Phase-Controlled Dimmable Ballast
- Summary
- Fluorescent lamp is a common form of illumination in offices, public areas and even households. However, it is much harder to provide dimmable control for fluorescent lamps when compared with incandescent ones. A new method is now invented in achieving control over dimming function for fluorescent lamps.
The problem with dimmable fluorescent lamps is that the mechanism of fluorescent lamps does not allow dimming to be achieved with just varying the applied voltage. It will otherwise just go out when the applied voltage is below the minimum. In the new invention, the ballast of the lamp consists of a power factor corrector, an inverter stage and a controller. Together, they allow dimming control by: maintaining a stable prescribed DC voltage; converting this DC voltage into an AC voltage suitable to drive the lamp; issuing the correct switching frequency or pulse width at a prescribed frequency to adjust the power delivered; and regulating the output of the power factor corrector at a fixed DC voltage if an active PFC is employed. The ballast is connected to its wall unit with only a pair of electrical wires. The wall unit may have a selector between dimming fluorescent lamp or incandescent lamp, and it controls the level of light.
A control wire from the wall unit to the ballast is no longer needed in this new design, making it more cost-effective. This new design is applicable to both fluorescent lamps and compact fluorescent lamps.
- Technology Benefits
- 1. Elimination of a control wire from the wall unit to the ballast (as in other designs)
2. Stable control of light
3. Cost-effective
4. Energy-saving
5. Environmental-friendly
- Technology Application
- - Dimmable ballast for use in:
(a) Small areas like households
(b) Larger areas like auditorium, factory
- Supplementary Information
- Patent Number: US6172466B1
Application Number: US1999249106A
Inventor: Ki, Wing Hung | Mok, Kwok Tai Philip | Sin, Kin On Johnny
Priority Date: 12 Feb 1999
Priority Number: US6172466B1
Application Date: 12 Feb 1999
Publication Date: 9 Jan 2001
IPC Current: H05B0041392
US Class: 315224 | 315307 | 315DIG4
Assignee Applicant: The Hong Kong University of Science & Technology
Title: Phase-controlled dimmable ballast
Usefulness: Phase-controlled dimmable ballast
Summary: For fluorescent lamp.
Novelty: Phase-controlled dimmer ballast for fluorescent lamp has controller which varies switching frequency of ballast based on amount of phase removed from input power supply
- Industry
- Optics
- Sub Category
- Lighting
- Application Date
- 12 Feb 1999
- Application No.
- US 09/249106
- Patent Information
- US 6172466
- ID No.
- TTC.PA.088
- Country/Region
- Hong Kong
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