PIXEL SHIFTING DEVICE AND PROJECTOR

The present application is based on, and claims priority from JP Application Serial Number 2023-007153, filed Jan. 20, 2023, the disclosure of which is hereby incorporated by reference herein in its entirety.

BACKGROUND
1. Technical Field

The present disclosure relates to a pixel shifting device and a projector.

2. Related Art

In the past, there has been a projector equipped with a pixel shifting device for shifting a light path of image light emitted from a light modulation device such as a liquid crystal panel (see, e.g., JP-A-2020-91343).

The pixel shifting device in the projector described above is provided with a first frame for holding an optical member, a second frame which is arranged around the first frame to couple the first frame, a base which is arranged around the second frame to couple the second frame, a first actuator for oscillating the first frame around a first oscillation axis with respect to the second frame, and a second actuator for oscillating the second frame around a second oscillation axis with respect to the base.

In the pixel shifting device described above, there is adopted a layout in which the first actuator and the second actuator are collectively arranged at one side along an axial direction of the second oscillation axis to thereby make it possible to efficiently cool the actuators to be heat sources when driving the pixel shifting device.

In the pixel shifting device described above, there is provided a structure in which the second frame and the base are coupled to each other via a pair of shaft members formed to have the same width, the same length, and the same thickness on the second oscillation axis. Due to this configuration, it becomes difficult for the displacement of the second frame caused by the thrust force of the second actuator to propagate as getting away from the actuator, and therefore, there is created a state in which torsional angles by the pair of shaft members are different from each other. Therefore, in the pixel shifting device described above, the optical member cannot rotate around the second oscillation axis in a balanced manner due to the difference in torsional angle by the pair of shaft members, and therefore, it is difficult to accurately shift the light path of the image light.

Further, there is a possibility that there arises a problem that a difference occurs between the loads of the respective shaft members due to the difference in torsional angle, and thus, a variation occurs in durability of the respective shaft members.

SUMMARY

In view of the problems described above, according to an aspect of the present disclosure, there is provided a pixel shifting device including an optical member, a first frame which is configured to hold the optical member, and which oscillates around a first oscillation axis, a second frame which is arranged on a periphery of the first frame, which is coupled to the first frame, and which oscillates around a second oscillation axis perpendicular to the first oscillation axis, a base which is arranged on a periphery of the second frame, and which is coupled to the second frame, a pair of first oscillation shaft formation parts which are located on the first oscillation axis, and which are configured to couple the first frame and the second frame to each other, a pair of second oscillation shaft formation parts which are located on the second oscillation axis, and which are configured to couple the second frame and the base to each other, a first actuator which is arranged on the second oscillation axis, and which is configured to oscillate the first frame with respect to the second frame between the first frame and the second frame, and a second actuator which is constituted by two actuators arranged in an actuator holding part across the second oscillation axis, and which is configured to oscillate the second frame with respect to the base, the actuator holding part being disposed at a side of the second frame and the base where the first actuator is arranged, wherein the pair of second oscillation shaft formation parts include a one-side coupling shaft part configured to couple the second frame and the base to each other at the actuator holding parts side, and another-side coupling shaft part configured to couple the second frame and the base to each other at an opposite side to the actuator holding parts, and the another-side coupling shaft part is lower in rigidity than the one-side coupling shaft part.

Further, according to another aspect of the present disclosure, there is provided a projector including an image generator configured to generate image light, a projection optical system configured to project the image light, and the pixel shifting device according to the aspect described above which is arranged between the image generator and the projection optical system, and which is configured to shift a light path of the image light from the image generator.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing a schematic configuration of a projector according to an embodiment.

FIG. 2 is an explanatory diagram showing a principle of achieving high resolution of an image by a pixel shifting device.

FIG. 3 is a plan view of the pixel shifting device.

FIG. 4 is a cross-sectional view as an arrow view along the line IV-IV in FIG. 3.

FIG. 5 is a diagram showing a positional relationship between the pixel shifting device and an image generator.

FIG. 6 is a diagram showing a positional relationship between the pixel shifting device and the image generator.

FIG. 7 is a perspective view showing a configuration of an essential part of a second frame.

FIG. 8A is a displacement distribution diagram showing a first simulation result.

FIG. 8B is a displacement distribution diagram showing a second simulation result.

FIG. 9A is an enlarged view showing a configuration of an essential part of a pixel shifting device according to a modified example.

FIG. 9B is an enlarged view showing a configuration of an essential part of the pixel shifting device according to the modified example.

DESCRIPTION OF EMBODIMENTS

An embodiment of the present disclosure will hereinafter be described in detail with reference to the drawings. It should be noted that the drawings used in the following description show characteristic parts in an enlarged manner in some cases for the sake of convenience in order to make the features easy to understand, and the dimensional ratios between the constituents and so on are not necessarily the same as actual ones.

FIG. 1 is a diagram showing a schematic configuration of the projector according to the present embodiment.

As shown in FIG. 1, a projector 1 according to the present embodiment is provided with a light source 2, a color separation optical system 3, an image generator 4, a projection optical system 6, and a pixel shifting device 10.

Hereinafter, a layout relationship between members is described using an XYZ coordinate system shown in the drawings in some cases. In each of the drawings, the Y axis is an axis extending along a projection direction of image light LT with respect to a screen SCR in the projector 1. The X axis is an axis which is perpendicular to the Y axis, and extends along a width direction of the screen SCR. The Z axis is an axis which is perpendicular to the X axis and the Y axis, and extends along a vertical direction of the screen SCR.

In the present embodiment, for example, both directions along the Z axis are collectively referred to as a “vertical direction Z” in the projector 1, a direction toward the +Z direction is referred to as an “upper side”, and a direction toward the −Z direction is referred to as a “lower side”. Further, both directions along the X axis are collectively referred to as a “horizontal direction X” in the projector 1, a direction toward the +X direction is referred to as a “right side”, and a direction toward the −X direction is referred to as a “left side”. Further, both directions along the Y axis are collectively referred to as a “front-back direction Y” in the projector 1, a direction toward the +Y direction is referred to as a “front side”, and a direction toward the −Y direction is referred to as a “back side”.

It should be noted that the vertical direction Z, the horizontal direction X, and the front-back direction Y are mere denotations for describing layout relationships between constituent members of the projector 1, but are not ones for defining actual installation postures and directions in the projector 1.

The light source 2 has constituents such as a laser source and a wavelength conversion element. The light source 2 collects a blue laser beam emitted from the laser source as excitation light with a light collection lens to make the result enter a wavelength conversion element including a phosphor, and then emits white light WL consisting of the blue laser beam and yellow fluorescence. It should be noted that the light source 2 is not limited to the configuration using the laser source and the wavelength conversion element, but it is possible to apply, for example, a configuration using a laser source alone, or a configuration using an LED (Light Emitting Diode) or a discharge type light source lamp.

The image generator 4 has a light modulation device 4R for emitting red image light, a light modulation device 4G for emitting green image light, a light modulation device 4B for emitting blue image light, and a light combining element 5. The image generator 4 modulates the light emitted from the light source 2 based on image information to generate the image light LT.

The color separation optical system 3 is provided with 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, a relay lens 9a, and a relay lens 9b. The color separation optical system 3 separates the white light WL having been emitted from the light source 2 into red light LR, green light LG, and blue light LB.

The first dichroic mirror 7a separates the white light WL emitted from the light source 2 into the red light LR, and the green light LG and the blue light LB. The first dichroic mirror 7a transmits the red light LR, and reflects the green light LG and the blue light LB. The second dichroic mirror 7b separates light having the green light LG and the blue light LB mixed with each other into the green light LG and the blue light LB. The second dichroic mirror 7b reflects the green light LG, and at the same time, transmits the blue light LB.

The first reflecting mirror 8a is arranged in a light path of the red light LR. The first reflecting mirror 8a reflects the red light LR, which has been transmitted through the first dichroic mirror 7a, toward the light modulation device 4R. The second reflecting mirror 8b and the third reflecting mirror 8c are arranged in the light path of the blue light LB. The second reflecting mirror 8b and the third reflecting mirror 8c guide the blue light LB, which has been transmitted through the second dichroic mirror 7b, to the light modulation device 4B.

The light modulation device 4G is constituted by a green-color liquid crystal panel 4GP and polarization plates (not shown) respectively disposed at an incident side and an exit side of the green-color liquid crystal panel 4GP. The light modulation device 4G has a first light exit surface 40G, and is arranged so that the first light exit surface 40G faces to the projection optical system 6.

The light modulation device 4R is constituted by a red-color liquid crystal panel 4RP and polarization plates (not shown) respectively disposed at an incident side and an exit side of the red-color liquid crystal panel 4RP. The light modulation device 4R has a second light exit surface 40R, and is arranged so that the second light exit surface 40R faces to the right side (+X) in the horizontal direction X perpendicular to the front-back direction Y in which the light modulation device 4G and the projection optical system 6 are arranged side by side.

The light modulation device 4B is constituted by a blue-color liquid crystal panel 4BP and polarization plates (not shown) respectively disposed at an incident side and an exit side of the blue-color liquid crystal panel 4BP. The light modulation device 4B has a third light exit surface 40B, and is arranged so that the third light exit surface 40B is opposed to the second light exit surface 40R of the light modulation device 4R. In other words, the light modulation device 4B is arranged so that the third light exit surface 40B faces to the left side (−X) in the horizontal direction X.

In particular, in the projector 1 according to the present embodiment, in order to display a brighter image, there are used large-sized panels as the liquid crystal panels 4RP, 4GP, and 4BP of the light modulation devices 4R, 4G, and 4B, respectively, as described above.

In the case of the present embodiment, the light modulation device 4G corresponds to a “first light modulation device”, the light modulation device 4R corresponds to a “second light modulation device”, and the light modulation device 4B corresponds to a “third light modulation device”.

Hereinafter, the red-color liquid crystal panel 4RP, the green-color liquid crystal panel 4GP, and the blue-color liquid crystal panel 4BP are collectively referred to as the liquid crystal panels 4RP, 4GP, and 4BP in some cases.

The light modulation device 4R modulates the red light LR out of the white light WL emitted from the light source 2 in accordance with an image signal using the red-color liquid crystal panel 4RP. The light modulation device 4G modulates the green light LG out of the white light WL emitted from the light source 2 in accordance with the image signal using the green-color liquid crystal panel 4GP. The light modulation device 4B modulates the blue light LB out of the white light WL emitted from the light source 2 in accordance with the image signal using the blue-color liquid crystal panel 4BP. Thus, the light modulation devices 4R, 4G, and 4B each generate image light corresponding to the colored light.

At the light incident side of the light modulation device 4R, there is arranged a field lens 11R for collimating the red light LR entering the light modulation device 4R. At the light incident side of the light modulation device 4G, there is arranged a field lens 11G for collimating the green light LG entering the light modulation device 4G. At the light incident side of the light modulation device 4B, there is arranged a field lens 11B for collimating the blue light LB entering the light modulation device 4B.

The light combining element 5 is formed of a cross dichroic prism having a substantially cubic shape. The light combining element 5 combines the colored light respectively emitted from the light exit surfaces 40R, 40G, and 40B of the light modulation devices 4R, 4G, and 4B with each other to generate the image light LT.

The projection optical system 6 is constituted by a plurality of projection lenses. The projection optical system 6 projects the image light LT combined by the image generator 4 toward the screen SCR in an enlarged manner. Thus, a color image is displayed on the screen SCR.

The pixel shifting device 10 is arranged on the light path of the image light LT between the light combining element 5 of the image generator 4 and the projection optical system 6. It is possible for the projector 1 to display an image higher in resolution than the liquid crystal panels 4RP, 4GP, and 4BP on the screen SCR by making the pixel shifting device 10 shift the light path of the image light LT to cause so-called pixel shift. For example, when the liquid crystal panels 4RP, 4GP, and 4BP are each a liquid crystal panel compliant with the full-high definition, it is possible to display a 4K image.

Here, the principle of achieving high resolution using the light path shift will briefly be described using FIG. 2. FIG. 2 is an explanatory diagram showing the principle of achieving the high resolution using the light path shift of the image light LT.

As described later, the pixel shifting device 10 has an optical member 20 as a light transmissive substrate for transmitting the image light LT, and changes the posture of the optical member 20 to thereby shift the light path of the image light LT using refraction.

The pixel shifting device 10 oscillates the optical member 20 in two directions, namely a first oscillation direction around a first oscillation axis J1 crossing a light axis AX, and a second oscillation direction around a second oscillation axis J2 crossing the light axis AX and crossing the first oscillation axis J1. When the optical member 20 oscillates in the first oscillation direction, the light path of the light entering the optical member 20 is shifted toward a first direction F1 shown in FIG. 2. When the optical member 20 oscillates in the second oscillation direction, the light path of the light entering the optical member 20 is shifted toward a second direction F2 crossing the first direction F1 shown in FIG. 2. Thus, a pixel Px to be displayed on the screen SCR is displayed at a position shifted in the first direction F1 and the second direction F2 crossing the first direction F1. In the case of the present embodiment, the first direction F1 corresponds to the horizontal direction X, and the second direction F2 corresponds to the vertical direction Z.

The projector 1 combines the shift of the light path in the first direction F1 and the shift of the light path in the second direction F2 with each other to thereby increase the apparent number of pixels to achieve the high resolution of the image light LT to be projected on the screen SCR. For example, as shown in FIG. 2, the pixel Px is moved to a position shifted as much as a half pixel in each of the first direction F1 and the second direction F2. Thus, it is possible to move the image display position on the screen SCR to an image display position P2 shifted from an image display position P1 along the first direction F1 as much as a half pixel, an image display position P3 shifted from the image display position P1 along each of the first direction F1 and the second direction F2 as much as a half pixel, and an image display position P4 shifted from the image display position P1 along the second direction F2 as much as a half pixel. In FIG. 2, there is shown a shift operation of A→B→C→D paying attention to an area of a fourth of the pixel Px.

As shown in FIG. 2, the light path shifting operation is performed so as to display an image at each of the image display positions P1, P2, P3, and P4 for a certain period of time to vary the display content in the liquid crystal panels 4RP, 4GP, and 4BP in sync with the light path shifting operation. Thus, it is possible to apparently display the pixels A, B, C, and D smaller in size than the pixel Px. For example, when performing display of the pixels A, B, C, and D with a frequency of 60 Hz as a whole, it is necessary to make the liquid crystal panels 4RP, 4GP, and 4BP perform the display at quad speed in accordance with the image display positions P1, P2, P3, and P4. In other words, the frequency of the display, namely a so-called refresh rate, in each of the liquid crystal panels 4RP, 4GP, and 4BP becomes 240 Hz.

It should be noted that in the example shown in FIG. 2, the first direction F1 and the second direction F2 are directions perpendicular to each other, and are arrangement directions of the pixels Px to be displayed in a matrix on the screen SCR. Instead of this configuration, the first direction F1 and the second direction F2 are not required to be the directions perpendicular to each other, and can be directions tilted with respect to the arrangement directions of the pixels Px. Even with such shifting directions, by arbitrarily combining the pixel shifts toward the first direction F1 and the second direction F2 with each other, it is possible to move the pixel Px to the image display positions P1, P2, P3, and P4 shown in FIG. 2. Further, the shift amount of the image display position is not limited to a half pixel, but can also be, for example, a fourth of the pixel Px, or three fourths thereof.

Subsequently, a configuration of the pixel shifting device 10 will be described. FIG. 3 is a plan view of the pixel shifting device 10. FIG. 3 is a plan view of the pixel shifting device 10 viewed from the −Y side toward the +Y side.

As shown in FIG. 3, the pixel shifting device 10 is provided with the optical member 20, a first frame 21, a second frame 22, a base 23, a pair of first oscillation shaft formation parts 24, a pair of second oscillation shaft formation parts 50, a pair of first actuators 25, and a pair of second actuators 26.

In FIG. 3, there is shown a state in which the pixel shifting device 10 does not change the posture of the optical member 20, namely a state in which the pixel shifting device 10 does not operate.

The pixel shifting device 10 shifts the light path of the image light LT in accordance with the posture of the optical member 20 which the image light LT having entered the pixel shifting device 10 from the image generator 4 enters. The shift amount of the light path of the image light LT is defined (see FIG. 2) in accordance with a degree of a change in posture of the optical member 20.

The optical member 20 is a member which shifts the light path of the image light LT which enters the optical member 20 from the image generator 4, using the refraction. When the pixel shifting device 10 is located at a reference position where the incident angle of the image light LT with respect to the optical member 20 is 0°, a normal direction of the optical member 20 coincides with the front-back direction Y.

As the optical member 20, there is used, for example, super white glass having a substantially square shape. By adopting the super white glass excellent in strength, the rigidity of the whole of the optical member 20 is increased, and therefore, it is possible to suppress the distortion caused in the optical member 20.

It should be noted that the material of the optical member 20 is not limited to the super white glass, it is sufficient for the material of the optical member 20 to be a material which has light transmissive property, and which is capable of refracting light, and it is possible to use a variety of glass materials such as borosilicate glass or quartz glass. Alternatively, it is also possible to use a variety of crystalline materials such as quartz crystal or sapphire, or a variety of resin materials such as polycarbonate series resin or acrylic resin. It should be noted that the shape of the optical member 20 is not limited to the substantially square shape, and can also be a rectangular shape, a rhombic shape, or an elliptical shape.

The first frame 21 is a frame which holds the optical member 20 and which oscillates around the first oscillation axis J1. The first oscillation axis J1 of the first frame 21 is an imaginary axis passing through the center of the optical member 20 supported by the first frame 21.

The first frame 21 is a frame made of metal and having a frame-like shape, and is arranged on the periphery of the optical member 20. The first frame 21 supports an outer circumferential edge of the optical member 20 to thereby house the optical member 20 in a state in which obverse and reverse surfaces are exposed. As the material of the first frame 21, there is used, for example, stainless steel as a metal material having predetermined rigidity. The optical member 20 is fixed to the first frame 21 with an adhesive. It should be noted that the first frame 21 is not limited to the frame-like shape, and is only required to be a member for supporting at least a part of the optical member 20.

The second frame 22 is a frame which oscillates around the second oscillation axis J2 perpendicular to the first oscillation axis. The second oscillation axis J2 of the second frame 22 is an imaginary axis which is perpendicular to the first oscillation axis J1, and which passes through the center of the optical member 20 supported by the first frame 21.

The second frame 22 is formed of a plate member having a substantially octagonal shape in a plan view, and has an opening section 22H having a substantially octagonal shape. Inside the opening section 22H of the second frame 22, there is arranged the first frame 21 for holding the optical member 20. In other words, the second frame 22 is formed of a frame-like member surrounding the first frame 21, and is arranged on the periphery of the first frame 21, and is at the same time coupled to the first frame 21.

The second frame 22 is coupled to the first frame 21 via the pair of first oscillation shaft formation parts 24. Further, the second frame 22 is coupled to the base 23 via the pair of second oscillation shaft formation parts 50 described later. It should be noted that configurations of the pair of first oscillation shaft formation parts 24 and the pair of second oscillation shaft formation parts 50 will be described later.

Based on such configurations, in the pixel shifting device 10 according to the present embodiment, the optical member 20 supported by the second frame 22 via the first frame 21 rotates around the second oscillation axis J2 with respect to the base 23 to thereby be able to change the posture.

In the case of the present embodiment, the second frame 22 and the first frame 21 are arranged so as to at least partially overlap each other in the front-back direction Y. In other words, at least a part of the second frame 22 and at least a part of the first frame 21 are arranged on the same plane parallel to the X-Z plane. It should be noted that it is sufficient for the second frame 22 to have a shape which is arranged so as to surround the periphery of the first frame 21 in the plan view in the front-back direction Y, and the position with respect to the first frame 21 can be shifted in the front-back direction Y. In other words, the second frame 22 and the first frame 21 can be arranged in a state in which the positions of the second frame 22 and the first frame 21 are shifted in the front-back direction Y from each other.

The base 23 is formed of a metal member made of, for example, aluminum. The base 23 has an opening section 230, a primary second frame fixation part 231, a secondary second frame fixation part 232, and a pair of second coil holders 234.

The opening section 230 is constituted by a first opening 230a and a second opening 230b communicated with each other. The second frame 22 is located inside the first opening 230a of the opening section 230, and one of the pair of second oscillation shaft formation parts 50 is located inside the second opening 230b of the opening section 230.

The primary second frame fixation part 231 fixes the second oscillation shaft formation part 50 located at an upper side (+Z) in the vertical direction Z of the second frame 22.

The secondary second frame fixation part 232 fixes the second oscillation shaft formation part 50 located at a lower side (−Z) in the vertical direction Z of the second frame 22.

The pair of second coil holders 234 respectively hold coils of the pair of second actuators 26 described later. The pair of second coil holders 234 are disposed so as to be opposed respectively to a pair of second magnet holders 35 provided to actuator holding parts 55 described later in a direction perpendicular to the second oscillation axis J2 out of the base 23.

In other words, the base 23 is arranged on the periphery of the second frame 22, and is at the same time, coupled to the second frame 22.

In the case of the present embodiment, the second frame 22 and the base 23 are arranged so as to at least partially overlap each other in the front-back direction Y. In other words, at least a part of the second frame 22 and at least a part of the base 23 are arranged on the same plane parallel to the X-Z plane. It should be noted that it is sufficient for the base 23 to have a shape which is arranged so as to surround the periphery of the second frame 22 in the plan view in the front-back direction Y, and the position with respect to the second frame 22 can be shifted in the front-back direction Y. In other words, the second frame 22 and the base 23 can be arranged in a state in which the positions of the second frame 22 and the base 23 are shifted in the front-back direction Y from each other.

The pair of first oscillation shaft formation parts 24 are arranged at both sides of the first frame 21 in the horizontal direction X as a direction along the first oscillation axis J1, and couple the first frame 21 and the second frame 22 to each other. Although in the case of the present embodiment, the pair of first oscillation shaft formation parts 24 are formed integrally with the first frame 21, the pair of first oscillation shaft formation parts 24 and the first frame 21 can be formed separately from each other.

The pair of first oscillation shaft formation parts 24 are fixed to an obverse surface 22b of the second frame 22 via screw members 60. The obverse surface 22b of the second frame 22 is a surface facing to the back side (−Y) in the front-back direction Y, and is a surface at a side where the image generator 4 is arranged to the pixel shifting device 10.

In the pixel shifting device 10 according to the present embodiment, the pair of first oscillation shaft formation parts 24 are symmetrically arranged centering on the second oscillation axis J2. In the present embodiment, the expression that the pair of first oscillation shaft formation parts 24 are symmetrically arranged means that the first oscillation shaft formation parts 24 have substantially the same shapes, and the shapes have a relationship in which when one of the formation parts is turned over the other of the formation parts with reference to the second oscillation axis J2, the one of the formation parts overlaps the other of the formation parts. According to the pixel shifting device 10 related to the present embodiment, since the first frame 21 and the second frame 22 are coupled to each other in a balanced manner with the pair of first oscillation shaft formation parts 24, it is possible to oscillate the optical member 20 in a stable state around the first oscillation axis J1.

The pair of first oscillation shaft formation parts 24 have a pair of coupling shaft parts 240 and a pair of beams 241. The pair of coupling shaft parts 240 are located on the first oscillation axis J1 of the first frame 21, and each swingably couple an outer side surface 21a of the first frame 21 and an inner side of the second frame 22 to each other. The pair of coupling shaft parts 240 respectively protrude from surfaces facing to directions opposite to each other out of four outer side surfaces 21a of the optical member 20 having a rectangular frame-like shape, and couple the first frame 21 and the second frame 22 to each other.

In the present embodiment, the pair of coupling shaft parts 240 are equal in shape, width, length, and thickness to each other. In other words, the pair of coupling shaft parts 240 are made equal in rigidity to each other. It should be noted that the pair of coupling shaft parts 240 can be different in at least either one of shape, width, length, and thickness from each other providing the pair of coupling shaft parts 240 are equal in rigidity to each other. In the present specification, the rigidity of the coupling shaft part 240 means the rigidity in a state in which the first oscillation shaft formation part 24 couples the first frame 21 and the second frame 22 to each other, and is different from the rigidity as a single body of the first oscillation shaft formation part 24.

Further, as described later, the pair of first actuators 25 are arranged symmetrically at both sides in the vertical direction Z centering on the first oscillation axis J1 with respect to the optical member 20 held by the first frame 21. Therefore, since the thrust force of the first actuators 25 is transferred evenly to the pair of coupling shaft parts 240, it is also possible to prevent an occurrence of the torsion when the first frame 21 rotates around the first oscillation axis J1.

Based on such a configuration, in the pixel shifting device 10 according to the present embodiment, it is possible to accurately change the posture of the optical member 20 supported by the first frame 21 by rotating the first frame 21 around the first oscillation axis J1 with respect to the second frame 22 in a balanced manner.

The pair of beams 241 extend along the second oscillation axis J2 respectively from the pair of coupling shaft parts 240, and along the obverse surface 22b of the second frame 22. The second frame 22 is increased in strength of portions in which the pair of beams 241 are disposed. According to the pixel shifting device 10 related to the present embodiment, by disposing the beams 241 of the pair of first oscillation shaft formation parts 24 on the obverse surface 22b of the second frame 22, it is possible to increase the strength of peripheral areas of the coupling portions in the second frame 22 to the first frame 21.

In the present embodiment, the pair of beams 241 are each arranged so as to straddle the first oscillation axis J1. Each of the beams 241 is arranged at both sides of the first oscillation axis J1. In the case of the present embodiment, the pair of beams 241 are each arranged symmetrically centering on the first oscillation axis J1.

Based on such a configuration, it is possible for each of the beams 241 of the first oscillation shaft formation parts 24 to increase the strength of the portion extending in the vertical direction Z perpendicular to the first oscillation axis J1 out of the second frame 22 in a balanced manner.

A first length L1 in the vertical direction Z along the second oscillation axis J2 in each of the beams 241 is a length corresponding to a second length L2 in the vertical direction Z along the second oscillation axis J2 of the first frame 21.

In the present specification, the expression that the first length L1 is the length corresponding to the second length L2 means that the first length L1 and the second length L2 are substantially equal to each other. It should be noted that the expression that the first length L1 and the second length L2 are substantially equal to each other includes not only a state in which the first length L1 and the second length L2 completely coincide with each other, but also a state in which one of the first length L1 and the second length L2 is longer or shorter as much as several millimeters compared to the other. It should be noted that the first length L1 in the vertical direction Z of the beam 241 can be made equal to the length in the vertical direction Z of the optical member 20 held by the first frame 21.

According to this configuration, since the pair of beams 241 having the length corresponding to the first frame 21 are arranged so as to overlap the second frame 22, it is possible to sufficiently increase the rigidity of the second frame 22. Therefore, in the pixel shifting device 10 according to the present embodiment, even when using the second frame 22 formed of a lightweight material small in thickness, it is possible to ensure the sufficient rigidity as the second frame 22, and therefore, it is possible to realize a reduction in size and a reduction in weight of the device itself.

FIG. 4 is a cross-sectional view of an essential part of the pixel shifting device 10. FIG. 4 is a cross-sectional view as an arrow view along the line IV-IV in FIG. 3.

As shown in FIG. 4, the pair of beams 241 each have a rising wall part 243 which extends in the vertical direction Z along the second oscillation axis J2, rises along the front-back direction Y as the normal direction of the obverse surface 22b of the second frame 22, and extends in the vertical direction Z along the second oscillation axis J2.

The rising wall part 243 is disposed in an end portion 241a at the base 23 side in each of the pair of beams 241. In the case of the present embodiment, the rising wall part 243 extends toward the projection optical system 6 along an outer side surface 22c of the second frame 22. Since the pair of beams 241 are each provided with the rising wall part 243, the cross-sectional surface along the X-Y plane thereof has a substantially L shape, and thus, it is possible to make a second moment of area higher compared to a structure in which the rising wall part 243 is not disposed. Therefore, it is possible for the pair of beams 241 to increase the rigidity of the second frame 22 while keeping the first length L1 in the vertical direction Z at a minimum. Therefore, it is possible for the pixel shifting device 10 according to the present embodiment to efficiently increase the rigidity of the second frame 22 while suppressing an increase in weight by suppressing the length of the pair of beams 241.

Going back to FIG. 3, in the plan view in the front-back direction Y as the normal direction of the obverse surface 22b of the second frame 22, both end portions 245 in the vertical direction Z along the second oscillation axis J2 in each of the pair of beams 241 each have an oblique side 246 with which the length in the vertical direction Z increases in a direction from the first frame 21 side toward the base 23 side. In other words, the both end portions 245 of each of the beams 241 each have a shape having a width in the vertical direction Z spreads in a direction from the inner side toward the outer side of the second frame 22 to form a tapered shape due to the oblique side 246.

The inventor conducted a simulation of the case of adopting a rectangular shape as the planar shape of each of the beams 241, namely when the tapered shape is not provided to each of the both end portions of each of the beams 241. According to the present simulation, it was successfully confirmed that providing the rectangular shape to the planar shape of each of the beams 241 does not contribute to the rigidity of each of the beams 241.

In contrast, in the pixel shifting device 10 according to the present embodiment, by disposing the oblique sides 246 in the both end portions 245 of each of the beams 241 as described above, it is possible to achieve the reduction in weight while ensuring the rigidity of each of the beams 241.

Here, a resonance frequency of the second frame 22 varies in accordance with the length of the pair of beams 241. In the pixel shifting device 10 according to the present embodiment, the length of the pair of beams 241 is arbitrarily adjusted to thereby set the resonance frequency of the second frame 22 to a desired value. Specifically, in the pixel shifting device 10 according to the present embodiment, by appropriately adjusting the length of the pair of beams 241, the resonance frequency of the second frame 22 is shifted to a high frequency. Thus, it is possible for the second frame 22 to prevent the resonance from occurring without increasing the size or increasing the thickness. Therefore, according to the pixel shifting device 10 related to the present embodiment, it is possible to provide the pixel shifting device in which a problem caused by the resonance is prevented from occurring, and is high in reliability, while achieving the reduction in size of the device configuration.

As described above in the pixel shifting device 10 according to the present embodiment, since the pair of beams 241 of the pair of first oscillation shaft formation parts 24 for coupling the first frame 21 and the second frame 22 to each other are formed along the obverse surface 22b of the second frame 22, it is possible to increase the strength of the second frame 22 in which the beams 241 are arranged.

Since the pair of first oscillation shaft formation parts 24 each provided with the beam 241 extending from the coupling shaft part 240 for coupling the first frame 21 for supporting the optical member 20 and the second frame 22 to each other on the first oscillation axis J1 to the obverse surface 22b of the second frame 22 in the vertical direction Z along the second oscillation axis J2, it is possible to efficiently increase the strength in the vicinity of the coupling portion of the second frame 22 to the first frame 21.

For example, when a load by a vibration when transporting the projector 1, or by an impact caused by accidentally dropping the projector 1 is applied, a particularly heavy load occurs on the periphery of the coupling portion of the second frame 22 to the first frame 21 for supporting the optical member 20. In contrast, in the pixel shifting device 10 according to the present embodiment, by increasing the strength of the coupling portion in the second frame 22 to the first frame 21 using the pair of first oscillation shaft formation parts 24 as described above, it is possible to prevent a deformation and a breakage of the second frame 22. Therefore, the pixel shifting device 10 according to the present embodiment is made enhanced in resistance to an impact load, and high in reliability.

The pair of second oscillation shaft formation parts 50 are members which are located on the second oscillation axis J2, and which couple the second frame 22 and the base 23 to each other. The pair of second oscillation shaft formation parts 50 include an upper base coupling member 28 and a lower base coupling member 29. In the present embodiment, the upper base coupling member 28 corresponds to the “other-side coupling member”, and the lower base coupling member 29 corresponds to “one-side coupling member”.

The upper coupling member 28 which forms one of the pair of second oscillation shaft formation parts 50 is a member which couples the second frame 22 and the base 23 to each other at an upper side (+Z) as one side on the second oscillation axis J2. The upper base coupling member 28 has a base fixation part 28a, an upper coupling shaft part 28b, and a frame fixation part 28c. The upper base coupling member 28 is fixed to the base 23 and the second frame 22 via the screw members 60.

The frame fixation part 28c fixes the upper base coupling member 28 to an upper end portion located at the upper side (+Z) in the vertical direction Z of the second frame 22. The base fixation part 28a fixes the upper base coupling member 28 to the primary second frame fixation part 231 of the base 23. The upper coupling shaft part 28b couples the frame fixation part 28c and the base fixation part 28a to each other to oscillate the second frame 22 around the second oscillation axis J2 with respect to the base 23.

In other words, the upper base coupling member 28 forming one of the pair of second oscillation shaft formation parts 50 includes the upper coupling shaft part 28b. In the present embodiment, the upper coupling shaft part 28b corresponds to “another-side coupling shaft part”. The upper base coupling member 28 can integrally be formed with the second frame 22. It should be noted that the configuration of the lower base coupling member 29 will be described later.

Each of the pair of first actuators 25 generates a drive force of oscillating the first frame 21 with respect to the second frame 22 between the first frame 21 and the second frame 22.

Each of the pair of first actuators 25 is arranged on the second oscillation axis J2 perpendicular to the first oscillation axis J1, and has a first magnet 25a arranged on the first frame 21, and a first coil 25b arranged on the base 23 and opposed to the first magnet 25a.

The pair of first actuators 25 are arranged symmetrically at both sides in the vertical direction Z centering on the first oscillation axis J1 with respect to the optical member 20 held by the first frame 21. The pair of first actuators 25 are located at equal distance from the first oscillation axis J1, and are therefore arranged to be able to transmit the drive forces to the first frame 21 holding the optical member 20 in a balanced manner. Therefore, it is possible for the pixel shifting device 10 according to the present embodiment to rotate the first frame 21 around the first oscillation axis J1 without a deflection using the pair of first actuators 25.

The first magnet 25a is arranged on the first frame 21 via a magnet holding plate 27. Specifically, the first magnet 25a is arranged in a first magnet holder 21b disposed in a region located on the first oscillation axis J1 out of the outer side surfaces 21a of the first frame 21. The magnet holding plate 27 is formed of metal such as iron, and functions as a back yoke. It is sufficient for a magnet used as the first magnet 25a to be a permanent magnet having a predetermined magnetic force besides a neodymium magnet, and it is possible to adopt a samarium-cobalt magnet, a ferrite magnet, or an alnico magnet.

The first coil 25b is arranged on an inner side surface 22a of the second frame 22 via a coil holder member 36. The coil holder member 36 is fixed to the base 23, and arranges the first coil 25b and the first magnet 25a so as to be opposed to each other via a gap. The coil holder member 36 is formed of metal such as iron, and functions as a back yoke. The first coil 25b is formed of a coil wire wound around the coil holder member 36.

It should be noted that the positions of the first magnet 25a and the first coil 25b can be exchanged, and it is possible to arrange the first magnet 25a in the magnet holder extending from the base 23, and to arrange the first coil 25b in the coil holder member disposed on the outer side surface 21a of the first frame 21.

Each of the pair of second actuators 26 is a device for oscillating the second frame 22 with respect to the base 23 between the second frame 22 and the base 23.

It is desirable for the pair of second actuators 26 to be arranged so as to be symmetric at both sides in the horizontal direction X centering on the second oscillation axis J2 with respect to the optical member 20 which the second frame 22 holds via the first frame 21 similarly to the first actuators 25 to thereby increase the transmission efficiency of the respective drive forces. In other words, it is desirable to arrange the pair of second actuators 26 on the first oscillation axis J1.

Here, a positional relationship between the pixel shifting device 10 and the image generator 4 in the projector 1 according to the present embodiment will be described.

FIG. 5 and FIG. 6 are each a diagram showing the positional relationship between the pixel shifting device 10 and the image generator 4. FIG. 5 is a cross-sectional view by a plane along the X-Y plane, and FIG. 6 is a plan view viewed from the −Y side toward the +Y side.

As shown in FIG. 5, the image generator 4 is unitized by integrally holding the light modulation devices 4R, 4G, and 4B and the light combining element 5 via a frame member F.

In the projector 1 according to the present embodiment, the light modulation devices 4R, 4B out of the light modulation devices 4R, 4G, and 4B are set in a state of coming closer to the pixel shifting device 10.

In the image generator 4 in the present embodiment, the light modulation devices 4R, 4G, and 4B are made larger in width than the light combining element 5.

In the pixel shifting device 10 according to the present embodiment, in the front-back direction Y in which the light modulation device 4G and the projection optical system 6 are arranged side by side, front end portions 4R1, 4B1 located at the projection optical system 6 side of the light modulation device 4R and the light modulation device 4B each overlap the pixel shifting device 10. Therefore, the front end portions 4R1, 4B1 of the light modulation device 4R and the light modulation device 4B are extremely close to the pixel shifting device 10. More specifically, the front end portions 4R1, 4B1 of the light modulation devices 4R, 4B are each arranged adjacent to the first frame 21, the second frame 22, and the base 23 of the pixel shifting device 10.

The pixel shifting device 10 according to the present embodiment is provided with the first oscillation shaft formation parts 24 to thereby be increased in strength of the second frame 22, and therefore, there is no need to increase the thickness for increasing the strength even when making the second frame 22 grow in size. As described above, in the pixel shifting device 10 according to the present embodiment, since it is possible to decrease the thickness of the second frame 22, it is possible to achieve a reduction in size of the device configuration by arranging the front end portions 4R1, 4B1 of the light modulation devices 4R, 4B and the pixel shifting device 10 so as to be close to each other in the front-back direction Y.

In contrast, in the projector 1 according to the present embodiment, since the front end portions 4R1, 4B1 of the light modulation devices 4R, 4B are arranged so as to be close to the second frame 22 and the base 23 out of the pixel shifting device 10, it is difficult to arrange the second actuators on the first oscillation axis J1.

Therefore, in the pixel shifting device 10 according to the present embodiment, the pair of second actuators 26 are respectively held in the pair of actuator holding parts 55 disposed at a lower side (−Z) as one side in the vertical direction Z along the second oscillation axis J2 with respect to the first oscillation axis J1.

The pair of actuator holding parts 55 are located at the lower side (−Z) as an opposite side to the first oscillation axis J1 with respect to the first actuators 25. In the case of the present embodiment, the pair of second actuators 26 are arranged at the lower side (−Z) of the first actuators 25 located at the lower side (−Z) of the optical member 20.

As shown in FIG. 6, in the pixel shifting device 10 according to the present embodiment, the front end portions 4R1, 4B1 of the light modulation devices 4R, 4B are respectively arranged at positions distant from the second actuators 26 of the pixel shifting device 10 in the vertical direction Z along the second oscillation axis J2. Therefore, in the pixel shifting device 10 according to the present embodiment, since the front end portions 4R1, 4B1 of the light modulation devices 4R, 4B and the second actuators 26 do not interfere with each other, it is possible to achieve a reduction in size of the device configuration by arranging the front end portions 4R1, 4B1 of the light modulation devices 4R, 4B and the pixel shifting device 10 so as to be close to each other in the front-back direction Y.

The pair of actuator holding parts 55 are disposed in a region extending at the lower side (−Z) in the vertical direction Z in the second frame 22 and the base 23. The pair of actuator holding parts 55 are constituted by the pair of second magnet holders 35 of the lower base coupling member 29 described later, and the pair of second coil holders 234 of the base 23. In other words, the pair of actuator holding parts 55 provided to the second frame 22 are constituted by the second magnet holders 35 of the lower base coupling member 29 as a part of the pair of second oscillation shaft formation parts 50. In the case of the present embodiment, since the actuator holding parts 55 are constituted by a part of the lower base coupling member 29, it is possible to achieve a reduction in number of components.

The second actuators 26 each have a magnet and a coil arranged at a predetermined distance in a direction along the first oscillation axis J1. Specifically, the second actuators 26 each have a second magnet 26a arranged in the second magnet holder 35 of the second frame 22 constituting the actuator holding part 55, and a second coil 26b which is arranged in the second coil holder 234 of the base 23 constituting the actuator holding part 55, and which is opposed to the second magnet 26a in a direction along the first oscillation axis J1 crossing the second oscillation axis J2.

The second magnet 26a is arranged on the second magnet holder 35 via the magnet holding plate 27 which functions as the back yoke. The second coil holder 234 for holding the second coil 26b functions as the back yoke.

The second magnet 26a and the second coil 26b have substantially the same configurations as those of the first magnet 25a and the first coil 25b constituting the first actuator 25, and therefore, the description thereof will be omitted.

It should be noted that the positions of the second magnet 26a and the second coil 26b can be exchanged, and it is possible to arrange the second magnet 26a at the base 23 side, and to arrange the second coil 26b at the second frame 22 side.

As described above, in the pixel shifting device 10 according to the present embodiment, the second actuators 26 are disposed in an area at the side of the second frame 22 at which the first actuator 25 is arranged. More specifically, in the pixel shifting device 10 according to the present embodiment, there is adopted a structure in which the first actuator 25 and the second actuators 26 are intensively arranged at the lower side (−Z) in the vertical direction Z along the second oscillation axis J2 with respect to the optical member 20.

According to the projector 1 related to the present embodiment, by aggregating the second actuators 26 at one side of the first actuators 25, it is possible to arrange the pixel shifting device 10 in the state of being close to the image generator 4 in the front-back direction Y. Therefore, it is possible to reduce the size in the front-back direction Y of the projector 1 according to the present embodiment. Further, it is possible for the pixel shifting device 10 to efficiently take in the image light LT emitted from the projection optical system 6 of the image generator 4, and thus, it is possible to increase the light use efficiency of the image light LT.

On the other hand, in the pixel shifting device 10 according to the present embodiment, it is necessary to arrange the second actuators 26 at the lower side (−Z) of the first actuator 25 as described above. Therefore, as shown in FIG. 3 and FIG. 6, the second frame 22 in the present embodiment has an extending part 220 which extends toward an opposite side to the first oscillation axis J1 with respect to the first actuator 25, and toward one side (−Z) in an axial direction along the second oscillation axis J2, and holds the magnets as the constituents of the second actuators 26 via the lower base coupling member 29 fixed to the extending part 220.

As described above, in the pixel shifting device 10 according to the present embodiment, since a distance from the second actuators 26 to the optical member 20 is longer compared to a distance from the first actuator 25 to the optical member 20, there is created a structure in which the drive forces of the second actuators 26 are difficult to be transferred to the optical member 20 side.

To cope with the above, in the pixel shifting device 10 according to the present embodiment, in order to make it possible for the second frame 22 to easily oscillate in response to the drive forces of the second actuators 26 efficiently transferred to the optical member 20 side, it is arranged that the second frame 22 is formed of a lightweight material such as aluminum.

In general, the lightweight material such as aluminum is low in rigidity. Therefore, there is a possibility that a deterioration in durability, a deformation, and so on occur in the second frame 22 formed of the lightweight material due to a concentration of the stress generated due to the drive forces of the first actuators 25 and the second actuators 26.

In particular, in the projector 1 according to the present embodiment, in order to display a bright image as described above, there are used the large-sized panels as the liquid crystal panels 4RP, 4GP, and 4BP of the light modulation devices 4R, 4G, and 4B, respectively, and thus, the optical member 20 grows in size, and therefore, the first frame 21 and the second frame 22 also grow in size as a result. When forming such a large-sized second frame 22 from such a lightweight material as described above, there is a possibility that the risk of the deterioration in durability, the deformation, and so on described above further increases.

In the pixel shifting device 10 according to the present embodiment, it is arranged that the rigidity of the second frame 22 is increased by disposing the lower base coupling member 29 in the area at the side in the second frame 22 at which the first actuator 25 and the second actuators 26 are intensively arranged, specifically in the extending part 220. In other words, the lower base coupling member 29 has a function as a frame reinforcement member for increasing the rigidity of the second frame 22.

A peripheral configuration of the lower base coupling member 29 and the second frame 22 in which the lower base coupling member 29 is disposed will hereinafter be described.

FIG. 7 is a perspective view showing a configuration of an essential part of the second frame 22 in which the lower base coupling member 29 is disposed.

As shown in FIG. 7, the lower base coupling member 29 which forms the other of the pair of second oscillation shaft formation parts 50 is formed of a sheet-metal member made of, for example, austenite stainless steel, and has predetermined rigidity. The lower base coupling member 29 can be formed of a single plate member, or can also be divided into two plate members as long as the object of sufficiently increasing the rigidity of the second frame 22 can be achieved.

The lower base coupling member 29 is fixed to the extending part 220 located at the lower side (−Z) in the vertical direction Z of the second frame 22 via the screw members 60. The lower base coupling member 29 includes a main body part 31 formed of a substantially U-shape in a plan view, the second magnet holders 35 for holding the magnets of the second actuators 26 described later, and a base coupling part 34 to be coupled to the secondary second frame fixation part 232 of the base 23.

The main body part 31 of the lower base coupling member 29 has a first surface 31a having contact with the obverse surface 22b of the second frame 22, and a second surface 31b opposite to the first surface 31a. The main body part 31 of the lower base coupling member 29 includes a first wall part 32 extending in the horizontal direction X, and a pair of second wall parts 33 extending toward the lower side (−Z) in the vertical direction Z from both ends in the horizontal direction X of the first wall part 32.

In the present embodiment, the first wall part 32 is provided with a pair of pin holes 32a in which a pair of pins 22P disposed on the obverse surface 22b of the second frame 22 are inserted. It should be noted that by forming one of the pair of pin holes 32a with an elongate hole, it is possible to improve the workability when performing the positioning between the lower base coupling member 29 and the second frame 22 irrespective of a variation in dimension between the pair of pins 22P.

The second magnet holders 35 are each a region which rises toward the back side (−Y) in the front-back direction Y from end portions 33a of the second wall parts 33 out of the second surface 31b of the main body part 31, and which extends in the vertical direction Z. In the case of the present embodiment, a part of each of the second magnet holders 35 protrudes toward the lower side (−Z) in the vertical direction Z with respect to the second wall part 33. In other words, the length in the front-back direction Y of the second magnet holders 35 is longer than the length in the front-back direction Y of the second wall parts 33.

Therefore, it is possible for the second magnet holders 35 of the lower base coupling member 29 to be able to hold a magnet larger in size.

The second magnet holders 35 each have a support plate 35a for supporting the magnet, and a locking stopper 35b for locking the magnet supported by the support plate 35a, and is made capable of stably holding the magnet.

In the case of the present embodiment, by disposing the second magnet holders 35 as uprise wall parts, it is possible to increase the strength without growing the lower base coupling member 29 in size. Further, by using the uprise wall parts as the magnet holders, it is possible to prevent the frame reinforcement member from growing in size.

The base coupling part 34 includes a base fixation part 34a and a lower coupling shaft part 34b. In other words, the lower base coupling member 29 forming one of the pair of second oscillation shaft formation parts 50 includes the lower coupling shaft part 34b.

The base fixation part 34a is a region which fixes the lower base coupling member 29 to the secondary second frame fixation part 232 of the base 23. The secondary second frame fixation part 232 has a support surface 232a for supporting the base fixation part 34a, and a positioning pin 232b protruding from the support surface 232a.

The lower coupling shaft part 34b is located on the second oscillation axis J2 and couples the second frame 22 and the base 23 to each other at the actuator holding part 55 side. That is, the lower coupling shaft part 34b couples the second frame 22 and the base 23 to each other at the lower side (−Z) in the vertical direction Z to oscillate the second frame 22 around the second oscillation axis J2 with respect to the base 23. In the present embodiment, the lower coupling shaft part 34b corresponds to a “one-side coupling shaft part”.

In the present embodiment, the base fixation part 34a is provided with a cutout 34a1 through which the positioning pin 232b disposed on the support surface 232a of the secondary second frame fixation part 232 is inserted. By inserting the positioning pin 232b into the cutout 34a1 of the base fixation part 34a, the position of the lower base coupling member 29 to the base 23 is regulated.

Further, in the pixel shifting device 10 according to the present embodiment, the first actuator 25 and the second actuators 26 are intensively arranged at the lower side (−Z) as one side in the vertical direction Z along the second oscillation axis J2 as described above.

The inventor found out the fact that it became difficult for the displacement of the second frame 22 due to the thrust forces of the pair of second actuators 26 to be transferred when intensively arranging the first actuator 25 and the second actuators 26 at one side in the vertical direction Z in the second frame 22 from the simulation result described below.

The inventor completed the configuration of the pixel shifting device 10 according to the present embodiment based on the simulation result. In the pixel shifting device 10 according to the present embodiment, in order to make it possible to transfer the displacement of the second frame 22 due to the thrust forces of the pair of second actuators 26 in the direction along the second oscillation axis J2 in a balanced manner, the lower coupling shaft part 34b of the lower base coupling member 29 and the upper coupling shaft part 28b of the upper base coupling member 28 for coupling the second frame 22 and the base 23 to each other are made different in rigidity from each other.

The upper coupling shaft part 28b and the lower coupling shaft part 34b are made different in at least one of shape, width, length, and thickness from each other to thereby be made different in rigidity from each other. In the present embodiment, the width W1 in the horizontal direction X of the upper coupling shaft part 28b is smaller than the width W2 in the horizontal direction X of the lower coupling shaft part 34b as shown in FIG. 3. In the case of the present embodiment, the upper coupling shaft part 28b and the lower coupling shaft part 34b are equal in length and thickness to each other.

In such a manner, the rigidity of the upper coupling shaft part 28b is made lower than the rigidity of the lower coupling shaft part 34b. Further, the second moment of area of the upper coupling shaft part 28b is made lower than the second moment of area of the lower coupling shaft part 34b. In other words, since the rigidity of the upper coupling shaft part 28b becomes lower than the rigidity of the lower coupling shaft part 34b, the upper coupling shaft part 28b becomes easier to twist than the lower coupling shaft part 34b.

First, the inventor conducted the following simulation regarding the displacement of the second frame 22 due to the thrust forces of the pair of second actuators 26 when intensively arranging the first actuator 25 and the second actuators 26 at one side in the vertical direction Z in the second frame 22.

As a first simulation, the inventor calculated how the displacement transfers to the second frame due to the thrust forces of the second actuators using a model corresponding to the pixel shifting device 10 according to the present embodiment. Further, as a second simulation, the inventor calculated how the displacement transfers to the second frame due to the thrust forces of the second actuators using a model corresponding to a pixel shifting device according to a comparative example having a configuration in which the upper coupling shaft part and the lower coupling shaft part are equal in rigidity to each other.

FIG. 8A is a displacement distribution diagram showing a first simulation result corresponding to the pixel shifting device 10 according to the present embodiment, and FIG. 8B is a displacement distribution diagram showing a second simulation result corresponding to a pixel shifting device 100 according to the comparative example.

As shown in FIG. 8B, when the upper coupling shaft part 128b and the lower coupling shaft part 134b are equal in rigidity to each other as in the pixel shifting device 100 according to the comparative example, it is possible to confirm that isopleth lines K of the displacement distribution of the second frame 22 spread toward the outside of the frame in a direction of getting away from the actuator holding parts 55. This is because the thrust forces of the second actuators 26 efficiently transfer to the second frame 22 at a position close to the actuator holding parts 55 in which the second actuators 26 are arranged, and it becomes difficult for the thrust forces of the second actuators 26 to transfer to the second frame 22 at a position distant from the actuator holding parts 55.

In other words, in the pixel shifting device 100 according to the comparative example, the displacement of the second frame 22 decreases in a direction of getting away from the actuator holding parts 55. Therefore, in the pixel shifting device 100 according to the comparative example, a torsional angle of the second frame 22 due to an upper coupling shaft part 128b becomes smaller than a torsional angle of the second frame 22 due to a lower coupling shaft part 134b.

As described above, in the pixel shifting device 100 according to the comparative example, since a difference in torsional angle occurs between the upper coupling shaft part 128b and the lower coupling shaft part 134b, it is unachievable to rotate the optical member 20 around the second oscillation axis in a balanced manner, and it is difficult to accurately shift the light path of the image light. Further, in the pixel shifting device 100 according to the comparative example, a difference in load on each of the shaft members due to the difference in torsional angle occurs, and there is a possibility that the deterioration of the reliability is incurred due to the occurrence of the difference in durability in each of the shaft members.

In contrast, in the pixel shifting device 10 according to the present embodiment, the width of the upper coupling shaft part 28b is made smaller than the width of the lower coupling shaft part 34b as described above to thereby make the rigidity of the upper coupling shaft part 28b lower than the rigidity of the lower coupling shaft part 34b.

According to this configuration, it is possible to relatively decrease the rigidity of the upper coupling shaft part 28b for coupling the opposite side (+Z) to the actuator holding part 55 in the second frame 22, to which the thrust forces of the second actuators 26 are difficult to transfer, to the base 23 while relatively increasing the rigidity of the lower coupling shaft part 34b for coupling the actuator holding part 55 side (−Z) in the second frame 22, to which the thrust forces of the second actuators 26 are easy to transfer, to the base 23.

Therefore, by appropriately adjusting the rigidity of each of the upper coupling shaft part 28b and the lower coupling shaft part 34b, it is possible to make the torsion of the second frame 22 in the upper coupling shaft part 28b easier to occur than the torsion of the second frame 22 in the lower coupling shaft part 34b. Therefore, it is possible to make the torsional angle of the second frame 22 due to the upper coupling shaft part 28b and the torsional angle of the second frame 22 due to the lower coupling shaft part 34b equal to each other.

It should be noted that according to the pixel shifting device 10 related to the present embodiment, it is possible to confirm that the isopleth lines K of the displacement distribution of the second frame 22 extend in substantially parallel to the second oscillation axis J2 as shown in FIG. 8A. As described above, according to the pixel shifting device 10 related to the present embodiment, it was confirmed from the simulation result that the displacement of the second frame 22 becomes substantially constant irrespective of the distance from the actuator holding part 55, and the torsional angles of the upper coupling shaft part 28b and the lower coupling shaft part 34b substantially coincide with each other.

Further, in the pixel shifting device 10 according to the present embodiment, it is possible to increase the rigidity of the second frame 22 by disposing the lower base coupling member 29 in the extending part 220 in which the first actuator 25 and the second actuators 26 are intensively arranged in the second frame 22.

Thus, since the deformation of the second frame 22 oscillating around the second oscillation axis J2 is suppressed, it is possible for the pixel shifting device 10 according to the present embodiment to accurately control the posture of the optical member 20 which is held via the first frame 21.

Further, since the deformation of the second frame 22 is difficult to occur, it is possible to prevent, for example, the second frame 22 or the optical member 20 held by the second frame 22 via the first frame 21 from moving in the front-back direction Y to make contact with the image generator 4. Therefore, according to the pixel shifting device 10 related to the present embodiment, it becomes possible to arrange the pixel shifting device 10 in the state of coming closer to the image generator 4 in the front-back direction Y. Therefore, it is possible to further reduce the size in the front-back direction Y of the projector 1 according to the present embodiment. Therefore, since the pixel shifting device 10 according to the present embodiment efficiently takes in the image light LT emitted from the projection optical system 6 of the image generator 4, it is possible to increase the light use efficiency of the image light LT.

Further, since the deformation of the second frame 22 is difficult to occur, it is possible to efficiently use the drive forces of the second actuators 26 in the rotation of the second frame 22. Therefore, since a current to be supplied to the second actuators 26 for tilting the optical member 20 as much as the same angle becomes smaller, it is possible to suppress the power consumption of the second actuators 26.

Then, an operation of the pixel shifting device 10 according to the present embodiment will be described.

The pixel shifting device 10 according to the present embodiment energizes the first coil 25b using a circuit board not shown to thereby generate a magnetic field to repel or attract the first magnet 25a to thereby generate the force in a direction crossing the first oscillation axis J1 between the first magnet 25a and the first coil 25b in each of the first actuators 25. Thus, the first frame 21 oscillates around the first oscillation axis J1. In the first frame 21, since the coupling shaft parts 240 of the pair of first oscillation shaft formation parts 24 located at the both ends in the direction along the first oscillation axis J1 are coupled to the second frame 22 as described above, it is possible for the optical member 20 fixed to the first frame 21 to oscillate around the first oscillation axis J1 with respect to the second frame 22.

Further, the pixel shifting device 10 according to the present embodiment energizes the second coil 26b using a circuit board not shown to thereby generate a magnetic field to repel or attract the second magnet 26a to thereby generate the force in a direction crossing the second oscillation axis J2 between the second magnet 26a and the second coil 26b in each of the second actuators 26. Thus, the second frame 22 oscillates around the second oscillation axis J2. In the second frame 22, since the upper coupling shaft part 28b and the lower coupling shaft part 34b located at the both ends in the direction along the second oscillation axis J2 are coupled to the base 23 as described above, it is possible for the optical member 20 fixed to the second frame 22 via the first frame 21 and the first oscillation shaft formation parts 24 to oscillate around the second oscillation axis J2 with respect to the base 23.

In such a manner, it is possible for the pixel shifting device 10 according to the present embodiment to biaxially control the posture of the optical member 20 using the drive forces by the pair of first actuators 25 and the pair of second actuators 26. It is possible for the pixel shifting device 10 to shift the light path of the image light LT emitted from the image generator 4 in the directions along the two axes by changing the posture of the optical member 20.

In the case of the present embodiment, when the first frame 21 oscillates around the first oscillation axis J1, the incident angle of the image light LT with respect to the optical member 20 changes, and the light path of the image light LT moves in the second direction F2 (see FIG. 2). Further, when the second frame 22 for holding the first frame 21 oscillates around the second oscillation axis J2, the incident angle of the image light LT with respect to the optical member 20 changes in a different direction from when oscillating around the first oscillation axis J1, and the light path of the image light LT moves in the first direction F1 (see FIG. 2).

As described above, the pixel shifting device 10 according to the present embodiment is provided with the optical member 20, the first frame 21 which holds the optical member 20 and which oscillates around the first oscillation axis J1, the second frame 22 which is arranged on the periphery of the first frame 21, and is at the same time, coupled to the first frame 21, and which oscillates around the second oscillation axis J2 perpendicular to the first oscillation axis J1, the base 23 which is arranged on the periphery of the second frame 22, and is at the same time, coupled to the second frame 22, the pair of first oscillation shaft formation parts 24 which are located on the first oscillation axis J1, and which couple the first frame 21 and the second frame 22 to each other, the pair of second oscillation shaft formation parts 50 which are located on the second oscillation axis J2, and which couple the second frame 22 and the base 23 to each other, the first actuators 25 which are arranged on the second oscillation axis J2, and which oscillate the first frame 21 with respect to the second frame 22 between the first frame 21 and the second frame 22, and the pair of second actuators 26 which are respectively held by the pair of actuator holding parts 55, and which oscillate the second frame 22 with respect to the base 23, the pair of actuator holding parts 55 being disposed at the side of the second frame 22 and the base 23 where the first actuators 25 are arranged, being arranged across the second oscillation axis J2, wherein the pair of second oscillation shaft formation parts 50 include the lower coupling shaft part 34b which couples the second frame 22 and the base 23 to each other at the actuator holding parts 55 side, and the upper coupling shaft part 28b which couples the second frame 22 and the base 23 to each other at the opposite side to the actuator holding parts 55, and the rigidity of the upper coupling shaft part 28b is lower than the rigidity of the lower coupling shaft part 34b.

According to the pixel shifting device 10 related to the present embodiment, by relatively decreasing the rigidity of the upper coupling shaft part 28b to which the thrust forces of the second actuators 26 are difficult to transfer while relatively increasing the rigidity of the lower coupling shaft part 34b to which the thrust forces of the second actuators 26 are easy to transfer, it is possible to evenly transfer the thrust forces of the second actuators 26 in the vertical direction Z along the second oscillation axis J2 of the second frame 22. Thus, by making the torsional angles of the upper coupling shaft part 28b and the lower coupling shaft part 34b substantially coincide with each other, it is possible to rotate the optical member 20 around the second oscillation axis J2 in a balanced manner to accurately shift the light path of the image light LT. Further, in the pixel shifting device 10 according to the present embodiment, since the difference in load is difficult to occur between the coupling shaft parts 28b, 34b due to the difference in torsional angle, by increasing the durability of the upper coupling shaft part 28b and the lower coupling shaft part 34b, it is possible to provide a device higher in reliability.

In the pixel shifting device 10 according to the present embodiment, since the second actuators 26 are intensively arranged at one side in the direction along the second oscillation axis J2, an area in which the interference with the second actuators 26 is not required to be considered increases compared to when the second actuators 26 are arranged on the first oscillation axis J1, and therefore, it becomes easy to lay out the image generator 4 to the pixel shifting device 10.

Further, according to the pixel shifting device 10 related to the present embodiment, since the pair of beams 241 of the pair of first oscillation shaft formation parts 24 for coupling the first frame 21 and the second frame 22 to each other are formed along the obverse surface 22b of the second frame 22, it is possible to increase the strength of the second frame 22. Therefore, in the pixel shifting device 10 according to the present embodiment, by increasing the strength of the coupling portion in the second frame 22 to the first frame 21 using the pair of first oscillation shaft formation parts 24, it is possible to prevent a deformation and a breakage of the second frame 22 even when, for example, a load caused by a vibration in transportation or a load caused by an impact due to a drop is applied.

Therefore, even when adopting what is constituted by a large-sized and lightweight member as the second frame 22 by increasing the size of the optical member 20 of the pixel shifting device 10, it is possible to provide a resistance to a load caused by an impact by increasing the strength of the second frame 22. Therefore, according to the pixel shifting device 10 related to the present embodiment, even when adopting a structure in which the first actuator 25 and the second actuators 26 are intensively arranged at one side of the second frame 22 light in weight and large in size, it is possible to provide a device in which the second frame 22 is provided with the resistance to a load caused by an impact, and which is high in reliability.

Further, in the pixel shifting device 10 according to the present embodiment, the first actuator 25 and the second actuators 26 are intensively arranged at one side of the second frame 22 with respect to the first oscillation axis J1, and it becomes easy for the stress generated due to the drive forces of the first actuator 25 and the second actuators 26 to be concentrated in the second frame 22. To cope with the above, since the deformation of the second frame 22 is suppressed by increasing the rigidity using the lower base coupling member 29, it is possible for the pixel shifting device 10 according to the present embodiment to accurately control the posture of the optical member 20 which is held via the first frame 21.

Further, since the deformation of the second frame 22 is difficult to occur, it is possible to prevent, for example, the second frame 22 or the optical member 20 held by the second frame 22 via the first frame 21 from moving in the front-back direction Y to make contact with the image generator 4. Therefore, according to the pixel shifting device 10 related to the present embodiment, it is possible to arrange the pixel shifting device 10 in the state of coming closer to the image generator 4 in the front-back direction Y. Therefore, it is possible to reduce the size in the front-back direction Y of the projector 1 according to the present embodiment.

Further, in the pixel shifting device 10 according to the present embodiment, by the lower base coupling member 29 increasing the rigidity, an amount of distortion caused by the stress of the second frame 22 is reduced, and it is possible to prevent the vibration of the second actuators 26 from attenuating to efficiently oscillate the second frame 22. Therefore, it is possible to efficiently use the drive forces of the second actuators 26 for the rotation of the second frame 22, and therefore, it is possible to drive the second actuators 26 in an energy-saving manner.

According to the projector 1 related to the present embodiment, since there is provided the pixel shifting device 10 excellent in durability, it is possible to project a high-quality image for a long period of time.

Further, according to the projector 1 related to the present embodiment, since the pixel shifting device 10 described above is provided, the projector 1 becomes excellent in resistance to the load caused by a vibration in transportation or by an impact due to a drop. Further, since it is possible to adopt one large in size as the optical member 20 in the pixel shifting device 10, it is possible to use the large-sized panels as the liquid crystal panels 4RP, 4GP, and 4BP, and thus, it is possible to project a bright image on the screen SCR.

Further, since the projector 1 according to the present embodiment is provided with the pixel shifting device 10 capable of driving the second frame 22 in an energy-saving manner, it is possible to keep the power consumption of the projector low.

It should be noted that the scope of the present disclosure is not limited to the embodiment described above, and a variety of modifications can be provided thereto within the scope or the spirit of the present disclosure.

Besides the above, the specific configurations of the number, the arrangement, the shape, the material, and so on of each of the constituents constituting the light source device are not limited to those of the embodiments described above, but can arbitrarily be modified.

There is cited when the pixel shifting device 10 according to the present embodiment is provided with the pair of first actuators 25 as an example, but it is possible to adopt a configuration provided with a single first actuator 25 alone. Also in this case, the second actuators 26 are arranged at the side at which the first actuator 25 is arranged.

In the embodiment described above, the upper coupling shaft part 28b and the lower coupling shaft part 34b are made different in widths W1, W2 from each other to thereby be made different in rigidity, but the measure for making the upper coupling shaft part 28b and the lower coupling shaft part 34b different in rigidity from each other is not limited thereto.

MODIFIED EXAMPLES

FIG. 9A and FIG. 9B are each an enlarged view showing a configuration of an essential part of the pixel shifting device according to a modified example. FIG. 9A shows an essential part of the lower base coupling member 29 for coupling the base 23 and the second frame 22 to each other, and FIG. 9B shows an essential part of the upper base coupling member 28 for coupling the base 23 and the second frame 22 to each other.

As shown in FIG. 9A, in a pixel shifting device 10A according to the present modified example, the lower base coupling member 29 couples the base 23 and the second frame 22 to each other at the lower side (−Z) in the vertical direction Z of the second frame 22. The lower base coupling member 29 is fixed to the base 23 and the second frame 22 via first screw members 61.

Further, as shown in FIG. 9B, in the pixel shifting device 10A according to the present modified example, the upper base coupling member 28 couples the base 23 and the second frame 22 to each other at the upper side (+Z) in the vertical direction Z of the second frame 22. The upper base coupling member 28 is fixed to the base 23 and the second frame 22 via second screw members 62.

As shown in FIG. 9A and FIG. 9B, in the present modified example, the lower coupling shaft part 34b and the upper coupling shaft part 28b adjust a first distance D1 from a head part 61a of the first screw member 61 to the lower coupling shaft part 34b and a second distance D2 from a head part 62a of the second screw member 62 to the upper coupling shaft part 28b to thereby make the lower coupling shaft part 34b and the upper coupling shaft part 28b different in rigidity from each other. It should be noted that in the case of the present modified example, the lower coupling shaft part 34b and the upper coupling shaft part 28b have the same thickness.

Specifically, the first distance D1 from the head part 61a of the first screw member 61 to the lower coupling shaft part 34b is shorter than the distance D2 from the head part 62a of the second screw member 62 to the upper coupling shaft part 28b. It should be noted that the distance between the head part of the screw member and the coupling shaft part means the shortest distance between an outer shape of the head part of the screw member and an outer shape of the coupling shaft part.

In the case of the present modified example, the first screw member 61 and the second screw member 62 are formed of the same material. In other words, the head part 61a of the first screw member 61 and the head part 62a of the second screw member 62 have the same size. Further, a distance from a screw hole for fastening the first screw member 61 to the lower coupling shaft part 34b is shorter than a distance from a screw hole for fastening the second screw member 62 to the upper coupling shaft part 28b. It should be noted that a distance between two screw holes means a center-to-center distance between the screw holes.

According to this configuration, the upper coupling shaft part 28b relatively decreases in rigidity since the distance to a fastening part with the screw member becomes longer compared to the lower coupling shaft part 34b. Therefore, also in the pixel shifting device 10A according to the present modified example, it is possible to make the rigidity of the upper coupling shaft part 28b lower than the rigidity of the lower coupling shaft part 34b.

It should be noted that the distance from the screw hole for fastening the first screw member 61 to the lower coupling shaft part 34b and the distance from the screw hole for fastening the second screw member 62 to the upper coupling shaft part 28b can be the same as each other.

In this case, the head part 61a of the first screw member 61 is made larger than the head part 62a of the second screw member 62. Thus, since the first distance D1 from the head part 61a of the first screw member 61 to the lower coupling shaft part 34b becomes shorter than the second distance D2 from the head part 62a of the second screw member 62 to the upper coupling shaft part 28b, it is possible to make the rigidity of the upper coupling shaft part 28b lower than the rigidity of the lower coupling shaft part 34b.

It should be noted that in the configuration shown in FIG. 9A and FIG. 9B, it is possible to perform a fine adjustment on the rigidity of each of the upper coupling shaft part 28b and the lower coupling shaft part 34b by making the size of the head part 61a of the first screw member 61 and the size of the head part 62a of the second screw member 62 different from each other. Thus, it is possible to more easily perform the adjustment of the rigidity of each of the upper coupling shaft part 28b and the lower coupling shaft part 34b.

Hereinafter, the conclusion of the present disclosure will supplementarily be noted.

Supplementary Note 1

A pixel shifting device including an optical member, a first frame which is configured to hold the optical member, and which oscillates around a first oscillation axis, a second frame which is arranged on a periphery of the first frame, which is coupled to the first frame, and which oscillates around a second oscillation axis perpendicular to the first oscillation axis, a base which is arranged on a periphery of the second frame, and which is coupled to the second frame, a pair of first oscillation shaft formation parts which are located on the first oscillation axis, and which are configured to couple the first frame and the second frame to each other, a pair of second oscillation shaft formation parts which are located on the second oscillation axis, and which are configured to couple the second frame and the base to each other, a first actuator which is arranged on the second oscillation axis, and which is configured to oscillate the first frame with respect to the second frame between the first frame and the second frame, and a pair of second actuators which are respectively held by a pair of actuator holding parts, and which are configured to oscillate the second frame with respect to the base, the pair of actuator holding parts being disposed at a side of the second frame and the base where the first actuator is arranged, and being arranged across the second oscillation axis, wherein the pair of second oscillation shaft formation parts include a one-side coupling shaft part configured to couple the second frame and the base to each other at the actuator holding parts side, and another-side coupling shaft part configured to couple the second frame and the base to each other at an opposite side to the actuator holding parts, and the another-side coupling shaft part is lower in rigidity than the one-side coupling shaft part.

According to the pixel shifting device having this configuration, by relatively decreasing the rigidity of the another-side coupling shaft part to which the thrust forces of the second actuators are difficult to transfer while relatively increasing the rigidity of the one-side coupling shaft part to which the thrust forces of the second actuators are easy to transfer, it is possible to evenly transfer the thrust forces of the second actuators in a direction along the second oscillation axis of the second frame. Thus, by making the torsional angles of the another-side coupling shaft part and the one-side coupling shaft part substantially coincide with each other, it is possible to rotate the optical member around the second oscillation axis in a balanced manner to accurately shift the light path of the image light.

Further, in the pixel shifting device having this configuration, since the difference in load is difficult to occur between the coupling shaft parts due to the difference in torsional angle, by increasing the durability of the coupling shaft parts, it is possible to provide a device higher in reliability.

Further, in the pixel shifting device, since an area in which the interference with the second actuators is not required to be considered increases compared to the configuration in which the second actuators are arranged on the first oscillation axis by intensively arranging the second actuators at one side in the direction along the second oscillation axis, it becomes easy to lay out other components to the pixel shifting device.

Supplementary Note 2

The pixel shifting device described in Supplementary Note 1, wherein each of the pair of first oscillation shaft formation parts has a coupling shaft part configured to couple the first frame and the second frame to each other, and the coupling shaft parts are equal in rigidity to each other.

According to this configuration, since the thrust force of the first actuator is transferred evenly to the pair of coupling shaft parts, it is also possible to prevent an occurrence of the torsion when the first frame rotates around the first oscillation axis.

Supplementary Note 3

The pixel shifting device described in one of Supplementary Note 1 and Supplementary Note 2, wherein the another-side coupling shaft part is lower in second moment of area than the one-side coupling shaft part.

According to this configuration, since the rigidity of the another-side coupling shaft part becomes lower than the rigidity of the one-side coupling shaft part, the another-side coupling shaft part becomes easier to twist than the one-side coupling shaft part. Therefore, the thrust forces of the second actuators evenly transfer in the direction along the second oscillation axis of the second frame, and it is possible to make the torsional angles of the another-side coupling shaft part and the one-side coupling shaft part coincide with each other.

Supplementary Note 4

The pixel shifting device described in any one of Supplementary Note 1 through Supplementary Note 3, wherein the pair of actuator holding parts provided to the second frame are formed of a part of the pair of second oscillation shaft formation parts, and each hold one of a magnet and a coil constituting the second actuator.

According to this configuration, since the second oscillation shaft formation part also functions as a holding part for holding one of the magnet and the coil constituting the second actuator, it is possible to achieve simplification of the structure.

Supplementary Note 5

The pixel shifting device described in any one of Supplementary Note 1 through Supplementary Note 3, wherein the another-side coupling shaft part and the one-side coupling shaft part are different in at least one of shape, width, length, and thickness from each other to thereby be made different in rigidity from each other.

According to this configuration, it is possible to easily realize the configuration in which the rigidity of the another-side coupling shaft part is made lower than the rigidity of the one-side coupling shaft part by adjusting the rigidity of each of the another-side coupling shaft part and the one-side coupling shaft part.

Supplementary Note 6

The pixel shifting device described in any one of Supplementary Note 1 through Supplementary Note 3, wherein the pair of second oscillation shaft formation parts include a one-side coupling part which has the one-side coupling shaft part, and which is configured to couple the second frame and the base to each other with a first screw member, and another-side coupling part which has the another-side coupling shaft part, and which is configured to couple the second frame and the base to each other with a second screw member, and the one-side coupling part and the another-side coupling part are made different in rigidity from each other by adjusting a distance from a head part of the first screw member to the one-side coupling shaft part and a distance from a head part of the second screw member to the another-side coupling shaft part.

According to this configuration, by making the distance to the fastening part with the screw member of the another-side coupling shaft part longer compared to the distance to the fastening part with the screw member of the one-side coupling shaft part, it is possible to make the rigidity of the another-side coupling shaft part lower than the rigidity of the one-side coupling shaft part.

Supplementary Note 7

The pixel shifting device described in any one of Supplementary Note 1 through Supplementary Note 3, wherein the pair of second oscillation shaft formation parts include a one-side coupling part which has the one-side coupling shaft part, and which is configured to couple the second frame and the base to each other with a first screw member, and another-side coupling part which has the another-side coupling shaft part, and which is configured to couple the second frame and the base to each other with a second screw member, and the one-side coupling part and the another-side coupling part are made different in rigidity from each other by adjusting a distance from a screw hole of the first screw member to the one-side coupling shaft part and a distance from a screw hole of the second screw member to the another-side coupling shaft part.

According to this configuration, by making the distance to the screw hole for fastening the another-side coupling shaft part longer compared to the distance to the screw hole for fastening the one-side coupling shaft part, it is possible to make the rigidity of the another-side coupling shaft part lower than the rigidity of the one-side coupling shaft part.

Supplementary Note 8

A projector including an image generator configured to generate image light, a projection optical system configured to project the image light, and the pixel shifting device described in any one of Supplementary Note 1 through Supplementary Note 7 which is arranged between the image generator and the projection optical system, and which is configured to shift a light path of the image light from the image generator.

According to the projector having this configuration, since there is provided the pixel shifting device excellent in durability, it is possible to project a high-quality image for a long period of time.

Supplementary Note 9

The projector described in Supplementary Note 8, wherein the image generator includes a first light modulation device which has a first light exit surface, and which is arranged so that the first light exit surface faces toward the projection optical system, a second light modulation device which has a second light exit surface, and which is arranged so that the second light exit surface faces to a direction perpendicular to a direction in which the first light modulation device and the projection optical system are arranged side by side, a third light modulation device which has a third light exit surface, and which is arranged so that the third light exit surface is opposed to the second light exit surface of the second light modulation device, and a light combining element which is configured to combine light beams respectively emitted from the first light modulation device, the second light modulation device, and the third light modulation device with each other to generate the image light, and then emits the image light toward the projection optical system, the optical member of the pixel shifting device is arranged on the light path of the image light between the projection optical system and the light combining element, and in a direction along the second oscillation axis, end portions at the projection optical system side of the second light modulation device and the third light modulation device are respectively arranged at positions distant from the second actuators of the pixel shifting device.

According to this configuration, since the second light modulation device and the third light modulation device are respectively arranged at the positions distant from the second actuators of the pixel shifting device in the direction along the second oscillation axis, it is possible to achieve a further reduction in size of the device configuration by arranging the second light modulation device and the third light modulation device closer to the pixel shifting device.

PIXEL SHIFTING DEVICE AND PROJECTOR

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