Large character LCD display modules explained
Larger character LCD displays are necessary for products that must be readable from a distance, such as a security alarm panel or sprinkler timer.
Before continuing, please check our online store (how to create a link so it opens on a different tab?) for standard, off the shelf LCDs that might fit your design. Standard LCDs have no MOQ and are in stock, so we can ship the same day you order.
If you don’t see what you need, we can custom build the unit you need.
Overview of large character LCDs:
Character LCDs are monochrome, meaning they have one color background and a different color character. Below is a photo of a 16×2 display with yellow/green background, yellow/green LED backlight and black letters.
You choose the background color and character to fit the needs of your new design.
Key advantages of monochrome displays are their ability to perform well in direct sunlight and capacity to operate with as little as 1mA of current (backlight is off).
I need a large character LCD:
If you need a larger display than our standard offerings, we can custom build a character display to meet your specs. Below are the available options.
Overall size of display:
Choose the size (also called viewing area) of the glass you want. Focus will calculate the size of the PCB. In the image below, the size of the viewing area is 120mm x 23mm.
Number of characters and rows:
A character is a small box that can display any letter, number, or punctuation mark. See image below:
The number of characters categorizes character LCDs they contain. An example is the16x2 in the drawing below. There are sixteen (16) characters across and two (2) rows for a total of 32 characters.
Common character configurations include:
8×1,8×2,16×1, 16×2, 20×1, 20×2, 40×2, 40×4
Size of Characters
Choose the height and width of each character. The character below is 15mm tall by 6mm wide. If you don’t know how tall and wide you need, just tell us the overall glass size, we will calculate the largest possible character size that will fit.
Choice of polarizer
Polarizers come in three flavors: reflective, transflective and transmissive.
Reflective:
As its name suggest, it reflects 100% of the sunlight, making it the best option for sunlight readable displays.
If you need to read the display in the dark, we can add a side lit LED. The challenge is that there may be hot spots near the edges of the LCD glass where the LEDs are located.
The larger the character LCD, the darker the center of the display, since it’s away from where the LEDs are located.
A diffuser can greatly reduce hot spots. Also, white LEDs are very bright and prone to create hot spots on a side lit module.
Transmissive:
Transmissive displays do not reflect back any sunlight, but produce the brightest backlight. The backlight must be on for the display to be readable, an issue for battery powered products.
Transflective:
A hybrid or mixture of reflective and transmissive. It works well in direct sunlight and allows a backlight that can be readable at night.
If you don’t know which way to go, choose transflective. There is no difference in price or lead time for the three options.
Cold weather operation.
Monochrome displays contain a twisted nematic fluid that freezes as temperatures drop. The result is a slower response time.
This takes place somewhere around -20C to -30C. This low of temperature will not damage the display, but it will no longer operate until warmed up.
One solution to avoid the freezing is to add quarter watt resistors to the PCB, placing them next to or just under the LCD glass. The resistors generate enough heat to keep the fluid moving (think heat tape on water pipes in the winter).
The down side to LCD heaters is power drain, demanding a higher current than the display itself. Low power draw is a design issue for battery powered products. We suggest keeping the resistor circuit, independent of the LCD driving circuit.
Custom size PCB
We will choose the size of the PCB necessary to support the glass and bezel and other components of the display. But if you need the board to be larger or shaped differently, we can tool up to build the board to the dimensions you need.
One customer had us round the corners of the PCB to fit within their case.
There is a small one-time tooling fee for a custom PCB.
Cable:
Most character LCDs contain plated through holes in the PCB for mounting to a .1 spacing header. See image below:
To reduce production cost for the customer, Focus Displays can add a cable to connect both LCD signal and the LED backlight. Let us know the type, length, and location of the cable.
Many customers prefer a separate, two-wire cable for the LED backlight. Red and white colors are standard to identify positive and negative voltage. The backlight cable can be attached to pins: 15&16 or the A&K on the side of the PCB.
It is possible to power the backlight through pins 1 and 2, but not recommended.
Backlight options
Let us know what color of backlight you want. Available options include: blue, white, red, yellow/green, pure green and others. Another option is RGB (red, green, blue), allowing you to change the color via software/firmware.
The backlight’s brightness is increased by reducing the value of the current limiting resistor. Warning: higher currents reduce the LED’s half-life.
LED backlights have a standard half-life of 70K to 90K hours at normal operation.
Note: Half-life is the amount of time before the backlight is half as bright, or 50%, of its original brightness.
MOQ
Our MOQ (Minimum Order Quantity) for a custom character LCD depends on the glass size. The larger the display, the lower the MOQ. Count on a 250 to 500 MOQ for a large character LCD.
What’s next?
Ready for us to build your large, custom character LCD?
Send us over a sketch of the display you want with the following information:
1. Overall size of the display
2. Number of characters and rows
3. Size of each character (or ‘just make it as large as possible to fit’)
4. Backlight? (Y/N)
5. Does this need to be readable at night?
6. Estimated usage
LCDs made simple®
Have questions about Character LCDs for your next project? Contact us today!