Light-emitting diode module for retrofit to flashlights using incandescent bulbs

• US 20030076051A1
• Filed: 09/06/2002
• Published: 04/24/2003
• Est. Priority Date: 09/07/2001
• Status: Active Grant

• Current Assignee: Opalec
• Original Assignee: Opalec
• Inventors: Post, Stephen F., Bowman, Scott A.
• Granted Patent: US 6,791,283 B2
• Time in Patent Office: Days
• US Class Current: 315/200A
• CPC Class Codes: H05B 45/3574 Emulating the electrical or functional characteristics of incandescent lamps
• CPC Class Codes: H05B 45/38 using boost topology
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

An LED illumination module for a flashlight has a housing, electronic control circuitry, and one or more LEDs connected in series and to the circuitry. The module is characterized in that the module is shaped to modularly replace an incandescent-bulb in an existing flashlight. In one aspect the control circuitry operates in a dual mode to extend life of the unit, and to warn when battery replacement is warranted.

Claims

1. An LED illumination module for a flashlight, comprising:

a housing;

electronic control circuitry; and

one or more LEDs connected in series and to the circuitry;

characterized in that the module is shaped to modularly replace an incandescent-bulb in an existing flashlight.

2. The LED module of claim 1 wherein the circuitry provides two distinct operating modes, a first mode stabilizing current through the LEDs as battery voltage wanes, and a second mode activated at a selected voltage to stabilize battery voltage and to trigger a low-battery alert.

3. The LED module of claim 2 wherein the alert mechanism is a colored LED.

4. The LED module of claim 1 wherein the alert mechanism is an audio element.

5. The LED module of claim 1 wherein the alert mechanism is obtained by intensity modulation of one or more of the LEDs.

6. The LED module of claim 1 wherein the electronic control circuitry comprises reverse polarity protection circuitry to avoid damage to components due to reversed battery polarity.

7. The LED module of claim 7 wherein the reverse polarity protection circuitry comprises a MOSFET configured to block the flow of current of reverse polarity, and to conduct current of correct polarity, said MOSFET being turned on by a voltage higher than that of the battery and provided by a DC/DC voltage boost converter.

8. In a LED illumination module having one or more LEDs, a control system for regulating power conversion and illumination intensity of the LED module comprising:

a voltage boost DC/DC converter, operating from a battery and powering said LEDs;

a first feedback mechanism for regulating LED current by controlling said voltage boost DC/DC converter;

a second feedback mechanism for regulating battery voltage by controlling said voltage boost DC/DC converter; and

a mechanism for automatically transitioning between the first and the second feedback mechanisms in response to a predetermined battery voltage threshold.

9. The control system of claim 8 wherein the module can be retrofitted to an existing hand-held light.

10. The control system of claim 8 further comprising reverse polarity protection circuitry to avoid damage to components due to reversed battery polarity.

11. The LED module of claim 8 wherein the reverse polarity protection circuitry comprises a MOSFET configured to block the flow of current of reverse polarity, and to conduct current of correct polarity, said MOSFET being turned on by a voltage higher than that of the battery and provided by a DC/DC voltage boost converter.

12. The control system of claim 8 further comprising a low battery indicator enabled to alert the user when transition between the first and the second feedback control modes occurs, or is about to occur.

13. The control system of claim 12 wherein alerting the user is accomplished via an LED indicator.

14. The control system of claim 12 wherein alerting the user is accomplished via an audio sound producing device.

15. The control system of claim 12 wherein alerting the user is accomplished via intensity modulation of one or more of the LEDs.

16. A method for controlling a LED module having one or more LEDs, comprising steps of:

(a) providing power to the one or more LEDs through a DC/DC converter from a battery pack providing an input voltage;

(b) feeding back a signal representative of LED current to the converter to maintain a substantially constant LED current as the batteries discharge and the input voltage decreases; and

(c) beginning at a preset value for input voltage, switching to a mode of battery voltage control feedback to the converter to reduce current to the LEDs in a manner to maintain the battery voltage at a substantially constant value.

17. The method of claim 16 further comprising a step (d) for initiating a low-battery alert mechanism at or near the pre-set input voltage.

18. The method of claim 16 wherein the alert mechanism comprises lighting a color LED.

19. The method of claim 16 wherein the alert mechanism comprises an audio signal.

20. The method of claim 16 wherein the alert mechanism comprises intensity modulation of the one or more LEDs.

21. A method for retrofitting a flashlight having a body cylinder and an incandescent bulb mounted with a reflector in an insulator receptacle translatable by rotating a head assembly relative to the body cylinder, said translation opening or closing a contact to the body cylinder as an on-off mechanism, the method comprising steps of:

(a) removing the head assembly;

(b) replacing the reflector with an adapter ring;

(c) removing the incandescent bulb;

(d) removing the translatable insulator receptacle, and replacing it with a LED module of substantially the same geometry, but comprising one or more white-light LEDs; and

(e) replacing the head assembly.

22. The method of claim 21 wherein, in step (d) the LED module further comprises electronic control circuitry for converting and managing the transfer of battery power to the one or more LEDs.

23. The method of claim 22 wherein the control circuitry operates in a dual mode, a first mode controlling LED current to be substantially constant while battery voltage deteriorates, and a second mode allowing LED current to decrease while maintaining battery voltage substantially constant, the second mode triggered at a preset voltage value.