Portable Ticket Vending Machine

[maheshkedari]

ticket vending machine

Hi all,
I am designing Portable Ticket Vending Machine. (Hand held electronic machine with small printer 80 lines, keypad and LCD (16*2)).
Please suggest me some good printers. Also i need to know some details about thermal printers. How does it work? Is laser printer available at this size if yes then how much is the cost of such printers?


Mahesh Kedari

 

[betwixt]

portable ticket printer

I can't suggest a particular printer but I can tell you to forget laser as an option.
Not only is laser quite complicated to drive, it requires a lot of mechanism and uses heat to fuse the toner to the ticket. The heat alone would require more power than your battery could provide.

Thermal printers are the best option, they are simple mechanically and very easy to drive electronically.

There are two common types, both work on the same principle. The ticket is fed through the mechanism by pulling it through motor driven rollers. Usually a stepper motor is used to give best control of speed. As it moves through the mechanism it passes a line of heating elements, these are tiny and only require a small current pulse to heat them up. They are normally mounted on a ceramic backing to allow the heat to dissipate as soon as the power is removed. When the element is on, the heat produces a dot on the ticket, and as the ticket is drawn over the elements and they are sequenced, the shape of the characters is produced.

The two types are direct and indirect, direct uses a chemically coated ticket, the chemical turns black or sometimes blue when heated. These are usually used for thin 'till roll' tickets. The other type uses a roll of chemically treated 'ink paper', usually a very thin black film. It sits between the heating element and the ticket and when heated, it transfers the ink to the ticket paper.

The second method gives a better quality print but is wasteful as most of the ink is never used and the roll cannot be used again.

If designing the whole thing, all you normally need to do is tell the printer what to print and its on-board processor does the rest. If you are making your own printer, you have to connect to a whole line of elements (one per dot per character across the ticket) and also to the stepper motor. Remember that you only print one line of dots at a time before advancing the ticket slightly so it isn't as complicated as it first appears.

Brian.