Braun Rolling Numbers Alarm Clock

This rolling numbers alarm clock works, as the name already says, not with folding or falling numbers, but with numbers, which are on roles. For the first minutes digits, it is a role with ten digts, for the 10th minutes a much smaller role with 6 numbers is used and because the role would be much too large for the 24 hours, a role and tilting mechanism with 8 prisms, which contain likewise in each case 3 numbers and scroll (and turn down), is used.

The clock is driven by (in the exemplary shown here unfortunately defective) a mini motor, which is fed by a C cell and once a minute, the time indicator advances and a spring stretches which drives again a classical clockwork with balance spring and ensures that each minute an electrical contact is closed.

And here's the inside view: