Photovoltaic cell panel photoluminescence window scanning imaging invisible defect detection device

Abstract

The invention provides a photovoltaic cell panel photoluminescence window scanning imaging invisible defect detection device. A photovoltaic cell panel end of a method comprises the following steps: acquiring a plurality of groups of rectangular window light spots which are emitted by a continuously moving near-infrared light excitation light source under the control of an image scanning and processing system and are processed by a light processor; and the light spot irradiation light of the window induces to generate a plurality of groups of continuously moving photoluminescence windows. According to the photoluminescence imaging, a driving voltage applying link required by the photoluminescence imaging is abandoned, so that the field detection efficiency can be improved; the technology of large-area detection of the invisible defects of the photovoltaic panel is realized; the light-induced excitation light source is adopted as the near-infrared light excitation light source, and meanwhile, the light processor is arranged between the near-infrared light excitation light source and the photovoltaic cell panel and is used for processing a light beam emitted by the laser light source into a rectangular window light spot, so that the required light source power is reduced, practicability is realized, and the device is suitable for long-distance field imaging detection.

Description

Technical Field

[0001] The present invention belongs to the technical field of photovoltaic panels, and particularly relates to a device for detecting invisible defects in a photovoltaic panel by means of photoluminescence window scanning imaging. Background Art

[0002] Silicon photovoltaic panels mainly include monocrystalline silicon photovoltaic panels, polycrystalline silicon photovoltaic panels, and amorphous silicon photovoltaic panel components, which dominate the field of solar cell applications. During the processes of material preparation, panel manufacturing, product transportation, installation, operation, etc. of these components, various non-visible invisible defects are likely to occur, including hidden cracks, fragments, black spots, broken grids, surface contamination, local heating, etc. These defects will reduce the photoelectric conversion efficiency and service life of the photovoltaic panel, and even pose potential safety hazards. Therefore, it is of great significance to pre-detect, especially online image detect, the invisible defects of photovoltaic panel components.

[0003] Existing defect imaging detection technologies for photovoltaic panels mainly include thermal imaging, electroluminescence imaging, photoluminescence imaging, etc. When using electroluminescence imaging, it includes a driving voltage application step, resulting in low on-site detection efficiency.

[0004] In addition, the literature "Research on Defect Detection Technology of Photovoltaic Panels Based on High Frame Rate InGaAs Cameras" introduces a photoluminescence imaging technology, which uses an LED surface light source as the excitation light source for photoluminescence, but the required light source power is too large, which is not conducive to practical application; Chinese invention patent CN118199517A, "Photoluminescence Imaging System and Method for Photovoltaic Panels Based on Linear Array InGaAs Cameras" introduces a technology that uses a linear array LED as the light excitation source and uses a conveyor belt structure to achieve target scanning imaging, and this technology is also not suitable for long-distance on-site imaging detection. Summary of the Invention

[0005] The purpose of the present invention is to overcome the above problems and provide a device for detecting invisible defects in a photovoltaic panel by means of photoluminescence window scanning imaging.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is:

[0007] On the one hand, a method for detecting invisible defects by means of photoluminescence window scanning imaging is provided, and the photovoltaic panel end includes the following steps:

[0008] Obtain multiple groups of rectangular window light spots that are continuously moving under the control of an image scanning and processing system and are emitted by a near-infrared light excitation source and processed by an optical processor;

[0009] The shaped window light spot irradiates light to induce multiple groups of continuously moving photoluminescent emission windows.

[0010] As a further improvement, the photoluminescent emission windows are composed of adjacent photoluminescent edge light interfaces.

[0011] As a further improvement, the photovoltaic panels at the photovoltaic panel end are monocrystalline silicon photovoltaic panels or polycrystalline silicon photovoltaic panels.

[0012] As a further improvement, the spectral energy of the photoluminescence in the photoluminescent emission windows is in the short-wave infrared range with a wavelength of 1050nm to 1250nm.

[0013] On the one hand, the present invention provides a method for detecting invisible defects by scanning and imaging a photoluminescent window, characterized in that the area array camera end includes the following steps:

[0014] Collect defect images of multiple groups of continuously moving photoluminescent emission windows;

[0015] Send the multiple groups of defect images to an image scanning and processing system.

[0016] As a further improvement, the area array camera at the area array camera end is a near-infrared or short-wave infrared camera, including an InGaAs camera or other types of short-wave infrared cameras.

[0017] On the one hand, the present invention also provides a method for detecting invisible defects by scanning and imaging a photoluminescent window, and the image scanning and processing system includes the following steps:

[0018] Receive multiple groups of defect images;

[0019] Process the multiple groups of defect images and synthesize a group of window images.

[0020] On the one hand, the present invention also provides a device for detecting invisible defects by scanning and imaging a photoluminescent window, which realizes a method for detecting invisible defects by scanning and imaging a photoluminescent window as described in any one of the above, and includes:

[0021] Photovoltaic panels, which are used to receive and obtain multiple groups of rectangular window light spots emitted by a continuously moving near-infrared light excitation source under the control of an image scanning and processing system and processed by an optical processor; and are also used for the shaped window light spot to irradiate light to induce multiple groups of continuously moving photoluminescent emission windows;

[0022] A scanning mechanism, including an electrically controlled translation stage or an electrically controlled rotary stage, on which a near-infrared light excitation source is installed; used to drive the near-infrared light excitation source to rotate, move the rectangular window light spot emitted by the near-infrared light excitation source on the photovoltaic panel; and also used to receive the scanning instructions of the image scanning and processing system;

[0023] An area array camera, used to collect defect images of multiple groups of continuously moving photoluminescence emission windows; and also used to send multiple groups of the defect images to the image scanning and processing system;

[0024] An optical processor, including a shaping lens or / and a beam splitting prism, located between the photovoltaic panel and the scanning mechanism and between the photovoltaic panel and the area array camera. The optical processor located between the photovoltaic panel and the scanning mechanism is used to process the light beam emitted by the near-infrared light excitation source into a rectangular window light spot; the optical processor located between the photovoltaic panel and the area array camera is used to process the defect image elements emitted by the photoluminescence emission window;

[0025] An image scanning and processing system, which is electrically connected to the scanning mechanism and the area array camera; used to control the rotation of the scanning mechanism and process multiple groups of defect images to synthesize a group of window images;

[0026] A display, which is electrically connected to the image scanning and processing system and used to display the synthesized window images.

[0027] As a further improvement, the near-infrared light excitation source includes a near-infrared LED light source or a near-infrared laser light source.

[0028] On the other hand, the present invention also provides a photoluminescence window scanning imaging invisible defect detection device, which includes at least one processor and a memory that stores instructions. When the instructions are executed by at least one processor, the method in the above technical solution is implemented.

[0029] A computer-readable storage medium stores a computer program, and the computer program is executed by a processor to implement the method described in the steps of the above technical solution.

[0030] A computer program product includes a computer program, and when the computer program is executed by a processor, the method described in the steps of the above technical solution is implemented.

[0031] The beneficial effects of the present invention are:

[0032] The photoluminescence imaging of the present invention abandons the link of applying driving voltage required for electroluminescence imaging, which is beneficial to improving the on-site detection efficiency; realizes the technology of large-area detection of invisible defects of photovoltaic panels; uses a near-infrared light excitation source as the photoexcitation light source, and a light processor is arranged between the near-infrared light excitation source and the photovoltaic panel to process the light beam emitted by the laser light source into a rectangular window light spot, reducing the required light source power and realizing practical and suitable long-distance on-site imaging detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The present invention has the following drawings:

[0034] Figure 1 is a schematic flow chart of a method for detecting invisible defects by photoluminescence window scanning imaging of a photovoltaic panel of the present invention;

[0035] Figure 2 is a schematic principle diagram of a device for detecting invisible defects by photoluminescence window scanning imaging of a photovoltaic panel using an electrically controlled turntable provided by an embodiment of the present invention Figure 1 ;

[0036] Figure 3 is a schematic principle diagram of a device for detecting invisible defects by photoluminescence window scanning imaging of a photovoltaic panel using an electrically controlled translation stage provided by an embodiment of the present invention Figure 2 ;

[0037] Figure 4 is a schematic diagram of the spectral sensitivity curve of an InGaAS camera and the photoluminescence spectrum curve of a crystalline silicon photovoltaic panel provided by an embodiment of the present invention;

[0038] Figure 5 Schematic diagram of a device for detecting invisible defects by photoluminescence window scanning imaging of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0039] The following embodiments further illustrate the content of the present invention, but should not be construed as limiting the present invention. Without departing from the spirit and essence of the present invention, any modification or replacement of the methods, steps or conditions of the present invention shall fall within the scope of the present invention.

[0040] On the one hand, the present invention provides a method for detecting invisible defects by photoluminescence window scanning imaging. The photovoltaic panel end includes the following steps:

[0041] Step S100: Obtain multiple groups of rectangular window light spots that are continuously moving under the control of an image scanning and processing system and are emitted by a near-infrared light excitation source and processed by a light processor;

[0042] For example, the scanning mechanism drives the excitation light source to rotate or move, so that the window light spot moves on the surface of the photovoltaic panel, forming an adjacent photoluminescence window. The excitation light source is used to emit a rectangular window light spot to irradiate on the surface of the photovoltaic panel to induce the photovoltaic panel to generate photoluminescence, and to contrast the invisible defects of the photovoltaic panel.

[0043] Step S101: The shaped window light spot irradiates the light to induce the generation of multiple groups of continuously moving photoluminescence emission windows.

[0044] In some embodiments of the present invention, the photoluminescence emission window is composed of adjacent photoluminescence edge light interfaces.

[0045] In some embodiments of the present invention, the photovoltaic panel at the photovoltaic panel end is a monocrystalline silicon photovoltaic panel or a polycrystalline silicon photovoltaic panel.

[0046] For example, as Figure 4 shown, the photovoltaic panel is a polycrystalline silicon or monocrystalline silicon photovoltaic panel, which generates photoluminescence under the irradiation of a near-infrared light source, and the wavelength range of the fluorescence is mainly distributed in the interval of 1100 - 1200 nm.

[0047] In some embodiments of the present invention, as Figure 4 shown, the spectral energy of the photoluminescence in the photoluminescence emission window is in the short-wave infrared range of 1050 nm to 1250 nm. The area array camera is a near-infrared or short-wave infrared camera, including an InGaAs camera and other types of short-wave infrared cameras, which have high sensitivity in the wavelength range of 1050 nm to 1250 nm.

[0048] On the one hand, the present invention provides a method for detecting invisible defects by scanning and imaging a photoluminescence window, characterized in that the area array camera end (the area array camera simultaneously images the entire photoluminescence window through an optical lens and saves the image) includes the following steps:

[0049] Step S200: Acquire defect images of multiple groups of continuously moving photoluminescence emission windows;

[0050] Step S201: Send multiple groups of the defect images to an image scanning and processing system.

[0051] In some embodiments of the present invention, the area array camera at the area array camera end is a near-infrared or short-wave infrared camera, including an InGaAs camera or other types of short-wave infrared cameras.

[0052] For example, as Figure 4 shown, the area array camera is a near-infrared or short-wave infrared camera, including an InGaAs camera and other types of short-wave infrared cameras, which have high sensitivity in the wavelength range of 1050 nm to 1250 nm.

[0053] On the one hand, the present invention also provides a method for detecting invisible defects by photoluminescence window scanning imaging. The image scanning and processing system includes the following steps:

[0054] Step S300: Receive multiple groups of defect images;

[0055] Step S301: Process the multiple groups of defect images and synthesize a group of window images.

[0056] As Figure 2 、 3 shown, on the one hand, the present invention also provides a device for detecting invisible defects by photoluminescence window scanning imaging, which implements a method for detecting invisible defects by photoluminescence window scanning imaging as described in any one of the above, including:

[0057] A photovoltaic panel, configured to receive and obtain multiple groups of rectangular window light spots that are continuously moving under the control of the image scanning and processing system and are emitted by a near-infrared light excitation source after being processed by an optical processor; and is also configured to irradiate the light-induced photoluminescence windows that are continuously moving with the rectangular window light spots;

[0058] A scanning mechanism (the scanning mechanism is an electric control turntable or an electric control translation stage, or other types of moving platforms), including an electric control translation stage or an electric control turntable, on which a near-infrared light excitation source is installed; configured to drive the near-infrared light excitation source to rotate, move the rectangular window light spot emitted by the near-infrared light excitation source on the photovoltaic panel; and is also configured to receive the scanning instruction of the image scanning and processing system;

[0059] A area array camera, configured to collect defect images of multiple groups of continuously moving photoluminescence windows; and is also configured to send the multiple groups of defect images to the image scanning and processing system;

[0060] An optical processor, including a shaping lens or / and a beam splitting prism, located between the photovoltaic panel and the scanning mechanism and between the photovoltaic panel and the area array camera. The optical processor located between the photovoltaic panel and the scanning mechanism is configured to process the beam emitted by the near-infrared light excitation source into a rectangular window light spot; the optical processor located between the photovoltaic panel and the area array camera is configured to process the defect image elements emitted by the photoluminescence window;

[0061] An image scanning and processing system (the image scanning and processing system is a microcomputer including an input-output interface, such as a USB3.0 interface), which is electrically connected to the scanning mechanism and the area array camera; configured to control the rotation of the scanning mechanism and process multiple groups of defect images to synthesize a group of window images;

[0062] For example, an image scanning and processing system combines a sequence of window images into a complete image of the defects of a photovoltaic panel for further processing.

[0063] A display, electrically connected to the image scanning and processing system, for displaying the synthesized window image.

[0064] In the present invention, a device for detecting invisible defects in a photovoltaic panel by photoluminescence window scanning imaging includes: a photovoltaic panel to be tested, an excitation light source, a area array camera, a scanning mechanism, an image scanning and processing system, etc. The excitation light source is used to emit a rectangular window light spot to irradiate the surface of the photovoltaic panel to induce photoluminescence of the photovoltaic panel and contrast the invisible defects of the photovoltaic panel; the area array camera is used to capture the defect image of the photoluminescence window of the above photovoltaic panel; the scanning mechanism drives the excitation light source to rotate or move so that the window light spot moves on the surface of the photovoltaic panel to form an adjacent photoluminescence window, and then the area array camera captures the defect image of the adjacent photoluminescence window. By repeating the above steps, defect images of the photovoltaic panel of multiple adjacent windows can be captured and form a sequence of window images; the image scanning and processing system is used to control the movement of the scanning mechanism and control the camera to capture images, and then combines the window image sequence into a complete image.

[0065] The photovoltaic panel is a polycrystalline silicon or monocrystalline silicon photovoltaic panel, which generates photoluminescence under the irradiation of a near-infrared light source, and the wavelength range of the fluorescence is mainly distributed in the interval of 1100 - 1200nm;

[0066] The excitation light source is a near-infrared narrow-band light source, such as a laser light source or an LED light source with a wavelength of 850nm;

[0067] The area array camera is a near-infrared or short-wave infrared camera, such as an InGaAs camera or a silicon CCD / CMOS camera;

[0068] The scanning mechanism is an electrically controlled turntable or an electrically controlled translation stage, or other types of electrically controlled moving platforms;

[0069] The image scanning and processing system consists of a microcomputer and its input / output interfaces, such as a USB3.0 interface.

[0070] In some embodiments of the present invention, the near-infrared light excitation light source includes a near-infrared LED light source or a near-infrared laser light source.

[0071] Embodiment 1:

[0072] As Figure 2 shown, the present invention provides a device for detecting invisible defects in a photovoltaic panel by photoluminescence window scanning imaging using an electrically controlled turntable, including:

[0073] A photovoltaic panel to be measured, a near-infrared LED light source, a shaping lens, a planar array InGaAS camera, an electric control turntable, a microcomputer and its USB3.0 peripheral interface, etc. The light beam emitted by the near-infrared LED light source forms a rectangular light spot after passing through the shaping lens and is projected onto the surface of the photovoltaic panel, thereby inducing it to emit fluorescence of a corresponding wavelength and forming a fluorescence window. The spectral energy of this photoluminescence mainly concentrates in the short-wave infrared range with a wavelength of 1050 nm to 1250 nm, as Figure 4 shown. Then, a planar array InGaAS camera is used to capture an image of this fluorescence window. This planar array InGaAS camera has high sensitivity in the wavelength range of 1050 nm to 1250 nm, as Figure 4 shown; driven by the electric control turntable, the window light spot of the LED light source moves on the surface of the photovoltaic panel to form another adjacent photoluminescence window, and then the InGaAS camera is used to capture an image of this adjacent window. By repeating the above steps, defect images of the photovoltaic panel with multiple adjacent windows can be captured and a set of window image sequences can be formed; the microcomputer and its peripheral interface are used to control the movement of the electric control turntable and control the InGaAS camera to capture images, and then the window image sequences are combined into a complete image.

[0074] Embodiment 2:

[0075] As Figure 3 shown, the present invention provides a photoluminescence window scanning imaging hidden defect detection device for a photovoltaic panel using an electric control translation stage, including:

[0076] A photovoltaic panel to be measured, a near-infrared laser light source, a shaping lens, a beam splitting prism, a planar array InGaAS camera, an electric control translation stage, a microcomputer and its USB3.0 peripheral interface, etc. The light beam emitted by the near-infrared laser light source forms a rectangular light spot after passing through the shaping lens and the beam splitting prism and is projected onto the surface of the photovoltaic panel, thereby inducing it to emit fluorescence of a corresponding wavelength and forming a fluorescence window; the image of this fluorescence window is captured by the planar array InGaAS camera after passing through the beam splitting prism; driven by the electric control translation stage, the window light spot of the laser light source moves on the surface of the photovoltaic panel to form another adjacent photoluminescence window, and then the InGaAS camera is used to capture an image of this adjacent window. By repeating the above steps, defect images of the photovoltaic panel with multiple adjacent windows can be captured and a set of window image sequences can be formed; the microcomputer and its USB3.0 peripheral interface are used to control the movement of the translation stage and control the InGaAS camera to capture images, and then the window image sequences are combined into a complete image.

[0077] The photoluminescence imaging of the present invention abandons the link of applying the driving voltage required for electroluminescence imaging, which is beneficial to improving the on-site detection efficiency; realizes the technology of large-area detection of invisible defects of photovoltaic panels; uses a near-infrared light excitation source as the photoexcitation light source, and a light processor is provided between the near-infrared light excitation source and the photovoltaic panel to process the light beam emitted by the laser light source into a rectangular window light spot, reducing the required light source power and realizing practical and suitable long-distance on-site imaging detection.

[0078] In some specific embodiments, such as Figure 5 shown, a photoluminescence window scanning imaging invisible defect detection device includes at least one processor and a memory that stores instructions to implement a photoluminescence window scanning imaging invisible defect detection method according to any one of the above technical solutions.

[0079] In some specific embodiments, a computer-readable storage medium stores a computer program, and the computer program is executed by a processor to implement the method of the steps in the above technical solution.

[0080] In some specific embodiments, a computer program product includes a computer program, and when the computer program is executed by a processor, it implements the method of the steps in the above technical solution.

[0081] The embodiments and functional operations of the subject matter described in this specification can be implemented in: digital electronic circuits, tangibly implemented computer software or firmware, computer hardware, including the structures disclosed in this specification and their structural equivalents, or a combination of one or more of the above. The embodiments of the subject matter described in this specification can be implemented as one or more computer programs, that is, one or more modules of computer program instructions encoded on one or more tangible non-transitory program carriers for being executed by a data processing device or controlling the operation of the data processing device.

[0082] As an alternative or addition, the program instructions can be encoded on an artificially generated propagated signal, for example, a machine-generated electrical signal, optical signal or electromagnetic signal, which is generated as encoded information to be transmitted to an appropriate receiver device for execution by a data processing device. The computer storage medium can be a machine-readable storage device, a machine-readable storage substrate, a random or serial access memory device, or a combination of one or more of the above devices.

[0083] A computer program (which may also be referred to as or described as a program, software, software application, module, software module, script, or code) can be written in any form of programming language, including compiled languages or interpreted languages or declarative or procedural languages, and the computer program can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. A computer program may, but need not, correspond to a file in a file system. The program may be stored in a part of a file that holds other programs or data, for example, stored in one or more scripts in: a markup language document; a single file dedicated to the relevant program; or in multiple cooperating files, for example, files that store one or more modules, subroutines, or portions of code. A computer program may be deployed to execute on one computer or on multiple computers, which are located at one site, or distributed across multiple sites and interconnected by a communication network.

[0084] The content not described in detail in this specification belongs to the prior art well known to those skilled in the art.

[0085] Although the present invention has been described in detail above with general descriptions, specific embodiments, and experiments, on the basis of the present invention, some modifications or improvements can be made to it, which are obvious to those skilled in the art. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of the present invention claimed.

Claims

1. A method for detecting invisible defects by photoluminescent window scanning imaging, characterized in that: The photovoltaic panel end includes the following steps: Acquire multiple groups of near-infrared light excitation light sources that are constantly moving under the control of an image scanning and processing system and emit rectangular window light spots that are processed by a light processor; The shaped window light spot irradiates light and induces the generation of multiple groups of continuously moving photoluminescent luminescent windows.

2. The method for detecting invisible defects by photoluminescent window scanning imaging according to claim 1, characterized in that: The photoluminescent light emitting window is formed by adjacent photoluminescent edge light interfaces.

3. The method for detecting invisible defects by photoluminescent window scanning imaging according to claim 1, characterized in that: The photovoltaic cell panel at the photovoltaic panel end is a monocrystalline silicon photovoltaic cell panel or a polycrystalline silicon photovoltaic cell panel.

4. The method for detecting invisible defects by photoluminescent window scanning imaging according to claim 1, characterized in that: The spectral energy of the photoluminescence in the photoluminescence window is in the short-wave infrared range of 1050nm to 1250nm.

5. A method for detecting invisible defects by photoluminescent window scanning imaging, characterized in that: The area array camera end includes the following steps: Collect multiple groups of defect images of the continuously moving photoluminescent light-emitting windows; Sending a plurality of groups of defect images to an image scanning and processing system.

6. The method for detecting invisible defects by photoluminescent window scanning imaging according to claim 5, characterized in that: The area array camera at the area array camera end is a near-infrared or short-wave infrared camera, including an InGaAs camera or other types of short-wave infrared cameras.

7. A method for detecting invisible defects by photoluminescent window scanning imaging, characterized in that: The image scanning and processing system includes the following steps: receiving a plurality of groups of defect images; The multiple groups of defect images are processed to synthesize a group of window images.

8. A device for detecting invisible defects by scanning imaging of a photoluminescent window, which realizes a method for detecting invisible defects by scanning imaging of a photoluminescent window as claimed in any one of claims 1 to 7, characterized in that: include: Photovoltaic panels are used to receive and acquire multiple groups of rectangular window light spots processed by a light processor and emitted by a near-infrared light source that is constantly moving under the control of an image scanning and processing system; and are also used to induce the generation of multiple groups of constantly moving photoluminescent light windows by the irradiation light of the rectangular window light spots; The scanning mechanism includes an electrically controlled translation stage or an electrically controlled rotation stage, on which a near-infrared light excitation light source is installed; used to drive the near-infrared light excitation light source to rotate, and move the rectangular window light spot emitted by the near-infrared light excitation light source on the photovoltaic cell panel; and also used to receive scanning instructions from an image scanning and processing system; An area array camera is used to collect multiple groups of defect images of the continuously moving photoluminescent light-emitting windows; and is also used to send the multiple groups of defect images to an image scanning and processing system; A light processor, including a shaping lens and / or a beam splitting prism, is located between the photovoltaic panel and the scanning mechanism and between the photovoltaic panel and the area array camera. The light processor located between the photovoltaic panel and the scanning mechanism is used to process the light beam emitted by the near-infrared light excitation light source into a rectangular window light spot; the light processor located between the photovoltaic panel and the area array camera is used to process defective image elements emitted by the photoluminescent light emitting window; An image scanning and processing system, which is electrically connected to the scanning mechanism and the area array camera; used to control the rotation of the scanning mechanism and process multiple groups of defect images to synthesize a group of window images; A display is electrically connected to the image scanning and processing system and is used for displaying the synthesized window image.

9. The method for detecting invisible defects by photoluminescent window scanning imaging according to claim 8, characterized in that: The near-infrared light excitation light source includes a near-infrared LED light source or a near-infrared laser light source.

10. A device for detecting invisible defects by scanning imaging of a photoluminescent window, the device comprising at least one processor and a memory storing instructions, characterized in that: When the instruction is executed by at least one processor, a photoluminescent window scanning imaging invisible defect detection method as described in any one of claims 1 to 4 is implemented.

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