JP2006058657A - Optical device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical device which does not use an actuator such as the conventional electromagnetic stepping motor, nor requires a motive power transmitting mechanism, and copes with the shortening of dimension in an optical axis direction. <P>SOLUTION: The optical device (30) is equipped with a lens for focusing (11) and lenses for variable power (3 and 4). The lens for focusing (11) advances in the optical axis direction by a 1st electrostrictive actuator (8b) elongated in the optical axis direction. Either lens for variable power (3 or 4) advances in the optical axis direction by a driving device equipped with a cam member (7). The cam member 7 is rotated by a 2nd electrostrictive actuator (8c) elongated in a periphery direction with an optical axis as center so as to make the lens for variable power (3 or 4) advance in the optical axis direction. The 1st electrostrictive actuator (8b) and the 2nd electrostrictive actuator (8c) are molded in circular-arc shapes having different radii, and arranged in parallel inside and outside. Thus, the optical device is made thin. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical device applied to a camera or the like, and more particularly to a mechanism for causing a lens to advance in the optical axis direction.

  A video camera such as a digital camera generally has a focus adjustment lens and a zoom lens, and an optical device that performs focus adjustment and zoom by moving these lenses forward and backward along the optical axis direction. I have. Here, electromagnetic stepping motors, voice coil motors, piezoelectric motors, and the like are used as actuators for driving these focus adjustment lenses and zooming lenses, and by using the force generated by these actuators, I am moving forward and backward. That is, the force of such an actuator is used to move the focus adjustment lens and the zoom lens in the optical axis direction through a power transmission mechanism such as a gear or a cam. However, in these actuators, the existence of the power transmission mechanism as described above has hindered downsizing of the entire apparatus. Further, there is a problem that is difficult to solve in order to reduce the size of the apparatus, for example, the actuator itself must be provided with a coil.

  Patent Document 1 has been proposed to solve the above problems. Patent Document 1 discloses an optical device that employs an electrostrictive actuator using an electrostrictive effect instead of the conventional actuator such as the electromagnetic stepping motor as described above, and simplifies and miniaturizes the device. ing.

JP 2003-215429 A

  However, in the optical device described in Patent Document 1, a lens is slidably supported by a main guide shaft and a sub guide shaft installed in parallel with the optical axis direction, and an electrostrictive actuator is attached along the main guide shaft. Yes. Here, since the lens supported by the main guide shaft and the sub guide shaft includes a focus adjustment lens and a zoom lens, a focus adjustment actuator and a zoom actuator are provided on the main guide shaft for each of these lenses. It is attached. Accordingly, at least a focus adjustment lens, a focus adjustment actuator, a zoom lens, and a zoom actuator are arranged in series in the optical axis direction. For this reason, the optical device described in Patent Document 1 requires a certain amount of dimension in the optical axis direction, and there is still room for improvement in terms of downsizing the device.

  Therefore, an object of the present invention is to provide an optical device that does not use an actuator such as a conventional electromagnetic stepping motor, does not require a power transmission mechanism, and can cope with shortening of the dimension in the optical axis direction.

  An optical device of the present invention that achieves such an object includes a focus adjustment lens, a variable power lens, a first electrostrictive actuator that extends in the optical axis direction, and a second electric force that extends in the circumferential direction around the optical axis. A distortion actuator, and either one of the focusing lens or the zoom lens is moved in the optical axis direction along with the extension operation of the first electrostriction actuator, and the other lens is The second electrostrictive actuator is moved in the optical axis direction in accordance with the extension operation (claim 1). Here, each of the first electrostrictive actuator and the second electrostrictive actuator includes a band-shaped electrostrictive actuator formed in an arc shape, and the first electrostrictive actuator is positioned so that one arc is located inside the other arc. It is desirable that the actuator and the second electrostrictive actuator are arranged in parallel inside and outside (Claim 2).

  That is, in the optical device of the present invention, one of the focusing lens and the variable power lens is moved in the optical axis direction by the first electrostrictive actuator extending in the optical axis direction, and the other lens is Movement in the optical axis direction is realized by a second electrostrictive actuator extending in the circumferential direction around the optical axis. From the viewpoint of thinning the device in such an optical device, it is not preferable that the two electrostrictive actuators are arranged in parallel in the optical axis direction, and the two electrostrictive actuators are arranged in a direction orthogonal to the optical axis direction. Is preferred. Therefore, for example, if the first and second electrostrictive actuators that are belt-shaped as described above are each formed into an arc shape and arranged in parallel inside and outside so that one arc is located inside the other arc, The size of the device in the optical axis direction does not become bulky, and the device can be thinned.

  Here, the electrostrictive actuator employed by the present invention has a plate-like configuration in which a highly flexible insulating film such as silicon is sandwiched between electrodes. In such an electrostrictive actuator, when a voltage is applied to the electrodes, the electrodes are attracted to each other and receive a force that crushes the insulating film. Thus, if a voltage is applied to the electrode without any constraint, the insulating film extends in the vertical direction and the horizontal direction. Therefore, the first electrostrictive actuator does not regulate the optical axis direction, but regulates the extension in the circumferential direction around the optical axis so as to extend only in the optical axis direction. The extension in the direction is restricted, and the extension in the circumferential direction around the optical axis is not restricted, and the extension is made only in the circumferential direction around the optical axis.

  Further, a lens holding member that holds a focus adjustment lens or a zoom lens and has a protrusion protruding in the radial direction of the lens, and light that passes through the peripheral wall of the cylindrical body whose axial direction coincides with the optical axis direction. A guide member formed with a longitudinal groove in the axial direction, and a groove that is rotatably held by the guide member and that engages with the protrusion on the peripheral wall of the cylindrical body whose axial direction coincides with the optical axis direction; And a cam member that rotates in accordance with the extension operation of the electrostrictive actuator.

  As the second electrostrictive actuator extending in the circumferential direction around the optical axis, the focus adjustment lens or the zoom lens is moved in the optical axis direction. It is conceivable to use a cam member. If the second electrostrictive actuator is formed in an arc shape along the lens barrel in order to rotate such a cam member, it is less wasteful in space than when used in a linear state.

  In the optical device configured as described above, the first electrostrictive actuator and the second electrostrictive actuator are integrally formed electrostrictive actuators, and the first electrostrictive actuator and the second electrostrictive actuator are integrated. It can be set as the structure which has a fixing | fixed part which negates the mutual influence of the expansion-contraction of said 1st electrostrictive actuator or said 2nd electrostrictive actuator by being fixed in the boundary part with an actuator.

  With such an integrated electrostrictive actuator, the movement operation of the focusing lens in the optical axis direction and the movement operation of the zoom lens in the optical axis direction are simultaneously performed by one electrostrictive actuator. realizable. However, in such an integrated electrostrictive actuator, it is conceivable that the first electrostrictive actuator and the second electrostrictive actuator mutually affect the expansion. In order to precisely control the movement of the focus adjustment lens and the zoom lens, it is desirable to avoid such mutual influence as much as possible. In view of this, the above-described mutual influence can be obtained by providing a fixed portion that cancels out the influence of extension in the direction perpendicular to the optical axis direction at the boundary between the first electrostrictive actuator and the second electrostrictive actuator. Can be reduced or eliminated.

  Such a fixing portion can be a constricted portion in which the width in the optical axis direction at the boundary portion between the first electrostrictive actuator and the second electrostrictive actuator is formed narrow (Claim 5).

  If the fixed portion is a constricted portion having such a shape, it is easy to fix, and the mutual influence of expansion between the first electrostrictive actuator and the second electrostrictive actuator can be canceled.

  According to the present invention, the first electrostrictive actuator extending in the optical axis direction moves either the focus adjustment lens or the variable power lens in the optical axis direction, and the optical axis is changed via the driving means. Since the other lens is advanced in the optical axis direction by the second electrostrictive actuator extending in the circumferential direction at the center, the optical device can be miniaturized. In particular, the first electrostrictive actuator and the second electrostrictive actuator are each formed by forming a band-shaped electrostrictive actuator into an arc shape, and the first electrostrictive actuator and the first electrostrictive actuator are positioned so that one arc is located inside the other arc. Thinning of the optical device can be achieved by arranging the second electrostrictive actuator in parallel inside and outside.

  The best mode for carrying out the present invention will be described below in detail with reference to the drawings.

  The configuration of the optical device 30 of this embodiment will be described with reference to the drawings. FIG. 1 is an exploded perspective view of the optical device 30, and FIG. 2 is an exploded perspective view in which a part of each component is cut out so that the shape of each component of the optical device 30 is clear. FIGS. 3A and 3B are cross-sectional views of the optical device 30 in an assembled state. FIG. 3A is a cross-sectional view taken along line BB in FIG. 3B, and FIG. It is -A sectional drawing.

  First, the case 2 is attached so as to surround the image pickup device 31 installed on the substrate 1. As shown in the figure, the case 2 includes a first lens holding member 5 holding the first zooming lens 3, a second lens holding member 6 holding the second zooming lens 4, a cam member 7, The strain actuator 8, the holding plate 9, the third lens holding member 10 holding the focus adjusting lens 11, and the spring material 13 are housed, and the lid member 12 is attached so that these elements do not fall off. Furthermore, a driver 14 incorporating an IC for controlling the electrostrictive actuator is installed on the substrate 1 to constitute the optical device 30. Hereinafter, each component will be described in detail.

  The zoom lens is provided with two lenses, a zoom first lens 3 and a zoom second lens 4. These zooming lenses are held by the first lens holding member 5 and the second lens holding member 6, respectively. The first lens holding member 5 protrudes in the radial direction and has a pair of protrusions 5a at positions symmetrical to the center, and the second lens holding member 6 also has a pair of protrusions at positions symmetrical to the center. 6a. On the other hand, the cam member 7 rotatably installed in the case 2 has spiral grooves 7b and 7c on its peripheral wall. The spiral grooves 7b and 7c each have a pair of grooves at symmetrical positions with respect to the center. The protrusions 5a and 5b are engaged with the spiral grooves 7b and 7c. Here, the inclination angles of the spiral groove 7b and the spiral groove 7c are different.

  A guide member 2 a is provided in the case 2. The guide member 2a is a cylindrical body located in the case 2, and longitudinal grooves 2a1 and 2a2 in the optical axis direction in which the protrusions 5a and 6a are engaged are provided on the peripheral wall. The cam member 7 is rotatably mounted along the outer periphery of the guide member 2a. At this time, if the protrusion 5a is engaged with the spiral groove 7b and engaged with the longitudinal groove 2a1 to rotate the cam member 7, the first lens holding member 5 moves forward and backward along the longitudinal groove 2a1. Similarly, when the protrusion 6a is engaged with the spiral groove 7c and the cam member 7 is rotated by being engaged with the longitudinal groove 2a2, the second lens holding member moves forward and backward along the longitudinal groove 2a2. At this time, since the inclination angles of the spiral groove 7b and the spiral groove 7c are different as described above, they are held by the first lens 3 for zooming and the second lens holding member 6 held by the first lens holding member 5. The second zoom lens 4 not only moves forward and backward, but also changes the distance between them. Here, the cam member 7 has a projecting piece 7a formed on the outer peripheral wall, and the cam member rotates when the electrostrictive actuator 8 described later pushes the projecting piece 7a. The above configuration corresponds to drive means for moving the zooming lenses 3 and 4 forward and backward in the optical axis direction in the present invention.

  Next, the electrostrictive actuator 8 attached to the optical device 30 will be described. As shown in the enlarged perspective view of FIG. 4A and the enlarged development view of FIG. 4B, the electrostrictive actuator 8 is an integrated electrostrictive unit in which the first electrostrictive actuator 8b and the second electrostrictive actuator 8c are integrally formed. It is a strain actuator. Here, the electrostrictive actuator 8 includes an electrode layer 8e formed by applying carbon powder on both surfaces of a silicon film 8d which is a highly flexible insulating film.

  Here, the configuration of the electrode layer 8e will be described in detail with reference to FIG. 4C or FIG. FIG.4 (c) is CC sectional view taken on the line of FIG.4 (b). As shown in FIG. 4C, electrodes 8e1 and 8e2 are provided on the front and back surfaces of the region of the first electrostrictive actuator 8b of the silicon film 8d. In addition, an electrode 8e3 and an electrode 8e4 are provided on the front and back surfaces of the region of the second electrostrictive actuator 8c. As described above, since the first electrostrictive actuator 8b and the second electrostrictive actuator 8c are provided with separate electrodes, each can be driven independently. Further, as shown in FIG. 4D, the electrode 8e may share the ground electrode of the first electrostrictive actuator 8b and the second electrostrictive actuator 8c. That is, even if the ground electrode 8e5 is provided on the entire surface of one surface of the silicon film 8d, the electrode 8e2 is provided in the region of the first electrostrictive actuator 8b on the other surface, and the electrode 8e4 is provided in the region of the second electrostrictive actuator 8c. Good. Further, in the unfolded state, a belt-like object as shown in FIG. 4B is used, and as shown in FIG. 4A, the arc-shaped second electrostrictive actuator 8c is replaced with the arc-shaped first electrostrictive actuator 8b. It is formed into a roll shape so as to be located inside. Comparing the width of the first electrostrictive actuator 8b and the width of the second electrostrictive actuator 8c, the second electrostrictive actuator 8c is narrower. A constricted portion 8a which is a fixed portion having a narrow width in the optical axis direction is formed at a boundary portion between the first electrostrictive actuator 8b and the second electrostrictive actuator 8c. Since the constricted portion 8a is fixed by the case 2 and the holding plate 9 so as not to expand and contract, the expansion and contraction of the first and second electrostrictive actuators 8b and 8c is not transmitted through the constricted portion 8a. Therefore, the first and second electrostrictive actuators 8b and 8c can be driven independently. A lead wire (not shown) is connected to the electrode layer 8 e of the electrostrictive actuator 8.

  Such an electrostrictive actuator 8 is mounted in the case 2 as shown in FIG. 5, and the shape of the case 2 will be described. The case 2 has the guide member 2a inside as described above. Moreover, it has the outer peripheral wall 2b in the outermost periphery, and also has the intermediate wall 2c between the guide member 2a and the outer peripheral wall 2b. The intermediate wall 2c is provided with a groove 2c1.

  The electrostrictive actuator 8 is mounted in the case 2 such that the constricted portion 8a coincides with the groove 2c1 of the case 2 having such a shape. That is, as shown in FIG. 3B, the first electrostrictive actuator 8b is accommodated in the space formed between the outer peripheral wall 2b and the intermediate wall 2c of the case 2, and along the outer periphery of the guide member 2a. The second electrostrictive actuator 8c is housed in a space formed between the mounted cam member 7 and the intermediate wall 2c. At this time, the tip end portion of the second electrostrictive actuator 8c is brought into contact with the protruding piece 7a of the cam member 7 and is fixedly bonded. Further, the first electrostrictive actuator 8b is also mounted in the case 2 so as to be restricted from extending in the circumferential direction around the optical axis.

  The presser plate 9 is mounted on the upper side of the second electrostrictive actuator 8c of the electrostrictive actuator 8 attached to the case 2 in this way. As shown in FIG. 6, the presser plate 9 has a protrusion 9a on the side in contact with the second electrostrictive actuator 8c. The presser plate 9 is mounted so that the position of the protrusion 9 a matches the position of the constricted portion 8 a of the electrostrictive actuator 8. By attaching the presser plate 9 in this way, the extension of the second electrostrictive actuator 8c in the optical axis direction is restricted.

  The third lens holding member 10 holding the focus adjustment lens 11 is placed above the presser plate 9 thus mounted. This third lens holding member 10 is an edge of the first electrostrictive actuator 8b. Support with. Accordingly, the focus adjustment lens 11 can move in the optical axis direction by the extension of the first electrostrictive actuator 8b in the optical axis direction.

  After the third lens holding member 10 is mounted, the lid member 12 is attached via the spring member 13. The spring material 13 biases each lens toward the substrate 1 in the optical axis direction. That is, when each electrostrictive actuator stops or reduces the application of voltage, the distortion of the silicon film 8d is naturally eliminated, and each lens attempts to return to the initial position, but the spring material 13 is interposed. This makes it possible to quickly return each lens.

  The optical device 30 is configured as described above. Next, the operation of the optical device 30 configured as described above will be described.

  When the optical device 30 energizes and applies a voltage to the electrode layer 8e of the electrostrictive actuator via the driver 14 of the electrostrictive actuator 8, the optical device 30 receives a force that causes the electrode layer 8e to be drawn and the silicon film 8d to be crushed. For this reason, the silicon film 8d tends to spread in the optical axis direction and the direction perpendicular to the optical axis direction.

  Here, first, the operation of the first electrostrictive actuator 8b will be described. Since the first electrostrictive actuator 8b is restricted from extending or contracting in the circumferential direction around the optical axis as described above, most of the portion of the first electrostrictive actuator 8b that is crushed is expended in the optical axis direction. . Thus, when the first electrostrictive actuator 8b extends in the optical axis direction, the third lens holding member 10 holding the focus adjustment lens 11 moves in a direction away from the image pickup device 31 in the optical axis direction from the initial position.

  On the other hand, the second electrostrictive actuator 8c is restricted from extending in the optical axis direction by the presser plate 9. Therefore, most of the amount of the crushing of the silicon film 8d is expansion and contraction in the circumferential direction around the optical axis. Is spent. The second electrostrictive actuator 8c extends in the circumferential direction around the optical axis, thereby pushing the protruding piece 7a of the cam member 7 and rotating the cam member 7 from the initial position. When the cam member 7 rotates, the first lens holding member 5 that holds the first lens 3 for zooming and the second lens holding member 6 that holds the second lens 4 for zooming are image pickup devices 31 in the optical axis direction. Move away from the camera.

  Here, the first electrostrictive actuator 8b and the second electrostrictive actuator 8c are integrally formed as an integrated electrostrictive actuator, but the first electrostrictive actuator 8b and the second electrostrictive actuator 8b are integrated with each other through the constricted portion 8a. The expansion and contraction in the circumferential direction around the optical axis of the actuator 8c does not affect each other. That is, since the constricted portion 8a, which is a fixed portion, is fixed by the case 2 and the holding plate 9, the left and right expansion and contraction of the constricted portion 8a does not travel through the constricted portion 8a.

  The optical device 30 that operates as described above controls the amount of expansion of the electrostrictive actuator 8 by adjusting the voltage applied to the electrode layer 8e, and moves each lens to a desired distance to obtain a desired magnification. Can be combined. When the application of voltage to the electrode layer 8e is stopped or lowered, the lens 11 can be quickly returned to a predetermined position by the action of the spring material 13. Further, the lenses 3 and 4 can be returned to a predetermined position by a contracting force when the voltage application of the second electrostrictive actuator 8c is stopped or reduced.

  Next, a second embodiment of the present invention will be described. FIG. 7 is a perspective view of the first electrostrictive actuator 15 and the second electrostrictive actuator 16 that can be used in place of the electrostrictive actuator 8 used in the optical device 30 of the first embodiment. That is, the electrostrictive actuator 8 of the first embodiment is an integrated type in which the first electrostrictive actuator 8b and the second electrostrictive actuator 8c are integrally formed, whereas in the second embodiment, the first electrostrictive actuator 8b. 15 and the second electrostrictive actuator 16 are separated.

  As described above, when the first electrostrictive actuator 15 and the second electrostrictive actuator 16 are separated from each other, wiring is applied to each electrostrictive actuator, and control is performed to individually apply a voltage. Accordingly, it is possible to independently control the focus adjusting lens 11 and the zooming lenses 3 and 4.

  Other components can be configured in the same manner as in the first embodiment, and thus detailed description thereof is omitted.

  The above-described embodiments are merely examples for carrying out the present invention, and the present invention is not limited to them. Various modifications of these embodiments are within the scope of the present invention. It is apparent from the above description that various other embodiments are possible within the scope. For example, the focus adjustment lens 11 is returned to the initial position or the like by the spring material 13, but even if the lens position is returned by the contraction force of the first electrostrictive actuator 8 b when the voltage application is stopped. Good. At this time, the contact surface between the third lens holding member 10 and the first electrostrictive actuator 8b is fixed with an adhesive or the like. Further, the movement of the zooming lenses 3 and 4 is performed by bonding and fixing the projecting piece 7a of the cam member 7 and the second electrostrictive actuator 8c (or 16). As shown in FIG. 5, a long hole 8f may be provided at the end of the second electrostrictive actuator 8c (or 16) on the side in contact with the protruding piece 7a, and the protruding piece 7a may be engaged with the elongated hole 8f. . Further, since the electrostrictive actuator can be extended only in a specific direction when it is adjusted in the machining process, it is specified by adjusting the machining in the area of the first electrostrictive actuator 8b and the area of the second electrostrictive actuator 8c. Only the direction may be extended. In addition, it is possible to provide a space extending in an undesired direction in advance without restricting the extension in an undesired direction.

It is a disassembled perspective view of the optical apparatus of this invention. FIG. 2 is an exploded perspective view in which a part of each component is cut out so that the shape of each component of the optical device illustrated in FIG. 1 is clear. (A) And (b) is sectional drawing of the optical apparatus of the assembled state of FIG. 1, respectively, (a) is BB sectional drawing in (b), (b) is (a). It is AA sectional drawing in. (A) is an enlarged perspective view of the electrostrictive actuator incorporated in the optical device shown in FIG. 1, and (b) is an enlarged development view of the electrostrictive actuator described in (a). (C) is CC sectional drawing which shows the structure of the electrode of an electrostrictive actuator, (d) is sectional drawing which shows the other Example of a structure of an electrode. FIG. 2 is a diagram illustrating a state in which an electrostrictive actuator is attached to a case attached to the optical device illustrated in FIG. FIG. 2 is an enlarged perspective view of a presser plate that is attached to the optical device shown in FIG. FIG. 6 is an enlarged perspective view of a first electrostrictive actuator and a second electrostrictive actuator that are attached to the optical device of Example 2. (A) is a front view of an electrostrictive actuator in other examples. (B) is sectional drawing of the part which made the protrusion engage with the long hole.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Board | substrate 2 Case 2a Guide member 3 First lens for zooming 4 Second lens for zooming 5 First lens holding member 6 Second lens holding member 7 Cam member 7b, 7c Spiral groove 8 Electrostrictive actuator 8a Fixed part (necking) Part)
8b First electrostrictive actuator 8c Second electrostrictive actuator 8d Silicon film 8e Electrode layer 9 Holding plate 10 Third lens holding member 11 Focus adjustment lens 12 Lid member 13 Spring material 14 Driver 30 Optical device 31 Imaging device

Claims (5)

A focus adjustment lens, a zoom lens,
A first electrostrictive actuator extending in the optical axis direction;
A second electrostrictive actuator extending in the circumferential direction around the optical axis,
One of the focusing lens and the zoom lens is moved in the optical axis direction along with the extension operation of the first electrostrictive actuator, and the other lens is the second electrostrictive actuator. An optical apparatus that is moved in the direction of the optical axis in accordance with the extension operation. The first electrostrictive actuator and the second electrostrictive actuator are each formed of a strip-shaped electrostrictive actuator in an arc shape, and the first electrostrictive actuator and the second electrostrictive actuator are positioned so that one arc is located inside the other arc. 2. The optical apparatus according to claim 1, wherein the second electrostrictive actuator is arranged in parallel inside and outside. A lens holding member that holds the focus adjustment lens or the zoom lens and has a protrusion protruding in the radial direction of the lens;
A guide member in which a longitudinal groove in the optical axis direction through which the protrusion penetrates is formed in a peripheral wall of a cylindrical body whose axial direction coincides with the optical axis direction;
A cam that is rotatably held by the guide member, a groove that engages with the protrusion is formed on the peripheral wall of the cylindrical body whose axial direction coincides with the optical axis direction, and rotates with the extension operation of the second electrostrictive actuator The optical device according to claim 1, further comprising: a member. The first electrostrictive actuator and the second electrostrictive actuator are integrally formed electrostrictive actuators, and are fixed at a boundary portion between the first electrostrictive actuator and the second electrostrictive actuator. The optical apparatus according to claim 2, further comprising: a fixing unit that cancels out the mutual influence of expansion of the first electrostrictive actuator or the second electrostrictive actuator. 5. The optical device according to claim 4, wherein the fixed portion is a constricted portion in which a width in the optical axis direction is narrowed at a boundary portion between the first electrostrictive actuator and the second electrostrictive actuator. .

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