Wireless communication back plane

Abstract

To provide a device in which an apparatus communicates with a plurality of removable modules using wireless links.SOLUTION: In a communication system including a set of communication modules CM and a printed circuit board PCB in which an apparatus communicates with a plurality of removable modules using wireless links, a device includes a main transmission line TL with a plurality of coupling points CP and is provided with a plurality of main antennas MA. Each of the main antennas is coupled at a coupling point to a coupling area CA for directional coupling between the main antenna and the main transmission line and adapted to communicate with an auxiliary antenna AA coupled to the communication module CM.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a short-range wireless frequency communication system that enables a device to communicate with a plurality of detachable modules using a wireless link.

Background Art

[0002] Industrial automation / control systems are used to control the operation of a variety of systems, including processes, machines, etc., and are typically adaptable to different control applications through the configuration and interconnection of multiple control system components or devices such as control modules, input / output (I / O) modules, I / O devices, etc. Existing industrial control systems typically include a processor that interacts with an I / O system (e.g., typically one or more I / O modules or devices) to receive system information in the form of analog and / or digital inputs from field sensors and provide outputs (analog and / or digital) to one or more actuators to implement or execute a control program. Industrial control systems are becoming increasingly interconnected with management information and other systems within manufacturing facilities and can be operably connected to any number of communication networks to facilitate various business management functions such as inventory control, accounting, manufacturing control, etc. in addition to process / machine control functions.

[0003] Therefore, there is a need to find a simple, space-saving, and economical solution for directly communicating between a plurality of communication modules via a wireless link (i.e., without electrical contact). The number of communication modules should preferably be variable, enabling one or more communication modules to be removed, replaced, or added very easily.

Summary of the Invention

[0004] This summary is provided to introduce concepts relating to the subject matter of the present invention. This summary is not intended to identify essential features of the claimed subject matter, nor is it intended to be used to determine or limit the scope of the claimed subject matter.

[0005] One implementation configuration provides a device for wireless communication between communication modules, the device includes a main transmission line having a plurality of coupling points, the device comprises a plurality of main antennas, each main antenna is connected to a coupling region for directional coupling between the main antenna and the main transmission line at a coupling point, and each main antenna is adapted to communicate with an auxiliary antenna connected to a communication module.

[0006] Advantageously, the device can handle any number and combination of communication modules, since the communication modules no longer affect the impedance matching of the main transmission line. Thus, the main transmission line can be designed according to deterministic parameters of line impedance, such as substrate thickness, width, or type, and these deterministic parameters are adapted to the desired frequencies for the main and auxiliary antennas.

[0007] Advantageously, the device can significantly limit the range of wireless communication, particularly by transmitting radio waves, to prevent such communication systems from interfering with the environment, from interference by the environment such as by transmitters that may be placed nearby (e.g., Wi-Fi transmitters), and to prevent two adjacent systems from interfering with each other.

[0008] In one embodiment, the main antenna communicates with the auxiliary antenna of the communication module when the communication module is positioned above the main antenna.

[0009] In one embodiment, the communication module is a detachable module.

[0010] In one embodiment, the main transmission line and the main antenna are conductive tracks integrated on the same printed circuit board.

[0011] In one embodiment, the connection points and connection regions are linear in shape.

[0012] In one embodiment, each main antenna is connected to a coupling region via a secondary transmission line, and each main antenna and secondary transmission line has a terminator having a line end impedance equal to the characteristic impedance of the secondary transmission line.

[0013] In one embodiment, the main transmission line has two terminators having line end impedances equal to the characteristic impedance of the main transmission line.

[0014] In one embodiment, the length of the coupling region depends on the operating frequency of the main antenna.

[0015] In one embodiment, the bonding region presents directional bonding, which is capacitive bonding and inductive bonding.

[0016] In one embodiment, the main antenna is a planar inverted-F antenna.

[0017] In one embodiment, the main antenna is of the same type as the auxiliary antenna.

[0018] In one embodiment, the printed circuit board is mounted within a metal housing that includes a panel surrounding the printed circuit board, the panel being positioned above the main transmission line and providing a hole above the main antenna that allows the communication module to be placed on the housing, so that the auxiliary antenna of the communication module is positioned directly above the main antenna.

[0019] The detailed description will be given with reference to the accompanying drawings. In the drawings, the leftmost digit of the reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the drawings to refer to like features and components. Here, some embodiments of the system and / or method according to the embodiments of the present subject matter will be described by way of example only with reference to the accompanying drawings.

Brief Description of the Drawings

[0020] [Figure 1] It is a schematic diagram of a communication system according to an embodiment.

[0021] [Figure 2] It is a diagram showing in detail a cross-sectional view along the axis X of the coupling between the main transmission line and the sub-transmission line.

[0022] [Figure 3] It is a diagram showing in detail a cross-sectional view along the axis Y of the coupling between the main antenna connected to the sub-transmission line and the auxiliary antenna of the communication module.

Modes for Carrying Out the Invention

[0023] The same reference numbers represent the same elements or elements of the same kind in all the drawings.

[0024] Those skilled in the art should understand that any block diagram herein represents a conceptual diagram of an exemplary system embodying the principles of the present subject matter. Similarly, any flowchart, flow diagram, state transition diagram, pseudocode, etc. is substantially represented on a computer-readable medium and represents various processes that can be executed by such a computer or processor, whether or not such a computer or processor is explicitly shown.

[0025] The drawings and the following description illustrate specific exemplary embodiments of the present invention. Accordingly, those skilled in the art will understand that although not explicitly described or illustrated herein, various configurations that embody the principles of the present invention and are within the scope of the present invention can be devised. Further, any examples described herein are intended to assist in understanding the principles of the present invention and should not be construed as being limited to such specifically recited examples and conditions. As a result, the present invention is not limited to the specific embodiments or examples described below, but is limited by the claims and their equivalents.

[0026] Referring to FIG. 1, the communication system includes a set of communication modules CM and a printed circuit board PCB.

[0027] The purpose of the short - range wireless radio - frequency communication system is to enable the communication modules CM to communicate with each other in the context of automation applications. The communication module CM may be, for example, a programmable logic controller or a microcontroller - type automation device having electronic components (or chips) for wireless transmission and reception. The communication between the communication modules CM may be executed according to various communication protocols as long as they have a transmission frequency that suits the desired application and does not require an overly long wire length and an appropriate data rate. For example, protocols such as Bluetooth® or Zigbee® can be used, and components such as BLE (Bluetooth Low Energy) components are inexpensive. The communication module CM may be, for example, a push - button or switch - type man - machine dialog unit, a visual or acoustic signaling unit (lamp, buzzer, etc.) and / or a sensor or detector, and these also have components for wireless transmission and reception.

[0028] For example, it is often desirable to upgrade automated applications by modifying or adding human-machine dialog units according to the needs of user clients. Furthermore, for various reasons, especially for maintenance, it is advantageous to be able to swap one unit for another.

[0029] To obtain such a modular, upgradeable, and easily modifiable system, the communication modules CM are detachably mounted and connected, meaning they can be easily removed, replaced, or added without interfering with wireless communication from the communication system. Similarly, the presence or absence of one communication module CM in one location does not affect the communication of other communication modules CM.

[0030] A printed circuit board (PCB) includes a main electrical transmission line TL connected to a termination impedance TI on both sides, particularly to avoid reflected waves. This main transmission line TL has multiple coupling points CP located at various points along the main line. In Figure 1, only three coupling points CP are shown for simplification of the figure. The main line TL is preferably generated by a conductive track located on the upper side of the printed circuit board (PCB), as detailed below. The termination impedance TI is, for example, 50 ohms, and the main line must also have a characteristic impedance of typically 50 ohms. This characteristic impedance is essentially determined by the width and thickness of the copper in the track, as well as the width of the dielectric of the printed circuit board (PCB) and its electric dielectric constant.

[0031] The printed circuit board (PCB) also comprises multiple secondary electrical transmission lines. Figure 1 shows secondary transmission lines STL, each having a coupling region CA that allows directional coupling to be generated with the main transmission line TL at the coupling point CP.

[0032] Advantageously, the presence of a secondary transmission line (which enables wireless transmission between communication modules CM) that is not electrically connected to the main transmission line provides a simple solution that allows for avoidance of mismatches in the main transmission line (and therefore potentially unstable or variable performance) depending on the number and presence of communication modules CM connected to the communication system.

[0033] Generally speaking, directional coupling redirects a portion of a signal traveling through a primary transmission line to a secondary transmission line. In this specification, the term “directional coupling” is used to mean that coupling between two wires that are close to each other in order to perform communication is performed capacitively and inductively. These directional couplings are created using, for example, “microstrips” or preferably “stripline” type wires.

[0034] In the illustrated embodiment, the main transmission line and the secondary transmission line are preferably linear, substantially parallel to each other, and at a small distance from each other at the coupling point CP and coupling region CA, in order to obtain good coupling. However, other shapes such as zigzag or sawtooth shapes are also possible instead of linear shapes, allowing for limitations on the geometric length of these regions while maintaining a satisfactory electrical length that fits the wavelength used.

[0035] Each sub-transmission line STL is connected to a terminator impedance TI on one side and to the main antenna MA via an impedance adapter on the other side. The main antenna is also connected to a terminator impedance TI. All terminator impedances TI are assumed to be similar, for example, 50 ohms.

[0036] The main antenna MA can be any type of short-circuit antenna that can be printed on a printed circuit board (PCB) and used in wireless circuits mounted on microstrips. For example, the main antenna MA can be a monopole antenna that extends parallel to the ground plane and is grounded at one end.

[0037] In one embodiment, the main antenna is a planar inverted-F antenna (PIFA), a short and compact antenna that can be impedance-matched to the feed circuit by the designer, enabling efficient power radiation without the need for unrelated matching components. In this case, the total height of the main antenna can be approximately 8 mm, and the total width of the main antenna can be approximately 10 mm.

[0038] Each communication module CM includes an auxiliary antenna AA linked to a communication adapter configured to transmit signals to the auxiliary antenna based, for example, on a modulation and multiplexing method. In one example, the communication module uses quadrature amplitude modulation to transmit signals to the auxiliary antenna. The auxiliary antenna AA may be any type of antenna capable of communicating with the primary antenna. In one embodiment, the auxiliary antenna AA is of the same type as the primary antenna MA.

[0039] Each communication module CM may be powered by various means not detailed herein, such as batteries or magnetic induction power supplies. Magnetic induction power supplies may be implemented at low frequencies far from the band covered by the wireless module (e.g., 2.4 GHz) and therefore not to cause interference with the communication system.

[0040] Figure 2 shows a cross-sectional view of a printed circuit board (PCB) called the main printed circuit board, generated at the junction CP along axis X in Figure 1. It can be seen that the junction CP of the main transmission line TL is located in the same horizontal plane of the PCB as the junction region CA of the secondary transmission line STL. Advantageously, the main transmission line TL (not shown) and the secondary transmission line STL (not shown) are conductive tracks integrated on the same printed circuit board (PCB), simplifying the manufacturing of the communication system.

[0041] The main printed circuit board (PCB) is a multilayer printed circuit board consisting of copper external conductive tracks ECT electrically connected to the zero potential (0V) of the PCB to form a screen and limit the propagation of radio waves. The PCB also includes copper external conductive tracks that form the main transmission line TL and the secondary transmission line STL. The PCB can be manufactured, for example, using conductive layers from which one of the copper layers is removed by trimming. For example, the thickness of the external conductive tracks may be 35 μm, and the total thickness of the PCB is approximately 0.8 mm. Typically, at the coupling point CP, the coupling region CA has a length of, for example, 5.9 mm, and the distance d1 between the coupling point CP of the main transmission line TL and the coupling region CA of the secondary transmission line STL is, for example, 0.7 mm.

[0042] Furthermore, it is preferable that the conductive track of the secondary transmission STL is wider within the coupling region CA. Generally speaking, it is clear that the smaller the distance d1 and the larger the length and width of the coupling region CA, the better the coupling. Therefore, these various parameters can be used to optimize the coupling with respect to existing dimensions and constraints.

[0043] Figure 3 shows a cross-sectional view of the main printed circuit board (PCB) generated at the main antenna MA along axis Y in Figure 1. In this example, the communication module CM includes an auxiliary printed circuit board (APCB) having an auxiliary antenna AA similar to the main antenna MA, and the auxiliary printed circuit board (APCB) includes a conductive layer made of copper located on top of the auxiliary printed circuit board.

[0044] Typically, the distance d2 between the main antenna MA and the auxiliary antenna is, for example, about 1 cm.

[0045] Therefore, if it is desirable to connect a communication module CM to a communication system, it is sufficient to place the communication module CM on the main printed circuit board PCB such that the auxiliary antenna AA of the communication module CM is located directly above the main antenna MA, thereby enabling the auxiliary antenna AA to be placed close to the main antenna MA and the wireless signal to be transmitted to the main antenna at a short distance. Thus, wireless communication between at least two communication modules CM is performed on the one hand via the auxiliary antenna AA and their respective main antennas MA, and on the other hand via directional coupling between the coupling region CA (related to the main antenna) and the main transmission line TL.

[0046] In one embodiment, when the communication module CM is located on the main printed circuit board PCB and both the auxiliary antenna AA and the main antenna MA are of the same type as the inverted-F planar antenna, the auxiliary antenna AA extends approximately perpendicular to the main antenna MA.

[0047] Therefore, in contrast to what may be suggested by Figure 1, which shows a simplified diagram illustrating the communication system, the auxiliary antenna MA (included here in the auxiliary printed circuit board APCB) and the main antenna MA of the printed circuit board PCB are in two separate planes, while the coupling region CA of the main transmission line TL and the secondary transmission line STL is in the same plane, as is clearly shown in detail in Figures 2 and 3.

[0048] In one embodiment, the printed circuit board (PCB) is mounted within a metal housing that includes a panel surrounding the board, the panel positioned above the main transmission line and presenting a hole above the main antenna that allows the communication module to be placed on the housing, so that the auxiliary antenna of the communication module is positioned directly above the main antenna. Several parts of the housing form a screen for the printed circuit board (PCB) to generate a near field for the main transmission line and act like a Faraday cage around the main transmission line.

[0049] In one embodiment, the communication system's printed circuit board (PCB) can be incorporated into a backplane for very strong isolation in a modular industrial PLC, for example, as a bus or redundant bus for input / output modules. In another embodiment, the communication system's PCB may be incorporated into a small home router with optical arrival and very high performance, or as a bus for information exchange within an electrical panel (where the energy required for communication can be significantly reduced by lowering the frequency used by the antenna).

[0050] A printed circuit board (PCB) can be designed according to the device in which it is incorporated. The PCB should demonstrate overall consistency between the length of the conductive tracks, the power of the transmitter, and the number of main antennas in the main transmission line. The main transmission line is a passive electronic assembly with a predetermined shape that allows the wave to be uniformly distributed across all main antennas. Therefore, the shape and dimensions of the main transmission line and main antennas can be specified for the desired spectrum of the transmitted wave.

[0051] Although the present invention has been described above with reference to specific embodiments, the present invention is not limited to the specific forms described herein. Rather, the present invention is limited only by the appended claims, and other embodiments not described above are equally possible within the scope of these appended claims.

[0052] Furthermore, while exemplary embodiments are described above in several exemplary combinations of components and / or functions, it should be understood that alternative embodiments may be provided by different combinations of components and / or functions without departing from the scope of this disclosure. Moreover, it is particularly intended that certain features described individually or as part of an embodiment can be combined with other individually described features or parts of other embodiments.

Claims

1. An apparatus for wireless communication between communication modules (CMs), the apparatus comprising a main transmission line (TL) having a plurality of connection points (CPs), the apparatus comprising a plurality of main antennas (MAs), each main antenna being connected to a coupling region (CA) for directional coupling between the main antenna and the main transmission line at a connection point, each main antenna being adapted to communicate with an auxiliary antenna (AA) connected to a communication module (CM).

2. The apparatus according to claim 1, wherein the main antenna (MA) communicates with the auxiliary antenna (AA) of the communication module when the communication module is disposed above the main antenna.

3. The apparatus according to claim 1, wherein the communication module is a detachable module.

4. The apparatus according to claim 1, wherein the main transmission line (TL) and the main antenna (MA) are conductive tracks integrated on one and the same printed circuit board (PCB).

5. The apparatus according to claim 1, wherein the connection point (CP) and the coupling region (CA) are linear in shape.

6. The apparatus according to claim 1, wherein each main antenna (MA) is connected to the coupling region (CA) via a secondary transmission line (STL), the main antenna (MA) and the secondary transmission line (STL) each having a terminator having a line-end impedance equal to the characteristic impedance of the secondary transmission line.

7. The apparatus according to claim 1, wherein the main transmission line (TL) has two terminators having a line-end impedance equal to the characteristic impedance of the main transmission line (TL).

8. The apparatus according to claim 1, wherein the length of the coupling region depends on the operating frequency of the main antenna.

9. The apparatus according to claim 1, wherein the coupling region exhibits a directional coupling that is capacitive coupling and inductive coupling.

10. The apparatus according to claim 1, wherein the main antenna (MA) is a planar inverted F antenna.

11. The apparatus according to claim 1, wherein the main antenna (MA) is of the same type as the auxiliary antenna (AA).

12. The printed circuit board (PCB) is mounted in a metal housing including a panel surrounding the substrate of the printed circuit board, and the panel is located above the main transmission line (TL) and presents a hole above the main antenna (MA) that enables a communication module (CM) to be disposed on the housing, such that the auxiliary antenna (AA) of the communication module is located directly above the main antenna, for the apparatus according to claim 4.

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