Printing apparatus and toner density measuring method
AssigneeFujitsu Limited of Kawasaki, Japan
InventorHirofumi Nakayasu
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Abstract
A toner mark transfer unit transfers a halftone pattern such as a transverse line pattern or a slanted line pattern on a belt by using a plurality of electrostatic recording units. A toner density measurement unit figures out density control parameters such as emission time and emission current on the basis of the ratio of a reflected light (inter-line space width) from the toner free portion to a light (line width) attenuated due to a diffuse light from the toner bearing portion in a read signal of a halftone pattern from a sensor unit.
Claims14
A printing apparatus comprising:
- a belt unit which conveys record sheets on a belt at a constant speed, said record sheets being electrostatically adhered to the surface of said belt;
- a plurality of electrostatic recording units arranged in the direction of conveyance of said record sheets, said electrostatic recording units forming a latent image corresponding to image data through an optical scanning on a photosensitive drum in rotation by an exposure device, said electrostatic recording units developing said latent image with a toner component of different color, to thereafter transfer said developed image onto said record sheets lying on the surface of said belt;
- a toner transfer unit which transfers a halftone pattern onto the surface of said belt by use of said plurality of electrostatic recording units;
- a sensor unit which optically reads said halftone pattern transferred onto the surface of said belt;
- and
- a toner density measurement unit which measures the toner density on the basis of the ratio of a reflected light from a toner bearing portion to a reflected light from a toner free portion in a read signal of said halftone pattern from said sensor unit.
A toner density measuring method for a printing apparatus having a belt unit which conveys record sheets on a belt at a constant speed, said record sheets being electrostatically adhered to the surface of said belt, and having a plurality of electrostatic recording units arranged in the direction of conveyance of said record sheets, said electrostatic recording units forming a latent image corresponding to image data through an optical scanning on a photosensitive drum in rotation by an exposure device, said electrostatic recording units developing said latent image with a toner component of different color, to thereafter transfer said developed image onto said record sheets lying on the surface of said belt, said method comprising the steps of:
- transferring a halftone pattern onto the surface of said belt by use of said plurality of electrostatic recording units;
- optically reading said halftone pattern transferred onto the surface of said belt, by use of a sensor unit;
- and
- measuring the toner density on the basis of the ratio of a reflected light from a toner bearing portion to a reflected light from a toner free portion in a read signal of said halftone pattern.
Dependencies are inferred from the claim text.