Toshiba 3511 Automatic Original Size Detection Circuit, Principle of original size detection

6

6.6 Automatic Original Size Detection Circuit

This circuit detects the size of original (standard sizes only) using the reflection type photosensors arranged on the base frame of the scanner unit.

6.6.1 Principle of original size detection

Reflection type photosensors are placed on the base frame of the scanner unit as shown in the Fig. 6-

601.Each sensor consists of an infrared Light Emitting Diode (LED) on the light emitting side, and a phototransistor on the light receiving side.

When there is an original on the original glass, light beams from the LEDs are reflected by the original and led to the phototransistors. This means that the presence of the original is detected by the presence of reflection (when scanning black image).

[A4 Series]	[LT Series]
Original glass	Original glass
Original	Original

		APS-R	APS-R
APS-3		APS-3
APS-1
	APS-C	APS-2	APS-C
	APS-2	Fig. 6-601

6.6.2 Process of detection of original size

(1)When the equipment is in the original size detection mode, carriage-1 is set at its home position.

(2)When the platen cover is opened, the sensors receive the light reflected from the original and if one of the matrix conditions shown in (4) for original sizes are met, the size of the original is instantly detected.

(3)The output signal from each sensor is input to CPU on the scanning section control PC board to

determine the size of the original. VDD VDD

[A4 Series]

Reflection type photosensor

APS-R

APS-C

APS-3

APS-2

	[LT Series]
		APS-R
		APS-C
CPU	Reflection type	CPU
	photosensor

APS-3

APS-1

APS-2

GND	PWA-SLG	GND PWA-SLG
Fig. 6-602 Original size detection circuit
e-STUDIO3511/4511 SCANNER	6 - 12	November 2003 © TOSHIBA TEC