Systems and methods for adjusting the dynamic range of a scanning laser beam

An imaging system for an electrophotographic device comprising:

• a laser source for emitting a laser beam;
• a scanner for causing said laser beam to sweep along a scan line;
• a laser driver circuit for supplying at least a bias current and a laser drive current to cause said laser source to emit said beam;
• a controller communicably coupled to said laser driver for controlling an output power of said laser beam;
• a laser power control signal coupled between said laser driver circuit and said controller;
• and
• a second control signal other than said laser power control signal for affecting at least one of said bias current and said laser drive current, wherein:
• said second control signal is set to a first value by said controller during a laser power adjustment cycle of operation such that a beam output by said laser source has a power level within a first dynamic range of power levels, the power level of said beam is adjustable within said first dynamic range of power levels by controlling a value of said laser power control signal and a limited control range of values of said laser power control signal correspondingly limits the operating range of said beam to said first dynamic range of power levels;
• and
• said second control signal is set to a second value by said controller after calibrating said laser power so as to shift the operating range of said laser source from said first dynamic range to a second dynamic range that is different from said first dynamic range, such that said limited control range of values of said laser power control signal correspondingly limits the operating range of said beam to said second dynamic range of power levels and said laser source is operable within a second range of power levels by setting said laser power control signal to a predetermined value when said laser source is swept along an image area of a photoconductive surface.

A method of adjusting a dynamic range of laser power in an imaging system for an electrophotographic device comprising:

• sweeping a beam emitted by a laser source along a scan line, said scan line having a non-imaging section wherein said beam is outside of an image area of a photoconductive surface and a imaging section wherein said beam is within said image area of said photoconductive surface;
• setting a bias current supplied to said laser source to a first bias current level;
• calibrating a laser drive current while said beam is within said non-imaging section of said scan line to a level necessary to cause said beam to be emitted by said laser source at a first output power level, said laser drive current based at least upon said first bias current level, wherein:
• the power level of said beam is adjustable within a first dynamic range of power levels by controlling a value of a laser power control signal;
• and
• a limited control range of values of said laser power control signal correspondingly limits the operating range of said beam to said first dynamic range of power levels;
• setting said bias current supplied to said laser source to a second bias current level that is different from said first bias current level after calibrating said laser drive current so as to shift the operating range of said laser source from said first dynamic range to a second dynamic range that is different from said first dynamic range, wherein said limited control range of values of said laser power control signal correspondingly limits the operating range of said beam to said second dynamic range of power levels;
• and
• controlling said beam at within said second dynamic range when said beam is directed towards said image area of said photoconductive surface.