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What is TFT LCD Technology?

In most of the Electronics projects, we would be extremely delighted to have a display through which we can monitor the vitals of our project. A TFT (Thin Film Transistor) type driver is the most popular form of LCD panel driver currently available. Through the active switch, it achieves independent and exact control of each pixel, allowing it to generate finer visual effects than the preceding passive driver (commonly known as pseudocolor). As a result, TFT has been used to power most LCD screens, LCD televisions, and certainly mobile phones.

In this blog, we are going to discuss what TFT LCD is,  Its construction, advantages and disadvantages, and applications. in detail.

What Does Thin-Film Transistor Liquid Crystal Display (TFT LCD) Mean?

TFT LCDs (thin-film transistor liquid crystal displays) are a form of liquid crystal display (LCD) that uses thin-film transistor technology to increase features like contrast and addressability. A single transistor is utilized to drive each individual pixel in TFT technology, providing for faster response times.

TFT (Thin Film Transistor) is a thin film field effect transistor that can “actively” control each individual pixel on the screen, resulting in a significant reduction in response time. TFTs have a reasonably fast response time of about 80 milliseconds and a large viewing angle of about 130 degrees, which is why they are mostly employed in high-end devices. This device has the ability to display screen information at a high rate, with high brightness, and with high contrast.

TFT stands for the thin-film transistor, and it is a liquid crystal display that is operated by an “active matrix” approach. To manufacture transistor electrodes, thin-film technology is used, and the scanning method is used to “actively pull” to control the opening of any display point. When a light source is irradiated, it emits light.

To make transistor electrodes, thin-film technology is used, and the scanning method is used to “actively pull” to control the opening of any display point. When a light source is irradiated, the light first passes through the lower polarizing plate and is then transmitted by the liquid crystal molecules, achieving the display’s goal of shielding and transmitting light.

Basic Construction of a TFT LCD

Thin-film transistor liquid crystal display technology employs “field-effect” transistors, which are constructed by layering thin films on a glass substrate, as the name implies. Microprocessors are frequently made using this method. 

The TFT in the LCD controls individual pixels in the display by controlling the polarization of the crystal material by setting the level of the electric field across the three liquid crystal capacitors (one for each subpixel of red, green, and blue) in the pixel. The amount of light that reaches the color filter from the backlight is determined by the amount of polarization in the crystal. TFT is also known as active-matrix LCD technology because of its ability to manipulate each pixel directly and quickly. The following are the different layers of a TFT LCD

 1. Polarization layer

 2. Thin Film Transistor

 3. Liquid Crystal

 4. RGB Color filter

  • Polarization Layer-

TFT LCD is made up of several layers that are sandwiched between two polarization layers. These two layers are at a 90-degree angle to one another. Unpolarized light is polarized with a polarization filter. When we switch on the backlight, it produces both horizontal and vertical light planes; however, the first polarization filter, which is close to the backlight, only allows the horizontal plane to pass through, whilst the second filter enables the vertical plane to pass through. You might be asking how we can see light on the screen when both filters are dark. This is a liquid crystal miracle.

  • Liquid Crystal-

These liquid crystals are sandwiched between horizontally edged glass and vertically edged glass and are arranged in random ways. The glass is aligned in such a way that it bends in a predictable fashion. Light follows the route of liquid molecules as it travels through squeezed liquid crystals. Any light that passes through the liquid crystal in a horizontal plane emerges in a vertical plane. This effect is called the scattering effect of liquid crystals. These compressed liquid crystals are coated with a transparent electrode, which aligns the liquid crystals when a voltage is given to it.

  • Thin-film transistor-
Thin film transistor

Each pixel must be addressed separately to align each liquid crystal in a meaningful fashion, which is accomplished using thin-film transistors. The refresh rate of the display is determined by the thin-film transistor layer.

  • RGB color filter-
TFT LCD

The backlight’s unpolarized light goes via a horizontal polarizer that permits only the horizontal light plane to pass through. This filtered horizontal plane light is twisted into a vertical position by liquid crystal, then passed through vertical polarization, and finally through the RGB color filter. When the thin-film transistor is turned on, however, Liquid crystal does not twist the light beam and instead stops at vertical polarization. We can regulate the amount of light reaching the color filter by altering the voltage through each set of crystals in this way. Different shades of color on display are determined by the brightness of each pixel. The voltage to each pixel (liquid crystal) is altered in this way to produce different shades of color. Each pixel consists of three subpixels, but it is so tiny that it is invisible to the human eye to find out its presence.

Factors to Consider when Selecting a TFT Display

The type of TFT LCD monitor or industrial display you choose to purchase will depend on the specifications of your application or project. Here are a few important factors to consider when selecting an appropriate TFT LCD display technology:

  • Size of the display
  • Resolution of the display
  • Interface type
  • Viewing angle
  • Backlight life
  • Refresh Rate
  • Power Consummation
  • Contrast Ratio
  • Driver IC
  • Image Quality

Advantages  of TFT Displays

  • Minimal energy consumption
  • Sharp visibility
  • Excellent physical design
  • Fast and accurate response time
  • Minimizes eye strain
  • Space efficient design (can be placed anywhere in your workspace on a rotational mount so you can turn it in all directions)

Disadvantages Of TFT Displays

  • Higher price point than other displays
  • Disproportionate viewing angles
  • Restricted utility due to glass paneling (e.g., ineffective for outdoor use where glass can showcase glares from natural lighting)
  • Relies on backlighting to provide brightness rather than producing their own light, hence, they need built-in light-emitting diodes (LEDs) in their backlighting structure

TFT Applications

TFT displays are found in many applications these days, from mobile devices, appliance, medical devices, instrumentation, aircraft and certainly computer display devices as well as TV’s. The addition of the thin film transistor in LCD design vastly improved the use of LCD’s in all market areas.

Conclusion:

Hope this blog helps you to understand the basics of TFT LCD Display, Its construction, advantages and disadvantages, and applications. We, MATHAELECTRONICS will come back with more informative blogs.

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