scanners and plotters

1. Presentation on- “Scanners and plotters” BY- HEENA ABBASI AND BHAWNA GARG BCA SECTION - D

2. CONTENTS--- Introduction to scanners . Types of scanners – Flatbed scanner. Hand-held scanner. Optical mark reader. Limitation of image scanners. Introduction to plotters. Types of plotters- Drum plotter. Flatbed plotter.

3. SCANNERS ---

4. Introduction to Scanners- Scanners are input devices which allow data entry from source document directly.

5. Image Scanner - It is an input device, translates paper document into electronic format, as an input to a computer. Input can be type, text, pictures, even handwritten material also. Useful for preserving paper documents, a document stored in computer does not deteriorate in quality with age. It can be printed or displayed whenever required. We can also alter and manipulate the stored images.

6. Characteristics of scanners - Eliminate manual entry of data , thus improves data accuracy. Automatic entry of data with their use improves data accuracy , increase timeliness of information processed. Demand high quality source document , rejects-poorly typed documents or strikeover documents or documents having erasures. Form design and ink specification is more critical with the use of these devices as compare to keyboard for data entry.

7. FLATBED SCANNER- HAND-HELD SCANNER- It is like a copier machine. Consist of a box having a glass plate on its top, lid that covers a glass plate. Activated glass plate moves horizontally from one end to another. After scanning one line, light beam moves up a little to scan other line , process continues till the scanning finishes. Takes 20 seconds to scan a document of 21*28 cm in size. They are costly as compare to hand-held scanner. User can hold them in hand conveniently. It has a case of light emitting diodes incased in a small case. For scanning, user drags it slowly from one end to other of a document when its light is on. User must drag it slowly and smoothly for the correct conversion of document to its equivalent bit map. User use them when they have less number of documents. They are cheaper than flatbed scanner.

8. LIMITATION OF IMAGE SCANNERS- If a document stored in the computer as an image instead of text , than it is not possible to do any word processing. Storage space required for storing the document as an image is much more than that required for storing a text document.

9. Optical mark reader(OMR)- It is a scanner , which recognize pre-specified type of mark made by pencil or pen. The technique used by OMR devices for recognition of marks on document involves–: Focusing a light beam on the document and detecting the reflected light pattern from the marks.

10. PLOTTERS ---

11. Plotters --- A plotter is an ideal output device for architects, city planners, engineers' and others who need to generate high precision, hard copy, graphic output of varying size.

12. Drum plotter --- It consist of a drum, 1 or more penholders mounted perpendicular to the drum’s surface. Drum rotates both clockwise and anti-clockwise to produce vertical motion. The pens move right to left and left to right to produce horizontal motion. Graph plotting software controls the movement of drum and pens. User can produce multi colored designs by mounting pens having ink in different colors in different folders.

13. Flatbed scanner --- Consist of a rectangular flatbed table, 1 or more penholder mounted perpendicular to the table’s surface. A graph plotting software is also there. Plots design on paper sheet spread and fix over the table. Paper doesn’t move and pen holder provide all necessary motion to draw designs. Plot size restricted by the area some are as small as A4 size and some are very large to make designs of bed , ships , aircraft etc. Some plotters also etch on plastic and metal plates , for that the pen has a sharp-edged needle.

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