US 5,479,062 A · Piezo actuator driving circuit

Abstract

A driving circuit which drives piezo element connected to a movable member, thereby moving the movable member. A current from a DC power source flows in an induction device. During each drive cycle, a switch mechanism cuts the current in the induction device to induce a driving voltage from the induction device. The switch mechanism cuts the current in the induction device at a first moment in a respective drive cycle occurring when the current is increasing. The driving voltage becomes substantially flat at a second moment during the respective drive cycle occurring after the first moment in the respective drive cycle. A voltage detection device detects the driving voltage induced from the induction device and compares the driving voltage with a predetermined reference level. In accordance with the comparison by the voltage detection device at the second moment during each drive cycle, a control unit determines a first moment for the next drive cycle. More specifically, when the driving voltage is lower than the reference level, the control unit determines the first moment for the next drive cycle to be delayed to cut the current in the induction device at a larger current level. When the driving voltage is larger then the reference level, the control unit determines the first moment for the next drive cycle to be advanced to cut the current in the induction device at a lower current level.

Claims28

Dependent claims

A piezo actuator driving circuit for a piezo element which mechanically drives a mechanical member on being applied with a driving voltage thereto, comprising:

a DC power source;
induction means;
switch means for controlling a current flowing in said induction means from said DC power source, upon being cut said current inducing said driving voltage from said induction means;
voltage detection means for detecting and comparing said driving voltage with a predetermined reference level so as to output a compared result;
control means for determining a first moment to cut said current with said switch means while said current is increasing according to said compared result at a second moment when said driving voltage is substantially flat after said current is cut, such that upon receiving a result that said driving voltage is lower than said reference level said first moment is delayed so as to cut said current at a larger current level, as well as upon receiving a compared result that said driving voltage is higher than said reference level said first moment is advanced so as to cut said current at a lower current level,
whereby said driving voltage is set substantially equal to said reference voltage for each drive cycle.

3 more elements

A driving circuit for driving a piezo element with a driving voltage during respective drive cycles of sequential drive cycles, the driving circuit comprising:

a DC power source;
an induction device connected to the DC power source, a current flowing in the induction device from the DC power source during each drive cycle and having a period of increasing current during each drive cycle;
a switch mechanism which, during each drive cycle, cuts the current in the induction device to induce a driving voltage from the induction device in the respective drive cycle, the switch mechanism cutting the current in the induction device at a first moment in the respective drive cycle occurring when the current is increasing, the driving voltage becoming substantially flat at a second moment during the respective drive cycle occurring after the first moment in the respective drive cycle;
a voltage detection device detecting the driving voltage induced from the induction device, comparing the driving voltage with a predetermined reference level, and producing a corresponding output signal indicating the result of the comparison;
and
a control unit receiving the output signal of the voltage detection device and determining, in accordance with the received output signal at the second moment of a respective drive cycle, a first moment for the next drive cycle, wherein
when the received output signal indicates that the driving voltage is lower than the reference level, the control unit determines the first moment for the next drive cycle to be delayed to cut the current in the induction device at a larger current level, and
when the received output signal indicates that the driving voltage is larger then the reference level, the control unit determines the first moment for the next drive cycle to be advanced to cut the current in the induction device at a lower current level.

5 more elements

A printer which drives a piezo element with a driving voltage during respective drive cycles of sequential drive cycles, to move a movable member and cause a printing operation, the printer comprising:

a DC power source;
an induction device connected to the DC power source, a current flowing in the induction device from the DC power source during each drive cycle and having a period of increasing current during each drive cycle;
a switch mechanism which, during each drive cycle, cuts the current in the induction device to induce a driving voltage from the induction device in the respective drive cycle, the switch mechanism cutting the current in the induction device at a first moment in the respective drive cycle occurring when the current is increasing, the driving voltage becoming substantially flat at a second moment during the respective drive cycle occurring after the first moment in the respective drive cycle;
a voltage detection device detecting the driving voltage induced from the induction device, comparing the driving voltage with a predetermined reference level, and producing a corresponding output signal indicating the result of the comparison;
and
a control unit receiving the output signal of the voltage detection device and determining, in accordance with the received output signal at the second moment of a respective drive cycle, a first moment for the next drive cycle, wherein
when the received output signal indicates that the driving voltage is lower than the reference level, the control unit determines the first moment for the next drive cycle to be delayed to cut the current in the induction device at a larger current level, and
when the received output signal indicates that the driving voltage is larger then the reference level, the control unit determines the first moment for the next drive cycle to be advanced to cut the current in the induction device at a lower current level.

5 more elements

Dependencies are inferred from the claim text.

Piezo actuator driving circuit

Life of this patent

Piezo actuator driving circuit

Life of this patent

Abstract

Claims28