Encoders are pieces of optically opaque material filled with regularly shaped transparent openings or holes. Shaft encoders work in conjunction with a light source and photodetector to determine position and/or speed of a moving object. For instance, you might want to know how fast a motor is spinning? Well you can put an encoder wheel on one end of the motor shaft with regularly spaced holes in it, put a light on one side of it and a photodetector on the other. Every time one of the spinning holes passes in front of the photodetector, the detector will register a pulse. If you know how many holes your rotary encoder has, you can calculate the speed of the motor by counting the pulses of light over time.
Rotary encoders are also used in positioning tables in much the same way, those encoders are long straight strips of metal with many of the same shaped holes arranged parallel to each other in a column.
There are no standards in the optical rotary encoder world, every application is different. Fotofab’s rotary encoder manufacturing process is very well suited to making a large number of very small holes in sheet metal simultaneously. Because we etch our parts chemically using a photolithographic process it costs the same to produce one hole as it does to fill an entire sheet of metal with holes. We are also able to produce shaft encoders with much finer features and hold much tighter tolerances than other manufacturing methods for rotary encoders.
Our tooling engineers have seen everything there is to see in the world of optical rotary encoder design, if you need help with your project or just need a suggestion or two about a feature of your design – feel free to contact us. We can help with your encoder needs.