WO1980001839A1

WO1980001839A1 - Gas concentration detector

Info

Publication number: WO1980001839A1
Application number: PCT/JP1979/000048
Authority: WO
Inventors: K Kato
Original assignee: New Nippon Electric Co; K Kato
Priority date: 1979-02-27
Filing date: 1979-02-27
Publication date: 1980-09-04

Abstract

A gas concentration detector comprising a gas sensor which utilizes a reaction rate accelerating heater to operate a semiconductor element whose resistance varies in response to gas concentration. The detector eliminates both the troublesome operation of switching between preheating and measurement, as well as inaccurate timing by a simplified circuit configuration that achieves gas detecting accuracy by indicating the operating state of the gas sensor via the lighting of a lamp. The voltage supplied from a power source (14) through a control element (16) to the gas sensor (10) is automatically switched from a high voltage application stage to constant voltage application stage through the use of timing elements (17, 18) and a first comparator (20). The former stage is identified by the activation of a first light-emitting element (27) connected to second comparator (26), and the latter stage controls the control element (16) via a voltage detecting circuit including a second light-emitting element (28) operated by the first comparator (20), and a third comparator (31), and is simultaneously identified by the activation of the second light-emitting element (28). A gas detection signal is compared with a reference level by a fourth comparator (36) to thereby judge whether an alarm should be generated or not. The detector is suited for use as a gas alarm or breath tester.

Description

Description Title of the invention

Gas concentration detector Technical field

The present invention relates to a gas concentration detector that measures through a preheating stage, and particularly to a gas alarm or a drinking machine that compares a gas concentration detection signal with a predetermined reference level signal and displays an output signal. The present invention relates to a driving power supply circuit for a gas concentration detector suitable for detection. Background art

In general, it is known that a certain kind of semiconductor substance changes its intrinsic resistance value when it comes into contact with the specified gas molecule.

Can be used to measure gas concentrations.

For example, the surface of an n-type semiconductor SnO.

Adsorbs on the semiconductor surface layer.

Move to the adsorption layer and close to the semiconductor surface

Presents a deficient layer with reduced

On the other hand, the oxygen partial pressure in the atmosphere

Temperature of the semiconductor.

The amount of oxygen and the state of adsorption

O This kind of solidification; ¾ When a reducing gas such as carbon monoxide is introduced, the reducing gas increases the conduction electron density on the semiconductor surface and increases the conductivity of the semiconductor, contrary to the case of oxygen. Therefore, to increase and promote the reaction speed of the semiconductor material, a gas sensitive element that is heated to an appropriate temperature using a heater to accelerate the reaction is used as a gas alarm or an end-of-coil detector. Used in.

However, the above-mentioned practical circuit for gas detection using a gas sensitive body described above is complicated due to problems such as complicated handling operation and inaccurate measurement judgment. It also hindered bright detection. For example, the drunk detector on which the present invention is based is the gas concentration detector of the electric circuit shown in Fig. 1, and the power supply (1) is connected via a two-way switching switch). It is configured by connecting to the gas sensor ( ³ ) and the indicating instrument W that senses in a call. The switching switch ( ² ) forms a different stage circuit when detecting the alcohol gas concentration. That is, when this switch is connected to the upper terminal ( ⁵ ), a relatively high power supply voltage is applied to the gas sensor. It forms a preheating stage for rapid heating. Also, when this switch is connected to the lower terminal ( ⁶ ), the constant voltage circuit ( ⁷ ) is operated at a predetermined output voltage and the gas output is applied to the switch. It forms a measuring stage that drives the sensor ( ³ ). Here, the light emitting diode ( ⁸ ) is provided so as to indicate the preheating stage to which the high voltage is applied, and the operator is provided with the preheating stage. ¾ ¾ 才ををををを

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Such a gas concentration detector would be too confusing and cumbersome to handle and operate; it could be a measurement-judgment; it could easily be misleading and lacked reliability and accuracy. The operator of the detector that detects the gas concentration must first put the switch (2) in the terminal ( ⁵ ) and preheat the heater. In the meantime, it is necessary to hold the preheating period for a predetermined time and check the elapse of that time. At the same time, if the pointer of the indicating instrument ( ⁶ ) is not abnormal, This must be checked, and after this check, the switch must be switched to the measurement stage. The preheating stage connects the gas sensor ( ³ ) to the power supply (1) through a relatively small resistor from the terminal (5), so that the heat of the gas sensor is reduced. Heating the heater quickly and the light emitting diode

-Turn on the indicator (8), and at the same time, connect the indicating instrument ( ⁴ ) to the power source (1) via the high resistance connected between the terminal and the terminal (5). At this time, the indicating instrument (4) causes the pointer to oscillate in a predetermined manner, thereby checking the voltage drop of the power supply (1). However, the pre-determined time for preheating may be switched to the measurement stage by accident or inadvertently, In addition, if the indicator (4) is not confirmed, the measurement circuit may be overlooked.

Invite you.

On the other hand, switching from the preheating stage force to the measurement stage is not only a matter of operation, but also involves the measurement stage.

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WIPO-, t o. Care must be taken in discriminating the measured values along with the confirmation, which is a major obstacle to performing simple, quick and accurate gas detection. Therefore, with the relatively simplified circuit configuration, the preheating and measurement stages described above are automatically switched, each stage is displayed, and the gas detection result is easily and clearly displayed. A gas concentration detector as shown was desired. Disclosure of the invention

The present invention has been proposed in view of the above, and in addition to the automatic switching of the preheating stage and the measuring stage, a display for identifying each stage, for example, The purpose is to provide an improved gas concentration detector with "WAIT" and "READ Y". In addition, a simplified gas concentration detector that enables easy and easy detection of the detector and enables measurement and detection without causing trouble or error in handling. O to provide

According to the present invention, the power supply circuit for operating the gas concentration detector is configured by combining the GR timing element and the comparator with the constant voltage control circuit. Here, the power supply voltage is a high voltage at a predetermined time at the time of start-up, and thereafter, a predetermined voltage controlled by a voltage control circuit is applied to a gas sensitive body as a load. . These different voltage application stages are identified by different emission colors. That is, the high voltage application stage at the initial stage of the startup is the preheating stage. The red light was turned on and displayed as "WAIT", and the light emitting element was used as a power failure display element in the constant voltage application stage. On the other hand, the constant voltage application stage emits green light to indicate that it is ready for measurement, displays "READY", and uses this light emitting device to convert the fluctuation of the output voltage. I also used it.

Another feature of the present invention is to use a gas sensor having a semiconductor element which changes a resistance value in response to a gas concentration and a heater which promotes the sensitivity of the element. ^four co down Roh, to preheat scan tape over di and measurement scan tape over and clearly di. Ru to alarm display the detection determination result is identification of. A circuit is constructed using a data collector, preferably a 4-bit collector integrated circuit, and facilitates accurate detection judgment by simple operation. Is measured. In particular, the detector according to the present invention is economically advantageous because, like the light-emitting display element, the number of circuit components is reduced by using common noise means for each computer. And achieve accurate detection. In addition, when using a battery power supply that cannot be omitted with a portable gas detector, the display element for the preheating stage is used as the battery power. Is also used. Further, a practical detection circuit is provided, for example, to reduce power loss by using a common bias voltage dividing means. Therefore, it is a gas level detector suitable for a drinking detector. Brief description of the drawings

Fig. 1 is an electric circuit diagram of a gas concentration detector on which the present invention is based, and Fig. 2 is an electric circuit diagram showing a block diagram of a basic circuit of the gas concentration detector according to the present invention. And FIG. 3 is a specific electric circuit diagram of the gas intensity detector of FIG. BEST MODE FOR CARRYING OUT THE INVENTION

Figure 2 is Ri Oh professional click manner connection diagram of the engagement Ru gas concentration detector in the present invention, as a gas sensitive body you a combustible gas and detection Ingredient S ii 0 ₂ based semiconductive钵 Using an element (11) and a heater (including an n-type semiconductor gas sensor (10) that keeps the element at an appropriate operating temperature, for example, to prevent drinking accidents. Alcohol detectors that are effective in detecting alcohol consumption are used as combustible gas, not only for alcohol concentration, but also for organic gases and hydrocarbons such as hydrocarbons. It can detect inorganic gas such as carbon oxide, so it can be used as an alarm for household fuel.

This gas concentration detector works as a load sensor for a gas sensor (1 (¾) and an output display (13) that displays the detected output) that converts the detected gas concentration into an electric signal. The power supply circuit is composed of a power supply circuit including 1. The power supply circuit is a control element that supplies the operating voltage to the load circuit via a switch (connected to the power supply ⁴ ). It is composed of a constant voltage circuit including a transistor (-). Here, the gas sensor (10) starts to perform its stable operation.

, OMPI A predetermined period in the early working hours is operated as a pre-heating stage for a room upgrade, and a voltage higher than a predetermined pressure is applied to the gas sensor (- Ο and the preheating stage

A series connection of a resistor (17) and a capacitor (18) to form a

A timing circuit is provided that includes a circuit and a connecting point (a connecting transistor () that operates in accordance with the potential of ι).

— When the connection point (19) is connected to the negative input terminal

Connect the resistors (21) and (connection point ³ ) of the power supply voltage dividing means to the positive electrode.

Ri you connect to the side input terminal, this is found two of the connection point ⁹⁾及

And the output side is shut off or conducting.

To. That is, the connection connected to the cono-recorder (20)

After the switch (15) is turned on, the capacitor (

The potential is gradually increased by the voltage divider resistor ( ² and

When the voltage is higher than the potential of the connection point (determined by), it is connected.

The output side of the collector (¾¾) is turned on, and the constant voltage

In order to be able to start the circuit operation, the resistance of the timing element

The initial value determined according to the σ R constant of the resistance (and the capacitor (IS)

The predetermined time at the beginning of the operation can be set as the preheating stage by this timing circuit.ο On the other hand, the constant voltage circuit can suppress the fluctuation of the output voltage on the output side. Detection

The transistor is controlled and driven by the signal from the reference voltage detection circuit described later. Unless the detection circuit is started, the transistor ( 16) is the output voltage of the collector.

: The preheating voltage determined by the bias resistance ^

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d-W1PO-, It fluctuates according to fluctuations on the power supply side and load side. Here, since the preheating voltage becomes the maximum value that can be set for the constant voltage operation, when this preheating voltage is applied to the heater ( ¹² >), a preheating stage is formed and rapid heating is performed. The emitter connection point of the transistor is connected to the negative electrode, and the connection point of the power supply voltage dividing means is connected to the positive electrode side. A second comparator () connected to each input terminal of, and a light-emitting element () connected to its output side to form a preheating stage display circuit and a preheating stage state WAIT "is identified by the light emission of the light-emitting element. In other words, the potential of the connection point (does not become lower than the potential of the connection point (when the potential of the connection point falls from the preheating voltage to a predetermined constant voltage value. As long as the comparator (keeps the conduction state, the light emitting element ^ connected to the output side emits light. Since the light emitting element ^ is a preheating stage and not a regular measurement stage, it is preferable to identify the light emitting device by lighting it in red.

Next, the reference voltage detecting circuit in the constant voltage circuit enables the automatic switching from the preheating stage, which is a feature of the present invention, to the measuring stage, and also enables the automatic switching of the measuring stage. The "READY" identification display element is used for detecting the fluctuation of the output voltage. The light emitting element ^ connected to the output side of the first comparator (20) ^ preparative run-g is te (16) a reference voltage generating resistor and the light emission element (the reference voltage generating resistor ^ the connection point is connected to the output side of the ⁽³ connects the element in series <¾, sand I Chi reference voltage point of the third co-down path was connected to the positive side input terminal -. Data (composed e Re that it comprises a 5¾ 3 co down Nono 'Les chromatography data ⁽³ output side bets run- The negative input terminal is connected to the voltage dividing resistor which is the output voltage dividing means, the voltage dividing resistor ( ³³ ), and the connection point of (^). Therefore, when the first comparator (20) commutes after the preheating stage and the light emitting element ^ emits light, the reference voltage detection circuit also operates. As a result, a measurement system for the normal operation state “READ Y ,,” of the constant voltage circuit is formed. Here, it should be noted that the light-emitting element (but preferably, the green light is emitted) In addition, the identification of the measurement stage is performed, and the reference voltage detection circuit of the constant voltage circuit is formed by using the operating voltage. That is, when the potential of the connection point (35) becomes higher than the potential of the connection point (), the output voltage of the transistor (ie) becomes the predetermined value. Therefore, the emitter (31) is turned on to shunt the current to the base circuit of the transistor (16). It controls the current to the circuit, thus enabling the operation of the load circuit with a predetermined constant voltage.

The power supply ⁴ ) is preferable to a battery power supply than a commercial AC power supply, even when the gas concentration detector is used not only for portable use but also for fixed use as a general gas alarm. However, battery power supplies are often prone to abnormally low power supply voltages. Another feature of the present invention is that the detection of such a voltage abnormality can be indicated by a ^second connector (2) and a light emitting element ( ² can be displayed as “WAIT”).

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That is what we did. The voltage of the power supply ⁴ ) is detected at the potential of the connection point of the voltage dividing means. When the potential of this connection point exceeds the lower limit of the power supply voltage, the potential of the output side of the constant voltage circuit is The abnormal voltage drop of the power supply 4) can be identified by the light emitting element () by setting it to be lower. • Therefore, the light emission indicating the measurement stage If the element (28) emits "READY" green light and the preheating stage light-emitting element ( ²⁷ ) emits "WAIT" red light, stop the measurement because the power supply voltage is abnormally low. The battery power supply needs to be replaced, which prevents erroneous detection of measurement detection due to abnormal power supply.

For such a power supply circuit, the load EI path including the gas sensor (10) and the output display (13) is connected to the fourth controller (36) and the gas detector. The ^fourth comparator (the input terminal of the ^fourth comparator) is connected to the connection point of the output voltage dividing means (and the semiconductor device). (11) and the connection point ^ of the variable resistor ^ are connected.The potential at the connection point (can be adjusted by the variable resistor, and the resistance change due to the gas sensitivity of the semiconductor element (11) For example, it can be varied by changing the loon from 10 kΩ ^, that is, the alcohol gas concentration is high and the resistance value of the semiconductor element decreases. And the potential of the connection point increases, and when this value exceeds the potential of the connection point ⁵ ) determined by the voltage-dividing resistor ( ³² ) (33) <34), the fourth component , 'Les Data (but conduction operation to output indicator (13 that runs. Output indicator (causes identified in the light emitting display or warning sound, needs

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) WWIIPPOO In response, this work will cause other safety circuits to be driven.

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-Fig. 3. Fig. 3 is a specific circuit diagram of the gas concentration detector of the present invention.

Yes, the first to ^fourth comparators (2Q

(26), (30) and (33 are 4-bit open collector connectors.

The circuit is configured using a light emitting diode and an electronic buzzer for the output display ³⁾ . here,

Of the circuit components in Fig. 3, the components corresponding to Fig. 2 are the same.

This is indicated by using a reference sign, and is explained by the explanation in Fig. 2.

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In this specific circuit, the light-emitting element in the preheating stage

I ²⁷⁾ red was (and through the power supply (4) resistor connected to the light emitting dialog O

The light emitting element ^ of the measurement stage is connected to the constant voltage output side.

Continued green ^ & light emitting diode and output display means are resistance

Red light emitting diode connected to the constant voltage output side via (41)

The output display is composed of light emission and sound generation.

To display in both, the phonetic («), transistor,

Electronic buzzer including bypass resistor (45) and 3-inorance (including

1 ^ 7) added to the output display means ο

Α ス. Έ ^ This circuit configuration is used for adjustment.

In total, there are four connectors (20), (26), (3D and (

G parts (5 are used to help simplify the circuit

Ο

Another feature of the above embodiment of the present invention is the circuit configuration.

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,-Wipo. In addition to the dual function of the light emitting die (27), <¾) described above, it is also used for the connector and its interface. There is a common use of sharing means. For example, a resistor for voltage division

(21) (and dividing resistors ¾, (33), ^ ² pieces of co emissions Pas Les Ru common use der against the over data. This is found in common are all these reducing the number of parts of the It also helps to prevent power loss and prolong the life of battery power.

Here, the components used in the specific circuit in Fig. 3 are as follows.

IG parts …… High-performance quad comparator (14!> Iii mold; DIP) NEO Type yWP 03390

Gas sensor (10)… "-1 ...: LOkll variable SnOs sintered body sensor built-in approximately 40 mm heater: FIGARO GAS SENS OH TGS # 812 Power supply (14) …… 9 V battery

Transistor control element) …… 2 ^: SC 15 07

Dio red light emitting element (27) (…… SR 103 D

Diode green light emitting element ^ ⁸ ) …… SG 203 D

Electronic buzzer (47) SUMITOMO DENK0 Τνρ Θ ΙΓ4— 20R

Resistance (17) …… 1.2ΜΠ capacitor (

Resistance ( ²¹ ) (321… ··· 3-3 kn resistance ^ 10

Resistance (24) ...... 150 Ω Resistance 270 Ω

Resistance) …… 22 Ω resistance 3.9 kn

Resistance …… 560 Ω Resistance (") 390 Ω

Resistance (…… 2.7 kO resistance (1 Ω

OMPI Variable resistor ^ 1 ~ 1.0 -kn Industrial applicability--This invention can be applied to both portable and fixed use as a gas concentration detector. Is simple and easy to use, and easy to use for everyone. In particular, it is suitable as a gas alarm or an alcohol pick-up for alcohol detection, practical as a relatively inexpensive detector, and has high industrial value.

Claims

39

— 1 —

The scope of the claims

(1) Combine the power supply and the load-side gas sensing element by connecting the I and timing elements to the input side and making the output side conductive after a certain period of time. And a reference voltage detection circuit connected to the output side of the converter, wherein the supply voltage from the power supply to the load is higher than the predetermined output voltage for a predetermined period after starting. It is characterized by using a 1 ° power supply circuit that controls the control element by a signal output from the detection circuit and maintains the predetermined output voltage after the elapse of the period. Yes Gas concentration detector.

(2) In claim 1, the power supply circuit uses the output voltage of the control element as an input signal and shuts off the output side by a change in the output voltage. The second component. The data and the second contour of this. A light emitting element connected to the output side of the unit is provided, and the light emitting element is lit when the voltage supplied from the power supply to the load is in an initial stage higher than a predetermined voltage. Gas concentration detector specializing in display.

(3) In the second aspect of the present invention, the power supply circuit 20 includes a second light emitting element connected to an output side of the first comparator, and the power supply circuit 20 supplies a second light emitting element to the load. When the supply voltage of the LED is in the normal stage where it is maintained at the specified voltage, this light emitting element is illuminated and displayed.

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' Gas concentration detection ο

(4) In the third aspect of the present invention, the detection circuit includes a third comparator connected to the control element on the -m force side: The input side of the comparator is connected to the first connector via the light emitting element of the SD2. A gas concentration detector which is connected to the output side of the recorder and which is characterized in that the voltage of the second light emitting element is used for detecting fluctuations in the output voltage of the control element.

(5) In claim 4, in the insd second connector, the input side has a voltage dividing means for the power supply on its input side, and the potential at the voltage dividing point is recorded in m. If the voltage of the power supply reaches the lower limit of the working pressure, it must not be set to a voltage that substantially matches the predetermined voltage of the control element.

The first light emitting device connected to the output side of the connector and the ° 2 connector is used for power supply abnormality detection that indicates the voltage drop of the power supply. Gas concentration detection Sff o

(6) In the description of the fifth item of the claim, the grj load has a semiconductor element that changes a resistance value in response to a gas concentration and a heater that promotes the sensitivity speed of the element. A gas sensor, and an output display for converting a change in the resistance value of the gas sensor into an electric signal and comparing the electric signal with a reference level to detect a gas concentration; Is a fourth controller connected to the input side of the detection signal of the gas sensor.

1 The alarm connected to the output side of the fourth controller

_ 0? ΛΡ! No Wa-0 Gas concentration detection, which is characterized by having an information display

(?) In the claim 6, the first to fourth connector recorders; open collector connector recorders. The first and second light-emitting elements are light-emitting diodes that emit light of different emission colors, and the control element is a light-emitting diode. Gas concentration detection, which is characterized by the fact that it is

(8) In the first aspect of the present invention, the first and second connectors are obtained by a power supply voltage dividing means common to one of the input terminals. Gas concentration detector O that is connected to a partial pressure point

(9) In claim 7, the third and fourth con- trollers each have one input terminal connected to one of the input terminals by a voltage dividing means for the output voltage of the control element. The obtained common voltage dividing point is connected, and the 分 §C voltage dividing means is connected between the first resistor connected to the high potential side and the second and third resistors connected in parallel to the low potential side. A gas concentration detection device comprising a series circuit, wherein the third resistor is connected to the output side of the first comparator.

( ¹⁰ > In the description of the ninth aspect of the present invention, the gas sensor is a flexible gas sensitive element of a II-type half-element, and a variable resistor is connected in series to the gas sensitive element. To form a voltage dividing circuit for obtaining a gas detection signal, and the voltage dividing circuit A gas concentration detector having a feature that a pressure point is connected to the other input terminal of the first comparator, and the reference level is adjusted by the variable resistor. .