Research On An Acquisition And Process System Of Weak Photoelectric Signals

Weak photoelectric signal acquisition and process is a common issue in industrial automation. This paper using the principle of photoelectric detection to designed a weak photoelectric signal acquisition and process system based on virtual instrument technique. System analyzed and compared the photoelectric conversion circuit and preamplifier circuit, designed a MCU control circuit. The real-time results of photoelectric signal acquisition and process are showed on the PC of man-machine interface in the end. The system can be applied to color sorting machine, through the different gloss detection of moldy or macular in grain of rice. Has the advantages of rapid and accurate, the system can be exploited further, has wide application prospects.The main works completed by the author of the paper include:1,By the investigation of weak photoelectric signal detection and virtual instruments technology research and development situation, on this basis, combined with the subject in the field of practical application of color sorters. Designed a system structure scheme constituted by photoelectric conversion, preamplifier and MCU controller and PC display.2,In-depth studies of the basic principle of weak photoelectric signal detection, adopted photodiode as photoelectric converter devices, improve the traditional photoelectric detection circuit, reduce the noise.3,Chosen the instrument amplifier to design system preamplifier, using the TI Company's integrated chip TLC2262, its high input impedance, and low noise characteristics as the photodiode load circuits. At the same time, using TL064 chip as the second stage amplification circuit, make the weak signal large enough. Posed by the C8051F040 MCU design control circuit, to realize control the signal acquisition and complete communication with the PC.4,Combined with the virtual instruments technology, system used the software of LabVIEW made by NI (National Instruments) to write the man-machine interface, it can realized to display the real-time signal and do some data process such as filter and spectrum analysis.5,Paper has completed hardware design and circuit board production, welded the components. Provided the software flowchart and used the C language to program, written the LabVIEW software in computer. Finally, summed up the whole work and examined the problems met in the process, analyzed the causes of error. The improved design was discussed in the end.