This invention relates to a rotary pulse switch which activates one switch circuit when an operating shaft is rotated in one direction, and activates another switch circuit when the operating shaft is rotated in the other direction. More particularly, the present invention relates to such a rotary pulse switch of a reduced size.
Rotary pulse switches such as that shown in FIGS. 1 through 5 have been known, for example, as described in U.S. Pat. No. 4,282,415.
In such a switch, a case molded from synthetic resin is formed of two parts 1 and 2, and has a central operating shaft 3 supporting a rotor 4 having an oblong central hole 4a receiving the operating shaft for rotation therewith. Elongate movable contacts 5 and 7 extend along respective sides of the case and have their lower end portions held in the grooves 1c formed in case part 1 in parallel spaced relation to fixed contacts 6 and 8 held in respective grooves 1c. The upper free ends of the movable contacts 5 and 7 carry respective contact portions 5a and 7a facing the upper end portions of the fixed contacts 6 and 8.
An operating member 9 is held for laterally sliding movement within the switch by projections 1b formed on the case past 1, and a nodal leaf spring 10 is supported in the lower portion of the case part 2 by projections 2b. The operating shaft 3 carrying the rotor 4 for unitary rotation is supported within the central holes 1a and 2a in the case parts 1 and 2, respectively. The rotor 4 is molded from a synthetic resin and has a plurality of projections 4.sub.1, 4.sub.2, etc. positioned equidistantly around its circumference and projecting from both surfaces of the rotor in the direction parallel to the operating shafts.
End portions 9a and 9b of the operating member 9 substantially face the rear surfaces of contact portions 5a, 7a formed at the ends of the movable contacts 5 and 7. A central projection 9c of the operating member 9 is located at a position within the path of movement of the projections 4.sub.1, 4.sub.2, etc. as the rotor 4 is rotated.
In the rotary pulse switch of the kind described above, when the operating shaft 3 rotates in the direction of the arrow A in FIG. 4, the rotor 4 rotates with it and the projection 4.sub.3 of the rotor 4 moves in the direction of the arrow A so as to push the projection 9c of the operating member 9 leftwardly in the direction of the arrow B, so that the operating member 9 moves in the direction of the arrow B and the end portion 9a of the operating member 9 pushes the movable contact 5 into engagement with the fixed contact 6.
When the rotor 4 rotates further, the projection 9c is pushed upwardly by the projection 4.sub.3 due to the inherent resiliency of the operating member 9 so that the projection 4.sub.3 of the rotor 4 rides under the projection 9c and the projection 9c is positioned between the projections 4.sub.3 and 4.sub.5. At this time, the operating member 9 returns in the direction opposite to the arrow B because of the resiliency of the movable contact 5, thus disengage the movable contact 5 and the fixed contact 6. A projection 10a of the nodal leaf spring 10 engages with or disengages from the projections 4.sub.2, 4.sub.4, etc. on the rear surface of the rotor 4 simultaneously with the operation described above to provide a clear nodal contact. Although the above deals with a rotation to the left, rotation to the right can be carried out in exactly the same way to cause the contacts 7 and 8 to repetitively engage and disengage.
In the conventional rotary pulse switch of the type described above, however, a plurality of projections 4.sub.1, 4.sub.2, etc. are provided equidistantly around an oblong hole 4a at the center of the rotor 4 in such a manner so as to project from both surfaces of the rotor in a direction parallel to the operating shaft, and contact pairs consisting of movable contacts 5 and 7 and fixed contacts 6 and 8 are spaced from respective sides from the outer periphery of the rotor 4, so that they do not come into contact with the projections 4.sub.1, 4.sub.2 etc. For this reason, the width of the case 1 into which the movable and fixed contacts are fitted must be somewhat greater than the diameter of the rotor 4.
The end portions 9a and 9b of the operating member 9 disposed slidably between the two contact pairs are separated vertically from the projection 9c that moves into contact with the projections 4.sub.1, 4.sub.3, etc. of the rotor 4, so that the height of the case 1 supporting the operating member 9 must also be increased. Hence, the prior art device has the problem that the overall size of the switch can not be reduced easily.