A keyboard system comprises a key structure including a key switch with a lighting element and phototransistor, and one or more processors that drive the lighting element for a first pulse duration. The output of the phototransistor is determined at the end of the first pulse duration, wherein the key structure is determined to be pressed when the output is below a first output value at an end of the first pulse duration, and unpressed when the output of the phototransistor is above a second output value at the end of the first pulse duration. A fall-time of the output during the first pulse duration is determined and the first pulse duration is calibrated to a second pulse duration when the fall time less than the first pulse duration, the second pulse duration being greater than the fall time and less than the first pulse duration.

A keyboard system comprises a key structure including a key switch with a lighting element and phototransistor, and one or more processors that drive the lighting element for a first pulse duration. The output of the phototransistor is determined at the end of the first pulse duration, wherein the key structure is determined to be pressed when the output is below a first output value at an end of the first pulse duration, and unpressed when the output of the phototransistor is above a second output value at the end of the first pulse duration. A fall-time of the output during the first pulse duration is determined and the first pulse duration is calibrated to a second pulse duration when the fall time less than the first pulse duration, the second pulse duration being greater than the fall time and less than the first pulse duration.

A keyboard key structure comprising a key stem, a contact-based mechanical trigger, and a contactless analog key switch. The key stem is configured to be depressed and move along a linear path over a range of operation. The contact-based mechanical trigger is configured to activate after the key stem is depressed a threshold distance in the range of operation. In response to the contact-based mechanical trigger activating, the contactless analog key switch is configured to detect, at a sample rate, a position of the key stem between the threshold distance and an end of the range of operation after the key stem is depressed. The contact-based mechanical trigger can be a galvanic-type key switch. The contactless analog key switch can be one of an optical key switch, a magnetic key switch, or an inductive key switch.