REVERSED-POLARITY PULSE GENERATING CIRCUIT FOR DIRECT CURRENT PLASMA AND DIRECT CURRENT PLASMA POWER SUPPLY UNIT
First Claim
1. A reversed-polarity pulse generating circuit for direct current plasma, comprising:
- a pair of direct current voltage terminals, to which direct current voltage from a direct current power supply for plasma is applied;
a pair of load terminals connected to a plasma load;
a capacitor connected between the pair of direct current voltage terminals;
inductance means connected between one end of the capacitor and one of the load terminals;
a unit switching circuit connected in parallel with the capacitor; and
a control circuit, to which direct current voltage of the pair of direct current voltage terminals is input, and which controls conduction of a first switching element and a second switching element in the unit switching circuit,wherein the unit switching circuit includes;
a series circuit connected in parallel with the capacitor, the series circuit having the first switching element,a first winding wire magnetically coupled to a winding wire of the inductance means or a second winding wire connected in parallel with the inductance means, andthe second switching element;
a first feedback rectifier element connected in parallel with the first switching element and the first winding wire that are connected in series with each other;
a second feedback rectifier element connected in parallel with the second switching element and the first winding wire that are connected in series with each other; and
each voltage balance resistor, which is connected in parallel with each of the first switching element and the second switching element or each of the first feedback rectifier element and the second feedback rectifier element,wherein, in a case in which the direct current voltage between the pair of direct current voltage terminals exceeds a set value, voltage at both ends of the capacitor is shared by the first switching element and the second switching element, without the first switching element and the second switching element being electrically conductive,wherein, in a case in which the direct current voltage between the pair of direct current voltage terminals is below the set value, on a periodic basis or upon detecting occurrence of abnormal electrical discharge or detecting prediction of occurrence of abnormal electrical discharge, the first switching element and the second switching element are electrically conductive, reversed-polarity voltage, which is higher than the direct current voltage between the direct current voltage terminals in a plasma generating state, is applied to the inductance means, and difference reversed-polarity voltage, of which level is equivalent to a level of difference between the direct current voltage between the direct current voltage terminals in the plasma generating state and the reversed-polarity voltage, is output between the load terminals, andwherein, in a case in which the first switching element and the second switching element are turned off, during a period in which the first feedback rectifier element and the second feedback rectifier element are electrically conductive, voltage at both ends of the capacitor restricts voltage applied to both ends of the first switching element and both ends of the second switching element.
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Accused Products
Abstract
A capacitor is connected between direct current voltage terminals, and inductance means is connected between one end of the capacitor and one of load terminals. In a case in which the direct current voltage exceeds a set value, voltage at both ends of the capacitor is shared by the first and second switching elements that are not electrically conductive; in a case in which the direct current voltage is below the set value, the first and second switching elements are electrically conductive on a periodic basis or as needed to output reversed-polarity voltage between load terminals; and in a case in which the first and second switching elements are turned off, voltage at both ends of the capacitor restricts voltage applied to both ends of the first and second switching elements, during a period in which the first and second feedback rectifier elements are electrically conductive.
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Citations
5 Claims
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1. A reversed-polarity pulse generating circuit for direct current plasma, comprising:
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a pair of direct current voltage terminals, to which direct current voltage from a direct current power supply for plasma is applied; a pair of load terminals connected to a plasma load; a capacitor connected between the pair of direct current voltage terminals; inductance means connected between one end of the capacitor and one of the load terminals; a unit switching circuit connected in parallel with the capacitor; and a control circuit, to which direct current voltage of the pair of direct current voltage terminals is input, and which controls conduction of a first switching element and a second switching element in the unit switching circuit, wherein the unit switching circuit includes; a series circuit connected in parallel with the capacitor, the series circuit having the first switching element, a first winding wire magnetically coupled to a winding wire of the inductance means or a second winding wire connected in parallel with the inductance means, and the second switching element; a first feedback rectifier element connected in parallel with the first switching element and the first winding wire that are connected in series with each other; a second feedback rectifier element connected in parallel with the second switching element and the first winding wire that are connected in series with each other; and each voltage balance resistor, which is connected in parallel with each of the first switching element and the second switching element or each of the first feedback rectifier element and the second feedback rectifier element, wherein, in a case in which the direct current voltage between the pair of direct current voltage terminals exceeds a set value, voltage at both ends of the capacitor is shared by the first switching element and the second switching element, without the first switching element and the second switching element being electrically conductive, wherein, in a case in which the direct current voltage between the pair of direct current voltage terminals is below the set value, on a periodic basis or upon detecting occurrence of abnormal electrical discharge or detecting prediction of occurrence of abnormal electrical discharge, the first switching element and the second switching element are electrically conductive, reversed-polarity voltage, which is higher than the direct current voltage between the direct current voltage terminals in a plasma generating state, is applied to the inductance means, and difference reversed-polarity voltage, of which level is equivalent to a level of difference between the direct current voltage between the direct current voltage terminals in the plasma generating state and the reversed-polarity voltage, is output between the load terminals, and wherein, in a case in which the first switching element and the second switching element are turned off, during a period in which the first feedback rectifier element and the second feedback rectifier element are electrically conductive, voltage at both ends of the capacitor restricts voltage applied to both ends of the first switching element and both ends of the second switching element. - View Dependent Claims (2, 3, 4, 5)
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Specification