Abstract: A timer operative by means of a clock mechanism and having a variable operation period, wherein a main cam plate and a subsidiary cam plate are mounted coaxially on a common shaft so that they are rotatable relative to each other, each of said main and subsidiary cam plates having recessed peripheral portions and protruded peripheral portions. A single operation lever pressingly bears against the peripheral portions of said main and subsidiary cam plates so that, when the recessed peripheral portions of said main and subsidiary cam plates are brought into alignment with each other, the operation lever can drop into said aligned recessed peripheral portions.

Abstract: The present invention relates to a counter feed mechanism as used in digital clock comprising a cam member adapted for advanced rotation and another cam member adapted for delayed rotation both arranged on a common axis so that the advanced rotation of the first-mentioned cam member under a drive force transmitted from a clock mechanism twists a coil spring stretched between both cam members, which is, in turn, charged with energy for rotation of the second-mentioned cam member and, upon rotary displacement of the first-mentioned cam member by a predetermined angle, said second cam member is released to be rotated at once so as to advance a rotary wheel step by step.