Optical path changing element and projector

Abstract

This optical path changing element comprises: a base member; a lens; a frame that holds the lens; an actuator that is provided on a first surface of the base member and that causes the frame to oscillate via vibrations; and an off-light plate that is disposed so as to be separated, by a prescribed distance, from a second surface of the base member opposite the first surface, and that receives unnecessary light which does not pass through the lens. A hole region having a plurality of holes is formed in some of the regions of the base member which overlap the off-light plate in plan view.

Description

Optical path changing element and projector

[0001] The present disclosure relates to a light-path changing element and a projector including the light-path changing element.

[0002] 2. Description of the Related Art Conventionally, a wobbling operation is known in which an optical member is swung to shift the optical path of image light incident on the optical member, thereby increasing resolution.

[0003] Patent Document 1 discloses an optical path shift device (optical path changing element) that includes a glass plate into which light enters a rectangular optical region in a planar view, a first actuator that displaces the glass plate around a first axis that passes through the center of the optical region in a planar view and forms an angle of less than 90° with a first side of the optical region, and a second actuator that displaces the glass plate around a second axis that passes through the center of the optical region and is perpendicular to the first axis.

[0004] JP 2022-82000 A Patent No. 6432744 A

[0005] The optical path changing element includes an off-light plate that receives unnecessary light that is not used for projecting an image. The off-light plate generates heat when it receives the unnecessary light. The actuator included in the optical path changing element includes at least a coil and a magnet. If the heat generated by the off-light plate increases the temperature of the coil and magnet of the actuator, the thrust force of the coil and the magnetic force of the adjacent magnet will decrease, which is a problem.

[0006] An object of the present disclosure is to provide a technology for suppressing a rise in temperature of a coil that constitutes an actuator.

[0007] The present disclosure provides an optical path changing element comprising: a base member, a lens, a frame for holding the lens; an actuator provided on a first surface of the base member for oscillating the frame by vibration; and an off-light plate positioned a predetermined distance from a second surface of the base member opposite the first surface and for receiving unwanted light that does not pass through the lens, wherein a hole region having a plurality of holes is formed in a portion of the base member that overlaps with the off-light plate in a planar view.

[0008] According to the present disclosure, the thermal conductivity of the hole area is lower than that of other areas, making it difficult for heat from the off-light plate to be conducted to the coil and magnet of the actuator, thereby suppressing the temperature rise of the coil and magnet of the actuator.

[0009] FIG. 1 is an overall view illustrating the configuration of an optical system of a projector including a light-path changing element according to the present disclosure;

[0010] Hereinafter, embodiments of the present disclosure will be described in detail with appropriate reference to the drawings. However, more detailed description than necessary may be omitted. For example, detailed descriptions of well-known matters and redundant descriptions of substantially identical configurations may be omitted. This is to avoid unnecessary redundancy in the following description and to facilitate understanding by those skilled in the art. Note that the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

[0011] 1 is an overall view for explaining the configuration of an optical system of a projector 200 including an optical path changing element 100 according to the present disclosure. In the following explanation, an X1Y1Z1 Cartesian coordinate system is set as shown in FIG.

[0012] <Overall Configuration> The laser light source is composed of multiple blue semiconductor lasers 301 to realize a high-brightness lighting device. Laser light emitted from each blue semiconductor laser 301 is collimated by a corresponding collimator lens 302. The light emitted from collimator lens 302 becomes approximately parallel light, and the entire light beam is collected by condenser lens 303. After passing through diffuser plate 304, the light is again approximately parallelized by lens 305. The laser light beam approximately parallelized by lens 305 is incident on dichroic mirror 306, which is positioned at approximately 45 degrees to the optical axis.

[0013] The diffusion plate 304 is a flat glass plate, and one side of the diffusion plate is formed with minute irregularities. The dichroic mirror 306 has the property of reflecting light in the wavelength range of the blue semiconductor laser 301 and transmitting light in other wavelength ranges.

[0014] The laser light incident on dichroic mirror 306 in the −X1 direction is reflected by dichroic mirror 306 and emitted in the −Z1 direction. The laser light is then condensed by condenser lenses 307 and 308 and excites the phosphor formed on phosphor wheel 320.

[0015] The phosphor wheel 320 has segments on which red and green phosphors are formed in the circumferential direction on a disk-shaped substrate, and further has openings as light-transmitting regions.

[0016] Red light and green light obtained from the red phosphor and green phosphor of phosphor wheel 320, respectively, are emitted from phosphor wheel 320. These red light and green light are approximately parallelized by condenser lenses 308 and 307, transmitted through dichroic mirror 306, condensed by condenser lens 317, and incident on rod integrator 318.

[0017] On the other hand, the blue light from blue semiconductor laser 301 that passes through the opening of phosphor wheel 320 travels via lens 309, lens 310, mirror 311, lens 312, mirror 313, lens 314, mirror 315, and lens 316, is reflected by dichroic mirror 306, is collected by collecting lens 317, and enters rod integrator 318. Lenses 312, 314, and 316 function as relay lenses.

[0018] The light emitted from rod integrator 318 passes through lenses 330, 331, and 332 and enters total reflection prism 335, which is made up of a pair of prisms 333 and 334. DMD (Digital Mirror Device) 336, which is a light modulation element, modulates the incident light with a video signal and emits it as video light. Lenses 330 and 331 function as relay lenses, and lens 332 functions to form an image of the light from the exit surface of rod integrator 318 on DMD 336.

[0019] The image light emitted from the DMD 336 is incident on a light transmitting member 101a disposed in the optical path changing element 100. The light transmitted through the light transmitting member 101a is incident on a projection lens unit 337, and the light emitted from the projection lens unit 337 is enlarged and projected onto a screen as image light.

[0020] The optical path changing element 100 can move the display position of the image light by displacing the light transmitting member 101a so that the optical axis of the light transmitting member 101a is tilted with respect to the optical axis AL of the projection lens unit 337. This function allows the projector 200 to perform a wobbling display. Here, the wobbling display is a method of displaying different images while shifting the display position multiple times during one frame period of the input image, thereby equivalently improving the resolution of the displayed image, and is also called a pixel shift display. A drive control device (e.g., a control device 910 described later) drives the first actuator 103 and the second actuator 104 (see FIG. 2 ) based on a control signal synchronized with the drive of the DMD 336.

[0021] <Configuration of Light Path Changing Element> Conventionally, for example, in a projector equipped with a light path shift changing device as disclosed in Patent Document 1, it is possible to improve resolution by wobbling. However, there is a problem in that the size increases due to the installation of a large number of actuators and the like to realize wobbling. In the present embodiment 1, a technique for miniaturizing a projector with a wobbling function is disclosed.

[0022] Fig. 2 is a perspective view showing a configuration example of the optical path changing element 100 according to the first embodiment. Fig. 3 is a cross-sectional perspective view showing a configuration example of the optical path changing element 100 according to the second embodiment.

[0023] The optical path changing element 100 comprises a base member 101, a lens 102, a first actuator 103, a second actuator 104, a first movable frame 105, a second movable frame 106, a first hinge 107, and a second hinge 108.

[0024] The base member 101 is plate-shaped and has a rectangular shape with a portion near one vertex cut out at an angle. The vertex on the side of the base member 101 that is not cut out at an angle is referred to as the vertex 110, one side extending from the vertex 110 is referred to as the first side 111, and the other side extending from the vertex 110 is referred to as the second side 112.

[0025] 3, the protruding portion 400 of the prism 334 is located in the obliquely cut portion of the base member 101. This allows the prism 334 and the optical path changing element 100 to be closer to each other, thereby enabling the projector 200 to be made smaller.

[0026] The first actuator 103 is disposed on the first surface 401 of the base member 101 along the first side 111. The first actuator 103 includes at least a coil and a magnet, and is capable of vibrating in a direction perpendicular to the first surface 401. Details of the configuration of the first actuator 103 will be described in the second embodiment.

[0027] The second actuator 104 is disposed on the first surface 401 of the base member 101 along the second side 112. The second actuator 104 includes at least a coil and a magnet, and is capable of vibrating in a direction perpendicular to the first surface 401. Details of the configuration of the second actuator 104 will be described in the second embodiment.

[0028] The first movable frame 105 constitutes a frame that holds the lens 102. In other words, the lens 102 is fixed to the first movable frame 105. The lens 102 is an example of a light-transmitting member 101a. The lens 102 refers to an optical body that transmits light, and includes those that have a light-condensing function and those that do not. The lens 102 may also be a parallel plate glass. One end of the first movable frame 105 is connected to the first actuator 103. The first movable frame 105 rotates about an axis due to vibration of the first actuator 103, and first hinges 107 are connected to both ends of the rotation axis (hereinafter referred to as the first axis 421). The first hinges 107 are then connected to the second movable frame 106. An opening is provided in the area of ​​the base member 101 that overlaps with the lens 102 in a planar view. The light that has passed through the lens 102 passes through the opening and enters the projection lens unit 337 .

[0029] The second movable frame 106 constitutes a frame having an opening at a location corresponding to the lens 102. The second movable frame 106 is disposed between the first movable frame 105 and the base member 101. The first movable frame 105 is connected to the second movable frame 106 by a first hinge 107. The second movable frame 106 also rotates on an axis due to vibration of the second actuator 104, and second hinges 108 are connected to both ends of the axis of rotation (hereinafter referred to as second axis 422). The second hinges 108 are then connected to the base member 101.

[0030] Next, the operation of swinging the lens 102 (that is, the wobbling operation) will be described.

[0031] When the first actuator 103 is driven to vibrate, the tilt of the first movable frame 105 and the lens 102 relative to the first surface 401 of the base member 101 changes around a first axis 421 passing through the first hinge 107 as the axis of rotation.

[0032] When the second actuator 104 is driven to vibrate, the second movable frame 106 changes its tilt with respect to the first surface 401 of the base member 101, with the second axis 422 passing through the second hinge 108 as the axis of rotation. Because the second movable frame 106 is connected to the first movable frame 105 by the first hinge 107, the change in tilt of the second movable frame 106 also changes the tilt of the first movable frame 105 and the lens 102.

[0033] Therefore, by driving the first actuator 103 and the second actuator 104 to vibrate, the lens 102 can be swung relative to the first surface 401 of the base member 101. This allows for wobbling, thereby increasing the resolution of the projected image.

[0034] As described above, the configuration of the optical path changing element 100 according to this embodiment makes it possible to realize wobbling using two actuators (103, 104). As a result, as described above, the vicinity of one vertex of the rectangle of the base member 101 (for example, the vertex farthest from the vertex 110) can be obliquely cut out, and the protruding portion 400 (reflecting surface) of the prism 334 can be disposed in this obliquely cut portion (i.e., near the first hinge 107 and the second hinge 108). In other words, at least a portion of the reflecting surface 412 of the prism 333 is located between the optical path changing element 100 and the projection lens unit 337 in the projection direction of the image light. Furthermore, at least another portion of the reflecting surface 412 of the prism 333 is located at a position other than between the optical path changing element 100 and the projection lens unit 337 in the projection direction of the image light. Therefore, interference between the protruding portion 400 of the prism 334 and the base member 101 can be avoided. As a result, the distance between the prism 333 and the base member 101 can be made shorter, and the projector 200 can be made smaller.

[0035] In a conventional configuration in which four actuators are arranged two by two to achieve wobbling, it is difficult to cut out a portion of the base member as in the present embodiment, and as a result, it is impossible to avoid interference between the protrusion 400 of the prism 334 and the base member. Therefore, in the conventional configuration, the distance between the prism 333 and the base member becomes large, making it difficult to reduce the size of the projector 200.

[0036] Furthermore, according to the configuration of the optical path changing element 100 according to this embodiment, wobbling can be achieved using two actuators (103, 104) without arranging the actuators opposite to each other (asymmetric arrangement) with respect to the first axis 421 and the second axis 422. Therefore, compared to the conventional configuration in which wobbling is achieved by arranging four actuators two by two opposite to each other, the number of parts can be reduced, and as a result, costs can be reduced.

[0037] Summary of First Embodiment The above description of the first embodiment discloses the following techniques.

[0038] <Technology A1> A projector (200) includes an image light modulation element (e.g., DMD 336) that modulates light from a light source into image light, a projection lens unit (337) that projects the modulated image light, a prism (e.g., prisms 333, 334) that guides light from the light source to the image light modulation element, and an optical path changing element (100) that is located between the image light modulation element and the projection lens unit in the projection direction of the image light and changes the optical path of the image light, wherein at least a portion of the prism is located between the optical path changing element and the projection lens unit in the projection direction of the image light. At least another portion of the prism is located in a position other than between the optical path changing element and the projection lens unit in the projection direction of the image light. This allows the distance between the optical path changing element and the prism to be reduced, thereby making it possible to reduce the size of the projector.

[0039] <Technology A2> In the projector described in Technology A1, the prism has a reflective surface that reflects light from the light source, and at least a part of the reflective surface of the prism is located between the optical path changing element and the projection lens in the projection direction of the image light. At least another part of the reflective surface of the prism is located at a position other than between the optical path changing element and the projection lens in the projection direction of the image light. This allows the distance between the optical path changing element and the prism to be reduced, and the projector to be made smaller.

[0040] <Technology A3> In the projector described in Technology A2, the optical path changing element includes a lens (102), a frame (e.g., a first movable frame 105) that holds the lens, an actuator (e.g., a first actuator 103) that vibrates one end of the frame in the projection direction, and a hinge (e.g., a first hinge 107) that is disposed on a rotation axis that rotates the frame by the vibration of the actuator and is connected to the frame, and the reflecting surface of the prism is located closer to the hinge than to the actuator. This allows the optical path changing element and the prism to be closer to each other, thereby making it possible to miniaturize the projector.

[0041] (Embodiment 2) In a conventional light path shift device, such as that disclosed in Patent Document 1, the actuator includes at least a coil and a magnet, and is driven by a current flowing through the coil. The current causes the coil temperature to rise, which reduces the driving force of the coil and the magnetic force of the adjacent magnet. In this embodiment 2, a technique for suppressing the temperature rise of the coil constituting the actuator is disclosed.

[0042] 4 is an exploded perspective view showing an example of the configuration of the first actuator 103 according to the second embodiment. The second actuator 104 has the same configuration as the first actuator 103, and therefore a description thereof will be omitted here. The contents described in the first embodiment also apply to the second embodiment.

[0043] As shown in FIG. 4, the first actuator 103 includes, in order from the closest to the first surface 401 of the base member 101 , a yoke 121 , a magnet 122 , a coil 123 , a heat conductive material 124 , and a heat conductive holding frame 125 .

[0044] The first movable frame 105 is disposed between the base member 101 and the first actuator 103 .

[0045] The thermally conductive material 124 has thermal conductivity and is disposed between the coil 123 and the thermally conductive holding frame 125. The thermally conductive material 124 may be a thermally conductive sheet. Alternatively, the thermally conductive material 124 may be a thermally conductive gel or grease.

[0046] The thermally conductive holding frame 125 covers (holds) the yoke 121 , the magnet 122 , the coil 123 and the thermally conductive material 124 , and is fixed to the base member 101 .

[0047] The thermally conductive holding frame 125 contains a material with a higher thermal conductivity than the first movable frame 105 .

[0048] When a current is passed through the coil 123 to drive the coil 123 to vibrate, thereby causing the first movable frame 105 to swing, heat is generated in the coil 123. The heat generated in the coil 123 is conducted by the thermally conductive frame 125, which has a higher thermal conductivity than the thermally conductive material 124 and the first movable frame 105. The heat conducted to the thermally conductive frame 125 is conducted to a position on the base member 101 away from the coil 123 and magnet 122, and is dissipated into the surrounding air via the base member 101.

[0049] This makes it possible to suppress a decrease in the thrust of the coil 123 and a decrease in the magnetic force of the adjacent magnet 122 due to a rise in the temperature of the coil 123 .

[0050] 2, the optical path changing element 100 of this embodiment is configured to oscillate one movable frame with one actuator, and therefore requires a larger thrust from the coil 123 than a conventional configuration in which one movable frame is oscillated with two actuators arranged opposite each other. Therefore, the configuration of this embodiment tends to generate more heat from the coil 123 than the conventional configuration. Therefore, in this embodiment, as described above, the first actuator 103 is provided with a thermally conductive material 124 and a thermally conductive holding frame 125 to enhance heat dissipation capability.

[0051] Summary of Second Embodiment The above description of the second embodiment discloses the following techniques.

[0052] <Technology B1> The optical path changing element (100) comprises a base member (101), a lens (102), a frame (e.g., a first movable frame 105) that holds the lens, and an actuator (e.g., a first actuator 103) attached to the base member and that vibrates the frame. The actuator has at least a magnet (122), a coil (123), and a holder (e.g., a thermally conductive holder frame 125) that holds the coil. The coil is positioned between the frame and the holder, and the holder contains a material with a higher thermal conductivity than the frame. This allows heat generated by the coil to be conducted to the holder, suppressing temperature increases in the coil and magnet. This prevents a decrease in the thrust of the coil and a decrease in the magnetic force of the magnet due to temperature increases.

[0053] <Technology B2> In the optical path changing element described in Technology B1, the actuator further includes a heat conductive material (124) between the coil and the holder. This allows the heat generated by the coil to be more effectively conducted to the holder. This makes it possible to suppress temperature increases in the coil and magnet.

[0054] <Technology B3> In the optical path changing element described in Technology B2, the heat conductive material contains a material with a higher thermal conductivity than the frame. This allows heat generated by the coil to be conducted to the holding part via the heat conductive material rather than to the frame. This makes it possible to suppress temperature increases in the coil and magnet.

[0055] (Embodiment 3) Fig. 5 is a side view showing a configuration example of an optical path changing element 100 according to embodiment 3. Fig. 6 is a perspective view showing a configuration example of an optical path changing element 100 according to embodiment 3. Note that the contents described in embodiments 1 and 2 are also applied to embodiment 3.

[0056] As described in embodiment 1, the surface of the base member 101 on which the first actuator 103 and the like are arranged is referred to as the first surface 401, and the surface opposite to the first surface 401 is referred to as the second surface 402.

[0057] As shown in Fig. 6, the off-light plate 130 is disposed on the second surface 402 of the base member 101. The off-light plate 130 has a blackened portion 131 in a predetermined area close to the lens 102. As shown in Fig. 4, there is a predetermined gap d (e.g., a gap of about 1 mm) between the second surface 402 and the off-light plate 130.

[0058] As shown in FIG. 6 , the off-light plate 130 may be arranged to overlap at least a portion of the area between the first actuator 103 , the second actuator 104 , and the lens 102 in a plan view of the second surface 402 .

[0059] The DMD 336 emits (reflects) image light used for image display toward the lens 102 through the prisms 333 and 334, and emits (reflects) unnecessary light 410 not used for image display toward the black-painted portion 131 of the off-light plate 130 through the prisms 333 and 334. The off-light plate 130 receives this unnecessary light 410 and generates heat.

[0060] Therefore, in this embodiment, a region (hereinafter referred to as hole region 151) having a plurality of holes 150 (e.g., punched holes) penetrating the base member 101 is provided in a region of the base member 101 that overlaps with a portion of the off-light plate 130 in a plan view. By providing the plurality of holes 150 in this manner, the hole region 151 of the base member 101 has a lower thermal conductivity than other regions of the base member 101.

[0061] For example, the hole region 151 may be provided in at least a part of the region of the base member 101 between the first actuator 103 , the second actuator 104 and the lens 102 .

[0062] For example, the hole region 151 may be provided in at least a portion of the region of the base member 101 between the first fixing member 126, the second fixing member 127, and the lens 102. The first fixing member 126 is a member that fixes the thermally conductive frame 125 of the first actuator 103 to the base member 101 and is closer to the vertex 110. The second fixing member 127 is a member that fixes the thermally conductive frame 125 of the second actuator 104 to the base member 101 and is closer to the vertex 110. The thermally conductive frame 125 contains a material with higher thermal conductivity than the base member 101.

[0063] For example, the hole region 151 may be provided so as to at least partially overlap the boundary line 153 of the black painted portion 131 of the off-light plate 130 in a plan view of the base member 101 .

[0064] By providing the hole region 151 in a portion of the base member 101 in this manner, the region of the base member 101 that becomes hot due to the heat generated by the off-light plate 130 can be reduced. Furthermore, by making the thermal conductivity of the thermally conductive holding frame 125 higher than that of the base member 101, the heat of the coil can be conducted and dissipated to a region different from the suppressed high-temperature region of the base member 101. This prevents the heat generated by the off-light plate 130 from being conducted to the coil 123 and magnet 122 through the base member 101, thereby preventing the temperature of the coil 123 and magnet 122 from increasing, and allows the heat of the coil to be dissipated to a desired position on the base plate 101. In other words, it is possible to prevent a decrease in the thrust of the coil 123 and a decrease in the magnetic force of the adjacent magnet 122 due to a temperature increase.

[0065] Summary of Third Embodiment The above description of the third embodiment discloses the following techniques.

[0066] <Technology C1> The optical path changing element (100) includes a base member (101), a lens (102), a frame (e.g., a first movable frame 105) that holds the lens, an actuator (e.g., a first actuator 103) attached to a first surface (401) of the base member and that vibrates to oscillate the frame, and an off-light plate (130) that is positioned a predetermined distance from a second surface (402) of the base member opposite the first surface and receives unwanted light 410 that does not pass through the lens. A hole region (151) having a plurality of holes is formed in a portion of the base member that overlaps with the off-light plate in a planar view. This reduces the thermal conductivity in the hole region, thereby preventing heat generated by the off-light plate due to reception of unwanted light 410 from being transmitted through the base member to the coil and magnet included in the actuator. This prevents temperature increases in the coil and magnet included in the actuator. This prevents a decrease in the thrust force of the coil and a decrease in the magnetic force of the magnet due to temperature increases.

[0067] <Technology C2> The optical path changing element described in Technology C1 further includes: a first frame (e.g., first movable frame 105); a first actuator (e.g., first actuator 103); a second frame (e.g., second movable frame 106) partially in contact with the first frame; and a second actuator (e.g., second actuator 104) provided on the first surface of the base member and vibrating to oscillate the second frame; and the hole region is formed in a partial region of the base member between the first actuator, the second actuator, and the lens. This makes it possible to suppress temperature increases in the coils and magnets included in the first actuator and the second actuator, respectively. That is, it is possible to suppress decreases in the thrust of the coils and the magnetic force of the magnets due to temperature increases.

[0068] <Technology C3> In the optical path changing element described in Technology C2, the first actuator and the second actuator each have at least a magnet (122), a coil (123), and a holder that holds the coil (for example, a thermally conductive holding frame 125), the first actuator is arranged along a first side (111) extending from a predetermined vertex (110) of the base member, and the holder of the first actuator is fixed to the base member by at least a first fixing member (126) located on the side closer to the vertex (110), the second actuator is arranged along a second side (112) extending from the vertex (110) of the base member, and the holder of the first actuator is fixed to the base member by at least a second fixing member (142) located on the side closer to the vertex, and the hole region is formed in a partial region of the base member between the position of the first fixing member, the position of the second fixing member, and the lens. This makes it possible to suppress temperature increases in the coils and magnets included in the first actuator and the second actuator, thereby suppressing decreases in the thrust force of the coils and the magnetic force of the magnets due to temperature increases.

[0069] <Technology C4> In the optical path changing element described in Technology C3, the thermal conductivity of the first fixing member and the second fixing member is greater than the thermal conductivity of the base member, thereby making it possible to conduct heat more efficiently through the first fixing member and the second fixing member than through the base member.

[0070] Fourth Embodiment In a fourth embodiment, a method for controlling the optical path changing element 100 shown in the first, second, and third embodiments will be described.

[0071] For example, Patent Document 2 (Japanese Patent No. 6432744) discloses a configuration in which a square-shaped parallel plate glass is connected to four actuators. In this configuration, each of the four actuators is disposed at the center of each side of the outer periphery of the parallel plate glass. Each of the disposed actuators faces one of the other actuators. In other words, in this configuration, the actuators are disposed symmetrically. In such a configuration in which the actuators are disposed symmetrically, by displacing a pair of actuators disposed opposite each other across the parallel plate glass by the same amount in opposite directions, the parallel plate glass can be tilted while maintaining the two axes of the rotation centers of the parallel plate glass perpendicular to each other.

[0072] However, in the optical path changing element 100 according to the first embodiment, the arrangement of the actuators (103, 104) is asymmetric. For example, with reference to FIG. 7 , a case will be considered in which the first actuator 103 rotates the optical path changing element around the first axis 421 as the center of rotation. FIG. 7 is a schematic diagram for explaining the rotation of the first movable frame 105 according to the fourth embodiment. Note that in the explanations of FIG. 7 and FIGS. 8 and 10 described below, a three-dimensional coordinate system consisting of the X-axis, the Y-axis, and the Z-axis will be used. It is also assumed that the orientations of the axes correspond to each other in each figure. When the first actuator 103 rotates the first movable frame 105 around the first axis 421 as the center of rotation, the rotation may cause a disturbance to the second actuator 104. This is because, due to the asymmetric arrangement of the actuators, the orthogonality of the two axes (421, 422) serving as the centers of rotation may not be maintained, unlike in the case in which four actuators are symmetrically arranged in the related art. In other words, the center position of the movable range of rotation about the first axis 421 may not overlap with the center position of the movable range of rotation about the second axis 422. Similarly, although not shown in FIG. 7 , when the second actuator 104 rotates the second movable frame 106 about the second axis 422, this rotation may cause a disturbance to the first actuator 103. If a disturbance occurs due to the rotation of the other movable frame, it may become difficult to control the actuator based on the error between the actuator position detected by a position sensor (described below) and the target value. This may make it difficult to control the tilt of the movable frame with high precision. Therefore, a method for accurately controlling the tilt of the movable frame even when the actuators are asymmetrically arranged will be described with reference to FIGS. 8 to 11 .

[0073] FIG. 8 is a schematic diagram for explaining a method of controlling the optical path changing element 100 according to the fourth embodiment.

[0074] The optical path changing element 100 further includes a position sensor 900A that detects the position of a movable part (not shown) of the first actuator 103, and a position sensor 900B that detects the position of a movable part (not shown) of the second actuator 104. Hereinafter, when the first actuator 103 and the second actuator 104 are commonly described, they may be simply referred to as actuators. This also applies to the position sensors 900A and 900B. In the following description, the movable range of the movable part of the actuator may be referred to as the movable range of the actuator, and the position of the movable part of the actuator may be referred to as the position of the actuator. Furthermore, in the following description, the expression "vibration of the actuator" refers to the vibration of the movable part of the actuator.

[0075] The control device 910 that executes the control method for the optical path changing element 100 may be configured, for example, with a microcomputer, a CPU, an MPU, a GPU, a DSP, an FPGA, an ASIC, or the like. The control device 910 includes at least an integration control circuit 911A, an integration control circuit 911B, an adder circuit 913A, an adder circuit 913B, a drive circuit 915A, and a drive circuit 915B. Although not shown in the figure, the control device 910 may also include circuits that can generate values ​​of a center position 912A of the movable range of the first actuator 103 and a center position 912B of the movable range of the second actuator 104, as well as drive waveforms 914A and 914B. Hereinafter, when a common description is given for the integration control circuit 911A and the integration control circuit 911B, they may be simply referred to as an integration control circuit. The same applies to the adder circuits 913A and 913B, the drive circuits 915A and 915B, the center positions 912A and 912B, and the drive waveforms 914A and 914B. The functions of the various circuits included in the control device 910 may be realized as software functions. The configuration of the control device 910 is an example, and the control device 910 may include additional components, or multiple components included in the control device 910 may be integrated into a single component.

[0076] The integral control circuit integrates the error between the detected value of the actuator position by the position sensor and the value of the central position of the actuator's movable range. Hereinafter, the value of the central position may be referred to as the median. The detected value may be the average value of the waveform of the actuator's vibration. The average value of the waveform of the actuator's vibration represents the central position of the vibration. The integral control circuit may integrate the error between the detected value of the actuator position and the value of the central position of the actuator's movable range, or may integrate the difference between the value obtained by dividing the integrated value of the detected value of the actuator position by the number of integrations and the median of the actuator's movable range.

[0077] The adder circuit adds the integration result output from the integration control circuit and the drive waveform. The drive waveform is a preset waveform. For example, the drive waveform may be set by measuring in advance how the actuator will operate with a certain drive waveform. Therefore, the drive waveform represents the ideal operation of the actuator, in other words, the amount of displacement. However, the preset drive waveform does not take into account disturbances caused by the operation of the actuator. Therefore, it is necessary to correct the drive waveform by adding the integration result output from the integration control circuit and the drive waveform in the adder circuit.

[0078] The drive circuit amplifies the power of the corrected drive waveform and outputs it to the actuator, thereby driving the actuator. The drive circuit functions as an interface between the control device 910 and the actuator.

[0079] Next, the flow of processing for feedback control of the actuator by the control device 910 will be described with reference to Fig. 9. Fig. 9 is a flowchart showing the flow of processing for feedback control of the actuator by the control device 910 according to the fourth embodiment.

[0080] The integral control circuit of the control device 910 receives the detected value of the actuator position from the position sensor (step St1000).

[0081] The integral control circuit of the control device 910 integrates the error between the detection value received in step St1000 and the median value of the movable range of the actuator, or integrates the difference between the median value of the movable range of the actuator and a value obtained by dividing the integrated value of the detection value received in step St1000 by the number of integrations (step St1001). Note that the length of time for integration by the integral control circuit may be set to a length of time that allows the drive waveform to be sufficiently averaged. For example, if the frequency of the drive waveform is 60 Hz and one cycle is approximately 16.6 ms, the length of time for integration by the integral control circuit may be set to 100 ms or 200 ms.

[0082] The adder circuit of the control device 910 adds the integration result by the integration control circuit in step St1001 to a preset drive waveform for driving the actuator, thereby correcting the drive waveform (step St1002). The corrected drive waveform is output to the drive circuit.

[0083] The drive circuit of the control device 910 outputs the drive waveform corrected by the adder circuit in step St1002 to the actuator (step St1003). At this time, the drive circuit may perform power amplification of the drive waveform as necessary. For convenience of explanation, FIG. 9 shows that the feedback control process ends in step St1003, but the feedback control process may be performed repeatedly. As a result, control is performed so that the center position of the vibration of the actuator is maintained at the center position of the movable range of the actuator.

[0084] Conventionally, when the actuators are arranged symmetrically, a method of performing PID control based on the difference between the position sensor's detected value and the target value allows for highly accurate control of the tilt of the movable frame. However, when the actuators are arranged asymmetrically, this method also applies PID control to disturbances caused by orthogonal actuators (e.g., the second actuator 104 relative to the first actuator 103). Since the actuators are driven based on PID control that cancels out the disturbances, the movement of the movable frame can become unstable. In the feedback control method described with reference to Figures 8 and 9, disturbances from orthogonal directions are canceled by integration, so no feedback is applied to the disturbances. Feedback can be applied to maintain the center position of the actuator's movable range.

[0085] Next, a control method for maintaining the center position of the movable range of the actuator even when an external impact is applied to the optical path changing element 100 will be described with reference to Figures 10 and 11. In the description of Figures 10 and 11, parts that overlap with the description of Figures 8 and 9 may be omitted or simplified. Figure 10 is a schematic diagram for explaining a control method of an optical path changing element according to embodiment 4.

[0086] The control device 910A may be configured, for example, with a microcomputer, a CPU, an MPU, a GPU, a DSP, an FPGA, an ASIC, or the like. The control device 910A includes at least one-period integration control circuit 916A, one-period integration control circuit 916B, a PID control circuit 917A, a PID control circuit 917B, a drive waveform generation circuit 918A, a drive waveform generation circuit 918B, an adder circuit 913A, an adder circuit 913B, a drive circuit 915A, and a drive circuit 915B. Although not shown, the control device 910A may also include circuits capable of generating synchronization signals and values ​​for the center position 912A of the movable range of the first actuator 103 and the center position 912B of the movable range of the second actuator 104. Hereinafter, when describing both the one-period integration control circuit 916A and the one-period integration control circuit 916B, they may be referred to simply as one-period integration control circuits. The same applies to the PID control circuits 917A and 917B, and the drive waveform generating circuits 918A and 918B. The functions of the various circuits included in the control device 910A may be realized as software functions. The configuration of the control device 910A is an example, and the control device 910A may include additional components, or multiple components included in the control device 910A may be integrated into a single component.

[0087] In the control device 910A, the one-period integration control circuit, the PID control circuit, and the drive waveform generation circuit are controlled by a synchronization signal so that they operate at the same timing, which enables, for example, the one-period integration control circuit to integrate over one period of the drive waveform, as will be described later.

[0088] The one-period integration control circuit integrates the actuator position detected by the position sensor in response to the input of a synchronization signal. The drive waveform is a composite of multiple sine waves with different frequencies and no DC component. Therefore, by integrating the drive waveform over one period, fluctuation components caused by the drive waveform and included in the detected value are averaged to zero. As a result, the output of the one-period integration control circuit does not include fluctuation components caused by the drive waveform. Meanwhile, in the description with reference to Figures 10 and 11, disturbances include not only disturbances caused by the actuator operation in the orthogonal direction but also external impacts, etc. Because these elements are not periodic, they are not eliminated by one-period integration. The one-period integration control circuit outputs the detected value of the position sensor, including fluctuations caused by external impacts, etc., without the influence of the drive waveform. The difference between the detected value output from the one-period integration control circuit and the central position value is input to the PID control circuit as an error signal.

[0089] The PID control circuit generates a control waveform for controlling the position of the actuator based on the error signal. Specifically, the PID control circuit outputs a control waveform for controlling the center position of the vibration of the actuator so as to maintain the center position of the actuator's movable range. The PID control circuit generates and outputs the control waveform by PID control.

[0090] The drive waveform generating circuit generates and outputs a drive waveform in response to an input of a synchronization signal.

[0091] The adder circuit adds the drive waveform output from the drive waveform generation circuit and the control waveform output from the PID control circuit, thereby correcting the drive waveform.

[0092] The drive circuit amplifies the power of the corrected drive waveform and outputs it to the actuator, thereby driving the actuator.

[0093] Next, the flow of processing for feedback control of the actuator by the control device 910A will be described with reference to Fig. 11. Fig. 11 is a flowchart showing the flow of processing for feedback control of the actuator by the control device 910A according to the fourth embodiment.

[0094] The one-period integration control circuit of the control device 910A receives the detected value of the actuator position from the position sensor and integrates it over the time of one period of the drive waveform in response to the input of the synchronization signal (step St2000). Because the one-period integration control circuit operates in response to the input of the synchronization signal, the length of the time of integration by the one-period integration control circuit is the length of one period of the drive waveform.

[0095] The control device 910A generates an error signal by calculating the error (difference) between the detection value integrated by the one-period integration control circuit in step St2000 and the median value of the movable range of the actuator (step St2001). The error signal is input to the PID control circuit of the control device 910A.

[0096] The PID control circuit of the control device 910A generates a control waveform for controlling the position of the actuator in response to the input of the error signal (step St2002).

[0097] The drive waveform generating circuit of the control device 910A generates a drive waveform in response to the input of the synchronization signal (step St2003).

[0098] The adder circuit of the control device 910A adds the control waveform generated by the PID control circuit in step St2002 and the drive waveform generated by the drive waveform generation circuit in step St2003, thereby correcting the drive waveform (step St2004). The corrected drive waveform is output to the drive circuit.

[0099] The drive circuit of the control device 910A outputs the drive waveform corrected by the adder circuit in step St2004 to the actuator (step St2005). At this time, the drive circuit may perform power amplification of the drive waveform as necessary. For convenience of explanation, FIG. 11 shows that the feedback control process ends in step St2005, but the feedback control process may be performed repeatedly. This allows control to be performed such that the center position of the vibration of the actuator is maintained at the center position of the actuator's movable range. Furthermore, since integration is performed over the time of one cycle of the drive waveform, the influence of the drive waveform can be eliminated.

[0100] Summary of Fourth Embodiment The above description of the fourth embodiment discloses at least the following techniques.

[0101] <Technology D1> A control method for controlling an optical path changing element integrates the error between the detection value of a position sensor that detects the position of an actuator possessed by the optical path changing element and the median value of the movable range of the actuator, corrects the drive waveform for driving the actuator using the integration result, and drives the actuator based on the corrected drive waveform.

[0102] This makes it possible to suppress the influence of disturbances caused by driving one actuator on other actuators even if the actuators are arranged asymmetrically, and to accurately control the tilt of an optical path changing member such as a lens.

[0103] <Technology D2> A control method for controlling an optical path changing element integrates the detection value of a position sensor that detects the position of an actuator possessed by the optical path changing element over the time of one cycle of a drive waveform for driving the actuator, generates a control waveform for controlling the position of the actuator based on the error between the detection value integrated over the time of one cycle and the median value of the movable range of the actuator, and corrects the drive waveform using the control waveform.

[0104] This makes it possible to suppress the influence of fluctuation components caused by the drive waveform, for example, and to control the tilt of an optical path changing member such as a lens with high precision.

[0105] Although the embodiments have been described above with reference to the accompanying drawings, the present disclosure is not limited to such examples. It is clear that a person skilled in the art can conceive of various modifications, alterations, substitutions, additions, deletions, and equivalents within the scope of the claims, and it is understood that these also fall within the technical scope of the present disclosure. Furthermore, the components in the above-described embodiments may be combined in any manner without departing from the spirit of the invention.

[0106] The technology of the present disclosure is useful for projectors with a wobbling function.

[0107] 100 Optical path changing element 101 Base member 101a Light transmitting member 102 Lens 103 First actuator 104 Second actuator 105 First movable frame 106 Second movable frame 107 First hinge 108 Second hinge 110 Vertex 111 First edge 112 Second edge 121 Yoke 122 Magnet 123 Coil 124 Thermally conductive material 125 Thermally conductive holding frame 126 First fixing member 127 Second fixing member 130 Off-light plate 131 Black painted portion 150 Hole 151 Hole area 153 Boundary line 200 Projector 301 Blue semiconductor laser 302 Collimator lens 303, 307, 308, 317 Condenser lens 304 Diffuser 305, 309, 310, 312, 314, 316, 330, 331, 332 Lens 306 Dichroic mirror 311, 313, 315 Mirror 318 Rod integrator 320 Phosphor wheel 333, 334 Prism 335 Total reflection prism 336 DMD 337 Projection lens unit 400 Protrusion 401 First surface 402 Second surface 410 Unwanted light 412 Reflecting surface 421 First axis 422 Second axis 900A, 900B Position sensor 910, 910A Control device 911A, 911B Integration control circuit 912A, 912B Central position 913A, 913B Adding circuit 914A, 914B Drive waveform 915A, 915B: drive circuit; 916A, 916B: periodic integration control circuit; 917A, 917B: PID control circuit; 918A, 918B: drive waveform generation circuit

Claims

1. An optical path changing element comprising: a base member; a lens; a frame for holding the lens; an actuator provided on a first surface of the base member for oscillating the frame by vibration; and an off-light plate disposed a predetermined distance from a second surface of the base member opposite the first surface and for receiving unwanted light that does not pass through the lens, wherein a hole region having a plurality of holes is formed in a part of the area of ​​the base member that overlaps with the off-light plate in a plan view.

2. An optical path changing element as described in claim 1, further comprising: said frame being a first frame; said actuator being a first actuator; a second frame connected to said first frame by a hinge; and a second actuator provided on said first surface of said base member and vibrating to cause said second frame to oscillate; and said hole region being formed in a partial region of said base member between said first actuator, said second actuator and said lens.

3. An optical path changing element as described in claim 2, wherein the first actuator and the second actuator each have at least a magnet, a coil, and a holding portion for holding the coil, the first actuator is arranged along a first side extending from a predetermined vertex of the base member, and the holding portion of the first actuator is fixed to the base member by at least a first fixing member located on the side closer to the vertex, the second actuator is arranged along a second side extending from the vertex of the base member, and the holding portion of the second actuator is fixed to the base member by at least a second fixing member located on the side closer to the vertex, and the hole region is formed in a partial region of the base member between the position of the first fixing member, the position of the second fixing member, and the lens.

4. The optical path changing element according to claim 3, wherein the thermal conductivity of the first fixing member and the second fixing member is greater than the thermal conductivity of the base member.

5. An optical path changing element comprising: a base member; a lens; a frame for holding the lens; and an actuator attached to the base member and vibrating the frame, wherein the actuator has at least a magnet, a coil, and a holding portion for holding the coil, the coil is positioned between the frame and the holding portion, and the holding portion includes a material having a higher thermal conductivity than the frame.

6. The optical path changing element according to claim 5, wherein the actuator further comprises a heat conductive material between the coil and the holding portion.

7. The optical path changing element according to claim 6, wherein the thermally conductive material includes a material having a higher thermal conductivity than the frame.

8. A projector comprising: an image light modulation element that modulates light from a light source into image light; a projection lens unit that projects the modulated image light; a prism that guides light from the light source to the image light modulation element; and an optical path changing element that is located between the image light modulation element and the projection lens unit in the projection direction of the image light and changes the optical path of the image light, wherein at least a part of the prism is located between the optical path changing element and the projection lens unit in the projection direction of the image light.

9. The projector according to claim 8, wherein the prism has a reflective surface that reflects light from the light source, and at least a portion of the reflective surface of the prism is located between the optical path changing element and the projection lens unit in the projection direction of the image light.

10. A projector as described in claim 9, wherein the optical path changing element comprises: a lens; a frame that holds the lens; an actuator that vibrates one end of the frame in the projection direction; and a hinge that is arranged on a rotation axis that rotates the frame about its axis due to the vibration of the actuator and is connected to the frame, and the reflective surface of the prism is located closer to the hinge than the actuator.

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