Electrical generator or motor structure – Non-dynamoelectric – Piezoelectric elements and devices
Reexamination Certificate
1998-05-21
2001-04-03
Dougherty, Thomas M. (Department: 2834)
Electrical generator or motor structure
Non-dynamoelectric
Piezoelectric elements and devices
C310S323170
Reexamination Certificate
active
06211603
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an ultrasonic motor used for driving printers, paper feeders, machine tools, camera zoom mechanisms, and the like and, more particularly, to an ultrasonic motor of a type such that a rectangular periodically vibrating member is supported and pressurized.
In recent years, an ultrasonic motor has been known in which a driving signal of a predetermined frequency is generated by a variable oscillator, and the driving signal is applied to a piezoelectric element via a power amplifier, by which traveling waves are generated on a vibrating body connected to the piezoelectric element to move a moving body touching the vibrating body with a predetermined pressure (for example, see Japanese Patent Publication No. Sho 62-92781).
In particular, an ultrasonic drive unit using elongation vibration and bending vibration of a rectangular piezoelectric vibrating plate (dual-mode vibrator), which is capable of effecting linear movement, rotational movement, etc. of a moving body by combined displacement of vibration mode, is expected to be used for various applications.
FIG. 13
shows an ultrasonic motor of a type using a rectangular vibrator.
This motor is made up of a piezoelectric vibrating body
14
vibrated by the application of a high-frequency voltage, a moving body
11
pressed on the vibrating body
14
, a support member
26
for supporting the vibration node of the vibrating body
14
, and a pressurizing member
33
, which is pressed on both ends of the support member
26
, for providing a pressurizing force to press the moving body
11
on the vibrating body
14
(see Jpn. J. Appl. Phys. Vol. 31 (1992) Pt. 1, No. 9BP3079).
With this unit, the moving body
11
is rotated by the combination of elongation vibration and bending vibration of the vibrating body
14
.
FIG. 14
also shows an ultrasonic motor of a type using a rectangular vibrator.
This motor is made up of a vibrating body
14
consisting of multi-layer piezoelectric elements
14
h
and a vibrating portion
14
i
connected to the piezoelectric elements
14
h
, a cylindrical support member
26
locked to the vibration node of the vibrating body
14
, protrusions
13
fixed on the lower side of the vibrating body
14
, and a moving body
11
in contact with the protrusions
13
(see Jpn. J. Appl. Phys. Vol. 34 (1995) pp2756-2759).
With this unit, the moving body
11
is moved linearly in a fixed direction by elliptical vibrations of the protrusions
13
produced by the combination of elongation vibration and bending vibration of the vibrating body
14
.
However, according to the aforementioned ultrasonic motor, because the pressurizing member
33
is needed in addition to the support member
26
, there exists technical problems in that the configuration of the unit is complicated, the whole of the unit is large in size, and loss of vibration is liable to occur for the small vibration body
14
.
Moreover, the aforesaid support member
26
is usually locked to the piezoelectric vibrating body
14
with a screw or pinning construction, so that the structural strength is not so high. Therefore, there arises a technical problem in that the pressurizing force provided to the support member
26
cannot be increased.
Further, the piezoelectric vibrating body
14
has a technical problem in that the moving direction of the moving body
11
is changed with respect to the target direction by a shift during assembly, nonuniformity of contact surface between the vibrating body
14
and the moving body
11
, and the like.
Thereupon, the present invention was made to solve the above-mentioned technical problems, and accordingly an object thereof is to provide an ultrasonic motor in which the configuration of the unit is simplified and made compact, the support structure for the piezoelectric vibrating body is strengthened, and the change in moving direction of the moving body is prevented.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an ultrasonic motor in which the configuration of the unit is simplified and made compact, since the periodically vibrating member is supported and pressurized by the node supporting/pressurizing member.
It is another object of the present invention to provide an ultrasonic motor where a sufficient frictional force is produced on the moving body, achieving stable movement, since the engagement strength with the periodically vibrating member is increased by the fitted support member, and a pressurizing force greater than before is applied to the fitted support member.
It is another object of the present invention to provide an ultrasonic motor where stable movement can be achieved against vibration deviation, since the periodically vibrating body is not displaced in any direction other than the regulating direction.
It is a further object of the present invention to provide an ultrasonic motor where the unit configuration on the side of periodically vibrating member can be made compact and simplified, since the pressurizing mechanism on the side of the periodically vibrating member is omitted.
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Patent Abstracts of Japan, vol. 1995, No. 01, Feb. 28, 1995, Publication No. 06284752, published Oct. 7, 1994 by EPO.
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Iino Akihiro
Kasuga Masao
Suzuki Makoto
Adams & Wilks
Dougherty Thomas M.
Seiko Instruments Inc.
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