Ch.5 Input and Output Devices Flashcards
5 examples of output devices
- Inkjet printer
- Laser printer
- 3D printer
- Speaker
- Projector
5 examples of input devices
- Scanner
- Microphone
- Keyboard
- Sensor
- Barcode reader
How does a capacitive touchscreen work?
- 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
4 benefits of a capacitive touchscreen
- Medium cost technology
- Screen visibility is good even in strong sunlight
- Multi-touch capacity
- Very durable screen
2 drawbacks of a capacitive touchscreen
- Only the use of bare fingers is permitted
- Special stylus is allowed
How does a heat-sensitive INFRA-RED touchscreen work?
- Uses glass as the screen material
- Needs a warm object as an input
3 benefits of an INFRA-RED touchscreen
- Allows multi-touch capacity
- Good screen durability
- Optical system allows bare fingers, gloved fingers or a stylus for input
3 drawbacks of an INFRA-RED touchscreen
- Heat-sensitive system only allows the use of bare fingers for input
- Very expensive
- Good screen visibility in strong sunlight
How does an optical INFRA-RED touchscreen work?
- Uses glass as the screen material
- Sensors form a grid
- The location of the touch is calculated using the coordinates in the grid
How does a touchscreen work (general)?
- 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
How does a resistive touchscreen work?
- 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.
2 benefits of a resistive touchscreen
- Cheap
- Can input with bare fingers, gloved fingers, or a stylus
3 drawbacks of a resistive touchscreen
- Bad screen visibility in sunlight
- Does not permit multi-touch capability
- Bad screen durability
How does an inkjet printer work?
- 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
How does a laser printer work?
- 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
How do 3D printers work?
- Uses resin
- Solid is built up in thin layers
- Uses a moving print head
What does QR stand for?
Quick Response
Explain how the system scans the QR code and checks if a person can enter.
- 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
How does a barcode reader work?
- 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
Advantages of using barcodes to the management
- 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
