JP2006301202A - Optical device and digital camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact optical device using a polymer actuator as a driving part, capable of accurately controlling displacement amount, and having simple constitution. <P>SOLUTION: An imaging unit 100 is equipped with: a lens group 146 forming the optical image of a subject; a moving lens frame 140 holding the lens group 146; guide shafts 131 and 132 supporting the moving lens frame 140 movably; a fixed lens frame 110 and a cover member 120 holding the guide shafts 131 and 132; a coil spring 148 energizing the moving lens frame 140 toward the cover member 120; the polymer actuator 150 moving the moving lens frame 140 toward the fixed lens frame 110; an imaging device 182; and a base plate 180 holding the imaging device 182. The moving lens frame 140 has a sleeve part 141 to which the guide shaft 131 is fit and a U-shaped groove 142 which receives the guide shaft 132, and is arranged nearer to the side of the imaging device 182 than 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 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.
Japanese Patent Publication No. 7-4075 Japanese Patent No. 2768869

  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. For example, application to a drive unit of a small optical device is conceivable. However, the displacement amount of the polymer actuator increases in a high temperature environment. Therefore, when applied to a small optical device, the polymer actuator is easily affected by the heat generated by the image sensor, and it is difficult to control the displacement with high accuracy. In order to control the amount of displacement with high accuracy, a temperature sensor and a temperature compensation circuit are required. This is a factor that hinders downsizing of the optical device.

  The present invention has been made in view of such a situation, and an object of the present invention is to provide a small optical device with a simple configuration capable of accurately controlling the amount of displacement using a polymer actuator in the drive unit. That is.

  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 an image sensor for converting an optical image formed by the optical element into digital image data are provided, and the optical element is disposed closer to the image sensor than the polymer actuator.

  ADVANTAGE OF THE INVENTION According to this invention, a small optical apparatus with a simple structure which can control the displacement amount which used the polymer actuator for the drive part with high precision 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. FIG. 6 is an exploded perspective view of the imaging unit 100 shown in FIG. 5 as viewed from the opposite side.

  As shown in FIGS. 5 and 6, the imaging unit 100 includes a 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 a movable lens frame 140. An optical image formed by the two guide shafts 131 and 132 that movably support the lens, the fixed lens frame 110 that holds the guide shafts 131 and 132 in cooperation with each other, and the lens group 146 is a digital image. An image sensor 182 for converting data and a substrate 180 that holds the image sensor 182 are provided.

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

  The coil spring 148 is inserted between the fixed lens frame 110 and the movable lens frame 140 through the guide shaft 131. When the lid member 120 is attached to the fixed lens frame 110, the coil spring 148 is compressed by the fixed lens frame 110 and the movable lens frame 140. As a result, the coil spring 148 attaches the movable lens frame 140 toward the lid member 120. To force.

  The polymer actuator 150 is elongated and curved along the edge of the movable lens barrel 140. One end of the polymer actuator 150 is fixed to the lid member 120 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. 7, 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. 7, the polymer actuator 150 has an upper end fixed, and a lower end being a free end. As shown in FIG. 7, the polymer actuator 150 bends in response to voltage application between the two electrodes 152 and 153, and the bending direction is a voltage applied between the two electrodes 152 and 153. Depends on the orientation.

  5 and 6, the polymer actuator 150 bends in response to voltage application, the free end moves away from the lid member 120, and pushes the movable lens frame 140. As a result, the movable lens frame 140 is moved toward the fixed lens frame 110 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 has a positioning part 111 for positioning the lens group 146, and the lid member 120 has a positioning part 125 for positioning the lens group 146.

  8 and 9 schematically show how the movable lens frame 140 is moved by the polymer actuator 150. FIG. FIG. 8 shows the position of the movable lens frame 140 when no voltage is applied to the polymer actuator 150, and FIG. 9 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 125 of the lid member 120 via the polymer actuator 150 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 fixed lens frame 110, and the movable lens frame 140 is moved in a direction approaching the fixed lens frame 110. The movement of the movable lens frame 140 ends when the movable lens frame 140 contacts the positioning unit 111 of the fixed lens frame 110.

  That is, in a state where a voltage is applied to the polymer actuator 150, the movable lens frame 140 is pressed against the positioning unit 111 of the fixed lens frame 110 by the polymer actuator 150 as shown in FIG. 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 polymer actuator 150 pressed against the positioning part 125 and the positioning part 111, and t is the thickness of the plate-like part (the part excluding the sleeve part 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 fixed lens frame 110 by the coil spring 148 and returns to the state of FIG.

  That is, the positioning unit 125 contacts the moving lens frame 140 via the polymer actuator 150 and prevents the moving lens frame 140 from moving toward the lid member 120 by the coil spring 148, thereby relatively moving the lens group 146 from the subject. Position in the first position. Further, the positioning unit 111 contacts the moving lens frame 140 and prevents the movement of the moving lens frame 140 in the direction away from the lid member 120 by the polymer actuator 150, thereby positioning the lens group 146 at a second position relatively far from the subject. To do. That is, the positioning unit 111 of the fixed lens frame 110, the positioning unit 125 of the lid member 120, and 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 125. Therefore, the lens group 146 can be positioned with high accuracy at two predetermined positions.

  FIG. 10 is a plan view of the movable lens barrel 140 shown in FIGS. 5 and 6 as viewed from the lid member 120 side.

  In FIG. 10, one end of the polymer actuator 150 is fixed to the lid member 120 with the support point P1 as the center, and the other end moves about the action point P2 by deformation or bending due to voltage application. The mirror frame 140 is pushed. As shown in FIG. 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 the circle passing through the center of the guide shaft 131 with the optical axis as the center. 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, the part where the movable lens frame 140 is urged by the coil spring 148 is on the back side of the sleeve part 141, is located near the contact part with the guide shaft 131, and is located closer to the action point P2 than the support point P1. ing.

  The image sensor 182 generates heat when driven. Further, the displacement amount of the polymer actuator 150 changes depending on the ambient temperature. A temperature sensor and a temperature compensation circuit are required to control the displacement with high accuracy. This is a factor preventing miniaturization.

  In the imaging unit 100 of this embodiment, the movable lens frame 140 is disposed on the imaging element 182 side with respect to the polymer actuator 150. The image sensor 182 generates heat when driven. Since the polymer actuator 150 is located relatively far from the image sensor 182, it is difficult to be heated by the heat generated by the image sensor 182. For this reason, the high temperature of the polymer actuator 150 can be avoided. Therefore, the amount of displacement can be controlled with high accuracy without requiring a temperature sensor and a temperature compensation circuit.

  Thereby, the imaging unit 100 can accurately control the position of the lens group 146 held by the movable lens frame 140 moved by the polymer actuator 150 between the first position and the second position.

  Subsequently, a modification of the present embodiment will be described. FIG. 11 is an exploded perspective view of an imaging unit according to a modification of the present embodiment. In FIG. 11, members denoted by the same reference numerals as those illustrated in FIGS. 5 and 6 are similar members, and detailed description thereof is omitted.

  As shown in FIG. 11, the imaging unit 200 of the present modification includes a transparent heat insulating member 118 such as heat insulating glass disposed between the movable lens frame 140 and the image sensor 182. The heat insulating member 118 has good heat insulating properties and suppresses conduction of heat generated by the image sensor 182 and heat generated by an electric circuit related to the image sensor 182 to the polymer actuator 150. As a result, the polymer actuator 150 is less likely to be warmed. For this reason, it is better to avoid the high temperature of the polymer actuator 150. Therefore, the displacement amount can be controlled more accurately and accurately without requiring a temperature sensor and a temperature compensation circuit.

  Thereby, the imaging unit 200 can accurately control the position of the lens group 146 held by the movable lens frame 140 moved by the polymer actuator 150 between the first position and the second position.

  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. It is the disassembled perspective view which looked at the imaging unit 100 shown by FIG. 5 from the other side. The structure of the polymer actuator shown by FIG. 5 and FIG. 6 is shown typically. FIG. 7 shows the position of the movable lens frame when no voltage is applied to the polymer actuator shown in FIGS. 5 and 6. FIG. FIG. 7 shows the position of the movable lens frame when a voltage is applied to the polymer actuator shown in FIG. 5 and FIG. 6. It is the top view which looked at the movable lens frame shown by FIG. 5 and FIG. 6 from the cover member side. It is a disassembled perspective view of the imaging unit by the modification of embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Imaging unit, 110 ... Fixed lens frame, 111 ... Positioning part, 115 ... Opening, 118 ... Heat insulation member, 120 ... Cover member, 121 ... Opening, 125 ... Positioning part, 131 ... Guide shaft, 132 ... Guide shaft, 140 DESCRIPTION OF SYMBOLS ... Moving lens frame, 141 ... Sleeve part, 142 ... U groove, 143 ... Escape 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 (7)

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;
An image sensor for converting an optical image formed by the optical element into digital image data;
An optical device, wherein the optical element is disposed closer to the imaging element than the polymer actuator.   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 optical element by deformation of the polymer part by application of voltage.   The said polymer actuator is provided with the water-containing ion exchange membrane as a polymer part, and a pair of electrode which is provided in the both sides of the said ion exchange membrane, and opposes via the said ion exchange membrane. Optical device.   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.   The optical apparatus according to claim 1, further comprising a heat insulating member that suppresses conduction of heat generated by the image sensor to the polymer actuator.   The optical device according to claim 1, further comprising a heat insulating member that suppresses the polymer actuator of heat generated by an electric circuit related to the imaging element.   A digital camera comprising the optical device according to any one of claims 1 to 6.

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