JP2014150714A - Linear drive unit, camera device and electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a linear drive unit in which generation of noise in the audible area can be suppressed sufficiently, and to provide a camera device and an electronic apparatus.SOLUTION: A linear drive unit includes vibration members (18, 38) having piezoelectric elements (14, 34) telescoping in response to a drive voltage having a drive voltage waveform repeating a first section rising gently and a second section falling steeply, drive shafts (20, 40) having a shaft proximal portion being coupled with the vibration members (18, 38) and reciprocating in the axial direction at different speeds, and lens supports (26, 46) friction coupled with the drive shafts (20, 40) movably in the axial direction thereof by vibration of the drive shafts (20, 40). In the initial stage of the second section of the drive voltage waveform, the lens supports (26, 46) move to follow up the movement of the drive shafts (20, 40), and moves not to follow up the movement of the drive shafts (20, 40) in the intermediate stage of the second section.

Description

  The present invention relates to a linear drive device used for a camera or a digital camera mounted on an electronic device such as a mobile phone, a camera device using the linear drive device, and an electronic device.

  As a linear drive device (lens drive device) for driving a lens used in a conventional small camera device, there is a type that performs zooming and focusing by moving a lens support body linearly by vibrating a piezoelectric element. It was. This movement of the lens support is performed by frictionally coupling the lens support to the drive shaft connected to the piezoelectric element, and applying vibration to the drive shaft that the piezoelectric element reciprocates at different speeds, thereby causing friction between the drive shaft and the lens support. Is performed by changing with the reciprocation of this vibration.

  For example, in Patent Document 1, an elastic substrate to which a piezoelectric substrate is attached, a moving axis formed on the elastic substrate or the piezoelectric substrate so that one side is fixed and interlocked with the displacement of the piezoelectric substrate, A linear drive device is described that includes a movable body formed to be movable along the same. This moving body is used as a lens support. As the driving voltage for driving the linear driving device, a rectangular wave having a repetitive waveform and a triangular wave having different rising and falling times are disclosed.

Korean Patent No. 10-0768888

  However, in the conventional linear drive device, although the piezoelectric element is driven in the ultrasonic frequency region, noise in the audible region may occur when the lens support moves. For this reason, for example, there is a problem that the noise may be recorded even when a moving image is shot.

  The present invention solves the above-described conventional problems, and an object thereof is to provide a linear drive device, a camera device, and an electronic apparatus that can suppress the generation of noise in the audible region.

  In order to achieve the above object, a linear drive device of the present invention includes a piezoelectric element that expands and contracts in response to a drive voltage having a drive voltage waveform that repeats a first section that rises gently and a second section that falls steeply. A vibration member having a shaft base end portion coupled to the vibration member and performing a reciprocating vibration in the axial direction at different speeds, and being movable in the axial direction of the drive shaft by vibration of the drive shaft A movable body frictionally coupled to the drive shaft, and the movable body moves following the movement of the drive shaft at an initial stage of the second section of the drive voltage waveform, and is an intermediate stage of the second section. Then, the moving body moves without following the movement of the drive shaft.

  In order to achieve the above object, the above-described linear drive device of the present invention includes a drive control unit, and the drive control unit generates a drive voltage having the drive voltage waveform.

  With these configurations, the intended purpose can be achieved.

  According to the present invention, a vibration member having a piezoelectric element that expands and contracts in response to a drive voltage having a drive voltage waveform that repeats a first section that rises gently and a second section that falls steeply, and a shaft on the vibration member. A drive shaft that reciprocally vibrates in the axial direction at different speeds by coupling the base end portions, and a moving body that is frictionally coupled to the drive shaft so as to be movable in the axial direction of the drive shaft by vibration of the drive shaft The moving body moves following the movement of the drive shaft at an initial stage of the second section of the drive voltage waveform, and the movable body moves the drive shaft at an intermediate stage of the second section. In such a configuration, a drive control unit is further provided, and the drive control unit is configured to generate a drive voltage having the drive voltage waveform. Shift of drive shaft The acceleration of the drive shaft at the moment the moving body has to follow no longer follow the small, the effect is obtained that the generation of noise is small.

It is sectional drawing which shows the structure of the linear drive device of Embodiment 1 of this invention. It is a figure which shows the relationship between the drive voltage of Embodiment 1 of this invention, a drive shaft, and the displacement of a lens support body (moving body).

  The linear drive device according to claim 1, wherein the vibrating member includes a piezoelectric element that expands and contracts in response to a drive voltage having a drive voltage waveform that repeats a first section that rises gently and a second section that falls steeply. A drive shaft that reciprocates in the axial direction at different speeds by coupling the shaft base end to the vibration member, and frictionally coupled to the drive shaft so as to be movable in the axial direction of the drive shaft by vibration of the drive shaft A moving body, and the moving body moves following the movement of the drive shaft at an initial stage of the second section of the drive voltage waveform, and the moving body moves at the intermediate stage of the second section. It moves without following the movement of the drive shaft.

  When the drive voltage waveform falls sharply in the second section, the movement of the moving body does not follow the movement of the drive shaft in the intermediate stage of the second section. On the other hand, the drive voltage waveform falls more gently in the initial stage of the second section than in the intermediate stage of the second section, so that the movement of the moving body is caused to move on the drive shaft in the initial stage of the second section. Follow the move.

  Thereby, since the acceleration of the drive shaft at the moment when the moving body that has followed the movement of the drive shaft does not follow, the effect that the generation of noise is small is obtained.

  The linear drive device according to claim 2 is the linear drive device according to claim 1, wherein the moving body moves following the movement of the drive shaft at the final stage of the second section of the drive voltage waveform. Features.

  The drive voltage waveform that falls steeply in the second section falls at a final stage of the second section more slowly than an intermediate stage of the second section, as in the initial stage. The movement of the body can follow the movement of the drive shaft.

  Thereby, the acceleration of the drive shaft at the moment when the moving body that has not followed the movement of the drive shaft at the intermediate stage in the second section of the drive voltage waveform follows the movement of the drive shaft is reduced. Therefore, an effect that noise generation is further reduced can be obtained.

  The linear drive device according to claim 3 is the linear drive device according to claim 1 or 2, wherein the piezoelectric element is attached to at least one surface of the elastic substrate.

  As a result, the vibration member includes an elastic substrate and the piezoelectric element attached to at least one surface of the elastic substrate. Therefore, the thickness of the vibration member in the axial direction of the drive shaft can be reduced. In addition, the axial thickness of the linear drive device can be reduced.

  The linear drive device according to claim 4 is the linear drive device according to any one of claims 1 to 3, further comprising a drive control unit, wherein the drive control unit generates the drive voltage having the drive voltage waveform. It is characterized by.

  The drive control unit is configured to generate the drive voltage having the drive voltage waveform described above.

  The camera device according to claim 5, wherein the moving body is a lens support that supports a lens, and the linear drive device according to claim 1, and the drive voltage having the drive voltage waveform. The drive control part to produce | generate and the image pick-up element which receives the light which the said lens converged were provided.

  Noise generation in the camera device is small. Therefore, for example, when shooting a moving image, the noise is difficult to be recorded.

  According to a sixth aspect of the present invention, an electronic apparatus includes the camera device according to the fifth aspect.

  Noise generation in electronic equipment is small. Therefore, for example, when shooting a moving image with an electronic device such as a mobile phone equipped with a camera device, the noise is difficult to be recorded.

(Embodiment 1)
Hereinafter, a linear drive device according to Embodiment 1 of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, the electronic apparatus 1 includes a camera device 3, and the camera device 3 includes a linear drive device 10.

  The electronic device 1 includes, for example, portable devices such as a mobile terminal device typified by a mobile phone or a smartphone or a palm-sized personal computer. In addition, stationary devices such as surveillance camera systems are also included.

  In the first embodiment, the linear driving device 10 is a lens driving device for driving a zoom lens and / or a focus lens.

  The linear drive device 10 includes drive members 22 and 42 and lens supports 26 and 46 as moving bodies.

  The drive members 22 and 42 have the vibration members 18 and 38 and the drive shafts 20 and 40.

  The vibrating members 18 and 38 have piezoelectric elements 14 and 34. The piezoelectric elements 14 and 34 expand and contract in response to a drive voltage having a drive voltage waveform that repeats a first section that rises gently and a second section that falls sharply as shown in FIG.

  The drive shafts 20 and 40 are coupled to the vibration members 18 and 38 and the shaft base ends are moved to reciprocate and vibrate in different axial directions.

  The lens supports 26 and 46 are frictionally coupled to the drive shafts 20 and 40 so as to be movable in the axial direction of the drive shafts 20 and 40 due to vibrations in the axial direction in which the speeds of the drive shafts 20 and 40 reciprocate are different.

  The lens supports 26 and 46 are for supporting the lenses 24 and 44 that focus light from a subject (not shown) on the image sensor 56.

  In the first embodiment, the lens 24 is a zoom lens, and the drive member 22 and the lens support 26 are a group for a zoom lens. The lens 44 is a focus lens, and the drive member 42 and the lens support 46 are a group for the focus lens.

  The drive members 22 and 42 include the vibration members 18 and 38 and the drive shafts 20 and 40.

  The vibration members 18 and 38 are configured by attaching the piezoelectric elements 14 and 34 to at least one surface of the elastic substrates 16 and 36.

  The elastic substrates 16 and 36 are metal plates such as copper having elasticity. The piezoelectric elements 14 and 34 are elements having a piezoelectric effect such as PZT (lead zirconate titanate).

  Power supply terminals (not shown) are provided on both surfaces of the piezoelectric elements 14 and 34. One of the power supply terminals may also serve as the elastic substrates 16 and 36.

  Although FIG. 1 shows an example of a so-called unimorph type in which the piezoelectric elements 14 and 34 are attached to one surface of the elastic substrates 16 and 36, a so-called bimorph type in which the piezoelectric elements 14 and 34 are attached to both surfaces of the elastic substrates 16 and 36 is shown. It does not matter. Also, a so-called laminated type may be used.

  By using the unimorph type or bimorph type vibration members 18 and 38, the thickness of the axial vibration members 18 and 38 can be reduced, so that the axial thickness of the linear drive device 10 can be reduced.

  The drive shafts 20 and 40 are shafts made of lightweight carbon or the like, and one end face which is a shaft base end portion is fixed to one surface of the vibration members 18 and 38. Fixing may be adhesive. Other methods may be used.

  You may make it the area of the end surface of the drive shafts 20 and 40 fixed become smaller than the area of a shaft main-body part. Since the area contributing to the vibration of the vibration members 18 and 38, which will be described later, increases accordingly, the driving force can be increased even if the outer diameter dimensions of the vibration members 16 and 36 are the same.

  The drive members 22 and 42 are fixed to the housing 12 by supporting both ends of the drive shafts 20 and 40 by being elastically pressed from the outer peripheral side by rubber bushes 52. Therefore, the vibration members 18 and 38 are not in contact with members other than the drive shafts 22 and 42 except for the power feeding related members. Accordingly, there is no vibration attenuation due to contact with a member such as the housing 12, so that the driving force transmitted to the driving shafts 20 and 40 is large.

  The ends of the drive shafts 20 and 40 opposite to the vibrating members 18 and 38 are bonded and fixed to the rubber bushing 52, but the ends close to the vibrating members 18 and 38 are not bonded.

  The lens support bodies 26 and 46 which are moving bodies are disposed on the main body portions of the drive shafts 20 and 40 while being supported by both rubber bushings 52.

  The drive shafts 20 and 40 are assembled so that the axial directions thereof coincide with the optical axis direction.

  The lens supports 26 and 46 are made of resin and have a hole at the center so that the lenses 24 and 44 can be supported.

  The contact portions of the lens supports 26 and 46 with the drive shafts 20 and 40 are made of a metal member and are urged by a spring or the like (not shown) so as to be in line contact with the drive shafts 20 and 40 in a cross section. Have been friction coupled. Since they are only frictionally coupled, the lens supports 26 and 46 can move on the drive shafts 20 and 40 along the axial direction.

  The opposite side of the lens support 26, 46 that is frictionally coupled to the drive shafts 20, 40 is U-shaped, and the drive shafts 40, 20 are arranged inside the U-shape, so that the lens support is provided. 26 and 46 are prevented from rotating around the drive shafts 20 and 40.

  The housing 12 is an exterior of the linear drive device 10, and driving members 22 and 42, lens supports 26 and 46 as moving bodies, position sensors 28 and 48 described later, and the like are arranged at predetermined positions. The housing 12 is made of resin, and is provided with a hole for placing the lens 54 at the center of the subject side and an opening for placing the substrate 58 with the image sensor 56 attached to the side opposite to the subject side. .

  Light from the subject is focused on the image sensor 56 through the lenses 54, 24 and 44. The image sensor 56 receives the light focused by the lenses 54, 24 and 44. The light received by the image sensor 56 is converted into an electrical signal and output to the camera device 3 body.

  The position sensors 28 and 48 are sensors for detecting the positions of the lens supports 26 and 46 in the axial direction and outputting them to the drive controller 60.

  In the first embodiment, MR sensors are provided on the lens supports 26 and 46 as the position sensors 28 and 48, and scales 30 and 50 are provided on the housing 12 as magnetic scales. As the scales 30 and 50, magnetic poles directed to the position sensors 28 and 48 are alternately arranged in the optical axis direction. The position sensors 28 and 48 and the scales 30 and 50 may be arranged on either the lens support 26 or 46 or the housing 12.

  In the first embodiment, MR sensors are used as the position sensors 28 and 48. However, Hall sensors or the like may be used, and the scales 30 and 50 need not be used depending on the sensor type.

  The drive control unit 60 moves the lens supports 26 and 46 by applying a driving voltage having a repetitive waveform as shown in FIG. 2 to the piezoelectric elements 14 and 34. The repetition frequency is in the ultrasonic frequency domain.

  Next, the relationship between the waveform of the drive voltage generated by the drive control unit 60 and the displacement of the drive shafts 20 and 40 and the lens supports 26 and 46 will be described.

  As shown in FIG. 2, the waveform of the drive voltage repeats a first section that rises gently and a second section that falls sharply.

  In the first section, the piezoelectric elements 14 and 34 slowly expand in the thickness direction and contract in the in-plane direction in response to the drive voltage waveform that rises gently. On the other hand, since the elastic substrates 16 and 36 do not deform so as to expand and contract like the piezoelectric elements 14 and 34, the vibrating members 18 and 38 deform in a bow shape so that the central portion moves upward in FIG. Therefore, as shown in FIG. 2, the drive shafts 20 and 40 move slowly upward along with the deformation of the vibration members 18 and 38, and the lens supports 26 and 46 follow the movement of the drive shafts 20 and 40 and move upward. Move to.

  Next, following the first period, a second period in which the drive voltage waveform falls steeply is entered. Corresponding to the steep fall of the drive voltage waveform, the piezoelectric elements 14 and 34 rapidly shrink in the thickness direction and extend in the in-plane direction. For this reason, the bow-like deformation of the vibrating members 18 and 38 tends to return rapidly, the drive shafts 20 and 40 move rapidly downward, and the lens supports 26 and 46 also move downward.

  Here, in the first embodiment, the drive voltage waveform that falls steeply in the second section falls more gently in the initial stage of the second section than in the intermediate stage of the second section. That is, in the initial stage of the second section, the driving voltage waveform becomes steep as the time falls, but falls more slowly than the intermediate stage of the second section. Thereby, in the initial stage of the second section, the lens supports 26 and 46 move downward following the movement of the drive shafts 20 and 40.

  In the intermediate stage of the second section in which the drive voltage waveform falls sharply, the acceleration of the drive shafts 20 and 40 overcomes the frictional force with the lens supports 26 and 46, and the movement of the lens supports 26 and 46 is driven by the drive shaft. It becomes non-following to the movement of 20, 40. In the intermediate stage of the second section, the drive shafts 20 and 40 are further accelerated and moved downward in response to the steep falling of the drive voltage waveform, and the lens supports 26 and 46 are moved by the drive shafts 20 and 40. Moves downward due to inertia without following.

  After the drive voltage waveform falls most steeply and the drive shafts 20 and 40 reach the maximum speed, the drive voltage waveform falls more slowly than the intermediate stage of the second section in the final stage of the second section. That is, at the final stage of the second interval, the driving voltage waveform starts to fall slowly and gradually falls with time. Correspondingly, the moving speed of the drive shafts 20 and 40 is reduced.

  Thus, in the final stage of the second section, the drive voltage waveform falls more gently than in the intermediate stage of the second section, so that the moving speed of the drive shafts 20 and 40 and the moving speed of the lens supports 26 and 46 coincide. The lens supports 26 and 46 move following the movement of the drive shafts 20 and 40.

  The lens supports 26 and 46 move upward in a period of the drive voltage waveform by an amount not following the movement of the drive shafts 20 and 40 in the intermediate stage of the second section.

  In the second section, since the acceleration of the drive shafts 20 and 40 at the moment when the lens supports 26 and 46 that have followed the movement of the drive shafts 20 and 40 do not follow, the generation of noise is small.

  In particular, in the initial stage of the second section, the driving voltage waveform that falls more slowly than the intermediate stage of the second section becomes sharper as the time elapses, and becomes sharper in the intermediate stage of the second section. By controlling the drive voltage so as to shift to the falling drive voltage waveform, the acceleration of the drive shafts 20 and 40 at the moment when the lens supports 26 and 46 that have followed the movement of the drive shafts 20 and 40 do not follow. Becomes smaller. This reduces noise generation.

  Further, in the intermediate stage of the second section, the acceleration of the drive shafts 20 and 40 at the moment when the lens supports 26 and 46 that did not follow the movement of the drive shafts 20 and 40 follow the movement of the drive shafts 20 and 40. Is small, noise can be further reduced.

  In particular, the driving voltage waveform at the final stage of the second interval falls more slowly than the intermediate stage of the second interval, and at this final stage, the driving voltage waveform starts to fall slowly and as time passes. By controlling the drive voltage so that the falling direction becomes gentle, the moment when the lens supports 26 and 46 that have not followed the movement of the drive shafts 20 and 40 follow the movement of the drive shafts 20 and 40. The acceleration of the drive shafts 20 and 40 becomes smaller. This further reduces noise.

  Since the noise generated from the linear drive device 10 is small, the generation of noise in the camera device 3 and the electronic device 1 can be suppressed. Therefore, for example, even when attempting to shoot a moving image, it is difficult for noise to be recorded.

  Since the absolute value of the drive voltage and the rise and fall of the drive voltage waveform are relative, it is the same even if the rise and fall of the first interval and the second interval are reversed, and the voltage value is The same is true regardless of where the zero point is set and whether the sign is reversed. Further, since the drive voltage has a repetitive waveform, any point in the cycle may be used as the start point / end point.

  In the first embodiment, regarding the transition from the first section to the second section and the transition from the second section to the first section, the next section starts without any interval, but the interval is opened. A section with a constant driving voltage may be provided.

  Further, the time of the first section and the time of the second section are preferably about 3 to 1, and in the first embodiment, it is 3 to 1, but it may be about 2 to 1 or about 4 to 1.

  Further, in the case of the unimorph type or the bimorph type, in the second section where the drive voltage falls steeply, the drive voltage is instantaneously lowered to deform the vibration members 18 and 38 warped in a bow shape, so that the elastic substrates 16 and 36 are deformed. It may be restored by the elastic restoring force. However, in the case of the first embodiment, the deformation of the vibrating members 18 and 38 is returned to the original by following the change of the drive voltage, instead of being restored by the elastic restoring force of the elastic substrates 16 and 36. Is preferable. This is because it is possible to reduce the acceleration of the drive shafts 20 and 40 by following the change of the drive voltage and returning the deformation of the vibrating members 18 and 38 to the original state, so that the generation of noise can be further suppressed.

  In the first embodiment, the linear driving device 10 is a lens driving device that moves the lens supports 26 and 46 in the optical axis direction. However, the present invention is not limited to this, and for example, a lens driving device in which a lens support that supports a lens for camera shake correction is used as a moving body, and a drive shaft is arranged so that the axial direction is orthogonal to the optical axis. good. Moreover, you may use as other than a lens drive device.

DESCRIPTION OF SYMBOLS 1 Electronic device 3 Camera apparatus 10 Linear drive device 12 Case 14, 34 Piezoelectric element 16, 36 Elastic board 18, 38 Vibration member 20, 40 Drive shaft 22, 42 Drive member 24, 44, 54 Lens 26, 46 Lens support body (Moving body)
28, 48 Position sensors 30, 50 Scale 52 Rubber bushing 56 Image sensor 58 Substrate 60 Drive controller

Claims (6)

A vibrating member having a piezoelectric element that expands and contracts in response to a driving voltage having a driving voltage waveform that repeats a first section that rises gently and a second section that falls steeply;
A driving shaft for reciprocating in the axial direction at different speeds by coupling a shaft base end to the vibrating member;
A moving body frictionally coupled to the drive shaft so as to be movable in the axial direction of the drive shaft by vibration of the drive shaft;
In the initial stage of the second section of the drive voltage waveform, the movable body moves following the movement of the drive shaft, and in the intermediate stage of the second section, the movable body does not follow the movement of the drive shaft. A linear drive device characterized by moving. 2. The linear drive device according to claim 1, wherein the movable body moves following the movement of the drive shaft at a final stage of the second section of the drive voltage waveform.   The linear drive device according to claim 1, wherein the piezoelectric element is attached to at least one surface of an elastic substrate.   4. The linear drive device according to claim 1, further comprising a drive control unit, wherein the drive control unit generates the drive voltage having the drive voltage waveform. 5.   The linear drive device according to claim 1, wherein the movable body is a lens support that supports a lens, a drive control unit that generates the drive voltage having the drive voltage waveform, and the lens. An image sensor for receiving the light focused by the camera device.   An electronic apparatus comprising the camera device according to claim 5.