Electricity: motive power systems – Impact – mechanical shock – or vibration-producing motors
Reexamination Certificate
2001-12-28
2004-01-20
Tamai, Karl (Department: 2834)
Electricity: motive power systems
Impact, mechanical shock, or vibration-producing motors
C318S112000, C318S113000, C318S128000, C318S130000, C310S361000
Reexamination Certificate
active
06680590
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an information apparatus which transmits information to a user by body sensation of vibration. For example, it relates to a vibration motor and an apparatus using this motor, such as a cellular phone, an information terminal and a watch and so on. The motor and the apparatus can be smaller, save space, consume less power and have additional functions.
Particularly, the vibration motor in this invention is formed of a brushless motor without using a position-detector of a rotor, and this vibration motor is suitable for detecting back-electromotive-force (BEMF) and to be driven. This vibration motor is equipped with a motor driver which realizes various controls such as speed-control, short brake, forward rotation, reverse rotation, start and stop and so on.
BACKGROUND ART
A conventional sensorless-brushless-motor driver which has no position-detecting device is described as follows. When the motor rests or rotates very slowly, such that back-electromotive-force (BEMF) generated at driving coils of the motor cannot be detected, an ON-OFF state of the driving-coil of each phase is switched sequentially by supplying timing pulses from outside. The motor then starts from its resting state. Such starting-circuit means is disclosed in Japanese Patent Application Non-Examined Publication No. H02-206394. Driving-circuit means, which detects BEMF generated at driving-coil and produces optimum driving timings after the motor starts, is known in Japanese Patent Application Non-Examined Publication No. H03-89889.
It is known using means that BEMF (voltage value) of the motor is proportional to the r.p.m. of a motor as speed-control means of the motor. As a vibration device, means of setting frequency and amplitude of vibration arbitrarily is disclosed in Japanese Patent Application Non-Examined Publication No. H08-149182. Means for changing vibration depending on the time is disclosed in Japanese Patent Application Non-Examined Publication No. H09-130840.
FIG. 12
is a driving circuit diagram of a vibration motor (sensorless-brushless-motor) in accordance with a first prior art example.
As shown in
FIG. 12
, each terminal of stator coils
802
,
803
and
804
is connected with power-input terminal
303
. BEMF generated from each coil
802
,
803
and
804
, are converted to rectangular pulses by comparators
721
,
722
and
723
, which are then input to timing circuit
113
. Timing circuit
113
delays leading edges and trailing edges of the rectangular pulses by electrical angle 30 degrees and produces timing signals to start powering.
Phase-switching circuit
114
inputs the timing signals from timing circuit
113
and outputs phase-switching signals to power amplifier
740
. Phase-switching circuit
114
supplies base electric currents to transistors
792
,
793
and
794
forming output-circuit
115
during 120 degree in electrical angle through power amplifier
740
. Electric currents are carried in coils
802
,
803
and
804
sequentially at the timings produced by timing circuit
113
during 120 degree in electrical angle respectively.
Power amplifier
740
is formed such that it can control the base electric current of transistors
792
,
793
and
794
based on an output signal of error amplifier
780
. Feedback is controlled such that the motor can rotate at the r.p.m. where reference voltage
781
and synthesized voltage are balanced, whereby synthesized voltage is synthesized between an output voltage of FV(frequency/voltage)-converting circuit
770
and an applied voltage of control-input terminal
701
. FV converting circuit
770
converts amplitude of BEMF generated at coils
802
,
803
, and
804
to a voltage and outputs the resultant voltage during off-time of transistors
792
,
793
and
794
. In other words an r.p.m. of the motor is converted to the voltage by FV converting circuit
770
, and the voltage feedbacks to error amplifier
780
which controls motor operating current, so that a closed loop circuit is formed. The r.p.m. of the motor is then controllable by an applied to voltage to controlling-input terminal
701
.
Capacitor
901
is used for a starting-oscillator. Capacitor
902
is used for producing ON-OFF-timing. Capacitor
903
is used for compensating phase of closed loop. Oscillating-circuit
710
, power supply
750
, switch
751
and resistor
761
are used for starting motor. The description of these elements are omitted here.
FIG. 13
is a circuit diagram of a vibration device in accordance with a second conventional example.
FIG. 14
is a circuit diagram of a vibration device in accordance with a third conventional example.
As shown in
FIG. 13
, motor
1
of the second conventional example is equipped with vibration-generating means (not shown) formed of unbalanced load at a rotor, and generates vibration by rotating the motor. Battery
2
is a secondary battery, e.g. a lithium ion battery. Transistor
11
is coupled between battery
2
and motor
1
, and transistor
12
and resistor
21
are coupled in series between them. Selecting terminal
31
or
32
is brought into contact with the minus side of the battery, thereby selecting a magnitude of vibration.
In the third conventional example shown in
FIG. 14
, a section, which corresponds to resistor
21
of the second conventional example of
FIG. 13
, is replaced with variable resistor
24
. A resistor value to be inserted to motor
1
in series is arbitrarily changeable by changing a value of variable resistor
24
with a signal of controlling-input terminal
33
, whereby a vibration magnitude and a vibration period are changeable
FIG. 15
is a speed-controlling circuit diagram of a vibration device in accordance with a fourth conventional example and disclosed in Japanese Patent Application Non-Examined Publication No. S55-109185.
FIG. 16
is a speed-error-detecting circuit diagram of the vibration device.
As shown in
FIG. 15
, first regular pulse-width-producing circuit
405
comprises N-ary counter, which uses a trailing edge of output signal of pulse-forming circuit
403
as a trigger signal.
The N-ary counter holds level “1” while the counter counts a number of output pulse of reference oscillator
108
, namely a reference clock, up to N pulses, and holds level “0” after counting N pulses. Second regular pulse-width-producing circuit
406
comprises M-ary counter, which uses a trailing edge of an output signal of first regular pulse-width-producing circuit
405
as a trigger signal. The M-ary counter holds level “1” while the counter counts a number of reference clock up to M pulses, and holds level “0” after counting M pulses. Pulse-synthesizing circuit
407
synthesizes output pulses of regular pulse-width-producing circuits
405
and
406
, and converts it to a pulse width corresponding to a speed error of motor
401
. In other words, speed-error-detecting circuit
411
comprises pulse-width-producing circuits
405
,
406
and pulse-synthesizing circuit
407
.
Filter circuit
408
smoothes an output pulse of pulse-synthesizing circuit
407
and converts it to a direct current voltage. Low-frequency-compensating circuit
409
amplifies low frequency component of outputs from filter circuit
408
. Motor-driving circuit
410
amplifies output power of low-frequency compensating circuit
409
.
FIG. 16
is a diagram of speed-error-detecting circuit
411
in FIG.
15
. As shown in
FIG. 16
, N-ary counter
421
has reference-clock-input terminal CK, output terminal DOB and clear terminal CL. Differentiating circuit
422
differentiates a trailing of a signal entering point B, and outputs a trigger signal. Set-Reset flip-flop (SR flip-flop) circuit
423
resets and sets responsive to the trigger signal at level “0”. First regular pulse-width-producing circuit
405
is composed of counter
421
, differentiation circuit
422
and RS flip flop
423
. Contents of the second regular pulse-width-producing circuit
406
are the same as first regular pulse-producing circuit
405
except count numbers N and M.
Resistors
426
and
427
supply a cur
Inoue Tomohiro
Iwayama Yoshiaki
Matsushita Electric - Industrial Co., Ltd.
Mohandesi Iraj A.
RatnerPrestia
Tamai Karl
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