Flicker-free technology
It is a way to reduce monitor flicker for people sensitive to it. The flickering of a fluorescent lamp is the main cause of this, so using an electronic ballast in place of the traditional magnetic ballast can help eliminate much of it. This also reduces power consumption by the monitor, improving the environmental impact.
This product does not use pulse width modulation technology to save power. Originally used for CRT displays, it has been proven to be unhealthy after extended periods of use.
These days it is mostly used as a buzzword term by the electronics industry, but you will want to be very cautious if a manufacturer mentions a new product as a "flicker-free" device because they might just be trying to take advantage of consumers who don't know any better.
Flicker-free monitors are designed to prevent repetitive changes in brightness from being sensed by users, specifically "the effect that occurs when a user's eye integrates periods of darkness and light into continuous perception."
PWM - what is it?
Pulse Width Modulation (PWM) is a modulation technique used to encode analog signals into digital signals. Because of its ease of implementation in digital circuits, PWM has become the most widely-used method for controlling power to electrical devices such as motors and appliances.
Flicker-free monitors are designed to prevent repetitive changes in brightness from being sensed by users, specifically "the effect that occurs when a user's eye integrates periods of darkness and light into continuous perception."
Comparison of PWM and flicker-free monitors
Listed below are some pros and cons of PWM technology versus flicker-free technology.
Pros for flicker-free monitors over PWM:
- The noise-canceling algorithm eliminates flickering related to voltage changes.
- This is especially effective against the 24 Hz flicker frequency commonly found in display backlights used on laptop computers due to its small size, which prohibits the use of large high-frequency transformers.
- It can run with a high refresh rate without causing eye strain or fatigue due to the reduced intensity of the light source.
- Excellent color rendition with no pulsation or modulation visible during operation.No ghosting effect caused by backlight pulse width modulation around moving images offered around the screen.
Cons for Flicker-free monitors over PWM:
- A flicker-free monitor may have a slightly higher response time. Flicker-free technology is designed from the ground up to offer 100% flicker-free operation, including all aspects of its function - especially during gaming.
- Flicker-free monitors are offered with RGB LED lighting and not CCFLs for better color rendition and power savings.
- It offers a fully adjustable stand capable of tilting or pivoting out to portrait mode for ideal viewing comfort.
- The manufacturer will further go above and beyond in customer service because you aren't just a product number to them - you're a human being receiving their help.
Do brightness settings matter?
When it comes to PWM, you only need to worry about the brightness of your screen. If your screen is too bright or dim, you will experience some flicker.
On a flickering free monitor, there are two options available on most models: High and low frequency which refer to how many times the light source flashes per second on the monitor. The high-frequency setting provides better color production than the low-frequency one does with less flicker.
It may cause eye strain however when used for long periods at this higher brightness level.
Some manufacturers say that their flicker-free technology eliminates all flicker but in reality, they just reduce it by half so they can promote brighter colors and stand out against competitors marketing similar products.
If you are someone who is sensitive to flicker or has a form of photosensitive epilepsy, then the best option for you would be using either an LCD monitor with PWM or LED lighting. You can also look up your product manufacturer's website for model-specific information on whether the device includes PWM or flicker-free technology.
How can you know your monitor uses PWM?
Don't rely on your manufacturer's website for accurate information about how the device you are purchasing works.
Manufacturers often mislead consumers into believing that their PWM technology is flicker-free, even if it isn't. You need to do your research beforehand so you don't end up with a weak-performing monitor, causing pain and eyestrain after extended use.
Some will tell you that they've done away with PWM altogether, but instead use DC (direct current) modulation for brighter colors at high brightness levels.
However, these monitors still produce undesirable flashing effects when changing video content or moving images around the screen because they are using "high frequency" pulse width modulation which does little more than double the number of flashes per second in an attempt to provide better color rendition.
In the end, you need to look at a monitor's specs and determine its flicker technology before making a purchase. While only a few manufacturers will tell you exactly how their products work with PWM or flicker-free lighting, most will not be completely honest about the quality of their products.
If this is something that really concerns you, then I recommend using an LED-backlit monitor with DC modulation as it has been proven to provide excellent color reproduction without flickering issues even when viewed from varying angles.
With that being said there are still some monitors which do use PWM but have been reported as having little or no visible flickering after extended periods of time (a decade). It is possible for your body to get used to it, but most people will experience some degree of eye strain after long periods of use.
It is also worth mentioning that you can always return the monitor if you notice any flickering on your new LED monitor. Don't let yourself be fooled by what you read on a manufacturer's website or purchase something just because it is priced lower than the competition unless the performance is your number one priority.
Screen flickering is worse when set at lower frequencies
The higher the color refresh rate of your screen, the less noticeable flicker becomes because certain colors tend to blend together better than they would on a standard display. This means that if you have an eye for detail and notice flickering almost instantly, then you will want to pick up a device with high color quality (and probably better-viewing angles).
If you aren't worried about this though, then there is no need to waste money on additional features. Most people don't even know the difference and will be perfectly happy with a monitor that includes PWM.
Screen flickering is not as bad on laptops or very large monitors
It may even be easier to adjust to on larger screens because you won't notice it as much, but your eyes can still get tired very quickly if you are using them for extended periods at high brightness levels (closer to the maximum lumen output). The same thing goes for older people who have less light sensitivity than those who are younger, due mainly to decreased blood flow and cell reproduction in the eye.
Cordless phones also use pulse width modulation technology which can cause interference with a flicker-free monitor, so avoid placing one near a cordless phone if possible.
Pulse width modulation is also used in most flashlights today which can cause a similar reaction. There are ways to make a flashlight flicker-free, but they aren't cheap and your typical LED flashlight will be prone to flickering especially if its brightness is adjusted rapidly.
Take your flicker-free monitor and plug it into an outlet that was flickering?
This would not damage you in any way because they either use PWM or DC modulation. LED-backlit screens can be very sensitive to certain frequencies, but most newer models will work fine with flickering outlets because they are designed to detect this type of lighting frequency and adjust accordingly.
Is DC modulation immune to screen flicker?
Not necessarily. Even though the backlight itself does not flicker, some manufacturers (mostly outside of North America ) still use PWM technology for dimming purposes. If that is the case then you should notice some flicking taking place after running a static image on the display for an extended period of time while using your computer's brightness controls at their lowest setting.
However, if you have tried all monitor settings and nothing seems to work, then you can try dimming the backlight yourself to see if that fixes the issue.
You should be able to find this control within your monitor's OSD (on-screen display) settings which are usually reached by hitting the menu button on your keyboard or scrolling through at least one sub-menu using your mouse.
You will usually notice that the flicker comes back if it was truly flickering during use and that should help you to narrow down what setting you need to change. Pulse width modulation is also used in most flashlights today which can cause a similar reaction.
Conclusion
Flicker-free monitors have a lot of advantages especially for those people who have the eye for detail. For normal uses, you should always buy a screen with higher color quality because it will be easier on your eyes and less noticeable even if you don't notice it at first.
We should also take into consideration that some devices that use PWM technology may cause interference which can only be solved by disabling or avoiding flicker frequencies from other electronic devices such as cordless phones and old desktops.