BARCODE

What's there in black and white lines...!!!

        We have seen black and white Zebra strips on every item from PEN to heavy machines. Have you ever wish to know how they are used.

 Coming to the point, bar-code contains black and white strips as we all know. we also knows that black color is a good observer of light and white is good reflector...........yes, there lies the concept behind the working of bar-code.

Bar-code scanner have two components.

1.Reflector

2.Receiver

Reflector of scanner will put a red light on to bar-code, when this light falls on bar-code, light which falls on black color strips doesn't reflect backs whereas light which falls on white strips will get reflected back to  scanner. This reflected back light is read by  Receiver and processor process the pattern of reflected back light and give entire details of the product

Add on:

  Every bar-code is a set of 95 evenly spaced columns. These 95 columns are divided into 15 different sections.

 12 of which are used for numbers at bar-code bottom and 3 are guards to bar-code. 

These guards unable the processor to know whether the bar-code is scanned in correct way or in upside down based on the pattern of reflected light.These guards are generally at left,middle and right portion of the bar-code.

How fuel gauge work ?

Fuel gauge is a simple device, consisting of 2 major parts:

1. Float in the fuel tank
2. Level indicator in the dashboard

The float in the fuel tank is attached to a resistor which is connected to battery and level indicator. Depending upon the level of fuel in the tank the resistance varies. This will makes the current flow fluctuations to the dashboard line.

 The indicator is calibrated depending upon the fuel level and current passing. Thus when the tank is full the float will be on the top of tank and resistor creates least resistance and hence high amount of current passes to the indicator which will makes the needle to deflect more and indicate the F and when the fuel level in the tank is low the float will be on the low level making more resistance to the flow of current to the dashboard and hence the indicator will drops to E

** content is limited to my knowledge and comments are most welcome

HOW A TOUCH SCREEN WORKS

There are mainly 2 types of touch screens that are widely used:

1. Resisitive touch screen

2. Capacitive touch screen

1.Resistive touch screen:
      Before going into the details of how it works, I wish to say what are its applications first so that we can better understand the topic

Applications:

        There are many applications of resistive touch screens some of them include

a) touch screens that we see in ATM's

b) touch screens used in supermarkets and malls

c) old touch mobile phones

 I quoted examples explaining the underlying concept just because this is what I expected in my school and college days from faculty so that I can have some interest in understanding what they are teaching.

Working principle:

The resistive touch screen consists of two transparent layers of glass or plastic that are coated with a conducting material like Indium Tin Oxide (ITO) and the coated sides of glass are arranged facing each other with a gap in between them

    When ever we apply pressure on the top layer it bends and touches the bottom layer which will create some kind of electrical disturbance at the point where we apply pressure. The x and y coordinates of this point exactly can be determined by sensor     

Pros and cons:

1. Unlike delicate capacitive touch screens these are hard in nature 

2. Multiple touches can't be detected so we can't zoom in ATM screen

2.Capacitive touch screen:

     capacitive touch screens make use of our body behaving like a capacitor (any object which has the ability to store charge). In capacitive touch screens electrodes of opposite charges are arranged perpendicular to each other all through the screen called as sensor grid. This sensor grid is covered by glass on top and bottom 

At the meeting point of these electrodes electric field will be created automatically.  So whenever we touch the screen at any point our finger (capacitor) will observe certain amount of charge creating a voltage drop at that point whose coordinates are then detected by sensors.

Applications:
        Present generation touch mobiles, laptops and many other

Add on's:

 In resistive touch screen we need to push the top layer so that it touches the bottom layer and in this process the screen bends little. And since resistive touch screens doesn't require any capacitor to make a voltage difference, this type of screens can work with any object pushing top layer .But in case of capacitive type it needs a object which acts like a capacitor so whenever we touch our mobile screens with clothes or things which are not capacitors they will not function and hence we can't use our mobiles with gloves to our hands 

** content is limited to my knowledge and comments are most welcome