Scanner

A scanner is a device that translates data on a sheet of paper to a form that can be stored on a computer. The basic function of a scanner is to convert a document to a digital format. You can thus convert a hard copy i.e. data on a paper to a soft copy i.e. files on your computer.

Different types of scanners are used for different application.

Flatbed Scanners

This scanners are also known as desktop scanners. Flatbed scanners are the most widely used. A flatbed scanner is similar to a photocopy machine in appearance. A scanner that provides a flat, glass surface to hold a sheet of paper, book or other object for scanning. The scan head is moved under the glass.

 

Sheet-Fed Scanners

A sheet-fed scanner (also referred to as an automatic document scanner or ADF scanner) is a digital imaging system specifically designed for scanning loose sheets of paper, widely used by businesses to scan office documents and less frequently used by archives and libraries to scan books that have been dis-bound or other robust unbound documents.

Handheld Scanner

A scanner that is moved by hand over the material being captured. Handheld scanners are small and less expensive than their desktop counterparts but partially rely on the user's dexterity to move the unit across the paper. Trays are available that keep the scanner moving in a straight line.

 

Drum Scanner

A type of scanner used to capture the highest resolution from an image. Photographs and transparencies are taped, clamped or fitted into a clear cylinder (drum) that is spun at speeds exceeding 1,000 RPM during the scanning operation. A light source that focuses on one pixel is beamed onto the drum and moves down the drum a line at a time.

 

Trouble Shooting Scanners

Problem: Computer does not recognize scanner.

Solution: Check whether the scanner is plugged in and the power switch is on. If your scanner has on/off button, ensure that is turned on.

Try interchanging the power cables connecting the scanner to the power outlet and computer. If the scanner works, then the power cables is faulty and will have to be replaced.

Unplug the scanner and restart the computer.

Check the USB or SCSI port connection of the scanner to see if the interface cable is connected properly and is not loose.

Check whether the correct scanner is selected for use.

Reconnect the interface cable to the computer. Make sure that the interface cable is fit properly and is not too tight. The OS will most probably now recognize the scanner. If the problem is  still same then change the interface cable.

Problem: Scanner does not work.

Solution: Ensure that power is on and the power indicator light must be glowing.

Ensure that the document or image to be scanned is placed face down on the glass.

Try connecting the scanner to another compatible computer to see if it works. If the scanner works fine, then the problem lies with your computer.

Problem: Scans are not clear.

Solution: Use an electric blower to blow away dirt and paper pieces on the glass surface. You must use optical-surface cleaning fluid with an anti-static cleaning cloth. It is also permissible to use a cleaning spray with a soft linen cloth. You must not spray cleaning fluid on the scanner. This could damage th scanner. It is necessary to ensure that the surface is totally dry before scanning any document. 

Computer

Printer

The printer is a device that prints text documents and images on paper means converts a soft copy to a hard copy. It is known as output device.

Printers are classified in two groups:

Impact Printers

It is used to printing document as well as graphics. It refers to a class of printers that work by banging a head or needle against an ink ribbon to make a mark on the paper. The working of impact printer is very similar to that of the typewriter. This includes dot-matrix printers, daisy-wheel printers, and line printers.

Dot Matrix Printer

A type of printer that produces characters and illustrations by striking pins against an ink ribbon to print closely spaced dots in the appropriate shape. Dot-matrix printers are relatively expensive and do not produce high-quality output. However, they can print to multi-page forms (that is, carbon copies), something laser and ink-jet printers cannot do.

Dot-matrix printers vary in two important characteristics:

Speed: Given in characters per second (cps), the speed can vary from about 50 to over 500 cps. Most dot-matrix printers offer different speeds depending on the quality of print desired.

Print quality: Determined by the number of pins (the mechanisms that print the dots), it can vary from 9 to 24. The best dot-matrix printers (24 pins) can produce near letter-quality type, although you can still see a difference if you look closely. It is connected with the parallel (LPT) or serial or USB port of the system. There are two types of DMP (Dot-matrix printers) depending upon size i.e. 80 column and 132 column.

Daisy-wheel Printer

A type of printer that produces letter-quality type and working on the same principle as a ball-head typewriter work. The daisy wheel is a disk made of plastic or metal on which characters stand out in relief along the outer edge. To print a character, the printer rotates the disk until the desired letter is facing the paper. Then a hammer strikes the disk, forcing the character to hit an ink ribbon, leaving an impression of the character on the paper. You can change the daisy wheel to print different fonts.

Daisy-wheel printers cannot print graphics, and in general they are noisy and slow, printing from 10 to about 75 characters per second. As the price of laser and ink-jet printers has declined, and the quality of dot-matrix printers has improved, daisy-wheel printers have become obsolete.

Line Printer

A high-speed printer capable of printing an entire line at one time. A fast line printer can print as many as 3,000 lines per minute. The disadvantages of line printers are that they cannot print graphics, the print quality is low, and they are very noisy.

 

Non-impact Printers

The non-impact printers are characterized by a quiet operation as physical contact is not established between print head, cartridge and media (paper). Inkjet, laser and thermal printers are types of non-impact printers.

Ink-jet Printer

An inkjet printers places extremely minute amounts of electrically charged ink on paper to create images or text. The drops of ink are sprayed through a series of nozzles. These drops are around 0.6 microns in diameter and are positioned with very high precision. Inkjet printers use color as well as monochrome cartridges. It provides high quality printing and cost of printing is also high. It can connect through parallel (LPT) or USB port or wireless to the system. A typical ink-jet printer provides a resolution of 300 dots per inch, although some newer models offer higher resolutions. It is also known as Desk-jet Printer.

 

Laser Printer

A type of printer that utilizes a laser beam to produce an image on a drum. The light of the laser alters the electrical charge on the drum wherever it hits. The drum is then rolled through a reservoir of toner, which is picked up by the charged portions of the drum. Finally, the toner is transferred to the paper through a combination of heat and pressure. This is also the way copy machines work.

There are two other types of page printers that fall under the category of laser printers even though they do not use lasers at all. One uses an array of LEDs to expose the drum, and the other uses LCDs. Once the drum is charged, however, they both operate like a real laser printer. The available resolutions range from 300 dpi at the low end to 1,200 dpi at the high end. By comparison, offset printing usually prints at 1,200 or 2,400 dpi. Some laser printers achieve higher resolutions with special techniques known generally as resolution enhancement. You can add additional fonts in one of two ways:

In addition to text, laser printers are very adept at printing graphics. However, you need significant amounts of memory in the printer to print high-resolution graphics. To print a full-page graphic at 300 dpi, for example, you need at least 1 MB (megabyte) of printer RAM. For a 600-dpi graphic, you need at least 4 MB RAM.

The speed of laser printers ranges from about 4 to 20 pages of text per minute (ppm). A typical rate of 6 ppm is equivalent to about 40 characters per second (cps).

 

Thermal Printer

A thermal printer is a printer that makes use of heat in order to produce the image on paper. Due to quality of print, speed, and technological advances it has become increasingly popular and is mostly used in airline, banking, entertainment, retail, grocery, and healthcare industries. Thermal printing does not make use of ink or toner unlike many other printing forms but largely depends on thermal papers for producing the images. They are also quiet popular in creating labels owing to speed of printing.

 

Advantages of Thermal Printers:

No involvement of cartridges or ribbons and thus organizations can save investment by using thermal printers.

Easier to use as there are less buttons and use of software involved.

Popular in noise-free environments and are great for offices.

Largely inexpensive and come in various models and sizes.

More efficient and faster in printing monochromatic ones compared to other forms of printing.

More durable compared to other printers.

Disadvantages of Thermal Printers:

Unlike standard printers, thermal printers usually do not print out colors well.

If they become too heated to operate, the ink consumed would be more and the printing may not be precise.

Print head could be harmed by the high heat used while printing, often resulting on cost to repair when it break down.

All-in-one Printers

An all-in-one printer is a device made up of multiple peripheral functionalities and capabilities, including printing, copying and scanning. All-in-one printers provide centralized document management for large and small enterprises. Manufacturer’s segment all-in-one printers by page-per-minute (PPM) speed, and cost varies by output quality and usage.

All-in-one printers include one or more of the following features and components:
 

Printing, Copying, Scanning, Faxing, Stapling, Duplexing, Hole punching, Color and/or black and white printer compatibility, Extra paper trays, Photo organization software, Optical character recognition (OCR) software.

USB or parallel port all-in-one printer types are as follows: 

Small Office, Home Office (SOHO): Small units with print, copy, scan and fax functionality, basic finishing (stapling, duplexing, hole punching) and USB connections. 

Office: Mid-sized units that serve as centrally networked office systems with integrated security, full features, document storage, advanced finishing (stapling, hole punching, offset mode), custom software and advanced network scanning, including email, Server Message Block (SMB), Network File System (NFS) and File Transfer Protocol (FTP). 

Production: Large and expensive units with high-quality output and advanced finishing. Serve as centrally located network printers that may not include advanced functionalities and also may be known as print on demand (POD) or digital presses. 

All-in-one printers also have basic input/output (I/O) features:

Input: Built with network drivers for different operating systems, page description languages, parallel connection/printing types, direct interpreters and USBs.

Output: Built with printing speed/technology, paper formats, dot-per-inch (DPI) resolution and duplex and direct printing.

Troubleshooting Dot Matrix Printers

Trouble: Paper is Jammed/Stuck.

Shoot: Try to dislodge the paper with a small object like a paper clip.

Remove the roller of the printer then remove the paper.

Check paper path and clean it.

Use a bulb chamber to heat up the paper before using it.

Trouble: Prints nonsensical/junk characters.

Shoot: Check the printer driver to see if it is proper one for printer.

A loose or faulty printer cable can cause improper printing. Try printing a document after replacing the interface cable.

Try the printer self –test. If the printer fails the self test, then the printer may be faulty.

Check the parallel port setting (e.g. EPP,ECP or SPP) and USB setting from the BIOS.

Trouble: Printer displays flashing lights

Shoot: Flashing lights can indicates one of many problems. Flashing lights as a signal to indicate some internal problem. It could be a paper jam or a damage logic card. Each patterns of flashing lights indicates a different problem to find out the cause of the flashing lights use printer manual.

Troubleshooting Inkjet Printers

Trouble: Printouts from the printer are blank

Shoot: Check if the plastic cover has been removed from the ink cartridge.

There may be air entrapment inside the cartridge. To undo any such fault, cover the cartridge in a tissue and shake it gently.

Try printing with another ink cartridge. This will help to verify a fault in the cartridge and find out if the cartridge is empty.

Trouble: Color printouts are not proper

Shoot: Wear gloves to prevent ink from falling on your hands.

Clean the cartridge with a soft wet tissue or lint free cloth.

Check with another color cartridge.

Try printing. If the printout is still improper, one of the colors must run out in the ink cartridge.

Trouble: Printers does not recognize the cartridge.

Shoot: Verify whether the cover of the cartridge has been removed.

Wipe the ink cartridge carefully with a wet tissue and let it dry.

Clean the print circuitry thoroughly

Check with another working cartridges.

Replace the cartridges if found defective.

Troubleshooting Laser Printers

Trouble: Output from the laser printer is not clear.

Shoot: Turn off the printer and remove any connections.

Open the printer and remove the paper tray.

Remove the toner.

Clean the cavity where toner is placed, with a clean dry cloth. Some laser printers are supplied with a brush. Use the brush if it is provided.

Clean spilled toner ink the interior of the printer.

Replace the toner if the above steps do not work.

Computer