JP2008197220A - Lens barrel driving device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lens barrel driving device which is composed of an SIDM (Smooth Impact Drive Mechanism) frictionally engaging a vibration member and a moving member with each other even when an elastic member is not used. <P>SOLUTION: The lens barrel driving device is equipped with: an electric conversion element which is expanded and contracted by application of a voltage; the vibration member which is coupled with one end in the expanding and contracting directions of the electric conversion element; a lens barrel which holds a lens and is frictionally engaged with the vibration member, to be movable in the expanding and contracting directions of the electric conversion element; a holding and fixing member which is made of a magnetic material and holds and fixes the vibration member between the holding and fixing member and the lens barrel; and a magnet which is arranged in the lens barrel. The magnet attracts the holding and fixing member, so that the lens barrel and the vibration member are frictionally engaged with each other. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a drive device using an electrical conversion element such as a piezoelectric element.

  2. Description of the Related Art A driving device using an electric conversion element such as a piezoelectric element (piezo element) that expands and contracts by application of a voltage is known as SIDM (Smooth Impact Drive Mechanism).

  This SIDM is a small actuator mainly composed of an electric conversion element 1, a vibration member 2, a holding member 3 and a moving member 4 as shown in FIG.

  The electrical conversion element 1 is a piezoelectric element in which a large number of piezoelectric plates are stacked, and expands and contracts when a voltage is applied.

  The vibration member 2 is a rod-shaped member coupled to one end of the electric conversion element 1 in the expansion / contraction direction, and is made of a hard material with good slipperiness.

  The holding member 3 cantileverly holds the other end of the electric conversion element 1 in the expansion / contraction direction and is formed of a metal material having a mass.

  The moving member 4 is a member that moves in connection with an arbitrary member to be moved, and engages the vibration member 2 with a predetermined frictional force.

  An example of the moving member 4 will be described with reference to FIG. The lens barrel 61 holds the lens L. The vibrating member 2 is tightly attached by the cap 62 and the concave portion 61 a of the lens barrel 61, and a tension spring 63 is stretched between the cap 62 and the arm portion 61 c of the lens barrel 61. Accordingly, a predetermined frictional force is applied between the recess 61a and the vibration member 2, and the lens barrel 61 is frictionally engaged with the vibration member 2, and the lens is accompanied by vibration of the vibration member 2 according to the SIDM driving principle described later. The lens barrel 61 is driven in the direction perpendicular to the paper surface.

  In addition, a guide shaft 64 is arranged on the non-moving member (not shown) in parallel with the vibration member 2, and a bifurcated portion 61 b provided on the lens barrel 61 engages and slides on the guide shaft 64. This prevents the lens barrel 61 from rotating about the vibration member 2.

  With the configuration described above, for example, the focusing operation and the zooming operation can be performed by moving the lens L. It can also be used for aperture control and camera shake correction.

  A flexible printed circuit board 6 is bonded to the electrical conversion element 1 by a conductive adhesive or the like, and a pulse voltage having a sawtooth waveform as shown in FIG. 3 is continuously applied to the electrical conversion element 1 through the flexible printed circuit board 6. . As a result, the electrical conversion element 1 expands and contracts, and at the same time, the vibration member 2 vibrates in the axial direction. Then, at the gradual rise a of the pulse voltage, the electrical conversion element 1 expands relatively slowly. Therefore, the vibration member 2 moves in a direction away from the holding member 3 (A direction), and accordingly, the moving member 4 also moves in the same direction. On the other hand, at the rapid fall b of the pulse voltage, the electrical conversion element 1 rapidly contracts and returns to the initial length. At this time, the vibration member 2 also rapidly moves in the direction (B direction) toward the holding member 3, but the moving member 4 stays at that position due to inertia or moves slightly toward the holding member 3. Therefore, by continuously applying such a pulse voltage, the moving member 4 moves in the A direction little by little according to the number of pulses.

  Note that when the moving member 4 is moved in the B direction, the pulse voltage of the sawtooth waveform applied to the electrical conversion element 1 may be reversed so as to make a rapid rise and a gentle fall.

Since such SIDM has high accuracy and high responsiveness and operates quietly, it is used for small devices and is also disclosed in patent publications (see Patent Documents 1 and 2).
Japanese Patent No. 3141714 Japanese Patent Laid-Open No. 2002-119074

  As described above, when a lens is moved using SIDM, conventionally, an elastic member such as a tension spring that applies a frictional force between the vibrating member and the moving member is arranged in the lens barrel driving device. When the lens barrel driving device is further reduced in size, it is difficult to reduce the size of the elastic member and maintain the accuracy.

  The first invention has been made in view of such a problem, and proposes a lens barrel driving device made of SIDM capable of appropriately frictionally engaging a vibrating member and a moving member without using an elastic member. This is the first purpose.

  In addition, when driving a lens barrel that holds a lens by SIDM, in addition to a portion that frictionally engages the vibration member on the lens barrel, a guide portion such as a bifurcated portion provided on the lens barrel by providing a guide shaft So that the lens barrel does not rotate about the moving member. However, since the bifurcated portion slides with respect to the guide shaft, a predetermined gap is inevitably generated between them, and the lens barrel rotates in the range of the gap.

  The second invention has been made in view of such a problem, and comprises a SIDM in which the lens barrel does not rotate around the moving member even if there is a gap between the guide shaft and the guide portion. The second object is to propose a lens barrel driving device.

  Conventionally, an elastic member such as a tension spring that applies a frictional force between the vibrating member and the moving member is arranged in the lens barrel driving device. However, when trying to further reduce the size of the lens barrel driving device. This makes it difficult to reduce the size of the elastic member and maintain accuracy.

  The third invention has been made in view of such a problem, and proposes a lens barrel driving device made of SIDM capable of appropriately frictionally engaging a vibrating member and a moving member without using an elastic member. This is the third purpose.

The object is achieved by the invention described below.
1. An electrical conversion element that expands and contracts by application of voltage;
A vibration member coupled to one end of the electrical conversion element in the expansion and contraction direction;
A lens barrel that holds the lens, is frictionally engaged with the vibration member, and is movable in the expansion / contraction direction of the electrical conversion element;
A narrow member that is formed of a magnetic material and tightly contacts the vibration member with the lens barrel;
A magnet disposed on the lens barrel;
With
The lens barrel drive device according to claim 1, wherein the lens barrel and the vibration member are frictionally engaged by the magnet attracting the narrow member.
2. An electrical conversion element that expands and contracts by application of voltage;
A vibration member coupled to one end of the electrical conversion element in the expansion and contraction direction;
A lens barrel that holds the lens, is frictionally engaged with the vibration member, and is movable in the expansion / contraction direction of the electrical conversion element;
An elastic member for applying a frictional force between the vibration member and the lens barrel;
In a lens barrel driving device comprising:
A guide shaft that is formed of a magnetic material and is arranged in parallel with the expansion / contraction direction of the electrical conversion element to guide the lens barrel,
A magnet is disposed in the vicinity of the guide portion provided in the lens barrel to be engaged with the guide shaft,
The lens barrel driving device according to claim 1, wherein one side wall of the guide portion of the lens barrel comes into contact with the peripheral wall of the guide shaft by the magnetic force of the magnet.
3. An electrical conversion element that expands and contracts by application of voltage;
A vibrating member formed of a magnetic material and coupled to one end of the electric transducer in the expansion and contraction direction;
A lens barrel that holds the lens, is frictionally engaged with the vibration member, and is movable in the expansion / contraction direction of the electrical conversion element;
In a lens barrel driving device comprising:
A lens barrel driving device characterized in that a magnet is disposed on the lens barrel and the vibrating member is made of a magnetic material, whereby the lens barrel and the vibrating member are frictionally engaged by a magnetic force.
4). 4. The lens barrel driving device according to any one of 1 to 3, wherein a magnetic sensor arranged on a predetermined immovable member detects a magnetic force generated from the magnet.
5. 5. The lens barrel driving device according to 4, wherein the magnetic sensor is a Hall element or a magnetoresistive element.

  According to the lens barrel drive device of the first aspect, since an elastic member such as a tension spring for applying a frictional force between the vibrating member and the lens barrel is not necessary, a lens mirror having a smaller size and a lower price can be obtained. A cylinder drive device can be realized.

  According to the lens barrel drive device of claim 2, even if there is a gap between the guide portion provided on the lens barrel and the guide shaft for guiding the guide portion, one peripheral wall of the guide shaft Since the side wall of the guide portion of the lens barrel always comes into contact with the lens barrel, the lens barrel does not rotate around the moving member.

  In addition, according to the lens barrel drive device of the third aspect, since an elastic member such as a tension spring for applying a frictional force between the vibrating member and the lens barrel is not necessary, the lens barrel driving device is smaller and less expensive. A lens barrel driving device can be realized.

An embodiment of a lens barrel driving device of the present invention will be described in detail with reference to the drawings.
[First Embodiment]
A first embodiment of the lens barrel driving device of the present invention will be described in detail with reference to FIG.

  FIG. 4 corresponds to the moving member 4 in FIG. 1, and the actuator for moving the moving member is the aforementioned SIDM. Therefore, a duplicate description of the SIDM configuration and driving principle is omitted.

  In FIG. 4, the lens barrel 11 holds a lens L. Then, the SIDM vibration member 2 is tightly attached by a narrowing member 12 fixed to the lens barrel 11 and formed of a magnetic material and a concave portion 11 a of the lens barrel 11. A magnet 15 is disposed on the lens barrel 11. Therefore, since the narrow member 12 is attracted by the magnetic force of the magnet 15, a predetermined frictional force is applied between the vibration member 2 and the recess 11 a, and the lens barrel 11 is frictionally engaged with the vibration member 2. Therefore, the lens barrel 11 is driven in the direction perpendicular to the paper surface in accordance with the vibration of the vibration member 2 based on the above-described SIDM driving principle.

  Further, a guide shaft 14 is disposed in parallel with the vibration member 2 on a non-moving member (not shown), and a bifurcated portion 11 b provided on the lens barrel 11 engages and slides on the guide shaft 14. Thereby, the lens barrel 11 is prevented from rotating around the vibration member 2.

  Further, a hall element 16 that is a magnetic sensor is disposed on an immovable member in the vicinity of the magnet 15. Accordingly, when a voltage is applied to the two electrodes of the Hall element 16 to pass a current and the lens barrel 11 is driven and positioned in the vicinity of the Hall element 16, the other two electrodes of the Hall element 16 are driven by the magnetic force of the magnet 15. Voltage is generated. In this way, when the lens barrel 11 is driven to a predetermined position, the Hall element 16 detects it, so that the initial position when the lens L is moved and the target position after the lens L is moved. In addition, the lens L can be reliably stopped. Therefore, the lens L can be used for focusing operation, zooming operation, and the like.

  In the lens barrel driving apparatus, the vibration member 2 and the lens barrel 11 are made of a metal or resin that is not a magnetic material.

  SIDM is a very small actuator with a maximum outer dimension of, for example, a shaft diameter of 2.5 mm and a total length of 8.9 mm. It is a sensor. In this way, since the ultra-small Hall element is used to detect the stop position of the lens L driven by the ultra-small SIDM, the entire lens barrel driving device can be made compact.

  In some cases, a magnetoresistive element may be used as the magnetic sensor instead of the Hall element.

  With the above configuration, the vibrating member 2 is frictionally engaged with the lens barrel 11 by the magnetic force of the magnet 15, so that a spring member as in the prior art is unnecessary and the configuration is simplified. Furthermore, the position of the lens barrel 11 can be detected by detecting the magnetic force of the magnet 15.

Further, if the narrow member 12 is formed long in the axial direction of the vibration member 2 and is formed long so as to cover the movement range of the lens barrel 11, the narrow member 12 is not fixed to the lens barrel 11. It is fixed to the vibration member 2.
[Second Embodiment]
A second embodiment of the lens barrel driving device of the present invention will be described in detail with reference to FIG.

  FIG. 5 corresponds to the moving member 4 in FIG. 1, and the actuator for moving the moving member is the aforementioned SIDM. Therefore, a duplicate description of the SIDM configuration and driving principle is omitted.

  In FIG. 5, the lens barrel 21 holds the lens L. The SIDM vibrating member 2 is tightly attached by the cap 22 and the concave portion 21a of the lens barrel 21, and a tension spring 23 (elastic member) is stretched between the cap 22 and the arm portion 21c of the lens barrel 21. Has been. Therefore, a predetermined frictional force is applied between the vibration member 2 and the recess 21a, and the lens barrel 21 is frictionally engaged with the vibration member 2, and the lens is accompanied by the vibration of the vibration member 2 according to the above-described SIDM driving principle. The lens barrel 21 is driven in the direction perpendicular to the paper surface.

  In addition, a guide shaft 24 is disposed on the non-moving member (not shown) in parallel with the vibration member 2, and a bifurcated portion 21 b (guide portion) provided on the lens barrel 21 engages and slides on the guide shaft 24. This prevents the lens barrel 21 from rotating about the vibration member 2.

  However, in order for the bifurcated portion 21b to slide with respect to the guide shaft 24, the inner dimension of the bifurcated portion 21b needs to be larger than the outer diameter of the guide shaft 24, and the lens barrel 21 vibrates by this difference. A play centering on the member 2 occurs.

  Therefore, the guide shaft 24 is formed of a magnetic material such as iron, and the magnet 25 is disposed on the left side of the bifurcated portion 21b. As a result, the lens barrel 21 is slightly rotated counterclockwise by the magnetic force of the magnet 25, and the left side wall (one side wall) of the bifurcated portion 21 b always comes into sliding contact with the peripheral wall of the guide shaft 24. The backlash is eliminated.

  Even if the magnet 25 is arranged on the right side of the bifurcated portion 21b, the same effect can be obtained.

  In addition, a Hall element 26 that is a magnetic sensor is disposed on an immovable member in the vicinity of the magnet 25. Therefore, since the Hall element 26 detects the magnetic force of the magnet 25 when the lens barrel 21 is driven to a predetermined position, the initial position when the lens L is moved and the purpose after the lens L is moved. The lens L can be stopped at the position. Therefore, the lens L can be used for focusing on the imaging surface, zooming operation, and the like.

In some cases, a magnetoresistive element may be used as the magnetic sensor instead of the Hall element.
[Third Embodiment]
A third embodiment of the lens barrel driving device of the present invention will be described in detail with reference to FIG.

  FIG. 6 corresponds to the moving member 4 in FIG. 1, and the actuator for moving the moving member is the aforementioned SIDM. Therefore, a duplicate description of the SIDM configuration and driving principle is omitted.

  In FIG. 6, the lens barrel 31 holds the lens L. A magnet 35 is disposed on the lens barrel 31. Since the lens barrel 31 is made of a non-magnetic resin or the like, and the SIDM vibrating member 2 is made of a magnetic material such as iron, the vibration member 2 and the recess 31a of the lens barrel 31 are caused by a magnetic force. A predetermined frictional force is applied between the lens barrel 31 and the vibration member 2, and the lens barrel 31 is driven in the direction perpendicular to the paper surface in accordance with the vibration of the vibration member 2 according to the driving principle of the SIDM. The

  Therefore, in the present embodiment, the narrowing member 12 in the first embodiment, the cap 22 and the tension spring 23 in the second embodiment are not necessary and are simplified. Therefore, the lens barrel driving device can be made smaller and the cost can be reduced.

  In addition, a guide shaft 34 is disposed in parallel with the vibration member 2 on a non-moving member (not shown), and a bifurcated portion 31 b provided on the lens barrel 31 engages and slides on the guide shaft 34. This prevents the lens barrel 31 from rotating about the vibration member 2.

  In addition, a Hall element 36 that is a magnetic sensor is disposed on an immovable member in the vicinity of the magnet 35. Accordingly, since the Hall element 36 detects the magnetic force of the magnet 35 when the lens barrel 31 is driven to a predetermined position, the initial position when the lens L is moved and the purpose after the lens L is moved. The lens L can be stopped at the position. Therefore, the lens L can be used for focusing on the imaging surface, zooming operation, and the like.

  In some cases, a magnetoresistive element may be used as the magnetic sensor instead of the Hall element.

It is a block diagram of SIDM. It is an example of a moving member. It is a figure explaining the working principle of SIDM. It is sectional drawing of 1st Embodiment of a lens barrel drive device. It is sectional drawing of 2nd Embodiment of a lens barrel drive device. It is sectional drawing of 3rd Embodiment of a lens barrel drive device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electric conversion element 2 Vibrating member 3 Holding member 4 Moving member 11, 21, 31, 61 Lens barrel 11b, 21b, 31b, 61b Forked part 12 Narrow member 22, 62 Cap 23, 63 Tension spring 14, 24, 34 , 64 Guide shaft 15, 25, 35 Magnet 16, 26.36 Hall element L Lens

Claims (5)

An electrical conversion element that expands and contracts by application of voltage;
A vibration member coupled to one end of the electrical conversion element in the expansion and contraction direction;
A lens barrel that holds the lens, is frictionally engaged with the vibration member, and is movable in the expansion / contraction direction of the electrical conversion element;
A narrow member that is formed of a magnetic material and tightly contacts the vibration member with the lens barrel;
A magnet disposed on the lens barrel;
With
The lens barrel driving device, wherein the lens barrel and the vibrating member are frictionally engaged by the magnet attracting the narrow member. An electrical conversion element that expands and contracts by application of voltage;
A vibration member coupled to one end of the electrical conversion element in the expansion and contraction direction;
A lens barrel that holds the lens, is frictionally engaged with the vibration member, and is movable in the expansion / contraction direction of the electrical conversion element;
An elastic member for applying a frictional force between the vibration member and the lens barrel;
In a lens barrel drive device comprising:
A guide shaft that is formed of a magnetic material and is arranged in parallel with the expansion / contraction direction of the electrical conversion element to guide the lens barrel;
A magnet is disposed in the vicinity of the guide portion provided in the lens barrel to be engaged with the guide shaft,
The lens barrel drive device according to claim 1, wherein one side wall of the guide portion of the lens barrel comes into contact with the peripheral wall of the guide shaft by the magnetic force of the magnet. An electrical conversion element that expands and contracts by application of voltage;
A vibrating member formed of a magnetic material and coupled to one end of the electric transducer in the expansion and contraction direction;
A lens barrel that holds the lens, is frictionally engaged with the vibration member, and is movable in the expansion / contraction direction of the electrical conversion element;
In a lens barrel drive device comprising:
A lens barrel driving device characterized in that a magnet is disposed on the lens barrel and the vibrating member is formed of a magnetic material, whereby the lens barrel and the vibrating member are frictionally engaged by a magnetic force. The lens barrel driving device according to claim 1, wherein a magnetic sensor disposed on a predetermined immovable member detects a magnetic force generated from the magnet. The lens barrel driving apparatus according to claim 4, wherein the magnetic sensor is a Hall element or a magnetoresistive element.

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