JPH01135393A - Detector for completed point of drying dry cleaning solvent and circuit for detecting concentration of gas - Google Patents

Abstract

PURPOSE: To improve the operability by incorporating a judging controller, which executes judging of a drying state based on a signal from a gas sensor and the control of a gas sucking means and a display means, in a main body to make a handy type. CONSTITUTION: A gas sucking port 2 is provided at one end opening part of the cylindrical main body 1, the gas sensor 3 and the gas sucking means 4 are arranged behind it and the hand switch 7 of the means 4 is provided at a part being the handle part of the main body 1. A detecting result display means 9 is provided at the handle part and the judging controller (a gas density detecting circuit 21, a comparing circuit 24, a logic part 25, a wait circuit 26, e.g.), which executes judging of the drying state based on the signal from the sensor 3 and the control of the means 4 and the means 9, is incorporated in the main body 1 to make the handy type. As a result, the detector and circuits are excellent in operability and can be handled single handedly.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a gas concentration measurement technique, and particularly to a technique that is effective when used in a device for measuring the residual concentration of dry cleaning solvent in clothing.

[Prior Art and its Problems] Conventionally, the determination of the dryness of the solvent remaining on clothes after dry cleaning has relied on the sense of smell of the operator. Therefore, in order to accurately determine the drying end point, an excellent sense of smell and long experience are required, and the determination results tend to vary from person to person.

Further, dry cleaning solvents are required to have high safety in addition to detergency, and as a result of pursuing such performance, odorless dry cleaning solvents have also been developed.

Therefore, when such an odorless solvent is used for dry cleaning, it becomes extremely difficult to judge the dryness state using the conventional human sense of smell and sense, and many errors occur.

In the field of gas concentration measurement technology, gas leak alarms that detect harmful gases such as LP gas using hot-wire semiconductor sensors and catalytic combustion sensors have been commercialized (1981).
(Nikkei Electronics Books Sensor, November 2, 2015, pp. 329-337).

However, most conventional gas leak alarms are installed type, and are not suitable for use as a drying end point detection device for dry cleaning solvents, which requires good operability. Also,
Some of the conventional gas leak detectors have been commercialized as portable ones, but they are constructed by connecting a rod with a sensor attached to the tip and a main body that has an analog meter, switch, etc., so it can be used with one hand. It is difficult to operate it. Therefore, this type of portable gas detector is also unsuitable for use as a device for detecting the drying end point of dry cleaning solvents.

Furthermore, hot wire semiconductor sensors used for gas detection are
The principle is to use an oxide semiconductor element whose resistance value changes depending on the concentration of atmospheric gas, and to extract the resistance change as a voltage change. It has temperature characteristics as shown by the formula (1/Te l/T).

Therefore, for example, a thermistor has been used to compensate for the temperature of the gas sensor, but the resistance value of the element that becomes the gas sensor varies considerably. Therefore, highly accurate gas concentration detection cannot be performed unless it is possible to adjust the resistance value of the gas sensor as well as temperature compensation.

This invention was made in view of the above-mentioned problems, and its purpose is to provide a handy type dry cleaning solvent drying end point detection device that has excellent operability and can be handled with one hand. It's about doing.

Another object of the present invention is to provide a gas concentration detection circuit that can perform highly accurate gas concentration detection by simultaneously compensating for variations in resistance values of gas sensors and fluctuations in resistance values due to temperature changes.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a gas suction port at one end opening of a cylindrical main body, arranges a gas sensor and a gas suction means behind the gas suction port, and provides a gas suction port at one end of a cylindrical body. A hand switch for the gas suction means is provided in the part that becomes the handle of the shaped body, and a means for displaying the detection results is provided in the handle. A determination control device for controlling the parts is built into the main body.

In addition, a variable resistor is connected in series with the gas sensor, and a transistor is provided to supply an active voltage to the gas sensor, and a thermistor is included, which matches the temperature characteristics of the thermistor with the temperature characteristics of the gas sensor to generate a voltage according to the ambient temperature. A compensation circuit is provided, and the transistor is operated by the output voltage of the temperature compensation circuit to supply the gas sensor with a drive voltage depending on the ambient temperature.

[Operation] According to the above-mentioned means, the sensor section and the display section are integrated, and the hand switch is provided in the handle section, so it can be operated with one hand, and a semiconductor sensor is used. Therefore, the sensitivity is high and the dry state can be detected even with odorless dry cleaning solvents.

In addition, by detecting the ambient temperature with a thermistor and changing the drive voltage applied to the gas sensor according to the ambient temperature, it is possible to compensate for the temperature characteristics of the gas sensor, and also adjust the variable resistor connected in series with the gas sensor. By doing so, it is possible to correct variations in the sensor and output an accurate voltage according to the gas concentration.

[Embodiment] FIG. 1 shows an embodiment of a handy type dry cleaning solvent drying end point detection device according to the present invention.

In the drying end point detection device of this embodiment, a dustproof member 2 having a mesh made of stainless steel is attached to an opening at one end of a cylindrical device main body 1 formed in a dogleg shape as a whole. Inside the device main body 1 behind the dustproof member 2,
A hot-wire type semiconductor gas sensor 3 is disposed, and behind it an eight-blade fan 4 and its driving motor 5 are disposed. When the fan 4 is rotated, air is sucked through the opening to which the dustproof member 2 is attached. The structure is such that the gas sensor 3 can detect the gas quickly.

The air suction amount by the fan 4 is designed to be approximately 0.512/sec. Further, an air discharge port 6 is formed in the upper bent portion of the apparatus main body 1 so that the air sucked by the fan 4 is quickly discharged to the outside.

Note that the gas sensor 3 is attached to the substrate 3a with a thermistor TH as a temperature sensor so as to be located in front of the gas sensor.

Furthermore, in FIG. 1, the cylindrical part of the device main body 1 shown tilted downward to the right is the part that becomes the handle of the device, and has a major diameter of 28 mm so that the operator can grasp and operate it with his/her hand. , and has an oval or elliptical cross section with a minor axis of 32 m.

A hand switch operation button 7 for driving the drive motor 5 of the fan 4 is provided on the front side of the handle 1a.
However, a portion thereof is exposed from the main body 1. This operation button 7 has elasticity, and one end (the lower end in the figure) is fixed to the inner wall of the main body 1, and the other end (the upper end in the figure) is a free end. A microswitch 8 is mounted on the board 1 so as to face the back of the operation button 7.
It is installed on 1.

On the other hand, three transparent members 9a are attached to the upper end of the back surface of the handle portion 1a.
, 9b, 9c attached to the main body 1, and light emitting diodes LEDtt that emit red, yellow, and green light in order from the top corresponding to each transparent member 9a, 9b, 9c. LEDs are mounted on a control board 12 fixed within the main body 1.

The display light emitting diode LED,
~LED, gas sensor 3. A dryness detection circuit as a control circuit that controls the fan drive motor 5 and its power supply circuit (
(not shown) is installed.

In addition, in FIG. 1, the symbol 13 indicates:
This is a transformer that makes up the power supply circuit.

Since the device of this embodiment uses a hot wire type gas sensor having a heater, it uses a commercial power source such as AClooV. Therefore, a power supply circuit having a rectifier circuit is mounted on the substrate 12 along with the transformer 13, but when using a type of gas sensor that does not have a heater, a battery is built in instead of the transformer 13 and the device is powered by the battery. The first
In the illustrated device, an insertion opening 15 for a power supply cord 14 is provided at the lower end of the main body 1 .

The dry cleaning solvent drying end point detection device of the above embodiment has a sensor section and a display section integrated, and is small and lightweight. Lightly touch the clothing, then press operation button 7.
Detection can be easily performed by pressing . In other words, it can be operated with one hand. Therefore, by holding clothing with one hand and operating the device with the other hand, work efficiency can be greatly improved.

Also, because it uses a semiconductor gas sensor.

It has good sensitivity, excellent reliability and durability, and can accurately determine the drying end point even with odorless solvents.
It also has excellent responsiveness as it uses an automatic suction system using a fan. Furthermore, since the drying state is displayed in three stages: red, yellow, and green, even people with no experience or a particularly poor sense of smell can accurately determine the drying end point.

In addition, although the fan is arranged behind the gas sensor in the embodiment, it may be arranged in the opposite direction.

FIG. 2 shows an embodiment of a gas concentration detection circuit that constitutes a part of the determination control device built into the main body of the drying end point detection device.

In the figure, the symbol GS indicates a thermal linear semiconductor type gas sensor, and the heater HT in the sensor is supplied with power at the same time as the power is turned on, and the element is heated to 300 to 400°C. In this heated state, the SnO and crystals inside the device are
It acts as a type semiconductor, and the resistance between terminals A and B changes depending on the gas composition of the atmosphere.

In this embodiment, a transistor TR for supplying an opening voltage to the sensor GS is connected between a power supply voltage vcc and one terminal A of the sensor GS, and a variable resistor VR is connected between the power supply voltage Vcc and one terminal A of the sensor GS. are respectively connected between the other terminal B of the sensor GS and the ground point.

Further, on the base terminal side of the transistor TR, a temperature compensation circuit TC consisting of resistors R1, R, R3 and a thermistor TH is provided. The resistors R8, R,, R3 are
The thermistor TH is connected directly between the power supply voltage Vcc and the ground point GND, and is connected in parallel with the resistor R3. and.

The potential of the ground node n1 of the resistors R1 and R2, that is, the voltage obtained by dividing the power supply voltage Vcc by the ratio of the combined resistance of the resistors R1, R8, R3, and thermistor TH, is applied to the base terminal of the transistor TR via the resistor R4. is being applied. In other words, the temperature characteristics of the thermistor and the temperature characteristics of the gas sensor GS are matched by the resistors R1, R, H□, and the resistance value of the thermistor TH, which changes depending on the ambient temperature, is converted into voltage, and the power is applied to the gas sensor GS. Voltage V
The temperature of the gas sensor GS is compensated by changing cc'(=Vn, -VB) according to the ambient temperature.

Note that Vn is the potential of the node n, and Vet is the base-emitter voltage of the transistor TR, which is about 0.7 V.

A resistor R4 connected between the node ni of the temperature compensation circuit TC and the base terminal of the transistor TR functions to stabilize the impedance of the transistor TR viewed from the node n1. Further, the transistor TR acts as a buffer that keeps the applied voltage constant even if the resistance value of the gas sensor GS changes with temperature.

The temperature characteristics of the resistance value R3 of the gas sensor GS in the above embodiment are as follows.

Since Rs=R11-B.exp (1/T, -1/T), if the resistance value of the variable resistor VR is Rv, the output voltage V out of the gas concentration detection circuit is.

Vout=Vc c' ・Rv/(Rv+Rs)=Vc
c' ・Rv/(Rv+R, ・B −exp(1/T
, -1/T))" (1), and in the above equation, T
o is the absolute temperature of 273° at 0° C., R is the resistance value of the gas sensor at the temperature T0, and B is the coefficient.

Therefore, from the above equation, it can be seen that in order to make the output V out constant regardless of the temperature, it is sufficient to change Vcc. In other words, Vc c' a:1+R0・B−e xp (1/To
-1/T) /Rv by changing Vcc'.

In the circuit of this embodiment, the temperature dependence of V c c ' as described above is controlled by the resistor R constituting the temperature compensation circuit TC,
This can be achieved by appropriately setting the resistance values of R2, R, and thermistor TH.

Furthermore, to make the output Vout constant regardless of variations in the resistance value R of the gas sensor O5.

According to the above formula, the resistance value Rv of the variable resistor VR may be adjusted so that RO/Rv becomes constant.

Furthermore, the resistance value of the gas sensor GS changes depending on the type of gas to be detected. However, even in that case,
The relationship between gas concentration and resistance value is the same, and the lines showing each characteristic are parallel to each other on the graph. Therefore, even when the type of gas to be detected is different, the variable resistor VR
By adjusting the resistance value Rv of the output Vout, it is possible to match the level of the output Vout with the detected concentration.

Next, FIG. 3 shows an embodiment in which the gas concentration detection circuit described above is applied to a determination control device built into a dry cleaning solvent drying end point detection device.

The reference numeral 21 in the figure is the gas concentration detection circuit shown in FIG. 2, and the gas concentration stepping circuit 2.
1 is connected to the power supply circuit 2 via the contact S of the hand switch.
Power supply voltage Vc converted from AC power supply to DC power supply at 0
c is made available for supply. Further, when the hand switch is turned on, power is supplied to a fan drive motor 5 provided in the main body 1 of the apparatus shown in FIG. 1, and the fan 4 is rotated. However, gas concentration detection circuit 2
The heater HT of the gas sensor GS in the gas sensor 1 is supplied with AC power at the same time as the power is turned on, and is heated immediately.

In the embodiment of FIG. 3, the output voltage Vout of the gas concentration detection circuit 21 is connected to a pair of comparators CMP1. CM
P, and is supplied to a comparison circuit 24 having P. The comparators CMP1 and CMP2 in the comparison circuit 24 are provided with two comparison reference voltages Vr, large and small, which are divided by series resistors.
, V r2 is applied.

When the detection output Vout is lower than Vr, high level signals are output from both comparators CMP, , CMP. Moreover, when the detection output Vout is higher than Vr□<lower than Vr2, the comparator CMP
The output of , is low level, CMP.

output becomes high level. Furthermore, the detection output Vout
is higher than Tr, the comparator CMP1. C
The outputs of MP and both become low level.

The output of the comparator CMP is supplied to the base of a drive transistor DR that drives a yellow light emitting diode LED.
The output of is supplied to the base of the drive transistor DR of the green light emitting diode LED□ through the logic section 25.

Here, the gas sensor GS has a lower resistance value as the amount of gas in the atmosphere decreases, so the output Vou of the gas concentration detection circuit 21
The level of t increases as the gas concentration increases, and the level decreases as the gas concentration decreases.

As a result, the detection output Vou of the gas concentration detection circuit 21
When t is lower than the comparison reference value Vr, that is, when the predetermined gas concentration is not reached, green and yellow light emitting diodes L E
D, and LED are lit, and when Vout is higher than Vr and lower than Vr, a yellow light emitting diode L is lit.
ED is lit, and the green LED □ is turned off. In addition,
In either case, the red light emitting diode LEDi is turned on by a signal from the logic section 25.

On the other hand, when the detection output Vout is higher than the comparison reference value Vr, that is, when it is higher than the predetermined gas concentration, the outputs of the comparators CMP and CMP both become low level,
Only the red light emitting diode LED□ is lit.

Furthermore, in this example, the above LED, ~LED,
a transistor TR connected in series with the drive transistors DR, -DR3 between their common collector terminal and the power supply voltage Vcc;

A wait circuit 26 consisting of a CR time constant timer circuit TM supplies current to the transistors DR□ to DR after a certain waiting time (for example, 1 second) has elapsed after the contact S1 is closed by operating the hand switch. supply each LE
D, ~LED, can be driven. The reason for providing the above waiting time is that the gas concentration detection circuit 21 does not immediately output the correct detected value when the hand switch is turned on, and the correct value is not output until about 1 second has passed after the fan starts running. be.

In addition, in the dryness detection circuit of this embodiment, after the power is turned on, it takes more than one minute for the heater HT of the gas sensor GS to rise to a predetermined temperature and the detection ability of the sensor becomes stable, so this unstable period In order to invalidate the CR time constant type timer circuit TM1 is provided. This timer circuit TM outputs a high-level wait signal tw for about 2 minutes after the power is turned on, and the signal is transmitted to the logic section 25.
supplied for. Accordingly, when the power is turned on, the logic section 25 first displays the red light emitting diode LED,
Turn on the drive transistor DR to light the red LED for 2 minutes, then turn off the transistor DR□ and instead turn on the drive transistor DR3 to light the green light emitting diode LED. Form.

Further, in this embodiment, a timer circuit TM, an oscillation circuit 29, and a buzzer 30 are provided to notify by sound that the power has been turned on when the power is turned on. The timer circuit TM is the same as the other timer circuits TM and TM.
It is composed of an R constant type circuit and outputs a high level signal for about 0.2 seconds after the power is turned on.The values of the internal resistance and capacitance are already determined. The output signal of this timer circuit TM is N
○It is supplied to the oscillation circuit 29 via the R gate G and the voltage is 0.
An oscillation signal is output for 2 seconds and a buzzer 3o is sounded.

In addition, in this embodiment, 1 light emitting diode LED1 to LED
, when the display changes from red to green, and when 1 second has passed after the hand switch is turned on.

A trigger pulse generation circuit 27 and a monostable multivibrator 28 are provided to make each buzzer sound. The trigger pulse generation circuit 27 includes the timer TM1.
The signal obtained by inverting the output of the inverter INV and the contact S,
Three signals are input: a signal from the timer TM and a signal from the timer TM. Then, the trigger pulse generation circuit 27 detects the rising edges of these signals from low level to high level, and when any one of the signals rises,
A whisker-shaped trigger pulse TP is generated. This trigger pulse TP activates the monostable multivibrator 28 and stretches the pulse width.

For example, pulses with a width of 0.1 seconds are formed. This pulse is supplied to the oscillation circuit 29 via the NOR gate G1, and by operating it for 0.1 seconds, the buzzer 3
o is configured to sound.

Next, a series of operations in the dryness detection circuit from power-on to detection display will be explained step by step using the flowchart shown in FIG.

First, when you insert the plug at the end of the cord into an outlet and turn on the power to the circuit, the buzzer will sound (step 5).
1) The display by the 1 light emitting diode LED, ~LED becomes lit in red only (step S2), and after 2 minutes, the display by LED1 ~ LED changes from red to lit only in green (step S2). Step S3)
. When the worker turns on the hand switch after seeing this display (step S4), the fan starts rotating.
All LEDs□～LEDs turn off for 1 second (step S5), then 1 light emitting diode LED
Depending on the detected gas concentration, the LED displays one of red only, red and yellow, or red, yellow, and green LEDs (step S6).

This allows the operator to know the dry state.

Thereafter, when the operator turns off the hand switch, the rotation of the fan is stopped, and the display by LED1 to LED returns to only green lighting (step S7), and it becomes possible to move on to the primary detection operation.

FIG. 5 shows another embodiment of the dry cleaning solvent dryness detection circuit using the gas concentration detection circuit shown in FIG.

In this embodiment, the output Vout of the gas concentration detection circuit 21
is input to the LED driver LDR which has a built-in A/D conversion function. Then, the detected gas concentration is 1, for example 12
Which level of the level divided into stages corresponds to LE
Level indicator L-A using an LED array in which 12 light emitting diodes are arranged in a row as judged by the D driver LDR
Outputs a signal to drive RY. As a result, the level indicator L-ARY is configured such that, for example, the higher the gas concentration, the more LEDs are lit, and the detected gas concentration can be displayed in an analog manner.

Note that the series resistance consisting of the variable resistors VR, , VR3 and the resistor R1 can be connected to the LED driver LD by resistance division.
This is a reference voltage generating means that provides an arbitrary reference voltage to the A/D converter or comparator in R.

[Effects of the Invention] As explained above, the present invention provides a gas suction port at one end opening of a cylindrical main body, arranges a gas sensor and a gas suction means behind the gas suction port, and has a handle portion of the cylindrical main body. A determination control device is provided with a hand switch for the gas suction means in a part thereof, and is provided with a detection result display means in the handle part, and determines the dry state based on the signal from the sensor and controls the gas suction means and the display part. is built into the main body, so the sensor section and the display section are integrated.

Also, since a hand switch is provided on the handle, it can be operated with one hand. Furthermore, since a semiconductor sensor is used, the sensitivity is high, and the drying end point can be detected even for odorless dry cleaning solvents.

In addition, a variable resistor is connected in series with the gas sensor, and a transistor is provided to supply a driving voltage to the gas sensor, and the temperature characteristics of the thermistor are matched with those of the gas sensor to initially control the voltage according to the ambient temperature. A temperature compensation circuit is provided, and the output voltage of the temperature compensation circuit operates the transistor to supply the gas sensor with a drive voltage corresponding to one ambient temperature. By changing it accordingly, it is possible to compensate for the temperature characteristics of the gas sensor. By adjusting the variable resistor connected in series with the gas sensor, it is possible to correct sensor variations and output an accurate voltage according to the gas concentration.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional side view showing an embodiment of a drying end point detection device for dry cleaning solvent according to the present invention. FIG. 2 is a circuit diagram showing an embodiment of a gas concentration detection circuit suitable for use in the drying end point detection device, and FIG. 3 is an example of a determination control circuit using the above gas concentration detection circuit. A circuit diagram showing an example. FIG. 4 is a flowchart showing the operating procedure of the dry cleaning solvent drying end point detection device incorporating the circuit. FIG. 5 is a circuit diagram showing another embodiment of the determination control circuit using the above gas concentration detection circuit. 1...Device body, 1a...Handle part, 2...
Dust-proof member, 3...Gas sensor, 4...Gas suction means (fan), 5...Fan IH driving motor, 6
...Air discharge port, 7..Hand switch operation button, 8..Micro switch, 9..Display section. 13...Transformer, O8...Gas sensor, LE
D1~LED3...Light emitting diode, TH...
Thermistor, TC...Temperature compensation circuit, 20...
Power supply circuit, 21...Gas concentration detection circuit, 24...
- Comparison circuit, 25... Logic section, 27... Trigger pulse generation circuit, 2-8... Monostable multivibrator, 29... Oscillation circuit, 30... Buzzer, No. 4 Figure

Claims (8)

[Claims] (1) A gas suction port is provided in the opening at one end of the cylindrical body, and a gas sensor and gas suction means are arranged behind it, and a hand switch for the gas suction means is installed in the part that will become the handle of the cylindrical body. and a means for displaying the detection results on the handle, and a determination control device built into the main body for determining the dry state based on the signal from the sensor and controlling the gas suction means and the display. Features: Dry end point detection device for dry cleaning solvents. (2) The display means is composed of a plurality of color emitting diodes, and is adapted to display the control state of the device and the detected degree of dryness by color. Dry end point detection device for dry cleaning solvents. (3) The display means is composed of a display lamp array in which a plurality of display lamps are arranged in a row, and is configured so that the number of lamps corresponding to the detected gas concentration level is lit from one end. Claim 1 characterized by
A device for detecting the end point of drying of a dry cleaning solvent as described in 2. (4) The dry cleaning solvent according to claim 1, 2, or 3, wherein the display means includes a sounding means for notifying the outside with sound when the control state of the apparatus changes. Drying end point detection device. (5) The cylindrical body has a dogleg shape as a whole, one side thereof is a handle portion, and the other side has a built-in gas sensor and gas suction means. The device for detecting the drying end point of a dry cleaning solvent according to item 1, 2, 3, or 4. (6) a gas sensor, a variable resistance means connected in series with the gas sensor, a transistor for supplying a driving voltage to the gas sensor, and a temperature compensation circuit that includes a temperature detection element and generates a voltage according to the ambient temperature; A gas concentration detection circuit comprising: a gas concentration detection circuit configured to operate the transistor according to the output voltage of the temperature compensation circuit to supply a drive voltage according to the ambient temperature to the gas sensor. (7) The temperature detection element is a thermistor whose resistance value changes depending on the ambient temperature, and the temperature compensation circuit includes a plurality of resistance elements connected in series between power supply voltage terminals, and a plurality of resistance elements of the resistance elements. 7. The gas concentration detection circuit according to claim 6, comprising a thermistor connected in parallel with one of the gas concentration detection circuits. (8) The gas concentration detection circuit according to claim 6 or 7, wherein the gas sensor is a hot wire type semiconductor sensor.