Title:
METHOD OF MONITORING ELECTRIC CHARACTERISTICS OF LARGE CURRENT DENSITY GLOW DISCHARGE AND APPARATUS THEREFOR
Document Type and Number:
Japanese Patent JPS5299935
Kind Code:
A
Abstract:
In a glow-discharge workpiece-treating system's control system, the existence of a direct short-circuit between workpiece and glow-discharge treatment chamber is ascertained. This is done by comparing a voltage-indicating signal and a current-indicating signal against respective threshold levels, and generating a short-circuit signal when the voltage-indicating signal falls below its threshold level and the current-indicating signal exceeds its threshold level. Preferably, the threshold level for the voltage-indicating signal, although lower than the arc-discharge voltage of the system, is higher than the glow-discharge voltage of the system. When used in combination with conventional arc-discharge-responsive switching action, operative for briefly interrupting and then resuming operation in response to each detected arc discharge during normal operation, this can serve to differentiate between arc discharge, which although undesirable is a part of normal operation, and, on the other hand, actual galvanic short circuiting, for which brief interruption of operation constitutes no remedy at all. In a preferred embodiment, the short-circuit detection involves automatic detection of whether the potential difference between the workpiece and the treatment chamber does or does not exceed a threshold level within a predetermined time interval, corresponding to one or several normal-operation brief interruptions of operation.
Inventors:
BERUNAA OPERU
Application Number:
JP1706377A
Publication Date:
August 22, 1977
Filing Date:
February 18, 1977
Export Citation:
Assignee:
NIPPON IONON KK
International Classes:
C23C8/36; H01J37/32; H02H1/00; H02H3/10; H05B7/16; H02H7/00; (IPC1-7): C23C11/00; C23C11/14; H05B7/16
Domestic Patent References:
| JPS4986926A | 1974-08-20 |
Foreign References:
| DE1275228U |