DE2347393A1 - METHOD AND DEVICE FOR RECOGNIZING A CODE - Google Patents

Description

PATENT LAWYERS

DR. ING. A. VAN DERWERTH DR. FRANZ! ÖDERER

21 HAMBURG 9O. P MUNICH 8O

WlLSTOItFEItSTR 32 TEL. CO 40) 77O8 6I lUCl ^ E-GR AHN-STR. 22 »Τ» "». (08 ΠΙ +73947

19.9.1973 M / jb X. 140

Applicant: Unilever N.V., Burgemeester s'Jacobplein 1, Rotterdam, Netherlands

Method and device for recognizing a code

The invention relates to code recognition systems, particularly for warehouse control and similar automated or computer-related activities.

Systems are already known in which photocells for reading binary codes are used that are applied to objects in a special way; however, these systems require an accurate Orientation of the items to be read to achieve a certain level of accuracy. Furthermore, other systems are known which make use of television cameras and complex codes, for example for reading checks, but such are common Systems tend to be disproportionately complex and expensive.

The present invention provides a system in which one particularly easily recognizable coding on objects nait a simple and easily operated reading system is combined. In particular, the system is insensitive to the arrangement of the objects to be read, while in the preferred method of operation in

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rejects a high degree of unwanted information.

In a corresponding manner, the invention provides a method for recognizing codes which is characterized by application a code on objects consisting of a multiplicity of essentially parallel rows of digital code records, by scanning each object with a television camera so that the code records are in the field of view of the Arrive camera and the rows with the camera line scan are in alignment, by feeding one from the camera and electrical output signal dependent on the code records to signal decoding means and through an independent one Decoding each row in the signal decoding means for decoding the object on the basis of its code recording.

The invention also provides a device for decoding a code created, which consists of a plurality of substantially parallel rows of digital code-on recordings, these Apparatus is characterized by a television camera with line and image scanning means for scanning a field of view in which the code records are included, and to generate a electrical output when the rows of code records align with the line scan of the camera, depending on the code recordings and by means of signal decoding means, which are designed to decode each row independently.

In general, it is the intervals between changes in the Code record that determines the code and distinguish the Decoding means between intervals of different lengths to determine the code. The code is in a special form formed from a series of narrow and wide records, the wide records representing a unit of the code and the

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(in the row direction) narrow records use a different code unit represent, for example, the zeros and ones corresponding code units. The fields between all code records are also preferably encoded. However, in any case it is the time interval between "Switching from the existence of a recording to the Absence of record or vice versa when scanning the code series that determines and distinguishes the code.

One of the advantages of such a system is that a TV camera can be set up particularly easily or simply, which furthermore at the same time fully satisfies all requirements Output is created at a relatively low cost. In addition, the output may be due to the line and image scanning system the television camera are generated or obtained multiple times. This helps ensure the accuracy of understanding due to the excess information thus generated. The system also allows other surpluses to be introduced in order to increase the accuracy of the understanding to improve further. It should be noted that in almost all communication systems the accuracy of understanding the greater, the more excess information is, for example through "repetition or different types of expressions or transmission. This applies both to understanding by means of the human senses and to understanding by means of electrical and mechanical systems.

The term "television camera" is understood to mean a device which scans a field of view and generates an electrical output signal (the video signal) as a function of the field of view being scanned. Usually the camera contains an optical system, a special form of electronic device such as a vidicon tube, Line and image scanning means and an amplifier for generating an initial gain of the electrical output signal of the tube. ,, 409813/0955

+) available

The camera should be aligned so that its line scan is parallel runs to the rows of code records and an image (generally an optical image) of these rows is scanned.

The decoding means should preferably be designed so that they reject or ignore signals originating from records or rooms or intervals that are smaller than a narrow one Code recording in the width direction or larger than a width Encoding in the width direction, and further reject the complete signal if there is an incorrect number of records seems to be. Another feature allows the system to reject signals that are records or rooms or intervals of a medium width.

The system can be used to identify codes that are applied to hard cardboard boxes in warehouses and shops are; and this type of coding helps ensure that any labeling on these boxes, for example Printed advertising and instructions should not be understood as a code recording.

The main advantage of using multiple rows for the code is in that a more reliable system is achieved in combination with a television camera. For a given amount of information are few bits of information are provided in each individual row, and the television camera can normally just as well or easily handle several Rows are set up as if for a single row. In addition, the system is alerted when there is a reading error on any part of the information occurs, i.e. in a row, is not prevented from decoding and displaying the remaining rows of information.

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Preferably, the different rows correspond to different properties of any number or letter code, the is to be used on the objects. The rows should all be aligned substantially parallel to the line scan of the television camera and as a result of the provision of several series, different parts of the code can be determined, checked and decoded, regardless of the other pieces of code in the other rows. For checking purposes, each row should preferably be at least decoded three times before their content is displayed as a correct code. This increases the effectiveness of the decoding, though Signals are weak. Another advantage of having multiple rows is that the placement of the system is less critical is compared to when the same information is contained in a single longer row.

Another characteristic is that, provided the objects move, these should move transversely with regard to the serial recordings provided on them and the camera line scan. As a result, a better definition of terms or definition of the characters of the coded output signal is achieved that is recorded by the camera and is generated.

Each series of properties can be formed from at least four records to indicate the particular number in the series from 0 to 9 using a binary scale code (e.g. 1, 2,4, 8 code). The narrow code record or the narrow space may indicate the "0", and the wide code record or the wide space can indicate the "1" or vice versa. Alphabetic or alphanumeric code properties can be found in can be represented in a corresponding manner.

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To create a surplus in the code, at least some of the recordings are repeated. In one embodiment, each property set has seven or more code records, which are symmetrical around the central code recording (the fifth in the case of four records) are arranged so that the code can be read in both directions (in the case of seven records the first, second and third record of both ends to be repeated). Thus, the coded property is still read even when the object to be read upside down. Seven on drawings or positions are the optimum for reading the decades of a numeric code, while for alphanumeric or alphabetic codes more records or Positions are desirable.

To get information about a particular set of properties that are shown is to be achieved, i.e. the order or magnitude of the property in the final and read overall code or the Decade on a numerical scale, the spaces between various binary code records can be encoded with this information. For example, the space between all code records can be a short or a long space for a particular property, and in a numerical system that of this dependent code to identify the order of magnitude or the particular decade, i.e. the ones, tens, hundreds of Property to be used.

In the case of using seven code records, there are six spaces between them. ! Door a completely symmetrical numerical code can form the first and sixth spaces as a long space while the rest Spaces are short spaces indicating a particular decade, for example the units; the training of the second and

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of the sixth space as a long space while the remaining spaces are short spaces, a second decade, for example the tens, indicate; and the formation of the third and fourth spaces as a long space, while the remaining spaces short spaces can be a third decade, for example the Hundreds, specify. While maintaining the rest of the symmetry, other combinations of long and short spaces can be used for can be used for more decades. For the three gaps on each side of the center, their width changed in this way eight different combinations are possible; and in conjunction with more than seven code records can do more Interstices and thus more combinations of the interstices can be provided.

In an alternative form, the symmetry can be retained The code records some of the gaps between these records to be asymmetrical, allowing the code to come from both directions remains readable, but also provides information regarding the direction from which it is read, for example to indicate that an object is placed with its top or bottom down.

In the case of using seven code records for the decades of an asymmetric numeric code, the first two spaces, which are arranged symmetrically from both ends, can can be used to display the decade. This means that the four combinations of long and short spaces are possible, making up to four decades series (ones, tens, hundreds, and thousands) can be used, which is desirable and for many applications is sufficient. The space on either side of the central code record can then be used to determine the alignment of the code. Unless the code with the third space is long

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Room and the fourth room is printed as a short room, the reverse decoding of the same can indicate that the box is not aligned properly.

In the following two exemplary embodiments according to the invention are described with reference to the drawings; in this shows:

Figure 1 shows a first form of coding recording on a.

F e ms ehbild s chi r m,

Fig. 2 shows a second form of coding recording and

3 shows a schematic representation of an overall system including a decoding device.

Fig. 1 shows a view of a symmetrical shape of the code record for a numeric code on a television screen. In this context it is stated that a television screen is not an integral part of the invention. The invention requires a television camera with an associated scanning system, a power supply and an amplifier and a decoder unit. However, a television screen can be used as a possible surveillance system be used.

The numerical code of Fig. 1 uses three decadic rows d3, d2 and dl, which are formed from seven code records, which in turn are arranged symmetrically to a central axis CL, with six code spaces alternating between the recordings are provided. The code records are printed on the box or other object to be monitored. If the items are items moving along a conveyor, the decadal rows are intended to be aligned in this way be that they are perpendicular to the conveying direction. The television camera

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should be arranged so that their line scan is parallel to theirs optical image of these rows runs.

Thus, the representation according to FIG. 1 would be a television monitor screen show the image of these rows as if they were moving up or down or in the "Y" direction when scanning the lines lies in the usual "X" direction. The advantage of this particular orientation or alignment is that despite the Movement of the bins every given line scan on the television camera produces a number of stationary representations of the code records and the movement does not tend to blur the code image in the row or X direction. Nonetheless, it is without difficulty to recognize that the accuracy of setting up such a system is not particularly critical, at least much less so more critical than most conventional systems that use photocells. In fact, the angle of orientation can the decadal rows vary by 30 or more depending on the length of the code compared to the width of the record, which is still legible. If a single line code were used, which would necessarily have to have a greater length for the same information potential, the list would be more critical.

The code system shown uses seven code records in each decadic line to determine a property or a character, these records being symmetrical to the central line CL are arranged. These records can be thin or thick to indicate whether a given digit unit is present or not. So when using the code 1, 2, 4, 8 from left to right, the decade d3 indicates the 8, since the fourth code recording, which corresponds to FIG. 8 is thick, while the first three are thin and thus their digit units are not present. In a corresponding way

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the decadic row d2 indicates the 7 (1 + 2 + 4), since the first three Records are thick, while the decadic row dl indicates 0 since all code records are thin. How easy to see is, the fifth, sixth and seventh code records are a mirror image of the first three records and confirm that Result (superfluous information to increase the accuracy the acquisition).

The spaces between coding records are arranged in narrow or wide widths as a binary code to identify the decade of each particular character as a unit, tens or hundreds. Since three distances are provided on each side of the central line CL, up to eight combinations are possible. In the code shown, a single wide space is provided behind the third code recording and thus represents the hundreds in the first row d3. In the second row d2, the wide space behind the second code recording is provided to display the tens; in the third row dl is the wide space behind the first code field for displaying the units. This means that the number shown is the number 870.

In the example shown in Fig. 1, both are code records as well as the spaces provided between these are arranged symmetrically, and so both codings can be used in the same way can be easily read, regardless of the direction in which the object to be identified is arranged.

In the modification shown in Fig. 2, there is a certain extent an asymmetry in the spaces between the code records intended. The code records are the same, and this one Example shows the representation of the same numbers 8, 7 and 0.

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However, in this case the hundreds row d3, the first row, is identified by two narrow spaces on the first and second fields, while the tens and ones decade series (d2 and dl) are as shown above. This leaves the rooms on both sides the central code record (the figure eight record) for the Decade detection not used. Instead, they are arranged asymmetrically to give information about the direction in which the code is going is to be read. For this purpose, the third room is wide and the fourth room is narrow. Unless the record the load-bearing object is not correctly aligned, the order of these spaces in the code read will be reversed, and this can be easily ascertained. The rest of the information can be read in any way as before, and that shown Number is also the number 870 as before.

The same code structure can be used for alpha-numeric codes with up to 16 character possibilities per row used based on the records will; it can be seen that other alphanumeric or alphabetic codes can be changed by increasing the number of code records or used through further use of the rooms can be. It can also be provided that characters are represented just as well by spaces as by code records can be; for example, eight code records can be used in a modification of the coding just described creating a special room in the center. The room then carries information for special character options for this line, although the special code recording does not provide any further information due to or in its symmetry.

Furthermore, it should be noted that there is basically no difference exists between a code record and a code field. On what it matters, are the intervals between the changes from one up-

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drawing for the lack of a record and vice versa. Indeed, situations can arise in which the distinction is made between what a Field and what a record is impossible, while the change is recognizable, for example in the case of light recordings, which are printed on a dark background, which in turn is printed on a light colored pack; the This description is to be understood accordingly.

Reference is now made to FIG. 3, which is a schematic Shows representation of a complete overall system.

Objects A with code records B in the form of the items shown in Fig. Coding shown are on a conveyor that moves in the direction of the arrow shown. A television camera C is Arranged above the objects and aligned with respect to their line scanning parallel to the rows of characters in the code recording .

The objects A are typically hard cardboard boxes, but it can be understood that bags, sacks, drums or others can also be used Packs are used provided that they are over have an area on which a code recording is provided can be. The recording can be provided as shown on the top side or on the side that is in the correct orientation relative to the camera. The system can also be used for records on buses, trucks, railroad cars or other vehicles that move past a reading station, or for identity tags, tickets, passports or rental or loan books are used.

The electrical output signal of the camera, the video output, is a signal conditioning unit D supplied. In this unit

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A bandpass filter removes high and low frequency signals and noise and reduces the signal gradations, after which the signal to trigger a square wave with two signal levels accordingly the background or the fields (white) and the code records (black) is used. A certain amount of reinforcement is provided here.

The conditioned signal is then sent to a decoding circuit E supplied.

In the decoding circuit, the conditioned video signal is in Level converted to the zero or one of a digital output signal correspond, depending on the time intervals between the ends or edges of the decoded signals below the Prerequisite that these certain pre-determined conditions suffice.

A timing pulse generator drives the decoding circuit Shift register on. The course or course of the time pulse generator is different from an operator for decoding signals Pulse lengths adjustable.

The incoming signal controls the system so that the shift register is set to zero whenever the signal level changes, after which it is set a standard signal is introduced into the shift register. The next time the signal level changes, the status will be that of the standard signal has been set in the shift register is used to determine the type of signal that is diverted. If the signal is there or while the standard signal has not moved far enough in the shift register, is too short in terms of its length, nothing is done dissipated, and this event is simply ignored; if the signal is slightly longer and falls within a predetermined range, the

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corresponds to a short code recording or field or space a "0" delivered; when the signal is again, slightly longer, this indicates an error and the entire signal is cleared; if the signal is even longer and in, a predetermined frame intended for a long code record or field or space is, a "1" is discharged; if the signal is longer, it will be treated as an error again, or it will be the end of the series and the overall signal is deleted. In this case or point in time, the information from the first part of the series is passed on.

This way, a series of zeros and ones becomes a digital one Standard coding generated according to the time intervals between the narrow and wide code records and code fields. The signal does not specifically distinguish between code records and C ode fields, however, this is also not necessary as the C ode records and fields alternate and the beginning of each series is unmistakable due to a code recording or in each Series initially inevitably a code recording occurs (after the previous signal ended the previous series with a very long background pulse).

As an additional check at this point, a further switching the system to a white state looking for black at the beginning of each series.

After that, the signal thus generated is encoded in the form of a binary Signal of zeros and ones corresponding to a character of the code is present together with the decadic information Checked symmetry. The signal is fed to the first half F of a shift register and then into the second Half G forwarded. As the signal progresses through the passes through both shift registers, a digital comparison compares

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circuit H opposite areas of the two shift registers for symmetry. Assuming a proper signal is passed, a point is reached at which the two shift registers are full, and the series of signals in the two shift register halves correspond to each other (starting from the two middle Fields that should be coded in the opposite direction). In this state or at this point in time, the signal continues through the circuit If symmetry is not achieved, the entire signal is ignored, as this can be done, for example, by reading from the Objects A derived signal must be a false signal.

The moment the required symmetry is achieved, check the comparison circuit also the order or order of magnitude of the two central fields for checking the alignment of the Code and passes this information on accordingly, if it is needed somewhere.

The output signal is then sent to the units I »J and K -To check that the same string of characters is at least three times has been received before it is forwarded for further use.

The unit I is a memory selector that the memory units J and K controls. Each binary signal of the sequence of characters checked for symmetry is transferred from the shift register G to one or the other of the two memories J and K forwarded. The memory selector I controls this process and continuously fills the memory units, so that at a given point in time the one spice purity that preceding drawing line signal and the other unit contains the corresponding drawing line preceding it.

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Separate storage units in J and K are used for the different ones Decades of each number line is used, and the decade information in the binary signal of each incoming character line gives the memory selector I indicates which decade group of the memory banks in J or K is to be selected. It is evident that this is necessary because as a result of the normal picture or frame and the line scan using the television camera to randomly mix signals from one decade line with those from another decade line in individual cases can.

The memories J and K thus contain current information from previous signals of the two corresponding rows for each decade. Then the next incoming character train signal becomes by means of digital comparison circuits L and M compared with these two character series signals, which for the same decade in the memory units J and K are stored - if all three correspond to each other, i.e. the signal has been checked three times a correctly and completely decoded signal is obtained, which is sent to units N and P for display, storage on tape or for Use in a computer or at another location that requires it. In the same "way it is done with the other Decades, and these checks are carried out continuously for all decades.

If an incoming signal does not correspond to the two preceding and stored character signals, the Memory selector I in one or the other of the two memories J or K (for the corresponding decade) to replace the oldest of the two characters stored there. Afterward a corresponding check of the next character string signal is carried out, and this procedure is repeated until possibly three times Correspondence is achieved.

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In the present system, the coding is only read after each code record and each field to the correct length The group of records in each row has been checked for symmetry and the number of records per row has been checked and the decoding of the row has been checked at least three times. That way is the probability for a wrong reading by scanning across the lettering or accidental records which, when congruent or coincident, correspond to the code records, are indeed very small.

The system can be used to decode more than one type of code at the same time. For example, a single camera be connected to two separate decoders with different Coding systems work, which in turn are completely different Have code length characteristics, but no interaction or other problems occur under the assumption that the rows of both codes parallel to the line scan the television camera.

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Claims (15)

9/19/1973 claims 1. Method of recognizing a code that is in the form of digital Code records is applied to an object, the code records being scanned optically and an electrical one Signal is electronically decoded depending on the recordings, characterized by applying one of a A plurality of essentially parallel series of digital Gode records of codes on objects, by scanning each object with a television camera, this in such a way that the code recordings get into the field of view of the camera and the rows are in alignment with the camera line scan. Feeding one from the camera and electrical output signal dependent on the code records to signal decoding means and by independently decoding each row in the signal decoding means for identification of an object based on its code records. 2. The method according to claim 1, characterized in that each code series consists of a predetermined number of records, the length of which is within predetermined limits, and that the Decoding agents only accept batches of records and decode when they have a predetermined number of records and the length thereof in the range lies before certain limits. 4098 13/0955 3. The method according to claim 1 or 2, characterized in that the decoding means only then each decoded row after at least three signals from the same set of code records have been decoded. 4. The method according to claim 2 or 3, characterized in that Each row represents a property and is formed from a multitude of binary code records, of which at least some are repeated to form an excess, and that the decoding means records these binary code records in the Decode properties. 5. The method according to claim 4, characterized in that.die intervals between changing the digital code records determine the code and distinguish the decoding means for decoding the code between intervals of different lengths. 6. The method according to claim 5, characterized in that each row the code records are essentially symmetrical to theirs Center is arranged and that the decoding means for decoding of a signal from the series are formed, regardless of the direction in which this series is presented. 7. The method according to claim 5, characterized in that each row is arranged essentially symmetrically to its center starting from an information digit that is used to determine the Direction from which the code is presented, and that the decoding means decode a signal from the series, namely regardless of the direction in which the series is presented, and also determine the orientation of the series. 4 09813/0955 8. The method according to claim 4, 5, 6 or 7, characterized in that each row is coded to determine a property, the length of each code record determining a property and the length of the spaces between the properties identifying the magnitude of the properties , and that the signal decoding means. identify the property and magnitude by distinguishing the time intervals between each "change of code records." 9. Apparatus for carrying out the method according to claim 1, characterized by a television camera (C) with line and image scanning means for scanning a field of view in which the code recordings (B) are included, and for generating an electrical output signal when the rows of code records (B) with align the line scan of the camera (C), depending on the code recordings (B) and by signal decoding means (E), which are designed to decode each row independently. 10. Apparatus according to claim 9 for decoding a code in which each row consists of a plurality of binary code records, at least some of which are repeated to form a surplus are, characterized in that the decoding means (E) are designed to decode these binary code records, provided that the output signal of the television camera (C) the number of Code records (B). 11. The device according to claim 9 or 10 for decoding a code, at which the intervals between the changes in the digital code recordings determine the code, characterized in that the decoding means (E) have a view to differentiating are formed between intervals of different lengths for decoding the code. 4098 13/0955 12. The device according to claim 9, 10 or 11, characterized in that that the decoding means (E) for displaying each decoded row only after at least three signals from the same Series of code records (B) have been decoded are formed. 13. The apparatus of claim 10, 11 or 12 for decoding a Code in which each row is arranged substantially symmetrically about its center, characterized in that the decoding means (E) are designed to decode a signal from the series, regardless of the direction in which the series is presented. 14. The apparatus of claim 10, 11 or 12 for decoding a Code in which each row is essentially symmetrical about its center, starting from an information digit for determination the direction from which the code is presented, is arranged, characterized in that the decoding means (E) for decoding a signal from the series, namely indifferent, in which direction the series is presented, and also to determine the alignment of the row are formed. 15. The apparatus of claim 11, 12, 13 or 14 for decoding a code, in which each row to determine a property is coded, the lengths of each code record being the property determine and the lengths of the spaces between the properties identify the magnitude of the property, thereby characterized in that the signal decoding means (E) for identification the property and the order of magnitude by differentiating the time intervals between each change of the code recording are trained. L, 0 S 8 1 3/0 9 Γ. 5