Beijer Electronics (formerly QSI Corporation)

Manufacturer of Mobile Data and Human Machine Interface Terminals.
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 Post subject: G55 and Z60 LCD burn-in
PostPosted: Mon Jul 17, 2006 4:38 pm 

Joined: Tue Jul 11, 2006 12:05 pm
Posts: 3
Location: Melbourne, FL, USA

After spending a couple weeks with a G55 and Z60, I must say I am very impressed with both the hardware and the software.

We have a little bit of concern for the LCDs in both units though. We've noticed that if we leave an image on either LCD for a few hours (big text, for example) a ghost of the image is visible in the hardware setup screen after messing with the contrast for a bit.

This ghost will persist even after powering off the unit for a while.

Our EE speculates that there may be an unwanted DC component in the AC bias voltage across the pixels of the display.

We don't want to use a screen saver in our project. I guess my question is whether the image burn-in will become more pronounced with time to the point that it will be visible even at normal contrast settings.



 Post subject:
PostPosted: Tue Jul 18, 2006 6:48 am 
QSI Support
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Joined: Wed Mar 08, 2006 12:25 pm
Posts: 881
Location: Salt Lake City, Utah
If the image on the display remains static for an very prolonged period of time, you may eventually begin to notice minor distortion in the image, even at normal contrast levels.

In my experience, this is not permanant. Turning off the display, or changing the display image will eventually fix the problem, although this may take a few hours to a few days depending on how long the original image was shown.

Both the G55 and the Z60 are available with a couple of different displays (G55 in color and grayscale and the Z60/H and Z60/L) which display different image retention characteristics. However, in at least two of the cases, and possibly all of them, the display manufacturers recognize that image retention is inherent in the display technology used and recommend that you not display a constant static image on them.

In practice I have noticed forms of image retention on the Z60/H display (after several days of inactivity) and the G55 grayscale display (much more quickly). I personally have little experience with the Z60/L display and the G55 color display does warn about the possibility of image retention, but in practice I have never observed it.

For this reason, the ScreenSaver object is automatically included in each workspace created by Qlarity Foundry. If you don't want the "dancing lines" functionality, you can disable that by setting the LaunchScreenSaver_Time property to 0. This will retain the "blanking" functionality.

Another option which a few customers have used on grayscale G55s is to design an application that principally uses the colors black and white and then invert the display (white becomes black, black becomes white) periodically. This works quite well in situations where blanking the screen is not acceptable. It is also fairly straightforward to program in Qlarity. A similar technique can be applied to the Z60, although care would have to be given to appropriate color selection that looked good on all color schemes and still gave the various red green and blue sub-pixels a chance to relax.

I will also forward your comment about the DC voltage to one of our electrical engineers, however, I suspect that you are simply seeing artifacts of the display technology used.


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