Electricity: electrical systems and devices – Safety and protection of systems and devices – Arc suppression at switching point
Reexamination Certificate
1999-11-10
2002-11-19
Leja, Ronald W. (Department: 2836)
Electricity: electrical systems and devices
Safety and protection of systems and devices
Arc suppression at switching point
C204S192120, C204S298410
Reexamination Certificate
active
06483678
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an arc extinguishing circuit; and more particularly, relates to an arc extinguishing circuit capable of extinguishing arc discharges occurring within a glow discharge when used in a power supply circuit for generating a glow discharge.
BACKGROUND ART
Conventional glow discharge power supply circuits comprise a direct current (d.c.) voltage generating circuit, with a positive terminal and a negative terminal connected to the anode and cathode of the d.c. voltage generating circuit respectively. The negative terminal is connected to a target and the positive terminal is connected to a substrate holder. A substrate is then supported by the substrate holder so that the target and a surface of the substrate (hereinafter referred to as the “substrate surface”) face each other within a low pressure atmosphere. When the d.c. voltage generating circuit is then activated and a d.c. voltage is applied across the positive terminal and the negative terminal, a glow discharge is generated across the substrate surface and the target, the target is sputtered and a thin-film is formed on the substrate surface.
However, arc discharges can occur when certain kinds of abnormalities occur within the glow discharge. When arc discharging occurs, the target is sputtered in a localized manner and the thin film is unevenly formed on the substrate surface. Depending on the circumstances, this can be destructive to the thin-film formed on the substrate surface.
In order to resolve the aforementioned problems, it is the object of the present invention to provide an arc extinguishing circuit capable-of reliably suppressing arc discharges when used in a power supply for generating a glow discharge.
SUMMARY OF THE INVENTION
An arc extinguishing circuit of the present invention comprises a switch element equipped with a control terminal and two input/output terminals, with conduction across the two input/output terminals being based on a voltage inputted to the control terminal, a sense circuit, being a circuit having a primary winding and a voltage sense capacitor connected in series, with one end thereof connected to one input/output terminal and a remaining end thereof connected to the remaining input/output terminal and a secondary winding being magnetically coupled with the primary winding and having one end connected to the control terminal and a remaining end connected to one of the input/output terminals.
The arc extinguishing circuit of the present invention can also be configured in such a manner that when a trigger current flows in the primary winding, the voltage sense capacitor discharges due to the switch element conducting due to a voltage induced in the secondary winding, and a discharge current flows in the primary winding, with the discharge current flowing in the primary winding in the same direction as the trigger current.
The arc extinguishing circuit of the present invention can also have at least one inductance element, with one end of the inductance element being connected to one or both of the input/output terminals.
An arc extinguishing circuit of the present invention a switch element equipped with a control terminal and two input/output terminals, with conduction across the two input/output terminals being based on a voltage inputted to the control terminal, a sense circuit, being a circuit having a primary winding and a voltage sense capacitor connected in series, with one end thereof connected to one input/output terminal and a remaining end thereof connected to the remaining input/output terminal, a secondary winding being magnetically coupled with the primary winding and having one end connected to the control terminal and a remaining end connected to one of the input/output terminals, a resonant circuit, constituted by a resonant inductance element and a resonant capacitor connected in series, with one end thereof connected to one input/output terminal and a remaining end thereof connected to the remaining input/output terminal and a diode inserted across one or both of said one end of the resonance circuit and said one input/output terminal or said remaining terminal of the resonance circuit and said remaining input/output terminal.
The arc extinguishing circuit of the present invention can also comprise at least one inductance element, with one end of the inductance element being connected to a terminal of the resonant capacitor.
The arc extinguishing circuit of the present invention can also comprise a voltage limiting circuit connected in parallel with the voltage sense circuit and constructed in such a manner as to prevent a voltage across the terminals of the voltage sense circuit from rising above a fixed voltage when a voltage of a polarity which is opposite to a polarity in a steady state occurs across the terminals of the resonant capacitor.
An arc extinguishing method of the present invention comprises the steps of pre-charging a resonant capacitor while supplying a fixed voltage to a load from first and second output terminals in a steady state, when load impedance rapidly drops, sensing the rapid drop in impedance, causing a switch element connected across the first and second output terminals to conduct, short-circuiting the first and second output terminals, and discharging the resonant capacitor; causing the discharged current to flow through a resonant inductance, and causing the resonant capacitor and the resonant inductance element to resonate, generating a voltage, of a polarity which is opposite to the polarity generated in the steady state, at the resonant capacitor due to the resonance and putting the switch element into a non-conducting state using the reverse voltage and having the voltage across the first and second output elements revert to the steady state voltage.
The arc extinguishing method of the present invention can further comprise the steps of pre-inserting a diode element in the path of current flowing between the first and second output terminals via the switch element when the switch element is in a conducting state and the first and second output terminals are short-circuited and reverse biasing the diode element using a voltage generated at the resonant capacitor of an opposite polarity to the voltage generated in a steady state so as to halt resonance when a current flows between the first and second output terminals via the switch element.
The arc extinguishing method of the present invention can also comprise the steps of connecting a circuit constituted by the voltage sense capacitor and the primary winding connected in series across the first and second output terminals and pre-charging the voltage sense capacitor in the steady state and, when the load impedance falls rapidly, causing a current to flow in the primary winding due to discharging of the voltage sense capacitor, inducing a voltage in a secondary winding magnetically coupled with the primary winding, and putting the switch element into a conducting state using the voltage induced at the secondary winding.
The arc extinguishing method of the present invention can further comprise the steps of connecting a delay circuit to the voltage sense capacitor and increasing the time taken from commencing charging of the voltage sense capacitor until the voltage across both terminals of the voltage sense capacitor becomes the voltage across both terminals occurring in the steady state using the delay circuit.
In the present invention having the above configuration, both terminals of a d.c. power supply for generating a d.c. voltage are respectively connected to input/output terminals of a switch element, with the input/output terminals being taken as first and second output terminals, respectively, with each being connected to an electrode that is within a vacuum. The d.c. power supply is then activated with the electrodes separated from each other, a high voltage is applied across the electrodes and a glow discharge is generated. One electrode is connected to a target and the other electrode is connected to a substrate. When the ta
Jou Hiroshi
Morita Tetsuo
Armstrong Westerman & Hattori, LLP.
Leja Ronald W.
Shindengen Electric Manufacturing Co. Ltd.
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