Optical scanning device and image forming apparatus including the same

An image forming apparatus comprising:

• an optical scanning device;
• a developing unit arranged to develop an electrostatic latent image formed on a scanned surface by the optical scanning device, as a toner image;
• a transfer unit arranged to transfer the developed toner image on a transferred material;
• and
• a fixing unit arranged to fix the transferred toner image to the transferred material,
• wherein the optical scanning device includes a deflecting unit having a first deflecting surface and arranged to deflect a light beam and optically scan the scanned surface in a main-scanning direction, an incident optical system arranged to cause the light beam to be obliquely incident on the first deflecting surface in a sub-scanning section, an imaging optical system arranged to guide a light beam deflected by the first deflecting surface onto the scanned surface, and a light receiving unit arranged to receive a light beam deflected by the first deflecting surface and generate a signal,
• wherein the incident optical system and the imaging optical system do not include optical elements integrally formed with each other, and
• wherein a following condition is satisfied,
• |β|≦|α|,
• where α (deg) is an incident angle of the light beam from the incident optical system with respect to the first deflecting surface in the sub-scanning section, and β (deg) is an angle defined by the light beam incident on the first deflecting surface and the light beam deflected by the deflecting surface and directed toward the light receiving unit in a main-scanning section.

An optical scanning device comprising:

• a light source;
• a deflecting unit having a first deflecting surface, and arranged to deflect a light beam from the light source and optically scan a scanned surface in a main-scanning direction;
• and
• an incident optical system arranged to guide the light beam from the light source to the first deflecting surface;
• and
• an imaging optical system arranged to guide a light beam deflected by the first deflecting surface onto the scanned surface,
• wherein the deflecting unit is formed of a single rotating polygon mirror,
• wherein the incident optical system and the imaging optical system do not include optical elements integrally formed with each other,
• wherein the incident optical system causes the light beam to be incident on the first deflecting surface from the outside of a scanned area in a main-scanning section, and causes the light beam to be obliquely incident on the first deflecting surface in a sub-scanning section, and
• wherein the light source emits the light beam at a timing at which the light beam from the incident optical system is vertically incident on the first deflecting surface in the main-scanning section.