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:
Feb. 02, 1993
Filed:
Mar. 02, 1990
Hitachi, Ltd., Tokyo, JP;
Abstract
In a communication system in which a plurality of communication units are connected to a common two-wire transmission line and signal transmission/reception is made between the communication unit and a field sensor connected to one end of the transmission line, the communication unit transmits a signal to the field sensor under the condition that no signal is present on the transmission line during a period of time not shorter than a predetermined time while the field sensor transmits a signal indicative of in-use of the transmission line at an interval of time shorter than the predetermined time during a period of time until the field sensor sends back a signal in response to the signal from the communication unit, whereby signal collision between the plurality of communication units is prevented with no provision of any specific means.