JP2013062997A - Drive mechanism and lens unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drive mechanism and a lens unit which reduce variations in a spring force amount of an elastic member which engages with a driving shaft of an actuator.SOLUTION: A drive mechanism includes: an actuator 4 and an engagement member. The engagement member includes an elastic member 6 and a cylindrical body 7 holding a driven member. The elastic member 6 includes: a cylindrical body holding part holding the cylindrical body 7 and having elasticity; a first holding part 61 disposed at a first end of the cylindrical body holding part; and a second holding part 62 disposed at a second end of the cylindrical body holding part. The cylindrical body holding part is disposed so as to wind around an outer peripheral of the cylindrical body 7 and holds the outer peripheral of the cylindrical body 7 with an elastic force of the cylindrical body holding part.

Description

  The present invention relates to a driving mechanism and a lens unit having an engaging member that engages with a driving shaft of an actuator (ultrasonic linear actuator) made of SIDM (Smooth Impact Drive Mechanism (registered trademark)) with a predetermined frictional force.

  In a small lens unit used for an imaging device of a mobile phone, an actuator is used as a drive mechanism. This actuator transmits expansion and contraction of a piezoelectric element, which is an electromechanical conversion element, to a drive shaft, and a driven member having a lens engaged with the drive shaft with a predetermined frictional force is applied when the piezoelectric element is expanded and contracted. It is driven using the speed difference. More specifically, in such an actuator, for example, by slowly extending the drive shaft, the driven member that is frictionally engaged with the drive shaft is also driven and moved, while the predetermined frictional force is exceeded. When the drive shaft is instantaneously reduced, the driven member is left in the extended position. By repeatedly performing such extension and contraction of the drive shaft, the actuator can drive the driven member having the lens in the axial direction of the drive shaft.

  Conventionally, as such a drive mechanism, a shaft contact member that makes contact with the drive shaft, a fixing member that fixes the shaft contact member, and a drive shaft that biases the drive shaft from the side opposite to the shaft contact member What is provided with the elastic member which performs is known. However, this conventional drive mechanism has a problem that the number of parts is large and time is required for assembly.

  On the other hand, there is one proposed in Patent Document 1, for example, in which the number of parts of the drive mechanism is reduced. This is provided with a holding portion for holding a connecting member connected to a lens holding frame at a first end of a long plate-like elastic member, and a holding portion for holding a drive shaft with the holding portion at a second end. It is equipped with.

JP 2007-49878 A

  However, in the thing of the said patent document 1, the spring length of the elastic member which makes elastic force act on a clamping part cannot be taken sufficiently, but has become short, and the sensitivity of the amount of spring force has become high. For this reason, there is a problem that variation in the amount of spring force increases due to a dimensional error of the elastic member, and it is difficult to stabilize the driving performance.

  An object of the present invention is to provide a drive mechanism and a lens unit that can reduce variations in the amount of spring force of an elastic member engaged with a drive shaft of an actuator.

  In order to solve the above-described problem, the present invention includes an actuator having a drive shaft connected to a first end of an electromechanical transducer, and an engagement member engaged with the drive shaft with a predetermined frictional force, A driving mechanism for driving a driven member held by the engaging member by driving the engaging member by a drive shaft, wherein the engaging member is an elastic member and a cylinder holding the driven member And the elastic member includes an elastic cylinder holding portion that holds the cylindrical body, a first clamping portion that is disposed at a first end of the cylindrical body holding portion, and the cylindrical body holding portion. A second holding portion disposed at a second end of the cylindrical body, and the cylindrical body holding portion is disposed so as to wind around an outer periphery of the cylindrical body, and the cylindrical body is supported by an elastic force of the cylindrical body holding portion. The outer periphery of the body is held, and the first holding portion and the second holding portion are configured such that the held cylindrical body is elastic. The drive shaft is slidable in the axial direction of the drive shaft and immovable in the radial direction by the elastic force of the cylindrical body holding portion so that it can move only in the axial direction of the drive shaft together with the material. A drive mechanism is provided.

  According to this, the drive shaft can be clamped between the first clamping part and the second clamping part by the elastic force of the cylinder holding part arranged so as to wind the outer periphery of the cylinder. Thereby, the length of the cylindrical body holding portion that applies an elastic force to the first clamping portion and the second clamping portion can be sufficiently increased, and the spring constant can be reduced. Therefore, even if a dimensional error of the elastic member occurs, the sensitivity of the spring force amount can be kept low, and variations in driving by the drive shaft of the actuator can be suppressed.

  In addition, since the first holding portion and the second holding portion disposed at both ends of one elastic member are held slidable in the axial direction of the drive shaft and immovable in the radial direction, the held cylindrical body is elastic. It can move only in the axial direction of the drive shaft together with the member, and a guide shaft or the like for guiding the cylinder can be made unnecessary. Therefore, the number of parts can be reduced and the assemblability can be improved.

  In another aspect, in the drive mechanism, the cylinder includes a movement restricting portion that restricts the cylinder holding portion from moving in the axial direction of the cylinder with respect to the cylinder. Features.

  According to this, it is possible to reduce the possibility that the cylindrical body holding portion and the cylindrical body slide with each other, and the driven member can be accurately driven.

  In another aspect, in the drive mechanism, the cylindrical body holding portion is ring-shaped.

  According to this, when the drive shaft is clamped between the first clamping unit and the second clamping unit, the elastic force of the entire cylindrical body holding unit can be applied reliably, and the spring constant can be further reliably reduced. it can.

  According to another aspect of the present invention, there is provided a lens unit comprising any one of the drive mechanisms described above and the driven member, wherein the driven member includes a lens.

  According to this, the length of the cylindrical body holding portion that applies an elastic force to the first holding portion and the second holding portion can be sufficiently increased, and the spring constant can be reduced. Therefore, even if a dimensional error of the elastic member occurs, the sensitivity of the spring force amount can be kept low, and variations in driving by the drive shaft of the actuator can be suppressed. Further, since the drive shaft can be clamped between the first clamping part and the second clamping part arranged at both ends of one elastic member, the number of parts can be reduced and the assemblability can be improved.

  The present invention can provide a drive mechanism and a lens unit that can reduce variations in the amount of spring force of an elastic member.

It is a perspective view of an imaging device as a lens unit which has a drive mechanism of one embodiment of the present invention. It is a disassembled perspective view of the imaging device of FIG. It is a front view of the imaging device of FIG. It is the IV-IV sectional view taken on the line of FIG. (A) is the perspective view of the state which looked at the elastic member from right front, (b) is the perspective view of the state which looked at the elastic member from left front, (c) is a front view of an elastic member. (A) is a perspective view of a cylinder, (b) is a front view of Fig.6 (a). It is a perspective view of the engaging member in the state engaged with the actuator. (A) is a front view of an engaging member in a state engaged with an actuator, (b) is a plan view of FIG. 7 (a), (c) is a bottom view of FIG. 7 (a), and (d). Fig. 7A is a right side view of Fig. 7A, and Fig. 7E is a left side view of Fig. 7A. It is a disassembled perspective view of the engaging member engaged with the actuator and the holding frame holding the lens.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. 1 is a perspective view of an imaging device as a lens unit having a drive mechanism according to an embodiment of the present invention, FIG. 2 is an exploded perspective view of the imaging device of FIG. 1, and FIG. 3 is an imaging device of FIG. FIG. 4 is a sectional view taken along the line IV-IV in FIG. In the following description, the X direction in the figure will be described as the front side.

  The imaging device 1 is preferably mounted on, for example, a mobile phone terminal device, and includes an imaging device body 10 having a lens group 21 and a drive mechanism for driving the lens group 21 as shown in FIG. ing.

  The imaging apparatus body 10 includes a lens holding frame 2 as a driven member that holds a lens group 21, housings 31 and 32 that store the lens holding frame 2 and a driving mechanism, and a cover 4.

  The lens holding frame 2 is formed of a cylindrical shape, and holds the lens group 21 so as not to move on the inner peripheral side. The lens group 21 includes one or a plurality of lenses.

  The housing is composed of a first housing 31 and a second housing 32 disposed on the rear side of the first housing 31.

  The 2nd housing | casing 32 is comprised from the synthetic resin and the outer periphery consists of a square-shaped cylinder body by front view. The second housing 32 includes a frame holding portion 32 a that holds the lens holding frame 2 on the inner peripheral side. Further, the second housing 32 includes an actuator holding portion 32b (shown in FIG. 4) that accommodates and holds a weight 43 of an actuator 4 of a drive mechanism (to be described later) outside the diameter of the lens holding frame 2.

  The 1st housing | casing 31 is comprised from the synthetic resin, and as shown in FIG. 2, an outer periphery consists of a square-shaped cylinder body by front view. The first casing 31 includes four side walls 31b extending rearward from the front wall 31a, and the cylindrical body 7 of the driving mechanism that holds the lens holding frame 2 therein and the elastic body by the side walls 31b. The member 6 and the like can be stored.

  Moreover, two opposing holes out of the side walls 31b are provided with locking holes 31c for locking to the second housing 52 (only one appears in FIG. 2).

  Further, an opening 31d is formed in the front wall 31a so that the lens group 21 faces the outside. In addition, a hole 31e into which a distal end portion of a drive shaft 42 of the actuator 4 described later is inserted is provided at one corner on the outer peripheral side of the opening 31d in the front wall 31a.

  The first casing 31 is disposed on the front side of the second casing 32 as shown in FIG. 4, and in this state, the locking holes 31c shown in FIG. The first housing locking protrusion 32c is locked. Thereby, the 1st housing | casing 31 and the 2nd housing | casing 32 are connected.

  The cover 33 mainly serves to prevent electromagnetic noise from leaking outside. As shown in FIGS. 1 and 2, the cover 33 has a first to fourth side wall 33 a and has a rectangular outer shape in front view. Consists of things.

  In the present embodiment, the first to fourth side walls 33a are configured such that four pieces of a cross-shaped metal flat plate can be bent at substantially right angles to accommodate the first housing 31 and the second housing 32 therein. Is formed.

  Further, the cover 33 has an elastic locking claw 33c that is detachably locked to a locking recess 32e provided in the second housing 32 at each end of the first to fourth side walls 33a. It has.

  The cover 33 includes a cover opening 33 d formed on the front surface so as to overlap the opening 31 d of the first housing 31.

  Next, the drive mechanism will be described. This drive mechanism includes an actuator 4 and engaging members 6 and 7.

  As shown in FIG. 2, the actuator 4 includes a piezoelectric element 41 that is an electromechanical conversion element that expands and contracts in the axial direction, a columnar drive shaft 42 connected to one first end of the piezoelectric element 41, and a piezoelectric element 41. And a weight 43 connected to the other second end.

  The weight 43 is for generating a displacement due to expansion / contraction of the piezoelectric element 41 only on the drive shaft 42 side. In this embodiment, the weight 43 is formed of a cylindrical shape that is formed so that the outer diameter protrudes from the outer periphery of the piezoelectric element 41 to the entire outer periphery.

  It should be noted that the weight 43 can be omitted if the same function as that of the weight 43 can be exhibited, for example, by attaching the second end of the piezoelectric element 41 to the housing. Good.

  In the piezoelectric element 41, a plurality of piezoelectric layers are stacked, and as shown in FIG. 2, electrodes of each piezoelectric layer are drawn out on a pair of side surfaces. The electrodes on the side surfaces are connected to external connection terminals 46 and 47 via individual lead wires 44 and 45, respectively. Although not shown, the tips of the external connection terminals 46 and 47 are soldered to a printed circuit board on the terminal device side of the cellular phone or fitted into a connector mounted on the printed circuit board. 4, 6, 7, and 8, the lead wires 44 and 45 and the external connection terminals 46 and 47 are omitted for convenience of explanation.

  In the actuator 4 configured as described above, the weight 43 is held on the actuator holding portion 32b of the second housing 32 via an adhesive or the like as shown in FIG.

  As shown in FIG. 2, the engaging member includes an elastic member 6 and a cylindrical body 7. The elastic member 6 is formed by forming a leaf spring into a substantially ring shape. As shown in FIG. 5, the elastic member 6 includes a ring-shaped cylinder holding portion 63 having elasticity for holding the cylinder 7 and a first end disposed at the first end of the cylinder holding portion 63. A clamping unit 61 and a second clamping unit 62 disposed at the second end of the cylindrical body holding unit 63 are provided.

  The 1st clamping part 61 is formed so that it may protrude on the diameter outer side. On the other hand, the 2nd clamping part 62 is formed so that it may protrude inside a diameter. The first clamping part 61 is arranged on the outer side (outer peripheral side) of the second clamping part 62, and thereby the axial direction of the drive shaft 42 is between the first clamping part 61 and the second clamping part 62. A clamping portion 8 that slidably and movably moves in the radial direction is sandwiched. As shown in FIG. 5 (c), the clamping unit 8 does not clamp the drive shaft 42, and the distance L between the inner surface of the first clamping unit 61 and the outer surface of the second clamping unit 62 is It is formed to be smaller than the outer diameter of the drive shaft 42.

  Moreover, in this embodiment, the elastic member 6 is provided with the 1st latching | locking part 64 latched to the cylinder 7 at the said 1st end. The first locking portion 64 is constituted by a groove-shaped member formed so as to be recessed with a predetermined length in the circumferential direction from the end surface of the first end.

  The elastic member 6 includes a second locking portion 65 and a third locking portion 66 that are locked to the cylindrical body 7 at the second end. The 2nd latching | locking part 65 is comprised from the groove-shaped thing formed so that it might be dented by the predetermined length in the circumferential direction from the end surface of the said 2nd end.

  The third locking portion 66 is disposed on the lateral side of the second locking portion 65 with the second clamping portion 62 interposed therebetween. The 3rd latching | locking part 66 is comprised from the square-shaped hole.

  As shown in FIGS. 2, 6, and 7, the cylindrical body 7 is configured in a cylindrical shape in this embodiment. The cylindrical body 7 has, on its outer periphery, a held portion 70 that is held by the cylindrical body holding portion 63 of the elastic member 6, a receiving recess 71 that receives the second clamping portion 62, and the first of the elastic member 6. A first locking protrusion 73 that locks with the locking portion 64 and the third locking portion 66 and a second locking protrusion 74 that locks with the second locking portion 65 of the elastic member 6 are provided. .

  The held portion 70 has an outer diameter that is a diameter of the cylindrical body holding portion 63 in a normal state in which no force is applied to the cylindrical body holding portion 63 of the elastic member 6 (a state indicated by a one-dot chain line in FIG. 5C). It is formed larger than.

  In this embodiment, the receiving recess 71 includes a recess formed between the two first protrusions 71a and the second protrusion 71b that project from the outer periphery of the cylindrical body 7 to the outside of the diameter.

  The 1st latching protrusion 73 is formed so that it may protrude on the diameter outer side from the 1st convex part 71a. The 2nd latching protrusion piece 74 is formed so that it may protrude from the 2nd convex part 71b to a diameter inner side.

  Further, the cylindrical body 7 of this embodiment includes a movement restricting portion that restricts the elastic member 6 holding the held portion 70 so that the cylindrical body holding portion 63 does not relatively move in the axial direction of the cylindrical body 7. Yes. In this embodiment, the movement restricting portion includes a first movement restricting portion 75 that restricts the elastic member 6 from moving relative to the front side (one direction side) of the cylindrical body 7 in the axial direction, and the elastic member 6. Is provided with a second movement restricting portion 76 that restricts relative movement to the rear side (the other direction side) of the cylindrical body 7 in the axial direction.

  The first movement restricting portion 75 is formed so as to receive the cylindrical body holding portion 63 of the held elastic member 6 from the front side at a position separated from the receiving recessed portion 71 by about 180 ° in the circumferential direction. The first movement restricting portion 75 in this embodiment is formed on the rear surface of a substantially quadrangular prism-shaped protruding piece 75 a that protrudes from the outer periphery of the cylindrical body 7.

  The protruding piece 75a is fitted into a guide groove (not shown) provided in the first housing 31 so as to be slidable in the front-rear direction. Specifically, the guide groove is formed on the inner periphery of the first housing 31 along the front-rear direction at a predetermined depth with the same width as the protruding piece 75a. And when the cylinder 7 is accommodated in the 1st housing | casing 31, the protrusion piece 75a of the cylinder 7 is inserted by the guide groove, Thereby, the cylinder 7 is with respect to the 1st housing | casing 31, It is movable in the front-rear direction and does not rotate around the axis of the cylinder 7. Accordingly, the projecting piece 75 a functions as a guide portion that guides the cylindrical body 7 so that it can move in the front-rear direction and cannot rotate with respect to the first housing 31.

  As shown in FIG. 6 (b), the second movement restricting portion 76 is located at a position spaced by about 90 ° clockwise and 270 ° from the receiving recess 71, that is, at the receiving recess 71 and the above-described position. Between the 1st movement control part 75, it forms so that the cylinder holding | maintenance part 63 of the elastic member 6 may be received from back side. The axial distance between the second movement restricting portion 76 and the first movement restricting portion 75 is set to be approximately the same as the width of the elastic member 6.

  The cylindrical body 7 includes a lens holding portion 77 that holds the lens group 21 on the inner periphery thereof. The lens holding portion 77 of this embodiment is configured to hold the lens group 21 via the lens holding frame 2 so that the lens holding frame 2 is inserted into the lens holding portion 77 and fixed with an adhesive or the like. And hold.

  And this cylinder 7 is hold | maintained at the elastic member 6 as follows. As shown in FIGS. 7 and 8, the cylindrical body holding portion 63 of the elastic member 6 is disposed around the held portion 70 of the cylindrical body 7 so as to be wound around the entire circumference. In this state, the cylindrical body holding portion 63 is in a state where the diameter is larger than that in the normal state, and the elastic force acts on the inner side of the diameter, and the held portion 70 is held by the elastic force.

  Further, due to the elastic force, the second clamping portion 62 of the elastic member 6 enters the receiving recess 71 of the cylindrical body 7, and the second locking portion 65 of the elastic member 6 enters the second locking protrusion 74. Further, the third locking portion 66 of the elastic member 6 enters the first locking protrusion 73. Thereby, the movement of the 2nd clamping part 62 with respect to the cylinder 7 is controlled, and the movement to the axial direction and circumferential direction of the 2nd clamping part 62 with respect to the cylinder 7 can be controlled.

  Further, the first locking portion 64 of the elastic member 6 can enter the first locking protrusion 73 by the elastic force. Thereby, the movement to the axial direction of the 1st clamping part 61 with respect to the cylinder 7 can be controlled.

  Further, in this state, the elastic body 6 is relatively moved in the longitudinal direction of the cylindrical body 7 by the first movement restricting portion 75 and the second movement restricting portion 76 in the cylindrical body holding portion 63. Is prevented.

  As shown in FIGS. 7 and 8, the holding portion 7 formed between the first holding portion 61 and the second holding portion 62 of the elastic member 6 holding the cylindrical body 7 in this manner is used as shown in FIGS. (2) The drive shaft 42 of the actuator 4 held in the housing 32 is inserted against the elastic force of the cylindrical body holding portion 63. 7 and 8, the second housing 32 is omitted for convenience of explanation. This is the same in FIG.

  Thereby, the drive shaft 42 can be clamped by the first clamping portion 61 and the second clamping portion 62 by the elastic force of the cylindrical body holding portion 63 so as to be slidable in the axial direction of the drive shaft 42 and immovable in the radial direction. The first clamping unit 61 and the second clamping unit 62 can clamp the drive shaft 42 in the radial direction connecting the drive shaft 42 from the center of the cylindrical body 7. In this state, the engaging members 6 and 7 are engaged with the drive shaft 42 with a predetermined frictional force.

  At this time, since the cylindrical body holding portion 63 that exerts an elastic force on the first clamping portion 61 and the second clamping portion 62 is shaped to wind the outer circumference of the cylindrical body 7, the length of the cylindrical body holding portion 63. Can be made sufficiently long and the spring constant can be lowered. Therefore, even if a dimensional error of the elastic member 6 occurs, the sensitivity of the spring force can be kept low, and variations in driving by the drive shaft 42 of the actuator 4 can be suppressed.

  In addition, since the first sandwiching portion and the second sandwiching portion disposed at both ends of one elastic member are sandwiched so as to be slidable in the axial direction of the drive shaft 42 and immovable in the radial direction, the cylindrical body 7 is held. Is supported by the drive shaft 42 (via an elastic member), the cylinder can be moved in the axial direction of the drive shaft together with the elastic member, and a guide shaft or the like for guiding the cylinder can be dispensed with. Therefore, the number of parts can be reduced and the assemblability can be improved.

  After the engaging members 6 and 7 are engaged with the drive shaft 42, the first casing 51 is connected to the second casing 52 as described above, and in this state, the cover 33 is on the first casing 51 side. Is put on.

  In the imaging apparatus 1 configured as described above, the piezoelectric element 41 vibrates in the axial direction in accordance with the voltage application to the piezoelectric element 41 of the actuator 4, and the drive shaft 42 reciprocates due to the vibration. Then, by the reciprocation, the elastic member 6 engaged with a predetermined elastic force and the cylindrical body 7 held by the elastic member 6 move in the optical axis direction.

  More specifically, in this actuator 4, the displacement of the piezoelectric element 41 becomes a triangular wave by giving a rectangular wave with a predetermined duty ratio to the piezoelectric element 41, and the amplitude increases and decreases by changing the duty ratio of the rectangular wave. A triangular wave with a different slope is generated. The drive mechanism of the actuator 4 utilizes this.

  For example, when the drive shaft 42 is vibrated slowly, the elastic member 6 and the cylinder 7 frictionally engaged with the drive shaft 42 with a predetermined elastic force also move in response to the vibration, and the predetermined friction force If the drive shaft 42 is vibrated instantaneously to the extent that exceeds, the elastic member 6 and the cylinder 7 are left as they are. By repeatedly performing such vibration in the axial direction of the drive shaft 42, the elastic member 6 and the cylindrical body 7 can be moved in the axial direction of the drive shaft 42.

  As the elastic member 6 and the cylinder 7 move in the axial direction of the drive shaft 42, the lens group 21 held by the cylinder 7 moves together with the cylinder 7 via the lens holding frame 2. It is driven in the optical axis direction which is the axial direction.

1 Imaging device (lens unit)
2 Lens holding frame (driven member)
4 Actuator 6 Elastic member (engagement member)
7 cylinder (engaging member)
10 Imaging device body 41 Piezoelectric element (electromechanical transducer)
42 Drive shaft 61 1st clamping part 62 2nd clamping part 63 Cylindrical body holding part

Claims (4)

An actuator having a drive shaft coupled to the first end of the electromechanical conversion element; and an engagement member engaged with the drive shaft with a predetermined frictional force; and driving the engagement member with the drive shaft A drive mechanism for driving a driven member held by the engaging member,
The engaging member includes an elastic member and a cylindrical body that holds the driven member,
The elastic member includes: a cylinder holding part having elasticity that holds the cylinder; a first clamping part disposed at a first end of the cylinder holding part; and a second end of the cylinder holding part. A second holding portion disposed,
The cylindrical body holding portion is disposed so as to wind around the outer circumference of the cylindrical body and holds the outer circumference of the cylindrical body by the elastic force of the cylindrical body holding portion,
The first sandwiching portion and the second sandwiching portion are formed by the elastic force of the cylindrical body holding portion so that the held cylindrical body can move only in the axial direction of the driving shaft together with the elastic member. A drive mechanism characterized in that the drive shaft is clamped so as to be slidable in the axial direction and immovable in the radial direction.   The drive mechanism according to claim 1, wherein the cylindrical body includes a movement restricting portion that restricts the cylindrical body holding portion from moving in the axial direction of the cylindrical body with respect to the cylindrical body.   The drive mechanism according to claim 1, wherein the cylindrical body holding portion has a ring shape. The drive mechanism according to claim 1 or 2, and the driven member,
The driven member includes one or more lenses.

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