Reading of RFID transponder on object in device

Abstract

The invention relates to reading of an RFID transponder on an object in a device. The invention relates to a system comprising a device (10) for receiving at least one object (12a-12b) and an object (12a-12b) arranged in the device (10), in which an RFID transponder (14) with an antenna (15) is arranged on the object (12a-12b), and in which the device (10) has at least one wall (18) and at least one resonant structure (20) spaced apart from the object (12a-12b). In this case, the resonating structure (20) is introduced as a slot structure into the wall (18).

Description

[0001] The invention relates to a device for accommodating at least one object with an RFID transponder according to the preamble of claim 1 and to a method for reading an RFID transponder on an object in the device according to the preamble of claim 10.

[0002] The RFID reading device stimulates the RFID transponders located in its reading range to radiate the stored information by means of the electromagnetic radiation of its antenna, receives the corresponding transponder signal and evaluates it. The UHF frequency range (ultra-high frequency) is usually used for this purpose, since there is an established framework in the ISO 18000-6 standard for reading transponders at different distances from a few millimeters to several meters. The UHF-RFID transponders are very compact in design and can therefore also be attached to very small objects.

[0003] One area of ​​application for RFID transponders is to document the production process as completely as possible, for example for quality assurance and traceability. It is often desirable to be able to identify the individual components used even after the product has been manufactured. The advantage of RFID transponders is that they can also be identified inside the housing, for example where optical detection is not possible due to its natural properties.

[0004] The possible communication range of the wireless transmission and reception of RFID signal electromagnetic waves is limited by factors such as free space attenuation, the maximum permissible transmission power determined by country-specific standards, the sensitivity of the receiver components and the antenna gain of the RFID reader and RFID transponder.

[0005] Among these factors, the antenna gain of the RFID transponder plays a particularly important role. In addition to the antenna structure, the antenna gain depends primarily on the size of the antenna and therefore also on the size of the RFID transponder. However, particularly small RFID transponders are used to identify components which are sometimes very small themselves and whose properties should be influenced as little as possible by the RFID transponder. The lower antenna gain of these particularly small RFID transponders leads to a smaller reading range, so that RFID transponders in larger devices or machines can no longer be read. Another problem is metal housings, which can hinder or seriously impair the radio connection due to their shielding properties.

[0006] An arrangement is known from US Pat. No. 6,320,509 and US Pat. No. 6,441,740 in which the RFID transponder is provided with one or more metal reflectors in the form of straight or curved surfaces in order to concentrate the antenna gain in a preferred direction in this way. However, this requires the reflector surface to be much larger than the transponder structure.

[0007] Yagi antennas have long been widely used, based on the principle that the directional effect of a dipole antenna can be concentrated in one direction if rods made of conductive material tuned to a resonant frequency are additionally placed in front of and behind the dipole antenna. This can then be used in RFID readers, as described in US 2009 / 0174557 A1. However, for reasons of space, in particular, the design of the RFID transponder is based on other antenna-optimized designs.

[0008] WO 00 / 21030 introduces an RFID transponder which, in addition to its actual antenna structure, also has an additional element for improving the RFID characteristics. However, the element is integrally encapsulated, so the RFID transponder has a corresponding size to accommodate the entire antenna.

[0009] US2008 / 0303633 A1 discloses a reflector and a director which are arranged spaced apart from the RFID transponder to form a Yagi antenna which can double the reading range. However, this does not solve the problem of being able to read the inside of the device, especially through a metal housing, and cannot be used if there is no available installation space inside.

[0010] In US 2017 / 0277922 A1, RFID signals are transmitted to the interior of a vehicle by means of a coaxial cable. However, this means that a lot of work and space are required.

[0011] US 7 994 962 B1 discloses a method for concentrating RF radiation on an object by means of a reflector whose dimensions cannot be used for a labeling assembly.

[0012] It is therefore an object of the present invention to further improve the reading of RFID transponders.

[0013] This object is solved by a device for accommodating at least one object with an RFID transponder according to claim 1 and a method for reading an RFID transponder on an object in a device according to claim 10. The device is, for example, an electronic device, a vehicle, a machine or a part of a machine, in particular a structure or a housing that encloses or carries an object. The device has at least one wall, so that an interior and an exterior can be distinguished, in particular with respect to the wall. The object can be a component or part thereof and is characterized by an RFID transponder in order to identify the object with the aid of an RFID reading device. The RFID transponder has an integrated antenna. The effective antenna gain of the antenna and therefore the reading range are increased by at least one resonant structure, which is spaced apart from the object and therefore also from the RFID transponder with the antenna.

[0014] The invention is based on the basic idea of ​​realizing a resonant structure together with the wall. For this purpose, the resonant structure is introduced into the wall as a slot structure. If the RFID reading device now reads from the side of the wall facing away from the RFID transponder, the slot structure effectively acts as an extension of the antenna of the RFID transponder.

[0015] The invention has the advantage that an improvement in the transmission and reception characteristics of the RFID transponder is achieved, thereby increasing the reading range. This makes it possible to communicate with particularly small or compact RFID transponders of various designs, which originally had too little antenna gain, were too far away or could not be detected due to shielding effects or attenuation (especially of walls). The RFID transponder itself does not need to be subsequently modified for this purpose. The installation of the slot structure requires only a small amount of work and does not require any additional material costs.

[0016] The device is preferably designed as a housing or a cover. The wall preferably closes the housing in one direction. The housing can be a housing of an electronic device or an inner housing of a component or module. Thus, a plurality of sub-housings can also be envisaged, for example a plurality of objects in one housing, one, more or all of which can be characterized by one or more RFID transponders.

[0017] The wall is preferably a metal wall. Preferably, the housing of the device is made entirely of metal. An example is the metal skin of a vehicle. According to the prior art, no information can be read through a metal wall or cladding due to the shielding effect. The slot structure not only makes the wall effectively transparent to RFID signals, but also increases the reading range. For example, a metal element with a slot structure can be introduced into a non-metallic wall.

[0018] The resonant structure is preferably matched to the wavelength of the RFID transponder. In particular, the size of the structure can be chosen to be half the wavelength of the RFID transponder. The required dimensions can thus be easily estimated and the slot structure can be kept fairly small. For example, at an RFID frequency of 866.5 MHz, the size of the slot structure is about 17.3 cm. It is not necessary to maintain this dimension exactly, since the resonance deteriorates with deviations, but a significant range increase can still be achieved, although not the maximum range increase.

[0019] The resonant structure is preferably arranged at a distance from the object that matches the wavelength of the RFID transponder. In particular, the distance is one quarter of the wavelength of the RFID transponder. Since the arrangement of the object relative to the wall usually does not meet the requirements for RFID reading, usually only that wall at a suitable distance from the object can be selected for the slot structure. Thus, the optimal distance can usually only be achieved approximately. However, as in the case of the resonant structure size, the ideal distance that is approximately maintained already leads to an increase in range.

[0020] The object preferably has at least one second resonant structure. The second resonant structure interacts with the slot structure to further improve the directional effect or the range increase. Various structural forms are conceivable for the second resonant structure, such as wires, electrical conductor tracks on a circuit board, metallized films with an adhesive layer, metal printing or metal particles integrated in the plastic, in particular by means of 3D printing. The second resonant structure can also be a slot structure if additional walls are present at suitable locations or are added.

[0021] The second resonant structure is preferably arranged as a guide between the slot structure and the object. The second resonant structure is then located in the propagation path of the RFID signal between the RFID transponder and the RFID reader. Alternatively, the second resonant structure is arranged as a reflector in the extension of the slot structure connected to the object, thus, so to speak, behind the actual propagation path. It is conceivable that a third resonant structure or a further resonant structure is provided as a guide and / or resonator.

[0022] The system preferably has an RFID reading device to read the information of the RFID transponder. The RFID reading device preferably includes at least one internal or external antenna of its own, a transceiver connected to the antenna, and an RFID control and evaluation unit connected to the transceiver. The RFID reading device uses the antenna to send RFID signals to the RFID transponder and / or receive RFID signals from the RFID transponder. Here, any combination of a transmitter and a receiver is referred to as a transceiver. The RFID control and evaluation unit has at least one digital computing module, such as a microprocessor, an FPGA (Field Programmable Gate Array), an ASIC (Application Specific Integrated Circuit), etc., which is designed to encode RFID information into the RFID signal and / or read RFID information from the RFID signal. The transceiver and the RFID control and evaluation unit can constitute a common computing module or at least partially share a computing module. Due to the gap structure, the reading range of the RFID reading device that can read the RFID transponder is increased.

[0023] The method according to the invention can be further developed in a similar manner and at the same time exhibits similar advantages. Such advantageous features are described exemplarily but not exhaustively in the dependent claims which are dependent on the independent claim. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Other features and advantages of the present invention will be described in more detail below based on the embodiments and with reference to the accompanying drawings.

[0025] Figure 1 A schematic overview of a device and an RFID reading device is shown, the device comprising a plurality of objects or components arranged therein, which objects or components are at least partially provided with RFID transponders;

[0026] Figure 2 A schematic diagram showing the antenna gain of an antenna changed by a resonant structure;

[0027] Figure 3 The small figures a)-f) show schematic diagrams of an RFID transponder and an antenna of an RFID reader device having resonant structures with different configurations; and

[0028] Figure 4 A schematic diagram of a resonant structure constructed as a slot structure is shown.

[0029] Figure 1 A schematic overview of an apparatus 10 (e.g. an electronic device) is shown, in which a plurality of objects 12a-12c or individual components are arranged, which objects 12a-12c or individual components are at least partially provided with an RFID transponder 14 having an antenna 15. An RFID reading device 16 can be arranged outside the apparatus 10 in order to communicate with the RFID transponder 14, in particular to identify the objects 12a-12c based on the RFID transponder 14 attached to the objects 12a-12c.

[0030] Particularly for small RFID transponders 14, the read / write range for successful communication between the RFID reading device 16 and the RFID transponder 14 is limited. This range may be further reduced due to the shielding effect of, for example, the wall 18 of the housing of the device 10, and in the case of a metal housing, communication may also be completely prevented.

[0031] Therefore, a resonant structure 20 in the form of a slot structure is provided in at least one wall to improve communication. Figures 2 to 4The possible designs and operating modes of the slot structure are explained in more detail. Depending on the frequency of the RFID communication, the position and size of the resonant structure 20 have respective optimum values. Since the positions of the objects 12a-12b and the wall 18 are fixed, in some cases only the optimum position can be approximately occupied. Due to the limitations of boundary conditions (e.g., available space), the dimensions may not be ideally achieved. Nevertheless, signal attenuation is reduced and communication is improved or even possible for the first time.

[0032] The RFID reading device 16 has an antenna 22 which is designed, for example, for the ISM band of approximately 900 MHz. Instead of the internal antenna 22 shown, an external antenna is also conceivable. A transceiver 24 is connected to the antenna 22, and a control and evaluation unit 26 of the RFID reading device 16 is connected to the transceiver 24 in order to evaluate the RFID signals received via the antenna 22 or to send information as RFID signals to the RFID transponder 14. The control and evaluation unit 26 is preferably connected to a wired or wireless interface (not shown) in order to exchange data, perform parameterization, etc. The operating principle of RFID reading devices in the UHF frequency range (ultra-high frequency) is known, for example, according to the ISO 18000-6 standard, and is therefore not explained in detail.

[0033] Figure 2 A schematic diagram of the antenna gain of an antenna 15 which is changed by a resonant structure 20 is shown. Here, for comparison, the antenna 15 alone is shown on the left and the antenna with the resonant structure 20 is shown on the right. For example, for an RFID transponder 14 in the UHF band of 88.5 MHz, a wire extending approximately half a wavelength (17.3 cm) can be selected as the resonant structure 20 and positioned at a distance of a quarter wavelength from the antenna 15. As described above, advantageous effects can also occur if these regulations are only approximately adhered to and, for example, a wire with a length of 16 cm is used. If in Figure 2 In the example on the right, if reading is to be done from the right, the resonant structure 20 significantly improves the directional effect.

[0034] Figure 3 The small figures a)-f) of FIG. 1 respectively show schematic diagrams of the antenna 15 of the RFID transponder 14 and the antenna 22 of the RFID reader 16 with resonant structures of different configurations. First, for comparison, Figure 3 The small figure a) shows the case where there are only two antennas without additional resonant structures. Figure 3 In the small figure b), from the perspective of the antenna 22 of the RFID reading device 16, the resonant structure 20 is arranged behind the antenna 15 of the RFID transponder 14, so that the resonant structure assumes the function of a reflector. Figure 3In the small figure c), the order is reversed, the resonant structure 20 is arranged in front of the antenna 15, so that the resonant structure acts as a director.

[0035] Figure 3 The sub-figures d)-f) of 20 show configurations in which the resonant structure 20 is supplemented with at least one further resonant structure 20a-20b. In principle, even more resonant structures and thus additional combinations of reflectors and guides are also possible. Figure 3 Inset d) shows an arrangement with two resonant structures 20, 20a in front of the antenna 15, whereby both resonant structures act as directors. Figure 3 The small figure e) shows that there is a resonant structure 20 in front of the antenna 15 and a resonant structure 20a behind the antenna 15, thus a combination of a director and a reflector. Figure 3 In the small figure f), relative to Figure 3 The arrangement of inset e) with another resonant element 20b added as a second guide is provided as an example of a combination of more resonant structures.

[0036] Figure 4 A schematic diagram of a resonant structure 20 designed as a slot structure is shown, which is introduced into a wall 18. The slot structure acts as a slot radiator or slot antenna, thereby also enabling an increase in the reading range or first enabling communication with the metal clad device 10. The geometric requirements of the slot or groove in terms of extension range and position are the same as discussed previously.

[0037] In one application example, the device 10 is a vehicle, in particular a passenger car. Components such as seats or control devices are installed in the vehicle as objects 12a-12b carrying RFID transponders 14. Even after the vehicle has been assembled, these components should still be identifiable by reading the RFID transponders 14. According to the prior art, this is not possible for an RFID reader 16 arranged in front of the vehicle due to the installation position. In one embodiment of the invention, the resonant structure 20 can now be attached to the side window or plastic cover as a metal part with a gap structure. A simpler method is to introduce the gap structure into the metal skin, which can then be filled, for example, with plastic so as not to interfere with the overall visual effect of the vehicle. The gap structure allows the components of the finished vehicle to be further identified from the outside by reading the RFID transponder 14.

[0038] In another application example, the device 10 is an electrical device, in particular a large electrical device, such as a flat-screen TV, a vacuum cleaner or a washing machine. In the production chain, a compact RFID transponder 14 is integrated into the device 10, which should be able to identify components or even the entire electrical device. According to the prior art, the size of the transponder can only be read at a short distance, for example less than 10 cm. In particular, in the case of repair or maintenance, it should be possible to identify from the outside without disassembling the housing. Therefore, now in one embodiment of the present invention, above the transponder, a slot structure is introduced into the circuit board as a resonant structure 20, or a metal element with a slot structure is arranged in the circuit board, alternatively, the slot structure is introduced into a housing wall, in particular a metal. Through the radiation characteristics of the RFID transponder 14 thus improved, it can now be identified from the outside. A label can also be attached to the housing to indicate to the user from which position of the RFID reading device 16 the RFID transponder 14 can be read particularly well.

Claims

1. A system comprising a device (10) for accommodating at least one object (12a-12b) and an object (12a-12b) arranged in the device (10), wherein an RFID transponder (14) with an antenna (15) is arranged on the object (12a-12b), and wherein the device (10) has at least one wall (18) and at least one resonant structure (20) spaced apart from the object (12a-12b), It is characterized in that The resonant structure (20) is introduced into the wall (18) as a slot structure.

2. The system according to claim 1, wherein: The device (10) is configured as a housing or a cover.

3. The system according to claim 1 or 2, wherein: The wall (18) is a metal wall.

4. A system according to any one of the preceding claims, wherein: The resonant structure (20) is matched to the wavelength of the RFID transponder (14), in particular the resonant structure (20) has a structural size of half the wavelength of the RFID transponder (14).

5. A system according to any one of the preceding claims, wherein: The resonant structure (20) is arranged at a distance from the object (12a-12b), the distance matching the wavelength of the RFID transponder (14), and the resonant structure (20) is particularly arranged at a distance of a quarter of the wavelength of the RFID transponder (14) from the object (12a-12b).

6. A system according to any one of the preceding claims, wherein: The object (12a-12b) has at least one second resonant structure (20a-20b).

7. A system according to any one of the preceding claims, wherein: A second resonant structure (20a-20b) is arranged as a guide between the slot structure and the object (12a-12b).

8. The system according to any one of claims 1 to 6, wherein: The second resonant structure (20a-20b) is arranged as a reflector in an extension of the slot structure connected to the object (12a-12b).

9. The system according to claim 1, comprising an RFID reading device (16) for reading the information of the RFID transponder (14).

10. A method for reading an RFID transponder (14) on an object (12a-12b) in a device (10) for receiving the object (12a-12b), the device (10) having at least one wall (18), wherein at least one resonant structure (20) is arranged at a distance from the object (12a-12b), It is characterized in that The resonant structure (20) is introduced into the wall (18) as a slot structure.

Images