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:
Dec. 27, 1988
Filed:
Mar. 23, 1987
Tamura Electric Works, Ltd., Tokyo, JP;
Abstract
A system for transmissing data by a pulse signal through a pair of lines connected between a main unit and a key telephone set is disclosed. The main unit includes a transmitter for sending, prior to transmission of pulse train data, a start signal of a pulse train including a pulse of an n-bit (where n is an integer) specific logic value and a pulse of an (n+1)-bit logic value opposite to the specific logic value. The key telephone set includes a change detector for detecting a change in the pulse train of the start signal in a direction of the logic value opposite to the specific logic value, a logic value detector for detecting a logic value of an (n+1)th bit pulse from a detection timing of the change detector, a discriminator for discriminating on the basis of the logic value of the (n+1)th bit pulse whether a line connection for the key telephone set is normal, and a reader for reading data following the start signal according to a logic determined by a discrimination result.