Power supply for a field emission light source

A power supply for a field emission lighting source, comprising:

• a DC-DC converter configure to receive a source of direct current at a first voltage level, at an input of the DC-DC converter, and to provide a direct current at a second voltage level, at an output of the DC-DC converter, the second voltage level being higher than the first voltage level;
• a resonant inverter comprising a transformer, the resonant inverter connected to the output of the DC-DC converter and configured to provide a pulsating signal at a first frequency having a third voltage level, the third voltage level being higher than the second voltage level, and
• a voltage multiplier rectifying the pulsating signal to a direct current at a fourth voltage level, the fourth voltage level being higher than the third voltage level, the voltage multiplier comprising a pair of output terminals for connecting to the field emission light source,
• wherein the power supply further comprises a control unit for controlling the resonant inverter based on a feedback relating to the operation of the field emission light source provide from the voltage multiplier, and
• wherein the voltage multiplier comprises a plurality of pairs of diodes and capacitors arranged on opposite sides of a PCB of the power supply, respectively, wherein the PCB comprises a plurality of air-gap provided in relation to the pairs of diodes and capacitors for increasing an electrical insulation between the pair of diodes and capacitors.

A lighting device, comprising:

• a field emission light source, comprising:
• a field emission cathode;
• an anode structure at least partly covered by a phosphor layer, said anode structure being configured to receive electrons emitted by the field emission cathode, and
• an evacuated chamber in which the field emission cathode and anode structure and field emission cathode is arranged, and
• a power supply comprising:
• a DC-DC converter configure to receive a source of direct current at a first voltage level, at an input of the DC-DC converter, and to provide a direct current at a second voltage level, at an output of the DC-DC converter, the second voltage level being higher than the first voltage level,
• a resonant inverter comprising a transformer, the resonant inverter connected to the output of the DC-DC converter and configured to provide a pulsating signal at a first frequency having a third voltage level, the third voltage level being higher than the second voltage level, and
• a voltage multiplier rectifying the pulsating signal to a direct current at a fourth voltage level, the fourth voltage level being higher than the third voltage level, the voltage multiplier comprising a pair of output terminals for connecting to the field emission light source,
• wherein the power supply further comprises a control unit for controlling the resonant inverter based on a feedback relating to the operation of the field emission light source provide from the voltage multiplier,
• the power supply connected to the anode and the field emission cathode and configured to apply a voltage so that electrons are emitted from the cathode to the anode for emitting light.

A method for controlling a power supply configured to apply an adjustable voltage level to a light source, the power supply comprising a resonant inverter, wherein the method comprises:

• determining a frequency for a signal configured to provide an operational power for the power supply;
• selecting a multiple of the frequency of the mains signal as a PWM base frequency;
• controlling the resonant inverter to stop producing an output for a predetermined duration based on PWM control of the resonant inverter at the selected PWM base frequency,
• thereby allowing an average voltage level to the light source to be controlled for controlling the intensity level of the light source.