Design of Control Panel of Automatic Sterilizer

With the rapid development of public health in my country, people's requirements for quality of life are becoming more and more stringent. Good indoor air quality is the most important factor to protect our health. However, due to poor indoor air circulation, a large number of harmful bacteria, viruses, organic or inorganic pollution particles, and toxic dust fill the indoor air, causing serious damage to our health. harm. Therefore, there is an urgent need to design an automatic instrument that can realize the sterilization and disinfection of the air in the living and office environment to meet people's health needs.

1. Design requirements for automatic sterilizers and sterilizers

While the system has efficient and safe sterilization and disinfection of indoor air, it should also have the following functions: the system can be fully automatic for 7 x 24 hours through preset settings; for the convenience of operators, an infrared remote control input function is added; ozone disinfection When it is forced to run in a human environment, it should have the function of automatically shutting down when it reaches the set maximum value; the ultraviolet light can work in an intermittent reciprocating cycle state when it is artificially turned on; in order to increase the effect of sterile air diffusion, it should have a full range of air supply functions; In order to prevent loss of system status and parameters due to power failure, the system should have a memory function.

2. Sterilization and disinfection program selection

Ozone is recognized as a broad-spectrum, high-efficiency fungicide, and using ozone to disinfect ambient air is currently one of the most efficient, convenient and fast ways. However, high concentrations of ozone are very harmful to the human body. It can stimulate the human respiratory tract and cause respiratory diseases; cause neurotoxicity, dizziness and headaches. Therefore, this method of sterilization and disinfection is only suitable for unmanned environments.

The deoxyribonucleic acid (DNA) and nucleoproteins of bacteria and viruses most easily absorb C-band ultraviolet rays with a wavelength of 200-300nm. After the fungus absorbs the ultraviolet energy, it will cause the chain break between the DNA nucleoproteins and cause the bacteria to perish. It has great bactericidal effect on Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus. Therefore this design utilizes ultraviolet ray to carry out sterilization at the same time. However, since long-term exposure to ultraviolet rays can cause damage to human eyes and skin, direct exposure to humans should be avoided while ultraviolet rays are sterilizing and disinfecting. In view of the above analysis, two methods of ozone and ultraviolet light are used comprehensively for sterilization and disinfection. After artificial setting, ozone is used for all-round automatic disinfection in an unmanned environment. In a human environment, the 254nm wavelength ultraviolet rays emitted by the ultraviolet lamp enclosed in the sterilization room are used to sterilize the air circulation, so as to achieve the purpose of indoor sterilization and disinfection. .

3. Design of the mechanical part of the automatic sterilization and sterilizer

The requirements for the machine are simple when the ozone is sterilized in an unmanned environment. It only needs to be able to exchange air. When the ultraviolet ray is sterilized in an environment with human beings, the mechanical part must have a closed sterilizing room, and the air entering the sterilizing room is irradiated and sterilized in a cycle. Because the air flow speed affects the ultraviolet sterilization effect, the power of the ultraviolet lamp should be matched with the air flow in the sterilization chamber during design to ensure the sterilization effect. At the same time, the wall of the sterilizing chamber should have a greater reflectivity of ultraviolet rays to enhance the sterilizing effect. Through experiments, the reflectance of ultraviolet rays is shown in Table 2. Therefore, the sterilization chamber should be designed with surface-treated aluminum as the raw material.

4. Design of control part of automatic sterilizer

The control circuit requires automatic control of ozone and ultraviolet rays, continuous and intermittent work of ultraviolet sterilization in human environments, automatic timing operation of ozone in unmanned environments, and a memory function when the system is turned on after an abnormal power failure. Therefore, the 8-bit MCU chip AT89S52 is selected as the main control chip in order to achieve the logic control of the above functions.

4.1 Input module design

The input module mainly collects the setting signals of people. Here, for the convenience of operation, two methods of 7-key keyboard setting and infrared wireless remote control setting are adopted. Since the AT89S52 chip has sufficient I/O ports, the single-key and single-line control method is adopted here. The timing sampling method is used to receive button information; the remote control input method adopts the combination method of infrared remote control chip LC7461+TL1838, and receives through the discrete interrupt receiving method.

4.2 Output module design

The output part is mainly composed of a display part and a control relay. The display part is composed of 4 LEDs with seconds and 6 status indicators because it needs to display accurate time and working status. In order to reduce the number of MCU I/O ports occupied by LEDs, an 8-bit serial-to-parallel chip 74HC164 is used in the design. Since the time display LEDs need to be dynamically scanned and displayed, a cyclic refresh method is adopted in the program. The output part of the control relay is driven by the high-voltage and high-current Darlington transistor TLN2003AN chip, which respectively drives the ozone generator, ultraviolet lamp group, wind swing motor, fan and buzzer to work.

4.3 Other module design

Because it is necessary to memorize the setting state of the machine in the case of power failure, so as not to destroy the original setting after power on, and continue to work according to the original setting mode, the 2402SerialCMOSE2PROM chip is used in the design circuit to store the parameter state. At the same time, due to the need to start up regularly to realize unmanned ozone disinfection, the HT1380 timing chip is used in the circuit. It is a serial clock holding chip with seconds, minutes, hours, days, weeks, months, and years launched by HOLTEK. The working pressure of the main controller is greatly reduced, and the micro-current power supply of the external battery can continue to keep accurate time when it is disconnected from the grid.

5. Software design of automatic sterilization and sterilizer

Due to the need to sample the keyboard, receive signals from the infrared receiver, display the display unit, control the control unit separately, read and write the ROM chip, read the time of the clock chip at any time, etc., the task thread many. Here, the keyboard and display part are cyclically scanned, the infrared remote control is interrupted, and the output relay, ROM chip, and clock chip are refreshed regularly.

Summarize

The designed automatic sterilizer has been developed into a prototype, and the control function fully meets the design requirements through the 240h uninterrupted operation test. According to the indoor environment, the working parameters are simply set manually. After the operation, the indoor air is sampled and the bacteria are cultivated by the air deposition method 10 times a day. The bactericidal rate calculated by comparing the number of colonies before and after the minimum reaches 97%, and the highest reaches 100%. There is a lot of room for market development.

The above is an example of the design and development of the control board of the automatic sterilizer and sterilizer introduced by Shenzhen Zuchuang Microelectronics Co., Ltd. If you have PCBA development needs for sterilizers and sterilizers, you can trust us. We represent a variety of single-chip microcomputers, voice chips, dual-mode Bluetooth ICs, and wifi chips. Brands include Songhan MCU, Yingguang MCU, Jerry Bluetooth, Ankai Bluetooth, Allwinner, and Realtek. Our technical services include: PCB design, microcontroller development, Bluetooth solutions, software and hardware custom development, APP development, small program development, WeChat official account development, etc. It can also undertake the design of intelligent electronic products, the development of living appliances, the research and development of beauty equipment, the application of Internet of things platform, the smart home control system, the development of TWS earphones, Bluetooth earphone speakers, the development of children's educational toys, the design of electronic education products, etc.