JP2010284056A - Oscillating drive device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an oscillating drive device that prevents the increase of a starting voltage, while resin-molding a frictional engagement member. <P>SOLUTION: The oscillating drive device 1 includes a drive member 4 reciprocated by an electromechanical transducer 3, and the frictional engagement member 5 frictionally engaged with the drive member 4. The frictional engagement member 5 contains a receiving member 6 and a pressing member 7 for sandwiching the drive member 4. The receiving member 6 is resin-molded. The surface roughness of a sliding face, which abuts against the drive member 4 on the receiving member 6, is set to 0.9 μm or larger in center line average roughness. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a vibration type driving device.

  There is provided a vibration type driving device in which an axial drive member is reciprocally displaced in an axial direction asymmetrically by an electromechanical conversion element such as a piezoelectric element, and a friction engagement member frictionally engaged with the drive member is slidably displaced with respect to the drive member. It is known.

  In the conventional vibration type drive device, in order to stabilize the friction between the drive member and the friction engagement member, it is important to make the sliding surfaces of the drive member and the friction engagement member as hard and smooth as possible. ing. For example, in Patent Document 1, in order to make the driving speed of the vibration type driving device constant, the surface roughness of the driving member and the friction engagement member should be Ra (center line average roughness) 0.8 μm or less. Are listed.

  For this reason, in the conventional vibration type drive device, a material obtained by solidifying carbon fiber with a resin is used for the drive member, and a resin in which a metal part is inserted on the sliding surface is often used for the friction engagement member. However, if a metal part is used for the friction engagement member, the production cost is increased.

  Patent Document 2 describes that the friction engagement member is formed of a liquid crystal polymer reinforced with carbon fiber. Patent Document 3 describes that a moving body that is formed integrally with a ball frame that holds an optical member and that frictionally engages with a driving member is formed of fiber-reinforced polyphenylene sulfide. However, even if the fibers are reinforced, thermoplastic resins (engineering plastics) such as liquid crystal polymers and polyphenylene sulfide have a problem that the starting voltage of the vibration type drive device becomes high because the elastic modulus is lower than that of metal. It was.

JP 2005-88687 A JP 2006-304529 A JP 2007-121679 A

  In view of the above problems, an object of the present invention is to provide a vibration type driving device in which a starting voltage is not increased while a friction engagement member is formed of resin.

In order to solve the above problems, a vibration type driving apparatus according to the present invention includes a driving member that is reciprocally displaced by an electromechanical transducer, and a friction engagement member that frictionally engages the driving member.
In the vibration-type driving device, the friction engagement member includes a receiving member and a pressing member that sandwich the driving member. The receiving member is made of resin and has a rough surface on a sliding surface that contacts the driving member. The center line average roughness is 0.9 μm or more.

  According to this configuration, the starting voltage can be made lower than when the sliding surface of the friction engagement member is formed of a smooth resin, and a sufficient driving speed can be obtained. Moreover, since the starting voltage is low, it is strong against the sticking of the friction engagement member.

  In the vibration type driving device of the present invention, it is preferable that the surface roughness of the sliding surface of the receiving member is a center line average roughness of 4.0 μm or less.

  If the surface roughness is excessively increased, the friction on the sliding surface increases, and on the contrary, the starting voltage increases and the variation in the driving speed between the solids increases. If the center line average roughness is 4.0 μm or less, these problems can be prevented.

  In the vibration type driving device of the present invention, the receiving member may be formed of polyphenylene sulfide, polycarbonate, or liquid crystal polymer.

  According to this configuration, since the receiving member can be formed by injection molding, the vibration type driving device can be provided at low cost.

  In the vibration type driving device of the present invention, a lubricant may be applied to the sliding surface.

  According to this configuration, the frictional force between the drive member and the friction engagement member is stabilized, so that the drive speed is constant.

  In the driving device of the present invention, the receiving member constituting the friction engagement member is formed of resin, and the surface roughness of the sliding surface of the receiving member is set to a center line average roughness of 0.9 μm or more. While using the engaging member, a sufficient driving speed can be secured and the starting voltage can be kept low.

It is a figure of the vibration type drive device of one embodiment of the present invention.

  Embodiments of the present invention will now be described with reference to the drawings. FIG. 1A is a side view of the vibration type driving apparatus 1 according to one embodiment of the present invention, and FIG. 1B is a front view of the vibration type driving apparatus 1.

  The vibration type driving device 1 includes a piezoelectric element (electromechanical conversion element) 3 having one end fixed to a weight 2 fixed to a housing, and a columnar driving member 4 having one end fixed to the other end of the piezoelectric element 3. And a friction engagement member 5 engaged with the drive member 4 by friction force.

  The drive member 4 is formed by solidifying carbon fiber with a resin. The friction engagement member 5 includes a receiving member 6, a pressing member 7, and a plate spring 8 that presses the pressing member 7 toward the receiving member 6, and the driving member 4 is interposed between the receiving member 6 and the pressing member 7. Is sandwiched. The receiving member 6 is provided on a driving object of the vibration type driving device 1, for example, a ball frame holding a lens, and is formed by injection molding a thermoplastic. The receiving member 6 may be individually injection-molded and then attached to the driving object with an adhesive or a screw. However, when the driving object is a resin product, the receiving member and the driving object are The integral injection molding is preferable in terms of production efficiency and assembly accuracy. The receiving member 6 has a V-shaped cross section perpendicular to the central axis of the driving member 4, and two inclined surfaces constituting the V-shape function as sliding surfaces that slide on the outer peripheral surface of the driving member. Random irregularities are formed on the two sliding surfaces of the receiving member 6 by, for example, sandblasting so that the surface roughness is 0.9 μm or more and 4.0 μm or less in terms of centerline average roughness. The pressing member 7 is formed by machining a metal (for example, stainless steel). A lubricant (for example, FT210 manufactured by Harves) is applied to the sliding surface of the receiving member 6.

  The vibration type driving device 1 applies a rectangular wave voltage with a duty ratio of 0.3 or 0.7 to the piezoelectric element 3 to cause the driving member 4 to reciprocate asymmetrically in the axial direction, thereby causing the friction engagement member 5 to move. A sliding displacement is performed on the driving member 4.

  In the vibration type driving device 1, since the unevenness is formed on the sliding surface of the receiving member 6 of the friction engagement member 5, the friction state between the drive member 4 and the friction engagement member 5 is stabilized, and the friction engagement is performed. The acceleration of the drive member 4 necessary for sliding the member 5 is not increased. Thereby, the voltage required for starting the vibration type drive apparatus 1 does not become high, and sufficient drive speed is obtained. Further, in the vibration type driving device 1, since the lubricant stays in the unevenness, the friction state between the driving member 4 and the friction engaging member 5 is further stabilized, and the friction engaging member 5 is driven by the driving member 4. The phenomenon of sticking to is difficult to occur.

  An embodiment of the vibration type driving device 1 will be described. As a first embodiment, the weight 2 is made of tungsten having a diameter of 1.8 mm and a thickness of 0.3 mm, the piezoelectric element 3 is □ 0.9 mm, the length is 1.2 mm, the drive member 4 is 0.8 mm in diameter, It formed in the column shape of length 2.5mm. The receiving member 6 is formed by injection molding of potassium titanate fiber-blended polyphenylene sulfide (Poticon AM2 manufactured by Otsuka Chemical Co., Ltd.) and forming the ones having different surface roughness (Ra: center line average roughness) by sandblasting. did.

  Table 1 shows the starting voltage of the vibration type driving device 1 of the first embodiment. Since the vibration type driving device 1 is assumed to be driven by a drive circuit with a power supply voltage of 3V, the evaluation is ideal if the starting voltage is 2V or less, and 2.3V or less. It was judged to be a practical evaluation Δ, and when it exceeded 2.3 V, it was judged to be a practical evaluation ×.

  As a second embodiment, the weight 2 is made of tungsten having a diameter of 1.8 mm and a thickness of 0.3 mm, the piezoelectric element 3 is □ 0.9 mm, the length is 1.2 mm, the drive member 4 is 0.8 mm in diameter, It formed in the column shape of length 2.5mm. The receiving member 6 was formed by injection molding liquid crystal plastic (UENO LCP 2030G-M, manufactured by Ueno Pharmaceutical Co., Ltd.) and changing the surface roughness (Ra: center line average roughness) of the sliding surface. Table 2 shows the starting voltage of the vibration type driving device 1 of the second embodiment.

  As a third embodiment, the weight 2 is formed of tungsten having a diameter of 1.8 mm and a thickness of 0.3 mm, the piezoelectric element 3 is □ 0.9 mm, the length is 1.2 mm, the drive member 4 is 0.8 mm in diameter, It formed in the column shape of length 2.5mm. The receiving member 6 was formed by injection molding liquid crystal plastic (manufactured by Nippon Oil Corporation, Zider CM-321B) and changing the surface roughness (Ra: center line average roughness) of the sliding surface. Table 3 shows the starting voltage of the vibration type driving device 1 of the third embodiment.

  As a fourth embodiment, the weight 2 is formed of tungsten having a diameter of 1.8 mm and a thickness of 0.3 mm, the piezoelectric element 3 is □ 0.9 mm, the length is 1.5 mm, the drive member 4 is 0.8 mm in diameter, It formed in the column shape of length 2.5mm. The receiving member 6 was formed by injection-molding engineering plastic and changing the surface roughness (Ra: centerline average roughness) of the sliding surface. Table 4 shows the starting voltage of the vibration type driving apparatus 1 of the fourth embodiment.

  As described above, although there are some variations depending on the embodiment, it is generally practical if the surface roughness of the sliding surface of the receiving member 6 of the friction engagement member 5 is 0.4 μm or more and 4.0 μm or less. A good starting voltage could be achieved.

  In addition to the resins of the above-described embodiments, examples of applicable liquid crystal plastic materials include Vectra 230 manufactured by Polyplastics, Poticon VT96HB manufactured by Otsuka Chemical Co., and Xider-XW-321 manufactured by Nippon Oil Corporation. Further, the friction engagement member 5 may be formed of polycarbonate.

  Further, in the above embodiment, the metal pressing member 7 is used, but the pressing member 7 is formed by injection molding of a thermoplastic plastic and is in contact with the driving member 4, similarly to the receiving member 6. The moving surface may be processed by sandblasting or the like so that the surface roughness is 0.4 μm or more and 4.0 μm.

  In the above embodiment, the friction engagement member 5 is constituted by the receiving member 6, the pressing member 7, and the leaf spring 8, but the present invention is not limited to this. For example, various configurations of the frictional engagement member are possible, such as a frictional engagement member configured with two points of a receiving member and a leaf spring, and a three-point configuration of a receiving member, a leaf spring, and a coil spring. However, in any configuration, since the stability of sliding between the receiving member provided on the driving object and the driving member is important, the surface roughness of the sliding surface of the receiving member is important.

  In the above embodiment, a piezoelectric element is used as the electromechanical conversion element. However, the electromechanical conversion element is not limited to this as long as it has a characteristic of expanding and contracting according to the drive voltage. A strain element or the like can also be used. As a material of the piezoelectric element, a known material such as barium titanate or lead zirconate titanate (PZT) may be appropriately selected and used.

DESCRIPTION OF SYMBOLS 1 ... Vibration type drive device 2 ... Weight 3 ... Piezoelectric element (electromechanical conversion element)
4 ... Driving member 5 ... Friction engagement member 6 ... Receiving member 7 ... Holding member

Claims (4)

A drive member that is reciprocally displaced by an electromechanical transducer;
A friction engagement member that frictionally engages the drive member;
The friction engagement member may be a vibration type drive device including a receiving member and a pressing member that sandwich the drive member.
The receiving member is made of resin, and the surface roughness of the sliding surface that comes into contact with the driving member is a center line average roughness of 0.9 μm or more.   2. The vibration type driving device according to claim 1, wherein a surface roughness of the sliding surface of the receiving member is a center line average roughness of 4.0 μm or less.   3. The vibration type driving device according to claim 1, wherein the receiving member is made of polyphenylene sulfide, polycarbonate, or liquid crystal polymer.   4. The vibration type driving device according to claim 1, wherein a lubricant is applied to the sliding surface.

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