Building A Touch Screen For My Final Year Project - Electronic Circuits Projects Diagrams Free

mekman · 26th November 2007, 05:30 AM

i am buliding a touch screen (4 wire resistive) for my final year project in university. and i need some help to point me in the right directions.

i now understand they are 3 parts to the project
1. building of the touch screen itself
2. creating a controller for it
3. the software interfacing

my problem is as follows

for the first part (building of the touch screen itself)
i know i need ITO coating on a glass or some sort of plastic
does anyone know where i could order this somewhere in the uk?
2. should get the coating with the most resistance?
3. i am going to have problem with noise either form the lcd screen i am mounting on or the plate itself and how do i resolve this?

for the second part (creating a controller for it)
any idea for a cheap 4 wire controller or chip to be used to make this controller to work through the RS232 port?
please any schematics?

for the software part
how do i get it to actually move the mouse in windows xp.
and do i need to create a driver?

any help you give me is appreciated and thank you for taking time to read my request.
anthony

Oznog · 26th November 2007, 07:04 AM

I don't think you can MAKE a touch screen.
Touch screens are complicated to manufactured and AFAIK it's not something you can make at home.

Typically there are 3 components here: the physical touch screen, a controller which interprets the analog electrical voltags as a logical location, and a microcontroller (or PC) which queries the controller for touch screen activities.

There are infrared LED touch screens which are not based on a coating but rather a frame around the screen, consisting of simply many infrared (invisible) transmitting LEDs on one side and many receivers on the other side, giving a low-resolution X-Y location of your finger by seeing which row/column receivers see a reduction in light exposure. There are issues of light spread, a finger will probably block the light to more than one receiver and light spreading off adjacent rows/columns will probably still illuminate the desired receiver some. It may be best to use highly focused LEDs but I really don't know.

mekman · 26th November 2007, 07:31 PM

Quote:

Originally Posted by Oznog

I don't think you can MAKE a touch screen.
Touch screens are complicated to manufactured and AFAIK it's not something you can make at home.

Typically there are 3 components here: the physical touch screen, a controller which interprets the analog electrical voltags as a logical location, and a microcontroller (or PC) which queries the controller for touch screen activities.

There are infrared LED touch screens which are not based on a coating but rather a frame around the screen, consisting of simply many infrared (invisible) transmitting LEDs on one side and many receivers on the other side, giving a low-resolution X-Y location of your finger by seeing which row/column receivers see a reduction in light exposure. There are issues of light spread, a finger will probably block the light to more than one receiver and light spreading off adjacent rows/columns will probably still illuminate the desired receiver some. It may be best to use highly focused LEDs but I really don't know.

i am studying computer systems and electrical engineer. and i am doing this at university. we have all the tools need to make it happen

Helder Ferreira · 26th November 2007, 10:59 PM

Look at the microchip.com site, they have an apnote on touch sreens. It's quite easy to work and with a little dedicated microcontroller you can use it's UART to comunicate with the PC. To interface the touch screen all it's needed is, 4 pins from the uC. 2 outputs and ADC channels. About every Pic micro has those.

Helder Ferreira · 26th November 2007, 11:04 PM

Another way to make a "virtual touch screen" is to use 4 small load cells on a base on to wich you mount the monitor. If you press the screen at different points, the relation between the cells change and it's different from each other. After calibration it will serve as a pretty good touch screen.

ClydeCrashKop · 27th November 2007, 01:35 PM

Microsoft DirectX SDK will let you intercept/modify mouse droppings with examples in the direct input section.

Hero999 · 28th November 2007, 10:00 PM

You could consider Linux as opposed to Windows, not only for reliability's sake but also, being open source, you can tweak it to get it working they way you want.

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

Similar Threads
Title	Starter	Forum	Replies	Latest
FInal year project --[development a PLC training kits]	ahheng2007	Electronic Projects Design/Ideas/Reviews	2	5th October 2007 07:48 PM
Noise handling algorithm in 8 wire touch screen	hanhao	General Electronics Chat	1	30th April 2007 12:11 PM
electronic project for final year	dhinesh kumar	Electronic Projects Design/Ideas/Reviews	6	13th March 2007 01:32 AM
final year project need help	sian840424	Robotics Chat	4	11th August 2006 07:01 PM
about usb touch screen report ? who can help me ?	kite.rui	Micro Controllers	0	16th February 2004 02:54 AM

26th November 2007, 05:30 AM	(permalink)
mekman	Building A Touch Screen For My Final Year Project i am buliding a touch screen (4 wire resistive) for my final year project in university. and i need some help to point me in the right directions. i now understand they are 3 parts to the project 1. building of the touch screen itself 2. creating a controller for it 3. the software interfacing my problem is as follows for the first part (building of the touch screen itself) i know i need ITO coating on a glass or some sort of plastic does anyone know where i could order this somewhere in the uk? 2. should get the coating with the most resistance? 3. i am going to have problem with noise either form the lcd screen i am mounting on or the plate itself and how do i resolve this? for the second part (creating a controller for it) any idea for a cheap 4 wire controller or chip to be used to make this controller to work through the RS232 port? please any schematics? for the software part how do i get it to actually move the mouse in windows xp. and do i need to create a driver? any help you give me is appreciated and thank you for taking time to read my request. anthony

26th November 2007, 07:04 AM	(permalink)
Oznog	I don't think you can MAKE a touch screen. Touch screens are complicated to manufactured and AFAIK it's not something you can make at home. Typically there are 3 components here: the physical touch screen, a controller which interprets the analog electrical voltags as a logical location, and a microcontroller (or PC) which queries the controller for touch screen activities. There are infrared LED touch screens which are not based on a coating but rather a frame around the screen, consisting of simply many infrared (invisible) transmitting LEDs on one side and many receivers on the other side, giving a low-resolution X-Y location of your finger by seeing which row/column receivers see a reduction in light exposure. There are issues of light spread, a finger will probably block the light to more than one receiver and light spreading off adjacent rows/columns will probably still illuminate the desired receiver some. It may be best to use highly focused LEDs but I really don't know. __________________ I thought what I'd do was I'd pretend I was one of those deaf-mutes.

26th November 2007, 10:59 PM	(permalink)
Helder Ferreira	Look at the microchip.com site, they have an apnote on touch sreens. It's quite easy to work and with a little dedicated microcontroller you can use it's UART to comunicate with the PC. To interface the touch screen all it's needed is, 4 pins from the uC. 2 outputs and ADC channels. About every Pic micro has those.

26th November 2007, 11:04 PM	(permalink)
Helder Ferreira	Another way to make a "virtual touch screen" is to use 4 small load cells on a base on to wich you mount the monitor. If you press the screen at different points, the relation between the cells change and it's different from each other. After calibration it will serve as a pretty good touch screen.

27th November 2007, 01:35 PM	(permalink)
ClydeCrashKop	Microsoft DirectX SDK will let you intercept/modify mouse droppings with examples in the direct input section. __________________ C:\WHUT ? Beware the asterisk *

28th November 2007, 10:00 PM	(permalink)
Hero999	You could consider Linux as opposed to Windows, not only for reliability's sake but also, being open source, you can tweak it to get it working they way you want. __________________ I also post at the following sites: http://www.stop-microsoft.org http://www.heated-debates.com Screen name: Aloone_Jonez And http://www.silicontronics.com, same screen name as here.