JP6771295B2 - Bed leaving sensor and bed leaving state judgment device - Google Patents

Description

The present invention relates to a bed leaving sensor and a bed leaving state determination device. Specifically, the present invention is a capacitance type bed leaving sensor that detects the presence or absence of a body on a bedding, and is a first capacitance electrode and a second capacitance. The present invention relates to a bed leaving sensor and a bed leaving state determination device that output a detection signal of the presence or state of the body according to a difference in capacitance due to a difference in the distance of the electrodes to the body.

A nurse who has difficulty walking independently may fall out of bed, or may fall while trying to move to a wheelchair on his own or to walk alone. In addition, they may wander around and go missing, or they may not be able to see the doctor at that time because they are out of bed during the consultation time. In addition, it may be delayed to notice that the person is not turning over normally, is moving abnormally when suffering, or is not moving at all. In order to prevent these accidents, prevent wandering, and detect medical conditions at an early stage, a device that detects the presence or absence of the body using various sensors and determines getting out of bed has been conventionally considered.

For example, a device for detecting a load when sleeping by disposing a sensor for detecting the presence or absence of a load as disclosed in Patent Document 1 (Japanese Unexamined Patent Publication No. 2015-8921) on a bed, Patent Document 2 (Japanese Patent Laid-Open No. 2015). Japanese Patent Application Laid-Open No. 2015 (Japanese Patent Laid-Open No. 2012-) In Patent Document 4 (Japanese Unexamined Patent Publication No. 2015-146856), a device for detecting the presence of the body when sleeping by disposing a capacitance type sensor on a bed mat as disclosed in Japanese Patent Application Laid-Open No. 45296. A photoelectric sensor that detects an object according to the reflected light from the object as disclosed, a beam sensor that detects the object according to the presence or absence of reflected light reflected by the reflecting plate, and heat generated by the object. A device that detects getting out of bed by a non-contact detection sensor such as a heat ray sensor that detects an object according to the signal, an ultrasonic sensor that detects the object according to the presence or absence of reflection of an ultrasonic signal, a tag sensor (IC tag), etc. There is a device that detects getting out of bed by carrying a sensing element to the patient.

Japanese Unexamined Patent Publication No. 2015-8921 JP-A-2015-126803 Japanese Unexamined Patent Publication No. 2012-45296 Japanese Unexamined Patent Publication No. 2015-146856 Japanese Unexamined Patent Publication No. 2013-235313

However, the conventional sensor for detecting the body has various problems as a sensor for determining the state of getting out of bed. When the load sensor or capacitance sensor is placed in or under the bedding, the temperature and humidity change depending on the nurse. As a result, the sensitivity of the load sensor and the capacitance sensor changes, causing a malfunction.

In addition, when the load sensor or capacitance sensor is placed under the mat, the distance between the sensor and the human body is greatly increased to reduce the sensitivity, and there are mats of various thicknesses. The effect of changes in humidity and the difference in mat thickness is large.

In addition, differences in physical constitution such as differences in body weight, body temperature, body fat percentage, and degree of sweating affect the sensitivity of load sensors and capacitance sensors, causing malfunctions and reduced sensitivity. Therefore, there is a problem that it is necessary to deal with any constitution.

Further, when the capacitance sensor is used for posture detection, it will be arranged in a plurality of areas such as the chest, waist, buttocks, and feet, but due to mutual interference due to the proximity of the capacitance sensors. There is a problem that malfunction occurs.

In addition, in a device in which a load sensor is placed on the floor near the bed to detect getting out of bed due to the ground contact of the foot, the wire is broken or damaged due to the heavy pressure of the foot of the bed or chair, and the nurse or a visitor is a nurse. There is a problem of erroneous judgment due to stepping on other than, and there is a problem that such a device cannot prevent falling from the bed or detect a medical condition at an early stage.

In addition, malfunction of the bed leaving sensor and the bed leaving state detection device is a serious problem in nursing. Devices that make erroneous judgments are shunned because they impose an extra burden on nurses, and some nursing / nursing facilities discontinue use.

Non-contact detection sensors such as photoelectric sensors, beam sensors, heat ray sensors, and ultrasonic sensors are expensive and therefore cannot be expected to be widely used. Sensing elements such as tag sensors (IC tags) have a problem of giving a feeling of binding and discomfort to the nurse who carries them.

In order to solve the problems peculiar to the bed leaving sensor and the bed leaving state detecting device, the present invention is based on a technique derived from Patent Document 5 (Japanese Unexamined Patent Publication No. 2013-235313), which is the prior application of the inventor. , Reduces malfunctions due to changes in temperature and humidity and mutual interference, extends the non-contact detection distance so that it can be installed under a mat away from the human body, does not have to be carried by the inventor, and is inexpensive. It is an object of the present invention to provide a bed leaving sensor and a bed leaving state determination device.

In order to achieve the above object, the bed leaving sensor of the present invention is a capacitance type bed leaving sensor that detects the presence or absence of a body, and is a first capacitive electrode formed of a pair of positive and negative electrodes, and the first capacitance electrode. It is composed of a second capacitance electrode provided close to the capacitance electrode 1 and formed by a pair of positive and negative electrodes, and the first capacitance electrode and the second capacitance electrode. It is characterized in that a detection signal for the presence or absence of the body is output according to the difference in capacitance due to the difference in the distance to the body.

If there is a difference in the distance between the two electrodes to the body, there will be a difference in their capacitance. The present invention uses one capacitance electrode for detection and the other adjacent capacitance electrode as a reference, and outputs a detection signal for the presence or absence of the body according to the difference in capacitance in the same environment. 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 due to changes in temperature, humidity, etc. Not affected. In addition, the capacitance changes depending on the constitution of the body, but the bed leaving sensor of the present invention is not affected by the change in the constitution because the capacitances of both capacitance electrodes change even if the constitution changes. .. As described above, since the influence of the environment and the physical constitution 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. Further, since the bed leaving sensor of the present invention is an inexpensive capacitance type sensor, it is cheaper than non-contact detection sensors such as photoelectric sensors, beam sensors, heat ray sensors and ultrasonic sensors. In addition, unlike the tag sensor, it is not carried by the nurse, so the nurse does not feel bound or uncomfortable with the mobile phone.

Further, in the bed leaving sensor of the present invention, the first capacitance electrode is arranged on the first base material, the second capacitance electrode is arranged on the second base material, and the first base material is used. A spacer is arranged between the base material 1 and the base material 2, and the first capacitance electrode and the second capacitance electrode are provided so as to overlap each other on the mounting surface. Is preferable.

Thereby, the difference in capacitance between the first capacitance electrode and the second capacitance electrode can be adjusted by the thickness of the spacer. In particular, flexibility is required when the bed leaving sensor is installed on a bendable bed or when cleaning is required, in which case it is not a general printed circuit board such as 1.6 mm thick hard glass epoxy. FPC (Flexible Printed Circuit Board) is preferred. However, since the FPC has a thin thickness of about 0.3 mm, the difference in capacitance between the first capacitance electrode and the second capacitance electrode is small. Therefore, by inserting a spacer, the separation distance between the first capacitance electrode and the second capacitance electrode can be increased. This spacer needs to have an appropriate dielectric constant, and should have excellent flexibility.

Further, in the bed leaving sensor of the present invention, it is preferable to provide a vent that penetrates from the surface of the first capacitance electrode side to the surface of the second capacitance electrode side. This reduces the influence of the environment such as humidity difference and temperature difference. In addition, the increase in humidity of the mat can be reduced.

Further, in the bed leaving sensor of the present invention, the AC voltage applying means for applying a common AC voltage to each one of the first capacitance electrode and the second capacitance electrode, and the first capacitance electrode. A first rectifying unit that rectifies the applied voltage supplied to the capacitance electrode, a second rectifying unit that rectifies the applied voltage supplied to the second capacitance electrode, and the first rectifying unit. The potential of the first rectifying unit becomes higher than the potential of the second rectifying unit when the body moves a predetermined distance from the comparison unit that compares the potential of the second rectifying unit with the potential of the second rectifying unit. It is preferable to include a potential difference portion whose impedance is set so that the potential of the first rectifying unit becomes lower than the potential of the second rectifying unit when the voltage approaches a predetermined distance.

Thereby, the sensitivity of the bed leaving state detection can be easily adjusted by adjusting the impedance of the potential difference portion. Further, it is easy to provide a 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. It may be applied to the capacitance electrode.

Further, in the bed leaving state determination device of the present invention, the first capacitance electrode formed by a pair of positive and negative electrodes and the pair of positive and negative electrodes provided close to the first capacitance electrode are formed. A second capacitance electrode is provided, the first capacitance electrode is disposed on a first substrate, and the second capacitance electrode is disposed on a second substrate. A spacer is arranged between the first base material and the second base material so that the first capacitance electrode and the second capacitance electrode overlap each other on the mounting surface. It is provided and statically outputs a detection signal for detecting the presence or absence of the body according to the difference in capacitance due to the difference in the distance between the first capacitance electrode and the second capacitance electrode to the body. A bed leaving sensor in which the capacitance element is installed in each of the plurality of detection regions and a determination unit for determining the bed leaving state based on the detection signals from the capacitance element installed in each of the plurality of detection regions. It is characterized by being prepared.

Thereby, various out-of-bed states can be determined based on the detection for each detection area. For example, it is possible to determine turning over, getting up, posture before getting out of bed, state of getting out of bed, immobility, and the like.

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 showing a configuration of a main part of the bed leaving sensor of 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 leaving sensor of the first embodiment, and FIG. 3B is a graph showing the input voltage of the bed leaving sensor to the comparator. FIG. 4 is a diagram showing a main part of the operation of the bed leaving sensor of the second embodiment. FIG. 5 is a diagram showing a main part of the operation of the bed leaving sensor of the third embodiment.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the embodiments and drawings, but the embodiments shown below are not intended to limit the present invention to those described herein. The invention can be equally applied to those with various modifications without departing from the technical idea shown in the claims. In each drawing used for the explanation in this specification, in order to make each member recognizable on the drawing, the scale is different for each member, and it is not always actual. It is not displayed in proportion to the dimensions of.

[First Embodiment]
The bed leaving state determination device 100 of the first embodiment of the present invention will be described with reference to FIGS. 1 to 3. The bed leaving state determination device 100 includes a bed leaving sensor 101 and a determination unit 20. The bed leaving sensor 101 is detachable from the determination unit 20 by the plug M of the bed leaving 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 and is laid between the base 50a of the bed 50 and the mat 50b, and detects the presence or absence of the body (nurse) 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 capacitance element 101a of the bed leaving sensor 101 includes a detection electrode 1 composed of a pair of positive electrodes 1a (+) and negative electrode 1b (−), which are first capacitance electrodes. A reference electrode 2 composed of a pair of positive electrodes 2a (+) and negative electrode 2b (-), which are second electrostatic capacitance electrodes, a first base material 3 on which the detection electrode 1 is arranged, and a reference electrode. The second base material 4 on which the 2 is arranged, the spacer 5 that separates the detection electrode 1 and the reference electrode 2 by a predetermined distance, and the first protective sheet 6 that protects both sides of the bed leaving sensor 101 from water or the like. , The second protective sheet 7, 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 in order from the body B side. It is overlapped with the protective sheet 7 of 2.

The first base material 3 and the second base material 4 are soft insulating sheets and are base materials for FPC. 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 not be separate bodies but may be obtained by bending one FPC.

The spacer 5 is preferably made of a material having flexibility, heat insulating properties, and an appropriate dielectric constant such as rubber. Further, as shown in FIG. 3A, the detection electrodes 1 (positive electrode 1a and negative electrode 1b) and the reference electrodes 2 (positive electrode 2a and negative electrode 2b) are provided so as to overlap in the direction perpendicular to the mounting surface and at the same position. Be done.

As described above, the capacitance 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. Formed by 7. Then, as shown in FIG. 1A, the capacitance element 101a has a chest (M1) and its left and right (L1, R1), a waist (M2) and its left and right (L2, R2), and a buttocks (M3), which are detection regions. It is installed in 12 regions 101b of the left and right sides (L3, R3), the foot (M4) and the left and right sides (L4, R4), respectively.

Depending on the presence or absence of the body B in each of these areas, the determination unit 20 can determine the state of being in bed (turning over, getting up, posture before getting out of bed, state of getting out of bed, immobility, etc.). For example, if only the left region L3 of the buttocks or the right region R3 of the buttocks is "Yes", a signal of caution is output to the nursing / nursing room assuming that the body B is sitting on the bed 50 and may get out of bed. As a result, the bed leaving state determination device 100 of the present invention monitors the body B for turning over to prevent pressure sores (bedsores), posture monitoring before getting out of bed to prevent bedsores, and a bed leaving state to prevent wandering and perform medical examinations. Immobility monitoring can be performed for monitoring and early detection of medical conditions.

Then, as shown in FIG. 1A, the bed leaving sensor 101 is provided with a plug P at the end for electrically connecting to the determination unit 20. 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 bend, and if the circuit part is sealed, the durability of sweat from the body B is improved and cleaning is performed. You can also do it.

As shown in the block diagram of FIG. 2A, the bed leaving sensor 101 includes a high frequency generation unit 8 that generates a high frequency, a first impedance element 9 that supplies a high frequency voltage generated from the high frequency generation unit 8 to the detection electrode 1. A second impedance element 10 that feeds the high-frequency voltage generated from the high-frequency generating section 8 to the reference electrode 2, a first rectifying section 11 that rectifies the applied voltage fed to the detection electrode 1, and a reference electrode. The output voltage via the first rectifying unit 11 is larger than the output voltage via the second rectifying unit 12 in the state where the body B is not on the second rectifying unit 12 and the mat 50b that rectify the applied voltage supplied to 2. The potential difference unit 13 that adds a potential difference so as to be higher, and the output voltage via the first rectifying unit 11 output from the potential difference unit 13 and the output voltage via the second rectifying unit 12 output from the potential difference unit 13 are compared. A comparison unit 14 is provided which outputs this as a result of determining the bed leaving state.

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 optimum frequency may be set within a wide range of approximately 100 KHz to several MHz, and 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 dimensions, the dielectric constant of the material (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. It may be appropriately determined by the constant of 7. It is not necessary to have an accurate oscillation frequency, a predetermined high frequency voltage, or the like, and it may be appropriately determined according to the specifications of the bed leaving sensor 101. The impedance values of the first impedance element 9 and the second impedance element 10 are equal. 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 suppress power consumption.

The first detection electrode 1 of FIG. 2B is a non-operating capacitance element 1f that schematically shows a 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. It has a capacitor 1n. Similarly, the first reference electrode 2 is a non-operating capacitance 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. It includes a capacitive element 2n.

The first rectifying unit 11 and the second rectifying unit 12 of FIG. 2B are composed of elements having the same value, and are the resistance element 11a for the output of the detection electrode 1 and the resistance element 12a for the output of the reference electrode 2, respectively. , Rectifying elements 11b and 12b that perform odd rectification, resistance elements 11c and 12c and capacitive elements 11d and 12d that perform smoothing, and resistance elements 11e and 12e and capacitive elements 11f that perform second-stage smoothing for noise prevention. It has 12f.

The potential difference unit 13 of FIG. 2B is provided with a resistance element 13a between the output side of the second rectifying unit 12 and the GND without providing anything on the output side of the first rectifying unit 11. As a result, the output voltage via the first rectifying unit 11 becomes higher than the output voltage via the second rectifying unit 12 by a predetermined value in the non-operating state. The comparison unit 14 includes a comparison element 14a, the output of the first rectifying unit 11 is input to the-side input terminal of the comparison element 14a, and the output of the second rectifying unit 12 resists the + side input terminal of the comparison element 14a. It is input via the element 13a. Therefore, in the non-operating state, the voltage of the-side input terminal is higher than the voltage of the + side input terminal, so that the comparison element 14a is a low-level signal (hereinafter, the low-level signal is referred to as L and the high signal is referred to as H). Is output. The L signal is a signal for determining that the body has not been detected, and the signal H is a signal for determining that the body has been detected.

Next, the outline of the operation of the bed leaving sensor 101 of the first embodiment will be described. First, a non-operating state in which the body B is out of bed and the bed leaving sensor 101 does not detect the body B will be described. In FIG. 2B, the high frequency generating unit 8 oscillates at a predetermined frequency and is composed of the detection electrode 1 and the reference electrode 2 via 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.

Note that the stray capacitance element 1n and the stray capacitance element 2n shown in FIG. 2B illustrate the stray capacitance due to the detection of the body B, and are ignored here because they do not exist during non-operation. Here, the shapes of the detection electrodes 1 and the reference electrodes 2 are formed to be substantially equal, and each electrode is formed at a close distance to the same location of the bed leaving sensor 101. Therefore, the non-operating capacitance element of the detection electrode 1 The stray capacitance of 1f and the stray capacitance of the non-operating capacitance element 2f of the reference electrode 2 are substantially equal. Therefore, each applied voltage waveform observed at the feeding points 1c and 2c is the floating capacitance of the non-operating capacitance elements 1f and 2f composed of the impedance elements 9 and 10, the detection electrode 1 and the reference electrode 2. It is an integrated waveform of, and the waveforms of each applied voltage are 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 rectifying unit 11 and the second rectifying unit 12 have the same element configuration with the same value, the output voltages 11g and 12g of the first rectifying unit 11 and the second rectifying unit 12 are substantially equal. .. If the output voltages 11g and 12g of the first rectifying unit 11 and the second rectifying 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. Becomes difficult. Therefore, as shown in FIG. 3B, the output voltage of the second rectifying unit 12 is reduced by a predetermined value by the resistance element 13a of the potential difference unit 13 and then input to the + side input terminal of the comparison element 14a. The output of the comparison element 14a can be fixed to L. Let V1 be the voltage difference due to the resistance element 13a.

Next, the operating state in which the body B is present and the bed leaving sensor 101 detects the body B will be described. The operating capacitance elements 1n and 2n shown in FIG. 2B are stray capacitances detected by the body B, which are expressed by the mathematical formula of Equation 1.

From the mathematical formula (Equation 1), the capacitance C is inversely proportional to the electrode spacing d if the permittivity ε and the electrode area S are constant. As a result, as shown in FIG. 3A, when the body B approaches the bed leaving sensor 101, the distance from the negative electrode 1b (−) of the detection electrode 1 to the positive electrode 1a (+) via 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 (+) via the body B is 2da + 2db. From this, when the body B approaches the bed leaving sensor 101, the stray capacitance 1n of the body B added to the detection electrode 1 having a short apparent electrode spacing is a reference for a longer apparent electrode spacing. It can be seen that the stray capacitance of the body B added to the electrode 2 is larger than the stray capacitance 2n. In order to keep the electrode area S constant so that the capacitance C is inversely proportional to the electrode spacing 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 leaving sensor 101 of the first embodiment, the stray capacitance 1n of the body B is added to the capacitance 1f of the detection electrode 1, and the stray capacitance of the body B is added to the capacitance 2f of the reference electrode 2. 2n is added. At this time, since the floating capacity 1n of the body B added to the detection electrode 1 side is larger than the floating capacity 2n of the body B added to the reference electrode 2, each impedance element 9 for supplying a high frequency voltage to each electrode, Although the current values of 10 increase together, the increase in the high-voltage current flowing on the detection electrode 1 side is larger than the increase in the high-voltage 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 of 1c is lower than the applied voltage of the high frequency voltage of the feeding point 2c fed by the second impedance element 10. As a result, the output voltage of the first rectifying unit 11 becomes lower than the output voltage of the second rectifying unit 12.

As the body B approaches the bed leaving 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 defined as V2. On the other hand, as described above, in the non-operating state in which the body B does not approach the bed leaving 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 portion 13 is the voltage on the reference electrode 2 side. It is set higher by V1 than. V1 is constant, but V2 increases as the body B approaches the bed leaving sensor 101. Then, 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 threshold value for detection of the bed leaving sensor 101.

FIG. 3B shows an operating state of V2> V1 when the body B of the constitution X having a high capacitance and the body B of the constitution Y having a low capacitance do not approach the bed leaving sensor 101 and the body B approaches the bed leaving sensor 101 by a predetermined distance or more. It is a 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 of 2 (X2, Y2) by the amount of V1.

In the operating state, the capacitance of the constitution X due to the approach of the body B is larger than that of the constitution Y, so that the input voltage to the comparison element 14a is larger than that of the constitution Y (Y1, Y2). Is 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. The input voltage (X1, Y1) of the reference electrode 2 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.

As described above, the bed leaving sensor 101 of the present invention uses one capacitance electrode 1 as a reference 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., so that in the detection of the body B, Not affected by changes in temperature and humidity. Further, the capacitance changes depending on the constitution and physical condition of the body B, but the bed leaving sensor 101 of the present invention changes the capacitances of both capacitance electrodes 1 and 2 even if the constitution and physical condition change. , Not affected by changes in constitution or physical condition. As described above, 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 the slightly lifted foot can be detected by placing a futon or the like. Further, since the bed leaving sensor 101 of the present invention is an inexpensive capacitive sensor, it is inexpensive as compared with non-contact detection sensors such as a photoelectric sensor, a beam sensor, a heat ray sensor, and an ultrasonic sensor. Further, unlike the tag sensor, it is not carried by the nurse, so that the body B does not feel bound or uncomfortable due to the carrying.

Further, since the bed leaving sensor 101 is provided with the detection electrode 1 and the reference electrode 2 overlapping in the direction perpendicular to the mounting surface, the body B can be evenly detected from any direction. Further, since the influence of the capacitance electrodes adjacent to the periphery is canceled by this overlap, malfunction due to mutual interference can be reduced.

Further, in the bed leaving sensor 101, a spacer 5 is provided between the first base material 3 and the second base material 4. Then, the difference in capacitance between the first capacitance electrode and the second capacitance electrode can be adjusted by the thickness of the spacer 5. Flexibility is required when the bed leaving sensor 101 is installed on the bendable bed 50 or when cleaning is required. At this time, the base material must be a flexible FPC (flexible printed circuit board) instead of a hard glass epoxy printed circuit board having a thickness of 1.6 mm. However, since the FPC has a thin thickness of about 0.3 mm, the difference in capacitance between the first capacitance electrode and the second capacitance electrode is small. Therefore, by inserting the spacer 5, the separation distance between the first capacitance electrode and the second capacitance electrode can be increased.

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 the separate bodies. For example, in the present invention, the first base material 3, the spacer 5, and the second base material 4 are used by using an elastic body such as rubber having a thickness capable of ensuring a sufficient separation distance between the detection electrode 1 and the reference electrode 2. May be integrated. Then, according to the present invention, the bed leaving sensor 101 can be configured by forming the detection electrode 1 and the reference electrode 2 on the surface of the elastic body in a pattern made of a conductive film or the like. By using such an integrated base material, the present invention can reduce the manufacturing cost of the bed leaving sensor 101.

Further, 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 rectifying unit 11 and the second rectifying unit 12, respectively. However, the present invention does not require the first rectifying unit 11 and the second rectifying unit 12 as essential constituent requirements, and the corrugated output of the output electrode 1 and the reference electrode 2 is not rectified and the comparison unit 14 is used. The comparison unit 14 can compare the levels even if it is 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 leaving sensor 101 of the first embodiment. In the bed leaving sensor 101A of the second embodiment, the same reference reference numerals are given to the parts having the same configuration as the bed leaving sensor 101 of the first embodiment to omit the description, and the bed leaving sensor 101 of the first embodiment is configured. For the parts that are similar to, add the subscript "A" to the reference code and describe only the differences.

The bed leaving sensor 101A of the second embodiment switches between the applied voltage fed to the detection electrode 1 and the applied voltage fed to the reference electrode 2 by the gate circuit 15 and inputs them to the same first rectifying unit 16. The microprocessor 17 (MPU) compares the voltage on the detection electrode 1 side and the voltage on the reference electrode 2 side output from the first rectifying unit 16 and outputs the resulting signal L or H. In addition, the gate circuit 15 is switched. Further, these processes are performed on the plurality of (n) capacitance elements 101a while switching the gate circuit 15. Since the microprocessor 17 performs a plurality of processes in this way, it is possible to reduce the number of parts and the number of outputs and improve the reliability.

The first impedance 9 and the second impedance 10 of the first embodiment have the same impedance value, but the first impedance 9A and the second impedance 10A of the second embodiment have different values of impedance. Due to this impedance difference, the output voltage of the first rectifying unit 16 on the detection electrode 1 side is the output of the first rectifying unit 16 on the reference electrode 2 side in the non-operating state in which the body B does not approach the bed leaving sensor 101A. It is higher than the voltage by V1. That is, the first impedance 9A and the second impedance 10A of the second embodiment play the role of the potential difference portion 13 of the first embodiment.

In the present invention, the potential difference portion 13 generates a potential difference V1 which is a threshold value for detection of the bed leaving 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 method of making the values of the first impedance 9 and the second impedance 10 different in the second embodiment, both of which are easy methods. is there. The present invention is not limited to these methods, and the output voltage of the first rectifying unit 16 on the detection electrode 1 side may be higher than the output voltage of the first rectifying unit 16 on the reference electrode 2 side by a predetermined value V1. Therefore, for example, if the first embodiment is used as the base, the values of the elements of the first rectifying unit 11 and the second rectifying 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 leaving sensor 101 of the first embodiment. In the bed leaving sensor 101B of the third embodiment, the same reference reference numerals are given to the parts having the same configuration as the bed leaving sensor 101 of the first embodiment, and the description thereof is omitted, and the bed leaving sensor 101 of the first embodiment is configured. For the parts that are similar to, add the subscript "B" to the reference code and describe only the differences.

As shown in FIG. 5, the bed leaving sensor 101B of the third embodiment has the exposed surface 6a (surface on the detection electrode 1 side) of the first protective sheet 6B to the exposed surface 7a (reference electrode) of the seventh protective sheet 7B. A plurality of vents 18 that penetrate to the surface on the 2 side) are provided. The vent 18 penetrates the bed leaving sensor 101B, and can be provided in the positive electrodes 1aB and 2aB and the negative electrodes 1bB and 2bB as shown in FIG. 5, and can also be provided in a place where there is no electrode. As a method of providing the vents 18 in the positive electrodes 1aB and 2aB and the negative electrodes 1bB and 2bB, the electrodes may have a mesh shape. Since the air on both sides of the bed leaving sensor 101B can pass through the vent 18, the environment such as temperature and humidity on both sides of the bed leaving sensor 101B becomes close, and malfunction due to the difference between the front and back environments of the bed leaving sensor 101B can be reduced. Can be done. In addition, the humidity rise 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 the use in the bed 50, and can be applied to, for example, a futon laid on a tatami mat. Further, although the body B is a nurse, it may be an infant or an infant who needs to observe the state of being in bed, and in some cases, a healthy person.

100: Bed leaving state determination device 101: Bed leaving sensor 101b: Capacitance element area 1: Detection electrode 1f: Non-operating capacitance element of detection electrode 1n: Operating capacitance element of detection electrode 2: Reference electrode 2f: Reference Non-operating capacitance element of the electrode for reference 2n: Operating capacitance element of the reference electrode 3: First base material 4: Second base material 5: Spacer 6: First protective sheet 7: Second protective sheet 9: Second 1 Impedance element 10: 2nd impedance element 11: 1st rectifying part 12: 2nd rectifying part 13: Potential difference part 14: Comparison part 15: Gate circuit 18: Vent 20: Judgment part 50b: Bed mat M: Plug F: Socket

Claims (3)

It is a capacitance type bed leaving sensor that detects the presence or absence of the body.
A first capacitive electrode formed by a pair of positive and negative electrodes,
It is composed of a second capacitance electrode provided close to the first capacitance electrode and formed by a pair of positive and negative electrodes.
The first capacitive electrode is disposed on the first substrate and
The second capacitive electrode is disposed on the second substrate and
A spacer is arranged between the first base material and the second base material, and the spacer is arranged.
The first capacitance electrode and the second capacitance electrode are provided so as to overlap each other on the mounting surface.
Awakening from bed, characterized in that a detection signal for the presence of the body is output according to the difference in capacitance due to the difference in the distance between the first capacitance electrode and the second capacitance electrode to the body. Sensor. An AC voltage applying means for applying a common AC voltage to each one of the first capacitance electrode and the second capacitance electrode, and
A first rectifying unit that rectifies the applied voltage supplied to the first capacitance electrode, and
A second rectifying unit that rectifies the applied voltage supplied to the second capacitance electrode, and
A comparison unit that compares the potential of the first rectifying unit and the potential of the second rectifying unit, and
When the body moves away from the body by a predetermined distance, the potential of the first rectifying unit becomes higher than the potential of the second rectifying unit, and when the body approaches a predetermined distance, the potential of the first rectifying unit becomes the potential of the second rectifying unit. The bed leaving sensor according to claim 1, further comprising a potential difference portion whose impedance is set so as to be lower than the potential of the portion. A first capacitance electrode formed of a pair of positive and negative electrodes and a second capacitance electrode provided close to the first capacitance electrode and formed of a pair of positive and negative electrodes are provided. , The first capacitance electrode is disposed on the first substrate, the second capacitance electrode is disposed on the second substrate, the first substrate and the second substrate. A spacer is arranged between the base material, and the first capacitance electrode and the second capacitance electrode are provided so as to overlap each other on the mounting surface, and the first capacitance electrode and the first capacitance electrode are provided. Capacitance elements that output a detection signal that detects the presence or absence of the body according to the difference in capacitance due to the difference in the distance of the second capacitance electrode to the body are installed in each of the plurality of detection regions. With the bed leaving sensor
A determination unit that determines the bed leaving state based on the detection signals from the capacitance element installed in each of the plurality of detection areas, and a determination unit.
A device for determining the state of getting out of bed.

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