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Application of photoelectric technology in printing and packaging

with the introduction of a series of new technologies such as optical and electronic technology, packaging and printing technology and equipment are becoming more and more advanced. Photoelectric technology plays an important role in modern printing and packaging technology, including automatic control of packaging machine, electronic plate making and color separation, etc. In order to discuss the application of photoelectric technology in the field of printing and packaging, this paper will discuss the photoelectric detection technology in the process of packaging control and the laser technology in printing plate making

I. photoelectric detection technology in the packaging process

photoelectric detection is mainly measured by photoelectric sensors. The working principle of photoelectric sensor is: the light source produces luminous flux, and the parameters of luminous flux (such as the cross-sectional area of radiant energy flow, spectral components, luminous intensity, etc.) are controlled by the measured object, and then received by photoelectric devices and then transformed into changes in electrical parameters for measurement. Different light sources can be used in different working environments, such as incandescent lamps, lasers, light-emitting diodes, etc. Sometimes the controlled object itself is the signal source, such as the mark line on the packaging bag

due to the weak signal detected directly and the lack of stability, the amplification and shaping circuit is often added to the control circuit to improve the practical operation ability of the system. Measuring institutions include indicating instruments, alarms, digital displays and product sorting devices, which display the relevant measured values of products or automatically classify products. Usually, in order to automatically adjust the production process so that the controlled quantity remains unchanged or changes according to some laws (such as realizing the automatic adjustment of the cutting position of packaging bags), a feedback circuit needs to be added to the circuit

photoelectric detection system has the advantages of simple structure, long detection distance, high precision, fast response speed, long service life and so on. It has its unique advantages in pattern recognition. It can realize non-contact detection without force and torque acting on the measured object. Even if the measured object has a large impact, it will not damage the detection instrument. Similarly, for some products with high requirements for packaging manufacturing process, such as food, pharmaceutical extrusion and calendering parts, which account for about 10% respectively, the non-contact feature can be used for measurement when counting

photoelectric detection circuit is composed of electronic components or integrated circuits, with low cost and high sensitivity, which can realize rapid measurement, objectivity of indicated value, etc., and is easy to automate. With the development of computer technology and mechanical industry, it can realize the combination of light, machine and electricity, calculate and process data, check, logical judgment, storage, etc., so as to realize the adjustable and synchronous supply of precision in the packaging process

to illustrate the problem, here is an example of position detection and positioning in the process of automatic packaging control:

due to the continuous reduction of the drum radius during the packaging operation, the tension of the packaging paper changes, and the friction coefficient between the paper feeding roller and the packaging paper fluctuates according to the influence of the temperature and humidity of the information environment of the Zhejiang People's government station, plus the trademark printing error and the differences of paper feeding, longitudinal sealing, cutting, etc, Make the actual tangent of the knife roll deviate from the specified position. Although the error each time is very small, due to the long-term accumulation of high-speed operation of the machine, it will lead to serious deviation of the tangent, reduce the packaging quality, and even cause waste products. Therefore, it is necessary to add automatic photoelectric positioning detection and control equipment to the system

the photoelectric detection and positioning system uses photoelectric tracking to detect the positioning color code on the packaging paper. By comparing the error between the paper feeding speed and the transverse sealing cutting speed, it outputs the corresponding control signal to promote the automatic positioning of the actuator or error compensation. In order to detect reliably, it is required that there is a significant difference between the positioning color code and the background color of the packaging paper. The greater the contrast, the more sensitive the detection is. The color code requires bright color, uniform printing ink and a certain area. Generally, the color code is rectangular, and the length and width should have an appropriate proportion. Photoelectric detection can be divided into transmission type and reflection type according to the different materials for clearing at the packaging time. The transmission type is used for the detection of transparent materials, and the packaging materials pass between the transmitting head and the reflecting head. In this way, even if the packaging materials bounce during the feeding process, it will not affect the detection sensitivity, and it is not easy to be disturbed by the ambient light. The transmitting head and the reflecting head of the reflective type are in the same direction, and it is required that the condensing beam form a focus on the packaging material or the reflecting plate, so the packaging material is not allowed to have a large jump when passing the testing part. According to different packaging forms and packaging requirements, there are different photoelectric detection and positioning devices used in packaging machines for feeding, bag making, sealing and cutting

Second, laser technology in printing plate making

laser is a new discipline and high-tech. since its birth in the early 1960s, it has been valued and developed rapidly all over the world. As a result, the application scope of laser has been continuously expanded, and many corresponding fields have undergone profound changes. The printing industry around the world, like other industries, is also actively adopting this new technology. Laser is used in electronic plate making and color separation, laser Phototypesetting, holographic printing technology and so on, and greatly optimizes the printing system. Limited by space, this paper only discusses the application of laser in plate making. Printing plate is an indispensable part of the printing process. It is the medium that transfers ink to the substrate. The quality of printing plate is directly related to the quality of printing products. The printing industry has been trying to improve the plate making process in order to make the printing plate as fast and as best as possible, while reducing labor intensity and plate making cost. In the early stage, the production of gravure, embossing and offset printing plates mainly depends on manual, mechanical, chemical corrosion, electric photography technology, etc., but these methods have defects such as lack of operational stability and long plate making time. These problems have been solved since the birth of laser. Using the high intensity, high coherence and monochromaticity of laser, printing plates can be produced quickly and reliably

laser engraving plate is to shoot the focused laser beam to the plate, melt the specified range of the plate, and then remove the unwanted parts to produce convex and concave images. The shape, size and size of the image can be controlled by electronic modulation. Generally speaking, when the power density of the laser reaches 10 low/cm, the plate making materials (including ceramics) will melt or vaporize, and the power density value obtained at the focus of the medium intensity laser beam after focusing by the lens is far greater than the above value, so the laser is more suitable. 6. Press the key switch to close the engraving plate. Because of its monochromaticity, high energy and good coherence, laser has shown strong advantages in engraving and plate making, especially the development and application of modern violet laser technology, which makes the plate making more perfect. Laser has high intensity, which can not only melt and etch non-metallic materials (such as imaging film, photosensitive resin plate and plastic plate), but also melt metal materials (nickel, lead, steel, chromium and other plates). It can even etch ceramic rollers with high fire resistance, and other methods

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