OPTICAL ELEMENT DRIVING CIRCUIT

• US 20100013404A1
• Filed: 10/22/2008
• Published: 01/21/2010
• Est. Priority Date: 07/21/2008
• Status: Active Grant

• Current Assignee: Tyco Fire & Security GmbH (Johnson Controls International plc)
• Original Assignee: Simplexgrinnell LP (Johnson Controls International plc)
• Inventors: Redjebian, Berj
• Granted Patent: US 7,994,729 B2
• Time in Patent Office: Days
• US Class Current: 315/291
• CPC Class Codes: H05B 41/32 for single flash operation

Abstract

An optical element driving circuit flexibly configures energy sources to cause illumination with an optical output element, such as a flash lamp. The energy sources include an illumination capacitor and a capacitive voltage divider circuit coupled with the optical output element. The illumination capacitor may be charged to a first voltage and a boost capacitor of the capacitive voltage divider circuit may be charged to a second voltage that is a fraction of the first voltage. The optical element driving circuit also includes a triggering circuit coupled with the capacitive voltage divider circuit. The triggering circuit is configured to place a sum of the first voltage and the second voltage across the optical output element.

Claims

1. An optical element driving circuit comprising:

an illumination capacitor charged to a first voltage and coupled with an optical output element;

a capacitive voltage divider circuit coupled with the optical output element and comprising a boost capacitor charged to a second voltage that is a fraction of the first voltage; and

a triggering circuit coupled with the capacitive voltage divider circuit and configured to place a sum of the first voltage and the second voltage across the optical output element.

2. The optical element driving circuit of claim 1, where the triggering circuit is configured to place the boost capacitor in series with the illumination capacitor to drive the optical output element.

3. The optical element driving circuit of claim 1, where the capacitive voltage divider circuit comprises the boost capacitor and a second capacitor, where the second capacitor is configured to be charged to a third voltage that is a fraction of the first voltage.

4. The optical element driving circuit of claim 3, where the triggering circuit is configured to prevent the third voltage from being applied across the optical output element.

5. The optical element driving circuit of claim 3, further comprising a discharge path configured to allow the second capacitor to discharge energy into the illumination capacitor.

6. The optical element driving circuit of claim 5, where the discharge path comprises a diode between the second capacitor and the illumination capacitor.

7. The optical element driving circuit of claim 3, where the capacitance of the boost capacitor is substantially equal to the capacitance of the second capacitor.

8. The optical element driving circuit of claim 3, where the capacitance of the boost capacitor is different than the capacitance of the second capacitor.

9. The optical element driving circuit of claim 3, where the capacitive voltage divider circuit comprises the boost capacitor, the second capacitor, and a third capacitor, where the third capacitor is configured to be charged to a fourth voltage that is a fraction of the first voltage.

10. The optical element driving circuit of claim 1, where the illumination capacitor is configured to provide a positive voltage level at a first terminal of the optical output element, where the triggering circuit is configured to use the boost capacitor to provide a negative voltage level at a second terminal of the optical output element.

11. The optical element driving circuit of claim 1, where the triggering circuit comprises an illumination triggering circuit, the optical element driving circuit further comprising:

a trigger input coupled with the illumination triggering circuit and an ionization triggering circuit;

a first resistor between the trigger input and the illumination triggering circuit; and

a second resistor between the trigger input and the ionization triggering circuit, where the resistance of the first resistor is lower than the resistance of the second resistor.

12. The optical element driving circuit of claim 1, where the triggering circuit comprises a thyristor, where a first terminal of the thyristor is coupled with a ground potential, where a second terminal of the thyristor is coupled between the boost capacitor and a second capacitor of the capacitive voltage divider circuit.

13. The optical element driving circuit of claim 1, where the optical output element comprises a xenon flash lamp.

14. An optical element driving circuit comprising:

an illumination capacitor charged to a first voltage and coupled with an optical output element;

a capacitive voltage divider circuit coupled with the optical output element and comprising multiple capacitors each charged to a fraction of the first voltage; and

a controller coupled with the capacitive voltage divider circuit and configured to select zero or more capacitors from the capacitive voltage divider circuit for use to drive the optical output element.

15. The optical element driving circuit of claim 14, where the controller is configured to place a sum of the first voltage and voltages of the selected zero or more capacitors across the optical output element.

16. The optical element driving circuit of claim 14, where the controller is configured to place one or more capacitors from the capacitive voltage divider circuit in series with the illumination capacitor to drive the optical output element;

and

where the controller is configured to prevent one or more capacitors from the capacitive voltage divider circuit from being in series with the illumination capacitor.

17. The optical element driving circuit of claim 14, where the capacitive voltage divider circuit comprises:

a first capacitor charged to a second voltage that is fraction of the first voltage;

a second capacitor charged to a third voltage that is fraction of the first voltage;

a first node between the first capacitor and the optical output element;

a second node between the first capacitor and the second capacitor; and

a third node at another terminal of the second capacitor;

where the controller is configured to select zero or more capacitors from the capacitive voltage divider circuit for use to drive the optical output element by coupling a ground potential with either the first node, the second node, or the third node.

18. The optical element driving circuit of claim 17, where the controller prevents the second and third voltages from being applied across the optical output element when the controller couples the ground potential with the first node;

where the controller prevents the third voltage from being applied across the optical output element when the controller couples the ground potential with the second node; and

where the controller applies both the second and third voltages across the optical output element when the controller couples the ground potential with the third node.

19. The optical element driving circuit of claim 17, where the controller is configured to move the ground potential from one of the first, second, or third nodes to another of the first, second, or third nodes when a different voltage level is desired across the optical output element.

20. A flash lamp driving circuit comprising:

an illumination capacitor charged to a first voltage and coupled with a flash lamp of a visual emergency warning device;

a capacitive voltage divider circuit coupled with the flash lamp and comprising a first capacitor and second capacitor, where the first capacitor is configured to be charged to a second voltage that is a fraction of the first voltage, where the second capacitor is configured to be charged to a third voltage that is a fraction of the first voltage;

a triggering circuit coupled with the capacitive voltage divider circuit and configured to place a sum of the first voltage and the second voltage across the flash lamp, where the triggering circuit is configured to prevent the third voltage from being placed across the flash lamp.