Design And Implementation Of Thermal Printing Head Detection Device

As a critical component of thermal printer,Thermal Print Head(TPH)realizes the information printing by applying the principle of Joule heating effect and using the Integrated Circuit to control logical signals.Being a specialized and sophisticated component with its complex control logic,TPH can hardly be tested by generic devices from present market.At the same time,no mature solutions are available either.Thus,in order to check TPH either in assembly line or as the end product,it is particularly significant to design and develop a set of integrated testing equipment.In this paper,based on the performance and parameters of TPH,the test requirements are analyzed.Test requirements mainly include two aspects:the first is the testing of short circuit,open circuit,electric leakage as well as current and voltage(IV)characteristic of each TPH input and output terminal and the second is the testing of TPH logic and timing sequence function as well as its heat resistance value.Firstly,through deep research toward the features of TPH,especially the research toward the features of specialized logic control Integrated Circuit(IC),and based on the testing demands,this paper formulates targeted testing plan,which in particular introduces and integrated IV fitting test method to detect IC hidden defects as well as the timing sequence test method from strobe to output to measure IC response character.Secondly,by using specialized IV testing circuit,unique IC function testing circuit and precise constant-current resistance measurement circuit,together with high-efficiency Field Programmable Gate Array(FPGA),easy-to-use ARM processor and stable graphic LabVIEW,this system realizes accurate IV test and stable IC features test as well as precise heat resistance value measurement.Finally,to check the reliability and feasibility of this system,relevant experiment and tests have been arranged accordingly.Tests show that this device makes up for such disadvantages as the simpleness of function and lowness of precision as well as inefficiency and high error rates of the present pick-and-mix TPH testing devices,and improves the capacity to detect defective products.