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:
Jun. 22, 1982
Filed:
Jan. 24, 1980
Richard L Smith, Concord, MA (US);
Polaroid Corporation, Cambridge, MA (US);
Abstract
Apparatus for positioning a projected image in response to input signals corresponding to the components of the commanded position of the image along a pair of orthogonal axes. The apparatus employs a pair of servo loops that position a projector mechanism along the respective axes. In each loop position feedback is provided by a capacitive transducer. A dielectric member is disposed between a pair of planar electrodes and moves back and forth in correspondence with movement of the projector mechanism. Consequently the area of the plates covered by the dielectric member, and thus the capacitance of the transducer, corresponds to the position of the mechanism. The capacitance of the transducer is converted to a dc signal by incorporating the capacitance in a conversion circuit that emits a series of pulses whose duty cycle is proportional to the capacitance.