Development Of Measure Light Screen In Tyres Inspection

The infrared measure light screen is a kind of special photoelectric sensor, which can be called infrared scan line-array, and has the big size and long tube shape. It consists of the transmitter and transceiver devices, which are separated and opposite from each other. The detecting ray generated by the transmitter device of light screen can come into being a carrier infrared array with the determining deviation along the length of the device, not a bunch obtained from an ordinary sensor. The light screen can monitor and measure the shape and dimensions of the object with the assistance of controller and its software in a scan mode. The light screen is often used in industrial production line control and sorting operations with its simple structure and high resolution features. This paper presents a measuring light screen which is used in automated tire inspection system to measure the inside and outside diameter of the meridian tire. The main works were done as follows.The light screen hardware system was designed based on the core of AT89C52 MCU. It included control panel circuit, transmitter circuit and the receive circuit, which achieved the scanning and logical control, emission and carrier of Infrared, receiving and filtering respectively. In addition to the above-mentioned functions, the R.S-485 and RS-232 interface were extended to realize the serial communication with PC by MCU control circuit. During the design of transmitter and receive circuit, a strobe signal was driven by the strobe pulse and transmitted in series shift register one after another in order to achieve the infrared sequential strobe channel. The system minimized the connections number of the MCU controller board, the infrared emission and receive board, also improved the system stability and anti-jamming capability effectively. The infrared emission and receiving line array was designed based on the cascade structure of series PCB, which had the same length of 254mm, and can be chosen from 1 to 8.At the same time, the range of the measurement can reach up from 254mm to 2032mm based on user parameters and selected Software. The resolution of designed infrared detection light screen can achieve 4mm, and the maximum scanning speed can achieve lOHz as the detecting width was 2032mm through the system debug and optimization.The T0, T1 timer of AT89C52 MCU were used to produce fiver pulse signal to control the scanning process in the software of microcomputer control system. TO as the carrier frequency generator which is used to generate 38kHz carrier infrared. As a baud rate generator T2 timer is used to achieve serial communication. HEX-ASCII is used in the data format of Communication regulation, each frame constitute of identification code and data, check code, support 19200 bits 9600 baud rate.In Windows, imaging software is compiled by the Visual Basic language, which using the serial communication communicate with the hardware of the measure light screens, achieve the function which is the parameters Settings, data processing and mapping features and otherwise. Practice has proved that the method has good accuracy and real-time, and the test results are simple and intuitive.