GB2478163A

GB2478163A - Liquid vessels

Info

Publication number: GB2478163A
Application number: GB1003471A
Authority: GB
Inventors: David Andrew Smith; Robert Henry Hadfield; Antonio Martin Gaeta; Ian Geoffrey White; Robin Keith Moore; Yuan An; Peter Hallam Wright; Jeremy Siddons; Andrew Hunt; Paul Boundy; Simon M Whiteley
Original assignee: Otter Controls Ltd
Current assignee: Otter Controls Ltd
Priority date: 2010-02-18
Filing date: 2010-03-02
Publication date: 2011-08-31
Anticipated expiration: 2030-03-02
Also published as: CN102762135A; EP2536317A2; GB201003611D0; WO2011101642A2; JP2013519485A; GB201017391D0; GB201008015D0; CN102762135B; GB201003471D0; WO2011101642A3; GB2478021A; GB201019649D0; GB2478163B; GB2478026A; GB2477944B; JP5950829B2; GB2477944A; GB201021926D0; GB201002777D0

Abstract

A liquid heating vessel with a valve through which liquid and steam can be dispensed, the valve being arranged to close when the vessel is tipped over. The valve may normally be closed when the vessel is upright. The valve has first sealing faces that close when the vessel is upright and second sealing faces which close when the vessel is tipped. The vessel may have a user-actuatable mechanism which can prevent the valve from closing. The valve may be designed to remain open when the vessel is tipped in a predetermined direction. A liquid heating vessel is also described wherein there is a steam outlet separate to the liquid dispensing outlet, wherein the liquid dispensing outlet has a user-actuated mechanism which is biased towards being closed unless opened by the user-actuated mechanism. A liquid vessel having a sensor to sense the level of liquid in the vessel is also disclosed wherein a plurality of capacitor plates are located circumferentially around the liquid vessel such that the measured capacitance indicates the volume of fluid within the vessel. An electrical component being located in an appliance wherein an optical communication means is provided for communication through a seal is also disclosed.

Description

Electrical Appliances

Field of the Invention

[0001] The present invention relates to electrical appliances and components therefor. Some aspects of the invention are directed to cordless electrical appliances. Other aspects are directed to liquid heating appliances with safety features to reduce or eliminate spillage if the appliance is accidentally tipped or knocked over. Other aspects are directed to liquid level sensors for liquid vessels.

Background of the Invention

[0002] In a cordless appliance, the appliance proper includes a cordless connector that is operable to cooperate with a corresponding cordless connector on a power base. Thus, when the appliance proper is mounted on the power base, power may be supplied to the appliance proper. Such arrangements allow a power base to be connected to a domestic power supply (such as by a plug), whilst further allowing the appliance proper to be removed from the base for various operations, such as dispensing heated liquid from a cordless liquid heating appliance. The above types of cordless electrical connectors have also found use on other domestic appliances, such as food processors, blenders and the like. This arrangement provides an advantage that the processed/blended food can be more easily dispensed by a user.

[0003] 360° cordless connectors, as described for example in WO-A-94/06185, allow the appliance proper to be rotated freely relative to the power base, so that the appliance proper may be positioned on the power base with any azimuthal orientation.

[0004] However, as will be appreciated, appliances such as food processors, blenders and, to a lesser extent kettle jugs, need regular cleaning. In particular, cordless appliances for containing food or liquids other than water require cleaning after each use. Such a task is time consuming and may be difficult to perform manually.

[0005] It would be desirable to provide a cordless appliance where the detachable part of the appliance can be washed in a dishwasher, by immersion in water or otherwise easily cleaned. Sealing arrangements for such a washproof appliance are disclosed in WO-A-09/109762.

[0006] It would be preferable to minimize the components in the appliance proper that need to be sealed, such as electrical components. For example, electrical power switching components may be located in the power base, but this requires some means of signalling the state of the appliance proper to the power base, so that power may be switched in response to the state of the appliance proper.

[0007] One way of signalling from the appliance proper to the power base is to provide additional electrical contacts therebetween, for example as disclosed in GB-A-23788 18 or in WO-A-01/282294. However, these additional contacts must themselves be sealed if the appliance proper is to be washable. Moreover, any debris on the low voltage contacts may prevent electrical contact from being made, and the debris will not be burnt away as might occur on high-voltage contacts.

[0008] WO-A-2008/155538 discloses a cordless appliance with wireless signalling between the appliance proper and the base, for example by means of a circular light guide concentric with a cordless electrical connector. Whilst this arrangement is advantageous in that it allows signalling between the appliance proper and the base while allowing the use of 360° cordless connectors, the arrangement requires additional optical connecting components which add to the complexity of the arrangement.

[0009] With electrical liquid heating appliances, there is a risk of spillage of hot liquid if the appliance is accidentally tipped or knocked over. Since the liquid may be at or close to boiling, such spillage can cause severe scalding to the user or bystanders.

[0010] There have been many proposals in the state of the art to reduce or inhibit such spillage, most of which are impractical or at least have never been incorporated into commercial products. The solutions proposed in the state of the art are generally one of two types: automatic types in which liquid can only be poured out when the appliance is in a particular orientation, and manual types in which liquid can only be poured out when an interlock is manually released. The state of the art is mostly directed to domestic water boiling appliances, referred to hereafter as safety kettles.

[0011] One particular problem common to both types is the need to allow pressure release, particularly to release steam pressure within the appliance. For example, JP-A-2008212315 discloses a manual type safety kettle with a separate venting outlet for steam. In tests of a Tiger' brand kettle commercially available in Japan and based on the disclosure of that patent application, boiling water spurted vigorously from the venting outlet when the kettle was tipped onto its side. However, if the heating vessel were completely closed by the interlock, as for example in GB-A-2272629, there is a risk that steam pressure will build up inside the vessel until it explodes. GB-A-2305353 discloses a safety kettle with a steam valve that closes when the kettle is tipped over. However, in the case of a corded kettle, the water may continue to boil after the kettle is tipped over, so that steam pressure builds up inside the kettle. In the case of a cordless kettle, the temperature difference between the heating element and the water may cause boiling to continue for a short while after the kettle is knocked over, so that pressure would also build up to some degree.

[0012] Automatic-type safety kettles generally do not address the problem of pressure build-up. For example, GB-A-2 189378 discloses a spout flap that closes automatically if the kettle is not orientated correctly for pouring. DE-A-197408261 discloses a kettle lid that can only be opened when the kettle is upright.

[0013] Another problem to be addressed in safety kettles and the like is the need to allow easy filling and pouring. In the state of the art, the safety features intended to inhibit spillage also tend to make pouring or filling more difficult.

[0014] Another problem to be addressed is the reliable detection and/or indication of liquid level in a vessel when the vessel is at a substantial angle from the vertical, such as when the vessel is tipped forwards or backwards for filling. WO-A-2008/155538 discloses a magnetic float arranged to actuate one or more of a series of reed switches at different heights; alternatively, an array of electrodes or capacitive level sensors may be used. WO-A- 2008/119966 discloses the use of a capacitive level sensor array positioned around the perimeter of a kettle, either within or outside the water reservoir, to measure the water level when the kettle is at an angle.

Statement of the Invention

[0015] According to one aspect of the present invention, there is provided a liquid heating vessel having a valve through which liquid can be dispensed, the valve being arranged to open under steam pressure within the vessel, and being arranged to close when the vessel is tipped over. In this way, a single valve provides both steam venting and spill prevention from the vessel.

[0016] The valve may comprise an overcentre mechanism that closes the valve when the vessel is tipped.

[0017] Preferably, the valve is arranged to be normally closed when the vessel is in an upright orientation. In this way, thermal losses through the valve can be reduced. The valve may have first sealing faces that close when the vessel is in an upright orientation, and second sealing faces that close when the vessel is tipped.

[0018] The valve may be prevented from closing when the vessel is tipped by a user-actuated mechanism, to allow dispensing of liquid through the valve. Alternatively or additionally, the valve may be prevented from closing when the vessel is tipped in a specific orientation, without the need for user actuation of the valve.

[0019] According to another aspect of the invention, there is provided a liquid heating vessel having an outlet for dispensing liquid from the vessel, and a user actuated mechanism arranged to open the dispensing outlet for dispensing when actuated. The user-actuated mechanism may be biased to a closed position so that liquid cannot be dispensed through the dispensing aperture. In one embodiment, in the closed position the dispensing outlet is open to a steam passage that opens towards an opposite side of the vessel from the dispensing outlet. In another embodiment, there is provided a separate steam outlet from the dispensing outlet. The separate steam outlet may be closed by a valve that opens under steam pressure, but may close when the vessel is tipped.

[0020] According to another aspect of the present invention, there is provided a liquid vessel having a liquid reservoir and a capacitative liquid level sensor for sensing the liquid level within the reservoir, the sensor comprising a plurality of capacitor plates each extending in a vertical direction of the reservoir and making a capacitative coupling with liquid within the reservoir through a portion of the wall of the reservoir, the capacitor plates being mutually spaced apart around the circumference of the reservoir such that the combined capacitance through the capacitor plates is representative of the volume of liquid within the reservoir, substantially independently of the angle of tipping of the reservoir.

[0021] Preferably, the vessel has an outer wall outside the wall of the reservoir.

[0022] The vessel may include means for indicating the volume of liquid within the reservoir in response to the liquid level sensor. The means for indicating may be substantially continuously variable, or may be responsive to one or more liquid level thresholds being exceeded.

[0023] According to another aspect of the present invention, there is provided a cordless electrical appliance comprising an appliance proper and a power base connectable together by means of respective cordless electrical connectors, the appliance proper having a component sealed therein by means of a seal and being arranged to communicate with the power base by means of electromagnetic radiation conveyed through the seal. Preferably, the electromagnetic radiation comprises light and the seal is arranged to act as a light guide for the light.

[0024] Advantageously, this arrangement allows wireless signalling between the appliance proper and the base without the need for an additional light guide, thereby allowing the appliance proper to be made washable with fewer components.

[0025] The seal may be concentric with the cordless electrical connector on the appliance proper, and the power base may include optical communication means arranged to interact with the seal when the appliance proper and the power base are connected electrically together, regardless of the relative rotation of the cordless electrical connectors.

Advantageously, this arrangement allows the use of 360° cordless connectors. The seal may be arranged to seal the cordless electrical connector within the appliance proper.

[0026] The seal within the appliance proper and/or the power base may include an optical transmitter and/or receiver located within the seal, for example within a pocket in the seal.

This arrangement improves the optical coupling between the seal and the transmitter and/or receiver.

[0027] An additional light guide may be positioned in optical communication with the seal and within the power base and/or electrical appliance.

Brief Description of the Drawings

[0028] There now follows, by way of example only, a detailed description of preferred embodiments of the present invention, with reference to the figures identified below.

Figure 1 is a schematic cross-section of a cordless liquid heating appliance in an embodiment of the invention.

Figure 2 is a schematic diagram of the electrical and optical components of the cordless liquid heating appliance.

Figure 3a is an isometric view of a waterproof cordless connector for a vessel body in an embodiment of the invention.

Figure 3b is an exploded view of the underside of the waterproof cordless connector for the vessel body.

Figure 4a is an isometric view of a waterproof cordless connector for a power base in an embodiment of the invention.

Figure 4b is an isometric view of the underside of the waterproof cordless connector for the power base.

Figure 4c is an exploded view of the waterproof cordless connector for the power base.

Figure 5 is a cross-section of the waterproof cordless connectors for the vessel body and the power base, connected together.

Figure 6 is a side view of a waterproof cordless connector for the vessel body, in an alternative embodiment.

Figure 7 is a side view of a wateiproof cordless connector for the vessel body, in another alternative embodiment.

Figure 8a is a schematic cross-section of a liquid heating appliance with a spill-inhibiting safety feature in an embodiment of the invention.

Figures 8b to 8e show details of the safety feature, respectively in rest, boiling, pouring and tipping positions.

Figures 9a to 9c show details of an alternative safety feature, respectively in boiling, pouring and tipping positions.

Figures 1 Oa to 1 Oc show details of another alternative safety feature, respectively in boiling, pouring and tipping positions.

Figure ha is a schematic cross-section of a liquid heating appliance with a spill-inhibiting safety feature in another embodiment of the invention.

Figure 1 lb is a cut-away perspective view of a lid chamber arrangement of the embodiment of Figure lla.

Figures 11 c and 11 d are schematic cross-sections of a venting arrangement of the embodiment of Figure 11 a, with the user actuator in a normal position and actuated position respectively.

Figures 11 e and 11 f are schematic cross-sections of an alternative venting arrangement of the embodiment of Figure 11 a, with the user actuator in a normal position and actuated position respectively.

Figures 1 ig and 1 lh are schematic cross-sections of another alternative venting arrangement of the embodiment of Figure 11 a, with the user actuator in a normal position and actuated position respectively.

Figures 1 ii, 1 lj and 11k are schematic cross-sections of yet another alternative venting arrangement of the embodiment of Figure 11 a, in upright, pouring and tipping configurations respectively.

Figures 111 and 1 im are schematic cross-sections of another alternative venting arrangement of the embodiment of Figure 11 a, with the user actuator in a normal position and actuated position respectively.

Figure 12a is a schematic cross-section of a liquid heating appliance with a spill-inhibiting safety feature in another embodiment of the invention.

Figure 1 2b is a perspective view of a lid chamber arrangement of the embodiment of Figure 12a, with the upper part of the lid removed.

Figures 12c and 12d are schematic cross-sections of the pouring aperture of the embodiment of Figure 1 2a, respectively in open and closed configurations.

Figure 13a is a schematic cross-section of a liquid heating appliance with a spill-inhibiting safety feature in another embodiment of the invention.

Figure 1 3b is a perspective cut-away view of the pouring aperture of the embodiment of Figure 13a.

Figure 13c and 13d are schematic cross-sections of the valve arrangement of the embodiment of Figure 13a, respectively in rest and pouring configurations.

Figures 13e to 13g are schematic cross-sections of an alternative valve arrangement of the embodiment of Figure 13a, respectively in rest position, pouring position and tilted to one side, viewed from the rear of the appliance.

Figure 14a is a schematic diagram of a liquid vessel with a single strip capacitance level sensor.

Figure 1 4b is a graph showing the capacitance of the double strip capacitance sensor with fill level.

Figure iSa is a schematic diagram of a liquid vessel with a double strip capacitance level sensor.

Figure 1 Sb is a graph showing the capacitance of the double strip capacitance sensor with fill level.

Figure 15c is a schematic diagram showing the effect of tilt on the double strip capacitance level sensor.

Figure 15d is a graph showing the effect of tilt on the capacitance of single strip and double strip capacitance level sensors.

Figure 16 is a circuit diagram of a circuit for generating a frequency as a function of the capacitance of the level sensor.

Figure 17 is a circuit diagram of a circuit for detecting electronically whether the capacitance of the level sensor is above a first or a second threshold.

Detailed Description of the Embodiments

[0029] In the following description, functionally similar parts carry the same reference numerals between different embodiments. The drawings are intended to be schematic, and dimensions and angles may not be determined accurately from them.

Cordless Electrical Appliance with Optical Coupling [0030] Figure 1 shows schematically a jug kettle with an electronic control, as an example of an appliance to which embodiments of the invention may be applied. In this example, the kettle is a cordless kettle comprising a vessel body 1 and a power base 2 having respective body and base cordless connectors 3 and 4, such as 360° cordless connectors of the type described in patent publication WO-A-94/06185 and/or as sold by Otter Controls Ltd. under the CS4/CS7 (power base socket) and CP7 or CP8 (appliance plug) references. The power base is connectable by a power cord 13 to an electrical power outlet (not shown).

[0031] The vessel body 1 comprises a reservoir 5 for containing water to be heated, and a base section 6 having a sub-base 19, which forms the bottom surface of the vessel body 1.

The vessel body 1 is formed as a jug kettle and therefore has a spout 7, a lid 8 and a handle 9. Water is heated by an element plate 12 forming the base of the reservoir 5, and including a heating element on the underside (i.e. facing towards the base section 6), connected to receive electrical power from the body cordless connector 3. The element plate 12 may be fitted into the vessel body using the Easifix (RTM) fitting as described in WO-A-99/17645.

The element may comprise a sheathed element and/or a thick film element. Preferably, the element plate is composed of stainless steel. Most preferably, the element plate is substantially as described in WO-A-06/83 162. However, at least some embodiments of the present invention are applicable to a liquid heating vessels having an immersed heating element, rather than an element plate.

[0032] A sensor 14 is arranged to sense the state of water in the reservoir 5. The sensor 14 is connected to an appliance control 15 which communicates with a base control 10 by means of an optical signal which is conveyed (as shown by a dashed line) through the cordless connectors 3 and 4. A user interface 11 allows the user to operate the vessel, and may provide a display of the operational state of the vessel. The user interface may be provided in the vessel body 1 and/or in the power base 2.

[0033] The operational state of the vessel is controlled in response to the sensor 14 and the user interface 11, by means of communication between the appliance control 15 and the base control 10. One example will now be described with reference with Figure 2.

[0034] The optical communication link between the vessel body 1 and the base 2 comprises an optical emitter and/or detector 31 in the base 2, which communicate respectively with an optical emitter and/or detector 31 in the vessel body 1, by means of an optically transmissive seal 21 which allows 360° of relative rotation between the base 2 and the body 1.

[0035] A power control 18 is provided in the vessel body 1 and is arranged to switch the supply of electrical power to the element plate 12, under the control of the vessel control 15.

A vessel PSU (power supply unit) 17 provides a low voltage power supply to the vessel control 15, which may be a microcontroller. A base PSU 16 provides a low voltage power supply to the base control 10, which may be a microcontroller.

[0036] The user interface 11 may be divided between the base 2 and the vessel body 1 as follows. The base 2 includes LED status indicators 1 la, user input means 1 lb (such as push buttons or switches) and/or audible output means 11 c, such as a piezoelectric sounder. The vessel body 1 may include lighting means 11 d arranged to illuminate a part of the vessel body 1 and/or the contents of the reservoir 5, so as to indicate the state of the vessel and/or to provide an aesthetic effect.

[0037] Hence, in this embodiment it is necessary for the base control 10 to communicate with the vessel control 15, for example to switch the power to the element plate 12 in response to a user input at the user input means 1 lb. This communication is provided by means of the optical communications link.

[0038] In other embodiments, the power control 18 may be provided in the base 2, so that it is necessary for the vessel control 15 to communicate with the base control 10 in order to switch power in response to an input from the sensor 14. In this embodiment, the optical communication may be unidirectional from the body 1 to the base 2, which is advantageous in that the optical communications link is simplified. However, the optical communication between the vessel body 1 and the base 2 may be unidirectional or bi-directional, depending on what information needs to be communicated. The same optical communications link may be used to support multiple functions between the power base 2 and the vessel body 1.

[0039] In an alternative embodiment, the vessel control 15 may simply communicate the output of the sensor 14 optically to the base control 10. In yet another embodiment, the vessel control 15 may be dispensed with altogether, and the sensor 14 may provide a direct optical output. For example, the sensor 14 may be arranged to detect light reflected off or passing through the surface of liquid in the reservoir 5, as described for example in WO-A- 2009/060 192. Light may also be conveyed to the surface of the liquid through the optical interface between the vessel body 1 and the base 2. In this embodiment, the sensor 14 may simply comprise a light guide, which therefore provides a very simple sensing arrangement within the vessel body 1.

[0040] It will be apparent from the above discussion that control, power switching, user interface and sensing functions may be distributed in many different ways between the body 1 and the base 2, any of which may require unidirectional or bidirectional optical communication between the body 1 and the base 2.

[0041] The vessel may have one or more additional features, such as a keep warm' feature, in which the liquid is maintained around a predetermined temperature, preferably after boiling; this may be done by intermittent activation of the main heating element, or by intermittent or continuous activation of a secondary heating element (not shown). The predetermined temperature may be just below boiling point, or a lower temperature such as 80°C, and may be selectable by the user.

[0042] Another heating feature is a sub-boil feature, in which the liquid is heated up to a predetermined temperature below boiling, such as 80°C for making coffee, and the heating power is then switched off or reduced, for example to activate a keep warm mode. The predetermined temperature may be selectable by the user.

[0043] Another heating feature is a prolonged boil feature, whereby the liquid is heated to boiling and then boiled for at least a predetermined time, such as 30 seconds to 2 minutes, to sterilize the liquid.

Cordless Connectors [0044] The cordless connector 3 of the vessel body 1 will now be described in more detail with reference to Figures 3a, 3b and 5. The cordless connector 3 is attachable to the sub-base 19 by attachment means such as bosses 3a. A seal 21 is provided around the circumference of the connector 3 for sealing against the sub-base 19 to prevent liquid entering the base portion 6. The seal 21 preferably comprises a main body 22 that fits against the outer side wall of the connector 3, and one or more circumferential protrusions or fins 23 extending between the connector 3 and the sub-base 19. As shown in Figure 5, the fins 23 deform against a side wall of the sub-base 19 and thereby seal the gap between the connector 3 and the sub-base 19, which gap may be variable in size depending on the tolerances and/or thermal expansion of the components.

[0045] At least the main body 22 of the seal 21 comprises a material that is both resilient and optically transmissive, such as a translucent silicone material. One possible material is disclosed in JP-A-2008291 124, in the context of a light conductive plate for illuminating the keypad of a mobile phone. The fins 23 need not be optically transmissive and may be made of a different material selected for resilience, for example.

[0046] The seal 21 may be a preformed seal that is assembled onto the connector 3, alternatively, the seal may be formed in the gap between the connector 3 and the sub-base 19, for example using a liquid sealant that sets within the gap. Alternatively, the seal 21 could be formed as part of the sidewall of the connector 3, such as a twin-shot seal.

[0047] The main moulding of the connector 3 includes one or more light emitter/receiver housings 32, each of which may hold a respective light emitting and/or receiving device 31, such as an LED or a photosensor. The wavelength of light that is transmitted and received may be in the visible range, or infrared for example. The wires of the or each device 31 are preferably held in place by wire supports 34 forming part of the main moulding. The wires are connected to the vessel controller 15.

[0048] As best shown in Figure 3b, the cordless connector 3 also includes live, neutral and earth terminals for connection to the element power control 18 and/or directly to the heating element.

[0049] The cordless connector 3 may be provided as a discrete component together with the seal 21 and optionally with the device(s) 31, for assembly into any suitable form of sub-base 19.

[0050] The cordless connector 4 of the power base 2 will now be described in more detail with reference to Figures 4a, 4b and 5. The cordless connector 4 includes an outer moulding 53 that fits within the cordless connector 3 of the vessel body 1. The live and neutral terminals of the cordless connector 4 are protected by a shutter seal 54 that is displaced by the cordless connector 3.

[0051] The cordless connector 4 includes an annular light transmitter 41 that is fitted onto an outer moulding 53, for example by means of corresponding click or bayonet fittings 43, 56. The annular light transmitter 41 is made from optically transparent or translucent material. Light emitting and/or receiving optical devices 31 are received in pockets or housings 42 in the annular light transmitter 41, to ensure good optical coupling between the devices 31 and the annular light transmitter 41. The housings 42 extend through apertures in the outer moulding 53 and the devices 31 are held in place against housing abutments 57 in the outer moulding 53 when the light transmitter 41 is fitted onto the outer moulding 53. A seal 44 is also held between the annular light transmitter 41 and the outer moulding 53, to prevent liquid ingress to the devices 31. The seal 44 in this case is not arranged to conduct light between the devices 31 and the light transmitter 41.

[0052] In an alternative embodiment, the annular light transmitter 41 may be integrated with the outer moulding 53, for example by means of a twin shot process, or the outer moulding may be substantially or entirely composed of optically transmissive material.

[0053] When the cordless connectors 3 and 4 are connected together as shown in Figure 5, light is conducted between the devices 31 of the power base 2 and of the vessel body 1 through the seal 21 and the annular light transmitter 41, regardless of the relative rotation of the cordless connectors 3 and 4. Precise alignment is not required between the optical devices 31 of the power base 2 and of the vessel body 1, because the seal 21 and/or the annular light transmitter 41 act as light guides or diffusers.

[0054] In order to provide a 360° optical coupling, it is not essential that both the optical connections on the power base 2 and the vessel body 1 subtend 360°; only one or neither of the connections may do so, provided that there is always some optical coupling between them, for example as a result of overlap between them. For example, in an alternative embodiment, each of the emitters acting through the seal 21 in the appliance may have an effective range or spread of 120° in which case the sensor 31 in the base 2 can be positioned at any point beneath the seal 21, and there would be no need for an annular light transmitter 41 in the base 2.

[0055] Figure 6 shows a variant of the cordless connector 3 of the vessel body 1, in which the seal 21 includes a pocket 24 into which the optical device 31 fits, so as to improve the optical coupling between the device 31 and the seal 21.

[0056] Figure 7 shows another variant of the cordless connector 3 of the vessel body 1, in which an annular light transmitter 46 is disposed between the optical device 31 and the main body 22 of the seal 21, so as to improve the optical coupling between the device 31 and the main body 22 of the seal 21. The annular light transmitter 46 has a housing 45 into which the optical device 31 fits, so as to improve the optical coupling between the device 31 and the annular light transmitter 46.

[0057] In each embodiment, the optical device(s) 31 and any housing 45 or pocket 24 therefor may be arranged at an angle to the annular light transmitter 41, 46 or the seal 21 respectively, to improve the optical coupling thereto, or to enhance the light guiding effect of the annular light transmitter 41, 46 or the seal 21 Alternative Embodiments [0058] In the above embodiments, the cordless connectors 3 and 4 could be reversed, so as to be provided respectively in the power base 2 and the vessel body 1. Alternatively, the power base 2 and the vessel body 1 may both have cordless connectors in which a seal is used to provide an optical coupling.

[0059] In an alternative embodiment, a seal other than that around the cordless connector may be used to provide an optical coupling between the power base 2 and the vessel body 1: for example, a seal between the sub-base 19 and the side wall of the vessel 1.

[0060] Some of the light generated by the optical device(s) 31 may be diffused in such a way as to be visible to the user when the vessel 1 is connected to the power base 2, for example to indicate to the user that optical communication is taking place, or for aesthetic effect.

Spill-inhibiting Safety Features [0061] Figures 8a to 8e illustrate a spill-inhibiting safety feature in an embodiment of the invention, in a cordless electric kettle. However, the safety feature is applicable to other liquid heating appliances.

[0062] As shown in Figure 8a, the lid 8 comprises a lid chamber 71, the floor of which comprises a lower lid surface 66 that is removably sealed against the upper end of the reservoir 5 by a reservoir seal 63. The lid 8 including the lid chamber 71 can be removed from the reservoir 5, to allow filling or cleaning of the reservoir 5.

[0063] The lid chamber 71 acts as a passage for liquid from the reservoir 5, which enters the lid chamber 71 through an aperture 86 in the lower lid surface 66. Liquid may then be poured out from the lid chamber 71 through the spout 7. Optionally, a spout filter 65 is arranged between the lid chamber 71 and the spout 7.

[0064] The lid chamber 71 also acts as a passage for steam from the reservoir 5. When liquid boils in the reservoir 5, steam passes through the aperture 86 into the lid chamber 71.

Some of the steam then passes through a steam tube 70 from the lid chamber 71 to a steam-sensitive control 60 arranged to switch off or reduce heating when steam is detected. In this case, the control 60 is an integrated cordless connector and control. The steam sensitive control 60 may include a thermally sensitive actuator, such as a snap-acting bimetallic actuator, onto which steam is directed from the steam tube 70 when the liquid in the reservoir 5 boils. The outer surface of the steam tube 70 is removably sealed against the lower lid surface 66 by a seal 67.

[0065] Alternatively, the steam-sensitive control 60 may be mounted in or adjacent to the lid chamber 71, in which case no steam tube 70 is necessary, but a connection of some type then needs to be made from the control 60 to the heater.

[0066] In this specific embodiment, the vessel body 1 has an outer wall 61 spaced apart from an inner wall 62, the latter forming the wall of the reservoir 5. The steam tube 70 passes through the space between the inner wall 62 and the outer wall 61, for example as described and claimed in the applicant's granted patents GB-B-2365752 and CN-C-1239 116.

[0067] The flow of liquid and steam through the aperture 86 is governed by flow management means 80, embodiments of which are described in detail below. The flow management means 80 allows steam to escape from the reservoir 5, but prevents liquid from escaping from the reservoir 5 when the vessel body 1 is tipped over. In at least some embodiments, the flow management means 80 allows liquid to escape from the reservoir 5 when actuated by a user-operable actuator 75 that is normally biased away from the flow management means 80. The user-operable actuator 75 may be a spring-biased pusher rod slidably mounted in the handle 9, and projecting beyond the handle 9 to present a portion for pushing by the user so as to engage the flow management means 80. Alternatively, the user actuable portion of the actuator 75 may be arranged to be pulled so that another part of the actuator 75 engages the flow management means. The user-actuable portion may be connected to the engaging portion by one or more gears. The user-actuable portion may comprise a trigger.

[0068] A first embodiment of the flow management means 80 is illustrated in Figures 8b-8e.

Figures 8b-8e also show the sealing arrangement between the outer wall 61 and inner wall 62 by means of seal 64 and between lower lid surface 66 and inner wall 62 by seal 63.

[0069] At the upper side of the aperture 86 is located an upper lid sealing face 82, forming a valve seat in which sits an upper part 89 of a valve member 81, having an upper valve sealing face 83 which seals against the upper lid sealing face 82. Both the upper lid sealing face 82 and the upper valve sealing face 83 are upwardly diverging frustums, and preferably conical frustums so that the valve member 81 may be positioned in the aperture 86 with any azimuthal orientation; other shapes such as pyramidal frustums may be used, however. The lower lid sealing face 82 diverges upwardly at a greater angle than the upper valve sealing face 83, so that in the rest position of Figure 8b, with the lower lid surface 66 horizontal, the upper lid sealing face 82 seals against the upper valve sealing face 83 only at the lower ends thereof.

[0070] In the rest position of Figure 8b, the aperture 86 is substantially closed, to prevent thermal losses through the aperture 86. Optionally, one or more ventilation apertures 87 may be located between the upper lid sealing face 82 and the floor 66, to allow pressure equalization between the reservoir 5 and the lid chamber 71.

[0071] The valve member 81 has a lower part 90 that extends below the aperture 86 and has an upwardly facing lower valve sealing face 85 for sealing against a lower lid sealing face 84, as will be described below. The lower part 90 in this embodiment has the form of an inverted shallow cup or dome.

[0072] In the boiling position of Figure 8c, liquid steam pressure in the reservoir 5 lifts the valve member 81 so that upper valve sealing face 83 moves apart from upper lid sealing face 82 and allows steam to escape into the lid chamber 71 and thence through the spout 7 or steam tube 70. The steam pressure is insufficient to bring the lower valve sealing face 85 into contact with the lower lid sealing face 84.

[0073] In the pouring position of Figure 8d, the upper valve part 89 tends to pivot about a contact point A on the upper lid sealing face 82. However, the user actuates the actuator 75 so as to limit to movement of the upper valve part 89 so that the upper and lower valve sealing faces 83, 85 seal against the respective upper and lower lid sealing faces 82, 84 at one side only, leaving a crescent-shaped passage for the liquid to pass the valve member 81 at the other side.

[0074] If the vessel body 1 is tipped without the actuator 75 being actuated, as shown in Figure 8e, the valve member 81 rotates so that the upper valve sealing face 83 lies flat against the upper lid sealing face 82, on the side towards which the vessel body 1 is tipped.

This brings the lower valve sealing face 85 completely into contact with the lower lid sealing face 84, thus sealing the aperture 86 and preventing spillage of liquid therethrough.

In other words, the valve member 81 acts as an overcentre mechanism that closes the valve if tipped.

[0075] The lower valve part 90, though wider than the aperture 86, may be sufficiently flexible to be forced through the aperture 86 if steam pressure builds up sufficiently, thus releasing the pressure. In this way, the valve member 81 acts as a safety valve. However, as an alternative or additional feature, a separate pressure relief valve may be provided in the lower lid surface 66, for relieving excess pressure in the reservoir 5 into the lid chamber 71.

In either case, it would be advantageous to provide some means for directing steam and/or liquid exhausted through the pressure relief valve away from the spout 7, for example by means of a baffle or shroud. This means may form part of the valve member 81, and may be enabled by the shape of the lower valve part 90 and/or the aperture 86.

[0076] The ability to pass the lower valve part 90 through the aperture 86 also allows easy fitting and replacement of the valve member 81. Alternatively, the upper and lower valve parts 89, 90 may be fitted or clicked together from either side of the aperture 86 to facilitate assembly.

[0077] In the specific embodiment, the aperture 86 is positioned towards the spout 7, while the steam tube 70 is positioned away from the spout 7 and opens towards the upper part of the lid chamber 71, as described and claimed in the applicant's granted patent GB-B- 2332095. As a result, any water leaking through the aperture 86 will tend not to enter the steam tube 70 if the vessel body 1 is knocked over and lies on one side, resting on the handle 9 or spout 7.

[0078] An alternative embodiment of the flow management means 80 is shown in Figures 9a to 9c. In this embodiment, the upper valve part 89 is connected through the aperture 86 to the lower valve part 90 by a pivoting joint 88, which is preferably a universal joint enabling the upper valve part 89 to pivot about any horizontal axis. The lower valve part 89 is constrained to move perpendicularly to the lower lid surface 66 by guides 91.

[0079] In the boiling position as shown in Figure 9a, as in the embodiment of Figure 8c, upper valve sealing face 83 moves apart from upper lid sealing face 82 and allows steam to escape into the lid chamber 71.

[0080] In the pouring position of Figure 9b, the upper valve part 89 pivots about a contact point B on the upper lid sealing face 82, on a side opposite to the actuator 75. However, the actuator 75 limits the extent to which the upper valve part 89 can rise up and thereby lift the lower valve part 90, so that liquid is able to flow around the lower valve part 90 and the upper valve part 89, through the aperture 86.

[0081] In the tipped position of Figure 9c, the upper valve part 89 is not constrained by the actuator 75, which is not actuated and is biased away from the valve member 91. The upper valve part 89 is able to pivot further about the contact point B, thereby lifting the lower valve part 90 so that the lower valve sealing face 85 seals against the lower lid sealing face 84 and closes the aperture 86, thus preventing leakage of liquid.

[0082] Another alternative embodiment of the flow management means 80 is shown in Figures lOa to lOc, which show respectively the boiling, pouring and tipped positions. In this embodiment, the upper valve part 89 and lower valve part 90 are spherical, but the valve member 91 functions similarly to that of the embodiment of Figures 8a to 8e. The upper and lower valve parts 89 and 90 may be joined by a universal joint as illustrated in the embodiment of Figures 9a to 9c.

[0083] Figure ha shows an alternative embodiment in which the lid chamber 71 may be separated into a front chamber 94 and a back chamber 95, as shown in more detail in Figure 1 ib, and/or may include a venting arrangement as shown in Figures 1 ic and lid, or Figures lie and 1 if, or Figures 1 ig and 1 ih, or Figures iii, 1 ij and ilk, or Figures ill and 1 im.

[0084] As shown in more detail in Figure 1 ib, the front chamber 94 includes the aperture 86 which in this embodiment is used for dispensing liquid from the reservoir 5. Steam and/or air are vented through a steam vent 92 in the lower lid surface 66, into the back chamber 95.

The front chamber 94 is thermally insulated from the back chamber 95 by a moveable flap that is normally closed, but opens under sufficient pressure from steam in the back chamber 95, to release the steam pressure into the front chamber 94 and through the spout 7.

[0085] The aperture 86 is normally closed by the actuator 75, which in this embodiment is biased towards the spout 7. When a trigger 99 is pulled by the user, the actuator 75 is pulled back towards the handle 9 and opens the aperture 86 to allow pouring through the spout 7.

The actuator 75 may be slidably mounted in the lid chamber 71, for example by means of one or more slots in the lower lid surface 66, so as to make a seal against the lower lid surface. If the vessel body 1 is tipped over, liquid is substantially prevented from leaking through the aperture 86 by the sealing of the actuator 75 against the lower lid surface 66.

[0086] In the venting arrangement of Figures ii c and lid, the steam vent 92 is always open, even when the actuator 75 is pulled back. Hence, the steam vent 92 allows air to enter the reservoir 5 as liquid is poured out, thereby equalising the pressure within the reservoir 5.

If the vessel body 1 is tipped over, liquid may leak from the reservoir 5 into the back chamber 95 but may be partially retained within the back chamber 95. If liquid enters the steam tube 70, it can be drained away from a steam sensor by the use of a steam chamber as disclosed for example in the applicant's granted UK patent GB-B-23 18452 and its Chinese equivalent CN-C-i 149046.

[0087] In the alternative venting arrangement of Figures lie and ii f, the steam vent 92 has an aperture seal 96, for example comprising silicone flaps, that opens under steam pressure from within the reservoir 5 and seals when the steam pressure is reduced. When the vessel body 1 is tipped over, the aperture seal 96 inhibits leakage of liquid through the steam vent 92. The aperture seal 96 will also open inwardly to equalise pressure as the interior of the reservoir 5 cools, and may allow pressure equalisation during pouring.

[0088] In the further alternative venting arrangement of Figure ii g and ii h, the steam vent 92 has an aperture flap 97 that opens under steam pressure from within the reservoir 5 and seals when the steam pressure is reduced. The aperture flap 97 allows pressure equalisation during cooling of the reservoir 5 and pouring, but may only be partially effective in preventing liquid leakage when the vessel body 1 is tipped over.

[0089] In the further alternative venting arrangement of Figures lii to ilk, the steam vent 92 is closed by a valve arrangement in a similar manner to the embodiment of Figures 1 Oa to lOc. The actuator 75, in the pulled back position of Figure llj, prevents the valve member 81 from rising up, and therefore prevents the lower valve part 90 from sealing completely against the lower lid sealing face 84. Alternatively, a valve arrangement as disclosed in Figures 9a to 9c or 8b to 8e may be used.

[0090] In a further alternative venting arrangement shown in Figures 111 and 11 m, a conical valve member 98 is seated against a lower lid sealing face 84 when the vessel body 1 is horizontal. Steam pressure forces the valve member 98 upwardly so as to release steam pressure through the steam vent 92. When the vessel body is tipped, as shown in Figure 1 im, the upper face of the valve member 98 seals against the steam vent 92 and thereby prevents liquid leakage. One or more small, permanently open vents may be provided around the steam vent 92, to allow a degree of permanent venting.

[0091] Figures 12a to 12d show a further embodiment of the invention, in which a steam path is integrated within a hollow moulding 100 of the actuator 75. The steam tube 70 is in communication with the hollow interior of the moulding 100, with a cap 101 also forming part of the moulding 100. The moulding 100 includes one or more vents 102 at an end towards the handle 9.

[0092] In the rest position of the actuator 75, the aperture 86 is connected to the hollow interior 100, so that steam escaping from the aperture 86 passes into the steam tube 70 or through the vents 102. If the vessel body 1 is tipped over, liquid will flow through the vents 102 into the lid chamber 71 and may escape through the spout 7. However, if the vessel body 1 lies on its side, then either the vents 102 or the spout 7 are raised above the plane of symmetry of the vessel body 1, thereby restricting the volume of leakage.

[0093] When the user actuates the actuator 75 by pulling the trigger 99, the aperture 86 is opened to the lid chamber 71, allowing liquid to be poured out through the spout 7.

[0094] Figures 13a to 13d show a further embodiment of the invention, in which the aperture 86 acts as an outlet for both water and steam, and includes a valve arrangement similar to that of Figures 111 and lim. In this embodiment, no user actuation is required to allow pouring. Instead, the valve seat includes an inwardly projecting portion 103 located towards the spout side of a lower lid valve wall 104, which prevents the conical valve member 98 from sliding upwards and closing the aperture 86 when the vessel body 1 is tipped forwards for pouring. However, if the vessel body 1 is tipped forward suddenly, the valve member 98 will jump past the projecting portion 103 and seal against the upper lid sealing face 82. If the vessel body 1 is tipped sideways or backwards, the valve member 98 will not be engaged by the projecting portion 103 but will seal against the upper lid sealing face 82, thereby closing the aperture 86. At the upper end of the lower lid valve wall 104 are provided one or more venting slots 87, which allow venting of the reservoir 5 when the valve member 98 is in its rest position, towards the bottom of the lower lid valve wall 104.

For improved thermal insulation, the spout 7 may include a spout flap (not shown) that opens when the vessel body 1 is tipped forward for pouring.

[0095] Figures 13e to 13g show an alternative embodiment of the valve arrangement, in which the inwardly projecting portion is located towards the lower end of the wall 104, and engages with a circumferential groove 105 towards the lower end of the valve member 98.

Capacitative Level Sensing [0096] Figures 14a, 14b and 15a-15d illustrate a capacitative level sensors for the reservoir of a liquid vessel 1; this may be a liquid heating vessel, but the application of this embodiment is not restricted to liquid heating vessels.

[0097] In the example of Figures 14a and 14b, a single electrically conductive strip 110 is positioned outside the wall of the reservoir, and an electrical connection is made through the electrically conductive element plate 12 at the bottom of the reservoir 5 to the liquid in the reservoir 5, which liquid is itself electrically conductive. The electrically insulating wall of the reservoir 5 then acts as the dielectric in a capacitor in the overlap area between the liquid and the electrically conductive strip.

[0098] However, as shown in Figure 14b, the capacitance of this capacitor varies by as much as 40% when the vessel body 1 is tilted up to 20° forward and backward i.e. away from and towards the strip 110. A tilt of 20° is normal during filling of the vessel, but it is at this time that an indication of fill volume is most needed. Hence, the arrangement with a single strip 110 is not suitable for capacitative detection of fill volume in these circumstances.

[0099] In the embodiment of Figures 15a-15d, the effects of tilt are substantially avoided by having a plurality of conductive strips mutually spaced apart, and measuring the capacitance between conductive strips rather than between the conductive strip 110 and the element plate 12.

[00100] First and second electrically conductive strips 1 lOa, 1 lOb are positioned at opposite sides of the reservoir 5, on the outside of the wall of the reservoir 5. The vessel body 1 advantageously have a double walled construction as in the embodiment of Figure 8a or 11 a, in which case the conductive strips 11 Oa, 11 Ob are located on the outside of the inner wall 62 and are protected and/or obscured by the outer wall 61. The use of capacitative level sensing is particularly advantageous for double-walled vessels, since otherwise a water window might be needed to view the level within the reservoir 5, which reduces the advantage of thermal insulation of the double walled construction.

[00101] The capacitance is measured between the conductive strips llOa, liOb. The walls of the reservoir 5 are electrically insulating and act as a dielectric, while the liquid within the reservoir 5 acts as an electrical conductor between the walls of the reservoir 5.

Hence, the capacitance between the first and second conductive strips 11 Oa, 11 Ob is that of two capacitances in series: CTotal = (Ci X C2)/(C1 + C2) (1) where C1, C2 are the capacitances between the first and second conductive strips 1 lOa, 1 lOb respectively and the liquid in the reservoir 5, through the dielectric wall.

[00102] The capacitances Ci, C2 depend on the liquid level adjacent the corresponding conductive strips llOa, liOb, as follows: C = ErC0A/d (2) where Cr is the permittivity of free space ( 8.85 x 1012 Fm') Co is the relative permittivity of the reservoir wall (typically 2.25) d is the thickness of the reservoir wall (typically 2.6 mm) A is the area of overlap between the conductive strip llOa, liOb and the liquid adjacent the conductive strip 11 Oa, 11 Ob within the reservoir 5.

[00103] The variation of capacitance with fill level of a cylindrical reservoir 5 in an example is shown in Figure 15b, in which the reservoir 5 is kept upright. The capacitance increases linearly with fill level, and is proportional to A. [00104] When the vessel body 1 is tilted, as shown in Figure 15c, the water level increases at one conductive strip 11 Oa, and decreases at the other conductive strip 11 Ob. The changes in capacitance at each strip llOa, liOb do not cancel out, because the total capacitance is not the sum of the individual capacitances, as shown in equation 1 above.

However, as shown in the example of Figure 15d, the variation of the capacitance due to tilting up to 18° either forwards or backwards is less than 5%, compared to a 40% variation in the case of a single conductive strip.

[00105] During filling, the liquid in the reservoir 5 may be turbulent, which can cause further uncertainty in the detected fill level. However, by using two or more conductive strips llOa ilOb at different locations, the variations in fill level caused by turbulence are averaged out.

[00106] The detected capacitance may be used to indicate a fill level, either to a control within the vessel body 1 or to a user. The indication may represent a substantially continuously variable fill level, or merely that the fill level has exceeded one or more thresholds.

[00107] A simple oscillator circuit for indicating the fill level as a frequency signal is shown in Figure 16, in which the capacitance C is the total capacitance CTotal of the conductive strips llOa, liOb as given by equation 1 above. The frequency fofthe frequency signal is given by f= 1/(RC) (3) where R is the (constant) resistance of the resistor in the oscillator circuit.

The frequency f is inversely proportional to the capacitance C (CTotal), from which the fill level can be calculated.

[00108] The frequency signal may be output to a microcontroller or dedicated circuit which calculates and displays or otherwise indicates the fill level, for example as a digital display of the number of cups or volume. Alternatively, the frequency signal f may be amplified and output directly to a speaker, so that the user can judge the fill level from the pitch of the sound.

[00109] Figure 17 shows an alternative circuit in which the capacitance is measured by one or more threshold detectors Dl, D2, providing respective outputs to a microcontroller MC which generates an indication (such as a sound and/or light effect) of the thresholds being exceeded; for example, a low beep or when crossing a low fill level threshold, and a high beep when crossing a high fill level threshold. This arrangement is particularly advantageous when filling a kettle, as the user does not need to watch the level of liquid in the reservoir 5, but simply fills until the relevant indication is given.

[00110] Preferably, the vessel body includes a power supply such as a battery or capacitor, for powering the level sensing circuitry while the vessel body 1 is separated from the base 2 for filling.

Alternative Embodiments [00111] The embodiments described above are illustrative of rather than limiting to the present invention. Alternative embodiments apparent on reading the above description may nevertheless fall within the scope of the invention.

Claims

Claims 1. A liquid heating vessel having a valve through which liquid can be dispensed, the valve being arranged to open under steam pressure within the vessel, and being arranged to close when the vessel is tipped over.
2. The vessel of claim 1, wherein the valve includes an overcentre mechanism responsive to tipping of the vessel.
3. The vessel of any preceding claim, wherein the valve is arranged to be normally closed when the vessel is in an upright orientation.
4. The vessel of claim 3, wherein the valve has first sealing faces that close when the vessel is in an upright orientation, and second sealing faces that close when the vessel is tipped.
5. The vessel of any preceding claim, including a user-actuable mechanism that, when actuated, prevents the valve from closing when the vessel is tipped, to allow dispensing of liquid through the valve.
6. The vessel of any preceding claim, wherein the valve is arranged to remain open when the vessel is tipped in a predetermined orientation.
7. A liquid heating vessel having an outlet for dispensing liquid from the vessel, and a user actuated mechanism arranged to open the dispensing outlet for dispensing when actuated, the user-actuated mechanism being biased to a closed position so that liquid cannot be dispensed through the dispensing outlet, the vessel including a steam passage for conveying steam indirectly from the vessel.
8. The vessel of claim 7, wherein in the closed position the dispensing outlet is open to the steam passage.
9. The vessel of claim 7 or 8, wherein the steam passage opens towards an opposite side of the vessel from the dispensing outlet.
10. The vessel of claim 7, wherein the steam passage is separate from the dispensing outlet.
11. The vessel of claim 10, wherein the steam passage includes a valve that opens under steam pressure.
12. The vessel of claim 11, wherein the valve is arranged to close when the vessel is tipped.
13. A liquid vessel having a liquid reservoir and a capacitative liquid level sensor for sensing the liquid level within the reservoir, the sensor comprising a plurality of capacitor plates each extending in a vertical direction of the reservoir and making a capacitative coupling with liquid within the reservoir through a portion of the wall of the reservoir, the capacitor plates being mutually spaced apart around the circumference of the reservoir such that the combined capacitance measured through the capacitor plates is representative of the level or volume of liquid within the reservoir, substantially independently of the angle of tipping of the reservoir.
14. The vessel of claim 13, wherein the vessel has an outer wall outside the wall of the reservoir.
15. The vessel of claim 13 or 14, whereinthe vessel includes means for indicating the level or volume of liquid within the reservoir in response to the liquid level sensor.
16. The vessel of claim 15, wherein the means for indicating is substantially continuously variable.
17. The vessel of claim 15, wherein the means for indicating is responsive to one or more liquid level thresholds being exceeded.
18. A cordless electrical appliance comprising an appliance proper and a power base, the appliance having a component sealed therein by means of a seal arranged to provide an optical coupling between the appliance proper and the power base.
19. The appliance of claim 18, wherein the component comprises a cordless electrical connector.
20. The appliance of claim 19, wherein the seal is concentric with the cordless electrical connector.
21. The appliance of claim 19 or 20, wherein the cordless electrical connector is a 360° cordless connector.
22. The appliance of claim 21, wherein the optical coupling is a 360° optical coupling.
23. The appliance of any one of claims 18 to 22, wherein the component is sealed within the appliance proper.
24. The appliance of any one of claims 18 to 23, including an optical device optically coupled to the seal.
25. The appliance of claim 24, wherein the optical device is located within the seal.
26. The appliance of any one of claims 18 to 25, including a light guide optically coupled with the seal.
27. The appliance of any one of claims 18 to 26, wherein the appliance proper includes an optical transmitter arranged to communicate through the seal to an optical receiver in the power base.
28. The appliance of claim 27, wherein the optical transmitter is arranged to communicate a sensed property of the appliance proper to the optical receiver.
29. The appliance of claim 28, wherein the power base is arranged to switch power to the appliance proper in response to said sensed property.
30. An electrical component having a seal for sealing the component within an appliance and/or power base, and optical communication means for optical communication through the seal.
31. The component of claim 30, comprising a cordless electrical connector.
32. A cordless electrical appliance substantially as herein described with reference to and/or as shown in the accompanying drawings.
33. A cordless electrical connector, seal and optical communication means substantially as herein described with reference to and/or as shown in the accompanying drawings.