I'm admiring all of the clever mechanical design as I take apart a Canon Pixma MX340 multi-function inkjet, even if some of the designs were too clever for me to figure out. Fortunately some of the mechanisms are more easily understood, like the damper mechanism.

After removing the top layer housing the ADF and control panel, the next layer is home to the scanner module.

This scanning bed tilts up for access to the ink cartridges.

A spring-loaded piece of blue plastic on the right props up the scanning bed assembly (and the ADF + control panel assembly above it) while we replace ink cartridges. When the task is complete, it is tempting to retract the blue plastic support and let the top slam shut. But slamming shut would destroy fragile components like scan bed glass.

Which is why Canon engineers have incorporated a damping mechanism to make sure the lid closes gently. This mechanism is my next teardown target. I could see most of it after removing side panels from the base.

Leaving only a small clipped-in cover before the entire mechanism became accessible.

Six removed screws later, the whole damper mechanism was free. It was a lot simpler than I had expected. The black arc is rigidly attached to the scanner, with geared teeth to engage with the upper white gear. The lower white gear is where the damping happens.

Here's a closer look at the gearbox still installed. Two small black assemblies surround the lower gear, it felt like they contain a viscous fluid to accomplish their rotational damping. I might want to reuse them later, so I didn't take them apart. Which also avoided making a mess.

The upper gear is not fixed at a single location, it is allowed to move almost 1cm in a slot, with a piece of spring to hold it against the upper side of the slot. When the user lifts the scanner for a ink cartridge replacement, the upper gear follows along and moves to the higher position. This movement disengages the upper gear from the lower gear, so the lifting motion is not damped. But when the lid starts falling, the upper gear is pushed to the lower side of the slot, engaging the lower gear and its pair of little black dampers.

This meant the user can lift the lid as fast as they like and not have to fight the damper before they could access the ink cartridges. After they were done, they can let go of the lid and the dampers will automatically engage to slow the fall. I had expected something more complex was necessary to implement unidirectional damping, but it was just a movable gear held by a piece of spring. Cool.

Once the damper was removed, I looked at the hinge itself and it's a simple plastic nub in a slot. Bending a little plastic was enough to free the hinge.

Once they were both freed, I could access all of the fasteners holding the scanner module together, allowing me to take that apart and look inside.

This teardown ran far longer than I originally thought it would. Click here for the starting point.