Articles: Monitors

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One more note. I measure the time it takes a black pixel to turn on and off again (from complete black to complete white and back again), but switching between two shades of gray may take more time, thus producing noticeable blurring. I am going to address this issue in one of the upcoming articles by showing the relation between response time and the initial and terminal states of the pixel.

Viewing angle is yet another important characteristic of an LCD display, but we don’t have any equipment at our disposal to measure it yet. Anyway, I am putting down my subjective impressions about it. Some displays don’t comply with their own specs in this respect, which can be easily seen with a naked eye.

The last thing to discuss before going over to the tests is the pulse-width modulation of the backlight lamps with a frequency of 200Hz – 1kHz. The question is whether this flicker strains the eyes. On the one hand, the frequency is rather high, but on the other – some people say they notice this flicker when working with the display for a long time. So, I carried out a brief test. After unpacking and turning on each display, I worked in a word processor (white background, black text) for a quarter of an hour. Then I tried to guess, listening to my own impressions, whether there was any flicker. Then I connected the oscilloscope and the sensor and checked whether my impressions reflected the reality adequately. The result surprised me a lot: I was only wrong with two displays, Samsung 171S and Sony SDM-X72. I guessed that the first one had no flicker, while the oscilloscope said it had modulation with 540Hz frequency (this is quite high, and that’s why I was wrong). For the latter I thought it had a flicker and it did have it, but not from the backlight lamp… We will discuss this phenomenon later in the article. For all remaining displays with pulse-width modulation of the backlight lamp (those from NEC) my guesses were correct. It means that the eye subconsciously perceives modulation of the light stream even if it is performed with 200-300Hz frequency. I won’t claim that it leads to higher eyestrain (this is a too subjective factor), but you may want to pay attention to this characteristic when choosing your display.

The last preliminary note concerns the cases of the displays. Few of them allow using the display in the portrait mode or mount it on the wall. But this limitation exists only when you use the monitor’s own base. There is a standard for fastening the base to a display called VESA – a square with 75mm-long sides and four holes in the corners. Most displays comply with this standard. In other words, you can simply buy another base from a third-party manufacturer and fasten it to the display with four screws.

Now, let’s wind up the introduction and get to the testing participants.

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