JP2005337873A - Gas sensor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas sensor device capable of elongating a sensor lifetime, and performing simply light source control processing for elongation of the lifetime. <P>SOLUTION: When taking a reference signal from a light receiving element 32, a signal processing part 6 increases the count value of a timer 9, and determines whether the count value is registered in a table stored in a storage part 7 or not. When the count value of the timer 9 is registered in the table in the storage part 7, namely, when the accumulated value of a lighting time of a light source 2 shows elapse of a fixed time, the signal processing part 6 determines that adjustment of the light source 2 is necessary, reads out as a control value a light source application voltage registered in the table corresponding to the count value, and gives a new control instruction based on the light source application voltage value to a light source control part 8, to thereby control lighting of the light source 2. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a gas sensor device that detects a detection target gas in an atmosphere by utilizing that the detection target gas absorbs infrared rays having a specific wavelength.

This type of gas sensor device receives infrared light from a light source through a filter that does not transmit the gas to be detected, and controls the applied voltage of the light source based on the amount of received infrared light to make the amount of infrared light from the light source constant. What is kept is provided (for example, patent document 1).
JP 61-223633 A

  By the way, with what was described in the said patent document 1, even if the lifetime of a sensor which can be brought about by the output fall by deterioration with time of a light source can be aimed at, it can extend from a light source through the filter which does not permeate | transmit detection object gas. Since the infrared light is received and the applied voltage of the light source is feedback controlled based on the amount of received infrared light, it is necessary to calculate the control amount from the difference between the target infrared light amount and the received infrared light amount. There was a problem that the burden of processing was heavy.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a gas sensor device capable of extending the life of the sensor and easily performing light source control processing for extending the life. It is in.

In order to achieve the above object, in the invention of claim 1, a light source that outputs infrared rays when lit,
Among the infrared rays output from the light source, the infrared rays are received through a selection filter that passes only the infrared rays having a wavelength absorbed by the detection target gas, and a gas detection signal having an electric quantity level corresponding to the received infrared ray amount is obtained. A light receiving element for outputting and a light receiving element for receiving an infrared ray through a reference filter that allows passage of infrared rays in a wavelength range substantially excluding the wavelength and outputting a reference signal having an electrical level corresponding to the amount of the received infrared ray. At least one of a light receiving unit, a storage unit storing data of control values for prolonging a period of securing a light source output that decreases in response to deterioration of the light source over time, and a period of time, and the gas detection signal and the reference signal A control value is read from the data based on one signal, and the light source is turned on so that the arrival time of the sensor life due to the deterioration of the light source over time is extended by the control value. And Gosuru control means, characterized in that it includes a gas concentration measuring means for measuring the concentration in the air of the detection target gas on the basis of at least the gas detection signal output from the light receiving portion.

  According to the first aspect of the present invention, it is possible to extend the life of the sensor due to the deterioration of the light source over time, thereby extending the service life, and to read out the control value from the data stored in the storage unit. Therefore, the burden on the control means is small.

  According to a second aspect of the present invention, in the first aspect of the invention, the data stored in the storage unit can obtain a predetermined light source output that is lower than the cumulative lighting time and the light source output at the rated lighting at the initial stage. It consists of data indicating the relationship with the applied voltage, and the control means has a measuring function for measuring the cumulative lighting time of the light source based on the reference signal, and the voltage applied to the light source corresponding to the measured cumulative lighting time As a control value from the data in the storage unit, and lighting of the light source is controlled by the voltage.

  According to the second aspect of the present invention, it is possible to extend the lifetime of the light source due to the deterioration of the light source with time, and as a result, it is possible to extend the lifetime of the sensor.

  According to a third aspect of the present invention, in the first aspect of the invention, the data stored in the storage unit is an electric quantity of the reference signal corresponding to a predetermined light source output lower than a light source output at an initial rated lighting. The voltage applied to the light source for obtaining the level is made up of data associated with the number of times of control processing for the light source, and the control means has a function of counting the number of times of control for the light source, and corresponds to the counted number of times of control. A voltage applied to the light source is read out from the data as a control value, and lighting of the light source is controlled by the voltage.

  According to the third aspect of the present invention, it is possible to extend the lifetime of the light source due to the deterioration of the light source with time, and as a result, it is possible to extend the lifetime of the sensor.

According to a fourth aspect of the invention, in the first aspect of the invention, the data stored in the storage unit includes data indicating a relationship between a measured gas concentration and a light source turn-on time and a light turn-off time.
The control means has a function of intermittently lighting the light source, and reads the lighting time and extinguishing time of the light source corresponding to the concentration of the detection target gas measured by the gas concentration measuring means as control values from the data, The lighting of the light source is controlled based on the lighting time and the lighting time.

  According to the invention of claim 4, when the number of times of measurement per fixed time may be small, such as when the concentration of the detection target gas in the atmosphere is low, it is possible to reduce the number of times of lighting of the light source per fixed time, For this reason, the arrival time of the light source lifetime due to deterioration of the light source with time can be delayed, and as a result, the sensor lifetime can be extended.

  According to a fifth aspect of the present invention, in the first aspect of the invention, the data stored in the storage unit is such that the amount of change in the gas concentration of the detection target gas between the previous measurement and the current measurement falls within the threshold value. The control means includes a function for intermittently lighting the light source and the amount of change within the threshold value. A counting function that counts the number of times continuously measured, and reads from the related data as control values the lighting time and extinguishing time of the corresponding light source from the data based on the number of measurements of the counting function, The lighting of the light source is controlled based on the lighting time and the lighting time.

  According to the invention of claim 5, when the change in the gas concentration of the detection target gas is small and the number of times of measurement may be reduced, it is possible to reduce the number of times the light source is turned on per certain time, and therefore the deterioration of the light source over time. As a result, the sensor life can be extended.

  According to a sixth aspect of the invention, in the second or third aspect of the invention, there is provided means for predicting and notifying the arrival of the lifetime based on a relationship between at least a change in the electric quantity level of the reference signal and a light source output. Features.

  According to the invention of claim 6, it is possible for the user to grasp the sensor life, and it is easy to deal with replacement and the like.

  The present invention can extend the life of the sensor due to the deterioration of the light source over time, thereby prolonging the service life. In addition, since the control value is read from the data stored in the storage unit, there is no need to calculate the control value. There is an effect that the burden of the control means is small.

Embodiments of the present invention will be described below.
(Embodiment 1)
FIG. 1 shows the overall configuration of a gas sensor device A of the present embodiment. The sensor head portion 1 of the gas sensor device A absorbs a light source 2 for emitting infrared light and a detection target gas (CO _{2 in the} present embodiment). A light receiving element 31 composed of a pyroelectric element that detects infrared rays and an infrared ray having a wavelength that is not substantially absorbed by the detection target gas, through a filter 31a for selection that allows only infrared rays having a wavelength (4.2 μm to 4.3 μm) to pass through. The light receiving unit 3 includes a light receiving element 31 including a pyroelectric element that detects infrared rays through a reference filter 31b. Between the light source 2 and the light receiving unit 3, an atmosphere including a detection target gas is provided. Air X flows in. The light source 2 is applied with a voltage intermittently at a period of, for example, 1 Hz to 10 Hz in order to detect infrared rays with the light receiving elements 31 and 32 made of pyroelectric elements that respond to the differentiation of the intensity of infrared rays. For example, an incandescent bulb that emits light including infrared light over almost the entire wavelength region (up to 5000 μm) of infrared rays, and the light source output (infrared amount) at the time of lighting is applied voltage. It can be controlled by changing. In FIG. 1, the power supply for applying a voltage to the light source 2 and the operation power supply unit of each unit are not shown.

  Each of the light receiving elements 31 and 32 composed of pyroelectric elements converts the amount of infrared light received intermittently into a voltage level and outputs the voltage level. The signal is A / D converted by the D converter 5 and taken into a signal processing unit 6 including a CPU.

The signal processing unit 6 constitutes a control unit for the entire apparatus together with a light source control unit 8 to be described later. The output signal of the light receiving element 31, that is, the remaining wavelength (4.2 μm to 4.3 μm) absorbed by the detection target gas. ) Is provided with a gas concentration measurement function for measuring the concentration of the gas to be detected in the atmosphere based on the level of the gas detection signal corresponding to the amount of infrared rays. As the selection filter 31a of the present embodiment, a filter that passes a wavelength of, for example, 4.26 μm among the above wavelengths (4.2 μm to 4.3 μm) is used, and corresponds to a wavelength that CO ₂ absorbs. Anything is fine.

  That is, in order to measure the gas concentration, the standard concentration of the detection target gas in the atmosphere and the change in the amount of infrared rays absorbed by the detection target gas are measured using the standard sensor head unit 1. Data indicating the relationship between the concentration of the detection target gas and the voltage level of the gas detection signal created based on the actual measurement data is registered in the storage unit 7, and the signal processing unit 6 outputs the gas output from the light receiving element 31. The detection target gas concentration corresponding to the voltage level of the detection signal is read from the database in the storage unit 7 and the detected gas concentration is output as a measurement result.

  In order to ensure a certain level of accuracy in this measurement process, the amount of infrared rays from the light source 2 must always be above a certain amount, but the amount of infrared rays from the light source 2 (light source output) is as shown in FIG. Since it decreases due to deterioration over time, if the amount of infrared rays is lower than a certain amount, accuracy cannot be ensured and the life of the gas sensor device A will be shortened.

  In FIG. 2C, when the light source 2 is turned on at a rated voltage so that the light source output is 100% at the time of initial lighting (A), an infrared amount of 70% of the rated value can be obtained from the time of initial lighting. The result of measuring the temporal change (deterioration identification) of the light source output when the light source 2 is turned on (b) is shown. As can be seen from this figure, 70% is a light source compared to 100%. The deterioration characteristic of 2 is improved.

  Therefore, in the present embodiment, the amount of infrared rays at the initial time when the rated voltage is applied to the light source 2 is set to 100%, and the light source output capable of achieving the target accuracy is set to 70% of the rated value, for example, and this 70% of infrared rays. The voltage applied to the light source 2 is controlled based on the signal level (reference signal level) of the light receiving element 32 so that the amount can be maintained, and the light source output is set to 70%. A table (data) showing the relationship between the cumulative lighting time and the light source applied voltage at which a light source output of 70% in the cumulative lighting time is obtained in anticipation of a decrease is registered in the storage unit 7 in advance.

  As the light source 2 of the sensor head unit 1 used for creating the table, a light source 2 that falls within an allowable range of characteristic variations is used.

  Here, in order to measure the cumulative lighting time, the signal processing unit 6 of the present embodiment is not affected by the concentration of the detection target gas in the atmosphere, and outputs from the light receiving element 32 according to the lighting of the light source 2. The number of reference signals to be counted is counted by the timer 9, and a function for accumulating the lighting time of the light source based on the count value is provided. That is, since the lighting time of the light source 2 per one time is set in advance under the control of the signal processing unit 6, the cumulative measurement of the lighting time of the light source 2 can be performed from the count value of the reference signal obtained in synchronization with the lighting. It is. Table 1 shows an example of the above table showing the relationship between the count value (cumulative lighting time) and the applied voltage of the light source 2.

  Of course, the light source application voltage of the table varies depending on the type of the light source 2 and the like, and the values shown in the table of Table 1 are merely examples.

  Next, the operation of the gas sensor device A of the present embodiment will be described with reference to the flowchart of FIG. First, when the sensor device A is initially started, a voltage is applied from the light source control unit 8 to the light source 2 based on a control command from the signal processing unit 6, and the light source 2 is turned on (step S1). Here, since the count value of the timer 9 is 0 at the initial start, the control command given from the signal processing unit 6 to the light source control unit 8 corresponds to the count value “0” of the table registered in the storage unit 7. The voltage command is created using the applied voltage of the light source 2 as a control value.

  The infrared light emitted from the light source 2 by turning on the light source 2 is received by the light receiving elements 31 and 32 of the light receiving unit 3 through the filters 31a and 31b, and the amount of infrared light received from the light receiving elements 31 and 32 is set to a voltage level. The gas detection signal and the reference signal converted into are respectively output.

  These signals are amplified by the amplifier circuit 4 (step S2), further A / D converted by the A / D converter 5 (step S3), and taken into the signal processing unit 6.

When the signal processing unit 6 captures the reference signal, the signal processing unit 6 increases the count value of the timer 9, and determines whether or not the count value, that is, the cumulative lighting time is registered in the table. That is, it is determined whether or not adjustment of the applied voltage of the light source 2 is necessary (step 3).
If it is determined that adjustment of the voltage applied to the light source 2 is unnecessary, the signal processing unit 6 reads the gas concentration corresponding to the level of the gas detection signal from the data in the storage unit 7 and determines the measurement gas concentration. The measured gas concentration is output to the outside as a sensor output, and the gas concentration is displayed on, for example, an LCD (step S5). And the data of each voltage level of a reference signal and a gas detection signal are preserve | saved in the memory | storage part 7 (step S6), and the light source control part 8 turns on the light source 2 with the same voltage as last time in step S1.

  On the other hand, if the count value of the timer 9 is registered in the table of the storage unit 7 in step S4, that is, if the accumulated value of the lighting time of the light source 2 indicates that a certain time has elapsed, the light source 2 needs to be adjusted. The signal processing unit 6 makes a determination, reads the light source application voltage registered corresponding to the count value as a control value, and gives a new control command based on the light source application voltage value to the light source control unit 8.

  The light source control unit 8 sets a voltage to be applied to the light source 2 based on this control command, and turns on the light source 2 in step S1 so that the output of the light source 2 becomes 70% of the initial rated lighting.

  In this way, in the present embodiment, by controlling the voltage applied to the light source 2 according to the cumulative lighting time of the light source 2, the light source output, that is, the amount of infrared rays is maintained at 70% of the initial rated lighting and a predetermined value is maintained. The gas detection accuracy is ensured over a long period of time, and the sensor life is extended.

FIG. 3B shows the processing operation of the signal processing unit 6 in step S4 in detail. The reference signal is fetched in step 40 and counted by the timer 9 (step S41). It is determined whether or not the value Xi is a count value registered in the table (step S42).
(Embodiment 2)
In the first embodiment, the cumulative lighting time of the light source 2 is measured by the timer 9, the voltage applied to the light source 2 is set corresponding to the cumulative lighting time, and the light source 2 is turned on, whereby the light source output is initially rated. In this embodiment, the voltage level of the reference signal is maintained at the voltage level of the reference signal corresponding to the light source output of 70% at the time of initial rated lighting. By setting the applied voltage of 2, the light source output is maintained at 70%. As shown in FIG. 4, the timer 9 in FIG. 1 is not provided, and the storage unit 2 has the following table. Is different from the first embodiment.

  That is, the light source 2 is turned on at the rated voltage at the time of initial lighting (the number of times the voltage command is given to the light source control unit 8 so that the light source output becomes 70% as described above, that is, the number of times of light source control is 0). The relationship between the voltage level of the reference signal output from the light receiving element 32 at the time and the light source applied voltage corresponding to the voltage level of the reference signal, which is 70% of the light source output at the time of initial rated lighting, is standard The table at the time of initial lighting (Table 2) created based on the actual measurement data using the sensor head unit 1 is stored in the storage unit 7 and the voltage level of the reference signal is 4.0 (for example, 4.0) for each light source control count. The table (Table 3) which created the light source applied voltage used as V) based on the actual measurement data is stored.

  On the other hand, the signal processing unit 6 reads the number of times the control command is given to the light source control unit 8, that is, the function of counting the number of light source control times, and reads the light source applied voltage value corresponding to the count value from the table of the storage unit 7 as a control value. In addition to the above-described gas concentration measurement function, a control function for giving a control command to the light source controller 8 based on the light source applied voltage is provided.

  The table shown in Table 2 shows only three examples. However, by preparing three or more tables corresponding to the initial variation of the light source 2, it is possible to flexibly cope with variations of individual sensor heads 1. Can do.

  The table shown in Table 3 lists only the light source control count values from “1” to “6”, but it goes without saying that a similar table is prepared for “7” or more. In addition, the level of the reference signal in the table and the light source applied voltage differ depending on the type of the light source 2, and the values shown in the table of Table 3 are merely examples.

  Thus, the gas sensor device A of the present embodiment basically operates based on the flowchart of FIG. At the time of initial start, the light source control unit 8 applies a rated voltage to the light source 2 to light up under the control of the signal processing unit 6.

  When the signal processing unit 6 takes in the reference signal obtained when the light source 2 is turned on for the first time, the light source applied voltage value corresponding to the voltage level of the reference signal is stored in the storage unit 7 as a control value in Table 2. A control command is given to the light source control unit 8 so as to turn on the light source 2 with this light source applied voltage, and the count value of the light source control count is incremented to “1”.

  Thereby, the applied voltage for lighting the light source 2 next is controlled to a voltage at which the light source output becomes 70%, and the light source output (infrared ray amount) becomes 70% at the time of initial rated lighting.

  Thereafter, in the flowchart of FIG. 3, the signal processing unit 6 determines in step S4 whether or not the reference signal from the light receiving element 32 is 4.0 V. If the reference signal is 4.0 V or less, the light source control at that time is determined. Based on the count value of the number of times, the light source applied voltage value is read from the table of Table 3 as a control value, and a control command based on the light source applied voltage value is given to the light source control unit 8 to control the applied voltage of the light source 2.

  Thereby, even if the light source 2 is deteriorated with time, the light source output is controlled so that the reference signal level becomes 4.0 V, that is, the light source output is maintained at 70%. The period during which the detection accuracy can be ensured can be extended, and as a result, the sensor life can be extended.

Since other operations are the same as those in the first embodiment, description thereof is omitted here.
(Embodiment 3)
In the first embodiment, the applied voltage of the light source 2 is controlled and set in accordance with the accumulated value of the lighting time of the light source 2 to maintain the light source output at 70% of the initial rated lighting. In the second embodiment, the reference signal Although the sensor life is extended by controlling and setting the applied voltage to the light source 2 so that the level becomes the reference signal level when the light source output is 70% of the initial rated lighting, Embodiment 1 Alternatively, the sensor life is further increased by limiting the use of the light source 2 in combination with the function 2.

  That is, in the gas sensor device A of the present embodiment, the signal processing unit 6 is provided with a gas concentration measurement function for measuring the concentration of the detection target gas in the atmosphere based on the voltage level of the gas detection signal and the voltage level of the reference signal. When the concentration of the gas to be detected exceeds a predetermined value, or when the gas concentration range requires accurate data, the gas concentration is measured by reducing the turn-off time when the light source 2 flashes once. When the gas concentration measured by increasing the number of points is conversely lower than the predetermined value or within a certain gas concentration range with a certain degree of accuracy, the extinction time of the light source 2 is increased to measure the gas concentration. By reducing the number of points, the use of the light source 2 is restricted, thereby delaying the deterioration of the light source 2 and extending the life, and as a result, the sensor life is extended. For the voltage control function for the light source 2 used in combination with the present embodiment, refer to the description of the configuration and operation of the first or second embodiment described above, and the description is omitted here.

  Thus, in the gas sensor device A of the present embodiment, a table (see Table 4) indicating the relationship between the concentration of the detection target gas in the atmosphere and the blinking method of the light source 2 is registered in the storage unit 7 in advance, and the signal processing unit 6 compares the gas concentration measured by the gas concentration measurement function with the contents of the table, determines the light source blinking method, and uses the lighting time and extinguishing time indicated in this light source blinking method as control values. Has a function to give control commands.

  That is, the signal processing unit 6 collates the measured gas concentration with the contents of the table, and if the measured gas concentration is in the range of 0 to 500 ppm, the signal processing unit 6 blinks the light source 2 with each of the lighting time and the lighting time being 1 second. If the control command based on the light source blinking method is 500 ppm to 2000 ppm, the control command based on the light source blinking method for blinking the light source 2 by turning on for 1 second and turning off for 5 seconds is given to the light source control unit 8. That is, the number of times the light source 2 is turned on in a certain time of the light source 2, that is, the lighting cycle is controlled by the measured gas concentration. Gas concentration measurement is performed in the same manner as in the first and second embodiments.

  Next, operation | movement of the gas sensor apparatus A of this embodiment is demonstrated based on the flowchart of FIG.

  When the gas sensor device A starts operating, the light source 2 is turned on at a predetermined voltage set by the light source control unit 8 under the control of the signal processing unit 6 in step S11 as shown in FIG. 5 (step S11). In step S12, the gas detection signal and the reference signal output from each of the light receiving elements 31 and 32 of the light receiving unit 3 are amplified, and after A / D conversion in step S13, the signal processing unit 6 performs the first embodiment in step S14. Alternatively, the gas concentration is measured in the same manner as 2 and the measurement result is output to the outside as a sensor output. Further, after the voltage value data of each detection signal is stored in the storage unit 7 in step S15, the measured gas concentration Is determined in step S16, the necessity of adjustment of the light source 2 is determined in step S16, and the current light source blinking method needs to be changed. Based on the control value registered in the light source flashes method in the table corresponding to the range of gas concentration is to control command to the light source control unit 8. Receiving this command, the light source controller 8 changes the light source blinking method for the light source 2 in step S17 and turns on the light source 2 in step S11.

  On the other hand, when there is no need to change the current light source blinking method, a new control command is not given, so the light source control unit 8 maintains the control by the current light source blinking method and returns to step S11.

  FIG. 6 shows an example of the temporal change in the measured gas concentration. When the above gas concentration of 500 ppm is used as a threshold and the measured gas concentration exceeds this threshold, the turn-off time of the light source 2 is shortened as described above. In addition, the lighting of the light source 2 is controlled to increase the number of measurement points, and the response speed is increased. On the other hand, if it is less than the threshold value, the light source 2 is turned off for a longer time to reduce the number of measurement points, and the use of the light source 2 is restricted.

  As described above, in the present embodiment, since the use of the light source 2 is restricted by changing the lighting cycle of the light source 2 according to the concentration of the detection target gas in the atmosphere, deterioration of the light source 2 can be delayed. And by using together with the function which controls an applied voltage, a sensor lifetime can be extended significantly compared with Embodiment 1,2.

  The function of controlling the applied voltage of the light source 2 of Embodiment 1 or 2 is not used in combination, and the function of changing the lighting cycle of the light source 2 according to the gas concentration alone delays the deterioration of the light source 2 and consequently extends the sensor life. You can also. In this case, since the reference signal level decreases due to the deterioration of the light source 2 over time, the gas concentration is detected from the voltage level difference between the reference signal and the gas detection signal based on the voltage level of the reference signal, and based on actual measurement in advance. What is necessary is just to determine the density | concentration of the detection target gas in atmosphere based on the table which shows the relationship between the level difference value of both signals stored, and gas concentration.

(Embodiment 4)
In the third embodiment, by controlling the turn-off time (turn-on cycle) of the light source 2 based on the detection gas concentration range, the use of the light source 2 is restricted unnecessarily, and the deterioration of the light source 2 over time is delayed. However, in this embodiment, when the detected gas concentration does not change continuously, the life of the light source 2 is shortened by reducing the number of times the light source 2 blinks, that is, by increasing the lighting cycle. In the same manner as in the third embodiment, the function for controlling the voltage applied to the light source 2 in the first or second embodiment is used in combination.

  Thus, in the gas sensor device A of the present embodiment, the storage unit 7 stores in the table the relationship between the amount of change in the concentration of the detection target gas in the atmosphere, the duration, and the blinking method of the light source 2 (see Table 5). Is stored in advance, and the signal processing unit 6 has a function of counting the number of times the change amount of the gas concentration measured based on the contents of the table is continuously measured within a predetermined threshold, and the number of changes and the amount of change. And the contents of the table are collated to read the lighting time and extinguishing time registered in the corresponding light source blinking method as control values, and to give a control command to the light source control unit 8 based on the control values ing.

  That is, the signal processing unit 6 stores the gas concentration in the storage unit 2 every time it measures the gas concentration, obtains the difference (gas change amount) between the stored previous gas concentration and the current measured gas concentration, and changes the gas If the amount is less than a threshold value (for example, 100 ppm), a process for increasing the count value is performed, and if the count value is less than 10 by comparing the count value when the amount is increased, the corresponding light source blinks. Based on the method, that is, the method in which the light source 2 is turned on for 1 second and then turned off for 1 second, and in the case of 10 or more, the gas change amount is calculated based on the method in which the light source 2 is turned on for 1 second and then turned off for 5 seconds. In the case of 100 ppm or more, regardless of the count value, a control command for controlling the light source 2 is given to the light source controller 8 based on a method of turning on the light source 2 for 1 second and then turning it off for 1 second. That is, the lighting cycle of the light source 2 is controlled based on the change amount of the detected gas concentration. The gas concentration measurement function of the signal processing unit 6 of this embodiment uses the same function as in the first and second embodiments.

  Next, operation | movement of the gas sensor apparatus A of this embodiment is demonstrated. The basic operation of the gas sensor device A of the present embodiment is based on the flowchart of FIG. 5, but the difference is that the determination process for adjusting the light source 2 is performed based on FIG. 7. The processing that becomes a point will be described in detail.

  In the present embodiment, after the reference signal level and the gas detection signal level data are stored in the storage unit 7 under the control of the signal processing unit 6 in step S15 in FIG. 6, the signal processing unit 6 is stored in the storage unit 7. The difference between the previous measured gas concentration data stored and the current measured gas concentration is obtained, and whether or not the difference, that is, the change amount of the gas concentration is less than 100 ppm is determined in step S161. The count value N of the built-in counter of the processing unit 6 is incremented by “1” (step S162). In the next step S163, it is determined whether or not the count value N is 10 or more. The corresponding light source blinking method is read from the table 7 (step S163), and a control command is given to the light source control unit 8 based on the control value indicated by the light source blinking method in step S17 of FIG. The light source blinking method in this case is 1 second on and 1 second off, and the light source controller 8 applies a predetermined voltage to the light source 2 in step S1 based on the control command to turn on the light source 2.

  On the other hand, if it is determined in step S162 that the count value N is 10 or more, the signal processing unit 6 reads the corresponding light source blinking method from the table in the storage unit 7 (step S165). Based on the control value indicated by this light source blinking method, a new control command is given to the light source controller 8 in step S17. The light source blinking method in this case is lighting for 1 second and turning off for 5 seconds, and the light source control unit 8 applies a predetermined voltage to the light source 2 in step S1 based on this control command to turn on the light source 2.

  If it is determined in step S161 that the gas concentration change amount is 100 ppm or more, the signal processing unit 6 resets the count value N in step S166 and then reads the corresponding light source blinking method from the table in the storage unit 7. A control command based on the light source blinking method is given to the light source control unit 8 in step S17. The light source blinking method in this case is 1 second on and 1 second off, and the light source controller 8 applies a predetermined voltage to the light source 2 in step S1 based on the control command to turn on the light source 2.

  Before returning to step S1, the signal processing unit 6 updates the previous measurement gas concentration data stored in the storage unit 7 with the current measurement gas concentration data, and determines the previous measurement gas when calculating the next gas change amount. Used as concentration data.

  As described above, in the present embodiment, the stable mode is applied in which the lighting cycle of the light source 2 is extended when the amount of change in the measurement gas concentration continuously changes within a certain range. On the other hand, when the amount of change changes by more than a certain value, or when the amount of change is not within a certain range, the change in the measured gas concentration is stabilized by applying the normal mode in which the lighting cycle of the light source 2 is shortened. It is possible to delay the deterioration of the light source 2 by restricting the lighting of the light source 2 in a state where the light source 2 is in operation. And by using together with the function which controls an applied voltage, a sensor lifetime can be extended significantly compared with Embodiment 1,2.

Note that the function of controlling the applied voltage of the light source 2 of Embodiment 1 or 2 is not used in combination, and only the function of changing the lighting cycle of the light source 2 according to the amount of change in gas concentration delays the deterioration of the light source 2, resulting in sensor life. Can be extended. In this case, since the reference signal level decreases due to the deterioration of the light source 2 over time, the gas concentration is detected from the voltage level difference between the reference signal and the gas detection signal based on the voltage level of the reference signal, and based on actual measurement in advance. What is necessary is just to determine the density | concentration of the detection target gas in atmosphere based on the table which shows the relationship between the level difference value of both signals stored, and gas concentration.
(Embodiment 5)
The present embodiment can be applied to the first or second embodiment, and predicts that the lifetime is approaching from the limit point where a predetermined amount of infrared rays cannot be obtained even if the voltage applied to the light source 2 is increased. It is characterized in that when the end of life is reached, it is detected and the end of life is displayed.

  That is, in the first or second embodiment, the display unit 11 controlled by the signal processing unit 6 is provided as shown in FIG. 8, and the reference signal level at the end of life shown in FIG. The reference signal level at the limit point at which the sensor life can be predicted to approach and the reference signal level at the end of the life are preliminarily registered in the storage unit 7 as the life warning level LA and the life level LB, respectively. The unit 6 compares the level of the reference signal fetched from the light receiving element 32 with the life warning level LB and the life warning level LA. When the level of the reference signal reaches the life warning level LA, the signal processing unit 6 approaches the sensor life. Is displayed on the display unit 11, and when the level of the reference signal reaches the life level LB, the display unit 11 indicates that the life has come. Cause shown.

  Thereby, in the gas sensor device A of the present embodiment, it is possible to notify the user accurately of the early notice of the life and the fact that the life has come. Since the operation for extending the sensor life is the same as that in the first or second embodiment, the description is omitted here, and the configuration of the entire apparatus is not shown.

  When the voltage level applied to the light source 2 reaches a controllable maximum value, the signal processing unit 6 determines that the life is approaching, and makes a life warning on the display unit 11, and then the reference signal level is set to a predetermined level. It may be determined that the service life is reached when the battery life is lowered, and the service life notification may be performed on the display unit 11.

  Further, even when the applied voltage of the light source 2 is not controlled, if the correlation data between the decrease in the level of the reference signal and the life of the light source 2 is obtained by actual measurement, the life warning display and the life display can be similarly performed. Become.

1 is a configuration diagram of Embodiment 1. FIG. (A) is a timing chart of the lighting operation of the light source of the first embodiment, (b) is an explanatory diagram of the change over time of the output of the light source of the first embodiment, and (c) is the rate of light source output and the time course of the first embodiment. It is explanatory drawing of a change. FIG. 2 is a flowchart for explaining the operation of the first embodiment, where (a) is an overall flowchart, and (b) is a flowchart of a main part. 6 is a configuration diagram of Embodiment 2. FIG. 10 is an overall flowchart for explaining the operation of the third embodiment. FIG. 10 is a transition diagram of measurement gas concentration for explaining operation of the third embodiment. 10 is a flowchart of the main part for explaining the operation of the fourth embodiment. FIG. 10 is a configuration diagram of a main part of a fifth embodiment. It is explanatory drawing of the lifetime warning of Embodiment 5, and the detection of a lifetime.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sensor head 2 Light source 3 Light receiving part 31 Light receiving element 31a Selection filter 32 Light receiving element 32a Reference filter 4 Amplifying circuit 5 A / D converter 6 Signal processing part 7 Storage part 8 Light source control part 9 Timer A Gas sensor apparatus

Claims (6)

A light source that outputs infrared light when lit,
Among the infrared rays output from the light source, the infrared rays are received through a selection filter that passes only the infrared rays having a wavelength absorbed by the detection target gas, and a gas detection signal having an electric quantity level corresponding to the received infrared ray amount is obtained. A light receiving element for outputting and a light receiving element for receiving an infrared ray through a reference filter that allows passage of infrared rays in a wavelength range substantially excluding the wavelength and outputting a reference signal having an electrical level corresponding to the amount of the received infrared ray. A light receiver;
A storage unit storing control value data for prolonging a period of ensuring a predetermined level or more of a light source output that decreases in response to deterioration with time of the light source;
A control value is read from the data based on at least one of the gas detection signal and the reference signal, and lighting of the light source is controlled by the control value so that the arrival time of the sensor life due to deterioration of the light source with time is extended. Control means to
A gas sensor device comprising: gas concentration measuring means for measuring the concentration of the detection target gas in the air based on at least a gas detection signal output from the light receiving unit. The data stored in the storage unit consists of data indicating the relationship between the cumulative lighting time and the light source applied voltage that provides a predetermined light source output lower than the light source output at the initial rated lighting,
The control unit has a measurement function of measuring the cumulative lighting time of the light source based on the reference signal, and reads out a voltage applied to the light source corresponding to the measured cumulative lighting time as a control value from the data in the storage unit. The gas sensor device according to claim 1, wherein lighting of the light source is controlled by the voltage. The data stored in the storage unit is a control process for the light source that is applied to a light source that can obtain an electrical quantity level of the reference signal corresponding to a predetermined light source output lower than the light source output at the rated lighting at the initial stage. It consists of data associated with the number of times,
The control means has a function of counting the number of times of control for the light source, reads an applied voltage of the light source corresponding to the counted number of times of control as a control value from the data, and controls lighting of the light source by the voltage. The gas sensor device according to claim 1, wherein The data stored in the storage unit consists of data indicating the relationship between the measured gas concentration and the lighting time and extinguishing time of the light source,
The control means has a function of intermittently lighting the light source, and reads the lighting time and extinguishing time of the light source corresponding to the concentration of the detection target gas measured by the gas concentration measuring means as control values from the data, 2. The gas sensor device according to claim 1, wherein lighting of the light source is controlled based on the lighting time and the lighting time. The number of times that the data stored in the storage unit is continuously measured when the amount of change in the gas concentration of the detection target gas between the previous measurement and the current measurement is within the threshold value, Consists of data showing the relationship between the light source turn-on time and the turn-off time,
The control means has a function of intermittently lighting the light source and a counting function for counting the number of times the change amount is continuously measured within the threshold, and based on the number of measurements of the counting function, from the data 2. The gas sensor device according to claim 1, wherein the corresponding light source lighting time and light extinguishing time are read from the relational data as control values, and the lighting of the light source is controlled based on the lighting time and light extinguishing time. 4. The gas sensor device according to claim 2, further comprising means for predicting and notifying the end of life based on a relationship between at least a change in an electric quantity level of the reference signal and a light source output.

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