Character LCDs, or alphanumeric displays, can display letters (capital or non-capital), numbers, and punctuation. You can find this type of display in products such as vending machines, 3D printers, data loggers, etc.
Most of Focus LCDs’ character lcds are equipped with a built-in driver. The driver contains a character table that is preloaded with letters, numbers, and punctuation in a particular language, allowing for easy programming. The character table eliminates the need to spend time programming each character. Focus LCDs’ standard character LCDs all use an English font. However, upon request, an alternative driver with a different language can be used.
If you have to display more information than the LCD allows when static, it is relatively simple to program the LCD to scroll text. A related application note can be found here: https://focuslcds.com/how-to-scroll-text-on-a-character-display-fan2201/
Easy to Replace Discontinued Character LCDs
One benefit of character LCDs is that they have a lower probability of being discontinued in comparison to newer, more complex display technologies. However, all displays are eventually discontinued at some point in time.
The good news is, it is relatively simple to develop an equivalent or close to equivalent replacement character LCD. Often times, Focus LCDs can produce direct cross overs for your discontinued character LCD and support it for many years.
If it is the driver that has gone EOL, you won’t have trouble finding a close replacement. Most of Focus LCDs’ character LCDs use driver ST7066 or equivalent. A comparison is made between 4 common character LCD built-in drivers in our LCD resource Character LCD Controller Compatibility ST7066. This resource can be found here: https://focuslcds.com/character-lcd-controller-compatibility-st7066/
It is important to note that while you won’t have trouble finding a close replacement driver, considerations must be made in regard to your product’s firmware. It is always advised to test samples before deciding on a replacement display.
Low Power Consumption
Character LCDs typically consume less power than displays such as TFTs. Focus LCDs’ standard character LCDs come in 5V or 3.3V. The latter voltage is low enough to be powered by two double A batteries - perfect for low power or mobile devices.
LED backlights are a considerable source of power consumption on an LCD module. If power consumption is a major concern, and the environment of usage is well-lit, you should inquire about a character LCD that utilizes a reflective or transflective polarizer, eliminating the need for a backlight. This in turn significantly decreases power consumption.
You may be out of luck if your product requires a low power display and the environment of usage is not well-lit. In cases such as this, it is possible to implement pulse width modulation to dim or brighten the backlight as necessary. When the backlight is dimmed, it will draw less power. If pulse width modulation of backlights is of interest, an application note can be found here: https://focuslcds.com/dimming-the-backlight-using-pwm-fan9203/
Character LCD Variations
As with all monochromatic LCDs, you are limited with your character LCD options in regard to colors. Positive mode character LCDs have dark pixels and a light background, while negative mode character LCDs have light pixels and a dark background.
When we refer to the background color, it is important to note that the background does not actually have a color. The background appears to be colored due to the color of the display’s nematic fluid. Below are common liquid/mode color combinations:
FSTN Positive – Gray background, black text
FSTN Negative – Black background, light text
STN Positive – Gray/Yellow background, bluish-black text
STN Negative – Blue background, light text
Negative mode displays require a backlight to be read. The color of the light text on a negative mode LCD is dictated by the color of the LED backlight. For example, a red LED backlight will shine through the light text and make it appear red.
Focus LCDs’ standard character variations range from 8x1 to 40x4 characters and have several different models for each variation. If a unique character variation is needed, inquire about a custom character LCD through our contact form here: https://focuslcds.com/contact-us/
Like all displays, character LCDs have a specific purpose. Even with their limitations, they are more practical for some applications and carry their own benefits. Character LCDs are a great option for your project if you:
- Require low power consumption.
- Need to display letters, numbers, and punctuation only.
- Want to make programming easy.
- Are on a budget.
Because they are so common and have existed for decades, Focus LCDs has a robust standard character LCD line with most parts kept in stock. Samples can be purchased directly through us, or through one of our many distribution channels.
Not sure which display will best fit your project? We can help with that too. Contact us today for recommendations from our LCD experts.
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