Stylus design

Thread Starter

Arjune

Joined Jan 6, 2018
354
My finger works on my Lenovo tablet touch screen but not my stylus. Doesn't the stylus have to have conductive rubber at the tip because it have to pick up the electrostatic force of the body for a capacitive screen? This would mean that the body of the stylus would also have to be metal to conduct electricity. I tried measuring the resistance of the robber on my stylus' tip but they have infinite resistance or non-conductive and above 20 megohms. How are your stylus' possibly working?
 

ZCochran98

Joined Jul 24, 2018
351
The capacitive touchscreens work by the screen detecting a change in the electric field around a point. Your finger is also incredibly resistive (mine is on the order of several megaohms), but stores charge well (it's a decent dielectric) - what causes the change in electric field is the vast difference between the dielectric constant of air and that of your finger. So, if you design another insulating material to have similar dielectric properties as skin, then you can mimic the behavior of your finger.
Wikipedia has a good article on it if you want to learn a little more about the specifics in greater detail.

Why your stylus isn't working with your screen depends on the type of touch screen or the stylus itself. I would imagine it's capacitive-touch, as that's a majority of touchscreens nowadays. With that said, however, it could also be that the touchscreen is designed with very specific conditions (for instance, depending on how sensitive it is to capacitive changes or how precise the change needs to be), so a stylus may or may not work with it.
 

ZCochran98

Joined Jul 24, 2018
351
I should also add that, for basic styluses, the metal body of the stylus resistively couples your finger to the rubber tip, so it's like connecting a several capacitors together - they stylus by itself may not be sufficient.
 

Thread Starter

Arjune

Joined Jan 6, 2018
354
Sorry I don't believe the logic. The dielectric is the rubber tip of the stylus and it is not conducting the electrostatic field of the fingers to cause a change in capacitance on the screen. Why it functions is without reason so something, possibly the spirit, is controlling the supernatural.
 

ZCochran98

Joined Jul 24, 2018
351
Sorry I don't believe the logic. The dielectric is the rubber tip of the stylus and it is not conducting the electrostatic field of the fingers to cause a change in capacitance on the screen. Why it functions is without reason so something, possibly the spirit, is controlling the supernatural.
While I do not argue that the supernatural exists, it has nothing to do with how this works. It's certainly not "without reason" why it works.

Here's an article from AAC about capacitive-touch sensors. It explains, in good detail, how it works.

In fact, a human isn't even required to make a touchscreen work. A simple experiment you can do (if you have the patience and don't mind getting a couple drops of water on a touchscreen) is this: put on a leather or rubber glove and get some pliers. Open the pliers just enough (~1-2mm) so that if you (gently) pour water on the end a droplet should stick in the small opening (due to water cohesion and adhesion). You may have to close the pliers slightly to "squeeze" the water to the end of the pliers. Carefully touch the screen with the wet end of the pliars, making sure that the water droplet makes contact with the screen. The screen should respond at the location the water droplet is touching. It needs to be a small droplet, or the sensor won't properly work, which is why I mention using pliers. It may take a few tries to get working properly, and once the water droplet is smeared over the screen (so after a couple touches), you'll have to get a new water droplet on the pliers (and probably dry your screen off).

Using a stylus is similar: the rubber itself is nonconducting, but can hold charges. When placed on the surface of the screen, the local electric field passes through the rubber, causing the charges in it to align and the electric field to amplify slightly (passing through the rubber, which can amplify electric fields by a factor of 3 or 4). Because it is attached to metal, the edge of the electric field conducts over the surface of the metal (which should, ideally, have a uniform potential across the entire surface) and also connects to your finger, which also then further amplifies the electric field, increasing the overall capacitance even more.

You can either choose to believe me or not: that's up to you. I'm just explaining the physics behind it. In the case of your stylus, it just may not work with the screen you have - it depends on the type of the screen or its sensitivity, or even how old the stylus is. Even how dry your hands are or the temperature and humidity levels can greatly affect whether a screen works or not.
 

Thread Starter

Arjune

Joined Jan 6, 2018
354
Living in America for so long I've noticed that white people (I'm not saying you are) are confident with their reasoning and that as an Indian I'm forced to follow along because I cannot disprove them since they (many) were educated in college and got a degree. I can understand if you think I'm wrong since my only reference is my belief and nothing material. Nobody really cares about me and how I think and maybe that is why I deviate from the norm. I blame this on psychiatry and the mental health system since they don't validate any paranoia that the patient may have such as myself. Someone, possibly and alien, was definitely patient in replying to me so I have to thank them for that. The barrel of my stylus looks like metal but I don't think it is and this forces the spirit to conform to the belief of understanding since it is forced to comply with the theory of relativity which creates a balance of action and reaction or belief or non belief since a force is applied to the stylus to operate. They (intelligence) don't want an error of space time (extra space) to create physical evidence that would show a reason to raise suspicion about fact-an action must create a certain result or it is false.
 
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