Research On The Single-ring Absolute Photoelectric Shaft Encoder

Photoelectrical shaft encoder is an angle displacement photoelectrical sensor. It is a digital angle measurement device in which optics, mechanics and electricity are integrated. With photoelectrical technology, the physical measurements such as angle information,line displacement, velocity, acceleration are transformed into electronic signal. The signal is sent to computer to accomplish the dynamics measurement and real time control by compare , magnify, pulse-shaping, correction, subdivision and coding. The encoder is abroad applied in many different fields such as radar, photoelectrical theodolite, avigation, spaceflight, numerical control machine tool, robot, command instrument , high precision closed loop timing system and so on. With the development of technology, the exigent requirement of many fields such as war industry, national defence, autocontrol needs minitype sensor with high precision, high resolution and intelligent. The measurement precision and the size of tradition absolute photoelectrical shaft encoder using moire stripe to measure angle displacement is unable to consist, which can't satisfy with development trend, so we should develop a new type of photoelectrical shaft encoder to meet with the needs.Firstly, based on analyzing and studying the coding mode and coding theory of photoelectrical shaft encoder presently especially Gray code, a new type of coding method is presented in this paper according to the theory of tradition absolute encoder how to gain absolute angle displacement information. The coding method need graduate a single ring on code disc to obtain angle position by special arithmetic. The codes can be given by using VC to program.Secondly, according to the gained codes, a single ring absolute code disc is made by touch photolithographic method. The configuration and the illumination system of single ring absolute photoelectrical shaft encoder whose core component is the code disc are designed, and the receiving system taking μPD3575D liner CCD as receiving component is also offered. The driving circuit of μPD3575D linear CCD is designed based on complex programmable logic device(abbr. CPLD). The driving circuit can provide multifold driving pulses. Results of simulation and experiment indicate that the circuit is simple and its practicability is wide, which prepares to collect signal.