Light emitting diode driver and image forming device including the same

A light emitting diode driver arranged to supply a drive current to a light emitting diode, the light emitting diode arranged with a photo detector that forms a monitor signal based on a radiant output that is formed by the light emitting diode, the drive current comprising a first current and a second current;

• the first current formed by a voltage difference across a resistor;
• the voltage difference formed by drive current's nodal voltage and a high speed, buffer output;
• the high-speed buffer output formed by a comparison signal;
• the comparison signal formed by comparing the monitor signal and a level control signal;
• and the second current provided by a current source whose input terminal is driven by an operational amplifier, the operational amplifier having an input signal that is the voltage difference formed by drive current's nodal voltage and the high speed buffer output.

An image forming device comprising a light emitting diode driver, the light emitting diode driver arranged to supply a drive current to a light emitting diode, the light emitting diode arranged with a photo detector that forms a monitor signal based on a radiant output that is formed by the light emitting diode, the drive current comprising a first current and a second current and formed by comparing the monitor signal and a level control signal to form a comparison signal;

• providing a buffered output signal based on the comparison signal;
• forming a voltage difference based on the buffered output signal and the drive current nodal voltage;
• providing the first current based on the voltage difference and a resistor;
• providing an amplified signal based on the difference voltage;
• and providing the second current based on the amplified signal.

An image forming device comprising a light emitting diode driver, the light emitting diode driver arranged to supply a drive current to a light emitting diode, the light emitting diode arranged with a photo detector that forms a monitor signal based on a radiant output that is formed by the light emitting diode, the drive current comprising a first current and a second current;

• the first current formed by a voltage difference across a resistor;
• the voltage difference formed by drive current's nodal voltage and a high speed buffer, output;
• the high-speed buffer output formed by a comparison signal;
• the comparison signal formed by comparing the monitor signal and a level control signal;
• and the second current provided by a current source whose input terminal is driven by an operational amplifier, the operational amplifier having an input signal that is the voltage difference formed by drive current's nodal voltage and the high speed buffer output.