Thin Film Transistor Introduction

Thin Film Transistor Introduction
March 16, 2017 Eric Hawkins
In Journals

Thin film transistor / TFT displays are the most popular type of color display. They technically are not a LCD (liquid crystal display) since they do not contain any liquid, but are operated with LEDs (light emitting diodes).

They can be seen in such products as TV’s, tablets, digital photo frames and older cell phones.

BENEFITS AND USE

Thin film transistor displays are a full color modules that can display graphics, characters and video and are great for adding an interesting user interface to any product.

Thin Film Transistor Advantages:

  • Can display up to 64 million colors
  • Operates down to -30C
  • Available sizes from 1.7” to 15”
    • Larger and smaller thin film transistor sizes are available, but not standard stock inventory
  • Active and passive matrix options
    • Active matrix technology is used on larger displays that require a faster refresh rate and provide a sharper image.
    • Passive matrix technology is used on smaller displays where each pixel can be refreshed in a cycle.
  • Wide viewing angles
    • Since there is no fluid, thin film transistor displays are readable from a greater range of rotation.
  • Multiple interface options (RGB, LVDS, Parallel)
    • RGB is the lowest cost and requires more computing power from the customer’s processor.
    • SPI (Serial Peripheral Interface) is becoming more popular.
  • Parallel is the most popular interface for displays less than 10.1 inches.
  • LVDS (low voltage differential signal) provides an ultra fast communication and refresh rate necessary for larger displays. LVDS is more expensive than other types of bus, such as RGB and parallel.
  • Larger than current OLEDs
    • At this time the largest OLED (organic light-emitting diode)  available for mass production is the 4.3”. There is a 5.3” under development.

Thin Film Transistor Disadvantages:

  • Thin film transistor displays can be power hungry
    • TFT modules can only be read when the LEDs are on. This can quickly drain a battery, unlike a monochrome graphics display that can be read with or without the backlight on.
  • Thicker than OLEDs
  • TFTs can average a greater thickness than OLEDs by as much as 8mm+
  • Sunlight readable
    • The greatest majority of thin film transistor displays integrate a Transmissive polarizer. Transmissive polarizers provide a very bright backlight, but operate poorly in direct sun light.
    • There are a few thin film transistor displays available with a Transflective polarizer that is better suited for direct sunlight. At this time they are more expensive than Transmissive thin film transistor displays.

Value added available:

  • Touch panel can be added
    • Resistive touch panels are the lower cost option and standard for many displays that are 5” or less in size.
    • Capacitive touch panels are more expensive and allow for multi touch and zoom. It is possible to add a capacitive touch panel to any thin film transistor, but a one-time tooling fee is required.
  • Brightness (nits) can be increased
    • Increasing the brightness of the thin film transistor is possible by modifying the design. There is a one-time NRE required for this customization
  • Customizable FPC cables, LED backlights, bezels and touch panels
  • Sunlight readable options available

Need a thin film transistor display for your next design? Call us at 480-503-4295 or use our Contact Form.

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