Flashcards
Input and Output devices how they work
Cards in this deck (21)
- 12D scannera- Document is placed on a glass panel and then closed onto by the cover
- Document is illuminated by bright white light
- A scan head moves across the document scanning it. The scanned image gets sent through a lens by a series of mirrors
- The lens focuses the image where it is then sent to a CCD.
- The ccd are pixels which contain an electrical charge when light is shone onto it which turns the image into a digital form - 23D scanners- A solid has 3 dimensions - x, y and z.
- The scanners take several images at many points across these 3 dimensions eventually forming a 3d digital object. - 3Barcodes + Barcode readers- A barcode represents different numbers from 0 to 9 which are represented by different thickness and amount of light and dark lines.
- The scanner picks up onto these lines by putting a laser onto it and the light reflected allows it to form the barcode and read it. White parts reflect, dark absorbs. - 4QR codes- Made up of several filled in dark squares on a light background
- Can hold up to 7000 digits.
- Normally used for marketing where it can directly send someone to a website - 5Digital cameras- A photograph is captured when light passes through the lens onto a light sensitive cell.
- The cell is made of pixels.
- Pixels determine file size. - 6Keyboards- Each character on a keyboard has a ASCII value
- When a character is pressed it is converted into a digital signal allowing the computer to understand - 7Mouse- Modern day mouses use red LEDs to detect movement in the x-y direction, these mouses are a type of optical mouse
- 8Microphones- When a microphone picks up sound a diaphragm vibrates producing an electric signal. This analogue signal is converted into digital by a sound card (ADC) for it to be understood.
- 9Types of touchscreen- Resistive
- Capacitive
- Infra - red - 10Capactive touchscreen- Made up of many layers of glass that act like capacitor creating electric field betweeen glass plates and layers.
- When the top glass layer is touch the electric current changes and where the circuit has broken are how the cooardinates are determined by a microprocessor - 11Infra red (Optical or/and heat) touchscreen- Heat sensitive method uses a glass as the screen material and needs a warm object (i.e. finger) to carry out an input operation
- Optical method uses a glass screen.
It has an array of sensors in the form of a grid and the point of contact is based on which grid cooardinate is touched - 12Resistive touchscreen- Makes use of upper layer polyester (type of plastic) and bottom layer glass
- When touched in a spot the plastic layer touches the bottom layer to complete the circuit
- The signals are then sent out which are interpreted by a microprocesser and results in coordinates of where the screen was touched. - 13Sensors- Sensors measure physical quantities in analogue signals. It is then conrted into digital through an ADC converter so it can be understood by the computer.
- Types of sensors and uses.
- Temp, mosture/humidity (used in greenhouse), light (light levels), infrared/motion (automatic doors and burglars alarms), pressure (burglar alarms and automatic doors), acoustic (picks up noise levles), ph, gas, magnetic field. - 14Inkjet printers- The inkjet printer is based on the ink cartridges containing colours or black and white.
- A stepper motor and belt moves these cartridges across the paper.
- Ink comes out of the cartridge onto the paper to form the image needed at a very fast speed eventually producing the image.
- Ink comes out of the cartridge in two ways - by heating localised within the cartridge or electrical vibrations. - 15LASER PRINTER- Once instructed a primary charged roller will rotate next to the OPC drum. The PCR applies a negative charge to the OPC drum.
- A laser is then shone onto the drum through mirrors creating the image by exposiing the drum in positive charges.
- Tonner is moved across components which makes a negative charge which sticks to the OPC positively charged areas. The toner on the drum is then transferred to the paper where it passes the fusing assembly to melt and fuse the toner. - 163D printers- Additive technology
- Design is made by CAD which is turned into a format for the printer to understand.
- The printer uses a nozzle that extrudes molten plastic and creates several layers until the object is finally formed. - 172D and 3D cutters -0- Subtractive technology
- Both cutters work similarly but just 3d cutters work on x,y,z axis instead of just x and y.
- Both cutters use a high powered laser cutter that is able to cut into the object with precision. - 18Speakers/headphones- Basically the computer sends out digital signals which a DAC converts into anologue and it is amplified out of the speaker.
- The sound is produced by voltage differences vibrating a cone in the speaker hous a different frequencies and amplitudes. - 19LCD monitorIt uses a backlight which shines into a horizontal polarizer, liquid crystals, vertical polariser and then the pixel. The pixel is broken into sub pixels which have a colour range of 255. The liquid crystals main job are too stop the light or let it go when the pixel needs to be illuminated the eventually forming the needed image.
- Uses bright flourescent backlight - 20LED monitorsIt is the same as LCD display however instead of bright flourecent backlight it uses LED diodes.
- 21OLED monitors- An OLED diode is made of six different layers with two of them retaining organic properties. When current is passed through these diodes, these organic layers produce light which passes through a colour refiner that produce picture on the screen
- This means that backlit setup that isn't used makes the screen way thinner
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- Year 10 Computer Science Flashcards on Input and Output devices how they work, created by fiery Barbarian on 23/01/2022.
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