Optical Sensor Control - Epson WF-7525 Service Manual

Epson WF-7520/7510/7010 series

2.3 Optical Sensor Control

WF-7520/7510/7010 series uses the optical sensor to control itself. The following describes the operating
principles of optical sensor control.
Control method
To ensure accurate printing, each part must be controlled to make an adequate amount (time) of movement. The
optical sensors read the amount (time) of movements as follows to printer to control it for achieving accurate printing.
1. Rotates the motors for control of the printer, and transmits drive force to the each part via the gear or the
timing belt.
2. The encoder reads the drive amount of each part from the scale one by one to printer to monitor that the part
drives for an adequate amount (time).
Controlled parts
The following table lists where the optical sensor control is used.
Item
PF/ASF (1st cassette)
CR
*2
ASF (2nd cassette
*3
ADF
Note *1: See Fig. 2-1 (p22)
*2: WF-7520/7010 series only
*3: WF-7520/7510 series only
Operating principles
The following describes the PF drive control as an example of the actual operation for the optical sensor.
The PF scale consists of light-passing and light-blocking portions on its surface, and runs through the slit between
the encoder's light-emitting and light-receiving devices. While the printer is operating, the encoder always emits
light from light-emitting device toward the light-receiving device, and the light-receiving device detects light when
the light is transmitted through the light-passing portion of the scale, and does not detect light when the light is
blocked by the light-blocking portion of the scale. According to the counts of light-detected and non detected times,
the printer controls paper feed drive direction and amount.
When the encoder cannot read light-emitting/blocking counts correctly due to the misalignment, broken or
contaminated scale, paper jam, foreign object and increasing a load, the fatal error occurs and the printer stops.
PF Encoder
Without cover (light-emitting
and receiving devices)
PF Scale
Operating Principles
Table 2-5. Controlled Parts
Motor
PF Motor
CR Motor
) Pickup Motor
ADF Motor
and Fig. 2-2 (p23) for the positions of the parts.
With cover
PF Encoder
Light passes
Light does not pass
Figure 2-5. PF Drive Control Section
Optical Sensor Control
*1
Scale
PF Scale PF Encoder
CR Scale CR Encoder
Pickup Scale Pickup Encoder
ADF Scale ADF Encoder
Left side of Printer Mechanism
Encoder Transmission method
PF Timing Belt
CR Timing Belt
Gear
Gear
PF Timing Belt PF Motor
Revision A
25