摘要:
A discharge lamp lighting circuit for supplying an AC power to a discharge lamp includes first and second converters for receiving a DC voltage and stepping up the voltage. A controlling circuit drives the first and second converters CON1, CON2 alternately at a first frequency and stops an operation of a side that is not driven such that the AC power is supplied to the discharge lamp to execute a lighting operation.
摘要:
A discharge lamp lighting circuit for supplying an AC power to a discharge lamp includes first and second converters for receiving a DC voltage and stepping up the voltage. A controlling circuit drives the first and second converters CON1, CON2 alternately at a first frequency and stops an operation of a side that is not driven such that the AC power is supplied to the discharge lamp to execute a lighting operation.
摘要:
A discharge lamp lighting circuit includes a power supplying portion having a series resonant circuit including transistors and a bridge driver, a starting portion for applying a high voltage pulse to a discharge lamp to promote a lighting operation, a lighting confirming portion for generating a lighting confirmation signal Sf indicating that a lighting operation for the discharge lamp fails or is successful by the high voltage pulse, and a control portion for generating a control signal Sc to control a driving frequency of the bridge driver. The lighting confirming portion generates a lighting confirmation signal Sf based on a relationship of the magnitude between a lamp voltage equivalent signal VS and a predetermined voltage V4 at a time that a predetermined time Δt passes since the application of the high voltage pulse to the discharge lamp.
摘要:
A discharge lamp lighting circuit 1 is provided with a DC-AC conversion circuit 3 having a plurality of switching elements 5H, 5L and a series resonance circuit (8, 9, 7p), and control means 17 for preventing a situation in which the drive frequency of the switching element remains less than its specified minimum frequency. When the discharge lamp is lit, driving control of the switching element is carried out in a frequency range higher than the series resonance frequency. By using a driving situation detection circuit 15, a driving situation of the switching element is monitored based on a relation with a phase of a lamp current which flows through the discharge lamp. If the drive frequency of the switching element becomes less than the specified minimum frequency, the drive frequency is increased, and thereby, a lower limit of the drive frequency is automatically restricted.
摘要:
A discharge lamp lighting circuit is provided. The discharge lamp lighting circuit includes a power supplying portion which comprises an inverter circuit comprising a switching element; a series resonant circuit comprising a capacitor, and at least one of an inductor and a transformer; and a driving circuit which drives said switching element, said power supplying portion converting DC power to AC power and supplying the AC power to a discharge lamp; and a controlling portion which produces a frequency control signal for controlling a frequency of a drive signal output from said driving circuit, the controlling portion including a phase difference detecting portion which detects a phase difference between an input voltage and an input current that are supplied from said inverter circuit to said series resonant circuit; and a control signal producing portion which produces the frequency control signal in accordance with the phase difference.
摘要:
A discharge lamp lighting circuit includes a power supplying portion having a series resonant circuit containing transistors and a bridge driver, and a control portion for generating a control signal Sc1 to control a driving frequency of the bridge driver. The control portion has a sample hold portion for generating a constant control signal S1, a frequency follow-up control portion for generating a control signal S2 in such a manner that a phase difference between a voltage and a current in the series resonant circuit is approximately zero, and a power control portion for generating a control signal S3 in such a manner that a magnitude of an AC power approximates a steady value. The control signal S1 is selected from a time t3 to a time t4, the control signal S2 is selected from the time t4 to a time t5, and the control signal S3 sent from the power control portion 13 is selected as the control signal Sc1 after the time t5.
摘要:
A A lighting apparatus for a discharge lamp includes a transformer for electric power transmission to the discharge lamp and for supplying a start signal to the discharge lamp. The transformer includes closed magnetic circuit type cores (15, 16) formed of magnetic material, a primary winding 7p, a secondary winding 7s, and an auxiliary winding 7v provided for supplying a voltage necessary for generating the start signal to the start circuit. The primary winding 7p and the secondary winding 7s are wound around the periphery of a common core pole 15a, and the auxiliary winding 7v is wound around another core pole 15b. The start signal is generated based on a voltage supplied from the auxiliary winding 7v and applied to the discharge lamp via the main windings (7p, 7s).
摘要:
A discharge lamp lighting circuit includes a power supplying portion having a series resonant circuit including transistors and a bridge driver, a starting portion for applying a high voltage pulse to a discharge lamp to promote a lighting operation, a lighting confirming portion for generating a lighting confirmation signal Sf indicating that a lighting operation for the discharge lamp fails or is successful by the high voltage pulse, and a control portion for generating a control signal Sc to control a driving frequency of the bridge driver. The lighting confirming portion generates a lighting confirmation signal Sf based on a relationship of the magnitude between a lamp voltage equivalent signal VS and a predetermined voltage V4 at a time that a predetermined time Δt passes since the application of the high voltage pulse to the discharge lamp.
摘要:
A circuit includes a transformer 7 for transmitting power to a discharge lamp 10 and for supplying a starting signal to the discharge lamp. The circuit includes a direct current-alternating current converting circuit 3 for supplying an output of the transformer 7 to the discharge lamp 10 after carrying out a direct current-alternating current conversion, and a starting circuit 4 for applying the starting signal to the discharge lamp 10. A primary side of the transformer 7 has a first capacitor 11, a circuit portion 13 including a rectifying element, and a switching element 14. The transformer 7 has an auxiliary winding 7v for supplying a voltage for generating the starting signal to the starting circuit. A second capacitor 12 is interposed between the auxiliary winding and the circuit portion 13 and prevents absorption of energy by the capacitor 11 in generating the starting signal and prevents attenuation of the starting signal
摘要:
A discharge lamp lighting circuit is provided. The discharge lamp lighting circuit includes an inverter circuit which has two output ends; a series resonant circuit which includes a capacitor, an inductor and a transformer, coupled in series; a driving portion; and a controlling portion which provides a control signal for controlling said inverter circuit, said controlling portion including a first signal producing portion which produces a first signal indicative of a phase of a current flowing through said series resonant circuit; and a second signal producing portion which produces a second signal indicative of a phase of the AC voltage output from said inverter circuit, said controlling portion producing the control signal on the basis of a phase difference between the first and second signals, wherein one component of said series resonant circuit is coupled between one of said output ends, and a detection point.