microcontroller for capacitive touch screen?

On Sun, 05 Aug 2007 22:42:05 -0700, Ajab <jasusvijay@yahoo.com> wrote:

>On Aug 4, 12:21 pm, jan <jans...@murray-microft.invalid> wrote:
>> Ajab wrote:
>> > We are thinking to interface LCD and this touch screen through a
>> > microcontroller.
>> > Is there any company available that provides microcontroller for
>> > capacitive touch screens?
>>
>> Qprox chips provide a self-calibrating ready made solution with
>> serial outputs. Parts are available to scan up to 8x8 matrix:
>>
>>    http://www.qprox.com/products/qmatrix_whitepaper.php
>>
>> It looks as though you might need two layers of transparent
>> conductor on your LCD.
>>
>> Jan Coombs
>> --
>
>I want to use capacitive screens because the resistive ones get easily
>damaged by sharp objects.(this is what i read).

If you want touchs screen that is hard to damage then look at SAW
technology. You can mount these on glass that sits on top of LCD
panels to help save the LCD as well.

On Aug 6, 1:42 pm, The Real Andy <thereala...@nospam.com> wrote:
> On Sun, 05 Aug 2007 22:42:05 -0700, Ajab <jasusvi...@yahoo.com> wrote:
> >On Aug 4, 12:21 pm, jan <jans...@murray-microft.invalid> wrote:
> >> Ajab wrote:
> >> > We are thinking to interface LCD and this touch screen through a
> >> > microcontroller.
> >> > Is there any company available that provides microcontroller for
> >> > capacitive touch screens?
>
> >> Qprox chips provide a self-calibrating ready made solution with
> >> serial outputs. Parts are available to scan up to 8x8 matrix:
>
> >>    http://www.qprox.com/products/qmatrix_whitepaper.php
>
> >> It looks as though you might need two layers of transparent
> >> conductor on your LCD.
>
> >> Jan Coombs
> >> --
>
> >I want to use capacitive screens because the resistive ones get easily
> >damaged by sharp objects.(this is what i read).
>
> If you want touchs screen that is hard to damage then look at SAW
> technology. You can mount these on glass that sits on top of LCD
> panels to help save the LCD as well.- Hide quoted text -
>
> - Show quoted text -

Yes. But SAW are prone to liquids.
I need a touch screen which is resistant to sharp
scratches,liquids(may be hot). Also it should be unaffected by IR and
mobile radiations in vicinity. Projected capacitive seem better.

Ajab wrote:
> On Aug 6, 1:42 pm, The Real Andy <thereala...@nospam.com> wrote:
>> On Sun, 05 Aug 2007 22:42:05 -0700, Ajab <jasusvi...@yahoo.com> wrote:
>>> On Aug 4, 12:21 pm, jan <jans...@murray-microft.invalid> wrote:
>>>> Ajab wrote:
>>>>> We are thinking to interface LCD and this touch screen through a
>>>>> microcontroller.
>>>>> Is there any company available that provides microcontroller for
>>>>> capacitive touch screens?
>>>> Qprox chips provide a self-calibrating ready made solution with
>>>> serial outputs. Parts are available to scan up to 8x8 matrix:
>>>>    http://www.qprox.com/products/qmatrix_whitepaper.php
>>>> It looks as though you might need two layers of transparent
>>>> conductor on your LCD.
>>>> Jan Coombs
>>>> --
>>> I want to use capacitive screens because the resistive ones get easily
>>> damaged by sharp objects.(this is what i read).
>> If you want touchs screen that is hard to damage then look at SAW
>> technology. You can mount these on glass that sits on top of LCD
>> panels to help save the LCD as well.- Hide quoted text -
>>
>> - Show quoted text -
> 
> Yes. But SAW are prone to liquids.
> I need a touch screen which is resistant to sharp
> scratches,liquids(may be hot). Also it should be unaffected by IR and
> mobile radiations in vicinity. Projected capacitive seem better.

so, did you like the Qprox parts?  From the white paper cited above:

QMatrix devices are digital charge-transfer (QT) ICs designed to 
detect touch using a scanned, passive matrix of electrode sets to 
achieve a large number of touch keys driven by a single chip.
. . .

QMatrix circuits offer tremendous signal-to-noise ratios, high 
levels of immunity to moisture films, extreme levels of temperature 
stability, superb low power characteristics, ease of wiring, and 
small IC package sizes for a given key count, For these reasons, 
QMatrix circuits are highly prized for automotive, kitchen 
appliance, and mobile applications.

Jan.

jan wrote:

Snip..

> QMatrix circuits offer tremendous signal-to-noise ratios, 

Snip...

First time I've ever seen S/N ratio specified as "tremendous"

Jim Stewart wrote:
> jan wrote:
>> QMatrix circuits offer tremendous signal-to-noise ratios, 

Nah - just reluctantly quoted it, because the OP seemed unable to 
follow posted link to Qproc's docs!

> First time I've ever seen S/N ratio specified as "tremendous"

Yes, "tremendous" is hardly a technical term, but I believe that 
their patented process does significantly simplify the effective 
application of capacitive sensors.

Jan Coombs