Ozone generating system

Abstract

The present invention provides an ozone generation system that can detect abnormal discharge in a discharge tube when no short-circuit current flows through the discharge tube. [Solution] The ozone generation system comprises an ozone generator, a power supply, a camera, a memory unit, and a control unit. The ozone generator has a window. The camera can image the discharge of the discharge tube through the window. The memory unit stores a first image obtained by imaging the discharge of the discharge tube with the camera. The control unit generates a second image in which one or more colors are displayed in gradation according to the brightness of multiple regions in the first image, and the brightness is binarized with a predetermined value as the first threshold. The control unit detects that the proportion of regions in the second image whose density exceeds the first threshold is greater than or equal to a predetermined value, which is the second threshold, and determines that there is an abnormal discharge in the discharge tube. Based on the abnormal discharge determination result by the control unit, the ozone generation system either issues a warning to the operator or stops operation.

Description

Technical Field

[0001] Embodiments of the present invention relate to an ozone generation system.

Background Art

[0002] Generally, in an ozone generator, an ozone generator is connected to a high-voltage high-frequency power supply device. Further, a discharge tube having a dielectric and a metal film laminated on the dielectric is inserted into the ozone generator. The ozone generator generates ozone by supplying a high-voltage high-frequency alternating voltage to the discharge tube.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] When abnormal discharge occurs due to scratches or dirt on the metal film of the discharge tube, a hole is formed in the discharge tube, a short-circuit current flows, and the fuse connected to the discharge tube melts, thereby blocking the current flowing through the discharge tube and stopping the abnormal discharge. However, when no short-circuit current flows through the discharge tube, the fuse is not melted, so the current is not interrupted and abnormal discharge occurs intermittently. And since the ozone generator cannot detect abnormal discharge in a state where no short-circuit current flows, the abnormal discharge cannot be stopped immediately.

[0005] The problem to be solved by the present invention is to provide an ozone generation system capable of detecting abnormal discharge of a discharge tube when no short-circuit current flows through the discharge tube.

Means for Solving the Problems

[0006] To achieve the above objective, an ozone generation system according to an embodiment of the present invention comprises an ozone generator, a power supply unit, a camera, a memory unit, and a control unit. The ozone generator generates ozone by applying AC power to a discharge tube and causing a discharge, and has a window. The power supply unit supplies AC power to the ozone generator. The camera is located outside the ozone generator and can image the discharge of the discharge tube through the window. The memory unit stores a first image obtained by imaging the discharge of the discharge tube with the camera. The control unit generates a second image in which one or more colors are displayed in gradation according to the brightness of each of the multiple regions in the first image, and the brightness is binarized with a predetermined value among the gradation densities as the first threshold. The control unit also detects whether there is an abnormal discharge in the discharge tube by detecting whether the proportion of regions in the second image whose density exceeds the first threshold is greater than or equal to a predetermined value, which is the second threshold. Based on the abnormal discharge determination result by the control unit, the ozone generation system either issues a warning to the operator or stops operation. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 is a schematic diagram showing the ozone generation system of this embodiment. [Figure 2] Figure 2 is a perspective view showing an example of the ozone generator according to the above embodiment. [Figure 3] Figure 3 shows images of the discharge tube during normal discharge and abnormal discharge, which have been processed by the image processing unit of the above embodiment. [Figure 4] Figure 4 shows an example of a method for determining abnormal levels in the ozone generation system of this embodiment. [Figure 5] Figure 5 is a schematic diagram showing an example of the configuration of the power supply unit in this embodiment. [Figure 6] Figure 6 is a flowchart showing the processing flow by the ozone generation system. [Modes for carrying out the invention]

[0008] (Embodiment) Hereinafter, embodiments of the ozone generation system 1 according to the present invention will be described in detail with reference to the attached drawings. The configuration of the embodiments described below, as well as the operation and results (effects) brought about by said configuration, are merely examples and are not limited to the following description. In this specification, ordinal numbers are used solely to distinguish parts and components and do not indicate order or priority.

[0009] Referring to Figure 1, the configuration of the ozone generation system 1 according to an embodiment of the present invention will be described. Figure 1 is a schematic diagram showing the ozone generation system 1 of this embodiment. The ozone generation system 1 shown in Figure 1 consists of an ozone generator 10 and an abnormality detection system 11. The ozone generator 10 is a dielectric barrier type ozone generator.

[0010] The principle of ozone generation in an ozone generator is explained below. In an ozone generator, a discharge tube and a ground electrode are positioned separated by a predetermined discharge gap. A high-frequency high voltage is applied from a power supply to the high-voltage electrode, and ozone molecules are generated from oxygen molecules in the raw material gas at the discharge gap.

[0011] In the following description, an X-axis, Y-axis, and Z-axis orthogonal coordinate system is defined. The radial direction of the ozone generator 10 is defined as the X-axis direction, and the axial direction of the ozone generator 10 is defined as the Y-axis direction. Furthermore, the direction perpendicular to the X-axis and Y-axis directions is defined as the Z-axis direction. The X-axis direction may also be referred to as the width direction. The Y-axis direction may also be referred to as the depth direction. The Z-axis direction may also be referred to as the height direction. Note that the X-axis, Y-axis, and Z-axis orthogonal coordinate system is a coordinate system used for convenience, and embodiments of the present invention can also be applied to ozone generation systems to which this coordinate system is not applicable.

[0012] As shown in Figure 1, the ozone generation system 1 of this embodiment comprises an ozone generator 10 and an abnormality detection system 11 for detecting abnormalities occurring in the ozone generator 10. The ozone generator 10 has a main unit 101, a high-voltage power supply 102, and a power supply unit 104. The main unit 101 is an example of an ozone generator.

[0013] The main body of the device 101 generates ozone by applying alternating current power to an internal discharge tube, causing a discharge. The main body of the device 101 includes an airtight container 1011, a plurality of dielectric electrodes 1013, a metal electrode 1014, a discharge gap 1015 formed between each dielectric electrode 1013 and the metal electrode 1014, a cooling water supply unit 1016, a plurality of inspection windows 1017, and a plurality of fuses 1018. The airtight container 1011 is a container sealed from the outside. The airtight container 1011 is formed in a substantially cylindrical shape. The airtight container 1011 houses a plurality of dielectric electrodes 1013 and metal electrodes 1014. The inspection windows 1017 are an example of windows.

[0014] The outer circumference of the airtight container 1011 is formed with a gas inlet 1011a, a gas outlet 1011b, a cooling water inlet 1011c, and a cooling water outlet 1011d. A raw material gas containing oxygen is supplied to the airtight container 1011 from the outside via the gas inlet 1011a. The raw material gas pressure, which is the pressure of the raw material gas, is preferably 0.1 to 0.3 MPa (megapascals). The airtight container 1011 then discharges unreacted raw material gas and ozone to the outside via the gas outlet 1011b. Cooling water flows into the airtight container 1011 via the cooling water inlet 1011c. The airtight container 1011 then discharges the cooling water to the outside via the cooling water outlet 1011d.

[0015] The dielectric electrode 1013 comprises a dielectric portion 1013a, a conductive film 1013b, and a high-voltage supply terminal 1013c. The dielectric portion 1013a contains a dielectric material and is formed in a cylindrical shape with a central axis along the Y-axis. The central axis of the dielectric portion 1013a is parallel (including approximately parallel) to the central axis of the airtight container 1011. The high-voltage supply terminal 1013c is provided inside the conductive film 1013b and is electrically connected to the conductive film 1013b.

[0016] The metal electrode 1014 contains a conductive material. The metal electrode 1014 is provided inside the airtight container 1011 and outside the dielectric electrode 1013. The metal electrode 1014 is grounded and at ground potential. The metal electrode 1014 also has a spacer 1014a. The spacer 1014a protrudes from a part of the metal electrode 1014 toward the dielectric electrode 1013, forming (maintaining) a discharge gap 1015 between the metal electrode 1014 and the dielectric electrode 1013. The metal electrode 1014 also forms a water channel 1014b between itself and the inner circumferential surface of the airtight container 1011 through which cooling water flows. The water channel 1014b communicates with the cooling water inlet 1011c and the cooling water outlet 1011d of the airtight container 1011. Therefore, the cooling water flowing in from the cooling water inlet 1011c is discharged from the cooling water outlet 1011d via the water channel 1014b.

[0017] The high-voltage power supply 102 is electrically connected to the high-voltage supply terminal 1013c via the power supply unit 104 and each fuse 1018. The power supply unit 104 supplies AC power to the main unit 101. The high-voltage power supply 102 then applies a voltage to the dielectric electrode 1013 (conductive film 1013b) via the power supply unit 104, fuse 1018, and high-voltage supply terminal 1013c. As a result, the ozone generator 10 generates a discharge in the raw material gas flowing into the discharge gap 1015, and generates ozone through this discharge. The cooling water supply unit 1016 is, for example, a pump. The cooling water supply unit 1016 supplies cooling water from the cooling water inlet 1011c of the airtight container 1011 to the water channel 1014b.

[0018] FIG. 2 is a perspective view showing an example of the ozone generator 10 of the present embodiment. As shown in FIGS. 1 and 2, a plurality of inspection viewing windows 1017 are provided on the side surface of the apparatus main body 101. The plurality of inspection viewing windows 1017 are windows through which an operator can visually inspect the inside of the apparatus main body 101. The operator observes the discharge state of the discharge tube (dielectric electrode 1013) disposed inside the apparatus main body 101 through the plurality of inspection viewing windows 1017. The plurality of inspection viewing windows 1017 are formed in a substantially circular flat plate shape. Each of the plurality of inspection viewing windows 1017 is disposed at substantially equal intervals from each other on the side surface of the apparatus main body 101 in the +Y direction.

[0019] The abnormality detection system 11 includes a plurality of cameras 11a, an abnormal discharge detection unit 11b, and a signal output unit 11c. The plurality of cameras 11a are disposed outside the apparatus main body 101. The plurality of cameras 11a are cameras capable of imaging the discharge tube and the discharge state disposed inside the apparatus main body 101 through the inspection viewing window 1017. One camera 11a is disposed opposite to one inspection viewing window 1017. The imaging directions of the plurality of cameras 11a are the directions facing the opposing inspection viewing windows 1017. The camera 11a is spaced apart from the opposing inspection viewing window 1017. The data output by the imaging of the camera 11a is still images, but may also be moving image data. In FIG. 2, the description of the plurality of cameras 11a is omitted.

[0020] The number of inspection visual windows 1017 and cameras 11a is four each in this embodiment, but it is not limited thereto. For example, the number may be three or five each. Also, the number of cameras 11a may be less than the number of inspection visual windows 1017. The number of inspection visual windows 1017 and cameras 11a is appropriately determined according to, for example, the angle of view of the cameras 11a, the positions where they are arranged, and the like. That is, the number and positions of the inspection visual windows 1017 and cameras 11a may be any number and positions as long as the cameras 11a can observe the discharge state of the entire discharge tube. When there are a plurality of cameras 11a, each camera 11a is arranged such that the imaging ranges partially overlap each other. In this case, the plurality of output image data or video data may be processed by the abnormal discharge detection unit 11b described later after the imaged ranges are combined.

[0021] The abnormal discharge detection unit 11b monitors and records the discharge state generated in the dielectric electrode 1013 by a plurality of cameras 11a, and detects abnormal discharge of the discharge tube based on the recorded image data. The abnormal discharge detection unit 11b includes a storage unit 111 and a control unit 112. The control unit 112 includes an image processing unit 112a and a threshold calculation unit 112b. The plurality of cameras 11a, the storage unit 111, the image processing unit 112a, and the threshold calculation unit 112b are communicably connected to each other by a LAN (Local Area Network).

[0022] The storage unit 111 stores the first image P1 obtained by imaging the discharge of the discharge tube with the camera 11a, and outputs the stored first image P1 to the image processing unit 112a. The first image P1 is an example of unprocessed image data or video data obtained by the camera 11a taking an image.

[0023] Here, referring to FIG. 3, the image processing of the image of the discharge tube by the image processing unit 112a will be described. FIG. 3 is a diagram showing images of the discharge tube during normal discharge and abnormal discharge processed by the image processing unit 112a of this embodiment.

[0024] The image processing unit 112a performs image processing on the first image P1 output from the storage unit 111 to generate a second image P2. More specifically, the image processing unit 112a generates a second image P2 in which one or more colors are displayed in gradation according to the brightness of each of the multiple regions in the first image P1, and the brightness is binarized using a predetermined value among the gradation densities as the first threshold D1. Figure 3 shows the second image P2, which is a binarized display of the first image P1, an image of a discharge tube captured by the camera 11a, after image processing by the image processing unit 112a. In Figure 3, (a) shows the discharge tube during normal discharge, (b) shows the discharge tube in the early stages of abnormal discharge, and (c) shows the discharge tube during abnormal discharge where discharge occurs intermittently.

[0025] Here, the luminance gradation display in the image processing of the image processing unit 112a refers to, for example, a display using 256-level grayscale. However, the luminance gradation display is not limited to this; for example, it may also be a 256-level color display using RGB.

[0026] Furthermore, the first threshold D1 is set, for example, when an operator inputs a predetermined value to an input unit (not shown) of the anomaly detection system 11, and the input value is output to the image processing unit 112a. The first threshold D1 is, for example, 200 when white is 255 and black is 0 in a 256-level grayscale display. In this case, as shown in Figure 3, in the second image P2, areas with 200 or more pixels are displayed in white, and areas with less than 199 pixels are displayed in black.

[0027] The threshold calculation unit 112b detects changes in the brightness of multiple regions in the second image P2 to determine abnormal discharge of the discharge tube. More specifically, the threshold calculation unit 112b detects, for example, that the proportion of regions in the second image P2 where the pixel density exceeds the first threshold D1 is greater than or equal to a predetermined value, the second threshold D2, to determine abnormal discharge of the discharge tube.

[0028] Here, the second threshold D2 is set, for example, when an operator inputs a predetermined value to an input unit (not shown) of the anomaly detection system 11, and that value is output to the image processing unit 112a. The second threshold D2 is, for example, 30% of the total area of ​​the discharge tube in the discharge tube image data, where the entire area of ​​the discharge tube is considered 100%. In this case, the threshold calculation unit 112b detects that in the second image P2, the proportion of the area with 200 or more pixels, which is the first threshold D1, exceeds 30% of the total area of ​​the discharge tube (second threshold D2).

[0029] Next, with reference to Figure 4, the determination of abnormal discharge in the discharge tube by the threshold calculation unit 112b will be explained. Figure 4 is a diagram showing an example of an abnormal level determination method in the ozone generation system 1 of this embodiment. The bar graph in Figure 4 shows the ratio of high-luminance areas (areas where luminance is equal to or greater than the first threshold D1) and low-luminance areas (areas where luminance is less than the first threshold D1) when the entire discharge tube area in the second image P2 is set to 100%. More specifically, abnormal level 0 in Figure 4 shows the ratio of high-luminance areas to low-luminance areas during normal discharge as shown in Figure 3(a). Abnormal level 1 in Figure 4 shows the ratio of high-luminance areas to low-luminance areas during the initial stage of abnormal discharge as shown in Figure 3(b). Abnormal level 2 in Figure 4 shows the ratio of high-luminance areas to low-luminance areas during abnormal discharge as shown in Figure 3(c).

[0030] In this embodiment, the image processing unit 112a sets two second thresholds D2a and D2b, which are different values ​​from each other. The threshold calculation unit 112b determines different abnormal levels within the range of percentages of each region divided using the two second thresholds D2a and D2b as boundaries. Figure 4 shows an example where the second threshold D2a is 5% and the second threshold D2b is 20%. In this example, abnormal level 0 indicates a state where the percentage of high-luminance regions is less than 5%, abnormal level 1 indicates a state where the percentage of high-luminance regions is 5% or more but less than 20%, and abnormal level 2 indicates a state where the percentage of high-luminance regions is 20% or more. That is, the threshold calculation unit 112b determines abnormal level 0 when the percentage of high-luminance regions is less than 5%, abnormal level 1 when the percentage of high-luminance pixels is 5% or more but less than 20%, and abnormal level 2 when the percentage of high-luminance pixels is 20% or more. In this way, the threshold calculation unit 112b determines the abnormal level according to the percentage of high-luminance regions in the second image P2.

[0031] The types of abnormality levels may include, for example, abnormality level 4 or higher, and the proportion of areas with high luminance that serve as the criterion for determining each abnormality level may be outside the range of values ​​mentioned above.

[0032] The abnormal level signal determined by the threshold calculation unit 112b is output to the control unit 112. The control unit 112 then determines abnormal discharge of the discharge tube according to the abnormal level output from the threshold calculation unit 112b. In this embodiment, the control unit 112 determines that abnormal level 0 is a normal discharge state, abnormal level 1 is an initial abnormal discharge state, and abnormal level 2 is an abnormal discharge state.

[0033] Next, with reference to Figure 5, the operation of the ozone generating system 1 when an abnormal discharge occurs will be described. Figure 5 is a schematic diagram showing an example of the configuration of the power supply unit 104 in this embodiment. Based on the abnormal discharge determination result by the threshold calculation unit 112b, the ozone generating system 1 either issues a warning to the operator or stops operation.

[0034] As shown in Figure 5, the power supply unit 104 includes an abnormal signal output unit 1041 and a display unit 1042. The abnormal signal output unit 1041 is communicatively connected to the signal output unit 11c. The signal output unit 11c is communicatively connected to the control unit 112 (see Figure 1).

[0035] When an abnormal discharge occurs, that is, when the control unit 112 determines that an abnormal discharge state has occurred or is in an abnormal discharge state, the control unit 112 outputs a signal (hereinafter referred to as an abnormal signal) to the signal output unit 11c indicating that it has detected an abnormal discharge. The signal output unit 11c then outputs the abnormal signal to the abnormal signal output unit 1041. At this time, the control unit 112 internally records the time when it output the signal indicating that it detected an abnormal discharge.

[0036] At this point, a signal indicating that an abnormal discharge has occurred in the discharge tube is output from the abnormal signal output unit 1041 to the display unit 1042. The display unit 1042 then illuminates a lamp or the like to indicate that an abnormal discharge has occurred in the discharge tube. This allows the operator to visually recognize that an abnormal discharge has occurred in the discharge tube by looking at the lamp or the like.

[0037] The lamp on the display unit 1042, once lit, will remain lit even if the control unit 112 subsequently determines that a normal discharge has occurred. The display unit 1042 may also light up a lamp or the like to indicate that an abnormal discharge has occurred in the discharge tube, and may also intermittently emit an alarm sound to inform those nearby that an abnormal discharge has occurred in the discharge tube.

[0038] If the control unit 112 determines that an abnormal discharge state is occurring, an abnormal signal output unit 1041 outputs a signal to the gate signal of a switching element such as an IGBT of the inverter element to cut off the power supplied to the main unit 101, thereby cutting off the power supply to the main unit 101. As a result, the ozone generator 10 immediately stops operating.

[0039] The operation of the power supply unit 104 in response to the determination of each discharge state by the control unit 112 is not limited to the above. For example, the power supply to the main unit 101 may be cut off even when the control unit 112 determines that an initial abnormal discharge state has occurred. Alternatively, depending on the abnormal level determined by the threshold calculation unit 112b, the power supply to the main unit 101 may be cut off after a predetermined time has elapsed since the abnormal signal was output from the control unit 112 to the signal output unit 11c.

[0040] When an operator performs maintenance on the ozone generator 10, the operator first visually checks whether the lamp on the display unit 1042 is lit. If the lamp on the display unit 1042 is lit, the operator checks the time recorded in the control unit 112 when a signal indicating the detection of abnormal discharge was output. Then, the operator identifies the image data corresponding to the confirmed time in the storage unit 111 and observes the discharge state of the discharge tube displayed in that image data. In this way, the operator can identify the discharge tube that experienced abnormal discharge from among multiple discharge tubes by observing the image.

[0041] In conventional ozone generation systems, when an operator performs maintenance on the ozone generator, they need to pull out all the discharge tubes from the main unit and visually check the condition of each discharge tube to identify which one is experiencing abnormal discharge.

[0042] In contrast, in the ozone generating system 1 of this embodiment, the operator can identify the time when an abnormal discharge occurred by checking the time recorded in the control unit 112, which indicates that a signal indicating the detection of an abnormal discharge was output. Furthermore, by observing the image of the discharge tube recorded at that time, which is stored in the memory unit 111, the operator can identify the discharge tube in which the abnormal discharge occurred. In other words, the operator can quickly identify the discharge tube in which the abnormal discharge occurred without directly visually checking the condition of all the discharge tubes. Consequently, the ozone generating system 1 can be made more maintainable.

[0043] (Process flow of the ozone generation system) Next, with reference to Figure 6, the processing flow of the ozone generating system 1 will be explained. Figure 6 is a flowchart showing the processing flow of the ozone generating system 1. Figure 6 shows the processing flow of the ozone generating system 1 from the time the camera 11a captures an image of the discharge state of the discharge tube, to the time the control unit 112 determines an abnormal discharge of the discharge tube, and to the time the power supply unit 104 performs each operation.

[0044] In step S101 in Figure 6, first, the camera 11a captures an image of the discharge state of each discharge tube. Then, in step S102, the storage unit 111 saves the first image P1 captured by the camera 11a and outputs the saved first image P1 to the image processing unit 112a.

[0045] Next, in step S103, the image processing unit 112a generates an image in which one or more colors are displayed in gradation according to the brightness of each of the multiple regions in the first image P1 output from the storage unit 111.

[0046] Then, in step S104, the image processing unit 112a performs a binarization process on the grayscaled image in step S103. More specifically, in step S103, the image processing unit 112a generates a second image P2 by binarizing the brightness of the grayscaled image, using a predetermined value among the grayscale densities as the first threshold D1.

[0047] Next, in step S105, the threshold calculation unit 112b calculates the proportion of regions in the second binarized image P2 where the pixel density exceeds the first threshold D1. Then, in step S106, the threshold calculation unit 112b refers to the second threshold D2a output to the control unit 112 and determines whether the proportion of regions in the second image P2 where the pixel density exceeds the first threshold D1 is equal to or greater than the second threshold D2a.

[0048] In step S106, if the threshold calculation unit 112b determines that the percentage of areas in the second image P2 where the pixel density exceeds the first threshold D1 is less than the second threshold D2a, then in step S107, the threshold calculation unit 112b determines the discharge state of the discharge tube to be abnormal level 0 and outputs this determination result to the control unit 112. Then, in step S108, the control unit 112 determines the discharge state of the discharge tube to be a normal discharge state based on the determination result output from the threshold calculation unit 112b, and returns to step S105.

[0049] In step S106, if the threshold calculation unit 112b determines that the proportion of areas in the second image P2 where the pixel density exceeds the first threshold D1 is greater than or equal to the second threshold D2a, then in step S109, the control unit 112 outputs an abnormal signal to the signal output unit 11c. The signal output unit 11c then outputs the abnormal signal to the abnormal signal output unit 1041.

[0050] In step S109, when an abnormal signal is output to the abnormal signal output unit 1041, in step S110, a signal is output from the abnormal signal output unit 1041 to the display unit 1042, informing the power supply unit 104 that an abnormal discharge has occurred in the discharge tube. The display unit 1042 then lights up a lamp or the like to indicate that an abnormal discharge has occurred in the discharge tube.

[0051] Next, in step S111, the threshold calculation unit 112b refers to the second threshold D2b output to the control unit 112 and determines whether the proportion of areas in the second image P2 where the pixel density exceeds the first threshold D1 is equal to or greater than the second threshold D2b.

[0052] In step S111, if the threshold calculation unit 112b determines that the percentage of areas in the second image P2 where the pixel density exceeds the first threshold D1 is less than the second threshold D2b, then in step S112, the threshold calculation unit 112b determines the discharge state of the discharge tube to abnormal level 1 and outputs this determination result to the control unit 112. Then, in step S113, the control unit 112 determines the discharge state of the discharge tube to be the initial abnormal discharge state based on the determination result output from the threshold calculation unit 112b, and returns to step S105.

[0053] In step S111, if the threshold calculation unit 112b determines that the proportion of areas in the second image P2 where the pixel density exceeds the first threshold D1 is greater than or equal to the second threshold D2b, then in step S114, the threshold calculation unit 112b determines that the discharge state of the discharge tube is abnormal level 2 and outputs this determination result to the control unit 112. Then, in step S115, the control unit 112 determines that the discharge state of the discharge tube is an abnormal discharge state based on the determination result output from the threshold calculation unit 112b.

[0054] In step S115, if the control unit 112 determines that the discharge state of the discharge tube is an abnormal discharge state, in step S116, the abnormal signal output unit 1041 outputs a signal to the gate signal of a switching element such as an IGBT of the inverter element to cut off the power supplied to the main unit 101. As a result, the power supply to the main unit 101 is cut off, and the ozone generator 10 stops operating. Processing by the ozone generation system 1 is performed according to the above procedure.

[0055] In the above-described embodiment, the ozone generating system 1 comprises a main unit 101, a power supply unit 104, a camera 11a, a storage unit 111, and a control unit 112. The main unit 101 generates ozone by applying AC power to a discharge tube and causing a discharge, and has a window. The power supply unit 104 supplies AC power to the main unit 101. The camera 11a is disposed outside the main unit 101 and can image the discharge of the discharge tube through an inspection window 1017. The storage unit 111 stores a first image P1 obtained by imaging the discharge of the discharge tube with the camera 11a. The control unit 112 generates a second image P2 in which one or more colors are displayed in gradation according to the brightness of each of a plurality of regions in the first image P1, and the brightness is binarized with a predetermined value among the gradation densities as the first threshold D1. Furthermore, the control unit 112 detects that the proportion of regions in the second image P2 where the concentration exceeds the first threshold D1 is equal to or greater than a predetermined value, the second threshold D2, and determines that there is an abnormal discharge in the discharge tube. Based on the abnormal discharge determination result by the control unit 112, the ozone generation system 1 either issues a warning to the operator or stops operation.

[0056] In the ozone generating system described above, the memory unit 111 stores a first image P1 obtained by a camera 11a, which is located outside the main body 101 of the device, capturing images of the discharge of the discharge tube. The control unit 112 then generates a second image P2 in which one or more colors are displayed in gradation according to the brightness of each of the multiple regions in the first image P1, and the brightness is binarized using a predetermined value among the gradation densities as the first threshold D1. The control unit 112 also detects whether the proportion of regions in the second image P2 whose density exceeds the first threshold D1 is equal to or greater than a predetermined value, the second threshold D2, and determines that there is an abnormal discharge in the discharge tube. Based on the abnormal discharge determination result by the control unit 112, the ozone generating system 1 either issues a warning to the operator or stops operation.

[0057] In this system, the image captured by camera 11a of the discharge of the discharge tube is processed, and an abnormal discharge of the discharge tube is determined based on the processed image. More specifically, the control unit 112 displays multiple regions in the first image P1 in gradation according to their brightness, generates a second image P2 that is binarized into high-brightness and low-brightness regions, and detects changes in the proportion of regions in the second image P2 where the density exceeds the first threshold D1. As a result, the control unit 112 can determine an abnormal discharge of the discharge tube based on the second image P2. Consequently, with the ozone generation system 1, even when no short-circuit current flows through the discharge tube, an abnormal discharge of the discharge tube can be detected based on the image from camera 11a.

[0058] Furthermore, in the above-described embodiment, the second threshold D2 is a plurality of mutually different values ​​(second thresholds D2a, D2b), and the threshold calculation unit 112b determines that the abnormal levels are mutually different within the range of proportions of each region divided with the plurality of second thresholds D2a, D2b as boundaries.

[0059] In the configuration described above, the second threshold D2 is a set of multiple distinct values ​​(second thresholds D2a and D2b). Therefore, the proportion of the region in the second image P2 where the pixel density exceeds the first threshold D1 is divided into multiple ranges by the second threshold D2. The threshold calculation unit 112b then determines that each state in each of the divided ranges is at a different abnormal level. As a result, the threshold calculation unit 112b can determine an appropriate abnormal level in the second image P2 according to the proportion of the region where the pixel density exceeds the first threshold D1. Consequently, the operator can predict the occurrence of abnormal discharge in the discharge tube from the magnitude of the abnormal level determined by the threshold calculation unit 112b.

[0060] (Variation 1) In image processing by the image processing unit 112a, the image processing unit 112a may generate a third image P3 in which one or more colors are displayed in gradation according to the brightness of each of the multiple regions in the first image P1, rather than a second image P2 in which the brightness has been binarized. In this case, the threshold calculation unit 112b detects that the proportion of regions in the multiple regions of the third image P3 in which the pixel density exceeds a predetermined value, the third threshold D3, is equal to or greater than a predetermined value, the fourth threshold D4, and determines abnormal discharge of the discharge tube. Furthermore, the fourth threshold D4 may be set to two different values, D4a and D4b, as in the embodiment described above.

[0061] In the above-described embodiment, the control unit 112 (image processing unit 112a) generates a third image P3 in which one or more colors are displayed in gradation according to the brightness of each of the multiple regions in the first image P1. The control unit 112 (threshold calculation unit 112b) detects that the proportion of regions in the multiple regions of the third image P3 whose density exceeds a predetermined value, the third threshold D3, is equal to or greater than a predetermined value, the fourth threshold D4, and determines that there is an abnormal discharge in the discharge tube.

[0062] In the above configuration, the control unit 112 (image processing unit 112a) generates a third image P3 in which one or more colors are displayed in gradation according to the brightness of each of the multiple regions in the first image P1. The control unit 112 (threshold calculation unit 112b) detects that the proportion of pixels in the multiple regions of the third image P3 whose pixel density exceeds a predetermined value, a third threshold D3, is equal to or greater than a predetermined value, a fourth threshold D4, and determines abnormal discharge of the discharge tube. That is, the image processing unit 112a generates a third image P3 in which the brightness is displayed in gradation, without generating a second image P2 in which the brightness of the first image P1 is binarized. Furthermore, the threshold calculation unit 112b determines abnormal discharge of the discharge tube based on the pixel density in the third image P3. As a result, the ozone generation system 1 can shorten the steps until the threshold calculation unit 112b determines abnormal discharge of the discharge tube compared to the method of generating a second image P2, and thus can determine abnormal discharge more quickly.

[0063] (Modification 2) The abnormal discharge detection unit 11b may be retrofitted to an existing ozone generator. Specifically, a camera 11a is positioned facing the inspection window of the ozone generator, and the camera 11a is connected to the abnormal discharge detection unit 11b. Furthermore, the abnormal discharge detection unit 11b is connected to the power supply unit 104 via the signal output unit 11c. This allows the ozone generator to be equipped with the functionality of the abnormal discharge detection unit 11b described above.

[0064] Although several embodiments of the present invention have been described above, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Explanation of Symbols]

[0065] 1. Ozone generating system 11a camera 11b Abnormal discharge detection unit 101 Main unit of the device 104 Power supply 111 Storage section 112 Control Unit 112a Image Processing Unit 112b Threshold calculation unit 1017 Inspection Visual Window D1 First threshold D2, D2a, D2b Second threshold D3 Third threshold D4, D4a, D4b: Fourth threshold P1 First image P2 Second image P3 Third image

Claims

1. An ozone generator has a window and generates ozone by applying AC power to a discharge tube and causing a discharge. A power supply device that supplies AC power to the ozone generator, A camera is provided that is located outside the ozone generator and capable of imaging the discharge of the discharge tube through the window. A storage unit that stores a first image obtained by capturing the discharge of the discharge tube with the camera, Control unit and Equipped with, The control unit, In the first image, one or more colors are displayed in gradation according to the brightness of each of the multiple regions, and a second image is generated by binarizing the brightness with a predetermined value among the gradation densities as the first threshold. In the second image, it is detected that the proportion of regions in which the density exceeds the first threshold is greater than or equal to a predetermined value, which is a second threshold, and an abnormal discharge of the discharge tube is determined. Based on the abnormal discharge detection result by the control unit, either a warning is issued to the operator or the operation is stopped. Ozone generating system.

2. The second threshold is a plurality of values ​​that are different from each other, and the control unit determines that the abnormal levels are different from each other within the range of proportions of each region divided with the plurality of second thresholds as boundaries. The ozone generating system according to claim 1.

3. The control unit generates a third image in which one or more colors are displayed in gradation according to the brightness of each of the multiple regions in the first image, and detects whether the proportion of regions in the third image whose density exceeds a predetermined value (a third threshold) is equal to or greater than a predetermined value (a fourth threshold) to determine an abnormal discharge of the discharge tube. The ozone generating system according to claim 1.

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