JP2595435B2 - Seating sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seating sensor for detecting the seating of a person on a toilet seat with a built-in heater provided in a Western style toilet.

[0002]

2. Description of the Related Art Conventionally, a seating sensor for detecting the seating of a person has been used in a Western-style toilet so that an accessory device such as a local washing machine can be operated only while a person is sitting on the toilet seat. . As this kind of seating sensor, a sensor in which a pair of electrodes are arranged on substantially the same plane and a change in capacitance between the two electrodes due to the approach of a human body is used to detect the seating of a person is considered. ing.

[0003] That is, this seating sensor is provided with a detection element 1 having a shape as shown in FIG. 4. The detection element 1 includes an inner electrode 11 and an inner electrode 1.
The outer electrode 1 is formed in a sheet shape in which the outer electrode 12 and the outer electrode 12 which surround the entire outer circumference are arranged on substantially the same plane. Inner electrode 1
1 and the outer electrode 12 are laminated or buried on an insulating base 13. As shown in FIG. 5, the inner electrode 11 is connected to the base of the detection transistor Q, and a rectangular pulse voltage is applied to the outer electrode 12 as a drive signal drv. That is, when the drive signal drv is applied to the outer electrode 12, the inner electrode 11 detects a current corresponding to the rise and fall of the drive signal drv.

When no object is present around the sensing element 1, electric charges are distributed only between the inner electrode 11 and the outer electrode 12, as shown in FIG. On the other hand, FIG.
As shown in (b), when the object 10 (the finger is shown in the figure) having a large ground-to-ground capacitance approaches the sensing element 1, a capacitor is formed between the outer electrode 12 and the object. Become. Since this capacitor functions as a bypass capacitor to the ground, the capacitance between the inner electrode 11 and the outer electrode 12 will be smaller than when the object 10 is not present, and when the drive signal drv rises and rises. The current flowing to the base of the transistor Q at the time of falling decreases. Therefore, in the signal to be determined sen, which is the collector output of the transistor Q, the peak value changes as shown in FIGS. 7A and 7B depending on the presence or absence of an object.

[0005] The signal to be determined sen is input to a detection circuit.
The detection circuit stores the reference value obtained based on the peak value of the signal sen at the time of power-on (that is, the peak value of the detected current), and compares the peak value and the reference value of the signal sen thereafter. Perform successive comparisons. That is, the signal to be determined sen is taken out at a constant cycle and compared with the reference value. Also,
When the peak value of the signal to be determined sen is smaller than the reference value, the detection circuit generates a detection signal indicating that the object has approached. If a switch element such as a relay is controlled using this detection signal, the load can be turned on and off.

It is sufficient that at least one sensing element 1 is provided, but it is desirable that a plurality of sensing elements be arranged in a matrix. Each detection element 1 is connected to a detection circuit 2 as shown in FIG. The detection circuit 2 includes a signal processing unit 21 including a microcomputer that applies a drive signal drv to the outer electrode 12. The drive signal drv is a rectangular pulse signal having a period of 25 milliseconds. A transistor Q is connected to the inner electrode 11 of each of the sensing elements 1a and 1b.
Are connected to each other, and a signal to be determined sen is output from the collector of the transistor Q. The signal to be determined sen output from each transistor Q is sequentially taken in via the multiplexer 22. Multiplexer 22
The signal to be determined sen taken through is input to the DC component removing circuit 23 where the DC component is removed, and then amplified by the amplifier circuit 24. The signal to be determined sen is the drive signal
Since the signal is a differential waveform signal generated in response to the rise and fall of drv, the output of the amplifier circuit 24 is input to the peak hold circuit 25, and the peak value of the differential waveform is detected. The signal processor 21 stores a reference value set based on the peak value of the signal to be determined sen when the power is turned on. This reference value is stored in the digital-analog converter 2.
7 to the comparator 26. The comparator 26 converts the peak value of the signal to be determined sen, which is the output of the peak hold circuit 25, into a digital-analog converter 27.
When the peak value of the signal to be determined sen is smaller than the reference value, a detection signal is generated and input to the signal processing unit 21. Here, in a state where the detection signal is not output, the reference value is sequentially updated so as to follow a gradual change in the surrounding environment.

The signal processing section 21 includes a multiplexer 22
It is possible to know which detection element 1 has generated the detection signal by the selection signal sel. Therefore,
When a human body is detected in at least one of the plurality of detection elements 1, a detection signal is output from the signal processing unit 21. Various devices can be controlled by using this detection signal output from the detection circuit 2. Here, the sensing element 1 and the transistor Q are arranged close to each other in order to prevent the influence of external noise, and the transistor Q is attached to the toilet seat together with the sensing element 1.

[0008]

On the other hand, some toilet seats have a built-in heater, and the characteristics of the transistor Q change according to the ambient temperature. Will fluctuate.
As described above, if the level of the signal to be determined sen fluctuates due to the heating of the transistor Q by the heater, erroneous detection occurs in the determination of the person sitting on the toilet seat. That is, in the state where no person is seated on the toilet seat, the reference value, which is the criterion for determining the capacitance, is updated successively. However, when a detection signal is output when a person is seated, the reference value is not updated.Therefore, if the heater temperature is adjusted while the person is seated, the level fluctuation of the signal to be determined sen causes the person to leave the toilet seat. It is not possible to discriminate whether it is due to a change in temperature or a change in the temperature of the heater, and there is a problem that a malfunction may occur.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a seating sensor in which a malfunction does not occur even when a heating temperature of a heater changes when used in a toilet seat having a built-in heater. Is what you do.

[0010]

According to the present invention, in order to achieve the above object, a sensing element in which a pair of electrodes are arranged close to each other on a substantially same plane, and an electric signal corresponding to a capacitance of the sensing element are provided. And a detection circuit that outputs a detection signal based on a change in capacitance between the two electrodes due to the presence of an object in the vicinity of the detection element. In addition, the detection circuit corrects the criterion for the capacitance when outputting the detection signal by using the output of the existing temperature sensor provided on the toilet seat for monitoring the heater temperature.

[0011]

According to the above arrangement, the output of the existing temperature sensor provided on the toilet seat for monitoring the temperature of the heater is used to determine the degree of change in the capacitance set in the detection circuit. Is corrected, the criterion can be corrected so that erroneous detection does not occur even if the temperature of the heater changes, and a malfunction due to a change in the heating temperature by the heater can be prevented. In other words, it may be erroneously determined that a person has left the toilet seat due to temperature adjustment during sitting,
Even if the person moves away from the toilet seat, malfunctions such as erroneous detection that the person is sitting on the toilet seat can be prevented.

[0012]

In this embodiment, as shown in FIG. 1, a heater 4 built in a toilet seat 3 made of a synthetic resin molded product is turned on only while a person is sitting, or a local cleaning device is turned on by a person. An example of use when enabling operation only when the user is sitting is shown. The detection element 1, the detection circuit 2, and the like have the same configuration as that described in the related art. In this embodiment, the output of the thermistor 5 attached to the toilet seat 3 as a temperature sensor is input to the signal processing unit 21, The difference is that the reference value generated from the signal processing unit 21 is corrected according to the output of the thermistor 5.

The toilet seat 3 has a built-in heater 4 over substantially the entire length and a built-in diffusion plate 6 for uniformly dispersing the heat of the heater 4 to the entire toilet seat 3. Thermistor 5
Is provided for monitoring the heating temperature of the heater 4 so that the heater 4 is maintained at the set temperature. The sensing element 1 and the transistor Q are embedded in the toilet seat 3 at a position where the capacitance between the inner electrode 11 and the outer electrode 12 of the sensing element 1 changes when a person is seated. In the present embodiment, the output of the thermistor 5 is
1, and the above-mentioned reference value is corrected.

The signal processing section 21 takes in the output of the transistor Q at a cycle of 25 milliseconds, and when the output level is lower than the reference value for more than 100 milliseconds, it is determined that the person is seated on the toilet seat 3. It has become. If the state exceeding the reference value continues for 200 ms or more, it is determined that the person has left the toilet seat 3. Further, during a period in which it is determined that a person is not sitting on the toilet seat 3, the transistor Q
If the output level is kept substantially constant for 200 milliseconds, the reference value is updated to set that level to the reference value. Therefore, when no person is seated on the toilet seat 3, even if the heating temperature of the heater 4 changes or the ambient temperature changes, the reference value can be updated and the temperature change can be followed. This is because the signal to be determined due to the temperature change of the heater 4 is
This is because the level change of n is slower than the convergence of the reference value.

When a person sitting on the toilet seat 3 is detected based on a change in the level of the signal sen to be determined, the signal processor 21 takes in the output of the thermistor 5 at that time. Here, the relationship between the output of the thermistor 5 and the level of the signal to be determined sen is shown in FIG.
The reference value is adjusted according to the output of the thermistor 5 in a linear relationship as shown in FIG. 3, and thereafter, the reference value is corrected based on the output of the thermistor 5 during sitting. Also, the signal to be determined
The reference value for sen and the output of the thermistor 5 are digitally processed in the signal processing unit 21.
In the illustrated example, when the output of the thermistor 5 changes by eight steps in digital value, the reference value changes by one step. Therefore, in the illustrated example, the reference value is corrected so that the reference value is changed by one step for eight steps of the output of the thermistor 5.

[0016]

As described above, the present invention provides a sensing element in which a pair of electrodes are arranged close to each other on a substantially same plane, a transistor for amplifying an electric signal corresponding to the capacitance of the sensing element, and a sensing element. A detection circuit that outputs a detection signal based on a change in capacitance between the two electrodes due to the presence of an object in the vicinity of the sensor, wherein the detection element and the transistor are attached to a toilet seat with a built-in heater, and the detection circuit has a heater temperature. Is used to correct the criterion for the capacitance when outputting the detection signal using the output of the existing temperature sensor provided on the toilet seat to monitor the temperature of the toilet seat. The output of the existing temperature sensor is diverted to correct the criterion for the degree of change in the capacitance set in the detection circuit. A as it can be also erroneously detected to correct the criterion so as not to cause, there is an advantage that it is possible to prevent malfunction of a change in the heating temperature by the heater. That is, it is possible to prevent erroneous operations such as erroneous determination that a person has left the toilet seat due to temperature adjustment during sitting, and erroneous detection that a person is sitting on the toilet seat even when the person has left the toilet seat. In addition, since the sensing element has a configuration in which a pair of electrodes are arranged on substantially the same plane, the sensing element can be formed to be thin, and there is no mechanical movable part and there is an advantage that there is little aging.

[Brief description of the drawings]

FIGS. 1A and 1B show an embodiment, wherein FIG. 1A is a schematic configuration diagram, and FIG.

FIG. 2 is an operation explanatory diagram of the embodiment.

FIG. 3 is a block circuit diagram showing a basic configuration.

FIG. 4 is a plan view of a detection element used for a basic configuration.

FIG. 5 is a main part circuit diagram of a basic configuration.

FIG. 6 is an explanatory view of the principle of a main part of a basic configuration.

FIG. 7 is an explanatory diagram of an operation of a main part of the basic configuration.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Detection element 2 Detection circuit 3 Toilet seat 4 Heater 5 Thermistor 21 Signal processing part 22 Multiplexer 23 DC component removal circuit 24 Amplification circuit 25 Peak hold circuit 26 Comparator 27 Digital-analog converter

Claims (1)

(57) [Claims] 1. A sensing element in which a pair of electrodes are arranged close to each other on a substantially same plane, a transistor for amplifying an electric signal corresponding to a capacitance of the sensing element, and a detection element for detecting presence of an object near the sensing element. A detection circuit that outputs a detection signal based on a change in capacitance between the two electrodes, wherein the detection element and the transistor are attached to a toilet seat with a built-in heater, and the detection circuit is provided on the toilet seat to monitor the heater temperature. A seating sensor that corrects a criterion for capacitance when outputting a detection signal using an output of an existing temperature sensor.