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Input devices of Computer

Computer Input Devices : The input device is the hardware device that connects to the computer system. The user can give the instructions to the computer with the help of these input devices. Input devices can convert the data or instruction into the machine-readable form and sent it to the processor for further processing.

Here we have discussed some essential input devices which are given below:

  1. Keyboard
  2. Point and draw devices (Mouse)
  3. Joystick
  4. Trackball
  5. Light pen
  6. Data scanning devices (image scanner)
  7. OCR (optical character reader)
  8. OMR (optical mark reader)
  9. MICR (Magnetic Ink Character Recognition)
  10. Bar code reader
  11. Card reader
  12. Touch screen
  13. Digitizers
  14. Voice recognition device
  15. Microphone

1. Keyboard

The keyboard is the typewriter-style device which can use the alphanumeric keys or buttons for the input given by the user to the computer system. There are various types of keyboard available nowadays, which are designed with the focus on the specific features according to the user's need.

Figure: keyboard and its keys.
Figure: keyboard and its keys.

The keyboard includes different types of sections such as control keys, function keys, LED indicators, wrist pad, arrow keys, and keypad. Mostly the keyboards are similar to each other, but maybe one or more sections are missing. The Smartphone and tablet keyboard do not come with the physical existence of the keyboard.

Multimedia keys

The multimedia keys allow the user to have control on the computer keyboard. These keys have some special functions such as play, pause, stop, rewind, fast forward, skip, track, eject, shuffle, and repeat.

2. Point and draw device (mouse)

The computer mouse is the input device with standard features. Today we are using various types of the mouse such as a cordless or wireless mouse, optical and laser mouse, etc. The mouse is the handheld pointing device that can detect two-dimensional motions related to the surface.

This motion is translated into the movement of a pointer on display. The first mouse controlling computer system was developed in 1968. Generally, the mouse used the ball rolling on the surface to detect motion, but the modern mouse has optical sensors that have no moving parts.

Figure: Diagram of the computer mouse or draw device.

The computer mouse has one or more buttons to execute the operations such as the selection of the menu item on display. Some system allows the user to use two or more computer mouse at once as the input devices.

3. Joystick

The joystick is a pointing input device with the stick that pivots on the base and reports its angle or direction to the device. The movement of the rod controls the cursor or pointer on the screen. The C.B. Mirick developed the first joystick at the U.S. Naval research laboratory.

There are various types of joystick exist, such as displacement joysticks, finger-operated joysticks, hand-operated, isometric joystick, etc. The joystick is also known as the control column, which is the primary control device in many civilian and military aircraft. It is used to control the machines such as cranes, trucks, underwater unmanned vehicles, etc.

block diagram of the joystick
Fig: block diagram of the joystick.

The joysticks are also used to control the video games and have one or more push-buttons whose state can read by the computer. The main advantage of the joystick is that it provides fast interactions, which are needed in the game applications.

4. Trackball

The trackball is a pointing device which consists of the ball in the middle held by socket with sensors to detect the rotation of the ball. The trackball is the computer cursor control device. The trackball is similar to upside-down mouse with the ball that sticks out. The user can roll the ball by the thumb, fingers, or the palm to move the cursor. The trackball currently made by only three major companies: Logitech, A4Tech, and Kensington. It has the same capability as click buttons on the mouse. The trackball does not require much space. The trackballs are physically more extensive as compared to the computer mouse.

picture of the trackball
Fig: picture of the trackball

The trackball allowed continuous and fast scrolling and did not require repositioning. It needs less work surface to perform the function. These are a little more expensive. The selection of trackball is not as broad as other input devices. Trackball requires minimal cleaning as compared to other input devices. The precision control is more in the case of trackball.

5. Light Pen

The light pen is the computer input device which is used in conjunction with the computer's cathode ray tube display. It allows the user to point the displayed objects or draw on the screen with the greater positional accuracy. The first light pen was developed around 1955 as part of the Whirlwind project at MIT.

The light pen detects changes in brightness of neighboring screen pixels. The CRT scans the whole screen one pixel at a time. The computer can keep track of the familiar time of scanning at different locations on the screen via beam and the pen's position from the latest timestamp. The light pens were common on the graphic terminals during the 1960s.

The light pen is used to select or modify the text or data on the CRT monitor screen. This device was used in the early form of manipulating and highlighted data on the screen. Some graphic cards are also included the connection for the light pen. It can be used as the stroke input device. The light pen is mainly used to manipulate and highlight the data or information.

Light pen
Fig: the picture of the Light Pen and its parts.

The light pen consists of the photocell and an optical system placed in the small tube. When the tip of the light pen is move over the monitor screen, and the user presses the pen button, then the photocell sensing element detects the screen location and sends the corresponding signals to the CPU.

6. Data Scanning Device (Image Scanner)

The Image Scanner is the digital input device which is used to scan the images, printed text, objects and then convert them into digital form. The Image Scanners are used in various domestic and industrial applications like design, reverse engineering, gaming, and testing.

Image Scanner
Fig: Image Scanner

The image scanner was developed in 1957 by the team of Russell kirsch at the U.S. National Bureau. When the document is placed inside the data scanning device, then the image scanned first.

Block diagram of Scanner
Fig: Block diagram of Scanner

Scanners can read red-green-blue color from the color array. The depth of these colors measured based on array characteristics. The image resolution measured in pixels per inch. 

7. OCR (Optical Character Reader)

The optical character reader or optical character recognition is the mechanical or electronic conversion of images, handwritten or printed text into machine-encoded text. The OCR is widely used in the form of information entry from printed paper data records to the digital file. The optical character reader is the research field in pattern recognition, artificial intelligence, and computer vision. It is used in different areas such as invoices, bank statements, digital receipts, business cards, mail, print outs of static data. The technique used in optical character recognition is the standard method of digitizing printed text. We can electronically edit, search, store more compactly, display online, and use in machine processes such as cognitive computing, machine translation, text to speech, key data, and text mining.

optical character recognition
Fig:  optical character recognition.

The early versions of optical character reader needed to be trained with the images of each character. Those old versions of OCR can work only on one font at a time. Now, the advanced OCR systems are capable of producing a high degree of recognition accuracy for every type of font.

Optical character recognition
Fig:  The Optical character recognition.

These advanced systems support the variety of digital image file format inputs. The OCR systems can produce formatted output that output contains approximates the original page include the image, columns and other non-textual components.

8. Optical Mark Reader (OMR)

The optical mark reader or optical mark recognition can capture the human marked data from any document forms such as surveys and tests. There are various traditional optical mark reader devices which can work with the scanner device that shines a beam of light onto the form paper.

Optical Mark Reader
Fig: The Optical Mark Reader.

The OMR can handle hundreds or thousands of physical documents per hour, and the accuracy of Optical Mark Reader is up to 99%. It is mostly used in offices, academics and research departments where a large number of hand-filled documents or forms must be processed.

9. MICR (Magnetic Ink Character Recognition)

The Magnetic Ink character recognition code is known as MICR code in short. This input device is used in the character recognition technology. It can encode the characters which are mentioned at the bottom of cheques and other vouchers.

The Magnetic Ink character recognition allows the user to scan and read the information directly from the data collection of the device. There are two types of major fonts used in the MICR: E-13B and CMC-7.

Magnetic Ink Character Recognition
Fig: The Magnetic Ink Character Recognition.

The font E-13B has the 14 character set which can contain ten decimal digits. The font CMC-7 has the 15 character set, which can include ten digits and five control characters. The CMC-7 has the barcode format, with every character having two different large gaps at different places.

These two unique fonts are used to help the computers in recognition of the characters and the limit check related to the frauds so that this device can help to prevent financial fraud. The Magnetic Ink Character Recognition is mainly used for the banking industries.

The CMC-7 font is used in many European countries, and the E-13B font has been adopted as the international standard in ISO. The MICR reader head reads the characters; this device is similar to the playback head of the tape recorder. This input device is the primary tool for cheque sorting and utilizes the check distribution network at multiple stages. The use of Magnetic Ink Character recognition is to verify the legitimacy or originality of paper documents.

working process of Magnetic Ink Character Recognition.
Fig: The working process of Magnetic Ink Character Recognition.

10. Bar Code Reader

The Bar Code Reader is the optical Scanner which can read the printed barcodes and decode the data contained in the Bar code and send that data to the computer.

Bar Code Reader
Fig: The Barcode reader.

These bar code readers consist of the light source, the lens, and light sensors for the translation. Every barcode reader contains decoder circuitry which can analyze the barcodes image data that the sensors provide data and send to the Scanner's output port.

The Barcode Reader
Fig: The Barcode Reader.

The barcode reader can be differentiating by many technologies which are given below:

Pen -type readers: This type of barcode readers consist of light source and photodiode that are placed next to each other. The photodiode is used to measure the intensity of the light reflected from the light source.

Laser Scanners: The Laser scanner works the similar way as the pen type bar code readers except that the laser scanner uses the laser beam as the light source in this device.

The light emitted by the reader is varied in brightness with the data pattern. The photodiode can receive circuitry, design to detect only signals with similar modulated patterns in both bar code readers.

Camera-based readers: The two-dimensional imaging scanners are the latest type of bar code readers. They can use the camera and image processing techniques to decode any bar code.

11. Card reader

The card reader is the type of data input device that can read the data from the card. It is the hardware device which is used to deliver data to the computer.

The Card Reader
Fig: The Card Reader.

This input device provides complete security, and it looks like a small calculator. The card reader is mainly used in the sales process to read the payment data, which is stored in the credit or debit card.

In a basic sense, the card reader is used to access contents of the memory card in the given format and passes that content on to another device. Most card readers accept multiple memory card formats.

 Smart card reader.
Fig: the Smart card reader.

The card reader is the device used to communicate with the smart card or memory card. The magnetic card reader is the device used to read magnetic stripe cards such as credit card, debit card, etc.

12. Touch screen

The touch screen is the input device which is generally layered on the top of any electronic visual display. It can be the computer system display screen; these types of screen are sensitive to the pressure.

When the finger touches the touch screen, it registered the event and sent that event to the controller for further processing. The touch screen may contain photos or words that the user can touch to interact with the device. It has two advantage, which is given below:

1. The touch screen of any computer or phone allows the user to communicate directly with that display rather than indirectly with a pointer controlled by the mouse or touchpad.

2. Touch screen does not require the use of an intermediate device.

The Touch Screen.
Fig: The Touch Screen.

The touch screens are common in different devices such as gaming devices, personal computers, electronic voting machines, and point of sale systems.

13. Digitizers

The Digitizers are those types of devices which receive analog information or data and create the digital representation of that data; this process is known as the digitization. For example, the digital camera is the digitizer.

Block Diagram of the digitizer
Fig: Block Diagram of the digitizer.

The dual digitizer provides features of both active and capacitive digitizers. The digitizers are mostly used in computer-aided design software. The analog input signal related to the digitizer may be A.C. or D.C. coupled and terminated in 50W.

14. Voice recognition device

The voice recognition is the hardware device with the capability to decode the human voice. It is mainly used to operate any device, perform any command without having to use the keyboard, mouse, or press any button.

Both the speech and voice recognition work on the principle of translates the "analog" spoken words into the "digital" signals so that the machine can understand the voice. For the work of voice recognition device with the computer, you must have a sound card either the Microphone or the headset. Other devices, such as smartphones already have all the necessary hardware built into the device.

components of the voice recognition device
Fig: components of the voice recognition device

The voice recognition device can evaluate the voice biometrics of an individual, such as the frequency and the flow of their voice. Auto speech recognition is also an example of voice recognition. There are various types of voice recognition systems which are given below:

  1. Speaker dependent system.
  2. Speaker independent system.
  3. Discrete Speech recognition.
  4. Continuous Speech recognition.
  5. Natural language.

15. Microphone

The Microphone is generally known as the mic or mike, and it is the input device. The Microphone can convert the sound into electrical signals. These microphones are used in many applications such as telephones, public address systems for the concerts in hall, live and recorded audio, sound recording, megaphones, radio, and television broadcasting.

Fig: The Microphone.

The dynamic microphones are the most common input device which uses the coil of wire suspended in the magnetic field. The Microphone is an example of a transducer, which is the device that changes the information from one form to another.