Capacitive weight sensor and respiration / heart rate sensor

Abstract

A capacitive weight sensor installed between the bed frame and mattress provides a capacitive weight sensor that can accurately and precisely detect minute pressure changes on the mattress, such as body movement, defecation, urination, respiration, and heart rate. [Solution] The conductor covering the resin plate covered by the outer cover 12 is covered on both sides of the resin plate, excluding a width of approximately 10 mm around the outer edge, using a cloth shielding material. The structure consists of a shielding cloth electrode S16 covered with a dielectric sheet and a pair of shielding cloth electrodes E18 arranged opposite each other, and elastic spacers 22, 24, and 26 arranged around the entire circumference of the gap at the outer edge, forming multiple detection block layers (air layers) 36 on the electrodes. This structure provides a shielding function to prevent the effects of electromagnetic waves and noise, and a detection sensitivity function depending on the density and volume of the elastic spacers and the number and area ratio of the detection block layers. This capacitive weight sensor has a shielding function to prevent the effects of electromagnetic waves and noise, and a detection sensitivity function.

Description

Technical Field

[0001] The present invention relates to a capacitance-type weight sensor installed between a bed frame and a mattress (150 mm thick), and to a capacitance weight sensor and a respiration / heartbeat sensor that can accurately detect and measure slight pressure changes on the mattress with high precision. Background Art

[0002] As a capacitance-type weight sensor in which a two-pole capacitor electrode and a shield electrode are formed by conductive coating or the like, and a dielectric sheet and a plurality of elastic spacers are provided between the electrodes to form a pair of capacitor electrodes, there is the technology described in Patent Document 1 below. The capacitance-type weight sensor described in Patent Document 1 provides a dielectric sheet between upper and lower two sheets formed by conductive coating or the like on a resin plate (insulator) made of an elastic material to form electrodes, and forms an outer peripheral frame (detection unit 1 block) with an elastic spacer in the gap between both electrode surfaces. A structure in which a plurality of elastic spacers are arranged in the frame has a capacitance-type weight sensor that detects a change in the load that compresses the elastic spacer and the air layer applied between the capacitor electrodes as a change in the capacitance between the capacitor electrodes.

[0003] However, the capacitance-type weight sensor described in Patent Document 1 covers the entire outer periphery of the panel electrode with a shield electrode, but cannot completely eliminate the influence of electromagnetic waves, etc. Also, the detection part of the entire panel electrode is one block, and a dozen or so elastic spacers are arranged in that block. In a structure that seals the air layer, the pressure when weighted is improved, but depending on the location where pressure is applied, there are problems such as the detected value being different and it being difficult to accurately detect minute pressures such as heartbeat.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Therefore, the present invention has been made in view of these circumstances, and aims to provide a capacitive weight sensor that can detect even slight pressure on a mattress with ultra-high sensitivity and accuracy by eliminating electromagnetic interference by constructing a shielded cloth electrode using a cloth electromagnetic shielding material, forming a uniform number of detection block layers (air layers) on the detection portion of the electrode using an elastic spacer, and providing a structure in which the air within the detection block layers is not sealed, and by providing a detection sensitivity function through the density and volume of the elastic spacer that constitutes the detected value and the configuration of the number of detection block layers.

[0006] The first aspect of the present invention, which solves the above problems, is a capacitive weight sensor characterized by a structure that completely eliminates the effects of electromagnetic interference such as electromagnetic waves by providing a shielding function. The conductor covering the resin plate (insulator) made of an elastic material covered with an outer skin cover is made of a flexible shielding cloth material made of cloth that combines conductivity and electromagnetic wave shielding properties and covers both sides of the resin plate from the outer edge, excluding a width of approximately 10 mm, and both sides of the shielding cloth electrode S are covered with a dielectric sheet, and a pair of shielding cloth electrodes E are arranged opposite each other on both electrode surfaces, with one side of each electrode similarly covered, excluding a width of approximately 10 mm.

[0007] The second aspect of the present invention, which solves the above problems, is a capacitive weight sensor characterized by a structure comprising an elastic spacer 1 positioned on the horizontal axis of the outer edge of the gap in contact between the shield cross electrode S and a pair of shield cross electrodes E, and an elastic spacer 2 positioned on multiple vertical axes inside the horizontal axis, thereby forming multiple detection block layers (air layers), and an elastic spacer 3 positioned in the center of each detection block layer.

[0008] A third aspect of the present invention for solving the above problems is a capacitive weight sensor characterized by having a fluid structure that does not seal the air in each detection block layer (air layer) composed of the elastic spacer 1 and elastic spacer 2, and having a structure that constitutes the detection sensitivity depending on the density and volume of the elastic spacers 1 to 3 and the number and area ratio of the detection block layers.

[0009] The fourth aspect of the present invention, which solves the above problems, is a capacitive weight sensor detection system comprising a capacitance measuring instrument that measures a capacitance output by electrical signal to detect slight changes with high precision, by configuring a structure such as a shield cloth electrode using a shield cloth material, multiple detection block layers made of elastic spacers in the gaps between the shield cloth electrodes, and not sealing the air in each detection block layer, and an external device that detects current flow.

[0010] According to the present invention, a capacitive weight sensor installed between the bed frame and mattress is a capacitive weight sensor that accurately and highly accurately detects various body movements and minute pressure changes of the user on the bed, such as getting in and out of bed, turning over, body movements, defecation and urination, decreased breathing, increased breathing, apnea, and heart rate. It can be provided to the fields of future medical care and nursing care, such as checking the life status of patients in hospital rooms at night, and monitoring care facilities and people living alone at home. [Brief explanation of the drawing]

[0011] [Figure 1] One embodiment of the present invention is a capacitive weight sensor, in which each detection block layer (air layer) is formed by elastic spacers on an electrode formed by a shielding cloth electrode on a resin plate covered with an outer shell cover, and the plan view shows the air flow function. [Figure 2]This is a cross-sectional view showing the output wire of a lead wire SE made from copper foil tape in close contact with the shield cloth electrode SE, in one embodiment of the present invention. The upper and lower pair of shield cloth electrodes SE have both sides of the shield cloth electrode S covered with a dielectric sheet, and several detection block layers (air layers) are formed between them using elastic spacers. [Figure 3] This diagram shows the installation of a capacitive weight sensor placed between the bed frame and the mattress. [Figure 4] This graph shows the change in capacitance based on data collected over 17.5 hours of environmental changes using a capacitive weight sensor placed between the bed frame and mattress. [Figure 5] This graph shows the change in capacitance based on data collected over 24 hours by installing capacitive weight sensors on the bed frame and mattress, and measuring environmental changes. [Figure 6] This graph shows the change in capacitance in a capacitive weight sensor, based on data measured over 15 hours under no load and considering environmental changes. [Figure 7] The data graph shows the temperature change measured over 15 hours with no load on the capacitive weight sensor, and the measurement date and time are the same as in Figure 6. [Figure 8] This graph shows the change in capacitance based on data measured over 24 hours under no load on a capacitive weight sensor, representing the change in capacitance. [Figure 9] The data graph shows the temperature change measured over 24 hours with no load on the capacitive weight sensor, and the measurement date and time are the same as in Figure 8. [Figure 10] Figures 4 to 9 are tables listing the data from the measurement of environmental and temperature changes. [Figure 11] This graph shows the measured change in the respiratory waveform, obtained by placing a capacitive weight sensor between the bed frame and mattress, and performing two respiratory pauses while the person was lying on their back and breathing normally. [Figure 12] Figure 11 shows the measured data values ​​of the heart rate waveform ▲1▼-1 during respiratory arrest. [Figure 13]Figure 11 shows the measured data values ​​of the heart rate waveform ▲1▼-2 during respiratory arrest. [Figure 14] This graph shows the change in respiratory waveform data obtained by placing a capacitive weight sensor between the mattress and the sheet, and then performing respiratory arrest and rapid breathing while the person was lying on their back and breathing normally. [Figure 15] Figure 14 shows the data values ​​for the heart rate waveform ▲1▼-1 during respiratory arrest. [Figure 16] Figure 14 shows the data values ​​for the tachypnea waveform ▲1▼-2 during the period of respiratory arrest. [Modes for carrying out the invention]

[0012] One embodiment of the present invention will be described with reference to the drawings. However, the present invention is not limited thereto, and various modifications are possible as long as they do not deviate from the spirit of the present invention.

[0013] Figure 1 is a plan view of a capacitive weight sensor 10, which is one embodiment of the present invention, and Figure 2 is a cross-sectional view thereof. The capacitive weight sensor 10 is composed of a shielded cloth electrode S16, which is made by covering both sides of an insulator 14 with a shielding cloth material, excluding a width of approximately 10 mm, and then covering both sides with a dielectric sheet 20, and a shielded cloth electrode E18, which is made by similarly covering two opposing insulators 14 on one side with a shielding cloth material and then pressing them together, as a pair of structures. Each detection block layer (air layer) 36, formed by elastic spacers 22, 24, and 26 attached between the two electrodes, is a structure that accurately and precisely detects minute pressures, has the function of allowing air to flow without sealing, and is made of a cover 12, etc.

[0014] Figure 2 is a cross-sectional view of Figure 1, showing a structure with the configuration of sealing the conventional shield electrode portion and the air layer removed. In this Figure 2, elastic body spacers 1 arranged on the upper and lower horizontal axes of the outer edge of the gap between the shield cross electrode S16 and the shield cross electrode E18, and elastic body spacers 2 arranged on a plurality of vertical axes form a plurality of detection block layers (air layers), and an elastic body spacer 3 is arranged at the center of each detection block layer (air layer). Lead wires S30 and E32 are drawn out from the copper foil tapes 28 of the shield cross electrode S16 and the shield cross electrode E18 and are connected to external devices.

[0015] Figure 3 is a view showing the capacitive weight sensor 10 installed between the bed frame and the mattress, and constitutes a structure that accurately detects a slight pressure from above the mattress with a thickness of 150 mm.

[0016] Figure 4 shows data obtained by installing the capacitive weight sensor between the bed frame and the mattress and measuring the change in capacitance every 0.1 second under natural environment. The measurement time was 17.5 hours, the maximum capacitance value during measurement was 3699 pf, and the minimum capacitance value was 3640 pf. The change amount of capacitance under natural environment was 59 pf, and the change rate of capacitance with respect to the average capacitance value of 3669 pf (the average of the maximum and minimum) was as small as 0.016%, and there was no interference from electromagnetic waves due to noise or the like.

[0017] Figure 5 shows data obtained under the same measurement conditions as Figure 4. The measurement time was 24 hours, the maximum capacitance value during measurement was 358 ps, and the minimum capacitance value was 3642 pf. The change amount of capacitance under natural environment was 56 pf, and the change rate of capacitance with respect to the average capacitance value of 3614 pf (the average of the maximum and minimum) was as small as 0.0159%, and there was no interference from electromagnetic waves due to noise or the like.

[0018] Figure 6 shows data obtained by measuring the change in capacitance every 0.1 second with no load on the capacitive weight sensor. The measurement time was 15 hours, the maximum capacitance value during measurement was 2111 pf, and the minimum value was 2098 pf. The change amount of capacitance under natural environment was 13 pf, and the change rate with respect to the average capacitance value of 2104 pf (the average of the maximum and minimum) was as small as 0.0061%, and there was no interference from electromagnetic waves due to noise or the like.

[0019] Figure 7, like Figure 6, shows data measured every minute for temperature changes due to the natural environment at the same time on the same day, with no load on the sensor. The maximum temperature measured was 30.2°C and the minimum temperature was 24.1°C, with a temperature change of 6.1°C. From the measurement results of capacitance change of 13pf in Figure 6 and temperature change of 6.1°C in Figure 7, it can be seen that for every 1°C change in temperature, the capacitance changes by 2.13pf. This means that the rate of change of 1°C in temperature relative to the average capacitance value of 2104pf is a small 0.001%.

[0020] Figure 8 shows the same measurement conditions as in Figure 6, but with a measurement time of 24 hours. The maximum capacitance value during measurement was 2109 pf, and the minimum capacitance value was 2095 pf. The change in capacitance under natural environmental conditions was 14 pf, and the average capacitance of the maximum and minimum was 2102 pf, with a rate of change of only 0.0066%. The measurement data, despite the different measurement time and capacitance values ​​compared to Figure 6, is almost identical, and there was no interference from electromagnetic waves such as noise.

[0021] Figure 9 shows the same measurement conditions as in Figure 7, with temperature measurements taken over 24 hours. The maximum temperature measured was 32°C, the minimum temperature was 25.5°C, and the change was 6.5°C. The capacitance change of 14pf in Figure 8 and the temperature change of 6.5°C in Figure 9 indicate that the capacitance changes by 215pf for every 1°C change in temperature. Therefore, the rate of change of 1°C in temperature relative to the average capacitance value of 2102pf (maximum to minimum) is a negligible 0.001%.

[0022] Figure 10 is a table listing the environmental measurement data and temperature measurement data for each load condition on the capacitive weight sensor shown in Figures 4 to 9.

[0023] Figure 11 shows the measurement data of a change of 80 pf in the respiratory waveform during a single breath when the sensor was placed between the bed frame and the mattress (150 mm thick).

[0024] Figure 12 shows the measured data of the change of 4 pf in the heart rate waveform ▲1▼-1 during respiratory arrest, as shown in Figure 11.

[0025] Figure 13 shows the measured data of the change of 4 pf in the heart rate waveform ▲1▼-2 during respiratory arrest, as shown in Figure 11.

[0026] Figure 14 shows the measurement data for a single respiratory waveform change of 110 pf when the sensor is placed between the mattress and the fitted sheet (3 mm thick).

[0027] Figure 15 shows the measured data for the change of 5 pf in the heart rate waveform ▲1▼-1 during respiratory arrest, as shown in Figure 14.

[0028] Figure 16 shows the measurement data for the change of 60 pf in the tachypnea waveform ▲1▼-2 in Figure 14. [Explanation of Symbols]

[0029] 10 Capacitive Weight Sensor 11. Capacitive weight sensor installation section 12 Outer Cover 14 Insulator 16 Shielded cross electrode S 18 Shielded cross electrode E 20 Dielectric Sheets 22 Elastic Spacer 1 24 Elastic Spacer 2 26 Elastic Spacer 3 28 Copper foil tape 30 lead wires S, 32 Lead wire E 34 Lead wire openings and ventilation openings 36 Detection block layer (air layer) 38 Gap between spacers 40 bed frame 42 mattresses

Claims

1. A capacitive weight sensor characterized by a shielding function, comprising a shield cloth electrode S, which covers a resin plate (insulator) made of an elastic material covered with an outer sheath cover, using a cloth-made shield cloth material that is conductive and has electromagnetic wave shielding properties to cover both sides of the resin plate except for the outer circumference, which is about 10 mm wide, and both sides of which are covered with a dielectric sheet, and a pair of shield cloth electrodes E which are arranged opposite each other on both electrode surfaces of the shield cloth electrode S, which cover one side of the resin plate except for the outer circumference, which is about 10 mm wide, thus providing a shielding function.

2. A capacitive gravity sensor characterized by comprising elastic spacers 1 arranged along the vertical and horizontal axes of the gap at the outer edge in contact with the shield cross electrode S and a pair of shield cross electrodes E, and elastic spacers 2 arranged along multiple vertical axes to form multiple detection block layers (air layers) on the electrode surface, and elastic spacers 3 arranged within each detection block layer.

3. The capacitive weight sensor according to claim 2, characterized in that it has a fluidity function for air that is not sealed by providing gaps between spacers in a plurality of detection block layers (air layers) composed of the elastic spacer 1, elastic spacer 2, and elastic spacer 3, and has a detection sensitivity mechanism and function depending on the density and volume of the elastic spacers and the number and area ratio of the detection block layers.

4. A capacitive weight sensor detection system comprising a capacitive weight sensor according to any one of claims 1 to 3, and an external device for detecting current flow from a capacitance measuring instrument that measures the capacitance output between a shielded cross electrode S and a shielded cross electrode E using an electrical signal.

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