JPH0433641A - Biodisplacement detector - Google Patents

Abstract

PURPOSE:To exactly detect the displacement of a living body by outputting a change in the external pressure to a detector and a change in the distance between the detector and a body to be examined in accordance with the displacement of the living body as a change in the electrostatic capacity between the electrode plate and electrode foil facing each other. CONSTITUTION:This detector is constituted of the electrode plate 1 which has high flexibility and stability, the electrode foil 2 which faces this electrode plate and a dielectric sheet 3 which has high flexibility and stability and is interposed between the electrode plate 1 and the electrode foil 2. A displacement is generated by the respiration motion or the like of the living body when the detector constituted in the above-mentioned manner is mounted to the arbitrary position of the living body, for example, directly to the living body or via clothing. This displacement acts as the external pressure to change the distance between the electrode plate 1 and the electrode foil 2, thereby the electrostatic capacity between both changes. The distance between the electrode foil (or electrode plate) and the living body is simultaneously changed by the displacement of the living body, by which the electrostatic capacity between the electrode foil 2 and the living body is changed. Namely, the displacement of the living body is detected as the total change of the change in the electrostatic capacity between the electrode plate 1 and the electrode foil 2 and the change in the electrostatic capacity between the electrode foil 2 and the living body. The change in the living body, therefore, detected with a high sensitivity.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is capable of statically detecting partial changes in a living body (subject), such as movements of a portion of the abdomen or chest due to breathing movement, heartbeat, etc. This invention relates to a biological displacement detector that detects changes in capacitance.

(Prior Art) Among conventional biological displacement detectors of this type, one is known that detects biological displacement as a change in capacitance.

Conventionally, focusing on the fact that the distance between the electrode and the living body changes due to partial displacement of the living body, the change in distance is calculated as 1.
The change in capacitance between the two is detected, and the displacement of the living body is detected from this.

(Problem to be Solved by the Invention) However, according to such a detection means, the change in capacitance with respect to the displacement of the living body is slight, and it is extremely difficult to accurately detect the displacement of the living body from this change.

The present invention aims to improve the detection sensitivity when detecting the displacement of a living body as a change in capacitance.

(Means for Solving the Problems) The present invention provides an electrode plate having high flexibility and resilience, an electrode foil made of metal foil facing the electrode plate, and a gap between the electrode plate and the electrode foil. It is composed of a flexible and highly resilient dielectric sheet interposed therebetween.

Changes in external pressure and distance between the living body (subject) and
It is characterized in that the output is output as a change in capacitance between the electrode plate and the electrode foil.

(Function) The detector configured as described above is attached to an arbitrary position of a living body, for example, directly on the living body or indirectly through clothing. When a displacement occurs due to breathing movement of the living body, the displacement becomes an external pressure, the distance between the electrode plate and the electrode foil changes, and the capacitance between the two changes.

At the same time, the electrode foil (or electrode plate) is changed due to the displacement of the living body.
The distance between the electrode foil and the living body changes, thereby changing the capacitance between the electrode foil and the living body.

In other words, the displacement of the living body is detected as the sum of the change in capacitance between the electrode plate and the electrode foil and the change in the capacitance between the electrode foil and the living body. This makes it possible to detect changes in the living body with high sensitivity.

Displacement due to breathing movement of the living body is repeated.

The electrode foil and dielectric sheet are deformed by the application of external pressure during the intake movement. However, when the external pressure is released by the next expiratory movement, the electrode foil and dielectric sheet
Restore to original state. This makes it possible to extract the displacement of the living body as a change in capacitance in response to each repetition of respiratory movement.

(Example) An example of the present invention will be described with reference to the drawings. 1 is an electrode plate that is the core of the detector, and is a thin metal plate (for example, a phosphor bronze plate or brass plate of about 0.3 mm) or an acrylic resin plate of about 0.511 m+ with a metal film sputtered on both sides. It is used to make it highly flexible and resilient.

Reference numeral 2 denotes an electrode foil that slides on the electrode plate 1, and has a thickness of 10 to 10 mm so as not to impede the flexibility and restorability of the dielectric sheet, which will be described later.
It is composed of about 15 μm of gold gItN.

Reference numeral 3 denotes a dielectric sheet interposed between the electrode plate 1 and the electrode M2, and the electrode foil 2 responds to slight changes in external pressure to cause the electrode plate 1 to
A highly flexible and resilient material is used so that changes in capacitance between the two can be output. For example, about 10μ thick
A polyethylene sheet with a diameter of about 100 m is used.

4 is the lead wire of the electrode plate 1, 5 is the lead wire of the electrode foil 2, 6
is the outer skin that protects, insulates, and integrates the whole. The detector 7 of the present invention is configured as described above.

In the example shown in the figure, the dielectric sheet 3 and the electrode foil 2 are made to face each other on both sides of the electrode plate 1, but if this is done, the dielectric sheet 3, the electrode foil 2, and the dielectric sheet 3 are placed symmetrically when viewed from the electrode plate 1. Therefore, even if the detector 7 is attached to a living body without considering its front and back sides, there will be no difference in characteristics, which is convenient.

Note that instead of this configuration, a configuration in which the dielectric sheet 3 and the electrode [2] are made to face only one surface of the electrode plate 1 may also be used.

The detector 7 is attached to an arbitrary position on the living body, for example, directly by being sandwiched between the living body and clothing, or indirectly by being sandwiched between clothing. Further, the electrode plate 1 and the electrode foil 2 are connected to a detector drive oscillation circuit. At this time, the electrode plate 1 has the same potential as the living body.

When a displacement occurs in the living body due to the breathing movement of the living body or movement of the abdomen or chest due to the heartbeat, the displacement becomes external pressure and the distance between the electrode plate 1 and the electrode i2 changes, causing both The capacitance between changes.

At the same time, the distance between the electrode foil 2 (or electrode plate 1) and the living body changes due to the above-mentioned displacement of the living body, thereby changing the capacitance between the electrode foil 2 and the living body.

In this way, the displacement of the living body is detected as a change in the capacitance between the electrode plate 1 and the electrode M2 and the capacitance between the electrode foil 2 and the living body. become. This makes it possible to detect changes in the living body with high sensitivity.

The displacement caused by the above-mentioned breathing movement of the living body is repeated. The electrode @2 and the dielectric sheet 3 are deformed by the application of external pressure during the intake movement. However, when the external pressure is released by the next exhalation movement, the electrode foil 2 and dielectric sheet 3 return to their original states. This makes it possible to extract the displacement of the living body as a change in capacitance in response to each repetition of respiratory movement.

FIG. 3 shows an example of a detector drive oscillation circuit. The illustrated example uses a Hartley oscillation circuit, and the detector 7 is connected in parallel with the resonant coil 11. At this time, the electrode foil 2 is connected to the high potential side, and the electrode plate 1 is connected to the ground potential side.

When the capacitance of the detector 7 changes, the oscillation frequency changes, which is converted into an oscillation amplitude change by the load coil 13 of the transistor 12 and transmitted to the buffer transistor 14 (see the waveform diagram in FIG. 4). ).

The buffer transistor 14 detects and amplifies the oscillation amplitude change and outputs it, as shown in the waveform diagram of FIG.

The waveform diagram in FIG. 5 is an output waveform diagram when the detector 7 is attached near the abdomen to detect respiratory motion.

(Effects of the Invention) As detailed above, according to the present invention, based on the displacement of the living body, changes in capacitance due to changes in external pressure applied to the detector, and changes in the capacitance between the detector and the living body wearing it, are detected. The combination of changes in capacitance between the two electrodes can be output as a change in capacitance of a detector with two poles facing each other. Therefore, changes in biological displacement can be detected with higher sensitivity than with conventional configurations. It produces the effect that can be achieved.

[Brief explanation of drawings]

Fig. 1 is a front view showing an embodiment of the present invention, Fig. 2 is a sectional view thereof, Fig. 3 is a circuit diagram showing an example of a detector drive oscillation circuit, and Figs. 4 and 5 are for explanation of the same operation. FIG.

Claims (1)

[Claims] a flexible and restorable electrode plate, an electrode foil made of metal foil opposite to the electrode plate, and a flexible and restorable dielectric interposed between the electrode plate and the electrode foil. a body sheet, and outputs changes in external pressure and changes in distance from the subject as changes in capacitance between the electrode plate and the electrode foil.