JP4610993B2 - Electronic equipment with ultrasonic motor - Google Patents

Description

    The present invention relates to an ultrasonic motor that frictionally drives a moving body by vibration of a vibrating body and an electronic apparatus using the same, and more particularly, to a configuration of an electronic apparatus that is driven by a mechanism that converts rotational output of the ultrasonic motor into linear motion. About.

In recent years, along with the downsizing and higher functionality of electronic devices, there are many cases where the moving part is accompanied by a linear motion. An example is the driving of a pickup in an information recording device such as a CD-ROM or DVD. In this case, generally, a method is used in which an output shaft of an electromagnetic stepping motor is used as a feed screw, and rotation of the feed screw is converted into a linear motion of an operating portion engaged therewith.
"Microstepping motor" Aoshima Tsuyoshi Journal of Precision Engineering Vol.68, NO.5, 2002, p. 637-640

    However, when an electromagnetic type stepping motor is used, there is a problem that the length of the electronic device on which the motor is mounted becomes long because the length of the motor itself is long. For this reason, for example, in a digital camera, when focusing is performed by moving the lens linearly, if the motor output shaft is aligned with the linear motion direction, the distance between the image sensor and the lens cannot be close, and focusing can be realized. There wasn't. Therefore, the motor has to be arranged in the direction orthogonal to the linear motion direction of the output shaft of the motor, and the width of the electronic device has been increased. Furthermore, since the positioning angle of the stepping motor is limited, the positioning resolution of the moving body that is linearly moved is also determined by the positioning angle. Then, changing the design parameters such as the pitch and diameter of the linear motion conversion mechanism, for example, the feed screw, so that this positioning resolution can be set to the desired value will not only limit the moving speed and driving force of the moving body but also linear motion Making the conversion mechanism difficult.

    Therefore, in order to solve the above problems, the ultrasonic motor of the present invention includes a vibrating body having a piezoelectric element, a moving body frictionally driven by vibration of the vibrating body, and a transmission member provided on the rotation center axis of the moving body. And an operating portion that linearly moves by rotation of the transmission member, and a pressure spring that transmits a force to the transmission member to generate a contact pressure between the vibrating body and the moving body.

  Alternatively, a vibrating body having a piezoelectric element, a moving body that is frictionally driven by vibration of the vibrating body, a transmission member provided on the rotation center axis of the moving body, and an operation unit that operates linearly by rotation of the transmission member, The pressure spring is configured to transmit a force to the vibrating body to generate a contact pressure between the vibrating body and the moving body.

  Alternatively, a vibrating body having a piezoelectric element, a moving body that is frictionally driven by vibration of the vibrating body, a transmission member provided on the rotation center axis of the moving body, and an operation unit that operates linearly by rotation of the transmission member; The pressure spring is configured to transmit a force to the operating part to generate a contact pressure between the vibrating body and the moving body.

  And it is set as the structure which has a pressurization spring which transmits force to the said ultrasonic motor and an operation part, and produces a contact pressure between a vibrating body and a moving body.

    According to the present invention, it is possible to reduce the size and thickness of an electronic device that requires linear motion, and it is possible to perform extremely fine positioning without reducing the operating speed of the operating portion that performs linear motion. At the same time, when the operation amount of the operation unit is the same, the rotation angle of the motor can be smaller than in the conventional case, and thus an electronic device with low power consumption can be realized.

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment 1)
Embodiment 1 of the present invention will be described with reference to FIG. FIG. 1 shows an example of an autofocus mechanism of a digital camera as an example of an electronic apparatus using the ultrasonic motor of the present invention.

  The ultrasonic motor of the present invention includes a vibrating body 3 in which a piezoelectric element 1 is bonded to an elastic body 2 having a disk shape and a protrusion 2a, a support plate 11 having a central axis 12 for fixing the center of the vibrating body 3, and a center A moving body 4 that is rotatably guided by the center shaft 12, a transmission member 5 provided on the rotation center axis of the moving body 4, and a hemispherical pivot provided at the tip of the transmission member 5. The pressure spring 7 applies pressure to 5b and the pivot 5a to apply a frictional force between the vibrating body 3 and the moving body 4. The pressure spring 7 and the support plate 11 are fixed to the casing 8 with screws 25 and 14, respectively. A male screw 5a is provided on the outer periphery of the transmission member 5 provided on the moving body 4, and a female screw 6a is provided on the operating portion 6 so as to be coupled to the male screw 5a. The guide portions 6b and 6c of the operating portion 6 are guided by guide shafts 17 and 18 fixed to the casing 8, and are configured to be movable in the direction of the arrow 21.

  When a drive signal is applied to the lead 15 connected to the piezoelectric element 1, the vibrating body 3 having the piezoelectric element 1 vibrates, and the vibration of a specific direction component is transmitted to the moving body by the protrusion 2a provided on the elastic body 2, and the moving body moves. The body 4 rotates. As the moving body 4 rotates, the transmission member 5, that is, the male screw 5 a also rotates, so that the operating unit 6 having the female screw 6 a moves in the direction of the arrow 18.

  The casing 8 is provided with an image sensor 10 made of a CCD or C-MOS sensor, and the operating portion 6 is provided with lenses 9a and 9b. By operating the lenses 9a and 9b, an autofocus mechanism can be realized. In addition, a zoom mechanism can be realized with the same mechanism, and if a pickup is provided in the operating unit 6, it is possible to drive the pickup in an information recording device such as a CD-ROM or DVD.

  Here, by providing the pressurizing spring 16 between the operating member 6 and the casing 8, rattling between the male screw 5a and the female screw 6a is eliminated. The spring force of the pressurizing spring 16 acts in a direction in which a contact pressure is generated between the vibrating body 3 and the moving body 4 regardless of the operating direction of the operating member 6, so that the output torque of the moving body 4 does not decrease.

(Embodiment 2)
A second embodiment of the present invention will be described with reference to FIG. Since the basic configuration of the electronic device is the same as that of the first embodiment, only the differences will be described.

  In FIG. 2, the tip 5 c of the transmission member 5 is guided rotatably in a guide hole 8 a provided in the casing 8. The pressure spring 19 is disposed between the casing 8 and the operating member 6. As a result, the pressure applied by the pressure spring 19 eliminates rattling between the male screw 5a and the female screw 6a, and acts as a contact pressure between the moving body 4 and the vibrating body 3 through the transmission member 5. This eliminates the need for the preload spring 16 in FIG.

(Embodiment 3)
Embodiment 3 of the present invention will be described with reference to FIG. Since the basic configuration of the electronic device is the same as that of the first embodiment, only the differences will be described.

  In FIG. 3, the tip 5 c of the transmission member 5 is guided rotatably in a guide hole 8 a provided in the casing 8. The pressure spring 20 is provided between the support plate 11 and the casing 8. A guide shaft 8b provided in the casing is passed through the hole 11a of the support plate 11, and the support plate 11 is guided so as to be movable only in the direction in which the pressing force of the pressure spring 20 acts. Accordingly, the spring force of the pressure spring 20 is applied to the vibrating body 3 via the support plate 11 and becomes a contact pressure between the vibrating body 3 and the moving body 4.

    The ultrasonic motor of the present invention requires a linear motion of the operating portion, and is particularly effective for applications that require positioning. The reading of an information recording device, the driving of a writing head, the lens of a digital camera, a video camera, etc. It can be applied as a driving source for various electronic devices such as driving.

FIG. 3 is a diagram showing a configuration of an electronic device using the ultrasonic motor according to the first embodiment of the present invention. FIG. 6 is a diagram showing a configuration of an electronic device using the ultrasonic motor according to the second embodiment of the present invention. FIG. 6 is a diagram showing a configuration of an ultrasonic motor according to a third embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Piezoelectric element 2 Elastic body 3 Vibrating body 4 Moving body 5 Transmission member 6 Operation member 7, 19, 20 Pressing spring 8 Casing 9 Lens 10 Image pick-up element 11 Support plate 12 Center shaft 17, 18 Guide shaft

Claims (3)

A moving body that rotates,
A vibrating body provided on a rotation center axis of the moving body and having a piezoelectric element that frictionally drives the moving body;
A transmission member provided on the movable body and having a male screw on the outer periphery;
An operating member having a female screw engaged with the male screw and guided so as to be movable in the direction of the rotation axis;
In the operating member, a lens provided at a position that does not overlap the vibrating body and the rotation center axis direction;
A pressure spring that transmits a force to the operating member to generate a contact pressure between the vibrating body and the moving body;
An electronic apparatus with an ultrasonic motor , comprising: In the electronic device with an ultrasonic motor according to claim 1,
An electronic apparatus with an ultrasonic motor , comprising: a second pressure spring that transmits a force to the transmission member to generate a contact pressure between the vibrating body and the moving body. The electronic apparatus with an ultrasonic motor according to claim 2, wherein the second pressure spring pressurizes a pivot provided at a tip of the transmission member.

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