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. 11, 2001
Filed:
Dec. 17, 1999
Kouji Kawamura, Chiba-ken, JP;
Miyachi Technos Corporation, Chiba-ken, JP;
Abstract
A simmer circuit,comprises a power supply unit,for the supply of a simmer current I,to an excitation lamp,and a control unit,for the control of the current value of the simmer current I,. In the control unit,a current detection signal V,from a current sensor, e.g., a Hall CT,attached to the power supply unit,is fed via a buffer amplifier,for impedance conversion to a non-inversion input terminal of an operational amplifier,for signal amplification. The amplification factor &mgr; of the operational amplifier,differs depending on which one is selected from three switches,and,A CPU,selects the switch,when switching the simmer current I,to 0.3 A for “low speed zone”, selects the switch,when switching to 2 A for “medium speed zone” and switches,when switching to 5 A for “high speed zone”. A current control circuit,provides an on/off control of the simmer current I,on the basis of a control signal from the CPU,and, during on period, compares a current detection signal &mgr; V,from the operational amplifier,with a reference current value KI from a reference current value setting unit,to provide a simmer current control so as to nullify the comparison error.