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:
Jan. 13, 1987
Filed:
Jul. 05, 1984
Horst Brandstatter, Zirndorf, DE;
Abstract
A telephone installation has two talk-listen stations each comprising a telephone case adapted to receive talking and listening means housed in a common receiver case. At least one switch is provided on the telephone case or on the receiver case and is operable as a result of the raising and setting down of the receiver case on the telephone case. Each talk-listen station has a buzzer or like means and the listening means comprises an electroacoustic piezoelectric device with metallic electrodes arranged on either side of a piezoelectric material plate, one electrode being subdivided into two partial electrodes which are not interconnected in direct current-like manner. An oscillator arrangement is provided between the partial electrodes and the other electrode which produces a dial tone in one switching position of a switch and in the other switching position one of the partial electrodes and the said other electrode form the actual listening means, the other partial electrode being disconnected.