Light scanning unit and image forming apparatus

An image forming apparatus comprising:

• a light scanning unit configured to generate a light, the light scanning unit including a source, a deflector, and an optical imaging system;
• a photosensitive medium on which a latent image is formed by the light generated by the light scanning unit;
• a developer configured to develop the latent image on the photosensitive medium;
• and a transfer unit configured to receive the image developed by the developer, wherein the source of the light scanning unit is configured to generate the light, wherein the deflector of the light scanning unit is configured to deflect the light generated by the source, wherein the optical imaging system of the light scanning unit is configured to form the light deflected by the deflector into an image on the photosensitive medium, the optical imaging system including a first optical imaging lens and a second optical imaging lens, the first optical imaging lens and the second optical imaging lens collectively configured to have the functionality of an f-theta lens, and wherein the optical imaging system is configured such that a first ratio of an f-theta scanning coefficient of the optical imaging system to a main scanning focal distance of the optical imaging system is higher than about 0.81 and lower than about 0.88, and a second ratio of the main scanning focal distance of the optical imaging system to a main scanning focal distance of the first optical imaging lens is higher than about 0.6 and lower than about 0.91.

A light scanning unit for an image forming apparatus, comprising:

• a source configured to generate a beam of light;
• a deflector configured to deflect the beam of light generated by the source, the source and the deflector defining a first optical path having a first optical axis;
• and an optical system configured to have the functionality of an f-theta lens, the optical system and the deflector defining a second optical path having a second optical axis substantially perpendicular to the first optical axis of the first optical path, the optical system having a first member and a second member, an optical axis of the second member of the optical system being offset from the optical axis associated with the second optical path,
• wherein the optical system is configured such that a first ratio of an f-theta scanning coefficient of the optical system to a main scanning focal distance of the optical system is higher than about 0.81 and lower than about 0.88, and a second ratio of the main scanning focal distance of the optical system to a main scanning focal distance of the first member of the optical system is higher than about 0.6 and lower than about 0.91.

A light scanning unit for an image forming apparatus, comprising:

• a source configured to generate a beam of light;
• a deflector configured to deflect the beam of light generated by the source, the source and the deflector defining a first optical path having a first optical axis;
• and an optical system configured to have the functionality of an f-theta lens, the optical system and the deflector defining a second optical path having a second optical axis substantially perpendicular to the first optical axis of the first optical path, the optical system having a first member and a second member, an optical axis of the second member of the optical system being offset from the optical axis associated with the second optical path,
• wherein the second member of the optical system is configured such that a ratio is more than about 1.5 and less than about 3, the ratio being a ratio of a sub-scanning curvature radius of an incident surface of the second member of the optical system on the optical axis of the optical system to a sub-scanning curvature radius of an exit surface of the second member of the optical system on the optical axis of the optical system.