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:
Mar. 21, 2000
Filed:
Jan. 28, 1999
Joao Carlos Brito, Richardson, TX (US);
John K Rote, Dallas, TX (US);
Frederick W Trafton, Lewisville, TX (US);
Marcus M Martins, Richardson, TX (US);
Texas Instruments Incorporated, Dallas, TX (US);
Abstract
An apparatus for controlling an actuator having a moveable member and having a coil that influences movement of the member, by provision of a drive current to the coil in response to a target speed voltage signal. The invention includes an up/down counter, counting at a predetermined count rate and providing a count output. A control unit is provided for controlling the direction of count of the up/down counter depending on whether the voltage across the coil, sensed periodically a first predetermined interval after the drive current to the coil is interrupted, is greater than, or less than, a reference voltage having a predetermined relationship to the target speed voltage. A digital-to-analog converter is provided, responsive to the count output to provide a compensated voltage signal having a voltage corresponding to the count output. A voltage sensing and holding unit is provided that periodically, after the drive current is interrupted for a second predetermined interval, senses and holds a sample voltage corresponding to the voltage across the coil. A plus/minus indicator is provided that senses when the up/down counter is in a down count direction and is at a count of zero, and in response thereto changes between a plus state and a minus state. A switch node is provided, combining the sample voltage signal with the compensated voltage signal to produce a command voltage signal, and providing the command voltage signal with a polarity controlled by the state of the plus/minus indicator. Finally, a transconductance amplifier unit is provided, receiving the command voltage signal and providing the drive current to the coil in a direction determined by the state of the plus/minus indicator.