Sensor

Abstract

A sensor comprising at least one NFC coil arranged in a cylindrical casing partially surrounding a first circuit board of the sensor. A coil for contactless energy transfer is arranged in the casing, extending over 360° of the circumference of the casing, magnetically orthogonal to the at least one NFC coil. A cylindrical flux guide (23) comprising at least one ferromagnetic material is arranged between the first circuit board (10) and the coil for contactless energy transfer. A cylindrical spacer (22) is arranged between the flux guide (23) and the coil for contactless energy transfer.

Description

[0001] The present invention relates to a sensor. State of the art

[0002] Sensors such as pressure sensors, temperature sensors, or flow sensors require a display on their housing for parameterization. Although this display is only required once, it represents a significant cost factor for the sensor. Because the display remains permanently attached to the sensor housing, there is also a risk that sensor parameters may be subsequently and inadvertently adjusted unless a key lock on the display has been activated.

[0003] In principle, it would be possible to parameterize sensors wirelessly, for example, using Bluetooth. However, this would open the door to external sabotage, which is why such technologies are not widely accepted in industries such as the automotive industry, the food industry, and machine tool manufacturing.

[0004] DE 10 2021 129 736 A1 describes a sensor with a sensor module and an evaluation module, which are wirelessly connected via an NFC radio unit. This makes it possible to separate the evaluation module, which can also be used for parameterization, from the sensor module. However, this requires a planar surface to accommodate the planar NFC antenna to be attached to the sensor module housing. Since sensors for automation technology are typically arranged in circular-cylindrical housings, this requires an unusual housing design.

[0005] DE 10 2019 211 607 A1 describes a measuring device with at least one communication device configured for wireless short-range communication with a mobile operating device. The communication device comprises one or more flat coil elements configured for electromagnetic coupling with at least one coil element of the operating device. At least two regions are provided on a coil element or on different coil elements of the communication device, each region having a different normal vector.

[0006] It is an object of the present invention to provide a sensor that can be wirelessly connected by means of NFC to a display device that can be arranged on a circular cylindrical housing of the sensor. Disclosure of the invention

[0007] This object is achieved by a sensor with a cylindrical, in particular circular-cylindrical, casing, which partially surrounds a first circuit board of the sensor. The first circuit board is provided, in particular, to contact a sensor element of the sensor, for example a pressure sensor element, a temperature sensor element, or a flow sensor element. It can be equipped with an electronic control element configured to control the sensor element. At least one NFC coil is arranged in the cylindrical casing. By arranging the NFC coil in the casing and thus the outer surface of the sensor, it is not necessary to attach a separate planar element, which has an NFC coil, to the sensor housing.In addition, wireless contacting of the sensor is enabled via NFC (Near Field Communication), particularly over 360° of the circumference of the sensor housing, so that communication with the sensor for reading data and / or parameterization is easily possible regardless of its spatial orientation.

[0008] It is preferred that the casing comprises a cylindrical, in particular circular-cylindrical, coil substrate. This can be, for example, a technical textile that supports wires of the at least one NFC coil. However, the coil substrate is particularly preferably a second circuit board. This is most preferably embodied as a flexible circuit board that has been bent into the cylindrical shape.

[0009] In a first preferred embodiment of the sensor, a first NFC coil is arranged in a first 180° section of the second circuit board. A second NFC coil is arranged in a second 180° section of the second circuit board. These two NFC coils are, in particular, frame-shaped. In such an arrangement, one of the NFC coils dominates over an NFC communication partner in every spatial position and can establish an electromagnetic coupling sufficient for reliable communication. It is preferred that the sensor has a multiplexer configured to switch between the two NFC coils so that NFC communication takes place only via the dominant NFC coil.

[0010] In another preferred embodiment of the sensor, the NFC coil runs in a ring around the first circuit board. Such an NFC coil preferably has 6 to 12 turns. It is, in particular, wound from enameled wire, bent from spring steel, or implemented as a self-bonding coil.

[0011] The first circuit board is preferably arranged in a cylindrical metal carrier. This carrier preferably comprises a non-ferromagnetic metal, particularly preferably brass. In particular, it is made of this metal. Furthermore, its thickness is preferably in the range of 0.30 mm to 0.50 mm. The carrier acts as a carrier for the NFC coil, directly or indirectly via additional elements arranged between the carrier and the NFC coil. It also electromagnetically shields the first circuit board.

[0012] If a display device communicating with the sensor via the NFC coil does not have its own power source, electrical energy transfer from the sensor to the display device may be necessary for its parameterization. For this purpose, the sensor further comprises a coil for contactless energy transfer in the casing, which extends over 360° of the circumference of the casing. This coil is arranged magnetically orthogonal to the at least one NFC coil. This enables inductive electrical energy transfer between the display device and the sensor and prevents interference with NFC communication caused by this energy transfer. The coil for contactless energy transfer is preferably designed as a radial double-D coil. It can be implemented in particular as a bipolar coil or with a center tap.

[0013] A cylindrical, in particular circular-cylindrical, flux guide comprising at least one ferromagnetic material, in particular consisting of at least one ferromagnetic material, is arranged between the first circuit board and the coil for contactless transmission. The ferromagnetic material is preferably a soft magnetic material. The flux guide directs the electromagnetic field of the coil for contactless energy transmission outwards, so that few losses occur during energy transmission. A cylindrical, in particular circular-cylindrical, spacer is arranged between the flux guide and the coil for contactless energy transmission. This spacer preferably comprises at least one electrical insulator, more preferably at least one plastic, and most preferably consists of at least one plastic.It minimizes eddy current losses that could be caused by the flux guide in the coil for contactless energy transfer. The thickness of the flux guide is preferably in the range of 0.10 to 0.20 mm, and the thickness of the spacer is preferably in the range of 0.50 to 1.50 mm.

[0014] The first circuit board and the casing are preferably enclosed by a cylindrical, in particular circular-cylindrical, housing. This housing has a groove, in particular annular, surrounding the housing in the area of ​​the casing. This groove can be used to arrange a display device on the sensor. Furthermore, it can indicate to a user where an NFC-enabled smartphone can be held against the sensor in order to use it instead of the display device to configure the sensor. Short description of the drawings

[0015] Embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description. Fig. 1a shows a side view of a circuit board with a casing in a first embodiment of the sensor according to the invention. Fig. 1b shows an isometric view of a circuit board with a casing in a first embodiment of the sensor according to the invention. Fig. 1c shows another isometric view of a circuit board with a casing in a first embodiment of the sensor according to the invention. Fig. 1d shows an exploded view of a circuit board with a casing in a first embodiment of the sensor according to the invention. Fig. 2 schematically shows an arrangement of coils in a casing in a sensor according to a first embodiment of the invention. Fig. 3 shows a diagram of the induced voltage characteristics of NFC coils of a sensor according to a first embodiment of the invention. Fig. 4 shows an isometric view of a sensor according to a first embodiment of the invention and a display device. Fig. Figure 5 shows schematically an arrangement of coils in a display device. Fig. 6 shows a schematic circuit diagram of essential elements of a sensor according to a first embodiment of the invention and a display device. Fig. 7 shows a schematic circuit diagram of the communication of a sensor according to the first embodiment of the invention with a smartphone. Fig. 8 shows a side view of a circuit board with a casing of a second embodiment of the sensor according to the invention. Fig. 8b shows an isometric view of a circuit board with a casing of a second embodiment of the sensor according to the invention. Fig. 8c shows another isometric view of a circuit board with a casing of a second embodiment of the sensor according to the invention. Fig. 8d shows an exploded view of a circuit board with a casing of a second embodiment of the sensor according to the invention. Embodiments of the invention

[0016] A sensor according to a first embodiment of the invention has in its housing a first circuit board 10 which is surrounded by a casing 20. This is shown in the Fig. 1a to 1d. The first circuit board 10 is contacted on its surface 11 by an electrical connector 12, which is intended to serve as an interface, for example, to an IO-Link system. At the end of the surface 11 opposite the connector 12, electrical contacts 13 are arranged for contacting a sensor element (not shown). These can be used, for example, to connect a pressure sensor element, a temperature sensor element, or a flow sensor element. The casing 20 is circular-cylindrical. It is dimensioned such that the connector 12 protrudes from one end of the casing 20 and the electrical contact elements 13 protrude from the other end of the casing 20. It consists of four circular-cylindrical elements 21 to 24, which are plugged into one another.The outer element is a second circuit board 21, which is designed as a flexible circuit board bent into a circular cylindrical shape. The second circuit board 21 has four levels and its thickness is, for example, 0.32 mm. A circular cylindrical spacer 22 is arranged in the second circuit board 21. This has, for example, a thickness of 1.25 mm and is made of a plastic. At its end facing the electrical contact elements 13, the spacer 22 has a radially projecting edge that covers the edge of the second circuit board 21. A circular cylindrical flux guide 23 is arranged in the spacer 22, which is made, for example, of a 1.15 mm thick soft magnetic material, such as soft iron. A circular cylindrical carrier 24 is arranged in the flux guide 23, which is, for example, 0.40 mm thick and is made of brass.An electronic control element 14 on the surface 11 of the first circuit board 10 is electrically connected to the second circuit board 21 by means of an electrical connecting element 15 through openings in the carrier 24, the flux guide 23, and the spacer 22. A solder connection 16 connects the surface 11 of the first circuit board 10 to the carrier 24. This fixes the carrier 24 and thus the entire casing 20 in a defined position relative to the first circuit board 10. In addition, an electrical connection is established between the carrier 24 and the first circuit board 10, which makes it possible to ground the carrier 24 via the electrical connector 12.

[0017] Fig. 2 shows a planarized representation of the circular-cylindrical second circuit board 21. A first NFC coil 31, which is arranged in a first plane of the second circuit board 21, is designed with a frame winding. It extends over half the length of the second circuit board 21 and thus, in its cylindrically bent state, over 180° of its outer surface. A second NFC coil 32 is arranged in the second plane of the second circuit board 21. It is also designed with a frame winding and has the same dimensions as the first NFC coil 31. It extends over the other half of the length of the second circuit board 21 and thus, in its cylindrically bent state, also over 180° of its outer surface. A coil 33 for contactless energy transmission is arranged in a third and fourth plane of the second circuit board 21. This coil is designed as a radial double-D coil.It extends over the entire length of the second circuit board 21 and thus, in its cylindrically bent state, over 360° of its outer surface.

[0018] The two NFC coils 31, 32 enable contactless NFC communication with a display device intended for reading sensor data and for parameterizing the sensor. Fig. Figure 3 shows the induced voltage U of the two NFC coils 31, 32 over the entire angular range α of the circumference of the casing 20. It can be seen that in each angular range, one of the coils always dominates, ensuring reliable NFC communication.

[0019] Fig. 4 shows the sensor 40 according to the first embodiment of the invention together with a display device 50 that is configured to be coupled thereto. The sensor 40 has a circular-cylindrical housing 41 in which the first circuit board 10 and its casing are arranged. In the area where the casing 20 borders the inside of the housing 41, the housing has an annular circumferential groove 42. A first connection element 43 is arranged at the end of the housing 41 facing the connector 12. It enables a wired electrical connection to the connector 12 to be fixed by means of a screw connection. A second connection element 44 is arranged at the other end of the housing 41. This makes it possible to fix a connection between the electrical contact elements of the circuit board and a sensor element by means of a screw connection.

[0020] The display device 50 has a touch display 51 to enable parameters of the sensor 40 to be read and changed using the display device. A coupling element 52 with a semicircular cylindrical inner contour is arranged on the touch display 51. This coupling element is designed to be inserted into the groove 42 of the housing 41 of the sensor 40.

[0021] An NFC coil 34 and a coil 35 for contactless energy transmission are arranged in the coupling element 52. Fig. 5 shows the arrangement of the two coils 34, 35 in a planarized representation of the coupling element 52. The NFC coil 34 has a frame winding and extends over half the length of the planarized coupling element 52. It thus covers 90° of the outer surface of the groove 42 when the display device 50 has been connected to the sensor 40. While the NFC coil 34 is arranged in one plane of the coupling element 52, a coil 35 designed as a radial double-D coil for contactless energy transmission extends over the entire length of two further planes of the planarized coupling element 52. When the display device 50 is coupled to the sensor 40, this coil covers 180° of the outer surface of the groove 42. This enables NFC communication between the NFC coil 34 of the display device 50 and one of the NFC coils 31, 32 of the sensor 40.Furthermore, electrical energy transfer is enabled between coil 35 of display device 50 and coil 33 of sensor 40. The NFC coils 31, 32, 34 are arranged magnetically orthogonally to the coils 33, 35 for electrical energy transfer and are thus decoupled from them.

[0022] Fig. Figure 6 shows the interaction of the sensor 40 with the display device 50. A Royer oscillator 61 in the sensor 40, which is arranged on the first circuit board 10, is connected to the coil 33. A second Royer oscillator 71 of the display device 50 is connected to the coil 35. This enables electrical energy to be transferred from the sensor to the display device 50 via the two Royer oscillators 61, 71 in the manner shown in Fig. 6. A tag 62, a CMOS multiplexer 63, and two diodes 64, 65 of a diode circuit are arranged in the electrical control element 14 of the sensor 40. The first diode 64 is connected to the first NFC coil 31, and the second diode 65 is connected to the second NFC coil 32. Depending on which of the two NFC coils 31, 32 dominates based on the positioning of the display device 50 on the sensor 40, the multiplexer 63 switches between the two NFC coils 31, 32 using the diodes 64, 65. The dominant NFC coil is identified by the fact that it has a higher rectified input voltage than the non-dominant NFC coil. The NFC coil 34 of the display device 50 is connected via a network 73 to a reading device 72 of the display device 50 and thus enables bidirectional communication of the touch display 51 via the NFC coils 31, 32, 34 with the sensor 40 in the Fig. 6 shown arrow direction.

[0023] Instead of the display device 50, an NFC-enabled smartphone 80 can also be used for bidirectional communication with the sensor 40. This is Fig. 7. In this case, NFC communication of the smartphone 80 via one of the NFC coils 31, 32 with the sensor 40 in the Fig. 7, without any energy transfer between the smartphone 80 and the coil 33 of the sensor 40. To do this, it is sufficient to hold the smartphone 80 near the housing 41. If the sensor 40 is not powered, however, active switching between the two NFC coils 31, 32 is not possible, so the position of the smartphone 80 may have to be changed to enable communication with the last active NFC coil 31, 32.

[0024] In a second embodiment of the sensor 40 according to the invention, the casing 20 differs from that of the first embodiment. While the second circuit board 21, as in the first embodiment, has a coil 33 for electrical energy transmission, no NFC coils 31, 32 are arranged in the second circuit board 21.

[0025] As in the Fig.8a to 8d, instead, a single NFC coil 36 is arranged between the second circuit board 21 and the spacer 22. This NFC coil 36 has, for example, an inner diameter of 18.5 mm, a wire diameter of 0.3 mm, and nine turns. It runs in a ring around the spacer 22. For this purpose, a groove is provided in the spacer 22, which accommodates the NFC coil 36. While the coil 33 for electrical energy transmission is connected to the electrical control element 14 via the electrical connection 15, as in the first exemplary embodiment, the wire of the NFC coil 36 is led out of the casing 20 parallel to the longitudinal axis of the latter and is electrically connected to the circuit board 10 in a manner not shown.

[0026] Since the sensor 40 according to the second embodiment has only one NFC coil, it requires neither the multiplexer 63 nor the two diodes 64, 65 of the diode circuit to switch between multiple NFC coils. NFC communication between the sensor 40 and a display device 50 or a smartphone 80 always takes place via the annular NFC coil 36. This communication can also take place in the manner described for the first embodiment, and the display device 50, which was described in connection with the first embodiment of the sensor 40, can be used in the same way with a sensor 40 according to the second embodiment. When communicating with a smartphone 80, the advantage over the first embodiment is that, regardless of the positioning of the smartphone 80 relative to the sensor 40, a consistently good communication quality can always be achieved.

Claims

[1] Sensor (40) comprising at least one NFC coil (31, 32, 36) arranged in a cylindrical casing (20) which partially surrounds a first circuit board (10) of the sensor (40), characterized by in that a coil (33) for contactless energy transmission, which extends over 360° of the circumference of the casing (20), is arranged magnetically orthogonal to the at least one NFC coil (31, 32, 36), wherein a cylindrical flux guide (23) comprising at least one ferromagnetic material is arranged between the first printed circuit board (10) and the coil (33) for contactless energy transmission and a cylindrical spacer (22) is arranged between the flux guide (23) and the coil (33) for contactless energy transmission. [2] Sensor (40) according to claim 1, characterized by that the casing (20) is circular-cylindrical. [3] Sensor (40) according to claim 1 or 2, characterized bythat the casing (20) has a cylindrical second circuit board (21). [4] Sensor (40) according to claim 3, characterized by that a first NFC coil (31) is arranged in a first 180° section of the second circuit board (21) and a second NFC coil (32) is arranged in a second 180° section of the second circuit board (21). [5] Sensor (40) according to claim 4, characterized by that it has a multiplexer (63) which is arranged to switch between the two NFC coils (31, 32). [6] Sensor (40) according to one of claims 1 to 3, characterized by that the NFC coil (36) runs in a ring around the first circuit board (10). [7] Sensor (40) according to one of claims 1 to 6, characterized by that the first circuit board (10) is arranged in a cylindrical metal carrier (24). [8] Sensor (40) according to one of claims 1 to 7, characterized bythat the first printed circuit board (10) and the casing (20) are surrounded by a cylindrical housing (41) which has a groove (42) running around the housing (41) in the region of the casing (20).

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