- Pulse width modulation (PWM) and mains power frequency are the main causes of flickering in LED screens.
- Adjusting the refresh rate in the operating system and updating drivers can stabilize the image on monitors.
- Deactivating ambient light sensors and manually controlling brightness prevents sudden changes in brightness.
- Synchronizing the camera's shutter speed with the current's hertz eliminates horizontal banding in recordings.
I'm sure it's happened to you: you're focused on working or playing, and suddenly the screen starts flickering or changing brightness in a way that drives you crazy. This phenomenon, technically known as screen flicker , can come from many sources, from a software glitch to the way the hardware manages light, and it's a pretty common headache these days.
The curious thing is that it's not always a panel defect; sometimes it's simply that the device is trying to be "too smart" by adjusting the brightness according to the environment or using energy-saving techniques. To fix it, you have to tackle the problem from several angles , whether by tweaking Windows settings, accessing the computer's BIOS, or adjusting the camera if the flickering only occurs while recording.
The mystery of LED flickering and PWM technology
To understand why this happens, we need to talk about Pulse Width Modulation, or PWM. LEDs can't gradually reduce their intensity, so they turn on and off at such a rapid pace that our eyes don't notice it, but the brain perceives that there is less light. The problem arises when a camera records at a speed that coincides with these micro-off periods, capturing some dark frames and others that are light.
If you're recording content and see this effect, the most effective solution is to increase the brightness to 100% . Doing this stops the PWM controller from cycling on and off, and the LED shines continuously, eliminating the flickering altogether. Additionally, it's crucial to adjust the shutter speed to a multiple of the electrical frequency in your area (60Hz in America or 50Hz in Europe), thus preventing those unsightly horizontal bands from appearing in the video.
Software settings and refresh rate in Windows
When flickering occurs while using your PC, the key often lies in the refresh rate (Hz). The refresh rate is the number of times the monitor redraws the image per second. If this rate isn't correct or there's a conflict, you might notice visual instability. Ideally, you should verify that the refresh rate is set to 60Hz, which is the most stable standard for most LCD panels.
To change this in Windows 10, you need to go into the advanced display settings and, from the adapter properties, select the refresh rate that best suits your monitor. If the problem persists, don't forget to update the graphics card and monitor drivers through Device Manager or by downloading the latest version from the manufacturer's official website, as an outdated driver can cause communication problems with the panel.
The problem of automatic dimming and the light sensor
There are cases, quite common in Dell laptops and other similar models, where the screen seems to have a mind of its own and changes brightness randomly . This isn't a malfunction; the ambient light sensor (ALS) is simply trying to adjust the brightness to the surrounding environment. If you're near a window with passing clouds or under an old, flickering fluorescent light, the sensor goes haywire, causing the screen to constantly dim and brighten.
To stop this at its source, you can first try environmental adjustments, such as closing the blinds or moving away from unstable lighting. If that doesn't work, the definitive solution is to prevent the screen brightness from changing on its own by disabling the ambient light sensor in the BIOS. Simply restart your computer, press F2 (or the corresponding key), and change the ALS status to "Disabled." This will make brightness control completely manual again, and the panel will stop making those abrupt adjustments.
Optimization for mobile creators and users
If the flickering only occurs when recording with your phone, the situation is different. On iPhones, HDR video can amplify the effect, so disabling HDR in the camera settings often helps. Likewise, avoiding slow-motion modes (120fps or 240fps) is crucial, as they capture the LED switching cycle much more precisely, making the flickering aggressive and potentially causing the phone's screen to flicker.
On Android, the advantage is that many phones have a Pro mode. Here you can manually set the shutter speed (denoted by an "S") to 1/50 or 1/60 depending on your region. If you don't have these options, there are third-party apps that allow complete control over the sensor. For those using decorative displays like those from Divoom, the golden rule is to keep the brightness at maximum during recording to override PWM.
Solving flickering involves understanding whether the cause is the monitor's refresh rate, battery power management, the ambient light sensor, or the interaction between the PWM and the camera. By adjusting the refresh rate in the system, disabling automatic functions in the BIOS, and synchronizing the video shutter with the electrical current, it's possible to achieve a stable and comfortable image on any device.
Passionate writer about the world of bytes and technology in general. I love sharing my knowledge through writing, and that's what I'll do on this blog, show you all the most interesting things about gadgets, software, hardware, tech trends, and more. My goal is to help you navigate the digital world in a simple and entertaining way.