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:
Sep. 20, 1983
Filed:
May. 20, 1980
Hitachi Koki Company, Limited, Tokyo, JP;
Abstract
In an impact printer or the like having a plurality of print-hammer drive electromagnets which are respectively connected in series with switching transistors between the terminals of a voltage source, the switching transistors are normally gated into conduction by gating signals with a duration sufficient to energize the electromagnets for operating the associated print hammers. In a test mode which occurs prior to the operation of the printer, the gating signals are successively applied to the switching transistors and the duration of each gating signal is reduced so that the gated transistor remains conductive for a short interval which is insufficient to operate the hammer. The potential at a circuit junction between the respective transistor and the associated electromagnet is coupled through a voltage divider to an input of a coincidence gate which receives its another signal from the gate electrode of the associated transistor to generate a failure indication signal when the input logic states have a predetermined relation therebetween.