EP1580487B1 - Electronically controlled hob with a plurality of cooking plates and method for its operation - Google Patents

Abstract

A glass ceramic cooking hob unit (11) has multiple cooking zones (14) heated by inductive heating elements (16) having capacitive sensing elements (22) which sense the existence of a cooking vessel (25). A single heating control switch (21) operates on any cooking zone selected by the user (27).

Description

Field of application and state of the art

The invention relates to a cooktop with a plurality of burners according to the preamble of claim 1 and a method for operating such a cooktop, which may be electronically controlled in particular.

For the power setting of, for example, hobs with touch switches, it is known to provide a so-called selection / select buttons for each hotplate, as well as a plus and a minus button for changing the power setting. By pressing one selection button each, a hotplate is selected. In this selected state, the power can be changed using the plus or minus buttons. Such a change in performance is only possible if a hotplate has been previously selected. In this way it is possible to reduce the number of plus / minus buttons, because only a single pair is to be provided for the entire hob and only one selection key per cooking zone.

Efforts have been made to further reduce the number of touch buttons required. It is for example in the DE 102 11 047 A described to select a hotplate by setting up a cooking vessel. A so-called pot detection sensor detects the installed cooking vessel and puts this cooking point in the selected state, so that after setting the cooking vessel, a power setting is possible. However, this method is apparently only suitable for the first power setting at the beginning of the operation of the cooking area. It is no longer suitable for subsequent performance settings.

A cooker with capacitive touch buttons is out of the US 2002/162730 known.

Task and solution

The invention has for its object to provide an aforementioned cooktop and an aforementioned method with which the problems and disadvantages of the prior art can be avoided and hobs and their operation can be further developed, in particular a selection of a hotplate at any possible Operating conditions can be improved.

This object is achieved by a hob with the features of claim 1 and a method having the features of claim 8. Advantageous and preferred embodiments of the invention are the subject of further claims and are explained in more detail below. The wording of the claims is made explicit reference to the content of the description. The features of the method according to the invention in various embodiments also result from the following description in a corresponding manner.

According to the invention, it is provided that such a hob has a selection device for each hotplate, with which it can be selected in preparation for an operator initiated or desired change in the operating state of the hotplate. Such a change of the operating state is preferably a change of the power. However, it can also be switched on or off, for example, in a so-called multi-circuit cooking area, an additional heating circuit. The selection device has an actuation sensor or such a device. The actuation sensor is designed such that it detects a touch of a cooking vessel on this hotplate by an operator. Such a touch evaluates the hob as a selection of this hotplate to allow depending on a user-dependent change in the operating state of the cooking position by further operator inputs.

This means in a possible embodiment that a touch or a touch of a cooking vessel is detected by the hob and this cooking vessel or the relevant hotplate is assigned. From the point of view, this is regarded as a selection of the cooking area in order to change the operating state of this cooking area depending on known methods. So can be dispensed with further input elements or controls such as the aforementioned select buttons. Furthermore, an instinctive selection of a cooking position by touching the cooking vessel on top of it is possible. Finally, it has been found in the context of investigations of this invention that in many cases, a touch of the cooking vessel, for example when lifting the lid or while stirring with simultaneous holding takes place. In practice, these actions are often followed by changes, at least to the power setting of the hotplate, since the operating state is recognized as undesirable. Thus, the selection of cooking zones to be changed happens almost automatically or by itself. In addition to the savings effect of a so-called selection key, an operator can in many cases even be spared even the selection process itself.

As an actuation sensor, basically different types of sensors can be used, which detect the touching of the cooking vessel. This can be a so-called capacitive sensor, as it is for example in the DE 42 24 934 A is described. Alternatively, it may be an inductive sensor, which may, for example, have a coil shape. Such an inductive sensor is for example in the DE 196 03 845 A disclosed. Furthermore, it is possible that an actuation sensor detects a slight movement of the cooking vessel, for example a slight back and forth by a few centimeters. Such a process can be detected in addition to the usual, above-described method by optical sensors or the like above the hob and sensors for vibration or acceleration under the hob.

In a preferred embodiment of the invention, an actuation sensor may simultaneously be a so-called cooking vessel detection sensor, also known as pan detection. Through this dual function, the number of sensors to be provided can be reduced. In this sense, it is therefore advantageous if the presence of a cooking vessel as well as a touch of the same is detected by the same measuring method. The different operating modes can, for example, take place alternately.

It is advantageous if the actuation sensor is arranged below the hob or a hob plate. So he does not disturb the appearance, is easy to install or provide on the hob and is also from impairment such as pollution or like protected. Such a hob plate is advantageously made of glass ceramic, which is permeable to the aforementioned sensors.

In one embodiment of the invention, even more actuation sensors can be provided per selection device or per hotplate. These are advantageously arranged at different positions. Thus, an adaptation to possible different sizes of a cooking vessel can take place on this cooking point, for example in a multi-circuit heating. The plurality of actuation sensors can be arranged in cooperation with possible sizes of the cooking vessel so that depending on the size of the cooking vessel only one actuation sensor responds to the touch of a cooking vessel.

Furthermore, it can be provided according to the invention that common control elements are provided for the operator-dependent change of the operating state of the hotplate, for example a setting of a power, which have the function assigned to them exactly the same for all cooking zones. Advantageously, these are a so-called plus and minus control with which the power can be increased or decreased continuously or in stages. If a hotplate is selected by touching the cooking vessel placed on top of it, then the common operating elements are aligned with this hotplate or their function changes the operating state of this hotplate.

It can be provided that by means of corresponding devices a feedback is issued to an operator, which indicates a selection state or a change in the operating state of a hotplate. If, for example, a selection is recognized as such, a feedback can be sent to the operator. This can be done visually or acoustically.

Furthermore, to increase the ease of use and the operating safety can be provided that the selection of a hotplate for a certain time is maintained as such, so to speak to give the operator time to change the operating state. Such a time period should be in the range of several seconds, for example a maximum of 10 seconds. Thus, incorrect operation can be avoided by too long selection times.

In a further embodiment, it can be provided that the selection of a cooking station is canceled immediately when an inappropriate operating state occurs or, for example, another cooking is selected. Either then this additional cooking area is selected or just the selection of the previous ones canceled.

As a further security feature can be provided that only then a selection is recognized as such when a standing on the hob cooking vessel is touched for a certain time. This time should also be in the range of seconds, preferably at least one second. It can thus be avoided that a selection takes place in the case of a fleeting contact, which, due to its short time, can actually only be unintentional.

Furthermore, it can be provided that in the event that two cooking vessels are touched at the same time, so either the touch has taken place at the same time or at least temporally overlapping, no selection is evaluated. In that case, it is not possible to make a precise distinction as to which hotplate should actually be selected. In such a case, for example, a corresponding signal in the manner of a fault or danger signal can be output to an operator.

If a so-called inductive cooking vessel detection sensor used as an actuation sensor and evaluated with Schwingkreisverstimmung, it can be operated at a higher frequency to detect a touch of the cooking vessel. For example, in the aforementioned types of sensors, this frequency may be in the range of 2 MHz to 30 MHz, preferably between 8 MHz and 20 MHz. This is due to the applied evaluation method of frequency measurement. In order to be able to evaluate the extremely small change in the resonant circuit capacitance of approximately 5 pF by touching the cooking vessel, it is necessary to operate the resonant circuit in the vicinity of the self-resonance of the sensor. From the strainer capacity of the cooker detection sensor, about 50 pF to 200 pF, and a small resonant circuit capacity, about 50 pF to 220 pF, and the cooker detection sensor inductance, about 300 nH to 800 nH, with the cooking vessel installed, a high resonant frequency results.

These and other features will become apparent from the claims but also from the description and the drawings, 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 drawing

An embodiment of the invention is in different variants in the Fig. 1 shown schematically and will be described in more detail below. It shows Fig. 1 a schematic perspective view of a cooking hob according to the invention with four burners and serving as a selector cooking vessel detection.

Detailed description of the embodiment

In Fig. 1 schematically a hob 11 is shown in an oblique view, in which the invention is implemented in two variants. The hob 11 has a glass ceramic plate 12 which forms the surface. However, this could also consist of other materials. On the glass ceramic plate 12 a plurality of hotplates 14a - d are provided, as in a conventional hob, namely approximately evenly distributed. They can be identified by corresponding markings on the upper side of the glass-ceramic plate 12, for example corresponding printing or the like. Of course, it is also possible to provide so-called switchable multi-circuit cooking, be it in round or oblong shape.

Under each hotplate 14a-d, a heater 16a-d is provided in each case. These are in particular in glass ceramic plates 12 so-called radiant heaters. Alternatively, induction heaters could be used, with the type of heater used for the invention not playing any role in this regard. Each of the heaters 16a-d is controlled by a controller 18 and energized according to a selected cooking or power level. For this purpose, the power switches 20a-d are provided, namely one for each heater 16. By means of touch switches 21, which are arranged on the right edge of the glass ceramic plate 12 and have corresponding markings on the top of the plate, the operation of the hob 11 can be done, for example, as setting a cooking or power level for the heater 16 a hob 14. Dazu For example, the touch switches 21 are provided with plus and minus symbols to increase or decrease the power. The touch switches 21 can For example, be designed as a capacitive touch switch and be so-called touch buttons or switches. In addition to capacitive operating principles and optical or other can be used, as mechanical switches or the like are possible. By placing a finger 27, the touch switches 21 can be operated according to their function.

Furthermore, below the cooking zones 14, advantageously between glass ceramic plate 12 and heater 16, the so-called cooking vessel detection sensors 22a and d. These can be designed in different forms. In a variant of the invention, a cooking vessel recognition sensor 22a, which has an approximately coil shape and is connected to the controller 18, is provided below the cooking point 14a. Such a sensor is for example in the EP 788 293 A which is expressly referred to in terms of possible implementations. Such a cooking vessel detection sensor 22a is usually used to detect the placement of a cooking vessel 25a on the cooking area 14a and only then to enable power to the heater 16a. Thus, a malfunction of a hotplate or an associated heater without attached cooking vessel from which either a risk of burn or at least energy loss would be avoided.

In another variant of the invention, two cooking vessel detection sensors 22d, which are not formed in coil form, are arranged underneath the cooking point 14d, but form two individual surfaces which are arranged approximately opposite one another with respect to the size of the cooking point 14d at its edge. This cooking vessel detection sensors 22d may have a capacitive operating principle, as for example from the DE 42 24 934 A is known. Although another functional principle is used. However, the purpose is the same, namely the detection of presence, education and possibly also the size of a vessel placed on the cooking area associated with the cooking vessel detection sensor.

function

In the following, the function will be described with reference to the hotplate 14a with the coil-shaped inductive cooking vessel detection sensor 22a. However, this functional description is expressly not limited to the specific design of the cooking vessel detection sensor 22a, but can be used, either directly or in a corresponding modification, with other cooking vessel detection sensors, especially if they work with electromagnetic fields, so either inductive or capacitive nature ,

Since only the two touch switches 21 are provided in the cooking hob 11 according to the invention for adjusting the power of all cooking zones 14a-d, a so-called selection, also referred to as selection, must take place. This is used to determine at which cooking point 14 the cooking or power level is changed during a subsequent process. If a cooking vessel 25 is set up, this is recognized by the cooking vessel detection sensor 22 together with the controller 18. The controller 18 evaluates this as a selection of the corresponding hotplate 14. This means that a subsequent actuation of the touch switch 21 for the state of this particular hotplate 14 and the associated heater 16 applies. This is in itself in this way from the prior art in the form of DE 102 11 047 known.

However, to make some time after setting up the cooking vessel or at any time during cooking, especially with multiple cooking zones of the hob 11, a change in the cooking or power level of a hotplate 14, this must again to be selected. According to the invention, this is done by touching the cooking vessel 25 with a finger 27. It is emphasized that a displacement of the cooking vessel is indeed possible and under certain circumstances, the clarity of a selection can underline. In principle, however, it is not necessary, since such a displacement would have to be so great, at least to the extent that it can be reliably detected by a cooking vessel detection, that under certain circumstances it is considered to be complicated or even impractical.

In the context of the invention, it has been shown that, with a correspondingly precise tuning and evaluation of the signals of the cooking vessel detection sensor 22, it can be determined whether a cooking vessel is being touched. For this purpose, metallic cooking vessels are necessary. By touching the cooking vessel 25 with one or more fingers 27, the capacity of an operator is added in parallel to the resonant circuit capacity. This can be recognized by the signal of the cooking vessel detection sensor 22. In order to detect this contact of the cooking vessel, it is necessary to shift the operating frequency of the cooking vessel detection sensor to very high values, for example 2 MHz to 30 MHz, preferably 8 to 20 MHz.

Was registered on the cooking vessel detection sensor 22 and the controller 18 that the cooking vessel has been touched, this is considered a selection and a subsequent actuation of the touch switch 21 or other state switch then applies exactly for this hotplate, for example, could also have an additional heating zone be switched on.

It can be provided to delete the selection state of the hotplate relatively quickly after actuation of the touch switch 21. Alternatively, it may be provided to maintain this state at least for a few seconds to a shortly thereafter fast change does not have to re-start a selection process.

Likewise, it may be possible to maintain this selection state a few seconds, for example 3 to 10 seconds after selecting a hotplate by touching the cooking vessel 25 thereon with a finger 27. Thus, a user is given sufficient time to change their performance or condition after selecting a particular hotplate.

If another cooking vessel 25 is touched after the selection of a hotplate and before actuation of the touch switch 21, the selection of the hotplate advantageously switches to the last actuated or the selection of the cooking surface activated first is canceled.

Above all, it is advantageously provided in the invention that, after the touch of a cooking field 25 has been detected, a corresponding signal is output to a user, either optically or acoustically. It is not necessary to continue to touch the cooking vessel 25 during the change of the state of the hotplate via the touch switches 21. A single touch, possibly with a minimum of time required, may be considered sufficient.

Claims (14)

1. A hob (11) with a plurality of rings (14), on which in each case a cooking vessel (25) may be placed for heating food contained therein, said hob having a selection means for each ring for selection in preparation for operator-dependent modification of the operating state, characterised in that the selection means comprises an actuation sensor (22), which is designed such that it detects touching of a cooking vessel (25) on said ring (14) by an operator, the hob (11) regarding this as selection of the ring for the purpose of operator-dependent modification of the operating state of the ring by further operator input.
2. A hob according to claim 1, characterised in that the actuation sensor is a capacitive actuation sensor, it comprising in particular a sensor surface (22d).
3. A hob according to claim 1, characterised in that the actuation sensor is an inductively operating sensor (22a), preferably in the form of a coil.
4. A hob according to any one of the preceding claims, characterised in that the actuation sensor (22) is at the same time a cooking vessel detection sensor.
5. A hob according to any one of the preceding claims, characterised in that the actuation sensor (22) is arranged below the hob (11) or below a hob plate (12), which preferably consists of glass ceramic.
6. A hob according to any one of the preceding claims, characterised in that a plurality of actuation sensors (22d) are provided per selection means and per ring (14d) at different positions around the ring, the plurality of actuation sensors (22d) in each case being activatable as a function of the size of the cooking vessel (25).
7. A hob according to any one of the preceding claims, characterised in that it comprises a plurality of common operating elements (21) for operator-dependent modification of the operating state of the ring (14), in particular adjustment of the power of each individual ring, preferably one plus and one minus operating element for all the rings, it being possible, after selection of a ring by way of the actuation sensor (22) by touching a cooking vessel (25), to modify the power of said ring accordingly by actuation as desired of the operating elements.
8. A method of operating a hob according to any one of the preceding claims, characterised in that, by touching a cooking vessel (25) placed on a ring (14), this ring is selected for operator-dependent modification of its operating state, modification of the operating state proceeding through operation of further operating elements (21) of the hob, in particular as a modification of power level.
9. A method according to claim 8, characterised in that, after selection of a ring (14) by touching a cooking vessel (25) standing thereon, a status signal is output to an operator, which is preferably visual and/or acoustic.
10. A method according to claim 8 or claim 9, characterised in that a ring (14) is regarded as selected only when the cooking vessel (25) standing thereon has been touched by the operator for a given time in the range of seconds, preferably at least one second.
11. A method according to any one of claims 8 to 10, characterised in that selection of the ring (14) is maintained for a specific period, preferably at most 10 seconds.
12. A method according to any one of claims 8 to 11, characterised in that selection of a ring (14) is cancelled immediately if another ring has been selected by touching a cooking vessel (25) standing thereon.
13. A method according to any one of claims 8 to 12, characterised in that, in the event of simultaneous or overlapping touching of a plurality of cooking vessels (25) on different rings (14), no selection is considered to have been made, a warning signal preferably being output to an operator.
14. A method according to any one of claims 8 to 13, characterised in that an inductive cooking vessel detection sensor (22) is used as the actuation sensor, said sensor preferably being operated at a frequency close to natural resonance.

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