What exactly is a LCD Digitizer? Well, to put it simply it is not an LCD. LCD stands for Liquid Crystal Display, is the component that actually “displays” the picture for your viewing. For people with iPhones, think of the Retina Display. The LCD is usually very thin, and extremely fragile.
Below is a picture of the iPad LCD as a reference:
The picture to the top is the iPad LCD replacement part, removed from the Digitizer. This LCD is what is responsible for actually displaying the image. This part is extremely FRAGILE and can break very easily. The cable at the top of the LCD is the LCD flex cable, this is directly attached to the LCD and is what connects to the iPad’s logic board during installation. If the LCD flex cable is not seated properly or torn during installation, it can cause several different issues such as a black screen, lines going up an down, faded images, discoloration, flickering of the LCD, etc.
The Digitizer is a completely separate component than the LCD, although the LCD and Digitizer are usually fused together during manufacturing with an optical adhesive. So yes, the glass on the front of your screen is the Digitizer, and since it is usually fused to the LCD, many people just refer to it as an LCD Digitizer. The Digitizer is essentially the front glass that cover the LCD. The digitizer’s main function is to protect the fragile LCD, as well as to transfer all of the touch functions (swipe, press, zoom, etc) to the LCD. The touch action on the Digitizer glass is transferred through the Digitizer flex cable, so the LCD image can respond accordingly. The Digitizer flex cable should already come installed on the glass digitizer (You can see the flex cable at the top of the Glass Digitizer in the picture below) Below is a picture of the iPad Digitizer Glass:
As you can see, this part (Digitizer) is separate from the LCD.
This is where things can get confusing- an LCD Digitizer assembly is actually these two parts fused together. If the glass digitizer is broken, some people say you can change the glass itself by separating it from the LCD. However, this is NOT EASY OR RECOMMENDED. The best way to repair a broken LCD or Digitizer is to buy the complete assembly of the LCD and Digitizer fused together. This is especially true with the newer iPhones that come out. When a new model iPhone comes out, the full LCD Digitizer Assemblies are generally super expensive; for example, the iPhone 5 LCD Digitizer Assembly was over $200 when the phone first came out. But you could buy the glass digitizer only for about $40. Since that time these prices have dropped significantly, but the point is, if you try to replace just the glass, you run the risk of damaging of your LCD as well. Then you will need to buy a new full LCD Digitizer assembly as well. A glass only repair can be done. However, it is literally nearly impossible unless you have the right tools. And even when you have the right tools, you run the risk of scratching and compromising the LCD of the device.