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Detecting the Size of Originals
Overview
The machine identifies the original size by the combination of measurement result of reflection light from the reflection sensor and specific points of CCD. Also to identify it accurately even though an original moves when ADF is closed, the machine measures 2 points for each size.
- Main scanning direction: CCD (AB type: 8 points measurement, inch type: 6 points measurement)
- Sub scanning direction: Reflection type photo sensor (AB type: 1 point, inch type: 1 point (original sensor 2 is not used.))
The followings are the procedures of original size identification.
1) External light search (main scanning direction only)
According to the LED status, the machine identifies the CCD level of each detection position in main scanning direction.
2) Output level detection of each sensor
The machine turns on the LED on CCD unit and measures the CCD level of each detection position in main scanning direction.
Also, turns on the LED on reflection type photo sensor in sub scanning direction and measures the sensor output.
The original size is identified by the combination of these output result.
Control Details
For main scanning direction, the machine moves the CCD unit to the following CCD original detection positions according to the location of original to measure the CCD level of each detection position. For sub scanning direction, the machine uses the original sensor 0, 1 to identify sizes.
1. 2 points original detection at each detection position
For each point of measurement in main scanning direction, the machine checks the presence/absence of an original with reference to the CCD output at 2 points near the point of measurement.
* The machine checks if the signal is changed or not from ADF (pressure plate) open to close at both points of 1A and 1B.
Change in the signal: Yes
Change in the signal: No
Judgment is done by the measurement results of 1A and 1B, and it indicates the presence of original if either point shows absence (absence). It indicates absence
of original if both signals show Yes (presence).
Change
Result of detection
1A
1B
Yes
Yes
Original absence
No
Yes
Original presence
Yes
No
Original presence
No
No
Original presence
2. Priority on the front sensor
When checking the measurements for main scanning direction, if the absence of an original is indicated at the rear while the presence of an original is indicated at the front, the machine will give priority to the indication at the front.
In case of B5 size original
Position of detection
Result of detection
Result of
identification
1
Yes
Yes
2
No
Yes
3
Yes
Yes
4
No
No
Detection Operation Overview
1) Standby state (The following is in case that the AB type, A4R size is set.)
CCD unit: shading position
LED: OFF
Original sensor: OFF
2) ADF opened
CCD unit: moves to original detection position
LED: OFF
Original sensor: OFF
3) ADF closed
CCD unit: in original detection position
LED: OFF to ON
Original sensor: in original detection operation
- With the ADF angle at 25 deg or less, the external light is blocked at the original width area. Then, the machine determines that the original is absent at the points that the external light is detected (external light search operation). When the original mount sensor (rear) detects [close], original size detection is started. In this case, B5/B4/A4/A3 size is eliminated at this point.
- After external light search, LED is turned ON at main scanning side and the CCD checks the reflection light (4 points). For sub scanning direction, original sensor detects the size.
4) ADF fully closed (5 deg or less)
CCD unit: in original detection position
LED: ON
Original sensor: in original detection operation
- For 2 sec from the original mount sensor (front) detected [close], this monitors the changes of output level of each sensor. The machine determines that the original is present in the position where the level is not changed.
The machine identifies the original size by the combination of level changes at 5 points (in case of AB type size).
5) Standby status (waiting for start key)
CCD unit: in original detection position
LED: OFF
Original sensor: OFF