Horology: time measuring systems or devices – Crown or stem details – Switch or detent
Reexamination Certificate
2000-04-20
2001-08-07
Roskoski, Bernard (Department: 2859)
Horology: time measuring systems or devices
Crown or stem details
Switch or detent
C368S190000, C368S196000
Reexamination Certificate
active
06270251
ABSTRACT:
The present invention concerns a push-button mechanism which produces a clicking to give the user a tactile or auditory indication that it is working properly and which also, when it is set in place in an apparatus, allows the force, which has to be applied on the push-button to act against the reaction force of a mechanical control element or to close an electric contact, to be adjusted.
The invention is particularly suited to a timepiece, and in particular a chronograph watch or stop watch wherein the push-buttons provided with such a mechanism allow the three conventional functions of a chronograph to be controlled, namely stop/start and reset to zero.
A push-button is a very simple control means which comprises schematically a stem and/or a small hollow cylinder closed at one end, sliding in a transverse passage of the frame of an apparatus, and held in an inactive or rest position by elastic means which push the head of the stem towards the exterior, and brought into a working position by pressure exerted on the head. The elastic means are mainly formed, either by a helical spring housed in the transverse passage and being supported by the frame, or by a leaf spring or a wire shaped spring secured to the frame by at least one of its ends and abutting directly and/or indirectly the opposite end of the stem to the head.
In applications where the proper working of the apparatus is easily perceptible, such as the lighting of a room or the switching on of an acoustic source, these control means can be satisfactory in its most simple embodiment, even if there exist numerous possible variants in the selection of materials and in assembly techniques.
In other cases, it is necessary for the user exerting pressure on the push-button to feel with certainty that the selected function has indeed been activated, even if he is not in a position to check this visually. This is particularly so in a chronograph watch, whether it is mechanical or electronic, in which the command for starting and stopping timing by pressing on an appropriate push-button has to be synchronised with an event that the user has to observe, which no longer allows him to perform a visual check of the proper working of the chronograph.
In order to overcome this drawback, various devices have been proposed to produce a clicking which is perceptible to the user when he exerts pressure. In U.S. Pat. No. 4,451,719, a stem slides in a tube against the return force of a helical spring, the stem being provided with an elastic element which has to pass through a neck of the tube to produce a clicking immediately before activating a function. Such as device has the drawback of having a clicking effect which gradually becomes indistinct as the elastic element becomes worn, and only allows adjustment of the pressure to be exerted via selection of the compressibility of the spring.
In Japanese Utility Model No. 7812/79, the elastic means are formed by a metal strip one end of which is fixed to the bottom of a case and the free end of which, which is used to hold the push-button in the inactive position, is extended by a portion bent into a U shape substantially in the longitudinal direction of the push-button. The free branch, which is also elastic abuts against a stud driven into the plate and has at its end an overthickness which the stud has to pass through producing a clicking when pressure is exerted. In this construction, it will be noted that the pressure to be exerted is finally the result of two forces depending on the strip itself to the push-button, on the free portion of the U shaped extension, and the relative positioning of the fixing points of the strip and the stud, so that the inevitable manufacturing and mounting tolerances will result in variations which cannot be controlled from one apparatus to the next as far as the force which has to be exerted on the push-button head is concerned.
In the case of a push-button used as the control for a complex kinematic chain, it will be noted finally that the pressure to be exerted can be such that the clicking is no longer perceived in a satisfactory manner.
An object of the invention is to overcome the drawbacks of this prior art by providing a push-button mechanism with a clicking device, whose elastic return means in the inactive position are of the leaf spring type and in which the force exerted on the head of the push-button can easily be adjusted.
The invention therefore concerns a push-button mechanism for activating a mechanical or electric function including first and second members which are mobile in relation to each other in planes parallel to a plane support to form return means and to produce a clicking via the action of a force F exerted by means of the push-button, characterised in that the first member is formed by a lever which pivots via one of its ends on a stud attached to the support, said lever including two other pins arranged in a triangle with respect to the stud, and the second member of generally elongated shape includes a substantially U shaped cut-out portion delimiting a base connecting first and second arms, said base including guide means intended to slide along a guide ramp attached to the support and at least one control means for a function to be activated, the first arm of said second member being rigid and having its free end rotatably mounted on a first pin of the lever and the second arm being flexible while having at its free end a notch against which the second pin of the lever rests in the inactive position, said notch being extended by a beak having an external edge oriented towards the exterior of the U shaped cut-out portion, against which the second pin of the lever slides when a force is exerted on the rigid arm via the push-button by compressing the flexible arm and producing a clicking by passing from one position to the other.
In the foregoing, the configuration of the second member having an elongated shape with a U shaped cut-out portion evidently designates more generally any member in which the edges of each arm are not all parallel, solely because of problems of assembly with other components of the apparatus.
In an embodiment in which a reduced compactness in height is sought, as is the case in a timepiece, the two members forming the mechanism are cut into a plate of uniform thickness, the lever then having a substantially triangular shape and the U shaped member having one arm sufficiently wide to be rigid and one arm sufficiently narrow to be flexible. Any material can form these two members provided that it has a certain flexibility, but a metal or metal alloy, such as a spring steel, will preferably be selected in applications where significant longevity is desired, as is the case for timepieces.
The force necessary to pass from the inactive position to the active position can be provided at the stage of designing the geometry of the two members, such as the relative positions of the two pins and the stud on the lever, the length of the flexible arm of the second member or the inclination of the external edge of the tip situated at the end of the flexible arm. This latter solution, inclination of the external edge of the tip, has the advantage of enabling mechanisms requiring different pressure forces to be made from the same rough part, simply by appropriate machining of the edge of the tip.
According to another aspect of the invention, the force necessary to pass from the inactive position to the active position can be adjusted after mounting the mechanism in the apparatus. For this purpose, the mechanism includes means for adjusting the force F which has to be applied to the push-button, these means being arranged between the edges facing the cut-out portion so as to modify the flexion point of the flexible arm or its initial distance with respect to the rigid arm. According to a first embodiment, these adjusting means are formed by a pin with a cylindrical body able to occupy several position between facing notches arranged in parallel edges of the rigid arm and the flexible arm so as to modify the flex
ETA SA Fabriques d'Ebauches
Roskoski Bernard
Sughrue Mion Zinn Macpeak & Seas, PLLC
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