JP3338293B2 - Print inspection equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inspection apparatus for inspecting a printed surface condition of characters, graphics, etc. printed on the surface of an inspection object such as a compact disk (hereinafter, referred to as a CD).

[0002]

2. Description of the Related Art Conventionally, a printed matter inspection apparatus 11 for inspecting a multicolor printed matter such as a CD using an image processing technique, as shown in FIG. 7 and area camera 1
The CD 9 put on the transport tray 10 from the stage 3 is printed as the stages 4, 5, and 6, the defect is inspected by the inspection stage 7, and the CD 9 is discharged from the discharge stage 8. Then, before the inspection of the CD 9 is started, a teacher CD that has been printed without any problem at each printing stage is photographed by the area camera 1 and stored in the image processing device 2 to be a teacher image. Then, when the CD to be inspected is located immediately below the area camera 1, the image is photographed by the area camera 1 to be an inspection image. The former teacher image and the latter inspection image are subtracted between the images, and a portion where the result of the subtraction cannot be regarded as “zero” has been determined to be defective if a considerable amount remains.

[0003]

Conventionally, even if the CD to be inspected is non-defective and has no printing defects, the number of tens to several tens of CDs per CD depends on the mechanical accuracy of the CD transport device and the printing accuracy of the printing machine. An error of about 100 microns occurs, and when subtraction is performed between the teacher image and the inspection image, a portion that cannot be regarded as “zero” remains near the edge of the printed symbol. If this is determined as "defect", most of the inspection CDs will be determined as "defect". Therefore, conventionally, even if there is a part near the edge of the symbol that can not be regarded as `` zero '', the defect is determined to be defective only when the amount is large enough to exceed the influence of mechanical accuracy and printing accuracy As a result, it was not possible to detect a minute printing defect generated at the end of the printed symbol.

[0004]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention is directed to a printing machine in which an object to be inspected is input from an input stage, and a pattern of the object to be inspected is sequentially printed in a plurality of colors on a plurality of printing stages. In a printed matter inspection apparatus for inspecting by comparing with a teacher image stored in a memory in advance, an inspection stage alternately arranged with a printing stage;
An image pickup unit disposed on the input stage and each inspection stage, for picking up an image of a printed symbol of the object to be inspected. Image processing means that detects newly printed color information on the stage and saves a teacher image extracted from the teacher design only the newly printed color based on the detected color information, and when printing the inspection pattern of the inspection object Detecting the newly printed color information at each printing stage from the image of the inspection pattern imaged by each imaging means, and extracting only the newly printed color from the inspection pattern based on the detected color information, the inspection image Image processing means for storing the image and subtracting the teacher image and the inspection image from each other to determine a print defect of the inspection symbol. According to another embodiment of the present invention, a teacher image is set in a printing machine in which an object to be inspected is input from an input stage, and a pattern of the object to be inspected is sequentially printed in a plurality of colors on a plurality of printing stages, and is stored in a memory in advance. In a printed matter inspection apparatus for inspecting by comparing with a printing stage, an inspection stage arranged alternately with a printing stage, an input stage and an imaging means arranged on each inspection stage to image a printed pattern of the inspection object, At the time of printing the teacher's design of the object, the color information newly printed at each printing stage is detected from the image of the teacher's design captured by each imaging means, and only the newly printed color is detected based on the detected color information. An image processing means for storing a teacher image extracted from the teacher symbol, and a step of obtaining a teacher image from an image of the inspection symbol imaged by each imaging means at the time of printing the inspection symbol of the inspection object. Image processing means for storing an inspection image in which only a newly printed color is extracted from the inspection symbol based on the color information, and subtracting the teacher image and the inspection image between the images to determine a print defect of the inspection symbol It is characterized by the following.

[0005]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention is directed to a printing machine in which symbols of a printed matter are sequentially printed in multi-colors for each printing stage, and a teacher image stored in a memory in advance. When printing a teacher's design of an inspection object, the printed matter inspection device detects how many colors were newly printed for each printing stage, and based on this color information, detects only newly printed colors. The image extracted from the design and obtained is stored in the memory as a teacher image for each printing color.

Next, at the time of printing the inspection pattern of the object to be inspected, how many colors are newly printed for each printing stage is detected, and only the newly printed colors are extracted from the inspection pattern based on this color information. Alternatively, only the newly printed color can be extracted from the inspection design using the color information used in extracting the teacher image. Then, the obtained image is aligned to the position of the teacher image only by the movement amount of the printing accuracy, and is stored in the memory as the inspection image.

[0007] Then, the teacher image and the inspection image are subjected to subtraction between the images, and if there is a portion that cannot be regarded as "zero", it is determined to be a defect.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the pattern of the CD is the first
A color camera fixed on an inspection stage attached to each printing stage that is installed in a printing machine that sequentially performs multicolor printing of colors, second colors, third colors,. The print color is detected, the color is extracted by an image processing device located at the rear stage of the color camera, and the print defect is inspected by comparing with the teacher CD.

When printing a teacher CD which is printed without defects in advance, colors to be newly printed for each printing stage are detected by a color camera fixed on an inspection stage attached to each printing stage, and detected. Only newly printed colors are extracted based on the obtained color information, and are stored in the image processing apparatus as teacher images for each printing color. Next, when printing the CD to be inspected, a color to be newly printed is detected for each printing stage of the CD to be inspected, or only the newly printed color is detected by using the color information detected from the teacher CD. Is extracted, the extracted image is aligned only within the printing accuracy to the image position of the teacher image, and is stored in the image processing apparatus as an inspection image for each printing stage. The inspection image and the teacher image are subjected to subtraction between the images, and if a part whose result cannot be regarded as “zero” remains, it is determined as a defect.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic explanatory view showing the configuration of a printed matter inspection apparatus according to the present invention. FIG. 2 is a block diagram of a main part image in the image processing apparatus of the printed matter inspection apparatus according to the present invention.

As shown in FIG. 1, a printed matter inspection device 30
Is a turntable 31 installed on the printing press 100,
A transport tray 32 disposed on each stage of the turntable 31 in equal divisions, a CD 33 placed at a substantially central portion of the transport tray 32, and an optical axis fixed to be located at the center of the CD to be inspected. Color cameras 50, 51, 52, 53
And an image processing device 54 that is located at the subsequent stage of each color camera and processes an image captured by each camera.

To explain each stage in the direction g of rotation of the turntable 31, a loading stage 34 at the top of the turntable 31 where an unprinted CD 33 is loaded into the transport tray 32, and then a printing machine ( The first color printing stage 3 on which the first color is printed by a not-shown)
5. Next, a first color inspection stage 36 for inspecting printing on the first color printing stage 35, next, a second color printing stage 37 on which a second color is printed, and next, a second color printing stage 37
The second color inspection stage 38 for inspecting the printing at the third color, the third color printing stage 39 at which the third color is printed, and the third color
A third color inspection stage 40 for inspecting printing on the color printing stage 39, and finally, a discharge stage 41 for discharging the printed CD 33 from the transport tray 32 to the outside, a total of eight stages.

The color camera includes a color camera 50 fixed on the input stage 34, a color camera 51 fixed on the first color inspection stage 36, and a second color inspection stage 3.
A total of four color cameras 52 fixed on the third color inspection stage 40 and a color camera 52 fixed on the third color inspection stage 40 are installed. Each of the color cameras 50, 51, 52, 53 is connected to the transport tray 32 on each of the stages 34, 36, 38, 40.
The CD 33 placed on the camera is fixed so as to be photographed from directly above, and the photographed images are captured by the respective color cameras 50, 51, 52, 5
3 is subjected to image processing by the image processing device 54 located at the subsequent stage, and the presence or absence of a defect on the printing surface of the CD 33 is determined.

Next, referring to FIGS. 1, 2 and 3, the process of the defect inspection in this embodiment will be described.

First, a teacher CD 33 serving as a CD inspection standard
When printing 1, the color camera 50 and the color camera 51
By using the image processing device 54 to check for a color that does not exist in the image 60 of the color camera 50 but exists in the image 61 of the color camera 51 using the image processing device 54, the image is printed by the first color printing stage 35. The detected color is detected and stored in the image processing device 54 as color information x of the first color. Next, from the image 61 by the color camera 51, an image 65 is obtained by extracting only the portion printed on the first color printing stage based on the color information x of the first color. The image 65 thus obtained is stored in the image processing device 54 as the teacher image 65 for the first color.

Similarly, based on the results obtained by photographing with the color cameras 51 and 52, the color which does not exist in the image 61 of the color camera 51 but exists in the image 62 of the color camera 52 is determined by using the image processing device 54. The color printed by the second color printing stage 37 is detected,
The color information y of the second color is stored in the image processing device 54.
Next, from the image 62 by the color camera 52, an image 66 is obtained by extracting only the portion printed by the second color printing stage 37 based on the color information y of the second color. The image 66 thus obtained is stored in the image processing device 54 as a teacher image 66 for the second color.

Similarly, based on the results of photographing with the color camera 52 and the color camera 53, the color which does not exist in the image 62 of the color camera 52 but exists in the image 63 of the color camera 53 is The color printed by the third color printing stage 39 is detected,
The color information z of the third color is stored in the image processing device 54.
Next, from the image 63 by the color camera 53, an image 67 is obtained by extracting only the portion printed on the third color printing stage based on the color information z of the third color. The image 67 thus obtained is stored in the image processing device 54 as the teacher image 67 for the third color.

Next, the following two examples of the process of printing and inspecting the CD 332 to be inspected to be inspected can be considered.

In the first example, in the process of obtaining the teacher images 65, 66, and 67, the color information x, y, and z for each stage stored in the image processing device 54 are used to extract the inspection image of the inspection CD 332. The inspection process is described below.

First, the color camera 50 and the color camera 5
By using the image processing device 54 to check the color that does not exist in the image 70 of the color camera 50 but exists in the image 71 of the color camera 51,
The color printed by the color printing stage 35 is detected and stored in the image processing device 54 as color information of the first color. Then, based on the color information of the first color, an image 75 is obtained by extracting only the portion printed on the first color printing stage from the image 71 by the color camera 51. The image processing device 54 uses the image 75 thus obtained as an inspection image for the first color.
To save. Then, before comparing the teacher image 65 stored in the image processing device 54 with the inspection image 75, the position of the inspection image 75 is moved and the teacher image is moved in order to eliminate an image deviation due to a variation in printing accuracy by the printing mechanism. An image in which the positional deviation from the image 65 is absorbed is created, and is stored in the image processing device 54 as the inspection image 85 for the first color. And
Image subtraction is performed between the teacher image 65 and the inspection image 85 for the first color, and a difference image 95 is obtained. If there is a portion where the difference is not “zero” in the difference image 95, it is determined that the defect is “present” in the first color.

Similarly, based on the results of photographing with the color camera 51 and the color camera 52, the color which does not exist in the image 71 of the color camera 51 but exists in the image 72 of the color camera 52 is The color printed by the second color printing stage 37 is detected,
The color information of the second color is stored in the image processing device 54. Then, from the image 72 by the color camera 52, the second
Based on the color information of the color, an image 76 is obtained in which only the portion printed by the second color printing stage 37 is extracted. The image 76 thus obtained is stored in the image processing device 54 as an inspection image for the second color. Then, before comparing the teacher image 66 and the inspection image 76 stored in the image processing device 54,
In order to eliminate an image shift due to a variation in printing accuracy by the printing mechanism, an image is created in which the position of the inspection image 76 is moved to absorb the positional deviation from the teacher image 66, and the image is used as the inspection image 86 for the second color. It is stored in the processing device 54. Then, the teacher image 66 and the inspection image 8 for the second color
In step 6, subtraction between images is performed to obtain a difference image 96. Difference image 96
In, if there is a portion where the difference is not “zero”, it is determined that the defect is “present” in the second color.

Similarly, based on the results obtained by photographing with the color camera 52 and the color camera 53, the color which does not exist in the image 72 of the color camera 52 but exists in the image 73 of the color camera 53 is determined by using the image processing 54. By checking, the color printed by the third color printing stage 39 is detected and stored in the image processing device 54 as color information of the third color. Then, from the image 73 by the color camera 53, an image 77 is obtained by extracting only the portion printed on the third color printing stage based on the color information of the third color. The image 77 thus obtained is used as the inspection image for the third color as the image processing device 54.
To save. Then, before comparing the teacher image 67 stored in the image processing device 54 with the inspection image 77, the position of the inspection image 77 is moved and the teacher image is moved in order to eliminate an image deviation due to a variation in printing accuracy by the printing mechanism. An image in which the positional deviation from the image 67 is absorbed is created, and is set as the inspection image 87 for the third color. Then, the teacher image 67 for the third color
And the inspection image 87 are subtracted between images to obtain a difference image 97. If there is a portion in the difference image 97 where the difference is not “zero”, it is determined that the third color has a defect “present”.

If no defect is detected through the above-described inspection for each color, the CD 33 is determined as having no defect.

In the second example, in the process of obtaining the teacher images 65, 66, and 67, the color information x, y, and z for each stage stored in the image processing device 54 are used to extract the inspection image of the inspection CD 332. The inspection process will be described below.

First, based on the color information x of the first color used when extracting the teacher image 65 from the image 71 from the color camera 51, only the portion printed by the first color printing stage 35 is extracted. Get 75. The image 75 thus obtained is stored in the image processing device 54 as an inspection image for the first color. Then, before comparing the teacher image 65 stored in the image processing device 54 with the inspection image 75, the position of the inspection image 75 is moved and the teacher image is moved in order to eliminate an image deviation due to a variation in printing accuracy by the printing mechanism. Image 6
An image in which the misalignment with the image No. 5 is absorbed is created, and is stored in the image processing device 54 as the inspection image 85 for the first color. Then, subtraction between images is performed between the teacher image 65 and the inspection image 85 for the first color, and a difference image 95 is obtained. If there is a portion where the difference is not “zero” in the difference image 95, the first
In the color, it is determined that the defect is “present”.

Similarly, only the portion printed by the second color printing stage 37 is extracted from the image 72 by the color camera 52, based on the color information y of the second color used when extracting the teacher image 66. Obtained image 76 is obtained. The image 76 thus obtained is stored in the image processing device 54 as an inspection image for the second color. Then, before comparing the teacher image 66 stored in the image processing device 54 with the inspection image 76, the position of the inspection image 76 is moved to remove the image deviation due to the variation in printing accuracy by the printing mechanism. An image in which the positional deviation from the image 66 has been absorbed is created, and the second
The inspection image 86 for the color is stored in the image processing device 54. Then, image subtraction is performed between the teacher image 66 and the inspection image 86 for the second color, and a difference image 96 is obtained. Difference image 9
In 6, if there is a portion where the difference is not “zero”, it is determined that the defect is “present” in the second color.

Similarly, only the portion printed by the third color printing stage 39 is extracted from the image 73 by the color camera 53 based on the third color information z used when extracting the teacher image 67. The obtained image 77 is obtained. The image 77 thus obtained is stored in the image processing device 54 as an inspection image for the third color. Then, before comparing the teacher image 67 stored in the image processing device 54 with the inspection image 77, the position of the inspection image 77 is moved and the teacher image is moved in order to eliminate an image deviation due to a variation in printing accuracy by the printing mechanism. An image in which the positional deviation from the image 67 is absorbed is created, and the third
The inspection image 87 for the color is stored in the image processing device 54. Then, image subtraction is performed between the teacher image 67 and the inspection image 87 for the third color, and a difference image 97 is obtained. Difference image 9
In 7, if there is a portion where the difference is not “zero”, it is determined that a defect is “present” for the third color.

If no defect is detected through the inspection for each color, it is determined that the CD has no defect.

The effect of the difference between Example 1 and Example 2 is that Example 2 has a shorter image processing time and a shorter inspection time than Example 1 by using the color information of the teacher image.

In the difference images 95, 96 and 97, even if the difference is not "zero", if the difference is equal to or less than a certain threshold value, the difference is regarded as "zero". It is also possible that such a density difference is not determined as a defect.

Further, it is possible to detect a small defect equal to or less than the print shift amount on the entire surface including the end of the printed pattern, while judging that the print shift caused by the printing accuracy of the printing press is a good product.

Conventionally, when a serial number or the like is engraved on a printing surface of a CD, the teacher image and the C
Since a difference occurs due to the difference in the serial number in the difference image of D, the portion has been determined to be defective. In order to avoid this, a certain area including a serial number is designated as a non-inspection area, and inspection cannot be performed even if a print defect occurs in that area. In the present invention, since each print color is extracted and inspected, differences due to elements other than printing, such as engraving, are not determined as defects.

[0033]

The present invention is embodied in the form described above and has the following effects.

By automating a fine defect inspection of a pattern edge which had to be manually performed conventionally, a reliable defect detection can be performed, and the labor of the inspection process can be reduced and the inspection time can be shortened.

Further, since the defect is detected by detecting the print color, it is possible to carry out the inspection over the entire surface of the printed matter including the inscription and the like, thereby improving the quality of the printed matter.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a printed matter inspection apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a main part image in the image processing apparatus of the printed matter inspection apparatus.

FIG. 3 is a schematic explanatory view showing a configuration of a conventional printed matter inspection apparatus.

[Explanation of symbols]

34 Input stage 33 Inspection CD (inspection object) 35, 37, 39 First color, second color, third color printing stage (each printing stage) 36, 38, 40 First color, second color, third Color inspection stage (each inspection stage) 50, 51, 52, 53 Color camera (imaging unit) 54 Image processing unit (image processing device) 65, 66, 67 Teacher image 85, 86, 87 Inspection image 331 Teacher CD (teacher design) ) 332 CD to be inspected (inspection pattern)

Claims (2)

(57) [Claims] An object to be inspected is loaded from an input stage, and a pattern of the object to be inspected is installed in a printing machine in which a plurality of printing stages sequentially print in a multi-color manner, and is compared with a teacher image stored in a memory in advance. In a printed matter inspection device to be inspected, an inspection stage arranged alternately with the print stage,
An imaging unit disposed on the input stage and each inspection stage and imaging a printed symbol of the inspected object; and at the time of printing a teacher symbol of the inspected object, each image is captured from the image of the teacher symbol captured by each imaging unit. Image processing means for detecting newly printed color information at the printing stage, and storing a teacher image which is obtained by extracting only newly printed colors from the teacher pattern based on the detected color information, and printing the inspection pattern of the inspection object. At the time, color information newly printed at each printing stage is detected from the image of the inspection pattern imaged by each imaging means, and only the newly printed color is extracted from the inspection pattern based on the detected color information. A printed matter inspecting apparatus, comprising: an image processing unit for saving, wherein a subtraction between the teacher image and the inspection image is performed to determine a print defect of the inspection symbol. 2. An inspection object is introduced from an input stage, and a pattern of the inspection object is set on a printing machine in which a plurality of printing stages sequentially print in multicolor, and is compared with a teacher image stored in a memory in advance. In a printed matter inspection device to be inspected, an inspection stage arranged alternately with the print stage,
An imaging unit disposed on the input stage and each inspection stage, and imaging a printed symbol of the inspection object. At the time of printing the teacher symbol of the inspection object, from the image of the teacher symbol imaged by each imaging unit, An image processing means for detecting newly printed color information at each printing stage, and storing a teacher image extracted from the teacher design only of a newly printed color based on the detected color information; and At the time of printing, an image for storing an inspection image obtained by extracting only a newly printed color from the inspection pattern based on the color information obtained in the step of obtaining the teacher image from the image of the inspection pattern captured by each imaging unit. A printed matter inspection apparatus, comprising: a processing unit, wherein subtraction between the teacher image and the inspection image is performed to determine a print defect of the inspection symbol.