Circuit for inductive heating apparatus with multiple high frequency energy sources
AssigneeTokyo Shibaura Denki Kabushiki Kaisha
InventorHidetoshi Hirata
Life of this patent
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Abstract
An inductive heating apparatus with multiple high frequency energy source. The apparatus includes plural resonant circuits each having an inductive heating coil and plural drive circuits for driving the resonant circuits. Switch circuits enable energization of one or more of the plural resonance circuits and a logic circuit is provided to ensure that whenever two or more resonance circuits are operated, they will operate at the same frequency to prevent unwanted noise otherwise resulting from the circuits operating at different frequencies.
Claims10
A circuit for an inductive heating apparatus with multiple high frequency energy sources comprising:
- (a) plural resonant circuit means, each including an inductive heating coil coupled with a magnetic load, a capacitor connected in series to said coil, and an on-off switching device connected in parallel to said capacitor, for generating high frequency signals respectively;
- (b) a plurality of trigger circuit means, one trigger circuit means associated with each resonant circuit for detecting resonant current through an associated coil and for generating trigger pulses in response to said resonant current;
- (c) a control means, including plural input terminals connecting to operating switches, and output terminals, for producing control pulse signals according to an operating-sequence of said operating switches for actuating said resonant circuits;
- (d) a logic circuit means, connected to said plurality of trigger circuit means and said control means, for producing the same trigger signal to plural output terminals thereof in response, at least in part, to said control pulse signals;
- and
- (e) a plurality of drive circuit means, one drive circuit means connected to each of the output terminals of said logic circuit means, for operating said on-off switching devices so that said plural resonant circuit means operate at the same high frequency.
A circuit for an inductive heating apparatus comprising:
- (a) a first high frequency energy circuit including:
- (1) a first resonant circuit having an inductive heating coil for coupling to a first load, and
- (2) a first drive circuit connected to drive said first resonant circuit in response to a first trigger signal,
- (b) a second high frequency energy circuit including:
- (1) a second resonant circuit having an inductive heating coil for coupling to a second load, and
- (2) a second drive circuit connected to drive said second resonant circuit in response to a second trigger signal,
- (c) first and second switches connected to operate said first and second high frequency energy circuits,
- (d) circuit means responsive at least to said first and second switches and providing said first and second trigger signals, and
- (e) said circuit means operable for:
- (1) generating said first and second trigger signals having the same frequency whenever both said first and second switches operate said first and second high frequency energy circuits,
- (2) generating only said first trigger signal whenever only said first switch operates only said first high frequency energy circuit, and
- (3) generating only said second trigger signal whenever only said second switch operates only said second high frequency energy circuit, said first and second trigger signals having first and second, separate, load-dependent frequencies whenever only said first switch and only said second switch are operated, whereby unwanted noise produced when said
- first and second high frequency energy circuits are operated at different frequencies at the same time is eliminated by forcing said first and second resonant circuits to operate at the same frequency whenever said first and second high frequency energy circuits are operated together.
Dependencies are inferred from the claim text.