Image forming apparatus

An image forming apparatus, comprising:

• an electrophotographic photosensitive member;
• a light source for producing a beam;
• control means for controlling an on-period of the beam per picture element of said light source in accordance with an image signal to be recorded;
• an optical system for scanning said photosensitive member with the beam from said light source on said photosensitive member, wherein the beam provides on said photosensitive member a spot having a size, measured in a main scan direction, which is not more than 0.7 times a size of a unit picture element and which is not more than 42 microns;
• developing means for developing the electrostatic latent image formed on said photosensitive member by said optical system scanning said photosensitive member, wherein said developing means supplies a developer to said photosensitive member, the developer containing toner particles having a volume average particle size M of not more than 12 microns;
• image transfer means for transferring a developed image formed on said photosensitive member onto a transfer material;
• and
• fixing means for fixing the developed image transferred onto the transfer material,
• wherein said developing means reverse-develops the electrostatic latent image,
• wherein said light source includes a semiconductor laser device, and said control means controls a laser driving pulse width in accordance with the image signal,
• wherein the toner has such a particle size distribution that not less than 90% by volume of the toner particles satisfy:
• (1/2)M<r<(3/2)M, and
• that not less than 99% by volume of the toner particles satisfy:
• <
• r<2M,
• where r is a particle size of the toner particle.

An image forming apparatus, comprising:

• an electrophotographic photosensitive member;
• latent image forming means for forming electrostatic latent images corresponding to plural colors on said photosensitive member, wherein said latent image forming means includes a semiconductor laser means, control means for controlling a driving pulse width of the semiconductor laser beam in accordance with an image signal to be recorded and an optical system for scanning said photosensitive member with a beam emitted from said semiconductor laser beam in a main scan direction;
• wherein the beams provide a spot on said photosensitive member having a size, measured in the main scan direction, which is not more than 0.7 times a size of a unit picture element of said image forming apparatus and which is not more than 42 microns;
• developing means having a plurality of developing devices for supplying different color developers to said photosensitive member, said developing devices each reverse-developing the electrostatic latent images with corresponding color developer;
• image transfer means for transferring the developed images onto a transfer material;
• fixing means for fixing the developed images overlaid on the transfer material,
• wherein said developing means supplies to said photosensitive member the developer containing the toner having such a particle size distribution that not less than 90% by volume of the toner particles satisfy:
• (1/2)M<r<(3/2)M, and
• not less than 99% by volume of the toner particles satisfy:
• 0<r<2M,
• where M is a volume average particle size of the toner, and r is a particle size of the toner particle.