LCD liquid crystal screen is now one of the most widely used display technologies and components. However, in the actual industrial chain, each company or each engineer has different technical opinions on the same problem, and it is often precisely because of this different opinion that it is easy to cause disputes and affect cooperation. Cooperation and production of companies and manufacturers.

The structure of STN and HTN-LCD is composed of upper and lower polarizer, ITO glass and liquid crystal, while the other structures are epoxy resin to form a closed liquid crystal box and bead laying process to control the height of the box. Usually some LCD manufacturers will provide driver IC and voltage divider resistor network to form the driver circuit, plus some necessary backlight and mechanical structure, generally called LCD module, that is: LCM. quite a lot of application engineers only understand the LCM driver circuit interface, but ignore the principle of LCD. At the same time, LCD manufacturers are prone to obsession with the LCD production process and testing methods, for the drive circuit is not enough attention. In this way, and then encounter the very common hidden strong failure phenomenon, often think that the other side of the wrong understanding, trying to convince each other and did not really find the root cause of the failure to give a solution.

The rapid development and revolutionary nature of modern physics has laid a solid foundation for the rapid evolution of electronic components. However, people are often surprised by the new functions of electronic components to become familiar with and seem to take for granted the feeling to enjoy the progress of science and technology, intentionally or unintentionally skipped the basic theory and basic physical phenomena and experiments of modern physics.

From a physical point of view, after passing through the earth's atmosphere, sunlight scatters into light polarized in all directions, and the polarizer passes the light polarized in a certain direction and filters out the rest of the light. In this way, the light entering the LCD liquid crystal cell will be and can only be polarized in the same direction. The two pieces of glass on the upper and lower sides of the liquid crystal cell are respectively distributed with corresponding ITO traces, which form corresponding electrodes for the liquid crystal. Liquid crystals are organic long rod molecules that have both electrical and optical anisotropy. If a voltage difference is established on the electrodes and the liquid crystal molecules are deflected, the light of a specific polarization direction will pass through the liquid crystal molecules to reach the lower polarizer and return to the observer's eyes, and the observer can see the relevant characters or patterns on the LCD. If the voltage difference applied on the electrodes is not enough, the deflection angle of the liquid crystal molecules is not enough, which will affect the amount of light returned, and finally the relevant characters or patterns on the LCD seen by the observer become insufficiently displayed, forming ghost images.

From the perspective of LCD panel manufacturers, STN and HTN type LCDs are difficult to understand due to the characteristics of liquid crystal materials, process limitations such as wiping angle, etc., because of the professionalism and the confidentiality of the production process. It is difficult to make it public, so the industry can calibrate the specifications for LCD users as the viewing angle direction — commonly six o’clock and twelve o’clock, and the driving method is like 1/16duty and 1/5 bias. Duty refers to the duty cycle of the driving waveform, and the horizontal axis is the time axis viewed from the oscilloscope. Bias refers to the bias voltage of the driving waveform. From the oscilloscope, the vertical axis is the voltage amplitude.