Electronics basics : Why a broken screen still works when in use

3년 전


Image source

Hey steemits so the other day a group of my friends were having an argument (as usual) about a football match we saw recently. We then, during the course of the argument, decided to consult google. One of us then brought his phone to help us search online. Now his phone has a very cracked screen and still works very well asides from a few tweaks here and there. Now being as curious as i am i decided to do my own small research on why his screen was still working. Thus this blog post was born.

In this day and age we leave in we find that touch screens are a part of our every day life. From our phones to our palm tops and even some laptops to also our tablets. Also in the grocery stores where touchscreens are used at counters by the sales attendant, and the list goes on and on.
The sensitivity of this piece of tech varies from application to application and can be seen in daily usage for example one may notice that when using an ATM one may have to push harder on the screen to get a response than on phone screens where one has to only touch to get a response
Now to properly get into the above topic i would like to first give a more general overview.

First there are two main and commonly used designs of the touch screen which are

  1. Capacitive touchscreens
  2. Resistive touchscreens

This generally are the kind of touchscreens used in ATM's, in malls and also some commercial printers.
Basically they consists of two layers one which is basically a flexible conductive layer and a resistive layer. Both layers are then coated with a conductive material such as indium tin oxide thus allowing them to conduct current. This two layers are separated by tiny dot like materials called spacers. Thus when you push against the "resistive" screen a contact is then established. This then changes the voltage at the point where contact is made. This change is then detected by a small microprocessor or even a system and the instruction is then carried out accordingly.
This kinds of touchscreens have a very inconvenient problem which is they can't respond to multiple touches at the same time. But given that they are durable and very consistent, they are still in use


This picture shows a small demonstration on how it works Image source is a screen shot from here

Now this is kinda very different from resistive touchscreens in the sense that instead of having two materials separated and doing the sensing work, we have only one material. This is what is usually called the touch pad in the case of a phone. Now this pad is made of hair thin conductors put in the x and y coordinates. The one connected in the x direction or horizontally are called the driving lines which conduct electric current and the connection made in the y direction are called the sensing lines and they detect electric current. Now where they cross there is an electric field set up which is registered as neutral by the microprocessor or system. Now that all changes when something conductive comes along such as your finger. This is because the human body has the ability to conduct electricity and also store charge so thus when in contact with the screen a resultant field is set up that causes a change in the screens electric field and this is then detected by a processor which can then detect what operation was called on and execute it accordingly. Now the good thing is that most screens now are made so that even with a screen crack the touch pad wouldn't be affected instead the screen be broken

Now other worthy mentions are

  1. Infrared touchscreens: Now this work by having photocells and led's arranged in opposite sides of the screen.
    When contact is made on the screen the light sent to the photo sensors is interrupted and this interruption is then detected by the processor and then action is taken accordingly. This is mostly seen in the screen of the kindle fire device.
  2. Surface Acoustic Wave touchscreens :
    This is the newest and i believe to the most exiting of all. Now this basically makes use of ultrasound( high sound frequencies that cannot be detected by the human) that is reflected back and forth on opposite sides of the screen. When a touch is made there is and interruption in the wave reflection. This interruption is then detected by the sensor and thus the function required is carried out

Now if we look below we can see a picture of how a basic phone screen is assembled. We can see that the touch pad i.e the hearth of the phone touch screen is placed such that it is given maximum protection. Thus making it difficult for cracks to penetrate to it. Also added that most people now consider using screen guards that further reduce the ability of crack penetration


The Parts of a phone screenImage source

Now that we have solved that what other common screen problems have you encountered at least well now you know the cause and also how it is made

Also stay creative and i will see you next time

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Hi @chitrics. I think you have some problem with the way you were directing your picture's link to the original source. You need to link the picture's source to the appropriate website with some details of the original author's name and license version; not to a google search. Sure your first picture is public domain, therefore, you have no obligation of citing the source but always make a good habit of doing things right.



Thanks man but to be honest that's the problem i have actually gone through the guide lines for citing of pictures and one of the problems i have is that i actually dont know how to do the same for myself
If you can show me an example it will be really helpful
Thanks for the comment


Hi @chitrics!
I am posting this guide for images here too, so that more people can find it if they read this comment.
All the best,

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