SERIES LAMP SAFEGUARD CIRCUIT

• US 3,639,805 A
• Filed: 05/25/1970
• Issued: 02/01/1972
• Est. Priority Date: 05/25/1970
• Status: Expired due to Term

• Current Assignee: Charles B. Murphy, Nils L. Muench
• Original Assignee: Charles B. Murphy, Nils L. Muench
• Inventors: Muench, Nils L., Murphy, Charles B.
• Primary Examiner(s): Hossfeld, Raymond F.
• Application Number:
  US05/040,184
• Time in Patent Office: 617 Days
• Field of Search: 315/74,75,82,83,122,123,185R,185S,191,192,193,66,73,121
• US Class Current: 315/122
• CPC Class Codes: B60Q 11/00 Arrangement of monitoring devices for devices provided for in groups B60Q1/00 - B60Q9/00
• CPC Class Codes: H05B 39/105 with a spare lamp in the circuit, and a possibility of shunting a failed lamp lamp changing devices H01R33/00, H01R43/00; incandescent lamps with a reserve body H01K

Abstract

A vehicle-headlamp-energizing circuit for headlamps connected in series. Each headlamp has a breakdown diode connected in parallel, and each breakdown diode has a breakdown voltage slightly larger than the normal potential drop across its parallel connected lamp so as to conduct current around the lamp when it fails and maintain conduction through the remaining lamps.

Claims

1. An electric lamp circuit comprising, in combination, a source of current at substantially constant potential, a plural number of electric lamps connected in series across the source, and a plural number of zener breakdown diodes, one of which is connected in parallel with each lamp, each breakdown diode having a breakdown voltage slightly greater than the voltage drop in normal operation of its parallel lamp, so that each breakdown diode is substantially nonconducting but will conduct upon failure of its parallel lamp and maintain the energizing circuit to the remaining lamp or lamps.

2. A vehicle headlamp energizing circuit comprising a plurality of headlamps connected in series with a battery, each lamp having a normal potential drop across it while operating, each lamp having a zener breakdown diode connected in parallel with it, the breakdown diode having a breakdown voltage slightly greater than the normal potential drop of its parallel headlamp so as to conduct current around the headlamp only when the headlamp fails.

3. A circuit as defined in claim 2 in which only two headlamps are connected in series with the battery in the said circuit.

4. A circuit as defined in claim 3 in which the battery is a power source of substantially X volts and the breakdown diodes have a breakdown voltage slightly greater than one-half X volts whereby failure of a headlamp causes the diode in parallel therewith to conduct so as to effect a voltage drop of slightly less than one-half X volts across the headlamp which remains energized.