GB2230369A

GB2230369A - Inspection of printed information on a product

Info

Publication number: GB2230369A
Application number: GB9006564A
Authority: GB
Inventors: Steven Buckby
Original assignee: Prestek Ltd
Current assignee: Markem Imaje Industries Ltd
Priority date: 1989-04-13
Filing date: 1990-03-23
Publication date: 1990-10-17
Anticipated expiration: 2010-03-23
Also published as: GB2230369B; GB9006564D0; GB8908378D0

Abstract

A method of inspecting printed information (12) on a printed product (11) comprises inspecting each printed character individually using a sensing means (13) which provides a signal to a data handling device (14), the data handling device processing the signal to derive a measure of the clarity of the character, comparing the measure of clarity for each individual character with stored data specific to the respective individual character and rejecting or accepting the product (11) depending upon the result of the comparison. <IMAGE>

Description

Title: Method and apparatus to inspect printed information on a product.

Description of Invention This invention relates to a method and apparatus to inspect printed information on a product.

There is a long standing requirement in the packaging industry automatically to inspect printed product item codes and over printed lot and batch information to ensure that these are correct and are printed to a sufficiently high quality. This is particularly important in the pharmaceutical industry or food industry where identification by lot/batch number and/or sell-by date are important.

Apparatus are known which can inspect printed product information. If the printed product information is adjudged sufficiently clear by the apparatus, the printed product is accepted. If the printed product information is adjudged not sufficiently clear by the apparatus, the printed product is rejected.

According to one aspect of the invention we provide a method of inspecting printed information of a printed product comprising inspecting each printed character individually using a sensing means which provides a signal to a data handling device, the data handling device processing the signal to derive a measure of the clarity of the character, comparing the measure of clarity for each individual character with stored data specific to the respective individual character and rejecting or accepting the product depending upon the result of the comparison.

The data handling device, when a product is rejected, may be adapted to indicate to a user the reason why the product is rejected. For example, the data handling device may be adapted to indicate which character of the printed information is not sufficiently clear.

Preferably the data handling device derives a measure of the clarity of each individual character by testing the integrity and/or confusability and/or print density and/or cleanliness and/or print position of each character, and ascribes a score to each criterion tested. The stored data relating to each individual character may comprise as appropriate, a pass score for each criterion tested.

By testing the "Integrity" of each character we mean that the apparatus determines whether a printed character generally is sufficiently similar to the expected character to be readable by a user, with regard to whether the printed character is missing, only partially printed, or is the wrong character.

For example, the apparatus determines whether a character is a "C" or a and whether the "C" or "6" is correct By testing the "Confusability" of each character we mean testing whether there is any possibility of the printed character being confused with another similar character e.g. is an "R" so badly printed that it could be confused with an "B".

By testing the "Print Density" of each character we mean testing whether the density of the print is sufficient for clear reading.

By testing the "Cleanliness" or print smudging of each character we mean testing whether there any extraneous ink which could lead to a character being misread e.g. if a smudge occurs adjacent the stem of a "P" could the "P" be read as a "B" or an By testing the "Print position" of each character we mean notwithstanding that the character may be perfectly printed is the character in the correct place on the label e.g. if the label is preprinted with: LOT NUMBER: DATE: when overprinted with the lot number and date, is the lot number printed adjacent "LOT NUMBER" or is it too close to the preprinted "DATE".

The data handling device may for example determine from the signal produced by the sensing means for each individual character, a score relating to the integrity and/or confusability and/or print density and/or cleanliness and/or print position of the character and the stored data may be adapted to include a specific pass score for each such criterion. In the event of a product being rejected, the data handling device may be adapted to indicate to the user not only which character is responsible for the rejection of the print product as a whole, but which tested criterion of the character has not achieved the pass score.

Thus an operator is able to take the necessary action to correct any specific deficiency in the printing process.

For example, a printed product may be rejected because the print density of one or more characters is not sufficiently high because the printer may require inking. The data handling device may indicate this to the user.

Alternatively, a printed product may be rejected because a character which it is particularly important to identify clearly, potentially can be confused with another similar character.

Conversely a printed product may be accepted even though one character which it is not essential is entirely clear, is slightly unclear. This is possible because different pass scores or measures of clarity can be set at least for individual specific characters of the printed information and/or for each criterion tested for each character.

Thus an individual pass score may be included in the stored data for each individual character, and/or for each criterion tested for each character.

Preferably the method includes programming into a memory of the data handling device stored data for each character of the printed information, which stored data may include a global pass score for each character, but preferably including a specifc pass score for each criterion tested about each individual character.

The stored data may include reference information about the characters which can be used by the data handling device to derive the measures of clarity of the characters.

It will be appreciated that the data handling device needs to be able to identify which character of the printed information is being inspected by the sensing means. Hence the signal from the sensing means may include positional information relating to the printed information from which the data handling device can determine which character of the printed information is being inspected on the basis of the postion of the character rather than the actual identity of the character.

The printed product may comprise a label in which case the method may include the step of inspecting the printed information of the label prior to applying the label to an end product.

However on another arrangement the printed product may comprise an end product e.g. packaging, in which case the method may include the step of inspecting the printed product subsequent to printing the printed information on it.

According to a second aspect of the invention we provide an apparatus for inspecting printed information of a printed product by a method according to the first aspect of the invention.

The sensing means may conveniently comprise a video or other imaging camera and the data handling device may comprise a computer which may include a display means and a memory into which the stored data may be programmed.

The invention will now be described with reference to the accompanying drawings in which: FIGURE I is a diagrammatic illustration of an apparatus for performing the method according to the invention, FIGURES 2a, 2b, 3a and 3b are examples of printed information with printing faults.

In Figure 1, a conveyor 10 conveys printed products comprising in this example, packets 11 of a pharmaceutical product, each packet 11 being printed with an identical batch number and sell-by date as indicated at 12.

This information is printed directly on the packets. Alternatively the printed products may comprise labels which subsequent to inspection as hereinafter described, are secured to the packets II.

As each packet I 1 passes a sensing means, which in this example comprises an imaging camera 13 such as a video camera, a signal is sent to a data handling device such as a computer I 14.

From the signal received from the camera 13 and stored data, the computer 14 can determine a measure of the clarity of the printed information 12 i.e. the computer 14 determines whether the correctness and printing quality of the information on the packet 11 passes a quality test, or fails.

If the packet il fails the quality test, the computer 14 actuates a reject mechanism 16 which removes the "failed" packet I i from the conveyor 10 further downstream and/or indicates on a display 17 that the packet I I has failed the quality test.

The computer 14 includes a processing means P, and a memory IS into which data may be programmed for storage.

In one arrangement, the computer 14 is arranged to consider individual character information in a signal from the camera 13 and to test each individual character for integrity i.e. recognition, confusability, print density i.e. contrast (darkness or lightness) of the character on the background.

cleanliness or print smudging, and print position. The individual scores for all these tests for each character are then added together and compared with stored data relating to that character - the total score must be more than a predetermined global pass score comprising the stored data, which global pass score may be the same or different for all of the characters of the printed information, for the product i.e. packet 11 to pass a quality control.

When a packet II is rejected, the computer 14 moy thus be adapted to indicate to a user which character(s) of the printed information is or are responsible for the packet II being rejected, and remedial action can be taken to improve the printing quality i.e. clarity, of that character of characters.

In a preferred second arrangement though, the computer 14 is programmed to enable an individual pass score to be set for each test for each individual character which is inspected.

The signal from the camera 13 contains information as to the position of each character in the printed information so that each character is considered by the computer 14 individually and a score is awarded for each test for each individual character which is compared with information stored as data in a memory 15 specific to each test for each character. For example, the stored data may comprise a pass score for each test for each character. The pass score for any test for any character can thus be individually set.

In this way, a packet II need not be rejected because an unimportant character fails any specific test and neither is there a risk of an important character which fails any particlar test, being accepted.

Again the computer 14 would be adapted to indicate to a user the reason for a "failed" packet II being rejected, and not only would the particular character or characters responsible for the rejection be identified, but the computer 14 can indicate to the user, the specific test the character has failed, so that the user can take specific remedial action to improve the printing quality of the character or characters in a specific respect.

Thus in the second arrangement, there is no need to make a compromise between setting too high a global pass score when too many packets II will unnecessarily be rejected, and setting too low a pass score when some improperly printed packets 11 may be accepted.

Rather,the computer 14 can be programmed to accept or reject packets II with faults in printed information depending upon the context of the printing fault i.e. whether the printing fault occurs in an important or unimportant position and the degree and nature of the fault.

In both the first and second arrangements described, for different printed information, the global pass score or the individual test pass scores for the individual characters respectively, may be set by a user, to suit the context of the characters, and an operator may thus "fine tune" the apparatus to enable an acceptable pocket pass rate and printing quality to be achieved.

The computer 14 may operate as follows: First, from the signal from the sensing means 13, the computer 14 determines which character of the printed information is being inspected.

Preferably the sensing means 13 scans the printed information 12 in the same way as a reader, starting from a top left position within the view of the camera 13 and moving to a bottom right position. The information is then sent to the processing means P as a string of information. For example with the particular example shown in figures 2a to 3b, the string of information may be sent as "LOT234B FEB 90".

The computer 14 can recognise from the signal from the camera 13 each individual character of the string and hence inspect each character in turn. Each character is then subjected to five tests as follows.

I) INTEGRITY The computer 14 compares the inspected character with reference data stored in memory IS, about the integrity of the character. This can be done with any known character recognition method such as for example superimposing the inspected character on a template stored in the memory 15 to see if they match. A score of the overall degree of similarity between the inspected character and the template is then awarded to the character.

2) CONFUSABILITY The computer 14 considers the character as to the confusability with other similar characters by paying particular attention to designated areas of the characters. For example, a test similar to the integrity test may be carried out, but only for specific designated areas of the character i.e. the designated area of the inspected character may be superimposed on a template of the designated area of the expected character.

Thus for example, in a confusability test for a "B", the bottom half may be a designated area, because if the bottom half is badly printed, there is the risk of confusion with an "R" or even a "P". Thus a confusability score is calculated.

3) PRINT DENSITY The computer 14 considers each individual character as to whether the print density of the character is above a predetermined level. This may be achieved by measuring current generated by the scanned character by charge coupled devices or pixels. Again a score is awarded as to print density.

4) CLEANLINESS The computer 14 considers the cleanliness of the character e.g. is there any extraneous print around the character which could lead to confusion in reading the character. Again the computer 14 may award a points score for cleanliness.

5) PRINT POSITION The computer considers the position where the character appears within the view of the camera 13 and awards points as to the closeness of the character to a predetermined position.

In the first arrangement described above the totai score for each specific character may then be ascertained by adding up the individual test scores and the total score for the individual character compared with a global pass score for the character in the relevant position within the string, stored in memory,15.

In the second arrangement described above upon each test being performed, the individual score obtained is compared with an individual test pass score stored in the memory 15. In the event that any character inspected fails to achieve a pass score for any one of the individual tests, the computer 14 may actuate the reject mechanism 16.

In a modified arrangement, the computer 14 may ascribe both individual test scores and a global test score for each character, and may be arranged to reject the packet 11 if any specific test is not passed or if the global score obtained is not greater than a stored global score which may be different from the total of the individual test scores.

The computer may be adapted to display on screen 17 the reason why a package II is rejected. The display 17 may identify only the character which is responsible for a packet II being rejected, but preferably also(where appropriate) the particular test the character has failed so as to give an operator sufficient specific information to remedy any printing defect.

Referring now to Figures 2a-3b examples of poor quality printed information will be described together with the action the computer 14 is programmed to take. The printed information reads "LOT234B-FEB 90". The most important characters of the string are the characters of the number "234B" and the date "FEB 90". The word Lot is less important.

In the first arrangement as described above, a high global score would thus be required for the most important characters, for the packet I I to pass the inspection.

Referring to figure 2a the printed information on one of the packets 11 has a printing fault in the letter "B" of "FEB 90" However the date "FEB 90" is easily recognisable by a reader despite this fault, and hence by programming a low global pass score for the letter "B" in "FEB 90" into the computer memory 15, an operator can ensure thot a packet 11 will not fail a quality test for the sole reason of the minor fault in the "B" of "FEB 90".

In Figure 2b however, the final character in the line "LOT 234B" has a printing fault and it is not easily recognisable whether the final character is the letter "B" or the letter "P". Because of the importance of a reader recognising that this should be a "B", an operator can program the memory 15 of the computer 14 with a high global pass score for this character so that a packet II would be rejected if it has the printing fault as shown in figure 2b.

Figure 3a gives another example of printed information which has a printing fault. In this case the first character in the line "LOT 234B" is misprinted but because the word "LOT" is still easily recognisable by a human reader, and in any case the word "LOT" is less important, an operator can set a low global pass score for the letter its ' and hence a packet II with a minor printing fault as seen in figure 3a. need not be rejected.

Figure 3b gives another example of a printing fault, in this case it is in the final character in the line "FEB 90" which cannot easily be recognised.

Because it is important for a reader to know exactly what this character is, an operator can set a high global pass score for this character which would result in a packet 11 with this printing fault being rejected.

In each case when a packet 11 fails the inspection, the computer would be adapted to display to a user the reason for the rejection i.e. which character of the string of characters fails the inspection.

In the second arrangment as described above the integrity and confusability and cleanliness and print position tests pass scores for the most important characters can be made suitably high whereas the print density test score for example can be made the same for all the characters.

However for the reasons explained above, the integrity, confusability, cleanliness and print position pass scores for the letter "B" in l'9EB.90" can be made lower than for other more important characters because of the unlikelihood of confusion arising in deciding on what the printed month is meant to read.

Thus the pass and fail rate for the packets 11 can be tailored for any desired printed information.

The features disclosed in the foregoing description, the following claims or the accompanying drawing, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, or a class or group of substances or compositions, as appropriate may, separately or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims

I. A method of inspecting printed information of a printed product comprising inspecting each printed character individually using a sensing means which provides a signal to a data handling device, the data handling device processing the signal to derive a measure of the clarity of the character, comparing the measure of clarity for each individual character with stored data specific to the respective individual character and rejecting or accepting the product depending upon the result of the comparison.
2. A method according to claim I wherein the data handling device, when a product is rejected, is adapted to indicate to a user the reason why the product is rejected.
3. A method according to claim 2 wherein the data handling device is adapted when a product is rejected, to indicate which character of the printed information is not sufficiently clear.
4. A method according to any one of claims I to 3 wherein the data handling device derives a measure of the clarity of each individual character by testing the integrity and/or confusability and/or print density and/or cleanliness and/or print position of each character, and ascribes a score to each criterion tested.
5. A method according to claim 4 wherein the stored data re!ating to each individual character comprises a pass score for each criterion tested.
6. A method according to claim 5 wherein the data handling device determines from the signal produced by the sensing means for each individual character, a score relating to the integrity and/or confusability and/or print density and/or cleanliness and/or print position of the chartacter and the stored data includes a specific pass score for each such criterion.
7. A method according to any one of claims 4 to 6 wherein in the event of a product being rejected, the data handling device indicates to a user not only which character is responsible for the rejection of the printed product as a whole, but which tested criterion of the character has not achieved the pass score.
8. A method according to any one of claims 2 to 7 where appendant to claim 2 wherein different global pass scores or measures of clarity are set at least for some individual specific characters of the printed information.
9. A method according to any one of claims 4 to 8, where appendant to claim 4, wherein different pass scores or measures of clarity are set for each criterion tested for each character.
10. A method according to any one of claims I to 9 which includes programming into a memory of the data handling device stored data for each character of the printed information.
II. A method according to claim 10 where appendant to claim 8 wherein the stored data includes a global pass score for each character.
12. A method according to claim 10 where appendant to claim 9 wherein the stored data includes a specific pass score for each criterion tested about each individual character.
13. A method according to any one of the preceding claims wherein the stored data includes reference information about the characters which can be used by the data handling device to derive the measures of clarity of the characters.
14. A method according to any one of the preceding claims wherein the signal from the sensing means includes positional information relating to the printed information from which the data handling device determines which character of the printed information is being inspected on the basis of the position of the character.
I 5. A method according to any one of the preceding claims wherein the printed product comprises a label and the method includes the step of inspecting the printed information of the label prior to applying the label to an end product.
16. A method according to any one of claims I to 14 wherein the printed product comprises an end product and the method includes the step of inspecting the printed product subsequent to printing the printed information on it.
17. A method substantially as hereinbefore described with reference to the accompanying drawings.
18. An apparatus for inspecting printed information of a printed product by a method according to any one of the preceding claims.
19. An apparatus according to claim 18 wherein the sensing means comprises an imaging camera and the data handling device comprises a computer which includes a display means and a memory into which the stored data may be programmed.
20. An apparatus substantially as hereinbefore described with reference to and as shown in the accompanying drawings.
21. Any novel feature or novel combination of features as herein defined and/or shown in the accompanying drawings.