JP2017169881A - Bed sensor and bed state determination device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bed sensor and a bed state determination device at low cost in which malfunction due to change of temperature/humidity and mutual interference is reduced, a non-contact detection distance is extended so as to be installed under a mat spaced apart from a human body, and a care-receiver may carry thereof.SOLUTION: A bed sensor 101 of an electrostatic capacity type is provided for detecting presence or absence of a body B on a bed. The bed sensor comprises a detecting electrode formed of a pair of positive and negative electrodes 1a, 1b, and a reference electrode provided in proximity to the detecting electrode and formed of a pair of positive and negative electrodes 2a, 2b. The bed sensor outputs a detection signal of presence of the body B according to a difference of capacitance by the difference of distance to the body B of the detecting electrode and the reference electrode.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a bed leaving sensor and a bed leaving state determination device, and more specifically, is a capacitance type bed leaving sensor that detects the presence or absence of a body on bedding, and includes a first capacitance electrode and a second capacitance. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bed sensor and a bed leaving state determination apparatus that outputs a detection signal of the presence or state of a body according to a difference in electrostatic capacitance due to a difference in distance of electrodes to the body.

  A patient who is difficult to walk independently may fall off the bed, or may fall accidentally trying to move to a wheelchair or to walk alone. In addition, he / she may be missing, or he / she may get out of bed at the time of examination and cannot be examined at that time. Also, it may be delayed to notice that the body has not been turned over normally, that it is moving abnormally, or that it is not moving at all. In order to prevent these accidents, to prevent wrinkles, and to detect medical conditions at an early stage, conventionally, various devices have been used to detect the presence of the body and determine bed leaving.

  For example, as disclosed in Patent Document 1 (Japanese Patent Laid-Open No. 2015-8921), an apparatus for detecting a load when sleeping is provided by a sensor that detects the presence or absence of a load, Patent Document 2 Japanese Patent Application Laid-Open No. 2015-126803, a device for detecting the presence of a load due to the grounding of a foot by disposing a sensor for detecting the presence or absence of a load on the floor beside the bed. Patent Document 4 (Japanese Patent Laid-Open No. 2015-146856) discloses an apparatus for detecting the presence of a body when sleeping by arranging a capacitive sensor as disclosed in Japanese Patent No. 45296 A photoelectric sensor that detects an object according to reflected light from the object as disclosed, a beam sensor that detects an object according to the presence or absence of reflected light reflected by a reflector, and heat generated by the object Detects objects according to A device that detects bed leaving by a non-contact detection sensor such as an ultrasonic sensor that detects an object according to the presence or absence of reflection of an ultrasonic signal, a sensing element such as a tag sensor (IC tag) There is a device that can be carried around to detect getting out of bed.

Japanese Patent Laying-Open No. 2015-8921 JP2015-126803A JP 2012-45296 A Japanese Patent Laying-Open No. 2015-146856 JP 2013-235313 A

  However, the conventional sensor for detecting the body has various problems as a sensor for determining the bed leaving state. When a load sensor or a capacitance sensor is disposed in or under the bedding, the temperature and humidity change depending on the care recipient. For this reason, the sensitivity of the load sensor or the capacitance sensor changes and malfunctions.

  In addition, when a load sensor or a capacitance sensor is disposed under the mat, the distance between the sensor and the human body is greatly separated to reduce the sensitivity, and there are mats with various thicknesses. The effects of humidity changes and mat thickness differences are significant.

  In addition, differences in body composition, such as differences in body weight, body temperature, body fat percentage, and degree of sweating, will affect the sensitivity of load sensors and capacitance sensors, causing malfunctions and reduced sensitivity. Therefore, there is a problem that any constitution must be dealt with.

  In addition, when the capacitance sensor is used for posture detection, for example, the capacitance sensor is disposed in a plurality of regions such as a chest, a waist, a buttock, and a foot. There is a problem that malfunction occurs.

  In addition, in a device that detects the bed leaving due to the grounding of the foot by installing a load sensor on the floor beside the bed, etc., the patient being cared for, such as disconnection or breakage due to heavy pressure on the bed or chair foot, nurses or visitors There is a problem of misjudgment caused by stepping on other than the above, and there is a problem that such an apparatus cannot prevent falling from the bed and early detection of a medical condition.

  In addition, malfunction of the bed sensor and the bed condition detection device is a serious problem in nursing. The devices that make misjudgments have been avoided because of the burden on the nurses of extra work, and some nursing / nursing facilities have been revoked.

  Non-contact detection sensors such as a photoelectric sensor, a beam sensor, a heat ray sensor, and an ultrasonic sensor are expensive and have a problem that they cannot be popularized. A sensing element such as a tag sensor (IC tag) has a problem that it gives a sense of restraint and a sense of incongruity to a patient who carries the sensing element.

  In order to solve such problems peculiar as a bed leaving sensor and a bed leaving detection device, the present invention is based on a technique derived from Patent Document 5 (Japanese Patent Laid-Open No. 2013-235313), which is a prior application of the inventor. Reduces malfunction due to temperature / humidity changes and mutual interference, extends the non-contact detection distance so that it may be installed under a mat that is separated from the human body, and does not require caregivers to carry it, and is inexpensive It is an object to provide a bed leaving sensor and a bed leaving state determination device.

  In order to achieve the above object, a bed sensor of the present invention is a capacitance type bed sensor that detects the presence or absence of a body, and includes a first capacitance electrode formed by a pair of positive and negative electrodes, A second electrostatic capacitance electrode provided in the vicinity of one electrostatic capacitance electrode and formed by a pair of positive and negative electrodes, and the first electrostatic capacitance electrode and the second electrostatic capacitance electrode. A detection signal for the presence or absence of the body is output in accordance with a difference in capacitance due to a difference in distance to the body.

  If there is a difference in the distance to the body between the two electrodes, there will be a difference in their capacitance. The present invention outputs the detection signal of the presence or absence of the body according to the difference in capacitance in the same environment, using one capacitance electrode for detection and the other adjacent capacitance electrode as a reference. For this reason, even if the capacitance of one capacitance electrode changes with temperature, humidity, etc., the other also changes with temperature, humidity, etc., so the difference in capacitance is the change of temperature, humidity, etc. Not affected. In addition, although the capacitance changes depending on the physical constitution of the body, the bed sensor of the present invention is not affected by the constitutional change because the electrostatic capacitances of both electrostatic capacitance electrodes change together even if the constitution changes. . Thus, since the influence of the environment and the constitution of the body is small, the presence or absence of the body on the bedding can be detected with high sensitivity. Therefore, the bed leaving sensor of the present invention can be installed under a mat that is separated from the body. Moreover, since the bed leaving sensor of the present invention is an inexpensive capacitive sensor, it is less expensive than non-contact detection sensors such as photoelectric sensors, beam sensors, heat ray sensors, and ultrasonic sensors. In addition, since it is not carried by the nurse like the tag sensor, it does not give the nurse a sense of restraint or discomfort due to carrying.

  In the bed leaving sensor of the present invention, the first capacitance electrode is disposed on a first substrate, the second capacitance electrode is disposed on a second substrate, and the first capacitance electrode is disposed on the second substrate. A spacer is disposed between one base material and the second base material, and the first capacitance electrode and the second capacitance electrode are provided so as to overlap with each other on an attachment surface. Is preferred.

  Thereby, the difference of the electrostatic capacitance of a 1st electrostatic capacitance electrode and a 2nd electrostatic capacitance electrode can be adjusted with the thickness of a spacer. In particular, flexibility is necessary when the bed leaving sensor is installed on a foldable bed or when cleaning is required. In this case, it is not a common printed board such as 1.6 mm thick glass epoxy. FPC (flexible printed circuit board) is preferred. However, since the thickness of the FPC is as thin as about 0.3 mm, the difference in capacitance between the first capacitance electrode and the second capacitance electrode is small. Therefore, the distance between the first capacitance electrode and the second capacitance electrode can be increased by inserting a spacer. This spacer needs an appropriate dielectric constant and should be excellent in flexibility.

  In the bed leaving sensor of the present invention, it is preferable to provide a vent hole penetrating from the surface on the first capacitance electrode side to the surface on the second capacitance electrode side. Thereby, environmental influences, such as a humidity difference and a temperature difference, are reduced. Further, an increase in humidity of the mat can be reduced.

  In the bed leaving sensor of the present invention, an AC voltage applying means for applying a common AC voltage to each of the first capacitance electrode and the second capacitance electrode, and the first capacitance electrode, A first rectifier that rectifies the applied voltage fed to the capacitance electrode; a second rectifier that rectifies the applied voltage fed to the second capacitance electrode; and the first rectifier. A comparison unit that compares the potential of the second rectification unit with the potential of the second rectification unit, and the potential of the first rectification unit becomes higher than the potential of the second rectification unit when the body moves away by a predetermined distance, It is preferable to include a potential difference unit whose impedance is set so that the potential of the first rectification unit becomes lower than the potential of the second rectification unit when the distance approaches a predetermined distance.

  Thereby, the sensitivity of bed leaving state detection can be easily adjusted by adjusting the impedance of the potential difference portion. In addition, it is easy to provide the potential difference portion. For example, one resistor may be provided in the second rectifying portion, and a voltage different from the voltage applied to the first capacitance electrode is applied to the second static electricity electrode. You may apply to a capacitive electrode.

  In the bed leaving state determination device of the present invention, the first electrostatic capacitance electrode formed by a pair of positive and negative electrodes and the pair of positive and negative electrodes provided in the vicinity of the first electrostatic capacitance electrode. A second capacitance electrode, wherein the presence of the body according to a difference in capacitance due to a difference in distance between the first capacitance electrode and the second capacitance electrode to the body. A capacitive element that outputs a detection signal for detecting presence / absence is based on a bed sensor installed in each of a plurality of detection areas and the detection signal from the capacitance element installed in each of the plurality of detection areas. And a determination unit for determining a bed leaving state.

  Thereby, various bed leaving states can be determined based on the detection for each detection region. For example, it is possible to determine whether to turn over, get up, posture before getting out of bed, getting out of bed, or not moving.

FIG. 1A is a plan view showing a configuration of a main part of the bed leaving state determination device of the first embodiment, and FIG. 1B is a front view of FIG. 1A. FIG. 2A is a block diagram illustrating a configuration of a main part of the bed leaving sensor according to the first embodiment, and FIG. 2B is a circuit diagram of FIG. 2A. FIG. 3A is a diagram showing the operation of the main part of the bed sensor of the first embodiment, and FIG. 3B is a graph showing the input voltage to the comparator of the bed sensor. FIG. 4 is a diagram showing a main part of the operation of the bed sensor according to the second embodiment. FIG. 5 is a diagram showing a main part of the operation of the bed sensor of the third embodiment.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to the embodiments and drawings. However, the embodiments shown below are not intended to limit the present invention to those described herein, and The invention can be equally applied to various modifications without departing from the technical idea shown in the claims. In addition, in each drawing used for the description in this specification, in order to make each member a size that can be recognized on the drawing, each member is displayed with a different scale, and is not necessarily actual. It is not displayed in proportion to the dimensions.

[First Embodiment]
A bed leaving state determination device 100 according to a first embodiment of the present invention will be described with reference to FIGS. The bed leaving state determination apparatus 100 includes a bed leaving sensor 101 and a determination unit 20. The bed sensor 101 is detachable from the determination unit 20 by the plug M of the bed sensor 101 and the socket F of the determination unit 20. As shown in FIG. 1B, the bed leaving sensor 101 has a sheet shape, is laid between the bed 50a of the bed 50 and the mat 50b, and detects the presence or absence of a body (nursing person) B on the mat 50b. The determination unit 20 determines the bed leaving state based on the detection signal from the bed leaving sensor 101, and notifies the result by various methods such as an alarm.

  As shown in FIG. 3A, one capacitive element 101a of the bed leaving sensor 101 includes a positive electrode 1a (+) and a negative electrode 1b (−) as a first capacitance electrode, and a detection electrode 1 including a pair of electrodes. Positive electrode 2a (+) negative electrode 2b (-) which is a second capacitance electrode, reference electrode 2 comprising a pair of electrodes, first base material 3 on which detection electrode 1 is disposed, and reference electrode 2, a spacer 5 that separates the detection electrode 1 and the reference electrode 2 from each other by a predetermined distance, and a first protective sheet 6 that protects both surfaces of the floor sensor 101 from water or the like. The first protective sheet 6, the detection electrode 1, the first base material 3, the spacer 5, the second base material 4, the reference electrode 2, the second protective sheet 7 in order from the body B side. 2 and the protective sheet 7 of FIG.

  The first base material 3 and the second base material 4 are soft insulating sheets and are FPC base materials. Note that the first base material 3 on which the detection electrode 1 is formed and the second base material 4 on which the reference electrode 2 is formed may be formed by bending one FPC instead of being separate.

  The spacer 5 is preferably made of a material such as rubber that has flexibility, heat insulation, and an appropriate dielectric constant. Further, as shown in FIG. 3A, the detection electrode 1 (positive electrode 1a and negative electrode 1b) and the reference electrode 2 (positive electrode 2a and negative electrode 2b) are provided so as to overlap each other in the direction perpendicular to the mounting surface. It is done.

  Thus, the capacitive element 101a includes the first protective sheet 6, the detection electrode 1, the first base material 3, the spacer 5, the second base material 4, the reference electrode 2, and the second protective sheet. 7. As shown in FIG. 1A, the capacitance element 101a includes a chest (M1) and its left and right sides (L1, R1), a waist (M2), its left and right (L2, R2), and a buttocks (M3) as detection areas. And the left and right sides (L3, R3), the foot (M4) and the left and right sides (L4, R4) thereof are installed in 12 regions 101b.

  Based on the presence or absence of the body B for each region, the determination unit 20 can determine the state of being in bed (turning over, getting up, posture before leaving the bed, leaving the bed, no movement, etc.). For example, if only the left region L3 of the buttocks or the right region R3 of the buttocks is “present”, a signal of caution is output to the nursing / care room as the body B is sitting on the bed 50 and may get out of bed. As a result, the bed leaving state determination apparatus 100 according to the present invention monitors the body B for turning over to prevent pressure ulcers (bed slippage), posture monitoring before bed leaving to prevent bed leaving, bed leaving state for preventing wrinkles and performing a diagnosis. Immobility monitoring for monitoring and early detection of medical conditions can be performed.

  As shown in FIG. 1A, the bed leaving sensor 101 is provided with a plug P for electrical connection with the determination unit 20 at the end. Since the bed leaving sensor 101 is a soft and waterproof sheet, it can be attached to the bed 50 where the waist and legs are bent. If the circuit part is sealed, the durability of sweat from the body B is improved and washed. You can also

  As shown in the block diagram of FIG. 2A, the bed sensor 101 includes a high-frequency generator 8 that generates a high frequency, a first impedance element 9 that supplies a high-frequency voltage generated from the high-frequency generator 8 to the detection electrode 1, A second impedance element 10 that feeds the high-frequency voltage generated from the high-frequency generator 8 to the reference electrode 2, a first rectifier 11 that rectifies the applied voltage fed to the detection electrode 1, and a reference electrode The output voltage via the first rectification unit 11 is higher than the output voltage via the second rectification unit 12 in the state where the body B is not present on the mat 50b and the second rectification unit 12 that rectifies the applied voltage fed to 2. The potential difference unit 13 that adds a potential difference so as to increase is compared with the output voltage via the first rectifier unit 11 output from the potential difference unit 13 and the output voltage via the second rectifier unit 12 output from the potential difference unit 13. Shit The and a comparator 14 for outputting a lifting state determination result.

  FIG. 2B is a simplified circuit diagram of FIG. The high frequency generator 8 is a CR oscillation circuit using an inverter as an example. The oscillation frequency may be set to an optimum frequency within a wide range of approximately 100 KHz to several MHz. The detection distance between the body B and the detection electrode 1, that is, the thickness of the mat 50b, the shapes of the detection electrode 1 and the reference electrode 2 And the dielectric constant of the substance (first base material 3, second base material 4, spacer 5) between the detection electrode 1 and the reference electrode 2, and the first rectifying element 6 and the second rectifying element What is necessary is just to determine suitably with the constant of 7. There is no need for an accurate oscillation frequency or a predetermined high-frequency voltage or the like, and it may be determined appropriately according to the specifications of the bed leaving sensor 101. The first impedance element 9 and the second impedance element 10 have the same impedance value. Therefore, the same high frequency voltage is supplied to the detection electrode 1 and the reference electrode 2. Further, it is not necessary to continuously generate a high frequency, and a high frequency voltage may be output intermittently in order to reduce power consumption.

  The first detection electrode 1 in FIG. 2B schematically illustrates a stray capacitance in a state where the body B is not detected and an operation illustrating a stray capacitance that increases when the body B is detected. A capacitor 1n is provided. Similarly, the first reference electrode 2 is a non-operating capacitive element 2f that schematically illustrates the stray capacitance in a state where the body B is not detected, and an operation that illustrates the stray capacitance that increases when the body B is detected. A capacitive element 2n is provided.

  The first rectification unit 11 and the second rectification unit 12 in FIG. 2B are composed of elements having the same value, and the output resistance element 11a of the detection electrode 1 and the output resistance element 12a of the reference electrode 2 respectively. Rectifying elements 11b, 12b for half-end rectification, resistance elements 11c, 12c and capacitance elements 11d, 12d for smoothing, resistance elements 11e, 12e and capacitance element 11f for smoothing the second stage for noise prevention, 12f.

  2B includes nothing on the output side of the first rectification unit 11 and includes a resistance element 13a between the output side of the second rectification unit 12 and GND. As a result, in a non-operating state, the output voltage via the first rectifier 11 becomes higher than the output voltage via the second rectifier 12 by a predetermined value. The comparison unit 14 includes a comparison element 14a, and the output of the first rectification unit 11 is input to the negative input terminal of the comparison element 14a, and the output of the second rectification unit 12 is a resistance to the positive input terminal of the comparison element 14a. It is input via the element 13a. Accordingly, in the non-operating state, the voltage at the − side input terminal is higher than the voltage at the + side input terminal, so that the comparison element 14a has a low level signal (hereinafter, the low level signal is denoted as L and the high signal is denoted as H). Is output. The L signal is a determination signal that the body is not detected, and the signal H is a determination signal that the body is detected.

  Next, the outline | summary of operation | movement of the bed sensor 101 of 1st Embodiment is demonstrated. First, a non-operating state in which the body B has left the bed and the bed sensor 101 has not detected the body B will be described. In FIG. 2B, the high frequency generator 8 oscillates at a predetermined frequency, and is composed of the detection electrode 1 and the reference electrode 2 through the first impedance element 9 and the second impedance element 10 having the same value, respectively. Power is supplied to the feeding points 1c and 2c of the stray capacitance.

  It should be noted that the working capacitive element 1n and the working capacitive element 2n shown in FIG. 2B illustrate stray capacitances detected by the body B, and are ignored here because they do not exist during non-operation. Here, each electrode shape of the detection electrode 1 and the reference electrode 2 is formed to be substantially equal, and each electrode is formed at a close distance of the same portion of the bed sensor 101. Therefore, the non-operating capacitive element of the detection electrode 1 The stray capacitance of 1f and the stray capacitance of the non-operation capacitive element 2f of the reference electrode 2 are substantially equal. Therefore, the applied voltage waveforms observed at the feeding points 1c and 2c are the stray capacitances of the non-operating capacitive elements 1f and 2f constituted by the impedance elements 9 and 10, the detection electrode 1 and the reference electrode 2, respectively. The waveform of each applied voltage is substantially equal.

  In this way, substantially equal voltages are input to the first rectifying unit 11 and the second rectifying unit 12. Since the first rectification unit 11 and the second rectification unit 12 are configured with the same element having the same value, the output voltages 11g and 12g of the first rectification unit 11 and the second rectification unit 12 are substantially equal. . If the output voltages 11g and 12g of the first rectification unit 11 and the second rectification unit 12 are input to the comparison element 14a of the comparison unit 14 as they are, the output of the comparison element 14a during non-operation is fixed to L or H. It becomes difficult. Therefore, by reducing the output voltage of the second rectifying unit 12 by a predetermined value by the resistance element 13a of the potential difference unit 13 and then inputting it to the + side input terminal of the comparison element 14a, as shown in FIG. Thus, the output of the comparison element 14a can be fixed to L. The voltage difference due to the resistance element 13a is assumed to be V1.

Next, an operation state in which the body B exists and the bed sensor 101 detects the body B will be described. 2n, which are the operation capacitive elements shown in FIG. 2B, are stray capacitances detected by the body B, and this is expressed by the mathematical formula 1.

  From equation (Equation 1), the capacitance C is inversely proportional to the electrode spacing d if the dielectric constant ε and the electrode area S are constant. Thus, as shown in FIG. 3A, when the body B approaches the bed sensor 101, the distance from the negative electrode 1b (−) of the detection electrode 1 to the positive electrode 1a (+) through the body B is 1da + 1db. On the other hand, the distance from the negative electrode 2b (−) of the reference electrode 2 to the positive electrode 2a (+) through the body B is 2da + 2db. From this, when the body B approaches the bed sensor 101, the stray capacitance 1n of the body B added to the detection electrode 1 with a short apparent electrode interval is a reference with a long apparent electrode interval. It can be seen that the stray capacitance 2n of the body B added to the working electrode 2 is larger. In order to make the electrode area S constant so that the capacitance C is inversely proportional to the electrode interval d, the area of the detection electrode 1 and the area of the reference electrode 2 are equal.

  As described above, when the body B approaches the bed sensor 101 of the first embodiment, the floating capacitance 1n of the body B is added to the capacitance 1f of the detection electrode 1, and the floating capacitance of the body B is added to the capacitance 2f of the reference electrode 2. 2n is added. At this time, since the stray capacitance 1n of the body B added to the detection electrode 1 side is larger than the stray capacitance 2n of the body B added to the reference electrode 2, each impedance element 9 that feeds a high frequency voltage to each electrode, Although the current value of 10 increases, the amount of increase in the high-frequency current flowing on the detection electrode 1 side is greater than the amount of increase in the high-frequency current on the reference electrode 2 side, and the feeding point fed by the first impedance element 9 The applied voltage of the high-frequency voltage 1c is lower than the applied voltage of the high-frequency voltage at the feeding point 2c fed by the second impedance element 10. As a result, the output voltage of the first rectifying unit 11 is lower than the output voltage of the second rectifying unit 12.

  Since the body B approaches the bed sensor 101, the voltage on the detection electrode 1 side input to the comparison element 14a is lower than the voltage on the reference electrode 2 side, and this voltage difference is V2. On the other hand, as described above, in the non-operating state where the body B does not approach the bed sensor 101, the voltage on the detection electrode 1 side input to the comparison element 14a by the resistance element 13a of the potential difference unit 13 is the voltage on the reference electrode 2 side. Is set higher by V1. V1 is constant, but V2 increases as the body B approaches the bed leaving sensor 101. When the body B approaches the bed leaving sensor 101 by a predetermined distance or more, V2> V1, and the output of the comparison element 14a is inverted from L to H. That is, V1 is a detection threshold of the bed leaving sensor 101.

  FIG. 3B shows an operating state in which V2> V1 when the body B of the body X having a high electrostatic capacity and the body B having a low capacity Y is not approaching the bed sensor 101 and the body B approaches the bed sensor 101 by a predetermined distance or more. It is the graph which showed the input voltage to the comparison part 14 when it became.

  In the non-operating state, since there is no capacitance due to the approach of the body B, the input voltage (X1, Y1) to the comparison element 14a on the detection electrode 1 side is the reference electrode for both the high constitution X and the low constitution Y. It is higher than the input voltage (X2, Y2) of 2 by V1.

  In the operating state, the constitution X has a larger capacitance due to the approach of the body B than the constitution Y, so the input voltage to the comparison element 14a is the constitution X (X1, X2) than the constitution Y (Y1, Y2). Will be lower. However, since the detection electrode 1 and the reference electrode 2 that are close to each other are equally affected by the constitution, V2> V1, and both the constitution H and the constitution L go to the comparison unit 14 on the detection electrode 1 side. Input voltage (X1, Y1) becomes lower than the input voltage (X2, Y2) of the reference electrode 2, and the output of the comparison element 14a is inverted from L to H.

  In this way, the bed leaving sensor 101 of the present invention uses one capacitance electrode 1 for detection and the other adjacent capacitance electrode 2 as a reference, according to the difference in capacitance in the same environment. The presence detection signal is output. For this reason, even if the capacitance of one capacitance electrode 1 changes with temperature, humidity, etc., the other capacitance electrode 2 also changes with temperature, humidity, etc. Unaffected by changes in temperature and humidity. In addition, the capacitance changes depending on the constitution and physical condition of the body B, but the bed sensor 101 of the present invention changes both the capacitances of the capacitance electrodes 1 and 2 even if the constitution and physical condition change. Unaffected by changes in constitution or physical condition. Thus, since the influence of the environment and the constitution and physical condition of the body B is small, the presence or absence of the body B on the bedding can be detected with high sensitivity.

  Therefore, the bed leaving sensor 101 of the present invention can be installed under the mat 50b separated from the body B, and a foot slightly lifted by placing a futon or the like can be detected. In addition, the bed leaving sensor 101 of the present invention is an inexpensive capacitive sensor, and is therefore cheaper than non-contact detection sensors such as photoelectric sensors, beam sensors, heat ray sensors, and ultrasonic sensors. In addition, since it is not carried by the nurse like the tag sensor, it does not give the body B a sense of restraint or discomfort due to carrying.

  Moreover, since the detection sensor 1 and the reference electrode 2 are provided so as to overlap each other in a direction perpendicular to the mounting surface, the bed leaving sensor 101 can detect the body B evenly from any direction. Moreover, since the influence of the electrostatic capacitance electrode adjacent to the periphery is canceled by this overlap, malfunction due to mutual interference can be reduced.

  In the bed leaving sensor 101, the spacer 5 is provided between the first base material 3 and the second base material 4. The thickness of the spacer 5 can adjust the difference in capacitance between the first capacitance electrode and the second capacitance electrode. Flexibility is required when the bed leaving sensor 101 is installed in the bendable bed 50 or when cleaning is required. At this time, the substrate should be a flexible FPC (flexible printed circuit board) instead of a hard printed circuit board such as 1.6 mm thick glass epoxy. However, since the thickness of the FPC is as thin as about 0.3 mm, the difference in capacitance between the first capacitance electrode and the second capacitance electrode is small. Therefore, the distance between the first capacitance electrode and the second capacitance electrode can be increased by inserting the spacer 5.

  In the above-described embodiment, the first base material 3, the spacer 5, and the second base material 4 are separate bodies, but the present invention is not limited to separate bodies. For example, in the present invention, the first base material 3, the spacer 5, and the second base material 4 are formed using an elastic body such as rubber having a thickness that can secure a sufficient distance between the detection electrode 1 and the reference electrode 2. May be integrated. And this invention can also comprise the bed sensor 101 by forming the electrode 1 for a detection and the electrode 2 for a reference | standard with the pattern by a conductive film etc. on the surface of this elastic body. By using such an integral base material, the present invention can reduce the manufacturing cost of the bed leaving sensor 101.

  In the above-described embodiment, the outputs of the output electrode 1 and the reference electrode 2 shown in FIGS. 2A and 2B are input to the comparison unit 14 via the first rectification unit 11 and the second rectification unit 12, respectively. However, the present invention does not require the first rectifying unit 11 and the second rectifying unit 12 as essential constituent elements, and the wave type outputs of the output electrode 1 and the reference electrode 2 are not rectified, and the comparing unit 14 is not rectified. The comparison unit 14 can compare the levels even if input to.

[Second Embodiment]
Next, the bed leaving sensor 101A of the second embodiment will be described with reference to FIG. FIG. 4 corresponds to FIG. 2A in the bed sensor 101 of the first embodiment. In the bed sensor 101A of the second embodiment, the same reference numerals are given to the same components as those of the bed sensor 101 of the first embodiment, and description thereof is omitted, and the bed sensor 101 of the first embodiment is configured. For the part that is approximated, only the difference is noted by adding the subscript “A” to the reference symbol.

  The bed leaving sensor 101 </ b> A of the second embodiment switches the applied voltage supplied to the detection electrode 1 and the applied voltage supplied to the reference electrode 2 by the gate circuit 15 and inputs the same to the same first rectifier 16. The microprocessor 17 (MPU) compares the voltage on the detection electrode 1 side output from the first rectification unit 16 with the voltage on the reference electrode 2 side, and outputs the resulting signal L or H. Further, the gate circuit 15 is switched. Further, these processes are performed on the plural (n) capacitance elements 101 a while switching the gate circuit 15. Since the microprocessor 17 performs a plurality of processes in this manner, the number of parts and the number of outputs can be reduced and the reliability can be improved.

  Although the first impedance 9 and the second impedance 10 of the first embodiment have the same value, the first impedance 9A and the second impedance 10A of the second embodiment have different values. Due to this impedance difference, in a non-operating state where the body B does not approach the bed sensor 101A, the output voltage of the first rectifier 16 on the detection electrode 1 side is the output of the first rectifier 16 on the reference electrode 2 side. It is higher by V1 than the voltage. That is, the first impedance 9A and the second impedance 10A of the second embodiment serve as the potential difference unit 13 of the first embodiment.

  In the present invention, the potential difference V <b> 1 is generated by the potential difference unit 13 as a detection threshold of the bed sensor 101. The method of providing the potential difference portion 13 is the addition of the resistance element 13a in the first embodiment, and the second embodiment is a method of making the values of the first impedance 9 and the second impedance 10 different, both of which are easy methods. is there. The present invention is not limited to these methods, and the output voltage of the first rectification unit 16 on the detection electrode 1 side can be higher than the output voltage of the first rectification unit 16 on the reference electrode 2 side by a predetermined value V1. Therefore, for example, if the first embodiment is used as a base, the values of the elements of the first rectification unit 11 and the second rectification unit 12 may be different.

[Third Embodiment]
Next, the bed leaving sensor 101B of the third embodiment will be described with reference to FIG. FIG. 5 corresponds to FIG. 3A in the bed sensor 101 of the first embodiment. In the bed sensor 101B of the third embodiment, the same reference numerals are given to the same components as those of the bed sensor 101 of the first embodiment, and description thereof is omitted, and the bed sensor 101 of the first embodiment is configured. For the part that is approximated, only the difference is noted by adding a subscript “B” to the reference symbol.

  As shown in FIG. 5, the bed leaving sensor 101B according to the third embodiment has an exposed surface 7a (reference electrode) of the seventh protective sheet 7B from an exposed surface 6a (surface on the detection electrode 1 side) of the first protective sheet 6B. A plurality of vent holes 18 penetrating to the surface on the second side are provided. The vent hole 18 penetrates the bed leaving sensor 101B, and can be provided in the positive electrodes 1aB, 2aB and the negative electrodes 1bB, 2bB as shown in FIG. 5, or can be provided in a place where there is no electrode. As a method of providing the vent hole 18 in the positive electrodes 1aB and 2aB and the negative electrodes 1bB and 2bB, this electrode may be formed in a mesh shape. Since the air on both sides of the floor sensor 101B can pass through the vent 18, the environment such as the temperature and humidity on both sides of the floor sensor 101B becomes close, and malfunction due to the difference between the front and back environments of the floor sensor 101B can be reduced. Can do. Further, an increase in humidity of the mat 50b can be reduced.

  Although the bed leaving state determination device 100 of the above-described embodiment is used for the bed 50, the present invention is not limited to use on the bed 50, and can be applied to, for example, a futon laid on a tatami mat. Moreover, although the body B was a nurse, it may be an infant or an infant who needs to observe the in-bed state, or a normal person depending on the case.

DESCRIPTION OF SYMBOLS 100: Bed leaving state determination apparatus 101: Bed leaving sensor 101b: Capacitance element area 1: Detection electrode 1f: Non-operation capacitive element of detection electrode 1n: Operation capacitance element of detection electrode 2: Reference electrode 2f: Reference Electrode non-operating capacitive element 2n: reference electrode working capacitive element 3: first substrate 4: second substrate 5: spacer 6: first protective sheet 7: second protective sheet 9: first 1 impedance element 10: second impedance element 11: first rectification unit 12: second rectification unit 13: potential difference unit 14: comparison unit 15: gate circuit 18: vent 20: determination unit 50b: bed mat M: Plug F: Socket

Claims (5)

A capacitive bed sensor that detects the presence or absence of a body,
A first capacitance electrode formed by a pair of positive and negative electrodes;
A second capacitance electrode provided in the vicinity of the first capacitance electrode and formed by a pair of positive and negative electrodes,
The bed leaving is characterized by outputting a detection signal of the presence of the body according to a difference in capacitance due to a difference in distance between the first capacitance electrode and the second capacitance electrode to the body. Sensor. The first capacitance electrode is disposed on a first substrate;
The second capacitive electrode is disposed on a second substrate;
A spacer is disposed between the first substrate and the second substrate;
The bed leaving sensor according to claim 1, wherein the first capacitance electrode and the second capacitance electrode are provided so as to overlap each other on an attachment surface.   The bed leaving sensor according to claim 1, further comprising a vent hole that penetrates from the surface on the first capacitance electrode side to the surface on the second capacitance electrode side. AC voltage application means for applying a common AC voltage to one of each of the first capacitance electrode and the second capacitance electrode;
A first rectifier that rectifies an applied voltage fed to the first capacitance electrode;
A second rectifier that rectifies the applied voltage fed to the second capacitance electrode;
A comparison unit that compares the potential of the first rectification unit and the potential of the second rectification unit;
The potential of the first rectification unit becomes higher than the potential of the second rectification unit when the body moves away by a predetermined distance, and the potential of the first rectification unit becomes the second rectification when the body approaches a predetermined distance. The floor sensor according to claim 1, further comprising: a potential difference portion whose impedance is set to be lower than a potential of the portion. A first capacitance electrode formed by a pair of positive and negative electrodes, and a second capacitance electrode formed by a pair of positive and negative electrodes provided in the vicinity of the first capacitance electrode. Capacitance for outputting a detection signal for detecting presence / absence of a body in accordance with a difference in capacitance due to a difference in distance between the first capacitance electrode and the second capacitance electrode to the body A bed sensor installed for each of a plurality of detection areas;
A determination unit for determining a bed leaving state based on the detection signal from the capacitance element installed for each of a plurality of detection regions;
A bed leaving state determination device comprising:

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