JP6826814B2 - Optical physical quantity measuring device and its light source control method - Google Patents

Description

The present invention relates to an optical physical quantity measuring device and a method for controlling a light source thereof. More specifically, the quantity and density of molecules to be measured in a medium can be measured with high accuracy immediately after the start or restart of the operation of the measuring device main body. The present invention relates to an optical physical quantity measuring device and a method for controlling a light source thereof.

Conventionally, a method of measuring the quantity and density of measurement target molecules in a medium by using absorption, diffraction, scattering, etc. of light such as infrared rays, ultraviolet rays, and X-rays is known.
For example, as a gas concentration measuring device for measuring the concentration of a gas to be measured using an infrared light source, a non-dispersive infrared gas concentration measuring device is known. The non-dispersed infrared absorption type gas concentration measuring device utilizes the fact that the wavelength of infrared rays absorbed differs depending on the type of gas, and measures the gas concentration by detecting the absorbed amount.
As a gas concentration measuring device using this principle, for example, a filter (transmissive member) that transmits infrared rays limited to a wavelength in which the measurement target gas has absorption characteristics and an infrared sensor are combined to absorb infrared rays absorbed by the measurement target gas. Examples include devices configured to measure the concentration of gas by measuring the amount.

Further, a carbon dioxide concentration measuring device to which this principle is applied is disclosed in Patent Document 1. The carbon dioxide concentration measuring device disclosed in Patent Document 1 is a wavelength range in which infrared rays are not absorbed by the measurement target gas (hereinafter, referred to as "non-absorption band by measurement target gas" or simply "non-absorption band". A reference filter that selectively transmits infrared rays (there is) and a wavelength range in which infrared rays are absorbed by the measurement target gas (hereinafter, may be referred to as "absorption band by measurement target gas" or simply "absorption band". ), A plurality of infrared detection elements each having a measurement filter that selectively transmits infrared rays are arranged, and the measurement target gas is detected and the concentration is measured based on the output signal from each infrared detection element.
It is described in Patent Document 1 that such a carbon dioxide concentration measuring device and a carbon dioxide detecting method can improve detection accuracy and output stability. Hereinafter, the apparatus and method for measuring the gas concentration including carbon dioxide gas are collectively referred to as a gas concentration measuring apparatus and a gas concentration measuring method.

For example, the operating principle of the carbon dioxide concentration measuring device disclosed in Patent Document 1 applies the difference in the degree of absorption depending on the wavelength to carbon dioxide detection. In the infrared rays radiated from the ceramic heater as a light source, the infrared rays having a wavelength of about 4.3 μm are absorbed by the carbon dioxide gas in the gas container, and the radiant intensity is lowered. On the other hand, infrared rays having a wavelength of around 3.9 μm are not absorbed by carbon dioxide gas, and their radiant intensity does not decrease. Then, from infrared rays containing different wavelengths that have passed through the gas container of the gas measuring device, two waves having a wavelength of 4.3 μm and a wavelength of 3.9 μm are transmitted by two types of optical filters having a pass band corresponding to each of the two waves. Filter wave selection. The concentration of carbon dioxide in the gas container is calculated based on the radiant intensity of each of these infrared rays having different wavelengths.
The radiation intensity distribution of the ceramic heater includes the infrared absorption spectrum of carbon dioxide gas, is broad in the wavelength region of 2 μm to 50 μm, and has sufficient radiation intensity in the wavelength region near the infrared absorption spectrum of carbon dioxide gas. Therefore, the detection accuracy and output stability of the gas measuring device using the ceramic heater as the light source are improved.

Japanese Unexamined Patent Publication No. 9-33431

For example, the non-dispersed infrared absorption type gas concentration measuring device according to the prior art operates a light source by various methods and uses a signal detected by an infrared detection unit. At this time, for example, the maximum value of the signal detected from the infrared detector while the light source is lit for a predetermined time and the signal detected from the infrared detector during the predetermined period when the light source is lit are integrated. The value and the signal detected by the infrared detection unit after a lapse of a predetermined time from the start of lighting of the light source are used.
Further, in the actual use of the gas concentration measuring device, power consumption is consumed by periodically blinking the light source or periodically changing the emission intensity of the light source according to the required update speed of the gas concentration measurement result. Can be reduced. The power consumption can be reduced by this periodic operation, for example, by alternately repeating the off state in which the power supply is cut off and the on state in which the power is supplied under a certain predetermined drive condition, and instead of the above-mentioned turn-off state. It can also be achieved by alternately repeating the state of supplying power under certain other predetermined drive conditions.

However, the light source generates heat in response to the supply of electric power, and the temperature of the light source changes with time. At this time, the amount and spectrum of infrared rays output from the light source also change due to the temperature change of the light source. At this time, when an incandescent light bulb, a ceramic heater, or a MEMS (Micro Spectrum Mechanical Systems) heater is used as a light source, light is emitted as blackbody radiation from the light source which is also a heat source, so that the temperature change of the light source is in principle. The amount of light and the spectrum will change.

Further, when a mercury lamp is used as a light source, the vapor pressure of mercury in the lamp changes when the temperature around the light source changes. Therefore, when an LED or the like made of a semiconductor material is used as a light source, the semiconductor is used. Depending on the temperature characteristics, the temperature characteristics as a light source appear, and the amount of light and the spectrum change.
When the above-mentioned periodic operation is repeated for a sufficient time under a fixed period, for example, when the periodic operation is a blinking operation, the temperature of the light source immediately after the start of lighting, the amount of infrared light, and the spectrum become the same values for each cycle. , It is expected that the amount and spectrum of infrared rays output from the light source will be the same each time after a certain period of time has passed from the start of each lighting, but immediately after the blinking operation starts from the state where the light source is sufficiently cold, etc. It cannot be expected that the above-mentioned physical quantities will be the same value every time. Therefore, some measures are required to accurately calculate the gas concentration immediately after the start of operation of the gas concentration measuring device.

These issues are not limited to non-dispersive infrared absorption type gas concentration measuring devices, but are physical quantity measuring devices that have a light source and measure the quantity and density of molecules to be measured in a medium by using light absorption, diffraction, scattering, etc. In addition, the medium to be measured is also common regardless of the gas phase, liquid phase, or solid phase.
The present invention has been made in view of such a problem, and an object of the present invention is to measure the quantity and density of measurement target molecules in a medium with high accuracy immediately after the start or restart of the operation of the measuring device main body. It is an object of the present invention to provide an optical physical quantity measuring device capable of the present invention and a method for controlling a light source thereof.

The first aspect of the present invention is an optical physical quantity measuring device that drives a light source housed in a device main body to periodically turn on and off, and measures a signal corresponding to the light output by the light source. Based on the measurement output from the measurement light detection unit that outputs as an output, the light source state detection unit that acquires the state of the light source, the light source control unit that controls the driving state of the light source, and the measurement output from the measurement light detection unit. A calculation unit for calculating the quantity or density of the molecule to be measured is provided, and the light source state detection unit is provided between the light source and the light source control unit to acquire a resistance value of the light source and obtain the resistance. The state of the light source is acquired by comparing the value with the reference resistance value, and when the light source control unit drives the light source in a preset period, the resistance value is the reference resistance. The light source is continuously kept lit while it is smaller than the value, the light source is turned off when the resistance value becomes equal to or higher than the reference resistance value, and the light source is turned on after a predetermined time has elapsed from the turning off of the light source. After that, the light source is driven to be turned on and off periodically .
A second aspect of the present invention is a light source control method for an optical physical quantity measuring device that drives a light source to be turned on and off periodically, in the nth (n is an integer of 1 or more) period. By acquiring the resistance value of the light source at a predetermined timing during the period of the first step of turning on the light source at the start and the period of the first step, and comparing the acquired resistance value with the reference resistance value. While the second step of acquiring the state of the light source and the state of the light source acquired in the second step are smaller than the reference resistance value, the light source is continuously maintained in the lit state. A third step of turning off the light source when the resistance value becomes equal to or higher than the reference resistance value, and when the light source is turned off in the third step, the light source is turned off after a predetermined time has elapsed from the turning off of the light source. It has a fourth step of turning on and off, and after the fourth step, the light source is driven so as to be turned on and off periodically .

According to one aspect of the present invention, an optical physical quantity measuring device and a light source control method thereof capable of measuring the quantity and density of measurement target molecules in a medium with high accuracy immediately after the operation of the physical quantity measuring device is started or restarted. Can be realized.

It is a block diagram for demonstrating Embodiment 1 of the optical physical quantity measuring apparatus which concerns on this invention. It is a block diagram for demonstrating Embodiment 2 of the optical physical quantity measuring apparatus which concerns on this invention. It is a figure which shows the flowchart for demonstrating the physical quantity measuring method of the physical quantity measuring apparatus in this embodiment. (A) to (d) are diagrams showing actual measurement data showing the superiority of the light source control method possessed by the physical quantity measuring device in the present embodiment. It is a figure which shows the flowchart for demonstrating another physical quantity measuring method of the physical quantity measuring apparatus in this embodiment.

The following detailed description describes many specific specific configurations to provide a complete understanding of embodiments of the present invention. However, it will be clear that other embodiments can be implemented without being limited to such specific specific configurations. In addition, the following embodiments do not limit the invention according to the claims, but include all combinations of characteristic configurations described in the embodiments.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
<Embodiment 1>
FIG. 1 is a configuration diagram for explaining the first embodiment of the optical physical quantity measuring device according to the present invention.
As shown in FIG. 1, the optical physical quantity measuring device 100 according to the first embodiment is an optical physical quantity measuring device 100 (which periodically drives a light source 101 housed in the device main body using a plurality of driving conditions. Hereinafter, it is simply referred to as a physical quantity measuring device).
The measurement light detection unit 102 outputs a signal corresponding to the light output by the light source 101 as a measurement output. The light source state detection unit 105 acquires the state of the light source 101. The light source control unit 103 controls the driving state of the light source 101. The calculation unit 104 calculates the quantity or density of the molecule to be measured based on the measurement output from the measurement light detection unit 102.

Further, the light source control unit 103 controls the power supply state to the light source 101 under a plurality of drive conditions by a command from the calculation unit 104, and supplies power according to the light source state acquired from the light source state detection unit 105. Control the state. Further, the calculation unit 104 periodically drives the light source 101 via the light source control unit 103.
The light source control method of the optical physical quantity measuring device according to the present invention is a light source control method of the optical physical quantity measuring device that periodically drives the light source 101 using a plurality of driving conditions, and the nth (n is 1 or more). A first step of driving the light source 101 under a predetermined driving condition at the start of the (integer) cycle, a second step of acquiring the state of the light source 101 at a predetermined timing during the period of the first step, and a second step. It has a third step of determining whether to continue or end the driving by the first step based on the state of the light source 101 acquired in the step of.

Further, the driving condition of the light source 101 executed at the start of the nth (n is an integer of 1 or more) period is one of a plurality of driving conditions. Further, in the second step, the state of the light source 101 is acquired based on the resistance value of the light source 101. Further, in the second step, the state of the light source 101 is acquired based on the output of the reference light detection unit (not shown). Further, n may be 1.
That is, at the start of the nth (n is an integer of 1 or more) period, the first step of driving the light source 101 and the first step of the first step, which are executed one or more times under one or more kinds of predetermined driving conditions. The second step, which is executed once or more to acquire the state of the light source 101 at a predetermined timing during the period, and the driving by the first step are continued based on the state of the light source 101 acquired in the second step. The drive of the light source 101 is controlled using a third step, which is performed one or more times to determine whether to do or end.

First, here, "driving the light source" means a state in which electric power is supplied to the light source 101. This power supply may be performed by current control or voltage control.
Further, "driving the light source periodically" means that the period for driving the light source 101 is repeated a plurality of times under a plurality of driving conditions of two or more types. Here, the drive conditions are the magnitude (including 0) of the electric power, voltage, or current supplied or applied to the light source 101, and the supply time or application time. The plurality of driving conditions of two or more types may be two types, a condition for supplying constant power and a condition for not supplying power. In this case, the light source 101 can be intermittently driven by alternately repeating these two types of driving conditions.

Further, the "cycle" is defined as "1 cycle" when the light source 101 is driven by a plurality of driving conditions, after a change in a certain driving condition until the same change as the change in the driving condition occurs. Is what you do. In the case of the intermittent drive described above, the total period of the period for supplying power to the light source 101 and the period for not supplying power is “1 cycle”. The "cycle" referred to here does not necessarily mean that the time interval of each cycle is constant, and the light source 101 may be driven at different time intervals for each cycle. Further, the "light source state" can be acquired by the method described later.

The medium containing the molecule to be measured can flow in or be arranged at least between the light source 101 in the physical quantity measuring device 100 and the photodetector 102 for measurement. Here, inflow or disposition means that the light output from the light source 101 acts on the medium, and the light itself, the excitation light, the scattered light, or the reflected light can reach the measurement light detection unit 102. It means that there is.
When the medium is a solid phase, it may be placed between the light source 101 and the photodetector 102 for measurement. When the medium is a gas phase, it may be enclosed in an appropriately closed space including the light source 101 and the measurement light detection unit 102, or between the light source 101 and the measurement light detection unit 102. The medium may flow directly into the space, or it may be placed in a container having sufficient transparency to the light used for measurement and then placed between the light source 101 and the light detection unit 102 for measurement. good. When the medium is a liquid phase, the medium may be placed in a container having sufficient transparency to the light used for measurement, and then the container may be placed between the light source 101 and the light detection unit 102 for measurement.

The light source 101 is not particularly limited as long as the light detection unit 102 for measurement can output light including a wavelength band having sensitivity and includes the wavelength band of light absorbed by the molecule to be measured. For example, when infrared rays are used for measurement, incandescent lamps and ceramic heaters, MEMS (Micro Electro Electrical Systems) heaters and infrared LEDs (Light Emitting Video) are used. For example, when ultraviolet rays are used for measurement, mercury lamps and ultraviolet LEDs are used. For example, when X-rays are used for measurement, an electron beam, an electron laser, or the like can be used as the light source 101. In the first embodiment, the light source 101 may include a drive circuit thereof, and may include functions for controlling the output such as lighting, extinguishing, and adjusting the output intensity.

The measurement light detection unit 102 outputs a measurement output according to the light output by the light source 101. The measurement light detection unit 102 may detect the light including the band that acts on the molecule to be measured among the light output by the light source 101, and output the photoelectric conversion measurement output to the calculation unit 104.
Further, the measurement light detection unit 102 is not particularly limited as long as it has the above-mentioned characteristics. For example, when infrared rays are used for measurement, the optical detection unit 102 for measurement includes a thermal infrared sensor such as a pyrolectric sensor, a thermopile, or a bolometer, or a quantum such as a diode or a phototransistor. A type infrared sensor or the like is suitable. Further, for example, when ultraviolet rays are used for measurement, a quantum type ultraviolet sensor such as a diode or a phototransistor is suitable. Further, for example, when X-rays are used for measurement, various semiconductor sensors are suitable.

The calculation unit 104 can periodically drive the light source 101 via the light source control unit 103, and at the start of the nth (n is an integer of 1 or more) period, one or more predetermined driving conditions are applied. A first step of driving the light source, which is executed one or more times, and a second step, which is executed once or more, of acquiring the state of the light source at a predetermined timing during the period of the first step. , The third step, which is executed one or more times, determines whether to continue or end the driving by the first step based on the state of the light source acquired in the second step. Especially if the drive can be controlled and the quantity and density of the molecules to be measured in the medium can be calculated using the measurement output acquired from the light detection unit 102 for measurement and the conversion formula prepared in advance. Not limited.

The light source state detection unit 105 is not particularly limited as long as it can acquire the state of the light source 101. For example, as shown in FIG. 1, a light source state detection unit 105 may be provided between the light source 101 and the light source control unit 103 to acquire the state of the light source 101 based on the resistance value of the light source 101. In this case, the resistance value of the light source 101 may be acquired by detecting the voltage between the terminals of the light source 101 and the current flowing through the light source 101. Further, when the light source 101 is driven by a constant current, the resistance value of the light source 101 may be acquired by detecting the voltage between the terminals of the light source 101. Similarly, when the light source 101 is driven by a constant voltage, the resistance value of the light source 101 may be acquired by detecting the current flowing through the light source 101.

<Embodiment 2>
FIG. 2 is a configuration diagram for explaining the second embodiment of the optical physical quantity measuring device according to the present invention. The difference from the first embodiment shown in FIG. 1 is that in the second embodiment, the light source state detection unit 105 sets the wavelength band of the light output from the light source 101 to a wavelength band different from that of the measurement light detection unit 102. The point is that the state of the light source 101 is acquired based on the output of the sensitive reference photodetector (not shown).
That is, in the second embodiment, for example, as shown in FIG. 2, the reference light detection unit having sensitivity in a wavelength band different from that of the measurement light detection unit 102 among the light output from the light source 101. The state of the light source 101 may be acquired based on the output. The wavelength band in which the reference photodetector has sensitivity may be matched in a band that does not affect the measurement target gas. Further, the state of the light source 101 may be acquired based on the resistance value of the light source 101 and the output of the reference light detection unit.

Similar to the measurement light detection unit, the reference light detection unit includes a thermal infrared sensor such as a pyrolectric sensor, a thermopile, and a bolometer, and a quantum type such as a diode and a phototransistor. An infrared sensor or the like is suitable. Further, for example, when ultraviolet rays are used for measurement, a quantum type ultraviolet sensor such as a diode or a phototransistor is suitable. Further, for example, when X-rays are used for measurement, various semiconductor sensors are suitable.

Further, as a method for determining whether to continue or end the driving by the first step based on the state of the light source 101, the following method can be given as an example, but the method is not particularly limited to this method.
For example, when the state of the light source 101 is acquired based on the resistance value of the light source 101, the light source resistance value increases due to the driving of the light source 101, or the light source resistance value becomes equal to or higher than the reference resistance value prepared in advance. The drive by the first step may be terminated, and when the light source resistance value is reduced by the drive of the light source 101, the first step is performed when the light source resistance value is equal to or less than the reference resistance value prepared in advance. The drive may be terminated. This reference resistance value may be arbitrarily determined for each individual device when calibrating the physical quantity measuring device.

Further, for example, when the state of the light source 101 is acquired based on the output of the reference light detection unit, and the output of the reference light detection unit is increased by driving the light source 101, the output of the reference light detection unit is output. The drive by the first step may be terminated when the reference output value or more prepared in advance is exceeded, or when the output of the reference light detection unit is reduced by driving the light source 101, the reference light detection unit The drive by the first step may be terminated when the output of is equal to or less than the reference output value prepared in advance, or when the output of the reference light detection unit increases or decreases due to the drive of the light source 101, refer to. The drive by the first step may be terminated when the output of the light source detection unit matches the reference output value prepared in advance or when the predetermined range before and after that is reached. The reference output value and the predetermined range may be arbitrarily determined for each individual device when calibrating the physical quantity measuring device.

The light source control unit 103 can control the power supply state to the light source 101 under a plurality of drive conditions by a command from the calculation unit 104, and the power is supplied according to the light source state acquired from the light source state detection unit 105. There is no particular limitation as long as the supply state can be controlled. As the light source control unit 103, for example, an analog IC, a digital IC, a CPU (Central Processing Unit), or the like is suitable. The light source control unit 103 may be included in the calculation unit 104 or the light source 101 itself.

Here, for the sake of simplicity, consider a case where the physical quantity measuring device 100 is a gas concentration measuring device using infrared rays, an incandescent light bulb is used as the light source 101, and the light source 101 is blinked at regular intervals. In this blinking operation, power is supplied by constant current drive when it is lit, and power is cut off when it is turned off. That is, the light source control unit 103 considers a case where the light source 101 is controlled by alternately repeating the drive condition for cutting off the power supply and the drive condition for supplying the power by the constant current drive at regular intervals.

When the power supply to the light source 101 is started at the time of lighting, the filament temperature of the incandescent light bulb which is the light source 101 (hereinafter referred to as "light source temperature") rises with time, and the amount of infrared light output from the light source 101 also increases with the light source temperature. Rise. This increase in the light source temperature and the infrared output continues until the power supplied to the light source 101 and the power released due to the infrared output and heat absorption by the ambient environment match. That is, the light source temperature is in the process of raising the temperature during lighting. Further, when the power is turned off, the power supply to the light source 101 is cut off, and when the light source is turned off, the light source temperature gradually decreases until it matches the ambient temperature. That is, while the light is off, the light source temperature is in the cooling process.

If the cooling process is long enough and the light source temperature is cooled until it matches the ambient environment temperature each time, the light source temperature at the start of lighting the light source is after repeating driving periodically for a sufficiently long time (hereinafter, steady). The same light source temperature is used immediately after the start of the periodic drive or immediately after the restart of the periodic drive (hereinafter collectively referred to as the start of the drive) from the state where the drive has been stopped for a time sufficiently longer than the extinguishing time during the steady drive. It becomes.
However, if the cooling process is not long enough to be cooled until the light source temperature matches the ambient environment temperature, the light source temperature at the start of the second and subsequent lightings will be higher than the ambient environment temperature. The light source temperature at the start of lighting gradually rises by repeating intermittent driving, and eventually converges to the light source temperature at the start of lighting during steady driving. If the driving conditions in the lighting state of the intermittent drive are the same each time, the difference in the light source temperature at the start of lighting is the difference in the light source temperature after a certain time has passed from the start of lighting, that is, the amount of infrared light output from the light source 101. And it appears as a difference in spectrum.

As described above, in the non-dispersed infrared absorption type gas concentration measuring device according to the prior art, for example, the maximum value of the signal detected from the infrared detection unit while the light source is lit for a predetermined time, or the light source is lit. A value obtained by integrating the signals detected by the infrared detection unit during a predetermined period of time, a signal detected by the infrared detection unit after a predetermined time has elapsed from the start of lighting of the light source, and the like are used. Therefore, when the cooling process is not long enough to be cooled until the light source temperature matches the ambient environment temperature each time, there are two cases, one is when the gas concentration measuring device is started and the other is when a sufficient time has passed since the start of driving. Then, the physical quantity used to calculate the gas concentration, that is, the maximum value of the signal detected from the infrared detector while the light source is lit for a predetermined time, or detected from the infrared detector during a predetermined period when the light source is lit. Since the integrated value of the signals and the signal detected by the infrared detection unit after a lapse of a predetermined time from the start of lighting of the light source are different, the gas concentration cannot be calculated accurately immediately after the start of operation.

In the above-mentioned example, for the sake of simplicity, an incandescent light bulb is used as the light source 101 to perform a complete blinking operation. However, regardless of which of the above-mentioned light sources is used, the light source 101 is alternately turned off and on. When the driving conditions of the light source 101 are changed periodically by repeating or changing the output of the light source 101 periodically, the light source 101 outputs at the same time in the cycle at the start of driving and the steady driving. The amount of light and the spectrum produced are different, and the measurement output is also different.

That is, if the state of the light source 101 equivalent to that at the time of steady driving can be created immediately after the start of driving of the physical quantity measuring device 100, the quantity and density of the molecules to be measured can be calculated accurately from the time of starting driving. Therefore, the physical quantity measuring device 100 is executed one or more times under one or more predetermined driving conditions at the start of driving the light source 101, during the first step of driving the light source 101 and during the period of the first step. Whether to continue the driving by the second step, which is executed once or more to acquire the state of the light source 101 at a predetermined timing, and the state of the light source 101 acquired in the second step. A light source control method comprising a third step, which is performed one or more times to determine whether to end, is to be used.

By this light source control method, the physical quantity measuring device 100 can match the state of the light source 101 with that at the time of steady driving from the start of driving the light source 101, and can accurately match the quantity and density of the molecules to be measured (in this example, concrete). Gas concentration) can be calculated.
Further, in reality, the temperature of the light source 101 at the start of lighting of the light source 101 may change for each cycle due to a change in the outside air temperature even during steady driving. Therefore, in order to accurately calculate the quantity and density of the molecules to be measured (specifically, the gas concentration in this example) even during steady drive, the states of the light source 101 at the start of each lighting are aligned. Is desirable. Therefore, the physical quantity measuring device 100 is executed one or more times under one or more predetermined driving conditions at the start of the nth (n is an integer of 1 or more) period, and the first step of driving the light source 101. , Acquiring the state of the light source 101 at a predetermined timing during the period of the first step, the first step is executed once or more based on the second step and the state of the light source 101 acquired in the second step. A light source control method having a third step, which is executed one or more times to determine whether to continue or end the driving by the step of, may be used.

By this light source control method, the physical quantity measuring device 100 can match the state of the light source 101 at the start of each lighting, and the quantity and density of the molecules to be measured with high accuracy (specifically, the gas concentration in this example). Can be calculated.
Further, when the light source temperature rises by driving the light source 101, the change width of the physical quantity indicating the light source state with respect to the light source temperature rise width becomes larger, the state of the light source 101 at the start of each lighting is changed. The first step of acquiring the state of the light source 101 at a predetermined timing during the period of the first first step using constant voltage drive and the first first step at the start of each lighting for quick alignment. The third step, which is executed one or more times, determines whether to continue or end the driving by the first step based on the state of the light source 101 acquired in the second step and the first second step. And, after the end of the drive by the first first step, the state of the light source 101 is changed at a predetermined timing during the period of the second first step and the second first step using constant current drive. It is executed one or more times to determine whether to continue or end the driving by the first step based on the state of the light source 101 acquired in the second second step to be acquired and the second step of the second time. You may use the light source control method which performs the third step.

By this light source control method, the physical quantity measuring device 100 can quickly match the state of the light source 101 at the start of each lighting, and can accurately match the quantity and density of the molecule to be measured (specifically, the gas concentration in this example). ) Can be calculated. An incandescent light bulb is used as the light source 101, and the filament resistance value of the incandescent light bulb is used as the physical quantity, as the change width of the physical quantity indicating the light source state with respect to the light source temperature rise width becomes larger as the light source temperature rises by driving. Is also good.
The above-described embodiment and the examples described later exemplify devices and methods for embodying the technical idea of the present invention, and the technical idea of the present invention describes the material, shape, and structure of components. , Arrangement, etc. are not specified. The technical idea of the present invention may be modified in various ways within the technical scope specified by the claims stated in the claims.

Hereinafter, the physical quantity measuring device 100 according to the present embodiment will be described more specifically with reference to Examples.
FIG. 3 is a diagram showing a flowchart for explaining a physical quantity measuring method of the physical quantity measuring device according to the present embodiment.
First, in step S101, the physical quantity measuring device 100 initializes the measurement output (maximum value) and turns on the light source 101. In step S102 following step S101, the latest measurement output and measurement output (latest value) are acquired from the measurement light detection unit 102. In step S103 following step S102, if the measurement output (latest value) acquired in step S102 is larger than the measurement output (maximum value) held at that time, the measurement output (latest value) is changed to a new measurement output (maximum value). Value) to update. However, for the first measurement output (latest value) after the initialization of the measurement output (maximum value), the authenticity determination in S103 is always true.

In step 104 following step 103, the light source state is acquired by acquiring the light source resistance value, and if the light source resistance value is less than the reference resistance value, the process returns to step S102 with the light source lit, and the reference resistance value is returned. If the above is the case, the process proceeds to step S105. In step S105, the light source 101 is turned off, and the physical quantity is calculated based on the measured output (maximum value) held.
In step S106 following step S105, it is determined whether the physical quantity measuring device 100 has received the measurement end command, and if the result is true, the measurement is ended, and if the result is false, the process proceeds to step S107. In step S107, it is determined whether a predetermined time has elapsed since the light source was turned off immediately before, and the process remains in step S107 until the determination result becomes true.

In step 108 following step S107, the measurement output (maximum value) is initialized and the light source 101 is turned on in the same manner as in step 101. In step S109 following step S108, the measurement output (latest value) is acquired in the same manner as in step S102. In step S110 following step S109, the measurement output (maximum value) is updated in the same manner as in step S103. In step S111 following step S110, it is determined whether a predetermined time has elapsed since the light source was turned on immediately before, and if the determination result is false, the process returns to step S109, and if true, the process proceeds to step S112.
In step S112, the light source 101 is turned off in the same manner as in step S105, and the physical quantity is calculated based on the measured output (maximum value) held. In step S113 following step S112, the measurement is terminated when the physical quantity measuring device 100 is instructed to end the measurement as in step S106, and the process returns to step S107 otherwise.

The physical quantity measuring device 100 in the present embodiment periodically drives the light source 101 to calculate the physical quantity, but for the measurement after the second cycle, the light source 101 is periodically repeated from step S107 to step S113. Turns on and off. On the other hand, for the measurement in the first cycle, after the light source 101 is turned on, it is not turned off until the light source resistance value becomes equal to or higher than the reference light source resistance value. For this reference light source resistance value, the light source resistance value immediately before turning off the light source 101 in step S112 is used when the light source 101 is turned on and off sufficiently repeatedly in a fixed time cycle after the second cycle.
By doing so, the physical quantity measuring device 100 in the present embodiment can calculate the physical quantity using a value equivalent to the measurement output (maximum value) during steady operation from the first cycle, and the molecule to be measured with high accuracy. The quantity and density of can be calculated.

4 (a) to 4 (d) are diagrams showing actual measurement data showing the superiority of the light source control method possessed by the physical quantity measuring device in the present embodiment.
The physical quantity measuring device 100 when acquiring the actual measurement data drives the light source 101 with a constant current when the light source 101 is lit. 4 (a) and 4 (b) are a drive current waveform when the light source 101 is driven by the light source control method, and an output waveform of the measurement light detection unit 102, respectively. Further, FIGS. 4 (c) and 4 (d) show the drive current waveform and the measurement light detection unit 102 when the light source 101 is turned on and off in the same manner as in the first to second cycles, respectively. This is the output waveform.

The output waveform of the measurement light detection unit 102 of FIG. 4 (d) is smaller than that of the second and subsequent cycles in the first cycle, but the measurement light detection of FIG. 4 (b) is obtained. It can be seen that the output waveform of the unit 102 can obtain the same output as that of the first cycle to the second cycle and thereafter. As can be seen by comparing FIG. 4 (c) and FIG. 4 (a), this is realized by driving the light source 101 for a longer time than after only the first period in which it is cold.
Here, there is a step of acquiring the state of the light source 101 only in the first cycle, but the present invention is not limited to this embodiment, and the state of the light source 101 is acquired in the second and subsequent cycles as well. It may have steps. Further, here, there is a step of acquiring the state of the light source 101 based on the light source resistance value, but the present invention is not limited to this embodiment, and the state of the light source 101 is obtained based on the output of the reference light detection unit. It may have a step to acquire.

FIG. 5 is a diagram showing a flowchart for explaining another physical quantity measuring method implemented by the physical quantity measuring device in the present embodiment.
As shown in FIG. 5, the physical quantity measuring device 100 in the present embodiment first initializes the measurement output (maximum value) in step S201 and turns on the light source 101. In step S202 following step S201, the latest measurement output and measurement output (latest value) are acquired from the measurement light detection unit 102. In step S203 following step S202, if the measurement output (latest value) acquired in step S202 is larger than the measurement output (maximum value) held at that time, the measurement output (latest value) is changed to a new measurement output (maximum value). Value) to update. However, for the first measurement output (latest value) after the initialization of the measurement output (maximum value), the authenticity determination in S203 is always true.

In step 204 following step 203, the light source state is acquired by acquiring the light source resistance value, and if the light source resistance value is less than the reference resistance value, the process proceeds to step S202, and if the light source resistance value is equal to or more than the reference resistance value, the process proceeds to step S205. In step S205, the light source 101 is turned off, and the physical quantity is calculated based on the measured output (maximum value) held. In step S206 following step S205, it is determined whether the physical quantity measuring device 100 has received the measurement end command, and if the result is true, the measurement is ended, and if the result is false, the process proceeds to step S207. In step S207, it is determined whether or not a predetermined time has elapsed since the light source was turned off immediately before, and the process remains in step S207 until the determination result becomes true, and returns to step S201 when the determination result becomes true.

The physical quantity measuring device 100 in the present embodiment periodically drives the light source 101 to calculate the physical quantity, but does not turn off the light source 101 until the light source resistance value becomes equal to or higher than the reference light source resistance value after the light source 101 is turned on. For this reference light source resistance value, the light source resistance value immediately before turning off the light source 101 when the light source 101 is turned on and off sufficiently repeatedly for a sufficiently long period of time is used.
By doing so, the physical quantity measuring device 100 in the present embodiment can match the state when the light source 101 is turned off each time, and as a result, as compared with the case where the light source 101 is turned on and off periodically at a predetermined time. Therefore, the state of the light source 101 at the start of the next lighting can be adjusted every time, and the physical quantity can be calculated using a value equivalent to the measurement output (maximum value) at the time of the predetermined steady operation every cycle. , The quantity and density of the molecule to be measured can be calculated accurately.
Although each embodiment of the present invention has been described above, the technical scope of the present invention is not limited to the technical scope described in the above-described embodiment. From the description of the scope of claims, it is possible to make various changes or improvements to the above-described embodiments, and the technical scope of the present invention may include such modifications or improvements. it is obvious.

100 Physical quantity measuring device 101 Light source 102 Photodetector for measurement 103 Light source control unit 104 Calculation unit 105 Light source state detection unit

Claims (6)

An optical physical quantity measuring device that drives the light source housed in the device body to turn on and off periodically.
A photodetector for measurement that outputs a signal corresponding to the light output by the light source as a measurement output,
A light source state detection unit that acquires the state of the light source,
A light source control unit that controls the driving state of the light source,
A calculation unit that calculates the quantity or density of the molecule to be measured based on the measurement output from the measurement light detection unit.
With
The light source state detection unit is provided between the light source and the light source control unit, acquires the resistance value of the light source, and acquires the state of the light source by comparing the acquired resistance value with the reference resistance value. To do
When the light source control unit drives the light source in a preset period, the light source is continuously kept lit while the resistance value is smaller than the reference resistance value, and the resistance value is the reference. An optical physical quantity measuring device that turns off the light source when the resistance value or more is reached, turns on the light source after a predetermined time has elapsed from the turning off of the light source, and then drives the light source to turn on and off periodically. .. The first aspect of the present invention, wherein the light source control unit controls the light source to be continuously turned on and then turned off based on the state of the light source after the light source is turned on only in the first cycle after the start of measurement. Optical physical quantity measuring device. The light source control unit controls the power supply state for the light source under a plurality of drive conditions by a command from the calculation unit, and sets the power supply state according to the light source state acquired from the light source state detection unit. The optical physical quantity measuring device according to claim 1 or 2, which is controlled. The optical physical quantity measuring device according to any one of claims 1 to 3, wherein the calculation unit periodically drives the light source via the light source control unit. A light source control method for an optical physical quantity measuring device that drives a light source to turn on and off periodically.
The first step of turning on the light source at the start of the nth (n is an integer of 1 or more) period, and
The second step of acquiring the resistance value of the light source at a predetermined timing during the period of the first step and acquiring the state of the light source by comparing the acquired resistance value with the reference resistance value.
While the state of the light source acquired in the second step is smaller than the reference resistance value, the light source is continuously maintained in a lit state, and the resistance value becomes equal to or higher than the reference resistance value. When the third step of turning off the light source and
It has a fourth step of turning on the light source after a predetermined time has elapsed from turning off the light source when the light source is turned off in the third step .
A method for controlling a light source of an optical physical quantity measuring device that drives the light source to be turned on and off periodically after the fourth step . The light source control method for an optical physical quantity measuring device according to claim 5, wherein n is 1.

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