Auto backlight management?

karl karl.ramberg at
Fri Apr 25 08:06:17 EDT 2008

Bert Freudenberg wrote:
> On 25.04.2008, at 10:46, Martin Dengler wrote:
>> On Fri, Apr 25, 2008 at 12:07:12AM -0400, Eben Eliason wrote:
>>> On Thu, Apr 24, 2008 at 10:43 PM, John Watlington <wad at>  
>>> wrote:
>>>> Bert misread the spec.  When the backlight is switched off, the  
>>>> screen
>>>> automatically switches to B&W mode.   Why would you want to take
>>>> that out of the control of the user ?
>>> It's clear to me that it would be quite useful to have a
>>> bright backlight AND black & white mode for reading a book at night,
>>> for instance, and this isn't possible in the current UI.
>> The camera could be checked once when the device went into/out of  
>> ebook mode
>> and the backlight changed appropriately.
> Malicious software also could snap a picture of the user at that  
> moment. This is the privacy issue that Ivan mentioned, and I agree, we  
> cannot use a camera image for this.
> What I suggested before, but which was not practicable, would be some  
> "passive" readout-hardware in the camera that only reports a single  
> brightness value. But I was told the current design would require to  
> power the camera on for that. And in a new hardware design it may be  
> cheaper and better to add a photo sensor than this.
> The biggest benefit I see from adding this is power savings. The  
> backlight should be automatically turned off when there is enough  
> ambient light, to save power. Switching it back on could easily be  
> done by the user (or automatically for convenience).
Hey, why not let the kids build this them self ? Here is a DIY light 
sensor project:


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