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:
Mar. 17, 1992
Filed:
May. 23, 1989
Kazuyoshi Shoji, Akishima, JP;
Takaaki Hagiwara, Hinode, JP;
Tadashi Muto, Iruma, JP;
Shun-ichi Saeki, Higashimurayama, JP;
Yasurou Kubota, Akishima, JP;
Kazuto Izawa, Musashino, JP;
Yoshiaki Kamigaki, Tokorozawa, JP;
Shin-ichi Minami, Kodaira, JP;
Yuko Nabetani, Hinode, JP;
Hitachi, Ltd., Tokyo, JP;
Hitachi VLSI Engineering Corp., Tokyo, JP;
Abstract
A time circuit is provided for a nonvolatile memory device which can electrically be written into. When the write operation on a particular memory cell lasting a relatively long period of time is specified from an external device, the memory device stops the write operation on that memory cell, irrespective of the external write operaiton specification, when the time set on the timer circuit has elapsed. The nonvolatile memory device has memory cells, each consisting of a single transistor. The erase operation on the memory cells is controlled according to a current flowing through these memory cells.