Research And Design Of Temperature Controlling System Of Infrared Therapy Instrument

Nowadays, infrared physiotherapy devices have been applied broadly as an adjunctive therapy to treat many kinds of diseases, the efficacy of which has been confirmed in many clinical case reports. However, if the infrared radiation intensity and irradiation time to patient is not controlled properly, the irradiated sites of patient will be burned. This gives patients many side-effects when received physical therapy.In order to ensure better treatment effect and prevent physiotherapy area of patients from burning, a good temperature control system is neccessay. But most of infrared therapy instrument on the market today do not have the function of temperature monitoring for the irradiated sites of patient. The design of related research, the temperature control system is only for a particular infrared therapy instrument.What's more, some of their design is directly using the industrial infrared thermometer with output interface, and using the output datas of the thermometer sent by data acquisition card to measure and control the temperature. Some of the design is using the switching power on the power control part of physiotherapy. All above make the using cost of infrared therapy apparatus high and the using range restricted. Therefore, the theses of this research are the following:First, this thesis does the research of the temperature measurement and control methods of the several widely used infrared therapy devices. Through the comparison and analysis to the characteristic wavelength of the infrared therapy devices as well as temperature measuring methods, the disadvantages of the contact thermometry method is pointed. The problems that should be noted when using the non-contact temperature measurement to control the surface temperature on the irradiated sites are also given.Second, the temperature control system of the near-infrared and mid-infrared physiotherapy device is designed. In hardware, zero-crossing detection method and silicon-controlled rectifier to control the power directly through AC chopper method are used in this design,which simplifies the hardware design and reduces the cost. Due to the control of the skin temperature of irradiation has following characteristics, such as multi-variable impaction, imprecise model and infrared temperature perturbation caused by non-contact, so the fuzzy PID algorithm is used. Then the response rate and accuracy of stable state of temperature control is high.Third, based on the characteristics of cryogenic burns of patients, we presented a new temperature controlling method which alternately used relatively high temperature and relatively low temperature to treat the patients during the infrared therapy.Experiment results show that this system could avoid burns on patients` irradiated parts effectively, and could set different temperature therapeutic schedule according to the different diseases and different parts of human body.