An LCD TFT display is among the most popular choices for visualizing information in a wide range of applications today. One reason behind the display’s popularity is the broad range of customization options that allow customers to choose an optimal mix of key parameters.
But what are the parameters you can choose from when ordering an LCD TFT display from a manufacturer?
In this article, we explore the crucial parameters of LCD screens that you should know before approaching a manufacturer with your application idea – or even before an LDC TFT display as a component for your application.
How do LCD TFT displays work?
LCD is an acronym for Liquid-crystal display. The name LCD refers to the liquid crystals that provide the core functionality of LCD screens. How do these crystals work exactly? It’s all down to the changes in light polarization achieved by manipulating the electric field to orient the liquid crystal particles the way we want.
And if we’re talking about LCD TFT displays, we need to explain TFT as well. TFT stands for the thin-film transistor, a type of transistor created by depositing thin films of semiconductors over a supporting substrate (which is nonconductive – in this case, it’s glass).
This technology offers a better quality of displayed content compared to passive-matrix solutions like STN (Super-Twisted Nematic). The images on LCD TFT displays change swiftly thanks to the reduced response time achieved by the active-matrix that maintains the liquid crystal state of matter between refreshing cycles.
5 key parameters of LCD TFT screens you should know
1. Brightness
Also called luminance, brightness measures the luminous intensity of the screen when displaying a pure white image. Usually, brightness is given in the SI unit which is candela per square meter (cd/m2). However, you can also access brightness in nits (nt, 1nt = 1cd/m2).
The brightness of a typical monitor you use in your daily life is usually around 140-150 cd/m2. This offers optimal work comfort as long as you’re surrounded by proper ambient lighting. A brightness of 250 to 300 cd/m2 might cause eye strain and impact work efficiency.
Did you know that some best-in-class smartphones come with brightness estimated as high as 700 cd/m2? This is necessary because brightness provides better readability of the content presented on a smartphone screen in intensely lit spaces. The same goes for applications such as passenger information systems or displays used in public service vehicles or shopping malls. Such applications require around 700 cd/m2 brightness.
And what about displays used in outdoor devices? For example, glass storefronts on the street? In this case, applications may require even 1000 cd/m2. Litemax is an acclaimed producer of high-brightness.
2. Resolution
It’s impossible to talk about display resolution without knowing what a pixel is. The pixel is the smallest controllable element of a picture that is displayed on the screen. It consists of three subpixels that carry the colors red, green, and blue. Together, they represent the RGB color model.
By manipulating the light transmitted through subpixels properly, we can generate the pixel’s color tones. And every pixel color can be easily adjusted independently.
In applications of the highest quality, it’s essential that users don’t see pixels with their own eyes. If you can see them, it means that the display has too few pixels.
And this is what resolution is all about. It defines the number of pixels visible on the screen. Usually, the resolution is expressed as a number of horizontal and vertical pixels. For example, take the popular resolution of 1280×720 pixels. This means that there are 1280 horizontal pixels and 720 vertical pixels.
Some other common resolutions are:
Full HD – 1920×1080 pixels
4K – 3840×2160 pixels
8K – 7680×4320 pixels (the highest resolution available to the general public).
High resolution is a crucial parameter for retail applications – for example, displays used in storefronts like video walls. Information carriers used in public utility buildings like government offices often require high-resolution displays as well.
3. Contrast
Contrast is a parameter that defines the ratio of light intensity between the brightest and the darkest points on the display. The content presented on the display with high contrast and optimal brightness will be readable and clear.
We can achieve high contrast by deepening the black color, for example. Increasing the display’s brightness isn’t going to have any impact on the contrast ratio. Furthermore, display manufacturers improve contrast by developing some other LCD TFT functionalities such as local dimming (selective backlighting).
4. Operating temperature
This parameter is crucial for outdoor applications. Note that displays in solutions used in outdoor environments can be exposed to both high temperatures and frost. If a device is located in a sunny spot and in conditions where a surface might heat up to even 100°C, the proper functioning of the displays might be disturbed. That’s because the liquid crystals that make the LCD TFT might boil.
However, if your application will be used in such contexts, there are solutions on the market that make it work. They extend the operating temperature range and use the hiTni technology to prevent the liquid crystals from boiling.
5. Viewing direction
The final aspect to consider is the accessibility and readability of displayed content. This is particularly in transportation applications and information carriers used in digital signage applications. Choose solutions offering the fullest viewing angles for such devices. The optimal options here is 89°/89°/89°/89°.
However, not every project will require a display with such high viewing parameters. For example, if your design will have screen located below the line of sight (for example, in home appliances), you can use the matrix with a 12 o’clock viewing angle. And if the users of your application will be looking at the screen from below, a matrix with 6 o’clock viewing angle will be enough.
Choosing a slightly more narrow viewing direction is an excellent measure for optimizing the final cost of your application.
Get high-quality LCD TFT displays with parameters that match your needs
It’s essential that you consider these parameters while looking for a display for your application. By analyzing your application’s requirements, you can analyze these parameters and equip your device with a display that offers perfect readability in its environment.
If you have any further questions about LCD TFT displays, don’t hesitate to get in touch with us.
At Melrose Systems, we have delivered countless LCD TFT displays matching even the strictest environments and know how to cherry-pick parameters to deliver a product that suits your unique requirements.