The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jan. 15, 1991
Filed:
Feb. 13, 1989
Nippon Oil and Fats Company, Limited, all of, JP;
Harada Electronics Industry, all of, JP;
Hitachi Ltd., all of, JP;
Abstract
A delay circuit for use in an electric blasting system including a capacitor for storing electric energy supplied from an electric blaster, an actuation circuit for detecting the stop of voltage supply from the blaster to generate an actuation signal, a circuit for generating clock pulses, a circuit for counting a predetermined number of clock pulses in response to the actuation signal to generate an igniting signal, and a switching circuit for responding to the igniting signal to discharge the electric energy stored in the capacitor through an igniting resistor, the actuation circuit having a zener diode with a threshold voltage. When the voltage supply from the blaster is stopped and the voltage across the zener diode becomes lower than the threshold voltage, the zener diode is cut-off to generate the actuation signal.