JP2000103039A - Apparatus for inspecting printing on cylindrical container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus for inspecting printing on a cylindrical container by which imaging time can be stably taken and accuracy in inspection is improved. SOLUTION: A plurality of articles 1 to be inspected carried in by means of a carrying-in belt 8 are inserted into a plurality of rotating shafts of a work rotating unit 2 and while the articles to be inspected are being rotated around the rotating shaft, the surface of the articles to be inspected are imaged by an imaging means 3. Existence of defects of printing on the outer surfaces of the articles to be printed is judged by the imaging data obtd. The articles to be inspected after imaging are taken out from the rotating shaft and are carried on a carrying-out conveyer 9 and articles of inferior quality are discharged. By carrying, imaging and inspecting simultaneously a plurality of the articles to be inspected, a stable imaging time for at least two rotations can be taken and accuracy of the inspection can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for inspecting the outer surface of a cylindrical container for the presence of foreign matter such as a print defect or a print stain.

[0002]

2. Description of the Related Art In the production of cylindrical containers such as aluminum tubes, plastic tubes, round molded bottles, and cans, minute defects in printing on the cylindrical surface are inspected. Inspection items are, for example, missing, blurred, stained (blurred), clogged, and adhered foreign matters of printed characters. The detected defective product is removed from the manufacturing process, and its outflow is prevented. Conventionally, printing inspection of the outer surface of a cylindrical container has been mainly performed by a manual inspection in the final step. A print inspection apparatus that automatically performs print inspection is used, for example, immediately after printing on an automated manufacturing line or in a final appearance inspection process, but does not mechanically satisfy required inspection accuracy and is expensive. Had become something. In addition, an inspection machine for partial printing or for the presence or absence of attached foreign matter has been partially used.

[0003]

A conventional printing inspection apparatus for cylindrical containers is a method of transporting and inspecting containers one by one by an index rotation type. This print inspection device
It is necessary to make the time for transferring to the imaging unit and the time for rotating and imaging within the production tact. For this reason, the imaging time due to stable rotation is limited, and high-precision inspection corresponding to a high-speed production line cannot be performed. In addition, the number of rotation axes increases,
The equipment is large and expensive.

It is an object of the present invention to provide a printing inspection apparatus for a cylindrical container having a long stable imaging time and improved inspection accuracy.

[0005]

According to the present invention, there is provided an apparatus for inspecting a printing defect on an outer surface of a cylindrical container, comprising: a rotating mechanism having a plurality of rotating shafts; Transfer means to be attached to and detached from, an imaging means installed in a direction perpendicular to the rotation axis of the rotating mechanism, and an image of the inspection object being inserted into the rotation axis and being rotated, and an outer surface of each of the inspection objects by imaging data by the imaging means. Defect determining means for determining the presence or absence of a printing defect. By simultaneously transporting a plurality of objects to be inspected and imaging them for inspection, a stable imaging time of two or more rotations can be taken, and particularly errors due to rotation of the cylindrical container can be corrected, and inspection accuracy can be improved. Preferably, the apparatus further comprises a carrying-in means for carrying in the object to be inspected, and a carrying-out means for carrying out the object to be inspected, and the transfer means transports the object to be inspected carried by the carrying-in means to a rotating shaft of a rotating mechanism, The inspection object removed from the rotation shaft of the rotation mechanism is transported to the unloading means.
Thereby, the print inspection device can be installed in the manufacturing process. Preferably, the apparatus further includes a discharge unit in the vicinity of the carry-out conveyor, which discharges the inspection object determined to have a printing defect by the defect determination unit out of the system. Preferably, there is provided a moving mechanism for moving a rotating mechanism having a plurality of rotating shafts to the setup unit. To maintain the accuracy of the rotating mechanism, replace the rotating shaft when changing the type (outer diameter) of the object to be inspected,
The task of measuring the diameter of the rotating shaft and the diameter of the cylindrical container is facilitated. Preferably, a transfer mechanism for transferring the object to be inspected to the carry-out conveyor before the object to be inspected is transferred to the rotating shaft is provided on the carry-in conveyor. As a result, the inspection object flows from the supply line directly to the discharge line.

[0006]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a cylindrical container print inspection apparatus according to an embodiment of the present invention.
In the drawings, the same reference symbols indicate the same or equivalent ones. This print inspection apparatus is used immediately after printing on an automated manufacturing line or in a final appearance inspection step, and inspects the surface of a cylindrical portion of a test object, which is a cylindrical container, for printing defects or foreign matter. FIG. 1 shows a configuration of an inspection system in a print inspection apparatus. FIGS. 2 and 3 are a plan view and a side view showing the arrangement of an object to be measured, a conveyor and an inspection unit, and a transfer path in the print inspection apparatus. The arrow indicates the moving direction of the inspection object. FIG. 2 shows a planar positional relationship between these components, and FIG. 3 shows a transfer of the inspection object in the inspection.

As shown in FIG. 1, the print inspection apparatus includes a work rotating unit 2, an image pickup device 3, a reflection light 4, two transfer mechanisms (a carry-in conveyor 8 and a carry-out conveyor 9), a transfer unit 15, and a control unit 5. Is provided. As shown in FIG.
The carry-in conveyor 8 and the carry-out conveyor 9 are arranged in parallel,
The transfer unit 15 is arranged between the carry-in conveyor 8 and the work rotating unit 2. The work rotating unit 2 is fixed to a rotating unit moving stage 6. In this print inspection apparatus, the inspection object 1 is transported to an inspection section by a servo-driven carry-in conveyor 8, and a plurality of inspection objects 1 are simultaneously inserted into the rotating shaft 2 'of the work rotating unit 2, and the servo motor rotates at high speed. The inspection object 1 is imaged by the plurality of line sensors of the imaging device 3 while the image data is
To inspect for print defects. After the imaging, the object to be measured is returned to the unloading conveyor 9 synchronized with the loading conveyor 8,
Proceed to the next step. By inspecting a plurality of inspection objects simultaneously, it is possible to achieve both high-speed and high-accuracy inspection. Hereinafter, the print inspection apparatus will be described in detail.

The loading of the inspection object 1 will be described. For example, a star wheel (not shown) is installed at one end (set portion) of the loading conveyor 8 and the inspection objects 1 are thrown into the loading conveyor 8 one by one. The inspection object 1 is transferred on the carry-in conveyor 8 by using the servomotor 11 as a drive source. The carry-in conveyor 8 can intermittently convey the plurality of inspection objects 1. Inspection object 1 by inspection object existence sensor 10
Is determined to have reached the predetermined position, the six inspection objects 1 are simultaneously moved by the transfer mechanism 14 in the horizontal direction onto the transfer unit 15. Next, the transfer unit 15 rises and stops at the same height as the work rotating unit 2. Further, another transfer mechanism 14 ′ simultaneously moves the six inspection objects 1 in the horizontal direction, and moves the opening of the cylindrical inspection object 1 to the cylindrical rotation shaft 2 ′ of the work rotating unit 2. insert.
Then, the rotating shaft 2 ′ enters the inspection object 1, and the inspection object 1 is fixed to the rotating shaft 2 ′. Thus, the surface of the inspection object 1 is set at a position where an image can be captured.

Work rotation unit 2 used for imaging
Is a motor that uses, for example, a servo motor 13 as a drive source, and rotates and stops with an electromagnetic clutch 12. Since a plurality of inspection objects are simultaneously transported, a stable imaging time of two or more rotations can be set. Therefore, the inspection object 1 is rotated at a constant speed by the rotation unit 2. The imaging device 3 installed above the inspection object 1 includes a line sensor in which photoelectric elements such as CCDs are arranged one-dimensionally in a vertical direction, and is electrically connected to the control unit 5. When the rotation is stabilized, the imaging device 3
With respect to the test object 1 rotated at a constant speed, an image of light reflected from the test object 1 by light emitted from the reflection illumination 4 is captured for two rotations. In this example, six test objects 1
In contrast, three imaging devices are installed to image three inspection objects 1 every other device. When the imaging is completed, the position of the work rotating unit 2 is moved, and the next inspection object 1 is imaged. As a result, images for two rotations of the surface of the six inspection objects 1 are obtained. The control unit 5 detects the presence or absence of a printing defect based on the obtained image data. By simultaneously transporting and inspecting a plurality of objects to be inspected, a stable imaging time of two or more rotations can be taken. Therefore, the control unit 5 determines the printing position deviation caused by the mechanical position deviation between the object and the rotating shaft 2 ′. And errors such as expansion and contraction in the rotation direction can be corrected, and the inspection accuracy is improved.

The plurality of DUTs 1 whose images have been picked up are withdrawn from the insertion position by the transfer mechanism 14 ', lifted up, and then returned to the unloading conveyor 9 which operates in synchronization with the loading conveyor 8. . Further, the transfer unit 15 descends and stops at the same height as the carry-in conveyor 8. When no printing failure is detected, the inspection object 1 is discharged from the unloading conveyor 9 as it is. Further, the inspection object (defective product) determined to be defective is removed from the carry-out conveyor 9 by, for example, the air blow 17 and discharged out of the system so as not to be transported to the next step. Since the print inspection apparatus described above has a small number of rotating shafts, a compact and inexpensive apparatus can be provided.

A rotating unit moving stage 6 to which the work rotating unit 2 having a plurality of rotating shafts 2 'is fixed.
Moves precisely in the left-right direction in FIG. 2 using, for example, the servomotor 7 as a drive source. For example, when the type (outer diameter) of the inspection object 1 changes, it moves to the setup position 16. In this printing inspection apparatus, since a plurality of inspection objects are inspected at the same time, the center of the rotating shaft 2 ′, the rotational unevenness, and the like must be maintained at a predetermined high accuracy. Therefore, at the setup position 16, when the type (outer diameter) of the inspection object is changed,
The work of replacing the rotating shaft (jig) in the work rotating unit 2 and measuring the deflection of the rotating shaft, the diameter of the rotating shaft, and the diameter of the cylindrical container can be easily performed. Further, a transfer mechanism to the carry-out conveyor 9 is provided on the carry-in conveyor 8 immediately before the inspection section. Thereby, when the inspection cannot be performed or when the inspection object is transported to the next process without performing the inspection, the inspection object 1 is directly transported from the loading conveyor 8 to the unloading conveyor 9 (see the lower right side in FIG. 2), Ensure operation of the production line.

The control unit 5 includes a motor control unit 51, a sequencer 52, an image processing unit 53, a ROM 54, an RA
M55, interface 56, display unit 57, and CP
U58, and each of the units 51 to 57 has a CP
It is electrically connected to U58. The CPU 58 uses the RO
In accordance with the control program of the print inspection apparatus stored in M54, the print inspection apparatus is controlled using the RAM 44 for temporarily recording data and the like. Motor control unit 51
Controls the drive current supplied to the servo motors 7, 11, 13. The sequencer 52 controls ON / OFF of signals of the inspection object presence / absence sensor 10 and the like, and the interface 56 performs input / output between the sequencer 52 and the CPU 58. The display unit 57 includes a liquid crystal display panel or the like, and displays an inspection result and the like.

The CPU 58 has the following functions (1) to (3). (1) Servo motor 17 via motor control unit 51
Function of controlling the rotation of the work rotating unit 2 by controlling the operation of A function of controlling the operation of the servo motors 11 and 13 to control the carry-in conveyor 8 and the rotary unit moving stage 6; (2) A function of inspecting the presence or absence of a print inspection defect based on a signal from the image processing unit 53 and transferring a defective product out of the system. (3) A function of controlling the display content of the display unit 57 based on the inspection result.

Next, an inspection procedure of the print inspection apparatus will be described with reference to a flowchart of control by the CPU 58 shown in FIG. When the inspection is started, the carry-in conveyor 8 is operated (Step S10), the work rotating unit 2 is operated (Step S12), the rotating unit moving stage 6 is operated (Step S14), and the reflection illumination 4 is turned on. (Step S16). When these initial settings are completed, loading of the inspection object (work) 1 is started (step S18). Next, it is determined whether or not a work signal indicating that the inspection object has reached a predetermined inspection position has been input (step S20). If not, after waiting (step S22), the process returns to step S20, and the determination is made again.

When the work signal is input, the six test objects 1 are transferred and inserted into the rotating shaft 2 'of the work rotating unit 2 (step S24). And the rotary clutch 12
Is activated (step S26). Inspection object 1
Is rotated, the image of the cylindrical surface of the inspection object 1 is captured by the imaging unit 3, and the inspection of print defects is started based on the obtained image data (step S28). Details of the inspection will be described later. When the image has been captured, the rotation clutch 12 is stopped (step S30). Then, the inspection object 1 is removed from the rotating shaft 2 ′ (Step S)
32) The inspection object 1 is placed on the unloading conveyor 9 and transported to the next process (step S34). If a printing failure is detected (YES in step S36), the inspection object 1 is discharged out of the system from the carry-out conveyor 9 using, for example, an air blow to prevent the outflow of the defective product (step S38). ). If no printing failure is detected,
Is discharged from the unloading conveyor 9 to the next process (step S40).

Next, image processing for inspecting a printing defect on the side surface of the cylindrical container in the image processing unit 53 will be described. FIG. 5 shows a basic flow of the image processing. First, in the reference image previously stored in the RAM 55, two templates to be used for template matching are set. As shown in (a), a print pattern of the inspection object 1 rotating around the rotation axis 2 ′ of the work rotation unit 2 is imaged, and an image for two rotations from an arbitrary position on the inspection object surface ( The video signal of the inspection object is captured.

Next, as shown in (b), an inspection image for one rotation is cut out from the image for two rotations and stored in the RAM 55. In this example, the same pattern as the reference image is found by extracting feature points using the template matching method using the two templates 1 and 2, and an inspection image for one rotation is cut out.
In order to cut out the inspection image for one rotation, at least two
A rotation image is required. And the clipped image
(Inspection image) is compared with a reference image stored in advance, and the difference between the template coordinates set in the reference image and the coordinates of the feature points extracted by template matching in the inspection image is used to determine the inclination of the inspection image. , Errors such as expansion and contraction in the rotation direction are calculated. Then, expansion / contraction correction and tilt correction in the rotation direction are performed on the inspection image using the error data, and the result is stored in the RAM 55. Next, template matching is performed again with the corrected inspection image having the changed size to extract feature points. Then, based on the difference between the coordinates of the feature points and the template coordinates set in the reference image, a positional shift is detected, the corrected inspection image is translated, and the alignment is performed to match the non-defective image data. By the above processing, it is possible to correct a printing position shift generated at the time of printing and a rotation error generated at the time of inspection.

Next, as shown in (c), a difference between the obtained inspection image and the reference image is obtained.
Binarization and noise removal are performed. Finally, as shown in (d), the obtained result is compared with a threshold to determine the quality. In this example, two locations were determined to be defective. As a result, this work is evaluated (determined) as a defective product. Since the evaluation is performed by correcting an error due to a printing position shift occurring at the time of printing and a rotation occurring at the time of inspection, high-precision inspection becomes possible.

FIG. 6 shows a flowchart of the above-described image processing. An image for two rotations is input from the imaging device 3 (step S100). Next, it is determined whether or not the input is a reference image (step S102). If it is a reference image,
Set templates 21 and 22 (step S13
0), the reference image (master image) is stored in the RAM 55 (step S132). Then, when the end of the image processing is instructed (YES in step S134), the processing ends. If the image processing is not completed (N in step S134)
O), returning to step S100 and continuing the processing.

If it is not a reference image input (step S10)
(NO in 2), the templates 21 and 22 are searched in the input image using the template matching method (step S104), and an inspection image for one rotation is cut out (step S106). Next, for the obtained inspection image,
Rotational direction expansion / contraction correction (step S108) and inclination correction (step S110) are performed. Further, in the corrected inspection image, the templates 21 and 22 are searched for using the template matching method (step S112), and the displacement of the inspection image is corrected (step S114). Then, the corrected inspection image is stored in the RAM 55 (Step S116).

Next, an absolute value difference between the inspection image and the reference image is calculated for comparison with the reference image stored in step S132 (step S118). The obtained result is binarized using a threshold value (step S12).
0) and noise removal (step S122). Then, the presence or absence of a printing defect is determined (step S124), and the result is output (step S126). Next, when it is determined that the inspection is not completed (N in step S134)
O), returning to step S100, and continuing the print defect inspection for the next inspection object.

[0022]

According to the apparatus for inspecting printing defects on the outer surface of a cylindrical container according to the present invention, a plurality of inspected objects are simultaneously transported, imaged and inspected, whereby a stable imaging time of two or more rotations can be secured. . For this reason, it is possible to correct errors such as a print position shift and a rotational direction expansion and contraction caused by a mechanical position shift between the object to be inspected and the rotating shaft, and the inspection accuracy for the presence or absence of a print defect can be improved. In addition, since the number of rotating shafts is small, a compact and inexpensive device can be provided, and the practical use of an automatic inspection device instead of a visual inspection can be promoted. Further, since the apparatus includes the carry-in means and the carry-out means, the print inspection apparatus can be installed in the manufacturing process. In addition, since there is provided a discharge unit for removing an inspection object determined to have a printing defect out of the system, a defective product does not flow to the next process.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a printing inspection device for a cylindrical container according to an embodiment of the present invention.

FIG. 2 is a plan view of a print inspection apparatus.

FIG. 3 is a side view of the print inspection apparatus.

FIG. 4 is a flowchart of a transport and inspection procedure.

FIG. 5 is a diagram showing a basic flow of image processing.

FIG. 6 is a flowchart of image processing.

[Explanation of symbols]

1 inspection object, 2 work rotation unit, 3
Imaging device, 4 reflection illumination, 5 control unit, 6
Rotary unit moving stage, 8 carry-in conveyor,
9 unloading conveyor, 12 electromagnetic clutch, 1
4, 14 'transfer mechanism, 15 transfer unit, 5
1 motor control unit, 53 image processing units,
58 CPU.

 ────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Makoto Takahashi 2-3-1-3 Azuchicho, Chuo-ku, Osaka-shi, Osaka F-term in Osaka International Building Minolta Co., Ltd. (reference) 2C250 EA02 EA31 EB43 2G051 AA11 AA90 AB01 AB11 AB20 BA01 BA20 CA03 CA04 CA07 DA02 DA06 DA08 DA13 EA08 EA11 EA14 EA23 EB01 EB02 FA10

Claims (3)

[Claims] A rotating mechanism having a plurality of rotating shafts; a transferring means for transferring a plurality of inspected objects to be attached to and detached from the rotating shaft of the rotating mechanism; and a rotating shaft installed in a direction perpendicular to the rotating shaft of the rotating mechanism. A print inspection apparatus, comprising: imaging means for imaging an inspected object inserted and rotated in the apparatus; and defect determining means for determining the presence or absence of a print defect on the outer surface of each inspected object based on image data obtained by the imaging means. apparatus. 2. The apparatus according to claim 1, further comprising a loading unit for loading the inspection object and an unloading unit for unloading the inspection object, wherein the transport unit transports the inspection object transported by the loading unit to a rotating shaft of a rotating mechanism. And transferring the object to be inspected removed from the rotating shaft of the rotating mechanism to the carrying-out means.
A print inspection device according to claim 1. 3. The printing apparatus according to claim 2, further comprising a discharge unit in the vicinity of the carry-out conveyor, the discharge unit excluding an inspection object determined to have a printing defect by the defect determination unit out of the system. Inspection equipment.