. 2 , the shift amount of the optical path of the image light LT is determined according to the degree of change in attitude of the optical member 20.

[0034] The optical member 20 is a member that uses refraction to shift the optical path of the image light LT incident from the image generation unit 4. When the pixel shift device 10 is in a reference position where the angle of incidence of the image light LT with respect to the optical member 20 is 0°, the normal direction of the optical member 20 coincides with the front-rear direction Y.

[0035] For example, a substantially square white glass plate is used as the optical member 20. By using white glass plate, which has excellent strength, the rigidity of the entire optical member 20 is increased, and distortion occurring in the optical member 20 can be suppressed. The material of the optical member 20 is not limited to white plate glass, but may be any material that is optically transparent and capable of refracting light, such as borosilicate glass or quartz glass. Alternatively, various crystal materials such as quartz or sapphire, or various resin materials such as polycarbonate resin or acrylic resin may be used. The shape of the optical member 20 is not limited to a substantially square, but may be rectangular, diamond, or elliptical.

[0036] The first frame 21 is a frame that swings around a first swing axis J1. The first swing axis J1 of the first frame 21 is an imaginary axis that passes through the center of the optical member 20 supported by the first frame 21.

[0037] The first frame 21 is made of a plate material that is approximately octagonal in plan view, and has an approximately octagonal opening 21H. The second frame 22 that holds the optical member 20 is disposed inside the opening 21H of the first frame 21. That is, the first frame 21 is made of a frame-shaped member that surrounds the second frame 22, and is disposed around and connected to the second frame 22.

[0038] The second frame 22 is a frame that holds the optical element 20 and swings around a second swing axis J2 that is perpendicular to the first swing axis J1. The second swing axis J2 of the second frame 22 is a virtual axis that is perpendicular to the first swing axis J1 and passes through the center of the optical element 20 supported by the second frame 22.

[0039] The second frame 22 is a metal frame in the shape of a picture frame, and is arranged around the optical element 20. The second frame 22 supports the outer periphery of the optical element 20, thereby housing the optical element 20 with its front and back surfaces exposed. The second frame 22 is made of a metal material having a predetermined rigidity, such as stainless steel. The optical element 20 is fixed to the second frame 22 with an adhesive. Note that the second frame 22 is not limited to a frame shape, and may be any member that supports at least a portion of the optical element 20.

[0040] The first frame 21 is connected to the base 23 via a pair of first oscillation shaft forming portions 24. The second frame 22 is connected to the first frame 21 via a pair of second oscillation shaft forming portions 27. The configurations of the pair of first oscillation shaft forming portions 24 and the pair of second oscillation shaft forming portions 27 will be described later.

[0041] Based on this configuration, the pixel shift device 10 of this embodiment can change its posture by rotating the optical element 20 supported on the first frame 21 via the second frame 22 around two axes, the first oscillation axis J1 or the second oscillation axis J2, relative to the base 23.

[0042] In this embodiment, the first frame 21 and the second frame 22 are arranged so that at least a portion of them overlap in the front-rear direction Y. That is, the first frame 21 and the second frame 22 are arranged so that at least a portion of them are on the same plane parallel to the XZ plane. Note that the first frame 21 may have a shape that surrounds the periphery of the second frame 22 when viewed in a plan view in the front-rear direction Y, and the position of the first frame 21 relative to the second frame 22 may be shifted in the front-rear direction Y. That is, the first frame 21 and the second frame 22 may be arranged so that their positions are shifted from each other in the front-rear direction Y.

[0043] The base 23 is made of a metal member such as aluminum. The base 23 has an opening 230 that surrounds the periphery of the first frame 21. The inner peripheral edge of the opening 230 has a first recess 231 provided on the right side in the left-right direction X and a second recess 232 provided on the left side in the left-right direction X. The first recess 231 and the second recess 232 are provided symmetrically in the left-right direction X on the second oscillation axis J2. A pair of first actuators 25 are disposed in the first recess 231 and the second recess 232, respectively.

[0044] In this embodiment, the first frame 21 and the base 23 are arranged so that at least a portion of them overlap in the front-rear direction Y. That is, the first frame 21 and the base 23 are arranged so that at least a portion of them are on the same plane parallel to the XZ plane. Note that the base 23 may have a shape that surrounds the periphery of the first frame 21 when viewed in a plan view in the front-rear direction Y, and its position relative to the first frame 21 may be shifted in the front-rear direction Y. That is, the first frame 21 and the base 23 may be arranged so that their positions are shifted from each other in the front-rear direction Y.

[0045] Each of the pair of first actuators 25 generates a driving force between the first frame 21 and the base 23 that causes the first frame 21 to swing relative to the base 23. In this embodiment, each of the first actuators 25 has a first magnet 25a arranged on the first frame 21 and a first coil 25b arranged on the base 23 and facing the first magnet 25a. The first actuator 25 in this embodiment is configured with a voice coil motor. This makes it easy to miniaturize the device configuration and enables precise positioning.

[0046] The first actuators 25 are arranged symmetrically on both sides of the optical member 20 held by the second frame 22 in the left-right direction X, with the first oscillation axis J1 as the center. The pair of first actuators 25 are positioned equidistant from the first oscillation axis J1, and therefore can transmit their respective driving forces in a well-balanced manner to the first frame 21 that holds the second frame 22. Therefore, the pixel shift device 10 of this embodiment can rotate the optical member 20 held by the second frame 22 around the first oscillation axis J1 without bias, using the pair of first actuators 25.

[0047] FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 3, showing the main configuration of the first actuator 25. As shown in FIG. 4, in the first actuator 25, the first magnet 25a is disposed on the first frame 21 via the first magnet holder 28. Specifically, the first magnet 25a is disposed on the first magnet holder 28, which is provided in a portion of the first frame 21 that is located on the second oscillation axis J2. The first magnet holder 28 is made of a sheet metal member made of a metal such as iron. Note that the magnet used for the first magnet 25a may be a neodymium magnet or any permanent magnet having a predetermined magnetic force, such as a samarium-cobalt magnet, a ferrite magnet, or an alnico magnet.

[0048] First coil 25b is arranged in first recess 231 or second recess 232 of base 23 shown in FIG. 3 via first coil holder 29. First coil holder 29 is fixed to base 23, and first coil 25b and first magnet 25a are arranged facing each other with a gap between them. First coil holder 29 is made of a metal such as iron. First coil 25b is made of an oval-shaped air-core coil arranged in first coil holder 29.

[0049] The first coil 25b is positioned and fixed to the first coil holder 29 so that two effective sides 251, 252 extending in the left-right direction X are aligned in the up-down direction Z.

[0050] The first magnet 25a has an S pole and an N pole aligned in the vertical direction on the surface facing the first coil 25b. When the optical member 20 and the first frame 21 are positioned at a reference position where the normal direction of the optical member 20 is parallel to the vertical direction Z, that is, a position where the angle of incidence of the image light LT on the optical member 20 is 0°, the first actuator 25 is such that one of the S pole and the N pole of the first magnet 25a faces the effective side 251, and the other faces the effective side 252.

[0051] When current is applied to the first coil 25b, current flows in opposite directions through the effective sides 251, 252 of the first coil 25b held by the first coil holder 29, causing the first magnet 25a to move relatively in the vertical direction Z, i.e., in a direction intersecting the surface of the optical member 20. This generates a driving force about the first oscillation axis J1 on the first frame 21 that holds the first magnet 25a. In the first actuator 25, the sheet metal members that make up the first magnet holder 28 and the first coil holder 29 function as a back yoke, thereby reducing leakage magnetic flux and increasing magnetic efficiency.

[0052] In the first actuator 25, the positions of the first magnet 25a and the first coil 25b can be interchanged, and the first magnet 25a may be placed in the first recess 231 or the second recess 232 of the base 23, and the first coil 25b may be placed in a coil holder provided in the first frame 21.

[0053] Each of the pair of second actuators 26 generates a driving force between the first frame 21 and the second frame 22 that swings the optical element 20 held by the second frame 22 relative to the first frame 21. Each of the pair of second actuators 26 has a second magnet 26a arranged on the second frame 22 and a second coil 26b arranged on the first frame 21 and facing the second magnet 26a. The second actuator 26 in this embodiment is configured with a voice coil motor. This makes it easy to miniaturize the device configuration and enables precise positioning.

[0054] The pair of second actuators 26 are arranged symmetrically on both sides of the optical element 20 held by the second frame 22 in the vertical direction Z, with the second oscillation axis J2 as the center. The pair of second actuators 26 are positioned equidistant from the second oscillation axis J2, and therefore can transmit their respective driving forces in a well-balanced manner to the second frame 22 that holds the optical element 20. Therefore, the pixel shift device 10 of this embodiment can rotate the optical element 20 held by the second frame 22 around the second oscillation axis J2 without bias, using the pair of second actuators 26.

[0055] The second magnet 26a is disposed on the second frame 22 via a second magnet holder 30. Specifically, the second magnet 26a is disposed on the second magnet holder 30, which is provided in a portion of the second frame 22 that is located on the first oscillation axis J1. The second magnet holder 30 is formed of a sheet metal member made of a metal such as iron. The magnet used for the second magnet 26a may be a neodymium magnet or any permanent magnet having a predetermined magnetic force, such as a samarium-cobalt magnet, a ferrite magnet, or an alnico magnet.

[0056] The second coil 26b is disposed on the first frame 21 via a second coil holder 31. Specifically, the second coil 26b is disposed on the second coil holder 31, which is provided on the inner circumferential surface of the first frame 21 at a position located on the first oscillation axis J1, and the second coil 26b and the second magnet 26a are disposed opposite each other with a gap in between. The second coil holder 31 is made of a metal such as iron. The second coil 26b is constituted by an oval-shaped air-core coil disposed on the second coil holder 31.

[0057] When current is applied to the second coil 26b, currents flow in opposite directions through the pair of effective sides of the second coil 26b held by the second coil holder 31, causing the second magnet 26a to move relatively in the vertical direction Z, i.e., in a direction intersecting the surface of the optical member 20. This generates a driving force about the second oscillation axis J2 on the second frame 22 that holds the second magnet 26a. In the second actuator 26, the sheet metal members that make up the second magnet holder 30 and the second coil holder 31 function as a back yoke, thereby reducing leakage magnetic flux and increasing magnetic efficiency.

[0058] In addition, in the second actuator 26, the positions of the second magnet 26a and the second coil 26b can be interchanged, and the second magnet 26a may be placed in a magnet holder provided on the first frame 21, and the second coil 26b may be placed in a coil holder provided on the second frame 22.

[0059] In this embodiment, the first actuator 25 and the second actuator 26, which are voice coil motors, hold the optical element 20 at a reference position when the magnetic characteristics between the magnets and the coils are stable, for example, when the first coil 25b and the second coil 26b are not energized. In this specification, the state in which the magnetic characteristics are stable is referred to as the "magnetic neutral point." At the magnetic neutral point, no driving force is generated between the magnets and the coils of the first actuator 25 and the second actuator 26, so the optical element 20 is held stably at the reference position.

[0060] According to the pixel shift device 10 of this embodiment, the optical member 20 can be held at the reference position by utilizing the magnetic neutral point without using a mechanical structure. Therefore, the oscillation angle of the optical member 20 can be controlled easily and with high precision.

[0061] The pair of first oscillation axis forming portions 24 connect the first frame 21 and the base 23 at positions sandwiching both sides of the first frame 21 in the up-down direction Z, which is the direction along the first oscillation axis J1. The pair of second oscillation axis forming portions 27 connect the second frame 22 and the first frame 21 at positions sandwiching both sides of the second frame 22 in the left-right direction X, which is the direction along the second oscillation axis J2.

[0062] Next, we will explain the configurations of the first oscillation shaft forming portion 24 and the second oscillation shaft forming portion 27. Fig. 5 is a cross-sectional view taken along line VV in Fig. 3, and Fig. 6 is a cross-sectional view taken along line VI-VI in Fig. 3. As shown in FIG. 5, the first oscillation shaft forming portion 24 includes a first shaft member 40, a first shaft support member 41, and a first bearing member 42. The first shaft member 40 extends from the inner surface 230a of the opening 230 of the base 23 along the first oscillation axis J1 and supports the first bearing member 42 on a bearing holder 40a located on the tip side. The first bearing member 42 includes a first inner ring raceway 420, a first outer ring raceway 421, and a plurality of first rolling elements 422 formed of spherical members and arranged between the first inner ring raceway 420 and the first outer ring raceway 421. The first bearing member 42 in this embodiment is a so-called ball bearing. The first inner ring raceway 420 is a ring-shaped member fixed to the first shaft member 40, and a plurality of first rolling elements 422 are arranged along its outer circumferential surface. The first outer raceway ring 421 is arranged to cover the outer periphery of the first inner raceway ring 420, and sandwiches a plurality of first rolling elements 422 between the inner peripheral surface of the first outer raceway ring 421 and the outer peripheral surface of the first inner raceway ring 420. The first shaft support member 41 is provided on the outer surface 21a of the first frame 21, and holds a first outer ring raceway 421 of the first bearing member .

[0063] Based on this configuration, the first oscillation axis forming portion 24 is configured so that the first shaft support member 41 attached to the first outer ring raceway 421 can rotate about the first oscillation axis J1 relative to the first inner ring raceway 420 fixed to the first shaft member 40 extending from the base 23 via a plurality of first rolling elements 422. Therefore, in the pixel shift device 10 of this embodiment, the first oscillation axis forming portion 24 allows the first frame 21 to rotate smoothly about the first oscillation axis J1 relative to the base 23.

[0064] The second oscillation shaft forming portion 27 has the same configuration as the first oscillation shaft forming portion 24 . 6, the second oscillation shaft forming portion 27 has a second shaft member 50, a second shaft support member 51, and a second bearing member 52. The second shaft member 50 extends from the outer surface 22a of the second frame 22 along the second oscillation axis J2, and supports the second bearing member 52 on a bearing holder 50a located on the tip side. The second bearing member 52 is provided on the inner surface 21b of the first frame 21, and holds the second bearing member 52. The second bearing member 52 is a so-called ball bearing that includes a second inner ring raceway 520, a second outer ring raceway 521, and a plurality of second rolling elements 522.

[0065] Based on this configuration, the second oscillation axis forming portion 27 is configured so that the second shaft support member 51 attached to the second outer ring raceway 521 can rotate about the second oscillation axis J2 relative to the second inner ring raceway 520 fixed to the second shaft member 50 extending from the second frame 22 via the plurality of second rolling elements 522. Therefore, in the pixel shift device 10 of this embodiment, the second oscillation axis forming portion 27 allows the second frame 22 to rotate smoothly about the second oscillation axis J2 relative to the first frame 21.

[0066] Here, a comparative example will be described in which the first oscillation axis forming portion 24 and the second oscillation axis forming portion 27 are made of sheet metal members. For example, if the first oscillation axis forming portion 24 connecting the base 23 and the first frame 21 is made of a leaf spring-shaped shaft made of sheet metal member, when the first frame 21 oscillates relative to the base 23, the shaft will be twisted with a predetermined stress applied. If, in order to ensure the rigidity of the shaft, the output of the first actuator 25 is suppressed and pressure is applied to the shaft in a region within elastic deformation that does not cause fatigue fracture, the oscillation angle of the optical member 20 will be reduced, and the shift amount of the image light LT will be reduced.

[0067] Consider, for example, a case in which the thickness of the glass plate constituting the optical member 20 is increased to increase the shift amount and suppress the oscillation angle while increasing the shift amount of the image light LT. In this case, the weight of the optical member 20 increases, causing the natural frequency to decrease from the conventional design value, and therefore it becomes necessary to widen the width of the stem to ensure that the natural frequency remains at a predetermined value. However, in order to deform the stem, whose rigidity has increased due to the increased width, it becomes necessary to drive the first actuator 25 with a higher output, making it difficult to ensure the rigidity of the stem. Furthermore, increasing the thickness of the glass plate constituting the optical member 20 increases the size of the pixel shift device, making it difficult to ensure the space between the pixel shift device and surrounding optical components.

[0068] Next, consider the case where a high refractive index material is used for the glass plate that constitutes the optical member 20, thereby increasing the amount of refraction and suppressing the oscillation angle, while increasing the amount of shift of the image light LT. In this case, although there is no increase in the weight of the optical member 20, the use of a high refractive index material may result in a decrease in display quality due to chromatic aberration, etc. For this reason, it is difficult to simply select a high refractive index material as the material for the optical member 20.

[0069] In contrast, in the pixel shift device 10 of this embodiment, the first oscillation axis forming portion 24 and the second oscillation axis forming portion 27 have the first bearing member 42 and the second bearing member 52 made of ball bearings, and therefore the optical element 20 can be smoothly oscillated around the first oscillation axis J1 and the second oscillation axis J2. In the pixel shift device 10 of this embodiment, when the optical member 20 is rotated around the first oscillation axis J1 and the second oscillation axis J2, no stress due to torsion is generated in the first oscillation axis forming portion 24 and the second oscillation axis forming portion 27. Therefore, in the pixel shift device 10 of this embodiment, defects such as fatigue due to stress are unlikely to occur in the first oscillation axis forming portion 24 and the second oscillation axis forming portion 27, and high rigidity is ensured.

[0070] The pixel shift device 10 of this embodiment can drive the first actuator 25 and the second actuator 26 with a large output because the rigidity of the first oscillation axis forming portion 24 and the second oscillation axis forming portion 27 is ensured. Note that in the pixel shift device 10 of this embodiment, the ball bearings allow the optical member 20 to rotate smoothly, so the outputs of the first actuator 25 and the second actuator 26 can be transmitted efficiently. Therefore, according to the pixel shift device 10 of this embodiment, the optical member 20 can be oscillated at a large oscillation angle while ensuring the rigidity of the first oscillation axis forming portion 24 and the second oscillation axis forming portion 27.

[0071] In this way, the pixel shift device 10 of this embodiment can increase the shift amount of the image light LT by swinging the optical element 20 greatly without increasing the thickness of the optical element 20 or using a material with a high refractive index as the optical element 20. Therefore, the pixel shift device 10 of this embodiment can realize a high-quality pixel shift device that ensures both the rigidity of the shaft that swings the optical member 20 and the display quality achieved by pixel shifting.

[0072] Here, when the first bearing member 42 and the second bearing member 52 made of ball bearings are used, there is a risk of vibration occurring due to backlash in the first bearing member 42 and the second bearing member 52. In contrast, the pixel shift device 10 of this embodiment applies a predetermined preload to the first bearing member 42 and the second bearing member 52, thereby suppressing backlash in the first bearing member 42 and the second bearing member 52.

[0073] Furthermore, the inventors have found that the natural frequency of the pixel shift device 10 can be adjusted by adjusting the strength of the preload on the first bearing member 42 and the second bearing member 52. Based on this finding, the inventors have completed the pixel shift device 10 of this embodiment, in which the natural frequency is set to a predetermined value by adjusting the amount of preload on the first bearing member 42 and the second bearing member 52.

[0074] Next, a description will be given of a method for applying a preload to the first bearing member 42 and the second bearing member 52. A method for applying a preload to the first bearing member 42 will be described below. FIG. 7A is a diagram showing a state in which pressure is applied to the first inner raceway ring 420 of the first bearing member 42. As shown in FIG. 7A, the first oscillation shaft forming portion 24 has an inner raceway side pressing member 430 that presses the first inner raceway ring 420. The inner raceway side pressing member 430 is disposed at the base of the bearing holder 40a of the first shaft member 40. The first bearing member 42 is supported by the first shaft support member 41 in a state in which the first inner raceway ring 420 is movable in the axial direction along the first oscillation axis J1. The inner raceway side pressing member 430 can be a member having a predetermined thickness, such as a washer or a collar, sandwiched between the first inner raceway ring 420 and the first inner raceway ring 420, thereby applying a fixed-position preload to the first inner raceway ring 420. Furthermore, the inner raceway side pressing member 430 can be a member that applies a predetermined pressure, such as a coil spring or a disc spring, thereby applying a fixed-pressure preload to the first inner raceway ring 420. Based on this configuration, the first oscillation shaft forming portion 24 can apply a preload to the first inner ring raceway ring 420 in the axial direction along the first oscillation axis J1 by using the inner ring side pressing member 430.

[0075] 7B is a diagram showing a state in which pressure is applied to the first outer ring raceway 421 of the first bearing member 42. As shown in FIG. 7B, the first oscillation shaft forming portion 24 may have an outer ring side pressing member 431 that presses the first outer ring raceway 421 instead of the inner ring side pressing member 430. The outer ring side pressing member 431 is disposed at the tip of a protrusion 406 that protrudes from the outer edge of the first shaft member 40 so as to surround the periphery of the bearing holder 40a. The first bearing member 42 is supported by the first shaft support member 41 in a state in which the first outer ring raceway 421 is movable in the axial direction along the first oscillation axis J1. For example, a member having a predetermined thickness, such as a washer or collar, may be sandwiched as the outer ring side pressing member 431 to apply a fixed position preload to the first outer ring raceway 421. Furthermore, by sandwiching a member that applies a predetermined pressure, such as a coil spring or a disc spring, as the outer ring side pressing member 431, a constant pressure preload can be applied to the first outer ring raceway ring 421. Based on this configuration, the first oscillation shaft forming portion 24 can apply a preload to the first outer ring raceway ring 421 in the axial direction along the first oscillation axis J1 by using the outer ring side pressing member 431.

[0076] When comparing position preload and constant pressure preload, position preload results in less axial displacement for the same amount of preload. On the other hand, constant pressure preload has the ability to absorb load fluctuations and expansion / contraction due to temperature differences with a spring, resulting in less fluctuation in the amount of preload and a stable amount of preload. In this way, position preload is suitable for applications where high rigidity is required, while constant pressure preload is suitable for applications where axial vibration needs to be prevented.

[0077] As with the first bearing member 42, the second bearing member 52 can also be preloaded in a fixed position or a constant pressure by using an inner ring side pressing member 430 or an outer ring side pressing member 431 depending on the application.

[0078] As described above, according to the pixel shift device 10 of this embodiment, by using the inner ring side pressing member 430 or the outer ring side pressing member 431, a predetermined preload is applied to the first bearing member 42 and the second bearing member 52, and the natural frequency of the pixel shift device 10 can be set to any value.

[0079] In the projector 1 of this embodiment, the natural frequency of the pixel shift device 10 is set to a frequency that is shifted from the resonance frequency of the frame rate, which is the frequency of image display in the light modulation devices 4B, 4G, and 4R of the image generation unit 4. The projector 1 of this embodiment can suppress the occurrence of resonance with the frame rate of the image generation unit 4 by adjusting the strength of the preload applied to the first bearing member 42 and the second bearing member 52 in the pixel shift device 10 as described above. This makes it possible to suppress the occurrence of problems such as vibration and noise due to resonance.

[0080] Next, the operation of the pixel shift device 10 of this embodiment will be described. In the pixel shift device 10 of this embodiment, in each first actuator 25, a circuit board (not shown) is used to pass current through the first coil 25b, generating a magnetic field that repels or attracts the first magnet 25a, thereby generating a force between the first magnet 25a and the first coil 25b in a direction intersecting the first oscillation axis J1. This causes the first frame 21 to oscillate around the first oscillation axis J1. As described above, the first frame 21 is connected to the base 23 through a pair of first oscillation axis forming portions 24 located at both ends in the direction along the first oscillation axis J1, so that the optical member 20 fixed to the first frame 21 via the second frame can oscillate around the first oscillation axis J1 relative to the base 23.

[0081] Furthermore, in the pixel shift device 10 of this embodiment, in each second actuator 26, a circuit board (not shown) is used to energize the second coil 26b, generating a magnetic field that repels or attracts the second magnet 26a, thereby generating a force between the second magnet 26a and the second coil 26b in a direction intersecting the second oscillation axis J2. This causes the second frame 22 to oscillate around the second oscillation axis J2. As described above, the second frame 22 is connected to the first frame 21 through a pair of second oscillation axis forming portions 27 located at both ends in the direction along the second oscillation axis J2. Therefore, the optical member 20 fixed to the second frame 22 can oscillate around the second oscillation axis J2 relative to the first frame 21.

[0082] In this way, the pixel shift device 10 of this embodiment can control the attitude of the optical member 20 in two axes by utilizing the driving forces of the pair of first actuators 25 and the pair of second actuators 26. By changing the attitude of the optical member 20, the pixel shift device 10 can shift the optical path of the image light LT emitted from the image generation unit 4 in directions along two axes.

[0083] In the present embodiment, when the first frame 21 swings around the first swing axis J1, the angle of incidence of the image light LT with respect to the optical member 20 changes, and the optical path of the image light LT moves in the second direction F2 (see FIG. 2). Furthermore, when the second frame 22 that holds the first frame 21 swings around the second swing axis J2, the angle of incidence of the image light LT with respect to the optical member 20 changes in a direction different from when swinging around the first swing axis J1, and the optical path of the image light LT moves in the first direction F1 (see FIG. 2).

[0084] As described above, the pixel shift device 10 of this embodiment includes the base 23, the first frame 21 that oscillates around the first oscillation axis J1 relative to the base 23, the optical member 20 supported by the first frame 21, the first oscillation axis forming portion 24 that connects the first frame 21 and the base 23 at positions sandwiching both sides of the first frame 21 in the vertical direction Z along the first oscillation axis J1, and the first actuator 25 that oscillates the first frame 21 relative to the base 23. The first oscillation axis forming portion 24 has a first shaft member 40 and a first bearing member 42. The first bearing member 42 includes a first inner ring raceway 420 fixed to the first shaft member 40, a first outer ring raceway 421, and a plurality of first rolling elements 422 arranged between the first inner ring raceway 420 and the first outer ring raceway 421. The optical element 20 is further provided with a second frame 22 that holds the optical element 20 and swings relative to the first frame 21 about a second swing axis J2 that is perpendicular to the first swing axis J1, a second swing axis forming section 27 that connects the second frame 22 and the first frame 21 at positions that sandwich both sides of the second frame 22 in the left-right direction X along the second swing axis J2, and a second actuator 26 that swings the second frame 22 relative to the first frame 21. The second swing axis forming section 27 has a second shaft member 50 and a second bearing member 52. The second bearing member 52 is made up of a second inner ring raceway 520 fixed to the second shaft support member 51, a second outer ring raceway 521, and a plurality of second rolling elements 522 arranged between the second inner ring raceway 520 and the second outer ring raceway 521.

[0085] According to the pixel shift device 10 of this embodiment, when the optical member 20 is rotated around the first oscillation axis J1 and the second oscillation axis J2, no stress due to torsion is generated in the pair of first oscillation axis forming portions 24 connecting the base 23 and the first frame 21 and in the pair of second oscillation axis forming portions 27 connecting the second frame 22 and the first frame 21. Therefore, the pixel shift device 10 of this embodiment ensures the rigidity of the first oscillation axis forming portions 24 and the second oscillation axis forming portions 27, so that the first actuator 25 and the second actuator 26 can be driven with a large output, and the optical member 20 can be oscillated at a large oscillation angle. Therefore, the pixel shift device 10 of this embodiment can provide a pixel shift device that provides high-quality display with excellent durability by ensuring both rigidity and display quality achieved by pixel shifting.

[0086] The pixel shift device 10 of this embodiment can suppress the occurrence of resonance with the frame rate of the image generation unit 4 by adjusting the strength of the preload applied to the first bearing member 42 and the second bearing member 52, thereby providing a highly reliable pixel shift device that suppresses the occurrence of problems such as vibration and noise caused by resonance.

[0087] In the pixel shift device 10 of this embodiment, the preload can suppress rattles in the first bearing member 42 and the second bearing member 52, so that no mechanical rattles are generated, and thus noises generated during driving can be minimized.

[0088] The pixel shift device 10 of this embodiment can hold the optical element 20 at a reference position by utilizing the magnetic neutral points of the first actuator 25 and the second actuator 26, so that the oscillation angle of the optical element 20 can be controlled easily and with high precision without using a mechanical structure.

[0089] The projector 1 of this embodiment is equipped with the pixel shift device 10, and is therefore highly durable and capable of projecting high-quality images. Furthermore, the projector 1 of this embodiment can provide a projector that is quieter during operation by suppressing the occurrence of problems such as vibration and noise due to resonance by shifting the natural frequency of the pixel shift device 10 from the resonance frequency of the frame rate of the light modulation devices 4B, 4G, and 4R of the image generation unit 4.

[0090] The technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. Furthermore, the specific configurations such as the number, arrangement, shape, and materials of the various components that make up the pixel shift device or projector are not limited to those in the above embodiment, and can be modified as appropriate. For example, the pixel shift device 10 in the above embodiment is exemplified as having a pair of first actuators 25 and second actuators 26, but a configuration having one first actuator 25 and one second actuator 26 may also be adopted.

[0091] (First Modification) For example, in the above embodiment, the optical member 20 is held at the reference position by utilizing the magnetic neutral points of the first actuator 25 and the second actuator 26, but the present invention is not limited to this.

[0092] 8 is a side view showing a schematic configuration of a pixel shift device of this modified example. Note that in this modified example, the same components as those in the above embodiment are denoted by the same reference numerals, and detailed descriptions thereof will be omitted.

[0093] 8 , the pixel shift device 10A of this modified example includes a holding force applying portion 60 that applies a holding force to the first frame 21 to hold the optical member 20 at the reference position. The holding force applying portion 60 has a main body portion 61 and a pair of leaf spring portions 62 extending from the main body portion 61. The main body portion 61 is fixed to the base 23 in an area not shown. One of the pair of leaf spring portions 62 has an end portion opposite to the main body portion 61 that applies a pressing force to the surface on the +Y side of the first frame 21, and the other of the pair of leaf spring portions 62 has an end portion opposite to the main body portion 61 that applies a pressing force to the surface on the -Y side of the first frame 21.

[0094] According to the pixel shift device 10A of this modification, the pressing forces of the pair of leaf spring portions 62 of the holding force imparting portion 60 cancel each other out, so that the optical member 20 can be held more stably at the reference position.

[0095] For example, the tip end of the leaf spring portion 62 may be fixed to the first frame 21. In this case, when the first frame 21 rotates around the first oscillation axis J1, the pair of leaf spring portions 62 elastically deform in response to the first frame 21, generating a biasing force that returns the first frame 21 to the reference position. Therefore, by utilizing the biasing force of the leaf spring portions 62, it is possible to return the optical member 20 to the reference position without applying electricity to the first actuator 25 and the second actuator 26. This makes it possible to reduce power consumption in the first actuator 25 and the second actuator 26.

[0096] Furthermore, since the pixel shift device 10A of this modified example can stably hold the optical element 20 at a reference position using the holding force imparting portion 60, it can also be applied to cases where the first actuator 25 and the second actuator 26 do not have a sheet metal member that functions as a back yoke.

[0097] (Second Modification) This modification relates to an example of a different form of the holding force imparting portion. 9 is a side view showing a schematic configuration of a pixel shift device of this modified example. Note that in this modified example, the same components as those in the above embodiment are denoted by the same reference numerals, and detailed descriptions thereof will be omitted.

[0098] 9, the pixel shift device 10B of this modification includes a holding force applying unit 65 that applies a holding force to the first frame 21 to hold the optical member 20 at the reference position. The holding force applying unit 65 includes a first magnet pair 63 and a second magnet pair 64.

[0099] The first magnet pair 63 is composed of a pair of magnets 63a arranged on the surface on the +Y side of the first frame 21. One of the pair of magnets 63a is attached to the surface on the +Y side of the first frame 21, and the other of the pair of magnets 63a is arranged at a position spaced a predetermined distance from the one of the pair of magnets 63a. Because the pair of magnets 63a have the same polarity, they generate a repulsive force against each other.

[0100] The second magnet pair 64 is composed of a pair of magnets 64a arranged on the surface on the -Y side of the first frame 21. One of the pair of magnets 64a is attached to the surface on the -Y side of the first frame 21, and the other of the pair of magnets 64a is arranged at a position spaced a predetermined distance from one of the pair of magnets 64a. The pair of magnets 64a have the same polarity, and therefore generate a repulsive force between them.

[0101] According to the pixel shift device 10B of this modified example, the repulsive forces of the first magnet pair 63 and the second magnet pair 64 of the holding force imparting portion 65 cancel each other out, so that the optical member 20 can be held more stably at the reference position.

[0102] Furthermore, since the pixel shift device 10B of this modified example can stably hold the optical element 20 at a reference position using the holding force imparting portion 65, it can also be applied to cases where the first actuator 25 and the second actuator 26 do not have a sheet metal member that functions as a back yoke.

[0103] (Third Modification) The pixel shift device 10 of the above embodiment has been described as an example in which the optical element 20 is rotatable around two axes, the first oscillation axis J1 or the second oscillation axis J2, relative to the base 23, but a configuration in which the optical element 20 is rotatable around one axis relative to the base 23 may also be adopted.

[0104] This modification relates to the configuration of a pixel shift device that rotates an optical member around one axis. 10 is a plan view showing a schematic configuration of a pixel shift device of this modified example. Note that in this modified example, the same components as those in the above embodiment are denoted by the same reference numerals, and detailed descriptions thereof will be omitted.

[0105] As shown in FIG. 10, the pixel shift device 10C of this modified example includes an optical element 20, a first frame 112 that holds the optical element 20, a base 113 that connects the first frame 112 so that it can oscillate around a first oscillation axis J1, a first actuator 114 that oscillates the first frame 112, and a pair of first oscillation axis forming portions 111.

[0106] The pair of first oscillation shaft forming portions 111 are provided to protrude from a pair of diagonally positioned corners of the outer surface of the rectangular frame-shaped first frame 112, and connect the outer surface of the first frame 112 and the inner surface of the base 113. The first oscillation shaft forming portions 111 have the same configuration as the first oscillation shaft forming portion 24 of the above embodiment, and therefore detailed description thereof will be omitted.

[0107] The first actuator 114 has a first magnet 114a arranged on the outer surface of the first frame 112 in a direction intersecting the first oscillation axis J1, and a first coil 114b arranged on the inner surface of the base 113 and facing the first magnet 114a. Specifically, the first magnet 114a is provided via a first magnet holder 115 made of a sheet metal member functioning as a back yoke at one corner of the outer surface of the first frame 112 located on the other diagonal corner where the first oscillation axis forming part 111 is not provided. The first coil 114b is located on a diagonal line perpendicular to the first oscillation axis J1 on the inner surface of the base 113, and is arranged opposite the first magnet 114a via a first coil holder 116 made of a sheet metal member functioning as a back yoke.

[0108] Based on this configuration, the pixel shift device 10C of this modified example can control the posture of the optical element 20 around one axis by adjusting the amount of current flowing through the first coil 114b to oscillate the first frame 112 around the first oscillation axis J1.

[0109] According to the pixel shift device 10C of this modified example, when the optical element 20 is rotated around the first oscillation axis J1, no torsional stress is generated in the first oscillation axis forming portion 111 connecting the base 113 and the first frame 112, and therefore, the optical element 20 can be oscillated at a large oscillation angle by driving the first actuator 25 with a large output. Therefore, according to the pixel shift device 10C of this modified example, even in a configuration in which the optical member is rotated around one axis, similar to the pixel shift device 10 of the above embodiment, it is possible to achieve a pixel shift device that provides a high-quality display with excellent durability by ensuring both rigidity and display quality due to pixel shifting.

[0110] A summary of this disclosure is provided below. (Appendix 1) With the base, a first frame that swings relative to the base around a first swing axis; an optical member supported by the first frame; a first oscillation shaft forming portion that connects the first frame and the base at a position that sandwiches both sides of the first frame in a direction along the first oscillation shaft; a first actuator that swings the first frame relative to the base, The first oscillation shaft forming portion has a first shaft member and a first bearing member, The first bearing member is composed of a first inner raceway ring fixed to the first shaft member, a first outer raceway ring, and a plurality of first rolling elements arranged between the first inner raceway ring and the first outer raceway ring. 1. A pixel shifting device comprising:

[0111] With a pixel shift device having this configuration, when the optical member is rotated around the first oscillation axis, torsional stress is unlikely to occur in the first oscillation axis forming portion connecting the base and the first frame. Therefore, by ensuring the rigidity of the first oscillation axis forming portion, this pixel shift device can drive the first actuator with a large output, allowing the optical member to oscillate at a large oscillation angle. Therefore, with this pixel shift device, by ensuring both rigidity and pixel shift display quality, a high-quality display with excellent durability can be obtained.

[0112] (Appendix 2) the first oscillation shaft forming portion sets a natural frequency of the pixel shifting device by applying pressure in an axial direction to one of the first inner ring and the first outer ring. 2. The pixel shifting device according to claim 1,

[0113] According to this configuration, rattle in the first bearing member can be suppressed by the preload, so that mechanical rattle is not generated, and therefore noise generated during driving can be minimized.

[0114] (Appendix 3) The first oscillation shaft forming portion further includes an inner ring side pressing member that presses the first inner ring raceway. 3. The pixel shifting device according to claim 2,

[0115] According to this configuration, a preload can be applied to the first inner ring raceway in the axial direction along the first oscillation shaft by the inner ring side pressing member.

[0116] (Appendix 4) The first oscillation shaft forming portion further includes an outer ring side pressing member that presses the first outer ring raceway. 3. The pixel shifting device according to claim 2,

[0117] According to this configuration, a preload can be applied to the first outer ring raceway in the axial direction along the first oscillation axis by the outer ring side pressing member.

[0118] (Appendix 5) The first actuator is a voice coil motor having a coil and a magnet arranged opposite to each other. 5. The pixel shifting device according to claim 1, wherein the first and second electrodes are electrically connected to each other.

[0119] According to this configuration, by providing the first actuator made up of a voice coil motor, it is possible to easily reduce the size of the device configuration and enable precise positioning.

[0120] (Appendix 6) Further, a sheet metal member is provided to hold at least one of the coil and the magnet. 6. The pixel shifting device according to claim 5,

[0121] According to this configuration, the sheet metal member functions as a back yoke, so that leakage magnetic flux can be reduced and magnetic efficiency can be increased.

[0122] (Appendix 7) the first actuator holds the optical member at a reference position at a magnetic neutral point; Pixel shifting device according to claim 1, characterized in that:

[0123] According to this configuration, the optical member can be held at a reference position by utilizing the magnetic neutral point of the first actuator, so that the oscillation angle of the optical member can be controlled easily and with high precision without using a mechanical structure.

[0124] (Appendix 8) a holding force applying unit that applies a holding force to the first frame to hold the optical member at the reference position, 8. The pixel shifting device according to claim 7,

[0125] According to this configuration, the optical member can be more stably held at the reference position by the holding force imparting portion.

[0126] (Appendix 9) a second frame that holds the optical member and swings relative to the first frame about a second swing axis that is perpendicular to the first swing axis; a second oscillation shaft forming portion that connects the second frame and the first frame at a position that sandwiches both sides of the second frame in a direction along the second oscillation shaft; a second actuator that swings the second frame relative to the first frame, The second oscillation shaft forming portion has a second shaft member and a second bearing member, The second bearing member is composed of a second inner ring raceway fixed to the second shaft member, a second outer ring raceway, and a plurality of second rolling elements arranged between the second inner ring raceway and the second outer ring raceway. 9. The pixel shifting device according to claim 1, wherein the first and second electrodes are electrically connected to each other.

[0127] With this configuration, when the optical member is rotated around the second oscillation axis, no torsional stress is generated in the second oscillation axis forming portion connecting the second frame and the first frame, so that the optical member can be oscillated at a large oscillation angle by driving the second actuator with a large output. Therefore, with this configuration, it is possible to provide a pixel shift device that provides a high-quality display with excellent durability in a configuration in which the optical member is oscillated around two axes.

[0128] (Appendix 10) an image generating unit including a light modulation device that generates image light; a projection optical system that projects the image light; the pixel shifting device according to any one of Supplementary Note 1 to Supplementary Note 9, which is disposed between the image generating unit and the projection optical system and shifts an optical path of the image light from the image generating unit; A projector characterized by:

[0129] A projector having this configuration includes the pixel shift device, and therefore has excellent durability and can project high-quality images.

[0130] (Appendix 11) the natural frequency of the pixel shifting device is a frequency that is shifted from a resonance frequency of a frame rate that is a frequency of image display in the light modulation device of the image generating unit, 11. The projector according to claim 10.

[0131] According to this configuration, by shifting the natural frequency of the pixel shift device from the resonant frequency of the frame rate in the light modulation device of the image generation section, it is possible to provide a projector that suppresses the occurrence of problems such as vibrations and noise caused by resonance, thereby improving quietness during operation. [Explanation of symbols]

[0132] 1...Projector, 4...Image generating unit, 4B, 4G, 4R...Light modulation device, 6...Projection optical system, 10, 10A, 10B, 10C...Pixel shift device, 20...Optical member, 21, 112...First frame, 22...Second frame, 23, 113...Base, 24, 111...First oscillation axis forming unit, 25, 114...First actuator, 26...Second actuator, 27...Second oscillation axis forming unit , 40...first shaft member, 42...first bearing member, 50...second shaft member, 52...second bearing member, 60, 65...retaining force imparting portion, 420...first inner ring raceway, 421...first outer ring raceway, 422...first rolling element, 430...inner ring side pressing member, 431...outer ring side pressing member, 520...second inner ring raceway, 521...second outer ring raceway, 522...second rolling element, J1...first oscillating shaft, J2...second oscillating shaft, LT...image light.

Claims

1. With the base, a first frame that swings relative to the base about a first swing axis; an optical member supported by the first frame; a first oscillation shaft forming portion that connects the first frame and the base at a position sandwiching both sides of the first frame in a direction along the first oscillation shaft; a first actuator that swings the first frame relative to the base, the first oscillation shaft forming portion has a first shaft member and a first bearing member, The first bearing member is composed of a first inner raceway ring fixed to the first shaft member, a first outer raceway ring, and a plurality of first rolling elements arranged between the first inner raceway ring and the first outer raceway ring.

1. A pixel shifting device comprising:

2. the first oscillation shaft forming portion sets a natural frequency of the pixel shifting device by applying pressure in an axial direction to one of the first inner ring and the first outer ring.

2. The pixel shifting device according to claim 1.

3. The first oscillation shaft forming portion further includes an inner ring side pressing member that presses the first inner ring raceway.

3. The pixel shifting device according to claim 2.

4. The first oscillation shaft forming portion further includes an outer ring side pressing member that presses the first outer ring raceway.

3. The pixel shifting device according to claim 2.

5. the first actuator is a voice coil motor having a coil and a magnet arranged opposite to each other; 5. A pixel shifting device according to claim 1, wherein the pixel shifting device is a pixel shifting device.

6. Further, a sheet metal member is provided to hold at least one of the coil and the magnet.

6. The pixel shifting device according to claim 5.

7. the first actuator holds the optical member at a reference position at a magnetic neutral point; 6. The pixel shifting device according to claim 5.

8. a holding force applying portion that applies a holding force to the first frame to hold the optical member at the reference position, 8. The pixel shifting device according to claim 7.

9. a second frame that holds the optical member and swings relative to the first frame about a second swing axis that is perpendicular to the first swing axis; a second swing shaft forming portion that connects the second frame and the first frame at a position that sandwiches both sides of the second frame in a direction along the second swing shaft; a second actuator that swings the second frame relative to the first frame, the second oscillation shaft forming portion has a second shaft member and a second bearing member, The second bearing member is composed of a second inner raceway ring fixed to the second shaft member, a second outer raceway ring, and a plurality of second rolling elements arranged between the second inner raceway ring and the second outer raceway ring.

5. A pixel shifting device according to claim 1, wherein the pixel shifting device is a pixel shifting device.

10. an image generating unit including a light modulation device that generates image light; a projection optical system that projects the image light; the pixel shifting device according to claim 1 , which is disposed between the image generating unit and the projection optical system and shifts an optical path of the image light from the image generating unit; A projector characterized by:

11. the natural frequency of the pixel shifting device is a frequency that is shifted from a resonance frequency of a frame rate that is a frequency of image display in the light modulation device of the image generating unit, The projector according to claim 10 .

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