Study Of Laser Marking Two Dimensional Barcodes On Fruit Surfaces

With the increasing attention to food safety, it is necessary for us to track the fruits.Presently, the most widely used method is to stick paper label to the surface of fruits.However, the adhesion strength of the paper label is unstable. Some of them are easy to fall off, causing the loss of information, and some of them bring trouble to consumers because of the difficulty of removal. To address this problem, laser marking of two dimensional symbols on the surface of fruits becomes a new research hotspot. In this paper, we used banana, grapefruit, and kiwi fruit as the research samples. The following five aspects has been studied:the effect mechanism between laser and fruits, effect of laser processing parameters on barcode quality, the durability of the barcode, the reading rate of the barcode,andand a quality prediction model based BP neural network:First, we analyzed the characteristics of laser. Then we studied the laser biological effect on fruits according to the characteristics of laser and fruits, and determined three effective methods of reading the bar code marking.We studied the influence of single factor processing parameters on the processing quality of laser direct marking DM barcodes on the surface of fruits by using CO2-S100XP laser. We also analyzed the effects of laser power, marking speed and line spacing on the processing quality of barcode (barcode contrast and marking depth).The results of the experiments showed that laser power, marking speed and line spacing are the main factors affecting the quality of the barcode.We studied the durability of DM barcode experimentally and analyzed the changes of fruit skin and recognition rate of DM barcode in the process of storage. The effects using fruit preservatives and preservation packages in the marking area on the durability of DM barcode was discussed. The results showed that the marking barcode remained its favorable durability under the optimal parameter combinarion. Also, its durability can be enhanced via adding fruit preservatives and preservation packages.We studied the factors including size of DM symbol and the fruit curvature that affect the recognition rate of DM bar code on fruits surfaces. Methods that can improve recognition rate was explored, such as using coloring agents in the marking area.A contrast prediction model of marking barcodes based on the BP network was established. The BP network was trained and tested with different samples. The testresults showed that the network has high accuracy in predicting symbol contrast, verifying the feasibility and effectiveness of the prediction model. The BP quality prediction model can be reliably used to select laser processing parameters in the actual machining process.