JPH06317676A - Human body detecting device - Google Patents

Abstract

PURPOSE:To provide a human body detecting device capable of discriminating a person from an object with a small amplification factor. CONSTITUTION:A human body detecting device is provided with a piezoelectric element 1 disposed on the face, in contact with a human body, of a seat 6; a filter 2 for filtering a certain specific frequency component of the output signal of the piezoelectric element 1; an amplifying means 3 for amplifying the output signal of the filter 2; a maximum displacement quantity detecting means 10 for detecting and outputting the fixed time maximum displacement quantity of the output signal of the amplifying means 3; and a judging means 5 for judging the presence of a person on the seat 6 on the basis of the output signal of the maximum displacement quantity detecting means 10. This constitution results in providing a presence detecting device capable of judging the presence of a person with a small amplification factor by a simple circuit while being influenced little by noise.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a human body detecting device for detecting the presence or absence of a person in a seat or a bed, and more specifically, to grasp the number of seated persons in a theater, a car, etc. The present invention relates to a human body detection device for performing floor management and performing air conditioning control and sound field control in these rooms.

[0002]

2. Description of the Related Art A conventional human body detecting device has a structure as shown in FIG. 6, for example. Here, the case where it is installed on the seat is shown. A piezoelectric element 14 disposed on the seat surface of the seat 19 for detecting body movement of a person, and a filter 15 for filtering only a certain frequency component of the output from the piezoelectric element 14.
An amplifying means 16 for amplifying the output signal from the filter 15, a smoothing means 17 for smoothing the output signal from the amplifying means 16, and the presence or absence of a person on the seat based on the output signal from the smoothing means 17. And the determination means 18 for determination.

When a human body is seated on the seat 19, the piezoelectric element 14 arranged on the seat 19 is deformed by the movement of the human body, and a voltage is generated by the piezoelectric effect. A specific frequency component of the generated voltage signal is filtered by the filter 15, amplified by the amplification means 16, and smoothed by the smoothing means 17. FIG. 7 shows an output signal waveform of the smoothing means 17 when seated. As shown in FIG. 7, in the case of coarse body movement such as sitting, limb movement, and sitting, the movement is over the whole body, so the piezoelectric element 14 undergoes a large deformation and a large signal waveform is output from the smoothing means 17, but a person When the person is in a resting state, a relatively low level output such as the portion S in FIG. 7 is produced due to minute body movements of the body propagated by the activity of the human heart and the respiratory activity. Further, when an object is placed on the seat as shown in FIG. 7, a large output is obtained immediately after the object is placed, but since the object does not have the heart activity and the respiratory activity as described above, as shown in part S of FIG. There is no output. The difference between the person and the object is used to distinguish the person and the object.

[0004]

However, in the human body detecting device of the above technique, the presence or absence of a person is determined by detecting an output signal of a relatively low level when the person on the device is in a resting state. In this case, since this signal is a very weak signal, it is necessary to set the amplification factor to a very large value in the amplification means, which complicates the circuit and is susceptible to noise. It was

A first object of the present invention is to provide a human body detecting apparatus capable of detecting the body movement of a person in a resting state with a small amplification factor.

A second object of the present invention is to provide a human body detecting device which is less likely to malfunction due to noise or the like.

[0007]

In order to achieve the first object, the present invention provides a piezoelectric element arranged on a contact surface of a device with a human body, and a specific frequency of an output signal of the piezoelectric element. A filter for filtering the components, an amplification means for amplifying the output signal of the filter, a maximum displacement amount detection means for detecting the maximum displacement amount of the output signal of the amplification means during a certain period of time, and the maximum displacement amount detection And means for determining the presence or absence of a person at the device based on the output of the means.

In order to achieve the above second object, the present invention filters a piezoelectric element arranged on a contact surface of a device with a human body and a specific frequency component of an output signal of the piezoelectric element. Filter, amplification means for amplifying the output signal of the filter, maximum displacement amount detection means for detecting the maximum displacement amount of the output signal of the amplification means for a certain period of time, and output signal of the maximum displacement amount detection means And a determining means for determining the presence or absence of a person in the device based on the output of the smoothing means.

[0009]

The present invention operates as follows with the above construction. When the human body comes into contact with the contact surface of the device with the human body and pressure is applied by the human body, the piezoelectric element arranged on the contact surface with the human body is deformed by the body motion of the human body, and a voltage is generated by the piezoelectric effect. A certain frequency component of the generated voltage signal is filtered by the filter and amplified by the amplifying means, and the maximum displacement amount detecting means detects the maximum displacement amount within a certain period of time. Then, based on the output of the maximum displacement amount detecting means, the presence or absence of a person in the device is determined.

Further, according to the present invention, when the human body comes into contact with the contact surface of the device with the human body and pressure is applied by the human body, the piezoelectric element disposed on the contact surface with the human body is deformed by the body movement of the human body. In response, a voltage is generated by the piezoelectric effect. A certain frequency component of the generated voltage signal is filtered by the filter and amplified by the amplifying means, and the maximum displacement amount detecting means detects the maximum displacement amount within a certain period of time. The output signal of the maximum displacement amount detecting means is smoothed by the smoothing means, and based on the output of this smoothing means, the presence or absence of a person in the equipment is determined.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a block diagram of this embodiment. Here, the case where the device is installed in a seat is shown. In FIG. 1, 1 is a piezoelectric element, 2 is a filter, 3 is amplification means,
Reference numeral 4 is a maximum displacement amount detecting means, and 5 is a determining means. The piezoelectric element 1 is formed by forming a polymer piezoelectric material such as polyvinylidene fluoride (PVDF) into a thin film and attaching a flexible electrode film on both sides to form a tape. Here, it is arranged under the seat cloth of the seat 6. is doing.

The operation of the configuration of the above embodiment will be described below. When the human body is seated on the seat, the piezoelectric element 1 arranged on the seat is deformed by the movement of the human body, and a voltage is generated by the piezoelectric effect. A specific frequency component of the output signal of the piezoelectric element 1 is filtered by the filter 2 and amplified by the amplification means 3. FIG. 2A shows an output signal waveform of the amplifying means 3 when the seated person keeps a resting state. When a seated person keeps a resting state, minute movements of the body propagated by the heart's heart activity and respiratory activity of the human body, as shown in FIG.
A signal in which a high frequency component and a low frequency component are mixed as shown in (a) is obtained. Here, the low frequency component is a component due to the activity of the heart or respiratory activity of the human body, but the high frequency component is a fluctuation component due to the piezoelectric element, and therefore signal processing is required to remove the high frequency component. Here, the maximum displacement amount detecting means detects the maximum displacement amount during a time period larger than the cycle of the high frequency component to remove the high frequency component. The output signal of the maximum displacement amount detecting means is shown in FIG. In this way, the high frequency components are removed and only the features of the low frequency components can be extracted. On the other hand, in the occupancy detection device of the conventional technology, the high frequency component is removed by smoothing by the smoothing means. However, when such a signal is smoothed, the signal obtained because the high frequency component is included is Very small Here, by using the maximum displacement amount detecting means for removing the high frequency component, the magnitude of the output signal obtained as compared with the case where the smoothing means is used is shown in FIG.
It is about 5 times that in (b). Therefore, here, in the case of using the maximum displacement amount detecting means, the amplification factor of the amplifying means necessary to obtain a signal of the same magnitude as in the case of using only the smoothing means is ⅕ of that in the case of using only the smoothing means. The presence or absence of a person can be determined with a smaller amplification factor than the conventional example.

With the above operation, the presence or absence of the human body on the device can be determined with a small amplification factor by detecting the maximum displacement amount of the weak signal obtained from the weak body movement of the human body in a resting state. Therefore, there is an effect that it is possible to provide a human body detection device that is less affected by noise.

Next, a second embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 3 is a block diagram of this embodiment. In FIG. 3, the present embodiment is different from the first embodiment in that the maximum displacement amount detecting means 10 is followed by a smoothing means 11 for smoothing the output of the maximum displacement amount detecting means 10.

The operation of the above configuration will be described below. The output value from the maximum displacement amount detection means detects the maximum displacement amount of the signal during a certain fixed time and outputs it.Therefore, when a momentary disturbance of the waveform occurs due to noise etc., the value at that time is output as it is. Therefore, it was found that the human body may be erroneously determined to exist even when the human body does not exist on the device. In order to solve this problem, the smoothing means for smoothing the output of the maximum displacement amount detecting means is provided.

FIGS. 4 and 5 show the signal conversion results of this embodiment. First, FIG. 4 shows a case where a person is absent. (A) shows the output signal of the amplification means 9. Waveform distortion due to noise is seen in A. (B) shows an output signal obtained by converting the signal of (a) by the maximum displacement amount detecting means 10. The disturbance of the waveform due to the noise shown in (a) appears in A '. (C) shows a signal obtained by smoothing the signal shown in (b) by a smoothing means. Here, it can be seen that the disturbance of the waveform due to noise is considerably small as shown by A ″.

Next, FIG. 5 shows a case where a human body is present.
(A) shows the output signal of the amplification means 9. Waveform distortion due to noise is seen in B. (B) shows an output signal obtained by converting the signal of (a) by the maximum displacement amount detecting means 10.
The disturbance of the waveform due to the noise shown in (a) appears in B '. (C) shows a signal obtained by smoothing the signal shown in (b) by a smoothing means. Here, it can be seen that the disturbance of the waveform due to noise is considerably small as shown by B ″. Further, the waveform of the output signal after smoothing is smoothed because it is smoothed as compared with FIG. Although the phase is also changing, the signal due to the body movement of the human body is captured, and it is possible to reduce the influence of noise regardless of the presence or absence of the human body.

By virtue of the above operation, the present invention can reduce the disturbance of the waveform due to noise, so that the influence of noise can be reduced and a human body detecting device with less erroneous determination can be provided.

According to the above-described embodiment, it is possible to accurately grasp the number of seated persons and vacant seats in the theater, the inside of a car, etc., and to manage the presence of a person in a bed in a hospital or the like with a small amplification factor with high accuracy. Further, when applied to the air conditioning control and the sound field control in the room or in the vehicle, the air conditioning control and the sound field control according to the seating location can be performed, and the comfort in the room is enhanced.

[0020]

As described above, according to the human body detecting apparatus of the present invention, the following effects can be obtained.

That is, since the maximum displacement amount of a signal due to a minute body motion of the body at rest during a certain period of time is detected,
The presence or absence of the human body can be determined with a small amplification factor.

Further, since the detected maximum displacement amount is smoothed, it is possible to reduce the influence of noise, and it is possible to provide a human body detection device with less malfunction.

[Brief description of drawings]

FIG. 1 is a block diagram of a human body detection device according to a first embodiment of the present invention.

FIG. 2 (a) is a waveform diagram of an output signal of an amplifying means in the same device, and (b) is a waveform diagram of an output signal of a maximum displacement amount detecting means in the same device.

FIG. 3 is a block diagram of a human body detection device according to a second embodiment of the present invention.

FIG. 4 (a) is a waveform diagram of an output signal of the amplification means in the absence of the device, (b) is a waveform diagram of an output signal of the maximum displacement amount detection means in the absence of the device in the device, and (c) is a waveform of the output signal of the absence in the device. Waveform diagram of output signal of smoothing means

FIG. 5 (a) is a waveform diagram of an output signal of an amplifying means in the same apparatus when seated (b) is a waveform diagram of an output signal of a maximum displacement amount detecting means in the same apparatus when seated (c) Waveform diagram of output signal of smoothing means when seated

FIG. 6 is a block diagram of a conventional human body detection device.

FIG. 7 is a waveform diagram of an output signal of a conventional smoothing unit.

[Explanation of symbols]

 1, 7, 14 Piezoelectric element 2, 8, 15 Filter 3, 9, 16 Amplifying means 4, 10 Maximum displacement amount detecting means 5, 12, 18 Judging means 6, 13, 19 Seat 11, 17 Smoothing means

Claims (2)

[Claims] 1. A piezoelectric element provided in a device, a filter for filtering a specific frequency component of an output signal of the piezoelectric element, an amplification means for amplifying an output signal of the filter, and an output of the amplification means. A human body detecting device comprising a maximum displacement amount detecting means for detecting a maximum displacement amount of a signal during a certain period of time, and a determining means for determining the presence or absence of a person in the device based on an output signal of the maximum displacement amount detecting means. 2. A piezoelectric element provided in a device, a filter for filtering a specific frequency component of an output signal of the piezoelectric element, an amplifying means for amplifying an output signal of the filter, and an output of the amplifying means. A maximum displacement amount detecting means for detecting the maximum displacement amount during a certain fixed time of the signal, a smoothing means for smoothing the output from the maximum displacement amount detecting means, and the device based on the output signal of the smoothing means. Human body detection device comprising a determination means for determining the presence or absence of a person.