Power source control circuitry for an automotive portable telephone

• US 5,212,836 A
• Filed: 01/30/1991
• Issued: 05/18/1993
• Est. Priority Date: 01/30/1990
• Status: Expired due to Fees

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Matsushita, Akimasa
• Primary Examiner(s): Eisenzopf, Reinhard J.
• Assistant Examiner(s): SOBUTKA, PHILIP
• Application Number:
  US07/647,791
• Time in Patent Office: 839 Days
• Field of Search: 455/89, 455/90, 455/99, 455/127, 455/345, 455/346, 455/351, 455/343, 379/58, 379/61, 379/63, 320/2, 307/86, 307/10.6
• US Class Current: 455/572
• CPC Class Codes: H04W 52/0274 by switching on or off the equipment or parts thereof
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

Power source control circuitry for an automotive portable radio telephone which is powered by a power source mounted on a motor vehicle via an adapter. When the telephone is mounted on the adapter, power is fed from the on-board power source to the adapter and telephone. When the telephone is removed from the adapter, the adapter is disconnected from the battery to eliminate wasteful supply of power from the power source to the adapter.

Claims

1. Power source control circuitry for an automotive portable radio telephone which is powered by a power source mounted on a motor vehicle, comprising:

switching means for providing a switching connection between said power source of said motor vehicle and an adapter and said telephone;

ignition sensing means for sensing an output signal of an ignition system incorporated in said motor vehicle;

power ON/OFF sensing means connected to a power switch of said telephone for inverting, every time said power switch produces an ON/OFF pulse, an output state of said power ON/OFF sensing means and holding said inverted output state; and

control means for controlling said switching means in response to an output of said ignition sensing means and an output of said power ON/OFF sensing means, such that when said telephone is removed from said adapter, said switching means interrupts the connection of said power source and said adapter.

2. Circuitry as claimed in claim 1, wherein said switching means comprises a relay switch and relay switch control means.

3. Circuitry as claimed in claim 2, wherein said relay switch comprises a relay contact connected between said power source and said adapter and said telephone, and a relay coil connected to said power source and ground of said telephone for opening and closing said relay contact, said relay switch control means comprising a switching transistor connected between said relay coil and ground of said telephone for selectively interrupting connection of said power source and ground of said telephone.

4. Circuitry as claimed in claim 3, further comprising:

a first terminal for feeding power to said telephone;

a second terminal for connecting said power ON/OFF sensing circuit and said power switch of said telephone; and

a third terminal for connecting said switching transistor and ground of said telephone.

5. Circuitry as claimed in claim 1, further comprising an anti-overvoltage means for short-circuiting a power feed line extending from said power source when a voltage higher than a predetermined voltage is applied to said power feed line.