JP2021131247A - Light detection system, discharge probability calculating method, and received light quantity measuring method - Google Patents

Abstract

To calculate an irregular discharge probability of an optical sensor.SOLUTION: A light detection system includes: an optical sensor 1; an application voltage generating circuit 12 that applies a drive pulse voltage to the optical sensor 1; a discharge determining portion 201 that detects the optical sensor 1's discharge; a discharge probability calculating portion 202 that calculates a discharge probability for each of a first state in which the optical sensor 1 is shielded from light and a second state in which the optical sensor 1 is shielded from the light and a pulse width of the drive pulse voltage is different from the first state; a sensitivity parameter storing portion 19 that stores the drive pulse voltage's reference pulse width as the optical sensor 1's sensitivity parameter, and a discharge probability when the optical sensor 1 is shielded and the drive pulse voltage's pulse width is the reference pulse width; and a discharge probability calculating portion 203 that calculates a discharge probability of irregular discharge that occurs without depending on the optical sensor 1's received light quantity on the basis of the sensitivity parameter, the discharge probabilities calculated in the first and second states, and the drive pulse voltage's pulse widths in the first and second states.SELECTED DRAWING: Figure 1

Description

The present invention relates to a photodetection system that detects light such as a flame.

A photocell type ultraviolet sensor may be used as an optical sensor that detects the presence or absence of a flame based on the ultraviolet rays emitted from the light of a flame in a combustion furnace or the like. It has been observed that a non-regular discharge phenomenon (suspicious discharge) occurs due to a noise component other than the discharge due to the photoelectric effect in the discharge of the phototube type ultraviolet sensor.

Patent Document 1 proposes a flame detection system capable of controlling the pulse width of a drive pulse applied to an optical sensor, obtaining the amount of received discharge from a calculation, and determining the life of the flame sensor from the amount of light. However, the actual discharge of the optical sensor includes a non-regular discharge due to noise, which is collectively called a failure, and even if there is no light due to the flame, the discharge may occur and an erroneous detection may occur. In order to eliminate such false detection of discharge, it is necessary to consider a method for measuring the discharge probability in consideration of the noise component.

Further, in the flame detection system disclosed in Patent Document 2, a method of obtaining a light receiving amount in consideration of the discharge probability of a noise component other than the normal discharge has been proposed, and it is possible to accurately detect the presence or absence of a flame. There is. However, in the flame detection system disclosed in Patent Document 2, it is necessary that the discharge probability of the noise component is known.

Further, in the failure detection device disclosed in Patent Document 3, it is proposed to detect a failure due to self-discharge of the optical sensor by providing a shutter mechanism for blocking electromagnetic waves incident on the optical sensor. However, in the failure detection device disclosed in Patent Document 3, there is no discriminating method for distinguishing between regular discharge and non-regular discharge due to a change in measurement sensitivity due to the life of the optical sensor, and there is a possibility that failure detection may be erroneous. was there.
The above problems occur not only in the flame detection system but also in the light detection system using the optical sensor.

JP-A-2018-84422 JP-A-2018-84423 Japanese Unexamined Patent Publication No. 05-012581

The present invention has been made to solve the above problems, and calculates the discharge probability of non-regular discharge due to noise components other than discharge due to the photoelectric effect of the optical sensor, which occurs independently of the amount of light received by the optical sensor. It is an object of the present invention to provide a photodetection system capable of performing a discharge probability calculation method.
Another object of the present invention is to provide an optical detection system and a light receiving amount measuring method capable of calculating a light receiving amount excluding noise components other than the normal discharge of an optical sensor.

The optical detection system of the present invention includes an optical sensor configured to detect light emitted from a light source, and an applied voltage generator configured to periodically apply a drive pulse voltage to the electrodes of the optical sensor. And a current detection unit configured to detect the discharge current of the optical sensor, and a discharge determination unit configured to detect the discharge of the optical sensor based on the discharge current detected by the current detection unit. And the applied voltage generation in each of the first state in which the optical sensor is shielded and the second state in which the optical sensor is shielded and the pulse width of the drive pulse voltage is different from the first state. First discharge probability calculation configured to calculate the discharge probability based on the number of times the drive pulse voltage is applied by the unit and the number of discharges detected by the discharge determination unit during the application of the drive pulse voltage. As known sensitivity parameters of the optical sensor, the reference pulse width of the drive pulse voltage and the discharge probability when the pulse width of the drive pulse voltage is the reference pulse width in a state where the optical sensor is shielded from light. A storage unit configured to store in advance, a sensitivity parameter stored in the storage unit, and a discharge probability calculated by the first discharge probability calculation unit in the first and second states. And, based on the pulse width of the drive pulse voltage in the first and second states, it is generated depending on the pulse width of the drive pulse voltage and does not depend on the received light amount of the optical sensor. It occurs independently of the discharge probability of the first type of non-regular discharge due to noise components other than the discharge due to the photoelectric effect of the optical sensor, the pulse width of the drive pulse voltage, and the amount of light received by the optical sensor. It is characterized by including a second discharge probability calculation unit configured to calculate the discharge probability of the second type of non-normal discharge due to the noise component.

Further, in one configuration example of the optical detection system of the present invention, the second discharge probability calculation unit has the reference pulse widths T ₀ and T of the drive pulse voltage, and the drive pulse voltage in a state where the optical sensor is shielded from light. ^{Discharge probability P *} when the pulse width of is the reference pulse width T, _{discharge probability 1} P ^* calculated by the first discharge probability calculation unit in the first state, and in the second state. _{The discharge probability 2} P ^* calculated by the first discharge probability calculation unit, _{the pulse width T 1} of the drive pulse voltage in the first state, and the pulse of the drive pulse voltage in the second state. Based on the width T ₂ (T ₁ ≠ T ₂ ), the discharge probability P _aB of the first-class non-regular discharge and the discharge probability P _bB of the second-class non-regular discharge are calculated. Is to be.

Further, the optical detection system of the present invention includes an optical sensor configured to detect light emitted from a light source and an applied voltage configured to periodically apply a drive pulse voltage to the electrodes of the optical sensor. A generation unit, a current detection unit configured to detect the discharge current of the optical sensor, and a discharge configured to detect the discharge of the optical sensor based on the discharge current detected by the current detection unit. The determination unit, the first state in which the optical sensor is shielded, the second state in which the optical sensor is shielded and the pulse width of the drive pulse voltage is different from the first state, and the optical sensor A third state in which light can be collected and the pulse width of the drive pulse voltage is the same as in the first state, and a third state in which the light sensor can collect light and the pulse width of the drive pulse voltage is the same as in the second state. For each of the fourth states, the discharge probability is calculated based on the number of times the drive pulse voltage is applied by the applied voltage generation unit and the number of discharges detected by the discharge determination unit during the application of the drive pulse voltage. As known sensitivity parameters of the discharge probability calculation unit and the optical sensor, the reference pulse width of the drive pulse voltage, the reference light receiving amount of the optical sensor, and the state in which the optical sensor can collect light. A storage unit configured to store in advance the discharge probability of a normal discharge when the pulse width of the drive pulse voltage is the reference pulse width and the light reception amount of the optical sensor is the reference light reception amount, and the storage unit. The sensitivity parameters stored in, the discharge probability calculated by the discharge probability calculation unit in the first, second, third, and fourth states, and the first, second, third, and third states. A light receiver configured to calculate the amount of light received by the optical sensor in the third and fourth states in which the optical sensor can collect light based on the pulse width of the drive pulse voltage in the state of 4. It is characterized by having a quantity calculation unit.

Further, in one configuration example of the light detection system of the present invention, the light receiving amount configured to determine the presence or absence of the light source by comparing the light receiving amount calculated by the light receiving amount calculation unit with the light receiving amount threshold value. It is characterized by further including a determination unit.
Further, in one configuration example of the light detection system of the present invention, the light receiving amount calculation unit has a reference light receiving amount Q _{0 of the optical sensor, a reference pulse width T 0} of the driving pulse voltage, and a discharge probability P of the normal discharge. _{aA , the discharge probability 1} P ^* calculated by the discharge probability calculation unit in the _{first state, the discharge probability 2} P ^* calculated by the discharge probability calculation unit in the second state, the first. _{Based on the discharge probability 1} P calculated by the discharge probability calculation unit in the third state _{and the discharge probability 2} P calculated by the discharge probability calculation unit in the fourth state, the third, It is characterized in that the light receiving amount Q of the optical sensor in the fourth state is calculated.
Further, one configuration example of the photodetector system of the present invention includes a light-shielding means provided between the light source and the light sensor, and a state in which the light sensor is shielded by opening and closing the light-shielding means. It is characterized by further including a shutter control unit configured to switch between a light sensor and a state in which light can be collected.

Further, in the discharge probability calculation method of the optical detection system of the present invention, a drive pulse voltage is periodically applied to the electrodes of the optical sensor when the optical sensor that detects the light emitted from the light source is in the first state of being shielded from light. The discharge of the optical sensor is based on the first step of applying, the second step of detecting the discharge current of the optical sensor in the first state, and the discharge current in the first state. The first step is based on the third step of detecting the above, the number of times the drive pulse voltage is applied by the first step, and the number of discharges detected in the third step while the drive pulse voltage is being applied. In the fourth step of calculating the discharge probability in the state of, and in the second state where the optical sensor is shielded from light and the pulse width of the drive pulse voltage is different from the first state, the optical sensor A fifth step of periodically applying a drive pulse voltage to the electrodes, a sixth step of detecting the discharge current of the optical sensor in the second state, and the discharge in the second state. The seventh step of detecting the discharge of the optical sensor based on the current, the number of times the drive pulse voltage is applied by the fifth step, and the discharge detected in the seventh step while the drive pulse voltage is applied. The eighth step of calculating the discharge probability in the second state based on the number of times of the above, the reference pulse width of the drive pulse voltage and the light shielding by the optical sensor as known sensitivity parameters of the optical sensor. With reference to a storage unit that previously stores the discharge probability when the pulse width of the drive pulse voltage is the reference pulse width in this state, the sensitivity parameters stored in this storage unit and the fourth and eighth Based on the discharge probability calculated in step 1 and the pulse width of the drive pulse voltage in the first and second states, it is generated depending on the pulse width of the drive pulse voltage and of the optical sensor. The discharge probability of the first type of non-regular discharge due to noise components other than the discharge due to the photoelectric effect of the optical sensor, the pulse width of the drive pulse voltage, and the received amount of the optical sensor, which are generated independently of the received light amount. It is characterized by including a ninth step of calculating the discharge probability of the second type of non-normal discharge due to the noise component, which is generated independently of the above.

Further, in the method for measuring the amount of received light of the light detection system of the present invention, a drive pulse voltage is periodically applied to the electrodes of the light sensor when the light sensor for detecting the light emitted from the light source is in the first state of being shielded from light. Discharge of the optical sensor based on the first step of applying, the second step of detecting the discharge current of the optical sensor in the first state, and the discharge current in the first state. The first step is based on the third step of detecting the above, the number of times the drive pulse voltage is applied by the first step, and the number of discharges detected in the third step while the drive pulse voltage is being applied. In the fourth step of calculating the discharge probability in the state of, and in the second state where the optical sensor is shielded from light and the pulse width of the drive pulse voltage is different from the first state, the optical sensor A fifth step of periodically applying a drive pulse voltage to the electrodes, a sixth step of detecting the discharge current of the optical sensor in the second state, and the discharge in the second state. The seventh step of detecting the discharge of the optical sensor based on the current, the number of times the drive pulse voltage is applied by the fifth step, and the discharge detected in the seventh step while the drive pulse voltage is applied. The eighth step of calculating the discharge probability in the second state based on the number of times of the above, and the second step in which the optical sensor can collect light and the pulse width of the drive pulse voltage is the same as that in the first state. A ninth step of periodically applying a drive pulse voltage to the electrodes of the optical sensor in the third state, and a tenth step of detecting the discharge current of the optical sensor in the third state. The eleventh step of detecting the discharge of the optical sensor based on the discharge current in the third state, the number of times the drive pulse voltage is applied by the ninth step, and the application of the drive pulse voltage The twelfth step of calculating the discharge probability in the third state based on the number of discharges detected in the eleventh step, and the pulse of the drive pulse voltage while the optical sensor can collect light. The thirteenth step of periodically applying a drive pulse voltage to the electrode of the optical sensor when the width is the same as the second state and the fourth state, and the discharge of the optical sensor in the fourth state. The 14th step of detecting the current, the 15th step of detecting the discharge of the optical sensor based on the discharge current in the 4th state, and the application of the drive pulse voltage by the 13th step. Number of times and this drive pulse The sixteenth step of calculating the discharge probability in the fourth state based on the number of discharges detected in the fifteenth step while applying a voltage, and the known sensitivity parameter of the optical sensor are described above. The reference pulse width of the drive pulse voltage, the reference light receiving amount of the optical sensor, the pulse width of the drive pulse voltage is the reference pulse width, and the received light amount of the optical sensor is the reference light receiving amount in a state where the light sensor can collect light. Refer to the storage unit that stores the discharge probability of the normal discharge in advance when the amount is used, and when the sensitivity parameters stored in this storage unit and the first, second, third, and fourth states are present. Based on the discharge probability calculated in the 4th, 8th, 12th, and 16th steps and the pulse width of the drive pulse voltage in the 1st, 2nd, 3rd, and 4th states, It is characterized by including a seventeenth step of calculating the amount of light received by the optical sensor when the optical sensor is in the third and fourth states where light can be collected.

According to the present invention, by providing the applied voltage generation unit, the current detection unit, the discharge determination unit, the first discharge probability calculation unit, the storage unit, and the second discharge probability calculation unit, the pulse width of the drive pulse voltage can be adjusted. The discharge probability of the first type of non-regular discharge due to noise components other than the discharge due to the photoelectric effect of the optical sensor, which occurs depending on and does not depend on the amount of light received by the optical sensor, and the pulse width of the drive pulse voltage. It is possible to calculate the discharge probability of the second type of non-regular discharge due to the noise component, which is generated independently of the amount of light received by the optical sensor. As a result, in the present invention, it is possible to realize the life determination of the optical sensor based on the discharge probability of these non-regular discharges.

Further, in the present invention, by providing the applied voltage generation unit, the current detection unit, the discharge determination unit, the discharge probability calculation unit, the storage unit, and the light receiving amount calculation unit, other than the normal discharge of the optical sensor by the light generated from the light source. The amount of received light excluding the noise component can be calculated. As a result, in the present invention, even when the discharge probability of the non-regular discharge due to the noise component is unknown, the light receiving amount excluding the noise component can be calculated, and the presence or absence of the flame can be accurately determined from the obtained light receiving amount. It can be detected well. Further, in the present invention, it is possible to reduce the possibility that the life of the optical sensor is erroneously determined depending on the amount of light received including the noise component.

FIG. 1 is a block diagram showing a configuration of a photodetection system according to an embodiment of the present invention. FIG. 2 is a waveform diagram showing a drive pulse applied to the optical sensor and a detection voltage detected by the current detection circuit in the embodiment of the present invention. FIG. 3 is a flowchart illustrating the operation of the photodetection system according to the embodiment of the present invention. FIG. 4 is a flowchart illustrating the operation of the photodetection system according to the embodiment of the present invention. FIG. 5 is a block diagram showing a configuration example of a computer that realizes the photodetection system according to the embodiment of the present invention.

[Example]
Hereinafter, a method for measuring non-regular discharge due to noise components and a method for measuring the amount of received light will be described. An optical sensor that utilizes the photoelectric effect is a photocell that energizes when a photon hits an electrode. Energization proceeds under the following conditions.

[Operation of optical sensor]
When a photon hits one of the electrodes while a voltage is applied between the pair of electrodes of the optical sensor, photoelectrons are likely to jump out and energize while causing electron avalanche (a discharge current flows between the electrodes).
While the voltage is applied between the electrodes, the optical sensor continues to be energized. Alternatively, as soon as the energization of the optical sensor is confirmed, the energization is stopped by lowering the voltage. In this way, the optical sensor ends energization when the voltage between the electrodes drops.

_{Let P 1} be the probability that the optical sensor will be discharged when one photon hits the electrode of the optical sensor. _{Also, let P 2} be the probability that the optical sensor will be discharged when two photons hit the electrodes of the optical sensor. Since P ₂ is the opposite of the probability that neither the first photon nor the second photon will be discharged, _{the relationship between P 2} and P ₁ is expressed by Eq. (1).

_{Generally, let P n be} the probability that the photosensor will be discharged when _{n photons hit the electrodes of the photosensor, and P m} be the probability that the photosensor will be discharged when m photons hit the electrodes of the photosensor. (N and m are natural numbers), and equations (2) and (3) hold as in equation (1).

From equations (2) and (3), equation (4) can be derived as the relationship between _{P n} and P _m.

If the number of photons flying to the electrodes of the optical sensor per unit time is E, and the time for applying a voltage equal to or higher than the discharge start voltage of the optical sensor between the electrodes (hereinafter referred to as pulse width) is T, voltage application 1 The number of photons that collide with the electrode per turn is represented by ET. Therefore, the relationship between the number of photons E, the pulse width T, and the discharge probability P when the same optical sensor is operated under a certain condition A and another condition B is as shown in the equation (5). Here, if the reference number of photons _{is set to E 0} and Q = E / E ₀ , then the equation (6) is obtained. Here, Q is referred to as a light receiving amount.

[Configuration and operation of optical detection system]
FIG. 1 is a block diagram showing a configuration of a photodetection system according to an embodiment of the present invention. The photodetector system drives the photosensor and calculates the discharge probability and the amount of light received from the light source from the drive result of the photosensor. This light detection system includes an optical sensor 1 that detects light (ultraviolet rays) generated from a light source 100 such as a flame, an LED, or a lamp, an external power supply 2, a computing device 3 to which the optical sensor 1 and the external power supply 2 are connected. It includes a shutter 21 provided between the light source 100 and the light sensor 1, a shutter drive unit 22 that drives the shutter 21, and a shutter control unit 23 that controls the shutter 21 through the shutter drive unit 22. The shutter 21 and the shutter driving unit 22 form a light-shielding means.

The optical sensor 1 is supported by a cylindrical enclosure with both ends closed, two electrode pins penetrating both ends of the enclosure, and electrode pins inside the enclosure in parallel with each other. It is composed of a phototube provided with two electrodes. In such an optical sensor 1, when a predetermined voltage is applied between the electrodes via the electrode support pins and ultraviolet rays are applied to one of the electrodes arranged to face the light source 100, the electrode has a photoelectric effect. Electrons are emitted and a discharge current flows between the electrodes.

The external power supply 2 comprises, for example, an AC commercial power supply having a voltage value of 100 [V] or 200 [V].

The arithmetic unit 3 includes a power supply circuit 11 connected to an external power supply 2, an applied voltage generation circuit 12 and a trigger circuit 13 connected to the power supply circuit 11, a terminal 1b on the downstream side of the optical sensor 1, and a grounding line GND. The voltage (reference voltage) Va generated at the connection point Pa between the resistors R1 and R2 of the voltage dividing resistor 14 and the voltage dividing resistor 14 composed of the resistors R1 and R2 connected in series between the two flows through the optical sensor 1. It includes a current detection circuit 15 that detects as a current I, and a processing circuit 16 in which an applied voltage generation circuit 12, a trigger circuit 13, and a current detection circuit 15 are connected.

The power supply circuit 11 supplies AC power input from the external power supply 2 to the applied voltage generation circuit 12 and the trigger circuit 13. Further, the electric power for driving the arithmetic unit 3 is acquired from the power supply circuit 11. However, it can also be configured to acquire driving power from another power source regardless of AC / DC.

The applied voltage generation circuit 12 (applied voltage generation unit) boosts the AC voltage applied by the power supply circuit 11 to a predetermined value and applies it to the optical sensor 1. In this embodiment, a pulsed voltage of 200 [V] synchronized with the rectangular pulse PS from the processing circuit 16 ( _{voltage equal to or higher than the discharge start voltage VST} of the optical sensor 1) is generated as the drive pulse voltage PM, and this generation is performed. The driven pulse voltage PM is applied to the optical sensor 1. FIG. 2 shows the drive pulse voltage PM applied to the optical sensor 1. The drive pulse voltage PM is synchronized with the rectangular pulse PS from the processing circuit 16, and its pulse width T is equal to the pulse width of the rectangular pulse PS. The rectangular pulse PS from the processing circuit 16 will be described later.

The trigger circuit 13 detects a predetermined value point of the AC voltage applied by the power supply circuit 11, and inputs the detection result to the processing circuit 16. In this embodiment, the trigger circuit 13 detects the minimum value point at which the voltage value becomes the minimum as a predetermined value point (at the time of triggering). By detecting a predetermined value point for the AC voltage in this way, it is possible to detect one cycle of the AC voltage.

The voltage dividing resistor 14 generates a reference voltage Va as a voltage dividing voltage between the resistors R1 and R2, and inputs the reference voltage Va to the current detection circuit 15. Here, the voltage value of the drive pulse PM applied to the terminal 1a on the upstream side of the optical sensor 1 is as high as 200 [V] as described above, so that a current is generated between the electrodes of the optical sensor 1. If the voltage generated in the terminal 1b on the downstream side when the current flows is input to the current detection circuit 15 as it is, a large load will be applied to the current detection circuit 15. Therefore, in this embodiment, the voltage dividing resistor 14 generates a reference voltage Va having a low voltage value, and this is input to the current detection circuit 15.

The current detection circuit 15 (current detection unit) detects the reference voltage Va input from the voltage dividing resistor 14 as the discharge current I of the optical sensor 1, and inputs the detected reference voltage Va as the detection voltage Vpv to the processing circuit 16. do.
The processing circuit 16 includes a square pulse generation unit 17, an A / D conversion unit 18, a sensitivity parameter storage unit 19, and a central processing unit 20.

The rectangular pulse generation unit 17 generates a rectangular pulse PS having a pulse width T every time the trigger circuit 13 detects the trigger time point, that is, every cycle of the AC voltage applied from the power supply circuit 11 to the trigger circuit 13. The square pulse PS generated by the square pulse generation unit 17 is sent to the applied voltage generation circuit 12. The rectangular pulse generation unit 17 and the applied voltage generation circuit 12 can adjust the pulse width of the drive pulse voltage PM. That is, when the rectangular pulse generation unit 17 sets the pulse width of the rectangular pulse PS to a desired value, the drive pulse voltage PM having a pulse width equal to that of the rectangular pulse PS is output from the applied voltage generation circuit 12.
The A / D conversion unit 18 A / D converts the detection voltage Vpv from the current detection circuit 15 and sends it to the central processing unit 20.

The central processing unit 20 is realized by hardware including a processor and a storage device and a program that realizes various functions in cooperation with these hardware, and includes a discharge determination unit 201 and discharge probability calculation units 202 and 203. , It functions as a pulse application number integration unit 204, an application number determination unit 205, a light reception amount calculation unit 206, and a light reception amount determination unit 207.

In the central processing unit 20, the discharge determination unit 201 detects the discharge of the optical sensor 1 based on the discharge current of the optical sensor 1 detected by the current detection circuit 15. Specifically, the discharge determination unit 201 determines the detection voltage Vpv input from the A / D conversion unit 18 each time the drive pulse voltage PM is applied to the optical sensor 1 (every time a rectangular pulse PS is generated). It is compared with a predetermined threshold voltage Vth (see FIG. 2), and when the detected voltage Vpv exceeds the threshold voltage Vth, it is determined that the optical sensor 1 has been discharged, and the number of discharges n is increased by 1.

The discharge probability calculation unit 202 performs the discharge determination unit 201 when the number of times N of the drive pulse voltage PM applied to the optical sensor 1 exceeds a predetermined number (when the number of pulses of the rectangular pulse PS exceeds a predetermined number). The discharge probability P of the optical sensor 1 is calculated from the number of discharges n detected by the above and the number of times N of application of the drive pulse voltage PM.

This discharge probability P is output as a frame signal. Certain operating conditions, the received light amount _{Q 0 (Q 0 ≠ 0)} , the discharge probability P ₀ of the pulse width T ₀ is known. For example, in the shipping inspection of a photodetection system, there is a method of measuring the discharge probability P at a predetermined light receiving amount and pulse width. At this time, the relationship between the received light amount Q, the pulse width T, and the discharge probability P is given by the equation (7). However, P = 0 is Q = 0. In the present invention, when P = 0 and P = 1, it is excluded from the calculation process of the received light amount Q.

Now, Q ₀ , T ₀ , and P ₀ are known, and T is known because the pulse width is controlled by the photodetection system. If the drive pulse voltage PM is applied to the optical sensor 1 a plurality of times, the number of discharges n is measured, and the discharge probability P is calculated, the light receiving amount Q, which is an unknown number, can be calculated from the equation (7). This received light amount Q may be output as a frame signal.

[Operation of photodetection system considering noise]
From the equation (7), it is assumed that the discharge probability P _{aA at} a certain operating condition, the light receiving amount Q ₀ , and the pulse width T ₀ is known, and the relationship between the received light amount Q, the pulse width T, and the discharge probability P is expressed by the equation (8). Given.

The following two can be considered as the relationship between the discharge of the optical sensor 1 and the time.
(A) Discharge that appears with a uniform probability while the drive pulse voltage PM is applied (Equation (8)).
(B) Drive pulse voltage A discharge that appears when the PM rises or falls.

Next, the relationship between the discharge of the optical sensor 1 and the amount of light received can be considered as follows.
(A) A discharge that appears according to the relationship between the amount of light received and the formula (8).
(B) Discharge that appears regardless of the amount of light received.

As shown in the matrix of Table 1, the noise discharge of the optical sensor 1 can be categorized by the combination of (a), (b) and (A), (B). In the present invention, the combination of (a) and (A) (aA), the combination of (a) and (B) (aB), the combination of (b) and (A) (bA), (b) and (B) It is highly probable that the combination of (bB) is surely observed.

The discharge of the combination of aA is a normal discharge called "sensitivity" (already incorporated in equation (8)). The discharge of the combination of aB is a discharge irrelevant to the amount of ultraviolet rays triggered by thermions and the like. The discharge of the combination of bA is a discharge that depends on the amount of light among the discharges that are limitedly generated when the drive pulse voltage rises or falls due to the inrush current or the residual ions. The discharge of the combination of bB is a discharge that does not depend on the amount of light among the discharges that are limitedly generated when the drive pulse voltage rises or falls due to the inrush current or the residual ions.

It should be noted that the ones categorized in Table 1 are not all of the UV (ultraviolet) failure modes. For example, there are failure modes not included in Table 1, such as discharge not being cut off and sensitivity wavelengths being different.

The above discharge of aA and the noise discharge of the three types of aB, bA, and bB can be expressed in the form of equation (9).

In equation (9), P _aB is the light receiving amount Q, the discharge probability of aB at the pulse width T, P _bA is the light receiving amount Q, the discharge probability of bA at the pulse width T, P _bB is the light receiving amount Q, bB at the pulse width T. Discharge probability of.

[Calculation method of discharge probabilities P _aB and P _bB]
When the light is not received in the formula (9) (for example, when the shutter is closed), if the light receiving amount Q is 0, the formula (10) is obtained. Here, P ^* is a discharge probability measurement value when no light is received.

The measurement is performed with the pulse width T _{1 and the discharge probability 1} P ^* is measured.

Further, the measurement is performed with the pulse width T ₂ (T ₁ ≠ T ₂ ), and the discharge probability ₂ P ^* is measured.

By dividing the equation (11) by the equation (12), the equation (13) is obtained, so that the discharge probability P _aB can be calculated according to the equation (14).

By substituting the equation (14) into the equation (10), the discharge probability P _bB can be calculated as in the equation (15).

Therefore, the discharge probabilities P _aB and P _bB can be obtained by measuring the discharge probabilities ₁ P ^* and ₂ P ^* when the pulse widths T ₁ and T _{2 are not received, respectively.}

[Calculation method of received light amount Q]
_{It is assumed that the discharge probability P aA} is known when the light receiving amount Q is unknown, and the discharge probability P a _B can be calculated by the equation (14).
Assuming that the discharge probability when the _{pulse width is T 1 while} the optical sensor 1 is capable of daylighting _{is 1} P, the equation (9) can be modified as the equation (16).

Similarly, if the discharge probability when the _{pulse width is T 2} while the optical sensor 1 is capable of daylighting _{is 2} P, the equation (9) can be modified as the equation (17).

Dividing equation (16) by equation (17) yields equation (18).

By modifying the equation (18) and substituting the equation (14), the light receiving amount Q can be obtained as shown in the equation (19).

Therefore, when the discharge probability P _aA is known, for example, the discharge probability P _aA has already been measured in the shipping inspection of the photodetector system, the variation in measurement sensitivity is small, and the representative value can be used. _{When it is considered that the discharge probability P aA} does not change during the life, the measurement is accompanied by the pulse width adjustment in the state where the optical sensor 1 is shielded from light, and the pulse width is adjusted in the state where the optical sensor 1 can collect light. By performing the measurement, it is possible to obtain the light receiving amount Q from which _{the noise components P aB} , P _bA , and P _{bB are removed.}

Hereinafter, the operation of the photodetector system of this embodiment will be described in more detail. 3 and 4 are flowcharts for explaining the operation of the photodetection system of this embodiment.
The shutter control unit 23 selectively outputs a shutter open signal (voltage) for opening and closing the shutter 21 to close the shutter (first and second states in which the optical sensor 1 is shielded from light) and open the shutter. It is possible to switch between (third and fourth states in which the optical sensor 1 can collect light).

In this embodiment, the shutter open signal is not output in the initial state at the time of shipping inspection of the photodetection system or at the site where the photodetection system is installed. Therefore, the shutter drive unit 22 keeps the shutter 21 closed (step S100 in FIG. 3). As a result, the light from the light source 100 is blocked by the shutter 21, and the light incident on the optical sensor 1 is blocked.

The discharge probability calculation unit 202 initializes the variable i for pulse width control to 1 (step S101 in FIG. 3). When the variable i is smaller than 3 (YES in step S102 in FIG. 3), the discharge probability calculation unit 202 instructs the rectangular pulse generation unit 17 to start applying the drive pulse voltage PM.

In response to the instruction from the discharge probability calculation unit 202, the square pulse generation unit 17 sets the pulse width of the square pulse PS to a predetermined value _Ti = T ₁ . By setting this pulse width, the applied voltage generation circuit 12 applies _{the drive pulse voltage PM having the pulse width Ti} = T ₁ between the pair of terminals 1a and 1b of the optical sensor 1 (step S103 in FIG. 3).

The discharge determination unit 201 compares the detection voltage Vpv from the current detection circuit 15 with the predetermined threshold voltage Vth, and determines that the optical sensor 1 has been discharged when the detection voltage Vpv exceeds the threshold voltage Vth. .. When the discharge determination unit 201 determines that the optical sensor 1 has been discharged, the discharge determination unit 201 counts the number of discharges n _i ^* = n ₁ ^* with this as one (step S104 in FIG. 3). It goes without saying that the initial values of the number of discharges n ₁ ^* and the number of times the drive pulse voltage PM is applied N ₁ ^{*, which will be described later, are both 0.} In this way, the processes of steps S103 and S104 are repeatedly executed.

The pulse application number integrating unit 204 counts the number of times the drive pulse voltage PM is applied N _i ^* by counting the rectangular pulse PS output from the rectangular pulse generation unit 17.
Applying number determination section 205 compares the driving pulse voltage PM of application times N _i ^* with a predetermined number Nth ^*.

Discharge probability calculation unit 202, a step S103 the number of applications of the driving pulse voltage PM from at start of the application of the pulse width T _i = T ₁ of the drive pulse voltage PM by N _i ^* = N ₁ ^* exceeds a predetermined number Nth ^* When the application number determination unit 205 determines (YES in step S105 of FIG. 3), the number of times the drive pulse voltage PM is applied N _i ^* = N ₁ ^* and the number of discharges detected by the discharge determination unit 201 n _i ^* = Based on n ₁ ^* _{, the discharge probability 1} P ^* is calculated by the equation (20) (step S106 in FIG. 3).
₁ P ^* = n ₁ ^* / N ₁ ^*・ ・ ・ (20)

After calculating the discharge probability ₁ P ^* , the discharge probability calculation unit 202 increases the variable i for pulse width control by 1 (step S107 in FIG. 3). When the variable i is smaller than 3 (YES in step S102), the discharge probability calculation unit 202 instructs the rectangular pulse generation unit 17 to start applying the drive pulse voltage PM again.

In response to the instruction from the discharge probability calculation unit 202, the square pulse generation unit 17 temporarily stops the output of the square wave PS, and then sets the pulse width of the square wave PS to a predetermined value T _i = T ₂ (T ₁ ≠ T). Set to _2). By setting this pulse width, the applied voltage generation circuit 12 applies _{the drive pulse voltage PM of the pulse width Ti} = T ₂ between the pair of terminals 1a and 1b of the optical sensor 1 (step S103).

The discharge determination unit 201 compares the detection voltage Vpv from the current detection circuit 15 with the threshold voltage Vth in the same manner as described above, and determines that the optical sensor 1 has been discharged when the detection voltage Vpv exceeds the threshold voltage Vth. The number of discharges n _i ^* = n ₂ ^* is increased by 1 (step S104). It goes without saying that the initial values of the number of discharges n ₂ ^* and the number of times the drive pulse voltage PM is applied N ₂ ^{*, which will be described later, are both 0.} In this way, the processes of steps S103 and S104 are repeatedly executed.

Discharge probability calculation unit 202 includes a pulse width T _i = the number of applications of the driving pulse voltage PM from time of application start of T ₂ of the drive pulse voltage PM N _i ^* = N ₂ ^* in step S103 exceeds a predetermined number Nth ^* When the application number determination unit 205 determines (YES in step S105), the number of times the drive pulse voltage PM is applied N _i ^* = N ₂ ^* and the number of discharges detected by the discharge determination unit 201 n _i ^* = n ₂ ^{Based on *} _{, the discharge probability 2} P ^* is calculated by the equation (21) (step S106).
₂ P ^* = n ₂ ^* / N ₂ ^*・ ・ ・ (21)

After calculating the discharge probability ₂ P ^* , the discharge probability calculation unit 202 increases the variable i for pulse width control by 1 (step S107).
In the sensitivity parameter storage unit 19, as known sensitivity parameters of the optical sensor 1, the reference pulse width T of the drive pulse voltage PM and the pulse width of the drive pulse voltage PM with the optical sensor 1 shielded from light are the reference pulse width T. The discharge probability P ^{* at} the time of is stored in advance. Either one of the above pulse widths T ₁ and T ₂ (T ₁ ≠ T ₂ ) may be the same as the reference pulse width T. Further, in the sensitivity parameter storage unit 19, as known sensitivity parameters of the optical sensor 1, the reference light receiving amount Q ₀ of the optical sensor 1, the reference pulse width T ₀ of the drive pulse voltage PM, and the pulse width of the drive pulse voltage PM are stored. _{The discharge probability P aA} of the normal discharge when the light reception amount of the optical sensor 1 is the reference pulse width T ₀ and the light reception amount of the optical sensor 1 is the reference light reception amount Q ₀ and the light sensor 1 can collect light is stored in advance. Either one of the above pulse widths T ₁ and T ₂ (T ₁ ≠ T ₂ ) may be the same as the _{reference pulse width T 0.}

The sensitivity parameter stored in the sensitivity parameter storage unit 19 shall be measured in advance, for example, in the shipping inspection of the photodetection system. The discharge probability P ^* can be measured in the same manner as the discharge probabilities ₁ P ^* and ₂ P ^*.
The discharge probability calculation unit 203 calculates the discharge probability by the discharge probability calculation unit 202 when the measurement in the light-shielded state of the optical sensor 1 is completed, that is, when the variable i reaches 3 (NO in step S102). ₁ P ^* , ₂ P ^* _{, the pulse widths T 1} and T ₂ of the drive pulse voltage PM when the discharge probabilities ₁ P ^* and ₂ P ^* _{are obtained, and the parameter T 0} stored in the sensitivity parameter storage unit 19. Based on the above, the discharge probability P _aB of the non-normal discharge is calculated by the equation (14) (step S108 in FIG. 3). As described above, the discharge probability P _aB is due to a noise component other than the discharge due to the photoelectric effect of the optical sensor 1, which is generated depending on the pulse width of the drive pulse voltage PM and not depending on the amount of light received by the optical sensor 1. The probability of discharge.

Subsequently, the discharge probability calculation unit 203 sets the discharge probabilities ₁ P ^* and ₂ P ^* calculated by the discharge probability calculation unit 202 and the pulses of the drive pulse voltage PM when the _{discharge probabilities 1} P ^* and ₂ P ^{* are obtained.} Based on the widths T ₁ and T ₂ ^{and the parameters T and P *} stored in the sensitivity parameter storage unit 19, _{the discharge probability P bB} of the non-normal discharge is calculated by the equation (15) (step 3 in FIG. 3). S109). The discharge probability P _bB is the probability of discharge due to a noise component other than the discharge due to the photoelectric effect of the optical sensor 1, which is generated independently of the pulse width of the drive pulse voltage PM and the amount of light received by the optical sensor 1 as described above. ..

Next, the shutter control unit 23 outputs a shutter open signal when the calculation _{of the discharge probabilities P aB} and P _{bB is completed.}
The shutter drive unit 22 opens the shutter 21 when a shutter open signal is output from the shutter control unit 23 (step S110 in FIG. 3). When the shutter 21 is opened, the optical sensor 1 is in a state where it can collect light. The light from the light source 100 is incident on the optical sensor 1.

Next, the discharge probability calculation unit 202 initializes the variable i for pulse width control to 1 in the same manner as in step S101 (step S111 in FIG. 3). When the variable i is smaller than 3 (YES in step S112 in FIG. 3), the discharge probability calculation unit 202 instructs the rectangular pulse generation unit 17 to start applying the drive pulse voltage PM.

In response to the instruction from the discharge probability calculation unit 202, the square pulse generation unit 17 sets the pulse width of the square pulse PS to a predetermined value _Ti = T ₁ . By setting this pulse width, the applied voltage generation circuit 12 applies _{the drive pulse voltage PM having the pulse width Ti} = T ₁ between the pair of terminals 1a and 1b of the optical sensor 1 (step S113 in FIG. 3).

The discharge determination unit 201 compares the detection voltage Vpv from the current detection circuit 15 with the threshold voltage Vth in the same manner as in step S104, and determines that the optical sensor 1 has been discharged when the detection voltage Vpv exceeds the threshold voltage Vth. , The number of discharges n _i = n ₁ is increased by 1 (step S114 in FIG. 3). Needless to say, the initial values of the number of discharges n _{1 and the number of times N 1} of the drive pulse voltage PM applied, which will be described later, are both 0. In this way, the processes of steps S113 and S114 are repeatedly executed.

The discharge probability calculation unit 202 determines that the number of applications of the drive pulse voltage PM from the start of application of the drive pulse voltage PM of the _{pulse width T i} = T _{1 in step S113 N i} = N ₁ exceeds a predetermined number Nth. When the unit 205 determines (YES in step S115 of FIG. 3), the number of times the drive pulse voltage PM is applied N _i = N _{1 at this time and the number of discharges n i} = n ₁ detected by the discharge determination unit 201. _{, The discharge probability 1} P is calculated by the equation (22) (step S116 in FIG. 3).
₁ P = n ₁ / N ₁ ... (22)

After calculating the discharge probability ₁ P, the discharge probability calculation unit 202, a variable i for the pulse width control is increased by one (Fig. 3 step S117). When the variable i is smaller than 3 (YES in step S112), the discharge probability calculation unit 202 instructs the rectangular pulse generation unit 17 to start applying the drive pulse voltage PM again.

In response to the instruction from the discharge probability calculation unit 202, the square pulse generation unit 17 temporarily stops the output of the square wave PS, and then sets the pulse width of the square wave PS to a predetermined value T _i = T ₂ (T ₁ ≠ T). Set to _2). By setting this pulse width, the applied voltage generation circuit 12 applies _{the drive pulse voltage PM of the pulse width Ti} = T ₂ between the pair of terminals 1a and 1b of the optical sensor 1 (step S113).

The discharge determination unit 201 compares the detection voltage Vpv from the current detection circuit 15 with the threshold voltage Vth in the same manner as described above, and determines that the optical sensor 1 has been discharged when the detection voltage Vpv exceeds the threshold voltage Vth. The number of discharges n _i = n ₂ is increased by 1 (step S114). Needless to say, the initial values of the number of discharges n _{2 and the number of times N 2} of the drive pulse voltage PM applied, which will be described later, are both 0. In this way, the processes of steps S113 and S114 are repeatedly executed.

The discharge probability calculation unit 202 determines that the number of applications of the drive pulse voltage PM from the start of application of the drive pulse voltage PM of the _{pulse width T i} = T _{2 in step S113 N i} = N ₂ exceeds a predetermined number Nth. When the unit 205 determines (YES in step S115), the equation is based on the _{number of times the drive pulse voltage PM is applied N i} = N _{2 and the number of discharges n i} = n ₂ detected by the discharge determination unit 201. (23) by calculating a discharge probability ₂ P (step S116).
₂ P = n ₂ / N ₂ ... (23)

After calculating the discharge probability ₂ P, discharge probability calculation unit 202, a variable i for the pulse width control is increased by one (step S117).
The light receiving amount calculation unit 206 calculates the discharge probability by the discharge probability calculation unit 202 when the measurement in the state where the light sensor 1 can collect light is completed, that is, when the variable i reaches 3 (NO in step S112). _{When 1} P and ₂ P are greater than 0 and less than 1 (YES in step S118 in FIG. 4), the discharge probabilities ₁ P ^* , ₂ P ^* , ₁ P, and ₂ P calculated by the discharge probability calculation unit 202 are discharged. probability ₁ P ^*, ₁ and the pulse width T ₁ of the drive pulse voltage PM when seeking P, discharge probability ₂ P ^*, ₂ a pulse width T ₂ of the drive pulse voltage PM when seeking P, the sensitivity parameter storage _{Based on the parameters Q 0} , T ₀ , and P _aA stored in the unit 19, the received light amount Q is calculated by the equation (19) (step S119 in FIG. 4).

_{Further, when at least one of the discharge probabilities 1} P and ₂ P calculated by the discharge probability calculation unit 202 is 0 (NO in step S118), the light receiving amount calculation unit 206 sets the light receiving amount Q to 0 or sets it to 0. Exception processing is performed so that the received light amount Q cannot be calculated (step S120 in FIG. 4). _{Further, when at least one of the discharge probabilities 1} P and ₂ P is 1 (NO in step S118), the light receiving amount calculation unit 206 performs exception processing for disabling the light receiving amount Q (step S120).

Next, the light receiving amount determination unit 207 compares the light receiving amount Q calculated by the light receiving amount calculating unit 206 with the predetermined light receiving amount threshold Qth (step S121 in FIG. 4), and the light receiving amount Q exceeds the light receiving amount threshold Qth. If (YES in step S121), it is determined that there is a flame (FIG. 4, step S122). Further, when the light receiving amount Q is equal to or less than the light receiving amount threshold Qth (NO in step S121), the light receiving amount determining unit 207 determines that there is no flame (FIG. 4, step S123).

As can be seen from the above description, in this embodiment, it is possible to calculate _{the discharge probabilities P aB} and P _bB of the non-regular discharge that occurs regardless of the amount of light received by the optical sensor 1. Discharge probability P _aB with the degradation of the optical sensor 1, it is considered that P _bB changes, discharge probability P _aB, it is possible to realize a life determination of the optical sensor 1 based on P _bB.

Further, in this embodiment, the light receiving amount Q excluding the noise component can be calculated. As a result, in this embodiment, it is possible to accurately detect the presence or absence of a flame from the obtained light receiving amount Q. Further, in this embodiment, it is possible to reduce the possibility that the life of the optical sensor 1 is erroneously determined by the light receiving amount Q including the noise component.

When only the discharge probabilities P _aB and P _bB are calculated, the light receiving amount calculation unit 206, the light receiving amount determination unit 207, and the processing after step S110 are unnecessary. Further, when calculating only the received light amount Q, the processes of the discharge probability calculation unit 203 and steps S108 and S109 are unnecessary.

In this embodiment, the present invention is applied to a photodetection system with a shutter mechanism, but it is also possible to apply the present invention to a photodetection system without a shutter mechanism. In this case, when performing the processing of steps S101 to S109 at the time of shipping inspection of the photodetection system or at the site where the photodetection system is installed, for example, by attaching a cover to the photosensor 1, the photosensor 1 can be The light may be shielded. At this time, a signal indicating that the optical sensor 1 is in a light-shielded state is input to the photodetection system by, for example, a user's operation. As a result, the arithmetic unit 3 of the photodetector system performs the processes of S101 to S109.

Further, when performing the processes of steps S111 to S117, the light sensor 1 may be released from the light-shielded state so that the light sensor 1 can collect light. At this time, a signal indicating that the photosensor 1 is in a state where light can be collected is input to the photodetection system by, for example, a user's operation. As a result, the arithmetic unit 3 of the photodetector system performs the processes of S111 to S117.

In this embodiment, the case where the light source 100 is a flame is described as an example, but the photodetection system of the present invention can be applied to a light source 100 other than the flame.

The sensitivity parameter storage unit 19 and the central processing unit 20 described in this embodiment can be realized by a computer equipped with a CPU (Central Processing Unit), a storage device, and an interface, and a program for controlling these hardware resources. can.

A configuration example of this computer is shown in FIG. The computer includes a CPU 300, a storage device 301, and an interface device (I / F) 302. The applied voltage generation circuit 12, the rectangular pulse generation unit 17, the A / D conversion unit 18, the shutter control unit 23, and the like are connected to the I / F 302. In such a computer, a program for realizing the discharge probability calculation method and the received light amount measuring method of the present invention is stored in the storage device 301. The CPU 300 executes the process described in this embodiment according to the program stored in the storage device 301.

The present invention can be applied to flame detection systems. The present invention can also be applied to the detection of light other than flame.

1 ... optical sensor, 2 ... external power supply, 3 ... computing device, 11 ... power supply circuit, 12 ... applied voltage generation circuit, 13 ... trigger circuit, 14 ... voltage dividing resistor, 15 ... current detection circuit, 16 ... processing circuit, 17 ... Rectangular pulse generator, 18 ... A / D conversion unit, 19 ... Sensitivity parameter storage unit, 20 ... Central processing unit, 21 ... Shutter, 22 ... Shutter drive unit, 23 ... Shutter control unit, 100 ... Light source, 201 ... Discharge Judgment unit, 202, 203 ... Discharge probability calculation unit, 204 ... Pulse application number integration unit, 205 ... Application number determination unit, 206 ... Light receiving amount calculation unit, 207 ... Light reception amount determination unit.

Claims (9)

An optical sensor configured to detect the light emitted by a light source,
An applied voltage generator configured to periodically apply a drive pulse voltage to the electrodes of this optical sensor,
A current detection unit configured to detect the discharge current of the optical sensor, and
A discharge determination unit configured to detect the discharge of the optical sensor based on the discharge current detected by the current detection unit, and a discharge determination unit.
The applied voltage generator determines each of the first state in which the optical sensor is shielded from light and the second state in which the optical sensor is shielded from light and the pulse width of the drive pulse voltage is different from the first state. A first discharge probability calculation unit configured to calculate the discharge probability based on the number of times the drive pulse voltage is applied and the number of discharges detected by the discharge determination unit during the application of the drive pulse voltage. ,
As known sensitivity parameters of the optical sensor, the reference pulse width of the drive pulse voltage and the discharge probability when the pulse width of the drive pulse voltage is the reference pulse width in a state where the optical sensor is shielded from light are stored in advance. With a storage unit configured to
Sensitivity parameters stored in the storage unit, discharge probabilities calculated by the first discharge probability calculation unit in the first and second states, and discharge probabilities in the first and second states. Other than discharge due to the photoelectric effect of the optical sensor, which is generated depending on the pulse width of the drive pulse voltage and not depending on the amount of light received by the optical sensor, based on the pulse width of the drive pulse voltage. The second type of non-regular discharge due to the noise component, which occurs independently of the discharge probability of the first type of non-normal discharge due to the noise component, the pulse width of the drive pulse voltage, and the amount of light received by the optical sensor. An optical detection system including a second discharge probability calculation unit configured to calculate the discharge probability of a discharge. In the light detection system according to claim 1,
The second discharge probability calculation unit sets the reference pulse width of the drive pulse voltage to T ₀ , T, and the discharge probability when the pulse width of the drive pulse voltage is the reference pulse width T in a state where the optical sensor is shielded from light. Is P ^* , the discharge probability calculated by the first discharge probability calculation unit in the first state is ₁ P ^* , and is calculated by the first discharge probability calculation unit in the second state. The discharge probability is ₂ P ^* , the pulse width of the drive pulse voltage in the first state is T ₁ , and the pulse width of the drive pulse voltage in the second state is T ₂ (T ₁ ≠ T). ₂ ) When the discharge probability of the first-class non-regular discharge is P _aB and the discharge probability of the second-class non-regular discharge is P _bB ,

To calculate _{the discharge probability P aB} of the first-class non-regular discharge.

A photodetection system characterized by calculating _{the discharge probability P bB} of the second type of non-regular discharge. An optical sensor configured to detect the light emitted by a light source,
An applied voltage generator configured to periodically apply a drive pulse voltage to the electrodes of this optical sensor,
A current detection unit configured to detect the discharge current of the optical sensor, and
A discharge determination unit configured to detect the discharge of the optical sensor based on the discharge current detected by the current detection unit, and a discharge determination unit.
A first state in which the optical sensor is shielded from light, a second state in which the optical sensor is shielded from light and the pulse width of the drive pulse voltage is different from the first state, and the optical sensor can collect light. A third state in which the pulse width of the drive pulse voltage is the same as in the first state, and a fourth state in which the optical sensor can collect light and the pulse width of the drive pulse voltage is the same as in the second state. The discharge probability is calculated based on the number of times the drive pulse voltage is applied by the applied voltage generation unit and the number of discharges detected by the discharge determination unit during the application of the drive pulse voltage. Discharge probability calculation unit and
As known sensitivity parameters of the optical sensor, the reference pulse width of the drive pulse voltage, the reference light receiving amount of the optical sensor, and the pulse width of the drive pulse voltage in a state where the light sensor can collect light are the reference pulse width. A storage unit configured to store in advance the discharge probability of a normal discharge when the light receiving amount of the optical sensor is the reference light receiving amount.
The sensitivity parameters stored in the storage unit, the discharge probability calculated by the discharge probability calculation unit in the first, second, third, and fourth states, and the first, second, and second states. It is configured to calculate the light receiving amount of the optical sensor in the third and fourth states where the optical sensor can collect light based on the pulse width of the drive pulse voltage in the third and fourth states. A photodetection system including a light receiving amount calculation unit. In the light detection system according to claim 3,
A photodetection system further comprising a light receiving amount determining unit configured to determine the presence or absence of the light source by comparing the light receiving amount calculated by the light receiving amount calculating unit with the light receiving amount threshold value. In the photodetection system according to claim 3 or 4.
The light receiving amount calculation unit sets the reference light receiving amount of the optical sensor to Q ₀ , the reference pulse width of the driving pulse voltage to T ₀ , the discharge probability of the normal discharge to P _aA , and the first state. The discharge probability calculated by the discharge probability calculation unit is ₁ P ^* , the discharge probability calculated by the discharge probability calculation unit in the second state is ₂ P ^* , and the discharge probability is 2 P * in the third state. The discharge probability calculated by the calculation unit is ₁ P, the discharge probability calculated by the discharge probability calculation unit _{in the fourth state is 2} P, and the optical sensor in the third and fourth states. When the amount of light received is Q,

A light detection system characterized in that the light receiving amount Q is calculated by the above method. In the photodetection system according to any one of claims 1 to 5.
A light-shielding means provided between the light source and the optical sensor,
A photodetection system further comprising a shutter control unit configured to open and close the light-shielding means to switch between a state in which the light sensor is shielded from light and a state in which the light sensor is capable of daylighting. The first step of periodically applying a drive pulse voltage to the electrodes of the optical sensor when the optical sensor for detecting the light emitted from the light source is in the first shaded state,
The second step of detecting the discharge current of the optical sensor in the first state, and
A third step of detecting the discharge of the optical sensor based on the discharge current in the first state, and
The discharge probability in the first state is calculated based on the number of times the drive pulse voltage is applied by the first step and the number of discharges detected in the third step while the drive pulse voltage is applied. The fourth step to do and
The fifth step of periodically applying the drive pulse voltage to the electrodes of the optical sensor when the optical sensor is shielded from light and the pulse width of the drive pulse voltage is different from the first state in the second state. ,
The sixth step of detecting the discharge current of the optical sensor in the second state, and
A seventh step of detecting the discharge of the optical sensor based on the discharge current in the second state, and
The discharge probability in the second state is calculated based on the number of times the drive pulse voltage is applied by the fifth step and the number of discharges detected in the seventh step while the drive pulse voltage is applied. Eighth step to do and
As known sensitivity parameters of the optical sensor, the reference pulse width of the drive pulse voltage and the discharge probability when the pulse width of the drive pulse voltage is the reference pulse width in a light-shielded state are stored in advance. With reference to the storage unit, the sensitivity parameters stored in the storage unit, the discharge probability calculated in the fourth and eighth steps, and the drive pulse voltage in the first and second states. The first due to noise components other than discharge due to the photoelectric effect of the optical sensor, which is generated depending on the pulse width of the drive pulse voltage and not depending on the amount of light received by the optical sensor based on the pulse width. The discharge probability of the non-regular discharge of the kind and the discharge probability of the non-normal discharge of the second kind due to the noise component generated independently of the pulse width of the drive pulse voltage and the received light amount of the optical sensor. A method for calculating the discharge probability of an optical detection system, which comprises a ninth step of calculating. The first step of periodically applying a drive pulse voltage to the electrodes of the optical sensor when the optical sensor for detecting the light emitted from the light source is in the first shaded state,
The second step of detecting the discharge current of the optical sensor in the first state, and
A third step of detecting the discharge of the optical sensor based on the discharge current in the first state, and
The discharge probability in the first state is calculated based on the number of times the drive pulse voltage is applied by the first step and the number of discharges detected in the third step while the drive pulse voltage is applied. The fourth step to do and
The fifth step of periodically applying the drive pulse voltage to the electrodes of the optical sensor when the optical sensor is shielded from light and the pulse width of the drive pulse voltage is different from the first state in the second state. ,
The sixth step of detecting the discharge current of the optical sensor in the second state, and
A seventh step of detecting the discharge of the optical sensor based on the discharge current in the second state, and
The discharge probability in the second state is calculated based on the number of times the drive pulse voltage is applied by the fifth step and the number of discharges detected in the seventh step while the drive pulse voltage is applied. Eighth step to do and
Ninth step of periodically applying the drive pulse voltage to the electrode of the optical sensor when the optical sensor is capable of collecting light and the pulse width of the drive pulse voltage is the same as the first state and the third state. When,
The tenth step of detecting the discharge current of the optical sensor in the third state, and
The eleventh step of detecting the discharge of the optical sensor based on the discharge current in the third state, and
The discharge probability in the third state is calculated based on the number of times the drive pulse voltage is applied in the ninth step and the number of discharges detected in the eleventh step while the drive pulse voltage is applied. The twelfth step to do and
The thirteenth step of periodically applying the drive pulse voltage to the electrode of the optical sensor when the optical sensor is capable of collecting light and the pulse width of the drive pulse voltage is the same as the second state in the fourth state. When,
The 14th step of detecting the discharge current of the optical sensor in the fourth state, and
A fifteenth step of detecting the discharge of the optical sensor based on the discharge current in the fourth state, and
The discharge probability in the fourth state is calculated based on the number of times the drive pulse voltage is applied in the thirteenth step and the number of discharges detected in the fifteenth step while the drive pulse voltage is applied. 16th step to do and
As known sensitivity parameters of the optical sensor, the reference pulse width of the drive pulse voltage, the reference light receiving amount of the optical sensor, and the pulse width of the drive pulse voltage in a state where the photosensor can collect light are the reference pulse width. With reference to a storage unit that previously stores the discharge probability of a normal discharge when the light reception amount of the optical sensor is the reference light reception amount, the sensitivity parameters stored in this storage unit and the first and second , The discharge probability calculated in the fourth, eighth, twelfth, and sixteenth steps in the third and fourth states, and the discharge probability in the first, second, third, and fourth states. Light including a seventeenth step of calculating the amount of light received by the optical sensor in the third and fourth states in which the optical sensor can collect light based on the pulse width of the drive pulse voltage. A method for measuring the amount of light received by a detection system. In the method for measuring the amount of received light of the photodetection system according to claim 8,
A method for measuring a light receiving amount of a photodetection system, further comprising an eighteenth step of determining the presence or absence of the light source by comparing the light receiving amount calculated in the seventeenth step with the light receiving amount threshold value.

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