Electronic headset telephone

• US 4,975,949 A
• Filed: 06/15/1989
• Issued: 12/04/1990
• Est. Priority Date: 06/15/1989
• Status: Expired due to Fees

• Current Assignee: Plantronics, Inc. (HP Inc.)
• Original Assignee: Plantronics, Inc. (HP Inc.)
• Inventors: Wimsatt, Jeff M., Sanders, Gary L., Bernardi, Robert J., DeKalb, Frederick P.
• Primary Examiner(s): Ng, Jin F.
• Assistant Examiner(s): Augustus, Jhanay
• Application Number:
  US07/366,763
• Time in Patent Office: 537 Days
• Field of Search: 379/397, 379/387, 379/395, 379/396, 379/413, 381/104, 381/109, 455/159
• US Class Current: 379/387.01
• CPC Class Codes: H04M 1/312 pulses produced by electronic circuits
• CPC Class Codes: H04M 1/50 by generating or selecting currents of predetermined frequencies or combinations of frequencies
• CPC Class Codes: H04M 1/53 Generation of additional signals, e.g. additional pulses
• CPC Class Codes: H04M 1/6025 implemented as integrated speech networks
• CPC Class Codes: H04M 1/6033 for providing handsfree use or a loudspeaker mode in telephone sets arrangements for preventing acoustic echo H04M9/08
• CPC Class Codes: H04M 19/08 with current supply sources at the substations generating ringing current H04M19/04

Abstract

An electronic telephone set for use with a telephone headset receiver/transmitter apparatus is disclosed. The telephone set is line-powered, and is capable of transmit muting, last number re-dial, and memory dialing. The volume of the received voice signal is controllable by a user, and a visual indication of the volume setting is provided. The receiver and transmitter amplifiers includes circuitry for compensating for the frequency response characteristics of two or more headsets, the compensation circuitry being selectively and automatically engaged by means of a programmable connecting jack. The design of the telephone is such that it consumes very little power, especially during "on-hook" operation. Moreover, an electrical storage device is employed to provide continuous operational power to the dialer circuitry and electronic hook-switch control circuitry, so that the telephone set retains its dialing memory when not in use. Bell tap suppression circuitry is included to prevent the ringer from responding to sporadic voltage transients on the transmission lines, allowing the telephone can be installed in parallel with other phones.

Claims

1. An electronic, line-powered telephone set for use with a telephone headset apparatus having a receiver and a microphone, said telephone set compatible with a standard telephone transmission system having at least first and second lines for establishing a loop connection between said telephone set and a central switching station, said telephone set comprising:

ringing means, selectively coupled either to said first and second lines or to said first line and a third line, responsive to the presence of an alternating-current ringing signal thereon for heralding an incoming telephone call;

dialing means for initiating outgoing telephone calls, said dialing means selectably capable of initiating the issuance of dialing pulses and dialing tones on said first and second lines, said dialing means further having memory means for storing dialing sequences and having the capability to issue said stored dialing sequences to said first and second lines under direction of a user;

rectifying means coupled to said first and second lines for receiving therefrom direct-current supplied from batteries in the central station, and producing a rectified, direct-current signal for powering electronic components of the telephone;

surge protector means coupled to said first and second lines for preventing internal components of the telephone from being exposed to voltages exceeding a predetermined threshold;

an electronic hook-switch circuit receiving the rectified, direct-current power signal from said rectifying means, the hook-switch circuit for selectively establishing the loop connection with the central station, such that when a loop connection is established, variations in the amount of current conducted in said loop are used to communicate voice information between the telephone set and the central station, said variations in current being superimposed upon the direct-current signal received from said rectifying means, the hook-switch circuit also providing a switched, direct-current output signal which has a non-zero level only when a loop connection is established

low-current regulator means receiving the rectified DC power signal for providing a low-current output power signal to components of the telephone set during periods when a loop connection is not established;

high-current regulator means receiving the low-current output power signal from the low current regulator and the switched direct-current signal from the hook-switch circuit, for providing a higher-current output power signal to components of the telephone set during periods when a loop connection is established;

bell-tap suppression circuit including an opticoupler, coupled to said first, second, and third lines, for preventing said ringing means from responding to voltage transients on said first, second, and third lines which may be generated during pulse dialing;

an electronic controlling circuit receiving power signals from said low-current regulator and said high current regulator, said controlling circuit having a plurality of input terminals and a plurality of output terminals,

electrical storage means receiving said low-current output power signal and said high-current output power signal, for storing electrical energy provided therefrom, said stored electrical energy being used by the dialing means, the hook switch circuit, and the controlling circuit during periods when a loop connection is not established;

voice signal processing means, including a receiver amplifier and a transmitter amplifier, coupled to said first and second lines, for establishing full-duplex voice communication between the telephone and the central station via a loop connection;

switching means coupled to said headset apparatus and to the voice signal processing means for identifying the type of said headset, and for adjusting the operation of the voice signal processing means according to the type of the headset;

indicator means for indicating the gain level of the receiver amplifier, for indicating when a loop connection is established, and for indicating the gain level of the transmitter amplifier;

a first subset of said controlling circuit input terminals coupled to the output terminals of a plurality of user-operated switches, for receiving a plurality of user control signals therefrom;

a second subset of said controlling circuit input terminals coupled to said dialing means, for receiving a plurality of dialing control signals therefrom;

a first subset of said controlling circuit output terminals coupled to said voice signal processing means, for issuing a plurality of volume control signals thereto, the gain of said receiver amplifier being adjusted in response to said volume control signals, and said volume control signals being issued in response to said user control signals;

a second subset of said controlling circuit output terminals coupled to the electronic hook-switch circuit, for issuing hook-switch control signals thereto, said electronic hook-switch circuit selectively establishing a loop connection with said first and second lines in response to said hook-switch control signals, said hook-switch control signals being issued in response to said dialing control signals and said user control signals;

a third subset of said controlling circuit output terminals coupled to the indicator means, for issuing indicator control signals thereto, the indicator means responsive to said indicator control signals to indicate the status of the hook-switch circuit, the gain of the receiver amplifier, and the gain of the transmitter amplifier.

2. An electronic telephone according to claim 1, wherein the switching means determines the frequency response characteristics of the receiver amplifier and the transmitter amplifier, said receiver amplifier and said transmitter amplifier each having at least two different, selectable frequency responses.

3. An electronic, line-powered telephone set according to claim 1, wherein a further one of said electronic controlling circuit output terminals is coupled to a control input of said electronic hook-switch circuit, and wherein said electronic hook-switch circuit comprises first and second transistors of opposite conductivity types, configured such that a low-level logic signal provided at said hook-switch control input from said electronic controlling circuit prevents said first and second transistors from conducting, thus preventing completion of a local-loop connection with the central station, while a high-level logic signal on said control input causes said first and second transistors to be conductive, thus completing the local loop;

and wherein a user-actuated switch produces a switched output signal, said switched output signal being received at one of said plurality of electronic controller responds to actuation of the user switch by logically inverting the output signal received at the control input of said electronic hook-switch.

4. An electronic, line-powered telephone set according to claim 1, wherein said low-current output power signal from said low-current regulator means charges said electrical storage means at a low rate during periods when no loop connection is established and said high-current power signal from said high-current regulator means charges the electrical storage means at a high rate during periods when a loop connection is established, such that said memory means in the dialer is provided with an uninterrupted power signal from the electrical storage means.

5. An electronic telephone set compatible with standard local-loop-type telephone transmission systems having at lease first and second wires extending to a central switching station, said telephone set comprising:

an electronic controller having a plurality of input terminals and a plurality of output terminals;

user-actuated means providing a plurality of output signals, for controlling the volume level of sound produced by the receiver of said telephone, and for controlling the level of the voice signal transmitted from the telephone, said output signals received at the input terminals of the electronic controller;

a plurality of indicators for providing a visual indication of said receiver volume level, of said transmitted voice signal level, and of the status of the loop connection between the telephone and the central station, said indicators receiving signals from the plurality of controller output terminals;

wherein the controller is responsive to the output signals from the user-actuated means to selectively activate individual ones of the plurality of indicators, such that;

at least one indicator is activated whenever a loop connection is established;

each indicator corresponds to a distinct receiver volume range; and

two alternately blinking indicators corresponds to a reduction in the level of the transmitted voice signal.