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:
Nov. 09, 1993
Filed:
Mar. 20, 1992
Brian Williams, Gloucestershire, GB;
David M Addison, Gloucestershire, GB;
Smiths Industries Public Limited Company, London, GB;
Abstract
The power supply of a brushless d.c. motor has a trigger circuit that controls the frequency of a ramp generator which receives an output Vs from an unregulated voltage supply. The amplitude of the output V.sub.R of the ramp generator is dependent on the amplitude of its input. A comparator receives the ramp output V.sub.R at one input and a steady voltage V.sub.D at the other input. The comparator produces a pulse output Vc, with each pulse being initiated and terminated at transitions of the ramp signal and the steady signal so that the width of each pulse increases when the unregulated voltage source decreases. The pulse output Vc is supplied to the control input of the motor's commutation circuit. The commutation circuit switches the supply voltage Vs to the coils of the motor under control of the input Vc so that its mean d.c. output is independent of variation in the supply voltage.