JP4488910B2 - Surface inspection method and surface inspection apparatus - Google Patents

Description

  The present invention relates to a surface inspection method for a substrate having a coating layer coated on the surface.

  Conventionally, such as a rust-preventing plating layer applied to the metal surface, a gloss maintaining resin layer applied to the plate surface, or an oxygen-blocking thin film applied to a resin molded product such as plastic, A technique for forming a base material in which a very thin film layer is coated on the surface of the base body is used in various fields.

For example, a coating layer applied to a resin molded product such as a PET bottle is one in which Si, SiO, SiO ₂ or the like is deposited on the surface of the resin molded product by a method such as plasma CVD, and usually has a thickness of several tens of nm to several It is formed in a thin film of μm order (for example, Patent Document 1).

  However, since such a film layer has a transparent property in addition to an extremely small film thickness, it is very difficult to easily determine whether or not the film layer is coated over the whole.

  Of course, using a large-scale analyzer, microscope, etc., and if it takes a long time, the inspection would be possible, but if all the inspections were performed with mass-produced products such as PET bottles, it would take too much time, Such a method cannot be adopted because it is difficult to inspect a complicated shape or a large shape.

  Further, as long as it is limited to a colored coating layer, there is a measurement method in which the coating layer is inspected based on the color density of reflected light (for example, Patent Document 2), but it is fatal that the inspection cannot be performed if the coating layer is colorless and transparent. Have some disadvantages.

For these reasons, a surface inspection method that can easily and quickly discriminate the presence or absence of a coating layer has been eagerly desired.
JP 2004-137419 A JP 2003-4648 A

  Therefore, the present invention completely breaks away from the idea of detecting the coating layer itself as in the past, and when a test solution such as water is attached to the surface of the substrate, the portion where the coating layer is formed and the substrate body It was made for the first time by paying attention to the fact that the test solution adheres differently from the exposed part of the substrate, and the coating layer is formed on the entire surface of the substrate in the substrate coated with the coating layer on the surface. The main objective of the present invention is to provide a surface inspection method that can easily and accurately discriminate what is being done.

That is, in the surface inspection method according to the present invention, the inspection liquid adhesion step of attaching the inspection liquid to the predetermined inspection area of the rising surface of the PET bottle composed of the base body and the transparent film layer formed on the surface thereof, and the inspection liquid adhered A light irradiation step of irradiating the inspection region with light close to parallel light from a low angle inclined in a vertical direction with respect to the standing surface, and an imaging surface is configured to calculate the amount of reflected light generated when the inspection region is irradiated with light. A light amount detection step of detecting by a light detection device arranged opposite to the standing surface, and a determination step of determining the presence or absence of a coating layer in the inspection region based on the light amount of the reflected light. It is characterized by being.

If this is the case, the coating layer is formed even when the substrate body and the coating layer are both colorless and transparent and it is difficult to detect the presence or absence of the coating layer, such as a container of a PET bottle. By adhering the inspection liquid onto the surface of the base material on the side where the light is applied, the light of the light due to the difference in the state of attachment of the inspection liquid between the part where the coating layer is not formed and the part where the film layer is formed Since a difference occurs in the degree of scattering, the state of the coating layer can be inspected quickly, simply and accurately only by detecting the intensity of the reflected light of the light irradiated on the substrate. Further, the inspection area is irradiated with light close to parallel light from a low angle inclined in the vertical direction with respect to the standing surface, and the light amount of the reflected light is detected by a light detecting device arranged with the imaging surface facing the standing surface. By detecting, the difference in the degree of scattering can be remarkably shown in the difference in the intensity of the reflected light, and the reliability of the inspection can be further improved. Here, the reflected light is regularly reflected light or irregularly reflected light.

  Further, in order to uniformly apply the test liquid over the entire inspection region by a simple method and improve the reliability of the test, in the atmosphere in which the test liquid is vaporized in the test liquid attaching step, A base material maintained at a temperature lower than the atmosphere may be brought into contact, and the test solution may be attached to the test region using the condensation phenomenon at that time. By using such a method, even when the shape of the base material is complicated such as a container shape, the test solution can be easily attached to the surface (inner surface).

  As an example of the other test liquid attaching process, for example, in the test liquid attaching process, a sprayed test liquid may be sprayed and attached to the test area.

  If water is used for the test solution, water is extremely easy to obtain and inexpensive, so that in the case of a product in which the base material is mass-produced, the surface inspection of the base material can be performed at low cost. The effect can be obtained. In addition, since moisture contained in the atmosphere can be used, facilities for storing and managing the test solution are not required, and the inspection can be performed with simple facilities. The water here does not need to be pure water in a strict sense, and may be water having a certain degree of purity that is used for industrial and household purposes.

As an example of a specific base material that can obtain a remarkable effect by applying the present invention, the base material body permeates at least one of oxygen and carbon dioxide, and the coating layer passes through the base material. A material composed of a material that does not permeate the permeating gas, for example, a resin molded product such as PET in which the base body is permeable to oxygen or carbon dioxide, and a coating layer is composed of, for example, Si, SiO, SiO ₂ or the like You can list what you have.

  Further, such a base material may constitute a food container. In this case, for example, by using a harmless liquid such as water for inspection, it is not necessary to perform special cleaning etc. after the inspection even for a substrate such as a food container that needs to be extremely hygienic. The inspection can be done more easily and quickly. In addition, as an example of such a food container, a plastic tray with a coating applied to the surface, a plastic case for containing food, a plastic bottle for drinking water, a resin film for food packaging, a plastic product And paper tableware.

As an apparatus that embodies the surface inspection method according to the present invention, an inspection liquid adhesion apparatus that adheres an inspection liquid to a predetermined inspection area of an upright surface of a PET bottle composed of a base body and a transparent film layer formed on the surface of the base body, A light irradiation device that irradiates light close to parallel light from a low angle inclined in a vertical direction with respect to the standing surface, and an imaging surface are disposed in the inspection region so as to face the rising surface, and light is emitted to the inspection region. A light amount detection device that detects a light amount of reflected light generated by irradiation, transmits a light amount signal indicating the detected light amount, receives the light amount signal, and determines the presence or absence of a coating layer based on a value indicated by the light amount signal A device having an information processing device can be given.

  As a more specific embodiment of the information processing device, the information processing device receives the light amount signal and stores the value in a light amount signal storage unit set in a predetermined area of the memory; A determination unit that reads a value of the light amount signal stored in the light amount signal storage unit and determines whether the value has a predetermined difference or more compared to a reference value; When it is determined that it has, an output unit that outputs that there is at least a portion having no coating layer in the inspection region is conceivable.

  In order to facilitate visual confirmation by an operator, it is preferable that the light amount detection device transmits a light amount signal indicating the amount of reflected or transmitted light at each part of the inspection area as image data.

In order to facilitate the adhesion of the test solution and to prevent the surrounding stray light from entering as much as possible when detecting reflected light or transmitted light, the test chamber is further provided with a substantially sealable test chamber, which is transported to the inside of the test chamber. The inspection member is attached to the inspection region and irradiated with light on the substrate, and the wall member forming the inspection chamber transmits reflected or transmitted light from the inspection region to the outside. What has a window part for derivation | leading-out and detects the light quantity of the derived | led-out reflected or transmitted light with the said light quantity detection apparatus is preferable.

  As described above, according to the surface inspection method according to the present invention, whether or not the coating layer is formed on the entire surface of the base material is easily and accurately determined in the base material coated with the transparent coating layer on the surface. It becomes possible to discriminate.

  Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.

  The surface inspection apparatus 1 according to the present embodiment inspects, for example, whether or not the surface film layer 14 of the PET bottle 10 is correctly formed, and eliminates defective products in which a part of the film layer 14 is missing. Used.

First, the structure of the plastic bottle 10 will be described. As shown in FIG. 1, the plastic bottle 10 has a hollow body 11 with a lid (not shown) as is well known. The body 11 is composed of a thin transparent base material 12, and the base material 12 has a base material body 13 made of PET and a base material body as shown in FIG. 2 (a). 13 and a coating layer 14 that coats the inner surface (inner surface). The coating layer 14 is very thin with a thickness of the order of several tens of nm to several μm, and is made of Si, SiO, SiO ₂ or the like. The coating layer 14 is made of a material that does not allow oxygen and carbon dioxide to pass through, and supplements the fact that PET has the property of allowing oxygen and carbon dioxide to pass through. It plays a role in preventing drinking water and juices from being altered by oxidation. By the way, as shown to the same figure (b), in the case of the poor film | membrane state in which the film | membrane layer 14 is not partially formed, the base-material main body 11a is exposed to an inner surface, oxygen, carbon dioxide, etc. which are contained in external air Is conducted to the inside of the PET bottle 10 through the base body 11a, and it becomes necessary to exclude the PET bottle 10 as a defective product.

  As shown schematically in FIG. 1, the surface inspection apparatus 1 includes a transport device 20 that transports the plastic bottle 10, and a position detection sensor 21 that detects that the plastic bottle 10 has been transported to a predetermined position. A test liquid adhering device 30 for adhering water as a test liquid to the inside of the PET bottle 10 transported to the predetermined position, and a light irradiation device 40 for irradiating the predetermined inspection area of the PET bottle 10 with visible light L; A light amount detection device 50 that mainly detects the light amount of irregularly reflected light generated when the inspection area is irradiated with the light L, and an information processing device 60 that controls these devices, collects information, and the like are provided.

  The conveyance device 20 uses, for example, a belt conveyer or the like, and is configured to convey one after another in a direction orthogonal to the paper surface of FIG.

  The position detection sensor 21 uses a non-contact type sensor such as an ultrasonic sensor or an optical sensor. As will be described in detail later, a test solution for injecting water (hot water), which is a test solution, into the PET bottle 10. A first position detection signal for detecting the arrival of the PET bottle 10 at the injection position and then the surface inspection position where the surface inspection is performed by irradiating the PET bottle 10 with light. And a second position detection signal are output.

  The test liquid attaching device 30 is not illustrated in detail, but for example, a tank for storing high-temperature (for example, 80 ° C. to 100 ° C.) water that is a test liquid, and a nozzle connected to the tank via a pipe And a valve for opening and closing the nozzle, and a certain amount of water made into a high-temperature liquid state from the nozzle is injected into the PET bottle 10 that has come to the test solution injection position, and steam is generated in the PET bottle 10. Is generated and water is uniformly attached to the inner surface.

  Although the illustration of the light irradiation device 40 is omitted for details, the light irradiation device 40 includes, for example, a wiring board, LEDs arranged in one to several rows in a straight line on the wiring board, and a casing for holding them, and the surface It arrange | positions so that the light L close | similar to parallel light may be irradiated with the angle of about 45 degree | times with respect to the test | inspection area | region 10a (here the standing surface of a PET bottle) of the PET bottle 10 in a test | inspection position.

  The light detection device 50 includes an area image sensor such as a CCD camera, for example, and is arranged with its imaging surface facing the upright surface. And the light quantity from each part of the test | inspection area | region 10a of the plastic bottle 10 irradiated with the light L is detected, and the light quantity signal which shows those values is each output. Here, these light quantity signals are transmitted in an image data format to the information processing apparatus 60 described later.

  As shown in FIG. 3, the information processing apparatus 60 is a general-purpose or dedicated computer including a CPU 60a, a memory 60b, a display 60e, an input means (mouse or keyboard) 60c, a communication interface 60d, and the like. As shown in FIG. 4, the CPU 60 a and its peripheral devices operate in cooperation with each other according to the program stored in the memory 60 b, and as shown in FIG. It functions as a control unit 63 that controls the device 30 and the like, and a determination unit 64 that determines whether or not the value of the received light amount signal is more than a predetermined value compared to the reference value.

  Next, the process of detecting the presence or absence of the coating layer 14 of the PET bottle 10 using the surface inspection apparatus 1 having such a configuration will be described below.

  The PET bottle 10 is transported one after another by the transport device 20 in a state where the lid is not attached, and all are inspected in the same manner. Here, a description will be given focusing on one PET bottle 10.

  When the PET bottle 10 reaches the test liquid injection position, the position detection sensor 21 detects this (step S1), and transmits a first position detection signal to notify that.

  When the receiving unit 62 of the information processing device 60 receives this, a test solution injection signal is issued from the control unit 63 to the test solution attaching device 30.

  When the test liquid injection device 30 receives this test liquid injection signal, the valve is opened for a predetermined time, and a predetermined amount of water (hot water) is injected into the PET bottle 10 from the nozzle. As a result, steam (vaporized water W) is generated, and during a certain period of time until it is transported to the surface inspection position, the steam touches the inner surface of the PET bottle 10 to condense and uniformly diffuse to the PET bottle. Water adheres over the entire inner surface of step 10 (step S2).

  The adhesion mode at this time is shown in FIG. FIG. 2A shows the case of a good coating layer 14, and the condensed water W forms a uniform thin layer and spreads on the surface of the substrate. FIG. 2B shows a defective product in which a part of the coating layer 14 is missing. The water W forms a uniform thin layer on the coating layer 14, but does not spread sufficiently on the substrate body 11a, and adheres as fine water droplets due to its surface tension. Thus, it is thought that the difference of the adhesion aspect of water W is influenced by the difference in the raw material of the membrane | film | coat layer 14 and the base-material main body 13, and the delicate difference in surface roughness.

  Next, when the plastic bottle 10 comes to the surface inspection position, the position detection sensor 21 detects it (step S3), and transmits a second position detection signal to notify that. The second position detection signal is received by the reception unit 62 of the information processing device 60, and the light amount signal transmitted from the light detection device 50 at that time is stored in the light amount signal storage unit 61 set in a predetermined area of the memory 60b. Latch (step S4).

  FIG. 6 shows the state of the plastic bottle 10 at the surface inspection position. At this position, the plastic bottle 10 is irradiated with light L from the light irradiation device 40. As shown in FIG. 5A, if the coating layer 14 is formed correctly, the water W adheres to the surface of the base material 12 in a layered form, so that the surface of the base material 12 has a low angle. The light L irradiated at an incident angle of about 45 degrees is regularly reflected or transmitted symmetrically without being irregularly reflected. Accordingly, almost no reflected light is generated in the direction perpendicular to the surface of the substrate W, that is, in the direction of the light detection device 50. On the other hand, as shown in FIG. 5B, when a missing portion where the coating layer 14 is not formed is present in the inspection region 10a, the water W is dropped and dispersed at the missing portion. Therefore, irregular reflection occurs, and reflected light toward the light detection device 50 is generated. Therefore, when the value of the latched light amount signal is higher than the reference value by a predetermined value or more, irregular reflection has occurred, so it can be determined that there is an abnormality in the coating layer 14, and otherwise it is normal.

  That is, next, the determination unit 64 obtains a light amount signal from the light amount signal storage unit 61, and compares the value of each light amount signal with a preset reference value (step S5). Then, it is determined whether or not the value of the light amount signal is a predetermined distance or more compared to the reference value (step S6). For example, when the value is higher than the predetermined value, there is an abnormality in the coating layer 14, and otherwise it is normal. Discrimination result data indicating the value is generated (steps S7 and S8).

  If the determination result data includes abnormality data, the output unit 65 having the display 60e displays on the display 60e that the coating layer 14 is abnormal. A message indicating the absence is displayed on the display 60e (step S8). Further, for example, the determination result data is output to the display 60e as binarized image data, and only the location of the abnormal part is displayed in a different color (for example, the surrounding area is black and only the part is white). Also good.

  Thereafter, if there is a plastic bottle 10 to be conveyed next, the process returns to step S1 again to inspect the plastic bottle 10. Note that the plastic bottle 10 determined to be abnormal is discarded separately.

  As described above, according to the above embodiment, the coating layer 14 formed inside the PET bottle 10 is not detected, but between the portion where the coating layer 14 is not formed and the portion where the coating layer 14 is formed. Is detected from the degree of scattering when the irradiated light L is reflected or transmitted by water (test solution), so that the coating layer 14 is colorless and transparent and has a very small thickness. The state can be easily and accurately inspected.

  Moreover, since water is used as the inspection liquid, even if it is attached to the coating layer 14 inside the PET bottle used for beverages, it is difficult for hygiene problems to occur, and it is not necessary to perform cleaning or the like after the inspection.

  The present invention is not limited to the above embodiment.

  For example, visual inspection may be performed without using the light amount detection device. If it is the case of the said embodiment, when it visually observes, the missing part of a membrane | film | coat layer will look bright compared with another site | part. Also, hot water may be injected manually. In this way, the device can be made very simple.

  Furthermore, the light amount detection signal itself (captured image) detected by the photodetection device may be displayed on the display as it is as a captured image. By doing so, the inspector can more clearly know the state of the PET bottle to be inspected.

  Moreover, the method of judging the quality of the film layer formed in the base body is not limited to the method performed by comparison with a reference value stored in advance. For example, after 100% inspection, the average value may be obtained, and the quality of the coating layer may be determined using the average value as a reference value. In this way, the quality of the coating layer can be determined based on the amount of light obtained under the same inspection conditions, so that the inspection conditions such as temperature and humidity can be compared with the case where a predetermined reference value is used. There is an effect that it becomes difficult to be affected.

  In addition, the surface inspection apparatus may be provided with a substantially sealed inspection room, and the inspection may be performed inside the inspection room. In this way, noise due to stray light from the outside can be cut, and the room Since it is possible to reliably adhere water and the like while maintaining a constant environment, it is possible to perform inspection with high accuracy and certainty.

  An example of the inspection room is shown in FIG. In the figure, elements corresponding to those of the embodiment are given the same reference numerals. This inspection room 100 is formed with a wall 110 coated with black or the like whose inner surface does not reflect light, and forms a substantially sealed space. A part of the wall 110 is provided with an inlet / outlet (not shown) for carrying in and out of the plastic bottle, and a window 110a is provided, and the light detection device 50 is installed outside the window 110a.

  In addition, the inspection liquid adhering device was maintained at a temperature outside the air from an air source (not shown) in the inside of the cooled PET bottle 10 and the cooler 120 that cools the inspection chamber in order to cool the plastic bottle that was carried in. The air supply unit 130 supplies a predetermined amount of air. Even in such a configuration, water as a test solution can be adhered to the inner surface of the PET bottle by condensation. About others, it is the same as that of the said embodiment.

  In the illustrated example, the air supplied from the air supply unit 130 is preferably air containing a large amount of water vapor, that is, high humidity, although it depends on the degree of cooling of the PET bottle 10 by the cooling unit 120. As a result, water can be reliably condensed (condensed) inside the PET bottle 10.

  In addition, for example, the inspection object is not limited to what constitutes a PET bottle, but a member formed of a base material composed of a base body provided with a coating layer, for example, a plating layer for rust prevention is formed. It may be a metal product, a plate material with a glossy resin layer formed on the surface, a glass material with an antireflection film, etc., and the test solution is not limited to water Depending on the type and properties of the coating layer contained in the substrate, it can be appropriately selected. In particular, when the inspection liquid is adhered to the base material body and the coating layer, the present invention can be applied if the adhesion mode differs depending on the surface tension or the like and the light scattering mode changes significantly.

  In addition, the test liquid adhesion device is not limited to the one that adheres the test liquid to the surface of the base material by condensing using the difference between the base material and the ambient temperature. It may be one that is sprayed directly on.

  Moreover, although LED is used in the said embodiment as a light irradiation apparatus, another light source, ie, a fluorescent lamp, an incandescent lamp, a laser light source, etc. can also be used. In addition, the wavelength of the light irradiated from such a light irradiation part is not specifically limited, Light other than visible region may be sufficient.

  In addition, the above-described light detection device is not limited to be installed so as to detect light irregularly reflected in the inspection region (in the vertical direction in the embodiment). For example, you may install so that the light reflected regularly and the light which permeate | transmitted the base material may be detected. In this case, since the amount of light in the scattered portion is reduced, in the case where water is attached to the PET bottle as in the above embodiment, it is not determined that the amount of light is larger than a predetermined value, but it is not abnormal. If it is small, it is judged as abnormal.

  In addition, it is needless to say that the present invention can be appropriately combined with some of the illustrated examples and explanations described above, and is not limited thereto, and various modifications can be made without departing from the spirit of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS Schematic which shows schematically the whole surface inspection apparatus in one Embodiment of this invention. The A section enlarged partial sectional view in FIG. The fragmentary sectional view which shows the aspect at the time of water adhering to the inner surface of the PET bottle in the embodiment. FIG. 2 is a schematic structural diagram of the information processing apparatus in the embodiment. The functional block diagram of the information processing apparatus in the embodiment. The fragmentary sectional view which shows a mode at the time of irradiating light in FIG. The flowchart which shows the surface inspection method in the embodiment. Schematic which shows schematically the surface inspection apparatus which concerns on other embodiment of this invention.

DESCRIPTION OF SYMBOLS 1 ... Surface inspection apparatus 10 ... PET bottle 12 ... Base material 13 ... Base material main body 14 ... Film | membrane layer 20 ... Conveyance apparatus 21 ... Position detection sensor 30 ... Inspection Liquid adhering device 40 ... Light irradiation device 50 ... Light detecting device 60 ... Information processing device 100 ... Inspection chamber 110 ... Wall 110a ... Window W ... Water

Claims (12)

A test liquid attaching step of attaching a test liquid to a predetermined test region of a rising surface of a PET bottle composed of a base material body and a transparent film layer formed on the surface thereof;
A light irradiation step of irradiating light close to parallel light from a low angle inclined in the vertical direction with respect to the standing surface on the inspection region to which the inspection liquid is attached,
A light amount detection step of detecting a light amount of reflected light generated by irradiating the inspection region with light by a light detection device in which an imaging surface is arranged to face the upright surface;
And a discrimination step of discriminating the presence or absence of a coating layer in the inspection region based on the amount of the reflected light.   In the test liquid attaching step, a base material maintained at a temperature lower than the atmosphere is brought into contact with the atmosphere in which the test liquid is vaporized, and the test liquid is attached to the test area using the condensation phenomenon at that time. The surface inspection method according to claim 1, wherein:   The surface inspection method according to claim 1, wherein, in the inspection liquid adhesion step, the atomized inspection liquid is sprayed and adhered to the inspection area.   The surface inspection method according to claim 1, wherein the inspection liquid is water.   The said base material main body permeate | transmits the gas of at least any one of oxygen or a carbon dioxide, The said membrane | film | coat layer is comprised from the material which does not permeate | transmit the gas which permeate | transmits the said base material main body. The surface inspection method as described.   The surface inspection method according to claim 1, wherein the base body is made of resin.   The surface inspection method according to claim 1, wherein the base body is made of PET.   The surface inspection method according to claim 1, wherein the base material constitutes a food container. A test liquid adhesion device for adhering a test liquid to a predetermined inspection region of an upright surface of a PET bottle composed of a base material body and a transparent film layer formed on the surface thereof;
A light irradiation device for irradiating the inspection region with light close to parallel light from a low angle inclined in a vertical direction with respect to the standing surface;
A light amount detection device that is disposed so that an imaging surface faces the upright surface, detects a light amount of reflected light generated by irradiating the inspection region with light, and transmits a light amount signal indicating the detected light amount;
A surface inspection apparatus comprising: an information processing apparatus that receives the light amount signal and determines the presence or absence of a coating layer based on a value indicated by the light amount signal. The information processing apparatus is
A light amount signal receiving unit that receives the light amount signal and stores the value in a light amount signal storage unit set in a predetermined area of the memory;
A determination unit that reads the value of the light amount signal stored in the light amount signal storage unit and determines whether the value has a predetermined difference or more compared to a reference value;
10. The surface inspection apparatus according to claim 9, further comprising: an output unit configured to output that a portion having no coating layer exists in the inspection region when the determination unit determines that the difference is greater than or equal to a predetermined value. .   The surface inspection apparatus according to claim 10, wherein the light amount detection device transmits a light amount signal indicating a light amount value of reflected light at each part of the inspection region as image data. Further comprising an inspection room, for the base material transported to the inside of the inspection room, the inspection liquid is attached to the inspection area and irradiated with light, on the wall forming the inspection room, The surface inspection apparatus according to any one of claims 9 to 11, further comprising a window portion for guiding reflected light from the inspection region to the outside.