Band Printers - Index

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Band Printers - Summary

Origins -

The principle of drum and band printers is very old - drum printers were common in old manual cash registers. Drums and bands are still seen in some small POS and ticketing printers.

Types -

In the Computer industry commercial and Industrial printers with 132, 136 and even 200 character positions on pages 14 inches and more wide. Usually rated by speed in lines per minute - 600, 1200, 2000, and 3000 lpm. Dot-band printers are a variant.
 
 
Merits
 
  • Fast printing
  • Low cost printing
  • Robust print mechanism with a very long life.
  • Ink exhaustion degrades but does not stop printing
    		• Problems
     
  • Complex mechanical assembly - when it goes wrong it needs specialist attention
  • Can give good print wihen new - in field conditions old machines often give crude print
  • Big and noisy.

    • Printing Method

    Characters on a print -band are hit against an ink bearing ribbon transfering the outline on the paper.

    General Concept of Impact Printers
    Typewriters, Teletypes, Daisywheel and GolfBall. Impact printer - metal typefaces press ink out of a ribbon onto the page

    Market Position - large volume printing at low cost or "transactional printing": batch printing of invoices, delivery notes, purchase orders, statements.
    Print speeds beyond 20 pages per minute. Bandprinters. Expensive Machines - But Low Copy Price with Large Volume

    Limitations - Pages are ugly. Left standing by fast laser printers like the IBM 4100 at 1,440 pages per minute Tractor fed stationery, Ugly print, No graphics

    Advantages - no cheaper method of print. Long service life of 10 years or more. No cheaper method to communicate business messages on paper

    Models:
    DEC / HP LP37. Fujitsu M3043. Dataproducts FP IBM 6252 Wescode 2000BP.Some models still avialable

    Outline Mechanism. Outline of the bandprinter mechanism
    Platen- Usually just a steel bar, although rubber rollers are possible. Platen - usually just a plished steel bar giving something for hammer, ribbon and paper to strike
    Hammer - plain metal hammer activated by a solenoid, usually via levers. Hammer Mechanisms - usually solenoid activated - difficulty is packing at 2.5mm intervals
    Hammer Shuttle - one possibility to reduce numbers is oscillating shuttle hammerbank. Hammer positions can be cut by using a shuttle mechanism - rare now
    Hammer storage - not usually oiled so prone to rust - keep very dry. Hammer banks aren't oiled - so they rust badly when not in use
    Print Band - Usually 96 characters repeated about 4 times on a band about a metre long. Print Band - flexible steel band carrying the character set
    Statistical Bands - Character set organised so most frequent characters eadily available. Statistical Bands make frequently used characters more readily available
    Ribbon - Polyester fabric soaked in a gel ink, typical life is many thousand pages. Statistical Bands make frequently used characters more readily available
    Spooled Ribbon - Simple spools are highly reliable and often low cost. Spools provide ribbon transport cheaply and simply
    Cartridge Ribbon - Less messy but usually proprietary so more expensive. Cartridges may be easier to use than spools - but tend to be more expensive
    Ribbon Shield - Strip of mylar that prevents the ribbon rubbing against the page. Ribbon shield - sheet of plastic that prevents the ribbon rubbing on the paper unnecesarily

    Outline Operation - when character on band matches position on paper hammer fires.Outline Operation - When character position on band matches that wanted on the page hammer fires
    Electronic Operation - line stored and matched against known characters on band.Electronics - shift register or microprocessor loop.
    Paper Movement - line feed can be stepper or DC servo, often a forms tacho as well. Paper handling - paper shifts one step at each line.

    Mechanical Structure - usually big, mostly noise suppression and paper handling. Bandprinters need about the same space as a desk

    Interfaces - fast print but just a few thousand cps. 3000 lpm 200 ch lines 10KBs. Bandprinters only print alphanumeric so 1 ch print is 1 ch transmitted

    Other Designs -
    Dot Band Printers - bands made of nothing but dots eg IBM 4234. Bands made purely of dots give graphical capability.
    Parallel Matrix - shuttle printers. Parallel dot matrix or shuttle printersClick for shuttle printer information
    Drum Printer - solid print with a drum column for each column on the paper. Drum printers - fast but heavy and expensive

    Environment - the only consumable is inked ribbon and electric power. Environmental impact - consumable is inked ribbon