JP5065147B2 - Semiconductor sensor type gas detector - Google Patents

Description

  The present invention relates to a semiconductor sensor type gas detection apparatus including a semiconductor type gas sensor.

Currently, for example, as one of gas sensors for detecting flammable gas and toxic gas, the gas concentration of the detection target gas is detected by detecting the change in the resistance value of the metal oxide semiconductor due to gas adsorption on the surface of the metal oxide semiconductor. A semiconductor gas sensor for detection is known.
In a certain type of this semiconductor gas sensor, for example, a metal oxide semiconductor made of a sintered body mainly composed of tin oxide (SnO ₂ ) is electrically separated from the heater coil and forms a heat conduction relationship. Oxygen in the atmosphere is adsorbed on the surface of the metal oxide semiconductor by being heated by the heater coil so that the surface temperature of the metal oxide semiconductor is maintained at, for example, about 250 to 600 ° C. In the state where the resistance value of the metal oxide semiconductor is maintained at a constant value, the detection target gas contacts the surface of the metal oxide semiconductor to react with oxygen on the surface of the metal oxide semiconductor to deprive oxygen. The resistance value of the metal oxide semiconductor decreases, and the gas concentration of the detection target gas is detected by detecting the change in the resistance value.

  In a semiconductor gas sensor, if a non-energized state continues for a long time, miscellaneous gases and moisture are adsorbed on the surface of the semiconductor gas sensor (metal oxide semiconductor), which stabilizes the characteristics of the semiconductor gas sensor. In general, the metal oxide semiconductor is heated by energization to remove the miscellaneous gas and moisture adsorbed on the surface of the metal oxide semiconductor (sensor activation). (For example, refer to Patent Document 1).

JP 2004-3915 A

  Thus, in the warm-up process associated with the use of the semiconductor gas sensor, the warm-up time (energization time) according to the length of the non-energization leaving time of the semiconductor gas sensor is set using, for example, a comparison table, Although the warm-up process is managed, for example, the operator or the manager himself performs a series of processes including the management of the non-energization time of the semiconductor gas sensor and the setting of the warm-up time. When there is a risk of mistakes intervening and the gas sensor is activated with insufficient activation of the semiconductor gas sensor, or when the main power is turned off and then immediately turned on again (instantaneous power interruption) However, although the warm-up time is substantially unnecessary, the warm-up process is inefficient and the warm-up process itself is troublesome.

  The present invention has been made based on the above circumstances, and an object thereof is to provide a semiconductor sensor type gas detection device capable of easily and efficiently performing a warm-up process of a semiconductor type gas sensor. .

The semiconductor sensor type gas detection device of the present invention includes a semiconductor type gas sensor, and after the warm-up process is performed by turning on the semiconductor type gas sensor, the gas detection operation for the detection target gas is performed. In the semiconductor sensor type gas detection device,
A microcomputer having a warm-up process management function that is started when the main power is turned on, and the power for executing a shutdown process including obtaining time information when the main power is turned off after the main power is turned off. And a recording unit in which time information at the time when the main power is turned off is recorded by the microcomputer in an updatable manner.
Based on the time information when the main power is turned on by the microcomputer and the time information when the main power is turned off in the previous gas detection operation recorded in the recording unit, Is calculated, a warm-up time corresponding to the non-energization leaving time is set, and a warm-up process is performed based on the warm-up time.

  In the semiconductor sensor type gas detector of the present invention, in the operating state, time information is acquired at every predetermined time interval, and the latest time information at the time when it is detected that the main power is turned off is the main power off. The time information can be recorded in the recording unit.

  Furthermore, in the semiconductor sensor type gas detection device of the present invention, it is possible to adopt a configuration provided with time measuring means.

  Furthermore, the semiconductor sensor type gas detection device of the present invention includes a display indicating that the remaining time of the warm-up process required until the gas detection operation can be performed or that the warm-up process is being performed. It can be set as the structure by which the display which shows the state of a semiconductor type gas sensor is made | formed.

  According to the semiconductor sensor type gas detection device of the present invention, the management of the warm-up process including the setting of the warm-up time required for the semiconductor gas sensor accompanying use is automated and the length of the warm-up time is set appropriately. Therefore, the warm-up process can be performed efficiently and easily.

  In the operating state, time information is acquired at predetermined time intervals, and the latest time information at the time when it is detected that the main power is turned off is set as time information when the main power is turned off. Since the non-energization standing time of the semiconductor gas sensor can be grasped with high reliability, the warm-up time can be reliably optimized and the warm-up process can be performed efficiently.

  Furthermore, after the main power is turned off, the backup power supply for supplying the power for executing the shutdown processing including the acquisition of time information when the main power is turned off is provided, so that the shutdown processing is surely performed. Therefore, it is possible to reliably manage the warm-up process associated with the next use.

  Furthermore, since the display data related to the warm-up process is output so that the state of the semiconductor gas sensor can be reliably grasped, the expected gas detection operation in a state adjusted to a state where a stable sensor output can be obtained. Can be implemented reliably.

FIG. 1 is a block diagram showing an outline of the configuration of an example of a semiconductor sensor type gas detection device of the present invention, and FIG. 2 shows an outline of the configuration of an example of a semiconductor type gas sensor constituting the semiconductor sensor type gas detection device of the present invention. It is an explanatory perspective view shown in the state where a part of internal structure was exposed.
This semiconductor sensor type gas detection apparatus includes a gas detection unit 10 including a semiconductor type gas sensor 11 and a control processing unit 20 having a function of calculating a gas concentration according to a gas detection signal obtained from the semiconductor type gas sensor 11. For example, data communication with an external device 30 having a timekeeping function such as a personal computer (PC) is possible.

The semiconductor gas sensor 11 includes a coil-shaped heater 13 that extends in the axial direction of the cylindrical member 12 inside a cylindrical member 12 made of alumina, for example, and both ends in the axial direction of the cylindrical member 12. An electrode 14 is provided on the outer peripheral surface of each of the portions, and further, a metal oxide semiconductor 15 made of a sintered body mainly composed of tin oxide (SnO ₂ ) is provided on the outer peripheral surface of the cylindrical member 12, It is configured. In FIG. 2, reference numeral 16 denotes a lead wire for energizing the metal oxide semiconductor 15.

  The heater 13 is energized by the heater drive circuit 22 in the control processing unit 20 during the gas detection operation, so that the surface temperature of the metal oxide semiconductor 15 is maintained at a predetermined temperature, for example, 250 to 600 ° C. The oxide semiconductor 15 is heated and made of, for example, tantalum, platinum, or an alloy thereof having a calorific value of 0.5 to 1.0 W.

  The control processing unit 20 includes, for example, a heater driving circuit 22 that supplies a current or voltage controlled to an appropriate magnitude to the heater 13 in the semiconductor gas sensor 11, and an amplification circuit that amplifies a gas detection signal from the semiconductor gas sensor 11. 23, a memory 24 in which information relating to warm-up processing performed in conjunction with the use of the semiconductor gas sensor 11 and information relating to the gas detection operation are recorded in an updatable manner, and the operation of each component in the semiconductor sensor gas detection device A microcomputer 21 having a control function, a gas concentration value calculation function, and a warm-up process management function, and a shutdown process including acquisition of time information when the main power is turned off, which will be described later, after the main power is turned off And a backup power supply 25 for supplying power.

  The management function of the warm-up process in the microcomputer 21 will be described in detail. The management of the warm-up process includes the calculation process of the non-energization leaving time of the semiconductor gas sensor 11 and the warm-up time required for the semiconductor gas sensor 11. This includes setting processing and recording processing of time information when the main power is turned off by periodically acquiring time information during the gas detection operation.

As information related to the warm-up process recorded in the memory 24, for example, time information such as date and time acquired from the external device 30 and a necessary warm-up time corresponding to the non-energization leaving time of the semiconductor gas sensor 11 are calculated. Data such as a comparison table for doing this.
In addition, as information related to the gas detection operation, an individual calibration curve (sensitivity curve) unique to the semiconductor gas sensor 11 indicating the relationship between the detection output value obtained by the semiconductor gas sensor 11 and the gas concentration value can be cited. An individual calibration curve is set for each detection target gas.

  The backup power source 25 has time information (time when the main power source is turned off) for calculating a non-energization leaving time when performing a necessary process, that is, a warm-up process associated with the next use after the main power source is turned off. Information) and the power for performing the shutdown process including the recording of the time information in the memory 24 is ensured, and can be configured by a delay circuit such as a capacitor.

Hereinafter, the operation of the semiconductor sensor type gas detector will be described.
As shown in FIG. 3, when the main power is turned on (S1), a warm-up process is performed to activate the semiconductor gas sensor 11 so as to obtain a stable characteristic. In this warm-up process, first, for example, time information (t1) according to the date and time when the main power supply is turned off after the end of the previous gas detection operation recorded in the memory 24 is acquired (S2), and the external device For example, current time information (t2) such as date and time is acquired from 30 (S3). Based on these time information (t1, t2), the non-energization leaving time (T = t2-t1) of the semiconductor gas sensor 11 is obtained. Calculated (S4). Warm-up time required for the semiconductor gas sensor 11 according to the non-energization leaving time (T) obtained in this way is the warm-up time setting data that is recorded in the memory 24, for example, based on a comparison table. Is set based on (S5). Here, in the warm-up time setting data, the warm-up time is set to become longer as the non-energization leaving time of the semiconductor gas sensor 11 becomes longer.
Next, a current (voltage) controlled to an appropriate magnitude by the heater drive circuit 22 is supplied, and a warm-up process is performed based on the set warm-up time (S6).

The heating condition in the warm-up process may be the same as or different from the heating condition during the gas detection operation, and the surface temperature of the metal oxide semiconductor in the semiconductor gas sensor 11 is maintained at a predetermined temperature. The magnitude of the supply current to the heater 13 in the semiconductor gas sensor 11 may be set.
Specifically, the supply current to the heater 13 in the semiconductor gas sensor 11 is in the range of 100 to 300 mA, for example, so that the surface temperature of the metal oxide semiconductor 15 in the semiconductor gas sensor 11 is 200 to 600 ° C. For example, when it is set within the range of 2.0 to 5.0 V and the non-energization leaving time is within the range of 1 to 24 hours, for example, the warm-up time is set to about 4 hours, for example.
The warm-up process is performed, for example, in the atmosphere (a state where humidified air is supplied to the semiconductor gas sensor 11).
Further, during the warm-up process, for example, a message indicating that the warm-up process is being executed and display data such as the remaining time required for the warm-up process are transmitted to the external device 30, and the state of the semiconductor gas sensor 11 is notified. Is done.

When the warm-up process is performed and the semiconductor gas sensor is activated, the gas detection operation can be performed. However, as described above, the warm-up process is performed under the same heating conditions as in the warm-up process. It may be performed continuously after the machine process, or may be performed by changing the setting to a heating condition different from the heating condition in the warm-up process, and re-energized through a non-energized state for a predetermined time. It may be.
For example, when the gas detection operation (S7) is performed under the same heating conditions as the warm-up process, the surface temperature of the metal oxide semiconductor 15 is heated so as to be maintained at a predetermined temperature state. When the detection gas is supplied to the semiconductor gas sensor 11 in the gas detection unit 10, a detection signal corresponding to the resistance value of the metal oxide semiconductor 15 is input to the microcomputer 21 via the amplifier circuit 23, thereby detecting the detection target gas. The gas concentration corresponding to the detection signal is calculated based on the individual calibration curve recorded in the memory 24, and the result is output to, for example, the external device 30 and displayed.

  When it is detected that the gas detection operation is finished and the main power supply is turned off (S8), the operation state is maintained for a predetermined time by the power supply from the backup power supply 25, and the shutdown process is performed. That is, when it is detected that the main power supply is turned off, the latest time information acquired from the external device 30 is the time information (t1) when the main power supply is turned off, that is, with the next use of the semiconductor gas sensor 11. It is recorded in the memory 24 as a reference time for the non-energization standing time (T) (S9).

  Thus, according to the semiconductor sensor type gas detection device described above, when the semiconductor type gas sensor 11 is used, it is necessary to perform a warm-up process. When the main power is turned on during the startup process, The non-energization leaving time (T) is calculated based on the current time information and the time information recorded in the memory 24 at the time when the main power supply is turned off, and according to the non-energization leaving time (T). By performing the warm-up process based on the set warm-up time, basically, a series of warm-up processes including calculation of the non-energization leaving time (T) of the semiconductor gas sensor 11 and setting of the warm-up time. Is automatically performed and the warm-up process is performed with the warm-up time set to an appropriate length, so that the warm-up process can be performed efficiently and easily. The semiconductor type gas It can be surely adjusted to a state where the output of the sensor 11 always stable can be obtained.

  In the operating state, time information is acquired at predetermined time intervals, and the latest time information at the time when it is detected that the main power is turned off is set as time information when the main power is turned off. Since the non-energization leaving time of the semiconductor gas sensor 11 can be grasped with high reliability, the warm-up time can be reliably optimized and the warm-up process can be performed efficiently.

  Furthermore, after the main power supply is turned off, the backup power supply 25 that supplies power for executing the shutdown process including the acquisition of time information when the main power supply is turned off is provided, so that the shutdown process is reliably performed. Therefore, it is possible to reliably manage the warm-up process associated with the next use.

  Furthermore, since the display data related to the warm-up process is output to the outside so that the state of the semiconductor gas sensor 11 can be reliably grasped, the expected data can be obtained in a state adjusted to a state where a stable sensor output can be obtained. The gas detection operation can be reliably performed.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to said embodiment, A various change can be added.

For example, as shown in FIG. 4, the semiconductor sensor type gas detection device itself can be configured to include a timer unit 26, and in such a configuration, a timer unit driving battery 27 is provided.
The timer unit 26 may have any function such as a clock function, a timer function, and a calendar function, and can be configured by, for example, an RTC (real time clock).
Even in such a configuration, the same effects as those according to the above-described embodiment, that is, the time information when the main power is turned off (reference time) and the time when the main power is turned on obtained in the semiconductor sensor type gas detector itself. The warm-up process including the calculation of the de-energization time based on the time information and the setting of the warm-up time is performed autonomously, so that the warm-up process can be performed efficiently and the semiconductor gas sensor 11 is always The desired gas detection operation can be reliably performed in a state adjusted to a state where stable characteristics can be obtained.

  Further, the semiconductor sensor type gas detection device itself may be configured to include display means.

It is a block diagram which shows the outline of a structure in an example of the semiconductor sensor type gas detection apparatus of this invention. It is an explanatory perspective view which shows the outline of the structure in an example of the semiconductor type gas sensor which comprises the semiconductor sensor type gas detection apparatus of this invention in the state which exposed a part of internal structure. It is an operation | movement flowchart for demonstrating operation | movement of the semiconductor sensor type gas detection apparatus of this invention. It is a block diagram which shows the outline of the structure in the other example of the semiconductor sensor type gas detection apparatus of this invention.

DESCRIPTION OF SYMBOLS 10 Gas detection part 11 Semiconductor type gas sensor 12 Cylindrical member 13 Heater 14 Electrode 15 Metal oxide semiconductor 16 Lead wire 20 Control processing part 21 Microcomputer 22 Heater drive circuit 23 Amplification circuit 24 Memory 25 Backup power supply 26 Timekeeping part 27 Timepiece part drive Battery 30 External device

Claims (4)

In the semiconductor sensor type gas detection device comprising a semiconductor type gas sensor, and after the warming-up process is performed by the semiconductor type gas sensor being energized, the gas detection operation for the detection target gas is performed.
A microcomputer having a warm-up process management function that is started when the main power is turned on, and the power for executing a shutdown process including obtaining time information when the main power is turned off after the main power is turned off. And a recording unit in which time information at the time when the main power is turned off is recorded by the microcomputer in an updatable manner.
Based on the time information when the main power is turned on by the microcomputer and the time information when the main power is turned off in the previous gas detection operation recorded in the recording unit, Is calculated, a warm-up time corresponding to the non-energization leaving time is set, and a warm-up process is performed based on the warm-up time.   In the operating state, time information is acquired at predetermined time intervals, and the latest time information at the time when it is detected that the main power is turned off is recorded in the recording unit as time information when the main power is turned off. The semiconductor sensor type gas detector according to claim 1 characterized by things. The semiconductor sensor type gas detection device according to claim 1, further comprising a timing unit . It is characterized in that a display indicating the state of the semiconductor gas sensor including the remaining time of the warm-up process required until the gas detection operation can be performed or the display indicating that the warm-up process is being performed is performed. The semiconductor sensor type gas detection device according to any one of claims 1 to 3.

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