Horology: time measuring systems or devices – Chronological – With mechanical or electromechanical driven display
Reexamination Certificate
1999-06-21
2001-10-23
Gutierrez, Diego (Department: 2859)
Horology: time measuring systems or devices
Chronological
With mechanical or electromechanical driven display
C368S073000, C368S187000, C368S250000
Reexamination Certificate
active
06307814
ABSTRACT:
FIELD OF THE INVENTION
The present invention concerns on the one hand a device of small dimensions including at least two coaxial wheels, rotatably mounted about a same geometrical axis of rotation and means for detecting the angular positions of the reference geometrical semi-axes associated with said wheels. On the other hand, the present invention concerns a method for detecting the angular positions of several coaxial wheels which can be applied to the device according to the invention.
BACKGROUND OF THE INVENTION
Those skilled in the art know optical devices for detecting the reference angular positions of wheels, in particular coaxial wheels belonging to the gear train of a clockwork movement. All these optical detection devices are relatively complex. They require a light source and a light receiver at a distance from said source. The mounting of an optical detection device is often difficult given the precise adjustment necessary between the light source, the receiver and the wheels associated with such device. In the case of the present invention, one thus proposes omitting any optical wheel position detection system for a device of small dimensions.
International Patent Application No. 97/45705 discloses a system for detecting the position of coaxial wheels respectively associated with coaxial hands of a clockwork movement. On each of the coaxial wheels, formed of full plates, are arranged several discrete portions of a hard magnetic film defining an identification pattern for a contactless inductive sensor. An inductive sensor is associated with each of the coaxial wheels. In other words, there are as many magnetic inductive sensors as coaxial wheels whose angular positions have to be detected, in particular given reference positions. The amplitude of the signal detected by the inductive sensors varies according to whether or not they are situated in front of a segment of magnetic material, as is shown in particular in
FIGS. 3 and 4
of the International Patent Application.
The detection system proposed in Patent Document No. WO 97/45705 is disadvantageous in that each wheel associated with an inductive sensor must be fitted with the segment or distinct portion of a solid magnetic film arranged on one face of the plate of the wheel. The manufacturing cost of the wheels is thus increased and the wheel plates are full or solid, which can be a drawback for the working of the clockwork movement, in particular from the point of view of power consumption. The wheel plates are formed of at least two different materials, namely the material forming the plate itself and the magnetic material arranged on one surface of this plate. In addition to these drawbacks, a major drawback relating to the cost of the detection system proposed and to the space requirement thereof will be mentioned, namely that there are as many inductive sensors as wheels whose position has to be detected. Thus, for three coaxial wheels, there are three inductive sensors respectively associated with said three wheels.
SUMMARY OF THE INVENTION
An object of the present invention is to overcome the aforementioned drawbacks by providing a device of small dimensions including coaxial wheels and efficient means for detecting the angular position of at least two coaxial wheels which are relatively simple, inexpensive, compact and easily able to be integrated into the device.
The present invention therefore concerns a device of small dimensions, in particular of the horological type, including a first wheel and a second wheel which are coaxial, rotatably mounted about a same geometrical axis of rotation and respectively including a first plate and a second plate perpendicular to said geometrical axis of rotation, this device further including means for detecting the angular positions of a first reference geometrical semi-axis of said first wheel, and a second reference geometrical semi-axis of said second wheel, this device being characterised in that said means for detecting the angular positions of said first and second semiaxes are formed by a single inductive or capacitive sensor provided with an element for detecting the presence of active materials above or below it, said first plate including at least one inactive region for said sensor, said first and second plates being formed at least partially of active materials for said sensor, said sensor being arranged relative to said first wheel so that its detection element is at least in part above or below said first inactive region in at least one determined angular position of said first wheel.
As a result of the features of the device according to the invention, the respective angular positions of at least two coaxial wheels are determined using a single inductive or capacitive sensor, in particular using an inductive sensor whose electronic circuit is disclosed in European Patent No. 0 746 100, which is integrated by reference in the present description.
The use of an inductive proximity sensor is particularly well suited to the case of the present invention, such a sensor being able to detect the presence of various materials, in particular non ferromagnetic metals like aluminium or brass which are widely used for the manufacture of wheels and other clockwork movement parts.
According to a preferred embodiment, said first inactive region of the plate of the first wheel is defined by a first opening provided in such plate. More generally, all the inactive regions of the plates of the coaxial wheels associated with the sensor are defined by openings. Consequently, the plates of the coaxial wheels can be formed of a single same active material for the selected sensor, the openings provided in these plates corresponding to inactive regions for the sensor.
Another object of the invention is to provide a method for detecting the angular positions of N coaxial wheels able to be applied to the device according to the invention in an efficient and reliable manner, i.e. assuring a level of accuracy in the detection of said angular positions.
The present invention therefore concerns a method for detecting the angular positions of N coaxial wheels, N being greater than 1, by means of a single inductive or capacitive sensor, these N wheels including respectively N plates each having at least one inactive region for said sensor which includes an element for detecting active materials forming at least partially each of said N plates, this detection element and each of said inactive regions being arranged so that they are superposed one above the other in at least one determined angular position of the wheel having said inactive region, said N plates each defining a reference geometrical semi-axis which can be detected by said sensor, said method comprising the following successive steps wherein the N plates are numbered in an ascending order from the plate situated closest to said detection element to the plate the furthest from said detection element:
A) Determining the angular position of said semi-axis of wheel No. 1;
B) Bringing or leaving said inactive region of wheel No. 1 into superposition with said detection element, or waiting until this inactive region and detection element are superposed with each other;
C) Performing steps A) and B) successively for wheel Nos. 2 to (N−1), if required;
D) Determining the angular position of said semi-axis of wheel N.
As a result of the features of this method, it is possible to detect, using a single inductive or capacitive sensor, at least one reference angular position of each of the coaxial wheels of a device, in particular of a clockwork movement.
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patent: 58
Bernasconi Ermanno
Born Jean-Jacques
Farine Pierre-Andre
Asulab S.A.
Goodwin Jeanne-Marguerite
Griffin & Szipl, P.C.
Gutierrez Diego
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