Morgana DocuMaster MFC, Руководство по обслуживанию

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Morgana DocuMaster MFC - Service Manual 13
1. Introduction - Description of Operation
1
1.9 Description of Operation
After the MFC system is turned on, the operator sets the paper size and type of finish;
the number of inner sheets and cover insert; the sheet sensing position, and a crease
type. The paper is loaded into the feed bins face down with the first sheet of the booklet
(centre sheet) at the top of the stack.
1.9.1 The Test Set
Before the MFC can process a job, it must complete a Test Set. The Test Set is
important because it records necessary data about the paper sheets in the MFC feed
bins. The MFC uses this data to setup the feed bins’ feed control and paper sensing
systems. Sheets can then be fed correctly and feed errors can be sensed when the job
is running.
Each feed bin is controlled by a bin control PCB. Each control PCB controls all of the
feed bin functions using a programmed, IC (Integrated Control) chip that is installed on
the PCB. The PCB is connected to a system of input sensors and control outputs to the
bin components. A feed bin can only operate correctly if the IC has recorded and
stored data about the paper to be fed. The feed bin records data about the length and
optical density of a sheet when it does a Test Set.
When the START button is pressed, the MFC's CPU (Central Processing Unit) sends a
start signal to the crease controller PCB and to the feed bins. The controller pcb starts
the conveyor motor and creaser conveyor motor at a low speed and sends the master
timing PWM (Pulse Width Modulation) signal to the CPU.
The CPU sends instructions through the Data bus communication line. These are
received and stored by each of the feed bin control pcbs. The feed bin control pcbs are
connected in parallel, with their own unique 'address'. When the CPU sends a feed
trigger, each bin will feed at the correct time because they all use the PWM signal from
the controller pcb.
Each time a sheet is fed, the feed bin IC uses the emitter/sensor to measure the optical
density of the sheet at a known reference point from the leading edge of the sheet.
Note: The Default reference point of the optical density check
is 15.2mm from the lead edge of the sheet. This value is
variable and can be adjusted electronically from the GUI to
overcome problems caused by print variations (see About the
Machine, in the DocuMaster MFC User Operating Instructions
Manual).
When the sheet is in the conveyor guides, the emitter is turned on and the sensor
receives more light through a low density sheet, and less light through a high density
sheet. The density is sensed as a voltage, which is then converted into a digital value
on an 8-bit scale between 0 - 255. This data can be seen as the 'Ref' value from the
FEEDER INFO
page on the GUI panel. Each feed bin stores its own Ref value because
the paper or the print may be different.
Because the paper and print density might vary slightly during a job, the MFC must
calculate a 'Limit', or tolerance, that it will allow either side of the Ref value before it
detects a feed error. When the MFC is running, the feed bin control PCB uses the
emitter/sensor to check each sheet and compare it to its Ref value.