Capacitive Screen vs Resistive Screen

[Merckle]

I have been wondering this. But what is the difference between Captive and Restive display screens on phones?

[spiritcrusher33]

http://forum.ppcgeeks.com/showthread...71#post1145471

sporklover post..


So we have a new wave of phones that are hitting the market thanks to Android that have capacitive touch screens.... not resistive. Why is that significant some of you may ask. I myself tried to find this answer and searched the forums and found a few threads covering the subject, but most of the information was opinions (which would you rather have), or not really detailed enough to draw any opinions from. So I decided to google the subject to death and write it up for anyone else interested. My main interest in my self-imposed homework was to find out what is the difference between capacitive and resistive technologies, and why capacitive may be an improvement. Lastly, with the understanding that resistive is "old" technology, I was interested to see where it still may be the leading technology.

Resistive Touch - The easiest way to describe resistive touch technology is as two layers of electrically conductive material separated by air or a gap. The upper layer is typically something pliable and flexible (polyester or other durable plastics) and the lower layer is typically glass. Both layers coated with material to make them electrically conductive. When the two layers are pressed together, through computer and electronic wizardy (don't really need to explain how, it's just magic!) a precise location of the touch is calculated. The location of the touch is exact! It can occur with any device that is able to provide pressure. Sometimes the two layers is covered by another layer, for protection and added durability.

This device is then overlayed on top of some type of optical device (in our cases its an LCD screen)

Pros of this technology:

1. Anything can be used to touch the screen. This is great when it's cold outside, you can keep your gloves on
2. When coupled with a stylus the input is very precise!
3. Cheap!

Cons of this technology:

1. A pain we all know, durability. The upper layer is prone to scratches, and the lower layer is prone to cracking or breaking when dropped or too much pressure is applied.
2. The layers of material and the gap of air really hinder optics. It hurts clarity and it hurts brightness. In daylight this becomes really apparent.
3. It is mechanical....pressure is required
4. Edges tend to lose accuracy. (I hated this on my mogul!)
5. Tend to be susceptible to water/humidity. Water does not lend itself well to this type of mechanical touch operation.

Projected Capacitive Touch (the subtype of capacitive touch used in Smartphones) - First off Projected Capacitive Touch (PCT) is a type of Capacitive Touch technology that is used in consumer devices such as PDA's and Smart Phones. What defines this type of Capacitive technology is the usage of very fine and thin wires. A typical PCT touch array is 3 layers, a layer of Glass for viewing, a layer with horizontally and vertically arranged wires in a durable thin medium (polyurethane), and a lower glass layer. The thin wires create a grid (think X axis, Y axis). The middle layer is where the magic happens, the two layers of glass are there for protection.

The wires in the middle layer are powered all the time, and act as capacitors. The magic happens when a human swipes their fingers across the screen. Humans naturally have the ability to conduct electricity. When the finger is introduced, it disturbs and changes the electrostatic field, and changes the capacity of each of the "capacitors". Measuring this change allows the controller board to determine the point of touch. Neat huh? This interference is also the secret to the Capacitive screen's ability to support multi-touch.

Pros of this technology:

1. With the layers of glass, the screen is very durable. If hard enough material is used, the screen can be virtually scratch proof.
2. Optics are great! Relative to resistive screens, does not hinder light anywhere near as much. Current manufacturing techniques can yield a screen that allows 90% of light to pass through.
3. Depending on construction, the screen can be relatively very resistant to water/humidity!
4. Due to the nature of the operation of the screen... a touch is not really required. No pressure at all. This is why swiping action on an Iphone seems more naturally and fluid when compared to a resistive screen phone (all windows mobile pro phones.)

Cons of this technology:

1. You must use your finger or a specially designed pointing device in order to work (meaning if you aren't fat fingering, you need a special stylus)
2. Comparative to resistive screens, higher manufacturing costs. Given time this will be overcome......


Projected Capacitive Touch Significance to PDA/Smartphone/MP3 or other touchscreen devices:

1. Hinders device brightness less than resistive screens. This is great for those of us who like to use our touch screen devices in daylight, or want better battery life!

2. Ease of use! This thing does not require any pressure at all!

3. Durability! Glass is more durable than resistive screen coverings.

4. This may be a plus to some, hindrance to others.... but the screen will look glossy due to the glass..... resistive screens tend to be more towards the matte end of things.

Where Resistive Screen still outperforms capacitive:

1. Hand writing recognitions systems. The preciseness of the resistive screen is still very handy for those that like to take notes on their digital devices. It allows you to "write" notes on your device. Capacitive devices don't do this so well (yet).

Conclusion:

PCT screens allow for very durable, brighter screens that work in the daylight, and are easy to use. It also enables multi-touch. (resistive screens offer this too... but its not yet perfected). Visibility and optics are important in PDAs and smart-phones, especially in this day and age where resolution is and screen size is growing.

It seems the natural technology solution for your next PDA or smart-phone, unless you rely on handwriting recognition.


My wondering / rambles:

Anyone have any idea which technology consumers more power?


Footnotes: I googled all of the information. Some came from wikipedia, infoworld, and other smartphone/pda publications.

[CozBoogie]

Threads merged.

late,
Coz

[code_311]

Nice write up! I always wondered why the iPhone had such a different feel than most WinMo phones.

[nemoshotyany]

Yea. I like the captive screens better. no scratches ftw