JPH10232337A - Linear actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a linear actuator capable of improving space efficiency and driving characteristic by making entire length short. SOLUTION: An engaging member T6 is fixed on either end face in a laminating direction of a laminated type piezoelectric element 74 formed by laminating plural piezoelectric element ingredients, and the other end face is fixed on a fixed part 72. The member 76 is provided with a fixed wall part 77 fixed at the end face of the element 74, and a supporting wall part 78(78a to 78e) connected to one side of the wall part 77 and extended along the side surface of the element 74. The wall part 78 supports a frictional engaging part 78e interposing a member to be driven on the side of the element 74.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear actuator, and more particularly, to a linear actuator using an electromechanical transducer, and more particularly to a linear actuator suitable as a driving source for a driving device for precision equipment.

[0002]

2. Description of the Related Art Conventionally, linear actuators have been provided as driving devices for precision equipment such as video cameras.

For example, Japanese Unexamined Patent Publication No. 4-69070 discloses a laminated thick electric element 202 in which a plurality of piezoelectric element elements are laminated, that is, as shown in FIG. A linear actuator 200 is disclosed in which a rod-shaped engaging member 208 is fixed to one end surface 204 of the electromechanical transducer 202 that generates displacement in accordance with a signal in the stacking direction, that is, one end surface in the displacement direction. The other end surface 206 of the electromechanical transducer 202 in the displacement direction is fixed to a fixing member 209. The driven member 210 is slidably supported by an engagement member 208 and a guide bar 214 fixed in parallel with the engagement member 208. That is, the engaging member 2
08 is inserted into the sliding contact hole 212 of the driven member 210,
The sliding contact hole 212 of the driven member 210 is pressed against the engaging member 208 by the elastic force of the leaf spring 216 screwed to the driven member 210, and the engaging member 208 and the driven member 210
Are frictionally engaged with each other.

Since each piezoelectric element of the electromechanical transducer 202 is extended by applying a voltage, a periodic voltage is applied to the electromechanical transducer 202 to apply a voltage to the electromechanical transducer 20.
2 is expanded and contracted in the displacement direction, and the engaging member 208 is reciprocated in the axial direction.
0 means that the driven member 210 can be moved. For example, by applying a voltage so that the elongation speed and the contraction speed of the electromechanical transducer 202 are different from each other, and feed and slip occur alternately at a frictional engagement portion between the engagement member 208 and the driven member 210 during expansion and contraction. Thus, the driven member 210 can be intermittently finely fed.

That is, in principle, when the engaging member 208 moves slowly, the driven member 210
Is caused by the frictional force at the frictional engagement portion.
Move with. On the other hand, when the engagement member 208 moves faster than a certain degree and the inertial force becomes larger than the frictional force of the frictional engagement portion, a slip occurs in the frictional engagement portion, and the driven member 210 remains stationary or substantially stationary. Engaging member 2
Only 08 moves. Therefore, when the engaging member 208 moves in one direction, the driven member 210 is moved to the engaging member 208.
When the engagement member 208 is moved in the other direction, the engagement member 208 is moved while the driven member 210 is stationary or substantially stationary by sliding, and the movement is repeated. The driving member 210 can be intermittently moved in one direction.

However, this linear actuator 200
Since the long engaging member 208 is fixed to the end face 204 of the electromechanical transducer 202, the overall length is long and the space efficiency is low, and the vibration system is long and the resonance point is lowered. The drive frequency of the linear actuator 200 is limited to a low range, and it is difficult to improve the drive characteristics.

[0007]

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a linear actuator capable of shortening its overall length and improving space efficiency and driving characteristics.

[0008]

In order to solve the above technical problems, according to the present invention, there is provided a linear actuator having the following configuration.

The linear actuator is provided with an electromechanical transducer for generating a displacement in accordance with the electric signal by applying a predetermined electric signal, an engaging member fixed to one end face of the electromechanical transducer in the direction of displacement. Having. In the linear actuator, the engaging member frictionally engages with the driven member, and the other end face in the displacement direction of the electromechanical transducer is supported by the fixed member. Linear actuators are
A voltage is applied to the electromechanical transducer to expand and contract the electromechanical transducer, and the driven member is moved by sliding and feeding at a frictional engagement portion between the engaging member and the driven member. The engaging member includes a fixed wall portion fixed to the one end surface of the electromechanical conversion element, and a support connected to a peripheral edge of the fixed wall portion and extending substantially along a side surface of the electromechanical conversion element. It has a wall portion and a frictional engagement portion supported by the support wall portion on the side of the electromechanical transducer, that is, between both end faces in the displacement direction of the electromechanical transducer, in a direction perpendicular to the displacement direction.

In the above configuration, the fixed wall of the engaging member is fixed to one end surface of the electromechanical transducer, and the support wall of the engaging member extends substantially along the side surface of the electromechanical transducer. The total length of the linear actuator can be reduced to about the length of the electromechanical transducer.

Therefore, it is possible to provide a linear actuator capable of shortening the overall length and improving the space efficiency and the driving characteristics.

The above-structured linear actuator is embodied in various modes.

Preferably, the engagement member has the fixed wall, the support wall, and the frictional engagement formed integrally. The support wall has a first piece, a pair of second pieces, and a pair of third pieces. The first piece extends along a side surface of the electromechanical transducer in a direction substantially perpendicular to one side of the peripheral edge of the fixed wall portion. The pair of second pieces sandwich the electromechanical transducer at substantially right angles from a pair of sides of the first piece that extend substantially perpendicularly to the one side of the peripheral edge of the fixed wall. Each extends along a side surface of the electromechanical conversion element to a side opposite to the first piece. The pair of third pieces are, with respect to the electromechanical conversion element, the first piece from each end of the pair of second pieces opposite to the first piece across the electromechanical conversion element. Project substantially parallel to each other in opposite directions, and sandwich a driven member as the friction engagement portion.

In the above construction, the first piece and the pair of second pieces of the engaging member extend around the electromechanical transducer so as to enclose the electromechanical transducer, and extend from the fixed wall to the frictional engaging part. The distance to a certain third piece is somewhat longer. Therefore, it is possible to easily configure the friction engagement portion so as to sandwich the driven member with a predetermined spring constant. In addition, the third piece of the engaging member is arranged close to the electromechanical transducer, and the distance between the frictional engagement portion and the electromechanical transducer can be shortened.

Therefore, it is possible to provide a linear actuator having a simple configuration in which the engagement member sandwiches the driven member and the moment acting on the electromechanical transducer by frictional engagement is reduced.

Preferably, the engagement member has the fixed wall, the support wall, and the frictional engagement formed integrally. The support wall has a first piece and a second piece. The first piece extends along a side surface of the electromechanical transducer at a substantially right angle from one side of the peripheral edge of the fixed wall portion. The second piece may be connected to the electromechanical conversion element from one of a pair of sides of the first piece extending substantially perpendicularly to the one side of the periphery of the fixed wall portion of the first piece. A substantially right angle extends to the opposite side. Both surfaces of the second piece are held by the holding portions provided on the driven member as the friction engagement portions.

According to the above configuration, the friction engagement portion of the second piece of the engagement member held by the holding portion of the driven member can be arranged close to the electromechanical transducer.

Therefore, it is possible to provide a linear actuator having a simple structure in which the engaging member is sandwiched between the driven members and the moment acting on the electromechanical transducer by frictional engagement is reduced.

Preferably, the engagement member has the fixed wall, the support wall, and the frictional engagement formed integrally. The support wall portion includes a pair of engagement pieces extending substantially at right angles along a side surface of the electromechanical conversion element from a pair of opposite sides of the peripheral edge of the fixed wall portion. The outer surfaces of the pair of engagement pieces opposite to the electromechanical conversion element are held by the holding portions provided on the driven member as the friction engagement portions.

According to the above configuration, the engaging member is formed by connecting a pair of engaging pieces on both sides of the fixed wall in a substantially U-shaped cross section. The pair of engagement pieces frictionally engage with the holding portion of the driven member on both sides of the electromechanical transducer. The moment acting on the electromechanical transducer due to the frictional engagement between the one engaging piece and the holding portion and the moment acting on the electromechanical transducer due to the frictional engagement between the other engaging piece and the holding portion are as follows. , The sizes are substantially the same, and the directions are opposite to each other. Therefore, both moments cancel each other out, so that no moment acts on the electromechanical transducer.

Therefore, it is possible to provide a linear actuator having a simple structure in which the engagement member is sandwiched between the driven members and the influence of the moment due to the frictional engagement is minimized.

Preferably, the engagement member has the fixed wall, the support wall, and the frictional engagement formed integrally. The support wall portion extends at right angles along a side surface of the electromechanical conversion element from a pair of opposing sides of the periphery of the fixed wall portion, and extends from the pair of sides of the periphery of the fixed wall portion. It consists of a pair of engaging pieces projecting substantially parallel to each other on both sides beyond the side surface of the electromechanical transducer in the extending direction. The pair of engagement pieces sandwich the driven member as the friction engagement portion.

In the above configuration, the driven member is sandwiched between the projecting portions of the pair of engagement pieces, that is, on both sides of the electromechanical transducer. That is, the friction engagement portions are arranged on both sides of the electromechanical transducer. Therefore, the moments acting on the electromechanical transducers due to the frictional engagement cancel each other, so that no moments act on the electromechanical transducers.

Therefore, it is possible to provide a linear actuator having a simple configuration in which the engagement member sandwiches the driven member and the influence of the moment due to frictional engagement is minimized.

The engaging member is typically formed integrally by bending a single plate, but may be formed by, for example, shaving, welding, or injection molding.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention applied to a digital camera 1 shown in the external view of FIG. 1 will be described.
This will be described in detail with reference to FIGS.

First, a first embodiment will be described. A digital camera 1 to which the present invention is applied has a thin rectangular parallelepiped housing 2. The photographing window 3, the exposure adjustment lever 5, and the shutter button 82 are arranged on one elongated side 2a of the housing 2, and the external power supply terminal 88 and the serial output terminal 89 are arranged on the other side 2b. In addition, on the upper surface 2c, the liquid crystal monitor 6, on which a captured image is displayed, a main switch 80, and a zoom switch 81 are arranged. Inside the housing 2, an optical unit 4 having a CCD element 90 on the opposite side to the photographing window 3, a circuit board 8 including an arithmetic control circuit and a flash memory, and a rechargeable battery 9 are housed. . The amount of light received by the CCD element 90 can be adjusted by sliding the exposure adjustment lever 5 toward the imaging window 3 and inserting an exposure adjustment ND filter (not shown) in front of the optical unit 4.

The optical unit 4 includes four groups of zoom lens mechanisms. First to fourth lens groups 12, 22, 32, and 42 each including one or two or more lenses are schematically shown in FIG. It has the zoom curves 11, 21, 31, 41 shown. The optical unit 4 includes a first unit 1 including a first lens group 12, as shown in a perspective view of FIG.
0, a second unit 20 including the second lens group 22, a third unit 30 including the third lens group 32, a fourth unit 40 including the fourth lens group 42, and a low-pass filter 5.
2 and a base unit 50 including a CCD element 90. The first to fourth units 10, 20, 30, 40 are
First to fourth lens supporting portions 15, 25, 35, 45 projecting from the upper ends of the flat moving plates 16, 26, 36, 46
Lens support members 14, 24, 34, 44, respectively.
The lens support portions 15, 25, 35, and 45 support the first to fourth lens groups 12, 22, 32, and 42, respectively. The base unit 50 includes a base member 54 having a low-pass filter support 55 and a CCD element support 92 projecting from the upper end of a flat fixed plate 56. The low-pass filter support section 55 supports the low-pass filter 52 and has a CCD
The element supporting section 92 supports the CCD element 90. As shown in FIG. 2, the moving plates 16, 26, 36, 46 of the stacked first to fourth lens support members 14, 24, 34, 44 are placed on the fixing plate 56 of the base member 54, and Spring 6
4 to be energized.

The fixing plate 56 of the base member 54 is shown in FIG.
As shown in FIG. 2, the cam hole 57 and a pair of straight guide pins 58 and 59 projecting perpendicularly to the plate surface are provided. First to fourth
Moving plate 16,2 of lens support member 14,24,34,44
As shown in FIGS. 4 (e), 4 (d), 4 (c) and 4 (b), 6, 36 and 46 are three holes penetrating therethrough, ie, a relief hole 17 and a cam hole 2.
7, 37, 47, and a pair of rectilinear guide holes 18, 19; 28, 29; 38, 29; 48, 49, which are long holes extending in the optical axis direction.
Respectively. A pair of rectilinear guide holes 18, 19; 28, 29; 38, 39; 4 of each moving plate 16, 26, 36, 46
A pair of rectilinear guide pins 58 and 59 of the fixed plate 56 of the base member 54 are respectively inserted into and slidably contact with 8 and 49, and the movable plates 16 and 24 of the first to fourth lens support members 14, 24, 34 and 44. 236, 36, 46 are supported by the fixing plate 56 of the base member 54 while being guided straight in the optical axis direction. The moving plate 16 of the first lens support member 14 has an interlock bar 60 whose one end 61 is rotatably fixed to the moving plate 16 as shown in FIGS. At the other end of the interlock bar 60, an interlock pin 62 protrudes.
The interlocking pin 62 passes through the clearance hole 17 of the moving plate 16 of the first lens support member 14 and the cam holes 27, 36 of the moving plates 26, 36, 46 of the second to fourth lens support members 24, 34, 44.
37, 47 and the cam holes 57 of the fixed plate 56 of the base member 54 are inserted into sliding contact with each other. Then, as the moving plate 16 of the first lens support member 14 moves in the optical axis direction, the second
Moving plate 26,3 of fourth lens support member 24,34,44
6 and 46 move in the optical axis direction while overlapping each other, and the first to fourth lens groups 12, 22, 32 and 42
The predetermined zoom movement shown in FIG.

The moving plate 16 of the first lens support member 14
Driving member 70 fixed to fixing plate 56 of base member 54
Thus, it can be moved in the optical axis direction.

The driving member 70 is a linear actuator in which an engaging member 76 is fixed to one end face of the laminated piezoelectric element 74 in the laminating direction, as shown in the perspective views of FIGS. The other end face of the multilayer piezoelectric element 72 is fixed to the fixing section 72. The fixing part 72 is fixed to the fixing plate 56 of the base member 54. The driving member 70, that is, the laminated piezoelectric element 74 and the engagement member 76
And extends in the optical axis direction while being separated from the fixing plate 56. The laminated piezoelectric element 74 is formed by laminating a plurality of piezoelectric element elements, and the laminating direction coincides with the optical axis direction. The multi-layer piezoelectric element 74 is an electromechanical transducer, and expands and contracts in the laminating direction by applying a voltage. The engagement member 76 has a fixed wall 77 fixed to the end face of the stacked piezoelectric element 74 and a support wall 78 extending from the fixed wall 77 so as to cover the side surface of the stacked piezoelectric element 74. The support wall 78 is provided in FIGS.
As shown in the cross-sectional view perpendicular to the optical axis, a bottom piece 78a that is bent at a substantially right angle from one side of the fixed wall portion 77 toward the multilayer piezoelectric element 74 to cover the bottom face 74a of the multilayer piezoelectric element 74, and a bottom piece 7
A pair of side pieces 78b, which are bent at substantially right angles from both sides of 8a to cover both side faces 74b of the multilayer piezoelectric element 74, and a side piece 7
8b, two upper pieces 78c which are bent inward from the upper side at substantially right angles to cover the upper surface 74c of the multilayer piezoelectric element 74, and are bent upward from the substantially central portion of the upper surface 74c of the multilayer piezoelectric element 74 from both upper pieces 78c. And two standing pieces 78d. The two standing pieces 78d extend substantially parallel to each other, and each of the tip portions has a protruding portion 78e projecting inward from each other. 2 and 6 between the two protruding portions 78e.
As shown in (1), the lower edge 16a of the moving portion 16 of the first lens support member 14 is elastically pressed, so that the lower edge 16a and the protruding portion 78e are frictionally engaged. That is, the protruding portion 78e is a friction engagement portion.

Due to the frictional engagement of the projection 78e with the movable plate 16, the driving member 70 causes the first lens supporting member 1 to move.
4 can be moved. That is, the driving member 70
When the protrusion 78e of the engaging member 76 moves slowly, the lower edge 1 of the moving plate 16 of the first lens support member 14 is moved.
6a moves integrally with the protrusion 78e due to the frictional force between the protrusion 78e and the lower edge 16a. On the other hand, when the protrusion 78e moves while rapidly changing the speed, the inertia force becomes larger than the frictional force between the protrusion 78e and the lower edge 16a, and a slip occurs between the two, and the protrusion 78e
It moves relatively to the lower edge 16a. Therefore,
A periodic voltage including a sharp voltage change such as a sudden change in the speed of the protrusion 78e, for example, a voltage changing in a sawtooth shape or a full-wave rectification shape is changed by a voltage generating device which is a piezoelectric actuator driving means (not shown). A voltage is applied to the multilayer piezoelectric element 74 to expand and contract the multilayer piezoelectric element 74, and the protrusion 78e
Is reciprocated in the optical axis direction. For example, at the time of reversing the protruding portion 78e from the forward to the reverse, or at the time of reversing the reversing from the forward to the forward, between the protruding portion 78e and the lower edge 16a The first lens support member 14 is intermittently moved in one of the forward direction and the backward direction by preventing the relative movement from occurring between the two members due to the occurrence of the slip and the relative movement between the two members. Fine feed can be achieved. Alternatively, in both forward and backward movements of the reciprocating movement of the protrusion 78e, slippage occurs between the protrusion 78e and the lower edge 16a, but the relative slip direction and length are different between forward and backward. It is also possible to move the first lens support member 14 in any one direction while vibrating. By changing the voltage pattern applied to the multilayer piezoelectric element 74, the moving direction of the first lens support member 14 can be changed.

Further, the support wall portion 78 is
4, so that the distance from the fixed wall portion 77 to the protruding portion 78e is increased to some extent to obtain a desired spring constant, and the frictional engagement portion is moved closer to the laminated piezoelectric element 74. By arranging, the moment acting on the laminated piezoelectric element 74 from the frictional engagement portion can be minimized.

As described above, the first member is driven by the driving member 70.
When the lens support member 14 is moved in the optical axis direction, the optical unit 4 of the digital camera 1 is moved to its second position by the engagement of the interlocking pin 62 of the interlocking bar 60 with the cam holes 27, 37, 47, 57. -The fourth lens support members 24, 34, 44 are moved in conjunction with each other. At this time, since the first to fourth lens support members 14, 24, 34, 44 are urged by the fixing plate 56 by the pressing spring 64, they move along the fixing plate 56, and A pair of projecting linear guide pins 58, 59 and a pair of linear guide holes 18, 19;
9; 38, 39; 48, 49, the guide is guided straight in the optical axis direction. Therefore, each lens support part 15, 2
Each lens group 12, 22, 32 fixed to 5, 35, 45,
The reference numeral 42 performs zoom movement with high precision along the optical axis without tilting.

In the above arrangement, each of the lens groups 12, 22,
32, 42, each driving lens support member 14, 24, 34,
44 and the base member 54, etc., each lens group 12, 22,
Since they are stacked and arranged collectively on one side in the radial direction of the lens groups 32, 42, the stacking thickness is set to each lens group 12, 22, 32, 4
2 can be as small as, or smaller than, the diameter of 2. Therefore, it is possible to configure the optical unit 4 including the zoom lens mechanism in which the diameter in one direction is reduced as much as possible.

In the digital camera 1, the CCD 9
0, the light receiving surface is small, so that each lens group 12, 22, 32,
42, the allowable value of the eccentric error is small. Therefore, each lens group 12, 22, 32, 42 is
It is difficult to achieve a predetermined positional accuracy with respect to the optical axis only by the accuracy of the components such as the base member 54, the base member 54, and the like. Then, after assembling the lens support mechanism except for the attachment of each lens group 12, 22, 32, 42, each of the lens groups 12, 22, 32, 42 is performed as follows. 34,44 lens support parts 15,2
Fix while aligning one by one in 5,35,45 one by one.

That is, as shown in the perspective view of FIG. 7, at a predetermined position in front and rear along the optical axis 106 of the lens support mechanism that has been assembled except for the mounting of the lens groups 12, 22, 32, and 42. The light emitter 102 and the light receiver 103 are fixed. At this time, the lens support portions 15, 25, 35, 45
Are arranged along the optical axis.

Next, one lens group appropriately selected,
For example, the outer peripheral surface of the second lens group 22 is
0, and placed on a predetermined lens support 25, that is, a lens frame 25 from the side of the optical axis 106, and
While observing the output from No. 3, the lens group 22 is positioned so that the center thereof coincides with the optical axis 106. In particular,
For example, the projector 102 emits parallel light parallel to the optical axis, arranges the light receiver 103 at a position corresponding to the focal length, moves the lens group 22 in the radial direction, and adjusts the image formation position observed from the light receiver 103. While watching, the lens group 22 is positioned. Then, while holding the lens group 22 in the positioned state, an adhesive is applied to the periphery of the lens group 22 by using an adhesive injector 104 so that the lens group 22 is moved to the lens support portion 2.
Adhere to 5. At this time, the lens group 22 is held during the bonding by holding the lens group 22 until the adhesive is hardened.
Misalignment can be prevented. Note that an adhesive may be applied to the lens support 25 in advance before the lens group 22 is placed.

The above operation is repeated for each lens group 12, 22, 3
By repeating 2,42 in an appropriate order,
Each lens group 12, 22, 32, 42 can be attached with high accuracy along the optical axis 106.

Therefore, centering can be performed not only on the lens groups 12 and 42 disposed at the front and rear ends of the zoom lens mechanism but also on the lens groups 22 and 32 disposed at the intermediate position.

In the above configuration, since the optical unit 4 is opened over substantially the entire circumference of each of the lens support portions 15, 25, 35, and 45, each of the lens groups 12, 22, 32, and 42 is supported by each of the lens support portions 15, 25, 35, and 45. It is easy to bring up to the parts 15, 25, 35, 45. However, at least each lens group 1
If there is an opening having a size equal to the diameter of 2, 22, 32, 42, each lens group 12, 22, 32, 42 can be brought to each lens support 15, 25, 35, 45.

In the first embodiment described above, the projecting portion 78e of the driving member 70 sandwiches the lower edge portion 16a of the first lens support member 16. On the contrary, the perspective view of the main part in FIGS. As in the second and third embodiments shown in the drawings, the driving members 70x and 70y may be configured to be clamped. Hereinafter, the second and third embodiments will be described focusing on differences from the first embodiment.

That is, in the second embodiment shown in FIG. 8, the engaging member 76x of the driving member 70x is connected to the fixed wall 77 fixed to the end of the multilayer piezoelectric element 74 and the fixed wall 77 And a support wall 78x extending to one side of the multilayer piezoelectric element 74. The support wall portion 78x is bent at a substantially right angle from one side of the fixed wall portion 77 to the multilayer piezoelectric element 74 side to cover one side surface of the multilayer piezoelectric element 74, that is, a side piece 78s and a side piece 78s. It is composed of a second piece, that is, a wing piece 78t, which is bent at a substantially right angle from the upper side to the opposite side to the laminated piezoelectric element 74. The wing piece 78t is sandwiched between a moving plate 16x fixed to be movable in the optical axis direction and a holding plate 16s fixed to the moving plate 16x, so as to be frictionally engaged. Therefore, similarly to the first embodiment, the multilayer piezoelectric element 74 is expanded and contracted in a predetermined pattern,
The relative movement between the moving plate 16x, the holding plate 16s, and the wing piece 78t of the driving member 70x is intermittently generated by the sliding and feeding between the x and holding plate 16s and the wing piece 78t of the driving member 70x, The moving plate 16x can be moved. Since the blade pieces 78t are arranged close to the laminated piezoelectric element 74, the moment acting on the laminated piezoelectric element 74 from the frictional engagement portion can be made as small as possible with a simple configuration.

In the third embodiment shown in FIG. 9, the engaging member 76y of the driving member 70y includes a fixed wall 77 fixed to the end of the laminated piezoelectric element 74 and a fixed wall 77 of the fixed wall 77. A pair of support walls 7 that are bent at substantially right angles from the upper side and the lower side and extend along the upper and lower sides of the multilayer piezoelectric element 74.
8y. The pair of support wall portions 78y, that is, the engagement pieces are sandwiched between a movable plate 16y fixed to be movable in the optical axis direction and a holding plate 16t fixed to the movable plate 16y, and the laminated piezoelectric element 74 is held. It is designed to frictionally engage on both sides of the body. Therefore, if the moment acting on the laminated piezoelectric element 74 from the frictional engagement portion is canceled, the moment can be prevented from acting on the laminated piezoelectric element 74 as a whole with a simple configuration.

In the second and third embodiments, the projections 16b at one ends of the movable plates 16x and 16y are provided with a first lens support member (not shown) substantially similar to the first lens support member 14 of the first embodiment. The first lens support member (not shown) is fixed or engaged with the lens support member and is integrally moved with the movable plate 16x in both directions in the optical axis direction.

Next, similarly to the third embodiment, the driving member 7
A fourth embodiment in which 0z has friction engagement portions on both sides of the laminated piezoelectric element 74 will be described with reference to the perspective view of the main part in FIG.

That is, a notch 16c extending in the optical axis direction is formed in the movable plate 16z, and the driving member 70z is disposed in the notch 16c. The engaging member 76z of the driving member 70z is fixed to the end face of the laminated piezoelectric element 74, and is bent at a substantially right angle from the upper side and the lower side of the fixed wall section 77 so that the upper and lower sides of the laminated piezoelectric element 74 And a pair of support wall portions 78z extending along both sides. The pair of support wall portions 78z protrude from the upper surface and the lower surface of the multilayer piezoelectric element 74 to the left and right sides, respectively. This support wall 7
At both left and right ends of 8Z, protruding portions 78v protruding inward from each other are formed. The portion 78w in which the interval between the opposed protruding portions 78v is narrowed is configured to frictionally engage with the periphery 16d on both sides of the notch 16c of the moving plate 16z. Since the driving member 70 has the friction engagement portions disposed on both sides of the multilayer piezoelectric element 74, the driving member 70 receives the multilayer piezoelectric element 7 from each of the left and right friction engagement portions.
4 can cancel each other, so that no moment acts on the laminated piezoelectric element 74.

The present invention is not limited to the above embodiments, but can be implemented in various other modes.
For example, two sets of zoom lens optical systems may be arranged on both sides of the movable plates 16, 26, 36, 46. Further, the disclosed linear actuator, that is, the driving members 70, 70x, 70y, and 70z use the multilayer piezoelectric element 74 as an electromechanical conversion element that generates a displacement according to a predetermined electric signal when the signal is given. However, another electromechanical transducer, for example, an electrostatic actuator or an electrostrictive element may be used. Also, the disclosed linear actuators 70, 70x, 70y, 70z can be used in various fields other than the zoom lens mechanism.

[Brief description of the drawings]

FIG. 1 is an external view of a digital camera according to a first embodiment of the present invention.

FIG. 2 is a perspective view of an optical unit of the digital camera in FIG.

FIG. 3 is an explanatory diagram of the zoom lens of FIG. 2;

FIG. 4 is a plan view of a moving plate of each lens supporting member and a fixing plate of a base member of FIG. 2;

FIG. 5 is a perspective view of the driving member of FIG. 2;

FIG. 6 is a sectional view taken along line VI-VI of FIG. 5;

7 is an explanatory diagram of a method of attaching a lens group of the optical unit in FIG. 2;

FIG. 8 is a perspective view of a main part of a driving member according to a second embodiment of the present invention.

FIG. 9 is a perspective view of a main part of a driving member according to a third embodiment of the present invention.

FIG. 10 is a perspective view of a main part of a driving member according to a fourth embodiment of the present invention.

FIG. 11 is a perspective view of a main part of a driving device using a conventional linear actuator.

[Explanation of symbols]

Reference Signs List 1 digital camera 2 housing 2a, 2b side surface 2c top surface 3 shooting window 4 optical unit 5 exposure adjustment lever 6 liquid crystal monitor 8 circuit board 9 rechargeable battery 10 first unit 11 zoom curve 12 first lens group 14 first lens support member 15 lens Supporting part (lens frame) 16 Moving plate 16a Lower edge 16b Projecting part 16c Notch 16d Around 16s, 16t Pressing plate 16x, 16y, 16z Moving plate 17 Escape hole 18 Straight guide hole 19 Straight guide hole 20 Second unit 21 Zoom Curve 22 Second lens group 24 Second lens support member 25 Lens support part (lens frame) 26 Moving plate 27 Cam hole (Second drive means) 28 Straight guide hole 29 Straight guide hole 30 Third unit 31 Zoom curve 32 Third Lens group 34 Third lens support member 35 Lens support (lens frame) 36 Moving plate 37 Cam Hole (second drive means) 38 Straight guide hole 39 Straight guide hole 40 Fourth unit 41 Zoom curve 42 Fourth lens group 44 Fourth lens support member 45 Lens support part (lens frame) 46 Moving plate 47 Cam hole (second) Driving means) 48 straight guide hole 49 straight guide hole 50 base unit 52 low-pass filter 54 base member 55 low-pass filter support 56 fixing plate 57 cam hole (second drive means) 58 straight guide pin 59 straight guide pin 60 interlocking bar (first bar) 2 driving means) 61 one end 62 interlocking pin 64 holding spring 70, 70x, 70y, 70z driving member (driving means, first driving means, linear actuator) 72 fixing part 74 laminated piezoelectric element (electromechanical conversion element) 74a bottom surface 74b Side surface 74c Top surface 76, 76x, 76y, 76z Engaging member 77 Fixed wall 78 Support wall 78a Bottom Piece (first piece) 78b Side piece (second piece) 78c Upper piece (second piece) 78d Standing piece (third piece) 78e Projection (friction engagement portion) 78s Side piece (first piece) 78t Wing piece (Second piece) 78v Projecting portion (friction engaging portion) 78w Narrow space 78x Support wall 78y, 78z Support wall (engaging piece) 80 Main switch 81 Zoom switch 82 Shutter button 88 External power supply terminal 89 Serial output Terminal 90 CCD element 92 CCD support part 100 Lens gripper 102 Light emitter 103 Light receiver 104 Adhesive injector 106 Optical axis

Claims (5)

[Claims] 1. An electromechanical transducer for generating a displacement in accordance with an electric signal by applying a predetermined electric signal, and an engaging member fixed to one end face of the electromechanical transducer in a displacement direction. A linear actuator,
While the engaging member frictionally engages the driven member, the other end face of the electromechanical transducer in the displacement direction is supported by a fixed member, and a voltage is applied to the electromechanical transducer to apply a voltage to the electromechanical transducer. The linear actuator, wherein the driven member is moved by sliding and feeding at a frictional engagement portion between the engagement member and the driven member. A fixed wall portion fixed to the one end surface; a support wall portion connected to a peripheral edge of the fixed wall portion and extending substantially along a side surface of the electromechanical conversion element; A linear actuator having a friction engagement portion supported on a side of the conversion element. 2. The engagement member has the fixed wall, the support wall, and the frictional engagement formed integrally, and the support wall includes the peripheral edge of the fixed wall. A first piece extending substantially perpendicularly from one side of the electromechanical transducer along a side surface of the electromechanical transducer; and a first piece extending substantially perpendicular to the one side of the peripheral edge of the fixed wall portion. At a substantially right angle from a pair of sides of
A pair of second pieces each extending along the side surface of the electromechanical conversion element to a side opposite to the first piece with the electromechanical conversion element interposed therebetween; From each end side of the pair of second pieces on the opposite side to the piece, the first piece projects substantially parallel to the electromechanical conversion element in a direction opposite to the first piece, and as the frictional engagement portion, The linear actuator according to claim 1, further comprising a pair of third pieces that sandwich the driven member. 3. The fixing member has the fixed wall, the support wall, and the frictional engagement formed integrally, and the support wall has a peripheral edge of the fixed wall. A first piece extending substantially perpendicularly from one side along the side surface of the electromechanical transducer, and a first piece extending substantially perpendicularly to the one side of the peripheral edge of the fixed wall portion. A second piece extending at a substantially right angle from one of the pair of side sides to the opposite side to the electromechanical conversion element, and both surfaces of the second piece serve as the frictional engagement portion for the driven member; 2. The linear actuator according to claim 1, wherein the linear actuator is held by a holding portion provided. 4. The fixing member has the fixed wall, the support wall, and the frictional engagement formed integrally, and the support wall has a peripheral edge of the fixed wall. A pair of engaging pieces extending substantially at right angles from the pair of opposing sides along the side surface of the electromechanical transducer, respectively, on the opposite side of the pair of engaging pieces from the electromechanical transducer. 2. The linear actuator according to claim 1, wherein the outer surface is clamped by a clamping portion provided on the driven member as the friction engagement portion. 5. The engagement member includes the fixed wall, the support wall, and the frictional engagement formed integrally, and the support wall includes the peripheral edge of the fixed wall. Extending at right angles along a side surface of the electromechanical conversion element from a pair of opposite sides of
A pair of projections projecting in parallel with each other beyond the side surfaces of the electromechanical transducer in the direction in which the pair of sides of the peripheral edge of the fixed wall extend, and serving as the friction engagement portions for sandwiching a driven member. 2. An engagement piece comprising:
The linear actuator as described.