The display on a laptop is an important output device, but it can also be a useful input device as well. In this video, you’ll learn about LCD display types, backlights, Wi-Fi antennas, digitizers, and more.
Many of the laptops we use today have an LCD display. This is a liquid crystal display where there are a series of liquid crystals associated with color filters, and there is a backlight or light source behind all of that shines through to give us the image that’s on our screen. From a laptop perspective, the advantages of an LCD display is that they are lightweight and use very little power, and they’re relatively inexpensive to make, keeping the cost of the laptop down.
There are some disadvantages with LCD displays. One is that this light source in the back has to shine through to provide the color, which means getting a true black can be quite difficult on an LCD display. We might also have different kinds of backlights on our displays. The light source may be fluorescent, it may be LED, or may be some other type of light. If this backlight was to fail, you could see that it’s part of the display itself, making it relatively difficult to be able to repair or replace.
There are three different technologies of liquid crystal displays that you need to be aware of. One is the TN LCD, this is the Twisted Nematic LCD, which gives us very good response times. If you’re a gamer or you’re using some application that has fast moving graphics, this may be the display type for you. Unfortunately, these displays often have very bad viewing angles, which means once you get off to the side of the display, you’ll notice there’s an inversion of the color. If you want the best possible view of a TN LCD, you need to be looking directly at the display.
If you’re looking for the best possible color representation on an LCD display, you’ll want to use an IPS LCD. The IPS stands for In Plane Switching. This gives you very good color representation, which is great for using graphics or doing some type of desktop publishing. But these are slightly more expensive than a TN. So that extra color representation comes at a bit of a cost.
If you like something that’s in the middle between TN and IPS, you may want a vertical alignment LCD or a VA display. This has good color representation, but you’ll find the response times are a bit slower than a twisted nomadic LCD. If you have a newer device, you may be using an OLED display. The OLED stands for Organic Light Emitting Diode. And it doesn’t have a backlight. Instead, this organic material emits light when you provide it with a current. Because there’s no backlight and no liquid crystals, these are very thin displays. And there’s no glass that you would need on the front of the display to protect it.
The real key is that organic material that’s able to create its own light when you provide it with power. And that’s what allows these displays to be very light and very thin. You’ll find them on tablets, phones, and smart devices, not only because they provide such great color representation, but because they’re so light and so easy to carry.
One aspect of our laptop displays that we don’t often think about is how they’re used on wireless networks. When you open the laptop, your display is the highest component in that system. So it’s a perfect place to run your wireless antennas. If you’re using 802.11, Bluetooth, or some other type of wireless networking, then you probably have an antenna that runs to the top of your laptop display. This creates some challenges when you are replacing the display, because you not only have to remember to connect all of your video components, you have to remember to connect all of these antenna wires as well.
Here’s a picture of a display. This one does look a bit damaged. You can see the primary connection that we use for the video signal. But coming out of the other side of the display is a white and a black wire that’s used for 802.11. You need to take care when replacing this display that you’re following the same path that the previous wires took, so that you could connect all of those wireless antennas to the appropriate components on the system board. This is what it looks like when everything is in place. You can see some antenna wires coming out of the system board. They’re wrapping around the system. And these appear to wrap all the way into the top of this particular laptop.
If we look closely, we can see wires that are used for the 802.11 network. There are some additional wires also at the top of this display. These are the wires that are used to bring the signal from the audio and video associated with the webcam. Many laptops these days have webcams integrated into the laptop itself. That’s that small little hole at the top for the camera and a tiny little right next to it for the microphone. This can obviously be used for video capture, but it’s also used for meetings and video conference calls. This makes it easy when you need to be on a Zoom call. You can simply open your laptop display, and the camera built into the display will be able to show you on the call.
Here’s a better shot from this laptop, which clearly shows that this is the webcam that’s integrated into the laptop display. And you can see there are holes also for the microphone in the display as well. We mentioned earlier that a liquid crystal display needs some type of light behind the system to shine through so that we’re able to see the images on the screen. If you’re working with an older laptop, this might be a fluorescent type of light, specifically a CCFL or Cold Cathode Fluorescent Lamp. These require a bit more power than the LED lights that we tend to use today. And you’ll find the LED back lights are also a bit thinner, taking up a lot less space on your laptop computer.
If you’re working with an older laptop or you need to replace the display on an older laptop, you may find that the backlight that it’s using is a CCFL backlight. Newer LCD displays might use LED lights instead of using a fluorescent lamp. These LED lights may be around the edge of the display or they might be in a matrix, such as the one that’s seen here. These have become so common that instead of people referring to this as an LCD, they often refer to it as an LED display. What they really mean, of course, is an LED backlit LCD.
If you were to pull the front off of a display that has LED backlights, you might see the matrix behind it looking like this. These are strips of LED lights. And you can see each one of these LED lights is in a very large matrix behind the display. The display is smart enough to recognize what parts of the display should be lighter or darker and will adjust the lighting depending on what you’re viewing on the screen.
If you’re working on one of these older laptops with CCFL or these fluorescent backlights, you may also find some additional components behind the screen. These are inverters. We use these inverters because the CCFL backlight requires AC power, but your laptop is using DC power. The inverters are responsible for taking that DC power, converting it to AC, so that we can power those fluorescent back lights.
One way to tell if your backlight has failed is to shine a flashlight directly at the screen. If you’re able to make out some of the information on the screen, then it’s very possible that the problem is not with the display, but with the backlight behind the display. If this is a CCFL backlight, you may just need to replace the inverters, and you’d be able to restore the backlight. On some systems you may have to replace the entire display. You’ll have to check with the documentation for your laptop to see what applies for your particular model.
If you’re using a hybrid device, like this one that has a keyboard and a tablet type display, you may be able to use a very high resolution input with this stylus. That stylus allows you to directly draw on the screen. And whatever you’re pushing on the screen is converted into digital signals in the display. We’re able to provide that conversion because inside of this display is a digitizer that converts that analog input onto the display into digital signals that the computer can use.
The digitizer in your device may only allow for stylus input, or it might also provide input using a touch screen. A touch screen digitizer takes input from our finger, converts it into a digital form to be used by that system. It’s a very common way to get information into a laptop or a tablet. And we can often use a keyboard, a stylus, or key presses all on the same system to perform this input function.