Fluorescent lamp controllers

A controller for a fluorescent lamp load, comprising:

• DC-AC converter means having an input and an output, DC supply means coupled to said input, output circuit means coupled to said output and arranged for coupling to said fluorescent lamp load, and control means for controlling operation of said DC-AC converter means and said DC supply means, said output circuit means including inductance means and a resonant capacitor means, and said DC-AC converter means being operable at a variable frequency, said control means being arranged to operate in an ignition phase to operate said converter means at a predetermined high frequency well above the resonant frequency of said output circuit and to then gradually reduce said frequency until ignition occurs in said fluorescent lamp load.

A controller for a fluorescent lamp load, comprising:

• DC-AC converter means having an input and an output, DC supply means coupled to said input, output circuit means coupled to said output and arranged for coupling to said fluorescent lamp load, and control means for controlling operation of said DC-AC converter means and said DC supply means, said output circuit means including inductance means and a resonant capacitor means, and said DC-AC converter means being operable at a variable frequency, said control means being arranged to operate in an ignition phase to operate said converter means at a predetermined high frequency substantially different from the resonant frequency of said output circuit and to then change said frequency toward said resonant frequency until ignition occurs in said fluorescent lamp load, said control means being arranged for discontinuing said ignition phase in response to the reaching of a predetermined condition beyond which a further change in frequency toward said resonant frequency might be unsafe.

A controller for a fluorescent lamp load, comprising:

• DC-AC converter means having an input and an output, DC supply means coupled to said input, output circuit means coupled to said output and arranged for coupling to said fluorescent lamp load, and control means for controlling operation of said converter and supply means, said DC supply means comprising input rectifier means having an input for coupling to a source of an AC input voltage and arranged to draw an AC input current from said source of said AC input voltage to develop a full-wave rectified AC voltage, and a switch mode power supply circuit having a gating pulse input and arranged to convert said rectified AC voltage to a DC output voltage having a magnitude controlled by the width of high frequency gating pulses applied to said input, said control means including pulse width modulator means for applying high frequency gating pulses to said switch mode power supply circuit which have a width so controlled as to maintain said DC output voltage at a substantially constant level while also obtaining a wave form of said AC input current which is proportional to and in phase with a waveform of said AC input voltage.

A controller for a fluorescent lamp load, comprising:

• DC-AC converter means having an input and an output, DC supply means coupled to said input, output circuit means coupled to said output and arranged for coupling to said fluorescent lamp load, and control means for controlling operation of said converter and supply means, said DC supply means comprising input rectifier means arranged to develop a full-wave rectified AC voltage, and a first switch mode power supply circuit having a gating pulse input and arranged to convert said rectified AC voltage to a DC output voltage having a magnitude controlled by the width of high frequency gating pulses applied to said input, and said DC-AC converter means comprising a second switch mode power supply for developing an AC output controlled by gating pulses applied thereto, said control means including first pulse supply means for applying a first high frequency gating pulse signal to said first switch mode power supply circuit and second pulse supply means for applying a second high frequency gating pulse signal to said second switch mode power supply, said first and second gating pulse signals being applied in synchronized relation to each other.

A DC supply comprising:

• input rectifier means having an input for coupling to a source of an AC input voltage and arranged to draw an AC input current from said source of said AC input voltage to develop a full-wave rectified AC voltage, a switch mode power supply circuit having a gating pulse input and arranged to convert said rectified AC voltage to a DC output voltage having a magnitude controlled by the width of high frequency gating pulses applied to said input, and control means for controlling said switch mode power supply circuit and including pulse width modulator means for applying high frequency gating pulses to said switch mode power supply circuit which have a width so controlled as to maintain said DC output voltage at a substantially constant level while also obtaining a wave form of said AC input current which is proportional to and in phase with a waveform of said AC input voltage.

A controller for a fluorescent lamp load, comprising:

• DC-AC converter means having an input and an output, DC supply means coupled to said input, output circuit means coupled to said output and arranged for coupling to said fluorescent lamp load, and control means for controlling operation of said converter and supply means, said DC-AC converter means comprising a switch mode power supply circuit which includes transistor means, and said output means including inductance and capacitance means and being operative under normal operating and load conditions to present an inductive load to said switch mode power supply such that currents through said transistor means have lagging phase relation to applied voltages, and protection means for developing and comparing signals which correspond to said currents through said transistor means and said applied voltages to measure the phase of currents through said transistor means relative to said applied voltage, and means for effecting a predetermined change in the operation of said converter means in response to a shift of said measured phase in a leading direction and beyond a certain threshold phase.

A controller for a fluorescent lamp load, comprising:

• DC-AC converter means including a switch mode power supply circuit and having an input and an output, DC supply means coupled to said input, output circuit means coupled to said output and arranged for coupling to said fluorescent lamp load, and control means for controlling operation of said converter and supply means, said DC supply means comprising input rectifier means arranged to develop a full-wave rectified AC voltage, and a switch mode power supply circuit having a gating pulse input and arranged to convert said rectified AC voltage to a DC output voltage having a magnitude controlled by the width of high frequency gating pulses applied to said input, and voltage-applying means for applying a supply voltage to said control means for operation thereof and including means for applying said supply voltage to said control means from said input rectifier means at least during a starting time interval following application of an input AC voltage to said input rectifier means.