Input Devices
Input Devices:
• Input devices can be described as the peripheral devices that we use to send out signals to the computer system.
• A computer system cannot do the processing without receiving some input from the user.
• Therefore, these devices are used to send raw data for processing to the system.
Types of Input Devices:
• Input devices are of two types:
• Manual Input Device – Devices like keyboard, mouse, and scanner are manual devices that require the user to manually input the data for processing.
• Direct Data Entry Devices (DDE) – Examples include smart cards, optical mark recognition, etc. These devices automatically transfer the data from the source file (e.g. barcode) to the computer system.
Different Input Devices:
• Mouse
• Keyboard
• Concept Keyboard
• 2D & 3D Scanner
• Trackball
• Graphic Tablets
• Touchscreens
• Microphone
• QR Code Reader
• Digital Camera
• Interactive Whiteboard
• Barcode Reader
1. Mouse:
• It can be wireless or wired and allows the user to control the cursor/pointer’s movement on the screen.
• The user can control the cursor coordinates or movement by moving it over a flat surface.
• The mouse has two to three buttons.
• With the mouse, objects can be clicked/moved, folders can be opened by double-clicking or options of a folder/application can be seen by using the right-click button.
• Today, the mouse has become optical i.e. it uses a laser to track the movement however, in the past mouse used to have a small ball inside them for the tracking.
2. Trackball:
• Besides mouse, a trackball is also an input device i.e. used to control the cursor movement on the screen.
• However, the user keeps the trackball at one position and only moves the ball within it for movement control.
• The trackball is best for users with limited hand motor skills and some people prefer it as it gives great control over the movement without demanding a lot of space to use it.
• Mouse and Trackball are also known as pointing devices.
3. Keyboard:
• It can be wireless or wired.
• It is an input device that allows the user to enter commands or data by pressing keys.
• When a user presses a key, an ASCII code is sent to the computer system.
• A keyboard contains over 100 keys that can be divided into four groups/categories:
- Function keys – contains twelve function keys from F1 – F12 that perform special functions.
- Numeric keys – contains numeric digits 0 – 9, arithmetic signs of plus, multiplication, division, subtraction, and a decimal point.
- Cursor keys – contains arrows for left, right, down and up.
- Main Keyboard – contains the alphabets, special characters, etc.
4. Concept Keyboard:
• A concept keyboard is a keyboard that has keys that are programmed to perform special tasks and have visual images on them instead of letters/characters/numbers.
• For example, a restaurant counter representative may have this keyboard with different meal button, etc.
• Today, these keyboards are replaced by virtual concept keyboards or touchscreens.
5. Microphone:
• The microphone is like a transducer i.e. it converts energy from one form to another.
• It is used to take analog sound waves as an input.
• It then converts the sound waves into electrical signals that the computer system can understand.
• There are different types of microphones available, but they all have a diaphragm.
• A diaphragm is a piece of paper, aluminum, etc. that vibrates when a person speaks into the microphone.
• These vibrations are then converted into electrical signals.
6. Digital Camera:
• It is used to capture images/videos by sampling light from by time, spatially and tonally, and store on a memory card.
- Spatially – sampling the angle of view into a rectangular grid of pixels.
- Tonally – sampling the varying tones of brightness.
- Time sampling – exposure of a given duration.
• Unlike the traditional camera, a digital camera uses an image sensor made of silicon that is sensitive to light.
• Digital cameras also contain a display screen with options to change settings.
• The display screen also allows the user to view the captured image/video.
7. 2D Scanners:
• 2D scanners are input devices that help in converting 2D documents as well as images in a digital format.
• 2D scanners can be either handheld or flatbed.
• Some printers come with a built-in flatbed scanner with them.
• To boost the overall functionality of scanners, users can use it with software like OCR or OMR.
• e.g. OCR converts documents into a computer-readable format.
8. 3D Scanners:
• An input device like a 2D scanner but can scan 3D models.
• To achieve this type of scanning radio waves, lasers, x-rays or light can be used.
• It is used majorly for security checking, it can also be found in biometric devices, etc.
• However, continuous exposure to rays like x-ray or laser can be harmful.
9. Interactive Whiteboard:
• Just like the traditional whiteboard, interactive whiteboards also widely used for explanations or presentations in schools and offices.
• It is consists of a big touch screen (touch-sensitive screen) that allows the images from the computer system to the interactive board.
• The board also allows to interact with the programs directly by using the dummy pen or finger.
• The dummy pen or finger can also be used to write or mark on the board while explaining or during a presentation.
10. Touchscreens:
• Touchscreens are input devices that are available in three types i.e. resistive, capacitive and infrared.
- In capacitive touchscreens, an electric current is sent from all corners of the screen and touch location is detected by the change in electrical current.
- In resistive touchscreens, there are multiple layers and touch is detected when the top layer touches the lower layer and electrical current changes.
- In infrared touchscreen, there are LED beams that form a grid (invisible) on the screen and the exact location of the touch is detected when the beam breaks because of the touch.
• It is a screen i.e. touch-sensitive and responds to it as well as it offers an electronic display to the user.
• Using the touchscreen, the user can interact with the software by simply touching the screen via a finder or dummy pen.
11. Barcode Reader:
• It is an input device that can read an image made of white and black lines.
• These lines represent digits from 0 to 9.
• The barcode reader is able to read the exact digits because the white and black surfaces reflect the light in a different way.
• With a barcode reader, it is quick and easier to scan the series of codes as you do not need to type these codes by hand.
• The bar code reader also helps in reducing the error as compared to manual entry.
• A barcode reader only helps in the identification of the item/product in order to know details about that specific product, the user must refer to the database with all the details.
12. QR Code Reader:
• A QR Code reader is capable of scanning the QR code i.e. a pattern generated by a computer that can hold a modest amount of information e.g. website address, contact details, product details, etc.
• A user can access and read the information in the QR code by scanning it via the QR code reader.
• A QR code reader consists of three parts including illuminator, decoder, and convertor (sensor).
• The scanner illuminates the QR code with red light and the sensor then detects the illuminated light which is decoded by the decoder and information is sent to the computer system.
• Mobile applications are also available on the PlayStore and AppStore that allows the user to scan the QR code.
• In the case of the mobile, the information is sent to the mobile device.
Input Devices in Real-Life Scenarios
Passport Scanning at Airport:
• At airports, 2D scanners are used to scan the passports.
• The OCR technology is used to produce the digital images of passport pages.
• These digital images can then be manipulated in various ways.
• For example, The data from the passport’s digital images can be extracted and copied in the database at the correct fields.
• The text can also be stored in ASCII format, it all depends on how you want your data to be manipulated.
• At some airports, the image in the passport is also scanned and stored as a JPEG file.
• The passenger’s photograph (taken from the digital camera) is then matched with the scanned image for verification using face detection software.
Barcode Readers in Supermarkets:
• The Barcode at supermarkets is a life savior as it not only speeds up the processing of at the cash counter but it also minimizes the error.
• The customer gathers up the items to purchase in a shopping cart and walks up to the cashier, the cashier will scan the barcode on items using the barcode reader and he will get all the information regarding the item from the database on his screen.
• The cashier keeps scanning the items and once he scans all the items he can see the total cost of the items in the shopping cart.
• The receipt is generated automatically and the cashier can collect the payment in the cash drawer.
• The receipt usually contains information of all the purchased items e.g. their name, quantity, and cost as well as the total amount given and the amount that the cashier gave back to the customer.
• Each transaction is recorded under the cashier’s account in the database.
• Managers can review the cashier’s transaction by simply connecting to the database.
SENSORS
Temperature Sensor:
• The temperature sensor can detect the temperature changes by measuring the heat generated by a system/object.
Application:
• Control and monitoring of a chemical process.
• Monitoring and control of temperature in a greenhouse.
• Controlling a central heating system.
Moisture/Humidity Sensor:
• Humidity sensors measure the moisture in the air while moisture sensors detect the amount of moisture in a material.
Application:
• Monitoring moisture level in industries.
• Monitoring and controlling humidity levels in greenhouses.
Light Sensor:
• The light sensors can detect the ambiance of the surrounding.
• The ambiance refers to the level of brightness/darkness.
Application:
• Controlling street lights.
• Automatically turning on vehicle headlights etc.
Infrared/Motion Sensor:
• The infrared/motion sensors can detect the movement or heat produced from an object.
Application:
• Burglar alarm system
• Automatic doors etc.
Pressure Sensor:
• These sensors detect the pressure.
• There are a number of pressure sensors including resistive pressure sensors, piezoelectric pressure sensors, and strain gauge type.
Application:
• Weight machine
• Burglar system etc.
Acoustic/Sound Sensor:
• It detects the noise levels in the surrounding.
Application:
• Burglar system
• Leakage detection system etc.
pH Sensor:
• It detects the type of material i.e. acidic or alkaline.
Application:
• Greenhouse
• River monitoring for contamination etc.
Magnetic Field Sensor:
• It can detect the changes in the magnetic field.
Application:
• Mobile phones
• Car detection in traffic lights etc.