JPH05281184A - Oxygen concentration detection device - Google Patents

Abstract

(57) [Summary] [Objective] To provide an oxygen concentration detection device capable of appropriately correcting an error due to aging of a galvanic battery. [Structure] At the time of updating to update the reference output, which is the output of the oxygen sensor at the standard oxygen concentration, according to the secular change of the oxygen sensor, the oxygen sensor output (X) at that time and the reference output (Y) up to that point Then, the average output is obtained and used as a new reference output (Y) (step S7).

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 the oxygen concentration in the air by using a galvanic battery type oxygen sensor or the like.

[0002]

2. Description of the Related Art Conventionally, an oxygen concentration detecting device utilizing a galvanic battery type oxygen sensor has been considered. An output voltage proportional to the oxygen concentration can be obtained with the galvanic cell type oxygen sensor, but the output voltage of the sensor actually decreases due to the aging of the sensor. Therefore, if you treat the output voltage measured by the sensor and the oxygen concentration as a fixed relationship, when the output voltage of the sensor decreases with time,
Even if the oxygen concentration is normal, it is determined that the oxygen concentration is below the reference value, and the abnormality is reported.

In order to solve the above-mentioned problems in the oxygen concentration detecting device which continuously measures the oxygen concentration of the environment in which it is placed, the applicant of the present invention defines a fixed length period, that is, an update period, and updates the period. It is assumed that the oxygen concentration at that time is the standard oxygen concentration (20.6%) at each start of the period (for example, every midnight on Sunday when the renewal period is one week). The sensor output is set as a reference output corresponding to the standard oxygen concentration, and basically, an oxygen concentration detection device has been proposed that measures the oxygen concentration thereafter based on this reference output (Japanese Patent Application No. Hei 10 (1999) -135242). 3-20288
7).

In the above oxygen concentration detector,
In consideration of the case where the above assumption is not satisfied, that is, the case where the oxygen concentration detection device is placed in a low oxygen environment at the start of the renewal period (hereinafter referred to as renewal), the reference output is used in the subsequent measurement. When there is a sensor output higher than the above, a correction method of replacing the higher sensor output with the reference output is also adopted.

[0005]

However, although the oxygen concentration detecting device as described above adopts the above-described correction method, the oxygen concentration detecting device is placed in a low oxygen environment at the time of renewal, and continues thereafter. When placed in such an environment, a notification such as a standard oxygen concentration environment will be issued despite the low oxygen concentration environment. Further, after the renewal, the change in the low oxygen concentration of the environment greatly progresses, and even if the human body is in a dangerous state, the oxygen concentration is slightly lowered, and the notification is stopped. The present invention has been made in view of the above circumstances, and at the time of updating the reference output, which is the output of the oxygen sensor at the standard oxygen concentration, according to the secular change of the oxygen sensor, the oxygen concentration of the environment is standard. An object of the present invention is to provide an oxygen concentration detection device in which subsequent measurement results do not greatly deviate from the actual oxygen concentration even when the oxygen concentration is lower than the oxygen concentration.

[0006]

In order to achieve the above object, the present invention obtains the oxygen sensor output at that time and the average output of the reference outputs up to that point in updating the reference output. A new reference output is used.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit configuration diagram of an oxygen concentration detection device according to an embodiment. In the figure, the reference clock signal generated by the oscillation circuit 1 is divided into a predetermined frequency by the frequency dividing circuit 2 and output to the time counting circuit 3. The time counting circuit 3 counts the clock signal from the frequency dividing circuit 2 to obtain time data, and outputs the time data to the CPU 5 together with the minute carry.
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 is composed of, for example, a galvanic cell type oxygen sensor and outputs a voltage proportional to the oxygen concentration in the air. The output voltage of the oxygen sensor 6 is amplified by the amplifier circuit 7, converted by the A / D conversion circuit 8 into an 8-bit digital value of 0 to 255, and output to the CPU 5. The amplifier circuit 7 and the A / D conversion circuit 8 are driven by the measurement signal output from the CPU 5 at 1-minute intervals.

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

The display unit 11 is composed of a liquid crystal display or the like,
Ten oxygen concentration indicators 11a to 11j indicating the level relating to the oxygen concentration are provided on the upper portion. These oxygen concentration indicators are placed in an environment of standard oxygen concentration and the output of the oxygen sensor 6 is present. Are all turned on when is the reference output, and when the output of the oxygen sensor 6 decreases, the number of turns on decreases according to the degree. A segment display is provided at the center and lower part of the display unit 11 to display date and time.

The key processing unit 12 is composed of a plurality of keys which are operated at the time of starting the time adjustment, the measurement of the oxygen concentration, etc., and the operation signals of these keys are output to the CPU 5. Figure 2
It is a figure showing the composition of the register of RAM9, and the measured oxygen concentration storage part X which memorize | stores the value from A / D conversion circuit 8 corresponding to the output detected by the oxygen sensor 6, ie, measured oxygen concentration data, in RAM9. A reference oxygen concentration storage unit in which the average of the measured oxygen concentration data measured at that point and the reference oxygen concentration data set up to that point is set as new reference oxygen concentration data at regular intervals (for example, every week). Y and a level storage section Z for storing level data which is a value obtained by subtracting the measured oxygen concentration data value from the reference oxygen concentration data value are provided.

Next, the operation of the first embodiment of the present invention will be described with reference to the flowchart of FIG. First, step S
At 1, it is determined whether or not minute carry occurs. If minute carry occurs, it is the measurement timing of the oxygen concentration every one minute, so in the next step S2 the amplifier circuit 7 and A /
The D conversion circuit 8 is driven to measure the oxygen concentration, and the measurement data is stored in the measured oxygen concentration storage unit X. Further, in step S3, the current measured oxygen concentration data value is subtracted from the reference oxygen concentration data value set in the reference oxygen concentration storage unit Y, the result, that is, level data is obtained, and this is set in the level storage unit Z. To do.

Next, at step S4, it is judged whether the measured oxygen concentration data value set in the measured oxygen concentration storage unit X is larger than the reference oxygen concentration data value set in the reference oxygen concentration storage unit Y. When it is larger, the measured oxygen concentration data of this time is set in the reference oxygen concentration storage unit Y as the reference oxygen concentration data in step S5 and then the process proceeds to step S6. If it is determined that the size has not increased, the process directly proceeds to step S6. Then, in step S6, it is determined whether the weekly carry is sent from the date counting circuit 4, and if the weekly carry is sent, the process proceeds to step S7, and the measured oxygen concentration data value in the measured oxygen concentration storage unit X and the reference After adding the reference oxygen concentration data value of the oxygen concentration storage unit Y, dividing the sum by 2 and obtaining the average value of both, after setting this as new reference oxygen concentration data in the reference oxygen concentration storage unit Y The process proceeds to step S8, but if it is determined in step S6 that the weekly carry has not been sent, the process directly proceeds to step S8. In step S8, first, the ten oxygen concentration indicators 11a to 11 of the display unit 11 are displayed.
The level data of the level storage section Z is displayed by j. In this case, as shown in FIG. 4, when the oxygen concentration is relatively high and the level data value of the level storage unit Z is a value up to 1, all the oxygen concentration indicators 11a to 11j are turned on. Becomes lower and the level data value of the level storage section Z becomes larger, the number of lights to be turned off is increased (that is, the number of lights to be turned on is decreased), and the level data value becomes 29.
When the value reaches 33 or more, all are turned off, and when the level data value becomes 34 or more, the oxygen concentration indicator 1
All of 1a to 11j will be displayed by blinking. After the display processing of the level data by the oxygen concentration indicators 11a to 11j, the date display data from the date counting circuit 4 and the current data from the time counting circuit 3 are respectively displayed by the segment display bodies at the central portion and the lower portion of the display unit 11. Display time data. However, for example, when it is 8:35:20 on Monday of January 23 at present and the level data of the level storage unit Z is up to 1, the display of the display unit 11 is displayed by the oxygen concentration indicators 11a to 11j. All are turned on, and the display becomes as shown in FIG. 5A. Further, the time has passed from the above time to 11:40:15, and the level data value of the level storage unit Z becomes a value from 8 to 9. Display 1
The display of 1 is as shown in (b) of the figure with the four oxygen concentration indicators 11a to 11d turned off.

After the display process of step S8 is completed, the process returns to step S1. If it is determined in step S1 that the minute carry has not been sent, step S
If there is a key input, the process proceeds to step S10, and if there is a key input, the process proceeds to step S11 to execute the corresponding key process, and then proceeds to the display process of step S8, but there is no key input. Goes directly to the display process of step S8.

[0015]

As described above in detail, the present invention, at the time of updating the reference output, which is the output of the oxygen sensor at the standard oxygen concentration, according to the secular change of the oxygen sensor, the oxygen sensor at that time. This is related to the oxygen concentration detection device that obtains the average output of the output and the reference output up to that point and uses this as the new reference output, so the oxygen concentration of the environment is lower than the standard oxygen concentration at the time of updating. Even if it is, it is possible to provide an oxygen concentration detection device in which the subsequent measurement results do not deviate significantly from the actual oxygen concentration.

[Brief description of drawings]

FIG. 1 is a diagram showing a circuit configuration of an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a RAM shown in FIG.

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

FIG. 4 is a diagram showing a relationship between a lighting mode of the oxygen concentration indicator of FIG. 1 and level data relating to oxygen concentration.

FIG. 5 is a diagram showing an example of a display mode of a display unit.

[Explanation of symbols]

 3 Time counting circuit 4 Date counting circuit 6 Oxygen sensor 8 A / D conversion circuit 9 RAM 11 Display section 11a to 11j Oxygen concentration indicator X Measured oxygen concentration storage section Y Reference oxygen concentration storage section Z Level storage section

Claims (1)

[Claims] 1. An oxygen sensor, a measured oxygen concentration data generating means for obtaining measured oxygen concentration data from the output of this oxygen sensor, a reference oxygen concentration data storage means for storing reference oxygen concentration data, and this reference oxygen concentration data storage means. Means for obtaining the oxygen concentration level from the reference oxygen concentration data and the measured oxygen concentration data, and the measured oxygen concentration data obtained by the measured oxygen concentration data generating means and the reference of the reference oxygen concentration data storage means at regular intervals. An oxygen concentration detecting device, comprising: average value with oxygen concentration data; and reference value storage control means for storing the average data as reference oxygen concentration data in the reference concentration data storage means.