JP2006293007A - Optical device and digital camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact optical device having simple constitution for making an optical element move. <P>SOLUTION: An imaging unit 100 is equipped with a lens group 146 for forming the optical image of a subject; a moving lens frame 140 for holding the lens group 146; guide shafts 131 and 132 for movably supporting the moving lens frame 140; a fixed lens frame 110 and a cover member 120 for holding the guide shafts 131 and 132; a coil spring 148 energizing the moving lens frame 140 toward the fixed lens frame 110; a polymer actuator 150 for moving the moving lens frame 140 toward the cover member 120; an imaging device 182; and a base plate 180 for holding the imaging device 182. The moving lens frame 140 has a sleeve part 141, in which the guide shaft 131 is fit and a U-shaped groove 142 for receiving the guide shaft 132. The point of application of the polymer actuator 150 pressing the moving lens frame 140 is positioned nearer to the guide shaft 131 than to the support point of the polymer actuator 150. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical device for photographing a subject.

  Japanese Patent Application Laid-Open No. 8-114736 discloses a drive mechanism that relatively moves an imaging element and an optical element along an optical axis by a piezoelectric element or a stepping motor formed in a long shape.

Japanese Patent Publication No. 7-4075 and Japanese Patent No. 2768869 disclose a polymer actuator that deforms by applying a potential difference to electrodes provided on both surfaces of an ion exchange membrane.
JP-A-8-114736 Japanese Patent Publication No. 7-4075 Japanese Patent No. 2768869

  A piezoelectric actuator requires a high voltage of several hundred volts to obtain a large displacement of several millimeters due to deformation of the piezoelectric actuator itself. For this reason, in a portable optical device (for example, a digital camera), a booster circuit for obtaining a high voltage is necessary, which is an obstacle to downsizing. Further, the stepping motor is an obstacle to downsizing due to its size.

  Further, in the driving mechanism disclosed in Japanese Patent Laid-Open No. 8-114736, the fulcrum of the piezoelectric actuator is located outside the lens frame, which is also an obstacle to downsizing.

  In a polymer actuator using an ion exchange membrane, a displacement of several millimeters can be obtained by applying a voltage of several volts, and a booster circuit for obtaining a higher voltage than that of a piezoelectric actuator is not required. However, Japanese Patent Publication No. 7-4075 and Japanese Patent No. 2768869 do not disclose any application to optical elements.

  The present invention has been made in consideration of such a situation, and an object of the present invention is to provide a small optical device with a simple configuration for moving an optical element.

  An optical device according to the present invention includes an optical element for forming an optical image of a subject, a support mechanism for supporting the optical element in a predetermined direction so as to be movable, and a height for moving the optical element. A molecular actuator; and the support mechanism has a moving member that holds the optical element and a guide shaft that movably supports the moving member, and one end of the polymer actuator is fixed as a support point The other end moves the moving member as an action point, and the action point is located closer to the guide shaft than the support point.

  According to the present invention, a small optical device with a simple configuration for moving an optical element is provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  The present embodiment is directed to a digital camera that is detachably incorporated in a PDA (Personal Digital Assistant). FIG. 1 is a schematic perspective view of a PDA in which the digital camera of this embodiment is incorporated. FIG. 2 shows a state in which the digital camera of this embodiment is detached from the PDA. FIG. 3 is a perspective view of the digital camera of FIG. 2 as viewed from the subject side. FIG. 4 shows an imaging unit of the imaging unit of the digital camera.

  As shown in FIGS. 1 and 2, the PDA 500 includes a liquid crystal monitor 510 and various operation buttons (operation switches) 520 on the front surface (the left surface in the figure), and a card-like recording on the upper surface. A card slot 530 is provided for exchangeable connection with peripheral devices such as media. As shown in FIGS. 2 and 3, the digital camera 600 includes an imaging unit 610 and a plate-like insertion unit 620 inserted into the PDA 500. The insertion portion 620 is inserted into the card slot 530 of the PDA 500 and is electrically connected to the PDA 500 via a connection connector on the bottom surface. As shown in FIG. 4, the imaging unit 610 of the digital camera 600 includes an imaging unit 100, and the imaging unit 100 can perform operations such as focusing (macro switching) and shooting by operating the PDA 500.

  FIG. 5 is an exploded perspective view of the imaging unit 100 of the digital camera 600 shown in FIG.

  As shown in FIG. 5, the imaging unit 100 can move the lens group 146 that is an optical element for forming an optical image of a subject, a movable lens frame 140 that holds the lens group 146, and the movable lens frame 140. An optical image formed by the two guide shafts 131 and 132 supported by the lens, the fixed lens frame 110 and the cover member 120 that jointly hold the guide shafts 131 and 132, and the lens group 146 is converted into digital image data. An image sensor 182 for holding the image sensor, and a substrate 180 for holding the image sensor 182.

  The lid member 120 has an opening 121 through which light from the subject passes, and is attached to the front side of the fixed lens frame 110 by screwing. The fixed lens frame 110 has an opening 115 through which light from the subject passes. The substrate 180 is attached to the rear side of the fixed lens frame 110 by screwing. The image sensor 182 receives light from the subject through the opening 121 of the lid member 120 and the opening 115 of the fixed lens frame 110.

  The lens group 146 is fixed to the movable lens frame 140 by bonding or the like. One end of the guide shaft 131 and the guide shaft 132 is fixed to the fixed lens frame 110 by press-fitting or the like, and the other end is held by the lid member 120. The guide shaft 131 and the guide shaft 132 are supported in parallel with each other by the fixed lens frame 110 and the lid member 120. The movable lens frame 140 has a sleeve portion 141 into which the guide shaft 131 is fitted and a U groove 142 that receives the guide shaft 132. The U-groove 142 of the movable lens frame 140 engages with the guide shaft 132 and restricts the rotation of the movable lens frame 140 around the guide shaft 131. The sleeve part 141 and the U-groove 142 of the movable lens frame 140 are movable along the guide shaft 131 and the guide shaft 132, respectively. The movable lens frame 140 is arranged on one axis parallel to the two guide shafts 131 and 132. Can move along. That is, the fixed lens frame 110, the lid member 120, the two guide shafts 131 and 132, and the movable lens frame 140 constitute a support mechanism that guides the lens group 146 in a predetermined direction and is movably supported. Desirably, the lens group 146 is fixed so that its optical axis is parallel to the moving direction of the movable lens frame 140, and the lens group 146 is moved along the optical axis as the movable lens frame 140 moves. .

  The imaging unit 100 includes a coil spring 148 that urges the movable lens frame 140 toward the fixed lens frame 110, and a polymer actuator that moves the movable lens frame 140 toward the lid member 120 against the urging force of the coil spring 148. 150.

  The coil spring 148 passes through the guide shaft 131 and is disposed between the lid member 120 and the sleeve portion 141 of the movable lens frame 140. In a state in which the lid member 120 is attached to the fixed lens frame 110, the coil spring 148 is compressed by the lid member 120 and the sleeve portion 141 of the movable lens frame 140. As a result, the coil spring 148 causes the movable lens frame 140 to be fixed to the fixed lens frame 110. Energize towards.

  The polymer actuator 150 is elongated and curved along the edge of the movable lens frame 140. One end of the polymer actuator 150 is fixed to the fixed lens frame 110 by a pin 158, and the other end is a free end. The movable lens frame 140 has an escape portion 143 to avoid contact with the pin 158.

  The polymer actuator 150 is disclosed in, for example, Japanese Patent Publication No. 7-4075 and Japanese Patent No. 2768869. The polymer actuator 150 has a polymer portion that deforms in response to application of a voltage. More specifically, as shown in FIG. 6, the polymer actuator 150 includes a water-containing ion exchange membrane 151 as a polymer portion, and a pair of electrodes 152 and 153 provided on both sides of the ion exchange membrane 151. ing. The electrode 152 and the electrode 153 are opposed to each other with the ion exchange membrane 151 interposed therebetween.

  In FIG. 6, the polymer actuator 150 has an upper end fixed, and a lower end being a free end. As shown in FIG. 6, the polymer actuator 150 bends in response to voltage application between the two electrodes 152 and 153, and the bending direction is the voltage applied between the two electrodes 152 and 153. Depends on the orientation.

  In FIG. 5, the polymer actuator 150 bends in response to voltage application, the free end moves away from the fixed lens frame 110, and pushes the movable lens frame 140. As a result, the movable lens frame 140 is moved toward the lid member 120 against the urging force of the coil spring 148.

  That is, in other words, the polymer actuator 150 has a polymer part that deforms in response to application of a voltage, and moves the movable lens frame 140 by deformation of the polymer part by application of voltage. The coil spring 148 biases the movable lens frame 140 in the direction opposite to the moving direction of the movable lens frame 140 by the polymer actuator 150.

  The fixed lens frame 110 includes a positioning unit 111 and a positioning unit 112 for positioning the lens group 146. Further, the movable lens frame 140 has a convex portion 144 protruding outward near the sleeve portion 141. The convex part 144 of the movable lens frame 140 is located between the positioning part 111 and the positioning part 112.

  7 and 8 schematically show how the movable lens frame 140 is moved by the polymer actuator 150. FIG. FIG. 7 shows the position of the movable lens frame 140 when no voltage is applied to the polymer actuator 150, and FIG. 8 shows the position of the movable lens frame 140 when the voltage is applied to the polymer actuator 150. Indicates the position.

  In a state where no voltage is applied to the polymer actuator 150, the movable lens frame 140 is pressed against the positioning portion 111 of the fixed lens frame 110 by the coil spring 148, as shown in FIG. As a result, the lens group 146 is positioned at a distance L from the back surface (right side in the drawing) of the fixed lens frame 110.

  When a voltage is applied to the polymer actuator 150, the polymer actuator 150 bends toward the lid member 120, and the movable lens frame 140 is moved in a direction approaching the lid member 120. The movement of the movable lens frame 140 ends when the convex portion 144 of the movable lens frame 140 contacts the positioning portion 112 of the fixed lens frame 110.

  That is, in a state where a voltage is applied to the polymer actuator 150, the convex part 144 of the movable lens frame 140 is pressed against the positioning part 112 of the fixed lens frame 110 by the polymer actuator 150 as shown in FIG. Yes. As a result, the lens group 146 is positioned at a distance L + 1−t from the back surface (right side in the drawing) of the fixed lens frame 110. Here, l is the distance between the positioning portion 111 and the positioning portion 112, and t is the thickness of the plate-like portion (the portion excluding the sleeve portion 141) of the movable lens frame 140.

  When the voltage application to the polymer actuator 150 is released, the movable lens frame 140 is moved away from the lid member 120 by the coil spring 148 and returns to the state of FIG.

  That is, the positioning unit 111 contacts the moving lens frame 140 and prevents the moving lens frame 140 from moving away from the lid member 120 by the coil spring 148 to position the lens group 146 at a first position relatively far from the subject. . In addition, the positioning unit 112 contacts the convex portion 144 of the movable lens frame 140 and prevents the movement of the movable lens frame 140 in the direction approaching the lid member 120 by the polymer actuator 150, thereby moving the lens group 146 relatively close to the subject. Position to the position. That is, the positioning part 111 and the positioning part 112 of the fixed lens frame 110 and the convex part 144 of the moving lens frame 140 constitute a limiting mechanism that limits the movement stroke of the lens group 146 by the polymer actuator 150.

  By this limiting mechanism, the position of the movable lens frame 140 is determined not by the deformation amount of the polymer actuator 150 but by the positioning unit 111 and the positioning unit 112. Therefore, the lens group 146 can be positioned with high accuracy.

  9 is a perspective view of the movable lens frame 140 shown in FIG. 5 as viewed from the image sensor 182 side. FIG. 10 is a perspective view of the movable lens frame 140 shown in FIG. FIG.

  9 and 10, one end portion of the polymer actuator 150 is fixed to the fixed lens frame 110 with the support point P1 as the center, and the other end portion has an action point P2 due to deformation or bending by voltage application. The movable lens frame 140 is pushed around the center. As shown in FIGS. 9 and 10, the action point P <b> 2 of the polymer actuator 150 is located closer to the guide shaft 131 than the support point P <b> 1 of the polymer actuator 150.

  Further, as shown in FIG. 10, the polymer actuator 150 avoids the optical path of light passing through the lens group 146 in the projection onto the plane orthogonal to the optical axis of the lens group 146, for example, a circle centered on the optical axis. It extends along the circumference. Further, in the projection onto the plane orthogonal to the optical axis of the lens group 146, both the support point P1 and the action point P2 are located inside a circle C centering on the optical axis and passing through the center of the guide shaft 131. Therefore, at least the inner peripheral portion of the polymer actuator 150 is located inside a circle C that passes through the center of the guide shaft 131 with the optical axis as the center. Thereby, the imaging unit 100 is miniaturized.

  More preferably, the entire polymer actuator 150 is located inside a circle C that passes through the center of the guide shaft 131 with the optical axis as the center. In this case, the imaging unit 100 can be further downsized.

  Further, a portion where the movable lens frame 140 is urged by the coil spring 148 is a sleeve portion 141, which is located near the contact portion with the guide shaft 131, and is located near the action point P2 rather than the support point P1. .

  In the present embodiment, an example of a digital camera that can be attached to and detached from the PDA has been shown. Examples of the usage of digital cameras and mobile phones include skiing and climbing. In such a situation, the temperature may be below freezing at the time of photographing, and there is a possibility that the responsiveness of the polymer actuator 150 is lowered, and that the polymer actuator 150 becomes inoperable due to freezing.

  In order to avoid such a problem, a method of incorporating a heater so that the polymer actuator 150 does not become a low temperature can be considered. However, this method leads to an increase in the size of the device and an increase in battery consumption.

  In the imaging unit 100 of the present embodiment, the polymer actuator 150 is disposed on the imaging element 182 side with respect to the movable lens frame 140 that is not easily affected by the external environment. The image sensor 182 generates heat when driven, and the polymer actuator 150 is warmed by the heat generated by the image sensor 182. For this reason, it can be avoided that the polymer actuator 150 becomes low temperature even in a low temperature environment.

  Thereby, the imaging unit 100 operates stably even in a low temperature environment without separately providing a heater.

  In this embodiment, the heat generated by the image sensor 182 is used to warm the polymer actuator 150. However, an electric circuit that generates a relatively large amount of heat due to the image sensor 182 such as a power supply circuit or a CPU is used. Exotherm may be used.

  The embodiments of the present invention have been described above with reference to the drawings. However, the present invention is not limited to these embodiments, and various modifications and changes can be made without departing from the scope of the present invention. Also good.

  In the embodiment described above, the lens group 146 is moved along the optical axis for controlling the in-focus position. However, the lens group is moved along the optical axis for controlling the focal length (zoom). It can also be applied to configuration. Further, in order to correct camera shake and shooting direction, it may be moved in a direction different from the optical axis, for example, a direction orthogonal to the optical axis.

1 is a schematic perspective view of a PDA in which a digital camera according to an embodiment of the present invention is incorporated. The state which removed the digital camera of embodiment of this invention from PDA is shown. FIG. 3 is a perspective view of the digital camera shown in FIG. 2 as viewed from the subject side. 4 illustrates an imaging unit of an imaging unit of the digital camera illustrated in FIG. 3. It is a disassembled perspective view of the imaging unit of the digital camera shown by FIG. FIG. 6 schematically shows the configuration of the polymer actuator shown in FIG. 5. 6 shows the position of the movable lens frame when no voltage is applied to the polymer actuator shown in FIG. FIG. 6 shows the position of the movable lens frame when a voltage is applied to the polymer actuator shown in FIG. It is the perspective view which looked at the movable lens frame shown by FIG. 5 from the image sensor side. It is the top view which looked at the movable lens frame shown by FIG. 5 from the image pick-up element side.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Imaging unit, 110 ... Fixed lens frame, 111 ... Positioning part, 112 ... Positioning part, 115 ... Opening, 120 ... Cover member, 121 ... Opening, 131 ... Guide shaft, 132 ... Guide shaft, 140 ... Moving lens frame, 141 ... Sleeve part, 142 ... U-groove, 143 ... Escape part, 144 ... Convex part, 146 ... Lens group, 148 ... Coil spring, 150 ... Polymer actuator, 151 ... Ion exchange membrane, 152 ... Electrode, 153 ... Electrode, 158 ... Pin, 180 ... Substrate, 182 ... Image sensor, 500 ... PDA, 510 ... Liquid crystal monitor, 520 ... Operation button, 530 ... Card slot, 600 ... Digital camera, 610 ... Imaging part, 620 ... Inserting part, P1 ... Supporting point , P2 ... operating point.

Claims (12)

An optical element for forming an optical image of a subject;
A support mechanism for guiding and moving the optical element in a predetermined direction;
A polymer actuator for moving the optical element;
The support mechanism includes a moving member that holds the optical element, and a guide shaft that movably supports the moving member. The polymer actuator has one end fixed as a support point, and the other end. Moves the moving member as an action point, and the action point is located closer to the guide shaft than the support point.   2. The optical device according to claim 1, wherein the polymer actuator has a polymer part that deforms in response to application of a voltage, and moves the movable lens frame by deformation of the polymer part by application of voltage.   3. The polymer actuator according to claim 2, comprising a water-containing ion exchange membrane as a polymer portion, and a pair of electrodes provided on both sides of the ion exchange membrane and facing each other through the ion exchange membrane. , Optical device.   2. The optical device according to claim 1, wherein the support mechanism supports the optical element so as to be movable along an optical axis thereof.   2. The projection according to claim 1, wherein at least one of the action point and the support point is a circle passing through the center of the guide axis with the optical axis of the optical element as a center in projection onto a plane orthogonal to the optical axis of the optical element. Or an optical device located in a circle.   6. The optical device according to claim 5, wherein the polymer actuator extends while avoiding an optical path of light passing through the optical element.   2. The working point and the support point according to claim 1, wherein the action point and the support point are on or within a circle passing through the center of the guide portion axis with the optical axis of the optical element as a center in a plane orthogonal to the optical axis of the optical element. An optical device that is located.   8. The optical device according to claim 7, wherein the polymer actuator extends to avoid an optical path of light passing through the optical element.   2. The optical device according to claim 1, further comprising a biasing member for biasing the optical element in a direction opposite to a direction of movement of the optical element by the polymer actuator.   The optical device according to claim 9, wherein the portion where the moving member is urged by the urging member is located closer to the action point than the support point.   The optical device according to claim 10, wherein the portion where the moving member is urged by the urging member is located near a contact portion with the guide shaft.   A digital camera comprising the optical device according to any one of claims 1 to 11.

Images