Linear Optical Encoder From Epson Stylus CX7400

Other Hardware Sensors
1

Hi everyone,

I'm working on a low-resolution XY-table and I was hoping I could pull some parts from an old Epson Stylus CX7400 I had lying around.

I was hoping to use the linear optical encoder on the print-head, but I think I might be doing something wrong. The numbers on the sensor are "E 18 7814" (Googling has gotten me nowhere). The encoder board has 4 pins (the actual sensor had 6, but they've connected power and GND), and I believe I've figured out +5V, GND, CH1, and CH2 (when I connect +5V and GND, the LED turns on) however I'm getting some tricky values out of the CH1 and CH2 pins. CH1 always reads 0V regardless of if I have something in the way of the sensor or not (I will admit it's possible I damaged the sensor while determining the pinout), and CH2 reads ~0.10V when the sensor is unblocked and ~0.23V when the sensor is blocked. I was thinking I could build a Schmitt Trigger with a cutoff voltage of 0.15V to convert this to digital logic, but it seemed to me that it would be logical for the sensor to already do this (all the other similar sensors I found online did), which would imply I'm doing something wrong. Am I missing something here? Or should I just give it a try with the Schmitt Trigger?

Thanks,
Kyle

2

The outputs are likely open-collector or open-drain - you should try connecting a 10k resistor from each one to 5V, and then looking at what they output.

3

That was it, thank you very much. A couple of 10K pull-ups and things started looking saner.