JP2020160064A - Light receiving-emitting device and method for diagnosing degradation - Google Patents

Abstract

To increase the accuracy of detecting the light receiving-emitting device.SOLUTION: In a light receiving-emitting device 100, a controller 30 acquires a first detection current from a light reception element 20 when a first driving current is supplied to a light emitting element 10 and acquires a second detection current from the light reception element 20 when a second driving current is supplied to the light emitting element 10. An operation unit 40 generates a signal showing a degradation in the light emitting element 10 when a reference value and an aging value as the rate of the first detection current and the second detection current satisfy a degradation determination condition.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to a light receiving and receiving device and a deterioration diagnosis method.

Conventionally, a light emitting element that emits infrared rays and a light receiving element that receives infrared rays transmitted through a gas to be detected (for example, CO ₂ gas) are provided, and the concentration of the gas is determined by utilizing the absorption characteristics of infrared rays in the gas. A gas detection device for detecting is known. In the gas detection device, for example, in consideration of aging deterioration of the light emitting element, calibration is performed at predetermined predetermined periods (for example, one week and one year).

For example, in Patent Document 1, an optical recording medium detection system that periodically corrects the drive current of a light emitting element by daily calibration so that the amount of light projected on the light receiving unit is maintained at the set value in the initial calibration. Is disclosed.

Japanese Unexamined Patent Publication No. 2006-46940

However, with the conventional light receiving and receiving device, it is difficult to diagnose the deterioration of the light emitting element easily and with high accuracy. Therefore, the deterioration of the light emitting element must be judged from the characteristics other than light, such as the forward voltage when the light source is driven by the current and the reverse current when the reverse voltage is applied. Since the characteristics of the above are temperature-dependent, they are not suitable for simple and highly accurate diagnosis.

On the other hand, a method of predicting deterioration from the drive time and performing calibration, for example, a calibration method such as periodic calibration once a year, is also conceivable, but the degree of deterioration differs depending on the device variation and the usage environment, so calibration is performed. It may not be calibrated when needed. Therefore, there is a problem that the detection accuracy of the light receiving / receiving device is lowered.

An object of the present disclosure is to improve the detection accuracy of a light receiving / receiving device.

The light emitting / receiving device of the present disclosure includes a light emitting element that outputs a light emitting amount corresponding to a driving current, a light receiving element that receives light from the light emitting element and outputs a detection current corresponding to the light receiving amount, and the light emitting device. A control unit, a calculation unit, and a control unit that supplies the drive current to the element and acquires the detection current from the light receiving element.
When the first drive current is supplied to the light emitting element, the control unit acquires the first detection current from the light receiving element and supplies the second drive current to the light emitting element. In this case, the second detection current is acquired from the light receiving element, and the calculation unit determines that the reference value and the aged value, which is the ratio of the first detection current to the second detection current, are deteriorated. When the condition is satisfied, a signal indicating deterioration of the light emitting element is generated.

The deterioration diagnosis method of the present disclosure includes a light emitting element that outputs a light emitting amount corresponding to a driving current, and a light receiving element that receives light from the light emitting element and outputs a detection current corresponding to the received light amount. A method for diagnosing deterioration of the light emitting element, which is executed by the light receiving / receiving device, is a step of supplying the driving current to the light emitting element and acquiring the detected current from the light receiving element, and a first step to the light emitting element. The step of acquiring the first detection current from the light receiving element when the drive current of 1 is supplied, and the second detection current from the light receiving element when the second drive current is supplied to the light emitting element. When the aged value, which is the ratio of the reference value to the first detection current and the second detection current, satisfies the deterioration determination condition, a signal indicating deterioration of the light emitting element is transmitted. Includes steps to generate.

According to the present disclosure, the detection accuracy of the light receiving / receiving device can be improved.

It is a figure which shows an example of the structure of the light emitting / receiving device which concerns on this embodiment. It is a flowchart which shows an example of the deterioration diagnosis method which concerns on this Embodiment. It is a flowchart which shows an example of the deterioration diagnosis method which concerns on modification 1. It is a flowchart which shows an example of the deterioration diagnosis method which concerns on modification 2. It is a flowchart which shows an example of the deterioration diagnosis method which concerns on modification 3.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

<Configuration of light receiving / receiving device>
The light emitting / receiving device 100 according to the present embodiment will be described with reference to FIG. FIG. 1 is a diagram showing an example of the configuration of the light receiving / receiving device 100 according to the present embodiment.

As shown in FIG. 1, the light emitting / receiving device 100 includes a light emitting element 10, a light receiving element 20, a control unit 30, and a calculation unit 40.

The light emitting element 10 emits a predetermined light according to the drive current supplied from the control unit 30. The light emitting element 10 emits light having a wavelength longer than, for example, 0.7 μm. When the light receiving / receiving device 100 is, for example, a gas detection device, the predetermined light has a wavelength region (for example, a wavelength region near 4.3 μm) including a wavelength absorbed by the gas to be detected (for example, CO ₂ gas). ) Is preferable.

The light emitting element 10 is, for example, a light emitting diode (Light Emitting Diode), a semiconductor laser, a MEMS (Micro Electro Mechanical Systems) heater, or the like. The light emitting element 10 is particularly preferably a light emitting diode.

Ａは、SRH（Shockley-Reａd-Hａll）再結合係数である。Bは、発光再結合係数である。Cは、オージェ再結合係数である。ｎは、キャリア濃度である。 Here, the reason why the deterioration rate of the light emitting element 10 depends on the drive current supplied to the light emitting element 10 will be briefly described. It is believed that the deterioration of the light emitting device 10 is caused by a decrease in internal quantum efficiency due to crystal defects. The internal quantum efficiency η _IRQ is proportional to the following equation (1).

A is an SRH (Shockley-Read-Hall) recombination coefficient. B is the luminescence recombination coefficient. C is the Auger recombination coefficient. n is the carrier concentration.

Since A is most affected by crystal defects, it can be seen from the equation (1) that the internal quantum efficiency depends on the drive current supplied to the light emitting device 10. That is, it can be seen that the deterioration rate of the light emitting element 10 depends on the drive current supplied to the light emitting element 10.

The light receiving element 20 receives at least a part of the predetermined light emitted by the light emitting element 10 and outputs a detection current to the control unit 30 according to the amount of light received. The light receiving element 20 receives at least a part of light in a wavelength region including a wavelength longer than 0.7 μm, and outputs a detection current to the control unit 30 according to the amount of light received. When the light receiving / receiving device 100 is, for example, a gas detection device, the light receiving element 20 has a wavelength region including a wavelength absorbed by the gas to be detected (for example, CO ₂ gas) (for example, a wavelength region near 4.3 μm). ) Can be received.

The light receiving element 20 is, for example, a quantum sensor, a quantum infrared sensor, a thermal infrared sensor, or the like. Examples of the quantum infrared sensor include a phototube, a photodiode, a phototransistor, and the like. Examples of the thermal infrared sensor include a pyroelectric sensor, a thermopile, a bolometer, and the like.

The light receiving element 20 may be formed on the same substrate as the light emitting element 10. Since the light receiving element 20 and the light emitting element 10 are formed on the same substrate, it is not necessary to separately prepare the substrates, so that the manufacturing cost can be reduced.

The light receiving element 20 may further include an optical filter having a function of transmitting light having a part of wavelengths. Examples of the optical filter include a bandpass filter that transmits light in a wavelength region near 4.3 μm.

The control unit 30 supplies the drive current to the light emitting element 10 and acquires the detection current from the light receiving element 20. Further, the control unit 30 converts the detection current acquired from the light receiving element 20 into a signal that can be processed by the calculation unit 40. The control unit 30 is, for example, an AFE (Analog Front End). The AFE may be composed of a single AFE circuit, or may be composed of a combination of a plurality of AFE circuits.

The control unit 30 supplies, for example, two types of drive currents having different values (a first drive current and a second drive current, which will be described later) to the light emitting element 10. As described above, the deterioration rate of the light emitting element 10 depends on the drive current supplied to the light emitting element 10. Therefore, the control unit 30 supplies two types of drive currents having different values to the light emitting element 10, and the calculation unit 40 determines the deterioration state of the light emitting element 10 based on the ratio of the deterioration rates of the light emitting element 10. It becomes possible to judge. In addition, the calculation unit 40 can generate a signal indicating deterioration based on the deterioration determination conditions described later. The control unit 30 can supply not only two types of drive currents having different values but also a plurality of types of drive currents having different values to the light emitting element 10.

For example, when the first drive current is supplied to the light emitting element 10 at a predetermined time, the control unit 30 acquires the first detection current from the light receiving element 20. For example, when the second drive current is supplied to the light emitting element 10 at a predetermined time, the control unit 30 acquires the second detection current from the light receiving element 20. The predetermined time is the time when the calculation unit 40 calculates the reference value for the aged value described later.

The first detected current I _p1 at a predetermined time can be expressed by the following equation (2).

The second detected current I _p2 at a predetermined time can be expressed by the following equation (3).

I ₁ is a first drive current supplied to the light emitting element 10. I ₂ is a second drive current supplied to the light emitting element 10. Φ _p1 is the amount of light emitted by the light emitting element 10 with respect to the first drive current I ₁ . Φ _p2 is the amount of light emitted by the light emitting element 10 with respect to the second drive current I ₂ . Rλ is the sensitivity of the sensor. T _x is the light guide efficiency assuming that a light guide mechanism (for example, a light guide) is included. _Tabs is the light attenuation factor due to gas.

The control unit 30 acquires the first detection current I _p1 and the second detection current I _p2 substantially at the same time. For example, the control unit 30, and the interval between the time of acquiring time for acquiring a first detection current I _p1 and the second detection current I _p2 is less than 10 seconds, the first detection current I _p1 and Acquire the second detection current I _p2 . As a result, for example, the control unit 30 can acquire the first detection current I _p1 and the second detection current I _p2 while the temperature of the light emitting element 10 does not change significantly, so that the calculation unit 40 can obtain the first detection current I _p1 and the second detection current I _p2 . It is possible to calculate the value (ratio of the reference value and the aged value, which will be described later) required to determine the calibration timing with high accuracy.

Further, when the control unit 30 acquires the first detection current I _p1 and the second detection current I _p2 substantially at the same time, and the calculation unit 40 calculates the ratio (reference value described later), for example. , Light guide efficiency, light attenuation by gas, attenuation of reflectance of gas cell, etc. need not be considered. Therefore, the calculation unit 40 can easily and highly accurately calculate the value required for determining the calibration timing. In a measurement environment in which the temperature of the light emitting element 10 suddenly rises in a minute time, the control unit 30 first acquires the first detection current I _p1 and then stabilizes the measurement environment. , The second detection current I _p2 may be acquired.

For example, when the first drive current is supplied to the light emitting element 10 after a predetermined time has elapsed from the predetermined time, the control unit 30 acquires the first detected current from the light receiving element 20. For example, when the second drive current is supplied to the light emitting element 10 after a predetermined time has elapsed from the predetermined time, the control unit 30 acquires the second detection current from the light receiving element 20.

First detection current I _'p1 after a predetermined time has elapsed from a predetermined time, the following equation (4) can be expressed.

The second detection current _I'p2 after a lapse of a predetermined time from a predetermined time can be expressed by the following equation (5).

I ₁ is a first drive current supplied to the light emitting element 10. I ₂ is a second drive current supplied to the light emitting element 10. α ₁ is the deterioration rate from a predetermined time when the first drive current is supplied to the light emitting element 10. α ₂ is the deterioration rate from a predetermined time when the second drive current is supplied to the light emitting element 10. α ₁ * Φ _{p 1} is the amount of light emitted by the light emitting element 10 with respect to the first drive current I ₁ , and α ₂ * Φ _{p 2} is the amount of light emitted by the light emitting element 10 with respect to the second drive current I ₂ . Rλ is the sensitivity of the sensor. _T'x is the light guide efficiency assuming that a light guide mechanism (for example, a light guide) is included. _T'abs is the light attenuation factor due to gas.

Control unit 30, similarly to the case of obtaining a first detection current I _p1 and the second detection current I _p2, substantially simultaneously acquired the first detection current I _'p1 and the second detection current I' _p2 .. For example, the control unit 30 sets the first detection current _{I'p1 so} that the interval between the time of acquiring the first detection current _I'p1 and the time of acquiring the second detection current _I'p2 is 10 seconds or less. ' _p1 and the second detection current _I'p2 are acquired almost simultaneously. As a result, the control unit 30 can acquire the first detection current _I'p1 and the second detection current _I'p2 while the temperature of the light emitting element 10 does not change significantly, so that the calculation unit 40 can obtain the first detection current _I'p1 and the second detection current _I'p2 . It is possible to calculate the value required to determine the calibration timing with high accuracy.

Further, when the control unit 30 acquires the first detection current _I'p1 and the second detection current _I'p2 substantially at the same time, the calculation unit 40 calculates the ratio (aged value described later). For example, it is not necessary to consider values such as light guide efficiency, light attenuation rate by gas, and attenuation of reflectance of gas cell. Therefore, the calculation unit 40 can easily and highly accurately calculate the value required for determining the calibration timing.

The calculation unit 40 includes, for example, a CPU, a memory, and the like, and controls the operation of each unit included in the light receiving / receiving device 100. The arithmetic unit 40 executes various processes by executing a predetermined program or the like expanded in the memory.

The calculation unit 40 calculates a reference value S, which is the ratio of the first detected current I _p1 acquired by the control unit 30 at a predetermined time to the second detected current I _p2 acquired by the control unit 30 at a predetermined time. To do.

The reference value S can be expressed as in the following equation (6) based on the equations (2) and (3).

The calculation unit 40 has a first detection current _I'p1 acquired by the control unit 30 after a predetermined time has elapsed from a predetermined time and a second detection current I'p1 acquired by the control unit 30 after a predetermined time has elapsed from the predetermined time. 'Calculate the aged value P, which is the ratio to _p2 .

The aged value P can be expressed as in the following equation (7) based on the equations (4) and (5).

The calculation unit 40 calculates the ratio of the reference value S and the aged value P based on the equations (6) and (7). The ratio of the reference value S to the aged value P (for example, the aged value P / reference value S) can be expressed as the following equation (8) based on the equations (6) and (7).

As described above, the reference value S is the ratio of the first detected current I _p1 to the second detected current I _p2 at a predetermined time (for example, time t _N ). Further, the aging value P, which is the ratio of 'and _p1 second detection current I' first detection current I and _p2 in after a predetermined time has elapsed from a predetermined time (e.g., time t _{N + 1).} The reference value S does not necessarily have to be a value calculated by the calculation unit 40, and may be a value preset by the control unit 30.

The calculation unit 40 determines whether or not the ratio of the reference value S and the aged value P is larger than the threshold value (first threshold value) T ₁ . The threshold value T ₁ is, for example, the deterioration rate α ₁ from a predetermined time when the first drive current is supplied to the light emitting element 10, and the second drive current when the second drive current is supplied to the light emitting element 10. It is a value set as a value (= α ₁ / α ₂ ) divided by the deterioration rate α ₂ from a predetermined time. The calculation unit 40 compares the ratio of the reference value S and the aged value P with the threshold value T ₁ and determines whether or not the deterioration determination condition J ₁ is satisfied. Here, the deterioration determination condition J ₁ is a condition that the ratio of the reference value S and the aged value P is larger than the threshold value T ₁ .

When the deterioration determination condition J ₁ is satisfied, the calculation unit 40 generates a signal indicating deterioration. On the other hand, if the deterioration determination condition J ₁ is not satisfied, the calculation unit 40 does not generate a signal indicating deterioration. As the deterioration of the light emitting element 10 progresses, the ratio between the reference value S and the aged value P changes. Therefore, the calculation unit 40 generates a signal indicating deterioration at the timing when the deterioration determination condition J ₁ is satisfied. The light emitting device 100 can request calibration at an appropriate timing.

Alternatively, the calculation unit 40 determines whether or not the ratio of the reference value S and the aged value P is equal to or less than the threshold value (second threshold value) T ₂ . The threshold value T ₂ is, for example, the deterioration rate α ₂ from a predetermined time when the second drive current is supplied to the light emitting element 10, and the first drive current when the first drive current is supplied to the light emitting element 10. It is a value set as a value (= α ₂ / α ₁ ) divided by the deterioration rate α ₁ from a predetermined time. The calculation unit 40 compares the ratio of the reference value S and the aged value P with the threshold value T ₂ and determines whether or not the deterioration determination condition J ₂ is satisfied. Here, the deterioration determination condition J ₂ is a condition that the ratio of the reference value S and the aged value P is equal to or less than the threshold value T ₂ .

When the deterioration determination condition J ₂ is satisfied, the calculation unit 40 generates a signal indicating deterioration. On the other hand, if the deterioration determination condition J ₂ is not satisfied, the calculation unit 40 does not generate a signal indicating deterioration. As the deterioration of the light emitting element 10 progresses, the ratio between the reference value S and the aged value P changes. Therefore, the calculation unit 40 generates a signal indicating deterioration at the timing when the deterioration determination condition J ₂ is satisfied. The light emitting device 100 can request calibration at an appropriate timing.

The threshold value is not limited to the above-mentioned threshold values T ₁ and threshold value T _2, and can be arbitrarily set by the user. Further, the number of the threshold values is not particularly limited, and may be singular or plural. When the number of threshold values is, for example, two (first threshold value, second threshold value), the deterioration judgment condition is that the ratio of the reference value S and the aged value P is equal to or greater than the first threshold value and equal to or less than the second threshold value. It is also possible to make the condition.

The light receiving / receiving device 100 may further include a storage unit 50. The storage unit 50 is not particularly limited as long as it has a function of storing various types of information, and may be, for example, a DRAM, an HDD, or the like. The storage unit 50 may include, for example, a first detection current I _p1 acquired by the control unit 30 at a predetermined time, a second detection current I _p2 acquired by the control unit 30 at a predetermined time, and a control unit 30 at a predetermined time. Reference value S, which is the ratio of the first detected current I _p1 acquired by the control unit 30 to the second detected current I _p2 acquired by the control unit 30 at a predetermined time, and the control unit 30 after a predetermined time has elapsed from the predetermined time. The acquired first detection current _I'p1 and the second detection current _I'p2 acquired by the control unit 30 after a predetermined time has elapsed from the predetermined time have been acquired by the control unit 30 after a predetermined time has elapsed from the predetermined time. first detection current I which is the ratio secular value P between _'p1 and the second detection current I controller 30 has obtained from a predetermined time after the predetermined time elapses' _p2, computing unit 40 executes various processes Memorize various programs and various information required for this purpose. The storage unit 50 may be provided inside the calculation unit 40.

The storage unit 50 has a first detection current I _p1 , a second detection current I _p2 , a reference value S, a first detection current _I'p1 , a second detection current _I'p2 , an aged value P, and the like. Not only the values may be stored one by one, but a plurality of each of these values may be stored.

Further, the light receiving / receiving device 100 may further include a communication unit 60. For example, the communication unit 60 can communicate with the external device by wire or wirelessly, and transmits, for example, a calibration request signal of the light receiving / receiving device 100 to the external device based on the instruction signal input from the calculation unit 40. .. As a result, the user who operates the external device can recognize that the light receiving / receiving device 100 needs to be calibrated. Alternatively, the communication unit 60 may transmit the calibration request signal of the light receiving / receiving device 100 to its own device to perform self-calibration. In any case, the light receiving / receiving device 100 will be calibrated at an appropriate timing.

Further, the communication unit 60 can transmit not only the calibration request signal but also various data input from the calculation unit 40 and the information stored in the storage unit 50 to the external device. The external device can also display predetermined information such as a measurement result and a calibration time on the display unit based on various data.

The communication unit 60 may use, for example, a Universal Asynchronous Receiver Transmitter (UART) interface. The communication unit 60 includes, for example, an external memory interface, a general-purpose asynchronous transceiver (UART: Universal Asynchronous Receiver Transmitter) interface, an extended serial peripheral interface (eSPI :), and a general-purpose input / output (GPIO: General-purpose input / output) interface. , Pulse Code Modulation (PCM) and / or Inter-IC Sound (I2S) interface, Inter-Integrated Circuit (I2C) bus interface, Universal Serial Bus (USB: Universal Serial Bus) ) Interface, Bluetooth® interface, Jigby interface, IrDA (Infrared Data Association) interface, or wireless USB (W-USB: Wireless-Universal Serial Bus) interface, which is realized via one or more of them. Good. The communication unit 60 is not limited to these means of realization.

According to the light emitting / receiving device 100 according to the present embodiment, two types of drive currents having different values are supplied to the light emitting element 10, and the timing of calibration is used by utilizing the change in the ratio between the reference value S and the aged value P. To determine. As a result, the calibration is performed at an appropriate timing under any environment, so that the detection accuracy of the light receiving / receiving device 100 can be improved.

<Deterioration diagnosis method>
Next, the deterioration diagnosis method according to the present embodiment will be described with reference to FIG. FIG. 2 is a flowchart showing an example of a deterioration diagnosis method.

In step S201, the control unit 30 drives the light emitting element 10 with the first drive current and acquires the first detection current from the light receiving element 20.

In step S202, the control unit 30 drives the light emitting element 10 with the second drive current and acquires the second detection current from the light receiving element 20.

In step S203, the calculation unit 40 calculates an aged value which is a ratio of the first detected current acquired in step S201 and the second detected current acquired in step S202.

In step S204, the calculation unit 40 calculates the ratio between the reference value and the aged value calculated in step S203, and compares it with the threshold value T. The threshold value T is a predetermined value set by the user.

In step S205, the calculation unit 40 determines whether or not the ratio of the reference value and the aged value is larger than the threshold value T, that is, whether or not the deterioration determination condition is satisfied. The calculation unit 40 proceeds to the process of step S206 when it is determined that the ratio of the reference value and the aged value is larger than the threshold value T, that is, when it is determined that the deterioration determination condition is satisfied. The calculation unit 40 ends the process when it is determined that the ratio of the reference value and the aged value is equal to or less than the threshold value T, that is, when it is determined that the deterioration determination condition is not satisfied.

In step S206, the calculation unit 40 generates a signal indicating deterioration and outputs an instruction signal to the communication unit 60.

According to the deterioration diagnosis method described above, deterioration of the light emitting element can be diagnosed easily and with high accuracy. Further, if the presence or absence of deterioration of the light emitting element is known, it can be used to estimate the cause of deterioration of the light emitting / receiving device. For example, if the light receiving / receiving device includes a light emitting element and a light receiving element, it is possible to distinguish whether the light emitting element is deteriorated or the light receiving element is deteriorated. For example, if the light receiving / receiving device includes a light emitting element, a light guide, and a light receiving element, is the light emitting element the cause of deterioration, or is the light guide or the light receiving element the cause of deterioration? , Can be distinguished. That is, since the user can obtain an index for determining which part of the part should be replaced at the time of maintenance, unnecessary parts replacement can be reduced.

<Modification example 1>
Next, the deterioration diagnosis method according to the first modification will be described with reference to FIG. FIG. 3 is a flowchart showing an example of the deterioration diagnosis method.

In step S201, the control unit 30 drives the light emitting element 10 with the first drive current and acquires the first detection current from the light receiving element 20.

In step S202, the control unit 30 drives the light emitting element 10 with the second drive current and acquires the second detection current from the light receiving element 20.

In step S203, the calculation unit 40 calculates an aged value which is a ratio of the first detected current acquired in step S201 and the second detected current acquired in step S202.

In step S204, the calculation unit 40 calculates the ratio between the reference value and the aged value calculated in step S203, and compares it with the threshold value T. The threshold value T is a predetermined value set by the user.

In step S205, the calculation unit 40 determines whether or not the ratio of the reference value and the aged value is larger than the threshold value T, that is, whether or not the deterioration determination condition is satisfied. The calculation unit 40 proceeds to the process of step S206 when it is determined that the ratio of the reference value and the aged value is larger than the threshold value T, that is, when it is determined that the deterioration determination condition is satisfied. The calculation unit 40 ends the process when it is determined that the ratio of the reference value and the aged value is equal to or less than the threshold value T, that is, when it is determined that the deterioration determination condition is not satisfied.

In step S206, the calculation unit 40 generates a signal indicating deterioration and outputs an instruction signal to the communication unit 60.

In step S207, the calculation unit 40 calculates a correction value of at least one of the first detected current and the second detected current by using the aged value calculated in step S203. Specifically, the calculation unit 40 calculates at least one correction value of the first detection current and the second detection current by referring to the deterioration correction value model for the aged value that has been formulated in advance. Further, here, the calculation of the correction value may be a method of referring to the deterioration correction value with respect to the aged value quantified in advance.

According to the deterioration diagnosis method according to the first modification, the deterioration of the light emitting element can be diagnosed easily and with high accuracy.

<Modification 2>
Next, the deterioration diagnosis method according to the second modification will be described with reference to FIG. FIG. 4 is a flowchart showing an example of the deterioration diagnosis method.

In step S201, the control unit 30 drives the light emitting element 10 with the first drive current and acquires the first detection current from the light receiving element 20.

In step S202, the control unit 30 drives the light emitting element 10 with the second drive current and acquires the second detection current from the light receiving element 20.

In step S203, the calculation unit 40 calculates an aged value which is a ratio of the first detected current acquired in step S201 and the second detected current acquired in step S202.

In step S204, the calculation unit 40 calculates the ratio between the reference value and the aged value calculated in step S203, and compares it with the threshold value T. The threshold value T is a predetermined value set by the user.

In step S205, the calculation unit 40 determines whether or not the ratio of the reference value and the aged value is larger than the threshold value T, that is, whether or not the deterioration determination condition is satisfied. The calculation unit 40 proceeds to the process of step S206 when it is determined that the ratio of the reference value and the aged value is larger than the threshold value T, that is, when it is determined that the deterioration determination condition is satisfied. The calculation unit 40 ends the process when it is determined that the ratio of the reference value and the aged value is equal to or less than the threshold value T, that is, when it is determined that the deterioration determination condition is not satisfied.

In step S206, the calculation unit 40 generates a signal indicating deterioration and outputs an instruction signal to the communication unit 60.

In step S207A, the calculation unit 40 performs baseline correction. Specifically, the baseline correction is to correct all the detected current values thereafter by referring to the deterioration correction value model for the threshold value T formulated in advance and using the obtained deterioration correction value.

According to the deterioration diagnosis method according to the second modification, the deterioration of the light emitting element can be diagnosed easily and with high accuracy.

<Modification example 3>
Next, the deterioration diagnosis method according to the modification 3 will be described with reference to FIG. FIG. 5 is a flowchart showing an example of a deterioration diagnosis method.

In step S201, the control unit 30 drives the light emitting element 10 with the first drive current and acquires the first detection current from the light receiving element 20.

In step S202, the control unit 30 drives the light emitting element 10 with the second drive current and acquires the second detection current from the light receiving element 20.

In step S203, the calculation unit 40 calculates an aged value which is a ratio of the first detected current acquired in step S201 and the second detected current acquired in step S202.

In step S204, the calculation unit 40 calculates the ratio between the reference value and the aged value calculated in step S203, and compares it with the threshold value T. The threshold value T is a predetermined value set by the user.

In step S205, the calculation unit 40 determines whether or not the ratio of the reference value and the aged value is larger than the threshold value T, that is, whether or not the deterioration determination condition is satisfied. The calculation unit 40 proceeds to the process of step S206 when it is determined that the ratio of the reference value and the aged value is larger than the threshold value T, that is, when it is determined that the deterioration determination condition is satisfied. The calculation unit 40 ends the process when it is determined that the ratio of the reference value and the aged value is equal to or less than the threshold value T, that is, when it is determined that the deterioration determination condition is not satisfied.

In step S206, the calculation unit 40 generates a signal indicating deterioration and outputs an instruction signal to the communication unit 60.

In step S207B, the control unit 30 adjusts the first drive current and the second drive current using the aged value calculated in step S203.

According to the deterioration diagnosis method according to the third modification, the deterioration of the light emitting element can be diagnosed easily and with high accuracy.

<Application of embodiment>
The light emitting / receiving device according to the present embodiment can be applied to various devices. For example, a gas sensor for detecting a specific gas concentration contained in a building or measuring device, a gas sensor mounted on a mobile communication device such as a mobile phone or a smartphone, and a gas concentration contained in a means of transportation such as an automobile, a train, or an aircraft. It can be applied to various devices such as a gas sensor for detection, a component detection device for substances (for example, water and body fluid) flowing in the optical path space between the light emitting element and the light receiving element, and a glucose concentration measuring device in blood. Is.

<Other variants>
In the present embodiment, the case where the control unit 30 and the calculation unit 40 are separately configured has been described as an example, but the control unit 30 and the calculation unit 40 may be configured in combination.

Although the above embodiments have been described as typical examples, it will be apparent to those skilled in the art that many modifications and substitutions can be made within the spirit and scope of the present invention. Therefore, the present invention should not be construed as being limited by the above-described embodiments, and various modifications and modifications can be made without departing from the scope of claims. For example, it is possible to combine a plurality of constituent blocks described in the configuration diagram of the embodiment into one, or to divide one constituent block into one.

10 Light emitting element 20 Light receiving element 30 Control unit 40 Calculation unit 50 Storage unit 60 Communication unit 100 Light receiving device

Claims (17)

A light emitting element that outputs the amount of light emitted according to the drive current,
A light receiving element that receives light from the light emitting element and outputs a detection current according to the amount of light received.
A control unit that supplies the drive current to the light emitting element and acquires the detected current from the light receiving element.
Calculation unit and
With
The control unit
When the first drive current is supplied to the light emitting element, the first detection current is acquired from the light receiving element, and the first detection current is acquired.
When the second drive current is supplied to the light emitting element, the second detection current is acquired from the light receiving element, and the second detection current is acquired.
The calculation unit
When the reference value and the aged value, which is the ratio of the first detection current to the second detection current, satisfy the deterioration determination condition, a signal indicating deterioration of the light emitting element is generated.
Light receiving and receiving device. The calculation unit
At a predetermined time, a reference value which is a ratio of the first detected current to the second detected current is calculated.
The light emitting / receiving device according to claim 1, wherein the aged value is calculated after a lapse of a predetermined time from the predetermined time. The light receiving / receiving device according to claim 1 or 2, further comprising a storage unit for storing the reference value. Equipped with a communication unit that communicates with the calibrating device
The light emitting / receiving device according to any one of claims 1 to 3, wherein the calculation unit outputs a signal indicating deterioration of the light emitting element to the communication unit. Any of claims 1 to 4, wherein the calculation unit calculates a correction value of at least one of the first detection current and the second detection current by using the aged value when the deterioration determination condition is satisfied. The light receiving / receiving device according to item 1. The light emitting / receiving device according to any one of claims 1 to 4, wherein the calculation unit performs baseline correction when the deterioration determination condition is satisfied. The item according to any one of claims 1 to 4, wherein the control unit adjusts the first drive current and the second drive current by using the aged value when the deterioration determination condition is satisfied. Light receiving and receiving device. The light emitting / receiving device according to any one of claims 1 to 7, wherein the light emitting element is an LED or a semiconductor laser. The light emitting / receiving device according to any one of claims 1 to 8, wherein the light emitting element emits light having a wavelength longer than 0.7 μm. The light emitting / receiving device according to any one of claims 1 to 9, wherein the light receiving element is a quantum sensor or a quantum infrared sensor. The light emitting / receiving device according to any one of claims 1 to 10, wherein the light emitting element and the light receiving element are formed on the same substrate. The light emitting / receiving device according to any one of claims 1 to 11, wherein the deterioration determination condition is a condition that the ratio of the reference value to the aged value is larger than the first threshold value. The light emitting / receiving device according to any one of claims 1 to 12, wherein the deterioration determination condition is a condition that the ratio of the reference value to the aged value is equal to or less than a second threshold value. It is executed by a light receiving / receiving device including a light emitting element that outputs a light emitting amount corresponding to a driving current and a light receiving element that receives light from the light emitting element and outputs a detection current corresponding to the light receiving amount. This is a method for diagnosing deterioration of a light emitting element.
A step of supplying the driving current to the light emitting element and acquiring the detected current from the light receiving element.
A step of acquiring a first detection current from the light receiving element when a first drive current is supplied to the light emitting element, and
A step of acquiring a second detection current from the light receiving element when a second drive current is supplied to the light emitting element, and
A step of generating a signal indicating deterioration of the light emitting element when the reference value and the aged value which is the ratio of the first detection current to the second detection current satisfy the deterioration determination condition.
Deterioration diagnostic methods, including. The 14th aspect of the present invention further comprises a step of calculating a correction value of at least one of the first detection current and the second detection current by using the aged value when the deterioration determination condition is satisfied. Deterioration diagnosis method. The deterioration diagnosis method according to claim 14, further comprising a step of performing baseline correction when the deterioration determination condition is satisfied. The deterioration diagnosis method according to claim 14, further comprising a step of adjusting the first drive current and the second drive current by using the aged value when the deterioration determination condition is satisfied.

Images