Light detection system and method for calculating the number of photons

Abstract

To enable a comparison between another optical sensor and an electrical discharge level.SOLUTION: An optical detection system comprises: an electrical discharge probability calculation unit 202 for calculating electric discharge probabilities of an optical sensor 1 regarding a first state in which a light-receiving area of the optical sensor 1 is a first area and a second state in which the light-receiving area is a second area different from the first area; a sensitivity parameter storage unit 19 for preliminarily storing, as a known sensitivity parameter of the optical sensor 1, a reference value of the light-receiving area at the time of a factory shipment of the optical detection system and an electrical discharge probability when the light-receiving area is the reference value; and a photon number calculation unit 205 for calculating a ratio of the number of photons reaching a light-receiving surface of the optical sensor 1 at the time of the factory shipment of the optical detection system and after on-site installation of the optical detection system, on the basis of the sensitivity parameter, the first and second areas, and the electrical discharge probabilities calculated by the electrical discharge probability calculation unit 202 at the time of the first and second states.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an optical detection system for detecting light such as a flame. [Background technology]

[0002] Phototube type ultraviolet sensors are sometimes used as optical sensors to detect the presence or absence of flames based on ultraviolet rays emitted from the light of a flame in a combustion furnace, etc. It has been observed that phototube type ultraviolet sensors are subject to irregular discharge phenomena (pseudo discharges) caused by noise components other than discharges due to the photoelectric effect.

[0003] Patent Document 1 proposes a flame detection system that can calculate the amount of light received from discharge by controlling the pulse width of the drive pulse applied to the optical sensor, and can determine the lifespan of the optical sensor from the amount of light. However, the actual discharge of the optical sensor includes irregular discharges caused by noise, collectively known as malfunctions, and discharges can occur even when there is no light from a flame, resulting in false detection. In order to eliminate false detection of such discharges, it is necessary to consider the amount of light received from which the discharge probability of noise components has been removed.

[0004] Therefore, the flame detection system disclosed in Patent Document 2 proposes a method of calculating the amount of received light that takes into account the probability of irregular discharge of noise components, making it possible to accurately detect the presence or absence of a flame. Furthermore, in the failure detection device disclosed in Patent Document 3, it is proposed to detect failure due to self-discharge of the optical sensor by providing a shutter mechanism that blocks electromagnetic waves incident on the optical sensor.

[0005] The techniques disclosed in Patent Documents 1, 2, and 3 all calculate the amount of light received by the optical sensor. However, since the amount of light received was a relative value for the optical sensor itself, it was difficult to compare the degree of discharge with that of another optical sensor. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2018-84422 A [Patent Document 2] JP 2018-84423 A [Patent Document 3] Japanese Patent Application Publication No. 05-012581 Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention has been made to solve the above-mentioned problems, and has an object to provide a light detection system and a photon number calculation method that are capable of comparing the degree of discharge with that of a separate solid-state light sensor. [Means for solving the problem]

[0008] The light detection system of the present invention includes a light sensor configured to detect light emitted from a light source, an aperture mechanism provided between the light source and the light sensor and configured to be able to adjust the amount of light received by the light sensor, an applied voltage generation unit configured to periodically apply a drive pulse voltage to an electrode of the light sensor, a current detection unit configured to detect a discharge current of the light sensor, and a discharge determination unit configured to detect a discharge of the light sensor based on the discharge current detected by the current detection unit, and a number of times the drive pulse voltage is applied by the applied voltage generation unit for each of a first state in which a light receiving area of ​​the light sensor is a first area and a second state in which the light receiving area is a second area different from the first area. a discharge probability calculation unit configured to calculate a discharge probability based on the number of discharges detected by the discharge determination unit during application of the drive pulse voltage; a memory unit configured to pre-store a reference value of the light-receiving area at the time of shipment of the light detection system from a factory and a discharge probability when the light-receiving area is at the reference value as known sensitivity parameters of the light sensor; and a photon number calculation unit configured to calculate a ratio of the number of photons reaching the light-receiving surface of the light sensor between when the light detection system is shipped from the factory and after installation on site, based on the sensitivity parameters stored in the memory unit, the first and second areas, and the discharge probability calculated by the discharge probability calculation unit in the first and second states.

[0009] In one configuration example of the light detection system of the present invention, the photon number calculation unit calculates the reference value S re , the light receiving area is a reference value S re The discharge probability P re The ratio E / E of the number of photons is calculated based on the first and second areas S1 and S3, and the discharge probabilities P1 and P3 calculated by the discharge probability calculation unit in the first and second states. re The present invention is characterized in that it calculates:

[0010] a current detection unit configured to detect a discharge current of the optical sensor; a discharge determination unit configured to detect a discharge of the optical sensor based on the discharge current detected by the current detection unit; a discharge probability calculation unit configured to calculate a discharge probability based on the number of applications of the drive pulse voltage 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 for each of a first state in which a light receiving area of ​​the optical sensor is a first area and a second state in which the light receiving area is a second area different from the first area; and a memory unit configured to store in advance a reference value of the light-receiving area at the time of shipment, a discharge probability when the light-receiving area is the reference value, a reference pulse width of the drive pulse voltage, a discharge probability of a first type of irregular discharge caused by a noise component other than a discharge caused by a photoelectric effect of the light sensor, which occurs depending on the pulse width of the drive pulse voltage and independent of the amount of light received by the light sensor, and a discharge probability of a second type of irregular discharge caused by the noise component, which occurs independent of the pulse width of the drive pulse voltage and the amount of light received by the light sensor; and a photon number calculation unit configured to calculate a ratio of the number of photons reaching the light-receiving surface of the light sensor when the light detection system is shipped from a factory and after installation on site, based on the sensitivity parameters stored in the memory unit, the first and second areas, the discharge probability calculated by the discharge probability calculation unit in the first and second states, and the pulse width of the drive pulse voltage in the first and second states.

[0011] In one configuration example of the light detection system of the present invention, the photon number calculation unit calculates the reference value S re , the light receiving area is a reference value S re The discharge probability P re, the reference pulse width T0 of the driving pulse voltage, the discharge probability P aB , the discharge probability P of the second type of irregular discharge bB The ratio E / E of the number of photons is calculated based on the first and second areas S1 and S3, the discharge probabilities P1 and P3 calculated by the discharge probability calculation unit in the first and second states, and the pulse width T of the drive pulse voltage in the first and second states. re The present invention is characterized in that it calculates: Furthermore, one configuration example of the optical detection system of the present invention is characterized in that it further includes a light receiving area calculation unit configured to control the aperture mechanism to put the optical detection system in the first state, and further control the aperture mechanism to put the optical detection system in the second state. Furthermore, in one configuration example of the optical detection system of the present invention, when the optical detection system is shipped from the factory before being installed at the site, the discharge probability calculation unit calculates a discharge probability based on the number of applications of the drive pulse voltage 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, when the light receiving area is at the reference value, and stores the calculated discharge probability in the memory unit. Moreover, one configuration example of the optical detection system of the present invention is characterized in that it further includes a received light amount calculation unit configured to calculate an amount of light received by the optical sensor after the optical detection system is installed at the site, based on the ratio of the numbers of photons calculated by the photon number calculation unit.

[0012] Further, a photon number calculation method of the present invention includes a first step of periodically applying a drive pulse voltage to an electrode of the optical sensor when the amount of light received by the optical sensor that detects light emitted from a light source is limited by an aperture mechanism and the light receiving area of ​​the optical sensor is a first area, a second step of detecting a discharge current of the optical sensor in the first state, a third step of detecting a discharge of the optical sensor based on the discharge current in the first state, a fourth step of calculating a discharge probability in the first state based on the number of applications of the drive pulse voltage in the first step and the number of discharges detected in the third step during application of the drive pulse voltage, a fifth step of periodically applying a drive pulse voltage to the electrode of the optical sensor when the amount of light received by the optical sensor is limited by the aperture mechanism and the light receiving area is a second area different from the first area, and a sixth step of detecting a discharge current of the optical sensor when the optical sensor is in the second state; a seventh step of detecting a discharge of the optical sensor based on the discharge current in the second state; an eighth step of calculating a discharge probability in the second state based on the number of applications of the drive pulse voltage in the fifth step and the number of discharges detected in the seventh step during application of the drive pulse voltage; and a ninth step of referring to a storage unit that pre-stores a reference value of the light-receiving area at the time of shipment of the optical detection system from a factory and a discharge probability when the light-receiving area is the reference value as known sensitivity parameters of the optical sensor, and calculating a ratio of the number of photons reaching the light-receiving surface of the optical sensor when the optical detection system is shipped from a factory to that when the optical detection system is installed on site, based on the sensitivity parameters stored in the storage unit, the first and second areas, and the discharge probabilities calculated in the fourth and eighth steps when the optical sensor is in the first and second states.

[0013] Furthermore, the photon number calculation method of the present invention includes a first step of periodically applying a drive pulse voltage to an electrode of the optical sensor when the amount of light received by the optical sensor that detects light emitted from a light source is limited by an aperture mechanism and the light receiving area of ​​the optical sensor is a first area, a second step of detecting a discharge current of the optical sensor in the first state, a third step of detecting a discharge of the optical sensor based on the discharge current in the first state, a fourth step of calculating a discharge probability in the first state based on the number of applications of the drive pulse voltage in the first step and the number of discharges detected in the third step during application of this drive pulse voltage, a fifth step of periodically applying a drive pulse voltage to an electrode of the optical sensor when the amount of light received by the optical sensor is limited by the aperture mechanism and the light receiving area is a second area different from the first area, a sixth step of detecting a discharge current of the optical sensor in the second state, and detecting a discharge of the optical sensor based on the discharge current in the second state. a seventh step, an eighth step of calculating a discharge probability in the second state based on the number of applications of the drive pulse voltage in the fifth step and the number of discharges detected in the seventh step during application of the drive pulse voltage, and a reference value of the light receiving area at the time of shipment from the factory of the light detection system, a discharge probability when the light receiving area is at the reference value, a reference pulse width of the drive pulse voltage, and a discharge probability that occurs depending on the pulse width of the drive pulse voltage and that does not depend on the amount of light received by the light sensor, as known sensitivity parameters of the light sensor. a memory unit that stores in advance a discharge probability of a first type of irregular discharge caused by a noise component other than a discharge caused by a photoelectric effect of the optical sensor, and a discharge probability of a second type of irregular discharge caused by the noise component, which occurs independent of a pulse width of the drive pulse voltage and an amount of light received by the optical sensor, and based on the sensitivity parameters stored in the memory unit, the first and second areas, the discharge probability calculated in the fourth and eighth steps when in the first and second states, and the pulse width of the drive pulse voltage when in the first and second states,and a ninth step of calculating a ratio of the number of photons reaching the light receiving surface of the optical sensor when the optical detection system is shipped from a factory to the number of photons reaching the light receiving surface of the optical sensor after the optical detection system is installed on site.

[0014] Furthermore, one configuration example of the photon number calculation method of the present invention is characterized in that it further includes a 10th step of controlling the aperture mechanism to put the light detection system in the first state, and an 11th step of controlling the aperture mechanism to put the light detection system in the second state. Furthermore, one configuration example of the photon number calculation method of the present invention is characterized in that it further includes a twelfth step of periodically applying a drive pulse voltage to an electrode of the optical sensor when the amount of light received by the optical sensor is limited by the aperture mechanism and the light receiving area is at the reference value at the time of shipping from a factory prior to installation on site of the optical detection system, a thirteenth step of detecting a discharge current of the optical sensor, a fourteenth step of detecting a discharge of the optical sensor based on the discharge current, and a fifteenth step of calculating a discharge probability when the light receiving area of ​​the optical sensor is at the reference value based on the number of applications of the drive pulse voltage in the twelfth step and the number of discharges detected in the fourteenth step during the application of this drive pulse voltage, and storing the calculated discharge probability in the memory unit. Effect of the Invention

[0015] According to the present invention, the ratio of the number of photons at the time of shipment from the factory and after installation at the site can be calculated. In the present invention, the degree of discharge can be compared with that of a separate solid-state optical sensor by calculating the ratio of the number of photons. Since the amount of received light obtained by the conventional technology is affected by the variation of the optical sensor, there is a possibility that the life of the optical sensor will be erroneously determined if the life of the optical sensor is determined based on the amount of received light. On the other hand, in the present invention, the influence of the variation of the optical sensor can be eliminated by calculating the ratio of the number of photons, so that the possibility of erroneously determining the life of the optical sensor can be reduced if the life of the optical sensor is determined based on the ratio of the number of photons. In addition, in the present invention, by providing an aperture mechanism, the amount of received light can be suppressed when the light source light is strong, and deterioration of the optical sensor can be suppressed. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a diagram for explaining the ratio of the amount of received light when the light receiving area of ​​the electrode surface of the optical sensor is changed by the aperture mechanism. [Diagram 2] FIG. 2 is a block diagram showing the configuration of a light detection system according to a first embodiment of the present invention. [Diagram 3] FIG. 3 is a waveform diagram showing a drive pulse applied to the optical sensor and a detection voltage detected in the current detection circuit in the first embodiment of the present invention. [Figure 4] FIG. 4 is a diagram for explaining the ratio of the amount of received light when the light receiving area of ​​the electrode surface of the optical sensor is changed by the aperture mechanism. [Diagram 5] FIG. 5 is a flowchart explaining the operation of the light detection system according to the first embodiment of the present invention at the time of shipment from the factory. [Figure 6] FIG. 6 is a flowchart illustrating the operation of the light detection system according to the first embodiment of the present invention after installation at the site. [Figure 7] FIG. 7 is a block diagram showing an example of the configuration of a computer that realizes the light detection systems according to the first and second embodiments of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] [Principle of the invention] In the present invention, a light sensor with known sensitivity parameters and a mechanism for varying the amount of light received by the light sensor are provided, and the discharge probability when the light receiving area is varied for light of a wavelength to which the light sensor is sensitive is used to determine the number of photons relative to the number at the time of shipment from the factory of the light detection system. An example of varying the amount of light received is to provide a mechanism such as an iris diaphragm or a filter to adjust the amount of light received by the light sensor.

[0018] In the present invention, the ratio of the number of photons in the optical sensor is calculated. In the technology disclosed in Patent Document 1, the amount of light received by the optical sensor is calculated and the life of the optical sensor is determined from the amount of light received. However, since the amount of light received was a relative value of the optical sensor itself, it was difficult to compare the amount of light received with that of another solid-state optical sensor. In the present invention, the ratio of the number of photons in the optical sensor is calculated, making it possible to compare the degree of discharge of another solid-state optical sensor.

[0019] [First Example] Below, we will explain how to calculate the number of photons when the amount of light received by the optical sensor is variable. In the first embodiment of the present invention, we will explain an example in which only the normal discharge of the optical sensor is considered. An optical sensor that uses the photoelectric effect is a phototube that conducts electricity when photons hit the electrode. The current flows under the following conditions.

[0020] [Optical sensor operation] When a voltage is applied between a pair of electrodes in an optical sensor, if a photon hits one of the electrodes, there is a certain probability that a photoelectron will be emitted, causing an electron avalanche and causing electricity to flow (a discharge current flows between the electrodes). The optical sensor continues to conduct electricity while a voltage is applied between the electrodes. Alternatively, the conduction of electricity is stopped by immediately lowering the voltage once the conduction of electricity is confirmed. In this way, the optical sensor stops conducting electricity when the voltage between the electrodes is lowered.

[0021] Let P1 be the probability that the optical sensor discharges when one photon hits the optical sensor's electrode. Let P2 be the probability that the optical sensor discharges when two photons hit the optical sensor's electrode. Since P2 is the inverse of the probability that the optical sensor does not discharge when hit by either the first or second photon, the relationship between P2 and P1 is expressed as in equation (1).

[0022]

number

[0023] In general, the probability that a photosensor discharges when n photons hit its electrodes is P n, the probability that the light sensor discharges when m photons hit the electrodes of the light sensor is P m (n and m are natural numbers), then equations (2) and (3) hold, just like equation (1).

[0024]

number

[0025] From equations (2) and (3), P n and P m Equation (4) can be derived as the relationship.

[0026]

number

[0027] The area of ​​the photo sensor electrode S i The number of photons that hit the electrodes per unit area is E, and the time that a voltage higher than the discharge start voltage of the optical sensor is applied between the electrodes (hereafter referred to as the pulse width) is T. i Then, the number of photons that hit the electrode per voltage application is ES i T i Therefore, when the same optical sensor is operated under one condition A and another condition B, the number of photons E and the area S i , pulse width T i , discharge probability P i The relationship is as shown in equation (5). Here, the reference number of photons is defined as E0, the unit area as S0, and Q A =E A S A / (E0S0),Q B =E B S B / (E0S0), we get equation (6). Here, Q i is called the amount of received light.

[0028]

number

[0029] Consider a light detection system equipped with a mechanism that can proportionally change the light receiving area of ​​the electrode surface of the light sensor using an aperture mechanism or the like. As shown in Figures 1(A) and 1(B), the amount of light received by the light sensor 1 is limited by the aperture mechanism 21, and the light receiving area of ​​the electrode surface of the light sensor 1 is set to S a The amount of light received when a The light receiving area is S b The amount of light received when b The relationship is expressed as equation (7).

[0030]

number

[0031] [Configuration and operation of the optical detection system] 2 is a block diagram showing the configuration of a light detection system according to a first embodiment of the present invention. The light detection system drives a light sensor and calculates the ratio of the number of photons and the amount of received light from the drive result of the light sensor. This light detection system includes a light 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 source 2, a calculation device 3 to which the light sensor 1 and the external power source 2 are connected, and an aperture mechanism 21 provided between the light source 100 and the light sensor 1.

[0032] The optical sensor 1 is composed of a phototube having a cylindrical envelope with both ends closed, two electrode pins penetrating both ends of the envelope, and two electrodes supported parallel to each other by the electrode pins inside the envelope. In such an optical sensor 1, when a predetermined voltage is applied between the electrodes via the electrode support pins and ultraviolet light is irradiated onto one of the electrodes arranged opposite the light source 100, electrons are emitted from the electrode due to the photoelectric effect, and a discharge current flows between the electrodes.

[0033] The external power source 2 is, for example, an AC commercial power source having a voltage value of 100 [V] or 200 [V].

[0034] The arithmetic device 3 includes a power supply circuit 11 connected to an external power supply 2, an applied voltage generating circuit 12 and a trigger circuit 13 connected to the power supply circuit 11, a voltage dividing resistor 14 consisting of resistors R1 and R2 connected in series between the downstream terminal 1b of the optical sensor 1 and a ground line GND, a current detection circuit 15 that detects a voltage (reference voltage) Va generated at a connection point Pa between the resistors R1 and R2 of the voltage dividing resistor 14 as a current I flowing through the optical sensor 1, and a processing circuit 16 to which the applied voltage generating circuit 12, the trigger circuit 13, and the current detection circuit 15 are connected.

[0035] The power supply circuit 11 supplies AC power input from the external power supply 2 to the applied voltage generating circuit 12 and the trigger circuit 13. Furthermore, power for driving the arithmetic device 3 is obtained from the power supply circuit 11. However, it may also be configured so that the driving power is obtained from a separate power supply, regardless of whether it is AC or DC.

[0036] The applied voltage generating circuit 12 (applied voltage generating 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 pulse-shaped voltage of 200 [V] synchronized with the rectangular pulse PS from the processing circuit 16 (the discharge start voltage V of the optical sensor 1) is applied. ST The above voltages) are generated as drive pulse voltage PM, and this generated drive pulse voltage PM is applied to the optical sensor 1. Fig. 3 shows the drive pulse voltage PM applied to the optical sensor 1. The drive pulse voltage PM is synchronized with a 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.

[0037] 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 where the voltage value is minimum as the predetermined value point (trigger time point). By detecting the predetermined value point of the AC voltage in this way, it becomes possible to detect one cycle of the AC voltage.

[0038] The voltage dividing resistor 14 generates a reference voltage Va as a divided voltage between resistors R1 and R2, and inputs it to the current detection circuit 15. Here, since the voltage value of the drive pulse PM applied to the upstream terminal 1a of the optical sensor 1 is a high voltage of 200 [V] as described above, if the voltage generated at the downstream terminal 1b when a current flows between the electrodes of the optical sensor 1 is input directly to the current detection circuit 15, a large load will be placed on the current detection circuit 15. For this reason, in this embodiment, a reference voltage Va with a low voltage value is generated by the voltage dividing resistor 14, and this is input to the current detection circuit 15.

[0039] 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 to the processing circuit 16 as a detection voltage Vpv. The processing circuit 16 includes a rectangular pulse generating section 17, an A / D converting section 18, a sensitivity parameter storing section 19, and a central processing section 20.

[0040] The rectangular pulse generating unit 17 generates a rectangular pulse PS with a pulse width T every time the trigger circuit 13 detects a trigger time point, that is, every period of the AC voltage applied from the power supply circuit 11 to the trigger circuit 13. The rectangular pulse PS generated by the rectangular pulse generating unit 17 is sent to the applied voltage generating circuit 12. The rectangular pulse generating unit 17 and the applied voltage generating circuit 12 are capable of adjusting the pulse width of the driving pulse voltage PM. That is, the rectangular pulse generating unit 17 sets the pulse width of the rectangular pulse PS to a desired value, so that a driving pulse voltage PM with a pulse width equal to that of the rectangular pulse PS is output from the applied voltage generating circuit 12. The A / D conversion unit 18 A / D converts the detected voltage Vpv from the current detection circuit 15 and sends it to the central processing unit 20 .

[0041] The central processing unit 20 is realized by hardware consisting of a processor and a storage device, and a program that works in cooperation with this hardware to realize various functions, and functions as a discharge determination unit 201, a discharge probability calculation unit 202, a pulse application number accumulation unit 203, an application number determination unit 204, a photon number calculation unit 205, a received light amount calculation unit 206, a received light amount determination unit 207, and a light receiving area calculation unit 208.

[0042] 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 compares the detection voltage Vpv input from the A / D conversion unit 18 with a predetermined threshold voltage Vth (see FIG. 3) every time the drive pulse voltage PM is applied to the optical sensor 1 (every time the rectangular pulse PS is generated), and determines that the optical sensor 1 has discharged if the detection voltage Vpv exceeds the threshold voltage Vth, and increments the number of discharges n by 1.

[0043] When the number of applications N of the drive pulse voltage PM applied to the light sensor 1 exceeds a predetermined number (when the number of pulses of the rectangular pulse PS exceeds a predetermined number), the discharge probability calculation unit 202 calculates the discharge probability P of the light sensor 1 from the number of discharges n detected by the discharge determination unit 201 and the number of applications N of the drive pulse voltage PM.

[0044] This discharge probability P is output as a frame signal. It is assumed that the discharge probability P0 under certain operating conditions, the amount of received light Q0 (Q0 ≠ 0), and the pulse width T0 is known. For example, in shipping inspection of a light detection system, there is a method of measuring the discharge probability P at a set amount of received light and pulse width. In this case, the relationship between the amount of received light Q, the pulse width T, and the discharge probability P is given by equation (8). However, P=0 is treated as Q=0. In the present invention, the cases when P=0 and P=1 are excluded from the calculation process of the amount of received light Q.

[0045]

number

[0046] Now, Q0, T0, and P0 are known, and T is also known because it is the pulse width controlled by the light detection system. By applying the drive pulse voltage PM multiple times to the light sensor 1, measuring the number of discharges n, and calculating the discharge probability P, the unknown amount of received light Q can be calculated from equation (8).

[0047] From equation (8), the discharge probability P aA Assuming that is known, the relationship between the amount of received light Q, the pulse width T, and the discharge probability P is given by equation (9).

[0048]

number

[0049] [Calculation method for the number of photons when the light receiving area is variable] As shown in FIG. 4(A) to FIG. 4(C), the amount of light received by the optical sensor 1 is limited by the aperture mechanism 21, and the light receiving area of ​​the electrode surface of the optical sensor 1 is set to S i The discharge probability when (i=1~3) is P i , the amount of light received is Q i In addition, the number E of photons per unit area of ​​the electrode that reach the electrode of the optical sensor 1 in the state of Fig. 4(B) is unknown. Here, from equation (7), Q1 = (S1 / S2) Q2, Q3 = (S3 / S2) Q2 (S1 ≠ S3).

[0050] When the light receiving area of ​​the electrode surface of the optical sensor 1 is S1, the discharge probability P1 and the amount of light received Q1 are substituted into equation (9) to obtain equation (10), and when the light receiving area is S3, the discharge probability P3 and the amount of light received Q3 are substituted into equation (9) to obtain equation (11).

[0051]

number

[0052] Dividing equation (10) by (11) gives equation (12).

[0053]

number

[0054] In addition, the photon count E re , light receiving area S re , discharge probability P re When the amount of light received is Q re The calculation is performed for the light receiving area S re , discharge probability P re , amount of received light Q re is known (the number of photons E re is unknown). The discharge probability is P re , the amount of light received is Q re Equation (9) for the case is transformed to obtain equation (13).

[0055]

number

[0056] Substituting equation (13) into equation (12) and rearranging it gives equation (14).

[0057]

number

[0058] Substituting Q1 = (S1 / S2)Q2 and Q3 = (S3 / S2)Q2 into equation (14) gives equation (15).

[0059]

number

[0060] Q2=(ES2) / (E0S0),Q re =(E re S re ) / (E0S0) into equation (15), E / E re can be sought.

[0061]

number

[0062] Therefore, the known values ​​P1, P3, S1, and S3 of the optical detection system after installation in the field and the known value P re ,S re The ratio of the number of photons at the time of shipment from the factory to that after installation on the site is E / E re It becomes possible to calculate

[0063] The operation of the light detection system of this embodiment will be described in more detail below. Fig. 5 is a flow chart for explaining the operation of the light detection system of this embodiment at the time of shipment from the factory. For example, at the inspection stage before shipment from a factory, the opening of the diaphragm mechanism 21 is manually set to an arbitrary size so that the optical sensor 1 can receive light and the amount of light received by the optical sensor 1 is limited (step S100). Light from the light source 100 passes through the opening of the diaphragm mechanism 21 and enters the optical sensor 1.

[0064] The diaphragm mechanism 21 may be configured to include a drive mechanism such as a motor. In this case, the light-receiving area calculation unit 208 can control the size of the opening of the diaphragm mechanism 21.

[0065] The light receiving area calculation unit 208 includes a means for acquiring information on the size (diameter) of the opening of the diaphragm mechanism 21, and calculates the light receiving area S of the electrode surface of the optical sensor 1 from the size of the opening of the diaphragm mechanism 21. re (Step S101). The light receiving area calculation unit 208 calculates the light receiving area S based on the information on the size of the opening that is manually input. re The light receiving area calculation unit 208 may calculate the light receiving area S re The value (reference value) is stored in the sensitivity parameter storage unit 19.

[0066] 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 rectangular pulse generation unit 17 sets the pulse width of the rectangular pulse PS to a predetermined value T. With this pulse width setting, the applied voltage generation circuit 12 applies the drive pulse voltage PM with the pulse width T between the pair of terminals 1a, 1b of the optical sensor 1 (step S102). Note that the pulse width T may be the same as the reference pulse width T0.

[0067] The discharge determination unit 201 compares the detected voltage Vpv from the current detection circuit 15 with a predetermined threshold voltage Vth, and determines that the optical sensor 1 has discharged when the detected voltage Vpv exceeds the threshold voltage Vth. When the discharge determination unit 201 determines that the optical sensor 1 has discharged, it counts this as one discharge and counts the number of discharges n (step S103). The initial values ​​of the number of discharges n and the number of applications N of the drive pulse voltage PM are both 0. In this manner, the processes of steps S102 and S103 are repeatedly executed.

[0068] The pulse application number accumulator 203 counts the number of rectangular pulses PS output from the rectangular pulse generator 17, thereby counting the number of times N that the driving pulse voltage PM is applied. The application number determination unit 204 compares the number of times N that the driving pulse voltage PM is applied with a predetermined number Nth.

[0069] When the application number determination unit 204 determines that the number of applications N of the drive pulse voltage PM from the start of application of the drive pulse voltage PM with the pulse width T in step S102 has exceeded a predetermined number Nth (YES in step S104), the discharge probability calculation unit 202 calculates the discharge probability P re is calculated (step S105). P re = n / N (17)

[0070] The sensitivity parameter storage unit 19 stores, as known sensitivity parameters of the optical sensor 1, a reference light receiving amount Q0 of the optical sensor 1, a reference pulse width T0 of the drive pulse voltage PM, and a discharge probability P aA and the light receiving area S2 used in deriving the above formula are stored in advance.

[0071] The light receiving amount calculation unit 206 calculates the discharge probability P re If is greater than 0 and less than 1 (YES in step S106), the discharge probability P re and the discharge probability P re The pulse width T of the driving pulse voltage PM when the above is calculated, and the parameters Q0, T0, and P aA Based on this, the amount of light received Q is calculated as Q re In this calculation, P in formula (9) is converted to P re can be substituted.

[0072] In addition, the light receiving amount calculation unit 206 calculates the discharge probability P re If it is 0 or 1 (NO in step S106), the process returns to step S102. re The processes in steps S102 to S106 are repeated until the amount of received light Q becomes greater than 0 and less than 1. re The discharge probability calculation unit 202 ends the calculation when the discharge probability P re The value of is stored in the sensitivity parameter storage unit 19.

[0073] Next, the operation of the light detection system after installation at the site will be described with reference to Fig. 6. After the light detection system is installed at the site, the light receiving area calculation unit 208 initializes the light receiving area and the discharge probability number i to 1 (step S200). After the light detection system is installed at the site, the opening of the diaphragm mechanism 21 is manually set to an arbitrary size so that the light sensor 1 can collect light and the amount of light received by the light sensor 1 is limited (step S201). As described above, the light receiving area calculation unit 208 may control the size of the opening of the diaphragm mechanism 21.

[0074] The light receiving area calculation unit 208 calculates the light receiving area S of the electrode surface of the optical sensor 1 from the size of the opening of the diaphragm mechanism 21. i = S1 (first area) is calculated (step S202).

[0075] 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 rectangular pulse generation unit 17 sets the pulse width of the rectangular pulse PS to a predetermined value T. With this pulse width setting, the applied voltage generation circuit 12 applies the drive pulse voltage PM with the pulse width T between the pair of terminals 1a, 1b of the optical sensor 1 (step S203). Note that the pulse width T after installation on site may be a different value from the pulse width T at the time of shipment from the factory.

[0076] The discharge determination unit 201 determines that the optical sensor 1 has discharged when the detection voltage Vpv from the current detection circuit 15 exceeds the threshold voltage Vth in the same manner as described above, and i =n1 is incremented by 1 (step S204). The initial values ​​of the number of discharges n1 and the number of applications N1 of the driving pulse voltage PM are both 0. In this manner, the processes of steps S203 and S204 are repeatedly executed.

[0077] The discharge probability calculation unit 202 calculates the number of times N of application of the driving pulse voltage PM from the start of application of the driving pulse voltage PM with the pulse width T in step S203. i When the application number determination unit 204 determines that N1 exceeds the predetermined number Nth (YES in step S205), the application number N of the driving pulse voltage PM at this time is i= N1 and the number of discharges n detected by the discharge determination unit 201 i Based on this, the discharge probability P i =P1 is calculated (step S206). P1 = n1 / N1 (18)

[0078] If the calculated discharge probability P1 is 0 or 1 (NO in step S207), the discharge probability calculation unit 202 returns to step S201. In this manner, the processes in steps S201 to S207 are repeated until the discharge probability P1 becomes greater than 0 and less than 1.

[0079] If the calculated discharge probability P1 is greater than 0 and less than 1 (YES in step S207), the discharge probability calculation unit 202 increments the number i by 2 (step S208). If the number i is smaller than 5 (YES in step S209), the discharge probability calculation unit 202 returns to step S201.

[0080] When the discharge probability P1 is greater than 0 and less than 1, and the number i is less than 5, the opening of the diaphragm mechanism 21 is manually set to an arbitrary size so that the light sensor 1 can collect light and the amount of light received by the light sensor 1 is limited (step S201). At this time, the size is set to be different from the size of the opening when the discharge probability P1 was calculated immediately before. As described above, the light-receiving area calculation unit 208 may control the size of the opening of the diaphragm mechanism 21.

[0081] The light receiving area calculation unit 208 calculates the light receiving area S of the electrode surface of the optical sensor 1 from the size of the opening of the diaphragm mechanism 21. i = S3 (second area) is calculated (step S202). As is clear from the above explanation, S1 ≠ S3.

[0082] 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 rectangular pulse generation unit 17 temporarily stops outputting the rectangular pulse PS, and then sets the pulse width of the rectangular pulse PS to a predetermined value T. With this pulse width setting, the applied voltage generation circuit 12 applies the drive pulse voltage PM with the pulse width T between the pair of terminals 1a, 1b of the optical sensor 1 (step S203).

[0083] The discharge determination unit 201 determines that the optical sensor 1 has discharged when the detection voltage Vpv from the current detection circuit 15 exceeds the threshold voltage Vth in the same manner as described above, and i =n3 is incremented by 1 (step S204). The initial values ​​of the number of discharges n3 and the number of applications N3 of the driving pulse voltage PM are both 0. In this manner, the processes of steps S203 and S204 are repeatedly executed.

[0084] The discharge probability calculation unit 202 calculates the number of times N of application of the driving pulse voltage PM from the start of application of the driving pulse voltage PM with the pulse width T in step S203. i When the application number determination unit 204 determines that N3 exceeds the predetermined number Nth (YES in step S205), the application number N of the driving pulse voltage PM at this time is i = N3 and the number of discharges n detected by the discharge determination unit 201 i Based on this, the discharge probability P i =P3 is calculated (step S206). P3 = n3 / N3 (19)

[0085] If the calculated discharge probability P3 is 0 or 1 (NO in step S207), the discharge probability calculation unit 202 returns to step S201. In this manner, the processes in steps S201 to S207 are repeated until the discharge probability P3 becomes greater than 0 and less than 1.

[0086] If the calculated discharge probability P3 is greater than 0 and less than 1 (YES in step S207), the discharge probability calculation unit 202 increments the number i by 2 (step S208). When the number i reaches 5 (NO in step S209), the photon number calculation unit 205 calculates the discharge probabilities P1 and P3 calculated by the discharge probability calculation unit 202, the light-receiving areas S1 and S3 calculated by the light-receiving area calculation unit 208, and the discharge probability P re , light receiving area S re Based on this, the ratio of the number of photons at the time of shipment from the factory to the number of photons after installation in the field, E / E re is calculated (step S210).

[0087] The received light amount calculation unit 206 calculates the ratio E / E re and the light-receiving area S2 stored in the sensitivity parameter storage unit 19, the amount of received light Q is calculated by equation (20) (step S211). Q=(E / E re )S2···(20)

[0088] The light receiving area S2 is not used in the measurement after installation at the site, but is a value used in deriving the formula as described above. Either one of the light receiving areas S1 and S3 (S1 ≠ S3) may be the same as the light receiving area S2.

[0089] The light-receiving amount determination unit 207 compares the amount of light received Q calculated by the light-receiving amount calculation unit 206 with a predetermined light-receiving amount threshold Qth (step S212), and if the amount of light received Q exceeds the light-receiving amount threshold Qth (YES in step S212), it determines that there is a flame (step S213). If the amount of light received Q is equal to or less than the light-receiving amount threshold Qth (NO in step S212), the light-receiving amount determination unit 207 determines that there is no flame (step S214).

[0090] As described above, in this embodiment, the ratio E / E re In this embodiment, the ratio of the number of photons E / E reBy calculating the discharge degree, it is possible to compare the discharge degree with that of another solid-state optical sensor. In addition, in this embodiment, by providing the diaphragm mechanism 21, the amount of received light can be reduced when the light source light is strong, thereby suppressing deterioration of the electrode surface of the optical sensor 1.

[0091] [Second Example] Next, a second embodiment of the present invention will be described. In this embodiment, an example will be described in which irregular discharge phenomena (pseudo discharges) caused by noise components other than discharges caused by the photoelectric effect are also taken into consideration. In this embodiment, the configuration of the light detection system is the same as in the first embodiment, so the symbols in FIG. 2 will be used for the description.

[0092] [Operation of optical detection system taking noise into account] The relationship between the discharge of the optical sensor 1 and time can be considered in the following two ways. (a) Discharge that appears with a uniform probability during application of the driving pulse voltage PM (Equation (9)). (b) Discharge occurring at the rising or falling edge of the driving pulse voltage PM.

[0093] Next, the relationship between the discharge of the optical sensor 1 and the amount of received light can be considered in the following two cases. (A) Discharge that appears according to the relationship between the amount of light received and equation (9). (B) Discharge that appears regardless of the amount of light received.

[0094] [Table 1]

[0095] As shown in the matrix of Table 1, the noise discharge of the optical sensor 1 can be categorized by combinations of (a), (b) and (A), and (B). In the present invention, it is considered that the combination (aA) of (a) and (A), the combination (aB) of (a) and (B), the combination (bA) of (b) and (A), and the combination (bB) of (b) and (B) are likely to be reliably observed.

[0096] The discharge in combination aA is a normal discharge called "sensitivity" (already incorporated into equation (9)). The discharge in combination aB is a discharge that is unrelated to the amount of UV light triggered by thermoelectrons, etc. The discharge in combination bA is a discharge that occurs in a limited manner due to inrush current or residual ions when the drive pulse voltage rises or falls, and is dependent on the amount of light. The discharge in combination bB is a discharge that occurs in a limited manner due to inrush current or residual ions when the drive pulse voltage rises or falls, and is independent of the amount of light.

[0097] Note that the types listed in Table 1 do not cover all UV (ultraviolet) failure modes. For example, there are failure modes not included in Table 1, such as discharge not being cut off or different sensitivity wavelengths.

[0098] The above aA discharge and the three types of aB, bA, and bB noise discharges can be expressed in the form of equation (21).

[0099]

number

[0100] In formula (21), P aB is the amount of light received, Q, the discharge probability of aB at pulse width T, P bA is the amount of light received, Q, and the discharge probability of bA at pulse width T, P bB is the discharge probability of bB at the light intensity Q and pulse width T.

[0101] [Calculation method for the number of photons when the light receiving area is variable] In equation (21), the discharge probability P aB ,P bB As shown in FIG. 4(A) to FIG. 4(C), the amount of light received by the optical sensor 1 is limited by the aperture mechanism 21, and the light receiving area of ​​the electrode surface of the optical sensor 1 is set to S i The discharge probability when (i=1~3) is P i , the amount of light received is Q iIn addition, the number E of photons per unit area of ​​the electrode that reach the electrode of the optical sensor 1 is unknown. Here, from equation (7), it is assumed that Q1 = (S1 / S2) Q2, Q3 = (S3 / S2) Q2 (S1 ≠ S3).

[0102] When the light receiving area of ​​the electrode surface of the optical sensor 1 is S1, the discharge probability P1 and the amount of light received Q1 are substituted into equation (21) to obtain equation (22). When the light receiving area is S3, the discharge probability P3 and the amount of light received Q3 are substituted into equation (21) to obtain equation (23).

[0103]

number

[0104] Dividing equation (22) by (23) gives equation (24).

[0105]

number

[0106] In addition, the photon count E re , light receiving area S re , discharge probability P re When the amount of light received is Q re The calculation is performed for the light receiving area S re , discharge probability P re , amount of received light Q re is known (the number of photons E re is unknown). The discharge probability is P re , the amount of light received is Q re For equation (21) when aB ,P bB Since is known, we can rearrange it to obtain equation (25).

[0107]

number

[0108] Substituting equation (24) into equation (25) and rearranging it gives equation (26).

[0109]

number

[0110] Substituting Q1 = (S1 / S2)Q2 and Q3 = (S3 / S2)Q2 into equation (26) gives equation (27).

[0111]

number

[0112] Q2=(ES2) / (E0S0),Q re =(E re S re ) / (E0S0) into equation (27), we obtain E / E re can be sought.

[0113]

number

[0114] Therefore, the known values ​​P1, P3, S1, and S3 of the optical detection system after installation in the field and the known value P aB ,P bB ,T0,P re ,Q re The ratio of the number of photons at the time of shipment from the factory to that after installation on the site is E / E re It becomes possible to calculate

[0115] The operation of the light detection system of this embodiment will be described in more detail below. In this embodiment, the flow of the operation of the light detection system at the time of shipment from the factory is similar to that of the first embodiment, so the operation at the time of shipment from the factory will be described with reference to FIG. For example, at the inspection stage before shipping from the factory, the aperture of the diaphragm mechanism 21 is set to an arbitrary size manually or by control of the light-receiving area calculation unit 208, as in the first embodiment (step S100).

[0116] The light receiving area calculation unit 208 calculates the light receiving area S of the electrode surface of the optical sensor 1. re (Step S101). The light receiving area calculation unit 208 calculates the light receiving area S re The value of is stored in the sensitivity parameter storage unit 19. The applied voltage generating circuit 12 applies a driving pulse voltage PM having a pulse width T between the pair of terminals 1a, 1b of the optical sensor 1 (step S102).

[0117] The discharge determination unit 201 determines that the optical sensor 1 has discharged when the detected voltage Vpv from the current detection circuit 15 exceeds the threshold voltage Vth, and increments the number of discharges n by 1 (step S103).

[0118] When the number of times N of application of the driving pulse voltage PM from the start of application of the driving pulse voltage PM with the pulse width T in step S102 exceeds a predetermined number Nth (YES in step S104), the discharge probability calculation unit 202 calculates the discharge probability P re is calculated (step S105).

[0119] The light receiving amount calculation unit 206 calculates the discharge probability P re If is greater than 0 and less than 1 (YES in step S106), the discharge probability P re and the discharge probability P re The pulse width T of the driving pulse voltage PM when the above is calculated, and the parameters Q0, T0, and P aA Based on this, the amount of light received Q is calculated as Q re is calculated (step S107).

[0120] Discharge probability P re When is 0 or 1, the discharge probability P re The processes in steps S102 to S106 are repeated until the amount of received light Q becomes greater than 0 and less than 1. re The discharge probability calculation unit 202 ends the calculation when the discharge probability Pre The value of is stored in the sensitivity parameter storage unit 19.

[0121] Next, the operation of the light detection system after installation at the site will be described with reference to Fig. 6. After the light detection system is installed at the site, the light-receiving area calculation unit 208 initializes the number i to 1 (step S200). As in the first embodiment, the aperture of the diaphragm mechanism 21 is set to an arbitrary size manually or by control of the light-receiving area calculation unit 208 (step S201).

[0122] The light receiving area calculation unit 208 calculates the light receiving area S of the electrode surface of the optical sensor 1. i = S1 is calculated (step S202). The applied voltage generating circuit 12 applies a driving pulse voltage PM having a pulse width T between the pair of terminals 1a, 1b of the optical sensor 1 (step S203).

[0123] The discharge determination unit 201 determines that the optical sensor 1 has discharged when the detection voltage Vpv from the current detection circuit 15 exceeds the threshold voltage Vth, and i =Increase n1 by 1 (step S204).

[0124] The discharge probability calculation unit 202 calculates the number of times N of application of the driving pulse voltage PM from the start of application of the driving pulse voltage PM with the pulse width T in step S203. i When N1 exceeds the predetermined number Nth (YES in step S205), the number of times N i = N1 and the number of discharges n detected by the discharge determination unit 201 i Based on this, the discharge probability P i =P1 (step S206). If the calculated discharge probability P1 is greater than 0 and less than 1 (YES in step S207), the discharge probability calculation unit 202 increments the number i by 2 (step S208).

[0125] When the discharge probability P1 is greater than 0 and less than 1, and the number i is less than 5, the aperture of the diaphragm mechanism 21 is set to an arbitrary size manually or by control of the light-receiving area calculation unit 208, as in the first embodiment (step S201). At this time, the aperture is set to a size different from the size when the discharge probability P1 was calculated immediately before.

[0126] The light receiving area calculation unit 208 calculates the light receiving area S of the electrode surface of the optical sensor 1. i =S3 is calculated (step S202). The applied voltage generating circuit 12 applies a driving pulse voltage PM having a pulse width T between the pair of terminals 1a, 1b of the optical sensor 1 (step S203).

[0127] The discharge determination unit 201 determines that the optical sensor 1 has discharged when the detection voltage Vpv from the current detection circuit 15 exceeds the threshold voltage Vth, and i =Increase n3 by 1 (step S204).

[0128] The discharge probability calculation unit 202 calculates the number of times N of application of the driving pulse voltage PM from the start of application of the driving pulse voltage PM with the pulse width T in step S203. i When N3 exceeds the predetermined number Nth (YES in step S205), the number of times the driving pulse voltage PM is applied N i = N3 and the number of discharges n detected by the discharge determination unit 201 i Based on this, the discharge probability P i =P3 (step S206). If the calculated discharge probability P3 is greater than 0 and less than 1 (YES in step S207), the discharge probability calculation unit 202 increments the number i by 2 (step S208).

[0129] In the present embodiment, the sensitivity parameter storage unit 19 stores the discharge probability P re , light receiving area S re In addition, the known sensitivity parameters of the optical sensor 1 are the reference light receiving amount Q0 of the optical sensor 1, the reference pulse width T0 of the driving pulse voltage PM, the light receiving area S2 used in deriving the above formula, and the discharge probability PaB ,P bB are stored in advance.

[0130] Discharge probability P aB is the probability of discharge due to noise components other than discharge due to the photoelectric effect of the optical sensor 1, which occurs depending on the pulse width of the driving pulse voltage PM and does not depend on the amount of light received by the optical sensor 1 as described above. Discharge probability P bB is the probability of discharge due to noise components other than discharge due to the photoelectric effect of the optical sensor 1, which occurs independently of the pulse width of the driving pulse voltage PM and the amount of light received by the optical sensor 1 as described above.

[0131] When the number i reaches 5 (NO in step S209), the photon number calculation unit 205 of this embodiment calculates the discharge probabilities P1 and P3 calculated by the discharge probability calculation unit 202, the light receiving areas S1 and S3 calculated by the light receiving area calculation unit 208, the pulse width T of the drive pulse voltage PM when the discharge probabilities P1 and P3 were calculated, and the discharge probability P re and the light receiving area S re and the reference pulse width T0 and the discharge probability P of non-regular discharge aB ,P bB Based on this, the ratio of the number of photons at the time of shipment from the factory to the number of photons after installation in the field, E / E re is calculated (step S210).

[0132] The received light amount calculation unit 206 calculates the ratio E / E re and the light-receiving area S2 stored in the sensitivity parameter storage unit 19, the amount of received light Q is calculated by equation (20) (step S211).

[0133] The light-receiving amount determination unit 207 compares the amount of light Q calculated by the light-receiving amount calculation unit 206 with a light-receiving amount threshold Qth (step S212), and if the amount of light Q exceeds the light-receiving amount threshold Qth (YES in step S212), it determines that there is a flame (step S213). If the amount of light Q is equal to or less than the light-receiving amount threshold Qth (NO in step S212), the light-receiving amount determination unit 207 determines that there is no flame (step S214).

[0134] In this way, in this embodiment, the same effect as in the first embodiment can be obtained. In addition, in this embodiment, the ratio E / E of the number of photons excluding noise components other than the normal discharge of the optical sensor 1 is re can be calculated.

[0135] In the first and second embodiments, the light source 100 is a flame, but the light detection system of the present invention can also be applied to light sources 100 other than a flame.

[0136] The sensitivity parameter storage unit 19 and central processing unit 20 described in the first and second embodiments can be realized by a computer equipped with a CPU (Central Processing Unit), a storage device, and an interface, and a program that controls these hardware resources.

[0137] An example of the configuration of this computer is shown in Fig. 7. The computer includes a CPU 300, a storage device 301, and an interface device (I / F) 302. The I / F 302 is connected to the applied voltage generating circuit 12, the rectangular pulse generating unit 17, the A / D conversion unit 18, and the like. In such a computer, a program for implementing the photon number calculation method of the present invention is stored in the storage device 301. The CPU 300 executes the processes described in the first and second embodiments in accordance with the program stored in the storage device 301. [Industrial Applicability]

[0138] The present invention can be applied to a flame detection system, and also to the detection of light other than flames. [Explanation of symbols]

[0139] 1...optical sensor, 2...external power supply, 3...calculation 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 generation unit, 18...A / D conversion unit, 19...sensitivity parameter memory unit, 20...central processing unit, 21...aperture mechanism, 201...discharge determination unit, 202...discharge probability calculation unit, 203...pulse application number accumulation unit, 204...application number determination unit, 205...photon number calculation unit, 206...received light amount calculation unit, 207...received light amount determination unit, 208...light receiving area calculation unit.

Claims

1. a light sensor configured to detect light emitted from the light source; an aperture mechanism provided between the light source and the optical sensor and configured to be able to adjust the amount of light received by the optical sensor; an applied voltage generating unit configured to periodically apply a driving pulse voltage to an electrode of the optical sensor; a current detection unit configured to detect a discharge current of the optical sensor; a discharge determination unit configured to detect a discharge of the optical sensor based on the discharge current detected by the current detection unit; a discharge probability calculation unit configured to calculate a discharge probability based on the number of applications of the drive pulse voltage by the applied voltage generation unit and the number of discharges detected by the discharge determination unit during application of the drive pulse voltage, for each of a first state in which the light receiving area of ​​the optical sensor is a first area and a second state in which the light receiving area is a second area different from the first area; A storage unit configured to store in advance a reference value of the light receiving area at the time of shipment from a factory of the light detection system and a discharge probability when the light receiving area is the reference value as known sensitivity parameters of the light sensor; and a photon number calculation unit configured to calculate a ratio of the number of photons reaching the light receiving surface of the optical sensor when the optical detection system is shipped from a factory to after it is installed on site, based on the sensitivity parameters stored in the memory unit, the first and second areas, and the discharge probability calculated by the discharge probability calculation unit in the first and second states.

2. 2. The optical detection system of claim 1, The photon number calculation unit calculates the ratio of the number of photons at the time of shipment from the photodetection system to the number of photons after installation at the site as E / E re , the reference value of the light receiving area is S re , the light receiving area is a reference value S re The discharge probability at P re , the first and second areas are S 1 , S 3 The discharge probability calculated by the discharge probability calculation unit in the first and second states is P 1 , P 3 When [0010] Thus, the ratio of the number of photons E / E re The optical detection system according to claim 1,

3. a light sensor configured to detect light emitted from the light source; an aperture mechanism provided between the light source and the optical sensor and configured to be able to adjust the amount of light received by the optical sensor; an applied voltage generating unit configured to periodically apply a driving pulse voltage to an electrode of the optical sensor; a current detection unit configured to detect a discharge current of the optical sensor; a discharge determination unit configured to detect a discharge of the optical sensor based on the discharge current detected by the current detection unit; a discharge probability calculation unit configured to calculate a discharge probability based on the number of applications of the drive pulse voltage by the applied voltage generation unit and the number of discharges detected by the discharge determination unit during application of the drive pulse voltage, for each of a first state in which the light receiving area of ​​the optical sensor is a first area and a second state in which the light receiving area is a second area different from the first area; a storage unit configured to store in advance, as known sensitivity parameters of the optical sensor, a reference value of the light receiving area at the time of shipment from a factory of the optical detection system, a discharge probability when the light receiving area is the reference value, a reference pulse width of the drive pulse voltage, a discharge probability of a first type of irregular discharge caused by a noise component other than a discharge caused by a photoelectric effect of the optical sensor, which occurs depending on the pulse width of the drive pulse voltage and occurs independently of the amount of light received by the optical sensor, and a discharge probability of a second type of irregular discharge caused by the noise component, which occurs independently of the pulse width of the drive pulse voltage and the amount of light received by the optical sensor; and a photon number calculation unit configured to calculate a ratio of the number of photons reaching the light receiving surface of the optical sensor when the optical detection system is shipped from a factory to after installation on site, based on the sensitivity parameters stored in the memory unit, the first and second areas, the discharge probability calculated by the discharge probability calculation unit in the first and second states, and the pulse width of the drive pulse voltage in the first and second states.

4. 4. The optical detection system of claim 3, The photon number calculation unit calculates the ratio of the number of photons at the time of shipment from the photodetection system to the number of photons after installation at the site as E / E re , the reference value of the light receiving area is S re , the light receiving area is a reference value S re The discharge probability at P re , the reference pulse width of the driving pulse voltage is T 0 , the discharge probability of the first type of irregular discharge is P aB , the discharge probability of the second type of irregular discharge is P bB , the first and second areas are S 1 , S 3 The discharge probability calculated by the discharge probability calculation unit in the first and second states is P 1 , P 3 When the pulse width of the driving pulse voltage in the first and second states is T, [0025] Thus, the ratio of the number of photons E / E re The optical detection system according to claim 1,

5. 5. The optical detection system according to claim 1, a light receiving area calculation unit configured to control the aperture mechanism to put the light detection system in the first state, and to further control the aperture mechanism to put the light detection system in the second state.

6. 6. The optical detection system according to claim 1 , the discharge probability calculation unit calculates a discharge probability based on the number of applications of the drive pulse voltage 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 when the light receiving area is at the reference value at the time of shipment from the factory prior to installation on site of the light detection system, and stores the calculated discharge probability in the memory unit.

7. 7. The optical detection system according to claim 1, The optical detection system further comprises a light receiving amount calculation unit configured to calculate an amount of light received by the optical sensor after the optical detection system is installed at a site, based on the ratio of the number of photons calculated by the photon number calculation unit.

8. a first step of periodically applying a drive pulse voltage to an electrode of the optical sensor when the amount of light received by the optical sensor that detects light emitted from a light source is limited by an aperture mechanism and the light receiving area of ​​the optical sensor is a first area; a second step of detecting a discharge current of the optical sensor in the first state; a third step of detecting a discharge of the optical sensor based on the discharge current in the first state; a fourth step of calculating a discharge probability in the first state based on the number of times the driving pulse voltage is applied in the first step and the number of times the discharge is detected in the third step during application of the driving pulse voltage; a fifth step of periodically applying a drive pulse voltage to an electrode of the optical sensor when the amount of light received by the optical sensor is limited by the diaphragm mechanism and the light receiving area is a second area different from the first area in a second state; a sixth step of detecting a discharge current of the optical sensor in the second state; a seventh step of detecting a discharge of the optical sensor based on the discharge current in the second state; an eighth step of calculating a discharge probability in the second state based on the number of times the driving pulse voltage is applied in the fifth step and the number of times the discharge is detected in the seventh step during application of the driving pulse voltage; a ninth step of referring to a memory unit that pre-stores, as known sensitivity parameters of the optical sensor, a reference value of the light-receiving area at the time of shipment of the optical detection system from a factory and a discharge probability when the light-receiving area is at the reference value, and calculating a ratio of the number of photons reaching the light-receiving surface of the optical sensor when the optical detection system is shipped from a factory to the number of photons reaching the light-receiving surface of the optical sensor after installation on site, based on the sensitivity parameters stored in this memory unit, the first and second areas, and the discharge probabilities calculated in the fourth and eighth steps in the first and second states.

9. a first step of periodically applying a drive pulse voltage to an electrode of the optical sensor when the amount of light received by the optical sensor that detects light emitted from a light source is limited by an aperture mechanism and the light receiving area of ​​the optical sensor is a first area; a second step of detecting a discharge current of the optical sensor in the first state; a third step of detecting a discharge of the optical sensor based on the discharge current in the first state; a fourth step of calculating a discharge probability in the first state based on the number of times the driving pulse voltage is applied in the first step and the number of times the discharge is detected in the third step during application of the driving pulse voltage; a fifth step of periodically applying a drive pulse voltage to an electrode of the optical sensor when the amount of light received by the optical sensor is limited by the diaphragm mechanism and the light receiving area is a second area different from the first area in a second state; a sixth step of detecting a discharge current of the optical sensor in the second state; a seventh step of detecting a discharge of the optical sensor based on the discharge current in the second state; an eighth step of calculating a discharge probability in the second state based on the number of times the driving pulse voltage is applied in the fifth step and the number of times the discharge is detected in the seventh step during application of the driving pulse voltage; a ninth step of referring to a storage unit that pre-stores, as known sensitivity parameters of the optical sensor, a reference value of the light-receiving area at the time of shipment of the optical detection system from a factory, a discharge probability when the light-receiving area is the reference value, a reference pulse width of the drive pulse voltage, a discharge probability of a first type of irregular discharge caused by a noise component other than a discharge caused by the photoelectric effect of the optical sensor that occurs depending on the pulse width of the drive pulse voltage and independent of the amount of light received by the optical sensor, and a discharge probability of a second type of irregular discharge caused by the noise component that occurs independent of the pulse width of the drive pulse voltage and the amount of light received by the optical sensor, and calculating a ratio of the number of photons reaching the light-receiving surface of the optical sensor between when the optical detection system was shipped from a factory and after installation on site, based on the sensitivity parameters stored in the storage unit, the first and second areas, the discharge probability calculated in the fourth and eighth steps when the optical sensor is in the first and second states, and the pulse width of the drive pulse voltage when the optical sensor is in the first and second states.

10. 10. The photon number calculation method according to claim 8, a tenth step of controlling the diaphragm mechanism to set the light detection system in the first state; and an eleventh step of controlling the aperture mechanism to set the light detection system in the second state.

11. The photon number calculation method according to any one of claims 8 to 10, a twelfth step of periodically applying a driving pulse voltage to an electrode of the optical sensor when the amount of light received by the optical sensor is limited by the diaphragm mechanism and the light receiving area is at the reference value at the time of shipment from a factory prior to installation at a site of the optical detection system; a thirteenth step of detecting a discharge current of the optical sensor; a fourteenth step of detecting a discharge of the optical sensor based on the discharge current; a fifteenth step of calculating a discharge probability when the light receiving area of ​​the optical sensor is the reference value based on the number of applications of the drive pulse voltage in the twelfth step and the number of discharges detected in the fourteenth step during the application of this drive pulse voltage, and storing the calculated discharge probability in the memory unit.

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