PWM, or Pulse Width Modulation: PWM is a technology that uses invisible pulse flickering to regulate brightness in most existing displays, such as smartphones, TVs, or tablets. While typically imperceptible to the naked eye, it can impact visual health, causing symptoms like eye fatigue, headaches, and mental confusion, known as Temporal Light Modulation (TLM).
In summary, PWM emits light pulses when brightness isn’t at maximum, creating rapid flickering. Though not directly perceptible, it can affect the brain and pupils.
Evaluation of PWM on the Steam Deck: Understanding three potential eye fatigue triggers is crucial:
Trigger 1. Modulation Percentage (%): Higher percentages are linked to increased eye fatigue and headaches, especially at higher brightness levels.
Trigger 2. Waveform Type and Shape: Square waveforms in the graphics I’ll show can intensify flickering. Consistency in rises and falls is key for assessing its impact on your view.
Trigger 3. Duty Cycle Percentage: Panels with lower brightness and high modulation percentages often face more issues, common in Oled and Amoled panels. It’s advised to avoid a square waveform with a duty cycle of 75% or less.
Typically, for screens, it’s advisable to avoid square/complex waves with a duty cycle of 75% (comprising 75% ON time and 25% OFF time) and less to prevent eye fatigue. For a PWM-type screen, the duty cycle below 50% generally begins when lowering the brightness below 45%.
In the analysis of the Steam Deck LCD Antireflective Display, these criteria will be applied to determine the PWM panel’s quality.
Additionally, PWM hertz is crucial (not to be confused with screen hertz); defined as “the speed of luminous pulsations per second” at which our screen’s PWM flickers, allowing panel use even with a duty cycle below 75% and a modulation percentage above 10% within the risk zone. These aspects are crucial for understanding the impact of PWM on visual health. Our goal is to assess if the Steam Deck is recommended for extended gaming without causing eye strain.
To achieve precise measurements, two professional devices (The Opple Light Master Pro and the Radex Lupin) will provide data at four different brightness levels: 100%, 75%, 50%, 30%, 0%.
How to Interpret Measurement Results:
Modulation Coefficient in Percentage or Modulation Percentage (%):
- Radex Lupin: Indicates relative light variation during flickering. A higher coefficient means greater intensity variation.
- Opple Light Pro: Similar to Radex Lupin, Modulation Depth reveals amplitude fluctuation, with a higher Modulation Depth suggesting more pronounced variation.
Frequency:
- Radex Lupin: Represents flickering speed, i.e., how many flickering cycles occur per second. Higher frequencies are generally preferable (not to be confused with screen hertz).
- Opple Light Pro: Frequency also denotes flickering frequency, indicating cycles of on and off per second.
Interpreting Opple Light Flicker Graph’s Nits (Light Intensity) in the Flicker Menu:
- Horizontal Axis (Time): Indicates the time progression during the flickering cycle.
- Vertical Axis (Nits): Represents light intensity in Nits during flickering.
Interpretation:
- Continuous Line: Signifies smoother and less perceptible flickering. (When flat, the screen is flicker-free, 100% safe for the eyes)
- Pronounced Variations: Sharp peaks and valleys may indicate more intense flickering. In general, a smoother graph suggests less perceptible flickering, desirable for reducing visual fatigue. Observe line consistency and patterns indicating flicker stability at different brightness levels.
BRIGHTNESS AT 100%
First, we analyze the results obtained with Radex Lupin. The initial recorded value is 454 lux, which translates to nits, indicating a maximum brightness of 454 nits at 100% luminosity. This exceeds the 400 nits promoted by Valve for the LCD model of the Steam Deck screen.
In the second measurement, we observe a PWM modulation percentage of the screen at 5.35%. To provide context, safe flickering levels are generally below 10%, with levels below 5% considered ideal. In this case, the 5.35% indicates that, at 100% brightness, the Steam Deck screen is safe for the eyes. Although an ideal value would be below 5%, the result remains positive.
To understand this in practical terms: screen flickering occurs when the backlight rapidly turns on and off to adjust brightness. Radex Lupin’s flicker percentage indicates the proportion of time the screen is off in each flickering cycle. For example, 10% flickering means the screen is off 10% of the time and on 90% of the time. This value is crucial for evaluating the impact of flickering on visual health.
The following three images were measured using Opple Light Master Pro, revealing a brightness of 455 nits, matching Radex Lupin’s measurement. When analyzing flickering, we gain additional information.
The first image presents a color map where green indicates a safe zone for the eyes, yellow signals low risk, and red indicates high risk. Opple Light Master Pro, like Radex, suggests that the screen is in a safe zone, though not perfect, hence it falls into the yellow zone. This classification is because, although the modulation percentage is very low (2.76%), the PWM frequency is also very low, at 60 hertz. It’s important to note that recommended values to avoid fatigue are usually above 960 hertz.
In summary… Low-frequency values: bad for the eyes High modulation percentage values: bad for the eyes.
In this case, it doesn’t fall into the red zone because the low modulation percentage compensates for the very low flickering speed.
“To understand it more clearly, visualize the screen’s PWM like the blades of a functioning helicopter. In this case, the blades represent the screen flickering while it’s on. The analogy extends thus: the thicker and more opaque the blades, the more damage they can do to the eyes (indicated by the modulation percentage). Similarly, the slower the blades spin, the more visible they are, and therefore, they affect more (related to frequency)”
Now, let’s apply this metaphor to the example of 100% brightness that we are evaluating. The “blades” spin at a very slow speed (PWM frequency at 60 hertz), but they are very thin and transparent (low modulation frequency, in this case, 2.76%). This translates to a movement that does not significantly impact vision. It’s like having blades that spin slowly, but they are so thin and transparent that their impact on our vision is minimal.
Now, let’s focus on evaluating the last image, a graph that records the variation of nits or brightness over time. Despite being the last, its importance is not diminished.
Observing the graph, the 2.76% modulation frequency is reflected in minimal variation between maximum and minimum brightness. The line is practically straight, indicating that, despite the 60Hz PWM frequency, the sensation of flickering is almost non-existent (almost flicker-free). At this brightness level on our Steam Deck, we can confirm that the view is safe, as the brightness variation is minimal.
BRIGHTNESS AT 75%
At 75% brightness, we see that the screen registers around 253 nits, and in the second image, we observe that we have better flickering values than at 100% brightness. We’ve reduced it to 4.53% flicker. In the following three images, we will understand why.
Here is the key: Let’s carefully observe the last two images. Now, the modulation percentage is higher, but the PWM flickering frequency has experienced a notable increase, going from 60 Hz to 1100 Hz. This change is crucial because, even though the modulation percentage has increased to 8%, the higher frequency makes the flickering less noticeable compared to the 100% brightness level. (Helices un poco mas opacas y gruesas que antes pero que giran infinitamente mas rápido en el helicóptero, apenas las vemos)
The importance of evaluating both values becomes evident. This modification takes us from the yellow zone to the green on the visual risk map. That’s why Radex Lupin provides an even lower eye-safe value, supporting the transition from the yellow risk zone to the green.
In summary, the key lies in understanding how the interaction between the modulation percentage and frequency influences flickering perception. The data supports the idea that a higher frequency can counteract the effects of a higher modulation percentage, providing a higher level of visual safety. In this case, they are a clear testimony that we are not in the yellow zone but in the green, reaffirming that the joint evaluation of both values is essential.
Let’s see how these dynamics are reflected in our graph with time and lux data. When examining it, we notice that at 100% brightness, the trend was almost a straight line. However, by reducing the brightness to 75%, this uniformity is disrupted. There is a noticeable jump, manifested in variations between 249 and 268 over time.
This phenomenon correlates directly with the 8.38% modulation percentage. As evident in the graph, as this percentage increases, PWM flickering intensifies, negatively impacting the visual experience. The consequence is evident in the lack of consistency in the screen brightness. To maintain the 75% level on this PWM panel, luminosity needs to fluctuate abruptly with pulsations, generating those peaks and valleys in the graph. In this case, the higher 1100 Hz frequency saves the day, making the “PWM” cycle so fast that our eyes and brain struggle to notice them.
As you will see, this behavior will become more pronounced when we further decrease the brightness of the Steam Deck. With each descent, the modulation percentage value will increase, and the graph will reveal sharper peaks. Consequently, flickering will become more harmful to the eyes. The visual interpretation of these data provides a clear perspective on how the relationship between the modulation percentage and brightness level affects flickering stability and safety.
BRIGHTNESS AT 50%
Lowering the brightness to 50%, we reach an intensity of around 116 lux/nits and obtain the best value so far for comfortable gaming with Radex Lupin, at 4.70%. We continue within the most recommended values.
At a brightness level of 50%, according to our color map, the PWM frequency remains constant at 1100 Hz, just like in the previous test. However, there is an increase in the modulation percentage, reaching 15.7%. This indicates an increase in screen flicker. As seen in the third image, the variation in brightness values results in a somewhat steeper peak in our lux/time graph.
This evolution is reflected in the position of the green dot, which now approaches closer to the yellow limit line on our color map. Although it does not cross that threshold, we maintain our position in the green safe zone. The following third image provides a more practical visualization of this phenomenon; ultimately, the crucial point is that 1100 Hz continues to be a very high value. It successfully compensates for the 8% increase in modulation frequency, doubling it, making the flicker so fast that it is easily perceptible again, and we remain in the green zone rather than the yellow.
BRIGHTNESS AT 30%
By reducing the brightness to 30%, we move away from the safe zone of this PWM screen, and people with visual sensitivity could start to experience certain symptoms. Although not all, some could notice changes. This increase in risk is evident in Radex Lupin, where the percentage not only exceeds 5%, which would be ideal, but also crosses the threshold of 10%, where potential risks begin. The 12% that we record indicates that the screen flicker could become perceptible to certain people, a phenomenon that, as we will see later, tends to intensify and become more aggressive as we decrease the brightness until reaching 0%.
Radex measures us about 13.4 lux/nits
In the last two images, we notice that the frequency remains healthy at 1100 Hz, but unfortunately, it is not enough to compensate for the exponential increase in modulation frequency, which reaches almost 100%. This discrepancy is strikingly reflected in the final graph, where the notable peaks now transform into sharp knives that dominate almost the entire visual representation. The PWM and flicker are significantly intense, and although the frequency works quickly at 1100 Hz, it is not able to keep us in the green zone of the color map. Now, we slide slightly into the red zone, classified as “high risk of eye damage.” It is crucial to emphasize that this elevated risk applies to certain users and not necessarily to everyone, only to those sensitive to PWM screens.
BRIGHTNESS AT 0%
When measuring brightness at 0% with Radex Lupin, we obtain values not recommended for the eyes, with a high risk for individuals sensitive to PWM panels. The resulting percentage is 31%, three times higher than the recommended threshold to avoid unpleasant side effects in those who are sensitive. As we will see later, Radex provides us with a measurement of approximately 3 nits of brightness at the minimum. Subsequently, Opple will show us 4 nits, aligning with Valve’s claim about the minimum brightness. As a curious fact, the OLED panel has a minimum of 2 nits, being even less bright in dark conditions.
When evaluating brightness at 0% with the Opple Light, I conducted several tests to obtain precise measurements, and here are the values obtained. These results tell an intriguing story compared to Radex Lupin:
The modulation percentage remains nearly at 100%, indicating significant peaks in brightness on our graph in relation to flicker. However, Opple, if not mistaken, records an increase in frequency, going from 1100 Hz to an impressive 32000 Hz. Despite the high modulation, the extremely fast cycles per second compensate for this value. According to Opple, we re-enter the green zone, supposedly meaning “no risk.”
In the nits and time graph, we observe these data as small brightness peaks followed by moments of complete darkness. Although the reliability of this reading may be questioned, it could explain the 32000 Hz frequency. According to Opple, 0% brightness should not affect the eyes, but according to Radex, it could be harmful. This contrast is more evident when compared to the brightness analysis from 1% to 30%, where it definitely falls into the risk zone regarding PWM perception. I leave the conclusions about which value holds more weight in this last section to your judgment.
CONCLUSIONS FROM MY ANALYSIS: The Steam Deck’s Anti-Reflective LCD panel has proven to be an excellent choice for enjoying long gaming sessions without fatigue, especially when maintaining brightness around 50%. However, the data reveals that below 30%, the PWM screen flicker could become noticeable and bothersome for those more susceptible than I am to this phenomenon. Associated symptoms could include nausea, rapid discomfort or eye fatigue, a sensation of grittiness in the eyes, migraines, and general fatigue.
It is important to note that each individual reacts differently, and although the measured values here provide an objective and recommended range, the response may vary from person to person. If you are particularly sensitive, the 60 Hz at 100% brightness or values below 30% with significant modulation may affect you. In my personal experience, I consider it one of the best IPS panels for gaming without discomfort, but these data may be useful for those who do not share my experience.
In a week, I will conduct a similar analysis with the OLED screen of the Steam Deck, which, being OLED instead of IPS, will likely yield different results.