| 1. | A method of marking meat products with a machine readable visual code, which includes: moving meat products (C) oneafteranother past a printer (2) having a plurality of print heads (3) which are spaced apart transverse to the direction of travel [A) of the meat products; and operating the print heads to print a plurality of substantially parallel code lines on the meat products as they move past the printer. |
| 2. | A method according to Claim 1 in which each code line represents a binary 1 or a binary 0. |
| 3. | A method according to Claim 2 in which a binary 1 is represented by a complete printed code line. |
| 4. | A method according to Claim 2 in which a binary 0 is represented by the omission of an intermediate part of a printed code line. |
| 5. | A method according to Claim 3 in which the outermost first and last code lines are always complete. |
| 6. | A method according to Claim 3 in which a complete printed code line is formed by a series of regularly spaced dots. |
| 7. | Apparatus for marking meat products with a machine readable visual identification code, which includes: a carrier system (1 ) for moving meat products (C) oneafteranother; a printer (2) having a plurality of print heads (3) which are spaced apart transverse to the direction of travel (A) of the meat products; and control means (10) arranged to operate the print heads to print a plurality of substantially parallel code lines on the meat products as they move past the printer. |
| 8. | Apparatus according to Claim 7 in which the print heads (3) are spaced apart in the direction of travel (A). |
| 9. | Apparatus according to Claim 7 in which each print head (3) is associated with an adjacent sensor (4) for detecting the arrival of a meat product to be printed. |
| 10. | Apparatus according to Claim 9 in which the sensors (4) are located upstream of the associated print head (3). |
| 11. | Apparatus according to Claim 7 including a line sensor (8) for detecting the movement of a meat product past the printer (2), which is arranged to change the printed code. |
| 12. | Apparatus according to Claim 11 in which the line sensor (8) is located downstream of the printer. |
TECHNICAL FIELD OF THE INVENTION
This invention relates to a method and apparatus for marking meat products with a machine-readable visual code.
BACKGROUND
WO 01 80 654 A discloses a method of improving the traceability of meat by applying a unique carcass-identification serial number to selected areas of a meat carcass before it is separated into primal cuts. The serial number may be visible or invisible and is applied in a manually readable and an encoded, machine-readable form. An indelible ink which is specified for food applications is applied using a printing head carried and moved by a mechanical robotic arm under the control of a computer while the meat carcasses move along a carrier system from a loading position to an unloading position. A proximity sensor allows positioning of the print head close to the carcass.
Whilst the known system is very effective, the use of a robotic arm is expensive and requires a sophisticated control system. In addition, the form of machine-readable code used in the earlier system is not accurately recognisable from a remote position using a camera linked to a computerised image recognition system.
The present invention seeks to provide a new and inventive way of marking meat products with a machine-readable code, which is inexpensive and reliable.
SUMMARY OF THE INVENTION
The present invention provides a method of marking meat products with a machine-readable visual code, which includes: - moving meat products one-after-another past a printer having a plurality of print heads which are spaced apart transverse to the direction of travel of the meat products; and - operating the print heads to print a plurality of substantially parallel code lines on the meat products as they move past the printer.
The method may be used to mark the carcass with a code that uniquely identifies the carcass.
The invention also provides apparatus for marking meat products with a machine-readable visual identification code, which includes: - a carrier system for moving meat products one-after-another; - a printer having a plurality of print heads which are spaced -apart transverse to the direction of travel of the meat products; and - control means arranged to operate the print heads to print a plurality of substantially parallel code lines on the meat products as they move past the printer. The size of the printer may be reduced if the print heads are spaced apart in the direction of travel. Each print head is preferably associated with an adjacent sensor for detecting the arrival of a meat product to be printed. The sensors are preferably located upstream of the associated print head.
Each code line may represent a binary 1 or a binary 0. A binary 1 may be represented by a complete line whereas a binary 0 may be represented by the omission of an intermediate part of a printed code line. The outermost first and last code lines are preferably always complete for referencing purposes.
A lines sensor is preferably provided for detecting the movement of a meat product past the printer, which is arranged to change the printed code. The line sensor is preferably located downstream of the printer so that it is only triggered when the meat product has been printed.
BRIEF DESCRIPTION OF THE DRAWINGS
The following description and the accompanying drawings referred to therein are included by way of non-limiting example in order to illustrate how the invention may be put into practice. In the drawings:
Figure 1 is a schematic diagram of apparatus for marking meat carcasses with a machine-readable visual code in accordance with the invention;
Figure 2 is a general view of the printer of Figure 1 which is being used to mark a meat carcass; and - A -
Figure 3 is a general view of a meat carcass showing the code which has been applied.
DETAILED DESCRIPTION OF THE DRAWINGS
Referring firstly to Fig. 1, apparatus for marking meat carcasses with a machine-readable visual code is installed on a production line within a slaughter area which includes a track 1 for carrying meat carcasses in the direction A, one-after-another, whilst hung on hooks. Beneath the track 1 there is mounted a printer unit 2 which includes a plurality of print heads 3 (seventeen in this example) which are mutually spaced apart in a vertical direction transverse to the direction of travel of the meat products. In the drawing, the print paths of the print heads is represented by the parallel lines 6. In order to reduce the spacing between the print lines to less than the physical width of a print head the print heads are also spaced apart in the direction of travel A, as shown. Each of the print heads 3 is associated with a respective sensor 4, located immediately before it in the direction of travel A. The purpose of the sensor is to detect (using optical or other means) the leading edge of the meat carcass as it passes across the printer. This ensures that, for each print head, printing commences at the same position relative to the leading edge of the carcass even though the print heads are mutually offset in the direction of travel. In addition, the use of associated sensors automatically takes account of the fact that the leading edge of a meat carcass will often not be perfectly vertical. Since the edge of the carcass is usually a smooth curve the sensors do not have to be horizontally aligned with the respective print heads and may be slightly offset as shown, enabling the size of the printer to be further reduced. A separate production line sensor 8 is mounted adjacent to the track 1 to signal the passage of individual carcasses to a controller 10. The controller receives the input of the individual print head sensors 4 and outputs separate control signals to the seventeen print heads 3 via a ribbon cable 11 or the like, to control the firing of the individual print heads.
Each leg of a meat carcass that passes the printer 2 is printed with a unique binary code that uniquely identifies the carcass for purposes of traceability. The track may carry whole meat carcasses or half carcass pairs C, as shown in Fig. 2.
The print heads print seventeen code lines on the carcass C as it travels across the printer. Although the lines could be continuous it is generally more economical in terms of ink usage and more acceptable to the customer to print a series of dots, as shown in Fig. 3. The two outer print heads (uppermost and lowermost), which are numbered 0 and 16 in Fig. 1, print complete rows of dots for referencing purposes, to ensure that the first and last lines are correctly recognised by an automated reading system. The intervening fifteen lines may each represent a binary 1 or a binary 0, making up a full fifteen digit binary code. A 1 is indicated by a complete line of dots whereas a binary 0 is indicated by the omission of a contiguous sequence of dots (typically three or four) in the mid part of a line. This provides a very reliable way of recognising a 0 since the presence of the first and last parts of the line again provides a reference to ensure that the line has simply not been read, or that the print head has stopped working, for example.
The line sensor 8 enables the controller 10 to increment or otherwise change the code each time a carcass passes the printer so that the next carcass is printed with a different and unique identifier.
The binary code is easily and reliably read using a non-contact computer vision system for example.
It will be appreciated that the features disclosed herein may be present in any feasible combination. Whilst the above description lays emphasis on those areas which, in combination, are believed to be new, protection is claimed for any inventive combination of the features disclosed herein.