6. Using The Twinhead Durabook N15RI: The Display

Note: These tests were done before the torture tests discussed below.

The display on the Durabook N15RI I tested was a bit unusual in that it was OK at higher brightness levels, but not so good at the lowest two levels. For example as I tried to set the notebook's display for the BAPCo MobileMark 2005 battery life tests, I found myself working with a screen with a brightness of nearly 90 candelas per square meter (cd/m^2) on the right side, 60-70 cd/m^2 in the middle and as low as 43 cd/m^2 on the left. The differences balanced out to the 60-70 cd/m^2 required by MobileMark 2005, but the screen was divided into three unmistakable vertical bands of brightness. This could be due to the age of the fluorescent display backlight or to the one-too-many-drop-tests syndrome.

Fortunately at higher brightness levels, including the maximum brightness setting the screen showed far less banding. As you can see in the first chart below the Durabook's brightness is fairly even, ranging 40 cd/m^2 between 120 and 160 while dropping some at the edges and peaking in the center. The mean brightness of the display, by the way, is 139. This is quite good for a notebook in this class.

The N15RI was unable to produce really dark blacks. The average of the 64 measurements of black on its display is 1.58 cd/m^2. That's quite high compared to notebooks with really good black capabilities averaging maybe 0.4 cd/m^2. So, given that a display's contrast ratio is the average of its white measures divided by its black measures, the Durabook, with its high black scores, gets a pretty low contrast ratio score of 90. And as the second chart below shows, the N15RI's contrast ratio is fairly rough and uneven, ranging from 70 in the middle to 140 (actually 132) nearer the edges. Note that this is exactly the opposite of the brightness measures. This happens because, while the display is at its brightest toward the center, its center blacks are also quite bright.

Despite the N15RI's low contrast ratio the display was still quite easily readable indoors under all lighting conditions and outdoors in deeper shade.