Reversible piezoelectric positioning device and a disk drive using same

A reversible piezoelectric positioning device of a rotary type comprising:

• a rotor of a cylindrical shape, said rotor having an outer surface, said rotor having a natural elastic compression limit,
• a reversible piezoelectric actuator having a hard edge, said actuator placed perpendicularly to, in linear contact with, and urged against said rotor by having said hard edge positioned along said outer surface of said rotor, said actuator containing a piezoelectric plate equipped with a first set of electrodes and a second set of electrodes, and
• a control unit for supplying electrical impulses to said first or said second sets of electrodes for causing periodic oscillations of said actuator in a first direction or a second direction respectively, said second direction being opposite to said first direction,
• whereby said oscillations in said first or said second direction by said actuator causing compressions of said rotor and its respective rotation in the same direction, said compressions not exceeding said natural elastic compression limit, and cessation of said compressions causing said outer surface of said rotor to fully restore its initial shape.

A reversible piezoelectric positioning device of a linear type comprising:

• a slider having a linear insert, said insert having a natural elastic compression limit,
• a reversible piezoelectric actuator having a hard edge, said actuator placed perpendicularly to, in linear contact with, and urged against said slider by having said hard edge positioned along said insert of said slider, said actuator containing a piezoelectric plate equipped with a first set of electrodes and a second set of electrodes, and
• a control unit for supplying electrical impulses to said first or said second sets of electrodes for causing periodic oscillations of said actuator in a first direction or a second direction respectively, said second direction being opposite to said first direction,
• whereby said oscillations in said first or said second direction by said actuator causing compressions of said insert and its respective movement in the same direction, said compressions not exceeding said natural elastic compression limit, and cessation of said compressions causing said insert of said slider to fully restore its initial shape.

A disk drive device for recording and reading data from a disk, said device comprising:

• a housing,
• a disk retaining and rotating means,
• a movable arm having a first end, said arm rotatably attached to said housing at said first end, said arm having an outer arcuate surface with a natural elastic compression limit, said arcuate surface being opposite said first end,
• a readout head positioned along said arcuate surface of said arm, said readout head placed adjacent said disk,
• a reversible piezoelectric actuator having a hard edge, said actuator placed in linear contact with and urged against said arcuate surface of said arm along said hard edge, said actuator equipped with a first set of electrodes and a second set of electrodes, and
• a control unit for supplying electrical impulses to said first or said second sets of electrodes for causing periodic oscillations of said actuator in a first direction or a second direction respectively, said second direction being opposite to said first direction,
• whereby said oscillations in said first or said second direction by said actuator causing compressions of said arcuate surface of said arm and its respective movement in the same direction, said compressions not exceeding said natural elastic compression limit, and cessation of said compressions causing said arcuate surface of said arm to fully restore its initial shape.

The disk drive device for recording and reading data from a disk, said device comprising:

• a housing,
• a disk retaining and rotating means,
• a movable arm having a first end and a second end,
• an arm moving means containing a wheel for activating said moving means, said wheel having a natural elastic compression limit, said arm attached to said means at said second end,
• a readout head positioned at said first end of said arm, said readout head placed adjacent said disk,
• a reversible piezoelectric actuator having a hard edge, said actuator placed in linear contact with and urged against said wheel along said hard edge, said actuator equipped with a first set of electrodes and a second set of electrodes, and
• a control unit for supplying electrical impulses to said first or said second sets of electrodes for causing periodic oscillations of said actuator in a first direction or a second direction respectively, said second direction being opposite to said first direction,
• whereby said oscillations in said first or said second direction by said actuator causing compressions of said wheel and its respective rotation in the same direction, said compressions not exceeding said natural elastic compression limit, and cessation of said compressions causing said wheel to fully restore its initial shape.

A control method for a reversible piezoelectric positioning device, said device comprising a movable element having a natural elastic compression limit, a reversible piezoelectric actuator having a hard edge, said actuator placed in linear contact with and urged against said movable element along said hard edge, said actuator equipped with a first set of electrodes and a second set of electrodes, and a control unit for supplying electrical impulses to said first or said second sets of electrodes for causing periodic oscillations of said actuator and therefore compressions of said movable element, said compressions not exceeding said natural elastic compression limit, cessation of said compressions causing said movable element to fully restore its initial shape, said method comprising the steps of:

• supplying an electrical impulse having a first voltage from said control unit to said first set of electrodes for causing an oscillation of said actuator in a first direction and respective movement of said movable element in the same direction, supplying an electrical impulse having a second voltage from said control unit to said second set of electrodes for causing an oscillation of said actuator in a second direction and respective movement of said movable element in the same direction, said second direction being the opposite of said first direction, said second voltage being less than said first voltage, repeating the previous steps.