The Mechanics of Ink-Free Mobile Photo Printers

How many precious photos are stored on your phone or digital camera right now? If you're like most people, it's probably a fair amount — just waiting there, consuming digital space. While we love capturing digital images, we can't help but long for the good old days of physical photos. Despite the convenience of high-quality printers, the effort and inconvenience of printing often holds us back.

Thankfully, new mobile photo printers are here to help us quickly and easily release our photos from their digital confines — and all without the need for ink.

Ink-free photo printers are significantly more compact than their traditional counterparts, offering more convenience and portability. While some stationary printers are marketed as 'mobile' for their wireless printing features, inkless technology makes printers truly portable. You can carry them in your pocket or purse, just like a smartphone. Best of all, with no need for ink, maintenance is as simple as replenishing photo paper.

What makes this photo-printing gadget tick? And is it truly compact enough to fit into your pocket? Find out more on the following page.

Details of the Ink-free Portable Photo Printer

In 2007, a spin-off company of Polaroid, named Zink, introduced its ink-free printing technology. Later, they collaborated with Polaroid to create a pocket-sized printer that won't spill ink in your pocket. Let's explore the PoGo instant mobile printer (the first device of its kind) to understand how this technology functions.

The PoGo printer connects directly to a digital camera using a USB adapter cable, eliminating the need for a computer. When connecting to your cell phone, no wires are required. Instead, the printer can receive images from the phone via Bluetooth. For those unfamiliar with How Bluetooth Works, this means your phone (if compatible) and the printer can communicate wirelessly. The phone then sends image data via radio waves to the printer when instructed.

Upon receiving the data, the printer produces a 2-inch by 3-inch color photo. The photo comes with a peel-off back that reveals an adhesive, making it ideal for use as a label.

When powered by its lithium-ion battery, the printer can produce up to 15 photos [source: Stone]. When plugged in, the AC adapter (the power cord that regulates the required current and voltage) ensures continuous printing. With the rechargeable battery attached (but without paper), the printer weighs around 8 ounces [source: Stone]. Measuring at 0.9 inches by 4.7 inches by 2.8 inches, it holds up to 10 sheets and is about the size of a pack of cards. Polaroid is betting on the device's compact size and light weight to appeal to consumers who want to carry it along with their cell phone or digital camera. The Polaroid printer is priced at around $150 [source: Bergstein].

In addition to Polaroid's efforts, Zink has teamed up with three other companies to develop devices using ink-free printing. Zink is also working on a device that brings back the classic Polaroid camera, creating a two-in-one device that serves as both a camera and an instant printer.

Zink envisions a future where these printers could even be integrated into cell phones. Since ink isn't required (only paper), these printers won't add much weight or bulk when attached to a phone or any other device. Moreover, as the specialized printing process extends beyond photos, Zink plans to incorporate similar technology into devices like laptops.

Now that we've explored what the printer can do, let's dive into how it achieves it. Next, we'll examine the zero-ink technology behind the instant image printing.

Ink-free Mobile Photo Printer Paper: The Secret Behind Portable Printers

How can you print a high-quality photo using only paper and no ink at all? It's not magic — the answer lies in the special paper itself. Here's the trick: before printing, Zink paper is just a plain white sheet. But, as the saying goes, it's what's inside that counts.

Scientists at Zink developed a special paper that holds all the "ink" needed to produce a photo. Each sheet is embedded with dye crystals that can transform into cyan, magenta, or yellow. These crystals are invisible to the naked eye and remain colorless before printing. To activate this hidden "ink," heat is introduced. The heat triggers a chemical reaction in the crystals, changing them from clear to vibrant colored dye.

To understand how the paper functions, let's take a closer look at its various layers:

Additionally, interlayers separate the imaging layers from one another, ensuring that they remain distinct during the printing process.

As the paper passes through the thermal printhead, the color that is activated depends on the temperature and duration of the heat applied by the printhead. For example, if the printer is only meant to activate the magenta layer, the heat will be insufficient to trigger the yellow crystals and won't stay on long enough to affect the cyan crystals.

The so-called "lower" temperatures and "longer" durations used in these printers are neither particularly low nor long — temperatures range from 212 to 392 degrees Fahrenheit (100 to 200 degrees Celsius), and it takes just 16 milliseconds to print a single line [source: Clarence].

By combining varying amounts of cyan, magenta, and yellow, all the colors necessary to produce a high-quality image can be achieved. Each 2-inch by 3-inch sheet contains around 100 billion dye crystals, activated by 200 million heat pulses [source: Zink].

Despite years of research and development, Zink has managed to produce this paper at a low cost, selling a 10-pack for about $3 (roughly 33 cents per sheet) for the PoGo printer [source: Kirsner]. While the PoGo printer uses 2-inch by 3-inch paper, Zink is capable of producing paper in a variety of sizes. As Zink and its partners create more compatible printers, additional paper sizes will become available.

We've established that this printer is both compact and mess-free, but what about its drawbacks? What are its pros and cons? Flip to the next page to find out more.

Mobile Photo Printer Advantages and Disadvantages

Let my pictures go! Could this pocket-sized printer be the Moses of printing devices — freeing the digital images captured in phones and digital cameras from their captivity? Perhaps, but it may need a little more lab work for PoGo to truly deliver on its promises.

Zink’s ink-free paper is inspired by traditional thermal fax paper technology. Fax paper is coated with special chemicals that darken when exposed to heat. Zink paper differs in that it can print in color, unlike fax paper, which only prints in black and white.

Zink paper has similarities to other printing technologies, such as dye diffusion thermal transfer or dye sublimation methods. While these techniques also produce color prints, they are more complex because they require an additional material (like a ribbon) that holds the ink, which must then be melted onto the paper. Zink simplifies the process by eliminating the middleman — it only needs the paper and the printer.

One clear benefit of the product is its compact size and light weight. It provides instant gratification, so there's no need to wait until you get home to print your photos on a stationary printer.

Eco-friendly users will appreciate that the paper is recyclable (unlike thermal paper) and non-toxic. Additionally, because there’s no ink cartridge or ribbon to dispose of, this printer generates no waste.

Considering all the benefits, you might expect this technology to become a massive hit. However, a few drawbacks could delay its widespread adoption, at least for now.

Some users have reported that the quality of the photos from mobile printers leaves much to be desired. For instance, David Stone, an expert reviewer for PC Magazine, noted that half of his test photos had distorted colors, and others appeared "washed out" [source: Stone]. He also tested the printer's water resistance and found that while photos can withstand immediate drops of water that are wiped off, the image suffers if the water dries on the photo. It remains to be seen whether these issues will be addressed in future updates.

As Stone pointed out, it’s no surprise that heat can alter the images after printing, considering it’s heat that triggers the printing process in the first place. When he held a print up to a hot light bulb, the colors changed. Remember, temperatures as high as 212 degrees Fahrenheit (100 degrees Celsius) are needed to activate the crystals in Zink paper. While photos are unlikely to face such extreme heat in everyday situations, it's still wise to avoid placing them in hot spots like ovens or stoves. Unlike thermal fax paper, Zink prints aren't likely to be affected by the heat in a sun-drenched car.