COMPUTER SCIENCE - SOFTWARE AMD HARDWARE - INPUT DEVICES AND SENSORS -…
COMPUTER SCIENCE - SOFTWARE AMD HARDWARE - INPUT DEVICES AND SENSORS - CHAPTER 5 / 6 / 1.3.3
An input device is a hardware device that allows data to be input into a computer system.
Software - programs and instructions run on a computer.
Hardware - the physical components of a computer.
Keyboards are one of the main and most common methods of entering data on a computer. A concept keyboard is a specialist keyboard with limited, specialised, programmable functions, for example the electronic menu in a fast food restaurant.
Advantages - simple to use, can be very efficient if a typist is inputting data.
Disadvantages - easy to make a mistake when inputting data, for non typists it can be slow and inefficient.
A mouse is an input device that is used to navigate to a point on a screen. There are different types of mouse: The older style mice have a ball on their under sides that move internal rollers; newer mice have optical lasers that track the movement of the mouse across a surface.
Advantages - simple to use, allows for navigation across a screen.
Disadvantages - requires a flat surface, if a roller gets clogged or dirt covers the optical laser the mouse can stop working properly.
You also get tracker ball mice, a ball you move with your finger, and foot mice, that are controlled with the feet.
A digital camera records and encodes digital images and videos and stores them for viewing and later use.
Encoding - the process of converting data or information to a particular form.
They capture images with a sensor called a Charge-Coupled Device or CCD; the larger the number of pixels the CCD is capable of the better the quality will be.
Advantages - image can be seen immediately on the screen, backup copies can be easily made, they can easily be shared as they are an electronic copy, can easily be edited as it is an electronic file.
Disadvantages - some cameras quality is worse than a camera that uses film, easy accidental mistakes with a digital camera could delete the image or share it, they have a limited storage space.
A touch screen is a device that combines an LCD (Liquid Crystal Display) visual display with touch-sensitive sensors. The sensors recognise simple touches.
More complex touch screens can recognise gestures, such as swipes, to do more than click buttons; they can switch between application for example.
Capacitive touch screens uses the natural electrical signals we have in our bodies to detect touch, cannot detect through gloves.
Resistive touch screens have multiple layers with space between so when pressure is applied the screens touch so it knows that it has been touched. Is cheaper.
Advantages - simple to use, save space as they combine an input device and a screen.
Disadvantages - can be quite imprecise, inputs can be impossible if screen is damaged.
An interactive whiteboard is a virtual whiteboard that works in a similar way to a touch screen. Interactive whiteboards are widely used in education, business and sport.
Is an input device only and connects to a computer via a Universal Serial Bus (USB), it is projected onto a board, the user touches the board with a special pen and sensors pick it up and translate it into a digital action.
Advantages - they are quite versatile, they can be: drawn on, written on and display images and text, offer a large screen.
Disadvantages - must be calibrated otherwise touch is registered incorrectly, can be quite imprecise.
A microphone is an analogue input that records sound.
Analogue-to-Digital Converter (ADC) - a device that converts analogue data into digital data.
Advantages - allow the use of speech recognition systems, disabled users can use a microphone to input commands to a computer.
Disadvantages - sound might not be accurately recorded speech recognition systems have to be trained and do not work very well with accents.
Scan a physical document by shining light onto its surface.
For black and white printing the scanner only shines a light on the pixel it is scanning, and if light is reflected then there is no dot there – it is white. Whereas if there is a no light reflected, then there is a dot to be put there – it is black.
With colour printing, there are three bits of information per pixel, as there are three different sensors used to sense green red and blue light, or cyan magenta and yellow light.
The scanner scans pixel by pixel, and saves the data onto the computer so that it knows how to print the image.
Advantages - flatbed scanners can produce high quality documents, some digital copies can be edited software such as graphic creators, photograph editors and word processors, can be included in an email or another digital document.
Disadvantages - documents can use a lot of memory space, especially photographs, not the same quality as the original, especially photographs.
Produce a 3D model using a laser or a light source or sometimes an x-ray to measure and input the geometry of an object into a computer system. They are used today as security measures at airports.
Bio-metric devices use scanners to identify people such as fingerprint scanners or facial recognition software.
Codes represented by black and white vertical bars. A bar-code reader scans a bar-code and translates it into a series of numbers.
They are printed on every product sold and bought, as it is scanned and then read automatically, bar-code readers provide a fast and reliable way of entering data.
A red light called an illuminator is shone onto the bar-code which reflects back from the bar code and is picked up by the sensor which converts the analogue data into digital data which is then sent to a decoder and after it is decoded it is sent to a computer.
Advantages - efficient method of entering data to find out product pricing and other information, can help keep record of stock levels for a product.
Disadvantages - if it is damaged or not printed clearly it may not scan properly, if the bar-code data is not recorded in the computer the scanner will not be able to find it.
Quick Response Codes
QR codes are made up of black and white squares. QR codes can link to many things such as a website, a video or a social networking profile, they are an excellent marketing tool. QR codes are scanned and read using a QR code reader.
Three large squares in the corner tell the scanner the edge of the side and the small code in the bottom right tells the scanner the scale of the code.
A bar-code can store up to 30 numbers a QR code can store up to 7000.
A QR reader is a piece of software inside a device such as a smart phone.
Advantages - efficient method of storing information and linking to it, can include a variety of information, the code can often still be read even if some areas are covered up.
Disadvantages - not yet as common as bar-codes so some people may not know what they are for, people need to have the a device that can read them such as a smart phone.
A sensor is a type of input device that detects a change s in the environment around it.
A temperature sensor is a device that measures heat generated by an object or system. By measuring the change in heat, the sensor can detect any changes in temperature. They are used : to regulate temperature, to control televisions, in security camera and in astronomy.
Thermostat - a device that keeps temperature at a constant level.
Another sensor that measures temperature is an infrared sensor. Infrared sensors detect infrared radiation that emits from a person or object.
A light sensor is a device that detects light. It will detect the ambient light level, meaning how bright or dark it is. They can be used: as street lamps, in mobile phones, in bar-code readers and allowing robots to 'see'.
A motion detector detects movement.They are used: in security systems, to open doors, to turn on lights, in gaming.
Accelerometer - a device that detects rotation and tilt.
Magnetic field sensors detect changes in magnetic fields. It will measure the strength and direction of a magnetic field and respond to its changes.The Earth itself has a Magnetic field. They are used: in mobile phones to turn off screens (with the cover).
A gas sensor can detect the presence of gas in a certain area. It will measure the amount of gas in a certain area and can trigger a response if the amount gets to high or too low. They are used: to detect the presence of carbon monoxide and in nuclear plants to detect toxic gas leaks.
A pressure sensor measures pressure. They are used: to measure the pressure of liquid through the pipes,
MOISTURE AND HUMIDITY
Moisture sensors measure the amount of moisture in a certain material whereas a humidity sensor or hygrometer measures the amount of moisture in the air, along with its temperature. They are used : to detect the moisture levels in water, to stop spread of bacteria at home and in museums to prevent damage to artefacts.
Automated - a process that is automatic.
A pH sensor measures how acidic or alkaline a material is. They are used: in water treatment plants and in aquariums.