Horology: time measuring systems or devices – Regulating means – For setting
Reexamination Certificate
1999-05-19
2001-06-26
Miska, Vit (Department: 2859)
Horology: time measuring systems or devices
Regulating means
For setting
C368S196000
Reexamination Certificate
active
06252827
ABSTRACT:
Arrangement for setting the minute hand of a timepiece which has at least minute and second hands
FIELD AND BACKGROUND OF THE INVENTION
The invention relates to an arrangement for setting the minute hand of a timepiece which has at least minute and second hands, having a setting stem which can be moved axially out of a normal position into a setting position, it being the case that, upon movement of the setting stem out of the normal position into the setting position, a zero setting drive of the second hand can be driven such that it moves the latter into its zero position and the seconds stem, which bears the second hand, can be driven via a seconds-display drive mechanism of the movement mechanism of the timepiece.
In the case of a known arrangement of this type, the zero setting drive is a heart-cam zero setting drive which, depending on the position of the heart cam, moves the second hand into the zero position in the clockwise direction or the counterclockwise direction. As a result of production tolerances, there is always play in the wheel train leading to the seconds-display drive mechanism, and this play has to be overcome upon a zero setting movement of the second hand in the counterclockwise direction. If the second hand is then driven again in normal operation, the play in the wheel train must first be overcome before the second hand is moved. This results in the starting of the second hand being delayed, and thus in the time display being incorrect by from one to two seconds.
SUMMARY OF THE INVENTION
The objective of the invention is thus to provide an arrangement of the type mentioned in the introduction which ensures that the second hand starts correctly following a setting operation.
This object is achieved according to the invention in that the seconds-display drive mechanism has a blocking device which can be actuated, by virtue of the setting stem being moved in the direction of the setting position, such that the seconds-display drive mechanism is blocked before the second hand is moved into the zero position.
This means that the seconds-display drive mechanism is blocked before the zero setting movement of the second hand, with the result that said drive mechanism always remains free of play in the normal drive direction and ensures that the second hand starts correctly following a setting operation.
The setting stem may serve exclusively for the zero setting of the second hand.
If the setting stem is a minute setting stem of the timepiece and the setting position is the minute setting position, in which, by virtue of rotation of the setting stem, the minute hand can be driven such that it can be moved manually, then the setting stem fulfils both the function of initiating operation of the zero setting drive and the function of actuating the minute setting. Movement of the setting stem into its minute setting position alone automatically brings about zero setting of the second hand. In order to be able to carry out zero setting of the second hand without the drive of the movement mechanism being affected thereby, the seconds stem may be coupled to the movement mechanism of the timepiece with a force fit. For this purpose, in a straightforward embodiment, there may be arranged between the seconds stem and a seconds-display drive mechanism of the movement mechanism a prestressed coupling spring which butts against at least either the seconds stem or the seconds-display drive mechanism with a friction fit.
A space-saving embodiment is achieved in that the seconds-display drive mechanism is mounted on the seconds stem in a freely rotatable manner, it being possible, without any great amount of installation space being required, for the coupling spring to be arranged axially between the seconds stem and seconds-display drive mechanism.
Both a straightforward construction of the coupling spring and concentric loading of the components on which the coupling spring acts are achieved if the coupling spring is a spring which has one or more radially directed spring arms, of which one spring-arm end is arranged on the seconds stem and the second spring-arm end is supported on the end side of the seconds-display drive mechanism, it being possible for the second spring-arm end to be supported on a radially directed, flange-like widened section of the gear wheel.
In a straightforward configuration, the blocking device may have a blocking lever which can be pivoted about a pivot spindle and which can act on a moveable drive part of the seconds-display mechanism with a force fit and/or form fit and/or friction fit.
Fulfilling a double function, and thus saving space, the moveable drive part may be the flange-like widened section of the seconds-display drive mechanism, of which the radially peripheral lateral surface can have the blocking lever acting on it.
The seconds-display drive mechanism is blocked particularly reliably in that the radially peripheral lateral surface has a radially peripheral approximately V-shaped groove into which the blocking lever, which can be pivoted about the pivot spindle parallel to the axis of rotation of the seconds-display drive mechanism, can be pivoted by way of an approximately V-shaped blocking region.
A reliably functioning construction of straightforward configuration is achieved if the zero setting drive is a cam-plate drive, of which the cam plate is arranged fixedly on the seconds stem, which bears the second hand, and, upon movement of the setting stem in the direction of the setting position, can be driven such that it can be moved into the zero position by a zero setting lever, for which purpose the cam-plate drive is preferably a heart-cam zero setting drive. If the cam plate can be arrested in the zero position by the zero setting lever, then these components serve not just for movement into the zero position, but also for keeping the second hand in the zero position.
Just a small amount of installation space is required if the zero setting lever is a lever which can be pivoted about a spindle parallel to the seconds stem and which acts on the radially peripheral lateral surface of the cam plate.
A straightforward and space-saving setting drive is achieved in that the zero setting drive has a pivot lever which can be pivoted, about a pivot spindle parallel to the seconds stem, between a normal position and a zero setting position, which is forced into its zero setting position by spring action and which can act on the zero setting lever such that it can be moved out of its normal position, in which it is spaced apart from the cam plate, against the cam plate.
If the blocking lever can be driven such that it can be pivoted by the pivot lever, then the pivot lever fulfils more than one function at the same time.
Blocking of the seconds-display drive mechanism before the second hand is moved into the zero position is achieved, in a straightforward construction, in that the pivot spindle of the blocking lever and the spindle of the zero setting lever are arranged axially with respect to one another, and the blocking engagement direction of the blocking lever and the zero setting direction of the zero setting lever are oriented in approximately the same way.
If the action of a blocking spring forces the blocking lever both in the blocking engagement direction and against the pivot lever, such that the latter is forced into the zero setting position, then the blocking lever, following its blocking engagement, can easily be released from the pivot lever and this can move on further in relation to the cam plate of the cam-plate drive. For this purpose, a straightforward construction consists in that the action of the blocking spring forces the blocking lever into abutment against a stop of the pivot lever or of the zero setting lever, it being the case that, when the blocking lever and pivot lever are respectively pivoted in the blocking engagement direction and the zero setting direction, the blocking lever reaches the blocking position before the zero setting lever reaches the zero setting position.
REFERENCES:
patent: 3526088
Farber Martin A.
Lange Uhren GmbH
Miska Vit
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