• Casio GS-1200 to use LEDs to tweak analog hand position

    John Biggs

    Biggs is the East Coast Editor of TechCrunch. Biggs has written for the New York Times, InSync, USA Weekend, Popular Mechanics, Popular Science, Money and a number of other outlets on technology and wristwatches. He is the former editor-in-chief of Gizmodo.com and lives in Bay Ridge, Brooklyn. You can Tweet him here and G+ him here. Email him directly at... → Learn More

    Friday, August 1st, 2008


    A new Casio movement for the GS-1200 Tough line – a radio controlled watch model built for shock resistance – has internal LEDs that calibrate the analog hands of the watch.

    The movement has a structure where the gears for second, minute and hour are sandwiched between the LED and the phototransistor. With this setup, it is possible to detect the positions of three gears by one sensor. The LED emits light 16 times a second to check the positions of the 300mum diameter detection holes that are formed on the gears.

    Most mechanical analog watches eventually slip out of alignment due to the internal motor. Buy adding the tiny LED and photosensor, the watch processor can tell exactly where the hands are on the face and ensure that the user won’t have to recalibrate the watch later.

    This is similar to the methods used to sense positions in the old-time mechanical mice.

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