LED Multi-touch sensing

I think this is really cool, and trying to think of ways to turn it into a product/implement it into a product.

Quote:

The researcher's technique requires at least two light-emitting diodes, one that senses light and one that emits light. When a translucent or reflective object like a finger makes contact, it reflects light from the emitting diode onto the sensing diode. The device can be configured as a button by triggering an action when the intensity of the sensed light passes a threshold corresponding to an object touching the device.

Quote:

Since LEDs share some basic physical properties with photodiodes, which also use p-n junctions with band gap energies in the visible light wavelengths, they can also be used for photo detection. These properties have been known for some time, but more recently so-called bidirectional LED matrices have been proposed as a method of touch-sensing. In 2003, Dietz, Yerazunis, and Leigh published a paper describing the use of LEDs as cheap sensor devices. In this usage, various LEDs in the matrix are quickly switched on and off. LEDs that are on shine light onto a user’s fingers or a stylus. LEDs that are off function as photodiodes to detect reflected light from the fingers or stylus. The voltage thus induced in the reverse-biased LEDs can then be read by a microprocessor, which interprets the voltage peaks and then uses them elsewhere. The website of Jeff Han features a video demonstrating one such implementation of an LED matrix multi-touch sensor.

TOUCH SCREEN SWITCH......have a switch that acts like a push button, except touch, use 3 LED's, one in an "off" color, one in an "on" color and one to sense light, when the sensor sees the off color it turns the switch on, and changes colors to the "on" color. When the light sensor senses the "on" color it switches the color to off and opens the switch back up.

EX: A 1"x1" pad that is red normally, then you touch the screen, the light switches to green and the circuit is closed, touch it again and it switches back to red and the switch is opened.

I'd be the first on your list to test them, I've been wanting to make a touch-screen switchbox for some time.

that switch would have to get a lot smaller than it looked like it on the table.



Also saw that this video was cool.

Phil wrote:

I think this is really cool, and trying to think of ways to turn it into a product/implement it into a product. Quote: The researcher's technique requires at least two light-emitting diodes, one that senses light and one that emits light. When a translucent or reflective object like a finger makes contact, it reflects light from the emitting diode onto the sensing diode. The device can be configured as a button by triggering an action when the intensity of the sensed light passes a threshold corresponding to an object touching the device. Quote: Since LEDs share some basic physical properties with photodiodes, which also use p-n junctions with band gap energies in the visible light wavelengths, they can also be used for photo detection. These properties have been known for some time, but more recently so-called bidirectional LED matrices have been proposed as a method of touch-sensing. In 2003, Dietz, Yerazunis, and Leigh published a paper describing the use of LEDs as cheap sensor devices. In this usage, various LEDs in the matrix are quickly switched on and off. LEDs that are on shine light onto a user’s fingers or a stylus. LEDs that are off function as photodiodes to detect reflected light from the fingers or stylus. The voltage thus induced in the reverse-biased LEDs can then be read by a microprocessor, which interprets the voltage peaks and then uses them elsewhere. The website of Jeff Han features a video demonstrating one such implementation of an LED matrix multi-touch sensor.

would be nice if they could integrate 3 into one led like they have for 3 colors led's now... 2 emitting one sensing.... touch a 5 mm led... senses the reflection.. changes colors to show the change..... etc... but i'm sure it's not quite possible or not cheap

still quite neat though

that is some pretty cool stuff there philbo...technology these days lol...

And i do say that some "touch" screen switches would be tight..would light up a different color when the lights are on or something lol

touch screen switches already exist, here is a site that sells them.
http://www.autoaccessorystore.com/home_n.asp?di...il&id=884&wizard=&s=

Yeah, and they have limited functionality, are fairly big, (A little bigger than a quarter) and don't change color when activated....

This kind of technology could make something entirely different....

Plus I want an "OZNIUM" Switch....

I'd like to see them less than 25 bucks too....I like the idea of taking a superflux chip and having one red element, a blue element, and a green element, as well as a sensing element in the bulb....now you're looking at a touch switch approx 3/8" in diameter that could produce at least 7 colors at any given time.