Linear displacement sensor with at least one connecting circuit board and method for manufacturing a linear displacement sensor and for electrically and mechanically connecting a first and a second circuit board

Abstract

Linear displacement sensor with at least one connecting circuit board (2) and a first circuit board (4) and a second circuit board (6) for length scaling of circuit boards, wherein the first circuit board (4) is connected to the second circuit board (6) via the connecting circuit board (2), wherein the connecting circuit board is arranged for electrical and mechanical connection of the first circuit board (4) and the second circuit board (6), wherein the circuit boards (4, 6) are equipped with sensor elements (14), and the connecting circuit board (2) has conductor tracks (22) to establish a conductive connection between contact surfaces (18) of the first and second circuit boards (4, 6), wherein the connecting circuit board (2) is one-piece and rigid, wherein metal contacts (20) are arranged along an edge for connecting to the contact surfaces (18) of the first and second circuit boards (4, 6), and wherein the connecting circuit board (2), the first circuit board (4) and the second circuit board (6) are arranged parallel to each other, wherein the first and second circuit boards (4, 6) and the connecting circuit board (2) have positioning openings (8, 8', 10, 10') for aligning the circuit boards (4, 6) and connecting circuit board (2) with each other, wherein the metal contacts (20) are provided on semicircular recesses (12) at the edge of the connecting circuit board (2).

Description

[0001] The present invention relates to a linear displacement sensor with at least one interconnecting circuit board, the interconnecting circuit board consisting of several long, narrow circuit boards connected to the interconnecting circuit board. The circuit boards are equipped with sensor elements, for example Hall sensors, arranged in a fixed grid.

[0002] This design creates a linear displacement sensor with a sensor array. This sensor array can be extended as needed to produce additional linear displacement sensors. The desired length is achieved by connecting a specific number of individual circuit boards. To maintain a consistent, predetermined distance between the sensor elements across multiple circuit boards, the circuit boards must be precisely aligned and dimensionally accurate.

[0003] Electrical connectors are typically used to connect two printed circuit boards both electrically and mechanically. These connectors come in various designs, such as pin headers and sockets. The contacts of the connectors are arranged in a fixed grid, also known as the 'pitch'. The distance between the contacts can be less than 1 mm.

[0004] However, these connectors have the following disadvantages: They are large, meaning they are wide and tall, and protrude unfavorably beyond the edge of the circuit boards. Furthermore, the assembly tolerances are too large, resulting in the sensor elements no longer being equidistant. The connectors only provide a loose connection between the circuit boards, allowing the boards to shift. The connectors are also expensive.

[0005] A sensor with a connection arrangement of two printed circuit boards positioned perpendicular to each other is known from DE 198 38 218 A1. To connect the two printed circuit boards both mechanically and electrically, a first printed circuit board with protrusions is inserted into a second printed circuit board with corresponding cutouts during the manufacturing of the sensor. The two printed circuit boards are then soldered together on one side via solderable sections located at the joints.

[0006] Furthermore, a connection arrangement of two printed circuit boards, which are also perpendicular to each other, is also known from DE 10 2008 012 443 A1. In this arrangement, the openings in a first printed circuit board are not only provided with solderable contact points on the top and bottom surfaces of the first printed circuit board, but also externally via contact points on an edge surface of the first printed circuit board, so that the top and bottom surfaces are electrically connected to each other via these solderable contact points.

[0007] EP 2 166 313 A1 relates to a magnetic sensor for determining the position of a sensor magnet along a path. The sensor comprises several sensor elements and control electronics for receiving a sensor element signal from one of the sensor elements, with the sensor elements and the control electronics each being grouped into modules. The length of the sensors can be scaled depending on the number of modules. The modules, or rather the circuit boards of the modules, are interconnected.

[0008] US patent 6 407 930 B1 discloses an add-on board that is soldered onto a mainboard to change the function of the mainboard.

[0009] US 2004 / 0005790 A1 reveals an add-on board that is soldered onto a main board.

[0010] US 2007 / 0159181 A1 discloses interconnect circuit boards that connect two circuit boards together.

[0011] US Patent 2012127674 A1 discloses a semiconductor device assembly comprising elements such as electronic components and substrates connected by a fastener. The fasteners for holding such elements together comprise an elongated section, a first end piece, and a second end piece. Printed circuit boards (PCBs) comprise multiple openings arranged in a configuration corresponding to an arrangement of openings in a semiconductor device assembly. Each opening is sized and configured to accommodate a fastener for maintaining an assembly between the semiconductor device assembly and the PCB.

[0012] US 2907924 A discloses a module arrangement comprising a dielectric wafer with a pair of closely spaced parallel planar surfaces, a plurality of spaced connection elements attached to the wafer, wherein one of said connection elements is designed to be connected to ground.

[0013] US Patent 2008057743 A1 discloses a printed circuit board interconnect structure that facilitates the joining of multiple printed circuit boards and reduces costs. The interconnect structure comprises multiple printed circuit boards with an interconnection section pattern formed on a surface.

[0014] The task is to electrically and mechanically connect at least two printed circuit boards (PCBs) in such a way that the following requirements are met: Both boards must be fixed in the same plane without any offset to ensure sufficient measurement accuracy of the overall sensor with its sensor elements on different PCBs. The spacing of the sensor elements must therefore be constant across the PCBs; that is, the distance is always the same, both between adjacent sensor elements on one PCB and between the outermost sensor elements of two adjacent PCBs. This spacing must not change during or after the PCBs are connected.

[0015] The problem is solved by a linear displacement sensor comprising at least one interconnection circuit board and a first circuit board and a second circuit board for length scaling of circuit boards, wherein the first circuit board is connected to the second circuit board via the interconnection circuit board, wherein the interconnection circuit board is arranged for electrical and mechanical connection of the first circuit board and the second circuit board, wherein the circuit boards are equipped with sensor elements, and the interconnection circuit board has conductor tracks to establish a conductive connection between contact surfaces of the first and second circuit boards, wherein the interconnection circuit board is a single piece and rigid, wherein metal contacts are arranged along an edge for connecting to the contact surfaces of the first and second circuit boards, and wherein the interconnection circuit board, the first circuit board and the second circuit board are arranged parallel to each other.wherein the first and second circuit boards and the interconnecting circuit board have positioning openings for aligning the circuit boards and interconnecting circuit board relative to each other, wherein the metal contacts are provided on semicircular recesses at the edge of the interconnecting circuit board.

[0016] The problem is further solved by a method for manufacturing a linear displacement sensor and for electrically and mechanically connecting a first and a second printed circuit board with an interconnecting printed circuit board, wherein the printed circuit boards are equipped with sensor elements, and the interconnecting printed circuit board has conductor tracks to establish a conductive connection between the contact surfaces of the first and second printed circuit boards, the interconnecting printed circuit board, the first printed circuit board and the second printed circuit board are arranged parallel to each other, so that the rigid and one-piece interconnecting printed circuit board rests on both the first and the second printed circuit board, wherein metal contacts arranged at the edge of the interconnecting printed circuit board lie on the contact surfaces and are electrically conductive and mechanically rigidly connected to them.wherein, prior to soldering, the first and second circuit boards and the connecting circuit board are aligned relative to each other by means of positioning openings, the metal contacts being provided on semicircular recesses at the edge of the connecting circuit board.

[0017] The interconnecting board allows for a robust electrical and mechanical connection between two printed circuit boards (PCBs). This interconnecting board enables precise positioning of the first and second PCBs in the same plane, thereby increasing the measurement accuracy of the sensor elements. Multiple interconnecting boards can be used to create a chain of PCBs, with each connection point between PCBs being formed by an interconnecting board. This allows for simple and cost-effective length scaling of the sensor.

[0018] The rigid electrical and mechanical connection between the interconnecting circuit board and the circuit boards ensures a precise and permanent bond between them, eliminating any play. This maintains a constant distance between the sensor elements on the circuit boards.

[0019] The metal contacts are arranged along the edge of the interconnect circuit board. The metal contacts can be arranged on at least one side edge and additionally on at least one end edge. However, according to the invention, it is also possible for metal contacts to be provided only on at least one side edge.

[0020] The mechanically robust connection of the interconnecting circuit board allows the assembly of circuit boards to withstand increased shock and vibration loads. The interconnecting circuit board enables a simple, quick, and cost-effective connection of circuit boards.

[0021] Furthermore, the connection between the connecting circuit board and the circuit boards withstands large tensile and / or compressive forces due to the contact surfaces distributed along the edge.

[0022] According to the invention, the first and second printed circuit boards, as well as the interconnecting circuit board, have positioning openings for aligning the circuit boards and the interconnecting circuit board relative to each other. These positioning openings advantageously pre-position the interconnecting circuit board and the circuit board for a soldering process. This is achieved, for example, by a positioning pin of a positioning device precisely fitting into the positioning opening, thereby aligning the interconnecting circuit board and the circuit boards easily and automatically. After the interconnecting circuit board has been soldered to the circuit boards, the soldered circuit boards can be removed from the positioning device. Therefore, no additional components besides the interconnecting circuit board are required for positioning.

[0023] In a further development of the invention, the metal contacts of the interconnecting circuit board are connected to the contact surfaces of the circuit boards using solder or conductive adhesive. A connection with solder is inexpensive and can be made using common soldering methods. For example, the interconnecting circuit board can be connected to the circuit boards in an automated soldering process. While manual soldering is also possible, automated soldering is more cost-effective and potentially more precise. A connection with conductive adhesive has the advantage that the thermal stress on the circuit boards and the interconnecting circuit board is lower than with soldering, thus reducing thermal stresses.

[0024] In a further development of the invention, the connecting circuit board has a width of less than 20 mm, in particular less than 8 mm. In conjunction with circuit boards that are only slightly wider than the connecting circuit board, it is advantageously possible to house the circuit boards connected to the connecting circuit board in a narrow, elongated housing. For this purpose, the connected circuit boards are inserted longitudinally along one short side of the housing.

[0025] According to the invention, the metal contacts are provided in semicircular recesses at the edge of the circuit board. The metal contacts are formed on the top and bottom surfaces of the interconnect circuit board, as well as on the cross-sectional side of the interconnect circuit board in the area of ​​the semicircular recess. By arranging the metal contacts on the top and bottom surfaces, detachment of the contacts under mechanical stress, such as twisting, is prevented. Furthermore, the metal contacts allow the interconnect circuit board to be easily and cost-effectively soldered automatically or manually using standard soldering methods.

[0026] According to a particular embodiment, the interconnection circuit board has several layers of conductor tracks. This makes it possible to arrange the conductor tracks one above the other on a small area, thus enabling the interconnection circuit board to have a smaller surface area. Particularly preferably, individual layers, especially the top and / or bottom layer, can be metallized. This improves electrical interference immunity, for example, electromagnetic compatibility or grounding. This effectively prevents interference, such as coupling, on the conductor tracks of the interconnection.

[0027] In a further development of the invention, the interconnect circuit board incorporates electronic components. This makes it possible to influence the signals on the conductor tracks of the interconnect circuit board. For example, electronic circuit components for signal conditioning can be provided on the interconnect circuit board. Resistors or capacitors for impedance matching, as well as active semiconductor components, can be provided on the interconnect circuit board.

[0028] According to a particular embodiment, the height of the interconnecting circuit board is less than 2 mm, preferably less than 1 mm. This makes the interconnecting circuit board very compact. This thin design of less than 2 mm or less than 1 mm is possible because the circuit board, for example in a displacement sensor mounted on a pneumatic cylinder, is hardly subjected to any bending forces. Furthermore, the compact design allows the displacement sensor to be mounted directly in the cylinder housing. The displacement sensor is then integrated into the cylinder housing. Integrating the sensor into the cylinder housing allows the outer wall of the cylinder housing to be designed smoothly. This is particularly important for use in the food industry.

[0029] According to the invention, the connecting circuit board is used in a linear displacement sensor.

[0030] Linear displacement sensors, such as linear magnetic field sensors, have proven effective for precise position or displacement measurement through non-contact detection of the position of, for example, pneumatic or hydraulic pistons within a working cylinder. Guide grooves are provided on the outer surfaces of the working cylinder housing to mount the sensors, allowing for axial adjustment. The sensors can be locked in a desired position along the length of the groove using suitable means, such as screws.

[0031] The invention relates to extremely compact displacement sensors for piston position determination, as used on pneumatic cylinders of automated machines to detect the position of the cylinder piston. In such applications, installation space is crucial, as the displacement sensors interfere with the actual mechanical function of the machine but are essential for position determination. Therefore, the displacement sensor according to the invention is designed to have the smallest possible cross-section and to be manufactured in various lengths for displacement measurement, ranging from a few centimeters to over one meter. The displacement sensor can be manufactured in different lengths during production by means of the connecting circuit board. The sensors must also have a small installation space so that they can be integrated into cylinder housings.

[0032] The magnetic displacement sensor according to the invention for determining the position of a encoder magnet along a path comprises several Hall sensors connected to control electronics. The control electronics are configured to receive the control data for a Hall sensor to be activated serially and to activate the Hall sensors directly in parallel according to the control signal. This allows the Hall signal of the addressed Hall sensor(s) to be tapped by evaluation electronics on an analog Hall signal bus line, to which all Hall sensors are directly connected, and evaluated for the purpose of assessing the Hall signals and determining the position. An analog Hall signal bus line is understood to be a line to which the Hall sensors are directly connected in a bus-like manner, such that their analog Hall signals are present sequentially on the line.

[0033] The invention will now be explained in detail using exemplary embodiments and with reference to the drawing.

[0034] The drawing shows: Fig. 1 a schematic representation of a connecting circuit board according to the invention for electrically connecting a first and second circuit board; Fig. 2 a schematic representation of a displacement sensor according to the invention on a cylinder for measuring the position of a cylinder piston; Fig. Figures 3 to 6 show a schematic representation of the interconnection circuit board according to the invention in various views; Fig. 7 Two circuit boards and the connecting circuit board before soldering assembly Fig. 8 two circuit boards and the connecting circuit board after a soldered assembly

[0035] Fig. Figure 1 shows an interconnecting circuit board 2 for electrically and mechanically connecting a first circuit board 4 and a second circuit board 6, wherein the circuit boards 4 and 6 are equipped with sensor elements 14. The interconnecting circuit board 2 has conductive traces to establish a conductive connection between contact pads 18 of the first and second circuit boards 4 and 6. The interconnecting circuit board 2 is a single piece and rigid. Metal contacts 20 are arranged along an edge of the interconnecting circuit board 2 for connecting to the contact pads 18 of the first and second circuit boards 4 and 6. The interconnecting circuit board 2, the first circuit board 4, and the second circuit board 6 are arranged parallel to each other.

[0036] The sensor elements 14 are arranged at equal intervals from each other. These identical distances are also maintained at the connection point between the first circuit board 4 and the second circuit board 6. The uniform distances are necessary for the sensor function, for example, to enable precise position determination. The sensor elements 14 are, for example, designed as Hall sensors 16.

[0037] A in Fig. The magnetic displacement sensor 1 shown in Figure 2, according to the invention, serves to determine the position C of a sensor magnet 42 along a measuring section AB, wherein the sensor magnet 42 is mounted on a piston 44 of a working cylinder 46. Such working cylinders are used, for example, in automated machines, such as robots and the like, to detect piston positions when the piston 44 moves in the piston direction 48.

[0038] The displacement sensor 1 comprises individual sensor elements 14, which are designed as Hall sensors 16 or magnetoresistive sensors, abbreviated MR sensors, and are arranged along the measuring section AB. The Hall sensors 16 are connected to a control electronics unit 52 and, together with this unit and the first or second circuit board 4 or 6, are combined to form modules 54 or 26, respectively. Module 54 comprises evaluation electronics 30, preferably designed as a microcontroller.

[0039] All necessary data and supply voltages are supplied to the displacement sensor 1 according to the invention via a line 32, and position signals, which are determined in the evaluation electronics 30, are output.

[0040] Preferably, the Hall sensors 16 and the control electronics 52 are arranged on a first printed circuit board 4 and a second printed circuit board 6, respectively. The evaluation electronics 30 are arranged on the first printed circuit board 4. The first and second printed circuit boards 4 and 6 are connected to each other via the connecting circuit board 2 according to the invention such that the printed circuit boards are arranged parallel to each other, with the connecting circuit board 2 being arranged parallel to the printed circuit boards 4 and 6.

[0041] Fig. Figure 3 shows the interconnection circuit board 2 from a top view. Metal contacts 20 are arranged on the top side. The metal contacts of the interconnection circuit board are connected to the contact surfaces of the circuit boards with solder or conductive adhesive. The interconnection circuit board 2 has a rectangular shape, with a width of less than 20 mm or less than 8 mm. In this example, the interconnection circuit board 2 has a first positioning opening 6 and a second positioning opening 8. As already explained, the metal contacts are arranged along the edge of the interconnection circuit board. The metal contacts can be arranged on at least one side edge and additionally on at least one end edge. However, according to the invention, it is also possible to provide metal contacts only on at least one side edge, for example, if fewer electrical connections are required.

[0042] In this example, the metal contacts 20 have semicircular recesses 12 at their edges, which improve solder adhesion during soldering. The semicircular recesses are also provided with a metallized soldering surface.

[0043] The interconnection circuit board 2 can also contain passive and / or active electronic components, such as resistors, capacitors, transistors, etc.

[0044] Fig. Figure 4 shows the connecting circuit board 2. Fig. 3 from a bottom side. The metal contacts 20 are also formed on the underside and are electrically connected over a surface area to the metal contacts 20 on the top side via the edge of the interconnecting circuit board 2. The metal contacts 20 are connected in pairs to conductor tracks 22 to connect the contact surfaces of the first circuit board to the contact surfaces of the second circuit board. The conductor tracks 22 can also be routed in different layers of a multilayer interconnecting circuit board 2. Furthermore, a top and / or bottom layer, as well as intermediate layers of the interconnecting circuit board 2, can have metallized surfaces for shielding and to improve interference immunity.

[0045] Fig. Figure 5 shows the connecting circuit board 2. Fig. Figure 3 shows a side view of a short side of the interconnecting circuit board 2. The metal contacts 20 extend over the edge of the interconnecting circuit board 2. The interconnecting circuit board 2 has a height or thickness of less than 2 mm or less than 1 mm, respectively.

[0046] Fig. Figure 6 shows the connecting circuit board 2. Fig. 3 in a side view of one long side of the connecting circuit board 2. The metal contacts 20 are, as already shown in Fig. 4 executed, guided over the edge of the connecting circuit board 2.

[0047] Fig. Figure 7 shows the connecting circuit board 2 according to Fig. 3 showing the underside with the conductor tracks 22. Further shows Fig. 7. The first circuit board 4 and the second circuit board 6 are positioned relative to each other, for example in a positioning device, so that they can be finally connected. For this purpose, the connecting circuit board 2 is placed on the two circuit boards 4 and 6 so that the metal contacts 20 of the connecting circuit board 2 rest precisely on the contact surfaces 18 of the first and second circuit boards 4 and 6. To ensure the position of the connecting circuit board 2 on the first and second circuit boards 4 and 6, positioning openings 8 and 10 are provided in the connecting circuit board 2, which must correspond to positioning openings 8' and 10' of the circuit boards 4 and 6. For this purpose, a positioning pin can be provided in the positioning device for each positioning opening 8 and 10 to mechanically determine the exact position.

[0048] Once the connecting circuit board 2 is positioned, it is soldered to the two circuit boards 4 and 6. This firmly fixes circuit boards 4 and 6 to each other.

[0049] Fig. Figure 8 shows the connecting circuit board 2, which is soldered to the two circuit boards 4 and 6. The metal contacts 20 are soldered to the contact pads 18. Thus, the circuit boards 4 and 6 form a single unit with the connecting circuit board 2. Reference symbol: 1 linear displacement sensor 2 Connecting circuit board 4 first circuit board 6 second circuit board 8, 8' first positioning opening 10, 10' second positioning opening 12 semicircular recesses 14 sensor elements 16 Hall sensors 18 contact surfaces 20 metal contacts 22 conductor tracks 24 sensor rows Module 26 30 Evaluation electronics 32 Line 42 Sensor magnet 44 pistons 46 working cylinders 48 Piston direction 52 Control electronics 54 Module AB measuring section Position C

Claims

[1] Linear displacement sensor with at least one connecting circuit board (2) and a first circuit board (4) and a second circuit board (6) for length scaling of circuit boards, wherein the first circuit board (4) is connected to the second circuit board (6) via the connecting circuit board (2), wherein the connecting circuit board is arranged for electrical and mechanical connection of the first circuit board (4) and the second circuit board (6), wherein the circuit boards (4, 6) are equipped with sensor elements (14), and the connecting circuit board (2) has conductor tracks (22) to establish a conductive connection between contact surfaces (18) of the first and second circuit boards (4, 6), wherein the connecting circuit board (2) is one-piece and rigid, wherein metal contacts (20) are arranged along an edge for connecting to the contact surfaces (18) of the first and second circuit boards (4, 6), and wherein the connecting circuit board (2), the first circuit board (4) and the second circuit board (6) are arranged parallel to each other, wherein the first and second circuit boards (4, 6) and the connecting circuit board (2) have positioning openings (8, 8', 10, 10') for aligning the circuit boards (4, 6) and connecting circuit board (2) with each other, wherein the metal contacts (20) are provided on semicircular recesses (12) at the edge of the connecting circuit board (2). [2] Linear displacement sensor according to claim 1, characterized by , that the metal contacts (20) of the connecting circuit board (2) are connected to the contact surfaces (18) of the circuit boards (4, 6) with solder or conductive adhesive. [3] Linear displacement sensor according to one of the preceding claims, characterized by, that the connecting circuit board (2) has a width of less than 20 mm, in particular less than 8 mm. [4] Linear displacement sensor according to one of the preceding claims, characterized by , that the connecting circuit board (2) has several layers of conductor tracks (22). [5] Linear displacement sensor according to any of the preceding claims, characterized by , that the interconnecting circuit board (2) has electronic components. [6] Linear displacement sensor according to any of the preceding claims, characterized by , that the height of the connecting circuit board (2) is less than 2 mm, particularly preferably less than 1 mm. [7] Method for manufacturing a linear displacement sensor and for electrically and mechanically connecting a first and a second printed circuit board (4, 6) with a connecting printed circuit board (2), wherein the printed circuit boards (4, 6) are equipped with sensor elements (14), and the connecting circuit board (2) has conductor tracks (22) to establish a conductive connection between contact surfaces (18) of the first and second circuit boards (4, 6), the connecting circuit board (2), the first circuit board (4) and the second circuit board (6) are arranged parallel to each other, so that the rigid and one-piece connecting circuit board (2) rests on both the first and the second circuit board (4, 6), characterized by , that Metal contacts (20) arranged at the edge of the connecting circuit board (2) come to rest on the contact surfaces (18) and are electrically conductive and mechanically rigidly connected to them, wherein, prior to soldering, the first and second circuit boards (4, 6) and the connecting circuit board (2) are aligned to each other by means of positioning openings (8, 8', 10, 10'), wherein the metal contacts (20) are provided on semicircular recesses (12) at the edge of the connecting circuit board (2). [8] Method according to claim 7, characterized by , that the metal contacts (20) of the connecting circuit board (2) are soldered to the contact surfaces (18) of the circuit boards (4, 6) or connected with conductive adhesive. [9] Method according to any one of the preceding claims 7 to 8, characterized by , that during soldering, solder is received in the metal contacts (20) through semicircular recesses (12) on the connecting circuit board (2). [10] Method according to any one of the preceding claims 7 to 9, characterized by , that the connecting circuit board (2) is populated with electronic components.

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