The Research Of A Method Of Photoelectric Encoder Entire Code Channel Detection

Photoelectric encoder is a digital goniometer device as a combination of optical,mechanical, electrical, using coded disk as the detection devices, by virtue of goodfeatures and merits such as small size, light weight, high resolution,it plays anincreasingly important role in the aerospace, automatic measurement and CNCmachine tools and other fields. In recent years, with the rapid development of China’saerospace industry, the demand of encoderis increasing, as a key technologyofphotoelectric encoder-the manufacturing of encoder disk, the quality of encoderdisk directly affects the accuracy of detection. However, due to restrictionof encoderdisk scribing process, it is often defective,for example, code channel of encoder diskwill have bright or dark spots, error of phasedifference among code channel is toolarge, and so on. Aimed at this situation, the detections methodssuch as, phasecomparison method, the two-step methods are used. These methods are complex anddifficult to achieve. In view of this, we propose a new detection method for codechannel of encoder disk, which has important significance of improving the detectionefficiency of photoelectric encoder and reducing manual operations.Based on the reference literature, we find andanalyze the characteristics ofexisting optical encoder detection equipment. Aimed at encoder GBJ280, which hasthe encoding scheme for the Gray code, we design a code disc defect detection system.Then we analyze the process of design for the method, and it is described the systemwhat consists GBJ280encoder,data acquisition card and a computer.Firstly, for the data acquisition circuit, the analog part is mainly usedtopreprocessthe original signalofcode channel: signal of precise code is amplified andsubdivided into eight segments using segmentation method of phase shift resistorchain, and then changed an effective square wave with combinational logic andshaping; signal processing section of the secondaryfine and coarse code is similar tothe processing sectionof amplifying and shaping into a square wave signal.Secondly,count, data caching, and data transmission module are designed using XC2S50as the core device, FPGA programmingis completedwith VHDL language, and has beenvalidated in the timing simulation. It is accomplished transiting from ISA bus to thePCI bus with PCI9052, and use tools to complete the driver of PCI bus and PCI9052configuration and programming implementation.Thensoftware design interfaceis programmedwith VC on the PC and the datadisplay is achieved.Finally, detecting data for code channel of encoder disk is analyzed andcalculated to determine the location of light or dark spots on the code channel and thephase difference among code channel, compared with the theoretical analysis andcalculation, the deficiency of encoder discis pointed out clearly. Detection device ofthis method is not complicatedto achieve digital automation of detection method. Butthere’re stillsome deficiencies, further improvement is necessary in order to meet theneeds of modern industrial technology.