JP2006246656A - Actuator, focusing device, and image pickup unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an actuator which uses piezoelectric elements and is a thin type, and by which an amount of deformation of the piezoelectric elements is much obtained, and to provide a focusing device and an image pickup unit making use of it. <P>SOLUTION: The image pickup unit 30 includes the focusing device 20 installed on a substrate 32, and an imaging device 31. The focusing device 20 includes the actuator 10 comprising the piezoelectric element 11 and the piezoelectric element 12. The piezoelectric element 11 and the piezoelectric element 12 of the actuator 10 have annular portions, and key portions which are formed at the annular portions facing the same circumferential direction. When a voltage is applied to the actuator 10, the key portions of the piezoelectric element 11 and the piezoelectric element 12 deform respectively, by which a lens holder 22 of the focusing device 20 moves in a direction of an optical axis. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an actuator using a piezoelectric element, a focus adjustment device using the same, and an imaging device.

  Conventionally, in an imaging apparatus, a piezoelectric element such as a bimorph piezoelectric element is used as an actuator for adjusting a focus by moving a lens barrel or an imaging element. For example, the bimorph piezoelectric element is formed in a disk shape as disclosed in Patent Document 1. The disk-shaped actuator is thin and effective in reducing the size of the device.

  By the way, since the deformation amount of the bimorph piezoelectric element is proportional to the square of the length of the element, it is necessary to form the element long in order to obtain a large deformation amount.

Therefore, in order to obtain a large amount of deformation of the bimorph type piezoelectric element, as disclosed in Patent Document 2 and Patent Document 3, an actuator in which a bimorph type piezoelectric element is formed in a spiral shape has been developed.
Utility Model Registration No. 2538695 JP 2004-294533 A Japanese translation of PCT publication No. 2003-518752

  In recent years, imaging devices have been mounted on small electronic devices such as mobile phones, and actuators for performing focus adjustment are also required to be downsized. The actuator disclosed in Patent Document 1 has a configuration in which a bimorph piezoelectric element is formed in a disk shape, and thus is thin and does not require a large installation space, and is effective for downsizing the device. As a result, many applications were limited.

  On the other hand, since the actuators disclosed in Patent Document 2 and Patent Document 3 have a configuration in which a bimorph piezoelectric element is formed in a spiral shape, a large amount of deformation of the piezoelectric element can be obtained, but the shape must be large. Therefore, it was difficult to cope with the downsizing of the apparatus.

  Therefore, there has been a demand for an actuator that uses a piezoelectric element, is thin, and can obtain a large amount of deformation of the piezoelectric element.

  The present invention has been made in view of the above circumstances, and provides a thin actuator that can obtain a large amount of deformation of a piezoelectric element using a piezoelectric element, and a focus adjustment apparatus and an imaging apparatus using the actuator. Objective.

In order to achieve the above object, an actuator according to the first aspect of the present invention provides:
Formed from piezoelectric elements,
An annular portion and a plurality of key portions arranged on the annular portion so as to face the same direction in the circumferential direction are provided.

In order to achieve the above object, an actuator according to the second aspect of the present invention provides:
A first piezoelectric element comprising: a first annular portion; and a plurality of first key portions arranged in the same direction in the circumferential direction inside the first annular portion;
A second piezoelectric element including a second annular portion and a plurality of second key portions arranged on the outer side of the second annular portion so as to face the same direction in the circumferential direction;
The diameter of the second annular portion is smaller than the diameter of the first annular portion,
Each of the second key portions is arranged in a region surrounded by the first annular portion and the first key portion.

In order to achieve the above object, a focus adjustment apparatus according to a third aspect of the present invention includes:
A lens holder that holds the lens and is movable in the optical axis direction;
A holder support substrate on which the lens holder is installed;
A focus adjusting device including an actuator that is provided between the holder support substrate and the lens holder and moves the lens holder in the optical axis direction;
The actuator includes a first piezoelectric element including a first annular portion, and a plurality of first key portions arranged in the same direction in the circumferential direction inside the first annular portion, A second piezoelectric element including a second annular portion and a plurality of second key portions arranged on the outer side of the second annular portion so as to face the same direction in the circumferential direction;
The diameter of the second annular part is smaller than the diameter of the first annular part, and the second key part is an area surrounded by the first annular part and the first key part, respectively. Are located in
The actuator is characterized in that when a voltage is applied, the first key portion and / or the second key portion are deformed in the optical axis direction, and the lens holder is moved in the optical axis direction. .

  The first key portion and the second key portion are respectively in the optical axis direction and in opposite directions when a voltage is applied to the first piezoelectric element and the second piezoelectric element. It may be deformed.

  A rotating cam that moves the lens holder in the optical axis direction is provided between the lens holder and the actuator, and the actuator is configured such that the rotating cam is moved by applying a voltage periodically. It may be rotated.

  The piezoelectric element may be formed of a bimorph type piezoelectric element.

In order to achieve the above object, an imaging apparatus according to the fourth aspect of the present invention provides:
The focus adjusting apparatus according to the third aspect;
A substrate on which the focusing device is installed;
And an image pickup device disposed on the substrate.

  According to the present invention, it is possible to provide a thin actuator that can obtain a large amount of deformation of a piezoelectric element by using a piezoelectric element including a key portion, and a focus adjustment device and an imaging apparatus using the actuator. .

  An actuator according to a first embodiment of the present invention, and a focus adjustment device and an imaging device using the actuator will be described with reference to the drawings.

  An imaging apparatus 30 according to a first embodiment of the present invention is shown in FIGS. FIG. 1 is a partial cross-sectional view of the imaging device 30. FIG. 2 is a cross-sectional view of the imaging device 30, and FIG. 3 is a cross-sectional view of the imaging device 30 when a voltage is applied to the actuator 10. 2 and 3 omit a lens barrel 26 and a cover 27 described later.

  The imaging device 30 according to the first embodiment of the present invention includes a focus adjustment device 20, an imaging element 31, and a substrate 32 as shown in FIG. The image sensor 31 converts an optical image of a subject into an electrical signal. The image pickup device 31 is composed of a CCD (Charge Coupled Device), a CMOS (Complementary Metal Oxide Semiconductor) image sensor, and the like, and is disposed on a substrate 32 as shown in FIG.

  As shown in FIG. 2, the focus adjustment device 20 includes an actuator 10, lenses 21 a to 21 c, a lens holder 22, cams 23 a and 23 b, a support substrate 24, a filter 25, a lens barrel 26, and a cover 27. With.

  The actuator 10 is installed between the lens holder 22 and the support substrate 24 as shown in FIGS. The actuator 10 includes a piezoelectric element 11 and a piezoelectric element 12 as shown in FIG. The actuator 10 is connected to a power source (not shown) and a drive circuit control unit (not shown), and a voltage is applied in accordance with an input from the control unit (not shown).

  The piezoelectric element 11 is formed from a bimorph type piezoelectric element. As shown in FIG. 4B, the piezoelectric element 11 includes an annular portion 11a and four cantilevered key portions 11b. The key portions 11b are formed inside the annular portion 11a and are arranged in the same direction in the circumferential direction of the annular portion 11a, and the respective key portions 11b are arranged substantially equally spaced from each other. The annular portion 11a of the piezoelectric element 11 is located inside the groove portion 24a of the support substrate 24, and is fixed to the support substrate 24 by a fixing means such as a pin (not shown).

  A cross-sectional view of the piezoelectric element 11 taken along the line X-X ′ is shown in FIG. As shown in FIG. 4C, the piezoelectric element 11 includes an electrode 51, a piezoelectric body 52, and a piezoelectric body 53. The piezoelectric body 52 is formed on the upper surface of the electrode 51, and the piezoelectric body 53 is formed on the lower surface of the electrode 51. The piezoelectric body 52 and the piezoelectric body 53 are formed on the electrode 51 by, for example, a hydrothermal synthesis method.

  The piezoelectric body 52 and the piezoelectric body 53 of the piezoelectric element 11 are polarized in different directions. When a voltage is applied to the upper and lower sides of the piezoelectric body 52 and the piezoelectric body 53, for example, the piezoelectric body 52 contracts in the lateral direction, the piezoelectric body 53 extends in the lateral direction, and the entire piezoelectric element 11 bends upward. Note that the polarization directions of the piezoelectric bodies 52 and 53 of the present embodiment may be the same or may be reversed.

  When a voltage is applied to the piezoelectric element 11, the piezoelectric element 11 is deformed from the state shown in FIG. 5A as shown in FIG. 5B. Further, the direction in which the piezoelectric element 11 is deformed can be changed by the applied voltage. For example, when a voltage is applied as shown in FIG. 5B, the piezoelectric element 11 is deformed upward, but when a voltage is applied as shown in FIG. 5C, it is opposite to FIG. 5B. The piezoelectric element 11 is deformed downward.

  The piezoelectric element 12 is formed of a bimorph type piezoelectric element in the same manner as the piezoelectric element 11. The piezoelectric element 12 is positioned inside the groove portion 24a of the support substrate 24 together with the piezoelectric element 11, and is fixed to the support substrate 24 by a fixing means such as a pin (not shown). As shown in FIG. 4D, the piezoelectric element 12 includes an annular part 12 a and four cantilevered key parts 12 b as in the piezoelectric element 11. The diameter of the annular portion 12 a of the piezoelectric element 12 is smaller than the diameter of the annular portion 11 a of the piezoelectric element 11. Moreover, the key part 12b of the piezoelectric element 12 is formed on the outer side of the annular part 12a in the same direction in the circumferential direction of the annular part 12a and at substantially equal intervals. As shown in FIG. 4A, the key portion 12 b is disposed in a region surrounded by the annular portion 11 a and the key portion 11 b of the piezoelectric element 11 so as to face the key portion 11 b of the piezoelectric element 11.

  When a voltage is applied to each of the piezoelectric element 11 and the piezoelectric element 12 of the actuator 10 having the above configuration, the key part 11b of the piezoelectric element 11 and the key part 12b of the piezoelectric element 12 are respectively in the optical axis direction and are mutually connected. Deformation in the opposite direction pushes up the cam 23b. As the cam 23b is pushed up by the actuator 10, the lens holder 22 is pushed up in the optical axis direction as shown in FIG.

  The lenses 21a to 21c collect optical images of the subject.

  The lens holder 22 includes a small-diameter cylindrical portion, a large-diameter cylindrical portion, and a medium-diameter cylindrical portion. The lens 21a is held in the small diameter cylindrical portion, the lens 21b is held in the medium diameter cylindrical portion, and the lens 21c is held in the large diameter cylindrical portion. The lens holder 22 is installed in the lens barrel 26 so as to be movable in the optical axis direction.

  The cam 23 a and the cam 23 b are provided between the lens holder 22 and the actuator 10. As shown in FIG. 2, the cam 23 a is fixed to the lens holder 22 and is movable together with the lens holder 22 in the optical axis direction. Unlike the cam 23a, the cam 23b is not fixed. The cam 23b is rotatably provided between the cam 23a and the actuator 10, and acts as a so-called rotating cam. When the cam 23b is moved in the optical axis direction by the actuator 10, the cam 23a is pushed up in the optical axis direction, and the lens holder 22 to which the cam 23a is fixed is pushed up in the optical axis direction. Further, when the cam 23b is rotated by the actuator 10, the lens holder 22 to which the cam 23a is fixed is pushed up in the optical axis direction by the action of the cam 23b and the cam 23a.

  The support substrate 24 includes a groove 24a, and the actuator 10 is installed in the groove 24a. The support substrate 24 further includes an opening 24b, and holds the filter 25 in the opening 24b. The support substrate 24 is installed on the substrate 32.

  The filter 25 is composed of, for example, an ND filter (Neutral Density filter) or the like, and reduces only the intensity of light entering the image sensor 31 at a specific ratio. The filter 25 is located in the opening 24 b of the support substrate 24 and is held by the support substrate 24.

  The lens barrel 26 is formed in a cylindrical shape as shown in FIG. The lens barrel 26 includes a lens holder 22, a support substrate 24, and the like. The lens barrel 26 is provided with a guide (not shown) that cannot rotate the lens holder 22 and guides the lens holder 22 in the optical axis direction. Thereby, the cam 23b is rotated by the actuator 10, whereby the lens holder 22 to which the cam 23a is fixed is pushed up in the optical axis direction. A cover 27 is attached to the tip of the lens barrel 26 opposite to the substrate 32.

  In the focus adjustment device 20 having the above-described configuration, when a voltage is applied to the piezoelectric element 11 and the piezoelectric element 12 of the actuator 10, the key portion 11b of the piezoelectric element 11 is directed upward in the optical axis direction, and the key portion 12b of the piezoelectric element 12 is light. It bends and deforms downward in the axial direction. Then, the cam 23b is an amount corresponding to the height in the optical axis direction, which is the sum of the amount of deformation of the key portion 11b of the piezoelectric element 11 in the optical axis direction and the amount of deformation of the key portion 12b of the piezoelectric element 12 in the optical axis direction. Is pushed up in the optical axis direction, and the lens holder 22 is pushed up in the optical axis direction. When the application of voltage to the piezoelectric element 11 and the piezoelectric element 12 is stopped, the key portion 11b of the piezoelectric element 11 and the key portion 12b of the piezoelectric element 12 return to their original shapes, so that the cam 23b returns to the initial position, and the lens holder 22 Returns to the first position.

  As described above, the actuator 10 is formed only from the piezoelectric element 11 even though the size is not much different between the case where the actuator 10 is only the piezoelectric element 11 and the case where the actuator 10 is composed of the piezoelectric element 11 and the piezoelectric element 12. About twice as much deformation can be obtained as compared with the case where it is done. By combining two piezoelectric elements each having a key portion in this way, the amount of deformation can be twice as large as that of the single piezoelectric element even though the width and thickness are substantially the same, and the piezoelectric element is small in size. An actuator capable of obtaining a large amount of deformation can be provided.

Moreover, in the focus adjustment apparatus 20 which employ | adopts said structure, a voltage is selectively applied to the piezoelectric element 11 and the piezoelectric element 12 of the actuator 10 periodically, for example, by applying the voltage which has a sawtooth waveform. It is also possible to move the lens holder 22 in the optical axis direction by intermittently moving the key portion 11b of the piezoelectric element 11 and the key portion 12b of the piezoelectric element 12 to rotate the cam 23b.
The operation of intermittently moving the key portion 11b of the piezoelectric element 11 and the key portion 12b of the piezoelectric element 12 to rotate the cam 23b will be described in detail below.
6A to 6C are diagrams schematically showing the piezoelectric element 11 and part of the piezoelectric element 12 of the actuator 10 and the cams 23a and 23b. When a voltage is periodically applied to the piezoelectric element 11 as shown in FIG. 6B, the key portion 11b of the piezoelectric element 11 is intermittently deformed, and the cam 23b rotates in the direction indicated by the arrow Y in FIG. The lens holder 22 moves upward in the optical axis direction by the action of the cam 23a. On the other hand, as shown in FIG. 6C, when a voltage is periodically applied to the piezoelectric element 12, the key portion 12b of the piezoelectric element 12 is intermittently deformed, and the cam 23b rotates in the direction indicated by the arrow Y '. The lens holder 22 moves downward in the optical axis direction by the action of 23b and the cam 23a.

  In this embodiment, since an actuator that deforms by applying a voltage is used, unlike the configuration in which the lens holder is moved using a small motor, no sound is emitted from the actuator. Therefore, it can be used for an imaging apparatus having a function of recording sound.

The present invention is not limited to the above-described embodiments, and various modifications and applications are possible.

  In the present embodiment, in order to obtain more stability, the case where there are four key portions has been described as an example, but it may be configured with two.

  Further, when two deformation amounts are not necessary, the actuator 10 may be composed of only the piezoelectric element 11 or 12.

  In the above-described embodiment, the case where the key portion is formed in the circular annular portion has been described as an example. However, the present invention is not limited to this. For example, as shown in FIG. It is also possible to provide. In this case, the actuator 80 shown in FIG. 7A includes an annular portion 80a and a key portion 80b. The actuator is not limited to a circle or a quadrangle, and may have various shapes such as a triangle, a pentagon or more polygon, and an ellipse. Further, two actuators 80 having the shape shown in FIG. 7A can be combined as in the actuator 10 of the above-described embodiment.

  In the embodiment described above, the key portion 11b of the piezoelectric element 11 and the key portion 12b of the piezoelectric element 12 are arranged in different directions, and the key portion 12b includes the annular portion 11a and the key portion 11b. Although the configuration arranged in the region surrounded by the example has been described as an example, the configuration is not limited thereto. For example, as shown in FIG. 7B, the respective key portions of the piezoelectric element are arranged in the same direction in the circumferential direction, and may not be arranged in a region surrounded by one annular portion and the key portion. good. In this case, the actuator 90 includes a piezoelectric element 91 and a piezoelectric element 92 as shown in FIG. The piezoelectric element 91 includes an annular portion 91a and a key portion 91b, and the piezoelectric element 92 includes an annular portion 92a and a key portion 92b.

  In the above-described embodiment, the actuator 10 is described by taking as an example the case where the actuator 10 is composed of two piezoelectric elements, ie, the piezoelectric element 11 and the piezoelectric element 12, but the present invention is not limited to this. For example, FIG. It may be composed of two or more piezoelectric elements, such as a combination of three piezoelectric elements having the shape shown in FIG.

  In addition, the amount of deformation when a voltage is applied to the piezoelectric element 11 and the piezoelectric element 12 of the actuator 10 varies depending on the relationship between the adhesive, the type of metal of the electrode, and the thickness of the piezoelectric body and the electrode. 10 can be appropriately changed according to the amount of deformation required.

  In the above-described embodiment, the actuator 10 has been described by taking as an example the case where it is provided between the lens holder 22 and the support substrate 24. However, the present invention is not limited to this, and the substrate 32 is not provided without providing the support substrate 24. And the lens holder 22, or the support substrate 24 and the substrate 32 may be formed integrally.

  In each of the above-described embodiments, the configuration in which the optical image of the subject is collected by the three lenses has been described as an example. However, the configuration is not limited thereto, and for example, a configuration using two lenses may be employed. Is possible.

It is a fragmentary sectional view of the imaging device concerning an embodiment of the invention. It is sectional drawing of the imaging device which concerns on embodiment of this invention. It is sectional drawing of an imaging device when a voltage is applied to the actuator which concerns on embodiment of this invention. It is a figure which shows an actuator typically. It is a figure which shows a piezoelectric element typically. It is a figure which shows typically the actuator at the time of changing the voltage to apply. It is a figure which shows the modification of an actuator.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Actuator 20 Focus adjustment apparatus 21a, 21b, 21c Lens 22 Lens holder 23a, 23b Cam 24 Support board 25 Filter 26 Lens barrel 27 Cover 30 Imaging apparatus 31 Imaging element 32 Board

Claims (7)

Formed from piezoelectric elements,
An actuator comprising: an annular portion; and a plurality of key portions disposed on the annular portion so as to face the same direction in the circumferential direction. A first piezoelectric element comprising: a first annular portion; and a plurality of first key portions arranged in the same direction in the circumferential direction inside the first annular portion;
A second piezoelectric element including a second annular portion and a plurality of second key portions arranged on the outer side of the second annular portion so as to face the same direction in the circumferential direction;
The diameter of the second annular portion is smaller than the diameter of the first annular portion,
The actuator is characterized in that the second key portion is disposed in a region surrounded by the first annular portion and the first key portion, respectively. A lens holder that holds the lens and is movable in the optical axis direction;
A holder support substrate on which the lens holder is installed;
A focus adjusting device including an actuator that is provided between the holder support substrate and the lens holder and moves the lens holder in the optical axis direction;
The actuator includes a first annular portion, a first piezoelectric element including a plurality of first key portions disposed on the inner side of the first annular portion and facing the same direction in the circumferential direction, A second piezoelectric element comprising two annular portions and a plurality of second key portions arranged on the outer side of the second annular portion so as to face the same direction in the circumferential direction;
The diameter of the second annular part is smaller than the diameter of the first annular part, and the second key part is an area surrounded by the first annular part and the first key part, respectively. Are located in
The actuator is characterized in that when a voltage is applied, the first key portion and / or the second key portion are deformed in the optical axis direction, and the lens holder is moved in the optical axis direction. Focus adjustment device.   The first key portion and the second key portion are respectively in the optical axis direction and in opposite directions when a voltage is applied to the first piezoelectric element and the second piezoelectric element. The focus adjustment apparatus according to claim 3, wherein the focus adjustment apparatus is deformed.   A rotating cam that moves the lens holder in the optical axis direction is provided between the lens holder and the actuator, and the actuator is configured such that the rotating cam is moved by applying a voltage periodically. The focus adjustment device according to claim 3 or 4, wherein the focus adjustment device is rotated.   The focus adjustment apparatus according to claim 3, wherein the piezoelectric element is formed of a bimorph type piezoelectric element. The focus adjustment device according to any one of claims 3 to 6,
A substrate on which the focusing device is installed;
An image pickup apparatus comprising: an image pickup element disposed on the substrate.

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