Design And Research Of Thermal Transfer Label Printer Testing System Based On Virtual Instrument Technology

With the development of information technology, the market of thermal transfer label printer is gradually expanding, which is widely used in business retail, express logistics, insurance companies, the law enforcement, etc. The structure of thermal transfer label printers is different from traditional thermal printers'. The special design of the software and hardware, the high requirement of feeding speed and printing accuracy, are the most important and necessary parts to make a fast and accurate online test for thermal transfer label printers, which are the key parts to guarantee the quality. The efficiency of most traditional manual test technology for thermal transfer label printers is much lower, so it is difficult to be real-timely implemented and hard to be used in the practical applications. How to design a set of automatic and efficient testing system for thermal transfer label printer has become an urgent requirement in the engineering practice, which has a practical value in production practice.Firstly, the domestic and foreign development of thermal transfer label printer and the testing technology in recent years are analyzed in this thesis. Then it has a comprehensive study on the working principle of thermal transfer label printer, making it clear about the test items and performance requirements. So this thesis designs the testing system for thermal transfer label printer combined with virtual instrument technology. The whole testing system mainly includes circuit board functional testing and integrated testing of the thermal transfer label printer. The functional testing includes software and hardware design. It focuses on the main electric control parts of the printer: the keyboard, indicator light and main board, making an analysis respectively, and separately designing the testing plan, completing the design of testing program and debug at last. In addition, through the analysis of different image quality evaluation method, a new image quality assessment method for printed QR code is proposed to achieve the integrated testing. After analyzing the QR code structure characteristics, and making the quality assessment from 5 aspects: referenced decoding, symbol contrasts, modulation ratio grade, inherent stains, and axial inconsistencies. This thesis at last completes the functional tests and integrated tests for thermal transfer label printers on the Lab VIEW platform.Finally, this thesis conducts some experiments and verifications on the testing system. The experimental results show that testing method based on virtual instrument greatly improve the test efficiency, and the testing time is about 3.75 minute. In addition, the testing results for the image quality assessment method shows those are consistent with subjective assessment based on human eye vision, which can effectively ensure the accuracy for the integrated test.