Inside an Inkjet Photo Printer

Even today's budget-priced home printers churn out quality photos that a few years ago you could have gotten only from a professional printing house. Key to the high quality are steady improvements in print heads, which can eject smaller and smaller droplets of ink with ever-greater precision.

A decade ago, eight-picoliter drops (that's eight trillionths of a liter) were considered small. These days, inkjet printers deliver drops as tiny as one picoliter through thousands of nozzles—some less than half the width of a human hair.

To make prints that look like photos instead of finger paintings, the printer must precisely control how much ink comes out of every nozzle, every time, at a rate of up to 22,000 drops per second.

Two types of technology can squeeze ink through the nozzles.

Here's an intimate look at what's happening inside your image-making machine.

Canon's printers use thermal nozzles, which can all be a single capacity, such as three picoliters, or various sizes, like one, three and five. Smaller drops render fine details like eyelashes; larger drops cover broad areas such as a blue sky. Software on your PC and printer decide which nozzles to use based on features in each part of the image, and the print head lays down all the necessary colors in a single pass.

Don't just unplug your printer; always turn it off using the power button. When you do, it places protective caps over the nozzles before shutting down. This helps prevent clogs due to ink accumulating in the print head and drying out.

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