Both Input–Output Devices:
•Touch Screen
•Modems
•Network cards
•Pendrive
•Audio Cards / Sound Card
•Headsets (Headset consists of Speakers and Microphone.
•Speaker act Output Device and Microphone act as Input device
•Facsimile (FAX) (It has scanner to scan the document and also have printer to Print the document)
Input Devices
Input devices are any electronic device that are connected to a device and produces input signal.
1. Keyboard 2. Mouse
3. Microphone 4. Touchpad 5. Touchscreen
Output devices
Output is the result of data processing activity when it is presented externally to the system.
The output from a computer can be printed or displayed form
An output device is hardware that is capable of delivering or showing information to one or more users
An output device shows, prints and presents the results of a computer’s work.
Examples
• Monitor
• Printer
• Speaker
• Projector
Storage Devices
• Information and documents are stored in a computer storage so that it can be retrieved whenever they are needed later on.
• Computer storage is the holding of data in an electromagnetic form for access by a computer processor.
• Examples 1. Hard Disk 2. CD ROM
3. Magnetic Disk
Keyboard
The keyboard is the piece of computer hardware used to input text, characters and other commands into a computer or similar device
Keyboard typically contains keys for individual letters, numbers and special characters, as well as keys for specific functions. A keyboard is connected to a computer system using a cable or a wireless connection.
Microsoft and Logitech are the probably the most popular physical keyboard manufacturers, but many other hardware makers also produce them.
Inventor of Keyboard
Christopher Latham Sholes (February 14, 1819 – February 17, 1890) was an American who
invented the QWERTY keyboard, and along
with Samuel W. Soule, Carlos Glidden and John Pratt, has been contended as one of the
inventors of the first typewriter in the United States.
Christopher Latham Sholes.
How keyboard connects to a computer?
Computer keyboard can connect with a computer through a cable or signal (wireless connection). Until recently, a keyboard connects with the standards PS/2 type or serial.
Now this trend is changed and the connection is replaced by USB (Universal serial bus) and wireless connectors. Most modern PCs (motherboards) even don’t have PS/2 connectors, only USB.
Since there is no connection with main pc, wireless keyboard gets power from battery or AC power connection. This is the side effect of wireless keyboards, you often charge battery.
Keyboard
How does a Keyboard Work ?
How does a Keyboard Work ?
The computer keyboard is very simple. You push a key, and it puts a letter on the screen. But how does it work? When you push a key, the metal part connects 2 wires which allows a current to flow to the computer. The computer measures the voltage and transforms the amount of volts in to binary. The computer compiler reads the binary, and a letter appears on a screen. Very simple.
Keyboard Matrix Scanner
•Most keyboards have around 100 keys. The computer system must react to each of them independently.
•But it is not possible to have a separate communication channel for each switch.
•So the switches are arranged in a matrix and connected to a keyboard scanner.
•The matrix usually contains 5 or 6 rows and around 20 columns.
•At the intersection of each row with each column is a key switch which ,when depressed ,makes electrical contact between that row and column.
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Keyboard Matrix Scanner Structure
• Is standard input device
Arrangement of keys
IC
Integrated Circuit
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Operators
• Each button on the keyboard corresponding to a switch connected between a row of A and a column of B, so each key has a row and column addresses only.
• When done press any key, this key will create binary code sent to the operating system then it will change to the ASCII code and display on the screen
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Operators
Key Binary Code ASCII code
A 0001 1110 0100 0001
S 0001 1111 0101 0011
D 0010 0000 0100 0100
F 0010 0001 0100 0110
G 0010 0010 0100 0111
H 0010 0011 0100 1000
Bit Binary ASCII code
Compiler
Character
Keyboard Controller Interface
Types of keySwitches
◼Capacitive switch
◼Hall effect switch
◼Opto electronic switch
◼Membrane switch
◼Mechnical switch
Capacitive switch
◼ Two plates of the capacitor are brought closer when the key is pressed.
◼ Change in capacitance of switch changes and change in capacitance is detected in terms of voltage.
◼ Based on the switch open/close voltage is received this voltage is converted into proper signals to inform CPU.
Capacitive switch
Types of key switch
◼ Hall effect switch:
magnetic field is applied to any device the resistance of device
will be increases or
decreased(current starts flowing)
◼ This allow current flow
Hall effect switch
Types of key switch
◼ Opto-electronic switch: have LED light generate light when electric power is applied.
◼ When key is pressed the light from LED falls onto photo- transistor
◼ Thus the value will be produced at the output Vout
Membrane switch
Membrane switch
• Generally contains three layers of materials such as polyester or polycarbonate film.
• The whole assembly is often less than 1mm thick.
• The bottom layer is fixed, the middle layer is flexible and the top layer which is also flexible.
• The switch contacts are between the inner surfaces of the bottom layer and the middle layer.
• Pressing the top layer causes the middle layer to press against the bottom layer and form an electrical contact.
• When the top layer is released, the contact is broken.
• Membrane switches are inexpensive, thin, inherently sealed and can be waterproof.
• Often used for control switches on peripherals such as printers.
Input Device :keyboard
Mechanical switch
Mechanical switch: it uses two metal pieces or contacts
Question?
Answer
Reference for answer: https://www.xtremegaminerd.com/membrane-vs-mechanical-switches-for-gaming/
Mouse
• A mouse is the most popular electro mechanical, hand held input device.
It is used as a pointer to control the cursor and coordinates. It can be wired or wireless having a small palm size box with a round ball at its
base, which senses the movement of the mouse and sends signals to CPU when the mouse buttons are clicked. The mouse makes it easier to
navigate menus by clicking on them.
• Normally it has two buttons called the left and the right button with a wheel between the buttons. It can perform the following functions.
• Control the position of the cursor Selecting commands Scroll Moving icons Open a program Drag and drop Resizing the window Perform other functions with the help of additional buttons
History of mouse
• Dr. Douglas Engelbart , a professor with the Stanford Research
Institute in Menlo Park, California, developed the first device that came to be known as the mouse in 1964.
• Dr. Engelbart made a small, brick-like mechanism with one button on top and two wheels on the underside.
Overview of Mouse image
Overview of Mechanical Mouse image along introduced a wheel
Mouse
Types:
Mechanical
Optical Mouse Wireless Mouse
Optical Mouse
◼ LED produces a red light that is emitted onto surface the light reflected back to CMOS sensor then to DSP(digital signal processor) for analysis
◼ DSP analysis the signal and patterns and determines mouse movements.
◼ Along with coordinates are received by computer and will show mouse movement on screen.
Optical Mouse
Mechanical mouse vs Optical Mouse
Optical Mouse
Optical mice have several benefits over track-ball mice
• Moving parts have lower chance of failure
• There’s no way for dirt to get inside the mouse and interfere with the tracking sensors
• Increased tracking resolution means a smoother response
• They do not require a special surface, such as a mouse pad.
Wireless Mouse
Most wireless mice use radio frequency (RF) technology to communicate information to your computer
RF devices require two main components- A Transmitter and a Receiver The transmitter is housed in the mouse. It sends an electromagnetic
(radio) signal that encodes the information about the mouse’s movements and the buttons you click.
The receiver, which is connected to computer, accepts the signal decodes it and passes it on to the computers operating system.
The receiver can be a separate device that plugs into computer, a special card that you place in an expansion slot, or a built in component.
Mouse
• Advantages of wireless mouse
• Advantages and disadvantages of using a mouse
• Difference between optical mouse and laser mouse
Microphone
• Microphone is an input device, used to input voice and music into the computer that is then stored in a digital form. The addition of a
microphone facilitates the people to dictate documents to their
computer, record sound, and have long distance conversation. But the voice communication is more complex than information through
keyboard. Two types of microphones are available: Desktop
Microphone and Hand held Microphone. The microphone is used for various functions like:
• Audio for videoComputer gamingOnline chattingAdding sound to a multimedia presentationRecording musical instruments and music mixingRecording voice for dictation and singingVoice recorderVoice recognitionVoice over internet protocol
Microphone
Scanners
Scanner is an input device, which reads hard copy images and converts them into a digital form. Scanner works more like a photocopy machine. It scans documents and transfers them in digital file. It is connected to the computer through USB.
Scanner is used when some data is available on the paper and it is to be
transferred to the hard disk of the computer for further operations. This data can be edited before printing with added OCR software.
There are different types of scanners are available in the
market. For example, Flatbed Scanner, Sheet fed Scanner, handheld Scanner and Card Scanner.
Scanners
Flatbed Scanner
Light Pen
Light pen is a pointing device similar to a pen that utilizes a light sensitive detector to select objects or draw pictures on the display screen. In light pen, there is a
photocell and an optical system placed in a small tube. When the tip of a light pen is moved over the monitor screen and the pen button is pressed, its photocell sensor detects the screen location and sends the signals to the CPU.
Digital Camera
• Digital camera is an input device that takes pictures digitally and stores them as data on memory cards. It has an LCD screen which provides preview of images.
Track ball
• Track ball is an input device that is generally used in notebook or laptop computers instead of a mouse. This is a half inserted ball and by moving your thumb, finger or palm of your hand on the ball, the pointer can be moved.
• Because track ball is static so it does not require much space to use it. It comes in
various shapes like a ball, a button or a square.
Track ball can be placed on any type of surface including your lap.
Trackball
•Internal design is almost identical to a mouse.
•Ball is completely free to rotate within its socket.
•Operated by the palm of the hand.
• Movements sensed by the ball being in contact with two rollers inside the casing in the same manner as a mechanical mouse.
• The roller’s movements again are detected by sensing the rotations of discs attached to their ends.
• This sensing can be achieved by electrical contacts or by LEDs and photodetectors
• Commonly integrated into the casing of most laptop personal computers.
Touchscreen
Touchscreen is a unique type of input device in which users interact with a computer by using their fingers. It is mainly used in laptops, smartphones, tablets and cash registers
Touch Screen
•A touch screen is a display screen which has something attached so that when a finger touches the screen, the X and Y coordinates on
the screen can be detected.
•The screen employs a row of transmitters on one side of the screen
and a corresponding row of receivers on the other side. There are transmitter and receiver along the top and bottom of the screen.
•The transmitters are continuously sending a signal to their receivers.
•When the finger touches the screen , one or more receivers receive the signal and the row-column touched are identified.
• A basic touch screen has three main components: a touch sensor, a controller, and a software driver. The touch screen is an input device, so it needs to be combined with a display and a PC or other device to make a complete touch input system.
1.Touch Sensor
A touch screen sensor is a clear glass panel with a touch responsive surface. The touch sensor/panel is placed over a display screen. There are several different touch sensor technologies on the market today, each using a different method to detect touch input. The sensor generally has an electrical current or signal going through it and touching the screen causes a voltage or signal change. This voltage change is used to determine the location of the touch to the screen.
2.Controller
The controller is a small PC card that connects between the touch sensor and the PC. It takes information from the touch sensor and translates it into information that PC can understand. The controller is usually installed inside the monitor for integrated monitors.
3.Software Driver
The driver is a software update for the PC system that allows the touch screen and computer to work together. It tells the computer's operating system how to interpret the touch event information that is sent from the controller.
Digitizer
Digitizer is an input device which converts analog data into digital form. Digitizer converts the signals from television or camera into numbers and stores them in computer.
They are used to create a picture of whatever the camera had been pointed at and then stores into binary inputs. A graphic tablet is used as digitizer for drawing and image
manipulation.
Optical Character Reader
• OCR is an input device that scans the printed text
optically, converts them into a machine language and
stores in the system memory.
Magnetic Ink Card Reader
• MICR input device is mostly used in banks to process
cheques. The bank’s code
number and cheque number are printed on the cheque with a special magnetic ink that are machine readable.
The main advantage of MICR is that it is fast and accurate.
Biometric Devices
Biometric device is also an input device used to enter
biometric data into a computer by scanning face, hand, finger or voice.
Barcode Scanner/Reader
Barcode reader also known as
Barcode scanner, is an input device. It is used as point of sale scanner and for reading barcoded data which is generally used in labelling goods or numbering the books. It can be
handheld scanner or stationary scanner.
References
https://medium.com/@tryeducationtypes/what-is-an-input-device- types-of-input-devices-a2ac2431637e
