JP2018031716A - Defect inspection device and defect inspection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a defect inspection device and a defect inspection method that can stably perform defect inspection for a long time by suppressing a variation of brightness of an image in which refractive index distribution of heating gas to an atmosphere within an observation space is visualized.SOLUTION: A device that, when an inspection object has a defect, detects a defect of an inspection object by visualizing refractive index distribution of heating gas 14 pushed out from a heating nozzle 53 into an observation space 70 to an atmosphere within the observation space 70, comprises a windbreak member 60 that surrounds the observation space 70, a knife edge 55 that constitutes a schlieren optical system 5 and is position-adjustable according to brightness of the refractive index distribution, and a partition wall 61 that partitions an ascending current passage 71 and a descending current passage 72 communicating each other such that the atmosphere within the observation space 70 can convect, and an opening 53a of a heating nozzle 53 is disposed in the ascending current passage 71, and further, a cooling head 62 is provided on a top part of the descending current passage 72.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a defect inspection apparatus and a defect inspection method, and more specifically, a defect inspection apparatus and a defect inspection method for detecting a defect in an inspection object by visualizing a refractive index distribution in an observation space by a Schlieren method or the like. About.

  Conventionally, defect inspection has been performed in order to detect defects such as pinholes and cracks in an inspection object such as a container. According to the sealed container defect inspection method described in Patent Document 1 below, the inside of the chamber containing the inspection object of the sealed container is sucked under reduced pressure, and gas is ejected into the observation space from a defective portion such as a pinhole, The sealed container is inspected by visualizing the squirting airflow by the Schlieren method or the like.

JP-A 63-273031

  By the way, in the method described in Patent Document 1, when a defect such as a pinhole is located in a portion that is behind the object to be inspected, it is difficult to detect the ejected airflow. In addition, even when the jet stream is weak, it is difficult to observe the jet stream because the density difference between the jet stream and the atmosphere in the observation space is small. In addition, since the ejected air flow is visualized through the chamber, there is a concern of detection failure due to the influence of dirt, distortion, refraction, and the like of the chamber.

  Therefore, for example, if the heated gas is pushed out from the nozzle into the observation space by the gas leaked from the defective part of the object to be inspected, the defect can be detected regardless of the defective part. Due to the density difference from the gas in the space, it is possible to detect defects even when the jet airflow is weak.

  However, if the heated gas is pushed out of the nozzle into the observation space, the extruded heated gas is easily affected by the wind, and the heated gas is diffused by the wind. As a result, the heated gas is refracted with respect to the atmosphere in the observation space. The brightness of the image that visualizes the rate distribution fluctuates, making it difficult to perform defect inspection stably for a long time.

  The present invention has been made in view of the above circumstances, and suppresses fluctuations in the brightness of an image obtained by visualizing the refractive index distribution of a heated gas with respect to the atmosphere in an observation space, so that defect inspection can be performed stably for a long time. An object of the present invention is to provide a defect inspection apparatus and a defect inspection method that can be performed.

  In order to achieve the above object, the defect inspection apparatus of the present invention is configured to heat the atmosphere in the observation space of the heated gas pushed out from the nozzle into the observation space covered by the windbreak member when the inspection object has a defect. A defect inspection apparatus for detecting a defect of an inspection object by visualizing a refractive index distribution of a gas by a visualization optical system, the visualization optical system having two optical members constituting a parallel light beam section, The inspection apparatus includes a windproof member surrounding the observation space together with two optical members, and the windproof member is arranged along a parallel light beam passing through the observation space in a parallel light beam section.

  According to the defect inspection apparatus of the present invention, the observation space is formed by the two optical members constituting the parallel light beam section of the visualization optical system and the windbreak member arranged along the parallel light beam passing through the observation space in the parallel light beam section. It surrounds the observation space while preventing the passing parallel light flux from crossing the windbreak member. Thus, the windproof member does not affect the parallel light flux passing through the observation space, and the heated gas can be prevented from being diffused by the wind, and the defect inspection can be performed stably for a long time.

  By the way, when the observation space is surrounded by the windproof member, the atmospheric temperature in the observation space gradually rises due to the heated gas pushed out from the nozzle or the heat radiation from the heated nozzle. As a result, since the temperature difference between the gas emitted from the nozzle and the atmosphere in the observation space is reduced, the density difference between the two is reduced. For this reason, as the atmospheric temperature in the observation space increases, it may be difficult to visualize the refractive index distribution of the heated gas with respect to the atmosphere in the observation space. In addition, if the observation space is ventilated or cooled to lower the atmospheric temperature in the observation space, turbulence will occur in the observation space, which becomes noise when visualizing the refractive index distribution of the gas in the observation space. I was sorry.

Therefore, in the present invention, it is preferable to provide a partition wall that separates the ascending air channel and the descending air channel that communicate with each other so that the atmosphere in the observation space can convect, and the nozzle opening is disposed in the ascending air channel.
As a result, a partition wall is provided in the observation space surrounded by the windbreak member, and the atmosphere in the observation space is separated into an updraft and a downdraft so that the opening of the nozzle is located in the updraft. Without causing turbulence in the observation space, the temperature rise of the atmosphere in the observation space can be suppressed and defect inspection can be performed stably for a long time.

  Further, the defect inspection method of the present invention visualizes the refractive index distribution of the heated gas with respect to the atmosphere in the observation space of the heated gas pushed out from the nozzle into the observation space covered with the windproof member when the inspection object has a defect. A defect inspection method for detecting a defect of an inspection object by arranging two optical members constituting a parallel light beam section of a visualization optical system and a parallel light beam passing through an observation space in the parallel light beam section The observation space is surrounded by a windproof member, and the atmosphere in the observation space is locally cooled and convection is generated by locally cooling the atmosphere in the observation space with the nozzle opening positioned in the upward flow. It is said.

According to the defect inspection method of the present invention, the observation space is formed by the two optical members constituting the parallel light beam section of the visualization optical system and the windbreak member arranged along the parallel light beam passing through the observation space in the parallel light beam section. It surrounds the observation space while preventing the passing parallel light flux from crossing the windbreak member. Thus, the windproof member does not affect the parallel light flux passing through the observation space, and the heated gas can be prevented from being diffused by the wind, and the defect inspection can be performed stably for a long time.
In addition, in the observation space surrounded by the windbreak member, the atmosphere in the observation space is separated into the updraft and the downdraft so that the nozzle opening is located in the updraft. In this way, it is possible to suppress the temperature rise of the atmosphere in the observation space without generating turbulent flow and to perform defect inspection stably for a long time.

  According to the defect inspection apparatus and the defect inspection method of the present invention, it is possible to stably perform defect inspection for a long time by suppressing fluctuations in the brightness of an image obtained by visualizing the refractive index distribution of the heated gas with respect to the atmosphere in the observation space. Can do.

It is the schematic of the defect inspection apparatus which concerns on embodiment of this invention. It is a cross-sectional schematic diagram of the observation space of the defect inspection apparatus which concerns on embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a schematic diagram of a defect inspection apparatus according to the present embodiment. In the defect inspection apparatus 1 shown in the figure, the inspection gas 11 is supplied into the inspection object 10 of the packaging bag by the gas inspection means 2, and the inspection object 10 is at a positive pressure. The inspection object 10 is stored in the chamber 3, and if the inspection object 10 has a defect such as a pinhole, the gas 12 leaks into the chamber 3 from the defective portion. Then, due to the leakage of the gas 12 into the chamber 3, the gas 13 is pushed out into the heating means 4 communicating with the chamber 3, and the heated gas 14 is pushed out from the nozzle 53 communicating with the heating means 4 into the observation space 70. It is. And the defect of the to-be-inspected object 10 is detected by visualizing the heating gas 14 extruded from the nozzle 53 in the observation space 70 with a visualization optical system.

  In the present embodiment, the refractive index distribution of the heated gas 14 with respect to the atmosphere in the observation space 70 is visualized using the Schlieren optical system 5 as the visualization optical system. The schlieren optical system 5 includes a point light source 51, a collimator lens 52 that converts a light beam emitted from the point light source 51 into a parallel light beam, a focus lens 54 that focuses the parallel light beam, and a knife edge 55 that is disposed at the focus of the focus lens 54. And an imaging unit 56 that captures a schlieren image, a calculation unit 57 that detects a defect based on the schlieren image captured by the imaging unit 56, and an actuator 58 that adjusts the position of the knife edge 55. The calculation unit 57 performs image analysis on the captured Schlieren image, and determines the inspection object 10 as a defective product when the heated gas 14 pushed out from the nozzle 53 is detected.

The observation space 70 is surrounded by a windproof member 60 made of an acrylic plate together with a collimator lens 52 and a focus lens 54 that form a parallel light beam section of the Schlieren optical system. The windproof member 70 is disposed along a parallel light beam that passes through the observation space in the parallel light beam section. That is, the acrylic plate is arranged so as to extend in parallel with the parallel light flux. Thus, since the windproof member 60 is arranged so as not to intersect the parallel light flux passing through the observation space 70 and surrounds the observation space, the windproof member 60 is affected by dirt, distortion, and refraction in the observation space 70. It is possible to prevent the heated gas from being diffused by the wind without giving it to the passing parallel light flux.
The windproof member 60 may be disposed within the parallel light flux or may be disposed outside the parallel light flux.

  In this embodiment, the knife edge 55 is arranged with the cutting edge facing upward, and is moved up and down by the actuator 58. By changing the position of the knife edge 55, the amount of light beam shielded by the knife edge 55 at the focal point is adjusted. When the shielding amount by the knife edge 55 is large, the schlieren image becomes dark, and when the shielding amount is small, the schlieren image becomes bright.

  By the way, during the inspection for a long time, a temperature difference is generated between the upper part and the lower part of the observation space 70 due to heat radiation from the heated gas 14 and the nozzle 53. As a result, the parallel light flux in the observation space 70 is slightly refracted downward, and the focal position tends to move slightly downward. For this reason, if the position of the knife edge 55 is not fixed yet, the light shielding amount by the knife edge 55 gradually increases, and the Schlieren image tends to become dark. For this reason, it is necessary to adjust the position of the knife edge 55 to maintain the light shielding amount by the knife edge 55 at an optimum amount.

  Therefore, in the present embodiment, the computing unit 57 detects the brightness of the schlieren image captured by the imaging unit 56. The computing unit 57 controls the actuator 58 to adjust the position of the knife edge 55 so that the detected brightness becomes a predetermined brightness. Thereby, even when the focal position moves in the vertical direction, the position of the knife edge 55 is automatically adjusted in the vertical direction, which can contribute to the realization of a stable defect inspection over a long period of time.

  FIG. 2 is a schematic sectional view of the observation space 70 taken along the line AA in FIG. The observation space 70 includes a partition wall (partition) 61 that is surrounded by the windproof member 60 and separates the ascending air channel 71 and the descending air channel 72. The partition wall 61 has a cylindrical shape having an axis parallel to the parallel light flux, and openings 61 a and 61 b are formed at the upper end portion and the lower end portion of the partition wall 61. Via the openings 61a and 61b, the rising air channel 71 inside the partition wall 61 communicates with the descending air channel 72 outside the partition wall 61, and the atmosphere in the observation space 70 is convected.

  An ascending air flow path 71 inside the partition wall 61 is provided with an opening 53 a at the tip of the nozzle 53. In addition, in order to suppress the heat radiation from the nozzle 53, the nozzle 53 is covered with a heat insulating material.

  A cooling means 62 is disposed on the lower air flow path 72 outside the partition wall 61. The cooling means 62 can be composed of, for example, a Peltier element. The cooling means 62 locally cools the atmosphere of the descending air flow path 72 in the observation space 70 to generate a descending airflow, and the atmosphere in the observation space 70 is convected. At this time, since the cooling means 62 locally cools the atmosphere of the descending air flow path 72, no turbulent flow is generated in the observation space 70, particularly in the vicinity of the opening 53a of the nozzle 53.

  The heated gas 14 pushed out from the opening 53a of the nozzle 53 into the observation space 70 has a refractive index lower than that of the atmosphere because it is higher in temperature than the atmosphere of the observation space 70. For this reason, since the refractive index difference between the heated gas 14 and the atmosphere is large, the refractive index distribution is easily visualized.

  Since the opening 53a of the nozzle 53 is disposed in the ascending air passage 71, the atmosphere cooled by the cooling means 62 in the descending air passage 72 is convected from below in the vicinity of the opening 53a. For this reason, the temperature rise of the atmosphere in the vicinity of the opening 53 of the nozzle 53 is suppressed, and the defect inspection can be performed stably for a long time.

  Thus, according to the defect inspection apparatus and the defect inspection method of the present embodiment, the atmosphere in the observation space 70 is in the ascending air channel 71 and the descending airflow so that the opening 53a of the nozzle 53 is positioned in the ascending air channel 71. By separating the convection from the path 72 by the partition wall 61, the temperature rise of the atmosphere in the observation space 70 is suppressed without generating turbulent flow in the observation space 70, and the defect inspection is performed stably for a long time. be able to.

  In the present embodiment, the example in which the cooling device 62 is provided has been described, but the cooling device 62 can be omitted. Even in the absence of the cooling device 62, the atmosphere in the descending air flow path 72 is cooled by the windproof member 60 and a descending airflow is generated. Therefore, the atmosphere in the observation space 70 is separated into an ascending airflow and a descending airflow for convection. be able to.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the present invention. For example, in the above-described embodiment, the defect inspection apparatus having a specific configuration has been described. However, in the present invention, the defect apparatus configuration is not limited to this, and heating is performed from the nozzle into the observation space when the inspection object has a defect. What is necessary is just the structure by which gas is extruded.
In the above-described embodiment, the example in which the refractive index distribution of the heated gas with respect to the atmosphere in the observation space is visualized in the schlieren optical system has been described, but in the present invention, the method for visualizing the refractive index distribution is not limited to this, For example, any suitable method such as a shadow graph method or a Mach-Zehnder method can be used.
In the above-described embodiment, the example in which the packaging bag is inspected as the inspection object has been described. However, in the present invention, the inspection object is not limited to the packaging bag, and various containers can be inspected. A partition wall such as a diaphragm or a film can also be used as an object to be inspected.
In the above-described embodiment, the example in which the nozzles are horizontally disposed has been described. However, in the present invention, the nozzles only need to be disposed so as to cross the parallel light flux. For example, the nozzle opening portion faces upward. You may arrange.

DESCRIPTION OF SYMBOLS 1 Defect inspection apparatus 2 Gas supply means 3 Chamber 4 Heating apparatus 5 Schlieren optical system 10 Inspected object (packaging bag)
DESCRIPTION OF SYMBOLS 11 Test | inspection gas 12 Leakage gas 13 Gas in heating means 14 Heating gas 51 Point light source 52 Collimator lens 53 Heating nozzle 53a Opening 54 Focus lens 55 Knife edge 56 Imaging means 57 Calculation means 58 Actuator 60 Windproof member 61 Partition (partition)
62 Cooling means 70 Observation space 71 Upflow passage 72 Downfall passage

Claims (7)

When the inspection object has a defect, the refractive index distribution of the heated gas pushed out from the nozzle into the observation space with respect to the atmosphere in the observation space is visualized by a visualization optical system, thereby detecting the defect of the inspection object. A defect inspection device,
The visualization optical system has two optical members constituting a parallel light beam section,
The defect inspection apparatus includes a windproof member surrounding the observation space together with the two optical members,
The defect inspection apparatus, wherein the windproof member is arranged along a parallel light beam passing through the observation space in the parallel light beam section. A partition that separates the rising air channel and the descending air channel that communicate with each other so that the atmosphere in the observation space can be convected;
The defect inspection apparatus according to claim 1, wherein an opening of the nozzle is disposed in the rising air flow path. The defect inspection apparatus according to claim 1, further comprising a cooling unit at an upper portion of the downflow passage. The defect inspection apparatus according to claim 1, further comprising a temperature adjusting unit that heats or cools the atmosphere in the observation space. The defect inspection apparatus according to claim 1, wherein the visualization optical system is a Schlieren optical system. Brightness detection means for detecting brightness of an image obtained by visualizing the refractive index distribution by the Schlieren optical system;
6. The control unit according to claim 5, further comprising a control unit configured to control a position of a knife edge constituting the Schlieren optical system so that the brightness detected by the detection unit becomes a predetermined brightness. Defect inspection equipment. A defect for detecting a defect in the inspection object by visualizing a refractive index distribution of the heated gas pushed out from the nozzle into the observation space when the inspection object has a defect with respect to the atmosphere in the observation space by a visualization optical system. An inspection method,
Surrounding the observation space by two optical members constituting a parallel light beam section of the visualization optical system, and a windproof member arranged along the parallel light beam passing through the observation space in the parallel light beam section,
A defect inspection method, wherein an atmosphere in the observation space is locally cooled in a state where an opening of the nozzle is positioned in an updraft to generate a downdraft and convection.

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