Laser printer

A laser beam projects an image of the page to be printed onto an electrically charged rotating drum coated with selenium. Photoconductivity removes charge from the areas exposed to light. Dry ink (toner) particles are then electrostatically picked up by the drum's charged areas. The drum then prints the image onto paper by direct contact and heat, which fuses the ink to the paper.Laser printers have many significant advantages over other types of printers. Unlike impact printers, laser printer speed can vary widely, and depends on many factors, including the graphic intensity of the job being processed. The fastest models can print over 200 monochrome pages per minute (12,000 pages per hour). The fastest color laser printers can print over 100 pages per minute (6000 pages per hour). Very high-speed laser printers are used for mass mailings of personalized documents, such as credit card or utility bills, and are competing with lithography in some commercial applications.The cost of this technology depends on a combination of factors, including the cost of paper, toner, and infrequent drum replacement, as well as the replacement of other consumables such as the fuser assembly and transfer assembly. Often printers with soft plastic drums can have a very high cost of ownership that does not become apparent until the drum requires replacement.A duplexing printer (one that prints on both sides of the paper) can halve paper costs and reduce filing volumes. Formerly only available on high-end printers, duplexers are now common on mid-range office printers, though not all printers can accommodate a duplexing unit. Duplexing can also give a slower page-printing speed, because of the longer paper path.In comparison with the laser printer, most inkjet printers and dot-matrix printers simply take an incoming stream of data and directly imprint it in a slow lurching process that may include pauses as the printer waits for more data. A laser printer is unable to work this way because such a large amount of data needs to output to the printing device in a rapid, continuous process. The printer cannot stop the mechanism precisely enough to wait until more data arrives, without creating a visible gap or misalignment of the dots on the printed page.Instead the image data is built up and stored in a large bank of memory capable of representing every dot on the page. The requirement to store all dots in memory before printing has traditionally limited laser printers to small fixed paper sizes such as letter or A4. Most laser printers are unable to print continuous banners spanning a sheet of paper two meters long, because there is not enough memory available in the printer to store such a large image before printing begins.

Screen Printing technique

A screen is made of a piece of porous, finely woven fabric called mesh stretched over a frame of aluminum or wood. Originally human hair then silk was woven into screen mesh; currently most mesh is made of man-made materials such as steel, nylon, and polyester. Areas of the screen are blocked off with a non-permeable material to form a stencil, which is a negative of the image to be printed; that is, the open spaces are where the ink will appear.The screen is placed atop a substrate such as paper or fabric. Ink is placed on top of the screen, and a fill bar (also known as a floodbar) is used to fill the mesh openings with ink. The operator begins with the fill bar at the rear of the screen and behind a reservoir of ink. The operator lifts the screen to prevent contact with the substrate and then using a slight amount of downward force pulls the fill bar to the front of the screen. This effectively fills the mesh openings with ink and moves the ink reservoir to the front of the screen. The operator then uses a squeegee (rubber blade) to move the mesh down to the substrate and pushes the squeegee to the rear of the screen. The ink that is in the mesh opening is pumped or squeezed by capillary action to the substrate in a controlled and prescribed amount, i.e. the wet ink deposit is proportional to the thickness of the mesh and or stencil. As the squeegee moves toward the rear of the screen the tension of the mesh pulls the mesh up away from the substrate (called snap-off) leaving the ink upon the substrate surface.There are three common types of screenprinting presses. The 'flat-bed', 'cylinder', and the most widely used type, the 'rotary'Textile items printed with multi-colour designs often a wet on wet technique or colors dried while on the press, while graphic items are allowed to dry between colours that are then printed with another screen and often in a different color after the product is re-aligned on the press.The screen can be re-used after cleaning. However if the design is no longer needed, then the screen can be "reclaimed", that is cleared of all emulsion and used again. The reclaiming process involves removing the ink from the screen then spraying on stencil remover to remove all emulsion. Stencil removers come in the form of liquids, gels, or powders. The powdered types have to be mixed with water before use, and so can be considered to belong to the liquid category. After applying the stencil remover the emulsion must be washed out using a pressure washer.Most screens are ready for recoating at this stage, but sometimes screens will have to undergo a further step in the reclaiming process called dehazing. This additional step removes haze or "ghost images" left behind in the screen once the emulsion has been removed. Ghost images tend to faintly outline the open areas of previous stencils, hence the name. They are the result of ink residue trapped in the mesh, often in the knuckles of the mesh, those points where threads overlap.While the public thinks of garments in conjunction with screenprinting, the technique is used on tens of thousands of items, decals, clock and watch faces, balloons and many more products. The technique has even been adapted for more advanced uses, such as laying down conductors and resistors in multi-layer circuits using thin ceramic layers as the substrate.

Chain (train) printer

Chain (train) printer

Chain printers (also known as train printers) placed the type on moving bars (a horizontally-moving chain). As with the drum printer, as the correct character passed by each column, a hammer was fired from behind the paper. Compared to drum printers, chain printers had the advantage that the type chain could usually be changed by the operator. By selecting chains that had a smaller character set (for example, just numbers and a few punctuation marks), the printer could print much faster than if the chain contained the entire upper- and lower-case alphabet, numbers, and all special symbols. This was because, with many more instances of the numbers appearing in the chain, the time spent waiting for the correct character to "pass by" was greatly reduced. Common letters and symbols would appear more often on the chain, according to the frequency analysis of the likely input. It was also possible to play primitive tunes on these printers by timing the nonsense of the printout to the sequence on the chain, a rather primitive piano. IBM was probably the best-known chain printer manufacturer and the IBM 1403 is probably the most famous example of a chain printer.

Band printer

Band printers are a variation of chain printers, where a thin steel band is used instead of a chain, with the characters embossed on the band. Again, a selection of different bands were generally available with a different mix of characters so a character set best matched to the characters commonly printed could be chosen. Dataproducts was a well known manufacturer of band printers, with their B300, B600, and B1000 range, the model number representing the lines per minute rate of the printer. (The B300 was effectively a B600 with only half the number of hammers—one per two character positions. The hammer bank moved back and forth one character position, requiring two goes to print all characters on each line.)

Bar printer

Bar printers were similar to chain printers but were slower and less expensive. Rather than a chain moving continuously in one direction, the characters were on fingers mounted on a bar that moved left-to-right and then right-to-left in front of the paper. An example was the IBM 1443.In all three designs, timing of the hammers (the so called "flight time") was critical, and was adjustable as part of the servicing of the printer. For drum printers, incorrect timing of the hammer resulted in printed lines that wandered vertically, albeit with characters correctly aligned horizontally in their columns. For train and bar printers, incorrect timing of the hammers resulted in characters shifting horizontally, albeit on vertically-level printed lines.Most drum, chain, and bar printers were capable of printing up to 132 columns, but a few designs could only print 80 columns and some other designs as many as 160 columns.

Types of Digital Printing machines

Digital printing is a term that includes many different equipment for different products and different levels of quality and expectations.
We start first term digital printing: Definition digital printing takes an electronic file directly from the archive to create the final output will not be to plates or any other kind of intermediary step or certificate. You or black.
The black is usually in the low Copiers end machines such as Xerox Docutech or Kodak Digimaster. The machine is capable at 100 copies per minute. Although the machines use toner but is unable higher resolution than copiers. Despite the fact that higher quality than DocuTech Copiers & digimaster opponent is still up for the quality of the actual presses offset.
The cause of the engine changed and became so popular is the ability to make low volumes at reasonable cost. These limited number of substrates and products that customers use their machines for.The development making this same thing in color is a natural evolution. The higher the quality the better to change the offset the low volume end of the spectrum.
Also, the number of digital color printing machine improved the quality of the customer considered acceptable for the increasing number of products and tools. Color Copiers come first, and use of graphite in four basic colors of CMYK to reproduce color photographs and illustrations. The quality is low end for color and is susceptible to scratches and abrasion over wet ink. Then there is the classification of digital presses. There are two types of toner and liquid ink presses.
All machines have their strengths and weaknesses of color as any other type of manufacturing process. Toner machinery iGen3 and Nexpress. The quality is much better than color copiers, but still have the appearance of toner on them and sometimes do not print screenes smooth. The only real compensation is either Heidelberg or Ryobi machine. That does make a temporary registration to produce print jobs to the press at the time.
It is true offset but has some limitations for the huge% of the machine is small format and not ink carrying capacity of larger presses do. The machine also can not print variable data printing where images or text may change from leaf to leaf. The other machine is the wet ink HP Indigo family. The Indigo 3050 can print variable data, while rivaling offset quality.

Quality of Digital Printing

Toner based machines how they still pay the toner particles. Nexpress iGen3 to do and a very good job, but still seems the blood line of many dye jobs. These 2 machines are very consistent color print results. Liquid ink is the ability of DI (Direct Imaging), offset printing machines, Indigo Digital Press family. DI options Heidelberg and Ryobi DI machines. These machines are not variable data and the limited capacity of the ink in more questions than ghosting and nuances of the problems look. They also depend more on individual skill press to print consistency. DI can not print spot colors and use temporary plates for the production of each job. Indigo 3050 Digital Press is a liquid ink technology and competitors in the quality of the offset. It can not print variable data and true spot PMS colors, and is very consistent with the result of force. All in all, if you get my vote as the best machine HP 3050 Digital Press as to the availability of variable information printing and quality rival replaced. It is very consistent results, and may be registered in the spot PMS colors, or better than the mark with matching color. It is not that the color copy of the sex of the view and print the screens and solids in the near offset look.

Printing Special Effects

There are a variety of treatments, which are printed on special procedures. There are many printing companies do this at home, and many of these procedures has been sent to the scenic highway specialize in "end of work". The stamping Foil, embossing, combination stamping, and Slots are the most frequently discussed. Foil stamping can be either a flat foil stamp or seal of the combination, where the image has risen above or below the surface of the leaf. Foil stamping is the process by which the foil substrate is transferred (on paper), through heat and pressure. Pressure applied through dies to transfer the image to plate letterpress usual. The disk is also heated to release the package to the substrate.

Dies are made of metal and are the most common metals: brass, copper and magnesium. Combination stamp dies truly remarkable picture of the package when dealing with the dead have the opposite image. The paper is then pressed the two heat transfer foil and emboss the image at the same time. Combination stamp dies are more expensive, but doing it is just the difference between the fixed costs of employment and seal combination. Relief is basically very similar to the process of foil stamping, there are only a transfer of aluminum foil. Either increase the level of image (paste) or cut (etched) from the original level surface of the paper. Blind is a relief when the picture was made is in the ink. If you crash, and you must subscribe to the ink color, called the register underneath. Which is the second death and dying are still able to emboss the book between. This pressure will help flatten the paper fibers to create the image.

Thermal image of reality can be improved by helping the smooth surface of iron paper. Die-cutting is a process where the steel rule die is used to cut paper to the desired shape of his death. This is how it is produced Pocket folders and other components in order. It is usually printed on a square or rectangular sheets and then die-cut to create a desired shape. Then the track is scrapped Die sheet or press or by hand. Nicks of die to prevent a piece from the same type of Slots. Pocket folders, brochures, direct mail, postcards, brochures, all the parts that can be diecut in specific shapes. Kiss Cutting diecutting is the process of die cuts in the first layer of material, but no more than aid.

The most commonly used material through the removal of the sign easy to support. Diecuts may be of any shape or size. Kiss cutting is usually a float plane Kluge or Heidelberg windmill. It normally causes a steel die. The pressure is regulated in only the first cut into the surface, but not the primary material.

Digital image processing

Digital image processing is the use of computer algorithms to perform image processing on digital images. As a subfield of digital signal processing, digital image processing has many advantages over analog image processing; it allows a much wider range of algorithms to be applied to the input data, and can avoid problems such as the build-up of noise and signal distortion during processing.

Digital printing

Digital printing is the reproduction of digital images on a physical surface. It is generally used for short print runs, and for the customization of print media.

The process differs from lithography, flexography, gravure, and letterpress printing in several ways:• Every print can be different, because printing plates are not required, as in traditional methods.

• There is less wasted chemical and paper, because there is no need to bring the image "up to colour" and check for registration and position.

• The ink or toner does not permeate the substrate, as does conventional ink, but forms a thin layer on the surface and may in some systems be additionally adhered to the substrate by using a fuser fluid with heat process (toner) or UV curing process (ink).

Because there is less initial setup, it is useful for rapid prototyping, and cost effective for small print runs.Digital Printing is used for personalized printing, or variable data printing (VDP or VI), for example personalized children's books, which are customized with the specific child's name and images. Print on Demand (POD) systems also use digital printing, for short run books of varying page quantities, and binding techniques. Digital prints can also be done on photographic paper, exposed with RGB laser lights from computer files, and processed in photographic developers and fixers. These prints are continuous tone images, and have the dyes imbedded in emulsion layers within plastic coatings. They can be very archival.

Offset printing

Offset printing is a commonly used printing technique where the inked image is transferred (or "offset") from a plate to a rubber blanket, then to the printing surface. When used in combination with the lithographic process, which is based on the repulsion of oil and water, the offset technique employs a flat (planographic) image carrier on which the image to be printed obtains ink from ink rollers, while the non-printing area attracts a water-based film (called "fountain solution"), keeping the non-printing areas ink-free.

Advantages

Advantages of offset printing compared to other printing methods include:• Consistent high image quality. Offset printing produces sharp and clean images and type more easily than letterpress printing because the rubber blanket conforms to the texture of the printing surface. • Quick and easy production of printing plates.

• Longer printing plate life than on direct litho presses because there is no direct contact between the plate and the printing surface. Properly developed plates running in conjunction with optimized inks and fountain solution may exceed run lengths of a million impressions.

• Cost. Offset printing is the cheapest method to produce high quality printing in commercial printing quantities.

Disadvantages

Disadvantages of offset printing compared to other printing methods include:• Slightly inferior image quality compared to rotogravure or photogravure printing.

• Propensity for anodized aluminum printing plates to become sensitive (due to chemical oxidation) and print in non-image/background areas when developed plates are not cared for properly.

• Time and cost associated with producing plates and printing press setup. As a result, very small quantity printing jobs are now moving to digital offset machines.

Printer

The printer is an output device that provides the user with the output in an acceptable form (Ref: - by Prof. Ramananda Chivite) In computers, a printer is a device that produces a hard copy (permanent human-readable text and / or graphics) of documents stored in electronic form, usually on physical print media such as paper or transparencies. Many printers are mainly used as local devices, and related printer cable or, in most newer printers, a USB cable to a computer that acts as a source document. Some printers, commonly known as network printers that have network interfaces (typically wireless or Ethernet), and can serve as a printed device for each user on the network. Personal printers are often designed to support local and network connected users simultaneously. Furthermore, some modern printers can directly interface to electronic media such as memory sticks or memory cards, or cameras, including digital cameras, scanners, printers are around, along with a scanner and / or a fax into a single unit, and can function as copiers. Printers that include non-printing features are sometimes called Multifunction Printers (MFP), multifunctional devices (MFD), or All-In-One (AIO). Most MFPs include printing, scanning and copying of their characteristics. A virtual printer is a piece of software user interface and API which resemble that of a printer driver, but that is unrelated to a physical printer to the computer. Printers are designed for low volume, short run print jobs require almost a year of establishment to obtain a paper copy of a document. However, printers are generally considered slow devices (30 pages per minute fast, cheap printers, and many consumers are much slower than that), and the cost per page is actually relatively high. However, this is offset by the ease of on-demand and management of project costs are more controllable than a solution to out-source. The type of course is the engine of choice for high-volume, professional publishing. However, as printers have improved in quality and performance, many jobs are done by professional printers have become by users on local printers; See desktop publishing. First computer printer in the world was the 19th century mechanically driven apparatus invented by Charles Babbage on the Difference Engine.

History of Computer Printers

Printers In 1953, the first high-speed printer was developed by Remington-Rand for use of the Univac computer.

In 1938, Chester Carlson invented a dry printing process called electrophotography commonly called "Xerox Technology Foundation for laser printers to come.
The original laser printer called EARS was developed at the Xerox Palo Alto Research Center began in 1969 and completed in November 1971. Xerox Engineer, Gary Starkweather adapted Xerox copier technology adding a laser to come with a laser printer. According to Xerox, "The Xerox 9700 Electronic Printing System, the first xerographic laser printer product, was launched in 1977. The 9700, a direct descendant of the original Parc" ears "that launched the laser printer scanning optics, character generation electronics and formatting software, was the first product on the market to be activated by a research park. "
According to IBM, "the first IBM 3800 was installed in the headquarters data center in North America accounting of FW Woolworth's in Milwaukee, Wisconsin in 1976." The printing system IBM 3800 was up first in the industry, the speed of laser printer. A laser printer that operates at a speed of over 100 pages per minute. E 'was the first printer to combine laser technology and electrophotography according to IBM.
In 1992, Hewlett-Packard released the popular LaserJet 4, the first 600 by 600 dots per inch resolution laser printer.
In 1976, the inkjet printer was invented, but it took until 1988 for the inkjet to become a commodity in the house with Hewlett-Parkard launch of inkjet printer Deskjet, with a price the whopping $ 1000.