JPH07237484A - In-seat detecting device - Google Patents

Abstract

PURPOSE:To surely perform in-seat decision with errorless operation even under a noisy environment. CONSTITUTION:A device is constituted of a control board of arranging a microcomputer for outputting a decision result by deciding the human body for whether provided or not on a seat and a conductive box 18 built in with the control board and conducted to a conductive shield material 1. An output terminal of a piezoelectric sensor, enveloped by the conductive shield material 1, is fixed to the control board, and further the control board is built in the conductive box 18 conducted to the conductive shield material 1. Thus by completely shielding the piezoelectric sensor and the control board, noise infiltration to the piezoelectric sensor and the box 18 is eliminated, accordingly, to prevent erroneous operation due to a noise such as in the past.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an occupant detection device for detecting the presence or absence of a human body on a seat.

[0002]

2. Description of the Related Art The inventors have found that, for example, a conventional seating detection device having a microswitch disposed on a seat has a problem of malfunctioning even when an object is placed on the seat, the switch is turned on by the load. In order to solve the above problem, an in-situ detection device having the structure shown in FIG. 7 was devised. That is, the piezoelectric sensor 2 (not shown) contained in the conductive shield material 1 is arranged under the seat cloth of the seat 3 so as not to impair the seating feeling, and the output from the piezoelectric sensor 2 is derived by the shield wire 4. The determination means (not shown) incorporated in the control unit 5 extracts the fine body movement caused by the heartbeat and respiration of the human body from the output signal of the piezoelectric sensor 2, and if there is a fine body movement component in the signal, the person is seated. And the determination result was output from the output line 6.

[0003]

However, in the presence detection device of the above technique, the piezoelectric sensor 2 itself has a high impedance, and since it processes a minute signal due to the above-described fine body movement, the influence of noise is affected. There is a problem that it is easily received, and in particular, when a distance between the piezoelectric sensor 2 and the control unit 5 is required due to installation restrictions, erroneous determination may occur due to noise intrusion from the shield wire 4.

A first object of the present invention is to eliminate the above-mentioned malfunction due to noise intrusion from the shielded wire 4.

Further, since there is a problem of malfunction due to noise intrusion from the output line 6 under a strong electric field, a second object of the present invention is to eliminate malfunction due to noise intrusion from the power supply line and output line.

Further, when the piezoelectric sensor 2 is arranged on the seat 3, since the detection area is widened, it is difficult to assemble the piezoelectric sensor 2 such that the piezoelectric sensor 2 has to meander under the outer cloth to fix the tape. A third object of the present invention is to make the piezoelectric sensor 2 easy to dispose on the seat.

A fourth object of the present invention is to reduce the number of parts and improve reliability.

A fifth object of the present invention is to improve the strength of the device.

[0009]

In order to achieve the above-mentioned first object, the present invention provides a piezoelectric sensor disposed in a seat and enclosed in a conductive shield material, an output terminal of the piezoelectric sensor, and the piezoelectric sensor. An impedance conversion unit that performs impedance conversion of the output signal of the sensor, at least one filter that filters only a specific frequency component of the output signal of the impedance conversion unit, and a human body on the seat based on the output signal of the filter. The control board is provided with an information processing means for determining the presence / absence and outputting the determination result, and a conductive box body that incorporates the control board and is electrically connected to the conductive shield material.

In order to achieve the second object of the present invention, the control board has a feed-through capacitor-containing connector for supplying power and for outputting a determination result.

In order to achieve the third object of the present invention, the conductive shield material is arranged on a flexible seat, and the seat is installed under the seat cover cloth.

In order to achieve the fourth object of the present invention, the control board has an IC having an impedance conversion section, a filter and an information processing means built therein.

Further, in order to achieve the fifth object of the present invention, the box body has a fitting portion for fixing a part of both the piezoelectric sensor and the flexible sheet.

[0014]

The present invention operates as follows with the above construction.

The output terminal of the piezoelectric sensor contained in the conductive shield material is fixed to the same control board on which the impedance converter, the filter and the information processing means are arranged, and the control board is electrically connected to the conductive shield material. Since it is built in the conductive box body, there is no noise intrusion from the output line of the piezoelectric sensor, and the presence can be determined without malfunction.

Further, according to the present invention, the control board has a connector containing a feedthrough capacitor for supplying power and outputting a judgment result,
There is no intrusion of noise from the power supply and judgment result output lines, and seating is judged without malfunction.

Further, in the present invention, the conductive shield material is arranged on the flexible seat, and when the piezoelectric sensor is arranged on the seat, the seat may be arranged under the seat cover cloth.

Further, according to the present invention, the control board has an IC in which the impedance converter, the filter and the information processing means are built in, and the number of parts is small, so that the reliability is high.

Further, according to the present invention, the box body has a fitting portion for fixing a part of both the piezoelectric sensor and the flexible sheet, and the fitting strength between the piezoelectric sensor and the flexible sheet and the box body is maintained. Be done.

[0020]

Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 is an external perspective view of this embodiment, and FIG. 2 is A of FIG.
Fig. 3 is a sectional view taken along the line -A ', Fig. 3 is a component configuration diagram of this embodiment, Fig. 4 is a schematic diagram of this embodiment installed on a seat, and Fig. 5 is a control block diagram of this embodiment.

In FIGS. 1 and 2, 1 is a conductive shield material made of, for example, an aluminum tape, 2 is a strip-shaped piezoelectric sensor made of a polymeric piezoelectric material such as polyvinylidene fluoride,
The piezoelectric sensor 2 is included in the conductive shield material 1.
A flexible sheet 7 is made of, for example, a non-woven fabric, and the conductive shield material 1 including the piezoelectric sensor 2 is fixed in a meandering shape with a cloth tape 8. The seating pressure is applied to the seat body 9, and the other portion 10 is a guide portion between the box body 18 and the seat body 9 described later. The seat body 9 is formed so as to conform to the seat shape. For example, when there is a suspending portion for forming the ups and downs of the seat cover, as shown in FIG. Sometimes the part is punched out. In FIG. 3, 11 is an output terminal for deriving the output of the piezoelectric sensor 2 and for deriving the ground of the conductive shield material. Reference numeral 12 denotes an impedance conversion unit 13 that performs impedance conversion of the output signal of the piezoelectric sensor 2, a filter 14, and a microcomputer 1 as information processing means.
It is an IC with built-in 5 (neither shown). The filter 14 filters only a specific frequency component of the output signal of the impedance converter 13 and amplifies the filtered signal. Reference numeral 16 denotes a feedthrough capacitor-containing connector for power supply and determination result output. The output terminal 11, the IC 12, and the feedthrough capacitor-containing connector 16 are provided on the control board 17. 18 is a metal box body for fixing the control board 17;
Reference numeral 9 is an upper lid made of the same material, and reference numeral 20 is a box-side fitting portion on which a tab 21 is formed. A fixing hole 22 through which the claw 21 penetrates is formed at the end of the guide portion 10. Reference numeral 23 is a fitting portion on the upper lid side, and a caulking hole 24 of the claw 21 is formed therein. The conductive shield material 1 connects the output terminal 11 to the control board 17
The control board 17 is configured such that it is electrically connected to the board ground when it is fixed to the box body 18, and the board ground and the box body 18 are connected to each other when the control board 17 is fixed to the box body 18. As shown in FIG. 4, the seat body 9 is disposed between the seat cloth 25 and the cushion material 26 of the seat 1, and the control unit 27 including the control board 17, the box body 18 and the upper lid 19 includes the frame 28 of the seat 1. Fixed to.

The operation of the configuration of the above embodiment will be described with reference to FIG. When the human body is seated, the piezoelectric sensor 2 arranged on the seat is deformed by the body movement of the human body, and a voltage is generated by the piezoelectric effect. Impedance conversion is performed on the generated signal by the impedance converter 13, and then a specific frequency component of the signal is filtered by the filter 14. As the filter 14, specifically, a low-pass filter that passes about 10 Hz or less may be used. The microcomputer 15 AD-converts the output signal from the filter 14,
Calculate the moving average. FIG. 6 shows calculated values for actual seating. From the figure, in the case of coarse body movement such as sitting, limb movement, and sitting, the movement is over the whole body, so the piezoelectric sensor 2 is greatly deformed and the calculated value increases, but if the seated person keeps a resting state. Due to minute body movements of the body propagated by the activity of the heart and the respiratory activity of the human body, the value becomes a relatively low value like the S portion in FIG. Further, when an object is placed on the seat as shown in FIG. 6, a large value is obtained immediately after the object is placed, but since the object does not have the above-mentioned cardiac activity and respiratory activity, it is as shown in part S of FIG. Does not have a value. Based on such a calculated value, the calculated value V in the microcomputer 15 is Va in FIG.
It is determined that the person is seated if the above is continued for the time to or more, and it is determined that the person is absent otherwise. The determination result by the microcomputer is output through the connector 16 as, for example, the output level Lo when present, and Hi when not present.

Here, a case will be described in which the present embodiment is exposed to a strong electric field in which a malfunction occurs in the conventional example. With the above configuration, the output terminal 11 of the piezoelectric sensor 2 included in the conductive shield material 1 is fixed to the same control board 17 on which the IC 12 is arranged, and the control board 17 is electrically conductive with the conductive shield material 1. Since the piezoelectric sensor 2 and the control board 17 are built in the control unit 27 including the conductive box body 18 and the upper lid 19, the piezoelectric sensor 2 and the control board 17 are completely shielded by the shield structure including the conductive shield material 1 and the conductive box body 18 and the upper lid 19. It is configured to be shielded. Therefore, noise does not enter the piezoelectric sensor 2, the box body 18, and the upper lid 19, and malfunctions due to noise do not occur.

Further, since the control board 17 has a connector 16 with a feed-through capacitor for power supply and judgment result output, there is no noise intrusion from the power supply and judgment result output lines, and there is no malfunction and there is no presence. To judge.

Further, the conductive shield material 1 is arranged on the flexible seat 7, and when the piezoelectric sensor 2 is arranged on the seat 1, the seat 7 may be arranged under the seat cover cloth.

Further, the control board 17 is an IC in which the impedance conversion section 13, the filter 14 and the microcomputer 15 are built in.
It has 12, and the number of parts is small and the reliability is high.

Further, the box body 18 and the upper lid 19 have fitting portions 20 and 23 for fixing a part of both the piezoelectric sensor 2 and the flexible sheet 7 and caulking structures 21, 22 and 24. Flexible sheet 7, box 18, and upper lid 1
The fitting strength with 9 is maintained.

With the above operation, the output terminal 11 of the piezoelectric sensor 2 contained in the conductive shield material 1 is fixed to the control board 17, and the control board 17 is electrically conductive with the conductive shield material 1 and has a conductive box body 18. Since it is built in the control unit 27 including the upper lid 19, the piezoelectric sensor 2 and the control board 17 are completely shielded by the shield configuration including the conductive shield material 1, the conductive box body 18, and the upper lid 19. The piezoelectric sensor 2, the box body 18, and the upper lid 1
There is no noise invading 9 and there is an effect that there is no malfunction due to noise as in the past. Further, since no shielded wire is used, the manufacturing cost is reduced accordingly.

Further, since the control board 17 has a connector 16 with a feed-through capacitor for power supply and judgment result output, there is no intrusion of noise from the power supply and judgment result output lines as in the conventional case, and a malfunction occurs. There is an effect that it is possible to judge the presence without.

Further, the conductive shield material 1 is arranged on the flexible seat 7, and when the piezoelectric sensor 2 is arranged on the seat 1, the seat 7 may be arranged under the seat cover cloth. In terms of manufacturing, there is an effect that workability is better than in the past.

Further, the control board 17 is an IC in which the impedance conversion section 13, the filter 14 and the microcomputer 15 are built in.
Since it has 12, there is an effect that the number of parts is small and the reliability is high. Further, although the filter 14 may be configured by an analog circuit, in consideration of the size of the element variation, the failure rate, and the like, the filter 14 may be configured by a digital filter using a DSP or the like, and the reliability is further improved.

Further, since the box body 18 and the upper lid 19 have fitting portions 20 and 23 for fixing a part of both the piezoelectric sensor 2 and the flexible sheet 7 and caulking structures 21, 22 and 24, for example, Piezoelectric sensor 2 and seat 7 as when seated
Even if a pulling force is applied to the, the fitting strength between the piezoelectric sensor 2 and the flexible sheet 7, the box body 18 and the upper lid 19 can be maintained.

In the above embodiment, vibration is not applied from the other side to the seat. However, when the presence detection is performed in a situation where vibration is applied to the seat such as a seat of a vehicle, an object is detected on the seat. Even if a person is placed, it may be judged to be present due to vibration. In this case, the difference in natural frequency between the person and the object may be used to add one more filter having different characteristics. That is, two filters having different characteristics for filtering the natural vibration components of the person and the object are provided, the signal components of the person and the object are separated from the output signal of the piezoelectric sensor 2 by the respective filters, and the magnitude of the two filter outputs is different. By comparing the relationships, it is possible to distinguish the person from the object and determine the presence. A low-pass filter that filters, for example, 10 Hz or less may be used to filter a human natural vibration component, and a high-pass filter that filters 10 Hz or more may be used to filter a natural vibration component of an object.

In the above embodiment, the conductive shield material 1 is used.
Although the strip-shaped piezoelectric sensor 1 included in the above is used, the present invention is not limited to the shape and structure of the piezoelectric sensor 1 as described above, and may be a sheet-shaped piezoelectric sensor that covers the entire seat or a coaxial cable. Piezoelectric sensors of other shapes and structures, such as the piezoelectric sensor of No. 3, may be used.

Although the piezoelectric sensor is used in the present invention, the output as shown in FIG. 6 is generated by generating an output signal corresponding to the deformation amount, such as a capacitance sensor or a pressure sensor using a pressure-sensitive conductive material. A sensor other than the piezoelectric sensor may be used as long as the sensor has characteristics to detect the presence.

[0036]

As described above, according to the presence determination apparatus of the present invention, the following effects can be obtained.

(1) Since the output terminals of the piezoelectric sensor enclosed in the conductive shield material are fixed to the control board, and the control board is built in the conductive box body which is electrically connected to the conductive shield material, The sensor and control board are completely shielded by the shield structure consisting of a conductive shield material and a conductive box body, so there is no noise intrusion into the piezoelectric sensor and box body, and there is no malfunction due to noise as in the past. .

(2) The control board has connectors for feed-through and output of judgment results, which have feed-through capacitors, so that there is no noise intrusion from the conventional power supply and judgment result output lines, and no malfunction occurs. You can judge your presence.

(3) The conductive shield material is arranged on a flexible seat, and when the piezoelectric sensor is arranged on the seat, the seat may be arranged under the seat cover cloth. Workability is better than

(4) Since the control board has an IC having a built-in impedance converter, filter and microcomputer, the number of parts is small and the reliability is high.

(5) Since the box body has the fitting portion for fixing a part of both the piezoelectric sensor and the flexible sheet, even if a tensile force is applied to the piezoelectric sensor or the sheet, for example, when seated. There is an effect that the fitting strength between the piezoelectric sensor and the flexible sheet and the box body is maintained.

[Brief description of drawings]

FIG. 1 is an external perspective view of an occupancy detection device according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along the line A-A ′ of the device.

FIG. 3 is an exploded perspective view showing a component configuration of the same device.

FIG. 4 is a side sectional view when the device is installed in a seat.

FIG. 5 is a control block diagram of the device.

FIG. 6 is a characteristic diagram showing a transition of a calculated value of a moving average by a microcomputer of the device.

FIG. 7 is an external perspective view of a conventional presence detection device.

[Explanation of symbols]

 1 Conductive Shielding Material 2 Piezoelectric Sensor 7 Sheet 8 Cloth Tape 9 Sheet Body 12 IC 13 Impedance Converter 14 Filter 16 Connector 17 Control Board 18 Box 20 Box Side Fitting 23 Top Lid Fitting

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshiaki Watanabe 1006 Kadoma, Kadoma City, Osaka Prefecture, Matsushita Electric Industrial Co., Ltd. (72) Takashi Iwasa 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co. 72) Inventor Gendo Kato 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor Hiroshi Mitsunaga 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. 1006 Kadoma, Kadoma, Fuchu Matsushita Electric Industrial Co., Ltd. (72) Inventor, Junji Sugimoto, 1-4-1, Chuo, Wako, Saitama, Ltd., Honda R & D Co., Ltd. Chuo 1-4-1 Chuo Technical Research Institute Ltd. (72) Inventor Mamoru Morota 1-4-1 Chuo Wako, Saitama Prefecture No. Stock Company Honda Technical Research Institute

Claims (5)

[Claims] 1. A piezoelectric sensor disposed in a seat and enclosed in a conductive shield material, an output terminal of the piezoelectric sensor, an impedance converter for impedance conversion of an output signal of the piezoelectric sensor, and an output of the impedance converter. A control board provided with at least one filter for filtering only a specific frequency component of the signal and information processing means for determining the presence or absence of a human body on the seat based on the output signal of the filter and outputting the determination result. And an occupancy detection device including a conductive box body that incorporates the control board and is electrically connected to the conductive shield material. 2. The occupancy detection device according to claim 1, wherein the control board has a connector with a feedthrough capacitor for supplying power and for outputting a determination result. 3. The seating detection apparatus according to claim 1, wherein the conductive shield material is provided on a flexible seat, and the seat is installed under a seat cover cloth. 4. The control board has an IC having a built-in impedance converter, a filter, and an information processing means.
The presence detection device described. 5. The presence detection apparatus according to claim 3, wherein the box body has a fitting portion for fixing a part of both the piezoelectric sensor and the flexible sheet.