Device including at least two coaxial wheels and means for detecting the angular position thereof and method for detecting said angular positions

Information

  • Patent Grant
  • 6307814
  • Patent Number
    6,307,814
  • Date Filed
    Monday, June 21, 1999
    25 years ago
  • Date Issued
    Tuesday, October 23, 2001
    23 years ago
Abstract
A device of small dimensions includes a two coaxial wheels (4, 6) respectively including two plates (44, 46) parallel to each other. A sensor (10) including a detection element (14).formed by a magnetic or capacitive element, in particular a flat spiral coil, is provided for detecting the angular position of both of the two wheels. In order to do this, the sensor (10) detects the presence or absence of an active material above the detection element (14). For this purpose, each of plates (44) and (46) has at least one inactive region for the sensor and is formed at least partially of active material for the sensor. The sensor is arranged relative to the wheel the closest to the detection element in such a way that the latter is at least in part above or below said at least one inactive region in at least one determined angular position of said wheel so as to allow the sensor to detect the angular position of the wheel whose plate (44) is furthest from the detection element (14). The inactive regions of the plates are preferably formed by openings.
Description




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.











BRIEF DESCRIPTION OF THE DRAWINGS




The present invention will be described in more detail hereinafter, with reference to the anneal drawings which are given by way of non-limiting example, and in which:





FIG. 1

is a schematic plane view of two coaxial wheels associated with an inductive sensor;





FIG. 2

is a cross-section along the line II—II of

FIG. 1

, the hands not having been shorn while other elements of the device of

FIG. 1

are shown;





FIG. 3

shows schematically a measurement curve of the type able to be obtained using measuring signals provided by the device of

FIGS. 1 and 2

, this curve allowing the reference angular position of one or other of the two coaxial wheels to be determined;





FIG. 4

shows schematically in plane a second embodiment according to the invention;





FIG. 5

is a similar cross-section to

FIG. 2

along the line V—V of

FIG. 4

;





FIG. 6

shows schematically a curve obtained using measuring signals provided by the sensor of the device of

FIGS. 4 and 5

, allowing the reference angular position of one or other of the two coaxial wheels of such device to be determined;





FIG. 7

is similar cross-section to that of

FIG. 5

, of a third embodiment of the device according to the invention;





FIG. 8

is a similar cross-section to

FIG. 5

, of a fourth embodiment of the device according to the invention;





FIG. 9

shows schematically an alternative embodiment of the coaxial wheels shown in the preceding Figures;





FIG. 10

shows schematically a curve obtained using measuring signals during a transition between a full or portion and an opening of the wheel shown in

FIG. 9

; and,





FIG. 11

shows two coaxial wheels associated with a capacitive sensor.











DESCRIPTION OF PREFERRED EMBODIMENTS




With reference to

FIGS. 1

to


3


, a first embodiment of a device according to the invention and a mode for detecting the angular position of the two coaxial wheels associated therewith will be described hereinafter.




The device includes two coaxial wheels


4


and


6


, rotatably mounted about a same geometrical axis of rotation


8


. These two wheels have respectively two plates


4


A and


6


A which are parallel to each other and perpendicular to geometrical axis


8


. In order to determine the respective angular positions of two reference semi-axes associated respectively with the two plates


4


A and


6


A, there is provided an inductive sensor


10


including a support


12


on one face of which is arranged an element for detecting the presence of the material forming plates


4


and


6


above said detection element. This detection element is formed by a flat spiral coil


14


. Two openings


4


B and


6


B provided respectively in plates


4


and


6


are associated with sensor


10


. It will be noted that in an embodiment which is not shown, the coil can be formed by a self-supporting winding.




Wheels


4


and


6


are respectively associated with two hands


16


and


18


of an analogue display. The cylindrical shaft


24


and


26


of wheels


4


and


6


are rotatably mounted about a central shaft


28


.




Plates


4


A and


6


A are formed of materials which are active for sensor


10


, i.e. materials whose presence in proximity to detection element


14


is detected by inductive sensor


10


. Openings


4


B and


6


B define first and second inactive regions of plates


4


A and


6


A. In the preferred case in which these inactive regions are formed by openings, the absence of material in superposition with coil


14


generates a different measuring signal to that provided in the presence of active materials forming plates


4


A and


6


A in superposition with said coil


14


.




The detection of reference semi-axis


30


of wheel


6


whose plate


6


A is closest to detection element


14


will be described first. In order to do this reference will be made to

FIG. 3

which corresponds to

FIG. 3

of European Patent No. 98110729.5 whose content is incorporated in the present description by reference.





FIG. 3

shows schematically a curve


32


obtained by a succession of measurement points


34


provided by inductive sensor


10


during the passage of opening


6


B above coil


14


. The inductive sensor provided in this embodiment includes a similar electronic circuit to that described in European Patent No. 0 746 100, this sensor defining a differential relaxation oscillator. The measuring signal provided by such a sensor is representative of a frequency determined by the electronic circuit of this sensor, this frequency varying as a function of the variation in presence of the active material forming plate


6


A above coil


14


. When this coil


14


is facing the active material forming plate


6


A, the frequency has a high value. Conversely, when coil


14


is situated substantially facing opening


6


B, the frequency is low. Curve


32


defines schematically the evolution in the value of the frequency generated in the sensor as a function of the angular position of reference semi-axis


30


of wheel


6


which starts from geometrical axis


8


and passes through the geometrical centre of circular opening


6


B.




It will be noted that curve


32


is substantially symmetrical relative to axis


36


corresponding to the value α=α


ref


. Thus, using an appropriate analysis of the evolution of measurement points


34


as a function of the angular position a of semi-axis


30


passing above or below coil


14


, it is possible to determine which measurement corresponds to the angular position α=α


ref


of semi-axis


30


, i.e. when the latter is substantially identical or superposed with a reference semi-axis RD of sensor


10


which starts from geometrical axis


8


and crosses the magnetic axis of coil


14


, which is parallel to axis


8


and passes substantially through the geometrical centre of coil


14


.




It will be noted that the width of the dip of graph


32


(or the peak in an alternative embodiment of the electronic circuit of sensor


10


) is a function of the profile of opening


6


B and in particular of the angular dimension of this opening. Once opening


68


has passed above coil


14


, thanks to driving means provided and known to those skilled in the art, the measurement of the angular position corresponding to α


ref


can be determined by electronic means which are also known to those skilled in the art. One will cited for example the calculation of the middle point of the width of the dip of curve


32


at a characteristic depth.




Once the angular position of semi-axis


30


has been determined, according to the invention, opening


6


B is brought or left in superposition with coil


14


, or one waits until opening


6


B is superposed with coil


14


to detect the angular position of reference semi-axis


38


associated with wheel


4


, this latter semi-axis


38


starting from geometrical axis


8


and passing through the geometrical centre of opening


4


B provided in plate


4


A. Preferably, opening


6


B has sufficiently large dimensions that spiral coil


14


is mostly above or below opening


6


B, defining an inactive region of plate


6


A, in at least one determined angular position of wheel


6


, namely in the present case when semi-axes


30


and RD are substantially identical to or superposed with each other.




Thus, according to the invention, in order to detect the angular position of reference semi-axis


38


of the plate


4


A further from coil


14


than plate


6


A, the closest opening


6


B to coil


14


is either brought substantially to face said coil, or one waits until it faces said coil. Then, opening


4


B is either brought above coil


14


or one waits until it passes above said coil and, consequently, also above opening


6


B to detect the angular position of semi-axis


38


. In order to do this, a series of measurements similar to those represented in

FIG. 3

are effected and the analysis of the resulting curve similar to curve


34


enables the detection means to determine which measurement corresponds to the angular position α=α


ref


for semi-axis


38


. This series of measurements and the analysis of the resulting curve and made possible by the fact that plate


6


has an inactive region above coil


14


during detection of the passing of opening


4


B above (or below) coil


14


of sensor


10


which responds to a variation in the presence of the active materials constituting plates


4


A and


6


A above or below its detection element by a variation in an oscillation frequency belonging to sensor


10


on which the measurement signal provided by said sensor depends.




It will be noted that, for the second opening


4


B belonging to the plate


4


furthest from detection element


14


, the dip in the measurement curve similar to curve


32


can be defined by a single measurement point, in particular by decreasing the angular dimension of opening


4


B, this opening being able to have in particular the shape of a radial slit. It is possible to determine a lower threshold value for frequency F below which a measurement point indicates that the geometrical axis of the slit is substantially aligned with reference axis RD of sensor


10


. In such a case, the angular position of wheel


4


is directly determined by a single measurement value corresponding to the angular position α


ref


for semi-axis


38


, which is then the same as or superposed with reference semi-axis RD. It will be noted that such a particular case simplifies processing of the measurement results for the detection of the angular position of wheel


4


.




It will be noted however that opening


6


B machined in plate


6


A can have considerably smaller dimensions than those of coil


14


without thereby preventing sensor


10


from detecting the angular position of the reference semi-axis associated with wheel


4


, and thus without departing from the scope of the present invention. However, in such a case, the efficiency of the measurement is decreased, i.e. there is liable to be less contrast in the frequency variation. Theoretically, the minimum condition for the present invention is given by the necessity for the two openings


4


B and


6


B and spiral coil


14


to be superposed with each other in at least one situation, i.e. in at least a first determined angular position of wheel


6


and at least a second determined angular position of wheel


4


. Conversely, in order to assure greater measurement efficiency for sensor


10


, and given the distance between plate


4


and coil


14


, it is preferable for opening


6


B to have dimensions at least comparable to those of coil


14


so that at least most of said coil is situated facing opening


6


B in said at least first determined angular position of wheel


6


.





FIGS. 4 and 5

show a second embodiment of a device according to the invention. This device includes a sensor


10


whose detection element is formed by a spiral coil


14


in the same way as the first embodiment described hereinbefore. The references which have already been described will not be described again here in detail. This second embodiment differs from the first essentially in the arrangement of plates


44


and


46


of coaxial wheels


4


and


6


. Plate


44


has four openings


47


to


50


which define four arms


51


to


54


, arm


54


having a greater width/angular dimension than that of arms


51


to


53


which are substantially the same as each other. Plate


46


also has four openings


55


to


58


arranged at a same distance from geometrical axis


8


as the corresponding openings


47


to


50


of plate


44


. Openings


55


to


58


also define four radial arms


59


to


62


, arm


60


having a greater width/angular dimension than that of arms


59


,


61


and


62


which are substantially identical. The median line of radial arm


54


defines a reference semi-axis


54


A of plate


44


, while the median line of radial arm


60


defines a reference semi-axis


60


A of plate


46


.




In this second embodiment, the passage of arm


60


and


54


respectively is detected in order to detect the angular position of wheel


6


and


4


respectively. In order to do this, the passage of arm


60


and


54


respectively above spiral coil


14


of inductive sensor


10


is detected. Again, the angular position of the plate


46


which is closest to coil


14


is first detected. With reference to

FIG. 6

, several successive measurements


64


are effected during rotation of plate


46


until arm


60


passes above coil


14


. The successive measurements


64


define a substantially symmetrical curve


66


. When one of openings


47


to


50


is situated facing coil


14


, the internal frequency of the oscillator forming sensor


10


corresponds substantially to F


min


. Conversely, when arm


60


is situated facing coil


14


, the frequency increases to a value F


max


.




Given the symmetry of arm


60


and the resulting symmetry of curve


66


, two characteristic parameters can be deduced by an electronic circuit of sensor


10


, namely the angular position corresponding to the middle of the peak generated by the passing of arm


60


in front of coil


14


and the angular width δα half way up the peak, δα=α2−α1. Measurement of δα allows arm


60


to be differentiated from the three other arms


59


,


61


and


62


which each have a lower angular dimension. Detection of arm


60


could possibly be determined by the value of Fmax which will probably be greater during the passing of arm


60


relative to the passing of the three other arms of plate


46


.




Determination of α


ref


allows one to determine when semi-axis


60


A is aligned with reference semi-axis RD of sensor


10


, i.e. when the two semi-axes


60


A and RD are the same or superposed with each other. Thus, while memorizing the time evolution of the rotation of plate


46


, the electronic circuit for detecting the angular positions of wheels


4


and


6


can determine the instantaneous angular position of plate


46


once the moment or the measurement corresponding to the angular position α


ref


of semi-axis


60


A has been determined.




Once the angular position of wheel


6


has been determined, plate


46


is driven in rotation or left so that coil


14


is superposed at least mostly with one of openings


55


to


58


of plate


46


. In another mode for detecting the position of wheel


4


, one waits until coil


14


is situated facing one of openings


55


to


58


to proceed with the detection of the angular position of wheel


4


. Since an opening defines an inactive region for sensor


10


, the latter then detects the passing of the arms of the plate


44


which is furthest from coil


14


. Detection of the passing of radial arm


54


and determination of the angular position of reference semi-axis


54


A corresponding to α


ref


is effected in a similar way to that explained in detail hereinbefore for wheel


6


with reference to FIG.


6


.




Thus, detection of the angular positions of the two coaxial wheels


4


and


6


is effected using a single sensor


10


which, according to the invention, is inductive or capacitive.

FIG. 11

illustrates a capacitive sensor


10


′, the detection element comprising an electrode


14


′ situated at the surface of the substrate


12


. The wheels


4


and


6


and in particular the plates of these wheels are arranged so that there is a variation in capacitance as a function of the presence of an opening or a full or solid portion facing the detection element.




In order to guarantee accurate detection of the angular positions of wheels


4


and


6


, an improvement to the invention proposes effecting a check consisting in bringing or leaving wheel


4


in a position in which coil


14


is superposed at least mostly with one of openings


47


to


50


of plate


44


, then driving plate


46


in rotation so that radial arm


60


passes above coil


14


again effecting a series of measurements allowing the passing of semi-axis


60


A onto the semi-axis RD corresponding to angular position α


ref


to be determined entirely reliably. This measurement may be more accurate than the first effected given that, during the first measurement, the exact angular position of wheel


4


was not known and that it is possible that one of arms


51


to


54


of plate


44


was situated substantially facing coil


14


; which can create a certain asymmetry in the curve which is shown in FIG.


6


and obtained on the basis of successive measurements.




Once the angular position of wheel


6


has been checked, the result of this second detection is kept for the angular position of wheel


6


. Finally, according to an alternative of the detection method according to the invention, it is possible to check again the angular position of wheel


4


having the furthest plate


44


from coil


14


. Given that the angular position of wheel


6


is now known precisely, it is possible to assure that detection of the angular position of wheel


4


is effected when the plate of wheel


6


is angularly positioned so that coil


14


is at least mostly superposed with an opening of plate


46


. It will be noted that such a check proves particularly well advised when checking of the angular position of wheel


6


has shown a difference between the initial detection and the check detection for wheel


6


.





FIG. 7

shows a third embodiment of the invention. Plates


44


and


46


of coaxial wheels


4


and


6


are identical to those shown in

FIGS. 4 and 5

described hereinbefore. This third embodiment differs from the second embodiment in that substrate


12


of sensor


10


which has coil


14


on its upper face is arranged between plates


44


and


46


. In this case, plate


44


is the closest to coil


14


. It will be noted however that substrate


12


can be turned over in an alternative embodiment so that coil


14


is situated under substrate


12


facing plate


46


. The method for detecting the angular position of the two wheels


4


and


6


is similar to that described hereinbefore. The arrangement of this third embodiment can be advantageous given that plates


44


and


46


are situated on either side of flat coil


14


.





FIG. 8

shows a fourth embodiment of the device according to the invention. This device includes three coaxial wheels


4


,


6


and


68


associated with a single same sensor


10


used for the detection of the angular positions of these three coaxial wheels. Wheels


4


and


6


are similar to wheels


4


and


6


of the second embodiment described hereinbefore with reference to

FIGS. 4 and 5

, these two wheels being situated in an identical manner relative to sensor


10


. The third wheel


68


includes a plate


70


parallel to plates


44


and


46


. This plate


70


has the same openings as plates


44


and


46


. Thus, plate


70


also defines four radial arms with one of these arms having a greater width/angular dimension than the others. The openings in plate


70


, two of which


72


and


74


are shown in the cross-section of

FIG. 8

, are arranged radially in an identical way to the openings of plates


44


and


46


.




In the event that the wheels have different diameters and have openings having different radial dimensions from one plate to another, one need only assure that at least one opening of each plate and detection element


14


are superposed one with the others in at least one determined position of the corresponding wheel.




Detection of the angular positions of wheels


4


and


6


is performed in a similar way to that described within the scope of the second embodiment. The same is true for wheel


68


the arrangement of which relative to sensor


10


is similar to that of wheel


6


of the third embodiment described with reference to FIG.


7


. It will be noted however that plate


46


is the closest to coil


14


, while plate


44


is the furthest from said coil


14


.




Thus, according to the method for detecting the position of the three coaxial wheels according to the invention, the angular position of wheel


6


is first detected as previously described, then plate


46


is brought or left in an angular position in which coil


14


is mostly superposed with an opening of plate


46


. Then, the angular position of wheel


68


whose plate


70


is situated below coil


14


, at a smaller distance than that of plate


44


, is determined. Once the reference semi-axis of plate


70


has been detected and thus the angular position of wheel


68


has been determined, plate


70


is brought or left in an angular position in which coil


14


is superposed with an opening in plate


70


, in particular with opening


74


. Finally, the angular position of wheel


4


is detected by sensor


10


, plate


46


being still in an angular position in which coil


14


is superposed with an opening of plate


46


. Preferably, the opening of plate


70


situated facing coil


14


during detection of the angular position of wheel


4


also has sufficient dimensions for most of coil


14


to be superposed with this opening in at least one determined angular position of wheel


68


. Plate


70


of wheel


68


is formed of an active material for sensor


10


, like plates


44


and


46


.




A check can be made of the angular positions of the three coaxial wheels starting with the closest plate to coil


14


up to the furthest plate, in the same way as the case with two wheels described hereinbefore. In order to do this, the other plates are brought or left in angular positions in which coil


14


is above or below an opening of each of the other plates, or one waits until the device is in such a situation.





FIG. 9

shows a variant of the plate of wheel


4


,


6


and


68


respectively. This plate


80


has three openings


81


,


82


and


83


forming annular sectors separated by three material parts also defining three angular sectors. Thus, the radial edges of openings


81


to


83


and the intermediate material portions define radial segments of plate


80


. By way of example, the two radial segments


86


and


88


respectively define two reference semi-axes


90


and


92


of plate


80


. Each of the these two reference semi-axes can be detected by the detection means using successive measurements


94


defining an S shaped curve


96


shown in FIG.


10


.




During passing from a full or solid portion to opening


83


or from this opening


83


to a full or solid portion of plate


80


above flat coil


14


, the frequency of the oscillator of sensor


10


passes from F


min


to F


max


or vice versa according to the arrangement of the electronic circuit defining the oscillator of sensor


10


. The alignment of reference semi-axis


90


and


92


respectively with reference semi-axis RD of sensor


10


, corresponding to reference angle α


ref


, corresponds to the middle point of S shaped curve


96


. α


ref


corresponds to a resonance frequency F


ref


.




Thus, when the frequency of the oscillator corresponds to F


ref


, the alignment of a radial edge of an opening


81


to


83


with semi-axis RD is detected. In the case of plate


80


, it is also necessary to determine the angular widths between two transitions. Given that only opening


83


defines an angle of 90°, and providing that the direction of rotation of plate


80


is known, it is possible to determine univocally the angular position of semi-axis


90


and


92


respectively. Moreover, given that the three radial arms separating the openings do not all have an identical angular width, semi-axis


90


and


92


respectively can be univocally detected without also requiring the other semi-axis to be detected.




It will also be noted that plate


80


defines a plurality of reference semi-axes at least six of which can be reliably and efficiently exploited.



Claims
  • 1. A horological device of small dimensions, 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, wherein said means for detecting the angular positions of said first and second semi-axes are formed by a single inductive sensor provided with an element for detecting the presence of at least one active material above or below said element, said first plate including at least one first inactive region for said sensor, said first and second plates being formed at least partially of said at least one active material 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.
  • 2. A device according to claim 1, wherein said sensor responds to a variation in the presence of an active material above or below said detection element by a variation in at least one parameter or in a variable of said sensor on which a measurement signal provided thereby depends, said first inactive region having dimensions provided so that said detection element is at least mostly facing said first inactive region in said determined angular position.
  • 3. A device according to claim 1, wherein said first inactive region is defined by a first opening provided in said first plate.
  • 4. A device according to claim 3, wherein said first and second plates are formed by active materials for said sensor, the second plate having at least one second opening, said detection element being arranged so that it is at least partially above or below said second opening in at least one determined angular position of said second wheel.
  • 5. A device according to claim 4, wherein said first and said second semi-axis is defined by a radius starting from said geometrical axis of rotation and either passing substantially through the geometrical center of said first and said second opening, respectively, or defined by a radial edge of said first and said second opening, respectively, or identical to a median line of a portion made of said at least one active material of said first and said second plate extending radially between two inactive regions of said first and said second plate, respectively.
  • 6. A device according to claim 1, wherein said sensor includes a support at the surface of which is arranged said detection element, said support being arranged facing said first plate, said second plate being situated on the other side of said first plate relative to said support, said sensor being arranged to detect the presence above said detection element of the active material at least partially forming said second plate when said first wheel is in said determined angular position.
  • 7. A device according to claim 1, wherein said sensor includes a support at the surface of which is arranged said detection element, said support being arranged between said first and second plates, said detection element being situated facing said first plate.
  • 8. A device according to claim 7, further including a third wheel which is coaxial to said first and second wheels and including a third plate perpendicular to said geometrical axis of rotation, said third wheel defining a third reference geometrical semi-axis whose angular position can be detected by said inductive sensor, said third plate being situated on the other side of said first plate relative to said support of said sensor and being at least partially formed of said at least one active material , said sensor being arranged to detect the presence above or below said detection element of said at least one active material at least partially forming said third plate when said first wheel is in said determined angular position.
  • 9. A device according to claim 8, wherein said second plate includes at least one second inactive region for said sensor, arranged so that said detection element is at least mostly above or below said second inactive region in at least one determined angular position of said second wheel.
  • 10. A device according to claim 8, wherein said third plate is formed by an active material and has a third opening, said detection element being arranged so that it is at least partially above or below said third opening in at least one determined angular position of said third wheel, said third semi-axis being defined by a radius starting from said geometrical axis of rotation and either passing substantially through the geometrical centre of said third opening, or defined by a radial edge of said third opening, or identical to a median line of a part made of active material of said third plate extending radially between two inactive regions of said third plate.
  • 11. A method for detecting the angular positions of N coaxial wheels, N being greater than 1, by means of a single inductive sensor, said N wheels respectively including N plates each having at least one inactive region for said sensor which includes a detection element of at least one active material at least partially forming each of said N plates, said detection element and each of said inactive regions being arranged so that they are superposed with each 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 in 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 into or leaving said inactive regions of wheel No. 1 in 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.
  • 12. A method according to claim 11, further including the following successive steps of:E) Bringing into or leaving inactive region No. 2 in the event that N=2, respectively the inactive regions of wheels Nos. 2 to N in the event that N is greater than 2 in superposition with said detection element, or waiting until said inactive region, respectively said inactive regions and said detection element are superposed with each other; F) Checking the angular position of said semi-axis of wheel No. 1, and keeping the angular position resulting from this check in the event that it does not correspond to the angular position measured during step A; G) Performing in ascending order for each wheel No. 2 to (N−1), if required, a check of the angular position of the semi-axis associated with said wheel after having brought into or left the inactive regions of the other wheels in superposition with said detection element, or having waited for said inactive regions and said detection element to be superposed with each other, and keeping the angular position resulting from this check for each wheel No. 2 to (N−1) in the event that it does not correspond to the angular position measured during step C).
  • 13. A method according to claim 12, further including a final step of:H) Checking the angular position of the semi-axis associated with wheel No. N after having brought into or left said inactive region in the event that N=2, respectively the inactive regions Nos. 1 to (N−1) in the event that N is greater than 2, in superposition with said detection element, or having waited for said inactive region, respectively said inactive regions and said detection element to be superposed with each other, this step being performed preferably if the step(s) for checking the angular position(s), of wheel 1, respectively wheels 1 to (N−1), have shown at least one erroneous detection during steps A) to C).
  • 14. A horological device of small dimensions, 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, wherein said means for detecting the angular positions of said first and second semi-axes are formed by a single capacitive sensor provided with an element for detecting the presence of at least one active material above or below said element, said first plate including at least one inactive region for said sensor, said first and second plates being formed at least partially of at least one active material 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.
  • 15. A method for detecting the angular positions of N coaxial wheels, N being greater than 1, by means of a single capacitive sensor, said N wheels respectively including N plates each having at least one inactive region for said sensor which includes a detection element of at least one active material at least partially forming each of said N plates, said detection element and each of said inactive regions being arranged so that they are superposed with each 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 in 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 into or leaving said inactive regions of wheel No. 1 in 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.
Priority Claims (1)
Number Date Country Kind
1382/98 Jun 1998 CH
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4084403 Kitai et al. Apr 1978
4196579 Schaefer Apr 1980
4238781 Vercellotti et al. Dec 1980
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4645357 Allgaier et al. Feb 1987
5202858 Kanzaki Apr 1993
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Number Date Country
38 28 810 A Mar 1990 DE
195 24 030 C Nov 1996 DE
WO9745705 Dec 1997 WO