BACKGROUND [0002] Certain devices, such as hand-held tools and small appliances which are connected to an external power supply (e. g. household mains) through a power cord, are designed to be in motion during use. If the device is still powered on when not in use, the device may become damaged and/or create a safety hazard. For example, common household appliances with heating components, such blow dryers and irons for ironing articles of clothing, may present a fire hazard if left powered on and unattended for a period of time.

As another example, in a workshop, hand-held power tools and soldering tools may be damaged and/or create a safety hazard if left powered on when not in use.

[0003] Previous attempts to address the above identified problem have involved incorporating various safety features and shut-off mechanisms into the devices. For example, in a known"press"style iron design, an iron is connected by a swing arm to an iron table and is adapted to swing down on top of the iron table by means of a handle operated by an operator. The heated base of the iron is automatically lifted off the iron table when the handle is released by the operator. a fter a timea delav. tne i-on is automatically disconnected from its power supply. While functional, the disadvantage of this design is its mechanical complexity, and lack of mobility of the device.

[0004] In another known design, a device including a built-in heating component may have a power cord with a plug to connect the device to an external power supply. The device may include a circuit breaker which disconnects the power supply when a certain predetermined maximum temperature is reached. While functional, a disadvantage is that the shut-off temperature generally exceeds the normal operating temperature of the device, potentially creating an increased safety hazard for a period of time before power shut-off.

[0005] In yet another known design, a device consists of a housing with a built-in heating component, a power cord with a plug, a device orientation detector, and a circuit breaker which disconnects the power supply when the device is placed in a certain predetermined orientation. For example, the device may be an iron which automatically shuts off when oriented vertically and resting on one end, with the heated base oriented substantially perpendicular to the ironing table. While functional, a disadvantage of this design is that the automatic shut-off mechanism requires placement of the device in a predetermined orientation. If the device is left unattended in its normal operating position (i. e. with the heated base of the iron on top of an article of clothing), this shut-off mechanism would be ineffective.

[0006] What is needed is an apparatus for increasing the operational life and/or safety of a movable device which addresses one or more of the disadvantages mentioned above.

SUMMARY [0007] There is provided an apparatus for disconnecting a corded device from its external power supply when the device is not used for a period of time.

[0008] The apparatus comprises a sensor adapted to detect movement of at least a part of the corded device, and a disconnecting component adapted to disconnect the corded device from its power supply when there is lack of movement of the corded device. In an embodiment, the sensor generates variations in a measurable characteristic in response to movement of the corded device. The variations in the measurable characteristic are detected by the disconnecting component and used to determine whether to disconnect the corded device from its power supply. In an embodiment, the characteristic is an electrical characteristic, such as electrical resistance.

[0009] The sensor may comprise particles of conducting material enclosed in a housing, and the measurable characteristic is variations in electrical resistance of the particles of conducting material to current passing therethrough. An ohmmeter connected to the sensor by a pair of electrodes may be used to detect the variations in electrical resistance resulting from movement of the sensor (e. g. as caused by moving the corded device).

[00N 0] The conducting material may be made of particles of graphite in the form of beads, chips, granules, pellets, flakes, a mixture thereof, etc. that are sufficiently small and loosely packed to shift inside the housing when the sensor is moved. Other conducting material that mav re suitabby síze¢ to sniff inside the rousing mav also be used.

[00111 The particles of conducting material may be mixed with particles of insulating material, such that shifting of this mixture of particles inside the housing may provide more pronounced variations in measurable electrical resistance.

[0012] In an aspect of the invention, there is provided an apparatus for disconnecting a device connected by a cord to an external power supply, comprising: a sensor configured to generate variations in a measurable characteristic in response to movement of at least a part of the corded device; a disconnecting component operatively connected to the sensor, the disconnecting component being configured to detect and be responsive to the variations in the measurable characteristic to determine whether to disconnect the corded device from the external power supply, the disconnecting component being operative to disconnect the device from the external power supply.

[0013] In an embodiment, the sensor comprises particles of conducting material contained in a housing, and the measurable characteristic is an electrical characteristic of the particles of conducting material.

[0014] In an embodiment, the housing is flexible, elongate and mounted to the cord.

[0015] In an embodiment, the particles of conducting material comprises graphite.

[001sD ln an embodiment, the measurable characteristic comprises variations in electrical resistance to a current passing through the particles of conducting material in response to movement of the housing. [0017] In an embodiment, the disconnecting component comprises an ohmmeter, a logic component, a timer, and a switch, the ohmmeter being operatively connected to the sensor and suitably calibrated to detect the variations in electrical resistance.

[0018] In an embodiment, the logic component is configured to be responsive to the variations in electrical resistance detected by the ohmmeter in sending a periodic reset signal to the timer.

[0019] In an embodiment, the timer is configured to send a shut-off signal to the switch in the absence of the periodic reset signal being received from the logic component within a predetermined period of time.

[0020] In an embodiment, the sensor further comprises particles of insulating material in a mixture with the particles of conducting material.

[0021] In another aspect of the invention, there is provided a corded device connectable by its cord to an external power supply, comprising: a sensor configured to generate variations in a measurable characteristic in response to movement of at least a part of the corded device; a disconnecting component operatively connected to the sensor, the disconnecting component being configured to detect and be responsive to the variations in the measurable characteristic to determine whether to disconnect the corded device from the external power supply, the disconnecting component being operative to disconnect the device from the external power supply.

[0022] In an embodiment, the sensor comprises particles of conducting material contained in a housing, and the measurable characteristic is an electrical characteristic of the particles of conducting material.

[0023] In an embodiment, the measurable characteristic comprises variations in electrical resistance to a current passing through the particles of conducting material in response to movement of the housing.

[0024] In an embodiment, the disconnecting component comprises an ohmmeter, a logic component, a timer, and a switch, the ohmmeter being operatively connected to the sensor and suitably calibrated to detect the variations in electrical resistance.

[0025] In an embodiment, the logic component is configured to be responsive to the variations in electrical resistance detected by the ohmmeter in sending a periodic reset signal to the timer.

[0026] In an embodiment, the timer is configured to send a shut-off signal to the switch in the absence of the periodic reset signal being received from the logic component within a predetermined period of time.

[0027] In an embodiment, the sensor further comprises particles of insulating material in a mixture with the particles of conducting material.

0028] These foregoing and other aspects of the invention will be apparent from the "oilowme. more particular descriptions of exemplary embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS [0029] In the figures which illustrate various exemplary embodiments of the invention : FIG. 1 shows an illustrative schematic block diagram of a device, and an apparatus for disconnecting the device from its power supply in accordance with an embodiment of the invention.

FIG. 2A is a schematic representation of the sensor of FIG. 1 in accordance with an illustrative embodiment of the invention.

FIG. 2B is a more detailed schematic block diagram of the disconnecting component of FIG. 1.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS [0030] Referring to FIG. 1, there is shown an illustrative example of a device 10 and an apparatus for disconnecting the device 10 from its power supply in accordance with an embodiment of the invention.

[0031] As shown, in known manner, the device 10 is connected by a pair of conducting wires 12, and a power plug 14 to an external power supply, such as standard household mains (not shown). In addition, there is shown a sensor 15 and a disconnecting component 13 provided between the power plug 14 and the device 10. Plug 14 is suitable for establishing a supply of electrical current from an external power supply, such as the household mains. The sensor 15 mav be mounted so as to move with the conducting wires 'within an integrated-sheathed cord 1 o [0032] Now referring to FIG. 2A, in the present embodiment, the sensor 15 may comprise separate particles (e. g. beads, chips, granules, pellets, flakes, a mixture thereof) 15a (FIG. 3) of conducting material contained within a flexible elongate housing 15b. These particles 15a are packed sufficiently loosely so that they may shift within the housing 15b. When these particles of conducting material 15a shift within the housing 15b when the housing 15b is moved, the random conductive paths created in the particles may also shift, causing their effective"lengths"and their net"cross-section"or"diameter"to vary. As a longer "length"or a smaller"diameter"for a conducting wire translates into higher resistance, it will be understood that measurable variations in electrical resistance may result when the particles 15a shift.

[0033] By way of illustration, a suitable material for forming the conducting particles 15a in sensor 15 is graphite. Graphite is a particularly suitable, inexpensive material for forming the conducting particles 15a for containment in the housing 15b. However, virtually any other conducting material may also be used, provided that the material may be formed into a suitable particulate form. For example, a conductive metal such as iron may also be used.

[0034] In an embodiment, the particles of conducting material 15a may be mixed together with some particles of insulating material such as plastic (not shown), which may assist in making the variations in electrical resistance more pronounced when the conducting and insulating particles in this mixture shift together when the housing 15b is moved.

[M35J In an embodiment. the sensor 15 is suitably shaped such that it may be mounted to or co-tocated together ih the conducting wires 12. as part of an integrated cord \"he sensor 15 is configured to move with the conducting wires 12 in the integrated cord 16 such that, when the sensor housing 15b is moved (i. e. translated, twisted or bent) under external mechanical forces, the electrical resistance of the particles of conducting material 15a varies.

[0036] Generally, the sensor 15 should extend along a sufficient the length of the integrated cord 16 such that movement of the integrated cord 16 (i. e. during movement of the corded device 11) will cause sufficient variation in electrical resistance in the sensor 15 to be detectable by a suitably calibrated ohmmeter (e. g. ohmmeter 17 in FIG. 2B) provided in the disconnecting component 13.

[0037] Now referring to FIG. 2B, and still referring to FIG. 2A, there is shown a more detailed schematic block diagram of the disconnecting component of FIG. 1. In the present illustrative embodiment, the disconnecting component 13 includes an ohmmeter 17, a logic component 18, a timer 19, and a switch 20. It will be understood that each of these components in the disconnecting component 13 may divert sufficient operational power from the conducting wires 12 connected to the household mains via the plug 14.

[0038] As shown, the ohmmeter 17 is electrically connected to the sensor 15 of FIG. 1. In an embodiment, a pair of electrodes 17a and 17b are used to connect the sensor 15 to the ohmmeter 17. The ohmmeter 17 should be suitably calibrated to sense variations in electrical resistance in the sensor 15 in response to movements thereof. As a very simple example, a suitable in series resistor may be used in the ohmmeter circuit to calibrate the ohmmeter. [0039] As will be understood by those skilled in the art, the ohmmeter may be suitably configured with a voltage source to provide a current across its electrodes 17a, 17b, when the electrodes 17a, 17b are embedded in the sensor 15 for the purposes of measurement.

This current may be drawn, for example, through a suitable AC/DC converter and step down voltage transformer connected to the standard household electrical outlet through plug 14, or alternatively provided by a separate power source such as a battery.

[0040] The logic component 18 is operatively connected to the ohmmeter 17, and contains logic to control the timer 19 during operation of the device 10, in response to a signal or signals received from the ohmmeter 17, as explained below.

[0041] The switch 20 may be a simple two way switch that is switchable between a "closed"position (i. e. the device 10 is connected to its power supply drawn through the power plug 14), and an"open"position (i. e. the device 10 is effectively disconnected from its power supply). By way of example, the switch 20 may be embodied by a simple transistor switch. The switch 20 may be configured to switch from its closed position to its open position to effectively disconnect one of the conducting wires in response to a shut-off signal generated by the timer 19, as explained below.

[0042] In an embodiment, the logic component 18 may be a logic circuit suitably configured to be responsive to a signal or signals received from the ohmmeter 17. For example, the signal received from the ohmmeter 17 may be a constantly varying signal, or a series of intermittent signals separated by pauses. In response to the signal or signals received from the ohmmeter 17, the logic component 18 may be configured to send a reset signal, or a repeated series of reset signals to the timer 19. In an embodiment, the logic component 18 may be embodied in a chip.

[0043] As will be appreciated by those skilled in the art, one or more of the components contained in the disconnecting component 13 may be integrated into an application specific integrated circuit.

[0044] In operation, when the device 10 is in use, it is connected to a power supply by the conducting wires 12, the disconnecting component 13, and the power plug 14. As the device 10 is moved (e. g. as an iron is moved back and forth over an article of clothing), the sensor 15 in the integrated cord 16 also moves back and forth.

[0045] As explained above, when the sensor 15 is physically moved by an external mechanical force, the electrical resistance of the sensor 15 changes. As also explained, the ohmmeter 17 connected to the sensor 15 via electrodes 17a, 17b is suitably calibrated to sense variations in electrical resistance caused by movement of the sensor 15 in the integrated cord 16.

[0046] As long as the corded device 10 is being used (i. e. is being moved), the ohmmeter 17 detects variations in electrical resistance in the sensor 15, and the logic component 18 continues to receive a signal or signals generated by the ohmmeter 17. In response to the signal or signals received from the ohmmeter 17, the logic component 18 is configured to send a periodic reset signal to the timer 19. As long as the timer 19 continues to receive a periodic reset signal from the logic component 18, the timer 19 is prevented from sending a shut-off signal to te switch 20. [0047] However, if the corded device 10 is powered on and is left in a stationary position, the ohmmeter 17 will stop detecting variations in the electrical resistance in the sensor 15, and will stop sending signals to the logic component 18. This, in turn, will cause the logic component 18 to stop sending the periodic reset signals to the timer 19. If the timer 19 reaches its predetermined maximum time value without receiving a reset signal from the logic component 18, the timer 19 sends the shut-off signal to open the switch 20, thereby disconnecting the power supply to the device 10. As will be appreciated, a suitable, predetermined maximum time value for the timer 19 may be selected such that the device 10 is not shut-off too frequently after only a brief period of non-use, and is not left on too long such that any potential safety hazard is minimized, such as for example one minute.

[0048] For certain devices, e. g. a household iron, in order to allow the device to reach an operating state, the logic component 18 may be programmed to exceed the predetermined maximum time value for the timer 19 upon initial power up. After initial power up, the logic component 18 may revert to normal operation to shut-off the power based on the predetermined maximum time value for the timer 19.

[0049] While an exemplary embodiment of the invention have been described, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention.

QOOgO] For example, while variations in electrical resistance are detected in the illustrative embodiment described above, it will be appreciated that this is just one measurable characteristic of the sensor 15 that may be used. A detector other than an ohmmeter may be used to measure other characteristics of the sensor 15.

[0051] Also, while the disconnecting component 13 (FIG. 1) is shown adjacent the power plug 14 with the sensor 15 extending towards the device 12, it will be appreciated that the disconnecting component 13 may just as easily be situated adjacent the device 10, with the sensor 15 extending towards the power plug 14.

[0052] In another embodiment (not shown), the disconnecting component 13 may be integrated into the device 10, with the sensor 15 extending outwardly from the device 10 along the integrated cord 16. In this case, the disconnecting component 13 may be provided with a separate power supply (e. g. through another set of conducting wires or via a battery) so that it is not also disconnected at the same time.

[0053] Furthermore, while the sensor 15 is shown extending substantially along the length of the integrated cord 16, it will be understood that any configuration of the sensor 15 which provides sufficient variation in electrical resistance detectable by a suitably calibrated ohmmeter 17 may be used.

[0054] In addition, where the illustrative embodiment describes various components such as the timer 19 and the switch 20 being responsive to a"signal", it will be understood that the signal may either be a"positive"signal or a"null"signal, with corresponding changes in logic. [0055] Also, the housing 15b may be provided in any configuration which allows the particles of conducting material 15a to shift during movement of the housing. For example, the housing 15b may be a round tube, or a substantially flat rectangular tube partially formed by laminates trapping the particles 15a loosely therebetween. The housing 15b may also be provided with internal insulating structures which may facilitate a degree of controlled shifting of the particles 15a.

[0056] Therefore, the scope of the invention is limited only by the following claims.