JP2733441B2 - Presence detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art The inventors of the present invention have a problem that a conventional presence detection device having a structure in which a microswitch is disposed in a seat has a problem that a switch is turned on by a load even when an object is placed on the seat. In order to solve such a problem, a presence detection device having a configuration as shown in FIG. 7 is devised. That is, the piezoelectric sensor 2 (not shown) included in the conductive shield material 1 is disposed under the surface cloth of the seat 3 so as not to impair the seating feeling, and the output from the piezoelectric sensor 2 is led out by the shield wire 4. Judgment means (not shown) incorporated in the control unit 5 extracts the flutter caused by the heartbeat or respiration of the human body from the output signal of the piezoelectric sensor 2 and, if the flutter component is present in the signal, is present. 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 processes a small signal due to the above-mentioned small body movement, so that the influence of noise is reduced. There is a problem in that when the distance between the piezoelectric sensor 2 and the control unit 5 is necessary due to installation restrictions, erroneous determination due to noise intrusion from the shield wire 4 occurs.

[0004] A first object of the present invention is to eliminate a malfunction caused by noise intrusion from the shield wire 4 as described above.

In addition, 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 a power supply line or an output line.

Further, when the piezoelectric sensor 2 is disposed on the seat 3, it is difficult to assemble, for example, the tape must be fixed by meandering the piezoelectric sensor 2 under the outer cloth in order to increase the detection area. A third object of the present invention is to provide a configuration in which the piezoelectric sensor 2 can be easily arranged on a seat.

A fourth object of the present invention is to improve the reliability by reducing the number of parts.

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

[0009]

SUMMARY OF THE INVENTION In order to achieve the first object, the present invention provides a piezoelectric sensor provided on a seat and contained in a conductive shield material, an output terminal of the piezoelectric sensor, and a piezoelectric sensor. An impedance conversion unit that performs impedance conversion of an 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 a seat based on the output signal of the filter. It comprises a control board provided with an information processing means for judging the presence or absence and outputting a judgment result, and a conductive box body containing the control board and electrically connected to the conductive shield material.

According to the present invention, in order to achieve the second object, the control board has a connector with a feedthrough capacitor for supplying power and outputting a determination result.

According to the present invention, in order to achieve the third object, the conductive shielding material is disposed on a flexible sheet, and the sheet is disposed under a seat cloth.

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

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

[0014]

The present invention operates as follows by the above configuration.

The output terminal of the piezoelectric sensor included in the conductive shield material is fixed to the same control board on which the impedance conversion unit, the filter and the information processing means are provided, and the control board is electrically connected to the conductive shield material. Since it is built in the conductive box, no noise enters from the output line of the piezoelectric sensor, and the presence of the seat is determined without malfunction.

Further, according to the present invention, the control board has a connector with a feedthrough capacitor for supplying power and outputting a determination result,
There is no noise intrusion from the power supply and determination result output lines, and the presence is determined without malfunction.

According to the present invention, the conductive shield material is provided on a flexible sheet. When the piezoelectric sensor is provided on a seat, the seat may be provided under a seat cloth.

Further, according to the present invention, the control board has an IC in which an impedance conversion section, a filter and information processing means are incorporated, and the number of components is small, so that the reliability is high.

Further, in the present invention, the box has a fitting portion for fixing both the piezoelectric sensor and the flexible sheet, and the fitting strength between the piezoelectric sensor and the flexible sheet and the box is maintained. It is.

[0020]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a perspective view showing the appearance of the present embodiment, and FIG.
FIG. 3 is a cross-sectional view taken along the line A-A, FIG. 3 is a component configuration diagram of the present embodiment, FIG. 4 is a schematic diagram in which the present embodiment is installed in a seat, and FIG. 5 is a control block diagram of the present embodiment.

1 and 2, reference numeral 1 denotes a conductive shield material made of, for example, aluminum tape, and 2 denotes a belt-shaped piezoelectric sensor made of a high-molecular piezoelectric material such as polyvinylidene fluoride.
The piezoelectric sensor 2 is included in the conductive shield material 1.
Reference numeral 7 denotes a flexible sheet made of, for example, a non-woven fabric, and the conductive shield material 1 in which the piezoelectric sensor 2 is included is fixed in a meandering manner with a cloth tape 8. The seating pressure is applied to the portion of the seat body 9 while the rest 10 is a guide portion between the box 18 and the seat body 9 described later. The seat body 9 is formed so as to conform to the shape of the seat. For example, when there is a suspended portion for forming the undulation of the surface cloth of the seat, as shown in FIG. Sometimes a part is punched. In FIG. 3, reference numeral 11 denotes 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 for performing impedance conversion of an output signal of the piezoelectric sensor 2, a filter 14, and the microcomputer 1 as information processing means.
5 (both not 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 connector with a feedthrough capacitor for supplying power and outputting a determination result. The output terminal 11, the IC 12, and the connector 16 with a feedthrough capacitor are arranged on a control board 17. Reference numeral 18 denotes a metal box for fixing the control board 17,
Reference numeral 9 denotes an upper cover made of the same material, and reference numeral 20 denotes a box-side fitting portion on which a claw 21 is formed. A fixing hole 22 through which the claw 21 penetrates is formed at an end of the guide portion 10. Reference numeral 23 denotes an upper lid side fitting portion, in which a crimping hole 24 for the claw 21 is formed. The conductive shield material 1 connects the output terminal 11 to the control board 17.
When the control board 17 is fixed to the box 18, the board ground and the box 18 are electrically connected to each other. As shown in FIG. 4, the seat body 9 is disposed between the surface cloth 25 of the seat 1 and the cushion member 26, and the control unit 27 including the control board 17, the box body 18, and the upper lid 19 is mounted on the frame 28 of the seat 1. Fixed to

The operation of the above embodiment will be described with reference to FIG. When the human body is seated, the piezoelectric sensor 2 disposed 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. Specifically, a low-pass filter that passes about 10 Hz or less may be used as the filter 14. In the microcomputer 15, the output signal from the filter 14 is AD-converted,
Calculate the moving average. FIG. 6 shows the calculated values at the time of actual sitting. As shown in the figure, in the case of a coarse body motion such as sitting, limb movement, or uncoupling, the operation is over the whole body, so the piezoelectric sensor 2 undergoes a large deformation and the calculated value becomes large. 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 level as shown in S in FIG. In addition, when an object is placed on the seat as shown in FIG. 6, a large value appears immediately after the object is placed, but since the object does not have the above-mentioned heart activity and respiratory activity, as shown in S part of FIG. Values are not Based on such calculated values, the microcomputer 15 calculates the calculated value V as Va in FIG.
If this is the case and this continues for time to or more, it is determined that the person is seated, otherwise it is determined that the person is absent. The determination result by the microcomputer is output through the connector 16 as an output level Lo when the user is present and Hi when the user is not present.

Here, a description will be given of a case where the present embodiment is exposed to a strong electric field which causes a malfunction in the conventional example. According to 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 provided, and the control board 17 is electrically conductive with the conductive shield material 1. The piezoelectric sensor 2 and the control board 17 are completely built in the control unit 27 including the conductive box 18 and the upper cover 19 by the conductive shield material 1 and the shield structure including the conductive box 18 and the upper cover 19. It is configured to be shielded. Therefore, noise does not enter the piezoelectric sensor 2, the box 18 and the upper lid 19, and there is no malfunction due to noise.

Further, the control board 17 has a connector 16 with a feedthrough capacitor for supplying power and outputting a determination result, so that noise does not enter from the power supply and determination result output lines, and the presence of a malfunction does not occur. Is determined.

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

The control board 17 is an IC in which the impedance converter 13, the filter 14, and the microcomputer 15 are built.
12 and the number of parts is small and the reliability is high.

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

By 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 further comprises a conductive box 18 electrically connected to the conductive shield material 1. And the piezoelectric sensor 2 and the control board 17 are completely shielded by the shield structure including the conductive shield material 1, the conductive box 18 and the upper cover 19. The piezoelectric sensor 2 and the box 18 and the top lid 1
There is an effect that there is no noise intrusion into the No. 9 and no malfunction due to noise as in the related art. Further, since no shield wire is used, there is an effect that the manufacturing cost is correspondingly reduced.

Further, the control board 17 has a connector 16 with a feed-through capacitor for supplying power and outputting the judgment result, so that noise does not intrude from the power supply and judgment result output lines as in the prior art, and a malfunction occurs. There is an effect that the presence can be determined without any.

Further, the conductive shield material 1 is provided on the flexible sheet 7, and when the piezoelectric sensor 2 is provided on the seat 1, the seat 7 may be provided under the seat cloth. In production, there is an effect that workability is better than before.

The control board 17 is an IC in which the impedance converter 13, the filter 14, and the microcomputer 15 are built.
Since there are 12, there is an effect that the number of parts is small and the reliability is high. Further, the filter 14 may be constituted by an analog circuit, but may be constituted by a digital filter using, for example, a DSP or the like in consideration of the size of the variation of elements, the failure rate, and the like, and the reliability is further improved.

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

In the above embodiment, no vibration is applied to the seat. However, when the presence of the vehicle is detected in a situation where vibration is applied to the seat, such as a vehicle seat, an object is not applied to the seat. May be determined to be present because of vibration. In this case, one more filter having different characteristics may be added by utilizing the difference in the natural frequency between a person and an object. That is, two filters having different characteristics for filtering the natural vibration components of the person and the object are provided, and the signal components of the person and the object are separated from the output signal of the piezoelectric sensor 2 by the respective filters. By comparing the relationships, it is possible to distinguish between a person and an object and determine presence. To filter a natural vibration component of a person, for example, a low-pass filter that filters 10 Hz or less may be used, and to filter a natural vibration component of an object, a high-pass filter that filters 10 Hz or more may be used.

In the above embodiment, the conductive shielding material 1
In the present invention, the shape and structure of the piezoelectric sensor 1 are not limited to the above-described configuration, and a sheet-like piezoelectric sensor that covers the entire seat, a coaxial cable-like piezoelectric sensor, or the like is used in the present invention. A piezoelectric sensor having another shape or structure, such as the above-described piezoelectric sensor, may be used.

Although a piezoelectric sensor is used in the present invention, an output signal corresponding to the amount of deformation is generated by, for example, an electrostatic capacity sensor or a pressure sensor using a pressure-sensitive conductive material to generate an output signal as shown in FIG. A sensor other than the piezoelectric sensor may be used as long as the sensor has characteristics, and the presence may be detected.

[0036]

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

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

(2) The control board has a connector with a feedthrough capacitor for power supply and output of the judgment result, and there is no noise intrusion from the line for power supply and output of the judgment result as in the prior art, and there is no malfunction. Can be determined to be present.

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

(4) Since the control board has an IC in which an impedance conversion section, a filter and a microcomputer are built, the number of parts is small and the reliability is high.

(5) Since the box has a mating 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 sitting down. There is an effect that the fitting strength between the piezoelectric sensor and the flexible sheet and the box is maintained.

[Brief description of the drawings]

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

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

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

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

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

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

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Conductive shield material 2 Piezoelectric sensor 7 Sheet 8 Cloth tape 9 Sheet main body 12 IC 13 Impedance conversion part 14 Filter 16 Connector 17 Control board 18 Box body 20 Box side fitting part 23 Top lid side fitting part

 ──────────────────────────────────────────────────の Continuing on the front page (72) Yoshiaki Watanabe, 1006 Kadoma, Kazuma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (72) Inventor Gento Kato 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor Hiroshi Mitsunaga 1006 Okadoma Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. Akira Shiratake 1006 Kazuma Kadoma, Kazuma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. 1-4-1 Chuo, Wako-shi, Saitama Prefecture Inside Honda R & D Co., Ltd. (72) Inventor Maki Morita 1-4-1 Chuo, Wako-shi, Saitama Prefecture No. In Honda R & D Co., Ltd. (56) References JP-A-64-54225 (JP, A) JP-A-55-33092 (JP, A)

Claims (5)

(57) [Claims] 1. A piezoelectric sensor provided in a seat and contained in a conductive shield material, an output terminal of the piezoelectric sensor, an impedance converter for performing 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 a seat based on an output signal of the filter and outputting a determination result And a conductive box body containing the control board and electrically connected to the conductive shield material. 2. The presence detection device according to claim 1, wherein the control board has a connector with a feedthrough capacitor for supplying power and outputting a determination result. 3. The presence detection device according to claim 1, wherein the conductive shield material is disposed on a flexible seat, and the seat is installed under a seat cloth. 4. The control board according to claim 1, wherein said control board has an IC having a built-in impedance converter, a filter, and information processing means.
Presence detection device as described. 5. The presence detection device 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.