Ozone generation device

Abstract

The control device has a storage unit that stores two or more functions representing the relationship between the power output and the ozone concentration corresponding to the power output according to different gas flow rates in the ozone generation unit. The control device calculates a first power output corresponding to the set ozone concentration and a second power output corresponding to the detected ozone concentration based on the set ozone concentration of the ozone generation unit, an index indicating the gas flow rate of the ozone generation unit, the detected ozone concentration, and the plurality of functions, and performs feedback control of the power output based on the difference between the first power output and the second power output.

Description

Technical Field

[0001] The present invention relates to an ozone generation device. Background Art

[0002] Ozone generation devices that generate ozone gas are widely used in semiconductor manufacturing processes and the like. In the ozone generation device of Patent Document 1, it is described that the power output of the ozone generation device is controlled by feedback control.

[0003] Patent Document 1: Japanese Patent Gazette No. 4085043 Summary of the Invention

[0004] -Technical Problem to be Solved by the Invention-

[0005] In the feedback control described in Patent Document 1, the set ozone concentration and the detected ozone concentration are compared, and the power output of the ozone generation device is increased or decreased so that the detected ozone concentration approaches the set ozone concentration. However, without fully considering the gas flow rate flowing through the ozone generation unit, the power output may sometimes not be adjusted to the optimum by feedback control.

[0006] Specifically, under conditions where the gas flow rate is relatively small, the ozone concentration changes significantly with respect to changes in the power output. Therefore, under such conditions, the ozone concentration easily fluctuates with the adjustment of the power output. Under conditions where the gas flow rate is relatively large, the ozone concentration does not change much with respect to changes in the power output. Therefore, under such conditions, the adjustment amount of the power output is insufficient, and the ozone concentration does not easily approach the set ozone concentration. Therefore, in the conventional feedback control, the ozone concentration cannot be quickly converged to the set ozone concentration.

[0007] The present disclosure has been completed in view of such problems, and an object thereof is to provide an ozone generation device that can quickly converge the ozone concentration to the set ozone concentration regardless of changes in the gas flow rate by feedback control.

[0008] -Technical Solution for Solving the Technical Problem-

[0009] To solve the above problems, in the ozone generation device of the present invention, feedback control is performed. In the feedback control, based on the set ozone concentration of the ozone generation unit, an index indicating the gas flow rate of the ozone generation unit, the detected ozone concentration, and a plurality of functions, a first power output corresponding to the set ozone concentration and a second power output corresponding to the detected ozone concentration are obtained, and the power output is controlled based on the difference between the first power output and the second power output.

[0010] In this way, even if the gas flow rate of the ozone generation unit changes, the optimal adjustment amount of the power output corresponding to the gas flow rate can be obtained according to multiple functions. Therefore, it is possible to quickly converge the detected ozone concentration to the set ozone concentration.

[0011] Preferably, the storage unit stores three or more functions corresponding to gas flow rates that are not equal to each other.

[0012] By using three or more functions corresponding to the gas flow rate, it is possible to track even finer changes in the gas flow rate. In this way, a more appropriate adjustment amount of the power output can be obtained.

[0013] Preferably, the multiple functions are functions formed by linearly connecting multiple points representing the power output and the ozone concentration corresponding to the power output.

[0014] In this way, simplification of the function can be achieved, and the computational processing load required for creating the function can be reduced.

[0015] If at least one of the first condition and the second condition is satisfied, the control device performs feedforward control, in which the power output is controlled to make the power output close to the first power output. The first condition is a condition that an index representing the gas flow rate changes by a specified value or more, and the second condition is a condition that the set ozone concentration changes by a specified value or more.

[0016] If the first condition or the second condition is satisfied, the difference between the detected ozone concentration and the set ozone concentration becomes large, and in the above feedback control, it may be difficult for the detected ozone concentration to converge to the set ozone concentration. If at least one of the first condition and the second condition is satisfied, by making the power output close to the first power output corresponding to the set ozone concentration, it is possible to quickly make the detected ozone concentration close to the set ozone concentration.

[0017] Preferably, the control device performs an automatic acquisition operation, in which multiple functions are automatically acquired by detecting the detected ozone concentration while changing the gas flow rate.

[0018] Through this automatic acquisition operation, after installing the ozone generation device on site, it is possible to automatically create multiple functions.

[0019] - Effects of the Invention -

[0020] According to the present invention, it is possible to provide an ozone generation device capable of quickly converging the ozone concentration through feedback control. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a schematic overall configuration diagram of an ozone generation system to which the ozone generation device according to the embodiment is applied;

[0022] Figure 2 is a curve graph showing the characteristics of multiple functions stored in a storage unit;

[0023] Figure 3 is the equivalent of adding multiple newly created functions Figure 2 of the curve graph;

[0024] Figure 4 is a basic flowchart of the operation of an ozone generation device;

[0025] Figure 5 is a flowchart of feedforward control;

[0026] Figure 6 is a flowchart of feedback control;

[0027] Figure 7 is the equivalent of the modification example Figure 1 of the graph. DETAILED DESCRIPTION

[0028] Hereinafter, embodiments of the present invention will be described in detail based on the accompanying drawings. It should be noted that the following embodiments are merely examples that are preferably essential in nature, and are not intended to limit the present invention, the application object of the present invention, or the scope of use of the present invention.

[0029] "Embodiments of the Invention"

[0030] The ozone generation device 20 of the present embodiment is assembled in an ozone gas generation system S. The ozone gas generation system S is applicable to, for example, semiconductor manufacturing equipment. The ozone gas generation system S has a first flow path 11 and a second flow path 12. The first flow path 11 is provided on the upstream side of the ozone generation unit 22. The second flow path 12 is provided on the downstream side of the ozone generation unit 22.

[0031] The first flow path 11 is a flow path through which a raw material gas flows. A raw material gas containing oxygen is supplied to the first flow path 11. As the raw material gas, high-purity oxygen (99.9% or more) is used. The raw material gas may also be concentrated oxygen generated by an oxygen generation device such as a PSA (pressure swing adsorption) type. The raw material gas may also be air.

[0032] The second flow path 12 is a flow path through which the ozone gas generated by the ozone generation unit 22 flows. The ozone gas is supplied to a specified object via the second flow path 12. A pressure regulating valve 13 is provided on the second flow path 12.

[0033] 〈Ozone Generation Device〉

[0034] The ozone generation device 20 generates ozone gas. The ozone generation device 20 includes: a power supply unit 21, an ozone generation unit 22, a flow rate detection unit 23, a concentration detection unit 24, a pressure detection unit 25, and a control device 30.

[0035] The power supply unit 21 is composed of a high-frequency high-voltage power supply. The power supply unit 21 supplies the high-voltage power output to the ozone generation unit 22.

[0036] The ozone generation unit 22 generates ozone by discharging. The ozone generation unit 22 adopts a silent discharge method. The raw material gas in the first flow path 11 is supplied to the ozone generation unit 22. When power is supplied from the power supply unit 21 to the discharge unit, discharging occurs between at least a pair of electrode units. Along with this discharging, a part of the raw material gas is converted into ozone. The ozone generated by the ozone generation unit 22 is supplied to a specified object via the second flow path 12.

[0037] The flow rate detection unit 23 detects the flow rate of the raw material gas flowing in the first flow path 11 as the detected gas flow rate. The detected gas flow rate is an index indicating the gas flow rate flowing in the ozone generation unit 22.

[0038] The concentration detection unit 24 detects the ozone concentration in the ozone gas flowing in the second flow path 12 as the detected ozone concentration Cd.

[0039] The pressure detection unit 25 detects the pressure of the second flow path 12 as the detected pressure.

[0040] The control device 30 includes a microcomputer and a storage device. The storage device stores software for operating the microcomputer.

[0041] The detected gas flow rate, the detected ozone concentration Cd, and the detected pressure are input to the control device 30.

[0042] The control device 30 has a setting unit 31, an arithmetic unit 32, a storage unit 33, and an output control unit 34.

[0043] In the setting unit 31, the target value of the ozone concentration in the ozone gas supplied to the object is set as the set ozone concentration Cs. Data for creating a plurality of functions is input to the setting unit 31, and the details of the plurality of functions will be described later.

[0044] The arithmetic unit 32 creates two or more functions representing the relationship between the power output and the ozone concentration corresponding to the power output according to different gas flow rates in the ozone generation unit. Here, the "ozone concentration corresponding to the power output" means the ozone concentration of the ozone gas generated in the ozone generation unit corresponding to the power output when the ozone generation unit operates with a specified power output.

[0045] The storage unit 33 includes, for example, an HDD (Hard Disk Drive), a RAM (Random Access Memory), a ROM (Read Only Memory), an SSD (Solid State Drive), etc. A plurality of functions created by the arithmetic unit 32 are stored in the storage unit 33.

[0046] The output control unit 34 controls the power output (discharge output) of the power supply unit 21. If the power output changes, the amount of ozone generated by the ozone generation unit 22 also changes. Along with this, the ozone concentration in the ozone gas supplied to the object changes.

[0047] The output control unit 34 performs feedback control on the power output. In addition, if at least one of the first condition and the second condition is satisfied, the output control unit 34 performs feedforward control on the power output. The above-mentioned first condition and second condition will be described in detail below. The output control unit 34 performs feedback control and feedforward control based on a plurality of functions stored in the storage unit 33.

[0048] 〈Regarding a plurality of functions〉

[0049] As Figure 2 shown, a plurality of functions are stored in the storage unit 33. These functions are created by the arithmetic unit 32. In the present embodiment, the arithmetic unit 32 creates a plurality of functions according to the data input by a person (user, installer, warranty personnel, etc.) to the setting unit 31.

[0050] The plurality of functions are information representing the relationship between the power output of the power supply unit 21 and the ozone concentration corresponding to the power output. These functions are determined according to the gas flow rate. These functions have the characteristic that the ozone concentration increases as the power output increases. In addition, these functions have the characteristic that the slope decreases as the power output increases. The slope of these functions has a tendency to increase as the gas flow rate decreases.

[0051] In the present embodiment, three functions are stored in the storage unit 33. These three functions are composed of a first function R1, a second function R2, and a third function R3.

[0052] The first function R1 corresponds to the maximum gas flow rate of the ozone generation unit 22. The first function R1 in this example corresponds to a gas flow rate of 50 L / min. The third function R3 corresponds to the minimum gas flow rate. The third function in this example corresponds to a gas flow rate of 10 L / min. The second function R2 corresponds to the intermediate gas flow rate between the maximum gas flow rate and the minimum gas flow rate. The second function R2 in this example corresponds to a gas flow rate of 30 L / min.

[0053] The maximum gas flow rate, the minimum gas flow rate, and the intermediate gas flow rate are preferably the gas flow rates with a high frequency of flow in the ozone generation unit 22 during the actual operation of the ozone generation device 20. The maximum gas flow rate is preferably the highest gas flow rate that can be supplied to the ozone generation unit 22. The minimum gas flow rate is preferably the lowest gas flow rate that can be supplied to the ozone generation unit 22 or a gas flow rate below it.

[0054] Three functions are determined based on the ozone concentration generation point, the maximum point, the first intermediate point, and the second intermediate point. The ozone concentration generation point is the point representing the minimum power output required to generate ozone in the ozone generation unit 22 and the ozone concentration corresponding to this power output. The ozone concentration generation point is determined by the structure and method of the power supply unit 21, etc., and it does not change significantly according to the gas flow rate. Therefore, the ozone concentration generation point can also be set to the same value regardless of the gas flow rate. The power output of the ozone concentration generation point in this example is 20%.

[0055] The maximum point is the point representing the maximum power output of the power supply unit 21 and the ozone concentration corresponding to this power output. The power output of the maximum point is 100%. The first intermediate point and the second intermediate point are the points corresponding to the specified power output between the ozone concentration generation point and the maximum point. In this example, the power output of the first intermediate point is 50%, and the power output of the second intermediate point is 70%.

[0056] A person sets the ozone concentration generation point, the maximum point, the first intermediate point, and the second intermediate point for each of the multiple gas flow rates in the control device 30. These points are determined based on the measured values obtained according to the gas flow rate after the ozone generation device 20 is installed on the equipment.

[0057] Based on these points, the arithmetic unit 32 creates multiple functions for each of the multiple gas flow rates. Specifically, the arithmetic unit 32 creates a function close to a curve by connecting the respective points of the maximum gas flow rate, the minimum gas flow rate, and the intermediate gas flow rate with a straight line.

[0058] In Figure 2 , the dotted lines k, l, m are the graphs of the relationship between the power output corresponding to the gas flow rate and the ozone concentration obtained through experiments. k, l, m change the power output at a finer interval than the three functions to more accurately determine the relationship between the power output and the ozone concentration. k corresponds to a gas flow rate of 50 L / min, l corresponds to a gas flow rate of 30 L / min, and m corresponds to a gas flow rate of 10 L / min. From Figure 2 it can be seen that the three functions obtained by the arithmetic unit 32 are roughly consistent with the respective curves k, l, m. Therefore, it can be known that the relationship between the ozone concentration corresponding to the gas flow rate and the power output can be accurately determined through the three functions.

[0059] -Operation action-

[0060] Refer to Figures 3 to 6 The operation action of the ozone generation device 20 will be described in detail.

[0061] Before the ozone generation device 20 of the present embodiment operates, the three functions obtained as described above are stored in the storage unit 33.

[0062] As Figure 4 As shown, if the ozone generation device 20 starts to operate (Yes in step ST1), the process proceeds to step ST2 and feedforward control is executed.

[0063] As Figure 5 As shown, in step ST11 of the feedforward control, the arithmetic unit 32 determines or creates a function corresponding to the gas flow rate.

[0064] For example, when the detected gas flow rate is 10 L / min, the third function R3 created in advance is directly used. For example, when the detected gas flow rate does not correspond to the flow rate of the function created in advance, a new function is created.

[0065] The ozone concentration generation point, the maximum point, the first intermediate point, and the second intermediate point change proportionally according to the gas flow rate. Therefore, for example, when the gas flow rate is 20 L / min, as Figure 3 As shown, each point of the newly created function is determined as the intermediate position (half position) of each point of the second function R2 and the third function R3. The arithmetic unit 32 creates a new function based on the ozone concentration generation point, the maximum point, the first intermediate point, and the second intermediate point corresponding to the gas flow rate of 20 L / min ( Figure 3 The fourth function R4 shown). The fourth function R4 is created by linearly connecting these points.

[0066] For example, when the gas flow rate is 40 L / min, as Figure 3 As shown, each point of the newly created function is determined as the intermediate position (half position) of each point of the first function R1 and the second function R2. The arithmetic unit 32 creates a new function based on the ozone concentration generation point, the maximum point, the first intermediate point, and the second intermediate point corresponding to the gas flow rate of 40 L / min ( Figure 3 The fifth function R5 shown). The fifth function R5 is created by linearly connecting these points.

[0067] In step ST12, the arithmetic unit 32 determines the target value of the power supply output based on the function corresponding to the current detected gas flow rate. Specifically, the arithmetic unit 32 uses the power supply output corresponding to the set ozone concentration Cs in the function corresponding to the current detected gas flow rate as the target value. In Figure 3In the example, the target value Po of the power supply output corresponding to the set ozone concentration Cs in the fourth function R4 is illustrated when the current detected gas flow rate is 20 L / min.

[0068] In step ST13, the output control unit 34 controls the power supply unit 21 so that the actual power supply output of the power supply unit 21 reaches the target value obtained in step ST12.

[0069] As Figure 6 shown, the feedforward control is repeatedly executed in step ST3 until a specified time has elapsed. It should be noted that in the case of repeatedly executing the feedforward control, the power supply output can also be increased step by step so that the actual power supply output of the power supply unit 21 finally reaches the above target value Po.

[0070] By executing the feedforward control when the ozone generation device 20 starts to operate, the ozone concentration in the ozone gas supplied to the object can quickly approach the set ozone concentration Cs.

[0071] After a specified time has elapsed in step ST3, it transfers to step ST4 and executes the feedback control.

[0072] As Figure 5 shown, in step ST21, for example, when the detected gas flow rate is 10 L / min, the third function R3 created in advance is directly used. For example, when the detected gas flow rate does not correspond to the flow rate of the function created in advance, a new function is created. The method of creating the new function is the same as the above feedforward control. That is, the arithmetic unit 32 determines the ozone concentration generation point, the maximum point, the first intermediate point, and the second intermediate point by proportional distribution corresponding to the flow rate according to the existing three functions. The arithmetic unit 32 creates a new function by linearly connecting these points.

[0073] In step ST22, the arithmetic unit 32 obtains the first power supply output P1 corresponding to the set ozone concentration Cs and the second power supply output P2 corresponding to the detected ozone concentration according to the function corresponding to the current detected gas flow rate. In Figure 3 it, the first power supply output P1 corresponding to the set ozone concentration Cs and the second power supply output P2 corresponding to the detected ozone concentration Cd are illustrated when the gas flow rate is 40 L / min.

[0074] Next, in step ST23, the arithmetic unit 32 calculates the difference ΔP (= P1 - P2) between the first power supply output P1 and the second power supply output P2. Next, the arithmetic unit 32 uses the value obtained by adding ΔP to the current power supply output Pc as the target value of the power supply output. ΔP is the adjustment amount of the power supply output.

[0075] In this way, when the first power output P1 is greater than the second power output P2, the power output increases. When the first power output P1 is less than the second power output P2, the power output decreases.

[0076] In step ST24, the output control unit 34 controls the power supply unit 21 so that the actual power output of the power supply unit 21 reaches the target value obtained in step ST23.

[0077] In the feedback control as described above, the difference ΔP in power output is obtained according to a function corresponding to the gas flow rate of the ozone generation unit 22, and the target value of the power output is determined based on this difference ΔP. Therefore, it is possible to optimally control the power output while fully considering the characteristics of the ozone concentration and the power output corresponding to the gas flow rate.

[0078] As Figure 4 shown, after the feedback control, when the condition of step ST5 is not satisfied, the feedback control of step ST4 is repeatedly executed via step ST1. Here, it is preferable to determine the interval ΔTb for executing the feedback control in consideration of the time (replacement time ΔTr) for replacing the gas in the pipe from the ozone generation unit 22 to the concentration detection unit 24. Specifically, in the setting unit 31 of the control device 30, the volume V in the pipe can be set as a parameter. The replacement time ΔTr can be calculated based on the volume V in the pipe and the detected gas flow rate. The interval ΔTb for executing the feedback control is preferably at least equal to or greater than the replacement time ΔTr.

[0079] In addition to this, in addition to the volume V in the pipe and the detected gas flow rate, the replacement time ΔTr can also be calculated based on the above-mentioned detected pressure.

[0080] In addition to this, the interval ΔTb for the feedback control can also be determined in consideration of the time delay from when the output voltage is changed until the detected ozone concentration Cd changes, the diffusion of ozone, and other effects. Considering such effects, the interval ΔTb is preferably set to the time obtained by multiplying the replacement time ΔTr by a predetermined coefficient α. Here, the coefficient α is greater than 1 and is preferably set to about 2 to 3.

[0081] After the feedback control in step ST4, when the condition of step ST5 is satisfied, the process proceeds to step ST2, and the feedforward control is executed again. In step ST5, it is determined whether a condition indicating a significant change in the operating conditions is satisfied. Specifically, this condition includes the following first condition and second condition.

[0082] The first condition is an index indicating the gas flow rate, that is, a condition for detecting a change in the gas flow rate exceeding a specified value. The second condition is a condition for setting a change in the ozone concentration Cs exceeding a specified value. In step ST5, if at least one of the first condition and the second condition is satisfied, the process proceeds to step ST4 to perform feedforward control.

[0083] If the gas flow rate flowing through the ozone generation unit 22 changes significantly, in the feedback control, the difference between the detected ozone concentration Cd and the set ozone concentration Cs becomes large, and it may not be possible to quickly bring the detected ozone concentration Cd close to the set ozone concentration Cs. In contrast, when the first condition is satisfied, by performing the above-mentioned feedforward control, the detected ozone concentration Cd can be quickly brought close to the set ozone concentration Cs.

[0084] If the set ozone concentration Cs changes significantly, in the feedback control, the difference between the detected ozone concentration Cd and the set ozone concentration Cs becomes large, and it may not be possible to quickly bring the detected ozone concentration Cd close to the set ozone concentration Cs. In contrast, when the second condition is satisfied, by performing the above-mentioned feedforward control, the detected ozone concentration Cd can be quickly brought close to the set ozone concentration Cs.

[0085] It should be noted that in step ST5, it is possible to determine only that the first condition is satisfied, or only that the second condition is satisfied.

[0086] - Effects of the Embodiment -

[0087] In the feedback control according to the above embodiment, the control device 30 calculates a first power output P1 corresponding to the set ozone concentration Cs and a second power output P2 corresponding to the detected ozone concentration Cd based on the set ozone concentration Cs of the ozone generation unit 22, an index indicating the gas flow rate of the ozone generation unit, that is, the detected gas flow rate, the detected ozone concentration Cd, and a plurality of functions. The control device 30 controls the power output based on the difference between the first power output P1 and the second power output P2.

[0088] Thereby, considering the characteristics of the relationship between the power output corresponding to the gas flow rate and the ozone concentration, the power output of the power supply unit 21 is adjusted. Therefore, it is possible to suppress, for example, that under the condition of a small gas flow rate, the adjustment amount of the power output is excessive and the detected ozone concentration Cd fluctuates significantly. It is possible to suppress, for example, that under the condition of a large gas flow rate, the adjustment amount of the power output is insufficient and the detected ozone concentration Cd is difficult to approach the set ozone concentration Cs. As a result, in the present embodiment, the actual ozone concentration can be quickly converged to the set ozone concentration.

[0089] In the feed-forward control according to the above-described embodiment, the control device 30 controls the power supply output to approach the first power supply output P1. The first power supply output P1 is the power supply output corresponding to the set ozone concentration Cs, and the set ozone concentration Cs corresponds to the gas flow rate. Therefore, under the condition that the difference between the detected ozone concentration Cd and the set ozone concentration Cs is large, the optimal power supply output corresponding to the gas flow rate can be obtained, and the detected ozone concentration Cd can be quickly made to approach the set ozone concentration Cs.

[0090] The multiple functions stored in the storage unit 33 are functions obtained by linearly connecting a power supply output and multiple points representing the ozone concentration corresponding to the power supply output. Therefore, these functions can be simplified, and the load on the arithmetic unit 32 can be reduced.

[0091] When the gas flow rate does not correspond to the multiple functions stored in the storage unit 33, multiple points are obtained by proportional distribution corresponding to the flow rate, and a new function is created based on these points. Therefore, even when the detected gas flow rate does not correspond to the gas flow rate stored in the storage unit 33, the optimal power supply output corresponding to the detected gas flow rate can be obtained.

[0092] Since there are three functions stored in the storage unit 33, the optimal power supply output can be obtained corresponding to the change in the minute gas flow rate.

[0093] The multiple functions stored in the storage unit 33 are functions obtained by linearly connecting a power supply output and multiple points representing the ozone concentration corresponding to the power supply output. Therefore, these functions can be simplified, and the load on the arithmetic unit 32 can be reduced.

[0094] If at least one of the first condition and the second condition is satisfied, the feed-forward control is executed. Therefore, under the condition that the difference between the detected ozone concentration Cd and the set ozone concentration Cs is large, the detected ozone concentration Cd can be quickly made to approach the set ozone concentration Cs.

[0095] The feed-forward control is executed at the start of operation. Therefore, under the condition that the difference between the detected ozone concentration Cd and the set ozone concentration Cs is large, the detected ozone concentration Cd can be quickly made to approach the set ozone concentration Cs.

[0096] 《Modification of the Embodiment》

[0097] The above-described embodiment may also adopt the configuration of the following modification.

[0098] Figure 7 The shown modification has a different configuration of the ozone generation device 20 compared to the above-described embodiment.

[0099] The ozone generation device 20 is provided with an MFC (strictly speaking, an automatic regulating valve such as a mass flow controller) 26 instead of the flow rate detection unit 23 of the above-described embodiment. The MFC 26 controls the gas flow rate supplied to the ozone generation unit 22 so that it becomes a preset set gas flow rate. The set gas flow rate is determined according to the set value input to the control device 30 or the requirements of the device on the facility side where the ozone generation device 20 is applied.

[0100] The ozone generation device 20 is provided with an APC (strictly speaking, an automatic pressure regulating valve such as an automatic pressure controller) 27 instead of the pressure detection unit 25 and the pressure regulating valve 13 of the above-described embodiment. The APC 27 performs control so that the pressure on its input side reaches a preset pressure.

[0101] In Modification 1, as an index indicating the gas flow rate, instead of using the detected gas flow rate, the set gas flow rate is used. Specifically, in the feedback control step ST21, a function corresponding to the set gas flow rate is determined or created. In steps ST22 to ST24, the same control is performed based on the function corresponding to the set gas flow rate.

[0102] Similarly, in the feedforward control step S11, a function corresponding to the set gas flow rate is determined or created. In steps ST12 to ST13, the same control is performed based on the function corresponding to the set gas flow rate.

[0103] In this way, by using the function corresponding to the set gas flow rate, even when it is difficult for the actual gas flow rate to converge to the set gas flow rate, the power supply output can be controlled to approach the final target value. Therefore, in feedback control and feedforward control, the ozone concentration can be quickly converged to the set ozone concentration Cs.

[0104] It should be noted that in Modification 1, a function corresponding to the detected gas flow rate detected by the MFC 26 may also be used in the same manner as in the above-described embodiment.

[0105] In Modification 1, the arrangements of the MFC 26 and the APC 27 may also be swapped. In this case, the APC 27 performs control so that the pressure on its output side reaches a preset pressure.

[0106] 〈Automatic acquisition operation〉

[0107] The control device 30 of Modification 1 executes an automatic acquisition operation. The automatic acquisition operation is executed after the ozone generation device 20 is installed in the facility. The automatic acquisition operation is executed before the ozone generation device 20 starts its first operation.

[0108] Automatic acquisition operation is used to automatically acquire the operations of multiple functions. Therefore, in the setting unit of the control device 30, multiple gas flows corresponding to the multiple functions and multiple power outputs for creating the functions for each gas flow are set.

[0109] In the case of automatically creating the three functions of the above-described embodiment, as the multiple gas flows, 10 L / min, 30 L / min, and 50 L / min are set. As the multiple power outputs, 20% corresponding to the ozone concentration generation point, 100% corresponding to the maximum point, 50% corresponding to the first intermediate point, and 70% corresponding to the second intermediate point are set. In the automatic acquisition operation, these set gas flows and the detected ozone concentration Cd corresponding to the set power output are sequentially measured. It should be noted that, as described above, the ozone concentration corresponding to the ozone concentration generation point is determined by the structure or method of the power supply unit 21 and the like. Therefore, in the automatic acquisition operation, the measurement of the power output corresponding to the ozone concentration generation point can also be omitted.

[0110] Specifically, in the automatic acquisition operation, the gas flow is adjusted to the above-described set value (for example, 10 L / min) by the MFC 26. Under the condition that the gas flow is 10 L / min, the output control unit 34 controls the power output to a specified set value. At this time, after a specified time for stabilizing the ozone concentration has elapsed, the concentration detection unit 24 detects the ozone concentration. Next, the output control unit 34 changes the power output to a different set value under the same gas flow, and then the concentration detection unit 24 detects the ozone concentration. In this way, data for each point (ozone concentration generation point, maximum point, first intermediate point, second intermediate point) corresponding to a gas flow of 10 L / min can be obtained, and the Figure 3 third function R3 shown can be created based on these data. These data and functions are stored in the storage unit 33.

[0111] The control device 30 repeatedly performs the same operation while changing the gas flow. In this way, in the automatic acquisition operation, multiple functions with different gas flows can be automatically created. As a result, after the control device 30 is installed, even if a person does not input each data, the optimal function corresponding to the installation environment can be obtained.

[0112] 《Other Embodiments》

[0113] In the above-described embodiment and modification example, the following structure can also be adopted.

[0114] The ozone gas generation device 20 of the above-described embodiment supplies the ozone gas (fluid) generated by the ozone generation unit 22 to the object. However, the ozone generation device 20 can also be a device that dissolves the ozone gas generated by the ozone generation unit 22 in water to generate ozone water and supplies the ozone water to the object.

[0115] The multiple functions stored in the storage unit 33 may be two, or may be four or more.

[0116] The multiple points for creating the multiple functions may be two, but are preferably three or more, and more preferably four or more as in the above-described embodiment. These multiple points preferably include at least an ozone concentration generation point and a maximum point.

[0117] The ozone generation unit 22 may not be a silent discharge method, and may be, for example, a surface discharge method or an electrolysis method.

[0118] -Industrial Applicability-

[0119] In summary, the present invention is useful for an ozone generation device.

[0120] -Symbol Explanation-

[0121] 20 Ozone generation device

[0122] 21 Power supply unit

[0123] 22 Ozone generation unit

[0124] 24 Concentration detection unit

[0125] 30 Control device

[0126] 33 Storage unit.

Claims

1. An ozone generating device, comprising a power supply unit and an ozone generating unit that generates ozone gas based on the power output of the power supply unit, characterized in that: The ozone generating device includes a concentration detection unit and a control device. The concentration detection unit detects the ozone concentration in the ozone gas generated by the ozone generating unit as the detected ozone concentration. The control device has a storage unit that stores two or more functions representing the relationship between the power output and the ozone concentration corresponding to the power output according to different raw material gas flow rates in the ozone generating unit, and The control device performs feedback control, in which, according to the set ozone concentration of the ozone generating unit, an index representing the raw material gas flow rate of the ozone generating unit, the detected ozone concentration, and the plurality of functions, the first power output corresponding to the set ozone concentration and the second power output corresponding to the detected ozone concentration are obtained, and the power output is controlled according to the difference between the first power output and the second power output. If at least one of the first condition and the second condition is satisfied, the control device performs feedforward control, in which the power output is controlled to make the power output approach the first power output. The first condition is a condition that the index representing the raw material gas flow rate changes by a specified value or more, and the second condition is a condition that the set ozone concentration changes by a specified value or more.

2. The ozone generating device according to claim 1, characterized in that: The storage unit stores three or more functions corresponding to unequal raw material gas flow rates.

3. The ozone generating device according to claim 1 or 2, characterized in that: The plurality of functions are respectively functions formed by linearly connecting a plurality of points representing the power output and the ozone concentration corresponding to the power output.

4. The ozone generating device according to claim 1 or 2, characterized in that: The control device performs an automatic acquisition operation, in which, by changing the raw material gas flow rate while detecting the detected ozone concentration, a plurality of the functions are automatically acquired.

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