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:
Jun. 29, 1993
Filed:
Jan. 24, 1992
Isaku Komuro, Kokubunji, JP;
Kabushiki Kaisha Toshiba, Kawasaki, JP;
Abstract
Disclosed is a key telephone system provided with a key service unit (KSU) 1 having a central control unit 6, and a digital key telephone set (DKT) 10 having a local control unit 13 for communications of control data with the central control unit 6. First and second add-on modules (ADMs) 24 and 34 for communications of control data with the central control unit 6 are optionally connectable to the DKT 10. When control data (up-data) are transmitted from the local control unit 13 of the DKT 10 to the KSU 1, a disable signal is given from the DKT 10 to the first ADM 24 to disable up-data from being transmitted from the first ADM 24. At this time, the first ADM 24 also outputs a disable signal to the second ADM 34 to disable up-data from being transmitted from the second ADM 34. At any selected time when no up-data are transmitted from the DKT 10, an enable signal is given from the DKT 10 to the first ADM 24. In response to this enable signal, when up-data to be transmitted from the first ADM 24 are present, the first ADM 24 transmits the up-data and further gives the disable signal to the second ADM 34 to disable up-data from being transmitted from the second ADM 34. On the other hand, in response to the enable signal from the DKT 10, when up-data to be transmitted from the first ADM 24 are absent, the first ADM 24 outputs an enable signal to the second ADM 34 to enable up-data to be transmitted from the second ADM 34.