JP2006162803A - Optical device and imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical device driven at low voltage and composed of the small number of parts, and an imaging apparatus using the same. <P>SOLUTION: The optical device 10 is equipped with a lens barrel 14, a lens holder 12 installed in the lens barrel 14 and holding lenses 13a to 13c, and an actuator 11 installed in the lens barrel 14 so as to abut on one surface of the lens holder 12. The actuator 11 is constituted of an insulating film 51, electrodes 52 respectively formed on the opposed surfaces of the insulating film 51, and a high polymer layer 53 formed to cover over the insulating film 51 and the electrodes 52. The periphery part of the electrode 52 of the actuator 11 is deformed to be swollen in an optical axis direction according as voltage is applied thereto. By utilizing the deformation in the optical axis direction, the lens holder 12 is moved in the optical axis direction. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical device for adjusting a focal length between a lens and an image sensor, and an image pickup device using the optical device.

  In recent years, electronic devices such as mobile phones equipped with a minute camera have become widespread, and downsizing of imaging devices has been demanded. Therefore, in order to reduce the size of the imaging apparatus, an electrostrictive actuator is used as an actuator for an autofocus and zoom mechanism.

For example, as disclosed in Patent Document 1, the electrostrictive actuator is installed in a shape wound around the outer periphery of the guide shaft. The electrostrictive actuator extends in the guide axis direction according to the applied voltage, and moves the lens frame in the guide axis direction.
JP 2003-215429 A

  In the optical device disclosed in Patent Document 1, the moving distance of the lens frame coincides with the extending length of the electrostrictive actuator of the optical device. In order to further increase the moving distance of the lens frame, it is necessary to further extend the electrostrictive actuator, in other words, to apply a high voltage to the electrostrictive actuator. However, when the voltage applied to the electrostrictive actuator increases, the insulation, withstand voltage, and the size of the drive circuit of the electrostrictive actuator become problems.

  For example, since the electrostrictive actuator disclosed in Patent Document 1 is arranged on the guide pillars installed at both ends of the lens frame, when the imaging device is downsized, a sufficient gap is secured between the electrostrictive actuators. Becomes difficult. Therefore, there is a problem that it is difficult to achieve good insulation and it is difficult to cope with downsizing.

  A method of dealing with the problems of insulation and pressure resistance by lowering the voltage applied to the electrostrictive actuator is also conceivable. In order to increase the displacement amount of the electrostrictive actuator at a low voltage, there is a method in which the elastomer used for the electrostrictive actuator is formed in multiple layers and the film thickness is reduced. However, there is a limit to the reduction in thickness and the manufacturing cost increases, so it is actually difficult to adopt this method.

  Therefore, in order to cope with the recent downsizing of the image pickup apparatus, it is necessary to reduce the voltage applied to the actuator after securing a predetermined amount of displacement of the actuator of the optical apparatus. In order to reduce the size of the optical device, it is also necessary to simplify the power transmission mechanism and reduce the number of parts.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide an optical device that is driven at a low voltage and has a small number of components, and an imaging device using the optical device.

In order to achieve the above object, an optical device according to the first aspect of the present invention provides:
A lens barrel,
A lens holder installed in the lens barrel, holding the lens, and movable in the optical axis direction of the lens;
An optical device including an actuator installed in the lens barrel and deformed in accordance with an applied voltage so as to abut one end of the lens holder in the optical axis direction,
The actuator includes an insulating film, electrodes formed on both surfaces of the insulating film, and a polymer layer formed on the insulating film and the electrode,
The lens holder uses a component in the optical axis direction of deformation according to the applied voltage of the actuator, moves in the optical axis direction,
The insulating film, the electrode, and the polymer layer of the actuator are each formed in a ring shape and laminated in the optical axis direction, and the width of the electrode is the insulating film and the polymer layer. It may be smaller than the width of the layer.

  The actuator may be deformed so that the insulating film and the polymer layer around the electrode are raised in the optical axis direction by attracting the electrode according to a difference in polarity of the applied voltage.

  The optical device may further include a biasing member that applies a biasing force for returning the lens holder to the initial position.

  A guide for guiding the movement of the lens holder in the optical axis direction may be formed on the inner wall of the lens barrel.

In order to achieve the above object, an imaging apparatus according to the second aspect of the present invention provides:
An optical device according to a first aspect;
A substrate on which the optical device is installed;
And an image pickup device disposed on the substrate.

  The present invention can provide an optical device that is driven at a low voltage and has a small number of components, and an imaging device using the optical device.

  An optical device 10 and an imaging device 20 according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a partial cross-sectional view of the optical device 10. FIG. 2 is a cross-sectional view of the optical device 10, and FIG. 3 is an exploded perspective view of the optical device 10.

  The imaging device 20 according to the embodiment of the present invention includes an optical device 10, an imaging element 21, and a substrate 22. As shown in FIG. 1, the optical device 10 is installed on a substrate 22 on which an image sensor 21 is arranged.

  As shown in FIG. 1, the optical device 10 includes an actuator 11, a lens holder 12, lenses 13 a to 13 c, a lens barrel 14, a cover 15, and a spring 16.

  As shown in FIG. 5A, the actuator 11 includes an insulating film 51, an electrode 52 formed on each of the opposing surfaces of the insulating film 51, and a polymer material formed so as to cover the insulating film 51 and the electrode 52. Layer (hereinafter referred to as polymer layer) 53.

  The insulating film 51 is made of a polymer material (elastomer) that exhibits rubber-like elasticity near normal temperature, such as silicon resin, acrylic foam, or the like. As shown in FIGS. 1 and 2, the insulating film 51 is formed in an annular shape, and the width of the insulating film 51 is substantially the same as the width of the bottom surface of the lens holder 12 and the width of the groove 14 a of the lens barrel 14. It is formed.

  The electrodes 52 are made of, for example, carbon black, gold, silver, aluminum or the like having stretchability and conductivity, and are formed on opposite surfaces (both sides) of the insulating film 51 as shown in FIG. Is done. As shown in FIGS. 1 and 2, the electrode 52 is also annular like the insulating film 51, and the width of the electrode 52 is smaller than the width of the insulating film 51 and the polymer layer 53. A power supply (not shown) is attached to the electrode 52 and connected to a drive circuit (not shown), and a voltage is applied in accordance with an input from a control unit (not shown).

  The polymer layer 53 is made of, for example, an elastomer, silicon resin, acrylic foam, or the like that is softer than the insulating film 51. The polymer layer 53 is formed in layers on the insulating film 51 and the electrode 52 so as to cover the insulating film 51 and the electrode 52 as shown in FIG. As shown in FIGS. 1 and 2, the polymer layer 53 has an annular shape like the insulating film 51 and the electrode 52, and the width of the polymer layer 53 is formed substantially the same as the width of the insulating film 51. The polymer layer 53 is formed thicker than the insulating film 51. One surface of the polymer layer 53 is in contact with one surface (one end surface in the optical axis direction) of the lens holder 12. The other surface of the polymer layer 53 is in contact with the groove 14 a of the lens barrel 14.

  When the voltage applied between the electrodes 52 of the actuator 11 having such a configuration is increased from the initial state (0), the electrodes 52 are attracted by electrostatic attraction as shown in FIG. 5B, for example. Since the electrode 52 of this embodiment has a smaller width than the insulating film 51, the insulating film 51 is pushed out to the periphery of the electrode 52 by attracting the electrodes 52, and accordingly, the electrode 52 is spread in the surface direction. The insulating film 51 around the electrode 52 rises in the vertical direction by ta2-ta1. The polymer layer 53 formed on the opposing surface of the electrode 52 is expanded in the surface direction along with the attracting electrode 52. The polymer layer 53 around the electrode 52 swells in the vertical direction by tb2-tb1. As a result, the actuator 11 as a whole rises in the vertical direction by (tb2-tb1) × 2 + (ta2-ta1). The lens holder 12 moves in the optical axis direction as shown in FIG. 4 using the component in the optical axis direction when the peripheral portion of the electrode 52 of the actuator 11 is deformed so as to rise.

  Further, when the voltage applied between the electrodes 52 of the actuator 11 is changed to 0, the inquiry between the electrodes 52 can be stopped. If the inquiry stops, the insulating film 51 and the polymer layer 53 return to the initial state shown in FIG. 5A, and the lens holder 12 also returns to the initial position. Here, in the present embodiment, the urging force is applied to the lens holder 12 by the spring 16, so that the actuator 11 quickly returns to the initial position by the urging force.

  The lens holder 12 has a cylindrical shape, and holds the lenses 13a to 13c inside thereof. One surface of the polymer layer 53 of the actuator 11 is in contact with the surface opposite to the bottom surface of the lens holder 12. The lens holder 12 has a groove 12a on the bottom surface, and one end of a spring 16 is installed on the surface opposite to the bottom surface of the groove 12a. The width of the groove 12a and the width of the actuator 11 are formed substantially the same. When the lens holder 12 moves in the optical axis direction, the distance between the lenses 13a to 13c and the image sensor 21 is adjusted to perform focus adjustment.

  The lens barrel 14 has a cylindrical shape and is installed on the substrate 22. The lens barrel 14 includes a groove 14a inside the bottom surface. The other surface of the polymer layer 53 of the actuator 11 is installed in the groove portion 14a. The width of the groove 14a and the width of the actuator 11 are formed substantially the same. A cover 15 is fixed to the other end of the lens barrel 14. The cover 15 includes a groove portion 15a, and the other end of the spring 16 is installed in the groove 15a.

  The image sensor 21 converts an optical image of a subject into an electrical signal. The imaging element is composed of a CCD (Charge Coupled Device), a CMOS (Complementary Metal Oxide Semiconductor) image sensor, or the like, and is disposed on the substrate 22 as shown in FIG.

  In the optical device 10 having the above configuration, when the voltage applied between the electrodes 52 of the actuator 11 is increased from 0, the electrodes 52 of the actuator 11 attract each other by electrostatic attraction, so that the insulating film 51 and The polymer layer 53 rises up and down in the optical axis direction. Thereby, the lens holder 12 is pushed up in the optical axis direction. When the voltage applied to the actuator 11 is returned to the initial state, the contact between the electrodes 52 stops, so that the insulating film 51 and the polymer layer 53 return to the initial state. At this time, the urging force acts in the direction of returning from the spring 16 to the lens holder 12 in the initial state, so that the actuator 11 quickly returns to the initial state.

  As described above, since the optical device 10 uses the actuator 11 in which the polymer layer 53 that is softer than the insulating film 51 is formed on the insulating film 51 and the electrode 52, a change amount in the optical axis direction can be obtained at a low voltage. . Further, since one surface of the actuator 11 is in contact with the lens holder 12, the deformation of the actuator 11 can be directly transmitted to the lens holder 12. Therefore, the focal length between the lenses 13a to 13c and the image sensor 21 can be adjusted by moving the lens holder 12 with a small number of parts without using power transmission means.

The present invention is not limited to the above-described embodiments, and various modifications and applications are possible.
For example, in the above-described embodiment, the configuration in which the spring 16 is disposed around the lens holder 12 as the biasing member that applies the biasing force to the lens holder 12 has been described as an example. Other than the spring can be adopted as long as the urging force for returning to the initial position is given.

  Further, in order to make the movement direction of the lens holder 12 constant, for example, a groove may be formed on the inner wall of the lens barrel 14, and a convex portion that meshes with the groove may be formed around the lens holder 12. A groove may be formed around the lens holder 12, and a convex portion that meshes with the groove may be formed on the inner wall of the lens barrel 14.

  In the above-described embodiment, the case where the number of lenses held by the lens holder 12 is three has been described as an example. However, the present invention is not limited to this. Further, it is not necessary to hold three pieces in one lens holder 12, and it is also possible to employ a configuration in which a plurality of lens holders or the like holding one lens are arranged and the actuator 11 is arranged in each.

  In the above-described embodiment, the actuator 11 has been described by taking as an example the case where the initial state and the voltage are changed in two stages. However, the present invention is not limited to this, and the voltage applied to the actuator 11 is set in multiple stages. It is also possible to change the amount of change of the actuator 11 in multiple stages and change the lens holder 12 in multiple stages in the optical axis direction of the lens.

It is a fragmentary sectional view of an optical device concerning an embodiment of the invention. It is sectional drawing of the optical apparatus which concerns on embodiment of this invention. It is a disassembled perspective view of the optical apparatus which concerns on embodiment of this invention. It is sectional drawing at the time of applying a voltage to the optical apparatus which concerns on embodiment of this invention. It is a figure which shows typically the actuator at the time of enlarging an initial state and an applied voltage.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Optical apparatus 11 Actuator 12 Lens holder 13a, 13b, 13c Lens 14 Lens barrel 15 Cover 16 Spring 20 Imaging device 21 Imaging element 22 Substrate 51 Insulating film 52 Electrode 53 Polymer layer

Claims (5)

A lens barrel,
A lens holder installed in the lens barrel, holding the lens, and movable in the optical axis direction of the lens;
An optical device including an actuator installed in the lens barrel and deformed in accordance with an applied voltage so as to abut one end of the lens holder in the optical axis direction,
The actuator includes an insulating film, electrodes formed on both surfaces of the insulating film, and a polymer layer formed on the insulating film and the electrode,
The lens holder uses a component in the optical axis direction of deformation according to the applied voltage of the actuator, moves in the optical axis direction,
The insulating film, the electrode, and the polymer layer of the actuator are each formed in a ring shape and laminated in the optical axis direction, and the width of the electrode is the insulating film and the polymer layer. An optical device characterized by being smaller than the width of the layer.   3. The actuator according to claim 1, wherein the actuator is deformed so that the insulating film and the polymer layer around the electrode rise in the optical axis direction due to a difference in polarity of the applied voltage. Optical device.   The optical apparatus according to claim 1, further comprising a biasing member that applies a biasing force for returning the lens holder to an initial position.   4. The optical device according to claim 1, wherein a guide for guiding the movement of the lens holder in the optical axis direction is formed on an inner wall of the lens barrel. 5. An optical device according to any one of claims 1 to 4,
A substrate on which the optical device is installed;
An image pickup apparatus comprising: an image pickup element disposed on the substrate.

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