Abstract: A switching circuit for turning on/off a DC voltage outputted from a DC/DC converter and a feedback voltage detection circuit for supplying a feedback voltage to the DC/DC converter are controlled in synchronism with each other. In synchronism with a transition of a PWM signal from high level to low level, the switching circuit is immediately turned off as well as a set voltage is also instantaneously supplied from the feedback voltage detection circuit to the DC/DC converter, and in synchronism with a transition of the PWM signal from low level to high level, the switching circuit is immediately turned on thereby to supply a DC voltage charged in the DC/DC converter to a light source as well as the DC/DC converter is caused to start its boosting operation, and a feedback voltage based on a detected voltage is supplied from the feedback voltage detection circuit to the DC/DC converter.

Abstract: A printed-circuit board module comprises: a flexible printed-circuit (FPC) sheet (25) with its two opposite end portions bent toward the side on which parts (24) are mounted and having connection terminals (29) formed side by side along marginal edges of the bend end portions; a printed-wiring board (22) having an opening (26) for receiving the parts (24) and connecting conductor patterns (27) formed in the neighborhood of the opening (26); and a fixing frame (23). The FPC sheet (25) is fixedly held by the fixing frame (23) and is mounted on the printed-wiring board (22) with the fixing frame (23) held therebetween. The FPC sheet (25) makes direct electrical connections to the printed-wiring board (22), and the amount of extension of the parts (24) into the opening (26) can be adjusted by changing the thickness of the fixing frame (23).