发明名称 |
Discharge lamp driving circuit having resonant circuit defining two resonance modes |
摘要 |
An improved discharge lamp driving circuit of a charge-pump type capable of suppressing a ripple in an envelop of a lamp current at the time of dimming the lamp or at a low environmental temperature. The circuit includes an inverter having switching elements Q1 and Q2 for converting a voltage across a smoothing capacitor Ce into a high frequency power which is applied through a resonant circuit to the discharge lamp Ld. A capacitor Cin is connected to one end of the resonant circuit to vary a DC voltage of the output of the rectifier in accordance with a varying instantaneous value of the high frequency current or voltage appearing in the resonant circuit. A control circuit is provided to give a control signal for alternately turning on and off the switching elements Q1 and Q2. A feedback circuit FB is provided to modulate the control signal within a permissible range given to the control circuit in such a manner as to adjust the timing of turning on and off the switching elements Q1 and Q2 in a feedback manner based upon a lamp current detected by a current sensor SI, for reducing the ripple in the lamp current. A mixer MX is included to compensate for the lamp current in consideration of a dimmer signal Dim of dimming the lamp in order to suppress the ripple which would otherwise increase due to the dimming of the lamp.
|
申请公布号 |
US5914572(A) |
申请公布日期 |
1999.06.22 |
申请号 |
US19970878821 |
申请日期 |
1997.06.19 |
申请人 |
MATSUSHITA ELECTRIC WORKS, LTD.;VIRGINIA TECH INTELLECTUAL PROPERTIES, INC. |
发明人 |
QIAN, JINRONG;LEE, FRED C.;YAMAUCHI, TOKUSHI |
分类号 |
H05B41/24;H05B41/28;H05B41/285;H05B41/392;(IPC1-7):H05B37/02 |
主分类号 |
H05B41/24 |
代理机构 |
|
代理人 |
|
主权项 |
|
地址 |
|