WO2014125755A1

WO2014125755A1 - Electronic tag, and vehicle door locking/unlocking system

Info

Publication number: WO2014125755A1
Application number: PCT/JP2014/000033
Authority: WO
Inventors: 前原　宏明; 宗範松本
Original assignee: 株式会社デンソー; 株式会社日本自動車部品総合研究所
Priority date: 2013-02-14
Filing date: 2014-01-08
Publication date: 2014-08-21
Also published as: JP2014156700A

Abstract

An electronic tag (1) is provided with: a coil conductor (22); a button battery housing unit (23) housing a button battery (30); a substrate (20); and a metal member (52). The coil conductor is provided in the form of a loop through which a magnetic flux radiated from an external antenna passes for near-field wireless communication. The substrate carries the coil conductor and the button battery housing unit at a proximate position where leakage towards the outside of the loop is promoted by the button battery. The metal member guides the magnetic flux, of which leakage towards the outside of the loop is promoted by the proximate position, towards the inside of the loop.

Description

Electronic tag and vehicle door locking / unlocking system

Cross-reference of related applications

This disclosure is based on Japanese Application No. 2013-26751 filed on Feb. 14, 2013, and the description is incorporated herein.

The present disclosure relates to an electronic tag having a coil conductor for performing short-range wireless communication and a vehicle door locking / unlocking system.

Conventionally, as an antenna device having a coil conductor for performing short-range wireless communication, a loop-shaped or spiral-shaped coil conductor having a winding center as a coil opening, a conductor opening, and the conductor opening and an outer edge A conductor layer having a slit portion that connects between them, and when the coil conductor is viewed in plan, the coil opening and the conductor opening overlap, the area of the conductor layer is larger than the formation area of the coil conductor, Some cases include a metal part, and a conductor layer is formed of at least a part of the metal part so as to increase a communication distance (see, for example, Patent Document 1).

JP 2012-1352020 A

By the way, in the vehicle, radio waves for electronic key verification are transmitted and received between the electronic key possessed by the user and the vehicle-mounted device mounted on the vehicle, and the door of the vehicle is locked according to the verification result of the electronic key. There is a vehicle door locking / unlocking system that permits start-up of unlocking, vehicle engine and the like.

In such a vehicle door locking / unlocking system, it is considered that an electronic tag for NFC (Near Field Communication) using a frequency of 13.56 MHz included in short-range wireless communication is incorporated in an electronic key. Yes.

The present inventor has recognized the following problems regarding the electronic key or the electronic tag. Since the electronic key of the vehicle door locking / unlocking system has a built-in button battery, the button battery and the coil conductor of the electronic tag may be disposed close to each other (closely disposed). In the first place, it is desirable that the electromagnetic waves for short-range wireless communication radiated from the terminal device pass inside the loop formed by the coil conductor.

However, due to the close arrangement of the button battery and the coil conductor, electromagnetic waves that are desired to pass inside the loop formed by the coil conductor leak out to the outside without being bent by the button battery and passing through the loop. May end up. Thus, if the electromagnetic wave from the terminal device leaks to the outside of the coil conductor, the sensitivity of the antenna is lowered and the communication quality is lowered.

Note that if the coil conductor and the button battery storage unit are arranged apart from each other, the communication quality can be improved, but the electronic tag becomes larger.

This disclosure aims to achieve both miniaturization and improvement in communication quality.

In order to achieve the above object, according to the first example of the present disclosure, the electronic tag is provided as follows. The electronic tag includes a coil conductor, a button battery housing, a substrate, and a metal member. The coil conductor is provided in a loop shape or a spiral shape so as to form a loop through which the magnetic flux radiated from the external antenna passes for short-range wireless communication. The button battery storage unit stores a button battery. The substrate is mounted with the coil conductor and the button battery storage portion in a proximity arrangement where the leakage of the magnetic flux is promoted to the outside of the loop of the coil conductor by the button battery. The metal member guides the magnetic flux, which is urged to leak out of the loop by the proximity arrangement, to the inside of the loop.

According to such a configuration, there is provided a metal member that guides a magnetic flux that leaks out of the loop without passing through the inside of the loop formed by the coil conductor. Normally, when the coil conductor and the button battery storage unit are arranged close to each other, the magnetic flux radiated from the external antenna so as to pass through the inside of the loop is originally looped by the button battery stored in the button battery storage unit. There is a tendency to leak outside without passing through. On the other hand, by providing the metal member, a magnetic flux that leaks outside the loop formed by the coil conductor is induced inside the loop. As a result, both miniaturization and improvement in communication quality can be achieved.

Furthermore, according to the second example of the present disclosure, a vehicle door locking / unlocking system is provided so as to include an electronic key and an in-vehicle device. The electronic key is the electronic tag of the first example described above. The vehicle-mounted device transmits and receives radio waves for authentication with the electronic key to lock and unlock the door of the vehicle. This configuration can provide the same effect as the first example.

The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description with reference to the accompanying drawings.
It is an external view of an electronic key according to an embodiment of the present disclosure, It is an exploded perspective view of an electronic key according to an embodiment of the present disclosure, It is a figure for demonstrating the mode of magnetic flux when an electronic key is brought close to a reader / writer, It is a figure for demonstrating the mode of magnetic flux when an electronic key is brought close to a reader / writer, It is a figure for demonstrating the mode of magnetic flux when an electronic key is brought close to a reader / writer, It is a diagram showing the overlap of the metal parts and the coil conductor, It is the figure shown about the characteristic of the minimum operating magnetic field intensity at the time of changing the overlap of a metal part and a coil conductor.

FIG. 1 shows an external view of an electronic key according to an embodiment of the present disclosure. The electronic key 1 is also referred to as an electronic device 1 or an electronic tag as will be described later. The electronic key 1 is used in a vehicle door locking / unlocking system that permits locking / unlocking of a vehicle door and starting of a vehicle engine or the like. This vehicle door locking / unlocking system includes an electronic key 1 possessed by a user and an in-vehicle device (not shown) mounted on the vehicle. The electronic key 1 transmits and receives radio waves for verification with an on-vehicle device mounted on a vehicle.

In addition, the electronic key 1 in the present embodiment also has a function as an electronic tag having a tag antenna for performing near field communication (NFC) in the HF band (for example, 13.56 MHz). When receiving the vehicle information transmitted from the vehicle-mounted device, the electronic key 1 stores the received vehicle information in a memory. Further, when a passenger holds a terminal device (for example, a smartphone) having a reader / writer for short-range wireless communication (e.g., an external antenna) over the electronic key 1, the electronic key 1 is connected to the terminal device via the tag antenna. The vehicle information is transmitted by radio wave, and the vehicle information can be confirmed on the display screen of the terminal device.

The electronic key 1 includes a case 100 including a first case 10 and a second case 50 made of resin. The case 10 is configured by fitting the first case 10 and the second case 50 together. Further, three operation parts 51 are formed on the outer surface of the second case 50. Further, the ring 100 a can be attached to the hole provided in the case 100.

FIG. 2 shows an exploded perspective view of the electronic key 1. The configuration of the electronic key 1 will be described with reference to this figure. The electronic key 1 includes a first case 10, a printed circuit board 20, a button battery 30, a mechanical key 40, and a second case 50.

A plurality of protrusions 10a for fixing the printed circuit board 20 are formed inside the first case 10a. Further, the first case 10a is formed with a notch 13 for housing the mechanical key 40.

The printed circuit board 20 has a substantially rectangular shape. The printed circuit board 20 is mounted on a plurality of protrusions 10a formed inside the first case 10a.

Three switches 21 are mounted on one surface of the printed circuit board 20. These switches 21 are arranged inside the case 100 of the three operation units 51 formed in the second case 50, respectively. A button battery storage unit 23 for storing the button battery 30 is provided on the opposite surface of the printed circuit board 20.

The printed circuit board 20 is formed with a loop-shaped coil conductor 22 for transmitting or receiving HF band radio waves to perform near field communication (NFC). The coil conductor 22 corresponds to a tag antenna, and is formed by printing a copper pattern on the middle layer of the printed board 20.

Note that a transmission antenna (not shown) for transmitting a 300 MHz band radio wave is formed on one surface of the printed circuit board 20 and mounted on the vehicle, and the other surface of the printed circuit board 20 is mounted on the vehicle. A receiving antenna (not shown) for receiving a 125 kHz band radio wave transmitted from the device is provided.

The printed circuit board 20 includes a circuit for transmitting and receiving radio waves for verification with an on-vehicle device mounted on the vehicle, and a circuit for performing near field communication (NFC). Yes. Note that a circuit for transmitting and receiving radio waves for collation operates by feeding power from the button battery 30, and a circuit for performing near field communication (NFC) is a near field communication provided in a terminal device. It operates with the electric power obtained by receiving the electromagnetic wave from the reader / writer. However, a circuit for performing near field communication (NFC) can be operated with electric power supplied from the button battery 30. Note that a circuit for performing near field communication (NFC) includes each IC chip (not shown) such as a control circuit that performs various signal processing, a memory, and a signal processing circuit.

The mechanical key 40 is used by being removed from the case 100 of the electronic key 1 when the electronic key 1 breaks down. By inserting the mechanical key 40 into a door cylinder provided on the door of the vehicle and rotating the mechanical key 40, the door of the vehicle can be locked or unlocked.

The second case 50 is formed with a notch 53 for accommodating the mechanical key 40. A substantially U-shaped metal part 52 is provided on the outer surface of the second case 50. The metal part 52 is configured using a metal material (for example, zinc). The metal part 52 has a locking claw (not shown). The locking claw of the metal part 52 is inserted into a locking hole (not shown) provided in the second case 50. The metal part 52 is fixed to the second case 50 by being locked.

The metal part 52 is added to the second case 50 as a decoration. Adding a metal part 52 to the case 100 produces a sense of quality. The metal part 52 also plays a role of improving communication quality by improving reception sensitivity of electromagnetic waves for short-range wireless communication.

Next, the assembly of the electronic key 1 will be described. First, a printed circuit board 20 on which circuit components are mounted is prepared, and the printed circuit board 20 is attached to the first case 10. Specifically, after inserting the button battery 30 into the button battery storage portion 23 provided on the printed circuit board 20, the printed circuit board 20 is mounted on the protrusion 10a formed inside the first case 10a.

Next, the second case 50 attached with the metal part 52 is fitted with the first case 10 to complete the assembly of the electronic key 1.

Finally, the mechanical key 40 is inserted into an insertion hole including the notch 13 formed in the first case 10 and the notch 53 formed in the second case 50, and the ring is inserted into the hole provided in the case 100. When 100a is attached, the electronic key 1 is completed.

In the above configuration, when a terminal device having a reader / writer (not shown) for near field communication is brought close to the electronic key 1, HF band electromagnetic waves are emitted from the reader / writer and formed on the printed circuit board 20 of the electronic key 1. An induced current corresponding to the intensity of the electromagnetic wave radiated from the reader / writer is generated in the coil conductor 22. This induced current is rectified in the signal processing circuit of the electronic key 1 to generate electric power. Then, with this power, the control circuit, memory, etc. of the electronic key 1 start operating.

The control circuit of the electronic key 1 performs processing according to the voltage rectified in the signal processing circuit, reads out necessary data from the memory, and returns the data read from the memory on the electromagnetic wave from the coil conductor 22. . The reader / writer receives an electromagnetic wave from the electronic key 1, and a control unit (not shown) of the reader / writer extracts information from the electromagnetic wave received from the electronic key 1.

Next, the state of the magnetic flux when the electronic key 1 is brought close to the reader / writer 200 will be described with reference to FIGS.

As shown in FIG. 3, when the substrate 20 on which the coil conductor 22 is formed is brought close to the reader / writer 200 for short-range wireless communication having the substrate 220 on which the antenna 222 is formed, electromagnetic waves in the HF band are generated from the reader / writer 200. An induced current corresponding to the intensity of the electromagnetic wave emitted from the antenna 222 of the reader / writer 200 flows through the coil conductor 22 radiated and formed on the printed circuit board 20 of the electronic key 1.

Here, when the button battery 30 is arranged near the coil conductor 22 formed on the printed circuit board 20 as in the electronic key 1, it is formed by the coil conductor 22 as shown in FIG. 4. A phenomenon occurs in which the magnetic flux radiated from the antenna 222 of the reader / writer 200 so as to pass through the inside of the loop leaks outside without passing through the inside of the loop formed by the coil conductor 22 by the button battery 30. To do.

That is, when a conductive object having a relatively large area such as the button battery 30 exists inside the loop formed by the coil conductor 22, a large eddy current is generated along the surface, and the coil conductor 22 is generated by the eddy current. A magnetic field opposite to the magnetic field that attempts to pass through the inside of the loop formed by is generated, and the magnetic field necessary for communication is canceled.

Further, at the peripheral portion of the conductive object such as the button battery 30, as shown in FIG. 4, it passes through the inside of the loop formed by the coil conductor 22 due to the eddy current generated along the surface of the conductive object. Thus, the magnetic flux radiated from the antenna 222 of the reader / writer 200 faces the outside of the loop formed by the coil conductor 22 so as to avoid the conductive object such as the button battery 30, and is formed by the coil conductor 22. Leaks outside the loop.

As described above, the electromagnetic wave trying to pass through the inside of the loop formed by the coil conductor 22 is canceled out, or the magnetic flux trying to pass through the inside of the loop formed by the coil conductor 22 is formed by the coil conductor 22. Leaking outside the loop, the reception sensitivity of the antenna decreases and the communication quality deteriorates.

Therefore, as shown in FIG. 5, the electronic device 1 according to the present embodiment uses the coil conductor 22 to cause a magnetic flux to be leaked to the outside of the loop formed by the coil conductor 22 by the metal part 52 provided in the case 100. It is configured to guide to the inside of the formed loop. That is, an eddy current is generated along the surface of the metal part 52, and a magnetic flux that leaks outside the loop formed by the coil conductor 22 is induced inside the loop formed by the coil conductor 22 by the eddy current. And passes through the inside of the loop formed by the coil conductor 22.

When the metal part 52 is not provided in the case 100, the magnetic flux that tries to pass inside the loop formed by the coil conductor 22 leaks to the outside of the loop formed by the coil conductor 22. For this reason, as shown in the region A in FIG. 4, the magnetic flux passing through the inside of the loop formed by the coil conductor 22 is reduced, whereas when the metal part 52 is provided in the case 100, The metal part 52 induces a magnetic flux that leaks outside the loop formed by the coil conductor 22 to the inside of the loop formed by the coil conductor 22. Therefore, as shown in a region B in FIG. 5, the magnetic flux passing through the inside of the loop formed by the coil conductor 22 is larger than the magnetic flux shown in the region A in FIG.

Next, the relationship between the overlap d between the metal part 52 and the coil conductor 22 and the magnetic field strength will be described. FIG. 6A shows an overlap d between the metal part 52 and the coil conductor 22. In the present embodiment, as shown in FIG. 6A, the overlap between the metal part 52 and the coil conductor 22 is defined as an overlap d with the end portion on the outer edge side of the coil conductor 22 in the printed board 20 as a reference position. The value of the overlap d between the metal part 52 and the coil conductor 22 increases as it approaches the center of the electronic key 1 from the reference position. Further, when the end of the metal part 52 is outside the loop formed by the coil conductor 22 from the reference position, the negative value is obtained.

FIG. 6B shows the characteristics of the minimum operating magnetic field strength when the overlap d between the metal part 52 and the coil conductor 22 is changed. The minimum operating magnetic field strength is a power obtained by receiving an electromagnetic wave from the reader / writer, and is a magnetic field strength at which the electronic key 1 can operate as an electronic tag or generate a lower limit power. That means.

In this embodiment, the reader / writer and the electronic key 1 are arranged so as to have a predetermined positional relationship, and the relationship between the intensity of electromagnetic waves radiated from the reader / writer and the magnetic field intensity around the coil conductor 22 of the electronic key 1 is determined in advance. Then, the intensity of the electromagnetic wave radiated from the reader / writer is changed, and the intensity of the electromagnetic wave that can be operated as the electronic tag by the electronic key 1 is specified as the intensity of the electromagnetic wave radiated from the reader / writer.

The minimum operating magnetic field strength shown in FIG. 6B is based on the relationship between the strength of the electromagnetic wave radiated from the reader / writer investigated in advance and the magnetic field strength around the coil conductor 22 of the electronic key 1, and the electronic key 1 operates as an electronic tag. It is a value converted from the intensity of electromagnetic waves that can be done. In FIG. 6B, as a reference, the minimum operating magnetic field strength without the metal part 52 is also indicated by a dotted line. In FIG. 6B, the smaller the minimum operating magnetic field strength is, the better the antenna performance is.

In the electronic key 1, the minimum operating magnetic field strength is the smallest when the overlap d between the metal part 52 and the HF antenna (coil conductor 22) is −1 to −2 millimeters (mm). This corresponds to the vicinity of M in FIG. 6B. As a result, the antenna performance is the best.

That is, as shown in the direction of arrow C in FIG. 6A, when the printed circuit board 20 is viewed in plan, the end of the metal part 52 is 1 to 2 millimeters from the outer end of the loop formed by the coil conductor 22. It has been found that the antenna performance is the best when it is located outside the loop formed by the coil conductor 22.

According to the configuration described above, the printed circuit board 20 includes the metal part 52 that guides the electromagnetic wave that is about to leak outside the loop formed by the coil conductor 22 to the inside of the loop formed by the coil conductor. Magnetic flux radiated from the external antenna so as to pass inside the loop formed by the coil conductor 22 leaks out of the loop formed by the coil conductor 22 by the button battery 30 stored in the button battery storage unit 23. Even if the coil conductor 22 and the button battery storage portion 23 are arranged close to each other as described above, the coil conductor 22 forms a magnetic flux that leaks to the outside of the loop formed by the coil conductor 22 by the metal part 52. Guided inside the loop, it is possible to achieve both reduction in size and improvement in communication quality.

The metal part 52 is preferably provided so as to surround the coil conductor from the outside when the printed circuit board 20 is viewed in plan.

In addition, by adding the metal part 52 as a decoration to the surface of the case 100 that houses the printed circuit board 20, it is possible to achieve both a reduction in size and an improvement in communication quality while producing a sense of quality.

In addition, this indication is not limited to the said embodiment, Based on the meaning of this indication, it can implement with a various form.

For example, in the above embodiment, as described above, an electronic key in a vehicle door locking / unlocking system including an electronic key and an onboard device that performs transmission / reception of radio waves for authentication with the electronic key to lock and unlock the door of the vehicle. However, the present invention is not limited to the electronic key, and the metal parts 52 as described above are provided in various portable devices having the substrate 20 having the button battery storage unit 23 for storing the button battery 30. You may comprise as follows.

In the above embodiment, the electronic key 1 includes the button battery 30. However, the button battery 30 is a separate component, and the user purchases the button battery 30 separately and attaches it to the electronic key 1. Also good.

Moreover, in the said embodiment, although the loop-shaped copper pattern was printed on the middle layer of the printed circuit board 20 and the loop-shaped coil conductor 22 was formed, the coil conductor 22 was shown on the surface and back surface of the printed circuit board 20. It may be formed or may be spiral. The coil conductor 22 may be formed by winding or an etching method.

Moreover, in the said embodiment, although the example which provided the substantially U-shaped metal part 52 in the outer surface of the 2nd case 50 was shown, the metal part 52 is used as the outer surface of the 1st case 10. It may be provided on the inside of the second case 50 or on the inside of the first case 10. Moreover, the shape of the metal part 52 is good also as shapes other than substantially U-shape.

Moreover, in the said embodiment, although the latching claw provided in the metal part 52 was latched in the latching hole provided in the case 100, the metal part 52 was fixed to the case 100. The fixing method is not limited.

Although the present disclosure has been described based on the embodiments, it is understood that the present disclosure is not limited to the embodiments and structures. The present disclosure includes various modifications and modifications within the equivalent range. In addition, various combinations and forms, as well as other combinations and forms including only one element, more or less, are within the scope and spirit of the present disclosure.

Claims

A coil conductor (22) provided in a loop or spiral shape to form a loop through which magnetic flux radiated from an external antenna passes for short-range wireless communication;
A button battery storage part (23) for storing the button battery (30);
A board (20) on which the coil conductor and the button battery storage unit are mounted in a close arrangement where the leakage of the magnetic flux is promoted to the outside of the loop of the coil conductor by the button battery;
An electronic tag comprising: a metal member (52) for guiding the magnetic flux, which is urged to leak out of the loop by the proximity arrangement, to the inside of the loop.
The electronic tag according to claim 1, wherein the metal member is provided so as to surround the coil conductor from the outside when the substrate is viewed in plan.
A case (100) for storing the substrate;
The electronic tag according to claim 1, wherein the metal member is added as a decoration to the surface of the case.
A vehicle door locking / unlocking system comprising an electronic key and an onboard device for performing transmission / reception of radio waves for authentication with the electronic key to lock and unlock the vehicle door,
The electronic key is
A coil conductor (22) provided in a loop or spiral shape to form a loop through which magnetic flux radiated from an external antenna passes for short-range wireless communication;
A button battery storage part (23) for storing the button battery (30);
A board (20) on which the coil conductor and the button battery storage unit are mounted in a close arrangement where the leakage of the magnetic flux is promoted to the outside of the loop of the coil conductor by the button battery;
A vehicle door locking / unlocking system comprising a metal member (52) for guiding the magnetic flux to the inside of the loop, which is urged to leak out of the loop by the proximity arrangement.