Ricoh SP 8400DN Field Service Manual page 1441

Ricoh a3 size black and white laser printer.

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compensates charge bias (Vc) and LD power based on the Vb result.

Slightly high

Slightly low

Fig. 1: Relation b/w Dev. bias and Toner adhesion amount

Vtref Compensation

To maintain a constant/proper toner density, the toner density in the developer must be controlled as well as the

bias control. Vtref is the target of the toner density in the developer.

Vtref Determination

With the output of the ID sensor and the TD sensor (µ sensor) in ID sensor detection, the machine determines

the Vtref used for the reference value for the TD sensor (µ sensor).

TD sensor (µ sensor) Initial Setting When a New PCDU Is Installed

When a new PCDU is set in the mainframe, this is detected by the machine as a new PCDU, and the initial µ

count (the output from the TD sensor (µ sensor) of initial developer setting) is determined after entering the TD

sensor (µ sensor) initial setting mode. The TD sensor (µ sensor) initial setting is done as follows.

Starting the developer initial setting

The new unit detecting mechanism performs the TD sensor (µ sensor) initial setting.

Developer Agitation

The developer is stirred, with the development roller and the transport coil rotating (30 seconds).

Toner Density

Slightly high

Slightly low

7.Detailed Descriptions

Vb Compensation SP

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