Computers in the real world Objectives Understand the terms input and output Look at different types of input devices – Sensors / actuators – Human interface.

Computers in the real worldObjectives

• Understand the terms input and output• Look at different types of input devices– Sensors / actuators– Human interface devices– Accessibility devices

Computers in the real worldA computer system

Input OutputProcess

Storage

Computers in the real worldA computer system

Input OutputProcess

Storage

Computers in the real worldA computer system – How it works

A keyboard supplies input to the computer by the user hitting various keys.

The software deals with those key strokes and adds them to a word file.

The text will then be displayed (output) on the monitor so the user gets a visual feedback of what keys they have pressed.

The document can also be saved / loaded from the hard drive for editing later.

Computers in the real worldInput – Supplies new information!

Input devices supply new information to a computer system. This can range from keyboards to digital cameras. Any device which can capture new information for a computer system is referred to as a input device.

Computers in the real worldSo is a memory stick or CD input?

Memory sticks, hard drives or CD’s are NOT input devices. They are actually secondary storage devices which will be covered in a later lesson.

Although they do supply new information to a computer (in some ways!) their primary function is to store data. This is why they are referred to as storage devices. You always consider a devices PRIMARY function!

Computers in the real worldInput – Supplies new information!

Output devices deliver information to the user through one of the users senses. This could be sound, sight or even touch! Force feedback (or rumble on a joypad) is a classic example of touch output! Mobile phones can vibrate which is another example of touch feedback.

Computers in the real worldHCI!

The first set of devices we will consider are human computer interfaces or HCI. These devices allow input and output directly to and from a human.

There are TOO MANY devices to list them all out. There are also many different variations of each one. In this power point you will only see a small number of them. One of your tasks will be to find more!

Computers in the real worldInput – Touch screens

Touch screens are becoming very much the defacto standard interface for mobile phones and self service devices. It converts user touch into a mouse click on the screen. It as if your finger is a mouse cursor!

Computers in the real worldHow it works

Underneath the glass/plastic is a transparent film which generates a signal when touched. When touched the touch screen can work out where the touch has occurred. It uses a grid system to work out the co-ordinates of the “tap”.

These co-ordinates are then sent to the software which can then decide what to do with the click.

Some devices can detect more than one touch at once. These are known as multi-touch devices.

Computers in the real worldGestures

Touch screens have some intuitive methods to interact with software. Things like “pinching” to make something's smaller or dragging your finger right to go onto the next image. These are known as gestures.

Multi-touch devices allow the user to stretch, rotate and shrink with intuitive motions. These gestures are now common place but when they were first used they were revolutionary!

Computers in the real worldAccelerometers

Accelerometers are used to detect orientation. These sensors reside inside the Wii controller, mobile phones and anything which detects orientation.

Devices which can detect orientation are now very popular. The Wii controller is a classic example of this. It can detect if it is held upright or tilted at any angle. The change in orientation can then be translated into actions such as swinging a tennis racquet or driving a car.

Computers in the real worldGraphics tablets and hand writing recognition

Not strictly a input device but hand writing recognition is a bolt on for most graphics tablets. Software will attempt to read your hand writing and convert it into text.

Graphics tablets allow you to write directly onto a computer. This is mainly used for drawing or photo touch up. They can detect when the pen is close (which moves the cursor) and also the pressure of the pen (to allow the user to create some interesting artistic effects)

Computers in the real worldPrinters

Laser printers work by shooting a laser onto a magnetic drum. This then attracts powder known as toner which is then transferred to paper. The paper is heated on the way out which fixes the toner to the page. Now you know why the paper is always so hot when it comes out of laser printer! Laser printers are fast and mainly used in offices or schools.

Printers are common output devices and ones which we should be familiar with. There are two main types which are in common use. These are inkjet and laser. Inkjet printers spray ink directly onto the page. They tend to be cheap and high quality. However they are slow.

Computers in the real worldSensors and actuators

Sensors and actuators are used in automated ICT systems such as automatic doors, factory production lines and robots.

Sensors will detect environmental conditions such as temperature, proximity or humidity. This will then be fed into a computer system which then will control a robot or device.

Physical movement is controlled by actuators. A robots arm will be made of a number of actuators which are controlled by the computer system. Automated doors, for example, will have a actuator which would open or close the door.

Computers in the real worldDifferent sensors

Light sensor – Detects the amount of ambient light and generates an electric signal. The more light the greater the signal.

Sound sensor – Detects the amount of ambient sound and generates an electric signal. The more light the greater the signal.

Pressure sensor – Detects force applied. The greater the force applied the larger the signal.

Motion sensor – Detects motion using infrared. Disturbances or movement will generate a signal. Cameras also have this capability but they can not work without light (unless it is a night camera!)

Humidity / water sensor – Detects the amount of water or moisture on the sensor. Water acts as a conductor and reduces the electrical resistance which in turn is detected as moisture.

Computers in the real worldDifferent sensors

Accelerometer sensor – Detects orientation. Uses mercury tilt switches.

Proximity sensor – Detects if objects are close to the sensor by shooting an infrared beam or a laser out and measuring how quickly it returns.

Computers in the real worldActuators

Actuator – Controls the movement of the robotic arm.

Actuator – This is a output device which will cause physical movement. This is associated with automated processes. Robots will use actuators to control the movement of the arms. A conveyor belt on a shop till will use an actuator to make the belt move / stop. A automatic door will have a actuator to open / close the door.

Computers in the real worldAccessibility devices

Computers allow new opportunities for people with disabilities to enable them to have careers and socialize. However every disabled person has a unique set of needs and can not be generalized. For example a blind user would have very different needs to a person who had lost the use of their arms.

Combinations of hardware and software have been created in order to support disabled users in order to get the best out of the computer. The next few slides will explore some disabilities and the solutions found.

Computers in the real worldCerebral palsy

Difficulties they face – Cerebral palsy can cause stiffness or weak muscle control. This means that using a mouse is very difficult for them. It can also cause unwanted movements which makes fine control very difficult.

ICT solutions – Tracker ball / Switch adapted mouse. Tracker balls stay stationary making it easier for the user to control the cursor. Also the switch on the side can be operated as a “left click” enabling collaboration between a carer and the disabled user if they are unable to use the tracker ball. The tracker ball could also be replaced with a joystick.

Computers in the real worldBlind ICT users

Difficulties they face – They can not respond to visual feedback on the screen. This means that using any form of pointing device is out of the equation. Also as they can not see anything on screen they must rely on auditory feedback to control the computer.

ICT solutions – A combination of speakers/headphones and special software known as a narrator.

Computers in the real worldDarren

Computers in the real world

ICT solutions – Head mouse / eye trackers. This will either allow the user to “point” on the screen with their heads or they will use their eyes to point with a blink as a “mouse click”. Multiple cameras will be trained on the users eyes in order to track their movements.

Computers in the real worldDemonstration of eye tracking

Computers in the real worldActivity

Find a input (or output!) device which will enable disabled users to communicate with a computer which has not been talked about already.

Then say what type of disability it is designed for, what difficulties they have accessing ICT and finally how the device solves their problems.

Then make notes on all of the devices described in this PowerPoint and add them to your own revision work.