Key Benefits and downfalls of a segment display
Low Power:
Segment displays require the least amount of power compared to other LCD products, demanding less than 1 Ma and in many cases, a mere 500 uA. A great benefit for products operating on ‘AA’ batteries, solar power, or even watch style batteries.
Low Cost:
- The displays are very simple: ITO glass, pins and nematic fluid. In higher volumes, they can run as low as .25/each.
Fully customizable:
The majority of segment displays for new designs are custom. The engineer/designer determines:
- Over all glass size
Square, Rectangle
- Background color
Grey, Yellow-Green, Blue, Black
- Backlight type (optional)
Blue, White, Red, Yellow-Green, RGB
- Interface type
4:1 Multiplex, 1:1 Static drive, SPI, or I2C.
- Connection method:
Pins or Cable
Low Tooling Cost:
Tooling cost is low, ranging from $1K to $4K.
This is a one-time expense, paid once. Allowing the OEM to order the display over and over without paying again.
Long term availability:
Since the display contains very few components, there is very little chance of your LCD going End of Life or obsolete.
Choice of interface:
Since the display contains very few components, there is very little chance of your LCD going End of Life or obsolete.
The most common interface is 4:1 mux, which means there are four segments for every one pin.
Other options include 1:1 direct drive, one pin for each segment, which provides a sharper contrast and performs better in colder temperature.
SPI is growing in popularity, because it is easier/faster to program but adds cost to each unit due to an attached controller/driver. When adding an IC to a segment display, it is often referred to as a LCD module, where a segment display without a controller is called ‘glass only.’
Fully customizable:
Segment LCDs are only a few millimeters thick, allowing them to be used in handheld or wearable products. It is possible to order thinner glass to reduce the units overall thickness by as much as one millimeter.
Downfalls of a segment display:
Segment displays are monochrome, meaning they are limited to one background color and one segment color. Unlike TFTs and OLEDs that offer multi colors (up to 64M), segments have one choice.
Adding a RGB (Red, Green, and Blue) LED backlight to the LCD is an option. By modulating this combination, any background color can be generated.
Some customers will set the background color to green when certain conditions are met. The background changes to yellow or red or blue or any combination to represent other condition of the equipment or operating environment.
At Focus LCDs, our goal is to make the selection and design of LCDs into new products simple and low-cost.