hippy
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Re: Why sell a 7" screen?

Mon Oct 08, 2018 10:17 am

Imperf3kt wrote:
Mon Oct 08, 2018 8:22 am
I'm not sure where screen dimensions come into "productivity"
At my job, I use a square 5*5 inch touchscreen and it's more than adequate for me to be "productive"
I believe it was meant in the sense that if you shrunk the desktop monitor you use regularly, day in, day out, down to 7" or smaller you would not find it as convenient to use and it would impact your productivity. I would agree with that.

It's all about finding that perfect size and resolution which suits the user and what they do. I find large monitors with high resolution impede my productivity. 13" or 15" 4:3, or 19" widescreen, are perfect for what I generally do. Larger than that and I have never found them as comfortable to use.

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Re: Why sell a 7" screen?

Mon Oct 08, 2018 1:39 pm

bensimmo wrote:
Mon Oct 08, 2018 9:01 am
Resolution is low on the old 7" they sell but it was 2015 when it came to market and I assume a least a year or so in development ?.
More like 2 years, IIRC. Problems were encountered, and even then, on the very first ones you couldn't adjust the backlight. That feature came later with a controller revision. (And I still think it'd be nice to be able to buy "replacement" controller boards if you have very early displays.)

Njord
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Re: Why sell a 7" screen?

Mon Oct 08, 2018 3:50 pm

W. H. Heydt wrote:
Mon Oct 08, 2018 5:12 am
Njord wrote:
Mon Oct 08, 2018 3:41 am
jamesh wrote:
Sun Oct 07, 2018 7:59 am
1. The display uses PWM for its backlight control.
That's too bad. I'll have to steer clear of it then.
If that's a problem, you probably have to stay away from *all* LED backlit screens.
Incorrect. PWM brightness adjustment is used only on very low-end screens.

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Re: Why sell a 7" screen?

Mon Oct 08, 2018 4:13 pm

Njord wrote:
Mon Oct 08, 2018 3:50 pm
W. H. Heydt wrote:
Mon Oct 08, 2018 5:12 am
Njord wrote:
Mon Oct 08, 2018 3:41 am

That's too bad. I'll have to steer clear of it then.
If that's a problem, you probably have to stay away from *all* LED backlit screens.
Incorrect. PWM brightness adjustment is used only on very low-end screens.
So how is it done on expensive screens? I am only aware of PWM for LED backlighting brightness control.

EDIT: Unless you just mean current control?
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Re: Why sell a 7" screen?

Mon Oct 08, 2018 4:19 pm

Oh, and in answer to the OP's initial question, it's because we sell loads of them.

(which by deduction, means that there is clearly a good market for 7" touch displays, in contradiction to the OP's initial post. Personal preconceptions can be misleading)
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bensimmo
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Re: Why sell a 7" screen?

Mon Oct 08, 2018 4:43 pm

Or that people like to buy an official known good screen that will have support.
Given there are no other sizes to choose from by Raspberry Pi.

(There are of course loads of compatible ones, including 10" https://www.inelcohunter.co.uk/10-1-inc ... -screen-2/ by the people who supply the official one I believe )

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Re: Why sell a 7" screen?

Mon Oct 08, 2018 4:56 pm

Do not make the assumption that all Pis are used as general purpose desktop computer. It can be used for many applications besides the desktop. A recent announcement by Adafruit, www.adafruit.com, has an add blokcing Pi-hole that uses 2.8 inch TFT screen to display the status. One could even go to a much smaller display for headless systems to just show the online status and the IP address.

These smaller screens would not be sold if there was not a market for them.
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Re: Why sell a 7" screen?

Mon Oct 08, 2018 6:09 pm

gkaiseril wrote:
Mon Oct 08, 2018 4:56 pm
Do not make the assumption that all Pis are used as general purpose desktop computer. It can be used for many applications besides the desktop.
The 7" screen makes a nice electronic photo frame.
Somewhat bizarrely you can log in and work on its Pi at the same time!

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Re: Why sell a 7" screen?

Mon Oct 08, 2018 6:17 pm

gkaiseril wrote:
Mon Oct 08, 2018 4:56 pm
Do not make the assumption that all Pis are used as general purpose desktop computer.
Indeed. Of all the--rather large number--of Pis I have, *none* of them are used as general purpose desktop machines. The closest any of them come to that are a half dozen Pi2Bv1.1 boards used as "workstations" to input new at-the-door members to a convention. The only "application" being run on them is PuTTY.

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Re: Why sell a 7" screen?

Mon Oct 08, 2018 7:33 pm

Njord wrote:
Sat Oct 06, 2018 3:02 am
But the 7" display is still being sold.
Because this is the official Pi display. There are no 7" and 10" models. The choice is between official 7" or 3rd party 10" or more.

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Re: Why sell a 7" screen?

Tue Oct 09, 2018 6:02 pm

jamesh wrote:
Mon Oct 08, 2018 4:13 pm
So how is it done on expensive screens? I am only aware of PWM for LED backlighting brightness control.
EDIT: Unless you just mean current control?
DC dimming. See here: https://pcmonitors.info/factors-influen ... g-comfort/

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Re: Why sell a 7" screen?

Tue Oct 09, 2018 7:30 pm

bensimmo wrote:
Mon Oct 08, 2018 4:43 pm
(There are of course loads of compatible ones, including 10" https://www.inelcohunter.co.uk/10-1-inc ... -screen-2/ by the people who supply the official one I believe )
Yes, I've discovered a 10" panel that might be good, from Sunfounder. Previously were making noises about releasing an Rpi based tablet, but that never happened, so I guess this is what came of that.
https://www.amazon.com/Raspberry-Inch-T ... B0776VNW9C?
Here's nicer one but without touch input:
https://www.amazon.com/Raspberry-Screen ... B07FZZ95WN
Last edited by Njord on Tue Oct 09, 2018 7:37 pm, edited 1 time in total.

Ernst
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Re: Why sell a 7" screen?

Tue Oct 09, 2018 7:36 pm

Njord wrote:
Tue Oct 09, 2018 7:30 pm
bensimmo wrote:
Mon Oct 08, 2018 4:43 pm
(There are of course loads of compatible ones, including 10" https://www.inelcohunter.co.uk/10-1-inc ... -screen-2/ by the people who supply the official one I believe )
Yes, I've discovered a 10" panel that might be good, from Sunfounder. Previously were making noises about releasing an Rpi based tablet, but that never happened, so I guess this is what came of that. There's no touch input unfortunately.
https://www.amazon.com/Raspberry-Screen ... B07FZZ95WN
https://www.raspberrypi.org/magpi/raspad-review/
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Njord
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Re: Why sell a 7" screen?

Tue Oct 09, 2018 7:44 pm

From the kickstarter comment area:

"And now it's October and still no tracking number and even worse, no word from sunfounder on some kind of status. "
Ricko

"I would like to know where my package goes, I haven't received any confirmation of package sent nor any tracking number."
Jouni

But a few people did receive them.

Ernst
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Re: Why sell a 7" screen?

Tue Oct 09, 2018 8:05 pm

Njord wrote:
Tue Oct 09, 2018 7:44 pm
From the kickstarter comment area:

"And now it's October and still no tracking number and even worse, no word from sunfounder on some kind of status. "
Ricko

"I would like to know where my package goes, I haven't received any confirmation of package sent nor any tracking number."
Jouni

But a few people did receive them.
But many people did receive them. I am one of those who did receive.
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Re: Why sell a 7" screen?

Tue Oct 09, 2018 8:17 pm

Njord,

From your link...
The good news is that the vast majority of monitors now use DC (Direct Current) instead of PWM to modulate backlight brightness
I think we can be very sure that the "Direct Current" of which they speak is generated by a switched mode power supply. That is to say PWM. Sure it will be operating at 100s of KHz and filtered so as to produce the smooth DC you crave.

The only other alternative is a linear regulator, which is very inefficient and run hot.
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Re: Why sell a 7" screen?

Wed Oct 10, 2018 5:08 am

Ernst wrote:
Tue Oct 09, 2018 8:05 pm

But many people did receive them. I am one of those who did receive.
Any issues yet? How much time have you spent using it?

Ernst
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Re: Why sell a 7" screen?

Wed Oct 10, 2018 6:10 am

Njord wrote:
Wed Oct 10, 2018 5:08 am
Ernst wrote:
Tue Oct 09, 2018 8:05 pm

But many people did receive them. I am one of those who did receive.
Any issues yet? How much time have you spent using it?
There is not much to say, the battery does not last that long, the power status LEDs are very bright, the touch screen is a bit difficult for my fingers, not optimal for heavy CPU usage (temperature), removing the memory card is difficult. and there are a few general problems not specific to raspad like use of the onscreen keyboard, size of the characters in a terminal, power off after shutdown.
I am happy with the raspad which I use as tool when I want to try something and I do not want to take a risk on my "normal" desktop (uptime 36 days).
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Re: Why sell a 7" screen?

Wed Oct 10, 2018 8:30 am

Njord wrote:
Tue Oct 09, 2018 6:02 pm
jamesh wrote:
Mon Oct 08, 2018 4:13 pm
So how is it done on expensive screens? I am only aware of PWM for LED backlighting brightness control.
EDIT: Unless you just mean current control?
DC dimming. See here: https://pcmonitors.info/factors-influen ... g-comfort/
AFAIK, that is rare in small LCD's. It's also more expensive and as stated above, runs hotter which is often a big problem.

We will not be using it in in the near future. PWM is fine for the majority of our use cases.
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Re: Why sell a 7" screen?

Wed Oct 10, 2018 9:49 am

jamesh wrote:AFAIK, that is rare in small LCD's.
Yes, it is!

There are lot's of constant current LED drivers available to the market which are using PWM for dimming. Much simpler than analog dimming.

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