1/05
10-72
DocuColor 12/DCCS50
Image Sensing (Digital Copier & Copier/Printer Con-
Reissue
Principles of Operation
Figure 4 Xenon Lamp Interrupted Drive Waveform
Carriage Motor and Drive
The Carriage Motor is a high-torque five-phase stepping motor driven by five magnetic control
lines: A through E. These lines are +24 VDC outputs of the Motor/Fan/Lamp Driver PWBA
which is under the control of the CPU on the Pre-IPS PWBA. +24 VDC is applied to all lines
when the motor is locked in one position.
The motor uses rubber dampers to isolate vibrations f
rom t
he rest of the IIT. It also uses mag-
netic damping to maintain a constant speed.
The motor emits a pulse ever 0.72 degrees of rotation. This is equivalent to 500 pulses per one
compl
ete motor revolution. These pulses are routed back to the Motor/Fan/Lamp Driver PWBA.
This assembly uses the interval between the pulses to determine if the carriage speed is cor-
rect and the cumulative number of pulses to determine the current location of the carriage.
Full and Half-Rate Carriages
The Xenon Lamp is mounted in the Full-Rate Carriage (Figure 1). Reflected light from the orig-
inal document is passed via mirrors through a stationary lens to a CCD PWBA. To maintain a
constant
image size, the distance between the original document and CCD (known as the con-
jugate) must remain constant. Therefore, an additional Half-Rate Carriage, traveling at half the
speed of
the F
ull-Rate Carriage, is used. Figure 5 shows the carriages and their relative
motion.
• T is the distance which the Half-Rate Carriage Moves
• 2T is the distance which the Full-Rate Carriage moves
• A is the distance from the original document to t
he mirror on the Full-Rate Carriage. This
distance is constant
• B is the minimum distance between the Full-Rate Carriage mirror and the top mirror on
the
Half-Rate Carriage. This occurs when the two carriages are at the start of their travel.
During carriage travel, this distance increases to a maximum of B + 2T - T=B + T.
• C is the distance between the mirrors on the Half-Rate Carriage, and is constant
• D is the maximum distance between the bottom Half-Rate Carriage mirror and the station-
ary mirror in front of the CCD PWBA. This occurs when the two carriages are at the start
of
t
heir travels. During carriage travel, this distance decreases to a minimum of D - T.
At the start of carriage travel, the conjugate is A + B + C + D. At the end of carriage travel, the
distanc
e is A + (B + 2T - T) + C + (D - T) = A + B + C + D.
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