JPH03274153A - Automatic inspecting device for printing defects - Google Patents

Abstract

PURPOSE:To clean a printing roller effectively by inspecting printing defects certainly in good yield by a method wherein at least two items among inspection items for the number of total dots corresponding to pixels of a binary coded signal printing part, the number of group binding components, and the number of dots corresponding to pixels of a printing part of each block enclosing the printing part are compared with standard ranges, and a cleaning mechanism part is controlled by driving by a printing defect detecting signal. CONSTITUTION:A number of total dots inside a window W1 corresponding to pixels of a printing part detected from a binary coded signal read at detection synchronous signal timing from a binary coded frame memory 14, the number of bonding components, and the number of dots corresponding to pixels of a printing part of each divided block inside an inspection mask W2 are compared with three kinds of standard widths established with a standard width establishing part. When any one of inspected results of those three kinds of printing defects is outside the standard, a defect detecting signal is outputted. When a generating rate of this defect detecting signal becomes not less than the established value, a cleaning mechanism part K is operated.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is mainly concerned with the prevention of dropping, chipping, or tearing of characters or symbols indicating product names, expiration dates, etc. printed on solid preparations, cartons, bottles, etc. The present invention also relates to an automatic printing defect inspection device that can automatically inspect for the presence or absence of defects such as ink stains, and automatically clean a printing roller to eliminate the cause of defects based on the inspection results.

<Prior Art> Solid preparations such as tablets, capsules, and caplets, cartons, and drug containers are required by laws such as the Pharmaceutical Affairs Law to print and display the product name, loft number, expiration date, etc. A common printing method for these is to supply the printing ink from the ink reservoir to the printing roller by a design roller, and then the printing roller that contacts the supply drum transfers the printing material such as tablets that is fed by the supply drum. It is configured to transfer printing ink to perform desired printing.

In continuous printing using such transfer, excess ink may remain on the printing roller over time, resulting in printing stains, and the accumulation of fine powder from the printing substrate such as tablets may cause printing to become blurred, resulting in cut-off characters or omitted characters. Alternatively, printing defects such as missing characters may occur.

Therefore, various devices have been devised to automatically inspect the presence or absence of such printing defects. If defects are also detected, the yield will be reduced, and conversely, if the detection accuracy is lowered, the detection will be rough, making it impossible to reliably select defective products. Therefore, the reality is that an automatic printing defect inspection device that meets user needs has not been put into practical use, and printing defects are currently sorted out by visual inspection.

<Problems to be Solved by the Invention> However, in the aforementioned visual inspection for printing defects, there is a problem in that the inspection accuracy varies greatly due to individual differences and the printing quality is unstable. In addition, the inspection work is extremely inefficient and requires a large number of skilled inspectors, which is a factor in high costs.

On the other hand, in continuous printing by transfer, as mentioned above, excess ink remains on the printing roller or fine powder from the tablets accumulates over time, which causes printing defects, so the printing roller must be cleaned each time. The cause of printing defects cannot be removed unless Therefore, the same applicant as the present application,
He has devised a device that automatically cleans the printing roller (see Japanese Patent Laid-Open No. 10457/1983). However, since printing defects are visually inspected, it is not possible to automatically perform cleaning in conjunction with the inspection results of printing defects, and the printing operation must be automatically stopped and cleaned after a certain period of time. There is a risk that the efficiency of printing operations will decrease.

The present invention has been made in view of these conventional problems, and provides a printing system that can detect various printing defects reliably and with a high yield, and that can effectively clean the printing roller and make printing work efficient. The technical problem is to provide an automatic defect inspection device.

<Means for Solving the Problems> In the present invention, as a technical means for achieving the above-mentioned problems, printing defects are inspected by the following means. That is, a supply means for transporting the printing material, a printing roller that sequentially rolls into contact with each printing material transported by the supplying means to transfer printing ink, and a cleaning position for bringing the printing roller into contact with and separating from the supplying means. a printing roller position switching unit for switching between the printing position and the printing position; a cleaning mechanism unit that presses a cleaning member against the printing roller at the cleaning position; and a printing unit for printing characters, symbols, etc. on the printed substrate transferred by the supplying unit. an imaging means for outputting a video signal, a total number of dots corresponding to the pixels of the printing part of the binary signal by converting the video signal into a binary signal, and a number of connected components in which the dots are continuous as a group; and the number of dots corresponding to the pixels of the printed part in each block obtained by dividing the inspection mask surrounding the printed part into N pieces, and use these as a reference range. In contrast, the present invention is characterized in that it includes a printing quality determination section that outputs a defect detection signal when at least one item is out of the standard, and is configured to drive and control the cleaning mechanism section based on the printing defect detection signal. .

<Function> For example, in inspecting printing defects on tablets, the printing roller rolls into contact with the tablets that are attracted to the supply drum of the supply means in an aligned state and transferred as the supply drum rotates, transferring printing ink. After printing, the printed part of the printed tablet is imaged by a camera, etc., and this video signal is converted into a binary signal to calculate the total number of dots, number of connected components, and each divided block corresponding to the pixels of the printed part. At least two of the numbers of dots corresponding to the pixels of the printed portion are determined, and it is determined whether these are within the reference range or not.

First, by determining whether the total number of dots corresponding to the pixels of the printing section is within the range of the standard total number of dots, it is possible to detect ink stains, etc. near the printing section without increasing the detection accuracy. can be reliably detected.

Furthermore, by determining whether or not the number of connected components is within the range of the reference number of connected components, it is possible to detect missing prints (letters), broken prints, ink stains in the printing section, and the like.

Furthermore, by further dividing the inspection mask that surrounds only the printed area, and individually determining whether or not the number of dots corresponding to the pixels of the printed area in each block is within the range of the reference number of dots for each divided block. In addition to missing prints, print cuts, and ink stains in the printing section, the detailed inspection allows for reliable detection of print breaks, different types of characters, etc., without requiring very high detection accuracy.

Therefore, by combining at least two of the above three types of inspection and determining a printing defect when any one of them is out of the standard, printing defects can be detected reliably with high yield. The cleaning mechanism unit cleans the printing roller according to the rate of occurrence of printing defects, so the printing roller can be cleaned without reducing printing efficiency. The entire line of work can be performed by unmanned automatic operation.

<Example> Hereinafter, a preferred example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic block diagram of an embodiment of the present invention, illustrating the case of a tablet 1 as the printing material, and FIG. 2 is a block diagram of a printing quality determination section. First, referring to FIG. 1, the outline will be explained. After passing through the primary hopper 2 and the secondary hopper 3, the tablets 1 to be printed are delivered to the first supply drum 4. The printing ink is sequentially transferred onto the second supply drum 5 and the third supply drum 6, and when the third supply drum 6 transfers the printing ink, the printing ink is transferred by the printing roller 7 at the contact position with the printing roller 7 to print ( In addition, optical fiber (
The presence or absence of printing defects is inspected at the inspection position where the tip of the endoscope (endoscope) 8 is installed oppositely, and non-defective products that are determined to have no printing defects in this inspection fall onto the discharge container 9 and are ejected. Defective products with . are collected in the defective product storage section 10. The cleaning mechanism section K is operated according to the frequency of occurrence of printing defects, and dirt and the like on the transfer surface of the printing roller 7 is removed.

The tablet 1 is attracted to the first supply drum 4 with its surface facing outward, and as it is transferred as the supply drum 4 rotates and passes through the inspection position, it is irradiated by the lamp section 11 and is irradiated by the camera 12. The image signal is processed and an inspection is performed to determine whether there is any foreign matter on the surface of the tablet 1. Then, at a position where the first supply drum 4 contacts the second supply drum 5, the tablets 1 are adsorbed from the first supply drum 4 to the second supply drum 5 with the back side facing outward. As described above, when the tablet 1 passes through the inspection position, it is irradiated by the lamp unit 13 and imaged by the camera 14, and the image signal is processed to inspect whether or not there is a foreign substance on the back side of the tablet 1. It will be done.

Thereafter, at the position where the second supply drum 5 contacts the third supply drum 6, the tablet 1 is transferred to the second supply drum 5.
With the surface facing outward from the third supply drum 6, a vacuum suction device (Fig. (not shown), and are transferred as the drum 60 rotates.

The printing section P supplies the printing ink from the ink reservoir 15 to the printing roller 7 through the design roller 16, and transfers the printing ink from the printing roller 7 to a predetermined location on the surface of the tablet 1 for direct printing. ing. The printing roller 7 is
The printing position where the printing position contacts both the design roller 16 and the third supply roller 6 shown by the dashed line in FIG. In the cleaning position, the transfer surface is cleaned by a cleaning mechanism section K to remove dirt and the like.

The cleaning mechanism includes, for example, a cleaning belt 17 in which gauze is laminated on one side of a core belt made of twill weave of fibers.
, a solvent nozzle 18 that injects a solvent onto the cleaning belt 17, an air cylinder 19 that advances and retreats between the solid line position and the dot-dashed line position, and a solvent drying section 20.
It is composed of. When performing cleaning, air cylinder 1 is operated by a solenoid valve (not shown).
9, the cleaning belt 17 is moved to the solid line position and is pressed against the printing roller 7 at the cleaning position, and the solvent is sprayed from the solvent nozzle 18 onto the cleaning belt 17, and the printing roller 7 is pressed against the cleaning belt 1.
By rotating while contacting the printing roller 7, dirt and the like on the transfer surface is removed, and the surface wetted by the solvent of the printing roller 7 is dried by dry air blown from the drying section 20.

When the cleaning work is completed, the air cylinder 19 retreats to the position indicated by the dashed-dotted line and separates from the printing roller 7.
Meanwhile, the printing roller 7 is also moved to the position indicated by the dashed-dotted line and comes into contact with the third supply drum 6 and the design roller 16, and the printing operation is resumed.

The tip of the optical fiber 8 is disposed at a printing defect inspection position along the third supply drum 6, and as shown in FIG. A synchronization sensor 21 is disposed on the downstream side of the direction, detects passage of the tablet 1 to the third supply drum 6 rotated at a constant speed, and outputs a detection signal to the inspection synchronization signal generation circuit 22. The test synchronization signal generation circuit 22 synchronizes the detection signal from the synchronization sensor 21 with the horizontal synchronization signal and vertical synchronization signal from the horizontal/vertical synchronization signal generation circuit 23, and outputs a test synchronization signal.

Then, when the printed tablet 1 is transferred as the third supply drum 6 rotates and reaches the printing defect inspection position, the strobe light 24 is turned on at the output timing of the inspection synchronization signal and irradiates the tablet 1. At the same time, the reflected light from the tablet 1 enters the CCD camera 25 through the optical fiber 8, is photoelectrically converted by the CCD solid-state image sensor of the CCD camera 25, and is a still image of the tablet 1 at the moment it passes through the printing defect inspection position. A signal is obtained, and this video signal is processed by the print quality determination section 26.

Next, the print quality determination section 26 will be explained with reference to FIG. 2. Single tablet 1 from the CCD camera 25
The video signal is divided into 512 x 512 pixels horizontally and vertically by the horizontal synchronization signal and vertical synchronization signal, and the A/D
After being converted by the conversion circuit 27 into an 8-bit digital signal, that is, a 256-gradation digital signal corresponding to the gray level, the image digital signal for one tablet 1 is temporarily stored in the image frame memory 28 in a don't-matrix manner. be remembered. FIG. 4 schematically shows the image stored in the image frame memory 28, and FIG. 3 shows the screen M of the monitor 29 based on the image digital signal of the image frame memory 28. An image is shown in which a symbol consisting of a combination of a square and a triangle and three numbers are printed in the center of the image.

This image digital signal is converted into a binary standard level setting circuit 3.
Only signals corresponding to printed parts such as printed characters, symbols, etc. are extracted from the image digital signal by comparing it with a reference value of 0 to 255 steps for binarization which is set externally to 0, and It is converted into a digitized symbol and stored in a 512×512 binarized frame memory 32 in matrix form, that is, at a predetermined address corresponding to the coordinate position of the image, using horizontal and vertical synchronizing signals. FIG. 5 schematically shows the storage state of the binarized frame memory 32.

Since the binarized symbol stored in the binarized frame memory 32 in this way is also a signal of the horizontal-vertical coordinate position,
In the inspection mask base point detection circuit 33 and the inspection mask size setting section 32, an inspection range is determined based on each specific coordinate position of the vertical signal and the horizontal signal in the binarized symbol read out from the binarized frame memory 14. The window and inspection mask are set.

First, to explain the settings of the window Wl shown in FIG. 6, the minimum coordinate position V that first appears in the vertical signal of the image e of the tablet 1 in the image digital signals stored in the image frame memory 28 in a matrix manner, and The minimum coordinate position H that appears first in the horizontal signal is detected, and the detected minimum coordinate position V of these two is detected.
,,H.

A window W that surrounds the printing unit based on a horizontal line and a vertical line passing through vertical and horizontal coordinates obtained by adding predetermined offset values Vo and Ho, respectively.

After setting, the image digital signal in this window WI is binarized, and from this binarized signal, the total number of dots corresponding to the pixels of the printing part and the number of dots corresponding to the pixels of the printing part of the binarized signal are calculated.・Calculate the number of connected components in which the throat is continuous as a group. Incidentally, the number of connected components in this example is
It is "4" made up of a symbol and three numbers.

Next, the setting of the inspection mask W2 shown in FIG.
2 and the minimum coordinate position H2 that appears first in the horizontal signal, and detect these two minimum coordinate positions V
2. The intersection of a horizontal line and a vertical line passing through the vertical and horizontal coordinates obtained by adding predetermined offset values V'r and Hx to H2, respectively, is determined, and the coordinate position of this intersection is set as the base point of the inspection mask. On the other hand, an inspection mask size corresponding to the object to be inspected is set in advance in the inspection mask size setting section 34, and the reference point of this set inspection mask size is set at the coordinate position of the reference point set by the above-mentioned inspection mask reference point detection circuit 33. Inspection mask W2 that matches and becomes the inspection range
is automatically set. Then, inside the front 2 of the inspection mask,
As shown in FIG. 8, it is divided into a predetermined number of blocks (5×5 in the figure), and the number of dots corresponding to the pixels of the printing part is determined for each divided block.

Incidentally, the inspection mask size can be arbitrarily variably adjusted according to the object to be inspected by the inspection mask size setting section 34. The reason is that the object to be inspected, such as tablet 1, is in pocket 6.
In many cases, the inspection mask W is fixed at a position shifted from the predetermined position of
If the position of No. 2 is fixed, a part of the printed characters etc. will be located outside the inspection mask, resulting in the inconvenience of erroneously determining a non-defective product as a defective product. To solve this problem, the inspection mask is made floating, and the inspection mask is automatically set by detecting the base point from the printed portion of the object to be inspected.

Further, the reference width setting section 35 sets the total number of dots and the number of connected components corresponding to the pixels of the printing section in the window WI and the division within the inspection mask W, based on the average value of a predetermined number of well-printed tablets 1. Three types of reference widths are set in advance, including the number of dots corresponding to the pixels of the printed portion of each block. and,
The microcomputer 36, which is a control unit, calculates the total number of dots and the number of connected components in the window WI corresponding to the pixels of the print section detected from the binary signal read out from the binary frame memory 14 at the timing of the inspection synchronization signal. The number of dots corresponding to the pixels of the printed part of each divided block in the inspection mask front 2 is compared with the three types of reference widths set by the reference width setting section 35, and if the number does not fall within this reference width, A defect detection signal is output to cause the tablet 1 to fall from the third supply roller 6 to the defective product storage section.

The above-mentioned quality determination based on the total number of dots on the printed part is aimed at detecting printing stains such as NG1 on the outside of the front 2 of the inspection mask shown in FIG. .

In the quality determination based on the number of connected components corresponding to the pixels of the printing part, the number of connected components in this embodiment is "4", but
If there is a print break NG2 like the number "1" in the figure, a print drop NG3 like the number "9", or a print stain NGI, the number of connected components increases or decreases, so it is determined that it is a printing defect.

In the quality judgment based on the number of dots corresponding to the pixels of the printed part in each divided block, in addition to the print stain NGI, print breakage NG2, and print dropout NG3, the inside of the inspection mask front 2 that surrounds only the print part is further divided into blocks. Because each detail is inspected using the
It is also possible to reliably detect missing printing (NG4) and different characters, such as the number ``3''.

When any one of the inspection results for these three types of printing defects is out of the standard, a defect detection signal is output, and when the occurrence rate of this defect detection signal exceeds a set value, the cleaning mechanism section K
or when the cleaning mechanism section K operates at regular intervals, the operation of the cleaning mechanism section is stopped when the occurrence rate of the defect detection signal is less than a set value. In addition to efficiently performing cleaning work and printing work, it is also possible to perform printing work, inspection of printing defects, and cleaning work of printing rollers based on the inspection results by unmanned automatic operation.

<Effects of the Invention> As described above, according to the automatic printing defect inspection device of the present invention,
The total number of dots corresponding to the pixels of the printing section in the part including the printing section, the number of connected components in which dots corresponding to the pixels of the printing section are continuous, and the printing section for each block divided into the inspection mask that surrounds only the printing section. Since printing defects are inspected by combining at least two of the three inspection items with the number of dots corresponding to each pixel, printing defects can be detected reliably with high yield.

In addition, since the printing roller is automatically cleaned based on the inspection results for printing defects, cleaning can be performed effectively without reducing printing efficiency.
Printing, inspection for printing defects, and cleaning of printing rollers can be performed automatically and unmanned.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of an embodiment of the present invention, and FIG.
Figure 3 is a block diagram of the print quality determination unit in Figure 2, Figure 3 is a diagram showing the monitor screen in Figure 2, Figure 4 is a schematic diagram of the storage state of the image frame memory in Figure 2, and Figure 5 is the diagram in Figure 2. Figure 6 is an explanatory diagram of the window settings in Figure 2, Figure 7 is an explanatory diagram of the inspection mask settings in Figure 2, and Figure 8 is a schematic diagram of the storage state of the binarized frame memory. FIG. 1... Tablet (printing material) 6... Third supply roller (supply means) 7... Print roller 17... Cleaning belt (cleaning means) 2
5... CCD camera (imaging means) 26... Printing quality determination section K... Cleaning mechanism section W2... Inspection mask

Claims (1)

[Claims] (1) A supply means for transporting the printing material, a printing roller that sequentially rolls into contact with each printing material transported by the feeding means to transfer printing ink, and a cleaning position where the printing roller approaches and separates from the supplying means. and a printing roller position switching means for switching between the printing position and the printing position, a cleaning mechanism unit that presses a cleaning member against the printing roller at the cleaning position, and printing of characters, symbols, etc. on the printed material transferred by the supplying means. a total number of dots corresponding to the pixels of the printing part of the binary signal by converting the video signal into a binary signal, and a connected component in which the dots are continuous as a group; At least two of the three types of inspection items, the number and the number of dots corresponding to the pixels of the printed area in each block obtained by dividing the inspection mask surrounding the printed area into N pieces, are determined, and these are determined as a reference range. In contrast, the cleaning mechanism is characterized by comprising a printing quality determining section that outputs a defective detection signal when at least one of the defects is out of the standard, and configured to drive and control the cleaning mechanism section based on the printing defective detection signal. Printing defect automatic inspection equipment.