Electric Timepiece Assembly

Abstract

An electric timepiece assembly wherein a flat blade is maintained in oscillation by electrostatic forces acting between said blade and electrode means and wherein said oscillation is transmitted from said blade to a rigid member of which the amplitude is limited by stops, and a stepping wheel is operated by said rigid member.

Description

BACKGROUND OF THE INVENTION

The present invention relates to an electric clock having a flat spring which acts on a stepping gear and is oscillated by electrostatic means. Such a driving system is particularly suitable for a clock having an isotope battery as a source of energy, since such batteries supply a relatively high voltage with very low current. Particular difficulty, however, was encountered when converting the oscillation of the spring into a rotary movement for driving the gearwheels of a clock, because the movements of the plate spring were too inaccurate and irregular to actuate a delicate stepping gear directly.

It is the object of the present invention to overcome this difficulty, and provide an electrostatically driven clock movement.

SUMMARY OF THE INVENTION

According therefore to the present invention there is provided an electrically driven timepiece assembly having a flat spring oscillated by electrostatic means, wherein the said spring drives a stepping wheel via a rigid armature the rotary movement of which is limited by stops.

This construction renders the action of the stepping movement substantially independent of the movement of the flat spring. The adjustment of the various parts is not very critical, and the transmission path from the spring to the armature preferably includes some lost motion.

BRIEF DESCRIPTION OF THE DRAWING

The FIGURE is a diagrammatic plan view of an electrically driven timepiece assembly according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring specifically to the drawing, one end of a flat spring 2 is clamped in a block 1 secured to a watch plate or on a frame of a clock. The spring 2 is electrically insulated from the block 1, or the latter from the plate or frame, and projects with clearance between two plate-shaped electrodes 3 and 4, between which a source of voltage 5 is connected. The free end of the flat spring 2 is located in a small lost motion space between two pins 6 of an armature 7 which is pivoted at 8. The rotary movement of the armature is limited by two stops 9. The two arms of the armature are each provided with a stepping pin 10. These stepping pins act at two positions on a scape wheel 11 which by means of a gear train, of which pinions 12 and 13 and a wheel 14 are indicated, drives the hands or other time indicating mechanism of the clock. The pins 6 are preferably located at or close to a node of the spring 2.

The arrangement shown operates as follows. During its oscillation the spring 2 moves between end positions each in contact with an electrode 3 or 4. In each position it is charged to the potential of the electrode contacted and is then subjected to a repulsion force directed towards the other electrode. In this manner an oscillation is maintained. By means of the pins 6 the oscillation of the spring 2 is transmitted to the armature 7, the amplitude of which is defined by the stops 9. The stepping pins 10 engage alternately in the teeth of the stepping wheel 11 and intermittently drive it in a rotary direction.

The advantages of the arrangement shown arise from the accurately determined movement of the armature. Variable spring movement amplitude, baffle action on contact with the electrodes 3 and 4, and possible twisting of the flat spring, lead to irregular movement of the scope wheel 11 if operated directly by the spring. In any case it would be necessary for the stepping members to be very accurately set, which in the embodiment shown is unnecessary.

Although the invention has been described above with reference to clocks it may advantageously be used in any type of timepiece such as in wrist watches.

Claims

What we claim is:

1. An electrically driven timepiece assembly, comprising a rigid armature pivotally mounted for driving a stepping wheel; a flexible flat spring; electrostatic means connected with said flat spring for oscillating the same and including electrode means against which said spring abuts during oscillatory movement; means coupling said spring to said rigid armature for driving the same, said coupling means including a pair of spaced upstanding projections on said armature between which said spring passes; and stop means limiting the movement of said armature independently of the degree of movement of said spring whereby said armature is accurately, indirectly driven by said electrostatic means.

2. A timepiece assembly according to claim 1, wherein said armature has a generally Y-shaped configuration and is mounted for rotation about a central point thereon, a first leg of said armature supporting said upstanding projections which comprise a pair of spaced pins between which said spring passes for driving said armature.

3. A timepiece assembly according to claim 2, wherein said spring is attached at one end to a frame and cooperates at a node with said pins of said armature.

4. A timepiece assembly according to claim 2, wherein said stop means coact with said first leg, and wherein second and third legs of said armature each support a protruding stepping pin disposed for cooperation with said stepping wheel at points circumferentially spaced thereabout.

5. An electrically driven timepiece assembly comprising, in combination, a frame; a flat, elongated spring attached at one end to said frame; electrostatic means cooperating with said spring for oscillating the same between a pair of spaced electrodes; a stepping wheel; a rigid armature mounted for rotary movement about a central point thereon, said armature coacting with said stepping wheel for stepwise advancement of the same; stop means limiting the movement of said armature; and means coupling the oscillatory movement of said spring to said rigid armature, said coupling means including a pair of spaced upstanding projections on said armature between which said spring passes whereby said armature is accurately driven without electrode chatter.

6. An electrically driven timepiece assembly according to claim 5, wherein said means coupling the oscillatory movement of said spring to said rigid armature comprises lost motion coupling means.