JP2009162644A - Method and device for inspecting defect in foam roller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for determining defects being present in the surface and the inside of a foam roller by an inspection, and a device therefor. <P>SOLUTION: Light passed through a cylindrical lens 4 from the light source of a projection device is projected to the foam roller 1. Then, reflection light P in the foam roller 1 is picked up by an imaging device 11 and transmission light transmitted the foam roller 1 is reflected by a reflection plate 2 and picked up by the imaging device 11. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a defect detection method and a defect detection apparatus that are performed by irradiating a foam roller member with light.

  As a method for discriminating a defect in the foam roller, there are a manual method and a method using an inspection apparatus. As for the manual method, it is necessary to find minute defects as the accuracy of products increases. For this reason, it is a persevering work that must be concentrated for a long time, which increases the mental burden and doubles fatigue. The visual inspection is a subjective inspection determination by the inspector and depends on the inspector's judgment. Accordingly, in the case where the inspectors are different or extreme, even if the inspectors are the same, the inspection level may change depending on the transition of the inspection time.

  As a method for replacing the inspector, an appearance inspection method using an electronic imaging device using a CCD camera has also been clarified (for example, Patent Document 1).

  Moreover, the inspection apparatus which irradiates light on the foam surface and judges the state of a roller using the reflected light from a roller is proposed (for example, patent document 2).

In the techniques disclosed in these patent documents, when the irradiated light is reflected on the foam surface, and the reflected light has a defect on the foam surface, a reflection change of the light occurs at the defective portion. I use that. That is, the reflected light is photographed by an imaging device, converted into a video signal, and the video signal is signal-processed to detect a defective portion.
JP-A-9-243568 JP 2005-274140 A

However, although the method described in the above-mentioned patent document is an effective means for defects existing on the surface of the product, the light reflected from the surface is reflected against the defects existing inside the product. There was a problem that internal inspection was not possible.

Then, the objective of this invention is providing the defect inspection method and defect inspection apparatus of a foam roller which can solve the said subject. An example of the purpose is to obtain defects present in the surface portion and inside of the foam roller by one inspection.

To achieve the above object, the present invention provides a defect detection method for a foam roller that includes at least a light projecting device and an imaging device, and detects a defect in the foam roller based on an image obtained by the imaging device. ,
The light from the light projecting device is projected onto the foam roller, the reflected light at the foam roller is imaged with the imaging device, and the transmitted light that has passed through the foam roller is reflected with a reflector, An image is picked up by the image pickup device.

  According to the present invention, defects existing in the surface portion and inside of the foam roller can be obtained by one inspection.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  In the present invention, it has been difficult to project the light reflected on the surface of the foam roller and the light transmitted through the foam roller onto one imaging device so that the images of these two lights do not overlap. For example, in a light projecting device that projects light onto a foam roller, it is the arrangement angle of the line light source to be irradiated. In the reflection plate, the reflection light component from the foam roller and the transmitted light component transmitted through the foam roller to be reflected by the reflection plate are arranged at angles that do not overlap. Furthermore, in the imaging device, image processing of the foam roller to be photographed.

  Specifically, the defect inspection of the foam roller can be performed by the apparatus configuration shown in FIGS. 1 and 2. FIG. 1 is a diagram showing a positional relationship between a foam roller, a light projecting device, and reflection antireflection according to the present invention, and FIG. 2 is a schematic configuration diagram of a defect detection device according to an embodiment of the present invention. Hereinafter, the apparatus and method of the present embodiment will be described using reference numerals in the drawings.

  The foam roller 1 to be measured is a roller whose main component is urethane. As a light transmittance characteristic, in the long wavelength region and the visible light region, a sheet having a thickness of 2 [mm] made of similar components has a transmittance of 60 to 90 [%]. However, the sheet does not transmit light suddenly from a short wavelength region, that is, a light source wavelength of 380 [nm] or less, and has a property that the transmittance is 20 [%] or less at 300 [nm] or less. It has been confirmed that the roller shape has similar properties.

  The arrangement position of the light projecting device having the light source 3 needs to be arranged so that light hits the entire foam roller. The line width of the light projecting device needs to be longer than the product width of the foam roller 1. Further, in order to eliminate unevenness in the illuminance of the light, for example, an irradiation part of the light projecting device uses an optical fiber divided and arranged in a line shape. A cylindrical lens 4 is used at the tip of the irradiated portion from the viewpoint of irradiating light with uniform illuminance. This lens is a lens that can be enlarged or reduced in height only in one axial direction of light. By using this lens, it is possible to converge diffused light and irradiate uniform light.

  About the wavelength of the light of a light projection apparatus, it is required to be a wavelength area | region which reflects on the surface of the foam roller 1, and permeate | transmits the inside of the foam roller 1. FIG.

  In this regard, a test was performed using an IR light source that irradiates a visible light region using a halogen light source and a long wavelength region of 1000 [nm] or longer, and a UV light source that irradiates 220 to 320 [nm].

  During the test, it was confirmed that no transmission into the foam roller was performed in the light source wavelength region of 220 to 320 [nm]. As a result, it is necessary to use a light source wavelength of 320 [nm] or more in the wavelength of light from the light source 3.

  The imaging device 11 needs to be disposed at a position where the light reflected from the foam roller 1 and the foam roller 1 are transmitted, the transmitted light is reflected by the reflection plate 2, and the reflected light can be imaged ( FIG. 5). In the present embodiment, a CCD camera is used as the imaging device 11, and the imaging range of the imaging device 11 is installed within the inspection target range of the foam roller 1. Further, due to the relationship between the viewing angle of the imaging device 11 and the resolution of the imaging device 11, when one imaging device 11 cannot capture the entire width direction of the foam roller 1, a plurality of imaging devices 11 are used. You may shoot. In addition, the width | variety of a foam roller means the length of the direction parallel to a roller axis | shaft.

  In this embodiment, the CCD camera used as the imaging device 11 is a color camera for planar imaging in which the pixel arrangement of the camera is a two-dimensional plane. The camera has about 300,000 pixels per image element, and the camera is divided into three elements of a red component (R), a blue component (B), and a green component (G). About 900,000 pixels included in one image each have an analog gradation, and are divided into 256 levels of light. However, a monochrome camera may be used as long as the imaging device can detect defects in the foam roller 1, and the specification is not limited to this.

  As the camera lens 12 used in the imaging device 11, a high-resolution lens that reduces distortion is used. In this embodiment, a lens whose focal length is 25 mm, TV distortion is within −0.1%, and focus and iris diaphragm can be adjusted manually is used. However, the camera lens specification is not limited as long as the imaging device can detect defects in the foam roller 1.

  The focal position of the imaging device 11 is that the reflected light P reflected by the surface of the foam roller 1 in one imaging device 11 and the reflected light Q that is transmitted by the foam roller 1 and reflected by the reflecting plate 2. Need to fall within the same depth of field in the imaging device 11. The depth of field can be adjusted by manually adjusting the focus and the iris diaphragm.

  As for the rotation mechanism of the foam roller 1 as a measurement object, both ends of the cored bar portion 1a that hits the core of the foam roller are received by the two rotating members 15 made of metal, whereby the foam roller 1 is installed in the apparatus. It is gripped with. The foam roller 1 can be rotated by rotating the rotating member 15. The rotating member 15 is fully driven from the viewpoint of rotating the measurement object at a constant speed. Further, the motor driver 18 with an encoder is rotated from the viewpoint of ensuring that the rotation of the measurement object is kept constant.

  The rotation mechanism is a mechanism that starts rotating upon receiving a rotation start signal from the drive control device 19 and stops rotating based on a rotation end signal from the drive control device 19.

  At the time of defect inspection, the foam roller 1 is rotated by the rotation mechanism, so that the imaging device 11 sequentially photographs the inspection target range location of the foam roller 1 and images the entire inspection target range. Image processing is performed from the captured image, and if there is a defect, the image number of the captured image is calculated based on the trigger issued from the drive control device 19, and at the same time the image in the image where the defect is found Calculate the position information inside. By combining these calculation results, approximate position information of the defective portion in the inspection object is obtained. At the same time, the size of the defect, the number of defects in one inspection, and the like are stored and displayed. These are performed by the storage device and the processing device 21.

  The adjustment mechanism of the imaging device 11 is made possible by installing the fine movement stage 13 in each imaging device 11 from the viewpoint of facilitating adjustment of the focal position of the camera. A specific configuration of fine movement stage 13 is shown in FIGS. In these drawings, reference numeral 13a represents a θ-angle fine movement stage, reference numeral 13b represents a Y-axis direction fine movement stage, reference numeral 13c represents an X-direction adjustment stage, reference numeral 13d represents a rotation stage, and reference numeral 13e represents a Z-axis direction fine movement stage. Further, reference numeral 13f denotes a Y-axis direction fine movement stage, and reference numeral 13g denotes an X-axis direction fine movement stage.

  As for the reflection plate 2 described above, the light transmitted from the light source 3 through the cylindrical lens 4 and collected is transmitted through the foam roller 1, the transmitted light is reflected by the reflection plate 2, and the reflected light is imaged. It is necessary to arrange so that 11 can image.

  In the present invention, from the viewpoint of photographing both the reflected light component and the transmitted light component at the same time with one imaging device 11, the angle θ (FIG. 1) formed by the reflector 2 is a light projection having the light source 2 and the cylindrical lens 4. It is necessary to arrange it at 60 degrees or more and 150 degrees or less with respect to the optical axis 6 of the apparatus.

  Regarding the reflectance of the reflecting plate 2, it is necessary that the reflectance of the reflecting plate 2 is 60% or more from the viewpoint of favorably imaging the foam roller 1. When the reflectance is less than 60%, it is confirmed that the imaging device 11 cannot obtain a sufficient amount of light when the shape of the foam roller 1 is grasped and the light transmitted through the foam roller 1 is reflected. Yes. In the present embodiment, the reflector 2 has a reflectance of about 90%. However, the reflectance is not limited to this reflectance because the surface shape and the internal shape of the foam roller 1 can be photographed and the reflectance can be determined.

  In addition, the reflected light P reflected from the surface portion of the foam roller 1 in one image pickup device 11 and the reflected light Q transmitted through the foam roller 1 and reflected by the reflecting plate 2 are reflected by the image pickup device. 11 need to fall within the same depth of field.

  In addition, the reflecting plate 2 may be a surface having a curvature instead of a flat reflecting surface from the viewpoint of capturing more images of the surface shape and internal shape of the foam roller 1 than a flat plate.

  In the captured image, an optimum value is experimentally obtained for the relationship between the arrangement angle of the light projecting device, the light projection output, the arrangement position of the imaging device, the reflectance of the reflector, and the installation angle.

  Next, the flow for inspecting the entire area of the foam roller will be described with reference to FIG. FIG. 6 is a flowchart showing a flow of inspecting the entire foam roller.

  First, power is turned on for both the rotation mechanism and the inspection unit. In the inspection unit that is turned on, the communication in the processing device 21 is confirmed, the software is activated, and the like. When the power is turned on, the rotation mechanism unit starts preparation for operation called “device origin”. This preparation is for confirming whether the apparatus is ready by receiving the mechanical origin of the apparatus, the software origin position, and the software activation signal trigger in the inspection unit.

  The rotation mechanism unit that has finished the origin of the apparatus turns on the inspection preparation completion lamp and waits for rotation preparation.

  When the foam roller 1 as a measurement object is placed on the rotation mechanism and a rotation start signal is received, the rotation mechanism (such as the motor driver 18) starts rotating. After the time when the rotation mechanism determines that the rotation of the measurement object has become constant, an inspection start trigger is transmitted to the inspection unit. The inspection unit receives the inspection start trigger signal and starts image processing, that is, inspection.

  When an inspection start trigger is received by the inspection unit, image capturing of the imaging device 11 is started, and image processing is sequentially performed on the captured image. From the viewpoint of improving the processing speed, the processing device 21 performs parallel processing so that capture and image processing can proceed simultaneously in parallel.

  The processing device 21 that has finished capturing the image or finished the image processing outputs an inspection end trigger to the rotation mechanism unit at the same time as the inspection is completed, from the viewpoint of enabling the next measurement object to be replaced as soon as possible. To do. Thereafter, the inspection results are totaled and the inspection results are output.

  Upon receiving the inspection end signal, the rotation mechanism immediately stops the rotation of the measurement object and enables the measurement object to be attached and detached. After determining that the rotation of the measurement object is sufficiently completed, an attachment / detachment signal is output. Upon receiving this signal, the hand unit attaches / detaches the object to be measured.

  The inspection result can be confirmed by displaying in the vicinity of the location of the rotation mechanism and output from the display device.

  Further, image processing in the inspection unit will be described in detail.

  First, preprocessing for image processing will be described.

  Illuminance calculation is performed on the captured image when capturing an image of the measurement object. The illuminance varies by about 10 to 20 depending on the shape state of the product and the arrangement angle of the optical system. The illuminance can be adjusted by the volume attached to the light projecting device. The brightness conversion adjustment value of the captured image can be set to any value in 256 gradations, but is preferably around 160 from the viewpoint of making the illuminance less susceptible to product tolerances. However, the present invention is not limited to this value as long as the foam roller 1 can be photographed satisfactorily.

  The captured image is subjected to a smoothing process in order to reduce noise due to external influences generated during data transmission, noise due to camera pixel loss, and the like. The smoothing process is set so as to reduce the influence of the surface roughness of the product. Therefore, the numerical value of the set value can be changed so as to be able to cope with differences in detection conditions and installation conditions.

  At this time, the pixel adjustment value for smoothing processing of the captured image, that is, the range of adjacent pixels when averaging, can be set to any value within the number of captured pixels, but preferably reduces the surface roughness of the product However, from the viewpoint of enabling detection of irregularities, the vicinity of 3 to 5 is desirable. However, the value is not limited to this value as long as the product surface portion can be photographed satisfactorily.

  Next, the defect detection process in the inspection unit will be described.

  After performing the image processing pre-processing, binarization processing, light amount difference processing, and the like are performed in order to detect defects. The binarization process is to recognize a defect below a set illuminance as a defect.

  In the light amount difference process, one captured image is divided into a plurality of set frames, and an average light amount of the divided frames is calculated. Next, the difference between the calculated frame and the adjacent frame is calculated. The maximum value of the difference value is calculated, and a defect is found by comparing the reference value as a defect with the maximum value.

  In this light quantity difference process, instead of comparing with adjacent frames, an image one image before may be used and the average light quantity difference of the frames at the same place may be used for calculation.

  By sequentially performing such processing on the captured image, it is possible to find a defective portion. Since the binarization method and the light amount difference processing are suitable for the foam roller, it is excellent as a defect detection method for use as a conveyance roller member (for example, a toner conveyance roller for an electrophotographic apparatus) in an image forming apparatus. It is also a thing.

  Hereinafter, the above-described embodiment will be described more specifically.

  The above-described defect detection apparatus is provided with components having the reference numerals shown in FIG. Although it overlaps with said description, the code | symbol 1 is a foam roller, the code | symbol 2 is a reflecting plate, the code | symbol 3 is a light source, the code | symbol 4 is a cylindrical lens, the code | symbol 5 is a light projection control apparatus, the code | symbol 11 is an imaging device, and the code | symbol 12 is a camera. Reference numeral 13 denotes a fine movement stage, and reference numeral 18 denotes a motor driver. Reference numeral 19 denotes a drive control device, reference numeral 20 denotes an inspection stage, reference numeral 21 denotes a storage device and a processing device, reference numeral 22 denotes a display device, and reference numeral 23 denotes a power supply unit and an uninterruptible power supply.

  The light projection control device 5, the imaging device 11, the motor driver 18, the drive control device 19, the storage device and processing device 21, and the display device 22 are supplied with power from a power supply unit and an uninterruptible power supply 23.

  The light emitted from the light source 3 from the light projection control device 5 and passed through the cylindrical lens 4 is applied to the foam roller 1. The light irradiated on the foam roller 1 is classified into a component that reflects on the surface portion of the foam roller 1 and a light component that transmits inside the foam roller 1. The light P reflected from the roller surface portion is taken into the image pickup device 11, and the light Q transmitted through the roller is also reflected by the reflector 2 and taken into the image pickup device 11.

  An image photographed by the imaging device 11 is transferred to the storage device and the processing device 21. At this time, the transferred image is stored in the storage device and the processing device 21 with an image number.

  The camera lens 12 of the imaging device 11 is a lens for exclusive use in close-up photography that can obtain the best optical performance during close-up photography, and has a focus function and an iris diaphragm function that can adjust the light amount. In the imaging device 11, an image was selected so that the image can be accurately formed without causing halation.

  The processing device 21 performs image processing on the basis of image data stored in a built-in storage device. The image processing flow is to remove noise and the like from the captured image first. Filter processing (image smoothing processing) is performed. This is set in order to eliminate sudden noise of pixels, such as when one pixel suddenly has a light amount that is significantly different from neighboring neighboring pixels, and to reduce the effect of product surface roughness. It is processing.

  In addition, since the illuminances of the foam roller image 33 by reflected light and the foam roller image 34 by transmitted light are different from each other as shown in FIG. 7, the light amount in each image is calculated, and based on the light amount value, A process to add light is added.

  Based on these images, it is possible to recognize irregularities on the surface of the product and locations such as bubbles inside the product, thereby enabling detection of defects on the product surface and inside.

  At that time, settings such as the magnification of each camera lens 12, the installation angle of the imaging device 11, and the position of the imageable range are registered in the processing device 21 in advance. Based on the information, the position information and size of the defect are calculated on the processing device 21, and the result is recorded in the storage device and simultaneously output to the display device 22.

  In addition, the processing device 21 can inspect the entire inspection region by interlocking with the drive control device 19 and controlling the motor driver 18 according to the set measurement resolution and sequentially changing the inspection position of the foam roller 1. It has become.

  Next, the defect detection operation will be described.

  The defect detection apparatus of this example includes a hand unit, a rotation mechanism unit, and an inspection unit. The work refers to an object to be inspected (measurement object) that is the foam roller 1 to be a product. The hand unit has a function of placing the work on the work table of the inspection stage 20 and a function of receiving the result of the image processing unit and placing the work on each conveyor from the work table (not shown in FIG. 2). In the hand portion, the workpiece can be attached to and detached from the workpiece table.

  The rotation mechanism unit includes a motor driver 18 as a drive unit and a rotation member 15 for rotating the workpiece.

  The inspection unit includes a storage device and processing device 21, a display device 22, a drive control device 19 that drives and controls the rotation mechanism unit, an imaging device 11, and a five light projector. And the defect location of the surface part of a workpiece | work can be recognized now by rotation control of a rotation mechanism part, and image processing.

  The rotation mechanism unit will be described. The rotation mechanism unit is a mechanism that aims to image the entire area where the imaging device 11 should image the workpiece, that is, the entire inspection area.

  First, the workpiece is conveyed from the hand unit to the rotation mechanism unit on the inspection stage 20 and set on the rotation member 15. The set work is moved forward to fix the position of the work so as not to be displaced. After gripping the workpiece and fixing the position, the gripping mechanism is retracted from the viewpoint of preventing the force from an unreasonable direction from acting outside the rotation mechanism portion.

  When the gripping mechanism is retracted, the rotating member 15 is rotated by the motor driver 18 controlled by the drive control device 19. After rotating the work so that the imaging device 11 captures the entire region to be imaged, that is, the entire inspection area, the rotation mechanism unit ends the rotation of the work. After the rotation mechanism unit completes the rotation of the workpiece, the workpiece is removed from the workpiece stage of the inspection stage 20 by the mechanism of the hand unit after waiting for the result of the inspection unit.

  After the workpiece is taken out from the workpiece table, the hand unit returns to the stage start position and waits for another workpiece to be placed thereon.

  The workpieces taken out from the workpiece table are separated by the respective conveyors after waiting for the result of the inspection unit.

  Next, the inspection unit will be described.

  An inspection part is a mechanism aiming at recognizing a spot considered as defects, such as an unevenness of the surface of foam roller 1 which is a work, and air bubbles inside. At the same time, it also serves as a control function for the hand unit and the rotation mechanism unit.

  The inspection unit receives an inspection trigger signal transmitted when a work is placed on the rotation mechanism unit, and starts initialization such as memory initialization and window setting for image processing.

  An inspection start trigger transmitted from the drive control device 19 is started when rotation of the rotating member 15 that holds the workpiece is started and a rotation speed region in which the imaging device 11 can determine that it is a stable workpiece rotation to be imaged. Upon receipt, image capture starts.

  After imaging the area to be imaged by the imaging device 11, that is, the entire inspection area, the processing device 21 performs image processing and totals the results. The totaled result is sent as a result I / O to the hand unit to send it to the conveyor according to the result.

  The hand unit, the rotation mechanism unit, and the inspection unit cooperate with each other, and by repeating the operation, a plurality of workpieces can be imaged in a short time.

"Comparative example"
Next, a comparative example is shown.

  As a comparative example, the arrangement of the light projecting device (housing provided with the light source 3 and the cylindrical lens 4) and the imaging device 11 of the present embodiment is as shown in FIG. That is, with respect to the foam roller 1, the imaging device 11A that captures the reflected light and the imaging device 11B that captures the transmitted light are arranged separately.

  As samples of the foam roller 1 used at this time, 5 defective products each having streaks on the roller surface portion and 5 defective products having air bubbles inside the roller were prepared. And the same test | inspection was performed by the method of a comparative example and a present Example.

  As a result of the inspection, in the comparative example and the present example, it was determined that both of the five were defective.

  From this, it was proved that the defect detection method in this example can show the same inspection ability as that of the comparative example.

  The preferred embodiments of the present invention have been described with reference to the drawings. However, the present invention is not limited to the structures and shapes disclosed in the drawings, and various modifications can be made without departing from the scope of the present invention. It goes without saying that it can be done.

It is a figure which shows the installation angle of the reflecting plate used for this invention. It is a block diagram which shows the structure of the defect detection apparatus by one Embodiment of this invention. It is a perspective view which shows the fine adjustment function of the imaging device of FIG. It is a side view which shows the fine adjustment function of the imaging device of FIG. It is a figure which shows arrangement | positioning of the light projector used for this invention, an imaging device, and a reflecting plate. It is the flowchart which showed an example of the flow which test | inspects the foam roller whole region using the defect detection apparatus of this invention. It is a block diagram of the captured image in the imaging device in an Example. It is a block diagram of apparatus arrangement in comparative example 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Foam roller 2 Reflector 5 Light projector 11 Imaging device 31 Captured image 32 Direct reflected image by reflector 33 Foam roller image 34 by reflected light Foam roller image by transmitted light

Claims (7)

In the foam roller defect detection method for detecting defects in the foam roller using at least a light projecting device and an imaging device,
The light from the light projecting device is projected onto the foam roller, the reflected light at the foam roller is imaged with the imaging device, and the transmitted light that has passed through the foam roller is reflected with a reflector, A defect detection method for a foam roller, wherein an image is picked up by the image pickup device.   The foam roller defect detection method according to claim 1, wherein an angle formed by the reflection plate is 60 degrees or more and 150 degrees or less with respect to an optical axis of the light projecting device. The defect detection method for a foam roller according to claim 1, wherein the wavelength of light from the light projecting device is 320 nm or more.   The defect detection method for a foam roller according to any one of claims 1 to 3, wherein the foam roller is a toner transport roller for an electrophotographic apparatus. In the foam roller defect detection device, which has at least a light projecting device and an imaging device, and detects a defect in the foam roller based on an image obtained by the imaging device,
The light from the light projecting device is projected onto the foam roller, the reflected light in the foam roller is imaged by the imaging device, and the transmitted light that has passed through the foam roller is reflected by a reflector, A defect detection apparatus for a foam roller, wherein an image is picked up by the image pickup apparatus.   The defect detection device for a foam roller according to claim 4, wherein an angle formed by the reflection plate is 60 degrees or more and 150 degrees or less with respect to an optical axis of the light projecting device.   The defect detection apparatus for a foam roller according to claim 5 or 6, wherein the foam roller is a toner transport roller for an electrophotographic apparatus.

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