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Patent Searching and Data

Document Type and Number:
WIPO Patent Application WO/1983/000548
Kind Code:
Known beverage warmers are automatically energized by the weight of a container with liquid in it when supported on an electrically heated surface and are deenergized by a heat sensitive element.The present beverage warmer selectively warms a beverage when a beverage container is positioned on a support surface in a particular orientation. In a preferred form, the present beverage warmer for selectively energizing and warming comprises a support 19 (43) of non-magnetic material providing an upwardly facing heating surface 21 (49), an electrical heating element 22 (45) disposed to heat the surface, an energizing electric circuit for the heating element including a normally open magnetic switch 26 (46) mounted in a predetermined location on the support below the surface, and a separate beverage container 12 (51) adapted to rest on the surface of the support being essentially of non-magnetic material and having a permanent magnet 44 (54) fixed to a lower portion thereof whereby to cause the magnetic switch to close and the electrical heating element to energize only when the container is oriented to dispose the magnet effectively adjacent the magnetic switch.

Application Number:
Publication Date:
February 17, 1983
Filing Date:
July 28, 1982
Export Citation:
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International Classes:
A47J31/50; A47J36/24; A47J39/02; H05B3/74; (IPC1-7): F27D11/00
Foreign References:
Other References:
See also references of EP 0084061A4
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1. A beverage warmer assembly comprising means providing an electrically heated surface, an energizing electrical circuit for said means having a magnetically operable normally open switch mounted adjacent said surface in a predetermined location, and a beverage container adapted to be mounted on said surface, said container having thereon a magnet, and said switch being closed to activate said circuit only when said container has such orientation on said surface that the switch is within range of the magnetic field of said magnet.
2. A beverage warmer assembly comprising a support providing an upwardly facing heating surface, an electrical element disposed to heat said surface, an energizing circuit for said element including a normally open magnetic switch mounted in a predetermined location on said support below said surface, and a beverage container adapted to rest on said surface, said container having a permanent magnet fixed in a lower portion t_ ereof whereby to cause said switch to close only when the container Is oriented to dispose the magnet effectively adjacent said switch.
3. In the assembly defined in claim 2, said support comprising a base mounting a horizontal plate member of nonmagnetic material having an upper planar face serving as said heating surface, and means whereby said electrical element is secured upon or adjacent the bottom of said member, said magnetic switch comprising a magnetic reed type switch mounted on the base below said member.
4. In the assembly defined in claim 3, said switch being located substantially centrally of said member.
5. In the assembly defined in claim 3, said switch being located outwardly from the central portion of said member.
6. In the assembly defined in claim 3, said circuit including an indicator lamp mounted at the side of said base adapted to be energized when said switch is closed.
7. In the assembly defined in claim 3, visible Index means on the upper part of said support facilitating operative orientation of said container.
8. In the assembly defined in claim 2, said container being a cup having a flat bottom rim slidable on said surface and said magnet being fixed on the container bottom in offset relation to the central axis of said cup.
9. A heater unit for a beverage warmer comprising a base on which is mounted a generally flat horizontal beverage cup support nonmagnetic plate providing a planar heating surface, and an electrical heating element fixed below said plate and having an energizing circuit mounted on said base, said circuit including a magnetically operable switch that is located within the base below said plate.
10. The heater unit defined in claim 9 wherein said switch is mounted substantially centrally of said base.
11. The heater unit defined in claim 9 wherein said plate is of aluminum, aluminum alloy or nonmagnetic stainless steel.
12. The heater unit defined in claim 9 wherein said plate is ceramic. OMPI . YIPO ¬ ls.
13. A beverage container composed mainly of nonmagnetic material and having fixed thereon a permanent magnet that is offset with respect to the vertical axis of said container.
14. The beverage container of claim 13, said container being a ceramic, plastic, glass or nonmagnetic metal cup having a permanent magnet imbedded in a bottom surface thereof.
15. The beverage container defined in claim 13, wherein said cup has a side handle and said handle and magnet are substantially aligned with the central portion of said cup. ^3 RE A (7" OMPI V IFO ' .

This invention relates to apparatus for selectively warming a beverage and particularly to apparatus consisting essentially of a supporring heating unit and a separate container unit adapted to be seated on it and having cooperating arrangements whereby only predetermined orientation of the container unit on the heating unit energizes the heating unit. PRIOR ART

It is known to provide beverage warmers wherein the weight of a container with liquid in it automatically energizes an electrically heated surface on which the container is supported, as for example disclosed in the patents to Wagner et al No. 2,660,658 and Barney No. 3,586,824. Electric hot plates are known wherein a heat sensitive element acts to limit energization when a predetermined temperature is attained, as in the patent to Jacobs et al No. 3,052/791.

The patent to Moreland et al No. 3,796,850 discloses a cooking pan and heater arrangement wherein a metal or other magnetic material pan is heated by indirect heating controlled by the presence of the pan on the heater. In this patent the circuit to the induction coils includes a magnetic reed switch having contacts held normally closed by a pair of permanent magnets on the heater and allowed to open to energize the coils when a pan of magnetic material is placed on the heater and shunts the magnetic field. OBJECTS OF THE INVENTION

The invention is specifically concerned with the novel combination of an electrically energized heating unit that provides support for a special coacting beverage container unit, with the heating unit having a circuit containing a normally open control switch which may automatically close only in response to predetermined orientation of the container unit on the heating unit, and this is a major object of the invention.

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A further ob ect of the invention is to provide an electrical heater unit having a container mounting heating surface heated by an electrically energized element in circuit with a normally open magnetic switch mounted in a fixed location on the unit.

Pursuant to the foregoing object the invention further contemplates the heater unit in novel combination with a special container such as a cup for beverage to be warmed seated on the said surface, the container being non-magnetic and there being a magnet fixed on the container in such location that the container may be moved over said surface between one or more predetermined positions where the magnet acts to automatically close the magnet switch and other positions where the magnetic field is not effective to operate said switch.

It is a major object of the invention to provide a novel combination of a heater unit wherein a circuit to an electrical heating element contains a magnetically operable switch that is normally open and a special container adapted to be placed on the heater unit, the container being essentially non-magnetic but there being at least one magnet fixed on the container whereby the switch is closed to energize the heating element only when the container is oriented to subject the switch to the magnetic field from the container.

A further object of the invention is to provide a novel beverage container such as a cup of non-magnetic material such as ceramic, glass or some metals wherein a permanent magnet is fixed in a lower part of the container in a predetermin peripheral or other off-center region such as near the outer bottom of a cup below the handle or off-center in the container bottom in alignment with the handle.

Further novel features and other objects of this invention will become apparent from the following detailed description, discussion and the appended claims taken in conjunction with the accompanying drawings.


Fig. 1 is an illustrative view showing a beverage warmer of the invention in use;

Fig. 2 is an enlarged plan view showing the beverage warmer of Fig. 1 according to one embodiment;

Fig. 3 is a section showing detail of the beverage warmer of Fig. 2 with a beverage container mounted on it;

Fig. 4 is a schematic view showing the electrical circuit and control;

Fig. 5 is a bottom plan view of the container or cup of Fig. 3 showing the magnet in an operative location; Fig. 6 is a section substantially at line 6-6 of Fig. 7 showing the invention according to a further embodiment;

Fig. 7 is a plan view of the heating unit partly broken away to show one form of heater element and location and the orientation of the reed switch;

Fig. 8 is a section substantially on line 8-8 of Fig. 7 showing heater unit detail;

Fig. 8 is a section showing a cup support plate with a different type of heater element attached;

Fig. 10 is a bottom plan view of the plate of Fig. 9; and

Fig. 11 is a bottom view of the cup of Fig. 6 showing the off-center location of the magnet.


Fig. 1 shows a beverage warmer heater unit 11 of the invention with a container 12 of liquid beverage such -as coffee seated on it.

As shown the unit 11 comprises a rigid base 13 having a depending rim 14 around its outer periphery, rim 14 having a flat lower surface 15 lying in a plane whereby the unit may seat evenly on a flat topped table 16 or the like.

A frame 17 which may be of plastic or wood extends around and is seated on the outer peripheral portion of the

base, preferably projecting a small distance outwardly with respect to rim 14. The inner periphery of frame 17 is recessed at 18 to seat a flat plate 19 of ceramic, glass or other non-magnetic material. The upper surface 21 of plate 19 is smooth and planar and this is the heating surface that supports the beverage container as will appear.

A heating element 22 is secured upon or immediately adjacent the flat bottom surface of plate 19. As shown in Figs. 2 and 3 the heating element is centered with plate 19 and comprises an assembly of heating resistors arranged to impart heat to plate 19 over a considerable part of its area, for example about half, and this heat is transmitted to a larger uniform area of surface 21.

Current for heating element 22 is provided by an electrical cord 23 containing the Input wires 24 and 25 of Fig. 2. The electrical circuit essentially comprises wires 24 and 25 connected to heating element 22 through an on-off switch 26 which here Is a magnetic reed switch and (Fig. 3) is mounted in an upwardly open compartment 27 in a predetermined location on base 13. Switch 26 is normally biased to the off or open circuit position shown in Fig. 4.

An indicator lamp 28 is mounted electrically across the circuit and is seated in an outwardly open side recess 29 in frame 17, the recess preferably being closed by a transluscent plastic or glass cover 31 usually red.

The electrical circuit may if desired include a normally closed switch 32 connected to a temperature responsive unit 33 that is located centrally of the base in an upwardly open compartment 34.

A layer or sheet of heat insulating or heat reflecting material indicated at 35 is provided on the base at least coextensively with and below heating element 22, this layer preferably being apertured as at 36 in alignment with the temperature sensitive unit 33, for exposing the unit to be directly heated by the heating element where such cor-tr l is

desired. The outer periphery 37 of the insulation layer or sheet is preferably bonded to the underside of plate 19 as shown to otherwise confine the heating element.

Thus substantially all of the heat emitted by element 22 is absorbed by the plate 19 which distributes it more uniformly to provide an evenly heated area on top surface 21.

The beverage container 12 may be an ordinary ceramic or plastic cup having a flat bottom rim 41 to be evenly seated on the planar upper surface 21 of plate 19, with the exception that the side wall in a predetermined location such as directly below and in alignment with the cup handle 42 is provided with a downwardly open recess 43 in which is mounted a permanent magnet 44.

The location of reed switch 26 may be such that it will lie approximately in vertical alignment with the magnet 44 on a normal size coffee cup seated on surface 21. In the invention the cups are usually selected or made to conform accurately to this dimension, although the invention may be applied to adapt conventional cups and heater plates to associate similarly. As shown in Fig. 2 the reed switch 26 is In a predetermined location at one side of the assembly. The reed switch is of any known construction wherein the switching elements thereof assume closed circuit condition when subjected to a predetermined magnetic force. Equivalent normally open magnetic switches may be used. The foregoing parts are so constructed and arranged that switch 26 will be closed only when the cup 12 is oriented to dispose magnet 44 at that side of plate 19 below which the switch 26 is mounted so that the switch is within the range of the magnetic field of magnet 44.

Should the cup 12 be oriented so as to dispose the magnet 44 at any other side of the plate 19, such as the top, bottom or the right in Fig. 2, switch 26 will not respond to the magnetic field and will remain open.

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In use of the invention the beverage to be heated or maintained heated may be placed in the cup 12 which is oriented about its vertical axis until the magnet 44 is positioned over the left side of the plate 19 as viewed in Fig. 2. To guide the user a colored or like visible index area 20 may be provided on the support to indicate the heat energizing position of the container handle. This closes the switch 26 and thereby energizes heating element 22 and indicator lamp 28. The beverage Is htereby heated. Should the heating temperature rise above a certain value, which for example would boil the beverage a control 22 may act to at least temporarily open switch 32 thereby deactivating the circuit, A balanced condition at a predetermined temperature of plate 19 can be achieved.

Should the user find the beverage too warm all he has to do is rotate the cup on surface 21 until the magnet no longer activates switch 26, and allow the beverage to cool.

Figs. 6-11 illustrate the invention in a further embodiment which differs mainly in the provision of a non-magneti metal support plate for the cup, and locations of the magnet and reed switch.

In this embodiment, the heater unit base 41 has an annular cover 42 surrounding an inverted shallow cup-shaped support plate 43 for the beverage cup. An annular heater housing 44 below the plate 43 contains a suitable electrical heating element 45 here a so-called rope type heater element which comprises a flexible resistance wire coil sheathed in a braided sleeve.

In this embodiment the reed switch 46 is mounted in a central housing compartment 47 so that it is located below the central portion of the plate and about equidistant between opposite sides of the plate. The heater unit 45 and reed switch 46, which is normally open, are interconnected as in the circuit of Fig. 4. In this embodiment no temperature responsive switch 32 is provided, but the warning light 28 is retained In the circuit.

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Below the heater unit, a heat shield 48 extends across teh housing interior, similarly to shield 35 of the Fig. 3 embodiment.

In this embodiment, the support plate 43 is of substantially unbreakable material and may be of non-magnetic metal, here an aluminum or aluminum alloy or may be of non-magnetic stainless steel. Preferably it is a metal stamping sized for fitting over and closing the heater unit housing. A stable smooth circular flat horizontal metal surface 49 thereby supports the container or cup 51.

It will be noted that the reed switch 46 is preferably oriented to extend substantially radially of the plate 43, and the base may also have two indicator bands such as band 20 of Fig. 2 at diametrically opposite sides.

Cup 51, like cup 12, is non-magnetic, usually of ceramic or stiff plastic, and it has a flat lower rim 53 resting on surface 49. In cup 51 the permanent magnet 54 is fixed in a downwardly open recess 55 in the cup bottom that is offset from the cup vertical axis in substantially radial alignment between the cup bottom center portion and the handle 56. In a normal sized coffee cup the magnet may for example be about one-half inch off-center in the cup bottom. This arrangement is beneficial in that it provides two opposed cup positions where the magnet will operate the centered reed switch, as for example the full and dotted line magnet locations shown in Fig. 11. This arrangement is beneficial and convenient for example to both right and left handed persons.

The foregoing embodiments provide a safe, efficient mode of beverage warming. The user need not turn a manual switch on or off. Expensive spring supports for the heater plate which may corrode are eliminated. The support plate surface can not be heated unless the properly oriented special container is on it, so that there is little danger of inadvertent burning or ignition of paper or the like that may contact the surface. If the container is inadvertently dislodged from the assembly, the heater is immediately aucomatically deenergized.

Figs. 9 and 10 Illustrate an alternate type of heater element usable in the Figs. 6-8 embodiment- Here the cup-chaped aluminum alloy plate 43 has an annular resistance type heater element 61 of the etched metal foil type with silicon insulation attached adhesively to its bottom surface. This is a known type of heater per se and r equivalently heat the support plate.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than hy the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.