JP2734997B2 - Piezoelectric sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polymer piezoelectric sensor disposed on a seat or a cushion for detecting a human body, and more particularly to a structure for detecting electrical disconnection or short circuit of a sensor electrode and shielding electromagnetic waves of the sensor. It is about.

[0002]

2. Description of the Related Art The inventors of the present invention have devised the following prior art as a prior art relating to detection of abnormality such as electrical disconnection or short circuit of a piezoelectric sensor. That is, as shown in FIGS. 15 and 16, the first resistor 4 is connected to the ends of the electrodes 2 and 3 provided on both surfaces of the piezoelectric material 1, and the first resistor 4 is applied to the applied voltage Vd. The voltage V divided by the second resistor 6 provided in the signal processing means 5 is detected by the abnormality detection means 7 so that the normal value Vo is broken if V = Vd, and if V = O, It was detected that a short circuit had occurred.

[0003]

However, in the prior art, since the piezoelectric material 1 is a high-resistance material, the first resistor 4 is also a high-resistance material so as not to lower the output sensitivity of the sensor. There is a problem that the value is easily affected by temperature and humidity. In addition, it is necessary to suppress variations in output sensitivity due to such an influence, and there is a problem that the yield of products is low and the cost is high.

An object of the present invention is to solve the above problems and to provide a simpler configuration for detecting an abnormality such as a disconnection or a short circuit.

[0005]

According to the present invention, there is provided a sensor body comprising a piezoelectric polymer material, electrodes formed on both surfaces thereof, and a protective layer for protecting the electrodes.
Shielding means disposed on both sides of the sensor main body to shield the sensor main body from electromagnetic waves; and detecting electric capacitance between the electrodes and between the electrodes and the shielding means to detect an electric connection between the electrodes and the shielding means. Abnormality detecting means for detecting an abnormality such as a disconnection or a short circuit.

The present invention also provides a sensor body comprising a polymer piezoelectric material, electrodes formed on both surfaces thereof, and a protective layer for protecting the electrodes, and a sensor body provided on both surfaces of the sensor body for protecting the sensor body from electromagnetic waves. Shielding means for shielding, a conducting part for conducting the shielding means to each other, and abnormality detecting means connected to the shielding means and detecting an electric disconnection abnormality of the shielding means by detecting conduction between the shielding means. Have.

Further, according to the present invention, the shield means is folded back so as to include the sensor main body, and is disposed on the sensor main body, and the folded back portion of the shield means is a conductive part.

According to the present invention, the abnormality detecting means detects an electrical disconnection abnormality of the shield means by detecting conduction between the shield means, and detects an electric capacity of the electrodes by detecting an electric capacity between the electrodes. Detects abnormalities such as disconnection or short circuit.

Further, the present invention provides a sensor body comprising a polymer piezoelectric material and electrodes formed on both surfaces thereof, and a contact portion in which the sensor body is bent and its inner electrodes are brought into close contact with each other.
By detecting the continuity of the outer electrode and the continuity between the inner electrode and the outer electrode, an abnormality such as an electrical disconnection of the outer electrode or a short circuit between the outer electrode and the inner electrode is detected.

Further, according to the present invention, when the sensor body is bent from the center, the output signal can be derived from the exposed inner electrode and outer electrode by bending the sensor body without aligning the ends so that a part of the inner electrode is exposed. There is a configuration.

Further, according to the present invention, the abnormality detecting means detects an electrical disconnection abnormality of the outer electrode by detecting conduction of the outer electrode, and detects an electric capacitance between the outer electrode and the inner electrode. Thus, an abnormality such as an electric disconnection or a short circuit between the outer electrode and the inner electrode is detected.

Further, the present invention provides a sensor body in which a signal deriving electrode, a piezoelectric material, and a reference electrode are coaxially arranged and the whole is formed in a cable shape, and the electrode is detected by detecting conduction of the electrode. Abnormality detecting means for detecting an abnormality such as an electric disconnection or a short circuit.

[0013]

According to the present invention, an abnormality such as an electric disconnection or a short circuit between the electrodes and the shield means is detected by detecting the electric capacitance between the electrodes and between the electrodes and the shield means.

Further, according to the present invention, an electrical disconnection abnormality of the shield means is detected by detecting conduction between the shield means.

Further, in the present invention, the shield means is folded back so as to enclose the sensor main body, and is disposed on the sensor main body, and the folded back portion of the shield means is a conductive part.

Further, according to the present invention, an electric disconnection abnormality of the shield means is detected by detecting conduction between the shield means, and an electric disconnection or short circuit of the electrode is detected by detecting an electric capacity between the electrodes. To detect abnormalities.

Further, according to the present invention, an abnormality such as an electric disconnection of the outer electrode or a short circuit between the outer electrode and the inner electrode is detected by detecting conduction of the outer electrode and conduction between the inner electrode and the outer electrode. To detect.

Further, according to the present invention, when the sensor body is bent from the center, the output signal can be derived from the exposed inner and outer electrodes by bending the sensor body without aligning the ends so that a part of the inner electrode is exposed. .

Further, according to the present invention, the disconnection of the outer electrode is detected by detecting the conduction of the outer electrode, and the electric capacity between the outer electrode and the inner electrode is detected by detecting the electric capacitance between the outer electrode and the inner electrode. And an abnormality such as electrical disconnection or short circuit of the inner electrode is detected.

Further, the present invention relates to a sensor main body in which a signal deriving electrode, a piezoelectric material, and a reference electrode are coaxially arranged and the whole of which is formed in a cable shape. Detects abnormalities such as electrical disconnection or short circuit.

[0021]

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.
It is -A 'sectional drawing. In FIG. 1, reference numeral 9 denotes a polymer piezoelectric material such as polyvinylidene fluoride (PVDF), which is formed into a thin film. Reference numerals 10 and 11 denote flexible electrodes, for example, by depositing a good conductive metal such as aluminum, copper, or nickel on the surface of the piezoelectric material 9 or forming a film of the metal and using a conductive adhesive or the like. 9 and molded. Reference numerals 12 and 13 denote protective layers for the electrodes 10 and 11, which are formed by laminating, for example, a polyester film or the like on the electrodes 10 and 11. 14 and 15 are shielding means provided on both sides of the sensor main body to shield the sensor main body from electromagnetic waves, and 16 and 17 are insulating layers of the shield layers 14 and 15. In FIG. 1A, reference numeral 18 denotes a terminal for extracting a sensor signal, and the sensor signal is transmitted to the control unit 20 via a shield wire 19. Although not shown here, the control unit 20 has built-in abnormality detecting means 23 for detecting abnormalities such as electrical disconnection or short circuit of the electrodes 10 and 11 and the shielding means 14 and 15. As another configuration of the present embodiment, the terminal unit 21 may be directly connected to the control board 22 provided with the abnormality detecting means 23 as shown in FIG. FIG. 3 is a block diagram of the abnormality detecting means 23. 24 is a sensor body, 25 is a third resistor, 26 is a transistor, 2
7, a differential amplifier; and 28, a microcomputer. The fourth resistor 30, the FET 31, and the filter 32 are one configuration example for using a signal from the sensor body, for example, for detecting the presence of a human body.

With the above configuration, this embodiment operates as follows. As shown in FIG. 4, when I1 is Hi by the microcomputer, the transistor 26 is turned on, and charging and discharging are repeated in the sensor main body 24 in synchronization with the pulse by the pulse output from I2.

In this case, the charge / discharge characteristics are determined by the third resistor 25.
And the electric capacitance of the sensor main body 24. At the time of charging and discharging, the potential difference dV between both ends of the third resistor 25
Therefore, the fluctuation signal is appropriately amplified by the differential amplifier 27 and taken in by the AD port O1 of the microcomputer. If the electrodes of the sensor body 24 are disconnected, the sensor body 2
Since the electric capacity of No. 4 changes, dV also changes. FIG. 5 shows the relationship between the disconnection length L and the signal V1 at O1. As L is shorter, V1 becomes smaller. The sensor body 2
When a short circuit occurs between the electrodes in V4, V1 becomes zero.
On the other hand, when I1 is Lo, the transistor 26 is turned off and the third resistor 25 side is opened, so that the original output signal of the sensor body 24 due to the piezoelectric effect is
AD port O of the microcomputer 28 through the filter 31 and the filter 32
2 The signal captured in O2 is used, for example, as a determination signal for detecting the presence of a human body. As described above, the intermittent but abnormal state of the sensor body is detected by switching I1.

According to the above operation, in this embodiment, a circuit for abnormality detection is added to some extent to detect the electric capacitance between the electrodes and between the electrode and the shield means to detect the capacitance of the electrodes and the shield means. Since an abnormality such as an electrical disconnection or a short circuit can be detected, there is an effect that the abnormality can be detected more easily and at lower cost than in the past.

A second embodiment of the piezoelectric sensor according to the present invention will be described with reference to the accompanying drawings. FIG. 6 is an external perspective view of this embodiment, and FIGS. 7A and 7B are AA ′ sectional view and BB ′ sectional view in FIG. 6, respectively. This embodiment differs from the above-mentioned embodiment in FIGS.
4 and 15 are not conducting with each other except for the conducting portion 33;
The abnormality detection means 23 is configured to detect an electrical disconnection abnormality of the shield means 14 and 15 by detecting conduction in a path of the shield means 14, the conduction part 33 and the shield means 15. The conducting portion 33 electrically connects the shielding means 14 and 15 with eyelets, but as other constitutions, for example, as shown in FIG. 8, (a) a constitution for conducting by a caulking 34, (b) a winding part 35 of the shielding means
And (c) a configuration in which the sensor body is shielded by being folded back at the end 36 so as to include the sensor body by the shield means 14 or 15.

The operation of the above configuration will be described below. As shown in FIG. 9, the fifth resistor 37 is connected to the shield means 14, and the voltage V2 at P1 is detected at the AD port I3 of the microcomputer. At this time, if there is no disconnection by the shield means, V
2 is zero, and if there is a disconnection, V2 becomes the power supply voltage Vc.

In the case where the electrode is disconnected in this embodiment, it is considered that the shielding means also causes the disconnection at the same time. Therefore, in this embodiment, the disconnection detection of the electrode is indirectly performed by the disconnection detection of the shield means as described above. In addition, the first method for detecting an abnormality by detecting an electric capacity.
In the embodiment, as shown in FIG. 5, as the disconnection length increases, the change in the potential difference decreases, so that it is difficult to detect a disconnection near the tip of the sensor. On the other hand, in the present embodiment, detection can be performed regardless of the disconnection as described above. Therefore, there is an effect that the reliability of abnormality detection is improved and the cost is lower than in the first embodiment.

As shown in FIG. 9, if a configuration for detecting the electric capacitance between the electrodes is added, abnormalities such as electrical disconnection or short circuit of the electrodes can be directly detected as in the first embodiment, and the cost is reduced. Thus, the reliability can be further improved.

A third embodiment of the piezoelectric sensor according to the present invention will be described with reference to the accompanying drawings. 10 (a), (b),
(C) shows a manufacturing procedure and an external perspective view of the piezoelectric sensor of the present embodiment. This embodiment is different from the first and second embodiments in that a sensor main body 24 composed of a piezoelectric polymer material 9 and electrodes 10 and 11 formed on both surfaces thereof is arranged as shown in FIG. Bending from position BB ', FIG.
As shown in FIG. 2 (b), a contact portion 38 is formed in which the inner electrodes 10 are brought into close contact with each other, and the conduction of the outer electrode 11 and the conduction between the inner electrode 10 and the outer electrode 11 are detected. An abnormality detecting means 23 for detecting an abnormality such as a disconnection or a short circuit between the outer electrode 11 and the inner electrode 10. Here, as shown in FIG. 10B, when the sensor main body 24 is bent, the inner electrode 10 is bent without aligning its ends so that a part of the inner electrode 10 is exposed.
An output signal can be derived from the terminal 39, 40, and 41 from the external electrode 11 and the outer electrode 11. Also, as shown in FIG. 10C, the insulating layers 16 and 17 are laminated on the outer electrode 11, and the terminals 39, 40 and 41 are molded by the molding part. Further, as shown in FIG.
One end is connected to ground, and the other end is connected to a power supply Vc via a fifth resistor 37.

With the above configuration, this embodiment operates as follows. As shown in FIG. 11, one end of the outer electrode 11 is connected to the ground and the other end is connected to the power supply Vc via the fifth resistor 37. Therefore, when there is no disconnection in the outer electrode 11, the voltage V3 at the point P becomes When it becomes zero and a disconnection occurs, V3 becomes the power supply voltage Vc. Such a change in V3 is captured by the AD port I3 of the microcomputer to detect whether or not a disconnection has occurred.

According to the above operation, in the second embodiment, the disconnection of the shield means is detected and the disconnection of the electrode is indirectly determined. However, according to the present embodiment, the electrode is directly disconnected without using the shield means. Since the disconnection can be detected, there is an effect that the reliability is further improved and the disconnection can be detected at low cost.

The disconnection of the inner electrode 10 and the outer electrode 1
When detecting a short circuit between the inner electrode 10 and the inner electrode 10, a configuration for detecting the electric capacitance between the inner electrode 10 and the outer electrode 11 as shown in FIG. 11 may be added.

A fourth embodiment of the piezoelectric sensor according to the present invention will be described below. FIG. 12 is an external perspective view of the present embodiment, and FIG. 13 is a sectional view taken along line AA ′ of FIG. This embodiment is different from the above-described embodiment in that the sensor main body 24 includes a signal deriving electrode 43, a piezoelectric material 9, a reference electrode 44, and an insulating layer 45 of the reference electrode 44, as shown in FIGS. It is arranged coaxially and formed as a whole in the shape of a cable, and is provided with abnormality detecting means 23 for detecting abnormality such as electrical disconnection or short circuit of the electrode 44 by detecting conduction of the reference electrode 44. .

With the above configuration, the present embodiment operates as follows. One end of the electrode 44 is connected to the ground as shown in FIG.
Since the other end is connected to the power supply Vc via the fifth resistor 37, the voltage V3 at the point P becomes zero when there is no disconnection in the outer electrode 11, and when the disconnection occurs, V3 becomes the power supply voltage Vc.
Becomes Such a change in V3 is captured by the AD port I3 of the microcomputer to detect whether or not a disconnection has occurred.

According to the above operation, in the second embodiment, the disconnection of the shield means is detected and the disconnection of the electrode is determined indirectly. However, according to the present embodiment, the shield means is used similarly to the third embodiment. Instead, the disconnection of the electrode can be directly detected, so that there is an effect that the reliability can be further improved and the disconnection can be detected at low cost.

When the disconnection of the electrode 43 and the short circuit between the electrode 44 and the electrode 43 are detected, as shown in FIG.
What is necessary is just to add the structure which detects the electric capacitance between 3 and the electrode 44.

[0037]

As is clear from the above description, the following effects can be obtained according to the piezoelectric sensor of the present invention.

That is, according to the present invention, it is possible to detect an electric capacitance between the electrodes and between the electrode and the shield means to detect an abnormality such as an electric disconnection or a short circuit between the electrodes and the shield means. There is an effect that abnormality detection can be performed more easily and at lower cost than in the past.

In the method of detecting the disconnection by detecting the electric capacity, it may be difficult to detect the disconnection depending on the position of the disconnection. However, in the present invention, the disconnection of the electrode is detected indirectly by the detection of the disconnection of the shield means. Even if the disconnection occurs, the detection is possible, and the reliability of the disconnection detection is improved, and the cost is reduced.

Further, according to the present invention, since the shield means is folded back so as to enclose the sensor main body and disposed on the sensor main body, there is no need for conducting means such as eyelets and the like, and there is an effect that the cost is reduced.

In the present invention, in addition to indirectly detecting the disconnection of the electrode by detecting the disconnection of the shield means, the capacitance between the electrodes is detected to directly detect an abnormality such as an electrical disconnection or a short circuit of the electrode. Therefore, there is an effect that the reliability can be further improved.

Further, according to the present invention, since the disconnection of the electrode can be directly detected without using the shielding means, there is an effect that the reliability is further improved and the disconnection can be detected at low cost.

Further, in the present invention, when the sensor body is bent from the center, the ends are not aligned so that a part of the inner electrode is exposed, so that an output signal is derived from the exposed inner electrode and the outer electrode. There is an effect that it is easy.

In the present invention, in addition to directly detecting the disconnection of the outer electrode without using the shielding means, the capacitance between the inner electrode and the outer electrode is detected. There is an effect that a short circuit between the outer electrode and the inner electrode can be detected.

Further, according to the present invention, the disconnection of the electrode can be directly detected without using the shielding means.
There is an effect that the reliability is improved and the disconnection can be detected at low cost.

[Brief description of the drawings]

FIG. 1A is an external perspective view of a first embodiment of the present invention in which a control unit of a piezoelectric sensor is separated, and FIG. 1B is an external perspective view of a case where a control base of the piezoelectric sensor is integrally formed.

FIG. 2 is a sectional view of the piezoelectric sensor.

FIG. 3 is a block diagram of abnormality detection means of the piezoelectric sensor.

FIG. 4 is a diagram showing input / output signals of a microcomputer of the piezoelectric sensor.

FIG. 5 is a characteristic diagram showing a relationship between a disconnection length and a potential difference.

FIG. 6 is an external perspective view of a piezoelectric sensor according to a second embodiment of the present invention.

7A is a sectional view of the piezoelectric sensor taken along line A-A 'in FIG. 6; FIG. 7B is a sectional view of the piezoelectric sensor taken along line B-B' in FIG. 6;

8A is a configuration diagram of a conductive portion in a crimped form in the piezoelectric sensor. FIG. 8B is a configuration diagram of a conductive portion in a rolled-up form in the piezoelectric sensor. Diagram

FIG. 9 is a block diagram of abnormality detecting means in the piezoelectric sensor.

10A is an external perspective view of a piezoelectric sensor according to a third embodiment of the present invention before the sensor main body is bent. FIG. 10B is an external perspective view of the piezoelectric sensor main body after the sensor main body is bent. Appearance perspective view after molding

FIG. 11 is a block diagram of abnormality detecting means in the piezoelectric sensor.

FIG. 12 is an external perspective view of a piezoelectric sensor according to a fourth embodiment of the present invention.

FIG. 13 is a sectional view of the piezoelectric sensor.

FIG. 14 is a block diagram of abnormality detecting means in the piezoelectric sensor.

FIG. 15 is an external perspective view of a conventional piezoelectric sensor.

FIG. 16 is a circuit diagram of the piezoelectric sensor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Piezoelectric material 2, 3 electrode 4 1st resistor 4 5 Signal processing means 6 2nd resistor 6 7 Abnormality detection means 9 Polymer piezoelectric material 10, 11 Electrode 12, 13 Protective layer 14, 15 Shield layer 16, Reference Signs List 17 Insulating layer 18 Terminal part 19 Shield wire 20 Control unit 21 Terminal part 22 Control board 23 Abnormality detection means 24 Sensor main body 25 Third resistor 26 Transistor 27 Differential amplifier 28 Microcomputer 30 Fourth resistor 31 FET 32 Filter

Claims (8)

(57) [Claims] A sensor body comprising a polymer piezoelectric material, electrodes formed on both surfaces thereof, and a protective layer for protecting the electrodes;
Shielding means disposed on both sides of the sensor main body to shield the sensor main body from electromagnetic waves; and detecting electric capacitance between the electrodes and between the electrodes and the shielding means to detect an electric connection between the electrodes and the shielding means. A piezoelectric sensor including an abnormality detection unit that detects an abnormality such as a disconnection or a short circuit. 2. A sensor body comprising a polymer piezoelectric material, electrodes formed on both surfaces thereof, and a protective layer for protecting the electrodes,
A shield unit disposed on both sides of the sensor main body for shielding the sensor main body from electromagnetic waves, a conduction unit for electrically connecting the shield units to each other, and detecting the conduction between the shield units connected to the shield unit to detect the conduction between the shield units. A piezoelectric sensor comprising: an abnormality detection unit configured to detect an electrical disconnection abnormality of the shield unit. 3. The piezoelectric sensor according to claim 2, wherein the shield means is folded back so as to include the sensor main body, and is disposed on the sensor main body, and the folded portion of the shield means is a conductive part. 4. An abnormality detecting means for detecting an electric disconnection abnormality of the shield means by detecting conduction between the shield means and an electric disconnection or short circuit of the electrodes by detecting an electric capacity between the electrodes. The piezoelectric sensor according to claim 2 or 3, which detects an abnormality such as the above. 5. A sensor main body comprising a polymer piezoelectric material and electrodes formed on both surfaces thereof, a contact portion in which the sensor main body is bent to bring the inner electrodes into close contact with each other; A piezoelectric sensor comprising: abnormality detection means for detecting abnormality such as electrical disconnection of the outer electrode or a short circuit between the outer electrode and the inner electrode by detecting conduction with the outer electrode. 6. When bending the sensor body from the center,
6. The piezoelectric sensor according to claim 5, wherein an output signal is derived from the exposed inner electrode and the outer electrode by bending the inner electrode so that a part of the inner electrode is exposed so that the ends are not aligned. 7. An abnormality detecting means for detecting an electrical disconnection abnormality of the outer electrode by detecting conduction of the outer electrode, and detecting an electric capacitance between the outer electrode and the inner electrode by detecting a capacitance between the outer electrode and the inner electrode. 7. An abnormality such as electrical disconnection or short circuit between an electrode and the inner electrode is detected.
The piezoelectric sensor according to any one of the preceding claims. 8. A sensor body in which a signal deriving electrode, a piezoelectric material and a reference electrode are coaxially arranged and the whole is formed in a cable shape, and an electrical connection of the electrode is detected by detecting conduction of the electrode. A piezoelectric sensor including an abnormality detection unit that detects an abnormality such as a disconnection or a short circuit.