发明名称 |
Fluorescent lamp ballast with integrated circuit |
摘要 |
A resonant fluorescent lamp ballast includes an IC driver for a half-bridge arrangement that supplies AC current to a lamp. The IC creates a frequency sweep from a pre-heat frequency, through a resonant frequency, to a still lower operating frequency. A pre-heat pin in the IC triggers a re-start or the frequency sweep when a first signal exceeds a first threshold level. A shut-down pin in the IC associated with an internal shut-down latch shuts down the driver when a second signal exceeds a second threshold level. Pre-heat trigger circuitry detects a current spike through half-bridge switches when the lamp has not yet started, supplying the pre-heat pin with a first signal exceeding the first threshold level. End-of-life circuitry provides to the shut-down pin a second signal exceeding the second threshold level if lamp current fails to reach a substantial portion of its normal level within a predetermined time. A DC current-supply path is provided from a DC current supply, through at least one filament of each lamp in the load circuit, to a power-supply pin for the IC. The end-of-life circuitry cooperates with the pre-heat trigger circuitry by limiting the number of the frequency sweeps to no more than occur during the predetermined time set by the end-of-life circuitry. The DC path cooperates with the end-of-life circuitry and the internal shut-down latch to reset the latch when the DC path is broken due to absence of the at least one filament in the path.
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申请公布号 |
US6366032(B1) |
申请公布日期 |
2002.04.02 |
申请号 |
US20000494193 |
申请日期 |
2000.01.28 |
申请人 |
ROBERTSON WORLDWIDE, INC. |
发明人 |
ALLISON JOSEPH M.;MOORE DAVID J. |
分类号 |
H05B41/298;(IPC1-7):G05F1/00 |
主分类号 |
H05B41/298 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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