PWM controller with automatic low battery power reduction circuit and lighting device incorporating the controller
US6870329B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jan 16, 2003 |
| Grant date | Mar 22, 2005 |
| Priority date | — |
| Expiry date | Jan 16, 2023 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02B20/00
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A controller for controlling a voltage applied to a load from a power source includes a square wave producing circuit for connection in the circuit with the battery and the lamp. The square wave producing circuit produces a variable duty cycle square wave for controlling application of power to the load in accordance with the duty cycle of the square wave. The square wave producing circuit has a control input for varying the duty cycle of the square wave in response to a voltage at the control input. A voltage varying circuit is connected to the power source for producing a selectively variable voltage that is fed to the control input of the square wave producing circuit for selectively adjusting the duty cycle of the square wave. A low voltage detection circuit is connected to the power source and coupled to the control input of the square wave producing circuit for automatically producing a voltage that decreases the duty cycle of the square wave when the battery voltage decreases to or below a predetermined level.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.