LCD Welding Filter

Second, the structure and working principle of liquid crystal.Liquid crystal is different from the usual solid, liquid and gaseous state of a state, it is in a certain temperature range both liquid and crystal two characteristics of the state of matter, with a regular molecular arrangement of organic compounds, commonly used liquid crystal for the phase of liquid crystal, the molecular status is an elongated rod, the length of about 1 ~ 10nm, under the action of different currents, liquid crystal molecules will do regular rotation 90o arrangement, resulting in a difference in transmittance, so that the power supply is turned on and off when the difference between light and dark. The liquid crystal on the ADF is a driving method that directly applies the driving voltage to the pixel level, so that the liquid crystal display directly corresponds to the applied voltage signal. The basic idea of the applied voltage is to continuously apply an electric field and no applied electric field between the corresponding pair of electrodes, and the difference in transmittance is displayed according to the size of the applied electric field.

Third, the significance of the shading number and related circuits.Shading number refers to how much ADF can filter light, the larger the shading number, the smaller the transmittance of ADF, according to different welding needs, choose the right shading number, can allow the welder to maintain good visibility during work, can clearly see the welding point and ensure better comfort, is conducive to improving the quality of welding. The shading number is a key technical indicator in the ADF, according to the correspondence between the transmittance ratio of ADF and the shading number in the national standard for welding eye protection, the visible light, ultraviolet and infrared transmission ratio of each shading number should meet the requirements of the standard.

First,The welding filter using the liquid crystal light valve is called LCD Welding Filter, referred to as ADF; Its working process is: the arc signal when soldering the arc is converted into a micro-ampere current signal by the photosensitive absorber tube, converted from the sampling resistor into a voltage signal, coupled by capacitance, removes the DC component in the arc, and then amplifies the voltage signal through the operation amplification circuit, and the amplified signal is selected by the dual T network, and sent to the switch control circuit by the low-pass filter circuit to issue a driving command to the LCD driver circuit. The LCD drive circuit changes the light valve from the bright state to the dark state, so as to avoid the damage of the arc light to the welder's eye. The voltage of up to 48V makes the liquid crystal instantly black, and then shuts down the high voltage in a very short period of time, so as to avoid the high voltage being continuously applied to the liquid crystal, damaging the liquid crystal chip, and increasing power consumption. The DC voltage in the liquid crystal drive circuit, whose output is proportional to the duty cycle, drives the liquid crystal light valve to work.

Fourth, the bonding of liquid crystal combinations. ADF's window is composed of coated glass, a double-piece liquid crystal light valve and a piece of protective glass (see Figure 2), they all belong to the glass material, easy to break, if the bond between them is not firm, once the welding solute splashes into the liquid crystal combination, it may cause the liquid crystal combination to crack, will hurt the eyes of the welder, therefore, the firmness of the bonding of the liquid crystal combination is an important safety indicator of the ADF. After many tests, the use of foreign A, B two-component glue, according to the 3:2 ratio method in a vacuum environment after stirring, in the 100-level purification environment using automatic gluing machine for dispensing and bonding, to ensure that the optical characteristics of ADF liquid crystal combination to en379-2003 and its related standard requirements, to solve the liquid crystal combination bonding process.

Post time: May-16-2022