Different types of Backlights
What is a backlight anyway?
LCDs are designed to work by using liquid crystals to produce an image. The liquid crystals are embedded into the display screen, and there must be some form of light source behind the thin film of Liquid Crystals to illuminate them. The light source can be several different types, such as an LED or CCFL or a flashlight even! Whether this LCD is a big TV screen in the family room where you watch superheroes save the world from impending doom, or a small 14-inch display screen inside a giant Mazak or Panelview 1400e CNC Milling machine controller – the basic concept is the same.
The liquid crystals do not emit light on their own, it is the job of the “Backlight” to shine a light on them to show you the latest viral cat video on TikTok on your cell phone for example. So, where does this light come from? How do we produce the light required to show an image on an LCD? Well, this is what we are here to discuss and clear up.
Before we get into the different light sources, it is important to note the “signal” that produces the image. The driver board commonly known as the video card is responsible to arrange the digital scan and signals of the image that is shown on the display – no matter if you have an old CRT or an LCD screen.
Just as there are different light bulbs for a building, there are a few different lamps for the LCD units. Some use a thin LED (Light Emitting Diode) hidden under the sides of the front bezel. This LED strips shine the light in an X or X & Y coordinates to light up the Liquid Crystals.
Some LCDs use a sheet of LED lights like below. This allows the LCD to have a much smaller bezel all the way around and will produce a brighter image, at the cost of a higher voltage. But the concept is still the same, light up the Liquid Crystals to show an image.
Other, older models LCDs, use the CCFL backlight bulbs. These use higher voltage and are very fragile, so they are susceptible to breakage and dimming over time.
Lastly there is the single LED light bulb that use many fiber optic strands to carry light to the back of the LCD screen. Panelview 550 controller is a prime example of this style backlight. The OEM incandescent bulb (think regular heating element light bulb) will burn so hot that it melts the ends of the fiber optic strands and turns them brown over time, so light can’t travel through and light up the LCD. A single low voltage LED bulb that emits no heat and a new fiber optic array will fix this issue. Or why not simply swap the whole LCD with one that has an LED backlight built in (under the bezel – remember) You will never have to change the fiber optics or the silly old style light bulb again. Monitech exclusive “All-In-One” LCD screen, replaces 3 parts – The Backlight, Fiber strands , and LCD panel in one sealed unit. Very popular!
LCD vs CRT
Unlike a CRT where a Cathode Ray Tube (-what CRT stands for by the way) shoots electrons that excite the phosphor inside the vacuum enclosed surface to display the image, an LCD uses Liquid Crystals to show the image, but it needs a light source. Advantages of an LCD are light weight, low voltage and much longer lasting; as well, a sharper image on a flat surface is much easier to read. Moreover, the Original Equipment MFG of the Industrial Machine have long closed their doors or they no longer have the CRT screen replacement available, because no one makes them anymore! You could try and find a used one, but you are faced with the same issue if it works on your controller at all. Frankly speaking, CRT screens are out, LCDs are in.
Do you remember when your parents told you not to sit so close to the TV? That is because of the Cathode Ray Gun was thought to be radioactive! 
In closing, let me leave you with this thought. When a light burns out at your home, Do you pickup and move to another house!! or do you simply change the light bulb. What if you could replace your light bulb with an affordable LED solution that runs on much lower current which saves you money, and it is durable and long lasting. However, there will come a time to change the whole light fixture to a flat panel LCD (Think machine controller display), we can help you with that issue also. Monitech services over 300 makes and models of industrial controller HMI displays on the market today. And if we don’t have the solution readily available on the shelf, we will develop a custom kit for your specific machine controller. Sounds to me like Monitech is your GO-TO “one stop shop” for all controller display needs. Please visit our website read our Blogs and Reviews as well, visit our social channels, Like and share, subscribe to our YouTube videos to stay informed. Often times we offer discounts and promos, to our valued customers, so that they can take advantage and save money where possible. How does that sound??
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