JP5901686B2 - Keyless entry in-vehicle device - Google Patents

Description

  The present invention relates to a keyless entry vehicle-mounted device applied to a keyless entry system of a saddle type vehicle such as a motorcycle.

  Conventionally, in the automotive field, even if a user does not operate a button on a portable device, by carrying the portable device, authentication is performed by wireless communication between the portable device and the in-vehicle device, and if the authentication is established, the vehicle A keyless entry system that can operate (lock, unlock, etc.) is known.

  In such a keyless entry system, a radio signal from a portable device intended to remotely operate a vehicle has an RF (Radio Frequency) band of several hundred MHz in order to realize operation from a long distance. A signal is used. An antenna (hereinafter referred to as “RF antenna”) for receiving an RF band signal (hereinafter referred to as “RF signal”) is mounted on the in-vehicle device.

  In addition, a signal in the LF (Low Frequency) band of several hundred kHz is used as a radio signal transmitted from the in-vehicle device. This is because when the user uses the keyless entry system, the distance between the vehicle and the user is limited, and the effect of shielding electromagnetic waves by the human body is reduced.

  Further, an antenna (hereinafter referred to as “LF antenna”) for transmitting an LF band signal (hereinafter referred to as “LF signal”) is in the vicinity of a range where the user uses the keyless entry system (for example, near a door). The in-vehicle device and the LF antenna are connected to each other by a harness.

  In addition, even in a saddle type vehicle such as a two-wheeled vehicle, a snowmobile, a water bike, etc., where the LF communication range is established only in one area, in order to fully utilize the characteristics of the LF antenna, metal objects are placed around the LF antenna The in-vehicle device and the LF antenna are connected by a harness so as not to arrange as much as possible.

  Here, in the configuration in which the LF antenna is connected by the harness, the influence of the parasitic inductance due to the harness and the tolerance of the length are large, so that there is a problem that the communication center frequency shifts and the communication distance cannot be determined.

  Therefore, in order to solve the above problem, a resonance circuit that switches the resonance frequency in multiple stages is provided in the LF receiver circuit of the portable device, and the portable device transmits the electric field strength measurement signal transmitted from the in-vehicle device to the resonance frequency of the resonance circuit. Wireless communication that prevents deterioration in communication performance by switching the resonance circuit to the resonance frequency when the electric field strength reaches the maximum value among the measured electric field strengths. A system has been proposed (see, for example, Patent Document 1).

JP 2012-67499 A

However, the prior art has the following problems.
In the wireless communication system disclosed in Patent Document 1, it is necessary to additionally provide a multi-stage resonance circuit in the LF receiver circuit of the portable device, which may increase the size and cost of the portable device that requires portability. . There is also a problem that no countermeasure is taken with respect to the influence of the parasitic inductance caused by the harness.

  The present invention has been made to solve the above-described problems, and provides a keyless entry vehicle-mounted device capable of eliminating a communication frequency shift due to parasitic inductance and ensuring good LF transmission performance. With the goal.

A keyless entry vehicle-mounted device according to the present invention is a keyless entry vehicle-mounted device applied to a keyless entry system for a saddle type vehicle, wherein a board on which various parts of the keyless entry vehicle-mounted device are mounted, and a user uses a portable device. RF receiving the LF transmitting antenna for transmitting an LF signal for confirming whether or not possessed, the LF transmission antenna driving circuit for driving the LF transmission antenna, an RF signal for remotely operating the saddle on type vehicle The LF transmission antenna is mounted on a substrate , the LF transmission antenna and the LF transmission antenna drive circuit are connected to each other by a pattern of the substrate, and the LF transmission antenna and the LF transmission are provided in one housing. An antenna drive circuit and an RF receiving antenna are built in .

According to the keyless entry vehicle-mounted device according to the present invention, the LF antenna that transmits the LF signal for confirming whether the user has the portable device is a board on which various components of the keyless entry vehicle-mounted device are mounted. Has been implemented.
For this reason, it is possible to eliminate the communication frequency shift due to the parasitic inductance and to ensure good LF transmission performance.

It is a whole lineblock diagram showing the keyless entry system to which the keyless entry vehicle equipment concerning Embodiment 1 of this invention is applied. It is a block block diagram which shows the keyless entry vehicle-mounted apparatus which concerns on Embodiment 1 of this invention. It is explanatory drawing which shows the relationship between the frequency and impedance in LF antenna of the keyless entry vehicle-mounted apparatus which concerns on Embodiment 1 of this invention. It is explanatory drawing which shows arrangement | positioning of the antenna on the board | substrate in the keyless entry vehicle-mounted apparatus which concerns on Embodiment 1 of this invention. It is explanatory drawing which shows arrangement | positioning of the antenna on the board | substrate in the keyless entry vehicle-mounted apparatus which concerns on Embodiment 2 of this invention.

  Hereinafter, preferred embodiments of a keyless entry vehicle-mounted device according to the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts will be described with the same reference numerals. The keyless entry in-vehicle device of the present invention is applied to a keyless entry system for a saddle type vehicle such as a two-wheeled vehicle, a snowmobile, a water bike, etc., in which the LF communication range is established in only one area.

Embodiment 1 FIG.
1 is an overall configuration diagram showing a keyless entry system to which a keyless entry vehicle-mounted device according to Embodiment 1 of the present invention is applied. In FIG. 1, this keyless entry system includes a keyless entry vehicle-mounted device (hereinafter simply referred to as “vehicle device”) 2 mounted on a two-wheeled vehicle body 1 and a portable device 4 attached to a user 3 of the two-wheeled vehicle body 1. It consists of and. The two-wheel vehicle body 1 is provided with a start button 5.

  The user 3 presses the start button 5 to perform a keyless entry operation such as unlocking the two-wheeled vehicle body 1 or starting the engine. In addition, since the vehicle-mounted apparatus 2 has an antenna for performing communication, it is desirable to dispose the vehicle-mounted apparatus 2 avoiding the metal frame portion of the two-wheeled vehicle body 1. In this embodiment, the description will be made using a two-wheeled vehicle body. However, the present invention is not limited to this, and it may be a saddle type vehicle (for example, a snowmobile or a water bike) in which the system is established with one LF communication range. In this case, the first embodiment can be applied.

  FIG. 2 is a block configuration diagram showing the keyless entry vehicle-mounted device according to Embodiment 1 of the present invention. In FIG. 2, the in-vehicle device 2 includes a board 6 on which various components of the in-vehicle device 2 are mounted, and an LF antenna 7 that transmits an LF signal for confirming whether the user 3 has the portable device 4. And an LF antenna driving circuit 8 for driving the LF antenna 7 and an RF antenna 9 for receiving an RF signal for remotely operating the saddle type vehicle.

  Here, the LF antenna 7 includes a coil 10 and a capacitor 11, and the coil 10 and the capacitor 11 are integrally formed by a mold and mounted on the substrate 6. In the case of a saddle type vehicle in which the system is established in one area as in the first embodiment, the communication range of the LF antenna 7 can often include the communication range in one area. The LF antenna 7 can be taken into the in-vehicle device 2.

  FIG. 3 is an explanatory diagram showing the relationship between frequency and impedance in the LF antenna of the keyless entry vehicle-mounted device according to Embodiment 1 of the present invention. Specifically, the relationship between the LF antenna drive frequency of the LF antenna drive circuit 8 and the impedance of the LF antenna 7 is shown.

  In FIG. 3, at the center frequency, the impedance decreases, the current flowing through the LF antenna 7 increases, and the communication distance increases. When the center frequency is 125 kHz which is the LF band, the inductance of the coil 10 of the LF antenna 7 and the constant of the capacitance of the capacitor 11 are designed to be close to the above. At this time, even if one of the inductance and the capacitance is deviated from the rating, it is deviated from the designed center frequency from the actual communication frequency, and the communication performance is deteriorated.

  Here, as in the first embodiment, the LF antenna 7 and the LF antenna driving circuit 8 are mounted on the substrate 6 and connected by the pattern of the substrate 6, thereby comparing with a configuration in which a conventional LF antenna is connected by a harness. Thus, it is possible to eliminate a communication frequency shift due to the parasitic inductance of the harness, and to prevent a decrease in communication performance. Therefore, the copper foil pattern that connects the LF antenna 7 and the LF antenna drive circuit 8 is preferably the shortest path.

  Further, the LF antenna 7 transmits an LF signal at a predetermined interval in order to notify the timing when the user 3 of the vehicle presses the button to start the engine or the loss of the portable device 4. The portable device 4 transmits an RF signal to the in-vehicle device 2 according to the received power. When the in-vehicle device 2 receives the RF signal by the RF antenna 9, the in-vehicle device 2 permits the release of the steering lock and the engine start according to the RF signal.

  When the LF antenna 7 is taken into the in-vehicle device 2 and mounted on the substrate 6, the in-vehicle device 2 also has the RF antenna 9, and the RF antenna 9 is configured by a copper foil pattern or a sheet metal. Therefore, compared to the case where the LF antenna 7 is placed outside the in-vehicle device 2, the communication distance is likely to be reduced and the communication range may be distorted.

  Therefore, in order to solve this problem, as shown in FIG. 4 showing the arrangement of antennas on the substrate in the keyless entry vehicle-mounted device according to Embodiment 1 of the present invention, the LF antenna 7 and the RF antenna 9 are provided. In order to be separated as much as possible in the in-vehicle device 2, they are arranged near both ends of the substrate 6. In this way, by disposing at the end of the substrate 6 and increasing the spatial distance between the LF antenna 7 and the RF antenna 9, the influence of the metal of the RF antenna 9 is less likely to be given to the LF antenna 7.

  Furthermore, the influence of the metal can be further reduced by not drawing the GND pattern on the substrate 6 where the LF antenna 7 is projected.

  Thus, by mounting the LF antenna 7 on the substrate 6, the influence of the parasitic inductance due to the harness can be eliminated as compared with the configuration in which the LF antenna and the LF antenna driving circuit are connected by the harness. It is possible to reduce the communication distance deviation by reducing the communication frequency deviation amount with respect to the center frequency.

  Further, with respect to the deterioration of the antenna performance due to the proximity of the metal object, which is a problem when the LF antenna 7 is mounted on the substrate 6, the RF antenna 9 which is the main metal object is kept away, and the LF By not drawing a GND pattern on the substrate 6 on which the antenna 7 is projected, deterioration of the antenna performance can be prevented.

  In the case of using a harness, the manufacturing variation of the harness is large. However, the manufacturing variation can be suppressed by connecting the LF antenna 7 and the LF antenna driving circuit 8 with the copper foil pattern of the substrate 6. it can. Furthermore, since no harness is used, the influence of electromagnetic radiation from the harness and external electromagnetic waves is reduced, and electromagnetic compatibility can be improved.

  Moreover, since the vehicle-mounted device 2 can be accommodated in one package, the restrictions on the layout of the vehicle-mounted device 2 can be reduced. Furthermore, by mounting the LF antenna 7 on the substrate 6, the cost of the harness and the connector connected to the substrate 6 can be reduced. Moreover, since a potting material for improving the earthquake resistance and a plastic material for fixing are unnecessary, the cost can be further reduced.

As described above, according to the first embodiment, various components of the keyless entry vehicle-mounted device are mounted on the LF antenna that transmits the LF signal for confirming whether or not the user has the portable device. It is mounted on the board.
For this reason, it is possible to eliminate the communication frequency shift due to the parasitic inductance and to ensure good LF transmission performance.

Embodiment 2. FIG.
FIG. 5 is an explanatory view showing the arrangement of antennas on the substrate in the keyless entry vehicle-mounted device according to Embodiment 2 of the present invention. Here, the difference from the first embodiment is that the coil 10 and the capacitor 11 constituting the LF antenna 7 are separately mounted on the substrate 6. Other configurations are the same as those of the first embodiment described above, and thus description thereof is omitted.

  In FIG. 5, the coil 10 and the capacitor 11 constituting the LF antenna 7 are separately mounted on the substrate 6, so that the coil 10 and the capacitor 11 are integrally formed by molding as compared with the configuration of the first embodiment. . Cost can be reduced. That is, it is not necessary to use a capacitor-integrated LF transmission antenna, and it is only necessary to prepare each of them, so the cost of the LF antenna 7 can be reduced.

  In the case of using a harness, the manufacturing variation of the harness is large. However, the manufacturing variation can be suppressed by connecting the LF antenna 7 and the LF antenna driving circuit 8 with the copper foil pattern of the substrate 6. it can. Furthermore, since no harness is used, the influence of electromagnetic radiation from the harness and external electromagnetic waves is reduced, and electromagnetic compatibility can be improved.

  Moreover, since the vehicle-mounted device 2 can be accommodated in one package, the restrictions on the layout of the vehicle-mounted device 2 can be reduced. Furthermore, by mounting the LF antenna 7 on the substrate 6, the cost of the harness and the connector connected to the substrate 6 can be reduced. Moreover, since a potting material for improving the earthquake resistance and a plastic material for fixing are unnecessary, the cost can be further reduced.

  DESCRIPTION OF SYMBOLS 1 Two-wheel vehicle body, 2 vehicle-mounted apparatus, 3 user, 4 portable machine, 5 start button, 6 board | substrate, 7 LF antenna, 8 LF antenna drive circuit, 9 RF antenna, 10 coil, 11 capacitor | condenser.

Claims (4)

A keyless entry in-vehicle device that is applied to a keyless entry system for a top-type vehicle,
A board on which various parts of the keyless entry vehicle-mounted device are mounted;
An LF transmission antenna for transmitting an LF signal for confirming whether or not the user has a portable device;
And LF transmission antenna driving circuit for driving the LF transmission antenna,
An RF receiving antenna for receiving an RF signal for remotely operating the saddle-type vehicle,
The LF transmission antenna is mounted on the substrate, and the LF transmission antenna and the LF transmission antenna driving circuit are connected to each other by a pattern of the substrate,
A keyless entry vehicle-mounted device in which the LF transmitting antenna, the LF transmitting antenna drive circuit, and the RF receiving antenna are built in one housing . The keyless entry vehicle-mounted device according to claim 1, wherein the LF transmitting antenna and the RF receiving antenna are mounted on both ends of the substrate. The keyless entry vehicle-mounted device according to claim 1, wherein a GND pattern is not drawn at a location on the substrate where the LF transmission antenna is projected. The LF transmitting antenna is composed of a coil and a capacitor,
The keyless entry vehicle-mounted device according to any one of claims 1 to 3, wherein the coil and the capacitor are separately mounted on the substrate.

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