17
Ricoh Co. Ltd.
http://www.ricoh.com/
B245-62 / PD-C4
Slide 17
Copy Process
Development
Laser exposure
Drum charge
Cleaning
Image transfer
Paper separation
Quenching
ID Sensor
See the notes for copy process details.
Exposure
¾
A xenon lamp exposes the original. Light reflected from the original passes to the CCD, where it is converted
into an analog data signal. This data is converted to a digital signal, processed and stored in the memory. At
the time of printing, the data is retrieved and sent to the laser diode which writes the image on the drum.
Drum Charge
¾
In the dark, the charge roller gives a negative charge to the organic photo-conductive (OPC) drum. The charge
remains on the surface of the drum because the OPC layer has a high electrical resistance in the dark.
Laser Exposure
¾
The processed data scanned from the original is retrieved from the memory and transferred to the drum by a
laser beam, which forms an electrical latent image on the drum surface. The amount of charge remaining as a
latent image on the drum depends on the laser beam intensity, which is controlled by the BICU board.
Development
¾
The magnetic developer brush on the development roller comes in contact with the latent image on the drum
surface. Toner particles are electrostatically attached to the areas of the drum surface where the laser reduced
the negative charge on the drum.
ID Sensor
¾
The laser forms a sensor pattern on the drum surface. The ID sensor measures the reflectivity of the pattern.
The output signal is one of the factors used for toner supply control. Also, the ID sensor measures the
reflectivity of the drum surface. The output signal is used for charge roller voltage control.
Image Transfer
¾
Paper is fed to the area between the drum surface and the transfer roller at the proper time for aligning the copy
paper and the developed image on the drum surface. Then, the transfer roller applies a high positive charge to
the reverse side of the paper. This positive charge pulls the toner particles from the drum surface onto the
paper. At the same time, the paper is electrostatically attracted to the transfer roller.
Paper Separation
¾
Paper separates from the drum as a result of the electrostatic attraction between the paper and the transfer
roller. The discharge plate (grounded) helps separate the paper from the drum.
Cleaning
¾
The cleaning blade removes any toner remaining on the drum surface after the image transfers to the paper.
Quenching
¾
The light from the quenching lamp electrically neutralizes the charge on the drum surface.
