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. 02, 1999
Filed:
Feb. 20, 1998
Masanari Shougomori, Kyoto, JP;
Rohm Co. Ltd., Kyoto, JP;
Abstract
A display device having driving circuits one for each of its light-emitting elements permits easy inspection of the driving circuits. The display device is formed as a fluorescent display tube that has an array of light-emitting units each consisting of a light-emitting element and its driving circuit. The display device further has a multiple-stage AND circuit consisting of 2-input AND circuits connected sequentially. One input of each stage is connected to the output of one of the driving circuits, another input of the first stage is connected to a power line, and the output of the last stage is connected to an inspection terminal, so that inspection is performed by checking whether a driving voltage appears at the inspection terminal. By activating all the driving circuits, whether they are functioning properly when they are in operation is checked globally; then, by deactivating one of the driving circuits, whether they are functioning properly when they are not in operation is checked individually. Instead of the multiple-stage AND circuit, a multiple-stage OR circuit may be used, in which case the other input of the first stage is grounded, and the output of the last stage is connected to the inspection terminal.