Types of Input Devices

Types of Input Devices

Keyboard

Keyboard is designed to resemble a regular typewriter with a few additional keys. Data is entered into computer by simply pressing keys. All computer keyboards have a typing area that includes the

letters of the alphabet, numbers, punctuation marks, function keys and other basic keys that provide additional functionality. The number of keys on a typical keyboard varies from 82 keys to 108 keys.

Advantages of using keyboards for data input include

 Entering data and instructions with keyboards is generally faster than

with pointing devices.

It is not necessary to buy additional equipment because most computer

systems are normally supplied with keyboards.

Disadvantages of using keyboards for data input include

 It takes a lot of time to practice in order to type quickly and accurately.

 Typing speeds are still very slow when compared with computer

 speeds.

 Pointing Devices :

Mouse                                                                                                      

•       A mouse is the most widely used pointing device with a GUI

environment on personal computers.

•       A pointing device is used to communicate with the computer by pointing to locations on the monitor on the screen.

•       Mouse has two buttons, left one to select the pointed option and right one to display the properties of the pointed option.

•       A mechanical mouse has a rubber ball on its underside to detect movement of the mouse.

•       It is the most common and least expensive pointing device.

•        An optical mouse uses devices that emit and sense light to detect the mouse's movement.

•       These are accurate and do not  need a mouse pad.

•       A cordless mouse (either mechanical or optical) transmits data

•       using wireless technology such as radio waves or infrared light waves.

Advantages of using a mouse include

•        A mouse is user-friendly for computer beginners.

•        A mouse is easy and convenient to use with a graphical user interface.

•        Using a mouse to select items or move to a particular position on the

•       screen is faster than using a keyboard.

Disadvantages of using a mouse include

•       It is not easy and convenient to input text with a mouse.

•       A mouse is not accurate enough for drawings that require high precision.

•        A mouse usually requires a flat surface to operate.

•        A mouse needs more desk space to operate when compared with a trackball.

Trackball

•       A trackball is a stationary pointing device with a ball mechanism

on its top.           

•       This pointing device comes in various shapes and forms but with  the same functions.

•       The three shapes,which are commonly used are a ball,button and square.

•       Like the mouse  a track ball is also used to control cursor movements and the actions on a computer screen.

•       The cursor is activated when the buttons on the device are pressed.

•       Track ball is used by many computer enthusiasts and graphic designers .

•       Trackballs are not supplied normally so an additional cost is always charged.

                                                                                                               

•       Advantages of a trackball include

•        A trackball is good for limited desk space because the user does not

have to move the entire device.

•       Disadvantages of trackball include

•        A trackball is usually not as accurate as a mouse.

•        The ball mechanism of trackballs also requires more frequent cleaning

than a mouse.

Touchpad

•       Is a small pressure- and motion-sensitive area on a portable computer that you can use

to move the mouse pointer.

•       When we move our finger across the pad, the mouse pointer on the screen moves in the same

direction.

•       A touch pad is an alternative to a mouse.

Advantages of a touch pad include

•        Easy and Fast one finger control.

•        Ideal for portable devices

Disadvantages of using a touchpad include

•        Expensive & found in specific devices e.g. laptops

Joystick

•       A joystick is a pointing device with a vertical lever mounted on a base.

•       The lever usually includes buttons called triggers, which activate certain events when pressed.

•       The device that moves in all directions and controls the movement of the cursor.

•       Joysticks are mainly used for computer games and ultrasound scanners in hospitals.

•       Joysticks are mainly used in CAD/CAM systems and flight simulators.

•       A joystick also consists of buttons that can be programmed to indicate certain actions once a particular position on the screen has been selected using a stick.

•       It offers three types of control:  digital,glide,and direct.

•       Digital control allows movement in a limited number of directions such as top,down,left, and right.

•       Glide and direct control  allows movements in all directions(360) degrees.

Advantages of using a joystick include

•        A joystick allows fast interactions required in most games.

Disadvantages of using a joystick include

•        It is difficult to use a joystick to select objects accurately on the screen.

Touch Screen

·         A touch screen is an input/output touch-sensitive display.

·         Touch screens are often used for information kiosks located in

department stores, hotels, airports, and museums.

·         Touch screens are also used for ATM machines to allow easy

access of bank accounts.

Advantages of a touch screen include           

·         No extra peripherals are needed except the monitor.

·         A touch screen allows easy access to commands, which are usually

identified by words or symbols on the screen.

Disadvantages of a touch screen include

·         Touch screens are not suitable for inputting a large amount of data because they require a lot of arm movements.

·         Only items already on the screen can be selected.

Light Pen

• A light pen is a pointing device that can detect the presence of light.
• Light pens are used by health care professionals (such as doctors and dentists) and design work.
• It facilitates drawing images and selects objects on the display screen by directly pointing to the objects.
• Using light pens users can interact more easily with applications such as drag and drop and highlighting.
• Pushing the light pen tip against the screen activities  a switch,which allows the user to make the menu selections,draw,and perform other input functions.

Advantages of light pens include

•  Using a light pen is more direct and precise than using a mouse.
•  Light pen is also convenient for applications with limited desktop space.

Disadvantage of light pens includes

•  Light pens normally require a specially designed monitor to work with.

 Graphics Tablet

·         A graphics tablet is a flat, rectangular, electronic plastic board, on which a

stylus writes or draws.

·         It is mainly used for computer-aided design and drafting by architects, mapmakers, artists, and designers.

·         Each location on the graphics tablet corresponds to a specific location on the screen.

·         A graphics tablet can be used to digitize drawing with great accuracy.

Advantages of graphics tablet include

·         A stylus can be pointed to different positions on the tablet quickly.

Disadvantages of graphics tablet include

·         A stylus and a graphics tablet normally have to work together, and

      cannot work separately.

Digital Camera

Digital camera stores images digitally rather than recording them on a film. Once a picture has been taken, it can be transferred to a computer system and then manipulated with an image editing software and printed. 

The big advantage of digital cameras is that making photos is both inexpensive and fast because there is no film processing.

Scanners

A scanner is an input device that converts a document into an electronic format that can be stored on the disk. The electronic image can be edited, manipulated, combined, and printed by using the image editing software. The scanners are also called optical scanners as they use a light beam to scan the input data.

They can store images in both gray-scale and color mode.

―   Hand-held Scanner

―   Flat-bed Scanner

  A flatbed scanner works like a copy machine except that it creates a file of the document rather than a paper copy.

•       It consists of a box containing a glass plate on its top and a lid that covers the glass plate.This glass plate is used for placing the document to be scanned.

•       For scanning,an A4 size document takes about 20 seconds.

•       The flat scanners are larger in size and more expensive than the hand-held scanners.

    A handheld scanner can be manually passed over the image to be

scanned. A portable device you can use to copy an image from

paper to your computer. Hand-held scanners are ideal for capturing

small images, such as signatures and logos. A hand-held scanner is

smaller, less expensive, and more portable than a flatbed scanner.

Scanners are mainly used for image processing, which consists of

capturing, storing, analysing, displaying, printing, and manipulating

images. Many scanners also include optical character recognition (OCR)

software, which can convert an image of text into a text file that can be edited.

Advantages of a scanner include

·         A scanner with appropriate OCR software can work as an OCR

system.

 Disadvantages of a scanner include

·         A scanner is best for two-dimensional objects only, difficult to scan 3-D

      objects

·         Scanned images usually take up a lot of storage space.

Optical Character Reader (OCR)

The scanned document is stored as a bitmap in the computer’s memory. If the scanned document contains text and you want to edit it, OCR software is required. The OCR software translates the bitmap image of text to the ASCII codes that the computer can interpret as letters, numbers, and special characters.

Because of OCR data entry  becomes easier,error free and less time consuming.

It is very expensive and if the document is not typed properly,it will become difficult for the OCR to recognize the characters.

Optical Mark Recognition (OMR)

OMR is the process of detecting the presence of intended marked responses. A mark registers significantly less light than the surrounding paper. Optical mark reading is done by a special device known as optical mark reader. OMR readers are often used for marking multiple choice answer sheets, capturing data from questionnaires, enrolment forms, and lottery tickets.

Advantages of OMR readers include

·      OMR has a better recognition rate than OCR because fewer mistakes

    are made by machines to read marks than by reading hand written characters.

·      Large volumes of data can be collected quickly and easily without the

                need for specially trained staff.

·      The cost of inputting data and the chance of data input errors could be

               reduced because it is not necessary to type the details for data entry.

Disadvantages of OMR readers include

·      The OMR reader needs to be reprogrammed for each new document design.

        OMR readers are relatively slow.

·         The person putting marks on the documents must follow the

            instructions precisely.

·         Any folding or dirt on a form may prevent the form from being read

           correctly.

Handwriting Recognition

·         Handwriting recognition is a technique which allows

a computer system to recognize characters and

other symbols written by hand in natural handwriting.

·         The technology is used for identification

and also on devices such as PDA and tablet PCs. After one writes on a

screen with a stylus, the computer turns that person’s handwriting into digital

text.

      Advantages of handwriting recognition include:

·   Handwriting recognition works regardless of which language text is

    written in i.e. it is language Independent.

·  It requires a minimal or no training to use.

·  It has very minimal system requirements and provides immediate input.

     Disadvantages of handwriting recognition include:

•       Cannot recognize mathematical symbols

•       Only understand linear structures

•       It is very tiring for the arms.

•       Handwriting needs to be clear for it to be recognised.

Magnetic Ink Character Reader (MICR)

•       A magnetic ink character recognition (MICR) reader can read text printed with magnetized ink. It reads the characters by examining their shapes in a matrix form. Magnetic ink character

•       recognition is used most exclusively by the banking industry for processing checks. The characters represent the

•       check number, the bank number, and the account number of customers

Advantages of MICR readers include

•        MICR is difficult to forge.

•        Documents can still be read when folded or written on.

Disadvantages of MICR readers include

•        MICR readers and encoders are very expensive.

•        The system can only accept a few different character sets.

Bar Code Reader

               

Ø  A bar code reader uses laser beams to read bar codes.

Ø  A bar code reader reads a bar code by using light patterns that pass through the bar code lines.

Ø  Bar code readers are widely used in a POS e.g. supermarkets, department stores, libraries, etc.

Ø  The light in the wave form data is converted from analog to digital,in order to be processed by a decoder and then transmitted to the computer software.

Ø  The pen in the bar code unit reads the information stored in the bar code and converted into a series of characters by which the operating system gets the information stored in the bar code.

     Advantages of using bar codes and bar code readers include

Ø  The process of data entry is fast and accurate.

Ø  Bar codes can be printed by normal printing methods.

Ø  No need to write down or key in the name of the item or its actual price.

    Disadvantages of using bar codes and bar code readers include

Ø  A bar code reader may misread a bar code if there is any dirt or mark

on the code.

Ø  Only numbers can be coded.OMR is the process of detecting the presence of intended marked responses. A mark registers significantly less light than the surrounding paper. Optical mark reading is done by a special device known as optical mark reader.

voice recognition

·        The field of computer science that deals with designing computer systems that can recognize spoken words and translate into text.

·        Voice recognition implies only that the computer can take dictation, not that it understands what is being said.

·        A number of voice recognition systems are available on the market. The most powerful can recognize thousands of words. However, they generally require an extended training  session during which the computer system becomes accustomed to a particular voice and accent. where an individual speaker reads sections of text into the SR system. These systems analyze the person's specific voice and use it to fine-tune the recognition of that person's speech, resulting in more accurate transcription. Such systems are said to be speaker dependent.

·        Many systems also require that the speaker speak slowly and distinctly and separate each word with a short pause.

·        These systems are called discrete speech systems.

·        There have been made great strides on continuous speech systems -- voice recognition systems that allow you to speak naturally. There are now several continuous-speech systems available for personal computers.

·        The term voice recognition or speaker identification refers to finding the identity of "who" is speaking, rather than what they are saying. Recognizing the speaker can simplify the task of translating speech in systems that have been trained on a specific person's voice or it can be used to authenticate or verify the identity of a speaker as part of a security process.