Apparatus for uniquely marking individual hides, and tracing method.

Field:

The invention relates to apparatus for making an indelible marking upon a hide, or on the skin of a slaughtered animal so that the marking remains visible after the hide is separated from the animal. The invention relates to uniquely identifying every hide. The invention provides a method for providing traceability of hides through tannery processes and for managing data related to the tannery processes.

Definitions:

The letters “RF” as used in this document are an abbreviation for “radio frequency”..

“RFID” as used in this document is an abbreviation for “radio frequency identification device”.

“Slaughterhouse” is a name for a meat processing plant in which animals are killed and disassembled; primarily to obtain food for human consumption. “Knacker’s yard” is a name for a carcass processing plant for animals not intended for human consumption. Since hides are useful by-products of knacker’s yards the present application applies to them.

Background:

Documents such as EP3134852, EP2088852, US20200385824 and US 9,530,162 illustrate attempts to track animal skins as raw materials for the leather industry from skinning though processing and to end uses. US 9,530,162 (Hein et al) describes example steps taken during prior tanning processes. The steps shall not be described further. Indeed, some tanneries have secret processes. None of the documents disclose an effective way to make permanent and easily read marks upon hides, wherein a unique identification can be applied on to any one hide. Absent same, a management scheme cannot be implemented.

Problem to be Solved:

There is a strong desire to be able to identify and trace any one hide out of all the hides taken from animals around the world. There is a requirement to identify the source of a particular hide by country and preferably with resolution down to the farm from which the animal was supplied. Other characteristics may also be recorded, and the data may be used during processing and distribution. The patent literature surveyed to date does not disclose a successful method.

A specific component would be apparatus and an industry-compatible method for applying an identifying marking on to each hide, at a slaughterhouse or knackery, or later in a tannery. Preferably, the identifying marking is unique within the world and comprises a unique code to be linked with details held within a separately held relational database; preferably available to the participating public over the World-wide Web. One preferred requirement is that nobody is able to change stored information. Data may include owner identification, country of origin and slaughterhouse identification and, if available, relevant particulars of the animal. Data is linked to the identifying marking at the slaughterhouse. The apparatus should be fully compatible with the extreme working conditions in slaughterhouses, knackeries and tanneries and the competence of the workers involved.

Identifying and tracing hides depends on apparatus and a method for placing uniquely different information on each different hide. The information should be permanent and immediately readable at any time.

OBJECT:

A first object of this invention is to provide apparatus capable in use of applying a unique identifier by means of an effective marking system to skins or hides, or at least to provide the public with a useful choice. A second object is to provide a tracing method that facilitates recall of data stored elsewhere, and linked to the unique identifier.

STATEMENT OF INVENTION:

In a first broad aspect, the invention provides apparatus for permanently and indelibly marking hides wherei the apparatus includes at least one matrix of electrodes that is, when in use, applied against the hide, while generator apparatus generates a controlled amount of high-frequency alternating electric power to be connected to one or more individually selected electrodes for a controlled period of time, thereby ablating adjacent portions of the hide and marking the hide in a manner that forms at least one recognisable character which may later be read by a person or by a machine.

Preferably said at least one matrix of electrodes is laid out in a “seven-segment display” arrangement. Preferably, a group comprising a number of individual matrices of electrodes is capable when in use of creating a row of characters during one application.

More preferably the number of groups is seven.

In a related aspect, each electrode comprises a conductive strip including a row of points directed toward the hide, thereby, when connected to a source of RF power, of promoting the formation of a row of discharge arcs commencing at the points and ablating the portion of the hide adjacent the electrode.

Preferably, the radio-frequency power is of sufficient frequency and amplitude when in use to create a plasma in air surrounding each point of an energized strip; the plasma is attracted toward the adjacent skin and hair, and the heat of the plasma causes ablation of the skin and hair, and burning against the hide.

In an example, the radio-frequency power is at a frequency of about 390 kiloHertz, has an amplitude of about 500 volts, and is derived from a generator having a controlled power output of about 350 Watts.

Preferably the duration of localized ablation and heating is in the range of from 0.2 to 1 second.

Preferably, all strips are held within a marking head comprised of a non-conductive material that holds the points at a common height

In a first form, the group is applied against a hide by hand.

In a second form, the group is carried on an arm of a robotically controlled device and is placed by the device against the hide.

Preferably the apparatus includes a generator of from 100 to 1000 kHz alternating electric power at a power of at least 500 watts.

Optionally, the generator produces from 390 to 420 kHz alternating current.

Preferably one generator supplies each individual matrix of electrodes.

Preferably, any one electrode of each matrix of electrodes will, when in use, be connected with a corresponding generator through one of an array of controllable switches selected from a range including electromechanical relays; each switch being placed in either a closed or an open state by a computer in order to generate a set of markings which may later be read by a person or by a machine.

In a second broad aspect, the invention provides a system or tracing method for individual hides, for which a managing computer has the task of maintaining a database or ledger of information about individual hides in which the ledger includes a series of records; each record including a unique number for any one hide, a modified number as it was actually marked on to the hide, and at least one detail about the animal from which the hide was obtained.

Preferably the computer controlling the set of markings is instructed to create a set of characters that conform to an internationally recognised standard in order that, when in use, a hide may be traced through factory processes.

Preferably the process for marking and identifying the hide is completely automated by using a robotic arm to press the marking head against an intended part of each carcass and perform a marking procedure, in order to provide a capacity to link the hide, using the unique marks made upon the hide, with information held within a corresponding record within a computer database or equivalent.

Preferably the managing computer is a type of immutable database, and is accessible to relevant or eligible persons around the world.

Preferably any record within the managing computer can receive additional information at any time, for a non-limiting example grading results.

Preferably the managing computer is immutable in at least the sense that no person is empowered to remove information from the ledger.

Preferably the managing computer is one of a set of computers within which the stored information is mirrored.

Optionally the managing computer creates each unique number before it is required; alternatively it is separately created elsewhere.

Preferably the host computer or server has the functions of (1) obtaining a unique identifier from the managing computer, (2) obtaining further data pertaining to the animal from which the hide has been or will be obtained, (3) sending the series of characters to the microprocessor to serve as an identifying mark, and (4) transmitting the combination of unique identifier linked to the further data to the database or ledger within the so that, when in use, the unique identifier serves as a code with which to recall the further data from the managing computer. Preferably the unique identifier in the form in which it is applied to the skin or hide has been modified in order to include an amount of redundancy in case some of the markings are unclear, so that a reading algorithm can reconstruct the original information during a reading process.

Preferably the managing computer can be accessed in order to determine the country of origin of any one, identifiable hide.

In a second broad aspect, each hide is uniquely marked with reference to an international collection of markings.

Preferably a hide so marked may be traced through factory processes and an origin of the hide may be established.

DESCRIPTION

The description of the invention to be provided herein is given purely by way of example and is not to be taken in any way as limiting the scope or extent of the invention. In particular the dimensions shown in one illustration are purely illustrative. The invention has been described in an illustrative manner, and it is to be understood that the terminology which has been used is intended to be in the nature of words of description rather than of limitation.

In this specification, reference numerals, including reference numerals appearing in the Summary of Invention, are provided for clarification only and are not intended to restrict the scope of the invention to the particular embodiments of the components in conjunction with which the reference numerals are used.

Throughout this specification unless the text requires otherwise, the word "comprise" and variations such as "comprising" or "comprises" will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps. Each document, reference, patent application or patent cited in this text is expressly incorporated herein in their entirety by reference. Reference to cited material or information cited in the text should not be understood as a concession that the material or information was part of the common general knowledge or was known in New Zealand or in any other country.

LIST OF DRAWINGS Fig 1: A flow-chart or scheme for tracing any hide around the world as far as its end use, using the present invention to apply markings to each hide.

Fig 2: A hide, a marking head with details, and an array of 7- segment characters.

Fig 3a with 3b: as two halves. Circuit diagram for the RF power generator circuit.

Fig 4a and 4b: Circuit diagram for the interface between detectors of sparks and the microprocessor.

Fig 5a, 5b and 5c: Circuit diagram for aspects of the RF switching circuits.

DETAILED DESCRIPTION OF THE INVENTION.

Please refer to Fig 1. Traceability of individual hides is desired in a commercial and international trading context. Fig 1 is an outline or timeline of data management for that purpose, crucially based on the apparatus described in this section for applying a unique marking 107 upon a hide, at 108.

Fig 1 shows, at top left, a Public Database (101) which is preferably a type of immutable database that is held in a “managing computer” which need not be a single, actual machine. For this purpose, the database is a controlled ledger that does not permit deletion of information once added. On the other hand the ledger does allow a reasonably indefinite number of information to be added to any one record. One record will specifically describe the corresponding hide.

For example, Amazon Corporation offers an “append-only journal” service as the “Amazon Quantum Ledger Database” (herein QLDB). (Reviewed on-line on 25 March 2022).The preferred QLDB is a mirrored system (for data permanence) but unlike a blockchain it is not a distributed system. All alterations are date-stamped within the ledger.

Fig 1 is a timeline, flowing downward. The left side of the page depicts evolution and usage of data within one record held in the Public Database over time. The right side portrays a contemporaneous sequence of actions over time in relation to any one hide (104). The hide is identified at Marking (108) within a slaughterhouse or a knacker’s yard, preferably before or optionally after the skin is taken off the carcass. Identification persists until broken up at the End Use (121). At that point, the applied markings are cut off when the hide is made into leatherware. Stored data may be kept beyond box 116 for administrative or research purposes. A: Uppermost group.

The uppermost group of events allowing the scheme of Fig 1 to be applied is focused at 107 (Write) and the box 108 “MARK MN” meaning “Mark one hide with the Modified unique Number”. The apparatus to be described later in this document can permanently apply 14 numeric characters to a single hide 108, although a limited range of other characters can be substituted for any number. 14 is a preference, not a limit. The theoretical limit of 100 million million identifiers ( 10 ¹⁴ ) or Unique Numbers (UN in Fig 1) is reduced to perhaps 1 or 10 billion by inclusion of error-correcting codes or checksums in order to reduce sensitivity to poorly written characters. A skilled worker will be aware of suitable systems.

The optional process included in box 104 “Modify as MN” identifies a procedure to take any one Unique Number (UN) and create a “Modified unique Number” (MN in Fig 1) which is best suited for use with the seven-segment character approach of this invention. Prior to that, a computer system (which may or may not be the managing computer holding the QLDB or equivalent) may create a bank of Unique Numbers (102) and store them ready for use in advance of demand in the Public Database. Note that it may be possible to not require correction of reading errors, or, some installations may have a greater need for error correction. The UN itself is sacrosanct.

B: Hide Identification section

The following will be done in synchrony with the appearance at a marking station of a carcass to be marked, perhaps once every 10-12 seconds in large slaughterhouses. About 2 seconds is required to mark each carcass. The block of functions within Server S (105) at the slaughterhouse, in Fig 1 includes the steps (at 104) of requesting in advance one unique number (UN) from a currently available record within block 102. That UN record is then deemed to be allocated and becomes not available to other requests. Realistically, a bank of UNs might be maintained within 102 in advance of demand. Server S preferably modifies the UN into a modified number (MN) in view of any limitations of the preferred symbol generation system and because of the risk that sometimes, a number may become imperfectly readable from the hide. Then, the MN is transmitted as a “write” message (107) to the present hide-marking invention 108. A permanent Modified Number is applied by a marking process to be described below.

Server S also receives Animal Data (AD) (103), describing the origin of the hide. AD ought to be at least the location (including the country) of the feedlot that grew and supplied the animals, but it may be expanded to include either a key to data held elsewhere, or describe the species (not always bovine). In addition, in some countries animals carry RFID eartags which either include a UID (unique identification number) for interrogating a governing database holding information (the data held elsewhere), or may themselves include a variable amount of information such as breed, progenitors, age, sex, location, disease status, and the like. That information may be useful when optimizing leather treatments and grades (see below).

Preferably the marking head is resiliently supported on a pneumatically controlled arm or a full, multi-axis robotic arm, likely to use machine vision to direct the marking head on to a suitable position upon each carcass, and press it against a selected site. Details will vary according to existing installations of machinery and the like at any one intended marking station.

Relevant information is bound together at (104) and written into the current record 109 (labelled “UN-MN-AD”). UN is the formal Unique Number. MN is the Modified Number and AD is the Animal Data. The MN is stored in the Public Database as the primary search term for later use, because a later search may not correctly predict how the MN had been formed from the UN. Different slaughterhouses may form their MNs in different ways, for instance some may not use a seven-segment numerical format.. It is expected that most subsequent queries to the Public Database will require a fast (such as 1-2 seconds) response with relevant data in order to keep pace with industrial actions including killing, marking, grading, sorting, treating and marketing. Since the preferred QLDB is a single entity (perhaps mirrored) and not for example a block chain entity, recall is quick. For control of international movements of hides, the process Start a Record, for taking a UN from UN bank 102 may include a step of recording the name and location of the slaughterhouse that requested the UN, and the date.

C: Example Actions section

“Server T” (110) is likely to be a supervisory computer system or server located in a tannery. For example, a person may wish to recall information about any one hide or hides. At 112, the visible MN is read (111) from the marked hide by an operator or by a machine. A search in the Public Database (101) based on the MN as a search term will recall the record for display and preferably it is shown in a usable form. For example, a hand-held device such as a smart phone or a tablet, or a fixed display may show data about one hide within seconds after the device has scanned the hide and resolved the number. A report 113 may be generated that shows some or all of the details in the accessed record 109 of the Public Database 101. The first use of the scheme of Fig 1 may be to identify and list the hides received in a shipment. Information recall may be done an indefinite number of times.

In the event of a MN occurring more than once in the Public Database, it will be necessary to revert to the associated UN in order to decide on the identity.

Grading the hide is a likely process, as at 114. A hide is passed through a grading device such as a hide scanner which is a machine-vision based grading machine. The Public Database data is searched as soon as the Modified Number is read from the hide by the machine vision apparatus and resolved, so that the hide being graded can be uniquely identified. When the hide has been evaluated, the grading report “QA Data” (114) according to any standardized grading scheme is added to the downloaded entry “UN-MN-AD”. The entry becomes “UN-MN-AD-QA1” (as in Box 115). It is likely that the hide will also be sorted after grading in the same handling operation, or sorting may be done later according to market requirements or the like. Of course, grading or sorting including reading of the marked MN, and data entry could be entirely manual. For that, it is helpful if the marked characters are human-readable, as seven- segment numbers are. Alternatively, sorting may be a separate “read-only” operation and could be based on grading or any other descriptor such as area, unblemished area, colour or weight. Example Actions may be carried out repeatedly and extra information may be added on one or more occasions to the record for each hide, now shown as the record “UN-MN-AD-QAl-plus” (119).

Another likely action is to positively identify each hide during export and import. There may be a requirement to exclude hides from certain countries. The “Get MN” step at 112 is repeated with a server located at a border entry point, in order to recall the stored data and read the AD which includes the country of origin. The data is presented at the site of inspection.

D: Private Subset section ( 117)

Many tanneries have trade-secret processes; sometimes operating for centuries past. In the event that a particular tannery wishes to systematically improve a proprietary or industrial-secret process for leather treatment (117), it can exploit the database by copying a “Subset” (118) from the Public Database, holding it separately and writing its own extra records concerning individual hides into that subset, perhaps as the hides are graded or re-graded. The subset may be held as a secure collection within the QLDB or in the tannery’s own computer system Server T (110). The complete data held about any one hide may be useful when analysing the efficacy of a process in order to improve it.

E: End Use section:

At Box 121 the hide ceases being a complete entity when the hide is cut into portions and the portion bearing the markings (MN) is removed. Before the MN is removed, it may be useful to take steps to support the farmer’s contribution to hide quality by making a bonus payment or other acknowledgement. Use of the database scheme as shown in Fig 1, in turn dependent on the hide unique-number marking apparatus of the present invention (see below) makes that possible. The Public Database data could be retained indefinitely, subject only to the cost of storage.

Details of Enabling Apparatus

The present hide-marking invention placed at 108 in Fig 1 is described. This invention has been designed to suit the typical industrial use environment. A marking station may be located just after the killing floor, once the unskinned carcass has been hung by its hind legs and is being hauled along an overhead conveyor belt. A slaughtering plant in the USA may kill 2500-5000 head per day, with several chains in use at the same time. Typically, carcasses pass the marking station on each chain every 10-12 seconds. There is likely to be water, mud and fecal contamination of the preferred marking site In the industrial environment, the suspended carcasses on the chain are hazardous in that each weighs 0.5 to over 2 tonnes. Workers around the marking station are unlikely to show technical sophistication. Pressure hoses carrying hot water and detergent are used to clean components of each killing chain, therefore electronic equipment has to be sealed.

By way of example only, the Inventors have selected the well-known “seven-segment display” layout of linear marking strips, to provide a process for recording numeric data as a series of seven-segment characters upon a surface. Each segment is one of segments a, b, c, d, e and f. They form at least the numeric digits 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9, and optionally a limited range of characters: A, C, d, E, F, g, H, and -. For example, additional distinct shapes such as D, f, F, 1, II, and H can easily be generated but are less amenable to reading by a person. In case of poorly readable markings, the Inventors prefer to use a coding process (within box 104) to Modify the UN as a MN (Modified unique Number) compatible with the seven-segment numeric data. It should be appreciated that each set of seven segments in the writing device, herein called a marking head, is reconfigurable within milliseconds to print a different character. When creating a MN, care should be taken to avoid a risk of confusion or mis-reading, such as “6” being readable as a “b”, or an “8” being readable as a “B”.

The characters made are instantly visible. Use of the seven-segment format allows humans to read the numbers at a later time although machine vision is likely to be preferred. The inventors currently prefer a marking head that creates one row of seven, seven-segment characters. The computer and associated electronics render the marking device an equivalent to an instantly reconfigurable branding iron.

Fig 2a is an oblique perspective side view of part of the print head, showing two seven- segment characters, 204 and 205 extended from a flat substrate 203. Each character is comprised of seven metal segments with a zigzag pattern on the extended edges such as 206. The zigzag pattern (as shown in Fig 2 is one way to form a series of points. An ion discharge in air is created at each point along an energized segment. That discharge is used to cause localized ablation. Each segment extends outward from an insulating base or substrate 203. A surrounding frame of metal connected to the “cold” side of the RF generator may be added along the left and right sides of Fig 2a, to act as an RF return and to server as a “standoff’ for purposes of physical separation. Most mounts for this head will include a resilient member behind the head and upon a support device. The marking head could be hand-held though it is preferably pressed in place on each carcass by a controlled manipulator such as a robotically controlled arm equipped with machine vision. No drawing of the manipulator is included, since each chain of each slaughterhouse will have its own dimensional requirements.

Fig 2b shows the face view of an example marking head as an array of 14 characters in two rows. The example characters “516” to be created are shown as mirror images, as for a rubber stamp, because they will be made when the head is in contact with the hide. As described below, each segment of each character of the marking head is connected to a relay that are switched ON or OFF before the RF power is generated, to select any character. There are a number of RF generators; one for each character and preferably one or two spares. The inventor has since realized that one row of seven characters will suffice.

Fig 2c is a section through the substrate 203 showing the configuration of one sheet metal segment, 206, which may be stamped from 1 mm stainless steel sheet. The segment is fixed through the substrate and a connecting lug 209 for receiving a cable from the switching devices (see below) is extended to the rear. One point of the five-point sawtooth is shown at 207. Example materials for the substrate include solid PTFE and ceramics, although prototypes were made by 3D printing with selected plastics. The substrate is preferably resistant to an arc between segments being tracked over its surface.

In Fig 2d, a rear portion of a bovine hide 200 is shown in relation to a preferred site for placing a marking head 201. The currently preferred marking position is symmetrically on to the skin over the first three or four sacral spines, posterior to the tuber sacrale of the pelvis. At that location, the leather is not often of good quality and it can be removed at the time of end use. Also, it is a reasonably accessible site while a slaughterhouse chain is in operation. It should be noted that the permanent marks will be trimmed off the leather so that they do not appear on the finished articles. Note that this drawing shows a 7 x 2 group of characters. 7 x 1 is now preferred.

The heat or more strictly an effect of ablation is generated by a brief application of high- frequency electric power, while the metal conductor is not heated. In an example, the radiofrequency power is at a frequency of about 390 or 420 kiloHertz, has an amplitude of about 500 volts, and is derived from a generator having a controlled power output of up to about 350 Watts. An actual frequency at a particular site may be limited by Regulations. That radio-frequency power will ionize air if there is a strong enough electric field to cause ionization of the air, notably at any pointed conductor. The invention uses the sawtooth shape imposed on an energized strip to create a line of ionized air. The arc generated upon any energized segment is attracted toward the adjacent skin and hair, and the heat of the plasma causes a line of ablation and burning against the hide. If a segment is connected to the “cold” side of the RF generator, no effective ionizing field is present and the segment may act as a return conductor.

The “printing” process as operated at 108 in Fig 1 uses apparatus that simulates an instantaneously reconfigurable form of a branding iron. It is capable of “printing” any selected symbols in a period of about 1 second, depending on conditions and RF power available. The process may be applied to an already skinned hide.

The size - that is, the height and width of the markings is not limited. If too small, a blurring effect as the RF energy is transferred through the layers of skin and dermis may make it hard to read the markings.

Circuit for Generation of RF Power Some of the electronic circuitry used resembles that used in medical electrocoagulation. Detail of circuits differing from that technology, by being adapted to generate and control a different frequency and power shall be described in detail. The remainder of the electronic components represents well-known practice largely as dictated by properties of components.

In a current prototype example, a microprocessor type WROOM-32E (Espressif Systems (Shanghai) Co., Ltd), and support circuitry includes three communications interfaces, “Bluetooth”, USB and Ethernet. Ethernet is preferred for industrial use, to receive marking commands and data from Box 104 of Server S in Fig 1. The microprocessor coordinates activation and control of the RF generator and switching for character-forming purposes under control of Box 104, typically through an Ethernet cable. The microprocessor generates the 390 kHz pulses.

Fig 3 a and 3b together are a circuit for a preferred RF generator having a regulated output at about 350W, and about 750 volts, at 390 kHz. Versions providing more power appear desirable. There is one generator per character. Those parts of the entire apparatus that differ from a conventional medical electrocautery machine are discussed.

One generator, shown as a circuit in Figs 3a with 3b, is used for each character of the marking head. Note: the lines 306- 306’ are continuous and connect Fig 3a with Fig 3b. Regarding Fig 3a, terminal 301 connects a DC supply at 48 to preferably 96 V (in this example) to the primary of T1 (300), the secondary of which when in use raises the voltage within the resonant circuit to about 800V; in practice reduced to about 750V at the marking head, the circuit also includes a 150 ohm 20 watt resistance connected at 302, for dissipating or damping excess energy in the resonant circuit by switching on the power MOSFET device 305 under microprocessor control. Power MOSFET type semiconductors 303, 304 and 305 are mounted on a fan-cooled heat sink. 303 and 304 are driven with pulses at a 390 kHz rate (in this Example) to generate and control the RF power by the microprocessor when RF power is required. In relation to Fig 3b, the inductive component of the resonant circuit 309 tuned to 390 kHz comprises the secondary of step-up and coupling transformer T1 (300) and the series inductances 307 and 308 (each 100 microHenry). The capacitative component is comprised of capacitors connected in series, including capacitor 313. RF power output and RF power return lines are capacitatively coupled at taps 312, 314 into that series of capacitors. The effective capacitance of the series as shown is 1.19 nF (nanofarads. The RF generator includes a device termed a voltage transformer, to monitor resonant current, a current transformer to monitor power supplied to the marking head, and an external spark detector samples transients information from the voltage transformer. The spark detector senses ionization or sparks arising from the enabled RF circuits as fluctuations within the RF resonant circuit. Regulation can be applied based on these parameters such as to cope with a variable number of energized segments, and to close down the generator when the RF power demand is terminated after writing. The microprocessor assesses the values of these parameters and may activate an output port supplying, through the driver circuit, the gate of Q3 (here 305, Fig 3a) When 305 is closed both DC power and a fraction of the resonant circulating current are dissipated through a 150 ohm 200 watt resistor at 302, reducing the resonant current circulating in conductor 303.

The RF power output 315 is coupled to all the common connections of a bank of relays (see Fig 5a) and an RF return connector 316 is connected to every un-energised segment through the relay contacts as shown in Fig 5b. It should be noted that the relays are made to change state while the RF generator is off. Each relay of the bank of relays is connected to an output terminal of a multi-output driver, for example type TPL9202_TSSOP (500). That driver receives character-building commands from the microprocessor through a local serial SPI bus. In turn, the microprocessor has an interface with an Ethernet interface, connected by cable to the Server S (105 in Fig 1) which determines the MN to be applied to the particular hide. In a modem slaughterhouse, the chain itself carries digital labelling marks as visual or RFID type identifiers used to maintain specific identity of carcasses, and that may be read by the Servo S device in order to synchronise labelling.

A spark detector is preferably included. Fig 4a shows the rectifying and filtering sections for the transformers 310 and 311 in Fig 3b. The output of the lower filter in Fig 4a is an input to an analogue comparator 406, such as a LM393 integrated circuit as shown in Fig 4b. The other input is developed by the microprocessor as a “reference voltage for the moment”. The output is passed to an input of a monostable digital circuit such as type SN74LS221. It generates a fixed- length digital pulse supplied to the microprocessor as a signal that a spark has been detected as a fluctuation in the resonant current in the circuit of Fig 3b. The circuit aids in monitoring the “plasma arc” that is generated for ablation purposes at the marking head.

VARIATIONS The device could be used for ink-free marking of other organic materials such as wood, in an industrial setting.

Layouts other than the preferred “seven- segment” character could be used. The mirror-image character has been mentioned previously. For example, the invention could be extended to use the “sixteen segment, alphanumeric character set” known in the electronics industry. Or a non- human-adapted code such as a one-dimensional bar code or a two-dimensional format could be applied using the same form of RF energy.

A 10-segment display may be created by adding an arch of 3 more segments over the topmost segment, to add more potential characters, at a cost of three more relays for each character. Sixteen- segment displays can display alphabetical characters. The inventors believe that using a restricted set of characters (0-9) is adequate, and better allows reconstruction of a partially obscured mark.

Or, a type of one-axis barcode may be printed where each thick line is made by energizing a pair of strip conductors that are located close together, or by a “double bum” to make the thicker lines.

ADVANTAGES

The invention provides an “instantaneously variable branding iron” that can generate characters on computer command and print within about a second while itself remaining cold.

Application of hide markings can be completely automated, so a slaughterhouse need not add staff.

The invention is capable of quickly marking each hide with a permanent and individual set of markings while the hide is still attached to the animal on a slaughterhouse chain. There is little cost involved since no identifiable objects such as an RFID tag are added. The marks can be read at any time by a person or by a suitably programmed machine vision device.

There should be no muscle spasm or nerve stimulation when RF power is used, even within a dead animal. Use of RF abolishes a risk of shock to a nearby human operator. A person holding a knife near the marking station could develop muscle spasms and cause injury if he or she inadvertently receives an electric shock.

Given a capability for conveniently marking hides with unique and permanent identification, a database for globally recognizing the source of any hide, plus other information may be maintained. The task of the marking head is reduced to placing a brief yet sufficient code on the hide that can be matched with an extensive and updatable record held within a computer. The unique marks should satisfy some of the requirements of the international “Leather Working Group” (LWG) by establishing the origin of the hide.

Being able to correlate any hide with an animal owner identification allows providers of less blemished hides to be rewarded.

Finally it will be understood that the scope of this invention as described and/or illustrated herein is not limited to the specified embodiments. Those of skill will appreciate that various modifications, additions, known equivalents, and substitutions are possible without departing from the scope and spirit of the invention as set forth in the following claims.