Segment code LCD or segment code LCD screen is just a way for users of LCD screens to call a certain type of LCD screen, but in the LCD industry, it is generally called patterned LCD screen to distinguish it from the point. Array LCD screen, so segment LCD screen is not a very strict expression or classification. The name of the segment code liquid crystal originated from the early application of the LCD screen, which was mainly used to replace the LED digital tube (it is composed of 7 pen segments, used to display the numbers 0-9), such as calculations Basically, the contents displayed on the devices, clocks and watches, etc. are numbers and relatively simple. Nowadays, non-dot-matrix LCD screens are generally collectively referred to as segment LCD screens.
Classification
LCD is divided into types: TN type LCD, HTN type LCD, STN type LCD, FSTN type LCD and many other types, relatively aligned with the pixels of the dot matrix LCD screen, and the pixels of the segment LCD screen. It is free in arrangement and appearance. The most common one is similar to the "8" field of a digital tube. An "8" is composed of 7 strokes, that is, 7 pixels. The "8" in the "M" font is composed of 16 pixels. Of course, the pen segment of the segment LCD screen can be made into any shape, as long as the driving capability of the driven chip permits. For example: the company's logo, other patterns, text, and so on.
The production price of liquid crystal materials is relatively low. The driving cost of the segment LCD is also very low, and the more classic HT1621 series chip is a good choice. HT1621 can drive 32x4=128 strokes, which is equivalent to 16 "8" characters. The interface of the HT1621 is serial, with CS, WR, RD (RD can also be omitted), and DATA. The HT1621 can also drive a buzzer, which can emit sounds with high and low frequencies.
working principle
TN-type LCD screens usually have three modes: full-transmission, semi-transmission, and reflection. The liquid crystal will not actively emit light, and it needs to be externally provided with a light source. The light source of the transparent liquid crystal comes from behind the liquid crystal; the light source of the reflective liquid crystal comes from the front of the liquid crystal, which is reflected by the polarizer of the liquid crystal screen, and then reaches the observer's eyes; the semi-transmissive liquid crystal is between the two In the meantime, there is both light from behind the liquid crystal and reflected light from the front. Therefore, the transparent liquid crystal requires the use of a backlight, the reflective liquid crystal does not require the use of a backlight, and the semi-transmissive liquid crystal can use a backlight or not. It is impossible to observe the display in the dark on an LCD screen that does not use a backlight.
Segment LCD has several major characteristics such as low price, low drive cost, simple operation, free format, etc., so it has also been widely used. Such as the following fields: *Instruments, meters: gas meters, water meters, bus systems, fuel dispenser counting--*Display office equipment: fax machines, punch cards, attendance machines, access control systems--*Communication equipment: various IC cards Telephone, Internet phone, IP phone--*Banking system: POS machine *Tax system: tax control machine--*Medical equipment: physiological monitor and various health care equipment--*Industrial control equipment: automated control--*Various man-machine interfaces, Handheld devices, etc.
