Wiggling thermal print head doubles resolution in Sears 12

Sears 12 uses a clever mechanical trick to double the resolution of its thermal printer by wobbling the print head during operation. The design adds a side-to-side motion to a single line of heating elements, effectively creating two sub-pixel positions for each element and cutting the dot size in half.

This approach reduces the number of required thermal elements compared with a straight-line head, lowering component costs and simplifying the driving circuitry. The video by Danalog demonstrates the movement and compares the output to a TI-5015 calculator that lacks the wiebelmechanisme.

Inside the calculator lies a Mitsubishi M58671 IC that controls both the computation and the printer mechanism, while the moving head improves print quality without increasing the bill of materials. The technique was a selling point in the 1970s when calculators still printed results on paper, and it remains relevant for modern low-cost thermal printers. Meer details staan op de pagina van Hackaday.