Method for determining axial displacement or axial position of shaft of electronic control device

Abstract

The invention relates to a method for determining an axial displacement or an axial position of a magnetization axis of an electronic control device (1), such as a setting rod (3) of a timepiece. The method is based on a new function obtained by multiplying the norm of the magnetic field generated by the axis of magnetization by a selected compensation function which depends only on the angle of rotation of the axis in a plane orthogonal to the axis of rotation of the axis. The main advantage of introducing the compensation function is that it allows to simplify the processing of the measurement and strongly minimize the necessary memory resources, since there is no need to store a large number of different curves corresponding to different angular positions, which should be necessary by directly using the norms for determining the axial displacement / position. By applying the proposed method using said new function, the axial displacement / position of the shaft can be detected in a sufficiently accurate manner by preferably using a single magnetic sensor.

Description

Technical Field

[0001] The present invention relates to a method for determining the axial displacement or axial position of an axis of an electronic control device. The axis can be, for example, a setting lever of a timepiece. The present invention focuses on a magnetic crown lever associated with an electronic control module including a magnetometer, wherein the magnetic field of a magnet attached to the lever is measured in order to determine the axial position / displacement of the lever. The present invention also relates to a device configured to perform the method. Background Art

[0002] In a first type of electronic crown lever, the axial position of the lever is typically determined by electrical contacts that are closed or opened at stable mechanical positions of the lever (referred to as T1, T2, and T3), where T1 refers to the rest position, T2 refers to the date setting position, and T3 refers to the time setting position. If the electronic control device also allows the lever to operate as a push button, then an additional position T0 is defined, which refers to the position at which the crown is pressed and the lever makes contact with the end electrical contact. These electrical contacts are mechanically actuated by a number of relatively complex components in contact with the lever.

[0003] In a particular electronic control device equipped with a magnet for detecting the rotation of the crown lever, the magnet forms a sliding member so as to maintain its axial position when the lever moves. The sliding member has a central hole with a square profile, and the lever includes at least a portion having a corresponding square cross-section that passes through the square hole, whereby the magnet is rotationally driven by the lever. The main drawback of the solution described above is the need for as many electrical contacts as there are stable positions of the lever. The electrical contacts must not be subject to oxidation over time and must be shock resistant. Furthermore, the number of mechanical components is high, and their assembly is relatively complex and expensive.

[0004] In a second type of electronic crown lever with a magnetic system, the magnet is attached to the lever and moves axially and rotationally with the lever. The rotation of the lever is detected in the position T1 using a magnetometer. Pressing the crown activates an end switch (position T0). The crown lever is thus used as a push rod, and when the switch is pressed, it can be determined that the crown lever is in the position T0. It often happens that when the crown is pressed to activate the switch, the lever rotates involuntarily, while the rotation of the lever is still detected by the magnetometer. This involuntary rotation may be interpreted by the watch as an action to be taken (e.g., changing the selected item of the displayed menu) before pressing the switch (for verification of entering the selected item).

[0005] European patent EP 3210083 B1 relates to a method for detecting the angular position of a magnet fixedly mounted on a control rod, the magnet being radially magnetized. The detection of the axial position of the magnet is only very briefly mentioned and not explained. The method proposed in EP 3210083 B1 is based on the measurement of three magnetic field components of the magnetic field generated by the magnet, the magnetic field vector being described as elliptical, as shown in Figure 1 for different axial positions of the magnet and for a full rotation. When these ellipses are projected onto a two-dimensional (2D) plane (X-Y), the resulting 2D curves remain elliptical, as shown in Figure 2 . In order to accurately determine the angular position of the control rod, a circular curve is alternatively required in the X-Y plane. For this purpose, a given transformation matrix is used to project the magnetic field vector onto the two-dimensional (2D) plane X-Y. However, as can be seen in Figure 3 , for a preselected transformation matrix, the projection is described as circular only for a given axial position of the magnet / rod. The projections for other axial positions are described as elliptical. Although not mentioned in EP 3210083 B1, we can assume the radii of the two circles shown in Figure 3 of this patent document for detecting axial displacement / position (the radii decrease as the rod decreases and thus the magnet moves away from the magnetic sensor / magnetometer). However, as mentioned, we observe that a circular shape is obtained only for a given axial position with a preselected transformation matrix. Therefore, for all other axial positions, firstly there is an inaccuracy in detecting the rotational angle value of the rod, and secondly the length of the projected measured magnetic field vector does not provide an accurate axial position as it also depends on the rotational angle, such a vector being described as elliptical by varying the rotational angle over 360°. Thus, as long as the axial position of the rod is not known, it is not possible to correctly determine the axial position of the rod and furthermore it is not possible to accurately determine the angular position of the rod. Therefore, the method proposed in document EP3210083B1 for determining the axial position is firstly unclear and not explained in detail. Further, the teachings of this patent document leave the person skilled in the art without means for efficiently and accurately measuring the axial position of the magnet, in particular a bipolar magnet and thus of the rod. SUMMARY OF THE INVENTION

[0006] An object of the present invention is to overcome at least some of the above disadvantages of the existing solutions for magnetizing control rods or shafts. The object of the present invention is thus to provide a solution for determining the axial displacement or axial position of the shaft of an electronic control device such as the crown rod arrangement of a watch.

[0007] According to a first aspect of the present invention, there is provided a method for determining the axial displacement or axial position of an axis of an electronic control device or a control value for a given function or operation depending on the axial displacement or axial position of the axis, as recited in claim 1.

[0008] The present invention has the following advantages: it makes it possible (when the present invention is applied to a watch) to detect the axial displacement or axial position of the crown stem with a relatively high level of certainty and without using electrical contacts and corresponding mechanical components.

[0009] In a particular mode, the present invention allows the detection of the axial displacement or axial position of the axis to be used to prevent the detection of or to ignore the rotation of the axis, to avoid involuntary actions related to the rotation of the axis, or to adjust the intensity of the functions of an electronic watch.

[0010] The software implementation in a microcontroller or digital signal processor for determining the axial displacement or axial position of the stem is relatively simple. Further, most magnetometers have three measurement axes, which thus makes it possible to use these magnetometers according to the present invention for the determination of axial displacement without generating additional costs due to the addition of sensors dedicated only to measuring axial displacement.

[0011] According to a second aspect of the present invention, there is provided an electronic control module as recited in claim 12 for determining the axial displacement or axial position of an axis of an electronic control device. According to a third aspect of the present invention, there is provided a timepiece including the electronic control module. Other aspects of the present invention are described in the dependent claims appended hereto. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] With reference to the accompanying drawings, other features and advantages of the present invention will become apparent from the following description of non-limiting exemplary embodiments, in which:

[0013] - Figure 1 It has been described, according to EP 3210083 B1, which shows the measurement of the 3D components of a magnetic field as a function of the rotation angle of a bipolar magnet (the bipolar magnet having a radially magnetized axis (two magnetic poles radially opposite)) and the axial position of the magnet;

[0014] - Figure 2 It has been described, according to EP 3210083 B1, which shows the measurement of the 2D components of a magnetic field as a function of the rotation angle of a bipolar magnet and the axial position of the magnet;

[0015] - Figure 3has been described, according to EP 3210083 B1, which shows the 2D components of the magnetic field projected onto the plane for z = 0.0 as a function of the rotation angle of the bipolar magnet and the axial position of the magnet in the X-Y plane by using a transformation matrix;

[0016] - Figure 4 An example of an electronic control device according to the invention is illustrated in an isometric view;

[0017] - Figure 5 Shows the value of the x-component of the magnetic field as a function of the rotation angle of the setting lever and the axial displacement / position of the setting lever in the electronic control device for Figure 4 ;

[0018] - Figure 6 Shows the value of the y-component of the magnetic field as a function of the rotation angle of the setting lever and the axial displacement / position of the setting lever in the electronic control device for Figure 4 ;

[0019] - Figure 7 Shows the value of the z-component of the magnetic field as a function of the rotation angle of the setting lever and the axial displacement / position of the setting lever in the electronic control device for Figure 4 ;

[0020] - Figure 8 Shows the value of the norm of the magnetic field as a function of the axial displacement / position and the rotation angle of the setting lever in the electronic control device for Figure 4 ;

[0021] - Figure 9 Shows compensation functions, each compensation function depending on the rotation angle of the setting lever, compensating for the dependence of the magnetic field norm on the rotation angle for three different axial positions;

[0022] - Figure 10 Shows the values of the function G(z,θ) equal to the magnetic field norm multiplied by a single selected compensation function, which is used in the first mode of the invention to select the relationship between the possible values of these functions and the corresponding axial displacement / position of the setting lever for all possible rotation angles of the setting lever in the electronic control device for Figure 4 ;

[0023] - Figure 11 Shows the values of the function G(z,θ) equal to the magnetic field norm multiplied by another single selected compensation function, which is used in the second mode of the invention to select the relationship between the possible values of these functions and the corresponding axial displacement / position of the setting lever for all possible rotation angles of the setting lever in the electronic control device for Figure 4 ; and

[0024] -Figure 12 is a flow chart summarizing the steps of the proposed method. Detailed implementation mode

[0025] Next, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The present invention will be described in the context of detecting the axial displacement or axial position of the shaft of an electronic control device of a timepiece, where the shaft in this example is a setting lever associated with the outer crown of the electronic control device. The electronic control device described below includes at least a crown, a setting lever, a magnetic element integrally mounted on the lever, and an electronic control module formed by a magnetometer and a signal processor. In this configuration, a magnetic field is generated by the magnetic element of the rotating lever. However, the teachings of the present invention are not limited to this environment or application.

[0026] Same or corresponding functional and structural elements that appear in different drawings are assigned the same reference numerals. As used herein, "and / or" means any one or more of the items in the list connected by "and / or". As an example, "x and / or y" means any element of the three-element set {(x), (y), (x, y)}. In other words, "x and / or y" means "either x or y or both". As another example, "x, y and / or z" means any element of the seven-element set {(x), (y), (z), (x, y), (x, z), (y, z), (x, y, z)}. In other words, "x, y and / or z" means "one or more of x, y and z". Further, the term "comprising" is used herein as an open-ended term. This means that the object covers all the listed elements, but may also include additional unnamed elements. Therefore, the term "comprising" is interpreted by the broader meanings "including", "containing" or "comprising".

[0027] In this description, a magnetic field is a vector field that describes the magnetic influence of an electric current and a magnetized material. The term "magnetic field" is sometimes used for two distinct but closely related fields denoted by the symbols B and H. H is measured in amperes per meter, while B is measured in teslas (equivalent to newtons per meter per ampere). H and B differ in how they account for magnetization. In a vacuum, B and H are the same except for the units, but in a magnetized material, they differ due to the magnetization M of the material. In the following description, the magnetic field is expressed as B, but H can be used interchangeably.

[0028] Figure 4An example of an electronic control device 1 in which the teachings of the present invention can be applied is shown. A rotatable element or shaft 3 is shown, which in this example is the setting stem of a timepiece such as a wristwatch. The stem 3 defines a rotational axis 5, which coincides with the center or longitudinal axis of the stem 3. Such a setting stem is also known as a crown stem. Thus, for example, the rotatable element 3 (i.e., the stem) in this example will be a small, slender workpiece having a diameter in the range of 0.5 mm to 1 mm. The stem 3 is provided with a magnet 7, which is assembled with the stem such that it is integral with the stem in terms of rotation and axial displacement at its inner end region (i.e., in the case where the setting stem is terminated by a crown, at the end of the setting stem opposite the crown and located in the timepiece housing). The magnet is configured as a ring through which the stem passes in this example. The magnet 7 is preferably a bipolar permanent magnet with radial magnetization, the two magnetic poles being radially opposite with respect to the rotational axis 5, hereinafter referred to as a "bipolar magnet" or simply a "magnet".

[0029] The stem 3 and thus the magnet 7 have only two degrees of freedom, one of rotation about the rotational axis 5 and the other of translation along the rotational axis 5. The rotational angle of the magnet and thus the stem is denoted by θ, and the axial displacement / position of the magnet and thus the stem is denoted by z along the rotational axis.

[0030] A magnetometer 9 mounted on a circuit board 11, in particular a printed circuit board (PCB), measures the magnetic induction field of the magnet along three orthogonal axes X, Y, and Z that form the reference system of the magnetometer, namely B x 、B y and B z . The Z axis is parallel to the stem and thus the rotational axis 5 of the magnet, such that the plane X - Y is perpendicular to the rotational axis 5. In this example, the center of the magnetometer located at the origin of the reference system defines the zero position (z = 0) for the bipolar magnet 7 and thus for the stem along the rotational axis; that is, the intersection of the X - Y plane with the rotational axis 5 defines the zero axial position (z = 0) for the magnet and thus for the stem 3. An optional switch 13 is also provided, which is used in this example to selectively enable and disable the magnetometer and / or activate selected functions of the timepiece.

[0031] The magnetic field lines generated by the magnet 7 act on the magnetometer 9, which is a triaxial sensor device that measures the incident magnetic field along three measurement axes (i.e., the X, Y, and Z axes). The magnetometer 9 can be, for example, a micro - surface - mount device SMD that is fitted onto the PCB 11 and connected to the PCB via micro - surface - mount device (SMD) connections.

[0032] In this example, the magnetometer 9 is a Hall effect sensor device, and a Hall effect sensor device is a device for measuring the magnitude or intensity of a magnetic field. The output voltage of a Hall sensor is directly proportional to the magnetic field strength passing through it. The magnetometer 9 is arranged to determine a first magnetic field component B along a first axis (which is the X axis in this case) x of the intensity, a second magnetic field component B along a second axis (which is the Y axis in this case) y of the intensity, and a third magnetic field component B along a third axis (which is the Z axis in this case) z of the intensity. In this example, these three axes are orthogonal to each other. A temperature sensor (not shown in the figure) may additionally be provided to measure temperature. The temperature sensor (if provided) may be integrated in the magnetometer 9, for example. The behavior of Hall sensors typically depends on the temperature under which they operate. It should be noted that the system does not include a three-axis magnetometer, but it may include, for example, three independent magnetic field sensors, each magnetic field sensor being configured to measure a different magnetic field component B x 、B y and B z in the magnetic field components. In this case, all three sensors may or may not be in the same plane.

[0033] The method for determining the axial displacement or axial position of the magnet 7 and thus the rod 3 along the rotation axis 5 according to the present invention is based on the measurement of the components B x 、B y and B z of the magnetic induction field. These magnetic field components depend on the rotation angle θ of the bipolar magnet and also on the position of the magnet along the rotation axis 5 parallel to the Z axis but away from the rotation axis. It should be noted that the symbol θ is used interchangeably in this description to refer to both the rotation angle of the magnetic field (and thus the magnet 7) and the rotation angle of the rod 3. In Figure 5 、 Figure 6 and Figure 7 can be seen the values of the magnetic field components B x 、B y and B z as a function of the rotation angle θ of the magnet for three different axial displacements / positions z = 0.0 mm, z = 0.5 mm, and z = 1.0 mm. The magnetic field components are compensated for the hard iron coefficient in order to remove the effects attributed to parasitic magnetic fields and possibly due to temperature variations. In other words, the main operations of the compensation are as follows: eliminating the offset due to the manufacturing of the Hall sensors; removing the distortion due to the presence of parasitic fields, especially generated by the circuit board carrying the magnetometer; and possibly further eliminating the effect of temperature. Figure 5 、 Figure 6 and Figure 7Shows the values of the compensated magnetic field components.

[0034] Viewed independently, these components are not sufficient to detect the axial displacement or axial position of the magnet. Additionally, component B z Has two zero crossings as the magnet rotates. However, if we take the norm of the magnetic field (in this example, the Euclidean norm), i.e.,

[0035]

[0036] Then we obtain interesting behavior, namely that its value decreases as the magnet 7 moves away from the magnetometer 9 along the axis of rotation. Further, the value of the norm is never zero. This is shown in Figure 8 In practice, and for reasons of computational savings, the square root is generally not calculated, and the square of the norm is used. However, in this example, the norm is calculated and used.

[0037] In Figure 8 It can be seen that the value of the norm depends not only on the axial displacement / position but also strongly on the rotation angle θ. To avoid or minimize this angular dependence, the method introduces a first function F(θ), which is also called the compensation function, and which depends only on the rotation angle / angle position θ. In other words, the value of the selected compensation function does not depend on the axial displacement / position. The compensation function is chosen such that when the norm of the magnetic field is multiplied by the compensation function, we obtain a second function G(z,θ), which depends mainly on the axial position of the axis (rod) and less or not at all on the rotation angle of the axis:

[0038]

[0039] This second function G(z,θ) is shown for two different specific compensation functions along the axis of rotation 5 (where z is used as the variable along the axis of rotation parallel to the Z axis) in Figure 10 And Figure 11 Where the lower curve and the upper curve are shown, which are defined by the second function G(z,θ) for all angular positions θ, or in other words, the envelope of all possible curves of G(z,θ) results from the dependence on the angular position θ for this second function. Two different specific compensation functions will still be described later in this description. In these figures, we can see that the spread of the second function G(z,θ) for all rotation angles / angle positions is much smaller than the corresponding spread for the norm.

[0040] The method further proceeds to a second function G(z, θ), since it allows for determining the axial displacement or position z of the magnet 7 / rod 3 with sufficient accuracy for several applications by selecting only one specific compensation function F(θ) (referred to as the "compensation function") for each specific application. The main advantage of introducing the compensation function is that it allows for simplifying the processing of the measurement and strongly minimizes the necessary memory resources, since it is not necessary to store a large number of different curves corresponding to different rotation angles / angle positions, which would have been required due to the direct use of the norm for determining the axial displacement / position (see Figure 8 ).

[0041] The preferred individual compensation function F z (θ) is graphically represented for axial positions z from 0.0 mm (the individual compensation function with the highest amplitude) to 1.0 mm (the individual compensation function with the lowest amplitude) in Figure 9 , where we can see that these individual compensation functions somewhat depend on the axial position. Between the two extreme compensation functions (corresponding to z = 0.0 mm and z = 1.0 mm, respectively), a specific compensation function F m (θ) representing the average / median over all individual compensation functions for each angular position at the axial position z for a given position range from 0.0 mm to 1.0 mm is shown. Thus, the function F m (θ) corresponds to the average compensation function or to the median compensation function.

[0042] Depending on the axial position z and the angular position θ, the preferred individual compensation functions are all defined by a general compensation function F G (z, θ):

[0043]

[0044] However, the axial position is not known before the method is carried out as defined, and the method is indeed implemented for determining the axial displacement / position of the magnet / rod. Thus, the method of the present invention advantageously selects a single specific compensation function F(θ) based on the preferred general compensation function F Figure 9 represented in G (z, θ) (representing the two extreme compensation functions F z (θ) for z = 0.0 mm and z = 1.0 mm, with all other preferred individual compensation functions lying between them).

[0045] A single specific compensation function (referred to as the "compensation function") has an amplitude specific to each electronic control device of the present invention. According to a preferred implementation of the present invention, a single specific compensation function F(θ) is selected in relation to the application for which the axial displacement / position determination method is implemented. For example, if the method is used to detect the unique axial displacement / position of a rod according to a first mode, such as stable positions T1, T2, and T3, then an average / median compensation function F m (θ) can be advantageously selected. This compensation function is:

[0046] The average or median over z

[0047] This means that for the first mode, we take the average or median value (shown by the solid line in Figure 9 ) in order to minimize the deviation over the entire displacement / position range (z = 0.0 to 1.0 mm) in the corresponding second function G(z,θ) due to the angular position, as can be seen in Figure 10 . In this Figure 10 , by selecting the average / median compensation function F m (θ) for the compensation function F(θ), the curve UC1 is the upper limit and the curve LC1 is the lower limit for the second function G(z,θ) as a function of the axial position z. Based on these upper and lower curves UC1 and LC1, the method establishes / selects the relationship between the value g of G(z,θ) and the axial position z for all angular positions θ. Generally, the method selects the relationship or / and control value between a first set of possible second values and a second set of possible axial displacements or axial positions, and establishes the corresponding axial displacement or axial position of the axis or the range of the corresponding axial displacement or position of the axis or the corresponding control value for each second value of the first set.

[0048] In Figure 10In the examples provided, for the positive values of the axial position z around the three corresponding unique stable axial positions T1, T2, and T3 that the rod can have, three position ranges R1, R2, and R3 are defined. By taking into account the manufacturing tolerances of the various components that make up the electronic control device and also the tolerances resulting from the assembly of these components, the position ranges R1, R2, and R3 are selected to cover all possible positions with sufficient margin and without overlap for the corresponding axial positions T1, T2, and T3. Note that each range Rn (n = 1, 2, 3) corresponds to a range Pn that includes all possible values g of the second function G(z, θ) for that range Rn, n = 1, 2, 3. Conversely, the range Rn (n = 1, 2, 3) does not include all possible values z of the corresponding range Pn of G(z, θ). The selected relationship advantageously defines a unique non-overlapping range Pn of g values for the corresponding axial position ranges Rn of the axial positions. In other words, the ranges Pn of the second values are unique such that the ranges of the second values do not overlap with another range. This is shown in Figure 10 which. Thus, for any possible second value, there is only one position range Rn and the corresponding axial position Tn.

[0049] On the other hand, according to the second mode, if a displacement / position determination method is used to detect the axial displacement of the rod 3, for example, in the direction of the position T0 starting from the position T1, so that the determination of the rotation angle of the rod 3 is disabled or ignored when the rod is pressed by the user, then a different compensation function can be selected. For example, if different menus are displayed by rotating the rod at a given position of the rod (which will typically be the non-pressed position of the rod), and the pressing of the rod at a second position of the rod (which will typically be the pressed position of the rod) is used to select a given function or enter a menu, then this operation is particularly useful. In this example, the user may inadvertently rotate the rod while pressing the rod, which will then result in different menus unless the rotation detection is disabled or ignored. In this case, the compensation function F(θ) can be defined as follows, where we take z = P to be more accurate at the start of the displacement from the axial position P, so as to be able to determine the pressing of the rod in its initial stage:

[0050]

[0051] If the pressing function is intended to start from the axial position T1 (around z = 0), then we introduce z = 0 in the above compensation function, as shown in Figure 11 which. By selecting the compensation function F p (θ) with P = 0 for the compensation function F(θ), the curve UC2 is the upper limit and the curve LC2 is the lower limit for the second function G(z, θ) as a function of the axial position z. We can select a threshold g for G(z, θ)Th , below which the detection of the rotation of the rod shall no longer be considered. This is illustrated in Figure 11 , which shows the negative position values along the axis of rotation. In other words, a threshold g is defined for G(z,θ) Th , and the method includes: when the value g of G(z,θ) is less than or equal to the threshold, disabling or ignoring the determination of the rotation angle of the shaft / rod 3.

[0052] Thus, as explained, the compensation function can advantageously depend on the use or application of the displacement or position determination method.

[0053] Once the compensation function F(θ) has been selected and once the current rotation angle θ of the rod has been measured, then the value of the second function G(z,θ) can be calculated. It should be noted that the rotation angle can be measured or determined by following the teachings of EP3705902A1. As explained in EP3705902A1, based on two of the magnetic field components orthogonal to the axis of rotation, namely the components B x , B y , the current rotation angle value of the rod in the plane orthogonal to the axis of rotation of the shaft is determined. When the current rotation angle θ c has first been applied to the compensation function F(θ), then the value of G(z,θ) can be calculated by multiplying the norm N c of the measured magnetic field by the value g c of the compensation function.

[0054] The compensation function is selected such that the value g of G(z,θ) mainly depends on the axial position z of the shaft and relatively little or not at all on the rotation angle θ of the shaft. The upper and lower curves represent the uncertainty for any value g of the axial displacement / position.

[0055] In summary, if the proposed method is used to detect stable mechanical positions (first mode), such as positions T1, T2, and / or T3, then a set of non - overlapping ranges for the values P1, P2, and P3 of the second function G(z,θ) can be defined, corresponding to these stable positions of the rod including possible errors / misalignments, as further illustrated in Figure 10 . In the case of preventing rotation detection (second mode), we select a threshold g Th for G(z,θ), below which the value of the angle shall no longer be considered. This is illustrated in Figure 11 .

[0056] Figure 12The flowchart summarizes the above method for determining the axial displacement or axial position of a rod that is at least partially magnetized in an electronic control device. In step 101, the first, second, and third magnetic field components of the magnetic field are measured by a magnetometer 9, which are orthogonal to each other in this case. This step typically includes a step of compensating the magnetic field components to account for the hard iron coefficients. In step 102, the current rotational angle value θ of the rod 3 in a plane orthogonal to the rotational axis 5 of the rod is determined based on at least two of the magnetic field components orthogonal to the rotational axis. c (Current angular position). In step 103, the current norm N of the magnetic field, either squared or non-squared, is calculated based on the first, second, and third magnetic field components c : The norm depends on the axial displacement of the shaft along the rotational axis and the rotational angle of the shaft.

[0057] In step 104, a first function F(θ), called a compensation function, is selected at least for a mode / application (e.g., for the first and second modes described previously), and in such a case, an appropriate function is selected for the current mode (detection of the axial position among a set of possible stable axial positions or detection of the activation of a push-button function). The selected compensation function depends on the rotational angle of the shaft and not on the axial displacement of the shaft. In step 105, for the current rotational angle value θ, a first value V, called the compensation function value, is determined by applying the current rotational angle value to the selected compensation function c : V c : c = F(θ c ). The obtained value V c is stored in the memory of the electronic crown module.

[0058] In step 106, a second value of the second function described previously is calculated by multiplying the calculated norm of the magnetic field by the determined compensation function value: g c = N c · V c . According to the invention, the compensation function is selected such that the second function depends mainly on the axial position of the shaft and relatively little or not at all on the rotational angle of the shaft. In particular, the compensation function is defined such that the bundle of the second function G(z,θ) (e.g., as shown in Figure 10 and Figure 11 ) is narrow enough so that G(z,θ) can provide a relatively good approximation for the axial position z for all θ, and thus allows the position z to be determined with a relatively low margin of error, so that in particular, it is possible to clearly distinguish between given distinct positions (T1, T2, T3), or to determine whether the rod 3 has been pressed beyond a specific threshold D that activates the permitted function Th, for example to prevent untimely selection of functions in the menu via rotation of the stem. In practice, the present invention relies on the extreme curves, i.e., the upper curve and the lower curve, for positions T1, T2, and T3 within their error margins. For the detection of a press, the present invention generally relies on the lower curve. Given a value of g less than a given threshold g Th for the value of g, it can be concluded that the stem has been pressed by at least the corresponding displacement value D given by this lower curve Th .

[0059] In step 107, a relationship or / and control value between a first set of possible second values and a second set of possible axial displacements or axial positions is selected, and for each second value of the first set, a corresponding axial displacement or axial position of the shaft or a range of corresponding axial displacements or positions of the shaft or a corresponding control value is established. The control value is related to the adjustment of the function or operation of the timepiece. More specifically, in this example, the control value can provide an intensity adjustment depending on the axial displacement or axial position of the shaft for the function of the timepiece. Note that the second function G(z) may not be used directly, but the present invention can simply use the range (envelope) defined by the lower curve and the upper curve, i.e., g -> Rz, where Rz is the range of possible axial positions for a given value g of the second function G(z). Thus, the relationship between g and z is selected, rather than necessarily a function that defines a single value of z for each g. Further, for the mode of detection linked to a press on the stem having at least its specific displacement, the algorithm does not determine the axial displacement z based on the obtained g c value, but directly determines the command for the function based on the current value of g c There is an implicit link to the axial position of the stem, but in this case, the algorithm operates such that there is no specific step of determining the axial displacement z before the action.

[0060] In step 108, the calculated second value g c is applied to the selected relationship between the first set and the second set to determine the axial displacement or axial position z c of the shaft or the control value with respect to the sensor arrangement (9).

[0061] The data processing steps of the method described above can be performed by a digital signal processor (DSP), and it is thus a computer-implemented processing step. The DSP can be a component of a magnetometer, or it can be an independent device. The DSP can also include a memory, or an independent memory unit can be used to store, for example, different functions and measurement values.

[0062] The solution proposed by the present invention thus makes it possible to detect the axial displacement or axial position of the stem without electrical contact and in an analog manner. If the magnetometer 9 and the angle determination algorithm operate during the movement of the stem 3, the angle of the crown and thus the axial position can be known accurately enough to unambiguously determine a specific axial position or range of axial positions determined using a single electronic component configured to perform the necessary calculations. It is thus possible to detect the adjustment positions T1, T2 and T3 (for the first mode) in particular by eliminating the mechanical complexity of electrical contacts. With regard to the second mode, it may happen that when the crown is pressed to reach T0 to thereby verify the operation or enter a menu, a slight rotation of the crown generates an angular increment sufficient to involuntarily change the menu in the watch. By monitoring the axial position of the crown according to the method of the present invention, it is possible to prevent or ignore the rotation detection once a given axial displacement or axial position value has been reached in order to avoid involuntary menu changes.

[0063] In view of the above, at least the following usage scenarios are possible application cases of the present invention: detecting the unique position of the stem (e.g., T1 to T3) according to the first mode; preventing or ignoring the angle detection during the axial movement of the stem, especially when a function (menu) is selected by pressing the crown (second mode 2); and intensity adjustment of the electronic watch function (third mode). The intensity adjustment function may involve making the hands of the watch move slower or faster when setting the time, or it may, for example, serve as an interface for a game.

[0064] Although the present invention has been illustrated and described in detail in the drawings and the foregoing description, such illustration and description should be considered illustrative or exemplary and not restrictive, and the present invention is not limited to the disclosed embodiments. Other embodiments and variations can be understood and achieved by those skilled in the art upon study of the drawings, the present disclosure and the appended claims when carrying out the claimed invention.

[0065] In the claims, the term "comprising" does not exclude other elements or steps, and the quantifier "a" or "one" does not exclude a plurality. The mere fact that different features are recited in mutually different dependent claims does not indicate that a combination of these features cannot be used advantageously. Any reference signs in the claims should not be construed as limiting the scope of the invention.

Claims

1. A method for determining the axial displacement or axial position of a shaft (3) provided with a permanently magnetized component (7) and rotating about a displacement axis along the displacement axis (5) or a control value for a given function or operation depending on the axial displacement or axial position of the shaft, by means of a magnetic sensor arrangement (9) and a processing unit jointly forming an electronic control module, the method comprising the following steps performed by the electronic control module: - Measuring (101) first, second, and third magnetic field components of the magnetic field generated by the permanently magnetized component using a magnetic sensor arrangement along first, second, and third orthogonal axes respectively linked to the magnetic sensor arrangement, the third axis being parallel to the displacement axis; and compensating these first, second and third magnetic field components for the hard iron coefficient; -Determine (102) the current rotation angle value (θ of the axis (3) in a plane orthogonal to the displacement axis (5) of the axis based on the compensated first magnetic field component and the compensated second magnetic field component C ); - Calculate (103) the norm (N) of the magnetic field as a square or non-square magnetic field based on the compensated first, second, and third magnetic field components c ), the norm depending on the axial position of the axis along the displacement axis (5) and the angle of rotation of the axis (3); - selecting (104) a compensation function F(θ) depending on the rotational angle (θ) of the shaft (3) but not on the axial displacement or axial position (z) of the shaft; - Determine (105) a first value (V c ), called a compensation function value, for the current rotation angle value (θ c ) by applying the current rotation angle value to a compensation function; - By multiplying the norm (N c ) of the calculated magnetic field by the determined compensation function value (V c ), a second value (g c ) is calculated (106), the compensation function being selected such that the second value depends mainly on the axial position of the axis and less or not at all on the rotational angle of the axis; - selecting (107) the relationship between a first set of possible second values and a second set of possible axial displacements or axial positions and / or the control value depending on the possible axial displacement or axial position, and establishing for each second value of the first set the corresponding axial displacement or axial position of the shaft or the range of the corresponding axial displacement or position of the shaft or the corresponding control value; - By applying the calculated second value (g c ) to the relationship between the selected first and second groups, the axial displacement or axial position or control value of the axis is determined (108) with respect to the sensor arrangement (9).

2. The method according to claim 1, wherein the step of selecting the relationship between the first set and the second set establishes a range of corresponding second values for each stable axial position among the possible stable axial positions of the shaft (3).

3. The method according to claim 2, wherein the ranges of the second values are unique such that the ranges of the second values do not overlap with the ranges of other second values.

4. The method according to claim 1, wherein the step of selecting the relationship includes: Define a threshold value (g Th ) for a second value, and the step of determining the axial displacement or axial position or control value includes: disabling or ignoring the determination of the rotational angle of the shaft (3) when the second value is less than or equal to the threshold value.

5. The method according to claim 1, wherein the control value in the step of selecting the relationship depends on the axial displacement or axial position of the shaft and provides intensity adjustment for the function of a timepiece, the timepiece incorporating an electronic control device including the shaft and the electronic control module.

6. The method according to any one of the preceding claims, wherein the compensation function is selected based on how the axial displacement or position of the shaft is used.

7. The method according to claim 2 or 3, wherein the compensation function F(θ) is as follows: Average over z, where z denotes the axial displacement or axial position of the axis of rotation (5) along the axis (3), θ denotes the angle of rotation of the axis (3) in a plane orthogonal to the axis of rotation (5), and denotes the magnetic field.

8. The method according to claim 4, wherein the compensation function F(θ) is as follows: where θ denotes the angle of rotation of the shaft (3) in a plane orthogonal to the axis of rotation (5), z = P denotes a given axial displacement or axial position along the axis of rotation (5) of the shaft (3) from which the axial displacement is to be detected, and denotes a magnetic field.

9. The method according to claim 8, wherein the axial position P = 0.

10. The method according to any one of the preceding claims, wherein the sensor arrangement is a three-axis magnetometer (9) or is formed by three sensors, each sensor being configured to determine a different magnetic field component among the magnetic field components.

11. The method according to any one of the preceding claims, wherein the electronic control module is incorporated in a timepiece, wherein the shaft (3) is a setting lever associated with the crown of the timepiece, and wherein the permanently magnetized component of the shaft is a bipolar magnet fixed to the shaft and having a radial magnetization.

12. An electronic control device (1) for determining the axial displacement or axial position of a shaft (3) along a displacement axis (5) or a control value for a given function or operation depending on the axial displacement or axial position of the shaft, the shaft being provided with a permanently magnetized component (7) and being configured to rotate about the displacement axis, the electronic control device comprising a control module, the control module comprising a magnetic sensor arrangement (9) and a processing unit, the electronic control module comprising means for: - Measuring first, second, and third magnetic field components of a magnetic field generated by a permanently magnetized component using a magnetic sensor arrangement (9) along orthogonal first, second, and third axes respectively linked to the magnetic sensor arrangement, the third axis being parallel to the displacement axis; and compensating these first, second and third magnetic field components for the hard iron coefficient; -Determine the current rotational angle value (θ) of the axis (3) in a plane orthogonal to the displacement axis (5) of the axis (3) based on the compensated first magnetic field component and the compensated second magnetic field component C ) - Calculate the norm (N) of the magnetic field as squared or non-squared, based on the compensated first, second, and third magnetic field components c ), where the norm depends on the axial position of the axis along the displacement axis (5) and the rotational angle of the axis; - Select a compensation function F(θ) that depends on the rotational angle (θ) of the shaft (3) but does not depend on the axial displacement or axial position (z) of the shaft; - Determining a first value (V c ) called a compensation function value for the current rotation angle value (θ c ) by applying the current rotation angle value to a compensation function; - Calculate a second value (g c ) by multiplying the norm of the calculated magnetic field by the determined compensation function value, the compensation function being selected such that the second value depends mainly on the axial position of the shaft and less or not at all on the rotational angle of the shaft; c ) - Select the relationship between the first set of possible second values and the second set of possible axial displacements or axial positions and / or the control value depending on the possible axial displacement or axial position, and establish the corresponding axial displacement or axial position of the shaft or the range of the corresponding axial displacement or position of the shaft or the corresponding control value for each second value of the first set; - Determine the axial displacement or axial position of the shaft or the control value with respect to the sensor arrangement (9) by applying the calculated second value to the selected relationship between the first set and the second set.

13. A timepiece comprising an electronic control device as claimed in claim 12.

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