Electrical generator or motor structure – Non-dynamoelectric – Piezoelectric elements and devices
Reexamination Certificate
1998-12-10
2001-04-10
Budd, Mark O. (Department: 2834)
Electrical generator or motor structure
Non-dynamoelectric
Piezoelectric elements and devices
Reexamination Certificate
active
06215224
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a driving device for a vibration type actuator to be controlled by a periodic signal generating circuit of which frequency can be digitally adjusted in a small unit.
2. Related Background Art
The speed or the position of a vibration type actuator is controlled by the control of the driving frequency, and periodic signal generating circuits of following types are known for varying the driving frequency:
1) A periodic signal generating circuit disclosed in the U.S. Pat. No. 3,976,945 utilizes integra means and defining, as the delay amount, the time until the integration result by the integral means reaches a value set by D/A converting means thereby generating an arbitrary timing;
2) A periodic signal generating circuit disclosed in the Japanese Patent Application Laid-open No. 4-351008 utilizes a logic element as the delay element and generates an arbitrary timing by selecting an arbitrary number of delay elements, with such control that the total delay time coincides with the reference period;
3) A periodic signal generating circuit disclosed in the Japanese Patent Application Laid-open No. 2-184277 improves the resolution of frequency in pseudo manner by digitally switching the frequency dividing ratio at small intervals and meaning them.
The periodic signal generating circuit disclosed in the U.S. Pat. No. 3,976,945 is associated with a drawback that the desired timing is difficult to obtain unless the current supplied to the integral means is precisely controlled, and, in case of dividing a reference period, there may result a fluctuation in the number of division.
The periodic signal generating circuit disclosed in the Japanese Patent Application Laid-open No. 4-351008 is associated with a drawback that the number of the logic elements required for delay is basically equal to the number of division, so that there is required a vary large number of elements including the number of selecting means for selecting the delay amount.
Also in the periodic signal generating circuit disclosed in the Japanese Patent Application Laid-open No. 2-184277, as the resolution of the frequency is set in pseudo manner, the modulation component of frequency may fall in the audible range.
SUMMARY OF THE INVENTION
One aspect of the present application is to provide a control device for a vibration type actuator in which the driving force is obtained by applying a periodic signal to an electro-mechanical energy conversion element, the control device comprising:
a periodic signal forming circuit for receiving pulses of a reference period and forming a signal of a period of an integral multiple of the reference period of the pulses;
a data setting circuit for setting data for dividing, with an integer, one period of the pulses of the reference period;
an analog signal forming circuit for forming an analog signal based on the signal from the periodic signal forming circuit and the data of the data setting circuit;
a low-pass filter for entering the analog signal from the analog signal forming circuit;
a conversion circuit for converting the output of the low-pass filter, by comparison thereof with a predetermined level, into pulse signals; and
a driving circuit for forming the periodic signal from the pulse signal from the conversion circuit thereby driving the electro-mechanical energy conversion element;
wherein the drive is achieved with a higher precision than in the drive with the frequency of the above-mentioned pulse period.
One aspect of the present application is to provide a control device for a vibration type actuator in which the driving force is obtained by applying a periodic signal to an electro-mechanical energy conversion element, the control device comprising:
an analog signal forming circuit for receiving pulses of a reference period and forming a first analog signal and a second analog signal based on a period corresponding to an integral multiple of the period of the pulses and also forming a third analog signal of a value between those of the first and second analog signals for a duration shorter than the period corresponding to the integral multiple of the period of the pulses;
a low-pass filter for entering the analog signals from the analog signal forming circuit;
a conversion circuit for converting the output of the low-pass filter, by comparison thereof with a predetermined level, into pulse signals; and
a driving circuit for forming the periodic signal from the pulse signal from the conversion circuit thereby driving the electro-mechanical energy conversion element;
wherein the drive is achieved with a higher precision than in the drive with the frequency of the above-mentioned pulse period.
One aspect of the present application is to provide a control device for a vibration type actuator in which the driving force is obtained by applying a periodic signal to an electro-mechanical energy conversion element, the control device comprising:
a periodic signal forming circuit for receiving pulses of a reference period and forming a signal of a period of an integral multiple of the reference period of the pulses;
a data setting circuit for setting data for dividing, with an integer, one period of the pulses of the reference period;
an analog signal forming circuit for forming an analog signal based on the signal from the periodic signal forming circuit and the data of the data setting circuit;
an integrator for receiving the analog signal from the analog signal forming circuit;
a conversion circuit for converting the output of the integrator, by comparison thereof with a predetermined level, into pulse signals; and
a driving circuit for forming the periodic signal from the pulse signal from the conversion circuit thereby driving the electro-mechanical energy conversion element;
wherein the drive is achieved with a higher precision than in the drive with the frequency of the above-mentioned pulse period.
One aspect of the present application is to provide a control device for a vibration type actuator in which the driving force is obtained by applying a periodic signal to an electro-mechanical energy conversion element, the control device comprising:
an analog signal forming circuit for receiving pulses of a reference period and forming a first analog signal and a second analog signal based on a period corresponding to an integral multiple of the period of the pulses and also forming a third analog signal of a value between those of the first and second analog signals for a duration shorter than the period corresponding to the integral multiple of the period of the pulses;
an integrator for receiving the analog signal from the analog signal forming circuit;
a conversion circuit for converting the output of the integrator, by comparison thereof with a predetermined level, into pulse signals; and
a driving circuit for forming the periodic signal from the pulse signal from the conversion circuit thereby driving the electro-mechanical energy conversion element;
wherein the drive is achieved with a higher precision than in the drive with the frequency of the above-mentioned pulse period.
One aspect of the present application is to provide a control device for a vibration type actuator in which the driving force is obtained by applying a periodic signal to an electro-mechanical energy conversion element, the control device comprising:
an analog signal forming circuit for receiving pulses of a reference period and forming a first analog signal at a timing based on a period corresponding to an integral multiple of the period of the pulses and also forming a third analog signal of a value smaller than that of the first analog signal for a duration shorter than the period corresponding to the integral multiple of the period of the pulses;
a low-pass filter for entering the analog signals from the analog signal forming circuit;
a conversion circuit for converting the output of the low-pass filter, by comparison thereof with a predetermined level, into pulse signals; and
a driving circuit for forming th
Atsuta Akio
Hayashi Tadashi
Ito Jun
Kataoka Kenichi
Yamamoto Shinji
Budd Mark O.
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
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