Resistive vs. Capacitive touch screen - Page 1
Forum section: electronics / projects

author: Wilson__
author_rank: Frequent Contributor
timestamp: June 13, 2024, 08:50:47 pm
content: 1. Can resistive touch screen (3 to 4 inches) work withfinger(lower pressure) instead of stylus (higher pressure at a fine point)?2. Does resistive hasshorter life? May be the two layers will stick together (instead of bounce back out) and fail?3. Any othershort comingfor resistive, other than restricted multipoint? Seem they arestill in advertisementfor lower cost DIY/Arduino although cell phone are now exclusively capacitive??Many thanks

author: wraper
author_rank: Unknown
timestamp: June 13, 2024, 09:00:13 pm
content: Quote from: Wilson__ on June 13, 2024, 08:50:47 pmIt can, not that well though.QuoteCapacitive touch screens do not wear out basically. Resistive touch screens wear out easily, especially with no screen protector and when poked with unsuitable things which is not that rare.

author: coppice
author_rank: Super Contributor
timestamp: June 13, 2024, 09:17:55 pm
content: Quote from: Wilson__ on June 13, 2024, 08:50:47 pmJust before Apple launched the first iPhone the cost of a capacitive screen was really high. HTC was making a lot of smartphones with resistive touch screens that worked pretty well. They operated with fairly light finger touch, and were fairly robust. They would eventually scratch up, though, and they were never quite as light touch as a capacitive screen. Apple gambled on high volumes driving the price of capacitive screens through the floor, and stirred up their supplier base enough to succeed. Nobody wants a resistive touch screen after experiencing a good capacitive one, but the last of them were not that bad. There are still places where electrical noise makes capacitive screens quirky enough to keep resistive ones in play. There are also infra red beam matrix touch screens, used in noisy environments, and sensitive places like medical applications, where capacitive doesn't cut it. If your mucky fingers stop registering on your phone, you wipe the screen and your fingers. You don't want that kind of ambiguity with patient systems. I think my Volvo uses an infra red touch screen for noise reasons. Some cars certainly have done. Some e-book readers also use infra red.

author: wraper
author_rank: Unknown
timestamp: June 13, 2024, 10:04:53 pm
content: Infrared touch was used for ages. I repaired elemental analyzers made in early-mid 90s with IR touch, EL screen and 386sx/486sx CPU, some of them are still working.

author: Wilson__
author_rank: Frequent Contributor
timestamp: June 14, 2024, 09:34:17 am
content: What resolution is infra? May be 3 or 4 or 5 rows/column of emitters and receivers, making 9, 16 or 25 'KEYS' on screen and it is a lot of 'keys' as compare with physical key on traditional hard-key devices.

author: harerod
author_rank: Frequent Contributor
timestamp: June 14, 2024, 10:40:21 am
content: From what I have seen, capacitive is far superior in haptics and optics.However, resistive will accept input by a single gloved finger, no tool required. Combined with an appropriate user interface, this may be a valid solution for environments where you don't want to pull off your glove.A simple civilian application would be a Garmin Montana.

author: m k
author_rank: Super Contributor
timestamp: June 14, 2024, 10:45:37 am
content: Not so long ago I scrapped some working Elo Touch monitors.Connections were sooo out of date.

author: wraper
author_rank: Unknown
timestamp: June 14, 2024, 10:52:24 am
content: IR does not need actually touching the screen to work, so it may be a good solution for cases where high ruggedness is needed and it should work with gloves. However it has limitations such as low resolution, no multi touch and that it must be put in bezel above recessed screen.

author: tooki
author_rank: Super Contributor
timestamp: June 14, 2024, 03:36:18 pm
content: Quote from: Wilson__ on June 13, 2024, 08:50:47 pmWhy would you think they would not work with a finger?!?Resistive touch screens are still widely used, just not on phones and stuff. Resistive touch screens are cheaper (especially for large ones), but their main advantages are mechanical robustness, flexibility as far as what is used to push on them (bare fingers, thick gloves, or any hard object will work), and above all, indifference to contamination (assuming one seals the display). Capacitive touchscreens don’t work reliably when rained on, for example, and won’t respond to thick gloves or a pen.These are reasons why things like ATMs, transit ticket machines, and industrial control displays are overwhelmingly resistive.

author: wraper
author_rank: Unknown
timestamp: June 14, 2024, 04:25:13 pm
content: Quote from: tooki on June 14, 2024, 03:36:18 pmI don't recall ever seeing ATM with a resistive touch screen. Industrial control yes, and I've seen holes worn out in them. I don't get the claim about mechanical robustness, they are not that robust at all. They still have a glass that can crack on an impact and they have plastic films on the outside that can be damaged and wear way easier than glass. Protective films greatly compromise sensitivity. Resistive touch is advantageous in presence of water or other contamination, electrical interference and when used with gloves.

author: dferyance
author_rank: Regular Contributor
timestamp: June 14, 2024, 06:59:47 pm
content: I have been surprised at how well capacitive touch screens have improved. I remember when the iPhone came out I was disappointed it was capacitive. You have better precision with a resistive touch screen. It is all analog while capacitive touch is limited by the grid pattern and spacing. My thought was with having such a small screen, combine that with not being able to use a stylus and the lower precision would greatly limit it's capabilities. In a sense it has but it seems no one cares.Capacitive touch has gotten really good at working in wet conditions, and higher precision. And resistive definitely wears out easier. There may still be cases for resistive but in general capacitive is usually the better route.

author: coppice
author_rank: Super Contributor
timestamp: June 14, 2024, 08:38:29 pm
content: Quote from: Wilson__ on June 14, 2024, 09:34:17 amWhy would you expect infra red to limited like that? They offer similar resolution to capacitive screens.

author: coppice
author_rank: Super Contributor
timestamp: June 14, 2024, 08:41:44 pm
content: Quote from: dferyance on June 14, 2024, 06:59:47 pmEven the first iPhone was not limited to the grid spacing. They have always used interpolation to achieve a pretty high resolution. The capacitive pads on notebooks were never low resolution. Why should one on a phone be? The problem with the phones, and the reason the cost was initially so high, was reliably making the very narrow ITO traces needed.

author: coppice
author_rank: Super Contributor
timestamp: June 14, 2024, 08:42:40 pm
content: Quote from: tooki on June 14, 2024, 03:36:18 pmI think you mean were resistive. The new designs aren't.

author: Wilson__
author_rank: Frequent Contributor
timestamp: June 14, 2024, 09:04:39 pm
content: Many thanks. I speciically referred to 'keys'. That is, on screen 'soft key' instead of hard physical keys. The number of key I stated is generally that a 'machine' need. Bank ATM, weighting scale and may be some industrial control machine. A few keys to select "one of out several" menu jump to next screen level. Up/Down arrow to trim parameters, says temperature controller.A few row is easily done with IR emitted and sensor. Yes, you can have high resolution sensor. Say, use an traditional (the original wide spread use version, 30 years ago, Rockwell modem inside. Not the advanced higher resolution G3 version that did not got wide deployment) fax machine 'contact' (direct touching document, no lens) linear 1-D CCD sensor is about 100 dot per inch if my memory is correct.

author: coppice
author_rank: Super Contributor
timestamp: June 14, 2024, 09:14:28 pm
content: Quote from: Wilson__ on June 14, 2024, 09:04:39 pmThere have been numerous types of touch screen offering only a small number of sensed areas. They have often used a coating on the surface of the glass, with contacts resistively bridged by a finger.QuoteIf you look at the infra-red touch sensors in cars and e-book readers they put something like those FAX machine strips behind the panel, with a light pipe that wraps over the edge of the panel. The part above the panel is very slim, so the border only has to be raised a small amount above the display panel itself.

author: Wilson__
author_rank: Frequent Contributor
timestamp: June 14, 2024, 09:27:48 pm
content: Many thanks. Just curious. Traditional black-and-white LCD are metal traces on glass and quite high resolution by 1986, 640 x 200, IBM PC Convertible. Not sure if it was ITO or other metal??

author: coppice
author_rank: Super Contributor
timestamp: June 14, 2024, 09:35:14 pm
content: Quote from: Wilson__ on June 14, 2024, 09:27:48 pmGood question. I don't know. However, before the iPhone was launched HTC had one phone with a cap touch display in small volume, very unprofitable production. People in Taiwan we were talking to at the time, serving both Apple, HTC and others who were trying to jump on the bandwagon, were struggling with this problem.

author: tooki
author_rank: Super Contributor
timestamp: June 14, 2024, 11:06:08 pm
content: Quote from: dferyance on June 14, 2024, 06:59:47 pmMaybe resistive is more precise in theory, but in practice they’re way worse. One big reason for this is that resistive touch screens must be carefully calibrated (remember doing that on Palm handhelds?), while capacitive ones don’t need that since the grid is precisely placed at the factory.

author: wraper
author_rank: Unknown
timestamp: June 18, 2024, 12:06:05 am
content: Got to one of those IR touch devices I talked about, this one is 29 years old.