Aim
The idea was simple. To produce a portable printer that attached to the underside of a digital camera, which could produce prints as quickly and cheaply as possible. I wanted to produce a system that was fun to use and could produce print almost instantly without the burden of expensive media or inks.
The realisation of this idea took much planning and tinkering over a period of about 8 months.
Hardware
Inside the main case there is a thermal printer, Raspberry Pi single board computer, LCD display, lithium ion rechargeable batteries and a voltage regulator. The most challenging aspect of the project was designing a mobile power source for the printer, initial tests using rechargeable AA batteries showed that these were unable to provide the current required by the printer, and the switch to lithium ion cells introduced new challenges.
Software
The printer runs the Raspbian distribution of Linux. The control code is written in a combination of Bash scripts and python and uses several open source programs to perform camera control, image scaling and file management.
Performance
I am very happy with the performance of the printer and it has caused several smiles amongst those who have used it or seen it operate. Prints are produced within a few seconds and are of surprising good quality considering this type of printer is designed to print text. Battery life is very good and a roll of receipt paper should produce about 200 prints, because the printer does not require ink the only cost of printing is the paper, about 0.5 pence per image. As always with this type of project there is still work to do, I plan to continue improving performance with further software changes.
Photographs
Below are a selection of photographs showing the printer in action and inside the case.
