Reflective optical sensor and image forming apparatus
A reflective optical sensor includes at least three light-emitting elements; a lighting optical system that guides light emitted from the light-emitting elements to a toner pattern; and at least three light-receiving elements that receive the beams of light reflected by the toner pattern. The lighting optical system has a lateral magnification m that satisfies m≦P/S, where S is the size of the light-emitting elements and P is the arrangement pitch of the light-emitting elements.
1. An image forming apparatus comprising:
an image carrier;
an optical scanning device that scans the image carrier with a beam of light in a main-scanning direction, thereby forming a latent image, wherein the beam of light is modulated in accordance with image data;
a developing device that forms a toner image by attaching toner to the latent image;
a transferring device that transfers the toner image onto a medium;
a reflective optical sensor that detects at least one of a position of or a toner density of a toner pattern on the image carrier or the medium, wherein the reflective optical sensor includes
a light-emitting system that includes at least three light-emitting elements arranged at equal intervals in a certain direction;
a lighting optical system that guides light emitted from the light-emitting system to the toner pattern;
a light-receiving system that includes at least three light-receiving elements arranged at equal intervals in the certain direction, wherein the light-receiving system receives light reflected from the toner pattern,
wherein the lighting optical system is arranged so that L/L 0 <P/S is satisfied,
where L 0 is distance between the light-emitting system and the lighting optical system,
L is distance between the lighting optical system and the image carrier when the toner pattern on the image carrier is detected; or L is distance between the lighting optical system and the medium when the toner pattern on the medium is detected,
S is size of the light-emitting elements, and
P is arrangement pitch of the light-emitting elements.
2. The image forming apparatus according to claim 1 , wherein L/L 0 is less than 10.
3. The image forming apparatus according to claim 1 , wherein the image data is multi-color image data.
4. The image forming apparatus according to claim 2 , wherein the image data is multi-color image data.