7 Answers to the Most Frequently asked TFT Questions
1. HOW MANY COLORS CAN A TFT DISPLAY?
TFT (Thin Film Transistor) Displays produce between 64K (64,000) and 64M (64,000,000) unique colors. The number of colors is determined by the interface and the number of inputs. The higher the number of colors, the more inputs (I/Os) needed. The more inputs, the faster the processor required.
Industrial applications tend to choose the 64K option. Medical, aviation and higher end products push for the 64M.
2. CAN TFTS DISPLAY VIDEO?
Most TFTs can display video and are dependent on the speed of their interface.
All TFTs can display letters, numbers and graphics.
3. WHAT INTERFACES ARE AVAILABLE?
- SPI is quick to interface and requires few I/O’s (In/Outs).
- Parallel is popular and fast. Freeware (firmware) available on the web greatly reduces development time.
- LVDS (Low Voltage Differential Signaling)is fast and provides great video capabilities but at a higher price. It is losing popularity to HDMI.
- HDMI (High Definition Multimedia Interface) is the fastest growing and easiest to activate. In most cases, the display will operate when plugged into a computer, tablet etc. No reboot is required. The higher price of an HDMI interface can be a detriment to higher volume production, but great for low volume production runs and development.
There are several types of interfaces available for each display. Some displays can even provide you with more than one interface option.
The faster the TFT’s interface, the faster the processor required.
4. DO TFTS CONTAIN A TOUCH SCREEN?
TFTs use either a capacitive touch panel, a resistive touch panel, or no touch panel.There is no tooling fee for adding a touch panel to your TFT because it is a standard feature.
Resistive touch panel is the most popular due to its low-price and ease of integration, but only allows single touch. Most resistive panels won’t scroll, pinch, or zoom.
Capacitive touch panels are more expensive and offer many features, but only work with bare skin or a stylus. Gloves, pencil erasers, or anything without an inductive load will not work.
A TFT with no touch screen is the least expensive option and provides the brightest display.
5. ARE THEY WATERPROOF?
No, water will damage the TFT. It is best to keep them in a low humidity environment. If your display must operate in or near moisture, you will need to seal it in a case.
6. DO THEY MAKE ROUND TFTS?
Yes. Round TFTs are new and therefore, more expensive. Also, some will require a higher MOQ. Often times, an engineer will choose a square display and place a round cover over it to make it appear round.
7. ARE THEY SUNLIGHT READABLE?
Some are sunlight readable. Most TFTs and tablets are difficult to read in direct sunlight. Two solutions to increase sunlight readability are using a brighter backlight or using a transflective display.
Brighter TFT Backlight
The minimum display brightness for sunlight readability is 700 nits. The brighter the display, the more power it draws. A disadvantage for battery powered products.
Note: One Nit is the brightness generated from one candle. 700 Nits is considered the minimum for sunlight readability. 1K Nits is ideal.
Transflective TFTs are a newer technology. They are easier to read in sunlight because they reflect most of the light to the user. They are more expensive than older transmissive displays.