GB2462858A

GB2462858A - An inventory control system

Info

Publication number: GB2462858A
Application number: GB0815409A
Authority: GB
Inventors: William Wesley Martin; John George Bend
Original assignee: Zeroshift Ltd
Current assignee: Zeroshift Ltd
Priority date: 2008-08-22
Filing date: 2008-08-22
Publication date: 2010-02-24
Also published as: GB0815409D0

Abstract

The removal and replacement of inventory items (24) such as hand tools or surgical implements is monitored. The inventory items each have an identification tag (22) having A magnetically encoded identification code. The code may be encoded using permanent magnetic material or Wiegand wires. The items are stored in storage locations (9) which may be shaped recess is in a foam lining of for example a drawer. At least one reading device (10) is used to read the identification tags (22) and a data processing system (12, 26) is arranged receive signals from the reading devices (10) and to monitor the removal and replacement of the items. The magnetically encoded identification code may be read using a Hall effect sensor or, in the case of Wiegand wires, inductively read (a particular reading head arrangement is disclosed). An inventory container e.g, a cabinet is also described. Access to such a container may be restricted to authorised users.

Description

INVENTORY CONTROL SYSTEM

The present invention relates to an inventory control system and in particular, but not exclusively, to an inventory control system for monitoring the use of hand tools, surgical implements or other critical items. The invention also relates to a storage container for use with the inventory control system, and an inventory control process.

An inventory control system may be useful when it is important to monitor the usage of hand tools, and to ensure that they are returned to storage after use. This can help to ensure that tools are not lost or stolen. Such a system is particularly important when tools are used for repairing or maintaining aircraft engines, as any tools left inside the engine after completion of the job can cause catastrophic damage. Similarly, in the case of surgical implements, it is essential to ensure that no implements are left inside a patient after an operation.

An inventory control system can also be useful by helping to ensure that only the correct tools are used for a particular task. Such a system may also be helpful to track the identity of the person using the tools, so that if a tool goes missing or if a tool is taken that is inappropriate for the task in hand, appropriate remedial action can be taken.

It is known to tag inventory items with active RFID tags to control the movement of the inventory items. For example, many shops attach tags to their goods and have detectors * : *.* at their doors to prevent goods from being stolen. It is also known to tag goods that are * ::: :* being fransrted over long distances and to track their movement using a GPS system.

While it is advantageous to tag inventory items there are some environments in which * : : there is equipment that is very sensitive to radio signals, for example some aircraft have *: *::* systems that are susceptible to damage or malfunction, as do satellites, some military equipment, scientific instruments, and electronics products. Such equipment can be particularly vulnerable to radio signals during manufacture. Accordingly manufacturers of this type of equipment are very reluctant to allow radio based tags to be taken into sensitive manufacturing areas because of the potential damage to their systems.

There are known inventory control systems that are suitable for use in these environments however they have their own drawbacks. For example, US5608 193 describes an inventory control system, in which a tool box containing tools is weighed before and after use. Discrepancies between the two weights are noted and optionally a database of tool weights can be interrogated to suggest which tool may have been left behind. However the system does not allow the presence of each individual tool to be verified or the choice of tools taken for a particular task to be monitored. Thus tool migration can occur between tool boxes.

Accordingly, the invention seeks to mitigate at least one of the aforementioned problems or at least to provide an alternative inventory control system, container and process.

According to one aspect of the invention there is provided an inventory control system including a set of inventory items in which each inventory item includes an identification tag having an identification code magnetically encoded therein; a set of inventory item storage locations; at least one reading device arranged to read the identification tags, and a data processing system arranged to receive signals from the or each reading device and to monitor the removal and replacement of the inventory items from the storage locations according to the determined identification codes.

* *. The tag can include a deposit of permanent magnetic material which is arranged to emit *** S * . an encoded magnetic field when subjected to an external magnetic force. The emitted encoded magnetic field can be detected and decoded by the reading device to determine * : the code encoded in the tag. A number of phenomena are known to behave in a manner S.....

* which allows the encoding of data into magnetic material including the Wiegand and * the Barkhausen effects.

The magnetic tags can be safely taken into environments having sensitive equipment in them because the field emitted by the tags is sufficiently small that the risk to damage equipment sensitive to radio signals or fields is very small. Since the identification code is stored as the product of permanent magnetic material there is sufficiently small risk of loosing the embedded code after subjecting the tag to any disruptive or antimagnetic force. Thus the invention provides a means of tagging tools with identification tags that can be used in environments that are sensitive to radio signals or fields, while having the benefit of being able to track the removal and replacement of tools automatically.

This type of system can detect which of the tools associated with the inventory item storage locations are present and which are not and therefore it is not possible to fool the system by replacing a tool with an alternative tagged tool, a non-tagged tool or some other item. If an alternative tagged tool is placed into the enclosure, the system will determine that an incorrect tool is located in the enclosure because the inventory item code will not match the set of inventory item codes associated with the storage locations. If a non-tagged tool or another object is placed into the storage locations they will not be detected and the system will determine that the correct tool is still missing.

Alerts can be generated to enable a supervisor to investigate.

Advantageously the system can include a set of reading devices in which each reading device is associated with one of the storage locations and is arranged to read identification tags at that storage location. The or each reading device can be arranged to subject the identification tag being read to a magnetic field thereby causing the identification tag to induce electrical signals in a conductor and the data processing * ** system is arranged to determine the identification codes embedded within the induced signals and to monitor the removal and replacement of the inventory items from the storage locations according to the identification codes determined. **.S * * S...

* ** Advantageously each identification tag can include a plurality of Wiegand wires each having an outer shell and a core having different magnetic properties, and wherein the *: *::* tag is arranged to operate on the Wiegand effect principle. The tags are read each time they are moved into and out of the vicinity of the reading devices.

Advantageously each identification tag includes first and second rows of Wiegand wires and each reading device is arranged to stimulate the first and second rows with opposite polarity thereby producing induced pulses in the conductor in opposite directions.

Advantageously the first and second rows can be positioned such that the wires of the first row are interleaved with the wires of the second row. Advantageously the first and second rows can be arranged in an alternating pattern, that is the first and second rows are longitudinally spaced such that none of the wires in the first row are aligned with the wires in the second row. The alternating pattern does not have to be an event pattern.

For example a group of wires in one of the rows can be followed by one or more wires in the other row.

Each reading device includes a first magnetic device for aligning the magnetic fields of the shells and the cores of the Wiegand wires in the same direction. For example, each reading device can include a first permanent magnet in the region of tool insertion into the storage location that is arranged to condition the Wiegand wires into an initial magnetic state. Each reading device also includes a second magnetic device for switching the direction of the magnetic fields of the cores of the Wiegand wires, thereby inducing electrical signals in the conductor.

The second magnetic device can include a substantially E-shaped core having a centre leg and two outer legs, and wherein the conductor comprises a pick-up coil wound around the centre leg of the core. The pick up coil does not have to be wound around the centre leg of the core, alternatively, it can be located adjacent the core. The second * magnetic device can include second and third permanent magnets for switching the * direction of the magnetic fields of the cores of the Wiegand wires, thereby inducing the *** * electrical signals in the coil. The switching of the magnetic fields of the Wiegand wires * in the first row causes induction of an electrical signal in the coil in an opposite **** * direction to the switching of the magnetic fields of the Wiegand wires in the second row. * ** * * * * S.

The data processing system includes means for decoding the signals detected by the reading devices into binary codes. The data processing system is able to detect the direction of each pulse generated by the switching of each Wiegand wire and accordingly assigns a "1" or "0" value according to the direction. Advantageously the binary code can have a code format that includes parts of the code being allocated to the reading device associated with the storage location for the inventory item. Since the data processing system knows which of the reading devices is reading the tag it can determine whether or not the tool has been placed into the correct inventory item storage location from that part of the code. Additionally, or alternatively, the code format can include parts being allocated to an enclosure I container number, a customer number, an inventory item type number (e.g. for a particular type of tool such as a 15mm spanner) andlor a unique number allocated to just one inventory item. The code format can include any suitable number of bits, but preferably has between 10 and 30 bits.

The data processing system can be arranged to compare the codes received from the reading devices with a set of inventory item codes stored in a database. This enables the data processing system to determine whether or not the inventory item has been replaced into the correct set of inventory items. Advantageously the database can contain data associating inventory item codes in the tags with their respective reading devices, and hence their storage locations. Since the data processing system knows which of the reading devices is reading the tag during a reading process it can determine whether or not the inventory item has been placed into the correct inventory item storage location.

* Advantageously each reading device can include an electromagnet device for generating : a variable magnetic field for stimulating the identification tag. This enables the tag to be stimulated when there is no relative movement between the reading device and the ** inventory item, for example when the inventory item is stationary within the inventory ***.

* : , item storage location.

*: *: :* Advantageously each inventory item storage location comprises an individually-shaped recess for receiving a specific inventory item, the shape of the recess being matched to the shape of the inventory item, and wherein each recess includes at least one of the reading devices located therein or adjacent thereto. This restricts the type of inventory items that can be placed into a particular storage location and enables a supervisor to perform a quick visual check to determine whether the inventory item is located in the correct storage location. The combination of having individually-shaped recesses and coded items that are associated with those recesses provides a very effective inventory control system.

The control system can include one or more enclosures each having a closure member that can be opened and closed by a user in order to gain access to the enclosure, and detector means for detecting whether the closure member is open and/or closed.

The means for inhibiting the operation of the set of reading devices operates according to the output of the detector means. This feature enables the operation of the or each reading device to be inhibited when the closure member is in a particular operational position, which is typically when it is open. When the closure member is open the signal or field that is emitted from each of the reading device travels more easily into the environment surrounding the enclosure. When the closure member is closed, the enclosure effectively shields the surrounding environment from the magnetic fields thereby protecting sensitive equipment from damage. The advantage of this is that the enclosure for storing inventory items can be located within the environment having sensitive equipment, without the possibility of the equipment being damaged by the fields generated by the reading device(s). This cuts down the distance that a worker has to travel in order to access tools. * **

* .. The enclosure can be for example, a room or a walk-in cupboard, but is preferably a *.

* *.* container, for example for storing tools. Typically, the enclosure is designed with security in mind to limit access to the inventory items stored therein and also to provide **** * adequate shielding to prevent fields emitted from the reading device(s) from damaging S.....

* sensitive equipment. The enclosure can include a plurality of storage compartments, For * example, a container may include a plurality of drawers, or separate sections each of which are accessible via a separate closure member such as a door.

Advantageously the enclosure includes a locking mechanism for controlling access to the inventory items. Advantageously the system can include means for determining the operational status of the locking mechanism and means for inhibiting the operation of the or each reading device according to the operational status of the locking mechanism.

For example, the locking mechanism can be controlled by the processing system and the processing system can be arranged to activate the or each reading device only when the locking mechanism is closed. This ensures that a user of the system cannot open the enclosure when the or each reading device is operating. It is advantageous to use this feature together with the means for detecting whether the closure member is open or closed to prevent the possibility of inadvertently operating the locking mechanism when a closure member is still open and subsequently activating the reading machine.

Advantageously the locking mechanism can include an input device for entering the identity of a user and the data processing system can include means for recording the identity of a user. The locking mechanism can be arranged to automatically open when an authorised user has been identified.

Advantageously the data processing system includes means for recording the time of removal and replacement of inventory items and may be for example a computer.

In some embodiments, the data processing system is located remotely from the enclosure and is connected to the or each reading device by a data link. The data link is preferably a wired link when working in sensitive environments, however it can be any suitable wireless if the application and location of the enclosure allows.

**b*I. . . . . i,, ,. Preferably the enclosure mcludes a local mdicator device for mdicatmg the presence * andlor absence of inventory items in the enclosure. For example, the indicator can be a visual and/or audio indicator, and may include a display screen or indicator lights. *S. I *

: *:: Advantageously the system can include a learning system arranged to perform a routine for detecting all of the inventory item tags that are readable by the or each reading -device and for generating a record in memory means that associates all of the detected inventory item tags with the enclosure. The invention provides a very quick way of associating a set of tools with a tool cabinet and the processing system can create an electronic record, which can be stored in a database. From then on, that record can be used in the inventory control process to determine whether or not the correct tools have been removed andlor replaced in the tool cabinet. If a tag is detected that is not associated with the tool cabinet, an appropriate alert can be issued, for example a pop up message on a supervisors display screen. Additionally, or alternatively, an audible and/or visual message on can be sent to the local output device to let the user know that an incorrect tool has been placed in the cabinet. This can be used in the initial setting up of the tool cabinet and also when a new tool, or set of tools, is to be added to the cabinet. In the latter case, the learning system can be used to detect the new tools, and the database can be automatically updated.

According to another aspect of the invention there is provided an inventory item container for use in an inventory control system, said container including, a set of inventory items in which each inventory item includes an identification tag having an identification code magnetically encoded therein; a set of inventory item storage locations; at least one reading device arranged to read the identification tags, and a data processing system arranged to receive signals from the or each reading device and to monitor the removal and replacement of the inventory items from the storage locations according to the determined identification codes.

Advantageously the container can include a set of reading devices in which each reading device is associated with one of the storage locations and is arranged to read * * *. ** identification tags at that storage location. The or each reading device can be arranged

I

* * to subject the identification tag being read to a magnetic field thereby causing the identification tag to induce electrical signals in a conductor and the data processing I...

* * system is arranged to detennine the identification codes from the induced signals and to monitor the removal and replacement of the inventory items from the storage locations according to the identification codes determined.

Advantageously the identification tag can include a plurality of Wiegand wires each having an outer shell and a core having different magnetic properties, and wherein the tag is arranged to operate on the Wiegand effect principle. Each reading device can include a first magnetic device for aligning the magnetic fields of the shells and the cores of the Wiegand wires in the same direction. The second magnetic device can include a substantially E-shaped core having a centre leg and two outer legs, and wherein the conductor comprises a pick-up coil wound around the centre leg of the core.

Advantageously each reading device can include an electromagnet device for generating a variable magnetic field for stimulating the identification tag.

The data processing system can include means for decoding the signals detected by the reading devices into binary codes. The data processing system can be arranged to compare the codes received from the reading devices with a set of inventory item codes stored in a database.

Advantageously each inventory item storage location can comprises an individually-shaped recess for receiving a specific inventory item, the shape of the recess being matched to the shape of the inventory item.

The container includes a storage volume for storing the inventory items and a closure member that can be opened and closed by a user in order to gain access to the storage volume, and the system includes detector means for detecting whether the closure member is open andlor closed. The container can also include means for inhibiting the *. operation of the or each reading device according to the output of the detector means. 0SSS * S. ****

The container may include a plurality of storage compartments, For example, the * container may include a plurality of drawers, or separate sections each of which are I ***S * accessible via a separate closure member such as a door. Each separate compartment *: *:: can include a reading device. For each compartment having a reading device, the detector means can be arranged to detect whether or not closure members associated with those compartments are open andlor closed. The operation of any reading device that is located in a compartment having an open closure member can be inhibited until the closure member is closed.

The data processing system can include a learning system arranged to perform a routine for detecting all of the inventory item tags that are readable by the or each reading device and for generating a record in memory means that associates all of the detected inventory item tags with the enclosure.

The container can include a locking mechanism for controlling access to the inventory items and may include means for determining the operational status of the locking mechanism and means for inhibiting the operation of the or each reading device according to the operational status of the locking mechanism.

Advantageously the locking mechanism can include an input device for entering the identity of a user and the data processing system may include means for recording the identity of a user.

Preferably the locking mechanism is arranged to automatically open when an authorised user has been identified and the data processing system includes means for recording the time of removal and replacement of inventory items.

The container can include a data transmission system for transferring data to a remote device or network.

*: According to another aspect of the invention there is provided an inventory control process for monitoring the removal and replacement of inventory items in an inventory S...

control system including a set of inventory items in which each inventory item includes an identification tag having an identification code magnetically encoded therein; said * process including using a set of inventory item storage locations and at least one reading *: * device arranged to read the identification tags, and further using a data processing system arranged to receive signals from the or each reading device and to monitor the removal and replacement of the inventory items from the storage locations according to the determined identification codes.

According to the method the inventory control system can include a set of reading devices in which each reading device is associated with one of the storage locations and is arranged to read identification tags at that storage location. The or each reading device can be arranged to subject the identification tag being read to a magnetic field thereby causing the identification tag to induce electrical signals in a conductor and the data processing system is arranged to determine the identification codes from the induced signals and to monitor the removal and replacement of the inventory items from the storage locations according to the identification codes determined.

Advantageously the inventory control system can be arranged according to any of the configurations described herein.

Advantageously the method can be applied to the inventory control of tools, such as hand tools.

Advantageously the process can include at least one of the following: recording the time of removal and replacement of inventory items, detecting and recording the identity of a user, and checking the identity of a prospective user against a list of authorised users and allowing access to the inventory items only if the prospective user is authorised.

An embodiment of the invention will now be described, by way of example only, with * * reference to the accompanying drawings, in which: **** * * S...

Figure 1 is a perspective view of a tool cabinet with an open tool drawer including an S...

S ****5 arrangement of recesses for receiving tools, with each recess having a magnetic * S reading head located adjacent thereto, and a tool including a Wiegand tag; * *5 Figure 2 is a view from above of the open tool drawer of Figure 1; Figure 3 is an enlarged perspective view of the tool cabinet swipe card access system, output display and keypad; Figure 4 is an alternative drawer layout including an arrangement of recesses for receiving tools, with each recess having a magnetic reading head located adjacent thereto; Figure 5 is a schematic view of a Wiegand tag attached to a tool and a reader located adjacent its recess; Figure 6 is a schematic diagram illustrating the main components of an inventory tool drawer insert; and Figure 7 is a flow diagram showing the main steps of an inventory control process.

The tool cabinet 2 shown in the Figures includes a steel cabinet housing 4, which may be static or mobile (for example, it may be mounted on castors), four tool drawers 6a- 6d, the top drawer 6a being shown pulled out in Figure 1, four micro-switches 8a-d, several Wiegand reader heads 10, a computer processing device 12, a local display 14, a data transmission unit 16, a power supply unit 18, and a backup electrical supply in the form of a rechargeable cell 20.

Each drawer 6a-d includes a liner 7, for example of a rigid foam material, having a number of cut-out compartments (or recesses) 9a-f, which are shaped to receive specific * tools. Figures 1 and 2 show a first layout of recesses 9. The recesses are preferably . colour-coded, to provide a simple visual indication that a tool has been removed. For I...

example, the recesses may have a bright colour (e.g. yellow), while the top surface of * the drawer liner has a contrasting colour (e.g. black). The liner 7 also includes at least * one additional recess 20 that provides a fmger hole to enable a user to more easily * remove tools from the recesses 9a-f. Figure 4 shows an alternative layout of recesses 9.

Each of the micro-switches 8a-d is connected to the computer device 12. Each micro-switch 8a-d is associated with one of the four drawers 6a-6d and is arranged to be activated when its associated drawer is closed. Thus from the signals received from the micro-switches 8a-d, the computer device 12 knows when the tool cabinet 2 is open, when it is closed, and which drawer 6a-d has been opened.

Each Wiegand reader 10 is connected to the computer device 12. Each reader 10 is arranged to detect the presence of a Wiegand tag 22 that is attached to each tool 24 stored in the tool cabinet 2. Each tag 22 includes an arrangement of Wiegand wires 25.

Each Wiegand wire is produced by cold-working, for example a Vicalloy wire (a mixture of cobalt, iron and vanadium) and then age-hardening to retain the effects of the cold-working process. This produces a wire having a work-hardened surface and a soft magnetic core, wherein the hard surface has a higher magnetic coercivity than the core.

When an alternating magnetic field is applied to the Wiegand wire, the magnetic fields of the shell and core switch poiarity thereby causing Wiegand pulses to be generated.

The Wiegand tag 22 includes first and second rows of Wiegand wires 25a,25b. The first and second rows are mainly offset from one another, with a small amount of interleaving in a central portion of the tag. The wires 25a of the first row are interspersed with the wires 25b of the second row such that there is an alternating pattern of first row wires 25a and second row wires 25b as shown in Figure 5. The alternating pattern does not have to be even and does not have to be uniform so for example, there can be a wire in the first row followed by two wires in the second row, * ** followed by two wires in the first row followed by three wires in the second row, etc. Of S course uniform patterns can be used. * *** * * *5*S

The Wiegand reader 10 is arranged to stimulate the first and second rows of Wiegand * wires 25a,25b such that the wires in the first row have opposite polarity to the wires in the second row. This causes pulses to be generated in opposite directions in a detection * coil 41 according to whether a wire in the first or second row is activated thereby enabling a binary code to be hard-wired into the tag 22. That is, all of the Wiegand wires in the first row 25a have binary bit "1" values and all of the Wiegand wires in the second row 25b have binary bit "0" values. The relative positions of the wires in the first and second rows enables different binary codes to be encoded into the tag. Thus a unique identifier can be assigned to each tool 24.

A data processing device, which is preferably a remote computer system 26, though can be the local computer device 12, is arranged to analyse the signals received from the readers 10 and converts them into binary codes. The system uses a data format such that different parts of the binary code stored in the tag provide different information, for example a first part relates to the owner code, and a second part relates to a unique tool identifier. Optionally, the format can include a part of the code that associates the tool with its reader 10, the cabinet 2 and / or the cabinet drawer 6. The computer device 12 can compare the received code with a set of codes stored in a database (either local or remote) and determine therefrom whether or not the tool 24 is being placed into or removed from the correct recess 9. If the code format includes a part that relates to the reading device associated with the recess 9 in which the tool 24 is stored, from a knowledge of which reading device 10 is supplying the code to the computer system 26, the computer system 26 is able to determine from that part of the code whether or not the tool is being placed into or removed from the correct recess 9.

There are various readers 10 that can be used in order to achieve the Wiegand effect. A typical reader 10 includes a first stage that includes a permanent magnet 27 providing a saturating magnetic field that orients the core and shell magnetic fields in the same direction, and a second stage including a substantially E-shaped core 29 having outer * leaves of soft magnetic materials which 31,33 and a centre part made from a magnetically inert material 35. Adjacent the core 29 are permanent magnets 37,39 that are arranged to provide the reversal of the magnetic fields of the first and second rows * of Wiegand wires 25a,25b when the tool 24 is inserted into and removed from the S...

*: recess 9. When the Wiegand wires approach the magnetic field generated by magnets 35,37, the wire switches poiarity into its reverse state, in which the work-hardened *: *.* portion of the wire captures and reverses the plurality of the soft inner core. Further movement causes the wire to change back to its initial state, which induces an electrical signal in the coil 41.

By continuously monitoring the changes in state of the Wiegand wires 25a,25b a binary output is captured and transferred to the computer system 26 for processing.

Therefore as the tool 24 is placed into and removed from its recess 9, the reader 10 reads the binary number coded into the tag 22 and therefore detects the removal or replacement of a tool 24.

Additionally, or alternatively, the Wiegand effect can be achieved by providing a reader that can produce an alternating magnetic field, for example by including an electro-magnet that can be used to stimulate the Wiegand wires. A particular advantage of this is that the tag 22 can be read when there is no relative movement between the tag 22 and the reader 10 and therefore allows the tag 22 to be read when the tool 24 is static within its recess 9. This enables the reading process to take place when the drawer 6 is closed thereby benefiting from the shielding provided by the closed cabinet 2. The alternating electromagnetic field can be provided by applying a current to the coil 41 or alternatively by providing an entirely separate e1ectromagnetic device in addition or as an alternative to the reader 10 described above. Reading the tags 22 in-situ can be done periodically to ensure that all the tools 24 are present.

A significant advantage of the Wiegand tag 22 is that it does emit radio signals and therefore can be taken into more sensitive manufacturing areas, since the magnetic field emitted by the wires in their normal state is small. A further advantage of this system is that the tag 22 enables the system to identify the specific tool, which overcomes the tool migration problem. Thus if a substantially identical tool which belongs to one cabinet is * : *:: placed into corresponding recess in another cabinet, the system is able to determine that *** * the tool 24 has been placed into the wrong cabinet. A further problem is for tools such as socket heads, which may have the same outside external dynamic diameter, wherein the difference between the socket sizes is an internal diameter and therefore it is ** S.*S * possible to place the wrong sized socket into a recess without it being visually obvious.

* The inventory control system recognises that the socket has been placed in the wrong recess when the code is read and can send a notification to a supervisor, and/or the user of the socket tool 24.

Although it is not necessary to locate the tool cabinet 2 within a sensitive working environment it is highly desirable to do so to cut down on the distance workers have to travel in order to retrieve and replace tools. If the tool cabinet 2 is located in a sensitive working environment it is important that the cabinet 2 has adequate shielding to block or limit the strength of the magnetic field generated by the reading device in the environment to prevent equipment from being damaged. Optionally, the computer device 12 can be arranged to allow the reader 10 to be activated only when all the tool cabinet drawers 6a-6d are closed. The computer system 26 determines this from the output of the micro-switches 8. Thus when a user opens one of the drawers 6, the reader will not operate. It will only operate when the drawer 6 has been closed again.

Optionally, the tool cabinet 2 can also include an electrically operated lock 30 for the drawers, which can be activated using a key, a personal identification number (PIN) via an input pad 15, or a swipe card system 17 containing data identifying the user. This allows the identity of the user to be monitored each time the tool cabinet 2 is opened.

This data can be stored in a database of tool usage. Optionally, the computer device 12 can be arranged to prevent operation of the reader 10 when the lock 30 is open. In this instance, the reader 10 will only operate when all the drawers 6a-d are closed and the cabinet 2 is locked to prevent a user opening a drawer when the tag reader 10 is operating.

The input pad 15 can be used to input other data, such as a part number or to select options on a menu system.

* The main components of an inventory control system, which includes the tool cabinet 2 **** * * ** described above, are shown schematically in Figure 6. The system includes the tool * * ** cabinet 2 and the remote computer system 26, which is connected to the cabinet 2 via **** * the data transmission unit 16. The computer system 26 includes a central processing *S**** * unit 32, a power supply 34 and a visual display unit 36 and optionally a network * * connection 38. The computer system 26 includes a database of all the tools 24 stored in the cabinet 2.

An inventory control process carried out using the system described above will now be described with reference to Figure 7. First, a user (for example a technician or a mechanic) identifies him or herself 40 by entering a PIN or using a swipe card. The identity of the user is checked against a list of authorised users held on the computer system 26 and if authorisation of the user is valid, the lock 30 to the tool cabinet is unlocked 42, allowing the user to gain access to the tools 24. At the same time, the identity of the user and the time are recorded 42 in the computer system 26 database. If the identity of the user is not validated as that of an authorised user, the tool cabinet 2 remains locked, preventing access to the tools 24. Optionally, a warning may be sent to the computer system 26 to indicate that an unauthorised person has attempted to gain access.

Assuming that the identity of the user has been validated, the user then opens one of the drawers 6a6d. The user then removes 44 the required tools from the cabinet 2. As this takes place, for each of the tools removed, the Wiegand reader 10 associated with the recess 9 from which the tool is removed reads 44 the code stored in the tag 22 and sends the received signals to the computer system 26 via the computer device 12. The computer system 26 determines which tools 24 have been removed by comparing the codes received from the readers 10 with the list of all the tools stored in the database.

This information is recorded 46, together with the time of removal and a user identifier.

After the user has closed the cabinet, after a short delay, the cabinet relocks automatically and the registered user is signed off 50. Additionally, or alternatively, the readers 10 ca.n be arranged to read all of the tags present in the cabinet 7 after the drawer 6 has been closed. In this case the tools 24 that have been removed are identified * ** by detecting those tools that are present and comparing the detected tool codes with the list of all tools associated with the cabinet. **IS * * ****

* : * After completing the assigned task, the user re-enters his/her ID 40, and once this has been verified, the cabinet unlocks 42 and the identity of the user is registered on the * ::* computer system 26. The user opens the appropriate drawer 6a-6d, replaces 52 each of the tools in the cabinet and closes the drawer. For each tool 24 that is replaced, the reader 10 reads the code stored in the associated tag 22 and sends signals to the computer system 26 for identification. If the tool is identified as belonging to the container, then another entry is made in the database 56, identifying replacement of the tool, the time and the identity of the user. If the computer system 26 determines that the information received from the reader 10, that an incorrect tool, or no tool, has been replaced into the tool cabinet 2, it issues an alert 60, which enables a supervisor to investigate the incident.

The user then closes the cabinet and is logged off 58.

The computer 26 therefore records which tools are in use, who has taken them and the time at which the tools are removed and returned. Using this information it is a simple matter for a supervisor to check whether all the tools are present in the cabinet and, if any are missing, who has taken them and when. The supervisor can also check that the tools taken for a particular task are appropriate for that task. Checks can be carried out by the supervisor whenever required or they can be instigated automatically, for example whenever the cabinet is closed. In addition the tool cabinet can be checked visually at regular intervals, to ensure the full complement of tools is present and that the automatic system is operating correctly. The computer 26 can also keep a continuous log of how long each tool has been in use, which may be useful for tools and measuring instruments such as torque wrenches that have to be recalibrated at preset intervals. The supervisor can also use the information as part of a schedule management system, which assigns an amount of time to a particular task. If the tool is not returned within a certain period an alert can be issued. This can provide an early indication that a tool is missing or that a particular job is overrunning. The system can also be 1:1:.. progranmied to disregard the absence of tools that have been removed deliberately for I...

* *** repair or replacement.

* The computer system 26 can include a learn function, which enables the database to log * .S..

* all the tools stored in a tool cabinet 2 and keep a record of the tools for future inventory *: *::* control processes. The learn function is very simple since it merely requires the magnetic tag readers 10 to detect which tools are present in the tool cabinet 2 using the electromagnets and to then keep a permanent record that the detected tools are now associated with a particular cabinet for the purposes of inventory control. If new tools are added to the cabinet, the learn process can be rerun to register the new tools. This is a significant advantage over prior art systems, wherein it is necessary to manually input associations between tools and the cabinets and is therefore significantly slower. The database can include more extensive tool information such as tool characteristics as well as an associated tool identifier.

It will be appreciated by the skilled person that modifications can be made to the above embodiment that are within the scope of the invention. For example, the computing device 12 can include some or all of the processing functions of the remote computer system 26 so that the tool cabinet 2 is a stand alone unit. The data connection 16 is optional in this case. Alternatively, some or all of the data processing can take place on the remote computer system 26. In this case, it may not be necessary to have a separate computer device 12 within the cabinet 2.

The tool cabinet 2 can be of any suitable design and may not include drawers 6 but rather may have one or more storage compartments that are accessible by one or more doors. The micro-switches 8 can determine whether or not the doors are closed.

The invention is not strictly limited to tool cabinets but is also applicable to cupboards, storage containers, storage rooms, vehicles and the like. Also, the invention can be used in relation to trays or other tool storage locations that are not enclosed, for example some work stations in factories have trays of tools without any additional casing. These trays can be replaced with modified trays similar to the drawer liners 7, which have a * * *. ** recess for each of tool, a tag reader 10 associated with each recess and a data processing * S* ***** device similar to the computer device 12 and I or computer system 26. Similarly, the invention can be applied to gun racks for military applications, wherein a reader 10 is positioned adjacent each gun receiving location on the gun rack, each reader 10 is *SIS* * connected to a data processing device similar to the computer device 12 and / or *: *::* computer system 26 and each weapon includes a magnetic effect tag 22.

Instead of using micro-switches, other means can be used for detecting whether a cabinet drawer or door is open, for example sensor such as magnetic or optical sensors.

The data connection can be a physical connection such as a wire of fibre optic cable or a wireless connection such as an infrared connection, Bluetooth�, or Wi-Fi connection.

A plurality of tool cabinets 2 can be connected to the remote computer system 26. Thus the remote computer system 26 can be arranged to monitor and record the removal and replacement of tools from a network of tool cabinets within, for example a manufacturing facility. Via the network connection 38, the computer system 26 can monitor and record the removal and replacement of tools of tool cabinet at other manufacturing sites. For example, a large manufacturing company may have several manufacturing facilities located in different countries and the network connection 38 can allow a central facility to receive data from multiple sites to monitor tool usage.

This data can be used in conjunction with job schedule information to compare the productivity of different facilities.

Other types of magnetic tags can be used, for example by adapting the technologies of Single-Molecule Magnets (SMMs). These magnetic structures are molecular in nature, have a high resilience and are suitable for encoding of binary data.

It is envisaged in the future that other types of magnetic data tags that can store data may become available and the invention may be implemented using them. * ** * * * * ** * ** * I I,-. *IIa * I

*1 II s0 * *

I SI * S S * I-

Claims

CLAIMS1. An inventory control system including a set of inventory items in which each inventory item includes an identification tag having an identification code magnetically encoded therein; a set of inventory item storage locations; at least one reading device arranged to read the identification tags, and a data processing system arranged to receive signals from the or each reading device and to monitor the removal and replacement of the inventory items from the storage locations according to the determined identification codes.
2. An inventory control system according to claim 1, including a set of reading devices in which each reading device is associated with one of the storage locations and is arranged to read identification tags at that storage location.
3. An inventory control system according to claim 1 or 2, wherein the or each reading device is arranged to subject the identification tag being read to a magnetic field thereby causing the identification tag to induce electrical signals in a conductor and the data processing system is arranged to determine the identification codes from the induced signals and to monitor the removal and replacement of the inventory items from the storage locations according to the identification codes determined.
4. An inventory control system according to any one of the preceding claims, wherein each tag includes an arrangement of permanent magnetic elements or *:* :* deposits that can be detected by the reading the device and wherein the arrangement *: : : of the elements or deposits determines the code encoded in the tag. a
5. An inventory control system according to claim 4, wherein each identification tag includes a plurality of Wiegand wires each having an outer shell * ,. and a core having different magnetic properties, and wherein the tag is arranged to operate on the Wiegand effect principle.
6. An inventory control system according to claim 5, wherein each identification tag includes first and second rows of Wiegand wires and each reading device is arranged to stimulate the first and second rows with opposite polarity thereby inducing electrical pulses in the conductor in opposite directions.
7. An inventory control system according to claim 5 or 6, wherein each reading device includes a first magnetic device for aligning the magnetic fields of the shells and the cores of the Wiegand wires in the same direction.
8. An inventory control system according to claim 7, wherein each reading device includes a second magnetic device for switching the direction of the magnetic fields of the cores of the Wiegand wires, thereby inducing electrical signals in the conductor.
9. An inventory control system according to claim 8, wherein the second magnetic device includes a substantially E-shaped core having a centre leg and two outer legs, and wherein the conductor comprises a pick-up coil wound around the centre leg of the core.
10. An inventory control system according to any one of the preceding claims, wherein each reading device includes an electromagnet device for generating a variable magnetic field for stimulating the identification tag.
11. An inventory control system according to any one of claims 1 to 4, wherein * ** the or each reading device includes a set of sensors for detecting the magnetic elements or deposits, and preferably includes a set of Hall effect sensors or magnetic reed switches. S. *a * S 5.5.

* $ .
12. An inventory control system according to any one of the preceding claims, * wherein the data processing system includes means for decoding the signals detected by the reading devices into binary codes.
13. An inventory control system according to any one of the preceding claims, wherein the data processing system is arranged to compare the codes received from the reading devices with a set of inventory item codes stored in a database.
14. An inventory control system according to any one of the preceding claims, wherein each inventory item storage location comprises an individually-shaped recess for receiving a specific inventory item, the shape of the recess being matched to the shape of the inventory item, and wherein each recess includes at least one of the reading devices located therein or adjacent thereto.
15. An inventory control system according to any one of the preceding claims, including an enclosure, such as a container for storing tools, having a closure member that can be opened and closed by a user in order to gain access to the enclosure, and the system includes detector means for detecting whether the closure member is open and/or closed.
16. An inventory control system according to claim 15, including means for inhibiting the operation of the set of reading devices according to the output of the detector means.
17. An inventory control system according to claim 15 or 16, wherein the container includes a plurality of storage compartments,
18. An inventory control system according to any one of the preceding claims, * : :* including a learning system arranged to perform a routine for detecting all of the identification tags that are readable by the or each reading device and for generating *** a record in memory means that associates all of the detected inventory item tags S...with the enclosure.

* S.... * .

* ,
19. An inventory control system according to any one of the preceding claims, *.. wherein the enclosure includes a locking mechanism for controlling access to the inventory items.
20. An inventory control system according to claim 19, including means for determining the operational status of the locking mechanism and means for irthibiting the operation of the set of reading devices according to the operational status of the locking mechanism.
21. An inventory control system according to claim 19 or 20, wherein the locking mechanism includes an input device for entering the identity of a user.
22. An inventory control system according to claim 21, wherein the locking mechanism is arranged to automatically open when an authorised user has been identified.
23. An inventory control system according to any one of the preceding claims, wherein the data processing system includes means for recording the identity of a user.
24. An inventory control system according to any one of the preceding claims, wherein the data processing system includes means for recording the time of removal and replacement of inventory items.
25. An inventory control system according to any one of the preceding claims, wherein the data processing system is located remotely from the enclosure and is connected to the or each reading device by a data link.
26. An inventory control system according to any one of the preceding claims, : wherein the container includes a local indicator device for indicating the presence and/or absence of inventory items in the container. * * S...

* : *
27. An inventory item container for use in an inventory control system, said * .. container including, a set of inventory items in which each inventory item includes an identification tag having an identification code magnetically encoded therein; a set of inventory item storage locations; at least one reading device arranged to read the identification tags, and a data processing system arranged to receive signals from the or each reading device and to monitor the removal and replacement of the inventory items from the storage locations according to the determined identification codes.
28. A container according to claim 27, including a set of reading devices in which each reading device is associated with one of the storage locations and is arranged to read identification tags at that storage location.
29. A container according to claim 27 or 28, wherein the or each reading device is arranged to subject the identification tag being read to a magnetic field thereby causing the identification tag to induce electrical signals in a conductor and the data processing system is arranged to determine the identification codes from the induced signals and to monitor the removal and replacement of the inventory items from the storage locations according to the identification codes determined.
30. A container according to any one of claims 27 to 29, wherein each tag includes an arrangement of magnetic elements or deposits, for example on a substrate, that can be detected by the reading the device and wherein the arrangement of the elements or deposits determines the code encoded in the tag.
31. A container according to claim 30, wherein each identification tag includes a plurality of Wiegand wires each having an outer shell and a core having different magnetic properties, and wherein the tag is arranged to operate on the Wiegand * :* : :* effect principle. S... * S *5S*
32. A container according to claim 31, wherein each identification tag includes *..S * first and second rows of Wiegand wires and each reading device is arranged to * S....stimulate the first and second rows with opposite polarity thereby producing induced : :* pulses in the conductor in opposite directions.
33. A container according to claim 31 or 32, wherein, each reading device includes a first magnetic device for aligning the magnetic fields of the shells and the cores of the Wiegand wires in the same direction.
34. A container according to claim 33, wherein each reading device includes a second magnetic device for switching the direction of the magnetic fields of the cores of the Wiegand wires, thereby inducing electrical signals in the conductor.
35. A container according to claim 34, wherein the second magnetic device includes a substantially E-shaped core having a centre leg and two outer legs, and wherein the conductor comprises a pick-up coil wound around the centre leg of the core.
36. A container according to claim 30, wherein the or each reading device includes a set of sensors for detecting the magnetic elements or deposits, and preferably includes a set of Hall effect sensors or magnetic reed switches.
37. A container according to any one of claims 27 to 36, wherein the data processing system includes means for decoding the signals detected by the reading devices into binary codes.
38. A container according to any one of claims 27 to 37, wherein each reading device includes an electromagnet device for generating a variable magnetic field for stimulating the identification tag. * ** * . *

*.:.
39. A container according to any one of claims 27 to 38, wherein the data **.* processing system is arranged to compare the codes received from the reading * devices with a set of inventory item codes stored in a database.

** ** ** * S * *
40. A container according to any one of claims 27 to 39, wherein each inventory item storage location comprises an individually-shaped recess for receiving a specific inventory item, the shape of the recess being matched to the shape of the inventory item, and wherein each recess includes at least one of the reading devices located therein or adjacent thereto.
41. A container according to any one of claims 27 to 40, including a storage volume and a closure member that can be opened and closed by a user in order to gain access to the storage volume, and the system includes detector means for detecting whether the closure member is open and/or closed.
42. A container according to claim 41, including means for inhibiting the operation of the set of reading devices according to the output of the detector means.
43. A container according to claim 41 or 42, including a plurality of storage compartments.
44. A container according to any one of claims 27 to 43, including a learning system arranged to perform a routine for detecting all of the identification tags that are readable by the or each reading device and for generating a record in memory means that associates all of the detected inventory item tags with the enclosure.
45. A container according to any one of claims 27 to 44, including a locking mechanism for controlling access to the inventory items.
46. A container according to claim 45, including means for determining the operational status of the locking mechanism and means for inhibiting the operation * : :* of the set of reading devices according to the operational status of the locking mechanism. *S.

*..
47. A container according to claim 45 or 46, wherein the locking mechanism * includes an input device for entering the identity of a user. * **
48. A container according to claim 47, wherein the locking mechanism is arranged to automatically open when an authorised user has been identified.
49. A container according to any one of claims 27 to 48, wherein the data processing system includes means for recording the identity of a user.
50. A container according to any one of claims 27 to 49, wherein the data processing system includes means for recording the time of removal and replacement of inventory items.
51. A container according to any one of claims 27 to 50, including a data link for communicating with a remote computer system.
52. A container according to any one of claims 27 to 51, wherein the container includes a local indicator device for indicating the presence and/or absence of inventory items in the container.
53. An inventory control process for monitoring the removal and replacement of inventory items in an inventory control system including a set of inventory items in which each inventory item includes an identification tag having an identification code magnetically encoded therein; said process including using a set of inventory item storage locations and at least one reading device arranged to read the identification tags, and further using a data processing system arranged to receive signals from the or each reading device and to monitor the removal and replacement of the inventory items from. the storage locations according to the determined identification codes.*
54. An inventory control process according to claim 53, wherein the inventory *::: :* control system includes a set of reading devices in which each reading device is associated with one of the storage locations and is arranged to read identification I...tags at that storage location.***.**
S

*: *: :* An inventory control system according to claim 53 or 54, wherein the or each reading device is arranged to subject the identification tag being read to a magnetic field thereby causing the identification tag to induce electrical signals in a conductor and the data processing system is arranged to determine the identification codes from the induced signals and to monitor the removal and replacement of the inventory items from the storage locations according to the identification codes determined.
56. A process according to any one of claims 53 to 55, wherein the inventory items are tools.
57. A process according to any one of claims 53 to 56, wherein each identification tag includes a plurality of Wiegand wires each having an outer shell and a core having different magnetic properties, and wherein the tag is arranged to operate on the Wiegand effect principle.
58. A process according to claim 57, wherein each identification tag includes first and second rows of Wiegand wires and each reading device is arranged to stimulate the first and second rows with opposite polarity thereby producing induced pulses in the conductor in opposite directions.
59. A process according to claim 57 or 58, wherein, each reading device includes a first magnetic device for aligning the magnetic fields of the shells and the cores of the Wiegand wires in the same direction.
60. A process according to claim 59, wherein each reading device includes a second magnetic device for switching the direction of the magnetic fields of the cores of the Wiegand wires, thereby inducing electrical signals in the conductor. * * *SS*
61. A process according to claim 60, wherein the second magnetic device **** * includes a substantially E-shaped core having a centre leg and two outer legs, and * wherein the conductor comprises a pick-up coil wound around the centre leg of the * ** core. * * * * **
62. A process according to any one of claims 53 to 61, wherein the data processing system includes means for decoding the signals detected by the reading devices into binary codes.
63. A process according to any one of claims 53 to 62, wherein each reading device includes an electromagnet device for generating a variable magnetic field for stimulating the identification tag.
64. A process according to any one of claims 53 to 63, wherein the data processing system is arranged to compare the codes received from the reading devices with a set of inventory item codes stored in a database.
65. A process according to any one of claims 53 to 64, wherein each inventory item storage location comprises an individually-shaped recess for receiving a specific inventory item, the shape of the recess being matched to the shape of the inventory item, and wherein each recess includes at least one of the reading devices located therein or adjacent thereto.
66. A process according to any one of claims 53 to 65, wherein the inventory control system includes a locking mechanism for controlling access to the inventory items
67. A process according to any one of claims 53 to 66, including recording the time of removal and replacement of inventory items. * ** * * S * **68. A process according to any one of claims 53 to 67, including detecting and **SS recording the identity of a user of the inventory control system. 55SS * S* 69, A process according to claim 68, including checking the identity of a *: *: :* prospective user against a list of authorised users and allowing access to the mventoiy items only if the prospective user is authorised.