JP2006330559A - Camera module using lamination type piezoelectric actuator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a camera module for driving a lens unit, the camera module having fewer components and using inexpensive and small laminated type piezoelectric actuators. <P>SOLUTION: The camera module using the laminated type piezoelectric actuators is constituted of: the lens unit 12; the laminated type piezoelectric actuators that move the lens unit; and a frame body 13 that fixes the laminated piezoelectric actuator. In the camera module using the laminated type piezoelectric actuators, the lens unit 12, the four laminated type piezoelectric actuators disposed around the central point of the lens unit 12 in four directions almost perpendicular to each other with a clearance not greater than the maximum displacement amount of the respective laminated type piezoelectric actuators, and the frame body 13 fixing the laminated type piezoelectric actuators are integrally formed of piezoelectric ceramics. The direction and magnitude of a voltage applied to each laminated type piezoelectric actuator is adjusted. Thereby, the lens unit 12 is moved in an arbitrary direction in the direction of the optical axis of the lens unit 12. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a camera module, and more particularly to a camera module that drives a lens unit using a laminated piezoelectric actuator suitable for a camera module used in a digital camera or a mobile phone.

  In recent years, with the reduction in weight, thickness and price of digital cameras, similar requirements are strongly demanded for each component. Digital cameras are equipped with a lens drive device that provides autofocus and camera shake correction functions, and mobile phones are also equipped with small cameras with autofocus functions, driving lighter and thinner lenses. There is a strong need for equipment. In general, a laminated piezoelectric actuator is used as a driving source in such a lens driving device.

  A lens driving device “camera, focus adjustment method and focus adjustment mechanism” using a multilayer piezoelectric actuator as a drive source is disclosed in Patent Document 1. FIG. 4 is a schematic view showing the principle of the focus adjustment mechanism disclosed in Patent Document 1. In this focus adjustment mechanism, the multilayer piezoelectric element 31 is arranged so that the displacement of the multilayer piezoelectric element 31 generated by the application of voltage is substantially parallel to the optical axis of the imaging optical system. A lever that abuts the tip surface of the multilayer piezoelectric element 31, expands the displacement of the multilayer piezoelectric element 31, transmits the expanded displacement to the lens frame 34 that holds the lens 33, and moves the lens frame 34 in the optical axis direction. 32, a main pole 35a for guiding the lens frame 34, a sub-pole 35b, a biasing spring 36 for biasing the lens frame 34, and a stopper 37 fixed to the camera body.

  In this focus adjustment mechanism, the lens frame 34, the lever 32, and the laminated piezoelectric element 31 are in a fixed state balanced. When a voltage corresponding to the feed amount set to the multilayer piezoelectric element 31 is applied by the drive circuit, the multilayer piezoelectric element 31 is displaced in the direction in which the convex portion 32b of the lever 32 is pressed (the direction of arrow A in the figure). The lever 32 rotates slightly counterclockwise about the rotation support point 32a, and the displacement increases at an expansion ratio corresponding to the distance from the rotation fulcrum 32a to each of the convex portions 32b and 32c. Presses the protruding portion 34c of the lens frame 34, and the lens frame 34 is guided by the main pole 35a and the sub pole 35b and moves in the direction of arrow B in the figure. With such a focus adjustment mechanism, the lens is moved to a predetermined location, thereby focusing.

JP 11-264927 A

  The focus adjustment mechanism of Patent Document 1 described above requires the lever 32, the urging spring 36, the main and sub poles 35a and 35b in addition to the laminated piezoelectric actuator 31 and the lens 33, and the number of parts is increased and the size is reduced. This is a disadvantageous structure for cost reduction. The multilayer piezoelectric actuator corresponds to the ratio of the distance from the convex portion 32b that contacts the laminated piezoelectric actuator of the lever to the rotation fulcrum 32a of the lever and the distance from the lens frame protrusion 34c to the rotational fulcrum 32a of the lever. This is based on the principle that the displacement of the actuator increases, so there is a limit to the miniaturization of the lever to secure the displacement amount of the multilayer piezoelectric actuator, and there is a problem that the miniaturization of the focus adjustment mechanism is limited. .

  The present invention has been made to solve the above-described problems, and a technical problem thereof is to provide a camera module using a low-priced and small stacked piezoelectric actuator with a small number of parts.

  A first invention for achieving the above object is a camera module using a laminated piezoelectric actuator comprising a lens unit, a laminated piezoelectric actuator for moving the lens unit, and a frame for fixing the laminated piezoelectric actuator. The lens unit and the lens unit are arranged with clearances having a length equal to or less than the maximum displacement amount in each of the stacked piezoelectric actuators in four directions substantially orthogonal to each other on the same plane with the center point of the lens unit as a center. In addition, the present invention is a camera module using four stacked piezoelectric actuators and a stacked piezoelectric actuator comprising a frame for fixing the stacked piezoelectric actuator.

  According to a second aspect of the invention for achieving the above object, there is provided a multilayer piezoelectric actuator in which the frame body and the multilayer piezoelectric actuator are formed of piezoelectric ceramics, and the frame body and the multilayer piezoelectric actuator are integrally formed. This is the camera module used.

  According to a third aspect of the invention for achieving the above object, each of the multilayer piezoelectric actuators has a dimension that is approximately half the distance from one main surface to the other main surface of each of the multilayer piezoelectric actuators. Two internal electrode layers, each of which can be driven independently, in which a plurality of layers are stacked in a direction parallel to the main surface and the other main surface are provided on the main surface and the other main surface of each of the stacked piezoelectric actuators. A pair of externals that electrically connect the internal electrode layers exposed on one of the principal surfaces and the other principal surface of each of the multilayer piezoelectric actuators to drive the multilayer piezoelectric actuator An electrode is provided on each of the one principal surface and the other principal surface of each of the multilayer piezoelectric actuators, and one principal surface of each of the multilayer piezoelectric actuators An insulator that insulates every other layer of the internal electrode exposed on each of the other main surfaces is provided, and is electrically connected to a first external electrode that is a pair of the pair of external electrodes Insulators that alternately insulate the exposed internal electrodes that are electrically connected to the exposed external electrodes and the second external electrodes that form a pair of the external electrodes in a direction parallel to the main surface; It is a camera module using a provided laminated piezoelectric actuator.

  According to a fourth aspect of the present invention for achieving the above object, in the laminated piezoelectric actuators according to the first and second aspects of the present invention, each of the stacked piezoelectric actuators substantially faces each other in four directions substantially orthogonal to a center point of the lens unit. A state in which no electric field is applied to the third and fourth stacked piezoelectric actuators that are substantially orthogonal to each other and substantially orthogonal to the stacked piezoelectric actuator is defined as step (a), and the first and second stacked piezoelectric actuators A state in which an electric field having the same phase as the polarization direction is applied to both of two independent internal electrode layers in each of the first and second stacked piezoelectric actuators, and the lens unit is sandwiched ( b) In the step, a voltage having the same phase as the polarization direction is applied to one of the two independent internal electrode layers in each of the first and second stacked piezoelectric actuators. (C) a state in which the lens unit is moved by applying a voltage having a phase opposite to that of the polarization direction to the other internal electrode layer to bend the one internal electrode layer convexly. And applying a voltage having the same phase as the polarization direction to both of two independent internal electrode layers in each of the third and fourth stacked piezoelectric actuators, so that the third and fourth stacked piezoelectric actuators are applied. A state in which the actuator is extended and the lens unit is sandwiched is referred to as step (d), and the voltage applied to the first and second multilayer piezoelectric actuators is set to 0 and the multilayer piezoelectric actuator is sandwiched. The state in which the unit is separated is defined as step (e), and one of the two independent internal electrode layers in each of the third and fourth stacked piezoelectric actuators is in phase with the polarization direction. One of the internal electrode layers applies a voltage opposite in phase to the polarization direction, thereby bending the one internal electrode layer side convexly to move the lens unit as a step (f), and the first step And a voltage having the same phase as the polarization direction are applied to both of two independent internal electrode layers in each of the second stacked piezoelectric actuators to extend the first and second stacked piezoelectric actuators. The state in which the lens unit is sandwiched is set as step (g), the voltage applied to the third and fourth laminated piezoelectric actuators is set to 0, and the third and fourth laminated piezoelectric actuators are set. When the state in which the lens unit that has been clamped is separated is defined as step (h), the lens unit is moved in the optical axis direction of the lens unit by repeating steps (b) to (h). It is a camera module using a laminated piezoelectric actuator having a function of moving in any direction.

  According to the present invention, in a camera module using a multilayer piezoelectric actuator configured by a lens unit, a multilayer piezoelectric actuator that moves the lens unit, and a frame that fixes the multilayer piezoelectric actuator, the center of the lens unit and the lens unit is provided. Four laminated piezoelectric actuators and laminated piezoelectric elements arranged with clearances of a length equal to or less than the maximum displacement amount in each of the laminated piezoelectric actuators in four directions substantially perpendicular to each other on the same plane centering on a point By integrally forming the frame that fixes the actuator with piezoelectric ceramics, parts such as levers, biasing springs, and poles required for conventional focus adjustment mechanisms can be reduced, and restrictions on downsizing the focus adjustment mechanism Can be eliminated.

  A camera using a multilayer piezoelectric actuator having a function of moving the lens unit in an arbitrary direction in the optical axis direction of the lens unit by adjusting the direction and magnitude of the voltage applied to the multilayer piezoelectric actuator. A module can be realized.

  As a result, it is possible to provide a camera module using a low-price and small stacked piezoelectric actuator with a small number of parts.

  A camera module using a laminated piezoelectric actuator according to the best mode for carrying out the present invention will be described below with reference to the drawings.

  1A and 1B show an outline of a camera module using a laminated piezoelectric actuator according to the present invention. FIG. 1A is a perspective view and FIG. 1B is a top view. 2A and 2B schematically show individual stacked piezoelectric actuators in a camera module using the stacked piezoelectric actuator of the present invention. FIG. 2A is a cross-sectional view and FIG. 2B is a top view. . FIG. 3 shows the operating state of each stacked piezoelectric actuator with respect to the lens unit of the camera module using the stacked piezoelectric actuator of the present invention, and FIGS. 3 (a) to 3 (h) showing the state of each operating step. Shown in front view (left side) and side view (right side).

  As shown in FIG. 1, in the camera module using the multilayer piezoelectric actuator according to the best mode for carrying out the present invention, the first multilayer piezoelectric actuator 11a and the second multilayer actuator centered on the center point of the lens unit 12. The laminated piezoelectric actuator 11b, the third laminated piezoelectric actuator 11c, and the fourth laminated piezoelectric actuator 11d are arranged so as to be substantially orthogonal to each other and to surround the lens unit 12 from four sides on the same plane. The four laminated piezoelectric actuators 11a, 11b, 11c, and 11d are fixed to the frame 13, and a clearance having a length equal to or shorter than the maximum displacement of the laminated piezoelectric actuator is provided to provide the lens unit 12 and the laminated piezoelectric actuator 11a, 11b, 11c, and 11d are arranged.

  In the camera module using the laminated piezoelectric actuator according to the best mode for carrying out the present invention, as shown in FIG. 2, approximately half the distance from one main surface of the piezoelectric ceramic 28 to the other main surface. Thus, two independent internal electrode layers of the internal electrode layer 21 including the internal electrodes 22a, 22b, 22c, and 22d and the internal electrode layer 23 including the internal electrodes 24a, 24b, 24c, and 24d are formed. A pair of external electrodes 25a and 25b are formed on the main surface from which the internal electrode layer 21 is exposed, and the insulating layers 27a, 27a, 25b 27b, 27c, and 27d are formed.

  As a result, the external electrode 25a and the internal electrodes 22a and 22c can be insulated, and the external electrode 25b and the internal electrodes 22b and 22d can be insulated. In this state, when positive and negative voltages are applied to the pair of external electrodes, the voltage can be applied to the entire piezoelectric ceramic layers sandwiched between the internal electrodes, and polarization treatment and driving can be performed.

  Similarly, a pair of external electrodes 26a and 26b are also formed on the other main surface where the internal electrode layer 23 is exposed, and the internal electrodes are alternated between every other layer and a pair of external electrodes. Insulating layers 27e, 27f (not shown), 27g, 27h (not shown) are formed as described above, and the external electrode 26a and the internal electrodes 24a and 24c can be insulated, and the external electrode 26b and the internal electrodes 24b and 24d can be insulated. The piezoelectric ceramics between the internal electrode layers 23 can be driven.

  The multilayer piezoelectric actuator thus obtained can drive the internal electrode layer 21 and the internal electrode layer 23 independently. When a voltage having the same phase as the polarization is applied to the internal electrode layer 21, the piezoelectric ceramic expands, and when a voltage having the same phase as the polarization is applied to the internal electrode layer 23, the piezoelectric ceramic expands and the actuator as a whole also expands.

  On the other hand, when a voltage having the same phase as that of polarization is applied to the internal electrode layer 21 and a voltage having a phase opposite to that of polarization is applied to the internal electrode layer 23, the piezoelectric ceramic of the internal electrode layer 21 expands, and the piezoelectric ceramic of the internal electrode layer 23 becomes Since it is reduced, the entire actuator is bent so that the internal electrode layer 21 side is convex. The lens unit can be moved by using these two drive modes.

  The movement of the lens unit is performed by applying a voltage so as to extend the first and second stacked piezoelectric actuators from the initial state (a) step as shown in FIG. It moves to the process (b) hold | maintaining on both sides of a unit.

  Next, by applying a voltage so that the first and second laminated piezoelectric actuators bend in the same direction from this state, the process proceeds to step (c) in which the lens unit moves along with the bending motion. When a voltage is applied to extend the third and fourth stacked piezoelectric actuators in this state, the process proceeds to step (d) in which the two stacked piezoelectric actuators hold the lens unit between them. In this state, when the voltage applied to the first and second laminated piezoelectric actuators is returned to 0, the lens unit is separated. Since the third and fourth stacked piezoelectric actuators sandwich the lens unit, the lens unit moves to the step (e) in which the state is moved from the initial state. Thereafter, when a voltage is applied to bend the third and fourth stacked piezoelectric actuators in the same direction, the process moves to a step (f) in which the lens unit moves with the bending motion.

  Next, when a voltage is applied so as to extend the first and second multilayer piezoelectric actuators, the process proceeds to the step (g) of holding the lens unit between the two multilayer piezoelectric actuators. Thereafter, when the voltage applied to the third and fourth laminated piezoelectric actuators is set to 0, the lens unit is separated. Since the lens unit is sandwiched between the first and second stacked piezoelectric actuators, the process proceeds to step (h) in which the lens unit maintains the moved state. By repeating such operations (b) to (h), the lens unit can be moved.

  Further, if the bending direction of the multilayer piezoelectric actuator is reversed, the lens unit can also move in the reverse direction.

  It should be noted that the lens unit can be moved at any position where it can be held between the stacked piezoelectric actuators. Theoretically, it can be moved by the length of the lens unit, and a large amount of movement can be obtained without using parts other than the laminated piezoelectric actuator.

  Furthermore, the multilayer piezoelectric actuator used in the camera module using the multilayer piezoelectric actuator of the present invention can be made in a thin plate shape, and the drive unit other than the lens unit can be made very thin, which is extremely advantageous for thinning the digital camera. become.

  In addition, it can be manufactured using a multilayer ceramic capacitor manufacturing method in which internal electrodes are printed on a general multilayer ceramic green sheet with a screen and fired integrally. It becomes possible to manufacture.

  As described above, the camera module using the multilayer piezoelectric actuator of the present invention has a small number of components and can provide a camera module using an inexpensive multilayer piezoelectric actuator.

The figure which shows the outline of the camera module using the lamination type piezoelectric actuator of this invention. FIG. 1A is a perspective view. FIG. 1B is a top view. The figure which shows the outline of each lamination type piezoelectric actuator in the camera module using the lamination type piezoelectric actuator of this invention. FIG. 2A is a cross-sectional view. FIG. 2B is a top view. The figure which shows the operation state of each lamination type piezoelectric actuator with respect to the lens unit of the camera module using the lamination type piezoelectric actuator of this invention. FIG. 3A to FIG. 3H are a front view and a side view of the state of each operation step. Schematic which shows the principle of the focus adjustment mechanism disclosed by patent document 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Camera module using the laminated piezoelectric actuator of the present invention 2 Laminated piezoelectric actuator used in the present invention 3 Conventional camera module 11a First laminated piezoelectric actuator 11b Second laminated piezoelectric actuator 11c Third laminated type Piezoelectric actuator 11d Fourth laminated piezoelectric actuator 12 Lens unit 13 Frame 21 Internal electrode layer (upper layer)
22a, 22b, 22c, 22d Internal electrode 23 Internal electrode layer (lower layer)
24a, 24b, 24c, 24d Internal electrode 25a, 25b External electrode (for driving internal electrode layer on upper layer)
26a, 26b External electrode (for driving internal electrode layer below)
27a, 27b, 27c, 27d, 27e, 27f, 27g, 27h Insulating layer 28 Piezoelectric ceramic 31 Multilayer piezoelectric element (actuator)
31a Lead wire (positive pole)
31b Lead wire (negative pole)
32 Lever 32a Rotating fulcrum 32b Convex part 32c (Abutting the actuator) Protruding part 33 Lens 34 Lens frame 34a Cylindrical part 34b holding the lens Convex part 34c through which the sub pole penetrates Protruding part 34d Convex part 35a through which main pole penetrates Main pole 35b Sub pole 36 Biasing spring 37 Stopper

Claims (4)

  In a camera module using a lens unit, a stacked piezoelectric actuator that moves the lens unit, and a stacked piezoelectric actuator that includes a frame that fixes the stacked piezoelectric actuator, a center point between the lens unit and the lens unit is defined. Four laminated piezoelectric actuators arranged with a clearance having a length equal to or less than the maximum displacement amount in each of the laminated piezoelectric actuators in four directions substantially perpendicular to each other on the same plane at the center, and the laminated piezoelectric actuator A camera module using a laminated piezoelectric actuator, characterized by comprising a frame body for fixing.   2. The camera using a multilayer piezoelectric actuator according to claim 1, wherein the frame and the multilayer piezoelectric actuator are formed of piezoelectric ceramics, and the frame and the multilayer piezoelectric actuator are integrally formed. module.   A direction approximately half the distance from one main surface to the other main surface of each of the multilayer piezoelectric actuators, and a direction parallel to the main surface and the other main surface of each of the multilayer piezoelectric actuators Two internal electrode layers each having a plurality of layers stacked on each other and provided on the main surface and the other main surface of each of the stacked piezoelectric actuators. The internal electrode layer exposed to each of the main surface and the other main surface is electrically connected, and a pair of external electrodes for driving the stacked piezoelectric actuator is connected to one of the stacked piezoelectric actuators. Provided on each of the main surface and the other main surface, and before being exposed to each of the one main surface and the other main surface in each of the multilayer piezoelectric actuators The exposed internal electrode and the pair of external electrodes provided with an insulator that insulates the internal electrodes every other layer, and electrically connected to the first external electrode that forms a pair of the pair of external electrodes 2. An insulator is provided that alternately insulates the exposed internal electrode electrically connected to the second external electrode of the pair in a direction parallel to the main surface. A camera module using the multilayer piezoelectric actuator according to claim 2.   In each of the multilayer piezoelectric actuators in four directions substantially orthogonal to the center point of the lens unit, the first and second multilayer piezoelectric actuators that are substantially opposed to each other are substantially opposed to each other. A state in which an electric field is not applied to the third and fourth stacked piezoelectric actuators is defined as step (a), and both of the two independent internal electrode layers in each of the first and second stacked piezoelectric actuators A state in which an electric field having the same phase as the polarization direction is applied to extend the first and second stacked piezoelectric actuators to sandwich the lens unit is defined as step (b), and the first and second steps A voltage having the same phase as the polarization direction is applied to one of the two independent internal electrode layers of each of the stacked piezoelectric actuators, By applying a voltage having a phase opposite to the polarization direction, the state in which the one internal electrode layer side is bent convexly and the lens unit is moved is defined as step (c), and the third and fourth stacked piezoelectric elements are formed. A voltage in phase with the polarization direction is applied to both of two independent internal electrode layers in each of the actuators, and the third and fourth stacked piezoelectric actuators are extended to hold the lens unit ( In step d), the voltage applied to the first and second multilayer piezoelectric actuators is set to 0, and the lens unit held by the multilayer piezoelectric actuator is released as step (e). 3 and the fourth laminated piezoelectric actuator, one of the two independent internal electrode layers has one internal electrode layer in phase with the polarization direction and the other internal electrode layer has the polarization direction. By applying a phase voltage, the state in which the one internal electrode layer side is bent convexly and the lens unit is moved is defined as step (f), and each of the first and second stacked piezoelectric actuators is A state in which the voltage in phase with the polarization direction is applied to both of two independent internal electrode layers to extend the first and second stacked piezoelectric actuators to sandwich the lens unit (g ) Step, the voltage applied to the third and fourth stacked piezoelectric actuators is set to 0, and the lens unit held by the third and fourth stacked piezoelectric actuators is released. In the case of (h) step, a function of moving the lens unit in an arbitrary direction in the optical axis direction of the lens unit by repeating the step (h) from the step (b) is provided. A camera module using the multilayer piezoelectric actuator according to claim 3.

Images