In today's digital age, a simple and efficient display technology still silently supports the operation of countless daily electronic devices, which is segmented LCD display technology.

From home appliance control panels and electronic watches to digital reading screens for industrial equipment, segmented LCD has become an ideal choice for embedded systems and simple display requirements due to its low power consumption, low cost, and simple driving. This technology is maintaining its place in today's high-precision display field through continuous innovation.

Segmented LCD, also known as segmented LCD screen or patterned LCD screen, is a general term for non dot matrix LCD products that use pen segment display technology.

Its name originated from the early application of LCD screens, mainly used to replace LED digital tubes. The most basic 7-segment digital display can show numbers 0-9, similar to the display on calculators and electronic clocks.

Unlike common dot matrix displays nowadays, segmented LCD displays have fixed content and are composed of pre designed pen segments (such as numbers, letters, or simple symbols).

These pen segments are very flexible in arrangement and shape, not only can they be made into the common "8" shape, but they can also be made into any shape, including company logos, various patterns, and text.

The driving core of segmented LCD is based on "scanning" or "time-division multiplexing" technology, utilizing the "visual persistence effect" of the human eye to achieve stable display.

The segment code LCD is composed of a matrix structure consisting of multiple intersecting "common terminals" and "segment terminals". Liquid crystal material is sandwiched between two transparent electrodes, and its transparency is changed by applying voltage - when there is no electric field, the arrangement of liquid crystal molecules allows light to pass through, displaying the background color; When an electric field is applied, the liquid crystal molecules deflect, blocking light and displaying dark colors.

Liquid crystals have a key characteristic: they must be driven by AC voltage, and DC voltage can cause electrolysis and permanent damage to the liquid crystal material. Driving an LCD requires generating precise square wave signals to ensure the correct phase relationship between the display and non display segments.

The driving of segmented LCD is divided into two types: static driving and dynamic driving.

Static driving is suitable for COM terminals with few or simple displays. Each segment is independently connected to a driving pin, which is easy to control and flicker free. However, it occupies a large number of pins and is only suitable for a small number of segments.

Dynamic driving is suitable for multi segment displays, such as calculators and electronic watches. It groups segment electrodes and scans different COM terminals in a time-sharing manner, utilizing the persistence effect of human visual perception to achieve stable display.

For example, the 4COM driver divides the screen into 4 groups and alternately activates each group of COM. The advantage of this method is that it can reduce the number of pins, but the disadvantage is that it requires strict timing control.

The dedicated driver chip greatly simplifies control complexity by incorporating multiplexing logic and LCD voltage generation. These chips can communicate with microcontrollers through SPI/I2C, greatly saving MCU pin resources.

The most significant advantage of segmented LCD is its extremely low power consumption, making it suitable for battery powered devices. The driver chip such as HT1621 can drive up to 128 pen segments, equivalent to 16 "8" characters, while the interface is only a few serial pins.

Compared with other display technologies, segmented LCD is still clear and visible under strong light, with low cost and simple driving.

However, the limitation of segmented LCD is that its display content is fixed and cannot dynamically update any graphics. This makes it unsuitable for scenes that require displaying complex graphics or changing rich information.