SOLID-STATE PHOTOCONTROL APPARATUS FOR LIGHTING LOADS

• US 3,654,514 A
• Filed: 10/12/1970
• Issued: 04/04/1972
• Est. Priority Date: 10/12/1970
• Status: Expired due to Term

• Current Assignee: Cooper Industries, Inc. (Eaton Corporation PLC.)
• Original Assignee: George A. Kappenhagen
• Inventors: Kappenhagen, George A.
• Primary Examiner(s): Kaufman, Nathan
• Application Number:
  US05/080,081
• Time in Patent Office: 540 Days
• Field of Search: 315/156,159
• US Class Current: 315/156
• CPC Class Codes: H05B 41/3922 and measurement of the incident light

Abstract

A simple solid-state photocontrol apparatus for controlling the operation of lighting loads comprises a series-connected rectifier and RC combination which generates a DC potential. A series-connected photocontrol element and a fixed resistor connect to the generated DC potential and under nighttime conditions, an increased potential is developed across the photocontrol element. The gate circuit of an AC symmetrical switch is connected intermediate the fixed resistor and the photocontrol element, and when the voltage applied to the gate circuit reaches a predetermined value as nighttime approaches, the AC symmetrical switch conducts to operate the lighting load. The symmetrical switch remains conducting until the resistance of the photocontrol element again decreases due to daytime conditions.

Claims

1. A photocontrol apparatus for controlling the application of alternating current energizing potential to a lighting device in response to a predetermined level of ambient lighting, said apparatus comprising:

a. input terminals adapted to be connected across said source of AC energizing potential, and output terminals adapted to have a lighting load device connected thereacross;

b. a gate-controlled solid state AC symmetrical switch connected between one of said input terminals and one of said output terminals, said switch adapted to be gated to an electrical conducting condition by the application thereto of a predetermined unidirectional electric signal;

c. a rectifier and RC combination comprising a solid-state rectifier connecting in series with a parallel-connected capacitor and fixed resistor which have a predetermined time constant of magnitude substantially greater than the period of one Cycle of said source of AC energizing potential, and said rectifier and said capacitor electrically connected in circuit across said input terminals;

d. the fixed resistor of said RC combination having one end thereof connected to the junction between said rectifier and said capacitor, and a light-responsive variable resistance means connected between the other end of said fixed resistor and in circuit with said one input terminal, said variable resistance means displaying a low value of resistance during daylight hours and a high value of resistance during the nighttime hours; and

e. voltage-responsive gate-current controlling means connecting between the junction of said fixed resistor and said variable resistance means and the gate of said symmetrical switch, said voltage-responsive gate-current controlling means operable to pass current therethrough to gate said symmetrical switch only when at least a minimum predetermined potential is applied thereacross;

whereby during hours of daylight the potential developed across said variable resistance means is insufficient to cause said symmetrical AC switch to be gated, and during hours of darkness the increased potential developed across said variable resistance means is sufficient to cause said symmetrical AC switch to be gated and thus to apply a lighting load operating potential across said output terminals.

2. The apparatus as specified in claim 1, wherein a current-limiting resistor connects between said capacitor and said one input terminal.

3. The apparatus as specified in claim 1, wherein said voltage-responsive gate-current controlling means comprises a unidirectional trigger diode which avalanches upon application thereacross of said minimum predetermined potential.

4. The apparatus as specified in claim 1, wherein said voltage-responsive gate-controlling means comprises a Zener diode.

5. The apparatus as specified in claim 1, wherein said voltage-responsive gate-controlling means comprises series connected diodes which will conduct only on the application thereacross of said minimum predetermined potential.

6. The apparatus as specified in claim 1, wherein lighting arrester means is directly electrically across said input terminals.

7. The apparatus as specified in claim 1, wherein said load comprises a discharge lamp and associated inductive ballast.

8. The apparatus as specified in claim 7, wherein a high resistance of predetermined value connects across said output terminals.

9. The apparatus as specified in claim 1, wherein the electrical components comprising said apparatus are mounted on one surface of a printed circuit board, and said input terminals and said output terminals are connected to a twist-lock connector which is mounted on the other surface of said printed circuit board.

10. The apparatus as specified in claim 9, wherein said electrical components comprising said apparatus are encased by a protective coating applied directly thereon.