input devices

Question 1

describe 2D scanner

Answer 1

The user places the document face down on the glass
Light moves across document
Reflected light is captured
Uses mirrors and lenses
Captured image is converted into a digital file Produces a 2D digital image

Question 2

describe 3D scanner

Answer 2

Scanners shines a laser (or light) over the surface of a 3D object
Records measurements of the geometry/dimensions of the object
Measurements are converted to digital file
Produces a 3D digital model
this could be used in CAD

Question 3

describe barcode scanner operation

Answer 3

Shines light / (red) laser at barcode
Light is called an illuminator
Light is reflected back
White lines reflect light
Black lines reflect less light/absorbs light
Sensors / photoelectric cells detect the light
Different reflections / bars will give different binary values
pattern converted to digital values
A microprocessor interprets the data

Question 4

how barcode scanner is applied

Answer 4

barcode identifies a (unique) product
barcode can be used to look up product (in a database) data about stock levels can be stored on a system
stock can be automatically deducted from the system
can check stock is below a certain level // check stock level
automatic re-order
automatically update new stock level
to locate if an item of stock is available in another location

Question 5

advantages of barcode scanner

Answer 5

To management:
much easier and faster to change prices on stock items
no need to price every stock item on the shelves (this reduces time and cost to the management)
allows for automatic stock control
possible to check customer buying habits more easily by linking barcodes to loyalty cards.
To customers
less errors
faster checkout

Question 6

describe QR code operation

Answer 6

quick response code
scans the QR code with the mobile device
Black squares reflect light different to white
Corner squares are used for alignment
App is used to read/interpret/decode the QR code
converts to digital data
links to a website/opens a document
can store the QR code to refer to again for the information

Question 7

differences between QR code and barcode

Answer 7

barcode 1D and QR code 2D
barcodes contain vertical lines and QR codes contain ‘squares’
QR code can hold more data than a barcode
QR code can be read from any angle, some barcode readers have to be lined up with the barcode
QR codes are faster to scan than barcodes
barcodes are frequently used at checkouts while QR codes are used for advertising

Question 8

operation of digital camera

Answer 8

The camera will break up what it sees through its lens into a grid of pixels
Each pixel is given a binary value –
Pixels form a grid (to create the image)
Each pixel has a color
Pixels are stored in sequence (in a file)
A shutter will open letting light onto a CCD sensor that is at the back of the lens
This information is interpreted as digital information and stored in the cameras memory.

Question 9

operation of keyboard

Answer 9

circuit board present at base of keys
A key is pressed that presses a switch
When a key is pressed it changes the current in a circuit The location of the keypress is calculated
An index of characters is searched to find the corresponding keypress

Question 10

operation of microphone

Answer 10

Converts sound into an electrical signal/voltage
used for voice recognition systems
used for computer interpreting words being said

Question 11

operation of interactive whiteboard

Answer 11

allows a user to write on a surface using a pen, the text and drawings can then be captured and stored for later use.

Question 12

types of touchscreens

Answer 12

resistive touchscreens
capacitive touchscreens
infrared touchscreens

Question 13

describe operation of resistive touchscreen

Answer 13

Screen has two / multiple layers
User presses on top layer
Top layer connects to bottom layer
creating a circuit
Calculation is carried out on where layers are connected
signals interpreted by microprocessor to determine location

Question 14

describe operation of capacitive touchscreen

Answer 14

is made up up of layers of glass
current sent/flows out from all 4 corners of the screen
sensors are used to read the electric field
when finger/stylus touches screen, charge transferred to user and current changes
the location of “touch” is calculated

Question 15

describe operation of infrared touchscreen

Answer 15

an “invisible” grid on the screen
sensors detect where the screen has been touched through a break in an infrared beam(s) −
the position where the screen touched is calculated
needs a warm object to carry out operations
heat sensitive

Question 16

features of resistive touchscreen

Answer 16

This touch screen can be used whilst wearing gloves 
doesnt have multi touch capabilities
it is cheaper than others
visibility in sunlight poor
screen wears out/scratches

Question 17

features of capacitive touchscreen

Answer 17

has quick response time
good visibility in sunlight
This touch screen has multi-touch capabilities
screen (glass) will shatter/break/crack (on impact)
(very) durable surface
This touch screen cannot be used whilst wearing gloves

Question 18

what are sensors

Answer 18

A sensor is a hardware device that will take measurement of physical properties like temperature, pressure or acidity.

Question 19

types of sensors

Answer 19

Gas
Infra-red
Light
Temperature
Pressure
Moisture / Humidity
Acoustic
PH
Magnetic Field

Question 20

stupid sensor microprocessor question

Answer 20

Suitable sensor (motion/infra-red)
Data converted (from analogue) to digital (using ADC) Data sent to microprocessor
Data is compared to stored value/range
if data matches/out of range action taken
nothing could happen
Continuous loop/process