[Gta04-owner] [Community] OpenPhoenux Prototype of GTA04 based7 inch tablet

Dr. H. Nikolaus Schaller hns at goldelico.com
Thu Nov 8 07:50:17 CET 2012


Am 07.11.2012 um 20:42 schrieb Flemming Richter Mikkelsen:

> Since the display is so demanding, maybe a hardware display power
> switch is in order?  That way one can boot without the display on.

Or we could simply dim the backlight by software. But it does not solve
the fundamental problem that the device will drain the battery even if
connected to a power supply while being used.

I think nobody would expect that it should be switched off/dimmed
during charging and has limited operation time even if connected
to the power supply. I.e. it does not work in picture frame mode...

> 
> The backlight may be controlled by PWM, but may still demand a lot of power...
> I was thinking USB 3.0 could solve the power issue.  We got lots of
> extra space...
> Or maybe just a normal power connector would be better since chargers that talk
> USB 3.0 is not easy to find. I know I would want to charge it at work,
> at home and
> from the car...

I now understand why even small netbooks come with a 9V 2A supply.

> I know some low power displayes, but they are either monochrome or
> really slow (for ebooks) and with such a nice tablet it would be a
> shame not to be able to watch videos.

Exactly. I have studied the Pixel Qi 7 inch display but it has the same
demand in full color mode. It appears to be a physical law that a
sufficiently bright 7 inch display needs 1.5 Watt or more.

> 
> Maybe also a bigger or double battery pack would help a little.

Not really. It is the balance between power supply and demand.
Only the difference can be used to charge the battery - independently
of its capacity.



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