Receipts Pt 1 - Receipt Printer Basics

Receipts?

In days of old, receipts were a hand-written affair to help the buyer and/or seller of goods or services keep track of a purchase. They’ve come a long way in the intervening years. Today, they’re typically automatically generated by the Point of Sale (POS) system and are usually printed, emailed, or texted to the recipient.

There are a number of common uses for receipts. I’ll list a few examples:

• In most places of business you need your receipt to return or exchange goods you've purchased.
• If you ever travel for business, your finance department probably asks for copies of your receipts as proof of purchase for financial reimbursement.
• For those who balance their bank accounts or checkbook, each receipt is important to track every expense coming out of the purchaser's financial accounts.
• Some establishments use the receipt as a form of customer communication soliciting a satisfaction survey, informing the customer of new items for sale, for issuing discounts or coupons, etc.
• Many more use cases I'm sure I've missed

Unless you have a specific use for your receipt, they’re either declined at the cash register, end up in your wallet, purse, pocket, car, or in the trash.

To most businesses, the receipt is a sunk cost that’s just a mandated part of doing business.

For most of these uses, the receipt just needs to contain a few pieces of information to be useful. The date, time, a list of goods or services purchased, prices for those items, and payment information. Other common basic information can include the name of the business, its address, its telephone number, the cashier name.

To accomplish its basic purpose(es) a receipt can simply be formatted plain text, but some businesses go a step farther by printing a graphic of their logo somewhere on the receipt for brand recognition.

Receipts!

So why am I bothering to write about receipts? I happen to work in a career that involves receipt printing — really thrilling stuff to most people I’m sure. Through the course of my job I’ve spent more than my fair share of time printing and analyzing receipts. The pieces I write on my blog about receipts are very much separate from my work and I’m going to stay away from bringing up the company I work for or its products.

Ultimately, this post is intended to set the stage for a more technical discussion of a very specific aspect of receipt printing. I’m going to try to strike a balance between laying some groundwork to introduce relevant topics without getting too deep into subjects that are outside of my intended focus.

In my professional duties I really only interact with one type of receipt printer.

Common Receipt Printer Types

A receipt can be printed by a standard document printer on standard printer paper, but the amount of real estate provided by Letter or A4 sized paper often considerably dwarfs what is needed for a standard receipt. Also, if the list of items purchased is considerable the receipt may grow to a length that far exceeds the length of any standard paper size. To avoid wasting paper, both materials and the cost of said materials, the industry has come up with dedicated receipt printers.

• Impact Receipt Printers
  I don't have a lot of experience with Impact Receipt Printers, so a barebones description is likely all I'll write on the topic.
  
  These are essentially miniature dot-matrix printers which print on a roll of matte receipt paper. They operate somewhat similarly to a typewriter where the print head impacts an ink ribbon to deposit ink onto the receipt paper. By making many impacts as a motor feeds the receipt paper, letters or basic shapes can be drawn. To the best of my knowledge, these printers cannot print graphics unless rendered as ASCII art. These printers are generally loud and slow. They have two consumables: the ink ribbon and the receipt paper. Despite these downsides, impact printers are commonly used to print kitchen orders because the paper + ink combination is not susceptible to heat. You'll also commonly find impact receipts on top of pizza boxes, as these are also usually hot.
  
  Impact printers are generally monochromatic, though not always black and white — red or blue inks are also common.


• Thermal Receipt Printers
  Thermal receipt printers are a more developed response to the shortcomings of impact receipt printers. As the name suggests, they print receipts thermally. But what does that mean? Similar to impact printers, thermal receipt printers are generally monochrome and use a roll of paper as their media. But in the case of thermal receipt printer paper, the surface is treated with a special heat-reactive pigment. This allows the printer to eliminate the need for an ink ribbon — the paper is both the printable surface AND the "ink". Having just one consumable simplifies buying supplies and performing maintenance on these printers.
  
  Unlike an impact printer that uses physical pressure to make its mark, a thermal receipt printer passes its paper over a metal bar that can be very rapidly and precisely heated as the paper is fed across it. The paper's surface starts as a glossy, usually white material, though other colors can be used. Blue, red, yellow, or green backgrounds are also somewhat common. The pigment can also be one of several colors, but black is most common. As the hot metal comes in contact with the paper, the pigment reacts causing it to darken and thus print the specified content on the paper.
  
  This interaction between the print head and the paper is why if you leave a thermal receipt in a hot car you might return to find that the whole thing has turned black -- because the pigment of the whole receipt has gotten hot enough for it to change color as if it had been printed on.
  
  Thermal receipt paper and thermal receipt printers are usually monochromatic, though there are some specialty printers that can print two colors through the use of two pigments with different reaction temperatures. Some of the latest receipt printers have the added ability to print shades of gray, by using a very fine dot pattern and carefully only partially reacting the thermal pigment. This can drastically improve graphical print quality, but usually comes at the cost of print speed.
  
  The thermal pigment can also be applied to stickers, commonly found as shipping labels or on the side of your Starbucks beverage.
  
  Another trick some receipt printers have up their sleeve is the ability to print on both sides of the receipt. This of course requires special receipt paper that has the heat-reactive pigment on both sides of the paper and requires a more complex print head with two heated metal bars.
  
  The thermal control of a thermal receipt printer is surprisingly advanced. The printers achieve a print resolution of roughly 180 dpi and the faster models can print several inches of receipt per second.

Why does this matter?

Where I’m going with this series is an analysis and discussion of printing graphics on receipts.

While this primer barely scratches the surface of the technology that enables printing receipts. I find that some common terminology and a basic understanding of a topic can aid in further discussing it.