INPUT DEVICES-part 2-Data scanning,Digitizer,Electronic cards,Voice recognition devices



Part 2- Data scanning devices,Voice recognition devices,Vision based devices,Data scanning devices,Digitizer &Electronic cards based devices

An input device is an electromechanical device, which data from the outside world, and translates them into a form, which the computer can interpret. Several input devices are available today. They are-

1. Keyboard devices

2. Point-and draw devices

3. Data scanning devices.

4. Digitizer

5. Electronic cards based devices

6. Voice recognition devices

7. Vision-based devices

The various types of input devices along with their typical applications are described (Data scanning, Digitizer,) below.

 2.3. Data Scanning Devices

             Data scanning devices are input devices, which are used for direct data entry into the computer system from source documents. Some of the data scanning devices are also capable of recognizing marks or characters. Data scanning devices typically have the following characteristics:

         They eliminate some of the duplication of human effort required to get data into the computer Human beings do not have to manually enter the data.

The reduction in human intervention improves data accuracy, and can increase the timeliness of the information processed.

Since scanners are direct data entry devices, they demand high quality of input documents. Documents that are poorly typed or have strike overs or erasures are normally rejected.

With these devices, form design and ink specification may become more critical than is the case when people key in the data from the forms.

 Data scanning devices are of many types. Some of the commonly used Data scanning devices are described below

 2.3.1. Image Scanner

 An image scanner is an input device, which translates paper documents into an electronic format, which can be stored in a computer. The input documents may be typed text, pictures, graphics, or even handwritten material, this input device has been found to be very useful in preserving paper documents in electronic form. The copy of a document stored in a computer in this manner will never deteriorate in quality or become yellow with are and can be displayed or printed, whenever desired. If the computer in which the scanned document is stored as the right kind of software (called image-processing software), the stored images can be altered and manipulated in interesting ways.

Image scanners come in various shapes and sizes. The two commonly used type’s are-

Flatbed scanner:

As shown in Figure 2.3.1(a), a flatbed scanner is like a machine, which consists of a box having a glass plate on its top and a lid that covers the glass plate. The document to be scanned is placed upside down on the glass plate. The light source is situated below the glass plate, moves horizontally from left to right when activated. After scanning one line the light beam moves up a little, and scans the next line the process is repeated for all the lines. It takes about 20 seconds to scan a document of size 21 cm. 28 cm.

Hand-held scanner:

As shown in Figure 2.3.1(b), a hand- held scanner has a set of light emitting diodes encased in a small case, which can be conveniently held in hand during operation. To scan a document, the scanner is slowly dragged from one end of the document to its other end, with its light on. The scanner has to be dragged very steadily and carefully over the document; otherwise the conversion of the document, into its equivalent bit map will not be correct. Due to this reason, hand-held scanners are used only in cases where high accuracy is not needed. They are also used when the volume of documents to be scanned is low. They are also much cheaper as compared to flatbed scanners.

 2.3.2 Optical Character Recognition (OCR) Device

When image scanners are used for inputting text (typed or handwritten), they have the following two limitations:

Since the input document is stored as an image, instead of text, it is not possible to do any word processing of document (the computer cannot interpret the stored document as letters, numbers and special characters).

The storage required for storing the document as an image is much more than required for storing the same document as a text. For example, a page of printed text, having 2000 characters, can be stored as 2000 bytes by using the ASCII representation. A bit map image (BMP) representation of the same document will require 10 to 15 times more storage, depending on the resolution (granularity) of points.

 The OCR technology is used to overcome these limitations. In this case, the scanner is equipped with a character recognition software (called OCR software), which converts the bit map image (BMP) as well as pdf images of characters to equivalent ASCII codes. That is scanner first creates the bit map image (BMP) of the document, and then the OCR software translates the array of gird points into ASCII text, which the computer can interpret as letters, numbers and special characters.

 OCR software is extremely complex, because it is difficult to make a computer recognize an unlimited number of typefaces and fonts. Hence, this software is designed to recognize texts, which are written using standard type fonts are (called OCR fonts). Two such standard fonts are OCR-A (American standard) and OCR-B (European standard) Figure 2.3.2 (a) shows OCR-A fonts. Note that, if the document contains italics or bold face letters, or fonts other than that for which the OCR software will not work effectively.

 2.3.3 Optical Mark Reader (OMR)

       These scanners are capable of recognizing a pre- specified type of mark made by pencil or pen. For example, many students might have appeared in objective type tests, in which they hand to mark their answers to questions on a special pre-printed test scoring sheet by darkening a small square, circular, or oval shaped box by a pencil, to indicate their correct choice out of the various given options (see Figure 2.3.3). These answer sheets are directly fed to a computer for grading with the use of an optical mark reader. The actual technique used by an OMR device for recognition of marks involves focusing a light on the page being scanned, and detecting the reflected light pattern from the marks. Pencil marks made with a soft lead pencil (high graphite content) reflect the light, enabling the reader to determine which responses are marked.

 2.3.4 Bar-Code Reader

       Bar codes are data coded in the form of small lines (Known as bar codes represent alphanumeric data by a combination of adjacent vertical lines (bars) by varying their width and the spacing between them. They are particularly used for unique identification of all types of foods, books, postal packages, badges, tags etc.

 A bar-code reader is a device, which is used for reading (decoding) bar-coded data, It may be a hand-held scanner, or may be embedded in a stationary scanner. It scans a bar-code image, and converts it into an alphanumeric value had typed on a keyboard.

 A bar-code reader uses a laser-beam scanning technology. The laser beam is stroked across the pattern of bars of a bar code. Different bar codes, having different patterns of bars, reflect the beam in different ways, which is sensed by a light-sensitive detector. Reflected light patterns are converted into electrical pulses, and then transmitted to recognition logic circuits, which convert it into an alphanumeric value.

       Just there are a variety of internal bit encoding systems, they arte a variety of bar-coding systems. The most widely known bar-coding system is the Universal Product Code (UPC), which now appears on almost all retail Packages in USA. The UPC, originally used for supermarket items, is now being on other consumer goods also. The UPC bar-code patterns are decoded as 10 digits. The first 5 of these digits identify the manufacturer or supplier of the product, and the next 5 digits identify a specific product of the manufacturer (see Figure 2.3.4).

       Bar code readers are commonly found in supermarkets and department stores. When a customer picks up a product for purchasing, and brings it to the cash counter for payment, the sales person at the counter uses a bar-code reader to scan the bar code printed on the product. The bar-code reader converts the bar code into an alphanumeric value and feeds it to the computer, which looks up the price of the product, possibly updates inventory and sales records, and uses the price and description information to prepare a purchase bill for the customer. Postal delivery services also use bar codes to identify and track each packet. For example, Federal Express of USA uses a unique bar-coding system, and their employees can usually tell a customer, within a matter of minutes, the current location of any packet.

2.3.5 Magnetic-Ink Character Recognition (MICR)

       MICR is similar to OCR, and is used by the banking industry for faster processing of the large volume of cheques being handled every day by this industry. Banks, which employ MICR technology, use a special type of cheque. The bank’s identification code (name, branch, etc), account number, and the cheque number are pre-printed (encoded) by using characters from a special character ser on all these cheques with a special character ser on all these cheques with a special ink, which contains magnetizable particles of iron oxide, before the cheques are given to the customers for A sample cheque which employs MICR technology, is shown in Figure 2.3.5. When a customer presents a filled in cheque at a bank employee manually enters (keys in) the amount written on the cheque, in the lower right corner of the cheque by using an MICR inscriber, which prints the amount with the magnetic ink. The data of the transaction is automatically recorded for all cheques processed that day. This cheque is then processed by using an MICR reader-sorter, which can recognize magnetic ink characters. The MICR reader- sorter reads the data on the cheques, and sorts the cheques for distribution to other banks, or for further processing.

 The most commonly used character set by MICR devices is known as E13B font, which consists of the numerals 0 to 9, and four special characters, as shown in Figure 2.3.5. Coded data in the form of these fonts are transferred from cheques to the computer by an MICR reader-sorter. As the cheques enter the reading unit, they pass through a magnetic field, which causes the particles in the ink to become magnetized, Read heads then interpret these characters by examining their shapes. The sorter is used to sort cheques into different pockets, according to their identification code numbers.

       MICR technology speeds up data input for the banking industry, because cheques can be directly fed into the input the input device, and automatically processed thereafter. Besides enabling faster processing of cheques, this technology also ensures accuracy of data entry, because most of the information is preprinted on the cheque, and is directly fed to the computer. However, MICR has not been adopted by other industries, because the currently supported character set has only 14 symbols (10 digits and 4 special characters). No alphabetic characters are available.

 2.4 Digitizer

       Digitizer is an input device which is used for converting (digitizing) pictures, maps and drawings into digital form for storage in computers. For example, the       x and y coordinates of points in a drawing may be stored in digital form. This enables recreation of the drawing from the stored information, and easy incorporation of changes in the drawing when required.

 As shown in Figure 9.14, a digitizer consists of a digitizing tablet (also known as graphics tablet) associated with a stylus. The digitizing tablet is a flat surface, which contains hundreds of fine copper wires forming a grid. Each a copper wire receives electric pulses. The digitizing tablet can be spread over a working table, and is connected to a computer. The stylus is like a pen, or a lens-like cursor with a cross hair and button. The stylus is connected to the tablet, and can be pressed down at a point on the tablet to input the (x, y) coordinates of the point. When the stylus moves on the tablet, the cursor on the computer screen moves simultaneously to corresponding position on the screen according to provide visual feedback to the operator. This enables the operator to draw sketches directly, or to input sketched drawings very easily. Inputting drawings or developing sketches by using a digitizer is further simplified by the fact that poorly sketched lines, arcs and other graphical objects are automatically input as mathematically precise objects, like straight lines and smooth curves.

       Digitizers are commonly used in the area of computer Aided Design (CAD) by architects and engineers to design cars, buildings, medical devices, robots, mechanical parts, etc. They are also used in the area of geographical information system (GIS) for digitizing of maps, which are available in paper form.

 2.5 Electronic-card Reader

             Electronic cards and their associated readers offer another moans of direct data entry into a computer system. Electronic cards are small plastic cards having encoded data, which are appropriate for the application for which they are used. An electronic card reader, which is normally connected to a computer, is used to read the data encoded on an electronic card, and transfer it to the computer for further processing.

            Electronic cards are often used by banks, and issued to the customers for use in automatic teller machines (ATMs). An ATM allows a customer to deposit or withdraw cash 24 hours a day, without the need to interact with a bank employee. It is an unattended machine, which may be located at any place (either inside the bank or away from the bank). It is normally connected to the bank’s computer. The electronic card for use in an ATM has the customer’s account number and credit limit (maximum amount that that he/ she can withdraw in a day) encoded on the card. An ATM has an electronic card reader associated with it when a customer inserts his/her card into the ATM (actually the electronic-card reader of the ATM). The reader reads the data encoded on the card and transmits it to the bank’s computer, which activates the customer’s account. The customer can then carry out the desired transaction by following the instructions displayed on the screen of the ATM, and by pressing a few keys on the customized keyboard of the ATM.

 2.6 Voice Recognition Devices

             Voice recognition devices are input devices, which allow a person input data to a computer system by speaking to it. Hence, they make computers much easier to use. However, as data input device, currently voice recognition systems have limited success, because correct interpretation by a machine of the large number of words in the vocabulary of a language is difficult. The major difficulty has been that people speak with different accents (pronounce differently) and intonations (with different tone or pitch of the voice), and the fact that the meaning of words can vary depending on the context in which they are used. Hence, today’s voice recognition systems are limited to accepting few words within a relatively small domain, and can be used to enter only limited kinds and quantities of data.

             Although in its infancy, voice recognition systems are already being used for a wide range of applications. Some of its typical applications are as follows:

 Inputting data to a computer system by a person in situations where his/her hands are busy, or his/her eyes must be fixed on a measuring instrument or some other object. Consider, Doctors in an operation room can request certain information about a patient while operating.

For authentication of a user by a computer system based on voice input.

For limited use of computers by individuals with physical disabilities.

             In addition to making input of data easier, voice recognition systems also provide tremendous freedom of movement to the operator, because the operator is free to up and move around, while inputting voice data to the system.

 2. 7 Vision-Input System

Vision- input system allows a computer to accept input just by seeing an object. The input data in this case is normally an object’s shape and features in the form of an image. The idea is to simulate the capability of a human vision system in a limited sense. A computer with a vision-input device consists of a digital camera, and follows the following steps to recognize a given object:

The digital camera is focused on the input object to take a picture of the object.

The digital camera creates an image of the object in digital form (in is and Os), so that it can be stored and interpreted by the computer.

The digitized image of the object is matched against similarly formed pre-stored image in the computer’s image database.

Depending on whether a match is found or not, the system takes the appropriate action.

             Vision- input devices are mainly used today in factories for designing industrial robots, which are used for quality control and assembly processes. For example, a robot used for quality control may inspect objects and separate those, which do not meet certain quality-control specifications. Another robot may used to separate objects of different shapes in different bins.

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