Industrial LCD displays are non-emissive displays. That is, they need a backlight system to operate and produce images. This is a major design difference when compared with other conventional industrial display technologies, such as LEDs and CRTs, both of which are types of emissive displays and don’t depend on a backlight system for their operation.
There are many different types of backlights used in the design of industrial LCD displays. Choosing the right backlight system is essential to achieving ideal performance and service characteristics for an LCD-panel-based product.
If you’re a manufacturer of an electronic product that utilizes LCD display, knowing about the different types of LCD-backlight systems and their features is essential. This article discusses the main types of backlights used in the design of industrial LCD displays and their advantages and disadvantages.
Most modern industrial LCD displays employ LEDsas backlights for operation.
LEDs, or light emitting diodes,are semiconductor devices that produce light when current is passed through them.
Inside an LED, we have a combination of free electrons and holes. The holes are present in the P-type semiconductor of the LED device, while the electrons are present in the N-type semiconductor of the LED device. When electric field is applied across the LED, the free electrons combine with the holes and release their excess energy in the form of visible light.
By specifying the types of materials used in the constructionof LEDs, manufacturers can produce LEDs in a variety of colors, including red, green, blue, yellow, amber and white.
LED backlight systems can be divided into three configuration categories:
- Full array
- Local dynamic dimming
Edge-lit LED backlight systems use one or more rows of LEDs placed around the rim of the LCD screen and incorporate a diffuser to produce even brightness across the display.
Full array LED backlight systemsuse LEDs that are arranged in a full-array configuration behind the liquid crystal (LC) layer. Like, edge-lit LED backlight systems, they also incorporate a diffuser to accomplish uniform brightness.
Local dynamic dimming LED backlight systems are designed as such where LEDs can be controlled individually or in groups. This allows users to adjust the level of light and color intensity in localized areas of the screen and achieve improved display results.
When compared to other backlight systems, LED backlight systems offer distinct performance advantage in terms of:
- Higher service life
- Widertemperature range operability
- Lower energy consumption requirements
- Higher dynamic contrast ratio
- Wider color gamut
- Higher shock resistance
- Wider dimming range
- Environmental friendly design
LED backlight systems also enable manufacturers to produce slimmer displays and helplower the overall production costs by eliminating the needs of an inverter.
Until about 2010, CCFL backlights, or cold cathode fluorescent lamp backlights, were the preferred backlight systemsfor large industrial LCD displays. However, due to the disadvantages in comparison to LED backlight systems, their present usehas been limited to only a few display manufacturers in the industry.
CCFL backlights operate on the principle of inelastic scattering of electrons. The electrons inside the CCFL backlight tubes are energized to high velocity, where they collide with the gas atoms (also present inside the tubes) andtransfer their energy to the atoms’ outer electrons. The outer electrons of the atoms transiently switch to higher energy states; however, because these energy states are highly unstable, the electrons revert to lower, more stable, energy levels, emitting photons in the process. These emitted photons are seen as visible light.
Unlike LED backlight systems, CCFL backlights operate on an AC supply. Hence, they need an inverter which can convertthe direct current in the circuit to alternating current. The incorporation of the inverter makes the cost of CCFL backlight systems higher than LED backlight systems.
Other issues with using CCFL backlights include:
- CCFL backlights generate electrical noise which tend to affect the performance of LCD displays
- CCFL backlights do not handle mechanical shocks very well
- CCFL backlights have high power needs
- CCFL backlights offer a limited dimming range
- CCFL backlights have poor switching response
- CCFL backlights are bulky, and so it can be difficult to produce compact LCDs with them
This completes our discussion of backlights systems used in the design of industrial LCD displays. If you have any questions about LCD backlights or LCD displays that you would like to ask, feel free to reach out; REVO will be happy to help you.
REVO is a global supplier of high-performing industrial LCD display solutions. The company works with OEMs, contract manufacturers and independent electronic distributors and supplies them high quality displays and display kits for their specialty product design needs. For more details, please call 1-866-738-6797 or visit the company’s official website.