EP1858299B1 - Utilisation of left-handed meta materials as display, in particular on a cooking hob, display and display method - Google Patents

Abstract

The meta material has adjustable display medium and magnetizing medium in particular an induction coil, are arranged near the meta material . The meta material is arranged in the form of a layer or a thin plate close or directly at a housing wall or a cover of the display (18a,18b). An independent claim is also included for a method for electric appliance.

Description

Field of application and state of the art

The invention relates to the use of left-handed metamaterials as a display, for example on an electrical appliance such as a hob or the like, and a corresponding display and a display method.

From the EP 1 317 164 A1 a device for marking an induction coil is known. In this case, LEDs are arranged around an induction coil on a hob and are electrically supplied by coils in which a voltage is induced during operation of the induction coil. For example, an automatic operation indicator for the induction heating coil can be realized.

From the DE 10 2005 025 896 A1 It is known to provide areas or materials on a hob plate of a hob, which have different optical transmission properties. Thereby Both an operating or hot indication and possibly a temperature detection can be realized. Furthermore, it is also known to use thermochromic material on a hob. This changes its color depending on its temperature and is therefore also very good for a hot indication on a hob. Among other things, it is also described here that photonic crystals can be provided in the hob plate or a coating of a hob plate. These also have advantages for temperature evaluation with IR radiation.

Task and solution

The invention has for its object to provide an aforementioned use, a display and a display method, which disadvantages of the prior art can be avoided and in particular a display can be realized using materials that have their optical properties under possibly targeted action change.

This object is achieved by a use with the features of claim 1, a display according to claim 12 or a display method according to claim 14. Advantageous and preferred embodiments of the invention are specified in the further claims and are explained in more detail below. Some of the following features are listed only once. However, you should be able to apply regardless of all versions. The wording of the claims is incorporated herein by express reference.

It is envisaged that the left-handed metamaterials will be used as display or in display means. These are in particular a function or information display, for example an electrical appliance such as an electric cooking appliance, so about hobs or ovens. The left-handed metamaterials are present in the form of a layer or at least one thin plate, which are arranged near or directly to a housing wall or cover of the display or the electrical device. According to the invention, it is provided that switchable induction means or so-called magnetizing means are arranged in the vicinity of these left-handed metamaterials. In particular, this is an induction coil, which can be switched on and off particularly easily. The exact formation of such metamaterials can be found in the article " Nonlinear properties of left-handed metamaterials ", Physical Review Letters, volume 91, number 3, 037401-1 to 037401-4 or the article " Magnetic metamaterials at Telecommunication and Visible Frequencies ", Physical Review Letters, PRL 95, 203901-1 to 203901-4 be removed.

As starting materials for metamaterials, for example, copper and gold are each suitable with structures in the range of less than 10 .mu.m. Ferroelectrics such as Ba _x Sr _1-x TiO ₃ can also be used. More about this can be found in the US 6963259 B2 or the CA 2430795 A1 , When choosing materials, however, it should be noted that there are no materials that have such self-heating due to magnetic induction that they or the metamaterials would be damaged or even destroyed. This applies, for example, to nickel.

Such metamaterials make it possible, when applying or changing a magnetic field in whose field of action they are to change the optical properties so that they change, for example, from the opaque state into a transparent state.

As a result of the changing magnetic field of the magnetizing means or induction means, therefore, the metamaterial is influenced in such a way that its optical properties change. This can either affect their transmission properties, ie their transmission. Alternatively, it may relate to their reflection properties, ie reflection. It can also affect color properties. In cooperation with a respective structure of the display, this "optical switching" can thus be visible to an operator or made visible in order to realize the display function. This will be discussed in detail below. Likewise, it is also discussed how exactly this change of the magnetic field can be generated.

In one embodiment of the invention, the metamaterials are arranged on the display so that they are directly visible. Thus, for an operator, the change of the optical properties or the changed visual appearance can be recognized directly. One possibility here is an arrangement under a cover or panel, which is substantially transparent, so for example, consists of transparent glass or plastic. In another possibility, however, the metamaterials are arranged on a cover, housing wall or panel. This one is independent of the optical properties of the cover itself, since the metamaterials or their change in the visual appearance are visible anyway. So it can also be used an opaque cover.

In a further embodiment of the invention, the metamaterials can be arranged in front of light sources or in front of a light display and cover them, for example. In this case, the metamaterials are considered as a kind of aperture, which usually covers, for example, the bulbs or ensures that they are not visible. On the other hand, when the magnetic field is applied or its optical properties change, the metamaterial becomes transparent and so becomes the light source visible, noticeable. In this way, a display function for an operator can be realized.

According to an alternative embodiment of the invention, the metamaterials can be arranged behind light sources or a display. Then mainly reflective properties, which can be changed depending on a magnetic field, are used. It may be possible, for example, that a display for an operator is only then visible when the metamaterials or a layer consisting of them becomes reflective by applying a magnetic field.

In a further embodiment of the invention, the metamaterials in the manner of a layer or the like. be arranged under a substantially transparent cover. Although they are not necessarily visible, when they change their optical properties towards reflecting ambient light can reflect back through the cover so that it can be clearly perceived by an operator as an indicator. In this case, as in the other cases, the metamaterials can be designed in the form of symbols or labels that they should display as an indication.

As induction means or magnetizing means can advantageously be used coils. A particularly advantageous possibility is an induction coil under a cover. This is a very advantageous possibility, for example, as induction heating coil in an induction hob. The metamaterials are then in the effective range of the induction heating coil when an object to be heated, in particular a cookware, is placed on the cover. In this case, the metamaterials are particularly advantageously outside the induction heating coil such that they are expected to be outside the object to be heated, so that they are still visible. simultaneously However, they should not be too far away from the induction heating coil, so that the magnetic field to be reached is still strong enough for the desired effect or change in the optical properties.

One advantage of these metamaterials is their increased temperature resistance compared to LED displays. Thus, they may be arranged closer to a heater, such as a radiant heater in a hob.

In a particularly advantageous embodiment of the invention according to the aforementioned type, the metamaterials are arranged in an annular manner around the induction heating coil or along an annular contour. Advantageously, they have a small distance from the induction heating coil. This small distance should not exceed a few centimeters, so that, as previously described, the magnetic field is still strong enough. You can form a substantially closed ring. It is advantageously possible here, in particular when used in an induction hob, when the metamaterials are applied as a ring-like layer on top or on the underside of the hob surface. So they are clearly visible according to the above-described embodiments.

As an alternative to induction means or magnetizing means fixedly provided on the display, provision can be made for example when applying a magnetic operating element, in particular according to the DE 296 05 163 U1 , which generates the magnetic field for altering the metamaterials. If such an operating element attached to a designated position for subsequent operation of the electrical appliance so that its operational readiness can be displayed, for example, by changing display due to the changing optical properties of the metamaterials.

These and other features will become apparent from the claims but also from the description and drawings, wherein the individual features each alone or more in the form of sub-combinations in an embodiment of the invention and in other fields be realized and advantageous and protectable Represent embodiments for which protection is claimed here. The subdivision of the application into individual sections as well as intermediate headings does not restrict the general validity of the statements made thereunder.

Brief description of the drawings

Fig. 1 bis 3

alternative Ausbildungen eines Induktionskochfeldes mit Induktionsheizspule und einer Anzeige mit Metamaterialien;

Fig. 4

eine Draufsicht auf das Induktionskochfeld gemäß Fig. 1 und

Fig. 5

eine Bedienvorrichtung mit einem abnehmbaren magnetischen Drehknebel und einer Anzeige ähnlich Fig. 1.

Embodiments of the invention are shown schematically in the drawings and will be explained in more detail below. In the drawings shows:

Fig. 1 to 3

alternative embodiments of an induction hob with induction heating coil and a display with metamaterials;

Fig. 4

a plan view of the induction hob according to Fig. 1 and

Fig. 5

an operating device with a removable magnetic rotary knob and a display similar Fig. 1 ,

Detailed description of the embodiments

In Fig. 1 an induction hob 11 is shown. It has according to a conventional induction hob on a cooktop plate 13, below which an induction heating coil 15 is arranged. Their size defines a hob 16, on which a cookware 17 is placed as a saucepan. In this case, the diameter of induction heating coil 15, Hotplate 16 and cookware 17 approximately match, or should agree for the best possible heating of the cookware 17 and its contents.

Furthermore, a display 18a or 18b according to the invention is provided. Although these are shown together, only one is available in practice. The display 18a includes a layer 19 of left-handed metamaterial as previously described. This lower layer 19 is disposed on the underside of the cooking field plate 13, slightly outside or adjacent to the surface corresponding to the extent of the induction heating coil 15 and the hotplate 16, respectively. Although it may continue to extend to the center of the induction heating coil 15 back. But then she is like out Fig. 1 can be seen, with attached cookware 17, ie when operating the induction hob 11, covered by the cookware 17 and no longer visible, so would bring little benefit.

The display 18b accordingly has an upper layer 20, which also consists of left-handed metamaterial or has this. Also, it is, as shown, usefully arranged outside the hob 16 or adjacent to this. In addition to the aforementioned reasons plays here also a role that depending on the mechanical resistance of the layer, the cookware 17 is then placed less frequently on the layer 20 and thus could neither damage nor scratch or remove it.

Layers 19 and 20 are shown in FIG Fig. 1 shown greatly exaggerated thick. This is certainly not necessary in practice, layer thicknesses of 1 mm and less are considered sufficient. This applies in particular to the upper layer 20, since an increasing thickness would be disturbing here.

The shape or configuration of the layers 19 and 20 is the Fig. 2 to 4 explained in more detail below. In principle, however, it should be noted, as already stated above, that the layers of the left-handed metamaterials, thus also the layers 19 and 20, can be formed in any desired form, that is to say both as simple surfaces and as symbols, characters or the like.

In Fig. 1 Although not the exact course of the magnetic field during operation of the induction heating coil 15 is shown. With attached cookware 17, that is, when the induction heating coil 15 is actually in operation for a long time, most of the magnetic field is concentrated in the bottom of the cookware. Nevertheless, even at the edge, that is to say where the layers 19 and 20 are arranged, a sufficiently strong magnetic field or stray field is produced in order to bring about the aforementioned change in the optical properties of the left-handed metamaterials.

In Fig. 2 is another induction hob 111 shown in a modified form. On the hob plate 113 with the induction heating coil 115 underneath, in turn, a cookware 117 is placed on a hotplate 116. Again, two displays 118a and 118b are shown, similar to FIG Fig. 1 , However, here are further arranged below each other display means. Under the lower layer 119, a seven-segment display 123 of the known type is arranged. Under the upper right layer 120, a simple light source 122 is arranged, for example a single LED, a glow lamp or the like.

In the further modification according to Fig. 3 For example, an induction hob 211, which is in principle the same as the display 218, has a lower layer 219 with the left-handed metamaterial. It is tilted so that it is illuminated by a light source 222 arranged to the left, which is shielded at the top by the shield 224 and thus is not visible in the active state, and the beam path the light rays are deflected upward through the hob plate 213.

Function of the described embodiments

The function of the indicators 18 in the versions of Fig. 1 to 3 is the following. at Fig. 1 When the induction heating coil 15 is switched on, the optical behavior of the layers 19 and 20 changes. If they were transparent or transparent, for example, without a magnetic field, they can now be seen as opaque or as a layer or as a symbol. While this is self-evident in the upper layer 20, since it is in the direct field of view, for the detection of a lower layer 19, ie below the hob plate, a substantially transparent cooktop plate is necessary. This can, in particular in an induction hob, consist of hard glass and has the necessary physical properties. Thus, the change in state of the layer 19 can be recognized by the cooktop plate 13 and be understood as a display function.

For the displays 118 according to Fig. 2 the layers 119 and 120 illuminate illuminated displays. So while in Fig. 1 To illustrate the operation of the induction heating coil, the layers have changed their optical properties from transparent to intransparent, this is done in Fig. 2 the other way around. The otherwise non-transparent layers 119 and 120 become transparent or translucent when the induction heating coil 115 is operated with the magnetic field generated. As a result, the illuminants 122 or the seven-segment display 123 arranged underneath are visible to an operator as an indication. In the case of the layer 120, it can be provided that either the formation of the layer 120 or another masking not only represents a light spot produced by the luminous means 122, but also a specific symbol.

In the operation of the display 218 according to Fig. 3 In turn, in the deactivated state of the induction heating coil 215, the layer 219 is not reflective. If it is influenced by the magnetic field of the induction heating coil 215 during its operation, it changes its optical properties and becomes reflective. As a result, the light of the luminous means 222 is reflected upward in accordance with the illustrated beam path and can be recognized by an operator as an operating indicator of the cooking position 216.

Further embodiments of displays with layers of left-handed metamaterials are easy to realize for the expert on the basis of the aforementioned information. Likewise, besides the three types shown, further state changes of the metamaterials under the influence of a magnetic field can be used for display purposes.

In Fig. 4 is in plan view of the induction hob 11 according to Fig. 1 illustrated how the upper layer 20 is formed so to speak as a closed ring around the hob 16 and a provided cookware 17 around. When the induction heating coil 15 is operated as described above, the layer 20 changes its optical properties, becomes, for example, opaque or changes in color or reflectivity. This is, in particular because the layer 20 is applied to the top of the hob plate 13, visible to an operator as a display 18. Likewise, as previously stated, the left lower layer 19 may also be used as shown in FIG Fig. 1 be formed in such a ring-like shape as a display.

Another embodiment is in Fig. 5 shown as an operating device 310. This operating device is based on the principle of the aforementioned DE 296 05 163 U1 built up.

On a cover or housing wall 313, either lower layers 319 or upper layers 320 are provided with said left-handed metamaterials, again in any shape or planar configuration. Below the cover 313 is a lower magnet 326 together with lower magnetic star 327th

Opposite the stationary magnet 326 is defined a location on which a detachable rotary knob 329 can be placed to operate or input commands. This rotary knob 329 includes a central magnet 330 together with the associated upper magnetic star 331. Will be in accordance with the above DE 296 05 163 U1 the rotary knob 329 positioned above the lower magnet 326 for a subsequent rotary operation, the magnetic field generated by it triggers said changes in the layers 319 or 320. In order to change these, similar to the start-up of the induction heating of the previous embodiments, their optical properties in the context of all the aforementioned possibilities and thus also form a display 318a and 318b.

In this embodiment, however, care must be taken that the magnetic field of the lower magnet 326 together with the lower magnetic star 327 does not already cause the optical properties in the layers 319 and 320 to change, but only the placement of the rotary knob 329. However, this is no problem for the person skilled in the art In addition, could be arranged in the outer region of the rotary knob 329 more magnets, for example, to display a certain rotational position similar to any other optical marking at a certain point of the rotary knob, for example, by additional shields. At a similar Fig. 4 Around the rotary knob 329 extending ring can then by moving the rotary knob and by the attached to the outside of the magnet a mitwandernder range modified optical Properties are generated in layer 319 or 320. This shows an operator just the rotational movement as usually odgl a projecting arrowhead. would do.

Claims (15)

1. Use of left-handed metamaterials as an indicator (18, 118, 218, 318) or in indicating means, in particular as a function indicator or information display on an electric appliance or hob (11, 111, 211), characterised in that the metamaterials are arranged in the form of a layer or at least a thin plate close to or immediately on a housing wall or cover of the indicator (18, 118, 218, 318), switchable induction means or magnetising means, in particular an induction coil, being arranged in the vicinity of the metamaterials.
2. Use according to claim 1, characterised in that the metamaterials are arranged in a directly visible manner on the indicator (18, 118, 318), in particular under a substantially transparent cover (13, 113, 313).
3. Use according to claim 1, characterised in that the metamaterials are arranged in a directly visible manner on the indicator (18, 118, 318), in particular on a cover (13, 113, 313).
4. Use according to any one of the preceding claims, characterised in that the metamaterials are arranged in front of illumination means (122, 222) or an indicator light (123) and in particular cover said means or light.
5. Use according to any one of claims 1 to 3, characterised in that the metamaterials are arranged behind illumination means or an indicator light, in particular as reflector means.
6. Use according to claim 1 or claim 2, characterised in that the metamaterials (19) are arranged under a substantially transparent cover (13) as reflector means for reflecting ambient light back through the cover.
7. Use according to any one of the preceding claims, characterised in that the induction means are an induction heating coil (15, 115, 215) under a cover (13, 113, 213), the active region of which, with an article (17, 117, 217) to be heated positioned on the cover, encompasses the metamaterials (19, 20, 119, 120, 219, 220).
8. Use according to claim 7, characterised in that the metamaterials are arranged in a ring around the induction heating coil (15, 115, 215, 315), preferably at a distance of at most a few cm, and in particular form a substantially closed ring.
9. Use according to any one of claims 1 to 6, characterised by additional induction means (330, 331) which are provided solely to influence the metamaterials.
10. Use according to any one of the preceding claims, characterised in that, to produce left-handed metamaterials, only materials with a heat resistance greater than 200°C, preferably greater than 300°C, are used, in particular metals and/or optionally conductive doped ceramics.
11. Use according to any one of the preceding claims, characterised in that the characteristics of the left-handed metamaterials vary in the visible range or the magnetic field of the magnetising means is appropriately selected.
12. An indicator, in particular acting as a function indicator or information display (18, 118, 218, 318) on an electric appliance or hob (11, 111, 211), characterised in that it comprises left-handed metamaterials, which are arranged in the form of a layer (19, 20, 119, 120, 219, 220, 319, 320) or at least a thin plate close to or directly on a housing wall or cover (13, 113, 213, 313) of the indicator, switchable induction means or variable magnetising means (330, 331), in particular an induction coil (15, 115, 215) being arranged in the vicinity of the metamaterials (19, 20, 119, 120, 219, 220, 319, 320).
13. An indicator according to claim 12, characterised in that it comprises one of the characterising features of any one of claims 2 to 11.
14. An indication method for an electric appliance (11, 111, 211), characterised in that left-handed metamaterials (19, 20, 119, 120, 219, 220, 319, 320) are changed with regard to their optical characteristics by switching on or switching off or varying a magnetic field (15, 115, 215, 330, 331) by way of influence, so that an operator may detect the changed optical characteristics as an indicator (18, 118, 218, 318).
15. A method according to claim 14, characterised in that said influence involves an operator bringing a magnet (330, 331) closer to the metamaterials (319, 320), in particular upon positioning an article provided with the magnet, preferably a mobile operating element (329), at a position intended therefor on the electric appliance.

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