JP2001037822A - Air mat - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effect air-feeding action in a slow cycle. SOLUTION: A switching transistor 54 is controlled by first and second switches S1, S2 which operate according to the expansion and contraction of an air pressure regulating bag having an internal pressure which corresponds to the internal pressure of an air cell. The first contact 49 of the first switch applies a switch driving voltage to the transistor via a time constant circuit 51, and the second contact 55 of the first switch quickly discharges the charging voltage of the capacitor 52 of the time constant circuit. Thereafter, the feed of air to the air cell is continued for a certain period of time determined by a time constant, even after the internal pressure of the air cell has built up beyond the lower limit value of a high pressure area and the first switch turned off, with the result that the driving time of an air pump 7 is prolonged and its cycle becomes slower. If external pressure is applied to the air cell during the feed of air to the air cell and its internal pressure builds up abruptly, the first switch is turned off and the second switch is turned on to quickly discharge the charging voltage of the capacitor of the time constant circuit to stop the air pump.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air mat for preventing bed sores, which is particularly observed in patients who are chronically in bed.

[0002]

2. Description of the Related Art Bedsore refers to localized necrosis of cells in a compression area of a patient's body, mainly a bone ridge, and is caused by inhibition of blood flow to capillaries due to local compression of the body for a long time. Often, and even if it does not cause bedsores,
Pressure and pain are often felt in the prominence of the bone. In order to suppress or reduce this, a structure is widely known in which a plurality of elongated air cells are arranged in a direction perpendicular to the front-rear direction, and the air cells are divided into two groups of air cells which are alternately arranged and supply and exhaust are repeated at a predetermined cycle. (For example, see JP-A-5-8412)
No. 3).

[0003] In order to alternately supply and exhaust two systems of air cells, a rotary valve is often used as disclosed in the above publication. Normally, a rotary valve is provided with a fixed plate having an air introduction hole on its surface and an air supply hole for two systems of air cells, and a rotating body which is overlapped in contact with the fixed plate and has an air distribution groove formed on the contact surface. Be composed. The rotating body is rotated by a motor, and by this rotation, air introduced from the air introduction hole is supplied to and exhausted from the two systems of air cells via the groove at predetermined intervals through the air supply hole.

In the rotary valve having the above structure,
Since air is sent from the introduction hole to the air supply hole through the contact surface between the fixed body and the rotating body, air leakage from this contact surface cannot be completely prevented. In particular, air leakage tends to increase due to wear of the contact surface between the two due to long-term use. The present inventors have solved an air mat having an air switching control structure that solves such a problem and has a small air leak as compared with a rotary valve structure and does not increase the amount of air leak even when used for a long time. A proposal has been made (Japanese Patent Application No. 10-198270). According to the present invention, an airbag having a diaphragm structure communicating with the air cell is built in the control unit, and a supply / exhaust passage is provided in the airbag, and the supply / exhaust passage is opened and closed to control supply / exhaust to the air cell. Things.

[0005]

In the invention of the above-mentioned application, an air pump drive switch is arranged adjacent to the air pressure adjusting bag portion, and the switch is turned on and off by inflation and contraction of the air pressure adjusting bag portion. The driving of the air pump is controlled. That is, a limit switch of a snap structure having a hysteresis characteristic is used as an air pump drive switch, and when the air pressure in the air cell falls to a lower limit in a high pressure range set in advance, the air pump is driven and the air pressure is reduced to this lower limit. When it rises above the value and rises to the upper limit set by the hysteresis characteristic, the air pump stops.

In such a structure, the driving time of the air pump is influenced by the hysteresis characteristic of the limit switch. The hysteresis characteristic varies several times between limit switches of the same product, and may take a certain upper limit. Often not. Therefore, there is a problem that the internal pressure of the air cell cannot be set to a stable pressure. In addition, the snap structure limit switch emits a clicking sound when it is turned on and off, and there is a problem that it is harsh for a sleeping person.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and obtains a stable air pressure without being influenced by the individual characteristics of the limit switch. An object of the present invention is to provide an air mat that does not emit sound.

[0008]

An air mat according to the present invention (Claim 1) comprises an air mat body made of a flexible hollow air cell, an air pump for supplying air to the air cell, and an air pump between the air pump and the air cell. In the air mat having a control unit for controlling the air supply to the air cell, a pressure detection unit for detecting the air pressure of the air cell, and the air pressure of the high pressure region in the pressure detection unit When it is detected that the temperature has dropped to the lower limit,
A first switch that is turned on, an air pump drive switch that drives the air pump, and a time constant circuit provided between the air pump drive switch and the first switch; The ON time of the first switch is set to be longer by the time constant of the time constant circuit.

In this configuration, when the internal pressure of the supply air cell drops to the lower limit of the high pressure range, the first switch is turned on, and then the air pump drive switch is turned on to drive the air pump and supply air to the air cell. Is started. Even if the internal pressure of the air cell rises and the first switch is turned off, the air pump drive switch continues to be on for the time constant time of the delay circuit, and keeps driving the air pump. Therefore, the air supply to the air cell is continued, and the air pump stops after the time set by the time constant elapses. Thus, the time during which the air pump is driven becomes longer, and at the same time, the interval until the time when the air pump is driven next becomes longer.

[0010] In the air mat according to the present invention (claim 2), the second switch which is turned on when the air pressure rises to the upper limit value of the high pressure range by the pressure detecting section, and the second switch. And a discharging circuit for discharging the charging voltage of the time constant circuit when is turned on. In such a configuration, when an external pressure is applied to the air cell during the air supply operation to the air cell, that is, during driving of the air pump, and the internal pressure of the air cell rises rapidly, the first switch is turned on from off, and then the second switch is turned on. Switch on. As a result, the charging voltage of the time constant circuit is discharged through the discharging circuit, the air pump drive switch is turned off, and the air pump stops.

[0011] In the air mat according to the present invention (claim 3), the pressure detecting section is arranged in the control section, and is inflated and contracted in accordance with the air pressure in the door ascel. And the first and second switches are:
The first switch is turned on when the internal pressure of the air pressure adjustment bag section falls below the lower limit of the high pressure range, and operates when the inflation and contraction of the air pressure adjustment bag section is detected. The second switch is turned off when the internal pressure of the air pressure adjusting bag rises above the lower limit of the high pressure range, and is turned on when the internal pressure of the air pressure adjusting bag rises above the upper limit of the high pressure range. And turns off when the internal pressure of the air pressure adjustment bag section falls below the upper limit of the high pressure range.

In such a configuration, when the internal pressure of the air cell falls below the lower limit of the high pressure range, the first switch is turned on to drive the air pump to supply air to the air cell. Turns off. However, the air pump drive switch then remains on for the time constant of the time constant circuit, and air supply is continued. On the other hand, when an external pressure is applied to the air cell during driving of the air pump and the internal pressure of the air cell rises above the upper limit of the high pressure range,
The first switch is turned off, the second switch is turned on, and the charging voltage of the time constant circuit is rapidly discharged through the discharging circuit, the air pump drive switch is turned off, and the air supply operation to the air cell is stopped.

According to the present invention (claim 4), the first
The switch comprises a first contact on the power supply side and a movable contact on the air pump drive switch side, and the second switch comprises a second contact on the ground side and the movable contact, and the first and second contacts An off area is provided therebetween, and the movable contact piece is a contact piece of a sliding structure, and slides on the first contact point, the off area, and the second contact point in accordance with the inflation of the air pressure adjusting bag portion. Things that move.

In this configuration, when the first switch is on, a power supply voltage for turning on the air pump drive switch is applied to the air pump drive switch via the first contact and the movable contact when the movable contact is in the off region. Means that the air pump drive switch is turned off by the self-discharge of the time constant circuit, and when the second switch is on, the charge voltage of the time constant circuit is rapidly discharged through the discharge circuit and turned on by the charge voltage of the time constant circuit. The existing air pump drive switch is turned off. The switching is performed by the sliding movement of the movable contact piece between the first contact point, the OFF region, and the second contact point, and no sound is generated at the time of the switching.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the entire structure of an air mat, 1 is an air mat body, 2a, 2a,... Are a first air cell group consisting of a plurality of elongated flexible hollow air cells, 2b, 2b, 2b.
.. Are second air cell groups having substantially the same shape as the first air cell groups 2a, 2a,. First
And the second air cell group 2a, 2a,..., 2b, 2b,.
As the material for ..., a material obtained by laminating polyvinyl chloride on both sides or one side of a woven fabric such as nylon can be used. Three
a is a first air pipe used for supply and exhaust to the first air cell groups 2a, 2a,..., 3b is a second air cell group 2b, 2
b, the second air pipe used for supplying and exhausting air to and from
And sheets in which the second air cell groups 2a and 2b are stored.
Is a controller, and 6 is a plug for supplying power to the controller 5.

As shown in FIGS. 2 and 3, the controller 5 switches the air pump 7 for discharging air and the air to the first and second air cell groups 2a, 2a,..., 2b, 2b,. A control unit 8 is provided, which is housed in a case 9. 10 is a power switch, 11 is an air pressure adjustment switch composed of a volume switch,
And the second air cell group 2a, 2a,..., 2b, 2b,.
Are adjusted arbitrarily such as hardening or softening according to the user's symptoms, weight, or preference. Reference numeral 12 denotes a neon lamp for displaying when an air leak is detected, which is used as a notifying means. 13a,
13b are first and second air tubes 3a, 3 respectively.
b are the first and second air supply / exhaust openings connected to b.

FIGS. 4 and 5 show the structure of the control unit 8.
Is a motor, and 15 is a disk that is rotationally driven by the motor 14. On the surface of the disk 15, two types of concentric grooves 1 are provided.
6, 17 are engraved in an arc shape at a predetermined angle with respect to the rotation center. Specifically, the angle of the groove 16 with respect to the disk rotation center is 16 degrees, the angle of the groove 17 is 200 degrees,
Both positions are out of alignment. 18 is the motor 14 and the disk 1
5 is a substrate for fixing, and only the disk 15 is rotatably attached to the substrate 18. Reference numeral 19 denotes a mounting hole for the motor 14 and the disk 15, 20A1, 20A2, 20B2, 2
Reference numeral 0B1 denotes a cylindrical hole which is linearly arranged on each side of the hole 19, and two grooves are formed.
These correspond to positions 6 and 17. A1, A2, B2, B
1 denotes these holes 20A1, 20A2, 20B2, 20
One end (disc side) of the pin movably inserted into B1 is formed in a hemispherical shape and is in contact with the disc 15. That is, the rotation of the disk 15 causes the pins A1, A
2, B2 and B1 take two positions: a position where the grooves 16 and 17 are present and a position where they are not present.

Reference numeral 21 denotes a flexible airbag disposed in contact with the substrate 18, formed by welding two flexible films made of PVC (polyvinyl chloride), PU (polyurethane), or the like into a predetermined shape. Have been. This airbag 21
As shown in detail in FIG. 6, the first and second air supply holes 2 communicating with the introduction hole 22 through which air is introduced from the air pump 7 and the first and second air supply and exhaust openings 13a and 13b (FIG. 2).
3a, 23b and first and second exhaust holes 24a, 24b. Inlet hole 22 and first and second air supply holes 23a, 23b
Are conducted through the first and second air supply passages a2 and b2, respectively, and the air introduced from the introduction hole 22 passes through the first and second air supply passages a2 and b2 respectively. Air is supplied to the first and second air supply holes 23a and 23b. The introduction hole 22 and the first and second exhaust holes 24a and 24b are communicated with each other through first and second exhaust passages al and a2, respectively.
Air is exhausted through the exhaust holes 24a and 24b.

The first exhaust path a1, the first air supply path a2, the second air supply path b2, and the second exhaust path b1 are connected to pins A1, A2, B
The width of the passage is set to be approximately the same as or slightly smaller than the diameter of the other end of the pins B2 and B1 and is arranged linearly in the above-mentioned order, and the interval is matched with that of the pins A1, A2, B2 and B1. I have. That is, the pins A1, A2, B
2, B1 are the exhaust passages a1, b1 and the air supply passages a2,
b2, the exhaust passages a1, b1 or the air supply passages a2, b2 are crushed by the pressing of the pins A1, A2, B2, B1 to be in a closed state (air cutoff state), and the other pin A
When the pressing of 1, A2, B2 and B1 is released, the opening state (air circulation state) is established. Here, pins A1, A2, B2, B1
Is open when it is located in the grooves 16 and 17 on the disk 15 and is closed when it is located outside the grooves 16 and 17.

In this configuration, the pins A1, A2, B
2, B1 functions as a pressing body of the airbag 21, and the motor 14 and the disk 15 function as pressing body driving means, and a combination thereof constitutes an opening / closing means. As shown in FIG. 7, the first and second air supply holes 23a and 23b are fixed to the airbag 21, and these are connected to the first and second air supply / exhaust openings 13a and 13b, respectively.

Reference numeral 25 denotes a circular air formed in the air flow passage between the introduction hole 22 of the airbag 21 and the first and second air supply passages a2 and b2 via a zigzag air vibration suppression passage 26. In the pressure adjusting bag section, the degree of inflation changes according to the magnitude of the internal pressure. The air vibration suppression passage 26 has an operation of eliminating small air vibrations such as air discharge vibrations of the pump 7 in the introduction hole 22 and the first and second air supply paths a2 and b2.

Reference numeral 27a denotes a first air supply passage a of the airbag 21.
The first pressure detection bag portion 27b formed between the second air supply passage 2 and the first exhaust passage a1 is a second pressure detection bag portion formed between the second air supply passage b2 and the second exhaust passage b1 of the airbag 21. And the degree of expansion changes in accordance with the magnitude of the internal pressure. The first pressure detection bag 27a is for detecting the air pressure in the first air cell group 2a, and the second pressure detection bag 27b is for detecting the air pressure in the second air cell group 2b. Things.

Referring back to FIGS. 4 and 5, reference numeral 28 denotes a pressure detecting plate, and a shaft 30 at one end thereof is rotatably supported by a support 29 protruding from the inner surface of the case 9. A part of the pressure detection plate 28 is formed in a disk shape, and the disk portion 31 is in contact with the air pressure adjustment bag portion 25, and outside thereof,
A substantially triangular extending portion 32 is formed, and its end is an open end. The distal end of the air pressure adjustment switch 11 is in contact with the approximate center of the disk portion 31, and functions to regulate the movement of the disk portion 31. That is, the disk portion 31 tries to rotate around the shaft 30 by receiving the inflation pressure of the air pressure adjusting bag portion 25, but the air pressure adjusting switch 11 suppresses rotation above a predetermined position.

As shown in FIG. 8, the air pressure adjusting switch 11 has a knob 33 having a volume structure, and a shaft 34 forming the center of the knob 33 is formed with a bolt screw on the right side in FIG. And is screwed to the case 9. A coil spring 35 and a projecting pin 36 elastically supported by the coil spring 35 are mounted in the shaft 34, and the projecting pin 36 constantly elastically presses the disk portion 31. 37 is a rubber ring. For example, when the knob 33 is rotated clockwise, the shaft 34 is screwed into the case 9, so that the coil spring 35 is compressed, the elastic pressing force of the projecting pin 36 is increased, and the internal pressure of the air pressure adjusting bag 25 is reduced. The opposing elastic force increases. Therefore, the rotation width of the pressure detection plate 28 becomes small. 38
Is an auxiliary coil spring for applying a constant elastic pressing force to the pressure detecting plate 28.

Reference numeral 39 denotes a micro switch having a sliding contact structure disposed opposite to the extending portion 32 to detect the pressure in the air pressure adjusting bag portion 25 corresponding to the internal pressure of the air cell.
A first switch S1 (FIG. 13) for detecting when the pressure falls below the lower limit of the high pressure range, and a second switch S1 for detecting this when it rises above the upper limit of the high pressure range.
2 (FIG. 13). That is, when the pressure in the air pressure adjusting bag unit 25 is within the range of the upper limit value and the lower limit value of the high pressure range, both the first and second switches S1 and S2 are in the off state (S0) and exceed the lower limit value. When it is lowered, the bag portion 25 contracts, so that the pressure detection plate 28 rotates counterclockwise about the axis in FIG. As a result, the first switch S1 is turned on, then the micro switch 39 is turned on, the air pump 7 is driven to start supplying air to the air cell, and the pressure in the air pressure adjusting bag unit 25 rises above the lower limit value. Then, the pressure detecting plate 28 turns rightward in the clockwise direction, and turns off the first switch S1.

Thus, the air pressure adjusting switch 1
Based on the air pressure (lower limit of the high pressure range) set in step 1, the micro switch 39 operates to maintain this value. The set pressure of the air is variably controlled by the rotation of the knob 33. The air pressure adjustment switch 11 arbitrarily variably adjusts the lower limit of the high pressure range of the air cell, and functions as expansion control means.

On the other hand, at the time of air supply to the air cell, if the pressure rises sharply due to external pressure applied to the air cell and the pressure in the air pressure adjusting bag section 25 exceeds the upper limit of the high pressure range, Due to the further inflation of the air pressure adjusting bag unit 25, the pressure detection plate 28 further rotates clockwise to turn on the second switch S2. As a result, the transistor 54 (FIG. 10) constituting the air pump driving switch is turned off, and the driving of the air pump 7 is stopped.

Numeral 40 is opposite to the pins A1, A2, B1, B2 relative to the portions of the airbag 21 where the first and second air supply passages a2, b2 and the first and second exhaust passages a1, b1 are located. A soft rubber plate arranged on the side is fixed to a protruding portion 41 formed on the inner surface of the case 9. This rubber plate 40
Are elastically receiving the pressing force of the pins A1, A2, B1, B2. The pins A1, A2, B1, B2 and the rubber plate 4
0 to protect the airbag 21 by elastically sandwiching the same, and at the same time, completely close the first and second air supply passages a2, b2 and the first and second exhaust passages a1, b1. To act. FIG. 9 shows a schematic cross-sectional structure of this part, in which four pins A1, A2, B1, B2 are driven by a disk 15 in the left-right direction in the figure, and the first and second air supply paths a2,
b2, the first and second exhaust paths a1, b1 are pressed or released. In the drawing, reference numeral 42 denotes a screw for fixing the substrate 18 to the projecting portion 41.

43a and 43b are a first and a second, respectively.
These are first and second air leak detection switches, which are limit switches disposed opposite to the pressure detection bag portions 27a and 27b, and are fixed to the inner surface of the case 9. These air leak detection switches 43a, 43b are used when any of the air cells in the first or second air cell group 2a, 2b leaks air, when an accident occurs in the controller 5, or when the air tubes 3a, 3b, etc. The air pressure in the air cell drops abnormally (for example, when the
mmAq), the lamp 12 is turned on to notify the occurrence of an accident.

FIG. 10 shows a circuit diagram of each electric component.
4 is a commercial AC 100V power supply, 45 is a fuse, 7 is an air pump, 10 is a power switch, and 46 is a power switch 10.
Power switch 10 is a neon lamp that lights when
It is built in. 14 is a motor, 43a and 43b are
The first and second air leak detection switches, 47 are neon lamps connected in series with the switches 43a and 43b, and 48 is an AC / DC converter, which receives an AC 100V power supply and obtains an output voltage of DC 5V. is there. S1
Is a first switch including a first contact 49 and a movable contact piece 50, to which an output voltage from the AC / DC converter 48 is applied. Reference numeral 51 denotes a time constant circuit including a capacitor 52 and a resistor 53. The terminal of the movable contact 50 is connected to the base of the switching transistor 54 via the time constant circuit 51. S2 is a second switch composed of the second contact 55 and the movable contact piece 50.
Are connected to the ground through a resistor 56. The second contact 55 and the resistor 56 constitute a discharge circuit 57,
It functions to discharge the voltage charged in the capacitor 52 of the time constant circuit 51. An off region is provided between the first and second switches S1 and S2. This is indicated by S0.

The transistor 54 connected to the terminal of the movable contact 50 functions as an air pump drive switch. 5
Reference numeral 8 denotes an LED connected between the output terminal of the AC / DC converter 48 and the collector of the transistor 54, and reference numeral 59 denotes a triac connected between the AC power supply 44 and the air pump 7, which is disposed adjacent to the LED 58. The light is turned on. The triac 59 and the LED 58 are called a photo triac, and act as a relay (solid state relay) 60. The time constant of the time constant circuit 51 can be set to about 3 seconds, and the time constant of the discharge circuit 57 can be set to about 1 second, which is shorter than this.

Next, the operation of the control unit 8 will be described with reference to FIGS. 11 and 12 from the time when the first air cell group 2a is in the air supply state and the second air cell group 2b is in the exhaust state. Pin A
1A, B2, and B1, the disk 15 is positioned as shown in FIG. 12A, that is, the first exhaust path a1 is closed, and the first air supply path a2 is opened (the state is shifting from the open state to the closed state, but until the disk 15 is completely closed). Is open), the second air supply path b2 is open, and the second exhaust path b1 is closed. In this case, the first and second air cell groups 2a,
Air supply is started at 2b. With this air supply, the first and second
When the internal pressure of the air cells of the air cell groups 2a and 2b rises and reaches the pressure set by the air pressure adjustment switch 11,
When the air pressure adjusting bag 25 expands, the first switch S
1 turns off, then the switching transistor 54 turns off, and the air supply operation stops.

Thereafter, the rotation of the disk 15 opens the first exhaust path a1, closes the first air supply path a2, opens the second air supply path b2,
The second exhaust path b1 is closed, the first air cell group 2a is exhausted, and the air in the second air cell group 2b maintains a high pressure state (FIG. 12B).

Since the length of the groove 16 is small, the first exhaust path a
1 is closed after a short time (after about 40 seconds), and the first air cell group 2a is maintained at a predetermined low pressure state. At this time, the high pressure state of the second air cell group 2b is similarly maintained (FIG. 1).
2C). The time for maintaining this state is arbitrarily set by the rotation speed of the motor 14, and can be set to, for example, a high pressure state time of 11 minutes and a low pressure state time of 9 minutes.

During a period when the second air cell group 2b is in a high pressure state (a period shown in FIG. 12C), the second air cell group 2b
When the internal pressure decreases, the first switch S1 turns on, the switching transistor 54 turns on, and the second switch S1 turns on.
Air is supplied to the air cell group 2b. When the internal pressure reaches a predetermined value due to air supply, the first switch S1 is turned off,
Thereafter, the switching transistor 54 is turned off. This air pump driving time is indicated by a waveform P. Air cell group 2
Completely sealing the air flow passages such as the air tubes 3a and 3b, such as the air tubes a and 2b, is not practically employed due to the necessity of a complicated structure, and often causes slight air leakage over time. Therefore, it is necessary to supply air in order to maintain a predetermined high pressure state. Actually, the pump driving time at this time is about 3 to 4 seconds. Thus, the high pressure state is maintained at a constant value while being replenished throughout the entire period.

After about 10 minutes, the rotation of the disk 15 causes the first exhaust path a1 to close, the first air supply path a2 to open, the second air supply path b2 to open, and the second exhaust path b1 to close (FIG. 12D). . Thus, the first and second air cell groups 2a and 2b communicate with each other,
The air in the air cell group 2b flows toward the first air cell group 2a, and the internal pressure of the second air cell group 2a decreases. As a result, the first switch S1 is turned on, the transistor 54 is subsequently turned on, and air supply to the first and second air cell groups 2a and 2b is started, and the internal pressure of both air cell groups 2a and 2b falls to the lower limit of the high pressure range. When it reaches, the first switch S1 is turned off, then the transistor 54 is turned off, and the air supply operation stops.
It takes about 30 seconds until the supply state is completed.

Subsequently, the first exhaust path a1 is closed, and the first air supply path a
The second air supply path b2 is closed, and the second exhaust path b1 is opened (FIG. 12E). Thus, the first air cell group 2a is maintained at a predetermined high pressure state, the second air cell group 2b is evacuated for a short time, and then maintained at a low pressure (FIG. 12F). In the first air cell group 2a, when the internal pressure is reduced due to air leakage during the high pressure period, air is supplied in the same manner as in the second air cell group 2b during the period shown in FIG.
The high pressure state is maintained. Actually, such an air supply operation is 1
It is about 1 to 2 times in one period of one minute. This operation is repeated, and the first and second air cell groups 2a and 2b alternately supply and exhaust air.

The lower limit of the air pressure in the high pressure range is about 250 mm
Aq is set in the range of Aq to 600 mmAq.
The feel is soft at 50 mmAq and hard at about 600 mmAq. These values are arbitrarily set for the user according to the symptoms and preferences, but can also be set according to the weight. In this case, a person with a light weight is used in a soft state, and a person with a heavy weight is used in a hard state. The air pressure adjustment switch 11 displays the pressure value or the weight as described above. The internal pressure (low pressure) in the exhaust state is set by adjusting the exhaust time. In the case of the above example, when the exhaust time is set to about 40 seconds, 150 mmAq (when exhausting from high pressure 250 mmAq) to 200 mmAq (high pressure 600 mm
(When exhausted from Aq).

FIG. 13 shows the first and second switches S1, S
2. The operation of the time constant circuit 51 and the discharge circuit 57 will be described with reference to the circuit diagram of FIG. If the air pressure of the air cell decreases and drops below the lower limit of the high pressure range, measure 1
When the switch S1 is turned on, the DC voltage from the AC / DC converter 48 is applied to and charges the capacitor 52, and at the same time, the transistor 54 is turned on, and the LED 58 emits light. The phototriac 59 is turned on by the light emission of the LED 58, the AC power supply 44 is applied to the air pump 7, and the air pump 7 is driven. When the internal pressure of the air cell rises above the lower limit value due to the air supply to the air cell, the movable contact piece 50 is rotated by the expansion of the air pressure adjusting bag section 25, the first switch S1 is turned off, and the AC / DC converter 48 is turned off. The supply of the DC voltage from the transistor to the transistor 54 is cut off. However, a charging voltage is applied to the base of the transistor 54 from the capacitor 52 of the time constant circuit 51 via the resistor 53, and the transistor 54 remains on for about 3 seconds, which is the time constant. This time constant is indicated by time t1. Since the first switch S1 does not have the hysteresis characteristic, when the time constant circuit 51 does not exist, the first switch S1 repeatedly turns on and off little by little from the lower limit value, and the transistor 54 also turns on and off accordingly. However, because of the time constant circuit 51, the ON time of the transistor is extended by the time constant.

Next, during the air pump driving period, that is, during the first switch S1 on period and the time constant period after the first switch S1 is turned on, a pressure from the outside such as a person lying on the air mat is applied, and the internal pressure of the air cell exceeds the upper limit value. When the air pressure adjusting bag portion 25 is inflated, the movable contact piece 50 moves from the first switch S1 to the second
It turns to the switch S2 within a short time, and the second switch S
2 is turned on. As a result, the charged voltage of the capacitor 52 is rapidly discharged (about 1 second or less) through the second contact 55 and the resistor 56. The time constant of this discharge circuit 57 is set to time t
Shown at 2. This discharge circuit 57 is provided because, even though the internal pressure of the air cell is increased due to the application of the external pressure during the supply of the air cell, if the air pump 7 continues to be driven, the air cell cannot withstand the pressure and bursts. This is because there is a danger of an accident occurring. Here, the upper limit of the high pressure range can be set to a value that is higher by about 100 mmAq than the lower limit.

During use of the air mat, the air tube 3
If the air leaks due to an accident such as a, 3b or the like coming off or the air cells of the air cell groups 2a, 2b being broken, and the internal pressure decreases, if it occurs on the first air cell group 2a side, the first air When the leak detection switch 43a occurs on the second air cell group 2b side, the second air leak detection switch 43b is turned on, and the lamp 12 is turned on to notify that an accident has occurred. Note that these switches 43
a and 43b are set to operate at a pressure lower than the internal pressure of the air cell in the exhaust state. This lamp 12
Detects the pressure of the first and second pressure detecting bags 27a and 27b. When the air mat 1 starts to be used, it takes about 15 minutes from the completely exhausted state of the air mat to the completion of air supply.
Lights up for a minute.

[0043]

According to the present invention (claim 1), after the first switch is turned on, the air pump is driven, the internal pressure of the air cell rises above the lower limit of the high pressure range, and the first switch is turned off. However, since the air pump continues to be driven by the time constant of the time constant circuit, the driving time of the air pump becomes longer, and the driving cycle (about 5 minutes) of the air pump becomes longer. If the time constant circuit is not provided, the air pump is driven in small increments every several seconds in response to the ON / OFF of the first switch, so the air pump driving noise may be annoying and shorten the life of the air pump. According to the present invention, such a problem is improved.

According to the present invention (claim 2), when air pressure is supplied to the air cell and the internal pressure of the air cell suddenly rises above the upper limit of the high pressure range due to external pressure applied to the air cell, the first
When the switch is turned off and the second switch is turned on, the charging voltage of the time constant circuit is rapidly discharged, the air pump driving switch is turned off, and the air pump stops. Therefore, despite the high pressure applied to the air cell, there is no danger that the air pump is driven to continue the air supply operation, further increasing the internal pressure of the air cell and causing the air cell to burst.

According to the present invention (claim 3), first,
The second switch can be turned on and off by utilizing inflation and contraction of the airbag, so that the switch structure can be simplified.

Further, according to the present invention (claim 4), the movable contact piece moves while sliding between the first contact point, the off region and the second contact point. In addition, no noise is generated at the time of switching, and a quiet operation sound can be obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view of an air mat according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a controller.

FIG. 3 is a sectional view taken along line III-III of FIG. 2;

FIG. 4 is an exploded perspective view of a control unit.

FIG. 5 is a sectional view taken along line VV of FIG. 4;

FIG. 6 is a plan view of the airbag.

FIG. 7 is a sectional view taken along line VII-VII of FIG. 6;

8 is a sectional view taken along line VIII-VIII in FIG.

FIG. 9 is a sectional view taken along line IX-IX of FIG. 4;

FIG. 10 is a circuit diagram of a control unit.

FIG. 11 is a waveform diagram for explaining the pressure of an air cell, and the opening and closing of an air supply passage and an exhaust passage.

FIG. 12 is a plan view showing a remarkable relationship between an air supply path, an exhaust path, and a disk.

FIG. 13 is a waveform chart for explaining operations of the first and second switches, a time constant circuit, a discharge circuit, and a switching transistor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Air mat body 2a 1st air cell group 2b 2nd air cell group 3a, 3b Air tube 4 sheets 5 Controller 6 Plug 7 Air pump 8 Control part 9 Case 10 Power switch 11 Air pressure adjustment switch 12 Lamp 13a, 13b First and second supply Air opening 14 Motor 15 Disk 16, 17 Groove 18 Substrate 21 Airbag 22 Introducing hole A1, A2, A3, A4 Pin a1 First exhaust path a2 First air supply path b2 Second air supply path b1 Second exhaust path 23a 1st air supply hole 23b 2nd air supply hole 24a 1st exhaust hole 24b 2nd exhaust hole 25 air pressure adjustment bag 28 pressure detection plate 33 knob 39 pump drive switch 49 rubber plate 43a, 43b first and second air leak detection switch 44 AC power supply 48 AC / DC converter 49, 55 First and second contacts 50 Possible Contact piece 51 time constant circuit 54 switching transients capacitor 57 discharge circuit 58 LED 59 Phototriac

Claims (4)

[Claims] An air mat body comprising a flexible hollow air cell, an air pump for supplying air to the air cell,
In an air mat that is interposed between the air pump and the air cell and has a control unit for controlling air supply to the air cell, a pressure detection unit that detects an air pressure of the air cell; When it is detected that the air pressure has dropped to the lower limit of the high pressure range, a first switch that is turned on, an air pump drive switch that drives the air pump, and a switch between the air pump drive switch and the first switch With the provided time constant circuit,
An air mat, wherein an ON time of the air pump disturbance switch is set longer than an ON time of the first switch by a time constant of the time constant circuit. 2. A second switch that is turned on when the air pressure rises to an upper limit value of a high pressure range in the pressure detection unit, and discharges a charging voltage of the time constant circuit when the second switch is turned on. The air mat according to claim 1, further comprising a discharge circuit. 3. The air conditioner according to claim 1, wherein the pressure detecting unit comprises an air pressure adjusting bag disposed in the control unit and inflating and contracting in response to air pressure in the air cell. The first switch is operated by detecting inflation and contraction of the pressure adjustment bag portion. The first switch is turned on when the internal pressure of the air pressure adjustment bag portion falls below a lower limit of a high pressure range, and the first switch is turned on. The second switch is turned off when the internal pressure of the pressure adjustment bag rises above the lower limit of the high pressure range, and the second switch is turned on when the internal pressure of the air pressure adjustment bag rises above the upper limit of the high pressure range. 3. The air mat according to claim 2, wherein the air mat is turned off when the internal pressure of the air pressure adjusting bag section falls below the upper limit of the high pressure range. 4. The first switch comprises a first contact on the power supply side and a movable contact on the air pump drive switch side.
The second switch includes a second contact on the ground side and the movable contact, an off region is provided between the first and second contacts, and the movable contact is a contact having a sliding structure. Yes,
4. The air mat according to claim 3, wherein the air mat slides on the first contact point, the off area, and the second contact point in response to the inflation of the air pressure adjusting bag.