Custom LCD-TFT Displays
Choosing an LCD-TFT display for a designed device involves selecting many parameters. It is expected that images presented on LCD-TFT screens will be of the highest quality, and the content presented will be perfectly readable even in unfavorable conditions. From the designer’s point of view, a favorable quality-to-price ratio is usually also important.
How to choose LCD-TFT display parameters?
The most important LCD-TFT display parameters include resolution, brightness, contrast, viewing direction, and operating temperature. It’s worth paying attention also to the active area, so that after placing the module with the screen in the device’s housing, all content presented on it is still visible. For solutions that require touch functions, it is necessary to choose a preferred touch sensor, and also to apply a decorative/protective glass.
In addition, depending on the conditions prevailing at the location of the end device, it’s worth paying attention to compliance with EMC standards or ensuring the tightness of the housing.
Below we describe selected LCD-TFT display parameters.
LCD-TFT screen resolutions
A pixel is the basic element that creates an image. Colorful LCD-TFT screens display pixels consisting of three subpixels – red, green, and blue (basic RGB colors). Sometimes an additional subpixel is added – in white, which increases the brightness of the LCD-TFT display. Proper control of individual subpixels results in the creation of a specific pixel color.
The resolution of the LCD-TFT display determines the number of pixels horizontally and vertically (e.g., 1920×1080 px is FullHD, 3840 x 2160 px is 4K, and 7680×4320 px is 8K). The choice of LCD-TFT screen resolution depends on the purpose of the application. This parameter affects the readability of the image (the higher the resolution, the clearer the image), and the larger the diagonal (value measured in inches), the more pixels are needed to achieve appropriate image sharpness.
Brightness of the LCD-TFT display
The brightness of the LCD-TFT display is the intensity of light emitted by the screen, which is measured by presenting pure white. According to the SI system, the unit used to measure it is candela per square meter (cd/m2). The optimal brightness of the LCD-TFT monitor in office conditions is about 150 cd/m2. High brightness of the LCD-TFT screen is necessary in brightly lit places, regardless of the type of light (natural/artificial). These include, for example, LCD-TFT displays used in information visualization systems in public spaces (e.g., in transport or commerce, and – broadly speaking – in digital signage solutions). In their case, brightness of at least 1000 cd/m2 is required.
Learn more about the brightness of LCD-TFT displays in the guide where we describe this parameter.
Contrast of the LCD-TFT display
The contrast of the LCD-TFT display is the ratio of light intensity between the brightest and the darkest point on the screen. Its value affects the quality of the image. Generally, it can be said that the higher the contrast ratio, the better the readability of content. However, it should be read in relation to other parameters, such as brightness. The contrast of LCD-TFT displays is affected by, among others, the backlighting technology, which can be further optimized by using, for example, local dimming technology.
Viewing direction
LCD-TFT displays with the widest viewing angles, such as 89°/89°/89°/89°, are gaining popularity. These are solutions where the presented content can be read almost from any plane. Such possibilities are provided by, for example, IPS technology matrices.
However, in the case of devices where content from LCD-TFT displays is read from “above” or “below”, models based on TN (Twisted Nematic) technology with limited viewing angles can be used – at 12:00 (when we look from “above”) and at 6:00 (when we look from “below”). LCD-TFT displays with narrower viewing angles can significantly affect the reduction of end device implementation costs.
Operating temperature
The operating temperature of the LCD-TFT display is an important factor, for example, in outdoor applications. Screens placed outside are exposed to the effects of weather conditions, including frost and heat. If the temperatures recommended by the manufacturers are exceeded, the liquid crystals may freeze or overheat. Therefore, in outdoor applications, LCD-TFT displays should be used with the widest possible operating temperature ranges (currently up to -30~80°C).
If the device with the LCD-TFT display will be located in a sunlit location, it’s worth using models with hiTNI technology. The solar radiation reaching the earth can reach a value of even 1000 W/m2, heating the surface of screens to over 100° C. The rising temperature can cause changes in the state of aggregation of liquid crystals, which until they cool down again, lose their original properties – light is not transmitted, which ultimately results in the formation of black spots. In LCD-TFT displays with hiTNI technology, the risk of “overheating” liquid crystals (and as a result their temporary damage) is minimized, ensuring constant access to the presented content.
LCD-TFT display manufacturers in the Unisystem offer
Among the most important suppliers of LCD-TFT displays in the Unisystem offer, it is worth mentioning the largest global manufacturers such as Winstar, Litemax, Innolux, AUO, and BOE, as well as a local manufacturer, the Polish company Riverdi.