Title:
LIGHTING CIRCUIT OF DISCHARGE LAMP
Document Type and Number:
Japanese Patent JP3197167
Kind Code:
B2
Abstract:
PURPOSE: To improve control precision by providing a control line related to the power control of a discharge lamp by the polygonal line approximation to a constant power curve.
CONSTITUTION: A lighting circuit 1 converts the output voltage of a DC booster circuit 5 into AC voltage, and then supplies it to a discharge lamp 8. A current detecting part 11 and a voltage detecting part 12 for detecting the corresponding signals to the current and voltage of the discharge lamp, respectively, and a control circuit 10 for controlling the output voltage of the DC booster circuit 5 according to the detection signals are provided to perform a lighting control according to a control line for regulating the voltage-current characteristic of the discharge lamp. A constant power control part 15 receives the detection signals from the current detecting part 11 and the voltage detecting part 12, and transmits a control signal to the DC booster circuit 5 through a PW (pulse width modulation) control part 15 so that the lighting control is performed with a substantially constant power according to the control line obtained by the polygonal line approximation to a constant power curve, to control the output voltage of the DC booster circuit 5.
Inventors:
Masayasu Yamashita
Atsuyuki Toda
Atsuyuki Toda
Application Number:
JP23607094A
Publication Date:
August 13, 2001
Filing Date:
September 06, 1994
Export Citation:
Assignee:
Koito Manufacturing Co., Ltd.
International Classes:
H05B41/282; H02M7/48; (IPC1-7): H05B41/282; H02M7/48
Domestic Patent References:
| JP4141988A | ||||
| JP7263158A | ||||
| JP745390A | ||||
| JP2503372A |
Attorney, Agent or Firm:
Yuji Komatsu