Input and Output devices
Why do we need input and output devices?
Without it our computer wouldn’t be able to function as well and correctly. They are the mini components of a computer. A bit like a bike, without a component the bike wouldn’t work. Check out chapter 4 for more detail.
Input – used to provide data and control signals to an information processing system.
Input devices:
- scanners
- keyboards
- mouse
- sensors
- microphones
- digital cameras
Output – any device used to send data from a computer to another device or user.
Output devices:
- Printers
- Loudspeakers
- Projectors
- LCD/LED monitors
Printers:
Colour vs Monochrome laser printer:
Monochrome laser printers use a single black toner cartridge. Color laser printers use four: one each for cyan, magenta, yellow and black.
Monochromes printers are much faster than coloured ones .To achieve the same output speed as a monochrome laser printer, a color device requires additional engineering to optimize a more-complex process. Colour laser printers that transfer all four of their toners to a single drum — rather than applying one toner to the paper at a time with individual drums — must do more work than a monochrome device just to produce a single page. At the same purchase price, expect a monochrome device to outpace a colour laser printer.
2D scanners:
2D scanners are more common than 3D’s most people have these in their ordinary lives. How it works:
- The image is converted into an electronic form which can be stored in a computer.
- The computer is equipped with optical character recognition software allow the scanned text from the document to be converted into a TEXT FILE format.
- This means it can be edited in a word processor.
If the original document was a photograph or image, then the scanned image forms an image file such as JPEG.
3D scanners:
3D printers scan real life solid objects and produce a three-dimensional image/ a real life object. Solid objects have x,y and z coordinates, these scanners take images at several points along the three coordinates. The scanned images can be used in a computer aided design (CAD) or more recently sent to a 3D printer to produce a working model of the scanned image.
Application of 3D scanning:
Computed tomographic (CT) scanners are used to create a 3d image of a solid object. This is based on tomography technology which basically builds up an object using slices.
Key words:
- X rays – CT scanners
- Radio frequencies MRI magnetic resonance images
- Gamma rays – SPECT signal photon emission computed tomography.
Quick response (QR) codes
Another type of barcode is the QR code. It’s a machine-readable code consisting of an array of black and white squares, typically used for storing URLs or other information for reading by the camera on a smartphone. Normal bar codes can hold only around 30 digits where the QR code can hold up to 7000 digits.
Image of QR code:
Digital cameras:
Digital cameras have replaced old traditional cameras that used film to record photos. The old traditional cameras was very time consuming as you had to developed the film then printing the picture before you could see the outcome of it. Now digital cameras, with a click of a button the picture is taken and there is no wait time, it appears instantly on your phone, computer, etc. These cameras are controlled by a microprocessor which can automatically carry out the following tasks:
- adjust the shutter speed
- focus the image automatically
- operate the flash automatically
- adjust the aperture size
- adjust the size of the image
- remove the ‘red eye’ when the flash has been used
The photograph is captured when the light passes through the lens onto a light sensitive cell. The cell is made up of tiny elements called pixels. The number of pixels determines the size of the file used to store the picture.
Keyboards
Keyboards is an essential part of a computer, without it you wouldn’t be able to type. Keyboards are used as the input device on computers. tablets, mobile phones, etc. The keyboard is connected to the computer either by a USB connection or wireless. Phones and tablets use touchscreen technology, the keyboard appears on the screen.
Pointing devices
Pointing devices are physical devices that requires the user to ‘click’ on an icon. The mouse is still the most popular pointing device (others are tracker ball or by touchscreen) Mice can be connected to the computer via wireless connection or by a USB connection (same as keyboard) The mouse requires space for it to move around, the mouse is generally supported by a mouse pad because mat surfaces is the easiest for movement instead of something like paper which will prevent the mouse operating correctly.
Microphones
Microphones are used to input sound to a computer. For example:
- doing a voice over in a presentation
- part of a speech recognition system
- part of a voice recognition system
Microphones are either built into the computer or are external devices connected through the USB port or using wireless connectivity. When a microphone picks up sound, a diaphragm vibrates producing an electric signal. This signal goes to a sound card and is converted into digital values and stored in the computer.
Touchscreens
Touchscreens is the future. It is every where from phones to computers. Touchscreens are a form of input device. They allow a simple touch to activate applications or to carry out many of the functions that the pointing devices can do.
Main uses of touchscreen is in mobile phones and tablets. At present there are 3 major types of touchscreen technologies applied to mobile phone screens.
- capacitive
- infra-red
- resistive
Sensors
Sensors are devices which read or measure physical properties . These can include temperature, pressure and so on. Real data is analogue (it’s constantly changing and doesn’t have a discrete value)
DAC and ADC
In the diagram above Vdd is a drain supply.
ADC is an analog to digital converter meaning a device for converting an analog signal (voltage or signals) to a digital code, usually binary. In the real world most of the signals sensed and processed by humans are analog signals.
DAC is a digital to analog converter so, the opposite of what the ADC does. Converting digital codes, normally in binary to analog signals and voltages.
Sensors and there real life everyday use:
- Temperature – Controls a central heating system. Controls/monitors chemical processes and an example of a real life scenario to when you would use it is in a thermometer. When someone is ill you could use the thermometer to take their temperature.
- Moisture/Humidity – These substances can be use in real life scenarios by monitoring the moisture levels in soil in a greenhouse, this more common in places where it’s cold (Europe, USA)
- Light – Lights are some of the most common used sensors in our everyday life. Lights has come so far in terms of technology. One example is: light automatically switching on when at night time and off during the day. There are many more examples but this is one of the most popular ones.
- Infra-red/motion – One of its most important and most common uses of this sensor is detecting intruders using burglar alarms. Infra-red sensors are able to detect what is going on by wavelengths.
- Acoustic/Sound – Used for picking up noise levels in a burglar alarm system.
Robots:
- What is meant by robotics? Give a definition.
An Independent device which capable of doing jobs, human cannot, reducing human error
- What can a robot do / do we need it to do?
The robot must be able to control actuators, to move how we want it to. The robot must be able to sense what it is doing, where it is and avoid any harmful obstacles. We want it to be able to interact with things that we want. Robot must need to be independent, making decisions based on its sensors and apply this to its actuators so the robot can act.
- What are the different types?
- Robots in space: Rovers, Space Stations
- Wheeled Robots, Legged Robots
- Autonomous Underwater Vehicle, Unmanned Aerial Vehicle
- Key component: what is a sensor? Give examples.
- Takes readings from physical environment and turns it into an electrical message/signal.
- Temperature – controls central heating system.
- Light – Light automatically turning on when it’s dark and off when it’s day time.
- Sound – Picking up sound/noise levels.
- What are the advantages of robotics?
Less human error, the same job can be done over and over again and be done quick, the job can be done very efficiently without wasting time.
- What are the disadvantages and limitations?
Robots cant think, any question/command which you have asked, and it’s not programmed, it will not respond. Robots can be very expensive. Robots can replace workers, which then leads to unemployment.
- Find a recent example (or an older and very interesting one!) online of the use of robotics in education, hospitals or industry. Add the details onto the next slide with images / links. You can present these to each other.
A very important and common futuristic robot are medical robots is a robot used in the medical sciences. They are used right now in the real world but doctors are preparing for more of an advanced and consistent use of them as they believe that “robots are the future” They include, but are not limited to, surgical robots. These are in most telemanipulators, which use the surgeon’s actions on one side to control the “effector” on the other side.
- Now Do some research on what the future holds.
Robots will be much used in the military, machines can replace humans and go to war, help people, etc. They can be loaded with guns, ammo, medical kits and extra batteries.
Also drones will be widely used, a drone can fly over a person when needed help and can give emergency supplies and tell the person what to do.
- What would you like to see? A paragraph please.
I would honestly like to see actual hoverboards. I wouldn’t mind if robots take over human jobs but we would have to get paid for doing nothing but these circumstances are very unlikely so I would prefer it if humans were still the dominant species as I’ve seen in many films what robots could do and I don’t want robots to take over the world. I would also like to see more consistent and fast deliveries for food and that would be an easy program for robots. I also would like an artistic robot as I would like it to draw a painting or create a big sculpture in the form of myself.
Here is a video about Input, Output devices and sensors, ENJOY!!
Loudspeakers:
A loudspeaker is an electroacoustic transducer which converts an electrical audio signal into a corresponding sound. The most widely used type of speaker right now is the dynamic speaker. The dynamic speaker operates on the same basic principle as a dynamic microphone, but in reverse, to produce sound from an electrical signal.
Speakers are typically housed in a speaker enclosure or speaker cabinet which is often a rectangular or square box made of wood or sometimes plastic. The enclosure’s materials and design play an important role in the quality of the sound.
Larger loudspeaker systems are used for music, sound reinforcement in theatres and concerts, and in public address systems.
Projector:
The most common type of projector used today is called a video projector. .A video projector takes a video signal and projects the corresponding image on a screen using the lens but some newer types of projectors can project the image directly, by using lasers. A virtual retinal display, or retinal projector, is a projector that projects an image directly on the retina instead of using an external projection screen, a bit like our eye. All video projectors use a very bright light to project the image, and most modern ones can correct any curves, blurriness, and other inconsistencies through manual settings, this is important as this was not possible in the olden days. Video projectors are widely used for conference room presentations, classrooms and cinemas.
Monitor:
A computer monitor is an electronic device that shows pictures for computers. Monitors often look similar to televisions. The main difference between a monitor and a television is that a monitor does not have a television tuner to change channels. Monitors often have higher display resolution than televisions. A high display resolution makes it easier to see smaller letters and fine graphics.
There are three types of computer displays:
- The CRT monitor. These are big and heavy and use a lot of desk space and electricity. It is the oldest technology used by monitors and is based on the cathode ray tube technology that was developed for television. Monitors are made with better parts which give a higher display resolution and picture sharpness than a television. This type of monitor is no longer popular.
- LCD Flat panel. Much thinner and lighter than monitors with a cathode ray tube.. The LCD monitor, the most common kind of flat panel display. It is a newer technology than CRT. LCD monitors use much less desk space, are lightweight and use less electricity than CRT. They have been used for many years in the screens of laptop and notebook computers. They also work as touch screens in tablet computers, mobile phones, and other handheld technologies.
- An LED Monitor (short for Light Emitting Diode) or LED display is an LCD Monitor that uses light emitting diodes for back lighting. The first LCD Monitors used cold cathode fluorescent lamps instead of LEDs to illuminate the screen.
IGCSE Computer Science 