JP6675831B2 - Print inspection method, print inspection apparatus using the same, and print inspection apparatus main body - Google Patents

Description

  The present invention relates to a printing inspection method and an apparatus therefor, and in particular, the date and time of manufacture, characters and symbols such as a serial number printed on packaging containers for food and medicine by an inkjet printer or the like (hereinafter, the symbols are also included in the characters, The present invention relates to a method and an apparatus for inspecting a printed character suitable for determining whether or not a printed character is good by reading a "character" with a camera.

  Labeling of the date of manufacture, expiration date, manufacturing lot, and the like is required by law for packaging containers for foods and medicines, and a printing device such as an ink jet printer realizes this. The printing device is installed on a transport line (including a packaging line) and performs printing on packaging containers that are transported one after another. Whether the printing by the printing device is performed correctly is performed by a printing inspection device that reads the printing on the packaging container.

  Japanese Patent Application Laid-Open No. 2003-168119 (Patent Document 1) discloses a background art of the print inspection apparatus. Japanese Patent Application Laid-Open No. H11-163873 describes "a step of expanding a dot image obtained by imaging a recognition target in which a plurality of dot patterns are arranged, and a step of projecting the expanded image in an arrangement direction of the dot pattern. This step is repeated until the number of projected images corresponding to the number of dot patterns constituting the recognition target array is obtained, so that boundaries between characters can be obtained from a plurality of dot patterns. Then, based on the finally obtained projection image, a dot pattern on the image is cut out, and each cut out dot pattern is compared with the registered model pattern, and each matching result is integrated to determine whether the character string is appropriate. Can be determined. "

JP 2003-168119 A

  In Patent Document 1, for a recognition target in which a plurality of dot patterns are arranged, a step of expanding a dot image obtained by imaging is performed until adjacent dots in one character are combined. A method is described in which a portion where dots are separated at that time is recognized as a boundary between characters, and a character to be inspected can be cut out. The print inspection method disclosed in Japanese Patent Application Laid-Open No. H11-157572 discloses a method in which the distance between dots to be recognized as belonging to different characters (the distance between printed characters) is significantly larger than the distance between dots to be recognized as one character. Is an effective method. However, when the distance is short, if the expansion processing is performed until the dots to be recognized as one character are combined, the characters are also combined and the character cannot be cut out for each character. Therefore, the present invention provides a plurality of dot patterns arranged even when the distance between printed characters is substantially equal to the distance between adjacent dots in one character or shorter than the distance between adjacent dots in one character. It is an object of the present invention to provide a print inspection method and apparatus capable of performing a character collation inspection by extracting each character from a recognition target.

  In order to solve the above problem, for example, a configuration described in the claims is adopted. The present application includes a plurality of means for solving the above-described problems, but to give an example, cut out each print character from an image obtained by imaging a recognition target in which print characters formed of a dot pattern are arranged. A print inspection method for determining the quality of a printed character, wherein an image of a recognition target is imaged every time a dot pattern of one character is printed on a printed matter, and an inspection is performed from an image captured in the image pickup process. An image extraction process for extracting a print image of a target character, and a numerical value for calculating the degree of coincidence between the print image of the determination target character obtained in the image extraction process and a character pattern registered in advance as a reference character pattern The numerical value obtained in the calculation step and the numerical value calculation step is compared with a predetermined threshold value for determining whether the print quality of the character to be determined is acceptable or not. A structure having a determination step of constant to.

  According to the present invention, even when the distance between characters is substantially equal to the distance between adjacent dots in one character or shorter than the distance between adjacent dots in one character, each test object It is possible to provide a print inspection method and apparatus capable of cutting out characters and performing collation inspection of printed characters.

FIG. 2 is a diagram illustrating an example of installation of a print inspection device according to the first embodiment. FIG. 2 is a block diagram of a print inspection device according to the first embodiment. FIG. 3 is a diagram illustrating a print inspection method of the print inspection device according to the first embodiment. FIG. 9 is a diagram showing a conventional print inspection method. FIG. 3 is a diagram for explaining an image capture timing of the print inspection apparatus according to the first embodiment. FIG. 9 is a diagram illustrating a print inspection method of the print inspection device according to the second embodiment. FIG. 13 is a block diagram of a print inspection device according to a third embodiment.

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

  FIG. 1 is an installation example of a print inspection device used in the present embodiment. In FIG. 1, a print inspection device irradiates a print 6 such as an ink jet printer 21 with a printing device 6 or the like on a food or medicine packaging container with light having an amount of light sufficient for reading printed characters by a camera 3. A lighting device 4; a camera 3 which is an image pickup means for reading an image including a character string to be inspected on the printed matter 6 irradiated with light; displaying the read image, setting inspection conditions, and displaying an inspection result; The monitor 2 performs a process such as extracting a printed image from an image read by the camera 3, and performs a print inspection processing unit that performs pass / fail judgment of a character to be inspected, and an illumination control unit that controls the amount and timing of illumination. It comprises a print inspection apparatus main body 1 mounted thereon, an external device for giving various instructions such as image processing to a print inspection processing section in the print inspection apparatus main body 1, and the like.

  In a manufacturing plant for beverages and canned beverages in PET bottles, the droplets 9 are ejected from the print head 22 of the dedicated ink jet printer 21 on the surface of the bottle or can of the product before shipment, and the expiration date and the serial number are printed. doing. The pre-shipment product printed by the inkjet printer 21 is conveyed by the conveyor 5 or the like, and when conveyed to a position where the camera 3 can confirm the characters to be inspected, the illumination device 4 such as an LED illumination irradiates light. Then, the image including the characters to be inspected is read by the camera 3, and the printed image is sent to the print inspection apparatus main body 1.

  In the printing inspection apparatus main body 1, a dot pattern having a good printing state is registered as a reference character pattern for a character to be recognized in advance. The print inspection apparatus main body 1 first performs a process of cutting out individual characters from the read image, and compares the print image of each cut out character with the corresponding reference character pattern, thereby printing each character to be determined. Determine the suitability of the state. Here, if the printing state is determined to be defective, it is excluded from shipping targets.

  FIG. 2 shows an example of a block diagram of a print inspection apparatus according to the present embodiment. In FIG. 2, a print inspection processing unit 11 in the print inspection apparatus main body 1 includes an imaging timing calculation unit 111 for each character printing, an image difference extraction processing unit 112, an image improvement processing unit 113, a numerical calculation unit 114, a character quality Various processes related to print inspection such as the determination unit 115 are performed. The print inspection processing unit 11 is performed by software processing by the CPU, but may be performed by dedicated hardware.

  First, when the signal of the ejection timing of the droplets is received from the inkjet printer 21 by the print inspection processing unit 11 in the print inspection apparatus main body 1, the imaging timing calculation unit 111 for each character print in the print inspection processing unit 11 prints. The image input timing is calculated, the image input signal generation unit 16 notifies the camera 3 of the image capture timing according to an instruction from the print inspection processing unit 11, and the illumination control unit 18 The light amount of the illumination device 4 is controlled, 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 the image input unit 14 in the print inspection apparatus main body 1 and is temporarily stored in the image storage unit 15. The image difference extraction processing unit 112 in the print inspection processing unit 11 performs a cutout process of extracting each inspection target character in the present embodiment from the captured image stored in the image storage unit 15, and performs processing for extracting the extracted character image. Image improvement such as noise removal is performed by the image improvement processing unit 113. Note that the difference extraction processing unit 112 and the image improvement processing unit 113 may be combined into an image extraction processing unit that extracts a print image of a character to be determined.

  The ROM 12 stores a program for a process of recognizing a print character string and determining whether print quality is acceptable or not. Further, the RAM 13 stores a reference character pattern of each constituent character of the character string to be inspected, setting data input from the external device 7, and the like. After the image improvement processing in the image processing unit 113 in the print inspection processing unit 11, the numerical calculation unit 114 in the print inspection processing unit 11 stores the degree of coincidence between the print image and the reference character pattern in the ROM 12. Perform the calculations according to the program. Then, based on the conditions stored in the RAM 13, the character quality determination unit 115 in the print inspection processing unit 11 performs a comparison / determination process between the read print image and the reference character pattern stored in the RAM 13, by the ROM 12. In accordance with the program stored in.

  In the above series of processing, 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 print inspection method according to the present embodiment. In the present embodiment, a case will be described in which three characters of ABC are printed, and whether or not the print quality of these three characters is acceptable. The horizontal character string shown in FIG. 3A in the upper part of FIG. 3 is a case where the distance between characters is larger than the distance between dots in one character, and FIG. 3B in the lower part of FIG. The horizontal character string shown by indicates the case where the distance between the characters A and B is substantially equal to the distance between the dots in one character. In any case, the first image is read after the character A is printed and before the character B is printed. FIG. 3A shows the obtained image. Next, the second image is read after the character B is printed and before the character C is printed. FIG. 3B shows the obtained image. Finally, after the character C is printed, the third image is read. The obtained image is shown in FIG. As described above, the image is read every time one character is printed, and the images corresponding to the number of characters are captured.

  Next, by performing image processing on these images, a print image of the character to be determined is cut out for each character. First, an image (A) is selected as the print image of the inspection target character A. Next, with respect to the print image of the inspection target character B, the difference between the read image (B) and the read image (A) is obtained to obtain a portion of the character A which is an image common to the image (A) and the image (B). Is deleted, and the portion of the character B remains. This is set as a print image of the inspection target character B. Similarly, by taking the difference between the read image (C) and the read image (B) for the inspection target character C, the character AB portion, which is an image common to the image (B) and the image (C), is deleted. Since the portion of the character C remains, this is set as a print image of the character C to be determined. Through these processes, as shown in FIG. 3D, a print image of the determination target character can be cut out for each character.

  Then, the cut print image is compared with the reference character pattern image stored in the RAM 13 in the print inspection apparatus in advance, and the degree of coincidence is calculated by the numerical value calculation unit 114. The numerical value obtained by the numerical value calculation unit 114 is compared with a threshold value stored in the RAM 13 by the character quality determination unit 115 for determining whether the print quality of the inspection target character is acceptable or not, thereby determining whether the print quality is acceptable. I do.

  Here, a conventional example of a print character cutting method will be described with reference to FIG. Similar to FIG. 3, the horizontal character string shown in FIG. 4A in the upper part of FIG. 4 is a case where the distance between characters is larger than the distance between adjacent dots in one character. The character string in the horizontal direction shown in FIG. 4B shows a case where the distance between the characters A and B is substantially equal to the distance between adjacent dots in one character. First, after printing the character "ABC", a print image of this character string is read. FIG. 4A shows the read image. Next, when cutting out print characters, an expansion process is performed as image processing for clarifying the position between characters. Image processing is performed to expand each dot so that the projected distribution of adjacent dots in one character is not cut off, since a point where the projection distribution projected in the direction perpendicular to the character string after the expansion processing is separated is determined as a position between characters. I do. FIG. 4B shows an image after the dilation processing is performed. After the image processing of FIG. 4B, the character is cut out with the position where the projection distribution is cut off as the position between the characters. As shown in FIG. 4C, the character is extracted from the distance between adjacent dots in one character. In the case of FIG. 4 (1) in the upper part of FIG. 4 where the distance between the characters is large, the character can be divided into three characters A, B, and C. In FIG. 4 (2) in the lower part of FIG. 4 which is almost the same as the inter-distance, the character C can be cut out, but the separation position between the characters A and B is not known, and the character AB is determined to be one character. Characters A and B cannot be split separately.

  As described above, in the conventional example, character cutout may not be performed depending on a printed state. However, according to the present embodiment, as shown in FIG. 3, the inter-character distance as shown in FIG. The present invention provides a print inspection apparatus capable of performing character cutout for each character and determining whether the print quality is acceptable or not, not only in the case where the distance is between the characters but also when the distance between the characters is short as shown in FIG. Can be.

  In the present embodiment, since it is necessary to read an image each time one character is printed, it is necessary to correctly grasp the character reading timing. Thus, how to set the character reading timing in the present embodiment will be described with reference to FIG.

  In FIG. 5, (A) shows a schematic diagram of the device configuration. The droplets 9 are ejected from the nozzles provided in the print head unit 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 exit the nozzles to when they land is determined by the delay time. And the gap 10 between the print head unit 22 and the printed matter 6. Then, the gap 10 is input to the ink jet printer 21 to store the delay time until landing. In the present embodiment, the delay time until landing is stored in the storage unit of the ink jet printer. However, a print inspection device or a separate storage device may be prepared.

  The timing of starting printing is determined by a detection signal of a sensor 8 installed in a conveyor such as the conveyor 5. The ink jet printer 21 used in the present embodiment always discharges droplets from the nozzles of the head unit at a constant cycle, and collects the liquid droplets that do not land on the printed matter 6 in the collecting unit in the head of the ink jet printer 21. A so-called continuous type, in which the droplets to be landed on the printed matter 6 are deflected in a direction not collected by the collecting unit and landed on the printed matter 6, was used. In the continuous type ink jet printer 21, droplets are discharged at a constant cycle in accordance with a dot clock signal.

  FIG. 5B shows a timing chart. As shown in FIG. 5B, upon receiving the detection signal from the sensor 8, the inkjet printer 21 performs a software process for setting a printing condition of a printing character string and the like for a predetermined time, and then starts printing. The dot clock signal is counted using the software processing end time as the print dot count start timing, and a trigger signal indicating the imaging timing is transmitted from the inkjet printer 21 to the print inspection device every time the number of dots for one character is counted. Here, the trigger signal is generated, for example, at the rising timing of the dot clock signal. The timing of actually starting the image reading is after a delay time from the transmission of the trigger signal to the landing calculated from the gap 10 initially set. The trigger signal is transmitted for the number of characters constituting the character string, and the print inspection apparatus performs image capture by the camera 3 after a time that takes into account the delay time from the transmission of the trigger signal. By setting the image reading timing as described above, an image can be captured for each character.

  If the image capture by the camera can capture one character, there is no need to take the difference between the captured image immediately before and after the character to be inspected is printed, and the image extraction processing unit captures the image with the imaging unit. It is only necessary to extract the print image of the character to be inspected from the image.

  As described above, the present embodiment is a print inspection method that cuts out each print character from an image obtained by imaging a recognition target in which print characters formed of a dot pattern are arranged and determines the quality of the print character. An image pickup step of picking up an image of a recognition target every time a dot pattern of one character is printed on a printed matter, and an image for extracting a print image of a character to be inspected from the image picked up in the image pickup step An extraction processing step, a numerical calculation step of calculating the degree of coincidence between the printed 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 numerical calculation step obtained by the numerical calculation step. A determination step of comparing the numerical value with a preset threshold value 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;

  Further, the image extraction processing step includes, for the image captured in the imaging step, a captured image immediately before the relevant character is printed for a character whose print quality needs to be determined, and a captured image immediately after the relevant character is printed. An image obtained by taking the difference between the two is extracted as a print image of a character to be inspected.

  Further, a print inspection apparatus main body that cuts out each print character from an image obtained by imaging a recognition target in which print characters formed of a dot pattern are arranged, and determines print quality. An imaging timing calculation unit for calculating timing, an image input signal generation unit for generating an image capture timing in an external imaging unit based on the imaging timing calculated by the imaging timing calculation unit, and an image for capturing an image captured by the imaging unit An input unit, an image storage unit that stores an image captured by the image input unit, an image extraction processing unit that extracts a print image of a character to be inspected from a captured image stored in the image storage unit, and an image extraction processing unit A numerical calculation unit for calculating the degree of coincidence between the dot pattern of the character to be determined obtained in step 2 and the dot pattern registered as a reference character in advance, Values obtained by the calculation unit compares the threshold value for determining the acceptability of the print quality of the pre-set target characters, a configuration and a determining character quality determination unit acceptability of print quality.

  Further, the image extraction processing unit, for the captured image stored in the image storage unit, the captured image immediately before the relevant character is printed for the character for which the print quality needs to be determined, and the image immediately after the relevant character is printed An image obtained by taking a difference from a captured image is extracted as a print image of a character to be determined.

  In addition, a print inspection apparatus main body that cuts out each print character from an image obtained by imaging a recognition target in which print characters formed of a dot pattern are arranged and determines print quality, and which is imaged by an external imaging unit. Image input unit that captures the captured image, an image storage unit that stores the image captured by the image input unit, and print inspection processing that performs signal processing on the captured image stored in the image storage unit to determine whether print quality is acceptable. And an image input signal generating section for generating an image capture timing in an external image pickup means. The image input signal generating section outputs an image every time a dot pattern for one character is printed on a printed material. It is configured to generate a capture timing.

  Therefore, according to the present embodiment, not only when the inter-character distance of the character to be determined in the print image is sufficient, but also when the inter-character distance is short, it is possible to cut out each character. It is possible to provide a print inspection device capable of determining whether print quality is acceptable.

  The present embodiment describes an example of a print inspection apparatus that is effective for cutting out a determination target character of a print image even when the print inspection apparatus such as a container for inspecting print characters has dirt.

  FIG. 6 is a diagram illustrating a print inspection method of the print inspection apparatus according to the present embodiment. FIG. 6 shows a case where, as in FIG. 3 (2), the print characters are three characters of ABC, and the distance between characters A and B is substantially equal to the distance between dots in one character. In FIG. 6, first, before printing a character, an image of a range where a character string is printed is taken. FIG. 6A shows the obtained image. As shown in FIG. 6A, if there is dirt or the like in the range in which the character string is to be printed, the dirt is captured in the image. Next, the second image is read after the character A is printed and before the character B is printed. FIG. 6B shows the obtained image. Similarly, the third image is read after the character B is printed and before the character C is printed. FIG. 6C shows the obtained image. Finally, after the character C is printed, the fourth image is read. FIG. 6D shows the obtained image. As described above, the image before printing and the image for each character printing are read, and the number of characters plus one image is captured. From these images, characters to be subjected to collation inspection are extracted for each character by image processing. First, with respect to the character A, the difference between the image (B) and the image (A) is obtained, thereby removing a dirt portion which is an image common to the image (A) and the image (B). It can be taken out as an image of character A. For the character B, by taking the difference between the image (C) and the image (B), the dirt portion and the character A, which are images common to the image (B) and the image (C), are deleted, and only the character B is inspected. It can be extracted as an image of the target character B. In addition, by taking the difference between the image (D) and the image (C) for the character C, the dirt portion and the characters A and B, which are images common to the image (C) and the image (D), are deleted, and Only C can be extracted as an image of the inspection target character C. Through these processes, as shown in FIG. 6E, a print image of the determination target character can be cut out for each character.

  As described above, in the present embodiment, in the imaging step, before printing of the first character, an area including the range in which the character string to be recognized is printed is captured, and this captured image is used as the background image. Then, the difference between the image obtained by imaging after each subsequent character printing and the background image is obtained.

  Thus, according to the present embodiment, even if there is dirt on the side of the print inspection device such as a container to be inspected by reading an image before printing, all the inspection characters have characters other than the dirt portion removed. The collation inspection can be performed only on the part to be inspected.

  In the present embodiment, an example of a print inspection apparatus that is effective for reducing the size of the apparatus and facilitating the setting of the apparatus will be described.

  FIG. 7 is a block diagram of the print inspection apparatus according to the present embodiment. In FIG. 7, the print inspection apparatus main body 1 has a part related to printing and a part related to print inspection.

  The print 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 as a printing device, and also performs an imaging timing calculation unit 111 for each character printing as a print inspection device, Of the print inspection, such as a difference extraction processing unit 112, an image improvement processing unit 113, a numerical calculation unit 114, and a character quality determination unit 115.

  In the monitor 2, information necessary for confirming the setting of printing conditions and contents in a series of processes performed by the printing device, and inspection of print images, inspection conditions, inspection results, and the like in the series of processes performed by the print inspection device are performed. Required information is displayed.

  The camera 3 and the print head 22 are integrally formed so as to be position-adjustable, and are connected to the print inspection apparatus main body 1 as a device housed in one housing. Therefore, once the positional relationship between the camera 3 and the print head 22 is set, a constant positional relationship can be maintained thereafter.

  First, the print data processing unit 116 in the print inspection processing unit 11 sets the contents of a character string to be printed by the printing unit, printing conditions, and the like. When receiving the detection signal from the sensor 8, the ink supplied from the ink supply unit 23 is supplied to the print head 22 after a predetermined time according to the delay time calculated by the print timing calculation unit 117 in the print inspection processing unit 11. Are discharged as droplets, and the expiration date, the production number, and the like are printed on the printed matter.

  Further, in the print inspection processing unit 11, there is an imaging timing calculation unit 111 for each character printing. Here, the input timing of the print image is calculated, and the image input signal generation unit 16 is operated in accordance with an instruction from the print inspection processing unit 11. In addition to notifying the camera 3 of the image capturing timing, the illumination control unit 18 controls the amount of light of the illumination device 4 according to an instruction from the print inspection processing unit 11 and adjusts the illumination device 4 in accordance with the image reading timing of the camera 3. Control the light emission timing. The subsequent operation is the same as that described with reference to FIG.

  As described above, in the present embodiment, the print inspection apparatus main body and the printing apparatus are integrally formed in one housing, and the monitor used by the print inspection apparatus main body and the printing apparatus are shared. And

  In addition, based on the above-described print inspection apparatus main body and an image capturing timing from the image input signal generation unit, an image pickup unit that performs imaging of a recognition target every time printing of one character is performed, and a droplet of the printing apparatus. A print inspection device including a device in which a print head unit for discharging is integrally formed in one housing.

  Therefore, according to the present embodiment, the printing device and the print inspection device are integrally formed in one housing, and the monitor of the printing device and the print inspection device and the print inspection processing unit 11 are shared, so that the size is small. Since the print head 22 and the camera 3 are integrally formed in a single housing, once set in the housing, the positional relationship between the print head 22 and the camera 3 is always kept constant. The delay time can be easily set.

  Note that the present invention is not limited to the above-described embodiments, and includes various modifications. For example, in the above-described embodiment, an image is taken and an image is read each time one character is printed. However, the present invention is not limited to one character. Imaging may be performed before and after the printing of characters, and this may be set as an inspection target.

  The image reading timing was set by the input of the gap between the ink jet head and the print, the sensor signal, and the dot clock of the ink jet printer used in this embodiment. Any method capable of recognizing the timing and the delay time from the start of droplet discharge to landing on a printed matter can be regarded as a configuration equivalent to the present embodiment.

  Further, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described above. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of one embodiment can be added to the configuration of another embodiment. Further, for a part of the configuration of each embodiment, it is possible to add / delete / replace another configuration.

1: Print inspection apparatus main body, 2: Monitor, 3: Camera, 4: Illumination device, 5: Conveyor, 6: Printed matter, 7: External device, 8: Sensor, 9: Droplet, 10: Between head and printed matter , 11: print inspection processing section, 12: ROM, 13: RAM, 14: image input section, 15: image storage section, 16: image input signal generation section, 17: input / output section, 18: illumination control section, 21: inkjet printer (IJP), 22: print head, 23: ink supply unit, 111: imaging timing calculation unit for each 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: print timing calculation unit

Claims (10)

A print inspection method for cutting out each print character from an image obtained by imaging a recognition target in which print characters composed of dot patterns are arranged and determining the quality of the print character,
An imaging step of imaging a recognition target every time a dot pattern for one character is printed on a printed matter;
An image extraction processing step of extracting a print image of a character to be inspected from the image captured in the imaging step,
Numerical calculation step of calculating the degree of coincidence between the print image of the determination target character obtained in the image extraction processing step and a character pattern registered in advance as a reference character pattern,
The numerical value obtained in the numerical calculation step is compared with a threshold value for determining the pass / fail of the print quality of the character to be determined in advance , having a determination step of determining pass / fail of the print quality ,
The image extraction processing step includes, for the image captured in the imaging step, a captured image immediately before the relevant character is printed for a character whose print quality needs to be determined, and a captured image immediately after the relevant character is printed. A print inspection method for extracting an image obtained by taking a difference between the two as a print image of a character to be inspected. The print inspection method according to claim 1, wherein
In the imaging step, before the first character is printed, an area including a range in which a character string to be recognized is printed is captured, and the captured image is used as a background image, and then captured after each character is printed. And a difference between the image obtained as a result and the background image . A print inspection apparatus main body that cuts out each print character from an image obtained by imaging a recognition target in which print characters composed of dot patterns are arranged and determines print quality,
An imaging timing calculation unit that calculates an imaging timing for each character printing;
An image input signal generation unit that generates an image capture timing in an external imaging unit based on the imaging timing calculated by the imaging timing calculation unit;
An image input unit that captures an image captured by the imaging unit;
An image storage unit that stores an image captured 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 calculation unit that calculates the degree of coincidence between the dot pattern of the determination target character obtained by the image extraction processing unit and the dot pattern registered as a reference character in advance,
The numerical value obtained by the numerical calculation unit is compared with a preset threshold for determining the pass or fail of the print quality of the target character, having a character quality determination unit to determine the pass or fail of the print quality,
The image extraction processing unit, for the captured image stored in the image storage unit, a captured image immediately before the corresponding character is printed for a character whose print quality needs to be determined, and immediately after the corresponding character is printed A print inspection apparatus main body, wherein an image obtained by taking a difference from a captured image is extracted as a print image of a character to be determined. A print inspection apparatus main body according to claim 3,
An imaging unit that performs imaging of the recognition target each time printing of one character is performed based on an image capture timing from the image input signal generation unit;
A print inspection device comprising: A print-inspection equipment according to claim 4,
Furthermore, the captured image, inspection conditions, print-inspection equipment characterized by have a monitor for displaying the test results. The print inspection device according to claim 4 or 5 ,
The print inspection device main body has an illumination control unit that controls the light amount and the light emission timing of an external illumination device,
Furthermore, a printing inspection device having an illumination device controlled by the illumination control unit. The print inspection device according to any one of claims 4 to 6 , wherein
A print inspection apparatus, wherein the print inspection apparatus body has an input / output unit for outputting a signal to an external monitor and inputting an inspection condition . The print inspection apparatus main body according to claim 3 , wherein
The printing inspection apparatus to form the body with a printing device integrated into one casing, the printing inspection apparatus main body, characterized in that to share the monitor to be used in said printing inspection apparatus main body and the printing apparatus. A print inspection device main body according to claim 8 ,
An image pickup means for picking up the image of the recognition target every time one character is printed based on an image fetch timing from the image input signal generating unit, and a print head unit for ejecting droplets of the printing apparatus are provided as one unit. A device integrally formed in the housing;
A print inspection device comprising: A print inspection apparatus main body that cuts out each print character from an image obtained by imaging a recognition target in which print characters composed of dot patterns are arranged and determines print quality ,
An image input unit that captures an image captured by an external imaging unit;
An image storage unit that stores an image captured by the image input unit,
A print inspection processing unit that performs signal processing on the captured image stored in the image storage unit to determine whether print quality is acceptable,
Having an image input signal generation unit that generates an image capture timing in an external imaging unit,
The image input signal generation unit generates the image capture timing each time a dot pattern for one character is printed on a printed matter,
The print inspection processing unit, with respect to the captured image stored in the image storage unit, a captured image immediately before the corresponding character is printed for a character whose print quality needs to be determined, and immediately after the corresponding character is printed A print inspection apparatus main body , wherein an image obtained by taking a difference from a captured image is extracted as a print image of a character to be determined .

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