Intraplant communication system

• US 4,206,318 A
• Filed: 06/19/1978
• Issued: 06/03/1980
• Est. Priority Date: 06/19/1978
• Status: Expired due to Term

• Current Assignee: GAI-Tronics Corp. (Hubbell, Inc.)
• Original Assignee: GAI-Tronics Corp. (Hubbell, Inc.)
• Inventors: Steely, Lee W.
• Primary Examiner(s): Morrison, Malcolm A.
• Assistant Examiner(s): Kemeny, E. S.
• Application Number:
  US05/916,910
• Time in Patent Office: 715 Days
• Field of Search: 179/159, 179/167, 179/1 SW, 179/1 A, 179/1 HS, 179/103, 325/16
• US Class Current: 379/185
• CPC Class Codes: H04M 1/06 Hooks; Cradles
• CPC Class Codes: H04M 1/6033 for providing handsfree use or a loudspeaker mode in telephone sets arrangements for preventing acoustic echo H04M9/08

Abstract

This invention is an improvement of the intraplant communication system in U.S. Pat. No. 3,527,890. It comprises one base unit composed of a handset amplifier and speaker amplifier, each with its own integral power supply and each located on a common printed circuit board. This unit also features a disconnect device, formerly called a hook switch, which includes a radio frequency proximity detector which has no moving parts.

Claims

1. A telephone communication system including a station connected thereto comprising two relatively movable elements, namely a handset and a hang-up support for said handset, said handset having an audio receiver in one end and a microphone in the other, said handset and hang-up support containing means devoid of movable switching contacts for proximity detection of movement of said handset relative to said hang-up support, said means comprising a proximity radio frequency transmitter contained in the handset, and a proximity receiving antenna contained in the hang up support, and disconnect relay means activated by a proximity detector responsive to said proximity radio frequency transmitter upon movement of said handset to close proximity to said hang-up support, even without hanging said handset thereon, so as to effect electrical disconnection of said handset from said system and so that movement of said handset away from said hang-up support will effect electrical connection of said handset to said system.

2. A telephone communication system as recited in claim 1 wherein said transmitter is tuned to a frequency of approximately 39 Khz.

3. A telephone communication system as recited in claim 1 wherein said proximity radio frequency transmitter is mounted closely adjacent to said audio receiver and includes a metal housing which acts as a radiating antenna, and wherein said hang-up support is devoid of movable parts and acts as a receiving antenna for signals emitted from said radiating antenna.

4. A telephone communication system as recited in claim 2 wherein said hang-up support is in the form of a hang-up hook, said hang-up hook being rigidly and insulatingly supported on a front panel of a housing.

5. A telephone communication system as recited in claim 4, said housing including a handset amplifier and a speaker amplifier, both energized by a common power source, a party line and a page line, movement of said handset to close proximity to said hang-up hook effecting disconnection of said handset amplifier from said party and page line.

6. A telephone communication system as recited in claim 5 wherein said proximity detector includes a phase-locked loop detector for detecting signals generated by said radiating antenna when said handset is moved to close proximity to said hang-up hook.

7. A telephone communication system as recited in claim 6 wherein said proximity detector includes an input buffer amplifier used as a voltage follower for for matching said hang-up hook antenna to a low impedance circuit.