Shim in the monitor - what is it?

Have you ever heard such a name as PWM monitor? Surely you would be interested to know what it is, especially if you find out that it can quickly tire your eyes.

Monitor shim - what is it?

Many people know that old CRT-based TVs flicker and thereby damage their eyesight, but few have heard that the flickering of modern displays is many times more dangerous.

It's true, a large number of modern displays flicker when operating. This effect occurs when the brightness level is lowered. This effect happens not only on PC monitors, but also on laptops, smartphones and other gadgets.

PWM is Pulse Width Modulation, which is a power control process by adjusting the duration of pulses at a set frequency.

To reduce the brightness level of equipment, you can use one of the following methods:

1. Reduce the lamp power. In this case, the lamp reduces the glow.
2. You can shine intermittently, this is necessary so that there is less light per unit of time. In this case, the lamp will flicker.

In the shimming technique, when you lower the brightness, the flicker becomes more noticeable, and this can negatively affect your eyes. The figure shows two methods for adjusting brightness.

When using this type of monitor, if you lower the screen brightness, flickering appears, and this may well cause your eyes to get tired more quickly.

Would you like to see the comparison features of the described methods? This can be seen in the picture below.

Is my monitor flickering?

There are monitors without shims or in which flickering occurs at minimum brightness. In the description of this technique you can find the inscription “Flicker-Free”. Translated, the inscription means that the equipment does not blink during operation, you can safely choose it for your purposes.

To test an existing monitor, you can use the “pencil test”. Take a regular pencil and move it against the background of the monitor from one side to the other, like a fan. If you see a blurry pencil mark, it means your technique does not have a flickering effect. If you see separated pictures, like a set of shadows, this indicates that shim is present. The test can be performed at different brightness levels. This will determine a safe brightness threshold to use.