Bleeding: what it is and why ips monitors suffer from it

Gone are those huge and heavy CRT monitors, the emergence of technologies such as the LCD has given us an incredible improvement in the image quality of a monitor. Especially the IPS panels, which we will talk about today due to the phenomenon called Bleeding or Backlight Bleeding that usually affects them.

It is possible that your monitor is of this type and you have never noticed this bleeding phenomenon, or perhaps you have been lucky enough to never meet one. We are sure of one thing, and that is that the LED technology of the monitors has many advantages, but there are also some factors or disadvantages that should not be forgotten.

Index of contents

TFT-LCD screens and IPS technology

Let's start by explaining what is the technology used by current screens, specifically that which has to do with IPS panels, which is none other than TFT-LCD.

Yes, it is not a mistake, an IPS screen is basically a TFT LCD or Thin Film Transistor Liquid Crystal Display. It seems silly, but the best way to know that a screen is liquid crystal is to touch it with a finger and see that a wave is produced around the finger in gray or black, as you see in the image.

TFT-LCD technology

TFT-type displays are a variant of the first LCDs that use transistors to improve image quality. In turn, it is the technology subsequent to CRT monitors or monitors with cathode ray tubes, those with a glass screen and a huge ass that generated the image with an electron gun striking a phosphor matrix. These are completely different, and use a matrix of pixels arranged in rows and columns. Each of these pixels, which are essentially capacitors, has a switching transistor so that it can be independently controlled, not losing brightness with every refresh update. This is precisely why TFT screens do not flicker in human sight.

In turn, the pixels are made with a transparent layer of indium oxide and tin in the front area (what we see), a liquid crystal layer in the central area and another transparent layer in the back area so that these let the light pass through them thus forming the colors. In a small area of ​​them have the transistors, which can only be seen under a microscope and that will not affect the image quality due to its tiny size. What's more, their silicon film is practically removed to let light pass through them.

But unlike OLED panels for example, these pixels are not light emitting diodes as such, what they do is obstruct the white light generated by a panel of LEDs or CCFL (Cold Cathode Fluorescent Light) that is located behind them. Variation of brightness in pixels consisting of Red, Green and Blue (RGB) sub-pixels will cause the corresponding image to appear. So, to begin with, a pixel is made up of three sub-pixels, and in turn these will let a certain amount of light pass through at any moment so that the effect makes our eyes see a certain color. If for example we go to a giant screen that is TFT, we can perfectly see each of these red, blue and green pixels in them.

How an IPS panel works and what advantages it gives us

Composition of an IPS panel

We have already seen more or less how an LCD screen works, but in the market we have different types of lighting technologies, some use white LED backlighting, and others CCFL, older and based on fluorescent tubes like the ones we have in the kitchen. One of them is for example TN technology, the cheapest and most basic of TFT panels.

But we will focus on the IPS that means In- Plane Switching or plane variation. These have a liquid crystal distribution aligned in parallel by means of several layers that improve the colors that the pixels generate when letting light pass. This design aims to substantially improve the quality delivered by the TN panels, since the displacement of the liquid metal horizontally makes the viewing angles much better. Currently they are at 178 mientrasC while a TN offers a very marked distortion in colors if we look at it from open angles. This is the clearest way to know if we are in an IPS or TN panel.

But it not only improves angles, it also increases color rendering and depth, thanks to the use of LED backlighting instead of CCFL. In this way we have 8 and 10 bit panels, being able to generate 16.7 million colors for the first case, and 1, 070 million colors for the second. Of course, they used to be slower panels in response than TNs and they supported less refresh rate, although this gap has been greatly reduced, with IPS of up to 240 Hz and responses of only 1ms. But without a doubt the biggest disadvantage that they can present is the phenomenon of screen bleeding or backlight bleeding, which we will now explain.

What is Backlight bleeding

We come to the main point, bleeding is a phenomenon that occurs when there are light leaks on the edges of an LCD technology panel, more specifically in the IPS. Screens of this type have, as we already know, a very powerful backlight system behind the pixels that is what really illuminates them. It can be CCFL or LED type, and sometimes they deliver brightness of up to 1500 cd / m ² or nits.

The case is that, due to small manufacturing defects, the liquid crystal panel and pixels do not adequately block the backlight, thus causing light to leak from the sides. This is especially evident when the screen is representing dark colors such as gray or black, and it is also more noticeable when we increase the brightness power of the screen. Because the effect is assimilated to a bleed or stain, it has been given that name.

Bleeding is quite usual in mid or low range IPS screens, and it almost always occurs at the edges of the screen, especially in the corners, where the panel finishes are usually more critical. However, this phenomenon can also be seen in central parts of the screen, especially after a long time of use of the screen and the degradation of the liquid crystal, which also makes them yellow a little.

Does it only appear in the IPS?

In theory, the construction method using these IPS honeycombs is the one that makes them more susceptible to bleeding. Panels with this technology are made up of numerous layers, placed on top of each other and at different angles. With simple deviations in the laminate or cutting them, it can cause these light leaks. Likewise, changes in pressure in the gluing and installation of the different sheets can also cause this type of light leakage in areas other than the edges of the panel.

Theoretically, all the honeycombs with TFT-PCD technology can be susceptible to bleeding, although the manufacturing peculiarities of the IPS make them long being the most prone to this phenomenon.

How to tell the difference between bleeding and IPS Glow

A very important aspect to take into account of LCD technology in general is that its panels present a characteristic brightness effect due to the use of liquid crystal. This brightness is called IPS Glow, since it is usually more noticeable in IPS, although it is also observed in TN.

IPS Glow is different from bleeding, although it also manifests itself on dark backgrounds. In this case, it is a more generalized brightness that appears in different areas of the screen or even on the full screen depending on the angle at which we look at it. This is a normal operation of these panels, due to the technology used, so it is not a mistake, although it is true that less quality will appear on quality monitors.

What is important will be how to differentiate one phenomenon from another. To do this, we must put a black background on the screen, and then raise the brightness until it is more noticeable. Now what we must do is look at the screen from different angles.

• When bleeding, the brightness will show up prominently at the edges and will remain perfectly visible regardless of the angle at which we look at the monitor. In addition, the bleeding appears from the moment we start the monitor for the first time. When it is IPS glow, the brightness will be more widespread and anywhere on the screen. If we move at different angles, this should be seen more or less depending on where we are, and can be completely eliminated if we place ourselves in front of the monitor. It is possible that due to the degradation of the panel, this brightness will appear after a period of use.

How to remove bleeding

There is no possible way to remove bleeding from a screen unless we take it apart and stick its layers back, something we believe is not within the reach of many. This is what we can do to get rid of it or at least reduce it:

• Use the manufacturer's warranty and have the monitor replaced. Many times bleeding appears only in certain units, the least we can do is take advantage of our rights as users. Lower the maximum brightness of the monitor until it is seen as little as possible. It is not a bad idea to do this if we do not have a guarantee or it is a mid / low range monitor that we already expected something like this. We can tighten or loosen possible screws that fix the image panel to the screen frames. We know that the LCD reacts to pressure by distorting colors, so it may be due to a poor fit on the frames. Disassemble and reassemble the panel. We do not recommend it at all, but if you like to experiment, go ahead.

Conclusions on bleeding and IPS monitors

We have already seen that bleeding can appear on any monitor with IPS technology, and the most expensive monitors do not get rid of it either. Obviously not a pleasant feeling, especially if we spend a fortune, so the least we can do is claim the manufacturer for a new unit.

Luckily, in the market we have other technologies such as TN or VA, which combines the advantages of IPS and TN to give us very good quality honeycombs and free of bleeding. Whether you are a gamer or a designer, there are impressive models in both color quality and speed.

Now we leave you with other tutorials and our guide to monitors.

So do you have bleeding on your monitor or is it IPS glow? Tell us about your experience with this phenomenon and if you have ever returned a monitor for this problem.