JP2011095434A - Optical member driving device, optical member lens barrel, and imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical member driving device superior in position detecting accuracy. <P>SOLUTION: The optical member driving device includes: a magnet 33a attached to a lens holder 22; a magnetic substance 31a having a cross section formed of a vertex and first and the second piece parts extending from the vertex respectively and having nearly the same shape each other, and having an opening formed between the first and the second piece parts; a piezoelectric element 32a vibrating the magnetic substance 31a, whereby the magnet 33a is slidably driven to move the lens holder 22; and a magnetic sensor 34a for detecting a moving position of the magnet 33a. The piezoelectric element 32a is driven in a state where the magnet 33a is coupled with the first and the second piece parts of the magnetic substance 31a from the opening side. The magnet 33a is magnetized in a direction orthogonal to a magnetization line that is a line linking the vertex of the magnetic substance 31a with a center of the cross section of the magnet 33a. The magnetic sensor 34a is arranged in a direction other than on the magnetization line in sectional view of the magnetic substance 31a. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an optical member driving apparatus, an optical member barrel, and an imaging apparatus that move an optical member holder by sliding a magnet to vibrate a magnetic body with a piezoelectric element.

  2. Description of the Related Art Conventionally, an imaging apparatus such as a digital still camera or a digital video camera forms a subject image using an imaging optical lens (optical member). An image is formed by an imaging element such as a CCD (Charge Coupled Device Image Sensor) image sensor or a CMOS (Complementary Metal Oxide Semiconductor) image sensor disposed at the rear of the optical lens.

  Here, a digital still camera and a digital video camera equipped with an optical shake correction mechanism are known in order to prevent deterioration in quality of a captured image due to shake of the imaging apparatus. Specifically, the shake is corrected by moving the optical lens in two directions orthogonal to the optical axis direction. As an optical member driving device for moving the optical lens, for example, a relatively large number of techniques using an electromagnetic driving type actuator including a coil and a magnet are employed.

A technique using a piezoelectric element as an actuator for moving an optical lens is also disclosed. For example, there is a technique for moving a shake correction lens by a bimorph type piezoelectric element. There is also a technique in which piezoelectric ceramic plates are stacked in order to increase the displacement of the piezoelectric element.
Furthermore, the driving force generated by the piezoelectric element by utilizing the magnetic attraction force acting between the magnet attached to the piezoelectric element and the magnetic body attached to the movable part of the optical member holder that holds the optical lens. There is also a technology that makes it possible to transmit the light to the optical member holder more stably.

JP 2000-194026 A Japanese Patent No. 27968831

  However, since the conventional lens driving technique using a piezoelectric element does not have a position detecting means for an optical lens that is moved by the piezoelectric element, as in the techniques of Patent Document 1 and Patent Document 2 described above, the position detection accuracy is high. There is a problem of being bad.

  Therefore, the problem to be solved by the present invention is to provide an optical member driving device excellent in position detection accuracy. Another object of the present invention is to provide a small and low-power optical member driving device having excellent driving characteristics.

The present invention solves the above-described problems by the following means.
According to the first aspect of the present invention, there is provided an optical member holder for holding an optical member, a magnet attached to the optical member holder, and a cross section extending from the apex and having substantially the same shape. A magnetic body composed of one and second pieces and having an opening formed between the first and second pieces, and the magnetic body is oscillated to slide the magnet so that the optical A piezoelectric element that moves the member holder; and a magnetic sensor that detects a moving position of the magnet that moves when the piezoelectric element is driven, and the first and second pieces of the magnetic body have openings on the opening side. The piezoelectric element is driven in a state where the magnet is coupled to the magnet, and the magnet has a magnetization straight line that is a straight line connecting the vertex of the magnetic body and the cross-sectional center of the magnet. It is magnetized in direction orthogonal, the magnetic sensor in a cross-sectional view of the magnetic, an optical member driving device for being disposed in a direction other than the clothes 磁直 line.

Moreover, invention of Claim 3 of this invention is an optical member barrel provided with said optical member drive device.
Furthermore, the invention according to claim 4 of the present invention is an imaging apparatus including the optical member driving device.

(Function)
According to the first, third, and fourth aspects of the present invention, the magnetic member is vibrated by the piezoelectric element, so that the magnet is slid and driven to move the optical member holder.
Further, the moving position of the magnet that moves by driving the piezoelectric element is detected by a magnetic sensor.

  According to the present invention, a high position can be detected by appropriately disposing a magnet that moves by driving a piezoelectric element and a magnetic sensor for detecting the moving position of the magnet.

It is a perspective view showing the front side of a digital still camera as one embodiment of an imaging device of the present invention. It is a perspective view which shows the rear surface side of the digital still camera as one Embodiment of the imaging device of this invention. It is a front view which shows the optical member drive unit in a lens barrel as one Embodiment (1st Embodiment) of the optical member barrel of this invention. It is the elements on larger scale which expand and show a part of optical member drive unit shown in FIG. It is a perspective view which shows the principal part of the lens drive device as one Embodiment of the optical member drive device of this invention. It is explanatory drawing which shows the arrangement | positioning relationship of the magnetic sensor with respect to the magnet of the optical member drive device of this invention. It is a graph which shows the output waveform by the relative position with the magnet of the magnetic sensor ((theta) = 40 degrees) shown in FIG. It is a graph which shows the output waveform by the relative position with the magnet of the magnetic sensor ((theta) = 20 degree) shown in FIG. It is a graph which shows the output waveform by the relative position with the magnet of the magnetic sensor ((theta) = 0 degree) shown in FIG. It is a graph which shows the output waveform by the relative position with the magnet of the magnetic sensor ((theta) =-20 degrees) shown in FIG. FIG. 10 is a graph showing output amplitude (output difference between cut ends) obtained when a certain position is cut out in the position of the horizontal axis in FIGS. 7 to 9. It is a graph which shows the output waveform of a magnetic sensor at the time of changing the magnetization direction of the magnet shown in FIG. 6, and the shape of a magnetic body. It is the front view and side view which show the principal part of the lens drive device as other embodiment of the optical member drive device of this invention. It is the front view and side view which show the principal part of the lens drive device as further another embodiment of the optical member drive device of this invention. It is a front view which shows the optical member drive unit in a lens barrel as one Embodiment (2nd Embodiment) of the optical member barrel of this invention. It is the elements on larger scale which expand and show a part of optical member drive unit shown in FIG. It is a front view which shows the optical member drive unit in a lens barrel as one Embodiment (3rd Embodiment) of the optical member barrel of this invention. It is a side view which shows the optical member drive unit in a lens barrel as one Embodiment (3rd Embodiment) of the optical member barrel of this invention. It is a front view which shows the optical member drive unit in a lens barrel as one Embodiment (4th Embodiment) of the optical member barrel of this invention. It is a side view which shows the optical member drive unit in a lens barrel as one Embodiment (4th Embodiment) of the optical member barrel of this invention.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
Here, the imaging device according to the present invention is assumed to be a digital still camera 10 in the following embodiments. In the following embodiments, the optical member barrel in the present invention is assumed to be a lens barrel 20 or the like incorporated in the digital still camera 10. Furthermore, the optical member driving device according to the present invention is incorporated in the lens barrel 20 or the like.
The description will be given in the following order:

1. First Embodiment (Arrangement Example of Magnet and Magnetic Body in Camera Shake Correction)
2. Second Embodiment (Another Arrangement Example of Magnet and Magnetic Material in Camera Shake Correction)
3. Third Embodiment (Example in which the magnetic body has an L-shaped cross section in autofocus)
4). Fourth Embodiment (Example in which a magnetic body is a flat plate in autofocus)

[External appearance of imaging device]

FIG. 1 is a perspective view showing a front side of a digital still camera 10 as an embodiment of an imaging apparatus of the present invention.
FIG. 2 is a perspective view showing the rear side of the digital still camera 10 as an embodiment of the imaging apparatus of the present invention.
As shown in FIG. 1, the digital still camera 10 includes a rectangular parallelepiped body 11 constituting an exterior. Further, a lens barrel 20 (corresponding to an optical member barrel in the present invention) indicated by a two-dot chain line in FIG. The lens 20 a provided in the lens barrel body of the lens barrel 20 is positioned at the upper part on the front side of the body 11.
In the digital still camera 10 shown in FIGS. 1 and 2, left and right mean left and right viewed from the front side shown in FIG.

  Further, a flash 12 for emitting photographing auxiliary light and an AF (Auto Focus) auxiliary light emitting unit 13 are provided on the left side of the lens 20a. Furthermore, a shutter button 14 is provided on the left side of the upper surface of the body 11. Furthermore, a cover 11 a is provided on the front side of the body 11. The cover 11a is positioned below the front side of the body 11 so as to expose the lens 20a, the flash 12, and the AF auxiliary light emitting unit 13, and a protective position located above the front side and covering them. It can be slid like an arrow. Therefore, if the cover 11a is set to the shooting position (position shown in FIG. 1) and the shutter button 14 is pressed, shooting can be performed.

  On the other hand, as shown in FIG. 2, a menu button 15, a display 16, a cross key 17, a zoom lever 18, and an exposure correction button 19 are provided on the rear side of the body 11. By operating the menu button 15, various setting menus (still image shooting mode, moving image shooting mode, playback mode, shake correction mode ON / OFF, etc.) can be displayed on the display 16 (for example, a liquid crystal display). . The displayed menu can be selected with the cross key 17, and the selected setting can be determined with the enter button 17a. In addition to the setting menu, the display 16 can display an image to be taken and can reproduce the taken image. Further, zooming (magnification operation) can be performed by operating the zoom lever 18, and exposure correction such as backlight correction can be performed with one touch by operating the exposure correction button 19.

<1. First Embodiment>
[Configuration example of optical member driving unit in optical member barrel]

FIG. 3 is a front view showing the optical member driving unit 120 in the lens barrel as one embodiment (first embodiment) of the optical member barrel of the present invention.
FIG. 4 is a partially enlarged view showing a part of the optical member driving unit 120 shown in FIG. 3 in an enlarged manner.
An optical member driving unit 120 shown in FIG. 3 is an optical member driving device serving as a lens shift type camera shake correction mechanism in the digital still camera 10 shown in FIGS. 1 and 2. More specifically, by moving the shake correction lens 21 that is an optical member in two directions orthogonal to the optical axis direction, it is possible to prevent deterioration of the quality of a captured image due to shake.
The optical member driving unit 120 can be applied not only to a lens shift type shake correction mechanism but also to an imager shift type shake correction mechanism by moving an image pickup element (in this specification, an image pickup element is also an optical member). Included).

  Here, the lens 21 is held by a lens holder 22 (corresponding to an optical member holder in the present invention) formed in a rectangular shape. This lens holder 22 has one side (the left side in the vertical direction in FIG. 3) attached to the moving frame 24 so as to be movable in the vertical direction via a vertical guide shaft 23a. The moving frame 24 is formed in a substantially L shape when viewed from the front, holds the vertical guide shaft 23a, and is fixed in the lens barrel body via the horizontal guide shaft 23b. Between the part 11b and the fixed part 11c, it is attached to the horizontal direction so that movement is possible. Furthermore, as shown in FIG. 4 (indicated by arrow A in FIG. 3), a concave portion 22a is formed in the upper portion of the lens holder 22, and a guide shaft 23c is inserted into the concave portion 22a.

  Therefore, the lens holder 22 can move in the vertical direction along the guide shaft 23 a with respect to the moving frame 24. Further, the moving frame 24 can move in the horizontal direction along the guide shaft 23b with respect to the lens barrel body of the lens barrel 20 (see FIG. 1). The rotation of the lens holder 22 around the guide shaft 23a and the rotation of the moving frame 24 around the guide shaft 23b are prevented by the guide shaft 23c attached between the fixed portion 11b and the fixed portion 11c. ing. Therefore, the lens 21 can move only in two directions orthogonal to the optical axis direction.

  Further, the optical member driving unit 120 includes a guide shaft 23b and a magnetic body 31a provided in parallel with the guide shaft 23c as an embodiment of the optical member driving device of the present invention. As shown in FIG. 4 (indicated by arrow B in FIG. 3), the magnetic body 31a is formed of a rod-shaped body having an L-shaped cross section, and is attached to the fixed portion 11c (see FIG. 3). Vibrates in the horizontal direction by 32a. The inner surface of the magnetic body 31 a is in contact with a columnar magnet 33 a attached to the moving frame 24 by a magnetic force. Furthermore, a magnetic sensor 34a configured by an element that converts a change in magnetic force into an electric signal is disposed so that the magnetic force of the magnet 33a can be detected.

  Similarly, the optical member driving unit 120 includes a magnetic body 31b having an L-shaped cross section provided in parallel with the guide shaft 23a. The magnetic body 31 b vibrates in the vertical direction by the piezoelectric element 32 b attached to the moving frame 24. Further, the inner surface of the magnetic body 31b is in contact with a columnar magnet 33b attached to one side of the lens holder 22 (the right side in the vertical direction in FIG. 3) by magnetic force. Furthermore, a magnetic sensor 34b configured by an element that converts a change in magnetic force into an electric signal is disposed so that the magnetic force of the magnet 33b can be detected.

[Configuration example of optical member driving device]

FIG. 5 is a perspective view showing a main part of the lens driving device as one embodiment of the optical member driving device of the present invention.
The lens driving device shown in FIG. 5 includes a magnetic body 31a, a piezoelectric element 32a, a magnet 33a, and a magnetic sensor 34a.
The magnetic body 31b, the piezoelectric element 32b, the magnet 33b, and the magnetic sensor 34b shown in FIG. 3 have the same shape and the same arrangement.

  Here, the piezoelectric element 32a is configured by laminating a plurality of piezoelectric ceramic plates. A magnetic body 31a having an L-shaped cross section is bonded to one end face in the displacement generation direction (longitudinal direction) of the piezoelectric element 32a by an adhesive such as an epoxy resin adhesive or an acrylic adhesive. Therefore, when the piezoelectric ceramic plate is expanded and contracted as indicated by the arrow by driving the piezoelectric element 32a, the magnetic body 31a vibrates as indicated by the arrow.

  The magnetic body 31a is formed of a material that can be attracted to the magnet (for example, SUS430). Therefore, a cylindrical magnet 33a (for example, a magnet of neodymium or samarium cobalt) is in contact with the L-shaped inner surface of the magnetic body 31a by magnetic force (line contact at two points).

  In such an optical member driving apparatus of the present invention, for example, a driving voltage having a triangular waveform is input to the piezoelectric element 32a. At this time, the piezoelectric element 32a extends slowly in a long time T, and the piezoelectric element 32a has a short time t such that acceleration greater than the maximum static friction force between the magnetic body 31a and the magnet 33a generated by the magnetic force can be obtained. To shrink quickly. As a result, the magnetic body 31a and the magnet 33a move together in the long time T. However, in the short time t, slip occurs between the magnetic body 31a and the magnet 33a, and the magnet is moved even if the magnetic body 31a moves. 33a does not move.

  The magnet 33a is in contact with the L-shaped inner surface of the magnetic body 31a, and is formed in a cylindrical shape whose sliding direction is regulated in the longitudinal direction of the magnetic body 31a. For this reason, when the driving of the piezoelectric element 32a that extends slowly in the long time T and rapidly contracts in the short time t is continuously repeated, the magnet 33a moves in one direction in the longitudinal direction of the magnetic body 31a. Furthermore, the moving direction of the magnet 33a is reversed by causing the piezoelectric element 32a to contract slowly and expand rapidly.

Therefore, by vibrating the magnetic body 31a with the piezoelectric element 32a, the magnet 33a is driven to slide, and the moving frame 24 (see FIG. 3) to which the magnet 33a is attached is moved in the longitudinal direction (horizontal direction) of the magnetic body 31a. Can be moved. As the moving frame 24 moves, the lens holder 22 also moves in the horizontal direction via the guide shaft 23a shown in FIG. For this reason, optical camera shake correction (horizontal shake correction) can be realized by moving the moving frame 24 in the direction opposite to the direction in which the camera shake is caused by driving the piezoelectric element 32a.
Since each piezoelectric ceramic plate has a small amount of displacement with respect to the applied voltage, the amplitude of the piezoelectric element 32a is adjusted depending on the length of the piezoelectric ceramic plate and the number of laminated layers. Even in such a case, since the thickness in the optical axis direction does not increase, a lens driving device that is thin in the optical axis direction can be provided.

  Similarly, optical camera shake correction (vertical shake correction) can be realized by moving the moving frame 24 by driving the piezoelectric element 32b.

Further, as shown in FIG. 5, the magnetic body 31 a is composed of a first section and a second section, each having a cross section extending from the top and having substantially the same shape, between the first section and the second section. It has an L shape in which an opening is formed. Furthermore, a magnet 33a is coupled to the first and second pieces of the magnetic body 31a from the opening side. Furthermore, a magnetic sensor 34a is disposed on the opening side of the magnetic body 31a. The magnetic sensor 34a is attached in the lens barrel body of the lens barrel 20 (see FIG. 3). And in order to detect the horizontal movement position of the lens holder 22 (refer FIG. 3) moved by the piezoelectric element 32a, it arrange | positions so that the change of the magnetic force generated by the movement of the magnet 33a can be detected.
The magnetic sensor 34b shown in FIG. 3 is attached to a member (not shown) fixed to the moving frame 24 (see FIG. 3), and moves in the horizontal direction together with the moving frame 24. Therefore, it can be distinguished whether the sensor output change due to movement in the horizontal direction or the output change in the vertical direction.

FIG. 6 is an explanatory diagram showing the positional relationship of the magnetic sensor 34a with respect to the magnet 33a of the optical member driving apparatus of the present invention.
As shown in FIG. 6, the cylindrical magnet 33a is magnetized in a direction orthogonal to a magnetization straight line (a 45 ° oblique direction in FIG. 6) that is a straight line connecting the apex of the magnetic body 31a and the cross-sectional center of the magnet 33a. Has been. And the magnetic sensor 34a is arrange | positioned in directions other than on a magnetization straight line in the cross sectional view of the magnetic body 31a so that the magnetic force (magnetic flux density) of the normal line direction of such a magnet 33a can be detected.

Here, the magnetic sensor 34a includes, for example, an angle 1 which is a normal direction from the south pole of the magnet 33a, a horizontal angle 2, an angle 3 perpendicular to the angle 1, a vertical angle 4 and an N pole. It is conceivable to arrange them at an angle of 5 or the like, which is the normal direction.
However, considering the magnetization direction of the magnet 33a and the cross-sectional shape of the magnetic body 31a, even if the magnetic sensor 34a is arranged at the angle 3, the output from the magnetic sensor 34a cannot be obtained (the magnetic flux density does not change). Further, if the sensors are arranged in the ranges 1 and 2, a good sensor output from the magnetic sensor 34a can be obtained. However, in the range 3, the sensor output cannot be used, and the range 4 is not suitable as the sensor output.

  Therefore, the magnetic sensor 34a is preferably arranged in the range 1 or the range 2. For example, when the magnetic sensor 34a is arranged at an angle 4 within the range 2, the range of the arrow in the lower diagram of FIG. 6 becomes the relative movement range between the magnetic sensor 34a and the magnet 33a due to the movement of the magnet 33a. As a result, an output waveform corresponding to the relative position between the magnetic sensor 34a and the magnet 33a is obtained.

As described above, in the optical member driving device of the present invention, the magnetic sensor 34a detects a change in magnetic force (magnetic flux density) generated by the movement of the magnet 33a (detects a relative movement amount of the sensor 33 relative to the magnet 33a). . Therefore, the moving position of the lens holder 22 (see FIG. 3) can be accurately detected.
Next, the optimal arrangement of the magnetic sensor 34a (deviation angle θ from the angle 4 when the counterclockwise direction is positive) will be described.

FIG. 7 is a graph showing an output waveform according to the relative position of the magnetic sensor 34a (θ = 40 °) shown in FIG. 6 with the magnet 33a.
FIG. 8 is a graph showing an output waveform according to the relative position of the magnetic sensor 34a (θ = 20 °) shown in FIG. 6 with respect to the magnet 33a.
FIG. 9 is a graph showing an output waveform according to the relative position of the magnetic sensor 34a (θ = 0 °) shown in FIG. 6 with respect to the magnet 33a.
Further, FIG. 10 is a graph showing an output waveform according to the relative position of the magnetic sensor 34a (θ = −20 °) shown in FIG. 6 with respect to the magnet 33a.
In addition, the distance from the surface of the magnet 33a of the magnetic sensor 34a shows three types, gap 1 (0.1 mm), gap 2 (0.2 mm), and gap 3 (0.3 mm).

  The magnetic sensor 34a shown in FIG. 7 is arranged at θ = 40 °. In this case, the output waveform (change in magnetic flux density) of the magnetic sensor 34a is a curve as shown in FIG. Further, in the gap 1 where the distance from the magnet 33a is the closest, the amount of change in the magnetic flux density is the largest, and becomes smaller as the distance from the gap 2 and the gap 3 increases.

  Here, in order to accurately detect the moving position of the lens holder 22 (see FIG. 3), the magnetic flux density detected by the magnetic sensor 34a is within a range where the magnetic flux density is uniformly increased or decreased (a range where the linear increase / decrease). There must be. In other words, it is possible to accurately detect the moving position of the magnet 33a (lens holder 22) by using only the region in which the output waveform of the magnetic sensor 34a is a substantially straight line as the position information. When the output waveform is viewed in a substantially straight line region, the gap 3 is the longest and becomes shorter as the gap 2 and the gap 1 are approached.

  8 is arranged at θ = 20 °, the magnetic sensor 34a shown in FIG. 9 is arranged at θ = 0 °, and the magnetic sensor 34a shown in FIG. 10 has θ = −20 °. Is arranged in. The output waveform of the magnetic sensor 34a (change in magnetic flux density) has the same tendency as in the case of FIG. 7, but the amount of change in magnetic flux density gradually decreases.

FIG. 11 is a graph showing the output amplitude (output difference between the cut ends) obtained when a certain position is cut out from the position of the horizontal axis in FIGS.
In the graph shown in FIG. 11, the relative position between the magnet 33a and the magnetic sensor 34a is set to -0.2 mm to +0.2 mm.

  As shown in FIG. 11, as the arrangement angle θ of the magnetic sensor 34a increases from negative to positive, the amount of change in magnetic flux density increases. This tendency does not change regardless of whether the distance of the magnetic sensor 34a is the gap 1, the gap 2, or the gap 3.

FIG. 12 is a graph showing an output waveform of the magnetic sensor when the magnetization direction of the magnet and the shape of the magnetic body shown in FIG. 6 are changed.
If the magnetic body is L-shaped, it is optimal for driving to set the magnet to a 45 ° magnetization direction. However, in the case of a flat magnetic body 31, the magnetization direction shown in FIG. is there. As shown in FIG. 12, the output of the magnetic sensor 34 in this case is the same as in the case of FIG. 6 even if the magnet 33 is changed in the magnetization direction and the magnetic body 31 is changed from an L-shape to a flat plate. (An output waveform that uniformly increases or decreases is obtained). In the gap 1 where the distance from the magnet 33 is the closest, the amount of change in the magnetic flux density is the largest, and decreases as the gap 2 and the gap 3 are separated. In the region where the output waveform is substantially straight, the gap 3 is the longest and becomes shorter as the gap 2 and the gap 1 are approached.

  As described above, the graphs of FIGS. 7 to 12 clarify the output waveform depending on the relative position between the magnetic sensor and the magnet in relation to the arrangement angle θ and the gaps 1, 2, and 3. And it is preferable that the arrangement of the magnetic sensor (arrangement angle θ and gaps 1, 2, and 3) with respect to the magnetizing direction of the magnet is a place where the change amount of the magnetic flux density is large and the region where the output waveform is substantially linear is long.

  Therefore, the actual arrangement of the magnetic sensor is based on the restrictions on the shape of the body 11 (see FIGS. 1 and 2), the configuration of the lens barrel 20 (see FIG. 3), and the magnetic flux using the graphs in FIGS. The density change amount and the output waveform are appropriately determined by comprehensively considering the region where the output waveform is substantially linear.

FIG. 13 is a front view and a side view showing a main part of a lens driving device as another embodiment of the optical member driving device of the present invention.
FIG. 14 is a front view and a side view showing the main part of the lens driving device as still another embodiment of the optical member driving device of the present invention.
As shown in FIGS. 13 and 14, the magnet is not limited to the columnar magnet 33 a as shown in FIG. 5, but may be prismatic magnets 33 c and 33 d shown in FIGS. 13 and 14.

  Here, the lens driving device shown in FIG. 13 has a configuration in which a prismatic magnet 33c and a columnar magnetic body 31c are combined. The magnet 33c abuts on the upper surface of the magnetic body 31c by magnetic force (line contact at one point), and is adsorbed in a slidable state with an appropriate frictional force as a lens driving device.

  Further, the magnetic sensor 34c is disposed at the position 1, the position 2, the position 3, or the like on the magnet 33c. And the relative movement range of the magnetic sensor 34c and the magnet 33c is as shown by the arrow of the following figure. Therefore, the magnetic sensor 34c can detect a change in magnetic force generated by the movement of the magnet 33c.

  On the other hand, the lens driving device shown in FIG. 14 has a configuration in which a prismatic magnet 33d and a prismatic magnetic body 31d are combined. Specifically, two rails 35 are provided on the upper surface of the magnetic body 31d, and the magnet 33d is in contact with the upper surface of the magnetic body 31d via the rail 35 by magnetic force (line contact at two points). . Therefore, the magnet 33d and the magnetic body 31d are attracted in a slidable state with an appropriate frictional force as a lens driving device.

  Further, the magnetic sensor 34d is arranged at the position 1, the position 2, the position 3, or the like on the magnet 33d. The relative movement range between the magnetic sensor 34d and the magnet 33d is as shown by the arrows in the figure below. Therefore, the magnetic sensor 34d can detect a change in magnetic force generated by the movement of the magnet 33d.

  Thus, the shape of the magnet in the present invention is not limited to the cylindrical shape as shown in FIG. 5, but may be other shapes such as a prismatic shape as shown in FIGS. Further, the shape of the magnetic body in the present invention is not limited to the L shape as shown in FIG. 5, and may be a cylindrical shape shown in FIG. 13 or a prismatic shape shown in FIG. 14. And a relative position with a magnet is detectable by arrange | positioning a magnetic sensor in a suitable position.

  Further, the magnetic body is not limited to the L shape as shown in FIG. 5, and may be a V shape or a U shape. Then, by making the magnet and the magnetic body in line contact, it is possible to reduce the influence of the error during manufacture on the movement characteristics.

<2. Second Embodiment>
[Configuration example of optical member driving unit in optical member barrel]

FIG. 15 is a front view showing an optical member driving unit 220 in the lens barrel as one embodiment (second embodiment) of the optical member barrel of the present invention.
FIG. 16 is a partially enlarged view showing a part of the optical member driving unit 220 shown in FIG. 15 in an enlarged manner.
An optical member driving unit 220 shown in FIG. 15 is an optical member driving device serving as a lens shift type camera shake correction mechanism in the digital still camera 10 shown in FIGS. 1 and 2. Specifically, by moving the shake correction lens 21 in two directions orthogonal to the optical axis direction, it is possible to prevent the quality of the captured image from being deteriorated due to shake.
In FIGS. 15 and 16, the same members as those in the first embodiment are denoted by the same reference numerals. The optical member driving unit 220 can be applied not only to a lens shift type camera shake correction mechanism but also to an imager shift type camera shake correction mechanism by moving an image sensor.

  Here, the lens 21 is held by a lens holder 122 (corresponding to an optical member holder in the present invention) formed in a rectangular shape. The lens holder 122 is attached so that one side thereof (the left side in the vertical direction in FIG. 15) is movable in the vertical direction to the moving frame 124 via a vertical guide shaft 23a. Further, the moving frame 124 is formed in a substantially L shape when viewed from the front, and holds the guide shaft 23a in the vertical direction. Furthermore, as shown in FIG. 16 (indicated by an arrow A in FIG. 15), a concave portion 22a is formed in the upper portion of the lens holder 122, and the fixing portion 11b and the fixing portion 11c of the lens barrel main body are formed in the concave portion 22a. A guide shaft 23c provided between the two is inserted.

Further, the optical member driving unit 220 includes a magnetic body 131a attached to the moving frame 124 in parallel with the guide shaft 23c as one embodiment of the optical member driving device of the present invention. As shown in FIG. 16 (see arrow B in FIG. 15), the magnetic body 131a is formed of a rod-shaped body having an L-shaped cross section, and the L-shaped opening side is opposite to the guide shaft 23c (see FIG. 15 and FIG. 16, it faces downward. A piezoelectric element 132a is attached to the fixing portion 11c (see FIG. 15). Furthermore, a cylindrical magnet 133a that is vibrated in the horizontal direction by the piezoelectric element 132a is attached to the piezoelectric element 132a. The magnet 133a is in contact with the L-shaped inner surface of the magnetic body 131a by a magnetic force.

Thus, in the second embodiment, the cylindrical magnet 133a abuts on the L-shaped inner surface of the magnetic body 131a to support the lower portion of the moving frame 124, and the sliding direction of the magnet 133a is magnetic. The body 131a is restricted in the longitudinal direction (horizontal direction). Further, the upper part of the moving frame 124 is supported by the guide shaft 23c via the lens holder 122 so as to be movable in the horizontal direction.
The magnetic sensor 134a for detecting the magnetic force of the magnet 133a is fixed to the same member (not shown) as the moving frame 124 so as to move integrally with the moving frame 124.

  Therefore, the moving frame 124 can move in the horizontal direction along the surface of the magnet 133a. The rotation of the moving frame 124 around the magnet 133a is prevented by the guide shaft 23c. The rotation of the moving frame 124 around the guide shaft 23c is prevented by the contact between the magnetic body 131a and the magnet 133a. Therefore, in the second embodiment, the guide shaft 23b in the first embodiment shown in FIG. 3 is not necessary, and the simplification, size reduction, and cost reduction of the lens driving device can be realized. Moreover, since the magnetic body 131a and the magnet 133a always come into contact with each other without any backlash due to the magnetic force, the lens 21 does not move in an unnecessary direction due to backlash of the bearing portion as compared with the case where the guide shaft is used. Good optical performance can be obtained.

  Similarly, the optical member driving unit 220 shown in FIG. 15 includes a magnetic body 131b having an L-shaped cross section provided in parallel with the guide shaft 23a. The L-shaped opening side of the magnetic body 131b is directed to the opposite side (right side in FIG. 15) of the guide shaft 23a. In addition, a piezoelectric element 132 b is attached to the moving frame 124. Furthermore, a cylindrical magnet 133b that vibrates in the vertical direction by the piezoelectric element 132b is attached to the piezoelectric element 132b. The magnet 133b is in contact with the inner surface of the magnetic body 131b by a magnetic force.

Thus, in the second embodiment, the left portion of the lens holder 122 is supported by the guide shaft 23a so as to be movable in the vertical direction. The right portion of the lens holder 122 is supported by a cylindrical magnet 133b coming into contact with the L-shaped inner surface of the magnetic body 131b. The sliding direction is regulated in the longitudinal direction (vertical direction) of the magnetic body 131b.
The magnetic sensor 134b for detecting the magnetic force of the magnet 133b is fixed to the same member (not shown) as the lens holder 122 so as to move integrally with the lens holder 122.

  Therefore, the lens holder 122 can move in the vertical direction along the surface of the magnet 133b. The rotation of the lens holder 122 around the magnet 133b is prevented by the guide shaft 23a. Further, the rotation of the lens holder 122 around the guide shaft 23a is prevented by the contact between the magnetic body 131b and the magnet 133b.

  With the above configuration, the optical member driving apparatus of the present invention can move the lens 21 in the horizontal direction (X direction) by driving the piezoelectric element 32a (piezoelectric element 132a). Further, it is possible to move the lens 21 in the vertical direction (Y direction) by driving the piezoelectric element 32b (piezoelectric element 132b). Therefore, the lens 21 can be freely moved in a plane orthogonal to the optical axis direction, and the shake of the digital still camera 10 can be optically corrected. Then, by configuring the closed loop control for driving the piezoelectric element 32a (piezoelectric element 132a) and the piezoelectric element 32b (piezoelectric element 132b) according to the position of the lens 21, it is possible to obtain good driving performance. .

  The weight of the lens 21 and the lens holder 22 (lens holder 122) is generated by the magnetic force between the magnetic body 31b (magnetic body 131b) and the magnet 33b (magnet 133b) with respect to the fixed portion 11b and the fixed portion 11c. It is held by frictional force. Therefore, the optical member driving device of the present invention using the piezoelectric element 32a (piezoelectric element 132a), the magnetic body 31b (magnetic body 131b), and the magnet 33b (magnet 133b) is an optical device using a conventional electromagnetic driving type actuator. Unlike the member driving device, it is not necessary to supply power to keep the lens or the like in a predetermined position against its own weight, and power consumption can be reduced.

  Further, a magnetic sensor 34a (magnetic sensor 134a) is arranged so that the magnetic force of the magnet 33a (magnet 133a) can be detected. Furthermore, a magnetic sensor 34b (magnetic sensor 134b) is arranged so that the magnetic force of the magnet 33b (magnet 133b) can be detected. The relative movement amount of the magnetic sensor 34a (magnetic sensor 134a) relative to the sensor fixing portion with respect to the magnet 33a (magnet 133a) is changed to the magnet 33b (magnet 133b) relative to the sensor fixing portion by the magnetic sensor 34b (magnetic sensor 134b). ), The position of the lens 21 (lens holders 22, 122) can be accurately detected. Therefore, it is not necessary to separately provide a magnet for position detection, and downsizing and cost reduction can be realized.

  Also, the optical member driving device (optical member driving unit 120, optical member driving unit 220) of the present invention uses the piezoelectric element, the magnetic body, and the magnet as described above, and not a lens but a CCD image sensor or a CMOS image sensor. An imager shift type image stabilization mechanism can be obtained by freely moving an image sensor such as an image sensor in a plane orthogonal to the optical axis direction. Specifically, the optical member holder that holds the image sensor, the magnet attached to the optical member holder, the magnetic body, and the magnetic body are vibrated to slide the magnet to move the optical member holder. And a magnetic sensor for detecting the moving position of the magnet that moves by driving the piezoelectric element. Then, the piezoelectric element is driven in a state where the magnet is coupled to the magnetic body. Accordingly, it is possible to realize a shake correction mechanism based on the movement of the image sensor while accurately detecting the movement position of the image sensor with the magnetic sensor.

<3. Third Embodiment>
[Configuration example of optical member driving unit in optical member barrel]

FIG. 17 is a front view showing an optical member driving unit 320 in a lens barrel as one embodiment (third embodiment) of the optical member barrel of the present invention.
FIG. 18 is a side view showing an optical member driving unit 320 in the lens barrel as one embodiment (third embodiment) of the optical member barrel of the present invention.
An optical member driving unit 320 shown in FIGS. 17 and 18 is an optical member driving device serving as an autofocus mechanism in the digital still camera 10 shown in FIGS. 1 and 2. Specifically, a subject image is formed on the image sensor by moving the lens 221 in the optical axis direction.

Here, the lens 221 is held by a lens holder 222 (corresponding to an optical member holder in the present invention) formed in a substantially rectangular shape. This lens holder 222 has a corner side (upper left corner side in FIG. 17) in the optical axis direction between the fixed portion 211a and the fixed portion 211b in the lens barrel body via the guide shaft 223 in the optical axis direction. It is attached movably.
In addition, FIG. 17 is an A arrow view of FIG.

  The optical member driving unit 320 includes a magnetic body 231 provided in the optical axis direction in parallel with the guide shaft 223 as an embodiment of the optical member driving device of the present invention. As shown in FIG. 17, the magnetic body 231 is formed of a rod-shaped body having an L-shaped cross section, and vibrates in the optical axis direction by the piezoelectric element 232 attached to the fixed portion 211b (see FIG. 18). . The inner surface of the magnetic body 231 is in contact with a columnar magnet 233 attached to the lens holder 222 by a magnetic force. Furthermore, a magnetic sensor 234 attached to the fixed portion 211a (see FIG. 18) is arranged above the magnet 233 so that the magnetic force of the magnet 233 can be detected.

  Therefore, the lens holder 222 can move in the optical axis direction along the guide shaft 223. The rotation of the lens holder 222 around the guide shaft 223 is prevented by the contact between the magnetic body 231 and the magnet 233, and the rotation of the lens holder 222 around the magnet 233 is prevented by the guide shaft 223. . Therefore, the lens 221 can move only in the optical axis direction.

  In the third embodiment, for example, a driving voltage having a triangular waveform is input to the piezoelectric element 232. As a result, the piezoelectric element 232 vibrates and the magnetic body 231 vibrates so that the magnet 233 moves in the longitudinal direction (optical axis direction) of the magnetic body 231 while contacting the inner surface of the magnetic body 231 having an L-shaped cross section. Become. Therefore, since the lens 221 moves in the optical axis direction via the lens holder 222 to which the magnet 233 is attached, the focus can be adjusted.

  Further, a change in magnetic force generated by the movement of the magnet 233 is detected by the magnetic sensor 234. And the magnetic sensor 234 is arrange | positioned in the range which the detection output of the change of magnetic force increases / decreases substantially linearly. For this reason, the output waveform of the magnetic sensor 234 and the moving position of the magnet 233 correspond to each other, so that the moving position of the lens holder 222 can be accurately detected from the output of the magnetic sensor 234.

<4. Fourth Embodiment>
[Configuration example of optical member driving unit in optical member barrel]

FIG. 19 is a front view showing an optical member driving unit 420 in a lens barrel as one embodiment (fourth embodiment) of the optical member barrel of the present invention.
FIG. 20 is a side view showing an optical member driving unit 420 in the lens barrel as one embodiment (fourth embodiment) of the optical member barrel of the present invention.
The optical member drive unit 420 shown in FIGS. 19 and 20 is an optical member that serves as an autofocus mechanism of the digital still camera 10 (see FIGS. 1 and 2), similarly to the optical member drive unit 320 shown in FIGS. It is a drive device.

This focus adjustment mechanism moves a lens 321 in the optical axis direction to form a subject image on an image sensor such as a CCD image sensor or a CMOS image sensor. The lens 321 is held by a lens holder 322 (corresponding to an optical member holder in the present invention) formed in a substantially rectangular shape, and the lens holder 322 has a guide shaft 323 on one side (the upper left corner in FIG. 19). Is inserted and is movable in the optical axis direction.
FIG. 19 is a view on arrow A in FIG.

  The optical member driving unit 420 includes a magnetic body 331 provided in the optical axis direction in parallel with the guide shaft 323 as an embodiment of the optical member driving device of the present invention. As shown in FIG. 19, the magnetic body 331 is formed of a flat plate and vibrates in the optical axis direction by the piezoelectric element 332 attached to the fixed portion 311b (see FIG. 20). Therefore, the optical member drive unit 420 is an optical member drive unit 320 (see FIG. 17) in which the focus drive body is a magnetic body 231 having an L-shaped cross section in that the magnetic body 331 serving as the focus drive body is a flat plate. ) Is different.

  Furthermore, in the fourth embodiment, the upper surface of the magnetic body 331 is in contact with the columnar magnet 333 attached to the lens holder 322 by a magnetic force. Further, a magnetic sensor 334 attached to the fixed portion 311a (see FIG. 20) is disposed above the magnet 333 so that the magnetic force of the magnet 333 can be detected.

  Therefore, the lens holder 322 can move in the optical axis direction along the guide shaft 323. The rotation of the lens holder 322 around the guide shaft 323 is prevented by the magnetic force of the magnet 333 that contacts the magnetic body 331, and the rotation of the lens holder 322 around the magnet 333 is prevented by the guide shaft 323. . Therefore, the lens 321 can be moved only in the optical axis direction.

Also in such an optical member driving unit 420, the magnet 333 can be moved in the longitudinal direction (optical axis direction) of the magnetic body 331 by inputting a driving voltage to the piezoelectric element 332 and vibrating the magnetic body 331. . Therefore, since the lens 321 moves in the optical axis direction via the lens holder 322 to which the magnet 333 is attached, the focus can be adjusted.
Since the magnet 333 and the magnetic body 331 are in contact with each other by magnetic force, the lens 321 does not move in any direction other than the optical axis direction.

  Further, a change in magnetic force generated by the movement of the magnet 333 is detected by the magnetic sensor 334. And the magnetic sensor 334 is arrange | positioned in the range which the detection output of the change of magnetic force increases / decreases substantially linearly. Therefore, since the output waveform of the magnetic sensor 334 corresponds to the moving position of the magnet 333, the moving position of the lens holder 322 can be accurately detected from the output of the magnetic sensor 334.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to embodiment mentioned above, A various deformation | transformation is possible. For example, in the embodiment, the digital still camera 10 is taken as an example of the imaging device. However, the present invention is not limited to this, and can be widely applied to imaging devices such as a silver salt camera, a digital video camera, and a camera-equipped mobile phone.

10 Digital still camera (imaging device)
20 Lens barrel (optical member barrel)
21, 221, 321 Lens (optical member)
22, 122, 222, 322 Lens holder (optical member holder)
31, 31a, 31b, 131a, 131b, 231, 331 Magnetic body 32a, 32b, 132a, 132b, 232, 332 Piezoelectric element 33, 33a, 33b, 133a, 133b, 233, 333 Magnet 34, 34a, 34b, 134a, 134b, 234, 334 Magnetic sensor 120, 220, 320, 420 Optical member driving unit (optical member driving device)

Claims (4)

An optical member holder for holding the optical member;
A magnet attached to the optical member holder;
A magnetic body having a cross section extending from the top and first and second pieces each having substantially the same shape and having an opening formed between the first and second pieces;
Piezoelectric elements that move the optical member holder by sliding the magnet by vibrating the magnetic body;
A magnetic sensor for detecting a moving position of the magnet that moves by driving the piezoelectric element;
While driving the piezoelectric element in a state where the magnet is coupled to the first and second pieces of the magnetic body from the opening side,
The magnet is magnetized in a direction orthogonal to a magnetization straight line that is a straight line connecting the apex of the magnetic body and the cross-sectional center of the magnet,
The optical member driving device, wherein the magnetic sensor is disposed in a direction other than the magnetization straight line in a cross-sectional view of the magnetic body. The magnetic sensor is arranged in a cross-sectional view of the magnetic body other than on the magnetization straight line, and an imaginary straight line centered on the magnet is disposed in a direction other than the direction intersecting the magnetic body. The optical member driving device according to claim 1. An optical member holder for holding the optical member;
A magnet attached to the optical member holder;
A magnetic body having a cross section extending from the top and first and second pieces each having substantially the same shape and having an opening formed between the first and second pieces;
Piezoelectric elements that move the optical member holder by sliding the magnet by vibrating the magnetic body;
A magnetic sensor for detecting a moving position of the magnet that moves by driving the piezoelectric element;
While driving the piezoelectric element in a state where the magnet is coupled to the first and second pieces of the magnetic body from the opening side,
The magnet is magnetized in a direction orthogonal to a magnetization straight line that is a straight line connecting the apex of the magnetic body and the cross-sectional center of the magnet,
The optical member barrel, wherein the magnetic sensor is disposed in a direction other than the magnetization straight line in a cross-sectional view of the magnetic body. An optical member holder for holding the optical member;
A magnet attached to the optical member holder;
A magnetic body having a cross section extending from the top and first and second pieces each having substantially the same shape and having an opening formed between the first and second pieces;
Piezoelectric elements that move the optical member holder by sliding the magnet by vibrating the magnetic body;
A magnetic sensor for detecting a moving position of the magnet that moves by driving the piezoelectric element;
While driving the piezoelectric element in a state where the magnet is coupled to the first and second pieces of the magnetic body from the opening side,
The magnet is magnetized in a direction orthogonal to a magnetization straight line that is a straight line connecting the apex of the magnetic body and the cross-sectional center of the magnet,
The imaging device, wherein the magnetic sensor is arranged in a direction other than the magnetization straight line in a cross-sectional view of the magnetic body.

Images