[Q] How does touch sensitivity work? - Galaxy S 5 Q&A, Help & Troubleshooting

Hi,
I recently noticed that with my Galaxy S5 set to touch sensitivity mode it can sense touches from my finger even when I'm not actually touching the screen. This isn't a problem or anything, I love the option and use it all the time with gloves, but I'm just curious about how it actually works. From my limited knowledge about capacitive touchscreens it really makes no sense to detect touches when no physical connection is made, but it works in practice so I'm totally confused.
Thanks in advance!

Small electrical charge over the digitizer on the screen, your finger breaks the charge and the phone knows where, increasing the charge over the digitizer allows you to break that charge before actually touching the screen
That's how I understand it anyway, might not be 100% accurate

Related

Adjust screen sensitivity?...

I have been searching for the past few hours but have found nothing on the subject...
Does anyone know how to increase the sensitivity on the Sapphire? Is there a way to disable the "heat sensing" part of the touch screen (my wife has acrylic nails and a stylus doesn't work either)
Thanks
MrCheese
You cannot change the capacitive screen. So no nails and stylus...You can get a Tattoo (resistive screen)
but what about the sensitivity?
is there a way to change it?
the rom i'm currently using seems to have made the onscreen keyboard less sensitive when in landscape mode.
I think I read that external power source = greater screen sensitivity, I doubt that will help you though.
I have added a screen protector today and it seems to have had a positive impact on the screen responsiveness. When playing games my screen pretty much went dead form all the finger print grease. Glasses cloth ftw.
Edit: Have you turned off vibrating keys? nice as it is it definitely made me miss key presses.

touchscreen unresponsive when phone is on flat surface

sometimes my phones touchscreen becomes unresponsive when its flat on its back on a table for example. I unlock the screen with the trackpad or power button so that the screen comes on. Then when i try to slide the lockscreen it doesnt do anything. When i begin sliding the bar from the total edge of the screen it sometimes works.
Usually i just have to pick up the phone to get the touchscreen working again. actually, when i even lift up the phone the slightest bit, it works again.
Weird right?
anyone else experiences this issue ?
I assumed it was designed to work like this. Makes me move my phone rather than just slide to snooze the alarm then go back to sleep.
Same here. I think it has to do with the capacative toucscreen.
Sent from my HTC Vision using XDA App
wileykat said:
I assumed it was designed to work like this. Makes me move my phone rather than just slide to snooze the alarm then go back to sleep.
Click to expand...
Click to collapse
you're saying you move your phone to snooze the alarm? didnt know it could do that, gonna try that out tomorrow morning
forgot to mention the issue is not ROM specific. I have witnessed it on virtuous, CM, MIUI, stock
Ive had this problem as well. Slightly annoying!
I don't think its a design issue..
you don't have to lift your phone to get the screen to respond.
notice that it is enough just to touch the body of the phone to make the screen responsive again..
for me its very annoying, especially not being able to snooze the alarm in the morning
Let me point out that this happens with my G1 also so its not just the G2.
Yeah, there are a few discussions about this on the forums already. It's most likely a capacitance issue. When your phone is just sitting on a table and you touch the display, you may not create enough capacitance with the touchscreen for it to register as a touch (as opposed to resistive touchscreens which needed only physical contact but were less accurate as a result). Touching the body of the phone basically creates a common ground or voltage reference point for the phone, allowing your finger to create the needed amount of capacitance (in technical terms, no longer a floating ground). Whenever I touch the screen while the phone is lying on a table, I just always make sure to rest either my thumb or ring finger on one of the edges.
A lot of factors will also come into play---whether or not your phone is in a case, type of material the phone is resting on, the level of humidity in the air, even potentially the type of shoes you are wearing. This is why sometimes it works and sometimes it doesn't.
ianmcquinn said:
(...) Touching the body of the phone basically creates a common ground or voltage reference point for the phone, allowing your finger to create the needed amount of capacitance (in technical terms, no longer a floating ground). (...)
Click to expand...
Click to collapse
yes! I just figured this out myself. merely touching the body of the phone makes the screen respond to my fingers.
well in that case its not really a big problem. from now on i just touch teh body with my middle finger while sliding with my index finger =D
liory said:
notice that it is enough just to touch the body of the phone to make the screen responsive again..
for me its very annoying, especially not being able to snooze the alarm in the morning
Click to expand...
Click to collapse
Will give this a go tomorrow, I hope it doesn't work!!!.... I'm gonna be forever snoozing with 2 fingers now!!!
This seems to be temperature related (and it doesn't happen on a mytouch 3g)
I live in Minnesota and I deliver pizza. When I would need to call a customer to get into an apartment building, I would set the phone on top of the pizza bag and dial with one hand.
When I first got my G2 (early november) I had no problems doing this, then one day it wouldn't respond at all to touch. I still had my old mytouch 3g with me because the old number wasn't ported yet, and I was able to use that to make the call. It wasn't until later that I realized that the problem was caused by the cold and that I needed to touch the metal part to make it work, so I thought that the touchscreen on my 2 week old G2 had just died.
At room temperature the touch screen always works (I can silence the alarm while it's sitting on the table), but temperatures below 50F cause problems
I started noticing this as well. Sometimes I'll hit the power button to turn my phone on from idle-state and then I'll drag the unlock button with to no avail! But then again, I do use my thumb to do it so maybe the capacitance by using the thumb isn't good enough to unlock it.
I use my phone at work a lot so in order to text while being discreet, I usually have the phone in my right hand and text / unlock the phone using my thumb. I doubt it is a defect but it had me worried too. Guess I'm not the only one experiencing this. (Although I must say, dragging my thumb to swype and using the side of my thumb probably is the reason why it sometimes doesn't work)
Back when I had my g1 it did the same thing and experience this on my g2....if its laying down its like it thinks its just on in your pocket so the touch seems limited
Sent from my T-Mobile G2 using XDA App
Elegy said:
sometimes my phones touchscreen becomes unresponsive when its flat on its back on a table for example. I unlock the screen with the trackpad or power button so that the screen comes on. Then when i try to slide the lockscreen it doesnt do anything. When i begin sliding the bar from the total edge of the screen it sometimes works.
Usually i just have to pick up the phone to get the touchscreen working again. actually, when i even lift up the phone the slightest bit, it works again.
Weird right?
anyone else experiences this issue ?
Click to expand...
Click to collapse
Not weird. TOTALLY normal and expected.
It is because it has a CAPACITIVE TOUCHSCREEN.
This means that when you touch the screen, your finger is actually COMPLETING AN ELECTRIC CIRCUIT.
When the phone is lying on a table and you touch it, you are NOT completing the circuit since you are NOT touching the phone's body.
When the sensor is on, there is an electrical difference between the surface of the screen and the body of the phone. When you touch BOTH, you alter the electric field in that localized area of the screen. The sensor detects the change in voltage and determines the location of the contact.
dhkr123 said:
Not weird. TOTALLY normal and expected.
It is because it has a CAPACITIVE TOUCHSCREEN.
This means that when you touch the screen, your finger is actually COMPLETING AN ELECTRIC CIRCUIT.
When the phone is lying on a table and you touch it, you are NOT completing the circuit since you are NOT touching the phone's body.
When the sensor is on, there is an electrical difference between the surface of the screen and the body of the phone. When you touch BOTH, you alter the electric field in that localized area of the screen. The sensor detects the change in voltage and determines the location of the contact.
Click to expand...
Click to collapse
So how do I adjust the sensitivity? As I understand it I could increase the voltage to the screen making it easier to complete the circuit...such as through thin gloves.....
Sent from my HTC Vision using XDA App
dhkr123 said:
Not weird. TOTALLY normal and expected.
It is because it has a CAPACITIVE TOUCHSCREEN.
This means that when you touch the screen, your finger is actually COMPLETING AN ELECTRIC CIRCUIT.
When the phone is lying on a table and you touch it, you are NOT completing the circuit since you are NOT touching the phone's body.
When the sensor is on, there is an electrical difference between the surface of the screen and the body of the phone. When you touch BOTH, you alter the electric field in that localized area of the screen. The sensor detects the change in voltage and determines the location of the contact.
Click to expand...
Click to collapse
This is mostly true.
Put the phone on the table and dont touch it and try to swipe to unlock.
No touch a finger on the phone body and do it again, itll work.
Doesn't seem to always fit that behavior, but more often than not.
TheNewGuy said:
So how do I adjust the sensitivity? As I understand it I could increase the voltage to the screen making it easier to complete the circuit...such as through thin gloves.....
Click to expand...
Click to collapse
You don't. You should NOT even if you could. It would not work as you expect since it is NOT a matter of sensitivity, but of CONDUCTIVITY.
klmsu19 said:
This is mostly true.
Put the phone on the table and dont touch it and try to swipe to unlock.
No touch a finger on the phone body and do it again, itll work.
Doesn't seem to always fit that behavior, but more often than not.
Click to expand...
Click to collapse
It is not "mostly" true, it is PRECISELY true.
dhkr123 said:
It is not "mostly" true, it is PRECISELY true.
Click to expand...
Click to collapse
No reason for the condescending tone in every post (or if it's not your intention to be condescending, you may want to restrain your constant use of caps). You had stated:
dhkr123 said:
This means that when you touch the screen, your finger is actually COMPLETING AN ELECTRIC CIRCUIT.
When the phone is lying on a table and you touch it, you are NOT completing the circuit since you are NOT touching the phone's body.
Click to expand...
Click to collapse
Someone was just pointing out that if this was "precisely" true as you put it, then the screen should never be responsive if you aren't touching the phone's body (since the circuit is, based on your reasoning, still broken). This isn't the case though since it does work sometimes. How could your statement be precisely true if it's known to be false sometimes (hence the "mostly true" comment)?
And it's actually not true. You are not completing an electric circuit. No current flows from your finger into the screen and no components within the phone are electrically coupled because of your touch. As you stated, you are altering the electric field when you touch the screen. This results in a change in capacitance in that area. Note, this change occurs even when you are not touching the phone's body, just to a different degree. Touching the phone will typically increase the amount of capacitance as opposed to when you are not though (since you are basically "grounding" yourself to the phone). The more capacitance there is, the easier it is to measure. If there is too little capacitance, the touchscreen's microcontroller will not register the change at all. Even if it does register the change, there will be additional filtering that occurs to that raw data either in the microcontroller itself or in software (or both).
This is why the screen works sometimes when you touch it without touching the rest of the phone. You are still causing a change in capacitance. The amount of change depends on numerous factors (this is what I stated in an earlier post). These factors effect how grounded both you and the phone are relative to earth ground (in the electrical sense, not geographical). Typically speaking though, if you are relatively close to earth ground, then you will be able to use the screen without touching the body of the phone. For example, someone stated earlier that the screen doesn't work when it's cold. Cold weather results in lower humidity/drier air and you being less grounded (basically why people see an increase in static electricity as well). Chances are that the touchscreen would work again without the touching the phone's body if you had physically been touching a large piece of metal with your other hand (to help ground you).
So in response to the other question posed, yes, technically by raising the voltage level to the touchscreen, it may result in a more sensitive screen since there will be a larger increase in capacitance when you touch it. It may also reduce the life of the touchscreen though, if not damage it completely, so not a good idea. It would be better to figure out the filtering mechanism if possible and adjust that in software. Not sure if any devs have looked into it (though my guess is that if it was simple, it would have been done already).
I am so happy I found this thread..
Lately I thought my touchscreen was broken because I was unable to snooze my alarm in the morning (just as some of you seem to have been trying to do).
I think it's temperature related as suggested by the person who mentioned pizza delivery.. and I think this because it only happens on mornings where I've left the bedroom window open and it's very cool. My phone is often on a cold wooden surface. however even picking up the phone doesn't seem to help (I'll have to pay more attention next time) but after a few moments of struggling it eventually works (probably warms up in my hand and gets a better circuit).
I can also vouch that the screen works great with just a single finger on a flat surface, provided it's room temperature. I don't need to touch the body at all, and I do this a lot without issues (aside from cold mornings waking up to my alarm).

[Q] touch sensitivity too sensitive?

Hi All,
I have recently bought S4 and I'm having a small issue with it.
first of all, I turned off the "More Sensitive" feature in the setting, and "vibration on touch" is on.
However, I occasionally feel that touch is pressed before my finger actually touches the screen (the phone vibrates and types before I touch the screen when my finger is about 2~3mm apart from the screen), and it seems it's not consistent about it (some times it touches with 2~3mm gap and sometimes it doesn't).
I have even tried with the "display touch" from the developer mode and verified that it indeed touches with 2~3 gap...
The problem is...the ATT guy looked at me as if I'm overly sensitive about this...(the typical look of 'man this is just a phone')
Is anyone having this issue?
whitewjh said:
Hi All,
I have recently bought S4 and I'm having a small issue with it.
first of all, I turned off the "More Sensitive" feature in the setting, and "vibration on touch" is on.
However, I occasionally feel that touch is pressed before my finger actually touches the screen (the phone vibrates and types before I touch the screen when my finger is about 2~3mm apart from the screen), and it seems it's not consistent about it (some times it touches with 2~3mm gap and sometimes it doesn't).
I have even tried with the "display touch" from the developer mode and verified that it indeed touches with 2~3 gap...
The problem is...the ATT guy looked at me as if I'm overly sensitive about this...(the typical look of 'man this is just a phone')
Is anyone having this issue?
Click to expand...
Click to collapse
I have rarely noticed this myself, but usually only a 1mm-2mm gap for me, and maybe once every couple days. Really infrequent. On an older phone of mine, the cheaply-made car charger I was using caused my touchscreen to flip out and become super-sensitive. Might have been a static-to-ground issue or something weird.
Does it happen when you have it plugged in only, or does it happen while disconnected?
Also, speaking on static electricity, is it dry in your area? Do you have problems shocking things?
*shrug* only some suggestions. Could be a miscalibrated or otherwise defective touchscreen...
Mine also does this, whether plugged in or not it does it.
Nor do I have a problem with static in my house.
My best guess would be the air view sensor is falsly detecting the small distance away as an actual touch.
Sent from my Galaxy S4 using Tapatalk

When car mounted, top portion of the screen becomes less responsive to touch

Trying to lower the top bar is practically impossible... Anyone else has this problem? Could this be a problem caused by the screen protector?
Noam23 said:
Trying to lower the top bar is practically impossible... Anyone else has this problem? Could this be a problem caused by the screen protector?
Click to expand...
Click to collapse
I have the same problem but my problem is not limited to just the top part. i am having trouble with taps and swipes across the whole screen
Me too, I noticed my knock on wasn't working at all, but knock off worked fine...Then I noticed that if I drag the notification bar down really slowly about half inch down it just snaps up as if I lifted my finger, almost like its not detecting touch anymore when it reaches that section. My phone has worked great for 3 weeks, what could be causing this all of a sudden?
Is there a charger in the dock?
Lots of devices get touch screen issues when charging. (I have to double tap everything on my Tablet when it's charging). Some have bigger issues than others. Depends on how good the battery is shielded.
I almost never notice it on my G2 though. Only a tad. Depends on how stable the currency is in my house (The problem is almost non existent at my home. At my mom it's just like my tablet. Have to double tap everything)
Could also be because of a magnet or something in the car dock.

grounding issue

I got a problem with ghost touches, which happen randomly, very annoying when typing especially when swipe typing
Sometimes when I just hover my finger near the screen without actually touching it, the screen registered a touch by itself
I believe this is a grounding issue since changing the touchscreen set didn't fix it, and I don't want to open it again just to put insulation tape on the aluminium body which touches the touchscreen's flex, since opening it have a great risk of breaking the touchscreen set again
So I try adding line
persist.usb.hvdcp.detect=true
Into the build prop, and it didn't help
Any better idea?
While charge or while portable without charge?
Without charge and with charge is the same

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