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Screen Flickering. Is this normal?
06-27-2019, 07:42 PM
Post: #1
Screen Flickering. Is this normal?
Hello fellow HP enthusiasts,

I've recently acquired an HP Prime G2 from an UK seller, but the screen seems to have a lot of jitter whenever it's scrolled, mainly in the Home and CAS screens.

Here it is: https://youtu.be/v9V_jHZpJrc

It's not very noticable on video but it makes me crazy. Updating the firmware didn't help either. Does anyone else have this problem or is my unit possibly defective?
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06-27-2019, 10:05 PM
Post: #2
RE: Screen Flickering. Is this normal?
Moderator note: For anyone that might be concerned, the video is legit. No issues I found when viewing it.
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06-28-2019, 05:30 AM
Post: #3
RE: Screen Flickering. Is this normal?
Hello,

Are you seeing flickering (as in you see the screen refresh happening)?
or sheering, which happen when you see the screen being redrawn by the software as you scroll it?

We found that some people are more sensitive to these effect as others, and of course it depends on the lightning...

Strong, intermittent lighting such as most fluorecent lighting, but also a lot of the LED exacerbate the problem. We tried to mitigate it by selecting a screen refresh rate that does not sync with either the European 50Hz nor the american 60Hz... But as I said, some people are more sensitive to it than other (let us say that their eyes have "faster shutter speed")...

As for sheering, this is a purely software issue, but here again, there is a balance, removing/hiding the sheering makes the software more complex and slows down the system. It is also problematic when some objects are long to display.
This is why the software does not use double buffering...

Cyrille

Although I work for the HP calculator group, the views and opinions I post here are my own. I do not speak for HP.
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06-28-2019, 06:24 AM
Post: #4
RE: Screen Flickering. Is this normal?
It is a strange issue.

A few weeks back after doing an upgrade (don't know if it is caused by the firmware upgrade), I saw a lot of flicker. It gets worse when brightness is increased. I was even considering to buy a 50g since it doesn't have a back-light (still considering to buy one.. but that is because I'm a nerd). I have my calculator for almost 1.5 years and before I never found it an issue.

But after a few hours of serious irritation, somehow it passed. It could be the LED lights I was sitting under and I also reduced brightness. I'm using my calculator daily and I'm not bothered by it any longer. The issue also seems to be worse with the dark theme.

I do not have the newest version (with the improved CPU), but the version before that.

ps:
I'm very sensitive to flickering lights. Even though my monitor doesn't make use of PWM, I can still see the flicker on my screen. The more I focus on it, the more it irritates me. I sit at least 8h a day behind a screen since I'm a software engineer.
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06-28-2019, 01:30 PM (This post was last modified: 06-28-2019 10:32 PM by victorvbc.)
Post: #5
RE: Screen Flickering. Is this normal?
I think it's more of a redraw problem than the screen itself failing (the LCD passed the test on recovery mode), maybe I used the wrong term. The calculator does seem more unstable since I did the 2018-10-16 firmware update, I saw it crash and clear memory a few times.

Found this thread later here in the forum: http://www.hpmuseum.org/forum/thread-101...l#pid91020

So maybe it is a common issue?

Edit: Another thing that has been happening is the calculator resets itself after coming out of low power mode (hold shift + off) every time, which causes me to lose all my programs. I can see "Your HP Prime had a problem and will reboot in 3 seconds" when it tries to boot, while the backlight is still off.
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07-01-2019, 08:49 AM
Post: #6
RE: Screen Flickering. Is this normal?
(06-27-2019 07:42 PM)victorvbc Wrote:  It's not very noticable on video but it makes me crazy. Updating the firmware didn't help either. Does anyone else have this problem or is my unit possibly defective?

Yeah, is kinda normal at least in the non G2 version. I do not have a G2 to test but your video looks like the flicker I remember.

My website: erwin.ried.cl
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07-01-2019, 07:15 PM
Post: #7
RE: Screen Flickering. Is this normal?
I have g2 hardware, and having screen flickering especially when scrolling to the last line. Is it normal?
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07-02-2019, 05:44 AM
Post: #8
RE: Screen Flickering. Is this normal?
Hello,

Are you doing kinetic scrolling (ie, scroll very fast and let the system scroll while you are not touching the screen anymore)?

My guess is that the system is trying to continue redrawing, but just redrawing at the same spot, however, the redraw is done by erase/draw, and this might be what you are seeing...

Cyrille

Although I work for the HP calculator group, the views and opinions I post here are my own. I do not speak for HP.
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07-02-2019, 07:04 AM
Post: #9
RE: Screen Flickering. Is this normal?
Ok. It is normal then. Thank you.
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07-03-2019, 04:44 AM
Post: #10
RE: Screen Flickering. Is this normal?
Hello,

In some ways, yes, some flickering is normal...
But some flickering might be abnormal. For example a failing back-lighting system might cause extra flicker (more than the normal)...
however, it is always hard to find out what people are talking about with flickering...

Anyhow, we have tried to minimize flicker, but it is not an easy task...

In a game, for example, developers will do screen synchro to reduce the type of flicker called tearing...
But they can do it because they are a relatively constant redraw speed.
But this is not the case in the calc. Some math object can be much slower to draw than others. you can see it sometimes in the stack where the bottom of the stack first draws, then there is a "pause" as the complex/slow object is calculated, then drawn, and then the rest of the stack...
Adding screen synchro would mean that the "display" would apear at once when all is calculated... this would cause a sensation of "slowness"... this is why we do not have screen synchro for things like that.

Cyrille

Although I work for the HP calculator group, the views and opinions I post here are my own. I do not speak for HP.
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07-05-2019, 11:07 PM
Post: #11
RE: Screen Flickering. Is this normal?
It happens mostly with kinetic scrolling and side scrolling in the home/cas screens. I never noticed it in the plot view of any app. The numerical view has it sometimes, but it's much less noticeable.
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