JPH0461286B2 - - Google Patents

Description

[Detailed description of the invention]

<Technical Field> The present invention relates to a water level notification device for a bathtub. <Background> Bathtubs have a fairly large internal volume, and it takes quite a long time to pour hot water directly from the faucet or from a water heater, hot water storage tank, etc. After pouring hot water, you do kitchen work, etc., so you forget to stop the pouring even though you should have poured the correct amount of water and poured the hot water. There is a possibility that In view of this, water level notification devices for bathtubs that detect when the water level in the bathtub has reached a predetermined level and issue an alarm to notify that water pouring or pouring operation should be stopped are widely used in households. It has reached. <Prior Art> Such a water level notification device for a bathtub includes, for example, a sensor unit that is vertically disposed from the main body of the water level notification device for a bathtub, and water or molten metal that is poured to a water level that immerses a dew condensation sensor or the like built into the sensor unit. There is a device that electronically detects when someone has done this and issues an alarm. The conventional device will be explained in more detail as follows. That is, the bathtub water level notification device is composed of a sensor section 3' installed vertically inside the bathtub, and a bathtub water level notification device main body 2' installed at a predetermined position outside the bathtub, and the two are electrically connected. (See Figure 3). The sensor section 3' has a built-in sensor 32', such as a dew condensation sensor, whose resistance value changes rapidly when immersed in water, and the bathtub water level alarm device main body 2' has an alarm 26, such as a buzzer, etc. ' and sensor 3
It has a built-in amplifier circuit 5' which inputs the terminal voltage of terminal 2' and outputs a signal for driving the alarm. Therefore, when the water level rises by pouring water or hot water into the bathtub 1' and the sensor 32' is immersed in water or hot water, the terminal voltage of the sensor 32' changes rapidly. The amplification circuit 5' amplifies the terminal voltage of the sensor 32', and the alarm 2
6' can be driven to attract the attention of housewives and the like. This allows housewives and the like to timely pour water or stop pouring hot water, thereby eliminating waste of water, hot water, etc. However, in the conventional device, the sensor 32', which is immersed in water, hot water, etc., is constantly energized, and moreover, a commercial AC power source is usually used as the power source for the water level alarm device for a bathtub. There is a risk of electric shock to bathers. In addition, since the structure of the dew condensation sensor is complicated and the strength is not very high, not only does the structure for assembling and holding the dew condensation sensor etc. to the sensor part 3' become complicated, but also the assembly work becomes complicated, and the sensor part as a whole The disadvantage is that it is expensive. Furthermore, if water is poured into the bathtub 1' or droplets generated due to the pouring of hot water adhere to a condensation sensor or the like, the alarm 26' may be activated even though the water level in the bathtub is still low.
There is a drawback that there is a risk of erroneous operation of activating the . <Objective> The object of the present invention is to completely eliminate the risk of electric shock to bathers and the like, and to reliably prevent malfunctions caused by water droplets, dew condensation, etc. <Structure> In order to achieve the above object, the bathtub water level alarm device of the present invention includes a bathtub water level alarm device main body and a sensor section, which are installed at a predetermined position outside the bathtub, which are separately provided, and a water level detection device by the sensor section. The circuit's power supply voltage is applied to a large capacitor charged by a commercial alternating power supply, and the water level detection circuit consists of an input voltage comparison circuit that compares the voltage across the sensor terminals with a reference value, a CR time constant circuit, and a comparator. and an input voltage duration time circuit. Hereinafter, embodiments will be described in detail with reference to the accompanying drawings showing examples. <Example> FIG. 1 is a partially cutaway perspective view showing the installed state of the water level notification device for a bathtub according to the present invention.
and a sensor section 3 provided through a predetermined position of the side wall of the bathtub 1. The bathtub water level notification device body 2 includes a two-circuit set switch 21 that can select between a set state and a reset state, a power switch 22, an LED 23 that indicates the power switch ON state, and a set state that indicates the set state.
It consists of an LED 24, an LED 25 that indicates that the water level in the bathtub 1 has reached a predetermined level, and a buzzer 26 that outputs an alarm sound that indicates that the water level in the bathtub 1 has reached a predetermined level. The sensor section 3 includes a sensor 32 consisting of a pair of electrodes 33, 33, which passes through a hole 31 bored at a predetermined position on the side wall of the bathtub 1 and faces the inside of the bathtub, and a sensor 32 that penetrates the hole 31 in a watertight manner and faces the inside of the bathtub. It consists of a support body 34 that immovably positions a pair of electrodes 33, 33. Then, the bathtub water level notification device main body 2 and the sensor 3
2 are electrically connected by a cable 35. FIG. 2 is an electrical wiring diagram of the water level notification device for a bathtub according to the present invention, which is composed of a power supply circuit 4, a water level detection circuit 5, and a notification control circuit 7. The power supply circuit 4 applies a commercial alternating power supply 41 to the primary winding of the isolation transformer 42 via the power switch 22, and rectifies the secondary winding voltage of the isolation transformer 42 with a diode bridge 43. The DC voltage thus obtained is applied to the LED 23. Further, the rectified DC voltage is stabilized by a three-terminal regulator 44 to obtain a DC voltage VDD for driving the notification control circuit.
Furthermore, the stabilized output voltage of the three-terminal regulator 44 is stepped down to a predetermined voltage determined by the Zener diode 45, and
Large capacity capacitor 4 is connected via normally closed terminals 7 and 47.
Charge 8. Therefore, in the power supply circuit 4, the DC voltage VDD for driving the notification control circuit and the DC voltage VCC for driving the water level detection circuit.

[Voltage between terminals of large capacity diode 48] can be obtained. However, the DC voltage VCC is applied to the water level detection circuit 5 through the normally open terminals of the relay contacts 47, 47, and the water level detection circuit 5 and the commercial alternating current power supply 41 are completely cut off. . The water level detection circuit 5 has the following configuration. That is, while applying a DC voltage VCC to a time constant circuit consisting of a resistor 51 and a capacitor 52, the resistors 53,
Applying DC voltage VCC to the voltage divider circuit consisting of 54,
The voltage at the connection point 55 between the resistor 51 and the capacitor 52 is applied to the non-inverting input terminal of the comparator 57, and the voltage at the connection point 56 between the resistors 53 and 54 is applied to the inverting input terminal of the comparator 57, thereby forming the sensor 32. One electrode 33 is connected to the connection point 55 via a resistor 58, and the other electrode 3
3 is connected to earth GND1. Further, while applying a DC voltage VCC to a time constant circuit consisting of a resistor 60 and a capacitor 61,
DC voltage is applied to the voltage divider circuit consisting of resistors 62 and 63.
VCC is applied, the voltage at the connection point 64 between the resistor 60 and the capacitor 61 is applied to the non-inverting input terminal of the comparator 66, and the voltage at the connection point 65 between the resistors 62 and 63 is applied to the inverting input terminal to the comparator 66. Furthermore, the collector-emitter terminal of a switching transistor 59, which is turned on by the output signal of the comparator 57, is connected in parallel with a capacitor 61. The diode side of a photocoupler 68 is connected to the collector terminal of a switching transistor 67 which is turned on by the output signal of the comparator 66. The notification control circuit 7 is a logic circuit, that is, two
Three flip-flop circuits 71, 72, 73 composed of NAND gates and two
It has two multivibrator circuits 74 and 75 made up of NAND gates, and a buzzer 26. More specifically, the resistor 77 and the first switch 78 of the set switch 21, which is closed when the set state is selected, are connected in series to apply the DC voltage VDD, and the resistor 79 and the first switch 78, which is closed when the reset state is selected, are connected in series. Second switch 80 of set switch 21
The first input terminal of the flip-flop circuit 71 is connected to the connection point 81 between the resistor 77 and the first switch 78, and the second input terminal is connected to the resistor 79 and the second switch 78 in series. By connecting to the connection point 82 with the switch 80, an input circuit is configured, and when the set state is selected, a high level signal is output to the first output terminal of the flip-flop circuit 71, and a low level signal is output to the second output terminal. When the reset state is selected, a low level signal is output to the first output terminal of the flip-flop circuit 71, and a high level signal is output to the second output terminal. The collector terminal of the switching transistor 83 is turned on by the high level signal output from the first output terminal of the flip-flop circuit 71.
In addition to connecting the LED 24, a relay coil 84 for switching and driving the relay contacts 47, 47 is also connected. Therefore, when the set state is selected, the large capacity capacitor 48 can be connected to the water level detection circuit 5, and when the reset state is selected, the large capacity capacitor 48 can be indirectly connected to the commercial alternating current power supply 41. In addition, a DC voltage VDD is applied to the water level abnormality signal circuit, that is, the time constant circuit consisting of a resistor 85 and a capacitor 86.
is applied, a DC voltage VDD is applied to the voltage divider circuit consisting of resistors 87 and 88, and the voltage at the connection point 89 between the resistor 85 and the capacitor 86 is applied to the comparator 9.
1 to the inverting input terminal of resistor 8.
A comparator 91 detects the voltage at a connection point 90 between 7 and 88.
The switching transistor 92 is turned on by a high level signal applied to the non-inverting input terminal of the flip-flop circuit 71 and output from the second output terminal of the flip-flop circuit 71.
The collector emitter terminal of the capacitor 86 is connected in parallel with the capacitor 86. Therefore, when selecting the reset state, the connection point 89
The voltage at the connection point 89 is lower than the voltage at the connection point 90, and the comparator 91 outputs a high level signal. (approximately equal to the required time), and when the voltage becomes higher than the voltage at the connection point 90, the comparator 9
1 outputs a low level signal. Since the output signal of the comparator 91 is applied to the first input terminal of the flip-flop circuit 72 via the capacitor 93, the output signal of the comparator 91 is applied to the first input terminal of the flip-flop circuit 72.
The flip-flop circuit 7 is activated by the low level signal of 1.
Since the connection point 82 between the resistor 79 and the second switch 80 is connected to the second input terminal of the flip-flop circuit 72, the flip-flop circuit 72 is output when the reset state is selected. A high level signal is output from the second output terminal of. The notification operation circuit includes one flip-flop circuit 73 and two multivibrators 74, 7.
Specifically, the output signal from the transistor side of the photocoupler 68 is applied to the first input terminal of the flip-flop circuit 73 by the circuit of 5 and the LED 25, and the connection point 82 between the resistor 79 and the second switch 80 is 2 input terminal, and the flip-flop circuit 73 is activated by a high level signal on the transistor side of the photocoupler 68.
outputs a high level signal to the first output terminal of the flip-flop circuit 73, outputs a low level signal to the second output terminal, and outputs a low level signal to the first output terminal of the flip-flop circuit 73 when the reset state is selected;
A high level signal is output to the second output terminal. Then, an LED 25 is connected to the collector terminal of the switching transistor 94, which is turned on by the high level signal of the first output terminal of the flip-flop circuit 73, so as to visually notify that the water level in the bathtub has reached a predetermined level. I have to. Furthermore, the second flip-flop circuits 72 and 73
The output terminal is connected to the input terminal of the NAND gate 95, the output signal of the NAND gate 95 is applied to the first stage multivibrator 74, and the output signal of the first stage multivibrator 74 is applied to the second stage multivibrator 75. and apply the output signal of the second stage multivibrator 75 to the buzzer 26,
It is designed to visually notify that the water level in the bathtub has reached a predetermined level. The operation of the water level notification device for a bathtub having the above structure is as follows. When the power switch 22 is turned on, the LED 23 is turned on to indicate the energized state, and the large capacity capacitor 48 is charged, completing preparations for the water level notification operation. Therefore, after starting to pour water into the bathtub 1, if the first switch 78 is closed by operating the set switch 21, the water level can be notified as follows. That is, by closing the first switch 78, a high level signal is output from the first output terminal of the flip-flop circuit 71, so that the switching transistor 83 becomes conductive and conducts electricity to the LED 24 and the relay coil 84. Therefore, by switching the relay contacts 47, 47 to the normally open terminal side, the large capacity capacitor 4
8 is applied to the water level detection circuit 5 to enable water level detection operation. When the water level in the bathtub is low, the electrodes 33, 33
Since neither is immersed in water or hot water, the comparator 57 outputs a high level signal, causing the switching transistor 59 to conduct. Therefore, the comparator 66 outputs a low level signal to keep the switching transistor 67 in a cut-off state, and the photocoupler 68 outputs a low level signal. At this time, the first output terminal of the flip-flop circuit 73 outputs a low level signal, and the second output terminal outputs a high level signal, so that the LED 25
is off, the multivibrator circuits 74 and 75 are not activated, and the buzzer 26 is not driven at all, so no alarm is issued. When the water level in the bathtub becomes high and the electrodes 33, 33 are immersed in water or hot water, the capacitor 52
Since the voltage at the node 55 is lower than the voltage at the node 56 by short-circuiting the voltage at the node 56, the comparator 57 outputs a low level signal and the switching transistor 59
to be cut off. After that, resistor 60 and capacitor 6
Since the capacitor 61 is charged with a time constant determined by 1, the voltage at the connection point 64 gradually increases, and when it becomes higher than the voltage at the connection point 65, the comparator 66 outputs a high level signal. Then, the switching transistor 6 is connected by the capacitor 69.
7 is made conductive momentarily and a pulse current is passed through the diode side of the photocoupler 68, so that a high level signal is output to the transistor side of the photocoupler 68. This high level signal is transmitted to the flip-flop circuit 73.
When the voltage is applied to the first input terminal of the flip-flop circuit 73, a high level signal is output to the first output terminal of the flip-flop circuit 73, and a low level signal is output to the second output terminal. In addition to visually notifying that the water level in the bathtub has reached the predetermined level, the buzzer 26 is driven via the multivibrator circuits 74 and 75 to visually notify that the water level in the bathtub has reached the predetermined level. In addition, before the water reaches a predetermined level in the bathtub, the two electrodes 33 may be temporarily short-circuited due to droplets, dew condensation, or the like. In this case, the electrode 3 may be damaged by droplets, dew condensation, etc.
3 and 33 are short-circuited, which causes the comparator 57 to output a low-level signal to cut off the switching transistor 59, and then charge the capacitor 61 with a time constant determined by the resistor 60 and the capacitor 61, and connect it. The voltage at point 64 is connected to point 65
When the voltage becomes higher than the voltage of
There is a possibility that the LED 25 and the buzzer 26 will be energized and a notification will be issued. However, normally droplets rarely remain attached between the electrodes 33 for a long time, and droplets naturally flow down to the electrodes 33, 33.
This eliminates the short circuit between 3 and 33. Then, if the short circuit condition is eliminated, the connection point 55
As the voltage increases, the comparator 57 outputs a high level signal, making the switching transistor 59 conductive and shorting the capacitor 61.
The voltage at the connection point 64 becomes low again, and it is possible to prevent the LED 25 and the buzzer 26 from being energized. In addition, in a state where dew condensation or the like has occurred between the electrodes 33, 33, the resistance value is considerably higher than in a state where the electrodes 33, 33 are immersed in water or hot water (so-called semi-conducting state), and the comparator 57 becomes high. Since the level signal continues to be output, it is possible to prevent the LED 25 and the buzzer 26 from being energized. In the manner described above, false alarms caused by droplets, dew condensation, etc. can be reliably prevented. The above is a description of normal operation. Forgetting to turn on the water or hot water, or the bathtub tap becoming too hot.
If the water level in the bathtub does not reach the specified level even after a long period of time due to a water or hot water leak or a low supply of water or hot water, the water level detection circuit 5
Even if the circuit is configured with a high input impedance circuit such as a CMOS IC to reduce power consumption, there is a risk that the voltage between the terminals of the large-capacity capacitor 48 will decrease, causing malfunction of the water level detection circuit 5. . In such a case, the buzzer 26 can be driven as described below even if the water level in the bathtub has not reached a predetermined level. That is, by selecting the set state, the switching transistor 92 is cut off by the low level signal of the second output terminal of the flip-flop circuit 71, and the time constant determined by the resistor 85 and the capacitor 86 is immediately set in the water level abnormality signal circuit. The capacitor 86 is charged, and the voltage at the connection point 89 is gradually increased. Then, by charging for a predetermined time, the connection point 8
If the voltage at node 9 becomes higher than the voltage at connection point 90,
Comparator 91 outputs a low level signal, causing flip-flop circuit 72 to output a low level signal from its second output terminal. Therefore, the NAND gate 95 can output a high level signal to drive the multivibrators 74 and 75, and the buzzer 26 can output a notification sound. It should be noted that the present invention is not limited to the above-described embodiments, and design changes may be made as appropriate, such as using other sensors whose resistance value decreases dramatically when immersed in water or hot water. <Effects> As described above, the present invention uses a large-capacity capacitor that has been charged by a commercial AC power source as a power source for a water level detection circuit, and also transmits the detection output from the water level detection circuit to an alarm control circuit via a photocoupler. This ensures insulation from other electronic circuits regardless of whether the sensor is on standby or in operation, preventing accidents such as electric shock, and ensuring that the terminal voltage of the sensor is Since a notification is made only when the voltage is below a predetermined voltage and this state continues for a predetermined period of time or more, it is possible to prevent false notifications due to droplets, dew condensation, etc., and other unique effects are achieved.

[Brief explanation of drawings]

Fig. 1 is a partially cutaway perspective view showing the installed state of the water level alarm device for a bathtub according to the present invention, Fig. 2 is an electrical wiring diagram thereof,
FIG. 3 is a schematic configuration diagram showing a conventional example. 1... Bathtub, 2... Bathtub water level notification device body,
3... Sensor section, 4... Power supply circuit, 5... Water level detection circuit, 7... Notification control circuit, 21... Set switch, 24, 25... LED, 26... Buzzer,
32...sensor, 33...electrode, 47...relay contact, 48...large capacity capacitor, 57,6
6, 91... Comparator, 59, 67, 92...
...Switching transistor, 60,85...Resistor, 61,86...Capacitor, 64,89...
Connection point, 71, 72, 73... flip-flop circuit, 74, 75... multivibrator circuit,
95...NAND gate.

Claims (1)

[Claims] 1 A sensor consisting of two electrodes whose resistance value changes rapidly when immersed in water or hot water is placed facing inside the bathtub, and the voltage between the terminals as the resistance value of the sensor changes is input. In a water level notification device for a bathtub, the water level notification device for a bathtub is configured to notify the water level by driving a buzzer or other alarm when the voltage between the terminals reaches a predetermined value, and the change in the voltage between the terminals of the sensor is delayed in time. an input voltage comparison circuit that compares the voltage between the terminals of the sensor with a reference voltage using a comparator and indicates the state when the voltage between the terminals of the sensor reaches the reference value;
A water level detection circuit is constituted by a CR time constant circuit that starts a timing operation in response to an output signal from the input voltage comparison circuit, and an input voltage duration circuit made up of a comparator, and an input circuit made of a flip-flop circuit; It has a time constant longer than the required time for water supply, starts timekeeping operation upon receiving a start signal from the input circuit, and issues an abnormal signal when a constant water level notification signal is not output even after the set time limit is reached. It consists of a water level abnormality signal circuit consisting of a CR time constant circuit and a comparator, a flip-flop circuit and a multivibrator, and performs an alarm operation based on the detection output received from the water level detection circuit via a photocoupler and the output from the water level abnormality signal circuit. The notification control circuit is configured by the notification operation circuit to start, and the capacitor is switched to the external power supply and load circuits such as the water level detection circuit and the notification control circuit by operation from the input circuit.
A water level notification device for a bathtub, comprising a power supply circuit configured to supply a secondary power source to a load circuit.