EP2312908B1 - Hotplate with sensors - Google Patents

Description

The invention relates to a hob with sensors according to the preamble of claim 1. Such a hob is from the DE 37 33 108 C1 known.

Induction hobs are known from the prior art, which enable automatic detection of cooking utensils placed on the hob. For this purpose, either the Heizinduktoren the hob themselves are used as sensors or separate inductive sensors are arranged in the center of the inductors to detect the cookware element.

In both cases, the detection of the cookware element spatially relatively low resolution. The spatial resolution is limited by the distance between the heating inductors. Furthermore, the simultaneous use of the heating inductors as sensors is associated with an additional expense, since the heating inductors must either be connected to a readout electronics or to the power electronics, which requires additional circuitry and / or additional wiring. A high installation cost due to complex wiring is also necessary if the sensors are integrated into the heating elements.

The DE 37 33 108 C1 describes a cooktop having a cover plate, a plurality of heating elements disposed beneath the cover plate, and a plurality of sensors for detecting a cookware element mounted on the cover plate, wherein the sensors are disposed in a layer between the cover plate and the heating elements and a distance between adjacent sensors is less than a distance between adjacent heating elements, wherein the heating elements and the sensors are each arranged in a grid.

From the DE 10 2006 043 182 A1 is a hob with a cover known with four arranged under the cover plate heating elements and four sensors for detecting a position of a set on the cover plate cooking utensil, the sensors arranged in a layer between the cover plate and the heating elements are. The heating elements, which are each arranged below cooking zones, and the sensors, which are each arranged above the heating elements, are each arranged in a grid. Each heating element is assigned a sensor.

The invention is therefore in particular the object of providing a high-resolution and easy-to-install pot detection arrangement for a hob in a cost-effective manner, wherein the spatial resolution of the pot detectors to be improved.

The object is achieved in particular by a hob according to claim 1. Advantageous embodiments and modifications of the invention will become apparent from the dependent claims.

More particularly, the invention is directed to a hob having a cover plate, a plurality of heating elements disposed beneath the cover plate, and a plurality of sensors for detecting a cooking utensil mounted on the cover plate, the sensors being disposed in a layer between the cover plate and the heating elements. As a result, an independence of the sensors can be achieved by the heating elements. The number, distribution, size and cabling of the sensors can be made completely independent of the number, distribution and size of the heating elements and optimized for a better and higher-resolution pot detection. Furthermore, the assembly and the wiring can be simplified.

With regard to their sensor type, the sensors can all be designed as capacitive or all as optical sensors. Preferably, they are all designed as inductive sensors. It can also be provided that the plurality of sensors has at least one sensor of a first sensor type and at least one sensor of a second sensor type.

The advantages of the invention are particularly useful when the heating elements are inductors.

The spatial resolution of the sensor arrangement is improved with respect to the detection by means of heating inductors, since the distance between the adjacent sensors smaller is as a distance between the adjacent heating elements or heating inductors, wherein the heating elements and the sensors are each arranged in a grid, wherein the grid of the sensors is more closely meshed than the grid of the heating elements. The raster shape can also differ. For example, the heating inductors or heating elements can be arranged in a rectangular grid, while the sensors can be arranged in a triangular mesh or honeycomb network, or vice versa.

In a particularly inexpensive embodiment of the invention, the inductive sensors may consist of serigraphic conductor loops. Alternatively, the inductive sensors may be fabricated from flat foil cables known, for example, for cabling LCD displays.

The variety of components of the hob can be reduced when the inductors are applied to a back of a cover plate. Alternatively, the sensors may be applied to a carrier membrane arranged between the heating elements and the cover plate on a carrier screen, a carrier foil or carrier plate. In all cases, serigraphic methods can be used to print printed circuit traces, which are known, for example, from methods for producing car window heaters.

According to a further embodiment of the invention, the hob comprises a control unit for evaluating the signals of the sensors for detecting the cooking utensil element. The control unit may in particular be designed to use signals detected by the inductors in addition to the signals from the sensors for detecting the cooking utensil element. For this purpose, the number of necessary sensors can be reduced at a given spatial resolution. If the sensors are arranged in a grid, in particular those grid points can be omitted, which correspond to the centers of the inductors. The corresponding information can be determined by measuring the total effective inductance and / or the loss angle of the overall system consisting of the heating inductor and the cookware element.

Further advantages emerge from the following description of the drawing. In the drawings, embodiments of the invention are shown. The drawing, the description and the claims contain numerous features in combination.

Fig. 1

ein Kochfeld mit einer Abdeckplatte, vier Heizelementen und einem Raster von induktiven Sensoren in einer schematischen Draufsicht,

Fig. 2

eine Schnittdarstellung des Kochfelds aus Fig. 1 mit einem der induktiven Sensoren,

Fig. 3

die Abdeckplatte des Kochfelds aus Fig. 1 und 2 in einer Ansicht von der Rückseite,

Fig. 4

eine Explosionsdarstellung eines erfindungsgemäßen Kochfelds nach einer weiteren Ausgestaltung der Erfindung, und

Fig. 5

ein Kochfeld nach einer weiteren Ausgestaltung der Erfindung mit ausgesparten Rasterpunkten.

Show it:

Fig. 1

a hob with a cover plate, four heating elements and a grid of inductive sensors in a schematic plan view,

Fig. 2

a sectional view of the hob off Fig. 1 with one of the inductive sensors,

Fig. 3

the cover plate of the hob off Fig. 1 and 2 in a view from the back,

Fig. 4

an exploded view of a cooktop according to the invention according to a further embodiment of the invention, and

Fig. 5

a hob according to a further embodiment of the invention with recessed halftone dots.

The FIGS. 1 to 3 show a hob with a cover plate 10 made of glass or glass ceramic and a plurality of under the cover plate arranged heating elements 12a - 12d. The cooktop is an induction cooktop and the heating elements 12a-12d are inductors that generate a high-frequency magnetic field during operation of the cooktop that generates eddy currents in the bottom of a cookware element 14 to heat it.

On the back 20 of the cover plate 10, a plurality of inductive sensors 16 for detecting a size and position of the cookware element 14 is further arranged on the cover plate 10. The sensors 16 are arranged in a layer between the cover plate 10 and the heating elements 12a-12d ( Fig. 2 ), whose thickness is below about 1-2 mm, so as not to disturb the inductive coupling between the heating elements 12a-12d and the cooking utensil element 14 to be heated therefrom.

The sensors 16 are all configured as inductive sensors 16 in the exemplary embodiment. It can also be provided that at least one sensor 16 is a capacitive and / or at least one sensor 16 is an optical sensor.

In the in the FIGS. 1, 2 and 3 illustrated embodiment, this layer 18 is a serigraphically applied to the back 20 of the cover plate 10 layer of a conductive, suitable for screen printing paste, which can be cured or sintered after printing. The inductive sensors 16 are therefore formed from serigraphic conductor loops, the ends of which are connected via flat foil lines 22 or thin copper wires glued to the back side 20 of the cover plate 10 to a driver unit 24 for operating the sensors 16 of the layer 18.

The driver unit 24 can generate measurement currents in the sensors 16 in order to detect the inductance and / or a loss angle of an overall system formed from the conductor loops and the cookware element 14 and to deduce the presence of the cookware element 14 from this.

The driver unit 24 is just like the not explicitly shown power electronics of the hob controlled by a control unit 26, which is designed as a freely programmable arithmetic unit and which may be formed integrally with the driver unit 24 in alternative embodiments of the invention.

The heating elements 12a-12b and the sensors 16 are each arranged in a grid, wherein the grid of the sensors 16 is much closer meshed than the grid of the heating elements 12a - 12d. A lattice constant or a distance between two adjacent points of the grid of the heating elements 12a-12d is in the in Fig. 1 illustrated embodiment, four times as large as a lattice constant of the grid of the sensors 16. The inventive concept is also applicable to matrix cooktops with a closer-meshed grid of heating elements 12a - 12d. Such hobs comprise a large number of inductors, for example between 16 and 32 inductors. In this case, the pitch of the sensor raster may be twice as narrow as the pitch of the inductors or heating elements 12a-12d.

The FIGS. 4 and 5 show alternative embodiments of the invention. To avoid repetition, the following description of the figures is limited to differences to those in the FIGS. 1 to 3 illustrated embodiment. As description The consistent features will be on the description of the FIGS. 1 to 3 directed.

Fig. 4 shows an exploded view of a hob according to a further embodiment of the invention. The sensors 16 are mounted in a separable from the cover plate 10 layer 18 on a support membrane 30. The carrier membrane 30 is, for example, a temperature-resistant film and the sensors 16 may be screen-printed onto the carrier membrane 30. The entire wiring of the sensors 16 on the support membrane 30 via a common terminal 32, which can be easily plugged into a corresponding connector during assembly of the hob. The reading out of the sensors by the control unit 26 or the driver unit 24 is therefore particularly simple.

Fig. 5 shows a further alternative embodiment of the invention. In this embodiment of the invention, the sensors 16 are arranged in a grid, wherein those grid points are recessed, which correspond to the centers of the inductors or heating elements 12a - 12d. Since the heating elements 12a-12d can also be used as sensors, the information relating to the recessed halftone dots can be obtained by using the inductors 12a-12d as additional sensors.

Since the highest temperatures also occur in the center points of the heating elements 12a-12d, the omission of these points also reduces the maximum temperature to be expected for the sensors 16. As a result, the temperature stability requirements of the sensors 16 can be mitigated and further cost saving potentials can be developed.

reference numeral

10

cover

12

heating element

14

Cookware element

16

sensor

18

layer

20

back

22

film line

24

driver unit

26

control unit

28

operating element

30

support membrane

32

connection

Claims (11)

1. Hotplate with a cover plate (10), a plurality of heating elements (12a - 12d) arranged below the cover plate (10) and a plurality of sensors (16) for detecting a cookware element (14) placed on the cover plate (10), wherein the sensors (16) are arranged in a layer (18) between the cover plate (10) and the heating elements (12a - 12d) and a distance between adjacent sensors (16) is less than a distance between adjacent heating elements (12a - 12d), wherein the heating elements (12a - 12d) and the sensors (16) are arranged in a grid in each case, characterised in that the grid of the sensors (16) is more finely-meshed than the grid of the heating elements (12a - 12d).
2. Hotplate according to claim 1, characterised in that the heating elements (12a - 12d) are inductors.
3. Hotplate according to one of the preceding claims, characterised in that the sensors (16) comprise inductive sensors (16), in particular the sensors (16) are all inductive sensors (16).
4. Hotplate according to claim 3, characterised in that the inductive sensors (16) comprise serigraphically produced conductor loops.
5. Hotplate according to claim 3 or 4, characterised in that the inductive sensors (16) comprise flat foil cables.
6. Hotplate according to one of claims 3 to 5, characterised in that the inductive sensors (16) are attached to a rear side (20) of the cover plate (10).
7. Hotplate according to one of claims 1 to 5, characterised in that the sensors (16) are placed on a support membrane arranged between the heating elements (12a - 12d) and the cover plate (10).
8. Hotplate according to one of the preceding claims, characterised by a control unit (26) for evaluating the signals of the sensors (16) in order to detect the cookware element (14).
9. Hotplate according to claims 2 and 8, characterised in that the control unit (26) is configured, in addition to the signals of the sensors (16), to also use signals captured by the heating elements (12a - 12d) in order to detect the cookware element (14).
10. Hotplate according to claim 9, characterised in that the sensors (16) are arranged in a grid, wherein grid points which correspond to the centre points of the heating elements (12a - 12d) are omitted.
11. Hotplate according to one of the preceding claims, characterised in that the sensors (16) comprise at least one capacitive sensor and/or at least one optical sensor.

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