External Hadwear Devices

Question 1

How does a digital camera work?
In steps

Answer 1

1. When a photograph is taken the shutter opens and lets light in through the lens
2. The light is focused on to a sensor which is usually either a charge coupled device or a complementary metal oxide semiconductor
3. The sensors are made up of millions of transistors, each of which stores the data for one or more pixel
4. As the light hits the sensor it is converted into electrons and the amount of charge for each pixel in digital form.
5. With light all colours can be made from RGB.
6. Therefore to record colour you need three filters one for red one for green and one for blue
7. The data is typically stored on removable storage devices usually referred to as flash memory
8. Data is typically stored in compressed files eg PNG
9. Raw files can also be generated which are uncompressed and therefore contain all the data form the original photograph.
10. This digital data can now be decided and manipulated using specialised software

Question 2

How does a barcode reader work?
In steps

Answer 2

1. A light usually LED or laser is passed over an image
2. Some form of light sensor is used to measure the intensity of light being reflected back. Thks is converted into a currently effectively generating a waveform. Thks could be achieved using a photodiode or a CCD sensor
3. White areas reflect the most and the black the least making it possible to use the waveform to distinguish the patterns of black and white bars.
4. The waveform is analogue and therefore needs to be converted using an analogue to digital converter
5. The encoding will convert the black and white bars into binary codes eg white = 1 black = 0
6. The signal is decoded into a form that can then be interpreted by a software

Question 3

How does RFID work?
In steps

Answer 3

1. RFID Tag: This is a small device, typically attached to an object, containing a microchip and an antenna. The microchip stores information, and the antenna is used to transmit and receive signals.
2. RFID Reader/Scanner: This device emits radio waves through an antenna. When the RFID tag comes within range, the tag’s antenna picks up the radio waves emitted by the reader.
3. Energy Transfer: If the RFID tag is passive (most common), it doesn’t have its own power source. Instead, it uses the energy from the reader’s radio waves to power its microchip temporarily.
4. Data Transfer: Once powered, the RFID tag sends the stored information (such as an ID number) back to the reader using radio waves.
5. Reader Receives Information: The RFID reader captures the signal containing the data from the tag, and it decodes the information. This data is then sent to a connected computer or system for further processing, like logging the item’s location or identifying it.

Question 4

How does a laser printer work?
In steps

Answer 4

1. A rotating drum inside the printer is coated in a chemical which holds an electric charge.
2. The laser beam is reflected onto the drum and where the light hits the drum the charge is discharged effectively creating the image on the drum
3. As the drum rotates it picks up toner which is attracted to the charged part of the drum
4. As the drum rotates it picks up toner which is attracted to the charged part of the drum.
5. Paper is passed over the drum and by charging the paper with the opposite charge to the toner the toner is attracted to the paper and away from the drum.
6. The paper is then heat treated to fuse the toner onto the paper