The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 13, 1994
Filed:
Nov. 30, 1992
Phillip C Burke, Temecula, CA (US);
Device for Vascular Intervention, Inc., Redwood City, CA (US);
Abstract
The invention provides a motor drive unit for use in conjunction with an atherectomy device which limits the torque exerted on a drive cable for rotating a cutting blade in the device. In a preferred embodiment, a motor drive unit includes a motor having a shaft coupled to the drive cable for rotating the cutting blade, a power supply coupled to the motor and a switch for selectively connecting the power supply to the motor. A torque control circuit connected to the power supply and the motor controls the torque exerted by the motor when the switch is closed, whereby the current to the motor is continuously increased from zero to a start-up level, the start-up level being the minimum current sufficient to turn the cutting blade. Usually, the torque control circuit will include a resistor and a capacitor connected to a power supply in parallel with the motor, wherein a gradually decreasing portion of current from the battery is diverted through the RC circuit to charge the capacitor such that the current to the motor is at the start-up level when the capacitor is charged. The motor drive unit further includes a power MOSFET for discharging the capacitor when the switch is opened to reset the circuit.