Dimming & Eye Health: From PWM to DC Dimming
Pulse Width Modulation (PWM) dimming is a commonly used technique to control the brightness of display backlights. It involves rapidly turning the backlight on and off at high frequencies. While effective in adjusting brightness, low-frequency PWM poses significant risks to eye health.
Low Frequency PWM: Standard with caveat
When the PWM frequency is low, the human eye can perceive the rapid flickering, leading to a range of eye problems. Symptoms such as eye strain, fatigue, headaches, and dry eyes are commonly associated with prolonged exposure to low-frequency PWM displays. Furthermore, it can contribute to blurred vision and difficulty focusing.
High Frequency PWM: A Partial Solution
To address the issues associated with low-frequency PWM, manufacturers shifted towards higher PWM frequencies. At sufficiently high frequencies, the flickering becomes imperceptible to the human eye, reducing eye strain. However, this solution is not without its drawbacks.
While high-frequency PWM minimizes the direct impact of flickering, it does not eliminate the underlying principle of rapidly turning the backlight on and off. Some individuals, particularly those with sensitive eyes, may still experience eye discomfort even at high frequencies. Additionally, there are concerns about potential long-term effects of prolonged exposure to high-frequency PWM, although definitive research is still ongoing.
DC Dimming: The Optimal Solution
DC dimming offers a superior alternative to PWM by providing a steady and consistent light output. Unlike PWM, which relies on rapid switching, DC dimming directly adjusts the voltage supplied to the backlight, resulting in a flicker-free viewing experience. This technology is significantly gentler on the eyes, reducing the risk of eye strain, fatigue, and other related issues.
To further enhance the visual experience, combining DC dimming with a high number of brightness levels, such as Redmi Pad Pro’s 4096 level dimming, provides exceptional control over screen illumination. This allows users to fine-tune the display to match ambient lighting conditions, reducing eye strain caused by excessive brightness or insufficient light.
Further reading:
Eizo – How to address computer-related eye fatigue
PWM & DC dimming Conclusion
In conclusion, while PWM dimming has been the industry standard for controlling display brightness, its potential negative impact on eye health cannot be ignored. DC dimming offers a clear advantage by providing a flicker-free and more comfortable viewing experience.
| Feature | Low Frequency PWM | High Frequency PWM | DC Dimming |
| Dimming Method | Rapid On/Off Cycles (Visible to eye) | Rapid On/Off Cycles (Invisible to eye) | Voltage Adjustment |
| Flicker | High | Low | None |
| Eye Strain | Likely | Possible (for sensitive eyes) | Low |
| Color Accuracy | May be affected | Less affected | Maintained |
| Power Consumption | Efficient | Efficient | Less Efficient |
As technology advances, the adoption of DC dimming with high brightness levels is crucial for prioritizing user well-being and visual comfort. The Redmi Pad Pro 5G feature DC dimming to provide user better eye-health during usage. One thing we also notice is how big difference is the power consumption is between full brightness and 50% brightness of DC dimming. Check out our review for more information:
