Coil device for a proximity sensor and method for manufacturing such a coil device

Abstract

A coil device (10) for a proximity sensor is described, comprising a flexible printed circuit board (12) on which a conductor track (14) is arranged, the conductor track having a first end region (20) and a second end region (22), wherein the flexible printed circuit board (12) is rolled around a roll axis (R) or folded around a fold axis (F) such that the conductor track (14) forms a coil (46), with a rigid printed circuit board (18) for connecting at least one electronic component (24), and with an electrical connecting element (16), wherein the first end region (20) and the second end region (22) are each electrically connected to the rigid printed circuit board (18) by means of the electrical connecting element (16). This allows for the construction of a modular coil device.

Description

[0001] The invention relates to a coil device for a proximity sensor and a method for manufacturing such a coil device. State of the art

[0002] Proximity sensors are commonly used in practice to detect an object within a specific distance range. Inductive proximity sensors work by measuring changes caused by a metallic object in an oscillating electromagnetic field generated by a coil, thus detecting the object. While inductive proximity switches determine whether the object is within a certain distance of the sensor, inductive distance sensors can detect both the distance and the object's position relative to the sensor.

[0003] Proximity sensors generally operate on the principle that an excitation coil can be energized with an electric current to generate an oscillating electromagnetic field. If a metallic object is present near the sensor, eddy currents induced by the changing magnetic field of the coil occur near the object's surface. This, in turn, leads to a change in the geometry and intensity of the electromagnetic field. This change in the electromagnetic field can be detected by measuring an induced voltage in the excitation coil and / or in one or more separate sensing coils of the proximity sensor.

[0004] Such coils of a proximity sensor can be, for example, a wire coil, a coil structured on and / or in a rigid printed circuit board, or a coil structured on and / or in a flexible printed circuit board. The latter, "flexible coil," can be manufactured, for example, according to DE 10 2008 012 120 B4. Different configurations of several such "flexible coils" can be implemented on the circuit board of the "flexible coil" according to DE 10 2019 115 405 A1. These three manufacturing technologies each require different manufacturing processes for the coils, so that the production of a proximity sensor requires different manufacturing equipment and different processes depending on the type of coil.To minimize the costs of manufacturing a proximity sensor, it is desirable to unify and standardize coil devices and their manufacture in such a way that they are suitable for different types of proximity sensors or other product types that use similar coils. Disclosure of the invention

[0005] The invention is based on the objective of providing a coil device, a proximity sensor and a method for manufacturing a coil device that are particularly cost-effective.

[0006] This problem is solved by a coil device, a proximity sensor, and a method for manufacturing a coil device according to the independent claims. Advantageous embodiments are specified in the dependent claims.

[0007] According to a first aspect, a coil device for a proximity sensor is provided, comprising a flexible printed circuit board on which a conductor track is arranged, having a first end region and a second (in particular, different) end region, wherein the flexible printed circuit board is rolled around a rolling axis or folded around a folding axis such that the conductor track forms a coil, comprising a rigid printed circuit board for electrically connecting at least one electronic component, and comprising an electrical connecting element, wherein the first end region and the second end region are each electrically connected to the rigid printed circuit board by means of the electrical connecting element.

[0008] This allows for the production of a modular coil device, which can, for example, function as an excitation and / or detection element for any type of sensor (in particular an inductive proximity sensor or a gradiometer sensor or slope sensor), comprising three standardizable components: a coil based on a flexible circuit board, a rigid circuit board on which electronic components or parts for the proximity sensor can be placed, and an electrical connecting element for electrically and mechanically connecting both circuit boards.

[0009] The coil, particularly due to its coiled or folded circuit board, can be easily scaled in size, for example, in diameter, allowing the use of different sized sensor housings, such as M18, M12, M8, etc. It is also possible to implement a few basic coil types with the flexible circuit board. Since the flexible circuit board, unlike a coil based on a rigid board, has a different orientation, new coil types with a wide variety of electrical properties can be realized.

[0010] The rigid circuit board can serve as a configuration module for the respective sensor type, as the corresponding electrical connection of the coil to the rigid circuit board can enable different applications of the coil device. Depending on the number and type of connecting elements used, these can also be standardized. In this context, "standardized" can be understood to mean that the manufacturing process or the competencies can be unified. It does not necessarily mean that a DIN standard or a standard specification must be met.

[0011] Overall, the modular design allows for a reduction or minimization of the necessary manufacturing steps, logistics within the production process, and the types of manufacturing tools used. Furthermore, an entire product portfolio can be realized with only a few variations of the three components, thus reducing the complexity of manufacturing different proximity sensors. Additionally, the development of further products based on this modular coil assembly can be accelerated, as less planning time may be required for component redesign. For example, it may only be necessary to redesign the rigid circuit board, since the coil and connecting element can be reused.

[0012] Overall, due to the coil device according to the invention, both the manufacture of the coil device and the coil device and the proximity sensor can be particularly cost-optimized and / or cost-effective.

[0013] The flexible conductor track can be rolled or folded at least once, and in particular several times, completely or entirely (especially overlapping). The coil formed by the conductor track can have as many turns as the number of times the circuit board can be rolled up or folded around the folding axis. The rolling or folding axis can be perpendicular to the plane of the coil, i.e., the plane in which the coil can essentially extend.

[0014] In one embodiment, the connecting element incorporates solder or solder paste. This measure enables a direct connection of both circuit boards.

[0015] In one embodiment, the connecting element includes at least one Flexible Printed Circuit (FPC) connector, allowing for the use of a wide selection of connectors of varying sizes and mounting options. For example, surface-mountable FPC connectors can be soldered directly onto the rigid printed circuit board along with other surface-mounted electronic components (SMDs) or components of the proximity sensor. Furthermore, soldering between the flexible and rigid printed circuit boards can be eliminated. A mechanical and electrical connection can be achieved by assembling the components in a single, rapid production step.The end section of the flexible printed circuit board (FPC), and thus the end section of the conductor track, can be inserted into a corresponding slot of the FPC connector and held securely in place by either a locking mechanism or another mechanical fixing mechanism, preventing the end section from slipping out of the connector. Although the FPC connector, as an additional component, can increase manufacturing costs, the coil assembly produced in this way can be more cost-effective compared to a coil assembly where both circuit boards are soldered together.

[0016] In one embodiment, the rolling or folding axis of the flexible printed circuit board (PCB) runs essentially parallel or parallel to a dimension of the rigid PCB. In such a configuration, the coil plane or the body of the flexible PCB can thus run transversely, and in particular perpendicularly, to the dimension of the rigid PCB. An end region of the flexible PCB, on which the end regions of the conductor track are arranged, can be bent or folded in such a way that the end regions of the conductor track can be arranged parallel to the rigid PCB, for example, to simplify the soldering of the two PCBs. This measure can ensure that the length of the rigid PCB is not affected by the diameter of the coil. The electronic components can then be placed on the resulting larger area of ​​the rigid PCB.Components of the proximity sensor can be accommodated particularly easily.

[0017] In one embodiment, the rolling or folding axis of the flexible circuit board runs essentially transversely, and in particular perpendicularly, to a dimension of the rigid circuit board. In such a configuration, the end regions of the conductor track and also of the flexible circuit board can be bent in such a way that they run parallel to the dimension of the rigid circuit board. In this embodiment of the coil arrangement, the available surface area of ​​the rigid circuit board on which the electronic components or components for the proximity sensor can be placed may be limited. However, the coil device can be implemented very compactly and easily integrated into a housing.

[0018] In one embodiment, a contact point for the first end region of the conductor track is arranged on one side of the rigid printed circuit board (PCB), and a contact point for the second end region of the conductor track is arranged on a second (especially different) side of the PCB. This embodiment can particularly easily facilitate the arrangement of the rigid PCB parallel to the rolling or folding axis. In other words, the rigid PCB can be connected to different end regions of the conductor track on two different sides.

[0019] In one embodiment, contact points for the first and second end regions of the conductor track or for the connecting element are arranged on one side of the rigid printed circuit board, with a contact point for the at least one component being arranged on a second (in particular, other) side of the rigid printed circuit board. In other words, the rigid printed circuit board can be connected to the conductor track on only one side, while the component can be arranged on the other side. In this relative arrangement of the two printed circuit boards, their connection can be made particularly easily. This embodiment can be used particularly easily in conjunction with arranging the rigid printed circuit board transversely, in particular perpendicularly, to the roll or fall axis.

[0020] In one embodiment, at least a second conductor track is arranged on the flexible printed circuit board (PCB), which has a first end region and a second end region. The conductor track and the at least second conductor track run substantially adjacent to each other (in particular, on the same side of the flexible PCB), with the at least second conductor track forming at least a second coil. In particular, the conductor tracks can run substantially parallel to each other (for example, except at the end regions). This allows the number of coils in the coil device to be scalable in order to improve the excitation of the electric field and / or the detection of the induced voltage. In particular, compared to wire coils or a rigid PCB with coils, more coils can be accommodated in the coil device while maintaining the same overall size.Furthermore, the use of the flexible printed circuit board with multiple conductor tracks, compared to the other two coil types, makes it easier to realize axially offset and precisely positioned coils.

[0021] The rigid circuit board can have corresponding contact points as described above. Since the more rigid circuit board serves to connect the different coils, the electrical connection of multiple coils can be standardized and thus simplified during the manufacturing process.

[0022] In one embodiment, the first and second end regions of the conductor track and the first and second end regions of the at least second conductor track are electrically connected to the rigid printed circuit board in such a way that the first coil and at least the second coil are electrically isolated coils. This allows electrically independent coils to be configured on the rigid printed circuit board by means of appropriate contacts, depending on the desired application. If required, exactly as many electrically independent coils can be generated as there are coils on the flexible printed circuit board.

[0023] In one embodiment, the first and second end regions of the conductor track and the first and second end regions of the at least second conductor track are electrically connected to the rigid printed circuit board in such a way that the first coil and second coil are split coils. For this purpose, an end region of the first coil (for example, on a first side of the rigid printed circuit board) can be electrically connected to an end region of the second coil (for example, on a second or other side of the rigid printed circuit board), or an end region of the second coil (for example, on the first side of the rigid printed circuit board) can be electrically connected to an end region of the first coil (for example, on the second or other side of the rigid printed circuit board). This allows for the creation of a composite coil with three terminals. The coil device thus realized can be used in a Hartley oscillator.

[0024] In one embodiment, the first and second end regions of the conductor track and the first and second end regions of the at least second conductor track are electrically connected to the rigid circuit board in such a way that the first coil and second coil are connected in series. This allows a composite coil to be formed, which has a larger number of turns and can generate a correspondingly stronger electromagnetic field. Furthermore, this allows the inducible voltage to be increased.

[0025] The three embodiments described above allow for easy and flexible modification of the number, design, and functions of the resulting coils, as only the contacts of the first and second coils on the rigid circuit board need to be adjusted. In other words, based on the same coils formed by the flexible circuit board and its traces, a wide variety of coil configurations can be created simply by changing the configuration of the rigid circuit board and its contact points. This avoids the technically more complex task of directly contacting the first and second coils on the flexible circuit board, which is more challenging in terms of their orientation. Furthermore, electronic components can be placed directly on the rigid circuit board and do not need to be contacted with the flexible circuit board as well.

[0026] In one embodiment, the coil device further comprises a core element, which may be made of or formed from a ferromagnetic material, in particular ferrite, and which may be arranged in the interior of the coil in a coil plane. In this context, ferrite may belong to the class of ferrites and be a soft or hard magnetic ferromagnetic, usually ceramic, material. In particular, the selected ferrite material may be hard magnetic. Iron may not be used as the material for the core element. The core element may fill the interior of the coil, which may be bounded by the conductor track or the flexible circuit board, and an outer surface of the core element, which may extend transversely (in particular perpendicularly) to the coil plane, may be adapted to the internal shape of the rolled or folded flexible circuit board.The core element can therefore be plate-shaped and arranged parallel to the coil plane, filling the interior of the coil.

[0027] The coil device may further comprise a sheath that surrounds the rolled or folded flexible circuit board, and thus the coil, laterally on its outer surface and in the top area. The sheath may also be made of the same or a different ferromagnetic material as the core element, or be formed from it. In particular, the ferromagnetic material may be ferrite (for example, hard magnetic ferrite). Iron may not be used as the material for the sheath. The sheath may have a side element that surrounds and / or covers the outer surface of the flexible circuit board. Furthermore, the sheath may have a top element that covers one top side of the coil. The sheath may also have another top element that covers the other top side of the coil. The height of the core element may be dimensioned such that the top element(s) and the core element are flush with each other.The core element and the mantle can be formed in one piece.

[0028] These two previously described measures can enable the electromagnetic field of the coil to be directed towards the object to be detected and the field strength of the coil to be increased. This allows the range of the proximity sensor to be extended and objects located at a greater distance from the sensor to be detected. This can be particularly advantageous for an inductive proximity switch.

[0029] In one embodiment, the flexible printed circuit board has two flags extending parallel to the roll or fold axis, with the end regions of the conductor track arranged on one of the other two flags (particularly on the outer side facing away from the coil, axis, or coil interior). In other words, the first end region can be located on the first flag and the second end region on the second flag. Viewed from above, the flags can be arranged on opposite regions of the coil. This allows the coil contacts to be located at a distance from the coil plane, thus minimizing any electrical interference with the field generated by the coil.In particular, the core element in the area of ​​the flags can each have a (particularly semicircular) recess that opens or widens outwards (i.e., away from the inside of the spool) and through which one of the two flags can extend. If only a cover element of the jacket is present, the cover element can be arranged on the same side of the spool as the flags.

[0030] In one embodiment, the cross-section of the rolled or folded flexible circuit board, extending transversely, particularly perpendicularly, to the rolling or folding axis, is round, oval, rectangular, or square. This allows the respective coil shape to be advantageously adapted to the design of the proximity sensor.

[0031] In one embodiment, the conductor track runs in a straight line, a corrugated pattern, or a zigzag pattern on the flexible circuit board. This allows the inductance and / or resistance and / or coupling factor of the resulting coil to be adjusted in order to specifically optimize the electrical properties of the coil for a desired application.

[0032] In one embodiment, the flexible printed circuit board (PCB) is multilayered, with the conductor track arranged in a first layer of the PCB, and at least a second conductor track arranged in at least a second layer of the PCB, the second conductor track forming at least a second coil. The end regions of the first and second conductor tracks are arranged on a (particularly common) outer surface of the PCB by means of vias. This allows the number or density of the conductor tracks, and thus the overall performance of the coil, to be increased. The endpoints of the conductor tracks can be arranged on a conductive outer layer of the PCB, which may or may not contain a conductor track.

[0033] In one embodiment, the conductor track is configured with at least two strands, particularly with a plurality of strands, in its central region. In other words, the individual strands of the conductor track can each have a common first and second endpoint. This allows the conductor track to form a stranded wire. Despite increased manufacturing costs, this measure can be advantageous in certain sensor applications. In particular, the strands can be implemented on the circuit board such that they fan out at acute angles from an end region (particularly a straight one) and then extend adjacently, particularly parallel to each other, in a central region of the circuit board.

[0034] It is understood that at least the second coil can be realized in the same way as described above (for example, with regard to its cross-section, its course and / or its number of strands).

[0035] The flexible printed circuit board can, for example, contain or be made of polyimide. This material can provide the necessary structural integrity for the coil.

[0036] The rolled-up or folded coil can be held in shape, for example, by means of adhesive or a mechanical fixation.

[0037] According to a second aspect, a proximity sensor is provided, with a coil device according to the first aspect, wherein the proximity sensor is an inductive proximity switch or an inductive distance sensor.

[0038] According to a third aspect, a method for manufacturing a coil device for a proximity sensor is provided, comprising the steps of providing a flexible printed circuit board on which a conductor track is arranged having a first end region and a second end region, wherein the flexible printed circuit board is rolled around a rolling axis or folded around a folding axis such that the conductor track forms a coil, providing a rigid printed circuit board for electrically connecting at least one electronic component, providing an electrical connecting element, and electrically connecting each of the first end region and the second end region to the rigid printed circuit board by means of the electrical connecting element.

[0039] The flexible printed circuit board can be rolled or folded, for example, using a plastic coil forming tool or without using such a tool. The flexible printed circuit board can be fixed in place, as described above, using mechanical fixing or adhesive.

[0040] When solder paste is used as a connecting element, it can be applied to one or both printed circuit boards (PCBs). The two PCBs can then be positioned relative to each other. Applying heat melts the solder paste, thus establishing electrical and mechanical contact between the two PCBs. To connect the two PCBs in this way, the solder paste must be applied immediately before joining to prevent contamination.

[0041] When solder paste is used as a bonding element in reflow soldering, it can be applied before the flexible printed circuit board (PCB) is joined to the rigid PCB. In this process, the solder paste is applied to the rigid PCB, heated, and then cooled. As a separate step, flux can then be added to the already "soldered" surface to facilitate remelting. After adding the flux, the flexible PCB can be positioned on the rigid PCB. When heated, the solder paste melts. After the two PCBs cool, they are joined in the same way as if solder paste were used alone.

[0042] Alternatively, the two circuit boards can be soldered together using solder as the connecting element. In this method, solid solder material can be used, which facilitates a simple connection of the two circuit boards. Brief description of the drawings

[0043] Exemplary embodiments of the invention are shown in the drawings and explained in more detail in the following description. They show: Fig. 1 a schematic view of a coil device for a proximity sensor according to a first embodiment; Fig. 2A, Fig. 2B an example of a flexible printed circuit board of the coil device in Fig. 1; Fig. 3A, Fig. 3B further examples of flexible printed circuit boards in Fig. 1; Fig. 4A, Fig. 4B is another example of the flexible printed circuit board in Fig. 1; Fig. 5 another example of the flexible printed circuit board in Fig. 1 in top view; Fig. 6 another example of the flexible printed circuit board in Fig. 1 in top view; Fig. 7 a perspective view of another example of the flexible printed circuit board in Fig. 1; Fig. 8 the flexible circuit board in Fig. 7 with a core element and a shell; Fig. 9A, Fig. 9B a first and second side of an exemplary rigid printed circuit board in Fig. 1 in top view; Fig. 10A, Fig. 10B a first and second side of another exemplary rigid printed circuit board in Fig. 1 in top view; Fig. 11A, Fig. 11B an example of the coil device in Fig. 1 in section and as an enlarged section view; Fig. 12 a first side of another exemplary rigid printed circuit board in Fig. 1 in top view; Fig. 13A, Fig. 13B an example of the coil device in Fig. 1 in section and as an enlarged section view; Fig. 14 a method according to an embodiment for manufacturing a coil device in Fig. 1; and Fig. 15 a block diagram for an assembly of components for use in the procedure in Fig. 14. Embodiments of the invention

[0044] Identical or similar components or elements are marked with the same reference numerals.

[0045] One in Fig. A coil device, designated with reference numeral 10 and suitable for a proximity sensor 11, according to one embodiment, has a flexible printed circuit board 12, which is either completely rolled several times around a rolling axis R or completely folded several times around a folding axis F, and on which a conductor track 14 is arranged. The conductor track 14 forms a coil. The printed circuit board 12 is electrically connected to a rigid printed circuit board 18 by means of an electrical connecting element 16 such that a first end region 20 of the conductor track 14 and a second end region 22 of the conductor track 14 are coupled to the rigid printed circuit board 16 by means of the connecting element 16. Several electronic components 24 are arranged and contacted on the rigid printed circuit board 18 to enable, for example, a power supply to the conductor track 14 and / or an evaluation of a voltage induced in the conductor track 14.For the sake of clarity, only one component is marked with the reference number 24.

[0046] The connecting element 16 is designed as an FPC connector. For this purpose, the end sections 20, 22, bent from a coil plane, are inserted into corresponding slots of the FPC connector 16. The coil plane runs perpendicular to the axis R, F. The FPC connector 16 is inserted into the rigid circuit board 18 by means of pins.

[0047] The in Fig. 2A, Fig. The uncoiled or unfolded printed circuit board 12 shown in Figure 2B has an elongated central region 28 (partially shown), the two end regions of which are each formed as flags 30a, 30b and extend approximately perpendicular to the central region 28. The flags 30a, 30b widen in diameter towards their ends compared to the central region 28. Three conductor tracks 14a-14c extend from their respective first end regions 20a-20c along the flag 30a and the central region 28 to their second end regions 22a-22c on the flag 30b on a common outer surface A of the printed circuit board 12. The ends of the end regions 20a-20c, 22a-22c are designed as contact points with an enlarged surface area relative to the diameter of the conductor track 12.

[0048] It is also possible that the circuit board has 12 in Fig. 2A, Fig. 2B is multilayered. In a first outer layer, only the conductor track 14a is structured. In a second conductive layer, which is located inside the circuit board 12 beneath the outer layer and electrically insulated from it, the conductor track 14b is formed. In a third conductive layer, which is located inside beneath the second layer and electrically insulated from it, the conductor track 14c is formed. The conductor tracks 14b and 14c are connected to the conductor track 14a via corresponding vias.

[0049] The in Fig. 3A, Fig. The two examples of circuit board 12 shown in 3B are similar to circuit board 12 in Fig. 2A, Fig. 2B are formed and differ from this only in that the conductor tracks 14a-14c in the central area 28 are not straight, but wavy ( Fig. 3B) or in a zigzag shape ( Fig. 3B).

[0050] In the Fig. 4A, Fig. 4B shows the example of circuit board 12, which is similar to circuit board 12 in Fig. 2A, Fig. In the 2B configuration, each conductor track 14a-14c has one strand in its end region 20a, 20b, 20c, 22a, 22b, 22c. In contrast to the conductor tracks 14a-14c, each of the conductor tracks 14a-14c fans out into Fig. 2A, Fig. 2B splits into three strands in the area of ​​the flag 30a, 30b towards the central area 30, so that in the central area 28 of the circuit board 12 nine conductor strands 34a-34c, 36a-36c, 38a-38c run. The branching is designed such that a conductor strand 34a-34c, 36a-36c, 38a-38c splits off at an acute angle from each adjacent conductor strand 34a-34c, 36a-36c, 38a-38c.

[0051] Alternatively, the nine-strand coil can be formed by dividing the circuit board into Fig. 4A, Fig. 4B is multilayered. In a first outer layer, the end regions 20a-20c, 22a-22c, as well as the strands 34a, 36a, 38a, are structured. In a second conductive layer, which is arranged inside the circuit board 12 beneath the outer layer and electrically insulated from it, the strands 34b, 36b, 38b are formed, each extending from the central region 28 to the fanning points in Fig. 4A, Fig. 4B. In a third conductive layer, which is arranged internally beneath the second layer and electrically insulated from it, the strands 34c, 36c, 38c are formed, each extending from the central region 28 to the fanning points in Fig. 4A, Fig. 4B. Strands 34b, 36b, 38b and 34c, 36c, 38c are connected to strands 34a, 36a, 38a via corresponding vias.

[0052] As in Fig. 5 and Fig. As shown in Figure 6, a cross-section of the rolled-up or folded circuit board 12 running perpendicular to the rolling axis R or folding axis F can be round ( Fig. 5) or square ( Fig. 6) be formed. Alternatively, the cross-section can be oval or rectangular. The flexible printed circuit board 12 can be held in its rolled-up or folded position either mechanically with clamps 40 or by means of an adhesive 42. The mechanical clamps are provided at end regions 44a, 44b of the printed circuit board 12. The conductor track 14 runs on the outer surface A of the rolled-up flexible printed circuit board 12. The adhesive 42 is applied to an inner surface B of the flexible printed circuit board 12, so that the conductor track 14 lies under the adhesive 42 in the overlapping area of ​​the printed circuit board 12. The rolled-up or folded printed circuit board forms a coil 46. The printed circuit board 12 or conductor track 14 can be rolled up or folded with several turns, so that the coil 46 formed by the conductor track 14 has several turns.

[0053] In Fig. Figure 7 shows the rolled-up circuit board 12 together with the flags 30a, 30b in perspective view. The conductor track (not shown) runs on the outer surface A of the circuit board 12.

[0054] In Fig. 8 Inside the coil 46, in the plane of the coil, a plate-shaped, round core element 52 is arranged, which comprises a hard magnetic ferromagnetic material (in particular a ferrite). Furthermore, a sheath 54, which also comprises the same ferromagnetic material, encloses the coil 46 formed from Fig. 7. The sheath 54 has a side element 55a that covers the outer surface A of the flexible circuit board 12. Furthermore, the sheath 54 has an annular cover element 55b that covers one end of the coil 46. The height of the core element 52 is dimensioned such that the cover element 55b and the core element are flush with each other. The core element 52 and the sheath 54 are formed in one piece. In the area of ​​the bending points of the tabs 30a, 30b, the core element 52 has a recess 56a, 56b, through which one of the tabs 30a, 30b extends perpendicularly from the plane of the coil. The cover element 55b is arranged on the same side of the coil 46 as the tabs 30a, 30b.

[0055] Fig. 9A, Fig. Figure 9B shows a first side C and a second side D of an exemplary rigid printed circuit board 18, which is connected to a flexible printed circuit board 12 (not shown) having five parallel conductor tracks 14a-14e. The end regions 20a-20e and 22a-22e of the conductor tracks 14a-14e are soldered to corresponding contact points 60a-60e and 62a-62e on the printed circuit board 18 by means of a connecting element 16 in the form of solder paste. The contact points 60a-60e, 62a-62e are in turn connected by means of vias 64a-64d, 66a-66d provided on the rigid printed circuit board 18, so that the five coils formed by the five conductor tracks 14a-14e on the flexible printed circuit board 12 are connected in series and form a single composite coil. A coil end 66a, 66b, which is arranged on each side C, D of the printed circuit board 18, can be used to contact the component 24.

[0056] The in Fig. 10A, Fig. The example of the rigid printed circuit board 18 shown in 10B is similar to the example in Fig. 9A, Fig. 9B is formed. However, only three vias 64a-64c are present, which (viewed from the left) connect the first conductor 14a to the second and third conductors 14b, 14c, and the fourth conductor 14d to the fifth conductor 14e. Consequently, two composite coils are formed by contacting the rigid circuit board 18, each electrically isolated from the other. Corresponding coil ends 66a, 66b and 68a, 68b of the first and second coils, respectively, are structured on the rigid circuit board.

[0057] It is also possible to connect the end 66b of the first coil on side D to the end 68a of the second coil on the second side C of the rigid circuit board 18, or the end 68b of the second coil on the first side D to the end 66a of the first coil on the second side C. Such a circuit would create a common coil with three terminals, which could be used, for example, in a Hartley oscillator.

[0058] At the in Fig. 11A, Fig. In the embodiment of the coil device 10 shown in Figure 11B, the rigid printed circuit board 18 is arranged perpendicular to the plane of the coil, intersecting the rolled or folded flexible printed circuit board 12, and along the axis R, F. A longitudinal extension of the rigid printed circuit board 18 thus runs parallel to, or in the direction of, the axis R, F of the printed circuit board 12. The tabs 30a, 30b are bent at an acute angle out of the plane of the coil, while the end regions of the tabs 30a, 30b are bent towards the rigid printed circuit board 18 and arranged parallel to it. To connect the circuit board 12 with the rigid circuit board 18, solder 16a,16b is provided as a connecting element, which is provided between a copper contact point 60, 62 on each side C, D of the rigid circuit board 18 and the ends 20, 22 on the flexible circuit board 12.

[0059] At the in Fig. In the example shown in Figure 12 of the rigid printed circuit board 18, contact points 60a-60e and 62a-62e are arranged on one side C, to which the end regions 20a-20e and 22a-22e of the conductor tracks 14a-14e are coupled. The conductor tracks 14a-14e thus form a series-connected coil. The contact points 60b, 62a and 60c, 62b and 60d, 62c and 60e, 62d, respectively, are connected to each other by means of conductor strands 70a-70d structured on the rigid printed circuit board 18. Vias 64a, 64b connect the assembled coil to electronic components 24, which are arranged on the other side of the rigid printed circuit board 18.

[0060] At the in Fig. 13A, Fig. In the embodiment of the coil device 10 shown in Figure 13B, the flexible circuit board 12 and the rigid circuit board 18 are arranged parallel to each other. In other words, the axis R, F runs perpendicular to the rigid circuit board 18. The tabs 30a, 30b are folded such that they are bent twice at a right angle to the circuit board 12 and then run parallel to the flexible circuit board 12. The connecting element 16a, 16b, in the form of solder, is soldered between the corresponding contact points 60a, 60b on the rigid circuit board 18 and the end regions 20, 22 of the conductor track 14. The end regions 20, 22 are designed as solder contacts in this case.

[0061] At the in Fig. In the manufacturing process shown in Figure 14 for producing a coil device 10 for a proximity sensor 11, a flexible printed circuit board 12 is provided in a first step S1, on which a conductor track 14 is arranged. The printed circuit board 12 is rolled up completely once or several times around a rolling axis R or folded completely once or several times around a folding axis F, such that the printed circuit board 12 and the conductor track 14 form a coil 46. In a second step S2, a rigid printed circuit board 18 is provided. In a further process step S3, an electrical connecting element 16 is provided. In a subsequent process step S4, the flexible printed circuit board 12 is connected to the rigid printed circuit board 16 such that a first end region 20 and a second end region 22 of the conductor track 14 are electrically connected to the rigid printed circuit board 18 by means of the connecting element 16.

[0062] Steps S1-S3 can be performed in any order.

[0063] In Fig. Figure 15 illustrates that the coil device 10 can be modularly formed from three components: a coil component 90, a connecting element component 92, and a configuration printed circuit board component 94. Coil components 90 can represent different types of printed circuit boards 12 with conductor tracks 14, such as those found, for example, in Fig. Sections 2A to 8 are described. Three coil components 90a-90c are shown as examples. For connecting element components 92a, 92b, a connecting element in the form of solder or solder paste (reference 92a) or a connecting element 16 in the form of an FPC connector (reference 92b) can be selected. Then, a desired rigid printed circuit board 18 can be selected as a configuration printed circuit board component 94a-94e, as is the case, for example, in Fig.9A-13B are described. In this way, proximity sensors 11 can be built in a particularly simple modular fashion. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2008 012 120 B4

[0004] DE 10 2019 115 405 A1

[0004]

Claims

[1] Coil device (10) for a proximity sensor (11), comprising: - a flexible printed circuit board (12) on which a conductor track (14) is arranged, having a first end region (20) and a second end region (22), wherein the flexible printed circuit board (12) is rolled up around a roll axis (R) or folded around a fold axis (F) such that the conductor track (14) forms a coil (46); - a rigid printed circuit board (18) for connecting at least one electronic component (24), and - an electrical connecting element (16), wherein the first end region (20) and the second end region (22) are each electrically connected to the rigid printed circuit board (18) by means of the electrical connecting element (16). [2] Coil device (10) according to claim 1, wherein the connecting element (16a, 16b) comprises solder or solder paste. [3] Coil device (10) according to claim 1, wherein the connecting element (16) has at least one FPC connector. [4] Coil device (10) according to one of the preceding claims, wherein the rolling axis (R) or folding axis (F) of the flexible printed circuit board (12) runs substantially parallel to an extent of the rigid printed circuit board (18). [5] Coil device (10) according to one of claims 1 to 4, wherein the rolling axis (R) or folding axis (F) of the flexible printed circuit board (12) extends substantially transversely, in particular perpendicularly, to an extent of the rigid printed circuit board (16). [6] Coil device (10) according to one of claims 1 to 5, wherein a contact point (60a-60e) for the first end region (20) of the conductor track (14) is arranged on one side (C) of the rigid printed circuit board (18) and a contact point (62a-62e) for the second end region (22) of the conductor track (14) is arranged on a second side (D) of the rigid printed circuit board (18). [7] Coil device (10) according to one of claims 1 to 5, wherein contact points (60a-60e, 62a-62b) for the first and second end region (20, 22) of the conductor track (14) are arranged on one side (C) of the rigid printed circuit board (18), wherein a contact point for the at least one electronic component (24) is arranged on a second side of the rigid printed circuit board (18). [8] Coil device (10) according to one of the preceding claims, wherein at least a second conductor track (14a-14e) is arranged on the flexible circuit board (12) which has a first end region (20a-20e) and a second end region (22a-22e), wherein the conductor track (14a-14e) and the at least second conductor track (14a-14e) are substantially adjacent to each other, in particular parallel, wherein the at least second conductor track (14a-14e) forms an at least second coil (46). [9] Coil device (10) according to one of the preceding claims, wherein the first (20a-20e) and second end region (22a-22e) of the conductor track (14a-14e) and the first (20a-20e) and second end region (22a-22e) of the at least second conductor track (14a-14e) are electrically connected to the rigid circuit board (18) such that the first coil (46) and at least second coil (46) are electrically separated coils (46). [10] Coil device (10) according to any one of claims 1 to 8, wherein the first (20a-20e) and second end region (22a-22e) of the conductor track (14a-14e) and the first (20a-20e) and second end region (22a-22e) of the at least second conductor track (14a-14e) are electrically connected to the rigid circuit board (18) such that the first coil (46) and second coil (46) are split coils (46). [11] Coil device (10) according to one of claims 1 to 8, the first (20a-20e) and second end region (22a-22e) of the conductor track (14a-14e) and the first (20a-20e) and second end region (22a-22e) of the at least second conductor track (14a-14e) are electrically connected to the rigid circuit board (18) such that the first coil (46) and second coil (46) are connected in series. [12] Coil device (10) according to one of the preceding claims, wherein the coil device (10) further comprises a core element (52) comprising a ferromagnetic material, in particular ferrite, wherein the core element (52) is arranged in an interior of the coil (46) in a coil plane. [13] Coil device (10) according to one of the preceding claims, wherein the flexible printed circuit board (12) has two flags (30a, 30b) extending parallel to the roll axis (R) or fold axis (F), wherein the end regions (20, 22) of the conductor track (14) are arranged on each of the other two flags (30a, 30b). [14] Coil device (10) according to one of the preceding claims, wherein a cross-section of the coiled or folded flexible printed circuit board (12) extending transversely, in particular perpendicularly, to the rolling axis (R) or folding axis (F) is round, oval, rectangular or square. [15] Coil device (10) according to one of the preceding claims, wherein the conductor track (14) runs in a straight, corrugated or zigzag pattern on the flexible circuit board (12). [16] Coil device (10) according to one of the preceding claims, wherein the flexible printed circuit board (12) is multilayered, wherein the conductor track (14) is arranged in a first layer of the flexible printed circuit board, wherein a second conductor track is arranged in at least a second layer of the flexible printed circuit board, wherein end regions of the first and second conductor track are arranged on an outer surface of the flexible printed circuit board (12) by means of vias. [17] Coil device (10) according to one of the preceding claims, wherein the conductor track (14) is formed with at least two strands in its central region. [18] Proximity sensor (11) with a coil device (10) according to any one of claims 1 to 17, wherein the proximity sensor (11) is an inductive proximity switch or an inductive distance sensor. [19] Method for manufacturing a coil device (10) for a proximity sensor (11), comprising the steps: - Providing (S1) a flexible printed circuit board (12) on which a conductor track (14) is arranged having a first end region (20) and a second end region (22), wherein the flexible printed circuit board (12) is rolled up around a roll axis (R) or folded around a fold axis (F) such that the conductor track (14) forms a coil (46); - Providing (S3) a rigid printed circuit board (18) for electrically connecting at least one electronic component (24), - Provide (S2) to an electrical connecting element (16), and - electrical connection (S4) of the first end area (20) and the second end area (22) to the rigid printed circuit board (18) by means of the electrical connecting element (16).

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