Ch.5 Input and Output Devices

Question 1

5 examples of output devices

Answer 1

1. Inkjet printer
2. Laser printer
3. 3D printer
4. Speaker
5. Projector

Question 2

5 examples of input devices

Answer 2

1. Scanner
2. Microphone
3. Keyboard
4. Sensor
5. Barcode reader

Question 3

How does a capacitive touchscreen work?

Answer 3

• Made up of many layers of glass that act like a capacitor, creating electric fields between the glass plates in layers.
• When the top glass layer is touched, the electric current changes, and the coordinates where the screen was touched is determined by a microprocessor

Question 4

4 benefits of a capacitive touchscreen

Answer 4

• Medium cost technology
• Screen visibility is good even in strong sunlight
• Multi-touch capacity
• Very durable screen

Question 5

2 drawbacks of a capacitive touchscreen

Answer 5

• Only the use of bare fingers is permitted

- Special stylus is allowed

Question 6

How does a heat-sensitive INFRA-RED touchscreen work?

Answer 6

• Uses glass as the screen material

- Needs a warm object as an input

Question 7

3 benefits of an INFRA-RED touchscreen

Answer 7

• Allows multi-touch capacity
• Good screen durability
• Optical system allows bare fingers, gloved fingers or a stylus for input

Question 8

3 drawbacks of an INFRA-RED touchscreen

Answer 8

• Heat-sensitive system only allows the use of bare fingers for input
• Very expensive
• Good screen visibility in strong sunlight

Question 9

How does an optical INFRA-RED touchscreen work?

Answer 9

• Uses glass as the screen material
• Sensors form a grid
• The location of the touch is calculated using the coordinates in the grid

Question 10

How does a touchscreen work (general)?

Answer 10

• Sensors are located on the edge of the screen
• Electric field all over the screen
• When the finger touches the screen, the charge is transferred to the finger
• Coordinates of the touch is calculated

Question 11

How does a resistive touchscreen work?

Answer 11

• Top layer: polyester
• Bottom layer: glass
• When the polyester layer is touched, the top layer and the bottom layer complete a circuit
• Signals are interpreted by a microprocessor, the calculations determine the coordinates of where the screen was touched.

Question 12

2 benefits of a resistive touchscreen

Answer 12

• Cheap

- Can input with bare fingers, gloved fingers, or a stylus

Question 13

3 drawbacks of a resistive touchscreen

Answer 13

• Bad screen visibility in sunlight
• Does not permit multi-touch capability
• Bad screen durability

Question 14

How does an inkjet printer work?

Answer 14

• Data is stored in printer buffer
• Uses liquid ink cartridges
• Uses thermal bubble
• Rollers used to move the paper
• Uses a moving print head
• Sprays ink onto the paper
• Different colour inks are mixed to create required colors

Question 15

How does a laser printer work?

Answer 15

• Uses dry powder ink/toner
• Data stored in printer buffer
• Uses charged print drum
• Uses static electric charges
• Toner is fused to the paper
• Positive charge is replaced by negative charge

Question 16

How do 3D printers work?

Answer 16

• Uses resin
• Solid is built up in thin layers
• Uses a moving print head

Question 17

What does QR stand for?

Answer 17

Quick Response

Question 18

Explain how the system scans the QR code and checks if a person can enter.

Answer 18

• Laser shone on QR code
• Black squares reflect different light to white squares
• Pattern is converted from analogue to digital by an ADC
• The data is sent to a microprocessor
• There is a database of valid QR codes
• The data is compared to stored values
• If data matches, entry is allowed
• If data does not match, entry is no allowed

Question 19

How does a barcode reader work?

Answer 19

• Shines light at the barcode and light is reflected back
• The black bars in the barcode reflect less light than the white bars
• Sensors read the data
• The pattern is converted from analogue to digital data by the ADC
• Microprocessor interprets data

Question 20

Advantages of using barcodes to the management

Answer 20

• Can check stock levels
• Can check if there is stock in a different location
• When new stock items arrive, the stock levels are automatically updated in the database
• Can check price