Toshiba 4560, Service Manual

Page: 286 / 369

4560/4570 RADF 18 - 28 Nov. 1997 © TOSHIBA
18.8 Detection of Original Sizes
The size of originals is determined by both the number of pulses generated until the original passes the
aligning sensor and its width roughly detected by the size sensor 1.
(1) Each time the ADF feeds in an original, it detects its size and lets the copier know the lengthwise feed
and widthwise directions in millimeters, respectively.
(2) Method of detecting the size of originals
The length of the original is measured by using the number of drive motor clock pulses generated
from the start of original transporting (when the aligning roller starts rotating) until the aligning sensor
is turned off (when the trailing edge of the original passes the sensor). Since A4 widthwise and A5
lengthwise cannot be distinguished by the length in the feed direction alone, the size sensor 1 is used
roughly to know the width of the original, permitting its size to be determined (for A4 widthwise, the
size sensor 1 is turned on).
Note that the size sensor 2 is used to distinguish between A4 widthwise and Letter widthwise. A4
widthwise is 210 mm and Letter widthwise is 216 mm, respectively, in the feed direction. Since the
difference is only 6 mm, judgement would be difficult. So the size sensor 2 is additionally used to
distinguish between A4 and Letter sizes. The size sensor 2 is turned on for A4 lengthwise which is
297 mm and off for Letter lengthwise which is 279 mm.
REGS
SIZE S2
SIZE S1