JP5151199B2 - Drive device using electromechanical transducer - Google Patents

Description

  The present invention relates to a drive device using an electromechanical transducer that can linearly displace a moving body by vibration in the longitudinal direction of a drive shaft, such as a smooth impact drive mechanism (SIDM).

  Various actuators are used in the optical axis alignment mechanism of the coupling lens with the waveguide in the optical communication field, the zoom lens movement mechanism and the focus mechanism in the camera field, the tracking mechanism and the focus mechanism of the pickup lens in the optical disk field, etc. .

  In particular, in the optical axis adjustment of the waveguide and the coupling lens, high positioning accuracy of about 10 nm to 50 nm is required, and the lens driving mechanism needs to be housed in a package as small as possible. Therefore, a robust and short drive mechanism is required.

JP 7-298656 A JP-A-8-149860 JP 2002-51576 A JP 2002-95274 A JP 2002-300789 A JP 2003-309985 A

  In a conventional drive mechanism, both ends of the elongated drive shaft are held, and a housing for holding a piezoelectric element connected to one end of the drive shaft is employed (Patent Documents 1 to 4 and the like), or one end of the drive shaft is used. A piezoelectric element is mounted, and the other end of the drive shaft is fixed to the base member (Patent Document 5, etc.), or the piezoelectric element is fixed to the base member, and the drive shaft is press-fitted into the piezoelectric element (Patent Document) 6 etc.).

  Therefore, the total length of the drive mechanism is the length L1 of the piezoelectric element, the length L2 of the drive shaft corresponding to the stroke of the moving body, the length L3 necessary for fixing the drive shaft or the piezoelectric element, and an adhesive. If it is, the total length L4 of the adhesive residue is obtained.

  Since the lengths L1 and L2 are determined based on the specifications of the drive mechanism, there is little room for selection. However, the lengths L3 and L4 hinder the shortening of the drive mechanism, and there is room for improvement in structure.

  An object of the present invention is to provide a drive device capable of shortening the entire drive mechanism while firmly holding the drive shaft and the electromechanical conversion element.

In order to achieve the above object, a drive device according to the present invention includes a base member,
A drive shaft;
A moving body frictionally held on the drive shaft;
An electromechanical transducer for applying longitudinal vibration to the drive shaft;
A holding member for holding the drive shaft and the joint portion of the electromechanical transducer ,
The holding member is fixed to the base member .

  In the present invention, it is preferable that the joint surface between the drive shaft and the electromechanical conversion element is located within the range of the contact region between the holding member, the drive shaft, and the electromechanical conversion element.

  In the present invention, the drive shaft, the electromechanical conversion element, and the holding member are preferably fixed to each other using an adhesive.

  In the present invention, it is preferable that a reinforcing adhesive bonded to the surface of the holding member is provided on the side surface of the electromechanical conversion element.

According to the present invention, the drive shaft and the electromechanical conversion element can be firmly held and the holding member is fixed to the base member by arranging the holding member for holding the joint portion of the drive shaft and the electromechanical conversion element. By doing so, the length required for fixing the drive shaft or the piezoelectric element as in the prior art can be reduced, so that the drive device can be shortened.

  1A and 1B show an example of a drive device according to an embodiment of the present invention. FIG. 1A is a front view, FIG. 1B is a left side view, and FIG. 1C is a right side view. The drive device includes an electromechanical conversion element 10, a drive shaft 20, a holding member 30 that holds these, a moving body 40 that is frictionally held on the drive shaft 20, and the like.

  The drive shaft 20 is formed of, for example, a material such as metal, ceramic, glass, or carbon fiber composite, and has a uniform cross section in the longitudinal direction, for example, a columnar shape or a tubular shape. 4 illustrates a quadrangular prism shape having a cross section.

  The electromechanical transducer 10 is composed of a piezo element, a magnetostrictive element, or the like, and is disposed so as to contact the end of the drive shaft 20 and has a function of applying longitudinal vibration to the drive shaft 20. The electromechanical transducer 10 is supplied with a drive signal having a frequency of 20 kHz to 800 kHz via a pair of lead wires 18 and 19 from a drive circuit (not shown).

  The joint surfaces 15 and 25 of the drive shaft 20 and the electromechanical transducer 10 are formed flat so that vibrations from the electromechanical transducer 10 can be efficiently transmitted. It is preferable that the shapes and dimensions of the joint surfaces 15 and 25 are the same as each other, and here, they are formed to be squares having the same dimensions.

  The holding member 30 is formed of a material such as metal, ceramic, glass, or carbon fiber composite, for example, and has a role of holding a joint portion between the drive shaft 20 and the electromechanical transducer 10, and a part of the holding member 30 is It is fixed to a housing (not shown).

  The holding member 30 is formed with a through hole having a shape substantially coinciding with the joint surfaces 15 and 25 of the drive shaft 20 and the electromechanical transducer 10, and the drive shaft 20 and the electromechanical transducer 10 are inserted into the through hole. Inserted.

  At this time, the joint surfaces 15 and 25 of the drive shaft 20 and the electromechanical conversion element 10 are within the thickness range of the holding member 30, that is, the range of the contact region of the holding member 30, the drive shaft 20 and the electromechanical conversion element 10. It is preferable to be located within. Thereby, since the drive shaft 20 and the electromechanical transducer 10 are each attached to the holding member 30 in a cantilever structure, it is possible to realize a firm holding.

  Adhesion, fitting, press-fitting, welding, welding, soldering, and the like can be adopted as a method for fixing the drive shaft 20, the electromechanical transducer 10 and the holding member 30, but an adhesive is used in that the three members can be firmly fixed. It is preferable to use it. As the adhesive, for example, an epoxy adhesive, an acrylic adhesive, an impact resistant cyanoacrylate adhesive, or the like can be used.

  The adhesive is between the joint surface 15 of the drive shaft 20 and the joint surface 25 of the electromechanical conversion element 10, between the side surface of the drive shaft 20 and the inner surface of the through hole of the holding member 30, and the side surface of the electromechanical conversion element 10. It is preferable to apply between the inner surface of the holding member 30 and the inner surface of the through hole.

  The moving body 40 includes a rectangular tube-shaped housing, a sliding plate 41 provided inside the housing and abutting against a side surface of the drive shaft 20, and a sliding plate 41 interposed between the housing and the sliding plate 41. A spring member 42 for pressing toward the drive shaft 20 is formed.

  The housing of the moving body 40 is made of a material such as metal or FRP, and the sliding plate 41 is made of a material such as metal, ceramic, glass, or carbon.

  Here, as shown in FIG. 1C, the two sliding plates 41 and the two spring members 42 are disposed so as to contact two adjacent side surfaces of the drive shaft 20, and the remaining side surfaces are arranged. The housing of the moving body 40 is in direct contact.

  Next, the operation of the drive device will be described. When the electromechanical transducer 10 is not operating, the moving body 40 is stationary due to friction with the drive shaft 20. The holding force of the moving body 40 is determined by the friction coefficient between the sliding plate 41 and the drive shaft 20, the friction coefficient between the housing and the drive shaft 20, the pressing force of the spring member 42, and the like.

  When the electromechanical transducer 10 operates, vibration suitable for driving such as a sawtooth waveform displaced in the longitudinal direction is applied to the drive shaft 20. At this time, when the displacement speed is different between the rising section and the falling section of the drive waveform, and the displacement speed is large, the moving body 40 is stationary by its own inertia. On the other hand, when the displacement speed is small, the moving body 40 is It moves following the displacement.

  For example, in the case of sawtooth vibration in which the direction from the electromechanical transducer 10 toward the tip of the drive shaft 20 is the forward direction and the forward displacement speed is small and the reverse displacement speed is large, the moving body 40 accumulates in the forward direction. Move on. On the other hand, in the case of sawtooth vibration having a large forward displacement speed and a small reverse displacement speed, the moving body 40 moves cumulatively in the reverse direction. By controlling the sawtooth waveform for driving the electromechanical transducer 10 in this way, the moving direction of the moving body 40 can be controlled, and further, the moving body can be controlled by controlling the application time (number of applied pulses) of the sawtooth waveform. The amount of movement of 40 can be controlled.

  FIG. 2 is a front view showing a driving apparatus according to another embodiment of the present invention. In the drive device shown in FIG. 1, a reinforcing adhesive 50 bonded to the surface of the holding member 30 is added to the side surface of the electromechanical conversion element 10.

  The holding member 30 has a surface on the electromechanical conversion element 10 side and a surface on the drive shaft 20 side. It is preferable that the surface on the drive shaft 20 side does not limit the moving stroke of the moving body 40. On the other hand, the surface on the electromechanical conversion element 10 side is preferably provided with a reinforcing adhesive 50 that joins the holding member 30 and the electromechanical conversion element 10, thereby further improving the fixing strength of the electromechanical conversion element 10. Can do.

  FIG. 3 is a configuration diagram illustrating an example in which the above-described driving device is mounted on a lens unit. The electromechanical conversion element 10 and the drive shaft 20 are cantilevered by a holding member 30 at a joint portion between them. A movable body 40 that houses a lens 60 is mounted on the drive shaft 20.

  The lower part of the holding member 30 is fixed to the unit base 71. Unit walls 72 and 73 are erected on the unit base 71, and a unit cover 74 is placed thereon.

  As specific dimension examples, the electromechanical transducer 10 has a width of 0.5 to 3 mm, a length of 0.5 to 3 mm, a drive shaft 20 having a width of 0.5 to 3 mm, and a length of 1. The total length of the drive mechanism is 2 to 6 mm, and the moving stroke of the moving body 40 is 0.1 to 1 mm.

  By adopting such a cantilever support structure with the holding member 30, the support mechanism at the distal end portion of the electromechanical transducer 10 or the distal end portion of the drive shaft 20 can be omitted, so that the entire drive mechanism can be shortened.

  INDUSTRIAL APPLICABILITY The present invention is extremely useful in that a drive device can be realized in which the entire drive mechanism is shortened while firmly holding the drive shaft and the electromechanical conversion element.

FIG. 1A is a front view, FIG. 1B is a left side view, and FIG. 1C is a right side view, illustrating an example of a drive device according to an embodiment of the present invention. It is a front view which shows the drive device which concerns on other embodiment of this invention. It is a block diagram which shows the example which mounted the drive device mentioned above in the lens unit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Electromechanical conversion element 15, 25 Joint surface 18, 19 Lead wire 20 Drive shaft 30 Holding member 40 Moving body 41 Sliding plate 42 Spring member 50 Reinforcement adhesive 60 Lens

Claims (4)

A base member;
A drive shaft;
A moving body frictionally held on the drive shaft;
An electromechanical transducer for applying longitudinal vibration to the drive shaft;
A holding member for holding the drive shaft and a joint portion of the electromechanical transducer ,
The driving device using an electromechanical transducer, wherein the holding member is fixed to the base member .   2. The electricity according to claim 1, wherein a joint surface between the drive shaft and the electromechanical transducer is located within a contact area of the holding member, the drive shaft, and the electromechanical transducer. A drive device using a mechanical conversion element.   The drive device using an electromechanical transducer according to claim 1 or 2, wherein the drive shaft, the electromechanical transducer and the holding member are fixed to each other using an adhesive.   The drive device using an electromechanical transducer according to claim 3, wherein a reinforcing adhesive bonded to the surface of the holding member is provided on a side surface of the electromechanical transducer.

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