JP2015105988A - Actuation device, lens unit and imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an actuation device, a lens unit and an imaging device that enable suppression of an amount of change of a relative position between a detection member of a position detection sensor and a detected member, and enable suppression of reduction in position detection accuracy of the position detection sensor.SOLUTION: An actuation device 10 according to the present invention comprises: an actuator 3 that includes an actuation shaft 32; a moving member 4 that frictionally engages with the actuation shaft 32 movably in a shaft direction of the actuation shaft 32; a substantially rectangle-shape holding member 2 that holds the actuator 3; and a position detection sensor 53 that includes a hall element 53b detecting a position of the moving member 4 in the shaft direction with respect to the holding member 2 and a magnet 53a. The actuator 3 is configured to be arranged at a first corner part 2a of the holding member 2, and the hall element 53b is configured to be provided between the first corner part 2a in the holding member 2 and a fourth corner part 2d therein.

Description

  The present invention relates to a driving device, a lens knit, and an imaging device that can be mounted on a mobile phone or the like.

In recent years, with the spread of smartphones and tablet terminals, the demand for advanced camera functions is increasing. Among them, interest in autofocus is high, and there is a great demand for quickly focusing on an imaging target. Therefore, in many cases, a position detection sensor that detects the position of the moving member that holds the lens is mounted on the lens driving device in order to increase the speed to autofocus.

  For example, Patent Document 1 discloses an imaging unit having a lens driving device on which a position detection sensor is mounted. The lens driving device of the imaging unit disclosed in Patent Document 1 includes a piezoelectric element (electromechanical conversion element), an actuator having a driving shaft that is bonded to the piezoelectric element and transmits mechanical energy, and an axial direction of the driving shaft. A moving member that is frictionally engaged with the outer periphery of the drive shaft by a biasing force of a spring, and a substantially rectangular holding member that holds the actuator and has four corners when viewed from the axial direction of the drive shaft. And a position detection sensor for detecting the position of the moving member in the axial direction with respect to the holding member. And an actuator is arrange | positioned in the 1st corner part in a holding member. The position detection sensor includes a hall element as a detection member and a magnet as a member to be detected detected by the hall element, and the hall element is arranged at a corner portion adjacent to the first corner portion of the holding member. The magnet is disposed on the moving member so as to face the Hall element. When the moving member moves in the axial direction of the drive shaft, the Hall element detects the relative position to the magnet, thereby detecting the position of the moving member relative to the holding member.

JP 2009-25376 A

  By the way, there is a possibility that the moving member frictionally engaged with the outer periphery of the drive shaft by the biasing force of the spring rotates around the drive shaft. However, in Patent Document 1, since the Hall element is disposed in the corner portion adjacent to the first corner portion of the holding member, the distance from the drive shaft to the Hall element and the magnet becomes considerably long. Therefore, when the moving member rotates about the axis of the drive shaft, the amount of fluctuation in the relative position between the Hall element and the magnet increases. If the relative position fluctuation amount increases in this way, the position detection accuracy decreases.

  The present invention provides a driving device, a lens unit, and an imaging device that can suppress the amount of fluctuation in the relative position between the detection member of the position detection sensor and the detected member, and that can suppress a decrease in position detection accuracy of the position detection sensor. Objective.

  The drive device of the present invention includes an actuator having an electromechanical conversion element that converts electrical energy into mechanical energy, a drive shaft that is joined to the electromechanical conversion element and transmits the mechanical energy, and an axial direction of the drive shaft A movable member frictionally engaged with the drive shaft, a substantially rectangular holding member holding the actuator and having four corners when viewed from the axial direction of the drive shaft, and the holding member with respect to the holding member A position detection sensor that detects a position of the moving member in the axial direction, and the actuator is provided at a first corner portion that is one of the four corner portions of the holding member. The position detection sensor includes a detection member and a detected member that is detected by the detection member, and one of the detected member and the detection member is the holding portion. Either the first member at the first corner portion or between the first corner portion adjacent to the first corner portion and the first corner portion, and the detected member or the detecting member. The other is characterized in that it is disposed on the moving member so as to face the member to be detected.

  According to this configuration, any one of the detection member and the detection member is located at the first corner portion of the holding member or between the corner portion adjacent to the first corner portion and the first corner portion. Since the other member is disposed on the moving member so as to face the member to be detected, the distance from the drive shaft to the member to be detected and the member to be detected is shorter than the conventional one. As a result, even when the moving member rotates around the axis of the drive shaft, the amount of fluctuation in the relative position between the detected member and the detecting member is suppressed to be smaller than the conventional one, and the position between the detected member and the detecting member is reduced. A decrease in detection accuracy can be suppressed.

  In another aspect, the detection member is a Hall element, and the detected member is a magnet.

  According to this configuration, the position detection sensor can be downsized and the cost can be reduced.

  In another aspect, the holding member includes a rotation restricting stopper for restricting the rotation of the moving member around the axis of the drive shaft by stopping the moving member, and the rotation restricting portion. The application stopper is disposed at a corner that is diagonal to the first corner.

  According to this configuration, the corner portion that is diagonal to the first corner portion of the holding member is the position where the distance from the first corner portion where the drive shaft is disposed is the largest, and the corner portion has Since the rotation restricting stopper is disposed, if the rotation of the moving member around the axis of the drive shaft is restricted at this position, the amount of rotation of the moving member around the axis of the drive shaft (angle range of rotation) ) Can be minimized. Therefore, the fluctuation amount of the relative position between the detected member and the detection member accompanying the rotation of the moving member around the axis of the drive shaft can be minimized, and the decrease in position detection accuracy can be suppressed more efficiently. be able to.

  The lens unit of the present invention includes any one of the driving devices described above and one or a plurality of optical elements, and includes an imaging optical system that forms an optical image of an object on a predetermined surface. The optical element that moves along the optical axis direction among the one or more optical elements is attached to a moving member of the driving device.

  According to this configuration, even if the distance from the driving shaft to the detected member and the detecting member is shorter than the conventional one, and the moving member rotates around the axis of the driving shaft, the relative position between the detected member and the detecting member. Therefore, the lens unit can suppress a decrease in position detection accuracy due to the detected member and the detection member.

  An image pickup apparatus according to the present invention includes the lens unit, and an image pickup device in which a light receiving surface is arranged at a position of the predetermined surface and converts an optical image of the object into an electrical signal. To do.

  According to this configuration, even if the distance from the driving shaft to the detected member and the detecting member is shorter than the conventional one, and the moving member rotates around the axis of the driving shaft, the relative position between the detected member and the detecting member. Therefore, the image pickup apparatus can reduce the position detection accuracy due to the detected member and the detection member.

  The drive device, the lens unit, and the imaging device according to the present invention can suppress the fluctuation amount of the relative position between the detection member and the detection member, and can suppress a decrease in position detection accuracy of the position detection sensor.

It is a disassembled perspective view of the drive device of one Embodiment of this invention. FIG. 2 is a perspective view of a state in which a cover of the driving device of FIG. 1 is removed. It is the top view which made a part of drive device of Drawing 1 into a section. It is a principal part enlarged plan view of FIG. 1A is a perspective view of a state in which a moving member used in the drive device of FIG. 1 is engaged with an actuator, and FIG. 5B is an angle different from FIG. 5A in a state in which the moving member is engaged with an actuator. FIG. It is a perspective view of the moving member main-body part used for the drive device of FIG. (A) is a perspective view of the engaging member used for a drive device, (b) is a perspective view from the angle different from FIG. 7 (a) of an engaging member, (c) is a front view of an engaging member. It is. It is a perspective view of the actuator used for the drive device of FIG. It is sectional drawing which abbreviate | omitted the cover of the imaging device.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. 1 is an exploded perspective view of a drive device according to an embodiment of the present invention, FIG. 2 is a perspective view of the drive device of FIG. 1 with a cover removed, and FIG. 3 is a part of the drive device of FIG. FIG. 1, 2, and 5 to 9, the XY direction is the vertical direction (optical axis direction), the X direction is the upper side (object side), and the Y direction is the lower side (image side). To do.

  The drive apparatus 10 of this embodiment is provided with the apparatus main body 1, the actuator 3 hold | maintained at the apparatus main body 1, the moving member 4, and the position detection sensor 53, as shown in FIGS.

  The apparatus main body 1 includes a holding member 2 and a cover 9. The holding member 2 is made of a resin material such as LCP (liquid crystal polymer) and is formed by injection molding or the like. The holding member 2 of the present embodiment has a rectangular shape having four corners of the first corner portion 2a to the fourth corner portion 2d in a plan view seen from the optical axis direction, and has an optical path at the center portion. It consists of a plate-like body having a circular through hole 21.

  The holding member 2 includes a first support column 20a and an actuator holding portion 22 holding the actuator 3 at the first corner 2a. The first support pillar 20 a protrudes upward from the upper surface of the holding member 2.

  As shown in FIG. 9, the actuator holding portion 22 is formed in a circular shape with a predetermined depth from the upper surface of the holding member 2.

  Further, the holding member 2 has a second support column 20b at a second corner 2b disposed on the right side of FIG. 1 adjacent to the first corner 2a (counterclockwise side of the first corner 2a). The third support column 20c is adjacent to the first corner 2a at the third corner 2c arranged diagonally with the first corner 2a (the first corner 2a). The fourth support pillars 20d are arranged so as to protrude upward from the upper surface of the holding member 2 at the fourth corner 2d arranged on the clockwise side).

  Further, the third support pillar 20c is formed with a restricting portion receiving groove (turning restricting stop portion) 29 for receiving a turn restricting stop portion 52 of the moving member 4 described later so as to be movable in the vertical direction. Has been. Then, when the moving member 4 rotates around the axis of the drive shaft 32 on both inner side surfaces of the restricting portion receiving groove 29, the rotation restricting supported stop portion 52 of the moving member 4 is stopped and rotated. A rotation restricting stopper 29a for restricting movement is provided.

  The corner portion is a region that is substantially partitioned and formed by the end portions of two adjacent sides of the holding member 2 that intersect and the through hole 21.

  The cover 9 is formed by drawing and pressing a stainless steel thin plate of 0.1 mm to 0.2 mm, and includes a through hole 91 serving as an optical path in the upper wall 90.

  The cover 9 is locked to the holding member 2 in a state where the inner surface of the upper wall 90 of the cover 9 is placed on the upper surfaces of the first support column 20a to the fourth support column 20d of the holding member 2. At the same time, they are bonded and bonded by an adhesive. Further, when the cover 9 is coupled, the cover 9 and the holding member 2 define a storage portion 20 for storing the moving member 4 therein.

  As shown in FIG. 8, the actuator 3 includes a piezoelectric element 31 that is an electromechanical conversion element that expands and contracts in the axial direction, a drive shaft 32 that is joined to one end of the piezoelectric element 31, and a joint that is joined to the other end of the piezoelectric element 31. A weight 33 is provided.

  The weight 33 is for generating a displacement due to expansion / contraction of the piezoelectric element 31 only on the drive shaft 32 side. In this embodiment, the weight 33 is made of a material having a high specific gravity such as tungsten or a tungsten alloy.

  Further, the weight 33 is formed of a columnar shape whose outer diameter protrudes from the outer periphery of the piezoelectric element 31 over the entire periphery in the outer peripheral direction.

  The piezoelectric element 31 is an element that converts input electric energy into mechanical energy that expands and contracts, that is, mechanical motion. For example, a piezoelectric element that converts input electric energy into mechanical elastic motion by a piezoelectric effect, or the like It is. Such a piezoelectric element includes, for example, a laminated body and a pair of external electrodes.

  The laminated body is formed by alternately laminating a plurality of thin film (layered) piezoelectric layers made of a piezoelectric material and a conductive thin film (layered) internal electrode layer. In the present embodiment, the laminate has a quadrangular prism shape, but is not limited to this, and may be, for example, a polygonal column shape or a cylindrical shape.

  Each of the plurality of internal electrode layers is configured to face the outside with a pair of outer peripheral side surfaces facing each other. The plurality of internal electrodes are sequentially connected alternately.

Examples of the piezoelectric material include lead zirconate titanate (so-called PZT), crystal, lithium niobate (LiNbO ₃ ), potassium tantalate niobate (K (Ta, Nb) O ₃ ), barium titanate (BaTiO ₃ ), Inorganic piezoelectric materials such as lithium tantalate (LiTaO ₃ ) and strontium titanate (SrTiO ₃ ).

  The piezoelectric element 31 includes a first external electrode (electrode part) 31a and a second external electrode (electrode part) 31b that connect the internal electrodes between the layers in parallel and supply the electric energy to the laminated body. It is formed by sputtering silver or the like on the side surfaces of the pair.

  The lower end surface of the piezoelectric element 31 is bonded to the upper end surface of the weight 33 with an adhesive such as an epoxy adhesive.

  The drive shaft 32 is formed into a cylindrical shape with resin so that carbon fibers are arranged in the axial direction. The drive shaft 32 of this embodiment is formed so that the outer diameter protrudes from the outer periphery of the piezoelectric element 31 to the outer periphery over the entire periphery.

  The lower end surface of the drive shaft 32 is bonded to the upper end surface (one end) of the piezoelectric element 31 with an adhesive. As this adhesive, the same adhesive as the adhesive that bonds the piezoelectric element 31 and the weight 33 can be used.

  In this embodiment, although not shown, the adhesive is an adhesive (fillet) that protrudes from the joint surface between the drive shaft 32 and the piezoelectric element 31 and is formed on the piezoelectric element side. The entire region can be used for sliding with the moving member 4, and a large stroke can be realized with the short drive shaft 32.

  Then, the actuator 3 is inserted into the actuator holding portion 22 of the holding member 2 from the weight 33 side as shown in FIG. 9 by an adhesive (not shown) and the bottom surface, inner peripheral wall and weight of the actuator holding portion 22. 33 is bonded and fixed. Thus, in this embodiment, the lower end surface (the other end) of the piezoelectric element 31 is indirectly attached to the holding member 2 via the weight 33.

  The weight 33 is omitted if the lower end surface of the piezoelectric element 31 can be directly attached to and held by the holding member 2 and can perform the same function as the weight 33. Also good.

  In this state, the axial direction of the drive shaft 32 and the axial direction (thickness direction) of the holding member 2 are in a parallel state.

  Next, the moving member 4 will be described. The moving member 4 slides along the axial direction of the drive shaft 32. As shown in FIGS. 1 to 4, the moving member 4 of this embodiment has a substantially cylindrical moving member body 5 made of a resin material such as LCP (liquid crystal polymer) and a drive shaft 32 with a predetermined frictional force. The engaging member 6 is engaged.

  The moving member main body 5 includes a lens holding portion 54 having a female screw (not shown) on the inner peripheral side. The lens holding portion 54 includes one or a plurality of lens groups 171 (FIG. 9) as moving members. Is shown in FIG. 9 through a lens barrel 107 (shown in FIG. 9).

  The moving member main body 5 includes an engaging member holding portion 51 that holds the engaging member 6 on the outer periphery, and a rotation restricting stopper for restricting the rotation of the moving member 4 with respect to the drive shaft 32. 52.

  The engaging member holding part 51 is formed over a substantially half circumference of the outer periphery of the moving member main body part 5. Further, the engaging member holding portion 51 has a driving bearing portion holding portion 51b for holding a driving bearing portion 71 of the engaging member 6 to be described later on one end side, and the moving member main body portion 5 on the other end side. Protrusions 51a for increasing the adhesive strength with the combined member 6 are provided.

  As shown in FIG. 6, the rotation restricting stopper 52 is located at a position approximately 180 ° away from the drive bearing holder 51 b in the moving member main body 5 in the circumferential direction, that is, the driving in the moving member main body 5. It is formed at a position farthest from the bearing holder 51b.

  The rotation restricting stopper 52 of this embodiment includes a restricting main body 52a and a hemispherical protrusion 52b formed on the restricting main body 52a.

  The restriction main body 52 a is projected in a quadrangular prism shape from the outer periphery of the engaging member holding portion 51 to the radially outer side.

  The protrusion 52b protrudes outward from both outer side surfaces of the restriction main body 52a. The outer width of the protrusions 52b is set to be slightly narrower than the inner width of the restricting portion receiving groove 29 of the holding member 2, that is, the distance between the rotation restricting stoppers 29a.

  As shown in FIG. 7, the engaging member 6 includes an engaging member main body 7 having metal elasticity and a band-shaped elastic body 8 having metal elasticity. In this embodiment, the engagement member main body 7 is formed of a band shape, and includes a drive bearing portion 71 on one end side in the longitudinal direction.

  The drive shaft receiving portion 71 includes a first receiving portion 71a and a second receiving portion 71b that is bent at a substantially right angle from the first receiving portion 71a, and receives the drive shaft 32 in a slidable manner. The first receiving portion 71a has a vertical length L11 that is the same as the width of the second receiving portion 71b.

  The engaging member main body 7 includes a fitting insertion hole 72 into which the protrusion 51a of the engaging member holding portion 51 is fitted and inserted on the other end side in the longitudinal direction.

  The elastic body 8 includes a pressing portion 81 that presses the drive shaft 32 against the drive bearing portion 71 on one end side in the longitudinal direction. In this embodiment, the pressing portion 81 is formed such that the width L12 in the vertical direction is smaller than the width L11 of the first receiving portion 71a.

  The elastic body 8 includes a connecting portion 82 fixedly connected to the engaging member main body 7 on the other end side in the longitudinal direction. In this embodiment, the connecting portion 82 is fixedly connected to the engaging member body 7 at two locations 82a and 82b separated by a predetermined distance in the longitudinal direction by spot welding, whereby the elastic body 8 is engaged. The member main body 7 is prevented from rotating around the spot welded portion.

  In addition, the connection means of the connection part 82 is not restricted to spot welding, but may be, for example, another welding method or welding method, and can be changed as appropriate. Moreover, when performing by spot welding, you may make it carry out in one place or three or more places.

  The elastic body 8 includes an arm portion 83 formed of a belt-like elastic piece that applies an elastic force to the pressing portion 81 at an intermediate portion in the longitudinal direction, which is a portion between the pressing portion 81 and the connecting portion 82. . In this embodiment, the arm portion 83 is provided with a bent portion 83a on the side of the connecting portion 82, and is formed in a “heavy” shape in plan view.

  The arm 83 has a length that can be extended from at least the first corner 2a to the second corner 2b. In this embodiment, the arm 83 has a length that extends from the first corner 2a to the second corner 2b.

  The arm portion 83 is not limited to the one provided with the bent portion 83a, and may be, for example, a linear shape in a plan view, or a part or the whole of a curved shape (arc shape) in a plan view, It can be changed as appropriate.

  The elastic body 8 is disposed on one surface side in the thickness direction of the engagement member main body 7 so that the longitudinal directions thereof coincide with each other. In this state, the connecting portion 82 is engaged with the engagement member as described above. It is connected to the main body 7 by spot welding. In this state, the pressing portion 81 and the drive bearing portion 71 face each other, and a drive shaft receiving portion 74 that receives the drive shaft 32 is formed therebetween.

  In this state, as shown in FIG. 7C, the engaging member 6 composed of the elastic body 8 and the engaging member main body 7 is orthogonal to the axial direction of the drive shaft 32 received by the drive shaft receiving portion 74. The upper and lower sides of the center line 70 are symmetrical to each other with respect to the center line 70.

  The engaging member 6 configured in this manner has the protrusion 51a inserted into the insertion hole 72 so that the other surface side of the engaging member main body 7 in the thickness direction faces the moving member main body 5. In this state, the engaging member main body 7 and the moving member main body 5 are bonded together with an adhesive interposed therebetween.

  Then, the drive shaft 32 is received by the drive shaft receiving portion 74 of the engaging member 6 connected to the moving member main body portion 5. In this state, the engaging member 6 is frictionally engaged with the drive shaft 32 so as to be axially slidable.

  The position detection sensor 53 detects the position in the axial direction (optical axis direction) of the drive shaft 32 of the moving member 4 with respect to the apparatus main body 1, and the position detection sensor 53 of this embodiment is a Hall element (detection member) 53b. And a magnet (detected member) 53a detected by the Hall element 53b.

  In this embodiment, the Hall element 53b has a distance L between the first corner portion 2a and the fourth corner portion 2d, and the first corner between the first corner portion 2a and the fourth corner portion 2d. It is disposed at a position of approximately 1 / 4L from the corner 2a.

  More specifically, the holding member 2 protrudes upward from the upper surface of the holding member 2 from the first corner portion 2a to the substantially central portion between the first corner portion 2a and the fourth corner portion 2d. A detection member holding wall 23 is provided. The Hall element 53b is held by the detection member holding wall 23, so that the Hall element 53b is approximately ¼ L from the first corner 2a between the first corner 2a and the fourth corner 2d. Arranged in position.

  The magnet 53a is attached in the vicinity of the drive bearing holding portion 51b on the outer periphery of the moving member main body 5, and the engaging member 6 of the moving member 4 is frictionally engaged with the drive shaft 32 in FIG. As shown in FIG. 4, it faces the Hall element 53b with a predetermined distance L1. In this embodiment, the magnet 53a and the hall element 53b are indirectly opposed to each other with the detection member holding wall 23 interposed therebetween.

  In the driving device 10 configured as described above, for example, as shown in FIG. 9, the lens barrel 107 is held by the lens holding portion 54 of the moving member 4 to form a lens unit. Further, the image pickup apparatus 100 is formed by attaching a sensor substrate 104 having an IR cut filter 102 and an image pickup element 103 to the lower surface side of the holding member 2 in the lens unit.

  The image sensor 103 is an image of each component of R (red), G (green), and B (blue) according to the amount of light in an optical image of an object (subject) imaged by an imaging optical system (not shown) as a whole. It is an element that photoelectrically converts a signal and outputs it to a predetermined image processing circuit (not shown). The image sensor 103 is, for example, a CCD image sensor, a CMOS image sensor, or the like.

  The imaging optical system includes one or a plurality of lens groups (optical elements) 171 and forms an optical image of an object on the light receiving surface of the imaging element 103. The lens group 171 is an optical element that moves along the optical axis of the one or more optical elements in such an imaging optical system. The lens group 171 may be a single lens or may include a plurality of lenses. The lens group 171 may be, for example, a lens that moves along the optical axis to perform focusing (focusing), or a lens that moves along the optical axis to perform zooming (magnification), for example. It may be. An optical image of the object is guided along the optical axis by the imaging optical system including the lens group 171 to the light receiving surface of the imaging element 103, and the optical image of the object is captured by the imaging element 103. The

  The imaging device 100 is installed in the casing of the mobile phone so as to be connected to a circuit board of the mobile phone, for example.

  When electric power is supplied to the piezoelectric element 31 from a drive circuit provided in the mobile phone, the piezoelectric element 31 vibrates in the axial direction, and the drive shaft 32 reciprocates due to the vibration (expansion / contraction). The moving member 4 moves in the axial direction (optical axis direction) of the drive shaft 32.

  More specifically, when the rectangular wave having a predetermined duty ratio is applied to the piezoelectric element 31, the displacement of the drive shaft 32 becomes a triangular wave. By changing the duty ratio of the rectangular wave, the amplitude is increased and decreased. Triangular waves with different slopes are generated. The drive mechanism of the actuator 3 utilizes this.

  For example, when the drive shaft 32 is slowly extended, the moving member 4 that is frictionally engaged with the drive shaft 32 is also moved in accordance with the extension, and the drive is instantaneously performed to exceed the frictionally engaged friction force. When the shaft 32 is contracted, the moving member 4 is left as it is. The moving member 4 moves in the axial direction of the drive shaft 32 by repeatedly extending and contracting the drive shaft 32 in the axial direction.

  Further, when the moving member 4 tries to rotate around the axis of the drive shaft 32, any one of the protrusions 52 b of the rotation restricting stopper 52 has the rotation restricting stop of the restricting portion receiving groove 29. The rotation is restricted by being stopped by 29a. At this time, since the rotation restricting stopper 29a is formed at the third corner 2c having the longest distance L3 from the first corner 2a holding the drive shaft 32, the shaft of the drive shaft 32 is formed. The amount of rotation of the moving member 4 around the center can be minimized.

  Further, when the moving member 4 moves in the axial direction of the drive shaft 32, the Hall element 53 b provided in the holding member 2 detects the magnet 53 a provided in the moving member 4, and the moving member 4 with respect to the apparatus main body 1. The position in the optical axis direction is detected.

  At this time, the amount of change in the relative position between the Hall element 53b and the magnet 53a increases in proportion to the amount by which the moving member 4 rotates about the axis O of the drive shaft 32. For example, when the amount (angle) by which the moving member 4 is rotated clockwise around the axis O of the drive shaft 32 from the position shown in FIG. 3 is increased, the Hall element is proportionally shown in FIG. 3 and FIG. When the relative distance L1 between 53b and the magnet 53a increases, and the amount (angle) by which the moving member 4 rotates counterclockwise from the position shown in FIG. 3 increases, the relative distance L1 decreases proportionally. Become. Therefore, the amount of variation increases as the amount of movement of the moving member 4 about the axis O of the drive shaft 32 increases. Further, the amount of fluctuation increases in proportion to the distance from the axis O of the drive shaft 32.

  However, in this embodiment, the hall element 53b and the magnet 53a are disposed closer to the first corner 2a than the center between the first corner 2a and the fourth corner 2d, thereby causing the hall The distance (pitch distance) L2 from the axis O of the drive shaft 32 of the Hall element 53b and the magnet 53a is shorter than in the conventional product in which the elements are arranged at the fourth corner. Therefore, the amount of fluctuation is smaller than that of the conventional product, and the detection accuracy by the Hall element 53b and the magnet 53a is higher than that of the conventional product.

  Moreover, in this embodiment, as described above, the rotation restricting stopper 29a is formed at the third corner 2c where the distance from the first corner 2a holding the drive shaft 32 is the longest. As a result, the amount of rotation of the moving member 4 around the axis of the drive shaft 32 is kept to a minimum, so that the fluctuation amount is kept small, and the detection accuracy by the Hall element 53b and the magnet 53a is further increased. .

  Further, when the moving member 4 slides on the drive shaft 32 from the state in which the protrusion 52bc is in contact with the inner wall of the restricting portion receiving groove 29, the protrusion 52b is formed in a hemispherical shape and is pointed on the inner wall of the restricting portion receiving groove 29. Because of the contact, the moving member 4 can slide the drive shaft 32 with almost no resistance due to the contact.

  In the above embodiment, the hall element (detection member) 53b is disposed on the holding member, and the magnet (detected member) 53a is disposed on the moving member 4. it can. For example, the hall element 53b may be disposed on the moving member 4 and the magnet 53a may be disposed on the holding member.

  In the above embodiment, the Hall element 53b is approximately ¼ L (L is the first corner portion 2a) from the first corner portion 2a between the first corner portion 2a and the fourth corner portion 2d. However, the present invention is not limited to this configuration and can be changed as appropriate.

  For example, the Hall element 53b is disposed in the first corner 2a that is in the vicinity of the drive shaft 32, or the second corner 4b or the fourth corner 2d adjacent to the first corner 2a and the first corner 2a. You may arrange | position between 1 corner part 2a, and can change suitably.

  When the Hall element 53b is disposed between the second corner portion 2b or the fourth corner portion 2d and the first corner portion 2a, the second corner portion 2b or the fourth corner portion 2d It is preferable to be disposed at the center position between the first corner portion 2a or at the position between the center position and the first corner portion 2a. More preferably, the arrangement position of the Hall element 53b is a position between the first corner portion 2a and a position of approximately 1 / 4L.

  Moreover, in the said embodiment, although the Hall element and the magnet were used as a position detection sensor, it can change suitably not only in the thing of this form. For example, a position detection sensor that uses a magnetoresistive effect using a magnetoresistive element and a magnet, or a position detection sensor that measures the intensity of reflected light from an object using a photoreflector (PR) element, etc. There may be.

DESCRIPTION OF SYMBOLS 1 Apparatus main body 2 Holding member 3 Actuator 4 Moving member 5 Moving member main body 6 Engaging member 53 Position detection sensor 53a Magnet (member to be detected)
53b Hall element (detection member)
DESCRIPTION OF SYMBOLS 10 Drive apparatus 100 Imaging device

Claims (5)

An actuator having an electromechanical transducer that converts electrical energy into mechanical energy, and a drive shaft that is joined to the electromechanical transducer and to which the mechanical energy is transmitted;
A moving member frictionally engaged with the drive shaft so as to be movable in the axial direction of the drive shaft;
A substantially rectangular holding member that holds the actuator and has four corners when viewed from the axial direction of the drive shaft;
A position detection sensor that detects a position of the moving member in the axial direction with respect to the holding member;
The actuator is disposed at a first corner that is one of the four corners of the holding member,
The position detection sensor includes a detection member and a detected member detected by the detection member,
One of the detected member and the detection member is the first corner portion of the holding member or between the corner portion adjacent to the first corner portion and the first corner portion. Arranged in
One of the detection member and the detection member is disposed on the moving member so as to face the detection member. The detection member is a Hall element;
The drive device according to claim 1, wherein the detected member is a magnet. The holding member includes a rotation restricting stopper for restricting the rotation of the moving member around the axis of the drive shaft by stopping the moving member.
3. The driving device according to claim 1, wherein the rotation restricting stopper is disposed at a corner that is diagonally positioned with respect to the first corner. The drive device according to any one of claims 1 to 3,
An imaging optical system that includes one or a plurality of optical elements and forms an optical image of an object on a predetermined surface;
An optical element that moves in the optical axis direction among one or a plurality of optical elements in the imaging optical system is attached to a moving member of the driving device. A lens unit according to claim 4;
An image pickup apparatus comprising: a light receiving surface disposed at a position of the predetermined surface; and an image pickup device that converts an optical image of the object into an electrical signal.

Images