Light attenuation controlling apparatus and method for a CDM lamp

A light attenuation controlling method for a CDM lamp, wherein:

• the method is applied to a light attenuation controlling apparatus for a CDM lamp, the apparatus comprises:
• a full-bridge inverter as a power source to supply an output to the CDM lamp;
• a driving circuit for driving the full-bridge inverter;
• a single-chip microcomputer connected to the driving circuit;
• a tube-voltage sensing module, one end of which is connected to the full-bridge inverter so as to sense a tube voltage currently outputted by the full-bridge inverter to the CDM lamp, and the other end of which is connected to the single-chip microcomputer, characterized in that:
• the method specifically comprises steps of:
• S100:
• when the apparatus is working, detecting whether a DC input voltage is present at an input side of the full-bridge inverter;
• in the case of absence, determining that an abnormality exists at the input side of the full-bridge inverter;
• in the case of presence, proceeding to next step;
• S200:
• outputting, by the tube voltage sensing module, the sensed tube voltage of the CDM lamp to the single-chip microcomputer;
• S300:
• controlling, by the single-chip microcomputer, the driving circuit based on the sensed tube voltage of the CDM lamp so as to regulate the output of the full-bridge inverter, thereby controlling light attenuation of the CDM lamp, wherein
• a DC input voltage in the step S100 is provided through an output of the chopper circuit, and the single-chip microcomputer can regulate an output of the chopper circuit;
• the apparatus further comprises a power factor correcting circuit, an input end of which is connected to an output end of the full-bridge rectifier, and a bus voltage output end of which is connected to an input end of the chopper circuit;
• moreover, the power factor correcting circuit is controlled by the single-chip microcomputer;
• and
• the apparatus further comprises a power factor correcting circuit, an input end of which is connected to an output end of the full-bridge rectifier, and a bus voltage output end of which is connected to an input end of the chopper circuit;
• moreover, the power factor correcting circuit is controlled by the single-chip microcomputer.