Many of us have likely experienced this frustrating issue: after a few years of using a phone or monitor, the screen’s colors start to look off – either tinged red or pink, or appearing yellowish and dim. This isn’t your imagination; the screen is indeed undergoing visible changes. Today, let’s explore the principles behind aging in different screen types and how to address them.
OLED Screens Turning Red or Pink
Why Your iPhone or iPad Screen Is Red (And How to Fix It)
If your screen suddenly looks reddish or warm, don’t panic! In most cases, it isn’t a hardware glitch—it’s actually a display setting designed to protect your eyes.
If the screen is intensely red, you might have accidentally turned on a Color Filter. This is often used by people with color blindness or those who want to reduce blue light even further.
- The Fix: 1. Go to Settings > Accessibility. 2. Tap Display & Text Size. 3. Select Color Filters. 4. If it’s on, turn it off. (Specifically, check if “Color Tint” is selected and set to red).
The Relationship Between Screen Color and Sub-Pixel Display Ratio
To understand why OLED screens turn red or pink, we first need to know how screens display colors. Each pixel is composed of three sub-pixels: red, green, and blue. Various colors are mixed by controlling the brightness ratio of these three sub-pixels. Normally, when displaying white, the brightness of all three sub-pixels should remain balanced.
When the screen appears predominantly red, it’s typically because the relative brightness of the red sub-pixel remains unchanged while the green and blue sub-pixels have severely degraded. This shifts the RGB ratio from a standard 1:1:1 to something like 1.2:0.9:0.8. A screen that’s generally pink indicates a slight dominance of the red sub-pixel, with a ratio possibly around 1.1:0.95:0.9. These subtle ratio changes become increasingly noticeable after prolonged use.
To further illustrate this, we’ve created an OLED color shift simulator. Under normal conditions, when the screen displays white, the RGB light emission ratio is 1:1:1 (all sliders to the far right). After prolonged use, the blue pixels degrade the most, followed by green. At this point, to display white, the aged blue and green pixels cannot emit light at full brightness, causing the red pixel to have a higher proportion. Depending on these ratios, the screen color will lean towards red or even purple.
Organic Materials Used in OLED Screens
The core of an OLED (Organic Light-Emitting Diode) screen is its organic light-emitting material. These materials emit light when an electric current passes through them, eliminating the need for a backlight. This is why OLED screens can achieve true blacks and high contrast.
However, the nature of organic materials means they gradually degrade with use. Each instance of light emission consumes molecular energy, much like a burning candle, slowly “using up” the material. Different colored organic materials have different chemical structures, leading to varying degradation speeds. This is the fundamental reason why OLED screens exhibit color shifts after a period of use.
Why Blue Pixels Degrade Faster
Among the RGB primary colors, blue sub-pixels degrade the fastest. There are several key reasons for this:
- Higher Energy of Blue Light: According to physics, photon energy is directly proportional to frequency. Blue light has a higher frequency than red and green light, meaning blue organic materials endure greater energy impact during light emission, making their molecular structures more susceptible to damage.
- Lower Chemical Stability of Blue Organic Materials: In early OLED technology, the lifespan of blue materials was roughly half that of red and green materials. While current technology has significantly improved, blue pixels still remain the first to degrade.
When blue sub-pixels begin to degrade, the original balanced RGB ratio is disrupted, and the screen gradually shifts towards a mixture of red and green colors, leading to the red or pink tint we observe. This process typically becomes noticeable after 2-3 years of use.
Countermeasures
Unfortunately, the aging of OLED screens is an irreversible physical process, much like human aging – it cannot be stopped, only slowed down. The focus should be on usage habits and preventive measures.
- Avoid prolonged display of static images: Especially bright white or blue screens. If you need to work for extended periods, regularly switch screen content to allow different pixel areas to “rest.”
- Appropriately reduce screen brightness: High brightness accelerates the degradation of organic materials. Whenever possible, use lower brightness settings for normal use. Many devices have automatic brightness adjustment features; it’s recommended to enable them.
- Sensibly use dark mode: A dark background keeps most pixels in a low power state, especially black pixels which emit no light at all. This can significantly extend the screen’s lifespan.
LCD Screens Turning Yellow
Explanation of Causes
Unlike OLED, the reasons for LCD screens turning yellow are completely different. It’s crucial to note that LCD screens turning yellow is not due to burn-in. In fact, LCD screens do not experience burn-in. Burn-in is a phenomenon unique to self-emissive screens like OLEDs. LCDs display images by shining a backlight through liquid crystal molecules, so there’s no issue of individual pixels “burning out.”
The yellowing of LCD screens is primarily caused by the aging of various physical components that make up the screen. This is a slow but unavoidable process.
Aging of Physical Components
The yellowing problem in LCD screens can be attributed to the aging of three main components:
- Liquid Crystal Panel Aging is the most complex and difficult issue to address. Liquid crystal molecules undergo orientation changes under long-term electric field exposure, and some molecules may experience irreversible structural alterations. These changes affect light transmittance and polarization characteristics, leading to color shift. Liquid crystal aging usually manifests as an overall color temperature change, with the screen gradually appearing yellowish and warmer.
- Backlight Component Aging is the most common cause of yellowing. LCD backlights typically use LEDs or CCFL (cold cathode fluorescent lamps). These light sources will dim over prolonged use, and their color temperature will also change. The blue light component of LED backlights degrades faster, causing the overall spectrum to shift towards yellow-green. Backlight aging can manifest as yellowing in the central area of the screen, or an overall decrease in brightness accompanied by a change in color temperature.
- Optical Glue Aging primarily affects the screen edges. Optical glue is a transparent material used to bond the display panel and touchscreen. Under high temperatures, UV light, or other environmental factors, it undergoes oxidation, gradually turning from transparent to light yellow. This aging typically starts from the four edges of the screen and gradually spreads inward, forming noticeable yellow edges.
Generally, the backlight component is the first to begin aging because it has the heaviest workload, continuously emitting light and enduring heat accumulation.
Impact of Screen Yellowing
Yellowing is usually accompanied by decreased brightness, making readability poorer in bright environments. Users may need to increase brightness to compensate, which in turn accelerates the aging of other components, creating a vicious cycle. Screen yellowing can also affect eye comfort. While warmer tones can be more eye-friendly in some situations, non-uniform yellowing can cause visual fatigue, especially when requiring prolonged focused work.
Screen yellowing not only impacts the visual experience but also leads to practical usage problems. Firstly, color accuracy decreases, with white no longer appearing pure, affecting the viewing quality of images and videos. For professionals in design, photography, and other fields requiring high color accuracy, a yellowed screen can severely impair work quality.
Countermeasures
The yellowing issue with LCD screens is essentially hardware aging, and it cannot be fully repaired through software adjustments. However, depending on the specific cause of aging, there are some targeted solutions.
If it’s determined that backlight component aging is causing the yellowing, replacing the backlight module is the most economical and effective repair method. The cost of this repair is relatively low, and the technical difficulty is not high; many repair shops can handle it.
Optical glue aging can also be addressed. This requires disassembling the screen and re-applying the optical glue, replacing the aged material. However, this process demands higher technical skill, requiring a professional dust-free environment and precision tools, making the cost higher than replacing the backlight.
Liquid crystal layer aging is almost impossible to repair because it involves the core display structure of the screen. Even if technically feasible, the repair cost would be very high, usually not economically worthwhile.
When considering repairs, you need to comprehensively evaluate the overall value of the device and the repair cost. If it’s a high-end monitor or a device still under warranty, repair is worthwhile. However, if it’s an older device that has been used for many years, or if the repair cost is close to or exceeds half the price of a new device, it’s advisable to directly replace it.
For preventive measures, maintaining a good usage environment is crucial. Avoid prolonged exposure of the screen to high temperatures, regularly clean it to prevent dust accumulation from affecting heat dissipation, and reasonably set brightness to reduce the burden on the backlight. All these can effectively extend the lifespan of your LCD screen.
In summary, whether it’s the red/pink shift of OLEDs or the yellowing of LCDs, these are unavoidable issues in the development of screen technology. Understanding these principles and adopting appropriate preventive and remedial measures can help us better use and maintain our display devices.