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:
Nov. 28, 1978
Filed:
Aug. 18, 1977
Toshio Tanaka, Toride, JP;
Juichi Honda, Fujisawa, JP;
Sadao Mimori, Yoshikawamachi, JP;
Kazutoshi Ikegami, Kokubunji, JP;
Hitachi, Ltd., , JP;
Abstract
A safety test circuit for a combustion control apparatus. This safety test circuit is used to check the off-failure of a safety transistor actuating a safety relay which acts to stop the operation of controlled units in the event of mal-combustion or the like, and also to check the on-failure of a control transistor actuating a control relay which controls the controlled units. An operation instruction signal and the collector potential of the safety transistor are applied to a logic circuit including a flip-flop and logic gates so that the off-failure of the safety transistor can be driven to check, utilizing the electrical signal propagation delay time of the elements constituting the logic circuit, before the propagation delay time has elapsed. The logic circuit is also used for similarly checking the on-failure of the control transistor. A check signal may be additionally applied to the logic circuit so that these transistors can be tested during the continuous operation of the combustion control apparatus.