Optical writing device and image forming apparatus

An image forming apparatus, comprising:

• a photosensitive body;
• and
• an optical writing device that exposes the photosensitive body and forms an electrostatic latent image line by line for each horizontal scanning period, wherein the optical writing device includes
• a plurality of current driven light emitting elements arranged in lines,
• first and second power source lines extending along a plurality of light emitting elements, and connected with a constant voltage source,
• a designation circuit that outputs a designation potential designating a light emission amount for each of the light emitting elements,
• first driving circuits provided for each of the light emitting elements, each of the first driving circuits including a first holding circuit that receives and holds the designation potential output from the designation circuit, and connected with the first power source line to supply driving current to the corresponding light emitting element in accordance with a potential difference between a potential at a junction point with the first power source line and the designation potential held by the first holding circuit,
• second driving circuits provided for each of the light emitting elements, each of the second driving circuits including a second holding circuit that receives and holds the designation potential output from the designation circuit, and connected with the second power source line to supply driving current to the corresponding light emitting element in accordance with a potential difference between a potential at a junction point with the second power source line and the designation potential held by the second holding circuit, and
• a switching control unit that controls the first and second driving circuits provided for the same light emitting element so as to alternately switch respective states of the first and second driving circuits between a state where one of the first and second driving circuits receives the designation potential while the other driving circuit supplies the driving current, and a state where the other driving circuit receives the designation potential while the one driving circuit supplies the driving current, for each of the horizontal scanning periods.