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:
Apr. 25, 1995
Filed:
Feb. 28, 1991
Ryoji Maruyama, Saitama, JP;
Kabushiki Kaisha Toshiba, Kawasaki, JP;
Abstract
A transmission input/output device for signal transmission through a telephone line, with reduced power consumption, size, and cost. The device includes: a resistor, connected to the telephone line, for setting a signal input and output impedance; and a transmission control circuit for amplifying the transmission signals to be outputted to the telephone line, including: a variable resistor, connected in series with the resistor, for supplying voltages corresponding to the transmission signals to be outputted to the telephone line into the resistor according to changes of an impedance of the variable resistor; and an operational amplifier for controlling the changes of the impedance of the variable resistor by supplying an output according to the transmission signals to be outputted to the variable resistor.