Encoder, High Performance, LED
Tuesday, September 05, 2006
An LED High Performance Encoder has been designed and developed using geometric information between two channels of the encoder to reduce phase sensitivity to mounting position. There are four photodetector per code wheel cycle and each photodetector contributes to both output signal channels. This design feature also assists in reducing phase errors between channels in response to alignment errors. The integrated photodetector subassembly combines light detection and signal processing for both output channels in a single integrated chip. Each point on the photodetector array can only measure light intensity, but the integrated photodetector subassembly, as a whole, is sensitive to the pattern of light and shadows (Moire patterns).
The precision molded polycarbonate emitter lens produces a collimated laser light beam. The lens has a f/n of 0.7 for high efficiency and two aspheric surfaces for controlling collimation and light intensity uniformity. Tight collimation tolerance requires a small point light source. The emitter used is a gallium arsenide phosphide LED radiating from a 60 μm wide active area.
Source: “Economical, high performance optical encoders”, by Howard C. Epstein, Mark G. Leonard and Robert Nicol, Hewlett-Packard Journal, October 1988; Hewlett-Packard, San Jose, CA, Ph 408-435-6344,
Reference: None Available
Industrial Products
posted by JD52 @ 9:31 PM,
