JP5544504B2 - Linear drive device, lens drive device, camera and mobile phone with camera - Google Patents

Description

The present invention relates to a linear drive device that linearly moves a moving body, a lens drive device using the linear drive device, a camera, and a camera-equipped mobile phone.

  In Patent Documents 1 and 2, there is a linear drive device that moves a moving body by fixing a base end of a drive shaft to a vibration member composed of a piezoelectric element and a metal vibrator and vibrating the drive shaft in the axial direction. It is disclosed.

  The vibrating members described in Patent Documents 1 and 2 have a structure in which both the piezoelectric element and the vibrator have a circular shape in plan view, and the piezoelectric element formed in a circular shape and the circularly formed vibrator are overlapped and fixed. Yes.

International Publication WO2005 / 083874 A1 JP 2007-318850 A

  Conventionally, it has been thought that a piezoelectric element and a vibrator cannot obtain a uniform vibration unless the plan view is circular.

  On the other hand, when the shape of the piezoelectric element or the vibrator is a circular shape in plan view, there is a problem that a dead space occurs when the wall surface of the casing on which the vibration member is installed forms a flat surface or a straight line.

  In the case of manufacturing a vibrating member, for example, as shown in FIG. 10, (a) a piezoelectric member 61 manufactured in a cylindrical shape is cut into round pieces to obtain a piezoelectric element 63 having a predetermined thickness, (B) The vibrator 65 is punched out in a circular shape from the metal substrate 67, and (c) one face of the vibrator 65 is fixed to one face of the piezoelectric element 63. In the conventional method for manufacturing the vibration member 69, the vibrator 65 punches the metal substrate 67 in a circular shape (see FIG. 10C), so that the yield is low and the vibration members 69 are manufactured one by one by the above-described procedure. Therefore, there is a problem that it takes time and effort to manufacture.

Therefore, an object of the present invention is to provide a linear drive device, a lens drive device, a camera, and a camera-equipped mobile phone that have a high yield, are easy to manufacture, and can reduce dead space even when installed in a rectangular casing.

  The invention described in claim 1 includes a vibration member and a drive shaft having a base end fixed to the vibration member. The vibration member and the drive shaft are housed in a housing, and the drive shaft is driven by vibration of the vibration member. In the linear drive device in which the moving body frictionally contacting the drive shaft moves linearly by vibrating in the axial direction, the outline of the vibration member is rectangular in plan view, and the plate-like piezoelectric element and the elastic plate-like element A vibrator made of metal, the vibrator is fixed to all or only the periphery of one surface of the piezoelectric element, and the base end of the drive shaft is fixed to the central part of the vibrator or piezoelectric element. The outline of the element and vibrator is a rectangular surface in plan view, the drive shaft is slidably held in the housing on the base end side and the tip end side, and the vibration member is fixed only to the drive shaft In addition, it is arranged with a gap between the case and the pulse current to flow through the piezoelectric element. More, the vibration member is a linear drive, wherein the bowl-shaped central portion projects into the driving shaft side as a whole periphery also including, from being deformed alternately opposite bowl-shaped central portion is recessed.

  According to a second aspect of the present invention, in the first aspect of the present invention, the piezoelectric element and the vibrator have the same dimensions and the same shape in plan view, and the corners and sides coincide with each other. .

A third aspect of the invention includes the housing according to the first aspect and the linear drive device according to the first or second aspect, wherein the moving body that frictionally contacts the drive shaft includes a focus lens holder of the camera and The lens driving device is at least one of an optical zoom lens holder.

Invention of Claim 4 is a case where the vibrator is a copper plate in the invention of Claim 3 , its thickness W is 0.1 to 0.3 mm, and a driving torque of 6 to 12 g is obtained. When the frequency of the current supplied to the piezoelectric element is H (kHz), the relational expression of H (kHz) ≈ (23 + 215 W) ± 5 kHz is satisfied.

The invention according to claim 5 includes the lens driving device according to claim 3 or 4 and an image sensor provided on the optical axis of the lens, wherein the casing has a substantially rectangular parallelepiped shape, and the vibration member has a rectangular shape. The camera is characterized in that one side is arranged along the wall surface of the housing.

A sixth aspect of the present invention is a camera-equipped mobile phone in which the camera according to the fifth aspect is mounted.

  According to the first aspect of the present invention, since the outline of the vibrator is rectangular in plan view, compared to a case where the metal plate is punched into a circle, the vibrator is vertically and horizontally like a grid. Since it can be obtained by cutting with a wire, the product yield can be increased and the production is easy. A piezoelectric element can also be obtained by cutting a piezoelectric substrate formed in a plate shape with vertical and horizontal lines, so that the product yield is high and the manufacture is easy.

  Since the outline of the vibration member is rectangular in plan view, when the side wall of the housing that houses the linear drive device forms a flat surface, the edge (side) of the vibration member can be arranged along the side wall of the housing, and dead space is reduced. Less.

  Conventionally, the vibration member has a circular shape in plan view, and is limited to a piezoelectric element having a circular surface and a vibrator having a circular surface. As a result of research and experiment, the inventors have found that even if the surface of these members is rectangular, it can be driven sufficiently if the predetermined conditions are adjusted, and the present invention has been achieved.

  According to the second aspect of the present invention, the effects described in the first aspect can be obtained, and the piezoelectric element and the vibrator can be manufactured by being overlapped with each other, so that the manufacture is easy. For example, the vibration member can be manufactured by stacking and fixing the surfaces of the piezoelectric substrate and the metal substrate, and cutting them vertically and horizontally, so that the manufacture is easy.

According to invention of Claim 3 , the lens drive device which has the effect of Claim 1 or 2 can be provided.

According to the invention described in claim 4 , the effect of the invention described in claim 3 is achieved, and, as a result of the experiment, the thickness of the vibrator and the frequency of the current are determined in consideration of the weight of the lens or lens holder for the camera. This is because by setting the range, the lens holder can be moved smoothly with a predetermined driving torque. This is because when the frequency H exceeds the range of the relational expression, it is difficult for the surface of the vibrator to have a uniform unevenness at the portion (center portion) where the drive shaft is attached, and a uniform deformation cannot be obtained.

  The thickness of the vibrator is 0.1 to 0.3 mm. If the thickness is less than 0.1 mm, it is difficult to manufacture and the elastic restoring force of the copper plate is inferior. This is because it becomes difficult to deform.

According to the invention described in claim 5 , it is possible to provide a camera having the function and effect described in claim 3 or 4 .

According to the invention described in claim 6 , it is possible to provide a camera-equipped mobile phone having the function and effect described in claim 5 .

  Embodiments of the present invention will be described below with reference to the accompanying drawings. First, embodiments of the present invention will be described with reference to FIGS. FIG. 1 is a diagram of a linear drive device according to the present embodiment, (a) is a longitudinal sectional view, (b) is a plan view, and FIG. 2 uses the lens drive device according to the present embodiment. 3 is a perspective view of the lens driving device according to the present embodiment as seen from the rear side, and FIG. 4 is a plan view of the lens driving device shown in FIG. 3 as seen from the rear side. 5A and 5B are diagrams simulating the vibrator when the vibration member according to the present embodiment is tested. FIG. 5A is a diagram illustrating a convex deformation state, and FIG. 5B is a diagram illustrating a concave deformation state. 6 is a graph showing the relationship between the thickness of the vibrator and the frequency of the electric power supplied to the piezoelectric element, and FIG. 7 is a perspective view for explaining a method for manufacturing the vibrating member.

  In FIG. 3, a mirror device M is mounted on the front side of the lens driving device, but is omitted in other drawings.

  A lens driving device 1 according to an embodiment of the present invention is a lens driving device of an autofocus camera 2 with an optical zoom incorporated in a mobile phone.

  As shown in FIG. 2, in the camera 2, the lens driving device 1 includes a zoom lens holder (moving body) 3, a focus lens holder 5 (moving body), and a zoom that drives the zoom lens holder 3 in a housing 13. A lens holder driving means (linear driving device) 7 and a focus lens holder driving means (linear driving means) 9 for driving the focus lens holder 5 are provided. The lens driving device 1 is mounted on a substrate 4 on which an image sensor 11 is provided. Further, as shown in FIG. 4, a zoom lens position detecting unit 43 that detects the position of the zoom lens holder 3 and a focus lens position detecting unit 45 that detects the position of the focus lens holder 5 are provided in the housing 13. It is provided.

  As shown in FIG. 2, the zoom lens holder 3 holds an optical zoom lens 14, the focus lens holder 5 holds a focus lens 16, and the optical zoom lens 14 and the focus lens 16 are optical axes. And the image sensor 11 is provided at the conjugation position on the optical axis. Further, the casing 13 is provided with a subject side lens 18 and an imaging side lens 20 with the zoom lens 14 and the focus lens 16 aligned with the optical axis. In FIGS. 3 and 4, each lens is omitted.

  Since the zoom lens driving means (linear driving device) 7 and the focus lens driving means (linear driving device) 9 have substantially the same configuration, the zoom lens driving means 7 will be described and the same effect as the focus lens driving means 9 will be described. The same reference numerals are given to the parts having the above description, and the description thereof is omitted.

  The zoom lens driving means 7 includes a vibration member 17 and a drive shaft 21 (22) disposed in the optical axis direction. A base end 21a of the drive shaft 21 (22) is fixed to the vibration member 17. . The vibration member 17 side portion and the tip end portion 21b of the drive shaft 21 (22) are held by the housing 13 by a holder 12 that holds the drive shaft 21 (22) slidably.

  As shown in FIG. 1, the vibrating member 17 includes a piezoelectric element (piezo element) 23 whose outline is rectangular in plan view, and a vibrator 19 that is bonded and fixed to the surface of the piezoelectric element 23. The base end 21a of the drive shaft 21 is bonded and fixed to the surface. The vibrator 19 has the same rectangular shape in plan view as the piezoelectric element 23. In the present embodiment, the piezoelectric element 23 and the vibrator 19 are both squares having the same dimensions in plan view, and the respective corners and sides are made to coincide. In this embodiment, the vibrator 19 is bonded and fixed to the entire surface of the piezoelectric element 23.

  As shown in FIG. 2, the vibration member 17 is fixed only to the drive shaft 21 (22), and is arranged with a gap between the vibration member 17 and the wall of the housing 13.

  As shown in FIG. 1B, the drive shaft 21 (22) has a cylindrical shape, and the base end 21a is fixed to the central portion of the vibrator 19 in the positive direction in plan view.

  The vibrator 19 is a copper plate having a thickness W of preferably 0.1 to 0.3 mm. In the present embodiment, the vibrator 19 is 0.15 mm and is a square having a side of 3.85 mm.

  As shown in FIG. 1A, a power source control unit 27 is connected to the piezoelectric element 23 and the vibrator 19, and a pulse current having a predetermined frequency is supplied to the piezoelectric element 23.

  When a pulse current is supplied to the piezoelectric element 23 and the piezoelectric element 23 extends in the surface direction, the vibrator 19 moves toward the front side (subject side) due to elastic deformation (see FIG. 5A). The reaction force causes the piezoelectric element to rapidly return to its original position and to deform so that the piezoelectric element contracts, and the center part discharges toward the rear side (FIG. 5 (b)). It comes to vibrate.

  On the other hand, as shown in FIGS. 2 and 3, the zoom lens holder 3 is provided with a pressure contact portion 31 that is in pressure contact with the drive shaft 21, and as shown in FIG. It is in pressure contact with the side surface of the drive shaft 21.

  As shown in FIG. 2, the other end portion of the zoom lens holder 3 is provided with an engagement portion 33 with the drive shaft 22 of the focus lens holder 5, and the engagement portion 33 is engaged with the drive shaft 22 of the focus lens holder. The zoom lens holder 3 is guided to be supported. The engaging portion 33 has a substantially U-shaped cross section, and the drive shaft 22 of the zoom lens holder 3 is inserted into the U-shape.

  The configuration of the focus lens holder 5 is substantially the same as that of the zoom lens holder 3, and the drive shaft 22 of the focus lens holder 5 is attached to the vibrating member 17 in the same manner as the drive shaft 21 of the zoom lens holder 3.

  Next, the zoom lens position detecting means 43 for detecting the position of the zoom lens holder 3 shown in FIG. 4 and the focus lens position detecting means 45 for detecting the position of the optical focus lens holder 5 will be described. The zoom lens position detecting means 43 and the focus lens position detector 45 have the same configuration, and each includes a magnetic pole member 57 in which different magnetic poles (S pole and N pole) are alternately arranged along the optical axis direction of the lens, and a magnetic field. It comprises an MR sensor 59 that detects the intensity. The magnetic pole member 57 is fixed to the inner surface of the housing 13 along the drive shafts 21, 22, and the MR sensor 59 is fixed to the holders 3, 5. Along with this, it is possible to detect the amount and direction of movement of each holder from the reference position (or initial position).

  As shown in FIGS. 3 and 4, the housing 13 has a substantially rectangular parallelepiped shape. The zoom lens 14 and the focus lens 16 are located at the center of the rectangle when viewed from the front, and sandwich the lenses 14 and 16. Zoom lens holder driving means 7 and focus lens holder driving means 9 are arranged on both sides. That is, the vibration member 17 is disposed on the rear side (see FIGS. 2 and 3) of the substantially rectangular parallelepiped housing 13, and the space in which the vibration member 17 is disposed has a rectangular shape in plan view. Since one side of the vibration member 17 can be disposed along the flat side wall (inner wall), the dead space can be reduced as compared with the case where the vibration member 17 is circular in plan view.

  In particular, the zoom lens driving means 7 and the zoom lens position detecting means 43 are arranged on one side of the housing sandwiching the lenses 14 and 15, and the focus lens driving means 9 and the focus lens position detecting means 45 are arranged on the other side. In this case, even if the area of the vibration member 17 is large, the rectangular shape can be arranged in the rectangular parallelepiped housing 13 and the dead space can be reduced by making the rectangular shape in plan view, and the lens driving device 1 can be made small. .

  Next, operations and effects of the first embodiment will be described. In this embodiment, the zoom lens holder 3 is moved to change the magnification by optical zoom, and the focus lens holder 5 is moved to adjust the focal length.

  When the zoom lens holder 3 is moved to the telephoto side (subject side), a predetermined pulse current is supplied to the vibration member 17, and the vibration member is expanded and contracted, and the vibration member 19 is elastically deformed and elastically restored. 17 is vibrated in the axial direction of the drive shaft 21.

  That is, when a pulse current is supplied to the piezoelectric element 23, for example, as shown in FIG. 5A, the piezoelectric element 23 is deformed so that the central portion of the vibrator 19 protrudes to the front side. Moves toward the front side, and the zoom 1 lens holder 3 moves forward because there is a frictional force with the drive shaft 21 at the press contact portion 51. Next, as shown in FIG. 5B, the vibration member 17 expands and contracts by suddenly returning to the original position and the piezoelectric element 23 contracting (or returning to the original) due to the reaction force of the vibrator 19 being elastically deformed. The zoom lens holder 3 moves forward along the drive shaft 21 by repeating the above.

  By changing the direction of the current supplied to the vibrating member 17, the pulse waveform, and the duty ratio of the pulse, the deformation of the vibrator 19 is reversed from the forward movement (FIG. 5 (b) to FIG. 5 (a)). The zoom lens holder can be retracted along the drive axis.

  Similarly to the zoom lens holder 3, the focus lens holder 5 can also be driven forward or backward along the drive shaft 22 by supplying a predetermined pulse current to the vibration member 17.

  Here, an experiment was conducted on the driving torque and the driving speed when the thickness W of the diaphragm and the frequency H of the pulse current supplied to the piezoelectric element 23 were changed. The results are shown in Table 1 and FIG. To explain.

  In the experiment, when a copper plate was used as the vibrator 19 and the thickness was changed to 0.1 mm, 0.15 mm, 0.20 mm, 0.25 mm, and 0.3 mm, a pulse current having a predetermined frequency was supplied and Drive torque and drive speed were measured. Table 1 below shows frequencies when the optimum driving torque and driving speed are obtained with respect to the thickness W of each vibrator 19.

  As is clear from the results of the experiment shown in Table 1, a driving torque of 6 to 12 g could be obtained at a predetermined frequency with respect to the thickness of each copper plate (vibrator). In the above-described embodiment, since the weight of the lens is 1 to 2 g, it is sufficient that a driving torque of 6 g or more is obtained.

  On the other hand, with respect to the thickness W of each vibrator 19, frequencies before and after the frequencies shown in Table 1 (+2, +4, +5, +7 (kHz) and -2, -4, -5, -7 (kHz) ) But we did the experiment. The result is shown in FIG. With respect to the thickness of each vibrator 19, it was possible to obtain substantially the same driving torque and driving speed in the ranges of +5 kHz and -5 kHz, respectively, but the ranges F of plus 5 kHz and minus 5 kHz, respectively (shown by the dashed line in FIG. 6). It was almost impossible to drive beyond the range shown.

  From FIG. 6, the relationship of the frequency H to the thickness W of the vibrator 19 can be expressed by an equation (Equation 1) of H≈ (23 + 215 W) ± 5 kHz.

  9A and 9B show the simulation of the vibrator 19 when the thickness W of the vibrator 19 is 0.15 and the frequency supplied to the piezoelectric element 23 is 315 kHz. Thus, at frequencies outside the above range, the vibrator 19 could not be expanded and contracted in a well-formed manner, and the drive shaft could hardly be vibrated.

  Here, with reference to FIG. 7, the manufacturing method of the vibration member 17 which concerns on this Embodiment is demonstrated. The vibration member 17 according to the present embodiment is obtained by bonding and fixing a copper metal substrate 34 having a rectangular shape in plan view and a piezoelectric substrate 36, and then cutting like a grid by vertical lines 38 and horizontal lines 39. A large number of vibrating members 17 can be easily obtained, and manufacturing is easy.

  Next, another embodiment of the present invention will be described with reference to FIG. In other embodiments described below, portions having the same operational effects as those of the above-described embodiments are denoted by the same reference numerals, and description thereof is omitted. In the following description, the portions described above are described. Differences from the embodiment will be mainly described.

  In the embodiment shown in FIG. 8, the vibrator 19 is fixed only to the periphery of the piezoelectric element 23, the vibrator side surface is exposed at the center of the piezoelectric element 23, and the piezoelectric element 23 is exposed. The base end of the drive shaft 21 (22) is directly fixed to the center portion.

  In the other embodiment shown in FIG. 8, the same effects as those of the above-described embodiment can be obtained.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the present invention.

  For example, the vibration member 17 is not limited to a square in plan view, but may be a rectangular shape or a rhombus.

  The linear driving devices 7 and 9 are not limited to being used in the lens driving device 1 of the camera 2, and may be a device that linearly moves a workpiece of a precision processing machine or linearly moves a cutting tool or the like.

  The metallic vibrator 19 is not limited to a copper plate, but may be other types of metal such as aluminum or steel.

  In the method for manufacturing the vibration member 17 shown in FIG. 7, the piezoelectric substrate 36 may be formed on the surface of the metal substrate 34 and then cut like a grid by vertical lines 38 and horizontal lines 39.

It is a figure of the linear drive device which concerns on this Embodiment, (a) is a longitudinal cross-sectional view, (b) is a top view. It is a longitudinal cross-sectional view of the camera using the lens drive device which concerns on this Embodiment. It is the perspective view which looked at the lens drive device concerning this embodiment from the back side. It is the top view which looked at the lens drive device shown in FIG. It is the figure which simulated the vibrator | oscillator when experimenting the vibration member which concerns on this Embodiment, (a) is a convex deformation | transformation state, (b) is a figure which shows a concave deformation state. It is a graph which shows the relationship between the thickness of a vibrator | oscillator, and the frequency of the electric current supplied to a piezoelectric element. It is a perspective view explaining the manufacturing method of the vibration member concerning this embodiment. It is a figure of the linear drive device which concerns on other embodiment, (a) is a longitudinal cross-sectional view, (b) is a top view. It is the figure which simulated the vibrator | oscillator when the frequency supplied to a vibrator | oscillator exceeds the predetermined range, (a) is a convex deformation | transformation state, (b) is a figure which shows a concave deformation | transformation state. It is a perspective view explaining the manufacturing method of the conventional vibration member.

DESCRIPTION OF SYMBOLS 1 Lens drive device 3 Zoom lens holder (moving body)
5 Focus lens holder (moving body)
7 Zoom lens holder drive means (linear drive)
9 Focus lens holder driving means (linear driving device)
17 Vibrating member 19 Vibrator 21 Zoom lens holder drive shaft (drive shaft)
22 Focus lens holder drive shaft (drive shaft)
23 Piezoelectric element H Frequency W Vibrator thickness

Claims (6)

A vibration member and a drive shaft having a base end fixed to the vibration member are provided. The vibration member and the drive shaft are housed in a housing, and the drive shaft vibrates in the axial direction due to vibration of the vibration member. In the linear drive device in which the moving body frictionally contacting the shaft moves linearly,
The vibration member has a rectangular outline in plan view, and has a plate-like piezoelectric element and an elastic plate-like metal vibrator, and the vibrator is fixed only to the entire surface of the piezoelectric element or only on the periphery. The base end of the drive shaft is fixed at the center of the vibrator or piezoelectric element, and the outline of the piezoelectric element and vibrator is a rectangular surface in plan view.
The drive shaft has a base end side and a tip end side slidably held in the housing, and the vibration member is fixed only to the drive shaft and is arranged with a gap between the housing and the housing. ,
By passing a pulse current through the piezoelectric element, the vibrating member is deformed alternately into a saddle shape whose central portion protrudes toward the drive shaft as a whole, and a reverse saddle shape whose central portion is recessed. A linear drive device.   2. The linear drive device according to claim 1, wherein the piezoelectric element and the vibrator have the same dimensions and the same shape in plan view, and the corners and sides coincide with each other.   A moving body comprising the casing according to claim 1 and the linear drive device according to claim 1 or 2 and in frictional contact with the drive shaft is at least one of a focus lens holder and an optical zoom lens holder of the camera. A lens driving device. The vibrator is a copper plate, the thickness W is 0.1 to 0.3 mm, and a driving torque of 6 to 12 g is obtained. When the frequency H (kHz) of the current supplied to the piezoelectric element is set, The lens driving device according to claim 3 , wherein the relational expression of H (kHz) ≈ (23 + 215 W) ± 5 kHz is satisfied. 5. The lens driving device according to claim 3, and an image sensor provided on an optical axis of the lens, wherein the casing has a substantially rectangular parallelepiped shape, and the vibration member has one side of the rectangle along a wall surface of the casing. A camera characterized by being arranged. A camera-equipped mobile phone, comprising the camera according to claim 5 .

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