JP2006311794A - Driving device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a driving device having a driving shaft which is light, inexpensive, and has high degrees of freedom for shaping. <P>SOLUTION: The driving device 10 is provided with a piezoelectric element 14 which expands and contracts, when a voltage is applied, and a driving shaft 16 which supports a movable body 18 slidably and is coupled to the piezoelectric element 14 to be displaced together with the piezoelectric element 14. According to the expansion and contraction of the piezoelectric element 14, the movable body 18 slides along the driving shaft 16. The material of the driving shaft 16 is fiber-reinforced resin complex. A synthetic resin material, composing the fiber reinforced resin complex, is a liquid crystal polymer or polyphenylene sulfide. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a drive device suitable for driving an optical member such as a lens used in a reading device for a recording medium such as a camera, a DVD, a CD, or an MD, or an endoscope.

  2. Description of the Related Art Conventionally, a driving apparatus that moves a moving body by using expansion and contraction of a piezoelectric element that is an electromechanical conversion element is known. 1 and 2 show an example of a linear drive device. In the driving apparatus 100 shown in FIG. 1, one end in the expansion / contraction direction of the piezoelectric element 101 is fixed to the end surface of the fixed body 102 with an adhesive 102a, and the driving shaft 103, which is a moving body support member, is fixed to the other end with an adhesive 101a. Has been. In addition, a power supply member 104 is connected to the piezoelectric element 101 with a conductive adhesive, whereby a predetermined pulse voltage is applied to the piezoelectric element 101.

  As shown in FIG. 2, the moving body 108 is slidable along the drive shaft 103. The moving body 108 includes a slider 105, a sandwiching member 106 that sandwiches the drive shaft 103 between the slider 105, and a plate spring 107 that presses the sandwiching member 106 toward the slider 105 while sandwiching the drive shaft 103. ing. By attaching an optical member such as a lens to the slider 105, the optical member is linearly driven when the moving body 108 moves on the drive shaft 103.

  FIG. 3 shows the driving principle of the driving device 100. For example, a pulse voltage having a sawtooth waveform having a gentle rising portion (between A and B) and a sharp falling portion (between B and C) as shown in FIG. 3B is applied to the piezoelectric element 101 of the driving device 100. When the voltage is applied, first, at the gently rising portion (between A and B) of the pulse voltage, the piezoelectric element 101 is gently extended and displaced in the thickness direction as shown in FIG. The drive shaft 103 is moved in the feeding direction. Along with this, the moving body 108 frictionally engaged with the drive shaft 103 moves together with the drive shaft 103.

  Subsequently, at the sudden falling part (between B and C) of the pulse voltage, the piezoelectric element 101 rapidly shrinks and displaces in the thickness direction, and the drive shaft 103 fixed to the piezoelectric element 101 also rapidly displaces in the return direction. . At this time, as shown in FIG. 3 (a3), the inertial force of the moving body 108 overcomes the frictional force with the drive shaft 103 to cause slipping, so that the moving body 108 substantially remains in that position. Do not move. As a result, the moving body 108 moves in the feeding direction by an amount corresponding to the difference in the amount of movement between expansion and contraction compared to the initial state shown in FIG. By repeating such expansion and contraction of the piezoelectric element 101, the moving body 108 is driven in the extending direction along the drive shaft 103.

  On the other hand, the moving body 108 is driven in the return direction on the principle opposite to that described above. That is, when a pulse voltage having a sawtooth waveform composed of a sudden rising portion and a gentle falling portion is applied to the piezoelectric element 101, the piezoelectric element 101 is rapidly expanded and displaced at the sudden rising portion of the pulse voltage. Accordingly, the drive shaft 103 fixed to the piezoelectric element 101 is also rapidly displaced in the feeding direction. At this time, the inertial force of the moving body 108 overcomes the frictional force with the drive shaft 103 to cause slipping, so that the moving body 108 remains substantially in that position and does not move.

  Subsequently, at the gently falling portion of the pulse voltage, the piezoelectric element 101 is gradually contracted and displaced, and accordingly, the drive shaft 103 fixed to the piezoelectric element 101 is gradually displaced in the return direction. At this time, the moving body 108 is displaced in the return direction together with the drive shaft 103. As a result, the moving body 108 moves in the return direction by the difference in the amount of movement between the extension and the contraction from the initial state. By repeating such expansion and contraction of the piezoelectric element 101, the moving body 108 is driven in the return direction along the drive shaft 103.

  As a moving body support member of the driving device 100 that generates a driving force through such friction, the following Patent Document 1 discloses one manufactured by orienting carbon fibers in the axial direction and hardening them with an epoxy resin. Has been. However, in this manufacturing method, the movable body support member often has a certain shape in the axial direction, and there is a problem that the degree of freedom in shape is small.

  Moreover, the following patent document 2 discloses that a ceramic hollow shaft is used as the movable body support member. However, since the moving body support member made of ceramic is heavier than the moving body support member made of the fiber reinforced resin composite, it is not preferable for efficient transmission of force from the piezoelectric element 101. In addition, there is a problem that it is expensive to finish the surface roughness of the movable body support member to a desired smoothness.

Japanese Patent No. 3180557 JP-A-10-337055

  Then, in view of the said problem, this invention makes it a subject to provide the drive device which has a mobile support member which is light, cheap, and has a large shape freedom degree.

In order to solve the above-described problems, the present invention provides an electromechanical conversion element that expands and contracts when a voltage is applied, and a movable body that is slidably supported and coupled to the electromechanical conversion element. A moving body support member that is displaced together with the conversion element, and a drive device that moves the moving body along the moving body support member by expansion and contraction of the electromechanical conversion element,
The material of the movable body support member is a fiber reinforced resin composite, and the synthetic resin material constituting the fiber reinforced resin composite is a liquid crystal polymer or polyphenylene sulfide.

  In the drive device of the present invention, the synthetic resin material constituting the fiber reinforced resin composite may be wholly aromatic polyester.

  In the driving device of the present invention, the reinforcing fiber included in the fiber reinforced resin composite may be carbon fiber, glass fiber, carbon whisker, or potassium titanate whisker.

  In the driving device of the present invention, the content of reinforcing fibers in the fiber-reinforced resin composite may be 10 to 50 volume percent.

  In the drive device of the present invention, the movable body support member may be a drive shaft that is partially hollow in the axial direction.

  In the drive device of the present invention, the movable body support member may be a drive shaft having portions having different diameters in the axial direction.

  Furthermore, in the drive device of the present invention, the movable body support member may be a drive shaft whose cross section perpendicular to the axial direction forms a polygon.

  According to the drive device of the present invention, the moving body support member is made of a fiber reinforced resin composite, and the synthetic resin material constituting the fiber reinforced resin composite is a liquid crystal polymer or polyphenylene sulfide. The support member can be manufactured by injection molding. As a result, the movable body support member can have a high degree of freedom in shape and can be manufactured at low cost. In addition, it is lighter than a ceramic moving body support member, so it can realize efficient transmission of force from the electromechanical transducer, and there is no secondary processing on a smooth surface suitable for sliding of the moving body. Is obtained.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
FIG. 4 is a side view including a partial cross section showing a schematic configuration of the driving apparatus 10 according to an embodiment of the present invention. The drive device 10 includes a fixed body 12, a piezoelectric element 14 that is an example of an electromechanical conversion element, a drive shaft (moving body support member) 16, and a moving body 18.

  The fixed body 12 is fixed to a base member (not shown) of the driving device 10. The piezoelectric element 14 expands and contracts in the axial direction when a pulse voltage is applied, and one end in the expansion / contraction direction is bonded and fixed to the fixed body 12. The drive shaft 16 has, for example, a cylindrical outer shape, and a hollow portion 17 is formed in an end portion thereof. The other end of the piezoelectric element 14 in the expansion / contraction direction is bonded and fixed to the drive shaft 16 while being inserted into the hollow portion 17 of the drive shaft 16. Thus, by inserting and fixing the piezoelectric element 14 in the drive shaft 16, there is an advantage that the thickness of the entire drive device 10 including the piezoelectric element 14 and the drive shaft 16 can be reduced.

  The drive shaft 16 is supported so as to be displaceable in the axial direction in a state where both ends of the drive shaft 16 pass through two support plates 20 fixed at predetermined intervals. A moving body 18 is supported on the drive shaft 16 with a predetermined frictional force. A lens frame (not shown) that supports an optical member such as a lens is connected to the moving body 18 so that the optical member is linearly driven by sliding the moving body 18 on the drive shaft 16 in the axial direction. It has become.

  The material of the drive shaft 16 in the drive device 10 of the present embodiment is a fiber reinforced resin composite, and the synthetic resin material constituting the fiber reinforced resin composite is a liquid crystal polymer (for example, liquid crystal polyester) or polyphenylene sulfide. In this way, the drive shaft 16 is made of a fiber reinforced resin composite, and the drive shaft 16 can be manufactured by injection molding by using a liquid crystal polymer or polyphenylene sulfide as the synthetic resin material constituting the fiber reinforced resin composite. become. As a result, the degree of freedom of the shape of the drive shaft 16 is increased, and the manufacturing cost can be reduced. Further, since it is lighter than a ceramic drive shaft, it can realize efficient transmission of force from the piezoelectric element 14 and obtain a smooth surface suitable for sliding of the moving body 18 without secondary processing. It is done.

  Commercially available polyphenylene sulfide includes Ryton from Chevron Phillips, DIC / PPS from Dainippon Ink Chemicals, Asahi PPS from Asahi Glass Matex, Fortron from Polyplastics, Sastil from Tosoh, Toray Torelina made by company, etc. can be used.

  Examples of the liquid crystal polymer include wholly aromatic or semi-aromatic polyesters, polyester imides, polyester amides, polyamide imides, polyester carbonates, poiazomethines, and the like, and wholly aromatic liquid crystal polyesters are particularly preferable. As constituent components of the liquid crystal polyester, aromatic dicarboxylic acid, aromatic hydroxycarboxylic acid compound, aromatic diol compound, aromatic dithiol, aromatic thiophenol, aromatic thiolcarboxylic acid compound, aromatic hydroxyamine, aromatic Examples thereof include diamine compounds or combinations thereof. Examples of commercially available aromatic polyesters include Vectra manufactured by Polyplastics, Zyder manufactured by Nippon Petrochemical Co., Sumika Super manufactured by Sumitomo Chemical Co., and Siberus manufactured by Toray.

  Carbon fiber, glass fiber, carbon whisker, or potassium titanate whisker can be used as the reinforcing fiber contained in the fiber reinforced resin composite. In this case, the reinforcing fiber content in the fiber-reinforced resin composite is preferably 10 to 50 volume percent. This is because if the reinforcing fiber content is lower than 10 volume percent, the desired strength of the drive shaft 16 cannot be obtained, while if the reinforcing fiber content is higher than 50 volume percent, injection molding becomes difficult.

  The operating principle of the drive device 10 having the above-described configuration is the same as that of the drive device 100 of the conventional example described above. Therefore, the description which overlaps here is abbreviate | omitted.

  The drive shaft 16 has a circular cross section with the same diameter in the cross section perpendicular to the axial direction, but the drive shaft 16 is formed of a fiber reinforced resin composite based on a liquid crystal polymer or polyphenylene sulfide. Therefore, the degree of freedom of the shape is large, and as shown in FIG. 5, it can be easily formed to have portions having different diameters at the axial end portions. Further, the drive shaft 16 may be formed such that a cross section perpendicular to the axial direction forms a polygon such as an octagon, a hexagon, or a quadrangle. If the drive shaft 16 is polygonal, the rotation of the movable body 18 around the drive shaft 16 can be prevented, so there is no need to separately provide a member for preventing the rotation of the movable body 18.

The side view of the drive device of a prior art example. The exploded perspective view and assembly drawing of the drive device of the prior art example containing a moving body. The figure for demonstrating the operating principle of a drive device. The side view including the partial cross section which shows the drive device of embodiment of this invention. The figure which shows the modification of a drive shaft.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Drive apparatus 12 ... Fixed body 14 ... Piezoelectric element (electromechanical conversion element)
16 ... Drive shaft (moving body support member)
18 ... moving body 20 ... support plate

Claims (7)

An electromechanical transducer that expands and contracts when a voltage is applied; and a movable body support member that supports the movable body so as to be slidable, and is coupled to the electromechanical transducer and displaced together with the electromechanical transducer. A driving device for moving the movable body along the movable body support member by expansion and contraction of the electromechanical conversion element,
The drive device characterized in that the moving body support member is made of a fiber reinforced resin composite, and the synthetic resin material constituting the fiber reinforced resin composite is a liquid crystal polymer or polyphenylene sulfide.   The drive device according to claim 1, wherein the synthetic resin material constituting the fiber reinforced resin composite is a wholly aromatic polyester.   3. The driving device according to claim 1, wherein the reinforcing fiber included in the fiber reinforced resin composite is carbon fiber, glass fiber, carbon whisker, or potassium titanate whisker.   The drive unit according to claim 3, wherein a content rate of the reinforcing fiber in the fiber reinforced resin composite is 10 to 50 volume percent.   The drive unit according to claim 1, wherein the movable body support member is a drive shaft partially hollow in the axial direction.   The drive device according to claim 1, wherein the movable body support member is a drive shaft having portions having different diameters in the axial direction.   The drive device according to claim 1, wherein the movable body support member is a drive shaft having a polygonal cross section perpendicular to the axial direction.

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