Abstract A discharge lamp lighting apparatus of this invention includes an inverter circuit (20) and a control circuit (30) connected to a power source rectifier (14) for supplying a D.C. voltage. The inverter circuit (20) includes a parallel voltage resonance circuit of an output transformer (T1) and a resonance capacitor (C2) and the output side of the output transformer (T1) is connected to a discharge lamp (16) and a timer circuit (50). The inverter circuit (20) further includes a switching transistor (Q1) for switching the D.C. power source and a voltage detection circuit (40) for detecting a voltage V CE between the collector and emitter of the switching transistor (Q1). In the start-up operation of the discharge lamp (16), the control circuit (30) raises the control level of V CE of the switching transistor (Q1) so as to set the output voltage of the inverter circuit (20) high until it receives a signal which is output after a preset time determined by the timer circuit (50) has elapsed, and under this condition, the discharge lamp (16) is started.
A discharge lamp lighting apparatus comprising means for supplying a D.C. voltage; switching means for switching a voltage from said D.C. voltage supplying means; parallel voltage resonance circuit means including an inductor and a resonance capacitor and connected at a connection point in series with said switching means across said D.C. voltage supplying means; voltage detection means connected to said connection point, for detecting a voltage of said switching means at said connection point; and control means for controlling the voltage of said switching means detected by said voltage detection means to a constant level when said discharge lamp is started; characterized in that said control means (30) effects the control operation to raise the voltage of said switching means (Q1), detected by said voltage detection means (40), to a relatively high constant preset level for a predetermined period of time from the time at which said D.C. voltage supplying means (12, 14) is turned on until said discharge lamp (16) is lit and set the voltage of said switching means (Q1) detected by said voltage detection means (40) to a relatively low constant level after said discharge lamp (16) is lit.
Claim 2
Dependent Claim
192 words
A discharge lamp lighting apparatus comprising means for supplying a D.C. voltage; switching means for switching a voltage from said D.C. voltage supplying means; parallel voltage resonance circuit means including an inductor and a resonance capacitor and connected at a connection point in series with said switching means across said D.C. voltage supplying means; voltage detection means connected to said connection point, for detecting a voltage of said switching means at said connection point; and control means for controlling the voltage of said switching means detected by said voltage detection means to a constant level when said discharge lamp is started; characterized in that said control means (30) effects the control operation to raise the voltage of said switching means (Q1), detected by said voltage detection means (40), to a relatively high constant preset level for a predetermined period of time from the time at which said D.C. voltage supplying means (12, 14) is turned on until said discharge lamp (16) is lit and set the voltage of said switching means (Q1) detected by said voltage detection means (40) to a relatively low constant level after said discharge lamp (16) is lit.
Claim 3
Dependent Claim
51 words
An apparatus according to claim 1, characterized in that said control means (30), independently from the lighting condition of the discharge lamp (16), raises the voltage of said switching means (Q1), detected by said voltage detection means (40), to a relatively high preset constant level, for a predetermined period of time.
Claim 4
Dependent Claim
120 words
An apparatus according to claim 1, characterized by further comprising timer means (50) for counting time which has elapsed after said D.C. voltage supplying means (12, 14) is turned on and said discharge lamp (16) is started and characterized in that said control means (30) effects the control operation to raise a voltage of said switching means (Q1) to a preset level for a predetermined period of time in which the time counted by said timer means (50) reaches a preset period of time and set the voltage of said switching means (Q1) detected by said voltage detection means (40) to a constant level after the time counted by said timer means (50) has exceeded the preset period of time.
Claim 5
Dependent Claim
44 words
An apparatus according to claim 3, characterized in that said timer means (50) counts a course of time from when said discharge lamp (16) is turned on by integrating voltage generated between terminals of said discharge lamp (16) after rectifying and smoothing said voltage.
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