JP3062615B2 - Oxygen concentration detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oxygen concentration detecting device for detecting oxygen concentration in air.

[0002]

2. Description of the Related Art Conventionally, an oxygen concentration detecting apparatus using a galvanic cell type oxygen sensor or the like has been proposed. In the galvanic cell type oxygen sensor, an output voltage proportional to the oxygen concentration is obtained, but this output voltage decreases with the aging of the sensor.

Therefore, various methods have been proposed for correcting the aging of the sensor. For example, in Japanese Patent Application Laid-Open No. Sho 61-231451, the output voltage of the sensor at the start of measurement is stored as a reference value. A technique is disclosed in which a ratio between an output voltage of a sensor measured thereafter and a reference value is determined, and when the ratio falls below a certain value, an abnormality in the oxygen concentration is notified.

[0004] In the above method, when the oxygen concentration detecting device is turned on and off in conjunction with the turning on and off of the heater, the oxygen concentration at the start of the measurement is changed to the standard oxygen concentration in the air (approximately 21%), it is possible to correct the temporal change of the output voltage of the sensor by storing the oxygen concentration at the time of power-on as a reference value, but the power is always on. Not applicable to equipment.

[0005] Therefore, it is conceivable to store the measured oxygen concentration as a reference value for each predetermined period, and determine abnormality based on the reference value and the oxygen concentration detected by the sensor. However, in the above method, the oxygen concentration taken in every predetermined period is not always equal to the standard oxygen concentration in the air. It is conceivable that the low oxygen concentration at that time is set as the reference value. In this case, even if the oxygen concentration level in the room is reduced to a dangerous level, the abnormality may not be reported because the reference value is low.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an oxygen concentration detecting device capable of correctly correcting a change with time of the output of an oxygen sensor.

[0007]

The gist of the present invention is that the difference data between the measured oxygen concentration data at the time of correction of the reference oxygen concentration and the reference oxygen concentration data is stored as a correction amount, and the measured oxygen concentration data is stored at predetermined intervals. Obtain difference data from the reference oxygen concentration data, determine whether the difference data exceeds a predetermined amount, if the difference data is less than the predetermined amount, the measured oxygen concentration data at that time as the reference oxygen concentration data When the difference data exceeds a predetermined amount, the reference oxygen concentration data is corrected based on the correction amount at the time of the previous correction, and the corrected value is stored as the reference oxygen concentration data.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit configuration diagram of the oxygen concentration detecting device of the embodiment.

In FIG. 1, a reference clock signal generated by an oscillation circuit 1 is divided by a frequency dividing circuit 2 to a predetermined frequency and output to a time counting circuit 3. The time counting circuit 3 counts the time signal from the frequency dividing circuit 2 to obtain time data, and the time data is sent to the CPU 5 together with the minute carry and the hour carry.
Output to The date counting circuit 4 counts the day carry signal from the time counting circuit 3 to obtain date data, and outputs the date data to the CPU 5 together with the week carry signal.

The oxygen sensor 6 comprises, for example, a galvanic cell type oxygen sensor and outputs a voltage proportional to the oxygen concentration in the air. After the output voltage of the oxygen sensor 6 is amplified by the amplifier circuit 7, it is converted into a digital value by the A / D converter circuit 8 and output to the CPU 5. The amplification circuit 7 and the A / D conversion circuit 8 are driven by measurement signals output from the CPU 5 at one-minute intervals.

The CPU 5 is a central processing unit for controlling the entire circuit. The CPU 5 stores the oxygen concentration data and the like detected by the oxygen sensor 6 in the RAM 9 and drives the display drive circuit 10 to display the time and date data. It is displayed on the unit 11.

The display unit 11 comprises a liquid crystal display or the like,
10 oxygen concentration indicators 1 indicating the oxygen concentration level at the top
1a is provided, and the oxygen concentration indicator 11a is sequentially turned on every time the measured oxygen concentration becomes lower than the reference value by 1%. At the center and lower part of the display unit 11, a date display unit 11b for displaying a date and a time display unit 11c for displaying time are provided.

FIG. 2 is a diagram showing a configuration of a register of the RAM 9. The RAM 9 stores a measured oxygen concentration storage unit X for storing oxygen concentration data detected by the oxygen sensor 6, and a fixed period (for example, one week). A) a reference oxygen concentration storage unit Y for storing the maximum value of the plurality of oxygen concentration data measured in each case) as reference oxygen concentration data, and level data indicating what percentage of the measured oxygen concentration is lower than the reference value. A level storage unit Z, a difference storage unit V for storing difference data between the measured oxygen concentration and the reference oxygen concentration, and a correction amount storage unit W for storing a correction amount of the reference value at the time of the previous correction are provided.

Next, the operation of the first embodiment of the present invention will be described with reference to the flowcharts of FIGS. FIG.
It is a flowchart of an oxygen concentration measurement process and a key process. First, it is determined whether or not minute carry has occurred in S1 of FIG. If the minute carry has occurred, it is the timing for measuring the oxygen concentration every minute, so in the next step S2, the amplifier circuit 7 and the A / D conversion circuit 8 are driven to measure the oxygen concentration, and the measurement data is measured. It is stored in the oxygen concentration storage unit X. Further, in step S3, the oxygen concentration level at that time is calculated.

If it is determined in step S1 that no carry has occurred, the flow advances to step S14 to determine whether a key input has been performed. When the key input is being performed, the key processing of step S15 is executed.

FIG. 4 is a more detailed flowchart of the oxygen concentration level calculation processing in step S3. In the following description, X and Y indicate the measured oxygen concentration storage unit, the reference oxygen concentration storage unit, or the measured oxygen concentration data and the reference oxygen concentration data stored in these storage units.

In step S21 of FIG. 4, it is determined whether or not the measured oxygen concentration X is smaller than the reference oxygen concentration Y. If the measured oxygen concentration X is not smaller than the reference oxygen concentration Y (NO in step S21), the process proceeds to step S22, and “0” is set in the level storage unit Z. This state is a case where the measured oxygen concentration X is equal to or larger than the reference oxygen concentration Y, and the ten oxygen concentration level indicators 11
All lights are turned off to clearly indicate that the oxygen concentration is normal.

If the determination in step S21 is YES,
Proceeding to step S23, if the measured oxygen concentration X is Y> X ≧ Y.
It is determined whether it is in the range of 99/100. When the measured constant oxygen concentration X is in the above range, the process proceeds to step S24, and “1” is set in the level storage unit Z. This state is a case where the oxygen concentration measured this time is at most 1% lower than the reference oxygen concentration, and one oxygen concentration indicator 11a of the display unit 11 lights up to clearly indicate that the oxygen concentration is 1% lower. .

If the determination in step S23 is NO, the process proceeds to step S25, where the measured oxygen concentration X is determined as follows: Y · 99/100> X
It is determined whether it is in the range of ≧ Y · 98/100. When the measured oxygen concentration is within the above range, "2" is set in the level storage unit Z in step S26. This state is a case where the oxygen concentration X measured this time is 1% to 2% lower than the reference oxygen concentration Y, and two oxygen concentration indicators 11a of the display unit 11 are turned on, and the oxygen concentration is 2% lower. Specified.

If the determination in step S25 is NO, similarly, the measured oxygen concentration X is 2% -more than the reference oxygen concentration Y.
.. Are determined in order of 3% lower range, 3% to 4% lower range,..., And a numerical value corresponding to the level storage unit Z is set based on each determination result. Then, step S2
At 7, the measured oxygen concentration X is Y · 92/100> X ≧ Y · 91/100
It is determined whether or not it is within the range. If it is within that range, “9” is set in the level storage unit Z in step S28.
In this state, the oxygen concentration X measured this time is equal to the reference oxygen concentration Y
This is the case where the oxygen concentration is lower by 8% to 9%, and nine pieces of the oxygen concentration indicators 11a of the display unit 11 are turned on to clearly indicate that the oxygen concentration is 9% lower.

At this time, if the determination in step S27 is NO, "10" is set in the level storage section Z in step S29. This state is when the oxygen concentration X measured this time is lower than the reference oxygen concentration Y by 9% or more.
All 0 oxygen concentration indicators light up and the oxygen concentration is 9%
It is clearly stated that it is lower.

By these treatments, the measured oxygen concentration X
Accordingly, the oxygen concentration indicator 11a of the display unit 11 is turned on or off according to the condition (1), so that it is possible to report what percentage of the current oxygen concentration is lower than the reference oxygen concentration Y.

When the oxygen concentration level calculation processing is completed,
In step S4 in FIG. 3, it is determined whether a weekly carry has occurred. If a weekly carry occurs, step S5
Then, the oxygen concentration measured this time is stored in the measured oxygen concentration storage unit X.

Further, in step S6, difference data between the measured oxygen concentration X and the reference oxygen concentration Y is obtained, and the difference data is stored in the difference storage unit V. Then, in the next step S7, it is determined whether or not the difference data is larger than a value obtained by adding a predetermined error amount α to the correction amount at the time of the previous correction.

If the difference data is equal to or smaller than the value obtained by adding α to the previous correction amount (NO in step S7), the current measured value is set as a reference value in the reference oxygen concentration storage unit Y in step S8. Store. Further, step S
In step 9, the difference data of this time is stored in the correction amount storage unit W. Thereafter, in the display process of step S10, the oxygen concentration indicator of the display unit 11 is turned on or off according to the oxygen concentration at that time.

If it is determined in step S7 that the difference data is larger than the value obtained by adding the error amount α to the previous correction amount, then in step S11 the previous correction amount is calculated from the reference oxygen concentration stored in the reference value storage unit Y. The subtracted value is stored in the reference oxygen concentration storage unit Y as a new reference oxygen concentration. Thereafter, in the display processing of step S10, the oxygen concentration indicator 11a of the display unit 11 is turned on or off according to the oxygen concentration at that time.

With these processes, even if a stove or the like is attached and low oxygen concentration data is taken in at the time of correction of the reference oxygen concentration every week, for example, the difference between the reference value and the measured value is obtained. Since the data becomes larger than the predetermined amount (previous correction amount + α), a value obtained by subtracting the previous correction amount from the reference value at the previous correction is set as the reference value. Therefore, a low oxygen concentration is not set as a reference value, and a temporal change of the sensor can be correctly corrected.

Next, a second embodiment of the present invention will be described with reference to the flowchart of FIG. In this embodiment, when the difference data is larger than the value obtained by adding the error amount α to the previous correction amount when correcting the reference value every week, another measurement timing (for example, when a carry signal occurs at 12:00) In (2), it is determined whether or not the difference data between the measured oxygen concentration and the reference value at that time is larger than “previous correction amount + α”, and the reference value is corrected.

First, it is determined in step S31 in FIG. 5 whether minute carry has occurred. If minute carry has occurred, the output voltage of the oxygen sensor 6 is amplified and A / D converted in step S32 to obtain digital oxygen concentration data. Further, in step S33, the above-described oxygen concentration level calculation processing is executed to obtain oxygen concentration level data corresponding to the oxygen concentration.

Next, in step S34, the flag FA is set to "0".
, “1” or “2”. The flag FA is a flag in which a predetermined numerical value is set based on the determination result of the magnitude relationship between the difference data at the time of correction of the reference value and the previous correction amount + α. When the difference data is larger than the previous correction amount + α, the difference data is “1” when the difference data is larger than the correction amount + α at 12:00, and when the difference data is equal to or smaller than the correction amount + α, the reference value is corrected. Is performed, "0" is set.

When the flag FA is "0" in the determination in step S34, the flow advances to step S35 to determine whether or not a weekly carry has occurred. If a week carry occurs, the measured oxygen concentration is stored in the measured oxygen concentration storage unit X in the next step S36. Further, in step S37, difference data between the measured oxygen concentration X and the reference oxygen concentration Y is calculated, and the difference data is stored in the difference storage unit V.

Next, in step S38, the difference data between the measured oxygen concentration X and the reference oxygen concentration Y is calculated by adding the error amount α to the previous correction amount.
It is determined whether the value is larger than the value obtained by adding. If the difference data is not larger than the previous correction amount + α, it is determined that the oxygen concentration measured this time is a normal value, and the process proceeds to step S39, where the current measurement value is set as the reference oxygen concentration and the reference oxygen concentration storage unit Y
Set to. Further, the current difference data is stored in the correction amount storage unit W in step S40. Then, step S50
Is executed. In this display process, the oxygen concentration indicator 11a of the display unit 11 is turned on or off according to the oxygen concentration level, and the oxygen concentration at that time is displayed.

If it is determined in step S38 that the difference data is larger than the previous correction amount + α, the flag FA is set to "1" in step S41. Flag FA in step S34
When FA = 1 in the determination of, the process proceeds to step S42 and 1
At 2 o'clock, it is determined whether or not a carry signal has occurred. 1
If a carry signal occurs at 2 o'clock, step S
At 43, the oxygen concentration at that time is measured, and the measured value is stored in the oxygen concentration storage unit X. Then, in step S44, difference data between the current measured value X and the reference value stored in the reference value storage unit Y is obtained.

In step S45, it is determined whether the difference data is equal to or smaller than the previous correction amount + α. If the difference data is equal to or smaller than the previous correction amount + α, it is determined that the oxygen concentration measured this time is a normal value, and the current measurement value is set as the reference oxygen concentration in step S46. Set to Y. Further, the current difference data is stored in the correction amount storage unit W in step S47. As a result, the correction of the reference oxygen concentration has been completed, and therefore, Step S48 is performed.
To set the flag FA to "0".

If the difference data is larger than the previously corrected amount + α in the determination in step S45, it means that the oxygen concentration has been measured twice and the values have not been both normal values. In this case, the process proceeds to step S49. "2" is set to the flag FA.

Thereafter, the display process of step S50 is executed, and the oxygen concentration indicator 11a of the display unit 11 is turned on or off according to the oxygen concentration level at that time, and the measured oxygen concentration is 100 to 90% of the reference value. Shows whether it is in range or less.

In the next step S51, it is determined whether or not the flag FA is "2". If FA = 2, it means that the read measured value of the oxygen concentration is an abnormally low value both times, and in this case, the abnormality processing of step S52 is executed to notify the abnormality of the sensor by display.

According to these processes, for example, when the oxygen concentration measured at the time of correction of the reference value every week happens to be low and the difference data is larger than the previously corrected amount + α, the carry signal at 12:00 after a predetermined time has passed. Is corrected, the reference value is corrected again, so that a lower than normal oxygen concentration can be prevented from being set as the reference value.

As described above, in the above embodiment, when correcting the reference oxygen concentration, the difference data between the current measured value of the oxygen concentration and the reference oxygen concentration is obtained, and the difference data is determined by a predetermined correction amount (for example, If it is equal to or less than the previous correction amount + α), it is determined that normal oxygen concentration data has been obtained, the measured value at that time is set as reference oxygen concentration data, and if the difference data exceeds the predetermined correction amount. For example, a value obtained by subtracting the previous correction amount from the reference value is set as the reference value, or the reference value is corrected again at another measurement timing.

Therefore, even if a low oxygen concentration happens to be measured when the reference value is corrected, the low oxygen concentration is not set as the reference value, so that no abnormality is reported even if the oxygen concentration becomes a dangerous level. Can be eliminated.

The oxygen concentration detecting device of the present invention may be a dedicated device for measuring the oxygen concentration, or may be incorporated in electronic equipment other than the electronic timepiece.

[0042]

According to the present invention, when the reference value is corrected,
Obtain difference data between the measured value and the reference oxygen concentration, if the difference data is equal to or less than a predetermined amount, set the measurement value at that time as the reference oxygen concentration, and when the difference data exceeds the predetermined amount, for example, from the reference value A value obtained by subtracting the previous correction amount is set as a reference value. Therefore, even when an oxygen concentration lower than a normal state is measured during the correction of the reference value, it is possible to prevent the low value from being set as the reference value.

[Brief description of the drawings]

FIG. 1 is a circuit configuration diagram of an oxygen concentration detection device according to an embodiment.

FIG. 2 is a configuration diagram of a RAM.

FIG. 3 is a flowchart showing the operation of the first embodiment.

FIG. 4 is a flowchart of an oxygen concentration level calculation process.

FIG. 5 is a flowchart showing the operation of the second embodiment.

[Explanation of symbols]

 5 CPU 6 Oxygen sensor 11 Display

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01N 27/26 371 G01N 27/26 381

Claims (2)

(57) [Claims] 1. An oxygen sensor, oxygen concentration calculating means for obtaining oxygen concentration data from the output of the oxygen sensor, reference oxygen concentration storage means for storing reference oxygen concentration data, and when the reference oxygen concentration is corrected. Correction amount storage means for storing the correction amount of the reference oxygen concentration data, and for each predetermined period, obtains difference data between the measured oxygen concentration data and the reference oxygen concentration data, and determines whether the difference data exceeds a predetermined amount. Determining means for determining whether or not the difference data is equal to or less than a predetermined amount; and storing the measured oxygen concentration data at that time as reference oxygen concentration data in the reference oxygen concentration storage means. And storing the difference data in the correction amount storage means. If the determination means determines that the difference data exceeds a predetermined amount, the reference oxygen concentration storage means The stored reference oxygen concentration data is corrected based on the correction amount at the time of the previous correction stored in the correction amount storage means, and the corrected value is stored in the reference oxygen concentration storage means as reference oxygen concentration data. An oxygen concentration detection device comprising: a reference value setting unit; and a notification unit that detects and reports an abnormality in oxygen concentration from the measured oxygen concentration data and the reference oxygen concentration data. 2. An oxygen sensor, oxygen concentration calculating means for obtaining oxygen concentration data from the output of the oxygen sensor, reference oxygen concentration storage means for storing reference oxygen concentration data, and when the reference oxygen concentration is corrected. Correction amount storage means for storing the correction amount of the reference oxygen concentration data, determination means for determining whether the difference data between the measured oxygen concentration data and the reference oxygen concentration data exceeds a predetermined amount, and a predetermined period. Operating the discriminating means for each time, when it is determined that the difference data is equal to or less than the predetermined amount, storing the measured oxygen concentration data at that time as the reference oxygen concentration data in the reference oxygen concentration storage means, First reference value setting means for storing difference data in the correction amount storage means, and the first reference value setting means operates the discriminating means so that the difference data exceeds the predetermined amount. If it is determined that there,
The determination means is operated after a lapse of time shorter than the predetermined period, and if it is determined that the difference data is equal to or less than the predetermined amount, the measured oxygen concentration data at that time is used as the reference oxygen concentration data in the reference oxygen concentration storage means. An oxygen concentration detection device comprising: a second reference value setting unit to be stored; and a notifying unit that detects and notifies an abnormality in the oxygen concentration from the measured oxygen concentration data and the reference oxygen concentration data.