阅读说明：本技术 具有延伸穿过印刷电路板的次级线匝的感应位置传感器 (Inductive position sensor with secondary turns extending through printed circuit board ) 是由 A.丰塔内 于 2018-06-28 设计创作，主要内容包括：本发明涉及一种感应位置传感器,包括至少两个次级绕组(4、6),所述次级绕组由形成在印刷电路板的两个相对面上并被分成第一和第二区段(1、2)的多个线匝(10)组成。第一和第二区段(1、2)在线匝的宽度上分成在印刷电路板的一个面上的第一部分(11、21)和在相对面上的第二部分(12、22)。第一区段(1)的第二部分(12)由第二区段(2)的第一部分(21)延伸,并且第一区段(1)的第一部分(11)连接到相邻线匝的第二区段(2)的第二部分(22)。部分(11、12；21、22)通过穿过印刷电路板的相应通路(31至34)两两连接。(The invention relates to an inductive position sensor comprising at least two secondary windings (4, 6) consisting of a plurality of turns (10) formed on two opposite faces of a printed circuit board and divided into a first and a second section (1, 2). The first and second sections (1, 2) are divided over the width of the turns into a first portion (11, 21) on one face of the printed circuit board and a second portion (12, 22) on the opposite face. The second portion (12) of the first section (1) extends from the first portion (21) of the second section (2), and the first portion (11) of the first section (1) is connected to the second portion (22) of the second section (2) of the adjacent turn. The sections (11, 12; 21, 22) are connected two by means of corresponding vias (31 to 34) through the printed circuit board.)

1. An inductive position sensor comprising a primary winding and at least two secondary windings (4, 6), each secondary winding being composed of a plurality of turns (10) formed on two opposite faces of a printed circuit board, each secondary winding (4, 6) comprising turns (10), each turn having substantially the same shape, and the turns (10) being aligned in a direction, called longitudinal, with an offset in the longitudinal direction each time, each of the turns (10) being divided over the length of the turn into a first section (1) and a second section (2) that are complementary and continuous, characterized in that:

the first section (1) is divided, over the width of the turn, into a first portion (11) arranged on a face of the printed circuit board, referred to as the first face, and a second portion (12) arranged on a face of the printed circuit board opposite the first face, referred to as the second face, the first and second portions (11, 12) of the first section (1) being complementary;

-a second portion (12) of the first section (1) is extended over the length of the turn by a first portion (21) of the second section (2), this first portion (21) being arranged on a first face of the printed circuit board;

-a first portion (21) of the second section (2) is extended over the width of the turn by a second portion (22) of the second section (2), this second portion (22) being arranged on a second face of the printed circuit board, the first and second portions (21, 22) of the second section (2) dividing the second section (2) in width while being complementary;

-a first portion (11) of the first section (1) is connected to a second portion (22) of a second section (2) of an adjacent turn;

-the first and second portions (11, 12) of the first section (1), the second portion (12) of the first section (1) and the first portion (21) of the second section (2), the first portion (21) of the second section (2) and the second portion (22) of the second section (2) and the first portion (11) of the first section (1) of adjacent turns are connected by respective vias (31 to 34) through the printed circuit board.

2. Inductive position sensor according to the preceding claim, characterized in that, for each turn:

-the first and second portions (11, 12) of the first section (1) have lateral edges on the first and second faces of the printed circuit board, respectively, the opposite ends of the lateral edges thereof being connected by a first via (31);

-the second portion (12) of the first section (1) and the first portion (21) of the second section (2) have longitudinal edges on the second and first faces of the printed circuit board, respectively, the opposite ends of the longitudinal edges of which are connected by a second via (32);

-the first and second portions (21, 22) of the second section (2) have lateral edges on the first and second faces of the printed circuit board, respectively, the opposite ends of the lateral edges thereof being connected by a third via (33);

a second portion (22) of the second section (2) and a first portion (11) of the first section (1) of adjacent turns have longitudinal edges on the second and first faces, respectively, of the printed circuit board, the opposite ends of the longitudinal edges of which are connected by a fourth via (34).

3. The inductive position sensor according to the preceding claim, characterized in that the connection between the end of the longitudinal edge of the first portion (11) of the first section (1) and the fourth via (34) and the connection between the end of the longitudinal edge of the first portion (21) of the second section (2) and the second via (32) are in the same plane parallel to the printed circuit board, the second and fourth vias (34) having the same length.

4. An inductive position sensor according to claim 2 or 3, characterized in that the first passage (31) and the third passage (33) have the same length.

5. An inductive position sensor according to any one of the preceding claims, characterized in that the longitudinal edges of the respective first and second portions (11, 12; 21, 22) of the first (1) and second (2) sections face each other in overlapping planes.

6. Inductive position sensor according to any of the preceding claims, characterized in that the first and second sections (1, 2) have the same length and that the offset between two adjacent turns (10) in the longitudinal direction is smaller than the length of the first section (1) or the second section (2).

7. Inductive position sensor according to any of the preceding claims, characterized in that the longitudinal offset between the two turns (10) is constant.

8. An inductive position sensor according to any one of the preceding claims, characterized in that the respective first and second parts (11, 12; 21, 22) of the first section (1) or the second section (2) are separated such that the respective first and second parts (11, 12; 21, 22) of the first section (1) or the second section (2) receive an equal amount of magnetic flux.

9. Inductive position sensor according to any of the preceding claims, characterized in that the primary winding surrounds the secondary winding (4, 6) and has turns comprising longitudinally extending linear sections.

10. Inductive position sensor according to the preceding claim, characterized in that the turns (10) of one and the same secondary winding (4, 6) are connected to each other such that the electromotive forces induced by the alternating magnetic field in these turns (10) add together.

Technical Field

The present invention relates to an inductive position sensor.

Background

An advantage of such a sensor is that the position of a mechanical part or any other element can be determined without contact with the part whose position is desired to be determined. This advantage makes these sensors useful in a variety of industries. Such sensors are also used in consumer applications, such as in the automotive field, where the invention is preferably implemented. However, the invention may be used in a variety of other fields.

The operating principle of an inductive sensor is based on the variation of the coupling between the primary and secondary windings of a transformer that operates at high frequencies and does not use a magnetic circuit. The coupling between these windings varies with the position of the conductive moving part, which is often referred to as the "target". Specifically, the current induced in the target changes the current induced in the secondary winding. By adjusting the configuration of the windings and knowing the current injected into the primary winding, the voltage induced in the secondary winding can be measured to determine the location of the target.

In order to incorporate such inductive sensors into devices, in particular electronic devices, it is known to produce the above-mentioned transformers on a printed circuit board. The primary and secondary windings are comprised of traces on a printed circuit board. The primary winding is then powered, for example, by an external power source, and the secondary winding is then subjected to a voltage induced by the magnetic field generated by the current flowing through the primary winding.

The conductive object is, for example, a metal part, the shape of which can be simple. For example, it may be a part cut from a metal plate. To manufacture a linear sensor, the target is cut, for example, into a rectangle, while for a rotary sensor it will be cut, for example, into a shape with corner segments that fit the radius and angle of the part motion.

Typically, the two sets of secondary windings are designed to acquire the sine and cosine functions of the target position in one full stroke of the sensor. Such cosine and sine functions are well known and can be easily handled by electronic systems. By determining the ratio of sine and cosine and then applying the arctan function, an image of the target location is obtained. The arguments of the sine and cosine functions are linear or affine functions of the position of the object, whose course therefore represents a greater or lesser part of the spatial period of these trigonometric functions.

In order to obtain induced currents that can be reliably measured, it is preferable to provide a large number of turns or turns of large size. The second option is not compatible with manufacturing a compact sensor. Because of this, it is often the option to provide a large number of turns.

In order to limit the space occupied on the printed circuit board, the document FR- A-3002034 in particular has proposed to manufacture the turns used to form the secondary winding on two different layers on the printed circuit board. To achieve this, vias should be made through the printed circuit board to allow the connection of the turns thus generated. Such turns have a continuous first and second section in the longitudinal direction of the turn. Each turn portion has a linear or angular sector shape. When viewing the turns from a distance, the average plane of the turns may be considered to be inclined relative to the plane of the board.

Such inductive sensors exhibit a degree of sensitivity to changes in the air gap. However, it is preferred that such a sensor is insensitive to geometrical changes other than the position where measurement is desired, which may be changes in the air gap or changes in eccentricity. Shaping the turns in the manner proposed by the closest prior art does not solve the problem of geometrical variations.

Disclosure of Invention

The problem on which the invention is based is to design an inductive sensor with a secondary turn arrangement that makes the sensor insensitive to geometrical variations and to eccentricity.

To this end, the invention relates to an inductive position sensor comprising a primary winding and at least two secondary windings, each secondary winding being made up of a plurality of turns formed on two opposite faces of a printed circuit board, each secondary winding comprising turns, each turn having substantially the same shape and said turns being aligned in a direction called longitudinal direction, with an offset in the longitudinal direction each time, each of said turns being divided over the length of the turn into a first and a second complementary and continuous section, characterized in that:

the first section is divided, within the width of the turn, into a first portion arranged on a face of the printed circuit board, called first face, and a second portion arranged on a face of the printed circuit board opposite the first face, called second face, the first and second portions of the first section being complementary;

the second portion of the first section extends over the length of the turn from a first portion of the second section, which first portion is arranged on the first face of the printed circuit board;

a first portion of the second section extends over the width of the turn by a second portion of the second section, which is arranged on the second face of the printed circuit board, the first and second portions of the second section dividing the second section in width while being complementary;

a first portion of the first section is connected to a second portion of the second section of the adjacent turn;

the first and second portions of the first section, the second portion of the first section and the first portion of the second section, the first portion of the second section and the second portion of the second section, and the second portion of the second section and the first portion of the first section of the adjacent turns are connected by respective vias through the printed circuit board.

The technical effect is to correct and balance prior art wire turns having two longitudinal sections, an upper section and a lower section, respectively. A problem with such a turn is that it has a slanted appearance along its length. By dividing each section into two lateral portions located at different heights and on opposite sides of the printed circuit board, the pattern of turns is more balanced in length by the shape of the two sections, which are no longer at different heights.

Each section is divided into lateral portions, a first portion of the first section remaining unchanged with respect to the turns of the prior art, and a second portion lowered by being placed on the other face of the printed circuit board. For the second section, the first portion is raised and the second portion remains unchanged.

This results in a greatly reduced sensitivity to air gap variations and eccentricity variations and an enhanced linearity of the sensor.

Specifically, calculations show that for a target eccentricity of 0.5 mm for a 360 ° sensor, the linearity is around 1.5% and the sensitivity to air gap is 0.5% before implementing the invention. After the invention is implemented, the linearity is close to 0.5%, and the sensitivity to air gaps is close to 0.3%. The performance of the sensor is improved by two times.

Furthermore, since each turn passes through the printed circuit board four times, it is better secured in place and there is no risk of the turn moving longitudinally or laterally with respect to the printed circuit board.

Advantageously, for each turn:

the first and second portions of the first section have lateral edges on the first and second faces of the printed circuit board, respectively, opposite ends of their lateral edges being connected by a first via;

the second part of the first section and the first part of the second section have longitudinal edges on the second and first faces of the printed circuit board, respectively, the opposite ends of their longitudinal edges being connected by a second via;

the first and second portions of the second section have lateral edges on the first and second faces of the printed circuit board, respectively, opposite ends of their lateral edges being connected by a third via;

the second portion of the second section and the first portion of the first section of adjacent turns have longitudinal edges on the second and first faces, respectively, of the printed circuit board, the opposite ends of their longitudinal edges being connected by a fourth via.

Advantageously, the connection between the end of the longitudinal edge of the first portion of the first section and the fourth via and the connection between the end of the longitudinal edge of the first portion of the second section and the second via are in the same plane parallel to the printed circuit board, the second and fourth vias having the same length. This makes it possible to have a symmetry that contributes to the balancing of the turns.

Advantageously, the first and third passages have the same length.

Advantageously, the longitudinal edges of the respective first and second portions of the first section and the second section face each other in overlapping planes.

Advantageously, the first and second sections have the same length, and the offset in the longitudinal direction between two adjacent turns is less than the length of the first or second section. This makes it possible to optimize the number of turns of wire over a given area.

Advantageously, the longitudinal offset between the two turns is constant. This makes it possible to facilitate the use of voltage measurements made at the terminals of the secondary winding.

Advantageously, the first and second portions of the first or second section are separated such that the respective first and second portions of the first or second section receive equal amounts of magnetic flux.

Advantageously, the primary winding surrounds the secondary winding and has turns comprising longitudinally extending linear portions.

Advantageously, the turns of the same secondary winding are connected to each other so that the electromotive forces induced in these turns by the alternating magnetic field add together.

Drawings

Other features, objects and advantages of the invention will become apparent from a reading of the following detailed description and a review of the accompanying drawings, which are given by way of non-limiting example, and in which:

figure 1 is a schematic top view of two secondary windings of a position sensor according to the prior art;

fig. 2 is a schematic perspective view of the secondary winding of fig. 1;

figure 3 is a perspective schematic view of a turn according to the prior art;

figures 4 to 7 are perspective schematic views of turns according to one embodiment of the invention, with respective hatching lines for each of these views of a specific portion of the first or second longitudinal section of the turns;

fig. 8 is a schematic view of the turns shown in fig. 4 to 7, in which the turn portions have been modified with respect to the turns according to the prior art shown in fig. 3, represented with a dashed line.

Detailed Description

Fig. 1 shows a top view of the first secondary winding 4 and the second secondary winding 6, and fig. 2 is a perspective view of the secondary winding of fig. 1. Each of the two windings has a turn 10 a. These turns 10a are in accordance with the prior art, but if the shape of the turns 10a is omitted, and only for stacked arrangements of the turns 10a, fig. 1 and 2 described below can be used to illustrate the invention.

It should be noted that the turns 10a are substantially similar for each of these windings, but are each time offset relative to each other in the longitudinal direction shown in fig. 1 by the longitudinal axis a.

The longitudinal offset between two adjacent turns may be the same each time. Furthermore, it is also preferred that the second secondary winding 6 is symmetrical with respect to the first secondary winding 4 with respect to a transverse plane (not shown) perpendicular to the longitudinal axis, when seen from above. The two windings have the same number of turns and the area of the turns is the same.

As shown in fig. 3, in the prior art, and not for the present invention, each turn 10a has a first upper section 1 and a second lower section 2, the first section 1 corresponding to a trace etched on one layer of a printed circuit board (not shown), and the second lower section 2 corresponding to a trace etched on another opposite layer of the same printed circuit board. Electrical continuity between the traces forming the first and second sections 1, 2 is provided by vias 32 through the printed circuit board, with the section labeled 16 in fig. 2 providing electrical continuity.

Electrical continuity between two adjacent turns is provided in the following manner: the first upper section 12 of the turn 10a is connected to the second lower section 2 of the adjacent turn by another via 34 through the printed circuit board, the section within the printed circuit board providing said electrical continuity. In the embodiment shown in fig. 1 and 2, each first upper section 1 and each second lower section 2 may take the shape of an irregular semi-hexagon.

Each first upper section 1 and each second lower section 2 therefore adopts an overall concave shape, the concavity of the first section 1 of a turn 10a being oriented oppositely with respect to the concavity of the second lower section 2 of the same turn.

More generally, in the secondary winding, the concavity of the first upper section 1 is directed towards the first side and the concavity of the second section 2 is directed towards the side opposite to the first side. Thus, it is possible to have lower and/or upper portions in the shape of circular arcs, elliptical arcs, half octagons, etc. When viewed from above, it can be seen that there is some symmetry between the first upper section 1 and the respective second lower section 2 with respect to a straight line through the passages 32, 34. Due to the offset between turns of the wire, the symmetry is not perfect.

Returning to fig. 1 and 2, the segments 16 (one of which is referenced in fig. 2, the position of which also corresponds to the position of the vias to which they are connected) are aligned with two parallel segments which are arranged on either side of the longitudinal axis a and perpendicular thereto, i.e. they pass through the printed circuit board. The two segments are not symmetrically arranged with respect to the longitudinal axis a, but are offset in a longitudinal direction defined by the longitudinal axis.

The first secondary winding 4 and the second secondary winding 6 are connected at the level of the transversal symmetry plane so that, for a given variable magnetic flux, the electromotive force induced in the first secondary winding 4 is opposite to the electromotive force induced in the second secondary winding 6. In the same winding, it should be noted that the electromotive forces induced by the variable magnetic flux in each turn 10a add together.

Finally, on the left side of fig. 1 and 2, the presence of two connection tracks 18 can be seen, which allow the secondary winding to be connected to a device for measuring the voltage at its terminals.

The assembly formed by the first secondary winding 4 and the second secondary winding 6 makes it possible to obtain, for example, a sinusoidal function when the conductive object moves close to these windings. In order to obtain a cosine function during the movement of the object, it is known to use another set of windings superimposed on the first set of windings.

Fig. 3 shows a single turn according to the prior art. Such a turn 10a is divided over the length of the turn into a first section 1, called upper section, and a second lower section 2, the first and second sections 1, 2 being complementary and continuous. As mentioned above, two passageways 32 and 34 are provided on the longitudinal edges of the turns 10a at the respective junctions between the longitudinal edges of the first and second sections 1, 2.

With the prior art turn 10a, if the first section 1 or the second section 2 is manually divided into a first and a second portion 11, 12, respectively, over the width of the turn; 21. the pairs of the respective two parts are substantially at the same level by being arranged on the same respective face of the printed circuit board (this face is referred to as the first face of the first section 1, or on the second face of the second section 2). Thus, the "artificial" first and second portions 11, 12 of the first and second sections 1, 2; 21. 22, there is no difference in level between each of the pairs.

The inductive position sensor according to the present invention has the following common features with the inductive position sensor of the prior art.

As can be seen from fig. 1 and 2, with the prior art sensor, although still valid for the sensor according to the invention, apart from the feature of replacing the turns 10a with turns 10, the inductive position sensor comprises a primary winding and at least two secondary windings 4, 6, each comprising a plurality of turns 10, each turn 10 being formed on two opposite faces of the printed circuit board.

The secondary windings 4, 6 comprise turns 10, each having substantially the same shape, said turns 10 being aligned in a direction called longitudinal, with an offset in the longitudinal direction each time. Each of said turns 10 is divided over the length of the turn 10 into a complementary and continuous first section 1 and second section 2.

Fig. 4 to 8 show a turn 10 forming part of a secondary winding of an inductive position sensor according to the invention.

According to the invention, the first section 1 is divided, within the width of the turns 10, into a first portion 11 arranged on a face of the printed circuit board, referred to as the first face, and a second portion 12 arranged on a face of the printed circuit board opposite the first face, referred to as the second face, the first and second portions 11, 12 of the first section 1 being complementary.

The second portion 12 of the first section 1 extends over the length of the turn 10 from a first portion 21 of the second section 2, which is arranged on the first side of the printed circuit board, the first portion 21 of the second section 2 extends over the width of the turn 10 from a second portion 22 of the second section 2, which is arranged on the second side of the printed circuit board, the first and second portions 21, 22 of the second section 2 dividing the second section 2 in the width direction while being complementary.

The first portion 11 of the first section 1 is also connected to the second portion of the second section of the adjacent turn. The first and second portions 11, 12 of the first section 1 grouped in pairs, the second portion 12 of the first section 1 and the first portion 21 of the second section 2, the first portion 21 of the second section 2 and the second portion 22 of the second section 2, and the second portion of the second section of the adjacent turn and the first portion 11 of the first section 1, respectively, are connected two by respective vias 31 to 34 through the printed circuit board.

Thus, for each of the two sections 1, 2 of the turn 10, the section 1 or 2 is in two lateral portions 11, 12 of the section 1, 2; 21. 22 have a height difference therebetween. For each section 1, 2, the portion 11 or 21 is on a first side of the printed circuit board and the associated other portion 12 or 22 is on a second side of the printed circuit board. Thus, instead of the upper section 1 or the lower section 2 envisaged in the prior art, the sections 1, 2 divide the turns 10 longitudinally, each section 1, 2 being divided on both faces of the printed circuit board, the portion 11 or 12 of the first section 1 on one face of the circuit board being extended by the portion 22 or 21 of the second section 2 on the other face, and vice versa, the two portions 11, 12 of the same section 1, 2; 21. 22 are located on different sides of the printed circuit board.

In fig. 4 to 8, the portions 11, 12 of the first and second sections 1, 2; 21. 22 are depicted as being relatively flat, but this may also be a different case. Similarly, portions 11, 12 of the same first section 1 or second section 2; 21. 22 are not necessarily equal in size; it is important that the same magnetic flux flows through them. Thus, the respective two portions 11, 12 of the first section 1 or the second section 2; 21. 22 may be divided mainly such that two parts 11, 12 or 21, 22 of the same section 1 or 2, e.g. the first and second parts 11, 12 of the first section 1 or the first and second parts 21, 22 of the second section 2 receive equal amounts of magnetic flux.

In fig. 4, the second portion 12 of the first section 1 is shaded to make it more visible. In fig. 5, a first portion 21 of the second section 2 is indicated with shading, whereas in fig. 6 a second portion 22 of the second section 2 is indicated with shading. In fig. 7, a first portion 11 of the first section 1 is indicated with shading. In fig. 8, the portion of the turn 10 modified with respect to the prior art turn 10a shown in fig. 3 is shown in dashed lines.

The alignment of the first and second sections 1, 2 need not be linear. It may also be circular or possibly elliptical. Those skilled in the art will appreciate that this alignment corresponds to the direction of movement of the object whose position is desired to be determined. In this case, this is most often a linear movement using a linear position sensor. However, it may also be a movement along a curved, most commonly circular trajectory.

For each turn, the first and second portions 11, 12 of the first section 1 may have lateral edges on the first and second faces of the printed circuit board, respectively, opposite ends of their lateral edges being connected by a first via 31.

The first and second sections 1, 2 may be half-hexagons, however, the second portion 12 for the first section 1 and the second portion 22 for the second section 2 are sunk by being arranged on the other side of the printed circuit board with respect to the first portion 11 of the first section 1 or the first portion 21 of the second section 2. The turns 10 can be produced by forming linear portions, and the number of linear portions is limited without excessively adversely affecting the area of the turns.

For each turn, the second portion 12 of the first section 1 and the first portion 21 of the second section 2 may have longitudinal edges on the second and first faces, respectively, of the printed circuit board, the opposite ends of the longitudinal edges of which are connected by a second via 32; the second via 32 may also be used to connect to the turns adjacent to the presently described turns 10.

The first and second portions 21, 22 of the second section 2 may have lateral edges on the first and second faces of the printed circuit board, respectively, opposite ends of which are connected by a third via 33. The top or bottom end of the first via 31 may be aligned with the top or bottom end of the third via 33 along the longitudinal axis of the turn 10.

Finally, the second portion 22 of the second section 2 and the first portion 11 of the first section 1 of adjacent turns 10 have longitudinal edges on the second and first faces, respectively, of the printed circuit board, the opposite ends of the longitudinal edges of which are connected by a fourth via 34.

The connection between the end of the longitudinal edge of the first portion 11 of the first section 1 and the fourth via 34 and the connection between the end of the longitudinal edge of the first portion 21 of the second section 2 and the second via 32 may be in the same plane parallel to the printed circuit board, the second and fourth vias 34 having the same length.

The same applies to the common length of the first and third passages 31, 33. The four passages 31 to 34 may also have the same length.

The longitudinal edges of the respective first and second portions 11, 12 of the first section 1 and the second section 2 may face each other in overlapping planes. One end of the longitudinal edge of the second portion 12 of the first section 1 may be connected to the lower end of the second passage 32, and one end of the longitudinal edge of the first portion 21 of the second section 2 may be connected to the upper end of the second passage 32.

The lengths of the first and second sections 1, 2 may be equal, and the offset between two adjacent turns 10 in the longitudinal direction may be less than the length of the first section 1 or the second section 2. This offset in the longitudinal direction may be constant.

With reference to any of figures 1, 2 and 4 to 8, bearing in mind that the turns 10a shown in these figures must be replaced by turns 10 according to the invention, the primary winding may surround the secondary windings 4, 6 by having turns 10 comprising longitudinally extending linear portions. The sensor according to the invention may comprise two sets of secondary windings 4, 6, one set for obtaining a sine function and the other set for obtaining a cosine function.

One of these secondary winding groups 4, 6 may comprise, for example, two secondary windings 4, 6 arranged symmetrically with respect to the central axis a and connected so that the electromotive force induced in the turns 10 of the first secondary winding 4, 6 is opposite to the electromotive force induced in the turns 10 of the second secondary winding 4, 6. There may be more than two secondary windings 4, 6, in particular redundant secondary windings 4, 6.

The turns 10 of one and the same secondary winding 4, 6 can be connected to one another such that the electromotive forces induced in these turns 10 by the alternating magnetic field add together.

The invention is not limited to the embodiments described above and to the variants presented by way of non-limiting example. It also relates to all modifications which may occur to a person skilled in the art within the scope defined by the appended claims.