DIGITAL
SENSORS
Touch screens
◦ Work using stored electric charges.
◦ One way to store charge is using capacitor.
◦ a battery pulls the electrons off one plate and pushes
them onto the other, when the battery is disconnected the
electron will stay there because of dielectric.
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02
03
One plate is the
screen and the other
plate is your finger.
A sensing circuit
connected to the
touch screen .
When you touch
screen you are
changing the electric
field between your
finger and the plate .
Digital camera
◦ At the back of the digital camera is a charged-couples
device (CCD). (acts like a capacitors.
◦ When the radiation such as light hits the CCD, charged is
produced.
◦ The charge is stored in the component’s capacitor.
◦ The amount of charge depend on the intensity of light.
◦ The charge on each component is transferred to a circuit
that produces digital signal.
◦ The camera converts this signals into an image.
◦ The image is made up of small dots called pixels.
Electric fields:
◦ Is the field around the charge.
◦ Its like the magnetic field ( the area around the
magnet where magnetic force exists).