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G2 screen refresh rate (20200121)
01-23-2020, 09:42 AM
Post: #1
G2 screen refresh rate (20200121)
I have a question about the G2 screen refresh rate.
Push On, push Shift and keep both touched, with + and - the refresh rate can be increased or decreased.

1-
What are the minimum and maximum refresh rates?
2-
What are the advantages and disadvantages of a low and a high refresh rate?
Such as processor time, battery drain, etc ?

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01-23-2020, 10:32 AM
Post: #2
RE: G2 screen refresh rate (20200121)
I'd guess that this was made possible so that you can shift the refresh rate even further away from the local AC frequency of your country.

AC is 50Hz or 60Hz depending on where you are, so HP settled on a 55Hz refresh rate so that it shouldn't be affected by fluorescent lighting. If there are, however, some lingering effects then you can get closer to a 50Hz refresh rate if you're in an area where AC frequency is 60Hz, or closer to 60Hz if AC is at 50Hz where you are.

This said, I don't know what the boundaries are.

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01-23-2020, 10:56 AM
Post: #3
RE: G2 screen refresh rate (20200121)
(01-23-2020 10:32 AM)grsbanks Wrote:  I'd guess that this was made possible so that you can shift the refresh rate even further away from the local AC frequency of your country.

AC is 50Hz or 60Hz depending on where you are, so HP settled on a 55Hz refresh rate so that it shouldn't be affected by fluorescent lighting. If there are, however, some lingering effects then you can get closer to a 50Hz refresh rate if you're in an area where AC frequency is 60Hz, or closer to 60Hz if AC is at 50Hz where you are.

This said, I don't know what the boundaries are.

Maybe I haven't understood very well, but I can't see the relationship between AC power and a battery powered calculator.
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01-23-2020, 10:58 AM
Post: #4
RE: G2 screen refresh rate (20200121)
(01-23-2020 10:56 AM)nbenm Wrote:  Maybe I haven't understood very well, but I can't see the relationship between AC power and a battery powered calculator.

If the refresh rate is close to the AC frequency then the screen will flicker because of interference from fluorescent lighting.

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01-23-2020, 11:17 AM
Post: #5
RE: G2 screen refresh rate (20200121)
What is the HP Prime screen default refresh rate?
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01-23-2020, 11:23 AM (This post was last modified: 01-23-2020 11:24 AM by Dirk.nl.)
Post: #6
RE: G2 screen refresh rate (20200121)
Thank you for your response, grsbanks !
I knew the reason for the adjustable refresh rate; However, I would like to know more about this. Maybe Tim and / or Cyrille can answer my questions?
This adjustable refresh rate can be a good solution.

Voldemar, was it 55Hz ? I’m not sure!

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01-23-2020, 02:35 PM
Post: #7
RE: G2 screen refresh rate (20200121)
(01-23-2020 10:56 AM)nbenm Wrote:  
(01-23-2020 10:32 AM)grsbanks Wrote:  I'd guess that this was made possible so that you can shift the refresh rate even further away from the local AC frequency of your country.

AC is 50Hz or 60Hz depending on where you are, so HP settled on a 55Hz refresh rate so that it shouldn't be affected by fluorescent lighting. If there are, however, some lingering effects then you can get closer to a 50Hz refresh rate if you're in an area where AC frequency is 60Hz, or closer to 60Hz if AC is at 50Hz where you are.

This said, I don't know what the boundaries are.

Maybe I haven't understood very well, but I can't see the relationship between AC power and a battery powered calculator.

AC powers your light. Some lights flicker - faster than your eye can see
BUT
if the calculator screen refresh rate is close to the flickering light
(the light seems to flicker close 100 Hz here in Finland, in my US visit it was closer to 120Hz)
then the screen also seems to flicker.
To avoid this HP (Cyrille) used ~55Hz screen refresh rate
which is between 60 Hz US AC and 50 Hz EU AC

As you can C (with your eyes as well as your mind)
the battery power of your calculator does not matter in this situation
VPN
_________________________________________________________________
PS: the HP Prime G3 screen refresh should go 80 Hz (in my very humble opinion)
as well as the resolution doubled in both directions 2x by 2y = 640 x 400
add a flag to use the old resolution vs the new one
and truly add a bigger, bold font (and a smaller one as requested by some 20/20 visionist)

What do you say,
Cyrille aka "Wolverine" <- my nickname for Cyrille from the last Millenium
??
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01-23-2020, 08:25 PM
Post: #8
RE: G2 screen refresh rate (20200121)
(01-23-2020 10:32 AM)grsbanks Wrote:  I'd guess that this was made possible so that you can shift the refresh rate even further away from the local AC frequency of your country.

AC is 50Hz or 60Hz depending on where you are, so HP settled on a 55Hz refresh rate so that it shouldn't be affected by fluorescent lighting. If there are, however, some lingering effects then you can get closer to a 50Hz refresh rate if you're in an area where AC frequency is 60Hz, or closer to 60Hz if AC is at 50Hz where you are.

This said, I don't know what the boundaries are.

In another thread, there's a program that shows flicker on particular screen but not others. Is changing the refresh rate the answer? I see the flicker even when the only light in the room is sunlight. What's the frequency of the sun? Smile

Tom L
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01-23-2020, 08:45 PM
Post: #9
RE: G2 screen refresh rate (20200121)
Tom, maybe it depends on the frequency of your eyes and brains !! Ha, ha.

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01-23-2020, 09:54 PM
Post: #10
RE: G2 screen refresh rate (20200121)
(01-23-2020 08:25 PM)toml_12953 Wrote:  What's the frequency of the sun? Smile

All of them.

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01-23-2020, 11:36 PM
Post: #11
RE: G2 screen refresh rate (20200121)
(01-23-2020 08:45 PM)Dirk.nl Wrote:  Tom, maybe it depends on the frequency of your eyes and brains !! Ha, ha.

Oh. Slow, then. Smile

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01-24-2020, 06:06 AM
Post: #12
RE: G2 screen refresh rate (20200121)
Hello,

OK, lots to untangle here...

> Cyrille aka "Wolverine" <- my nickname for Cyrille from the last Millenium
My nickname in the last milenium was never Wolverine (which is a name that I did not hear until I moved to english speaking countries, we did not do super heroes in France when I was youg, bar Superman, Zorro and Batman, and our comic books have nothing to do with super heroes)....
My nickname was HPmâd (note the important accent on top of the 'a') since I was 'crazy' (aka 'mad' in my poor english of the time) about HP calculators, and since crazies, in old movies and comics did wear funnels as hats (hence the accent circonflexe on top of the â which is a simplified "depiction" of said funnel (when I was writing it by hand, I would draw the funnel))...

> why flicher and AC frequency are linked.
non-incandessent lights flicker at the AC frequency. it used to be true only of neons in the old time, which meant only office buldings and the like. now that fluoressent and LED (which also flicker) are everywhere it is way more important.
if the screen refresh rate is very close to the light flicker rate, you get a stroboscopic effect (think weels that seems stationnary, or to go slow or backward in movies). this effect reinforce the lighting/visibility of some part of the screen amd make other seem dimmer. since your eye is verry sensitive to contrast, it will enhance this effetct and this will manifest as a type of flicker... since US uses 60hz and the rest of the world uses 50hz, I set the refresh rate at 55hz.

> about outside flicker.
The sun does flicker with 2 main periods super-imposing on each other. so such an effect is, in theory possible, with the sun...
However, since the sun flickering frequency, oen intrinsic, one external are, repectively, 11 years and 24h, we should be good from interference with the prime screen Smile

> frequency range on Prime:
The new frequency selection mechanism allows a setup from 55hz to 120hz.

> drwabacks
To refresh the screen, the CPU must fetch the screen from memory and send it to the screen driver at the rate of 300kb/screen.
so, 60 screen per second is 18MB that needs to be fetched from RAM, 120hz is 36MB.
This has a dirrect impact on RAM bus usage.
When the calculator is 'working' this buss usage will take precedence over CPU needs, so calculations might slow down a little bit (probably barely mesurable except on very memory intensive stuff, partially thanks to cache).
It also has a power consuption impact. 120hz uses (from memory) 40mA more than 60hz. in Idle mode (before the screen dims), this is an extra 10% power consumption! so there is a drback to high refresh rate, which is why you should set it at the minimum frequency that works for you.

Last point, when the screen dims, I lower the frequency by 20 or 30Hz (I do not remember). Since the screen is dimmed, it is much less visible. hence during the time of screen dimming, I can reduce power use.

Here you go, you should have all the info now.
Cyrille

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01-24-2020, 06:17 AM
Post: #13
RE: G2 screen refresh rate (20200121)
Whoa whoa whoa wait a second, let me get this straight.
Quote:frequency range on Prime:
The new frequency selection mechanism allows a setup from 55hz to 120hz
The Prime's LCD, as terrible as it is with colors and viewing angles, can actually refresh faster than my laptop monitor?! I tried to increase the refresh rate as high as I could (I hold down on, shift, and + right?) but it didn't look like it was 120hz, there was certainly a lot of screen tearing going on. Am I doing something incorrect or does the software only support up to 120hz while the LCD doesn't? Or, more likely, am I misunderstanding what you said?

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01-24-2020, 06:42 AM
Post: #14
RE: G2 screen refresh rate (20200121)
(01-24-2020 06:17 AM)TheLastMillennial Wrote:  ... I tried to increase the refresh rate as high as I could (I hold down on, shift, and + right?) but it didn't look like it was 120hz...

Press and hold down On, *then* press and hold down Shift, then press and release the [+] or [-] key to increase or decrease the refresh rate, respectively, one step per press. A refresh rate indicator is displayed while the [+] or [-] key is held down, so don't tap them too quickly or you won't see the indicator. When the indicator is at the far right, the refresh rate is 120Hz.

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01-24-2020, 08:14 AM (This post was last modified: 01-24-2020 08:18 AM by Carlos295pz.)
Post: #15
RE: G2 screen refresh rate (20200121)
Since I saw that in "release_info.txt" I tried it in G1_HW C, but it didn't show any action. This is only for G2?

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01-24-2020, 09:15 AM
Post: #16
RE: G2 screen refresh rate (20200121)
Hi Cyrille,
Thank you very much for your explanation about the adjustable refresh rate, great!!

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01-24-2020, 12:56 PM
Post: #17
RE: G2 screen refresh rate (20200121)
(01-24-2020 08:14 AM)Carlos295pz Wrote:  Since I saw that in "release_info.txt" I tried it in G1_HW C, but it didn't show any action. This is only for G2?

Yes, G2 only (hw rev D).

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01-24-2020, 05:03 PM (This post was last modified: 01-24-2020 05:03 PM by Tim Wessman.)
Post: #18
RE: G2 screen refresh rate (20200121)
The G1 Hardware had a different way of updating the screen module, so it did not exhibit the more visible issues pointed out on the G2 recently. Thanks to that user program, we really could track down what was going on with it...

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01-24-2020, 06:08 PM
Post: #19
RE: G2 screen refresh rate (20200121)
I answered my own question. The flicker can be eliminated with a higher refresh rate.

Tom L
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01-24-2020, 10:29 PM (This post was last modified: 01-24-2020 10:30 PM by Carlos295pz.)
Post: #20
RE: G2 screen refresh rate (20200121)
(01-24-2020 12:56 PM)Joe Horn Wrote:  Yes, G2 only (hw rev D).

Thank you


(01-24-2020 05:03 PM)Tim Wessman Wrote:  The G1 Hardware had a different way of updating the screen module, so it did not exhibit the more visible issues pointed out on the G2 recently. Thanks to that user program, we really could track down what was going on with it...

I understand, it seems that I missed things, thanks for the clarification.
I got excited when I read that in realease_info without distinction of hardware, I suspected.

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