I bought a stylus kit, when making it, I wanted it a little longer than it was supposed to be. I figured since there's no ink refill going through that I could just cut the brass tube to an inch or so and just leave the center of the blank solid. That's how I made it, but the stylus wouldn't work, unless my finger was within an inch of the end. So, I disassembled it, remade it with a brass tube all the way through and it works great. Since wood doesn't conduct electricity, I have no idea why the brass tube needs to be all the way through. Does anyone know why?
Stylus Question
- Thread starter KenB259
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jttheclockman
Member
What are you using it on? There are many different types of stylist pads that use different technology.
egnald
Member
Ok - here it goes (sorry for being so verbose),
Most touch screens these days are capacitive touch screens so that they work by detecting the electrical charge provided by our fingers. In a nutshell, the stylus needs to transfer electric charges from your finger to the tip of the stylus where it interacts with the electric field of the capacitive touch screen.
Here is how a capacitive touch screen works. The basic capacitive touchscreen is essentially two layers of conductors with stripes running horizontally on one and vertically on the other. Usually the conductors are not just straight lines, but have a pattern to them to maximize their coverage. So the light passes through them, the conductors are typically made from Indium Tin Oxide which is a transparent conductive material that is coated on the surface (usually of glass) and then is photographically/chemically etched off in select areas to form the pattern - much in the same way that copper is etched away from a substrate to make printed circuit boards. There is also a thin transparent insulating material between the two layers.
One row, the driver, is connected such that it has a given electric current applied, usually scanned across rather than having all of them energized at the same time. The other row, the sensor, detects the electric current. The insulator between them forms a capacitor (by definition a capacitor is two conductors separated by an insulator). The current through the driver layer produces a negative field which induces a positive field in the sensor layer.
Since our bodies are relative good conductors, when our finger approaches the screen, it interacts and disrupts the electric field in the sensor layer by changing the amount of positive charge on the sensor layer. This change in charge changes the capacitance of that specific area. It is this change in capacitance that is detected, measured, and located on the grid. This change is interpreted as a touch input in a specific location (x-y coordinate) on the screen.
A stylus is intended to work as an extension of our finger. It needs to be a conducive object that disturbs the electric field on the touch screen just like our finger would. The little rubber tip of the stylus is made from a conductive rubber material (usually carbon impregnated). In other words, some kind of electrical contact with our body is needed to make the stylus appear as an extension of our finger. In addition to having a similar amount of conductivity as our finger, and since our fingers are not pointy, the stylus tip needs to be a little rounded (not pointy) too.
Most commercial styluses in the market either have a metal body or have metal components that are exposed on the surface that connect internally to the stylus tip. When one holds the stylus the electric charges from our body are extended to the stylus tip which then interacts with the electric field on the touch screen to generate the touch input.
So, the brass tube acts as a conductor from other parts of the pen/stylus to connect your bodies conductivity to the stylus tip.
I hope that helps answer your "why" - Dave
Most touch screens these days are capacitive touch screens so that they work by detecting the electrical charge provided by our fingers. In a nutshell, the stylus needs to transfer electric charges from your finger to the tip of the stylus where it interacts with the electric field of the capacitive touch screen.
Here is how a capacitive touch screen works. The basic capacitive touchscreen is essentially two layers of conductors with stripes running horizontally on one and vertically on the other. Usually the conductors are not just straight lines, but have a pattern to them to maximize their coverage. So the light passes through them, the conductors are typically made from Indium Tin Oxide which is a transparent conductive material that is coated on the surface (usually of glass) and then is photographically/chemically etched off in select areas to form the pattern - much in the same way that copper is etched away from a substrate to make printed circuit boards. There is also a thin transparent insulating material between the two layers.
One row, the driver, is connected such that it has a given electric current applied, usually scanned across rather than having all of them energized at the same time. The other row, the sensor, detects the electric current. The insulator between them forms a capacitor (by definition a capacitor is two conductors separated by an insulator). The current through the driver layer produces a negative field which induces a positive field in the sensor layer.
Since our bodies are relative good conductors, when our finger approaches the screen, it interacts and disrupts the electric field in the sensor layer by changing the amount of positive charge on the sensor layer. This change in charge changes the capacitance of that specific area. It is this change in capacitance that is detected, measured, and located on the grid. This change is interpreted as a touch input in a specific location (x-y coordinate) on the screen.
A stylus is intended to work as an extension of our finger. It needs to be a conducive object that disturbs the electric field on the touch screen just like our finger would. The little rubber tip of the stylus is made from a conductive rubber material (usually carbon impregnated). In other words, some kind of electrical contact with our body is needed to make the stylus appear as an extension of our finger. In addition to having a similar amount of conductivity as our finger, and since our fingers are not pointy, the stylus tip needs to be a little rounded (not pointy) too.
Most commercial styluses in the market either have a metal body or have metal components that are exposed on the surface that connect internally to the stylus tip. When one holds the stylus the electric charges from our body are extended to the stylus tip which then interacts with the electric field on the touch screen to generate the touch input.
So, the brass tube acts as a conductor from other parts of the pen/stylus to connect your bodies conductivity to the stylus tip.
I hope that helps answer your "why" - Dave
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Using it on an iPad.
jttheclockman
Member
I believe David answered your question and glad he did because he did it more clearer than I for sure. With your finger close to the stylist end you made the circuit. If you moved your hand further away it broke. With a full tube you can now make the circuit on the other end as well with your palm.
Verbose----- I like that Had to look that one up. At times I think I fall into that group. I am verbose. Most times it gets me in trouble too.
Verbose----- I like that Had to look that one up. At times I think I fall into that group. I am verbose. Most times it gets me in trouble too.
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monophoto
Member
"Verbose' has negative connotations.
I prefer to describe Dave's excellent discussion as 'complete'
I prefer to describe Dave's excellent discussion as 'complete'
egnald
Member
Yes, iPad, iPhone, and other Apple products use Capacitive Touchscreen technology. - Dave
monophoto
Member
Don't disagree, but - - -
I have several styluses (or styli if you studied Latin - which I didn't). Two of them seem to be universal in the sense that the work on both my Fire HD8 Tablet and my iPhone. But I have one that is double-ended - a large end and a small end) and that I know is made from solid brass. Both ends work on my tablet, but only the large end works on my iPhone.
Just a curiosity to talk about over a pitcher of beer.
jttheclockman
Member
Again what are the ends of the stylist made of? Is one side rubber and the other side solid or plastic? There are a couple different types of screens and I will again leave that to David to explain. Has to do with the way the screen is made and also the stylist type that works on them.
egnald
Member
I am guessing that it has to do with the small end not meeting the expected touch size of your iPhone. Most Capacitive touchscreens expect a finger which in the scheme of things has a fairly big contact area. I tried to elude to it in my comments about the stylus being non-pointy. The devices I am familiar with need to detect a touch of 4mm to 5mm in diameter (about 0.15 to 0.2 inches) and then the hardware or software approximates the center of the touch as the point contact.
Nearly all of the touch screens that our company (the company I retired from) manufactured were not Capacitive but were Optical using infrared emitters and detectors around the perimeter of the display. They also ignored small contact points like one would find with the tip of a pencil, but they would detect larger objects, like a pencil eraser.
Another type touch screen is Acoustic or Surface Acoustic which use ultrasonic wave emitters and detectors. It has superior brightness because it doesn't have any kind of conductive matrix blocking the light. It too can detect both conductive and non-conductive touches.
The last type that I am aware of is a Resistive touchscreen. Like the Acoustic and Optical the Resistive is capable of responding to non-conductive touches. It essentially has two layers, one conductive and one resistive separated by a small space. Pressure from the touch causes the layers to connect in order to sense the touch.
Dave
PS I've always been impressed by the chop you use as an avatar photo. A small shop on Shamiandao Island in Guangzhou, China carved one for my youngest daughter (Annie Jinfei) and one for me back in 2008 when we were there. (Also - a nice pitcher of Yuengling sounds great. - We can't get it way out here in Nebraska).