Tuesday, March 18, 2008

BenQ FP241WZ First LCD BFI monitor

BenQ FP241WZ, the first BFI monitor… isn't a BFI, a 100 Hz or 120 Hz.
BenQ pulled off an amazing trick. At the CeBit they unveiled a technology called BFI, which stands for Black Frame Insertion. As its name implies, the principle relies on the insertion of a black frame between two colored images to reduce the afterglow due to retinal persistence. The surprise is that this isn't what has been implemented in the BenQ monitor. Our tests (and first of all our eyes), are proof that the technology introduced to the FP241WZ looks very much like a sort of MPA (Motion Picture Acceleration), unveiled by Samsung at the last CeBIT. These two technologies are quite different.

First of all, the BFI denomination isn't really common knowledge yet. In announcements to the general public, BenQ prefers to call it AMA-Z. AMA for them simply corresponds to the overdrive. The Z indicates that the BFI has been implemented. This AMA-Z (in fact the BFI only) is available via the OSD and can be activated on three different levels (0, 1, 2 and 3).The higher it is, the more important the afterglow correction (we will come back on this point later on).

And is it a 100 or 120 Hz? There is some confusion in this area due to documents provided by BenQ. We have to point out that they haven't written anywhere that the monitor works with a frequency of 100 or 120 Hz. The misunderstanding comes from a significant imprecision in the manufacturer’s data sheet. BenQ described the BFI as a mode with 60 frames per second with black frames inserted each time. We could come to the hasty conclusion that the monitor “artificially” increases the frequency from 60 to 120 Hz. This figure would simply represent the alternance between color and black frames. However, this isn't what is happening at all. BenQ doesn't insert a black screen, but rather BFI consists of integrating an artificial screening by successively shutting down the 16 neons located in the back of the panel. It doesn't mean that the monitor is less interesting, but only that the approach and principle are completely different. The BenQ FP241WZ is the first LCD with a screening like we used to have on CRTs. Now the question is: will it have the same reaction time?
A little aside: Samsung did the same thing with 100 Hz
The funny thing is that Samsung, who is at the origin of this other major innovation, the 100Hz, made even more mistakes in their explanation. We read all sort of things about 100Hz even on their website. At times, it added 10 images per second, or it introduced black frames by turning off the backlighting for every other image. However, this isn't the case and as we explained, Samsung’s 100Hz is a real 100 Hz with a processor devoted to the calculation of an intermediate image inserted between the two sent by the video source. For more information, take a look at the test of the LE40M73BD TV.
The screening in pictures
What a surprise! We thought that we would obtain black images and here are two results chosen randomly with the AMA-Z function activated:

If we take dozens of pictures, we in fact see an entire series of intermediate steps, which you can see when they are side by side:

1 - 2 - 3... 16 steps = there are 16 neons in the back of the panel. This corresponds also to what Samsung explained to us about their 24”. We noted that the two neons located at the two most extreme positions are shut down simultaneously. Upon further analysis, we took into consideration that the tubes are shut down successively.


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