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HP Forum Archive 10

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Screen contrast on HP 19BII
Message #1 Posted by Nick Nicholas on 2 Feb 2003, 3:39 a.m.

The screen contrast on the 19BII that I have seems to be worse than the 17BII. On the 17BII, the numbers are dark black on a relatively light background. On the 19BII, in order to get the same darkness of the foreground, the background is much darker than on the 17BII. Pressing the on and -/+ keys do not improve the situation on the 19BII. Can someone confirm that this is the case or does my 19BII have a defective screen?

      
Re: Screen contrast on HP 19BII
Message #2 Posted by Christof on 2 Feb 2003, 4:41 a.m.,
in response to message #1 by Nick Nicholas

I'm not entirely positive, since I can't see your LCD, but I'm fairly sure it is not defective. the Champion LCDs seem to have a lower absolute contrast value than most other HP LCD screens- vastly worse than the 32Sii, a bit worse than the 42/17 pioneers.

I find that the viewing angl emakes a huge difference, though

      
Re: Screen contrast on HP 19BII
Message #3 Posted by Gordon Dyer on 2 Feb 2003, 7:19 a.m.,
in response to message #1 by Nick Nicholas

Unfortunately this is related to the LCD technology of that time.
The first multiplexed screens with many pixels did not give good contrast and the more pixels which had to be multiplexed the lower the contrast. This is why the 7 segments are the best, the 1 line screens like the 32SII are next best, the 2 line 42s and 17BII are next best and the 4 lineers like the 19BII are the worst!
Today the LCD technology is vastly improved giving enough contrast for a clear display even when multiplexed, but often the TFT screens have a driver transistor per pixel built in so they are the best.
There is no excuse for HP's new calculators to have low contrast screens - unless they are penny-pinching (make that dimes).

            
Re: Screen contrast on HP 19BII
Message #4 Posted by Nick Nicholas on 2 Feb 2003, 4:29 p.m.,
in response to message #3 by Gordon Dyer

My HP 19BII was manufactured in 2000 with the relocated battery cover so HP had the opportunity to improve the screen but choose not to probably for cost reasons.

      
Re: Screen contrast on HP 19BII
Message #5 Posted by Rick on 2 Feb 2003, 8:57 a.m.,
in response to message #1 by Nick Nicholas

I own one of the earliest models of 19bII and can tell you that the early models have better contrast than the newer models.

            
Re: Screen contrast on HP 19BII
Message #6 Posted by Gordon Dyer on 2 Feb 2003, 1:06 p.m.,
in response to message #5 by Rick

Personally I have never tried full immersion and also feel wary of it, but I am sure it will cause problems with the LCD.
I guess if the water is well dried out as suggested and you do not immerse for too long it should be ok, but the porosity of the plasic encapsulation for ICs should protect them for about an hour, and keeping it warm will get the juice out faster. Than you should dry it as suggested within an hour.
Good Luck! It is better to try this than have a permanently disables calculator.

                  
Re: Screen contrast on HP 19BII
Message #7 Posted by Gordon Dyer on 2 Feb 2003, 6:47 p.m.,
in response to message #6 by Gordon Dyer

Sorry, this went in the wrong place!


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