JPH11180250A - Seat belt mounting detecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect the mounted state of a seat belt without erroneous detection. SOLUTION: A seat belt mounting detecting device for electrically detecting whether or not a tongue 11 of a seat belt for a vehicle or the like is mounted in a buckle 20 is provided with a magnetic field control means for controlling the magnetic field, a magnetic field generating means for generating the specified magnetic field in the buckle 20, and a sensor means for detecting the change of the magnetic field, generated by the magnetic field generating means, due to insertion of the tongue 11 into the buckle 20. With this constitution, the mounted state of the seat belt can be detected in a contactless state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seat belt fastening detecting device for electrically detecting whether a seat belt is fastened or not fastened, for example, used in automobiles.

[0002]

2. Description of the Related Art In an SRS air bag system, the presence or absence of a seat belt is detected, and the explosion intensity of the air bag is changed according to the detection result. Therefore, it is required that the detection accuracy of the presence or absence of the seat belt is high. On the other hand, this type of conventional seatbelt fastening detection device has a configuration as shown in FIG. That is, FIG. 1 shows a seat belt device as an occupant protection device and a seat belt wearing detection device.

[0003] In FIG.
Belt and belt mounting bracket (hereinafter referred to as "tang")
And a belt fixing side member (hereinafter referred to as “buckle”). In addition, the seat belt wearing detection device,
A sliding contact provided inside the buckle, the sliding contact being movable in a tongue insertion direction, and an electrode made of a conductive metal material that is made electrically contactable when the sliding contact moves to a predetermined position, Belt attachment is detected by the conduction state of the sliding contact and the electrode.

[0004]

As described above, in the above-mentioned conventional seat belt attachment detecting device, the tongue is turned into a buckle when the conductive state at the contact by the sliding contact, that is, when the electric resistance value is approximately 0, is obtained. It was detected that it was inserted. However, the electrical contact system having such a configuration has a problem in that the mechanical contact pressure between the contact and the electrode is unstable, a non-conductive oxide film is easily formed on the contact member, and the contact state due to external vibration or the like. Is highly likely to cause poor contact due to instability. In addition, the tongue insertion portion of the buckle is open to the outside, and dust, dirt, and sometimes water, etc. existing in the cabin of the automobile may enter, resulting in the above-described poor contact and erroneous detection. It encourages the possibility of

[0005] Therefore, even when the seat belt is fastened, the detection device may output that the seat belt is not fastened, so that the SRS airbag system may be erroneously controlled. In view of the above-mentioned problems of the related art, the present invention proposes a non-contact type seatbelt detection device that does not have an electric / mechanical contact portion.

[0006]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, a seatbelt attachment detecting device for electrically detecting whether a tongue of a seatbelt of a vehicle or the like is attached to a buckle according to the present invention controls a magnetic field. Magnetic field generating means for generating a predetermined magnetic field in the buckle, and sensor means for detecting a change in the magnetic field generated by the magnetic field generating means due to insertion of the tongue into the buckle. It is characterized by having.

[0007] The magnetic field control means of the present invention can be applied to both cases where a magnetic field is interpreted and difficult to pass.
Specifically, according to Claims 2 and 3, which are one preferable aspect of the present invention, when the magnetic field control means is made of a metal material having a high magnetic permeability, the sensor means includes: When inserted into the buckle, it is detected that the intensity of the magnetic field generated by the magnetic field generating means has increased by the magnetic field control means. Conversely,
In the case where the sensor is made of a material having a low magnetic permeability, when the tongue is inserted into the buckle, the strength of the magnetic field generated by the magnetic field generating means near the sensor means is controlled by the magnetic field control. It is characterized in that it is detected by means that it has become smaller.

According to a fourth aspect of the present invention, the magnetic field generating means generates an alternating magnetic field. According to claim 5 which is a preferred aspect of the present invention, the magnetic field generating means includes a magnetic field generating coil. The integral shaping with the sensor means becomes possible. Although various kinds of sensor means can be applied, according to a preferred embodiment of the present invention, the sensor means is a coil having a predetermined number of turns.

When the sensor means is two sensor coils arranged in a plane in the insertion direction of the tongue, the arrangement of the sensor coils is characteristic. That is,
According to claim 7, which is a preferable aspect of the present invention, these sensor coils are provided closer to the first sensor coil provided farther from the buckle opening for inserting the tongue. A third sensor coil.

When the magnetic field control means is made of a metal material having high magnetic permeability, and when the sensor means is composed of two sensor coils, the arrangement of the sensor coils is characteristic. That is, according to claim 8, which is a preferred aspect of the present invention, the magnetic field generating means is disposed between the first sensor coil and the third sensor coil, and The sensor coil is arranged closer to the magnetic field generating means than the third sensor coil. With this arrangement, when no tongue is inserted, there is a difference between the outputs from the two sensor coils, which facilitates signal processing.

When the magnetic field control means is made of a metal material having a low magnetic permeability, and when the sensor means comprises two sensor coils, the arrangement of the sensor coils is characteristic. That is, according to claim 9 which is a preferred aspect of the present invention, the magnetic field generating means is disposed between the first sensor coil and the third sensor coil, and The sensor coil is disposed farther away from the magnetic field generating means than the third sensor coil.

In a case where the magnetic field control means is made of a metal material having high magnetic permeability, the magnetic field generating means is a preferred embodiment of the present invention. The sensor coil is disposed at an intermediate position between the first sensor coil and the third sensor coil, and the number of turns of the first sensor coil is set to be larger than the number of turns of the third sensor coil. The same effect as that of No. 9 can be achieved.

In a case where the magnetic field control means is made of a metal material having low magnetic permeability, the magnetic field generation means may be a preferred embodiment of the present invention. It is arranged at an intermediate position between the sensor coil and the third sensor coil, and the number of turns of the first sensor coil may be set smaller than the number of turns of the third sensor coil.

According to a twelfth aspect of the present invention, the magnetic field generating means, the first sensor coil and the third sensor coil are formed on the same plane.
The positional relationship between the sensor coil and the magnetic field generating means, which can reduce the size of the device configuration, can be set variously. For example, according to claim 13, which is a preferred aspect of the present invention, the first sensor coil and the third sensor coil are different from the magnetic field generating means via a space into which the tongue is inserted. It is formed on a plane.

In view of the fact that the output from the sensor means is weak, a preferred embodiment of the present invention is that the buckle includes a processing circuit for processing the output signal of the sensor means. As a result, noise can be prevented from being mixed. The magnetic field control means can take various arrangements or configurations. For example, according to claim 15, which is a preferred aspect of the present invention, the magnetic field control means is a metal portion near the tip of the tongue. Further, according to claim 16, which is a preferable aspect of the present invention, the magnetic field control unit includes:
A locking member made of a magnetically permeable metal that moves in the direction of the sensor means when the tongue is inserted into the buckle to lock the tongue.

[0016] The above-described problem is caused by a detection device having another configuration, for example,
A seat belt attachment detection device for electrically detecting whether or not a permeable tongue of a seat belt of a vehicle or the like is inserted into a gap in a buckle according to claim 17, wherein the buckle in the gap is A first sensor coil and a third sensor coil which are spaced apart from each other along a direction in which the tongue is inserted, a first circuit for generating an AC signal including an AC component, A magnetic field generating element disposed between the first sensor coil and the third sensor coil and driven by the AC signal to generate an alternating magnetic field; and an output of the first sensor coil and the third sensor coil. And a third circuit for detecting a phase difference between the AC signal and the differential signal, and a second circuit for generating a differential signal between the signals. In this case, whether or not the magnetically permeable tongue has been inserted into the gap is electrically detected based on the output of the third circuit.

According to a preferred embodiment of the present invention, the magnetic field generating element is a second coil. According to Claim 19, which is a preferable aspect of the present invention, the first
Is provided at a position farther from the buckle opening for inserting the tongue, and the third sensor coil is provided at a position closer to the buckle opening.

According to a preferred embodiment of the present invention, the magnetic field generating element is disposed between the first sensor coil and the third sensor coil. Are arranged closer to the magnetic field generating element than the third sensor coil. According to Claim 21 which is a preferred aspect of the present invention, the magnetic field generating element is disposed between the first sensor coil and the third sensor coil,
The number of turns of the first sensor coil is larger than the number of turns of the third sensor coil.

According to a preferred embodiment of the present invention, the magnetic field generating element, the first sensor coil and the third sensor coil are formed on the same plane.
According to Claim 23 which is a preferable aspect of the present invention, the first sensor coil and the third sensor coil are arranged on a plane different from the magnetic field generating element via a space into which the tongue is inserted. Is formed.

According to claim 24, which is a preferred aspect of the present invention, the first to third circuits are provided near the sensor coil in the buckle. 23. The seat belt wearing detection device according to any one of 23. According to claim 25, which is a preferred embodiment of the present invention, the first sensor coil and the third sensor coil are made of a printed wiring board material.

According to a twenty-sixth aspect of the present invention, the first sensor coil and the third sensor coil are connected in series with opposite polarities. 25. The seat belt wearing detection device according to any one of 25. 27. A preferred embodiment of the present invention.
According to the third aspect, the third circuit has a D-type flip-flop for phase comparison, and a resistor is connected between the Q output terminal and the D input terminal of the flip-flop. According to a preferred embodiment of the present invention, which can provide a hysteresis characteristic and is resistant to noise, the buckle has a hook member for fixing the tongue inside the buckle, and the sensor coil performs this movement. To detect.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a seat belt detection system for electrically detecting whether or not a permeable tongue of each seat belt is inserted into a gap in a buckle in a vehicle or the like provided with a plurality of seat belts. This can also be achieved by a device. That is, in the tote belt attachment detection device according to claim 29, the first sensor coil and the third sensor coil disposed separately in the buckle of each of the plurality of seat belts along the tongue insertion direction. And the first
A magnetic field generating element that is arranged between the first sensor coil and the third sensor coil and that is driven by an AC signal to generate an alternating magnetic field; and outputs the outputs of the first sensor coil and the third sensor coil. And a difference detection circuit for generating a difference signal between them is a signal processing circuit provided at a position separated from and separated from the plurality of seat belts and the buckle. Occurs
A first circuit for supplying each magnetic field generating element of each buckle, and a third circuit for detecting a phase difference between the AC signal and a difference signal from a difference detection circuit of each buckle.
Circuit.

With this, it is possible to electrically detect whether the magnetically permeable tongue is inserted into the gap, and to share the first circuit and the third circuit for each buckle.

[0024]

Embodiments of the present invention will be described below with reference to the drawings. <Mechanical Structure> FIG. 2 shows a seatbelt device to which the detection device and the detection method of the present invention are applied.

In FIG. 2, reference numeral 10 denotes a known automobile seat belt, and a tongue 11 is attached to a tip of the belt 10. In the buckle 20, an opening 21 and
A fixing device (not shown) for fixing the tongue 11 inserted into the opening 21 and a detecting device (hereinafter, referred to as a seat belt tongue detecting device) 100 for detecting whether or not the seat belt tongue has been inserted. Are provided.

The seat belt tongue detecting device 100
Formed on the member 21 forming the mouse opening 21;
Three coils 101 to 103, a protective film 104 formed of a material such as glass epoxy for protecting these coils, and a tongue 1 formed of a metal having high magnetic permeability.
1, a signal processing circuit 110 described later and the like.
The detection device 100 is a non-contact type detection device that detects a magnetic field change. However, the tongue 11 that promotes a magnetic field change by being inserted into the opening 21 is usually made of a metal such as iron. Therefore, the detection device is substantially 3
It is composed of three coils 101 to 103, a protective film 104, and a signal processing circuit 110.

<Principle> FIG. 4 shows a more detailed configuration of the coils 101 to 103. That is, these coils are formed as a known print pattern on the surface of the circuit board 100 by etching a copper foil, and the pattern of each coil is formed by a spiral pattern as shown in an enlarged scale 1000 in FIG. It has a planar coil shape. As described later, an AC signal is applied to the coil 102, and the coil 102 generates an alternating magnetic field. 4 and 6, the magnetic flux φ ₂ is the magnetic flux generated by the coil 102, and the magnetic flux φ ₁ is a part of the magnetic flux generated by the coil 102.
The magnetic flux interlinking the 1, phi ₃ is a part of the magnetic flux coil 102 is generated, representing the magnetic flux interlinking the coil 103. In addition, as shown in FIGS. 6 and 3, the distance (= l ₁ ) 106 between the coil 101 and the coil 102 is set to be shorter than the distance 107 (= l ₃ ) 107 between the coil 102 and the coil 103. , Coils 101 to 103 are provided.

The mounting position of the coil 102 inside the buckle 20 is such that when the tongue 11 is completely inserted into the opening 21 of the buckle 20, the tip of the tongue substantially coincides with the vicinity of the center of the coil 102. It is located as a configuration. In this way, by disposing the coil 101 and the coil 103 with respect to the coil 102, the coil 101 and the coil 103 function as a sensor for detecting a change in magnetic flux. That is, when the tongue 11 is not inserted into the buckle, as shown in FIG. 6, the coil 102 generates a target alternating magnetic field around it, but the coil 1 provided at a position further away from the coil 102.
03 has less magnetic flux linkage than the coil 101 provided at a closer position. That is, the flux linkage φ ₁ of the coil 101> the flux linkage φ of the coil 103.
₃

On the other hand, as shown in FIG. 7, when the tongue 11 is completely inserted into the buckle, the tip of the tongue 11 just above the coil 102, at least almost covers the coil 102. , Coil 101
The length is set so that it does not reach above. Therefore, when the tongue 11 is completely inserted into the buckle, most of the magnetic field lines of the alternating magnetic field generated by the coil 102 pass through the tongue 11, and therefore, the coil 1
The magnetic flux linking 01 decreases sharply. Further, since most of the magnetic lines of force passing through the tongue 11 pass through the coil 103, the coil 1
The magnetic flux linking 03 increases.

The seatbelt / tongue wearing detection device is
By detecting a change in the distribution pattern of the magnetic field appearing in the two sensor coils (101, 103) as shown in FIGS. 6 and 7, it is detected whether or not the tongue 11 is completely mounted. The signal processing circuit 110 that detects a change in the distribution pattern of the magnetic field includes the sensor coils 101 and 10.
Since the signal from 3 is weak, as shown in FIG. 3, it was provided in the member 22 near the coils 101 to 103. FIG. 8 shows a configuration of the signal processing circuit 110.

<Structure of Electric Circuit> In FIG. 8, the detection circuit 110 includes a constant voltage circuit (V-REG) 111, a circuit (OSC) 112 for oscillating a sine wave, and a buffer 1 for amplifying power.
13, an amplifier (AMP) 114, and a phase difference detection circuit (PHASE-
DET) 115. The constant voltage circuit 111 has a T100
The output of a sine wave oscillation circuit 112 that is connected to a battery of a vehicle (not shown) and supplies power to each circuit element forming each individual electronic circuit of the signal processing circuit 110 through T101 through a constant DC voltage. Is supplied to the buffer circuit 112 and the phase detection circuit 115 via the output terminal T103. The output of the buffer circuit 112 is connected to the coil 102. That is, the power-amplified sine wave is input to the coil 102, and the coil 102 generates an alternating magnetic field that varies sinusoidally around the sine wave. This alternating magnetic field penetrates through the inside of the coil 101 and the coil 103 as shown in FIG. 7, so that the coil 101 and the coil 103 detect the AC voltage induced in each.

As shown in FIG. 8, the coils 101 and 103
Of the respective coil windings are connected to each other, so that the coils 101 and 103 are connected in series. The winding of the coil 101 that is not connected to the coil 103 is connected to the terminal T104 of the amplifier circuit 114, and the winding of the coil 103 that is not connected to the coil 101 is connected to the terminal T105 of the amplifier circuit 114. I have. Coil 102 is mutually coupled with coil 11 and coil 103, respectively. FIG. 9 shows coils 101 and 103
And the connection between the output of the amplifier 114 and the amplifier 114, and the connection between the phase difference detection circuit 115, the amplifier 114 and the oscillator 112.

In FIGS. 8 and 9, black circles (".") Added to the symbols of the coils indicate terminals at which induced voltages of the same polarity are detected. FIG. 10 shows the phase detection circuit 115.
The detailed configuration of is shown. That is, the phase detection circuit 115 includes a D-type flip-flop 201 (for example, TC4013BP manufactured by Toshiba) that inputs a sine wave signal (representing a reference phase) from the oscillation circuit 112 at T200, and a waveform shaping circuit (SHAPER) 202. And various resistors. Q output terminal of flip-flop 201 (T20
3) and the D input terminal (T202) are connected by a resistor R203. Also, flip flop 201
D terminal T202 is connected to the output side of the amplifier circuit 114 via the resistor R202.

The waveform shaping circuit 202 delays the phase of the sine wave signal (T103) from the oscillator 112 by 90 degrees, converts the signal into a rectangular wave, and converts the sine wave signal into a rectangular wave.
To the clock input terminal (T200). This clock signal is shown in FIG. T103) phase is 90
The significance of delaying will be described later. 8 and 9
, The amplifier 114 includes an induced voltage e ₁ generated by the coil 101 (described later) and a voltage e ₁ induced by the coil 103.
Amplify the difference from ₃ (described later). As will be described later, this difference signal is also an AC signal, and reflects whether or not the tongue 11 has been inserted into the buckle. The amplified output signal is input to the phase detection circuit 115.

In FIG. 8 and FIG.
5 compares the phase of the differential AC signal with the phase of the reference sine wave signal generated by the oscillator 112 to determine whether there is a phase difference. The output of the detection circuit 115 is a signal indicating whether or not the tongue 11 has been completely inserted into the buckle. <Description of Operation> The operation of the signal circuit 110 having the above configuration will be described below with reference to the drawings.

The constant voltage circuit 111 includes a vehicle (not shown).
Approximately 12V DC voltage to T100 via IG switch
Supplied. The constant voltage circuit 111 is a well-known series regulator.
The voltage stabilized at 5V by the rectifier method is from T101
Output to supply necessary power to each circuit element. Oscillation circuit
The output T103 of 112 is about 400, as shown in FIG.
5V at KHz _ppIs a sine wave signal of This sine wave signal
Is input to the phase detection circuit 115 and the buffer circuit 112.
Is done.

The buffer 113 power-amplifies the sine wave signal.
To apply the AC signal to the beginning of winding of the coil 102.
You. The other end of the coil 102 is the reference potential of the circuit board 100
(GND). Thereby, the coil 1
Flux φ from 02_TwoOccurs. As shown in Figure 2, the tongue
11 is not completely inserted into the buckle 20
In the situation, as described above, the magnetic flux φ₁And φ_ThreeSize of
Is the flux linkage φ of the coil 101₁> Chain of coil 103
Intersection flux φ_Three(See FIG. 6). Therefore, the linkage flux φ₁To
Thus, the induced electromotive voltage e of the coil 101 generated₁Is better
Linkage magnetic flux φ_ThreeVoltage induced by coil 103
Pressure e _ThreeLarger than.

Induced electromotive voltage e ₁ > Induced electromotive voltage e ₃ The induced electromotive voltage e ₁ of the coil 101 has the same phase as the output signal of the oscillation circuit 112 according to the winding direction, and the induced electromotive voltage e _{3 of the} coil 103. The phase of the generator 11
2 is opposite in phase to the output signal of
The input signal (= e ₁ −e ₃ ) of the oscillation circuit 112 is, as shown in FIG.
Has the same phase as the output signal T103.

On the other hand, as described with reference to FIG. 8, when the tongue 11 is completely inserted into the buckle 20, the tongue 11 is a magnetic material (or a metal having high magnetic permeability). Then, the magnetic resistance of the space in the opening 21 decreases, and most of the magnetic flux φ ₂ generated by the coil 102 passes through the inside of the magnetic material to the coil 103 side. That is, the influence of the difference between the separation distances l ₁ and l ₃ disappears, and many lines of magnetic force pass through the coil 103 side. Therefore, the linkage fluxes φ ₁ and φ ₃ satisfy φ ₁ <φ ₃ . To this end, the input terminal T
The phase of the differential signal at 104 is opposite to the output signal T103 of the oscillation circuit 112, as shown in FIG. Further, the amplifier circuit amplifies the signal of the input signal T104 at a predetermined magnification, and then outputs the signal from the terminal T106 as a sine wave signal of approximately 5 (V _pp ).

The flip-flop 201 shown in FIG. 10 corresponds to the output signal (difference signal) from the amplifier 114.
The phase difference from the reference sine wave signal is detected. Hereinafter, the operation of the flip-flop 201 will be described in detail. FIG.
Is a change in the D input (T202) following the change in the phase of the signal T106 from the amplifier 114 with respect to the clock signal T200 (indicated by d in the figure) input to the clock terminal of the flip-flop 201 (see FIG. Where e, f, g,
h).

In FIG. 12, V _th is a threshold value for distinguishing whether the flip-flop 201 is set or reset based on a signal input to its D terminal. That is, since the flip-flop 201 is D-type, at the leading edge of the clock input T200,
When the D input is higher than _Vth , the device is set (Q output is "1"), and when the D input is lower than _Vth , the device is reset (Q output is "0").

When the Q output of the flip-flop 201 is high (ie, the flip-flop 201 is set), it is determined that the seat belt tongue 11 has not been inserted. The state in which the flip flop 201 is reset) is defined as the seat belt tongue 11 being determined to be inserted. Therefore,
In a state where the tongue 11 is not inserted into the buckle 20, at the leading edge of the clock signal T200, the D input T202 of the flip-flop 201 is larger than the threshold value V _th as shown in FIG. -With the flop 201 set, the tongue is determined not to be inserted in the detection result.

When the seatbelt tongue 11 is inserted and approaches the vicinity of the coil 103, the signal T202 becomes
F. Even in this case, the clock signal T20
At each leading edge of 0, the D input T202 is larger than the threshold value _Vth as shown in FIG. 12F, so that the flip-flop 201 remains set and the tongue is determined not to be inserted in the detection result. . In other words, the threshold V
_th is set to obtain such a result.

When the seat belt tongue 11 is further inserted, the tongue 11 comes to be located above the coil 103. At this time, the signal T202 becomes as shown in FIG. 12G, and at each leading edge of the clock signal T200, the D input T202 becomes equal to or less than the threshold value _Vth . For this reason, the flip-flop 201 is reset, and the detection result determines that the tongue is inserted.

The phase difference detection circuit 115 is configured to have a hysteresis characteristic. For this purpose, the Q output and the D input of the flip-flop 201 are connected by a resistor R203, so that the T202 signal as the D input is affected by the value of the signal T203 as the Q output. Here, the threshold value V _th is determined by the flip-flop 20
When 1 is reset, the threshold voltage is set as a threshold voltage for the D input of the flip-flop 201 when the flip-flop 201 is inverted to the set state. By using such a threshold value V _th ,
When the flop 201 is set in advance, the terminal T202 is biased higher than when the flip-flop 201 is reset. It is difficult to set for D input.

In FIG. 12, flip flop 20
When 1 is reset, the signal T202 shifts from the state of g to the state of h due to the change in the bias even if the seat belt tongue 11 does not move at all. Then
The same effect as that of the threshold value being relatively increased is produced, so that even if there is a slight change in the signal T202, the flip-flop 201 is hard to be set.

As described above, the circuit 115 has a hysteresis characteristic as shown in FIG. <Effect of Embodiment> With the above configuration, the seatbelt wearing detection device of the present invention detects that the tongue is inserted into the buckle of the seatbelt without having an electrical / mechanical contact portion. To output an “L” level electric signal, and additionally output an “H” level before the tongue is inserted,
Hysteresis is applied to the characteristics of the "L" level output state after the tongue is inserted, so even under poor environmental conditions such as vibration, dust and water, the seatbelt can be reliably detected. It is possible to do.

The phase of an output signal obtained by serially connecting a coil (102) driven by a high-frequency signal and two detection coils (101, 103) disposed at both ends thereof, and the phase of a drive signal are determined. Because the configuration was compared, 1
Compared to a metal detection method such as a high-frequency proximity sensor that converts the inductance change due to the coil into an electric signal, the structure has no sensitivity to the change in distance between the tongue and the circuit board, that is, the detection unit, and mechanical vibration and It has an excellent feature that a change in current of a drive coil due to a change in temperature of a circuit board or a change in characteristics due to a variation in circuit elements is small, and the position of the tongue in the direction of entry can be accurately detected.

In addition, since the two detection coils are connected in opposite directions to take out a signal, an induced electromotive voltage in the detection coils due to electromagnetic field noise applied from outside the buckle is the same in each coil. Since it occurs in the polarity, it cancels out as a result, and has a feature that there is no influence on the detection signal.
Further, in the seat belt wearing detecting means of the above embodiment,
Since the detection element is a pattern coil formed on a circuit board, the elements (pattern coil) on the circuit board can be compared to the method of soldering and mounting individual components (coils, Hall elements, phototransistors, etc.) on the circuit board. ) Can be manufactured with high position accuracy, and thus has the advantage of high position detection accuracy.

<Modifications> The present invention can be variously modified without being limited to the above-described embodiments without departing from the gist thereof. <First Modification> For example, in the above-described embodiment, in a state where the seatbelt tongue 11 is not inserted, an output difference is provided between the two sensor coils 101 and 103 as shown in FIG. In addition, the positions of the sensor coil 101 and the sensor coil 103 with respect to the coil 102 are different. However, in order to generate an output difference, for example, as shown in FIG. 14, the number of turns n ₁ of the sensor coil 101 is made smaller than the number of turns n ₃ of the sensor coil 103.

<Second Modification> In the above embodiment, the coil 102 is arranged on the same side as the sensor coil 101 and the sensor coil 103. However, the present invention is not limited to this. As shown in (1), the sensor coil 101 and the sensor coil 103 may be arranged on the side opposite to the coil 102 with respect to the seat belt tongue 11.

In this case, as shown in FIG.
As shown in FIG. 5, it is necessary that l ₃ > l ₁ . The method of the first modification may be applied to the second modification. <Third Modification> In the above-described embodiment, the first modification, and the third modification, it is assumed that the seat belt tongue 11 is made of a metal having high magnetic permeability. However, the tongue 11 does not need to be a metal with high magnetic permeability as long as the rigidity is high. Conversely, it can be made of a metal having a very low magnetic permeability, for example, aluminum.

On the contrary, a metal having a low magnetic permeability has a property of eliminating lines of magnetic force. For this reason, when such a metal is adopted for the seat belt tongue 11, for example, as shown in FIG. 16, the polarities of the sensor coil 101 and the sensor coil 103 are connected in reverse to the embodiment, and And their arrangement needs to be l ₃ <l ₁ as shown in FIG.

With this arrangement, when the seatbelt tongue 11 is not inserted, the sensor coil 1
Many interlinkage magnetic fluxes occur on the 03 side, and e ₃ > e _1. However, by reversing the connection from the embodiment, the output from the amplifier 114 becomes the same as the above embodiment.
Here, when the seat belt tongue is inserted, FIG.
As shown in the figure, the tongue 11 acts in the direction of decreasing the flux linkage to the sensor coil 103 and increasing it to the sensor coil 101, so that the seat belt tongue 11
The change of the signal T202 in the process of inserting is the same as in the above embodiment.

The method of the third modification can be applied to the first and second modifications. <Fourth Modification> In the above embodiment and its modifications, the coils 101, 102, and 103 and the circuit components shown in FIG. 8 are mounted on one circuit board 100. About the seatbelt attachment point is 2
There are a plurality of about five. Therefore, it is not necessary to mount all the circuit elements of the present invention inside the buckle of each seat belt, and all the circuit functions such as the oscillation circuit / buffer circuit, the phase detection circuit, and the power supply circuit can be shared by a plurality of seat belts. It is a thing.

Therefore, as shown in FIG. 18, a plurality of buckles are wired from an airbag control unit (ECU) disposed at one place, and inside each buckle, the three pattern coils shown in the first embodiment are used. A structure in which only a substrate is formed is incorporated. According to this configuration, the volume for mounting the circuit board required for each buckle can be small, and the number of electronic components used by common use can be reduced.
It is possible to greatly reduce the manufacturing cost.

<Other Modifications> In the above embodiment and the first to fourth modifications, the insertion amount of the tongue is detected at the tip position of the tongue to be inserted into the buckle. The detection of seatbelt attachment, which is the object of the present invention, is not limited to the above-described configuration. For example, as shown in FIG. 19, a modification is made to detect the position of a known hook that descends to lock the tongue in the buckle. You may.

The electric circuit element of each part used in the present invention, for example, the oscillating circuit is not limited to a sine wave oscillating circuit, but may be a rectangular wave or the like. In addition, the amplifying circuit includes a known narrow band filter or the like. Things are also possible. next,
The pattern coil on the circuit board and the signal detection circuit system used in the seatbelt attachment detection device of the present invention are not limited to the seatbelt attachment detection application which is the final object of the present invention, and do not depart from the gist of the present invention. It can be understood that the present invention exerts an excellent effect even when used for position detection of other mechanical structures and the like.

[0059]

As described above, according to the present invention, it is possible to provide a non-contact type seat belt wearing detecting device which performs a stable operation with less erroneous detection.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of a conventional seatbelt attachment detection device.

FIG. 2 is a diagram illustrating a configuration of a seatbelt attachment detection device according to a preferred embodiment of the present invention.

FIG. 3 is a diagram showing a configuration of a main part of the seat belt wearing detection device of the embodiment.

FIG. 4 is a view for explaining coil arrangement in a main part of FIG. 3;

FIG. 5 is a diagram illustrating the shape of a coil used in the embodiment.

FIG. 6 is a diagram illustrating a detection principle of an embodiment using two sensor coils.

FIG. 7 is a view for explaining a state in which the insertion of the seat belt tongue 11 causes a change in magnetic flux linking two sensor coils.

FIG. 8 illustrates a configuration of a circuit 100 according to an embodiment.

FIG. 9 is a diagram illustrating connection between three coils and various circuits.

FIG. 10 illustrates a configuration of a phase detection circuit 115.

FIG. 11: Reference AC signal and flip-flop 201
4 is a timing chart comparing the clock signal of FIG.

FIG. 12 is a timing chart illustrating a comparison between a D input (T202) and a clock input (T200) of the flip-flop 201 in a process of gradually inserting the tongue 11;

FIG. 13 is a view for explaining how a hysteresis characteristic occurs in the embodiment.

FIG. 14 is a diagram illustrating the number of turns of three coils and the arrangement of the coils according to a first modified example.

FIG. 15 is a diagram illustrating an arrangement of three coils according to a second modified example.

FIG. 16 is a diagram illustrating connection of two sensor coils according to a third modified example.

FIG. 17 is a diagram illustrating an arrangement of two sensor coils according to a third modified example.

FIG. 18 is a diagram illustrating a configuration of a fourth modification. .

FIG. 19 is a diagram illustrating a configuration of another modification. .

Claims (29)

[Claims] 1. A seat belt attachment detecting device for electrically detecting whether or not a tongue of a seat belt of a vehicle or the like is attached to a buckle, a magnetic field control means for controlling a magnetic field, and a predetermined magnetic field in the buckle. A seat belt attachment detection device comprising: a magnetic field generating means for generating; and a sensor means for detecting a change in a magnetic field generated by the magnetic field generating means due to insertion of the tongue into the inside of the buckle. 2. The magnetic field control means is made of a metal material having a high magnetic permeability, and the sensor means detects that the intensity of the magnetic field generated by the magnetic field generation means when the tongue is inserted into a buckle. The seat belt wearing detecting device according to claim 1, wherein the increase is detected by magnetic field control means. 3. The magnetic field control means is made of a material having low magnetic permeability, and the sensor means is a sensor means for detecting a magnetic field generated by the magnetic field generating means when the tongue is inserted into a buckle. 2. The seatbelt attachment detecting device according to claim 1, wherein the magnetic field control unit detects that the intensity in the vicinity is reduced. 4. The seat belt attachment detecting device according to claim 1, wherein said magnetic field generating means generates an alternating magnetic field. 5. The apparatus according to claim 1, wherein the magnetic field generating means includes a magnetic field generating coil. 6. The seat belt attachment detecting device according to claim 4, wherein said sensor means includes a coil having a predetermined number of turns. 7. The sensor means comprises two sensor coils arranged in a plane in the tongue insertion direction, wherein the first sensor coil is provided at a position farther from a buckle opening for inserting the tongue. The seatbelt attachment detection device according to claim 4, further comprising: a sensor coil of (1) and a third sensor coil provided at a closer position. 8. The magnetic field control means is made of a metal material having high magnetic permeability, and the magnetic field generation means is arranged between the first sensor coil and the third sensor coil. The seat belt wearing detection device according to claim 7, wherein the first sensor coil is arranged closer to the magnetic field generating means than the third sensor coil. 9. The magnetic field control means is made of a metal material having a low magnetic permeability, and the magnetic field generation means is arranged between the first sensor coil and the third sensor coil. The seatbelt attachment detecting device according to claim 7, wherein the first sensor coil is arranged at a greater distance from the magnetic field generating means than the third sensor coil. 10. The magnetic field control unit is made of a metal material having high magnetic permeability, and the magnetic field generation unit is arranged at an intermediate position between the first sensor coil and the third sensor coil.
The seat belt attachment detecting device according to claim 7, wherein the number of turns of the first sensor coil is larger than the number of turns of the third sensor coil. 11. The magnetic field control unit is made of a metal material having low magnetic permeability, and the magnetic field generation unit is disposed at an intermediate position between the first sensor coil and the third sensor coil.
The seat belt attachment detecting device according to claim 7, wherein the number of turns of the first sensor coil is smaller than the number of turns of the third sensor coil. 12. The seat belt attachment detecting device according to claim 7, wherein the magnetic field generating means, the first sensor coil, and the third sensor coil are formed on the same plane. 13. The device according to claim 13, wherein the first sensor coil and the third sensor coil are formed on a plane different from the magnetic field generating means via a space into which the tongue is inserted. Item 7. A seat belt wearing detection device according to item 7. 14. The seat belt attachment detection device according to claim 1, further comprising a processing circuit for processing an output signal of the sensor means in the buckle. 15. The seat belt attachment detecting device according to claim 1, wherein the magnetic field control unit is a metal portion near a tip end of the tongue. 16. The magnetic field control means is a magnetically permeable metal locking member which moves in the direction of the sensor means when the tongue is inserted into the buckle in order to lock the tongue. Claims 1 to 15
The seatbelt wearing detection device according to any one of the above. 17. A seat belt attachment detecting device for electrically detecting whether or not a magnetically permeable tongue of a seat belt of a vehicle or the like is inserted into a gap in a buckle. A first sensor coil and a third sensor coil which are spaced apart from each other in the insertion direction of the tongue, a first circuit for generating an AC signal including an AC component, and the first sensor coil. A magnetic field generating element that is disposed between the first sensor coil and the third sensor coil and that is driven by the AC signal to generate an alternating magnetic field; A second circuit for generating a difference signal between them, and a third circuit for detecting a phase difference between the AC signal and the difference signal.
And a circuit for electrically detecting whether or not the magnetically permeable tongue has been inserted into the gap based on an output of the third circuit. 18. The apparatus according to claim 17, wherein the magnetic field generating element has a second coil. 19. The device according to claim 19, wherein the first sensor coil is provided at a position farther from a buckle opening for inserting the tongue, and the third sensor coil is provided at a position closer to the buckle opening. The seat belt wearing detection device according to claim 17. 20. The magnetic field generating element is disposed between the first sensor coil and the third sensor coil, and the first sensor coil is smaller than the third sensor coil. 20. The seat belt wearing detection device according to claim 19, wherein the device is arranged closer to the magnetic field generating element. 21. The magnetic field generating element is disposed between the first sensor coil and the third sensor coil, and the number of turns of the first sensor coil is equal to that of the third sensor coil. 20. The seat belt wearing detection device according to claim 19, wherein the number of windings is larger than the number of windings. 22. The seat belt attachment detecting device according to claim 19, wherein the magnetic field generating element, the first sensor coil, and the third sensor coil are formed on the same plane. 23. The device according to claim 23, wherein the first sensor coil and the third sensor coil are formed on a plane different from the magnetic field generating element via a space into which the tongue is inserted. Item 20. The seat belt wearing detection device according to item 19. 24. The seat belt attachment detecting device according to claim 17, wherein the first to third circuits are provided near the sensor coil in the buckle. 25. The seat belt attachment detecting device according to claim 15, wherein the first sensor coil and the third sensor coil are made of a printed wiring board material. 26. The seat belt wearing detecting device according to claim 17, wherein the first sensor coil and the third sensor coil are connected in series with opposite polarities. 27. The third circuit, comprising a D-type flip-flop for phase comparison, wherein a resistor is connected between the Q output terminal and the D input terminal of the flip-flop. The seatbelt fastening detection device according to any one of claims 17 to 26. 28. The seat belt attachment detecting device according to claim 17, further comprising a hook member for fixing the tongue inside the buckle, and wherein the sensor coil detects the movement. . 29. A seat belt attachment detecting device for electrically detecting whether or not a permeable tongue of each seat belt is inserted into a gap in a buckle in a vehicle or the like provided with a plurality of seat belts, In each of the buckles of the plurality of seat belts, a first buckle that is spaced apart along the insertion direction of the tongue is provided.
A sensor coil, a third sensor coil, a magnetic field generating element disposed between the first sensor coil and the third sensor coil, and driven by an AC signal to generate an alternating magnetic field; A difference detection circuit that receives an output of the sensor coil and the third sensor coil and generates a difference signal therebetween; and is provided at a position separated from and separated from the plurality of seat belts and the buckle. A signal processing circuit, comprising: a first circuit that generates an AC signal including an AC component and supplies the signal to each magnetic field generating element of each buckle; and a difference between the AC signal and a difference detection circuit of each buckle. A third circuit for detecting a phase difference between each signal and a signal; electrically detecting whether or not the magnetically permeable tongue is inserted into the gap; Seat belt wearing detecting apparatus is characterized in that in common for each of the buckle circuitry.