The film forming control system of the vacuum coating machine can be roughly understood by its name. It should be that the coating machine has a coating system that monitors and controls the coating process during the coating process, so that the coating engineer can be guaranteed and the entire coating process can be smoothly Finish coating.

         The current application methods of vacuum coating machine film monitoring mainly include: visual monitoring, fixed (extreme) value monitoring, crystal oscillation monitoring, time monitoring, and so on. I mainly introduce three kinds of visual monitoring, fixed (extreme) monitoring and crystal oscillation monitoring.

         Visual monitoring is also called direct monitoring, which is to monitor directly through the eyes. Because the color of the film changes due to interference phenomena during the growth of the film, we control the film thickness based on the color change. This method has certain errors, so it is not very accurate and requires experience.

        Fixed value (extreme value) monitoring: mainly adopts reflective (transmissive) optical monitoring.

        Extreme value monitoring method: When the thickness of the film increases, its reflectivity and transmittance will change accordingly. When the reflectivity or transmittance reaches the extreme point, it can be known that the optical thickness ND of the coating is the monitoring wavelength ( Into) an integer multiple of a quarter. However, the error of the extreme value method is relatively large, because when the reflectance or transmittance changes very slowly near the extreme value, that is, the film thickness ND increases a lot, the R/T changes. The more sensitive position is at one-eighth wavelength. 

        Fixed value monitoring method: This method uses the stop point to monitor the quarter wave position of the wavelength, and then the computer calculates the reflectance (or transmittance) of the total film thickness at the wavelength at one time. This is the stop coating point. 

        Crystal oscillation monitoring: The working principle of crystal oscillation is based on the principle that the vibration frequency of a quartz crystal is inversely proportional to its mass. However, one disadvantage of quartz monitoring is that when the film thickness increases to a certain thickness, the vibration frequency is not entirely due to the characteristics of the quartz itself, so that there is a linear relationship between the thickness and the frequency. At this time, a new quartz oscillator must be used. The electrical control part mainly adopts PLC automatic control, that is, first enter the pre-designed program in the PLC, and the main circuit of the processor is connected with the empty driving system on the operation panel. When the switch on the operation panel is pressed, the information is transmitted to The central processing unit analyzes and issues instructions by the central control system to execute and complete actions by the branch.

        The vacuum coating machine is a multi-disciplinary equipment, which integrates the most advanced electromechanical technology in the industry today, control technology, electrical automation, IT technology, refrigeration technology, micro-circuit integrated system, high-voltage control system, mechanical technology, processing technology, photoelectric technology , Optical technology, pneumatic control technology, photoelectric sensor technology, communication technology, vacuum technology, thin film optics and coating technology, etc.