Title:
PROTECTION CIRCUIT FOR ELECTROSTATIC PROCESSING UNIT
Document Type and Number:
Japanese Patent JP2567338
Kind Code:
B2
Abstract:
PURPOSE: To improve the safety by detecting a transient current before transition from a corona discharge to an iginition discharge so as to connect a high voltage opplication forcibly to ground instantaneously through plural semiconductor switching elements thereby preventing production of abnormal discharge in advance.
CONSTITUTION: A current detection circuit 5A detects a predetermined transient current before discharge transits from a corona discharge to an ignition discharge in a current from a high voltage application path 6 from a DC high voltage power supply to a load 4 and lights a light emitting diode LED 1. The light from the LED 1 is received by a photo diode of a control circuit through an optical fiber cable, the diode generates a gate pulse and it is received by gates G1-Gn of plural thyristors SCR. All the SCRs receiving the pulse at their gates G1-Gn are simultaneously turned on to connect the path 6 forcibly to ground. Thus, the charges stored in capacitors C1, C2 are instantaneously connected to ground and an applied voltage to the load 4 droppes down to zero. Thus, the production of abnormal discharge is prevented in advance and the safety is improved.
Inventors:
UEDA TAKEHIKO
Application Number:
JP17201793A
Publication Date:
December 25, 1996
Filing Date:
June 21, 1993
Export Citation:
Assignee:
KASUGA DENKI KK
HAIDEN KENKYUSHO KK
HAIDEN KENKYUSHO KK
International Classes:
B05B5/025; B29C48/92; H02H3/10; H02M7/06; H02M7/10; H03K17/08; H03K17/10; (IPC1-7): H02H3/10
Domestic Patent References:
| JP55151794A | ||||
| JP63103657A | ||||
| JP493439U |
Attorney, Agent or Firm:
Harada Shinichi