LED displays do get backlight bleed, which occurs when an LED TV's backlight leaks around the edges of its LCD panel or unevenly lights it.
Sony states that this is a common phenomenon on all LCD TVs.
- Backlight Bleed is when some screen areas are lighter than others due to spillover from a backlight or uneven backlighting.
LED TVs and QLED TVs work by using a strip or grid of LEDs (light-emitting diodes) as a backlight. This white backlight shines through an LCD (liquid crystal display) screen, which determines which colors show up in each screen pixel.
When light bounces off any surface around the edges of the screen, it can result in Flashlighting, or extra light at the edges or corners, making the lighting of the LCD panel uneven.
Clouding occurs when layers of the screen become uneven due to misalignment, damage, pressure, or temperature changes. The misalignment results in the light not being evenly distributed.
- Flashlighting is the type of backlight bleed experienced at the corners or edges of a screen. Kevin Jones / TechReviewer
- Clouding is the type of backlight bleed experienced as irregular patches throughout a screen. Kevin Jones / TechReviewer
Backlight bleed goes by various names, including light leakage, screen bleed, light bleed, clouding, blooming, mura, banding, and un-uniform brightness.
Excessive LED backlight bleed can be caused by temperature changes, overtightened screws, and poor TV design or manufacturing.
While some brands and models of TVs are better at preventing particular causes of backlight bleeding, it is pervasive among LCD TVs in general.
Excessive LED backlight bleed can be caused by the following:
- Temperature changes result in materials expanding or contracting, including the LCD panel or frame.
- Overtightened screws can cause the warping of components.
- Poor TV design or manufacturing may allow for excessive reflective surfaces, unsealed gaps where light can escape, or misaligned components.
In general, any TV which uses a backlight may experience some amount of backlight bleed.
According to Sony, new TVs can experience an increase in backlight bleed, which may slowly go away after a few weeks or months of usage.
Temperature changes may result in some components moving or warping slightly. Backlight bleeding could be reduced after either cooling down or warming up, depending on how the TV was designed.
If time doesn't fix your backlight bleeding, then check out the section on how to fix backlight bleed.
Backlight bleed caused by overtightened screws, misaligned components, and poor design will not go away on its own.
The main visual impact of backlight bleed is uneven lighting and reduced contrast.
Depending on the severity of backlight bleeding, some backlight bleeding is often tolerable and easy to ignore.
The uneven lighting will be more noticeable if you are in a dark room, are watching a dark scene, or have the TV set to high brightness.
Most LED TVs experience some form of backlight bleed, although it may not be distracting in many cases. Manufacturers are getting better at mitigating various causes of backlight bleed.
LED TVs and QLED TVs both use backlights, which is the underlying cause of backlight bleed. Because of this, the only way to guarantee that you won't get backlight bleed is to get an OLED TV, which doesn't experience backlight bleed.
Perhaps you still want to get an LED TV due to the lower price point. In that case, your best bet is to read reviews to determine if others are experiencing backlight bleed issues with a particular TV model.
Any TV which uses a backlight may experience some degree of backlight bleed. To altogether avoid backlight bleed, you'll need a TV with self-emitting pixels, which is the case for OLED TVs.
Some possible ways to fix LED backlight bleed or make it less noticeable include:
- Give it time: Some new TVs experience an increase in backlight bleeding which can slowly disappear after a few weeks or months.
- Reduce screen brightness: Reducing brightness can reduce the backlight intensity, which may cause the backlight bleeding to be less noticeable or even impact the screen's temperature.
- Turn on auto-brightness: Reduce backlight bleeding for darker scenes by lowering the overall backlight brightness.
- Enable local dimming or LED dynamic control if your TV supports it: Reduce backlight bleeding for darker scenes by dimming darker portions of the scene.
- Check your warranty, and determine if you can return the TV to the seller or manufacturer if the backlight bleed is excessive and distracting.
Some more extreme options, which may damage your TV and void your warranty:
- Loosen screws: Excessive pressure caused by over-tightened screws can result in flashlighting.
- Use a microfiber cloth to gently rub the portion of the screen where the backlight bleeding is prominent: This may help with clouding by evening out an uneven LCD panel.
- Take apart the TV and apply electrical tape around the edges of the LCD: While likely to void your warranty, this could reduce light escaping and reflecting around the edges of the screen.
If the backlight bleed is not too distracting, there's nothing to worry about. Backlight bleed typically will not get worse over time on its own. However, frequently moving a TV around or improper handling could result in bending the tv frame or components, resulting in backlight bleed.
Some manufacturers do not allow returns based on general backlight bleeding, which is typical of LED backlighting. For example, Sony considers bleeding that is only visible on "black images and in a dark or very dim room" to be considered within specification. Are you experiencing backlight bleeding in bright scenes and a well-lit room? If so, you may be able to return the TV to your manufacturer for a replacement.
Check with your seller and manufacturer for exact details.
Blacklight bleed is easiest to identify by evaluating whether the screen is evenly lit while viewing a pure-black image.
To determine the maximum amount of backlight bleed possible with a TV, you can: increase screen brightness, turn off auto-brightness, view the TV in a dark room, and disable local dimming. These are not settings for optimal viewing but can be used for testing the worst-case scenario.
See the section What is backlight bleed and what does it look like? for details on what to look for.
Kevin Jones / TechReviewer