| With the development of the industrial automation, the color has already gradually become the important foundation or index for the quality of a lot of products. With the correlative theory of color measurement and the comparison of classical color measurement methods, this paper determines to adopt the latest digital computer technology, and the combination of the theory of color measurement and modern industrial controlling theory,to design an online color measurement system with high precision, good stability, strong anti-jamming, and low cost, metting the requirement of online color measurement.This paper adopts a type of latest light source, the fourth generation"green light source"- white high light LED as light source of system. And this paper analyzes the characteristic of white LED, designs constant-current drive circuit, so that guaranteeing the quality of light. For decreasing the disturbance of environment, fully collecting signal and raising sensitivity, this paper adopts and designs Y type optical fiber probe to send and receive spectrum signal. For the structural setting of light source and phototonus element, this paper adopts compact settings.This design chooses MTCSiCT three element color sensor of German MAZeT to transform photoelectricity, and rationally designs the photoelectricity change-over circuit and the signal mu-circuit. The design adopts enhanced RISC and high capability 8 bit single-chip micro-computer AT90S8535 to control the system, and digital potentiometer X9241 and single-chip micro-computer AT90S8535 compose closed loop circuit to program amplifying gain, which adjusts system to get the best amplifying gain as the case if it is best for A/D conversion. High speed A/D converter converts intensity and three color analogical signals to 12 bit digital signal separately, and then high analytic algorithms are adopted to manage 48 bit digital quantity. Considering the effect of intensity eliminates the measurement error, which is produced by the variation of distance between the sensor and the object to be checked. So the measure speed of the color sensor is very quick,and it has higher accuracy and stabilityThe output adopts two types: one is 4×PNP or NPN open-collector output, which can be connected with PLC, especially suitable for industry on-line color detection. The other is RS 232 serial communication interface, which can be connected with PC to display the value of color by software. About the software of color detection, this paper especially increases the function of setting tolerance of color, and improves practicability.Finally, the stability, drift and accuracy of the system are evaluated, and the detected result, and propounds the possible improvements of the system are analyzed and discussed. This paper offers references to the further research on similar photoelectric measurement. The on-line color recognition system has good expectation of pr actical use, which is suitable for industry on-line color detection and large scale using. |
