CN107408289B - Printing inspection method, printing inspection apparatus using the same, and printing inspection apparatus main body - Google Patents
Printing inspection method, printing inspection apparatus using the same, and printing inspection apparatus main body Download PDFInfo
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- CN107408289B CN107408289B CN201680015365.9A CN201680015365A CN107408289B CN 107408289 B CN107408289 B CN 107408289B CN 201680015365 A CN201680015365 A CN 201680015365A CN 107408289 B CN107408289 B CN 107408289B
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T1/00—General purpose image data processing
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
- B41J2203/00—Embodiments of or processes related to the control of the printing process
- B41J2203/01—Inspecting a printed medium or a medium to be printed using a sensing device
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
- B41J3/00—Typewriters or selective printing or marking mechanisms characterised by the purpose for which they are constructed
- B41J3/407—Typewriters or selective printing or marking mechanisms characterised by the purpose for which they are constructed for marking on special material
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Abstract
An object of the present invention is to provide a printing inspection method and apparatus for cutting each character from a character string in which a plurality of dot patterns are arranged and performing a contrast inspection of the character, even when the distance between the characters is substantially the same as the distance between adjacent dots within 1 character or is shorter than the distance between adjacent dots within 1 character. In order to solve the above-described problems, each character constituting a character string is cut out by an imaging step of imaging a recognition target to be performed every time a print is printed with a dot pattern of 1 character amount by the imaging step and an image extraction processing step of extracting a print image of a character to be inspected by obtaining a difference between an image captured immediately before printing of a character whose print quality is to be determined and an image captured immediately after printing of a corresponding character with respect to the image captured in the imaging step.
Description
Technical Field
The present invention relates to a printing inspection method and a device therefor, and more particularly, to a printing inspection method and a device therefor, which are suitable for use in a method for inspecting printed characters and symbols such as production year, month and day, production serial number, and the like (hereinafter, the symbols are also included in the characters and are simply referred to as "characters") printed on packaging containers for foods and medicines by an ink jet printer or the like by a camera, and for determining whether printing is good or not.
Background
Printing devices such as ink jet printers are legally obligated to display the date of production, the shelf life, the production lot number, and the like on packaging containers for food and medicine. The printing device is provided on a conveying line (including a packaging line) and prints packaging containers conveyed one by one. Whether printing by the printing device has been correctly performed is determined by a printing inspection device that reads printing of the packaging container.
As a background technique of this printing inspection apparatus, japanese patent laid-open No. 2003-168119 (patent document 1) is known. Patent document 1 describes "a step of performing expansion imaging of an obtained dot image and a step of projecting the expanded image in the direction of dot pattern arrangement are repeated for an identification target in which a plurality of dot patterns are arranged until a number of projection images corresponding to the number of dot patterns constituting the arrangement of the identification target can be obtained, thereby obtaining the boundaries between the characters from the plurality of dot patterns. Then, based on the finally obtained projection image, the dot pattern on the image is cut out, the cut-out dot patterns are compared with the registered model patterns, and the comparison results are integrated to determine whether the character string is appropriate or not.
Documents of the prior art
Patent document
Disclosure of Invention
Problems to be solved by the invention
Means for solving the problems
In order to solve the above problems, for example, the structure described in the scope of patent protection is adopted. The present application includes a plurality of means for solving the above-described problems, and as one example, there is a print inspection method for cutting each print character from an image obtained by imaging a recognition target in which print characters composed of dot patterns are arranged to determine the quality of the print character, the method including: an imaging step of imaging the recognition target every time a dot pattern of 1 character amount is printed on the printed matter; an image extraction processing step of extracting a print image of a character to be inspected from the image captured in the capturing step; a numerical value calculation step of calculating a degree of coincidence between the print image of the character to be determined obtained in the image extraction processing step and a character pattern registered in advance as a reference character pattern; and a determination step of comparing the numerical value obtained in the numerical value calculation step with a threshold value set in advance for determining whether the print quality of the character to be determined is acceptable or not, and determining whether the print quality is acceptable or not.
Effects of the invention
According to the present invention, it is possible to provide a print inspection method and apparatus capable of performing a contrast inspection of a print character by cutting each inspection target character from a print character string even when the distance between characters is substantially the same as the distance between adjacent dots within 1 character or is shorter than the distance between adjacent dots within 1 character.
Drawings
Fig. 1 is a diagram showing an example of installation of a printing inspection apparatus in example 1.
Fig. 2 is a block diagram of the printing inspection apparatus in embodiment 1.
Fig. 3 is a diagram for explaining a printing inspection method of the printing inspection apparatus in embodiment 1.
Fig. 4 is a diagram illustrating a conventional printing inspection method.
Fig. 5 is a diagram for explaining the image acquisition timing of the printing inspection apparatus in example 1.
Fig. 6 is a diagram for explaining a printing inspection method of the printing inspection apparatus in embodiment 2.
Fig. 7 is a block diagram of a printing inspection apparatus in embodiment 3.
Detailed Description
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Example 1
Fig. 1 is an example of the installation of the printing inspection apparatus used in the present embodiment. In fig. 1, the printing inspection apparatus is composed of the following parts: an illumination device 4 that irradiates light with a sufficient amount of light required for the camera 3 to read a printed character on a printed matter 6 on which a packaging container for food or medicine is printed by a printing device such as an inkjet printer 21; a camera 3 which is an imaging means for reading an image including a character string as an inspection target of the printed matter 6 to which light is irradiated; a monitor 2 for displaying the read image, setting conditions for performing an inspection, and displaying an inspection result; a print inspection apparatus main body 1 mounted with a print inspection processing unit that performs processing such as extracting a print image from an image read by the camera 3 and determines whether or not a character to be inspected is acceptable, and an illumination control unit that controls the amount of illumination, timing, and the like; and an external device that provides various instructions such as image processing to a print inspection processing unit in the print inspection apparatus main body 1.
In a production plant for plastic bottled beverages, cans, and the like, the quality guarantee period, production number, and the like are printed by ejecting droplets 9 from a print head 22 of a dedicated ink jet printer 21 onto the surface of a bottle or can of a product before shipment. The product before shipment printed by the inkjet printer 21 is conveyed by the conveyor belt 5 or the like, and if the product is conveyed to a position where the inspection target character can be confirmed by the camera 3, the illumination device 4 such as LED illumination or the like irradiates light, an image including the inspection target character is read by the camera 3, and the print image is transmitted to the print inspection device main body 1.
The printing inspection apparatus main body 1 registers a dot pattern having a good printing state as a reference character pattern for a character to be recognized in advance. The printing inspection apparatus main body 1 first performs a process of cutting out each character from the read image, and compares the cut-out print image of each character with a reference character pattern corresponding to each character, thereby determining whether the print state of each character to be determined is appropriate. If it is determined that the printing state is defective, the printing state is excluded from the shipment target.
Fig. 2 shows an example of a block diagram of the printing inspection apparatus in the present embodiment. In fig. 2, the printing inspection processing unit 11 in the printing inspection apparatus main body 1 performs various processes related to the printing inspection such as an imaging timing calculation unit 111, an image difference extraction processing unit 112, an image improvement processing unit 113, a numerical value calculation unit 114, and a character quality determination unit 115 for 1 character per printing. The print inspection processing unit 11 is executed by the CPU through software processing, but may be executed by dedicated hardware.
First, if the print inspection processing section 11 in the print inspection apparatus main body 1 acquires a signal of the ejection timing of droplets from the inkjet printer 21, the input timing of a print image is calculated by the imaging timing calculation section 111 for every 1 character printed in the print inspection processing section 11, the image acquisition timing is notified to the camera 3 from the image input signal generation section 16 in accordance with an instruction from the print inspection processing section 11, and the light amount of the illumination device 4 is controlled by the illumination control section 18 in accordance with an instruction from the print inspection processing section 11, and the light emission timing of the illumination device 4 is controlled in accordance with the image reading timing of the camera 3.
The image read by the camera 3 is input to an image input unit 14 in the printing inspection apparatus main body 1, and is temporarily stored in an image storage unit 15. The difference extraction processing unit 112 of the image in the printing inspection processing unit 11 performs a cutting process of extracting each inspection target character in the present embodiment from the captured image stored in the image storage unit 15, and performs image improvement such as noise removal of the cut character image in the image improvement processing unit 113. The image difference extraction processing unit 112 and the image improvement processing unit 113 may be collectively referred to as an image extraction processing unit that extracts a print image of a character to be determined.
The ROM12 stores programs for recognition processing of print character strings and for determining whether or not the print quality is acceptable. The RAM13 stores reference character patterns of the constituent characters of the character string to be inspected, setting data input from the external device 7, and the like. After the image improvement processing performed by the image improvement processing unit 113 in the printing inspection processing unit 11, the numerical value calculation unit 114 in the printing inspection processing unit 11 calculates the degree of matching between the print image and the reference character pattern in accordance with a program stored in the ROM 12. Then, the character quality determination unit 115 in the print inspection processing unit 11 performs comparison and determination processing between the read print image and the reference character pattern stored in the RAM13 in accordance with the program stored in the ROM12 in accordance with the conditions stored in the RAM 13.
In the above series of processes, the print image, the inspection condition, the inspection result, and the like are displayed on the monitor 2 from the input/output unit 17.
Fig. 3 shows an example of a printing inspection method according to the present embodiment. This embodiment will explain a case where 3 characters of ABC are printed and whether the printing quality of the 3 characters is acceptable or not is determined. The horizontal character string shown in fig. 3(1) at the upper stage of fig. 3 shows a case where the distance between characters is larger than the distance between points within 1 character, and the horizontal character string shown in fig. 3(2) at the lower stage of fig. 3 shows a case where the distance between characters a and B is substantially the same as the distance between points within 1 character. In either case, first, the 1 st image is read after the character a is printed and before the character B is printed. The obtained image is fig. 3 (a). Next, the 2 nd image is read after the character B is printed and before the character C is printed. The obtained image is fig. 3 (B). Finally, the 3 rd image is read after the character C is printed. The obtained image is fig. 3 (C). In this manner, an image is read every time 1 character is printed, and an image of the number of characters is acquired.
Next, image processing is performed on these images to cut out a print image of the determination target character for every 1 character. First, the selected image (a) is a print image of the inspection target character a. Next, the print image of the inspection target character B is set as the print image of the inspection target character B by acquiring the difference between the read image (B) and the read image (a), deleting the part of the character a that is the image common to the image (a) and the image (B), and leaving the part of the character B. Similarly, the inspection target character C is also set as a print image of the judgment target character C because a difference between the read image (C) and the read image (B) is obtained, a part of the character AB, which is an image common to the image (B) and the image (C), is deleted, and a part of the character C remains. By these processes, as shown in fig. 3(D), the print image of the determination target character can be cut for each 1 character.
Then, the cut-out print image is compared with the image of the reference character pattern stored in advance in the RAM13 in the printing inspection apparatus, and the degree of matching is calculated by the numerical value calculation unit 114. The character quality determination unit 115 compares the numerical value obtained by the numerical value calculation unit 114 with a threshold value stored in the RAM13 for determining whether the print quality of the inspection target character is acceptable or not, and determines whether the print quality is acceptable or not.
Here, a description is made of an existing example of a cutting method of a print character according to fig. 4. Similarly to fig. 3, the horizontal character string shown in fig. 4(1) at the upper stage of fig. 4 shows a case where the distance between characters is larger than the distance between adjacent dots within 1 character, and the horizontal character string shown in fig. 4(2) at the lower stage of fig. 4 shows a case where the distance between characters a and B is substantially the same as the distance between adjacent dots within 1 character. First, after the character "ABC" is printed, a print image of the character string is read. The read image is fig. 4 (a). Next, when cutting out the print characters, the expansion process is performed as an image process for clarifying the position between the characters. After the expansion processing, since a position where the projection distribution projected in the direction perpendicular to the character string is broken is determined as a position between characters, the image processing for expanding each point is performed so that the projection distribution of adjacent points within 1 character is not broken. The image subjected to the expansion processing is shown in fig. 4 (B). After the image processing of fig. 4(B), character cutting is performed with the position where the projection distribution is broken as the position between characters, but as shown in fig. 4(C), in the case of fig. 4(1) in the upper stage of fig. 4 where the distance between characters is larger than the distance between adjacent points within 1 character, the character can be divided into 3 characters of A, B, C, but in fig. 4(2) in the lower stage of fig. 4 where the distance between characters a and B is substantially the same as the distance between adjacent points within 1 character, although the character C can be cut, the position cannot be clearly broken between the character a and the character B, and the character AB is determined as one character, and the characters a and B cannot be divided into separately.
As described above, although the conventional example has a case where character cutting cannot be performed depending on the printed state, according to the present embodiment, as shown in fig. 3, it is possible to provide a printing inspection apparatus which can perform character cutting for 1 character and can determine whether the print quality is acceptable or not, not only in the case where there is a sufficient inter-character distance as shown in fig. 3(1) but also in the case where the inter-character distance is short as shown in fig. 3 (2).
In the present embodiment, since it is necessary to read an image every time 1 character is printed, it is necessary to correctly grasp the character reading timing. Therefore, a method of setting the character reading timing in the present embodiment will be described with reference to fig. 5.
Fig. 5(a) is a schematic diagram of the device configuration. Although the droplets 9 are ejected from the nozzles provided in the print head 22 of the ink jet printer 21 and land on the printed matter 6 to form characters, the delay time from when the droplets 9 leave the nozzles until they land varies depending on the gap 10 between the print head and the printed matter. Therefore, the gap 10 between the print head and the printed matter is input to the inkjet printer 21, and the delay time until the drop is stored. In the present embodiment, the delay time until the ink drops is stored in the storage unit of the ink jet printer, but the delay time may be stored in the print inspection apparatus, or a storage apparatus may be separately prepared.
The timing of printing start is performed by a detection signal of a sensor 8 provided in a transport device such as the conveyor belt 5. The ink jet printer 21 used in the present embodiment employs a so-called continuous type which always ejects droplets at a constant cycle from a nozzle of a head, and causes the droplets not to land on the printed matter 6 to be recovered by a recovery portion located in a print head of the ink jet printer 21, deflects the droplets intended to land on the printed matter 6 in a direction not to be recovered to the recovery portion, and lands on the printed matter 6. In the continuous ink jet printer 21, droplet ejection is performed at a constant cycle in accordance with a dot clock signal.
Fig. 5(B) shows a timing chart. As shown in fig. 5(B), if the ink jet printer 21 acquires the detection signal from the sensor 8, the software processing for setting the printing conditions for printing the character string and the like is performed for a predetermined time, and then printing is started. The dot clock signal is counted with the software processing end time as the print dot count start timing, and a trigger signal that notifies the imaging timing every time the dot count of 1 character is sent from the inkjet printer 21 to the print inspection apparatus. Here, the trigger signal is generated at the timing of the rise of the dot clock signal, for example. The timing at which image reading is actually started is after the delay time from the transmission of the trigger signal until the drop calculated from the gap 10 between the print head and the printed matter that was initially set. The trigger signal is transmitted by the number of characters constituting the character string, and the image acquisition by the camera 3 is performed by the printing inspection apparatus after the time from the transmission of the trigger signal to the addition of the delay time. As described above, by setting the image reading timing, an image can be acquired for every 1 character.
Further, if the image acquisition by the camera is possible for 1 character, it is not necessary to obtain the difference between the captured images before and after the inspection target character is printed, and the image extraction processing unit may extract only the print image of the inspection target character from the image captured by the imaging unit.
As described above, the present embodiment is a print inspection method for determining the quality of a print character by cutting each print character from an image obtained by imaging a recognition target in which the print character composed of a dot pattern is arranged, the method including the steps of: an imaging step of imaging the recognition target every time a dot pattern of 1 character amount is printed on the printed matter; an image extraction processing step of extracting a print image of a character to be inspected from the image captured in the capturing step; a numerical value calculation step of calculating a degree of coincidence between the print image of the character to be determined obtained in the image extraction processing step and a character pattern registered in advance as a reference character pattern; and a determination step of comparing the numerical value obtained in the numerical value calculation step with a threshold value set in advance for determining whether the print quality of the character to be determined is acceptable or not, and determining whether the print quality is acceptable or not.
In addition, it is assumed that the image extraction processing step extracts, as a print image of a character to be inspected, an image obtained by obtaining a difference between a captured image immediately before printing of a character whose print quality needs to be determined and a captured image immediately after printing of a corresponding character, with respect to an image captured in the capturing step.
The printing inspection apparatus main body for cutting each print character from an image obtained by imaging a recognition target in which the print characters composed of dot patterns are arranged to determine the print quality includes: an imaging timing calculation unit that calculates an imaging timing for printing 1 character each; an image input signal generation unit that generates an image acquisition timing for an external imaging unit based on the imaging timing calculated by the imaging timing calculation unit; an image input unit that acquires an image captured by the imaging unit; an image storage unit that stores the image acquired by the image input unit; an image extraction processing unit that extracts a print image of a character to be inspected from the captured image stored in the image storage unit; a numerical value calculation unit that calculates a degree of coincidence between the dot pattern of the determination target character obtained in the image extraction processing unit and a dot pattern registered in advance as a reference character; and a character quality determination unit that compares the numerical value obtained by the numerical value calculation unit with a threshold value set in advance for determining whether the print quality of the target character is acceptable or not, and determines whether the print quality is acceptable or not.
The image extraction processing unit extracts, as a print image of a character to be determined, an image obtained by obtaining a difference between a captured image immediately before printing of a character whose print quality needs to be determined and a captured image immediately after printing of the corresponding character, with respect to the captured image stored in the image storage unit.
The printing inspection apparatus main body is configured to cut each print character from an image obtained by imaging a recognition target in which the print characters composed of dot patterns are arranged, and determine the printing quality, and includes: an image input unit that acquires an image captured by an external imaging unit; an image storage unit that stores the image acquired by the image input unit; a print inspection processing unit that performs signal processing on the captured image stored in the image storage unit and determines whether the print quality is acceptable or not; and an image input signal generating unit that generates an image acquisition timing for an external imaging unit, wherein the image input signal generating unit generates the image acquisition timing every time a dot pattern of 1 character is printed on a printed matter.
Therefore, according to the present embodiment, it is possible to provide a print inspection apparatus which can perform character cutting for each 1 character and can determine whether print quality is acceptable or not, not only in the case where there is a sufficient inter-character distance of characters to be determined of a print image, but also in the case where the inter-character distance is short.
Example 2
This embodiment describes an example of a printing inspection apparatus effective for cutting out a character to be determined in a printed image even when stains or the like are present on the printing inspection apparatus side for inspecting a container or the like of a printed character.
Fig. 6 is a diagram for explaining a printing inspection method of the printing inspection apparatus in this embodiment. Fig. 6 shows a case where the printed character is 3 characters, ABC, and the distance between characters a and B is substantially the same as the distance between dots within 1 character, as in fig. 3 (2). In fig. 6, first, before printing a character, an image of a range in which a character string is printed is taken. The obtained image is fig. 6 (a). As shown in fig. 6(a), if stains or the like are present in the predetermined range for character string printing, the stains are acquired in the image. Next, after the character a is printed, the 2 nd image is read before the character B is printed. The obtained image is fig. 6 (B). Likewise, the 3 rd image is read after the character B is printed, and before the character C is printed. The obtained image is fig. 6 (C). Finally, after the character C is printed, the 4 th image is read. The obtained image is fig. 6 (D). In this manner, the image before printing and the image of 1 character per print are read, and an image in which the number of characters is increased by 1 is obtained. From these images, characters to be subjected to a contrast check are extracted for each character by image processing. First, by obtaining the difference between the image (B) and the image (a) for the character a, the position of the smear, which is the common image between the image (a) and the image (B), can be deleted, and only the character a can be extracted as the image of the character a to be inspected. By obtaining the difference between the image (C) and the image (B) for the character B, the position of the smear and the character a, which are the common images of the image (B) and the image (C), can be deleted, and only the character B can be extracted as the image of the character B to be inspected. Further, by obtaining the difference between the image (D) and the image (C) for the character C, the position of the smear and the character A, B, which are the common images of the image (C) and the image (D), can be deleted, and only the character C can be extracted as the image of the character C to be inspected. By these processes, as shown in fig. 6(E), a print image of the judgment target character can be cut for every 1 character.
As above, the structure of the present embodiment is: in the image capturing step, before the first 1 character is printed, an area including a range in which a character string to be recognized is printed is captured, the captured image is used as a background image, and a difference between an image captured after the printing of each subsequent character and the background image is acquired.
Thus, according to the present embodiment, even when stains or the like are present on the printing inspection apparatus side of a container or the like to be inspected by reading an image before printing, a contrast inspection can be performed with respect to all inspection characters, with only the character portion from which the stain portion is removed being the inspection target.
Example 3
In this embodiment, an example of a printing inspection apparatus effective for downsizing of the apparatus and ease of installation of the apparatus will be described.
Fig. 7 is a block diagram of the printing inspection apparatus in this embodiment. In fig. 7, a portion related to printing and a portion related to printing inspection are provided in the printing inspection apparatus main body 1.
The printing inspection processing unit 11 performs various processes related to printing, such as a print data processing unit 116 and a print timing calculation unit 117, which are printing apparatuses, and also performs various processes related to printing inspection, such as an imaging timing calculation unit 111, an image difference extraction processing unit 112, an image improvement processing unit 113, a numerical value calculation unit 114, and a character quality determination unit 115, which are print inspection apparatuses, for each 1 character printed.
The monitor 2 displays information necessary for checking the setting of the printing conditions and contents in a series of processes performed by the printing apparatus, or information necessary for checking the printing images, the checking conditions, the checking results, and the like in a series of processes performed by the printing checking apparatus.
The camera 3 and the print head 22 are integrally formed so as to be adjustable in position, and are connected to the printing inspection apparatus main body 1 as a device housed in 1 rack. Therefore, the positional relationship of the camera 3 and the print head 22 can be maintained fixed after that as long as the positional relationship is set once.
First, the print data processing unit 116 in the print inspection processing unit 11 sets the content of the character string printed by the printing unit, the printing conditions, and the like. If the detection signal from the sensor 8 is received, after a predetermined time according to the delay time calculated by the printing timing calculation section 117 in the printing inspection processing section 11 has elapsed, the ink supplied from the ink supply section 23 is ejected as droplets from the print head 22, and the print is printed with the shelf life, the production number, and the like.
Further, in the print inspection processing section 11, there is an imaging timing calculation section 111 for 1 character per print, and here, the input timing of the print image is calculated, and the image acquisition timing is notified from the image input signal generation section 16 to the camera 3 in accordance with an instruction from the print inspection processing section 11, and the illumination control section 18 controls the light amount of the illumination device 4 and controls the light emission timing of the illumination device 4 in accordance with the image reading timing of the camera 3 in accordance with an instruction from the print inspection processing section 11. The operation thereafter is the same as that described with reference to fig. 2.
As described above, the present embodiment is a print inspection apparatus main body in which the print inspection apparatus main body and the printing apparatus are integrally formed in 1 rack and the print inspection apparatus main body and the monitor used in the printing apparatus are shared.
The printing inspection apparatus includes the printing inspection apparatus main body and a print head that ejects liquid droplets and is formed integrally with an imaging unit and a printing apparatus in one frame, and the imaging unit images an object to be recognized every time printing of 1 character is performed based on an image acquisition timing from an image input signal generating unit.
Therefore, according to the present embodiment, the printing apparatus and the printing inspection apparatus are integrally formed in 1 rack, and the monitor of the printing apparatus and the printing inspection processing section 11 are shared, so that miniaturization is easy to achieve, and the print head 22 and the camera 3 are integrally formed in 1 rack, so that the positional relationship between the print head 22 and the camera 3 can be constantly and fixedly maintained as long as the rack is set once, and setting of the delay time is easy.
The present invention is not limited to the above-described embodiments, and various modifications are possible. For example, in the above-described embodiment, the image is taken and read every 1 character is printed, but the image is not limited to 1 character, and the image may be taken before and after printing of the standard character such as the expiration date and the production lot number and may be used as the inspection target.
The method of setting the image reading timing is performed by inputting the gap between the inkjet printer head and the printed matter, the sensor signal, and the dot clock of the inkjet printer used in the present embodiment, but any method can be considered as the same as the present embodiment as long as the end timing of the dot pattern of 1 character and the delay time from the start of droplet ejection until the droplet is landed on the printed matter can be recognized.
The above-described embodiments are described in detail for the purpose of facilitating understanding of the present invention, and are not limited to the embodiments having all the configurations described. In addition, a part of the structure of one embodiment may be replaced with the structure of another embodiment, or the structure of one embodiment may be added to the structure of another embodiment. In addition, deletion, and replacement of other configurations may be performed for a part of the configurations of the embodiments.
Description of the symbols
1: printing inspection apparatus main body, 2: monitor, 3: camera, 4: lighting device, 5: conveyor belt, 6: printed matter, 7: external device, 8: sensor, 9: droplet, 10: gap between printer head and printed matter, 11: print inspection processing unit, 12: ROM, 13: RAM, 14: image input unit, 15: image storage unit, 16: image input signal generation unit, 17: input/output unit, 18: illumination control unit, 21: inkjet printer (IJP), 22: print head, 23: ink supply unit, 111: imaging timing calculation unit for 1 character printing, 112: image difference extraction processing unit, 113: image improvement processing unit, 114: numerical value calculation unit, 115: character quality determination unit, 116: print data processing unit, 117: a printing timing calculation unit.
Claims (10)
1. A print inspection method for determining the quality of a print character by cutting each print character from an image obtained by imaging a recognition target in which the print character composed of a dot pattern is arranged, the method comprising:
an imaging step of imaging the recognition target every time a dot pattern of 1 character amount is printed on the printed matter;
an image extraction processing step of extracting a print image of a character to be inspected from the image captured in the capturing step;
a numerical value calculation step of calculating a degree of coincidence between the print image of the character to be determined obtained in the image extraction processing step and a character pattern registered in advance as a reference character pattern; and
a determination step of comparing the numerical value obtained in the numerical value calculation step with a threshold value set in advance for determining whether or not the print quality of the character to be determined is acceptable,
the image extraction processing step extracts, as a print image of a character to be inspected, an image obtained by obtaining a difference between a captured image immediately before printing of a character whose print quality is to be determined and a captured image immediately after printing of the corresponding character, with respect to the image captured in the capturing step.
2. The printing inspection method according to claim 1,
in the image capturing step, before the first 1 character is printed, an area including a range in which a character string to be recognized is printed is captured, the captured image is used as a background image, and a difference between an image obtained by capturing images after the printing of each subsequent character and the background image is acquired.
3. A printing inspection apparatus main body for judging printing quality by cutting each printed character from an image obtained by imaging a recognition target in which the printed characters composed of dot patterns are arranged, the printing inspection apparatus main body comprising:
an imaging timing calculation unit that calculates an imaging timing for printing 1 character each;
an image input signal generating unit that generates an image acquisition timing for an external imaging unit based on the imaging timing calculated by the imaging timing calculating unit;
an image input unit that acquires an image captured by the imaging unit;
an image storage unit that stores the image acquired by the image input unit;
an image extraction processing unit that extracts a print image of a character to be inspected from the captured image stored in the image storage unit;
a numerical value calculation unit that calculates a degree of coincidence between the dot pattern of the character to be determined obtained by the image extraction processing unit and a dot pattern registered in advance as a reference character; and
a character quality determination unit that compares the numerical value obtained by the numerical value calculation unit with a preset threshold value for determining whether the print quality of the target character is acceptable or not, and determines whether the print quality is acceptable or not,
the image extraction processing unit extracts, as a print image of a character to be determined, an image obtained by obtaining a difference between a captured image immediately before printing of a character whose print quality needs to be determined and a captured image immediately after printing of the corresponding character, with respect to the captured image stored in the image storage unit.
4. The printing inspection apparatus main body according to claim 3,
the printing inspection apparatus main body and the printing apparatus are integrally formed in 1 rack, and a monitor used by the printing inspection apparatus main body and the printing apparatus is shared.
5. A printing inspection apparatus is characterized in that,
comprising: the printing inspection apparatus main body of claim 3; and
and an imaging unit that images the recognition target every time printing of 1 character is performed based on the image acquisition timing from the image input signal generation unit.
6. The print inspection apparatus according to claim 5,
the printing inspection apparatus further includes:
and a monitor for displaying the photographed image, the inspection condition, and the inspection result.
7. The printing inspection apparatus according to claim 5 or 6,
the printing inspection apparatus main body is provided with an illumination control unit for controlling the light quantity and the light emission timing of an external illumination device,
the printing inspection apparatus further includes an illumination device controlled by the illumination control unit.
8. The printing inspection apparatus according to claim 5 or 6,
the printing inspection apparatus main body has an input/output unit for outputting a signal to an external monitor and inputting inspection conditions.
9. A printing inspection apparatus is characterized by comprising:
the printing inspection apparatus main body of claim 4; and
and a device in which a photographing unit and a print head of the printing device that ejects liquid droplets are integrally formed in 1 frame, the photographing unit photographing the recognition target every time printing of 1 character amount is performed based on the image acquisition timing from the image input signal generating section.
10. A printing inspection apparatus main body for cutting each print character from an image obtained by imaging a recognition target in which the print characters composed of dot patterns are arranged to determine printing quality, comprising:
an image input unit that acquires an image captured by an external imaging unit;
an image storage unit that stores the image acquired by the image input unit;
a print inspection processing unit that performs signal processing on the captured image stored in the image storage unit and determines whether or not the print quality is acceptable; and
an image input signal generating section which generates an image acquisition timing for an external photographing unit,
the image input signal generating section generates the image acquisition timing every time a print object is printed with a dot pattern of 1 character,
an image extraction processing unit of the print inspection processing unit extracts, as a print image of a character to be determined, an image obtained by subtracting a difference between a captured image immediately before printing of a character whose print quality is to be determined and a captured image immediately after printing of the corresponding character, from the captured image stored in the image storage unit.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2015-067422 | 2015-03-27 | ||
| JP2015067422A JP6675831B2 (en) | 2015-03-27 | 2015-03-27 | Print inspection method, print inspection apparatus using the same, and print inspection apparatus main body |
| PCT/JP2016/054634 WO2016158057A1 (en) | 2015-03-27 | 2016-02-18 | Print inspection method, print inspection device using same, and print inspection device body |
Publications (2)
| Publication Number | Publication Date |
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| CN107408289A CN107408289A (en) | 2017-11-28 |
| CN107408289B true CN107408289B (en) | 2020-12-25 |
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| CN201680015365.9A Active CN107408289B (en) | 2015-03-27 | 2016-02-18 | Printing inspection method, printing inspection apparatus using the same, and printing inspection apparatus main body |
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| Country | Link |
|---|---|
| JP (1) | JP6675831B2 (en) |
| CN (1) | CN107408289B (en) |
| WO (1) | WO2016158057A1 (en) |
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| JP6962228B2 (en) * | 2018-02-14 | 2021-11-05 | セイコーエプソン株式会社 | Image quality inspection camera system, printing device and light source adjustment method |
| JP7092563B2 (en) * | 2018-06-08 | 2022-06-28 | マクセルフロンティア株式会社 | Printing inspection machine |
| EP3862913A4 (en) * | 2018-10-01 | 2022-07-06 | Hitachi Industrial Equipment Systems Co., Ltd. | Printing inspection device |
| JP6823839B2 (en) * | 2019-06-17 | 2021-02-03 | 大日本印刷株式会社 | Judgment device, control method of judgment device, judgment system, control method of judgment system, and program |
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Also Published As
| Publication number | Publication date |
|---|---|
| WO2016158057A1 (en) | 2016-10-06 |
| JP6675831B2 (en) | 2020-04-08 |
| CN107408289A (en) | 2017-11-28 |
| JP2016186766A (en) | 2016-10-27 |
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