DOMESTIC APPLIANCE DEVICE

Abstract

A household appliance apparatus, in particular a cooktop apparatus, includes a temperature sensor unit which includes a photodiode designed to detect incident infrared radiation and to convert the incident infrared radiation into a measurement signal. The measurement signal is amplified by an amplifier of an amplifier unit. A compensation unit at least partially compensates for a temperature influence as the infrared radiation is converted into the measurement signal and/or the measurement signal is amplified.

Claims

1-15. (canceled)

16. A household appliance apparatus, in particular a cooktop apparatus, comprising: a temperature sensor unit comprising a photodiode designed to detect incident infrared radiation and to convert the incident infrared radiation into a measurement signal; an amplifier unit comprising an amplifier designed to amplify the measurement signal; and a compensation unit designed to at least partially compensate for a temperature influence as the infrared radiation is converted into the measurement signal and/or the measurement signal is amplified.

17. The household appliance apparatus of claim 16, wherein the photodiode is arranged in a high temperature region having a temperature of up to 250 C.

18. The household appliance apparatus of claim 17, wherein the amplifier unit is arranged in a region in which a temperature thereof is reduced relative to a temperature in the high temperature region.

19. The household appliance apparatus of claim 18, wherein the compensation unit is arranged in the region of the amplifier unit.

20. The household appliance apparatus of claim 16, further comprising an electrical cable, the temperature sensor unit and the amplifier unit being connected together via the electrical cable.

21. The household appliance apparatus of claim 20, wherein the electrical cable is a shielded cable.

22. The household appliance apparatus of claim 16, wherein the compensation unit is designed to compensate electrically for a temperature influence as the infrared radiation is converted into the measurement signal and/or the measurement signal is amplified.

23. The household appliance apparatus of claim 16, wherein the compensation unit and the amplifier unit are configured at least partially in one piece.

24. The household appliance apparatus of claim 16, wherein the compensation unit comprises an amplifier designed to compensate for the temperature influence.

25. The household appliance apparatus of claim 24, wherein the amplifier of the amplifier unit and the amplifier of the compensation unit are at least substantially structurally identical.

26. The household appliance apparatus of claim 24, wherein the amplifier of the amplifier unit and the amplifier of the compensation unit are part of a common symmetrical electrical switching circuit.

27. The household appliance apparatus of claim 16, further comprising a printed circuit board, the amplifier unit and the compensation unit being commonly arranged on the printed circuit board.

28. The household appliance apparatus of claim 16, wherein the amplifier unit and the compensation unit are configured as discrete electrical switching circuits.

29. The household appliance apparatus of claim 16, wherein the amplifier unit and the compensation unit each comprise a feedback capacitor.

30. A household appliance, in particular a cooktop, the household appliance comprising a household appliance apparatus which includes a temperature sensor unit comprising a photodiode designed to detect incident infrared radiation and to convert the incident infrared radiation into a measurement signal, an amplifier unit comprising an amplifier designed to amplify the measurement signal, and a compensation unit designed to at least partially compensate for a temperature influence as the infrared radiation is converted into the measurement signal and/or the measurement signal is amplified.

31. A method for operating a household appliance apparatus, in particular a cooktop apparatus, the method comprising: detecting incident infrared radiation and converting the incident infrared radiation into a measurement signal by a photodiode of a temperature sensor unit; amplifying the measurement signal with an amplifier of an amplifier unit; and at least partially compensating with a compensation unit a temperature influence as the infrared radiation is converted into the measurement signal and/or the measurement signal is amplified.

32. The method of claim 31, further comprising arranging the amplifier unit in a region in which a temperature thereof is reduced relative to a temperature in a temperature region of the photodiode of up to 250 C.

33. The method of claim 31, wherein the temperature influence is electrically compensated as the infrared radiation is converted into a measurement signal and/or the measurement signal is amplified.

34. The method of claim 31, further comprising compensating for the temperature influence with an amplifier of the compensation unit.

35. The method of claim 34, further comprising forming the amplifier of the amplifier unit and the amplifier of the compensation unit as parts of a common symmetrical electrical switching circuit.

Description

[0033] In the drawing:

[0034] FIG. 1 shows a schematic plan view of a household appliance with a household appliance apparatus, comprising a temperature sensor unit, an amplifier unit and a compensation unit,

[0035] FIG. 2 shows a schematic electrical circuit diagram of the amplifier unit and the compensation unit,

[0036] FIG. 3 shows a schematic diagram for illustrating temperature influences on the amplifier unit and the compensation unit and

[0037] FIG. 4 shows a schematic process flow diagram for illustrating a method for operating the household appliance apparatus.

[0038] FIG. 1 shows a household appliance 50 in a schematic plan view. The household appliance 50 is configured as a cooktop, and namely as an induction cooktop. The household appliance 50 comprises a heating unit 38 with a plurality of induction heating elements 40.

[0039] The household appliance 50 comprises a cooktop plate 42, for setting down an item of cookware, which is shown in FIG. 1 by way of example as a cooking pot 44, on a surface 46 of the cooktop plate 42. The cooktop plate 42 is arranged above the heating unit 38 in a mounted state. An item of cookware set down on the cooktop plate 42, for example the cooking pot 44, can be inductively heated by means of one or more of the induction heating elements 40 of the heating unit 38 of the household appliance 50. The cooktop plate 42 forms at least one high temperature region 24 having temperatures of up to 250 C. In an operating state, in which an item of cookware, for example the cooking pot 44, is set down on the set-down plate 42 and heated by means of the heating unit 38, a temperature of the surface 46 can be up to 250 C. in the high temperature region 24.

[0040] In the figures, in each case only one of the objects which is repeatedly present is provided with a reference sign.

[0041] The household appliance 50 has a household appliance apparatus 10. The household appliance apparatus 10 is configured as a cooktop apparatus and namely as an induction cooktop apparatus.

[0042] The household appliance apparatus 10 has at least one temperature sensor unit 12. The temperature sensor unit 12 is provided for the purpose of detecting incident infrared radiation (not shown) and converting it into a measurement signal (not shown). The household appliance apparatus 10 has a control unit 16 which is provided to determine at least one temperature parameter from the measurement signal. The temperature parameter characterizes a temperature of at least one item of cookware, for example the cooking pot 44, and/or the cooktop plate 42.

[0043] The temperature sensor unit 12 has at least one photodiode 14. The photodiode 14 is provided for the purpose of detecting incident infrared radiation and converting it into the measurement signal. In the present case, the photodiode 14 is integrated in the cooktop plate 42 and terminates flush with the surface 46 of the cooktop plate 42, and namely such that at least one cookware portion of an item of cookware, for example a pot base of the cooking pot 44, when set down on the cooktop plate 42, can be in contact with the photodiode 14 at least in some portions. The photodiode 14 is arranged in the high temperature region 24 which has temperatures of up to 250 C.

[0044] Alternatively, however, the photodiode 14 could be fully integrated in the cooktop plate 42 or arranged below the cooktop plate 42, wherein a region of the cooktop plate 42 above the photodiode 14 in these two cases, not shown here, would have to be configured to be at least partially transparent and permeable to infrared radiation, so that this can impinge on the photodiode 14.

[0045] The household appliance apparatus 10 has at least one amplifier unit 18. The amplifier unit 18 has at least one amplifier 20 (see FIG. 2) for amplifying the measurement signal. The amplifier unit 18 is arranged in a region 26 in which the temperatures thereof are reduced relative to the high temperature region 24. In the present case, a temperature in the region 26 is a maximum of 125 C. The region 26 is arranged below the cooktop plate 42 on an opposing side of the surface 46.

[0046] The temperature sensor unit 12 and the amplifier unit 18 are connected together via at least one electrical cable 28 (see FIG. 2). In the present case, the photodiode 14 and the amplifier 20 are connected together via the electrical cable 28. The electrical cable 28 is configured as a shielded cable, in order to reduce interference which could be produced in the operating state, in particular by the electromagnetic fields generated by the induction heating elements 40 for the inductive heating, on the transmission of the measurement signal from the photodiode 14 to the amplifier 20.

[0047] The household appliance apparatus 10 has a compensation unit 22. The compensation unit 22 is provided for at least partially compensating for temperature influences on the conversion and/or amplification of the measurement signal. In the present case, the compensation unit 22 is provided to compensate electrically for temperature influences on the conversion and/or amplification.

[0048] In the present case, the amplifier unit 18 and the compensation unit 22 are arranged on a common printed circuit board 32.

[0049] FIG. 2 shows a schematic electrical circuit diagram of the amplifier unit 18 and the compensation unit 22. The compensation unit 22 and the amplifier unit 18 are configured as discrete electrical switching circuits. The compensation unit 22 and the amplifier unit 18 are configured at least partially in one piece. In the present case, the compensation unit 22 is part of the amplifier unit 18.

[0050] The amplifier 20 of the amplifier unit 18 is configured as a transimpedance amplifier. The amplifier 18 has two inputs, and namely an inverting input 52 and a non-inverting input 54. The amplifier 18 has an output 56. The photodiode 14 is electrically conductively connected in the reverse direction to the inverting input 52 of the amplifier 20, and namely via the electrical cable 28. The amplifier 20 has a feedback resistor 58. The feedback resistor 58 is arranged electrically in parallel with the inverting input 52 and the output 56. The amplifier 20 has a feedback capacitor 34. The feedback capacitor 34 is arranged electrically in parallel with the feedback resistor 58. In the operating state, the feedback capacitor 34 represents a very low AC resistance for high-frequency electrical alternating currents and thus bridges the feedback resistor 58 so that high-frequency interference signals are not amplified by the amplifier 20.

[0051] The compensation unit 22 has at least one further amplifier 30 for at least partially compensating for temperature influences on the conversion and/or amplification of the measurement signal. The further amplifier 30 is configured as a transimpedance amplifier. The further amplifier 30 has two further inputs, and namely a further inverting input 60 and a further non-inverting input 62. The further amplifier 30 has a further output 64. The photodiode 14 is electrically conductively connected in the forward direction to the further inverting input 60 and namely by a shielded further electrical cable 48. The further amplifier 30 has a further feedback resistor 66. The further feedback resistor 66 is arranged electrically in parallel with the further inverting input 60 and the further output 64. The further amplifier 30 has a further feedback capacitor 36. The further feedback capacitor 36 is arranged electrically in parallel with the further feedback resistor 66. The non-inverting input 54 of the amplifier 20 and the further non-inverting input 62 of the further amplifier 30 are electrically conductively connected to one another.

[0052] The amplifier 20 and the further amplifier 30 are at least substantially structurally the same. In particular, the amplifier 20 and the further amplifier 30 have the same number of elements which in each case are substantially structurally the same. A corresponding element of the amplifier 30 exists for each element of the amplifier 20, wherein elements corresponding to one another in each case have substantially the same parameters, i.e. the same parameters with the exception of minimal manufacturing-related variations. For example, the feedback capacitor 34 of the amplifier 20 and the further feedback capacitor 36 of the further amplifier 30 in each case have at least substantially the same electrical capacitance. The amplifier 20 and the further amplifier 30 are part of a common symmetrical electrical switching circuit. In the present case, the amplifier 20 and the further amplifier 30 together with the photodiode 14 form the symmetrical electrical switching circuit and are arranged mirror-symmetrically to one another relative to the photodiode 14.

[0053] In the operating state of the household appliance apparatus 10, due to the internal photo effect the photodiode 14 converts incident infrared radiation into an input-side measurement signal in the form of a photocurrent. The photocurrent flows in the reverse direction to the inverting input 52 of the amplifier 20. The amplifier 20 in the operating state is operated in a parallel voltage negative feedback operation, wherein at least a part of the output voltage at the output 56 is returned via the feedback resistor 58 to the inverting input. An amplification factor of the amplifier 20 thus is characterized significantly by the value of the feedback resistor 58 and can be varied by a suitable choice of feedback resistor 58. An amplified output-side measurement signal, in the form of a voltage which is proportional to the photocurrent, can be tapped off between the output 56 of the amplifier 20 and the further output 64 of the further amplifier 30. The amplifier 20 can thus be regarded as a current-controlled voltage source.

[0054] In addition to the photocurrent, in the operating state the photodiode 14 generates a dark current, the value thereof increasing as the temperature rises. In an electrical equivalent circuit diagram (not shown) of the photodiode 14, the dark current and optionally further interference of the photodiode 14, for example a noise current, could be described by an equivalent resistor (not shown) which is connected in series to the photodiode 14. A voltage drop via this equivalent resistor is denoted as the input-side offset voltage. As the temperature rises, a value of the equivalent resistor falls and a value of the input-side offset voltage increases. The input-side offset voltage is present at the inverting input 52 and thus is amplified therewith. In order to compensate at least partially for this temperature influence on the measurement signal, which can be described by the input-side offset voltage, the compensation unit 22 has the further amplifier 30 which is operated in the operating state exactly as the amplifier 20 in the above-described parallel voltage negative feedback operation. The input-side offset voltage in the operating state is also present with the same value and a reverse sign at the further inverting input 60 and is amplified by the further amplifier 30. Since the photocurrent only flows in the reverse direction of the photodiode 14, it does not flow to the further inverting input 60. In the operating state, therefore, the further amplifier 30 only amplifies the input-side offset voltage but not the photocurrent. Since the amplifier 20 and the further amplifier 30 are at least substantially structurally the same, and as a result have at least substantially the same amplification factors, the input-side offset voltage is uniformly amplified by the amplifier 20 and the further amplifier 30. An electrically negatively amplified offset voltage is present at the output 56 of the amplifier 20 and an electrically positively amplified offset voltage is present at the further output 64 of the further amplifier 30, which mutually cancel one another out when the amplified output-side measurement signal between the two outputs 56, 64 is tapped off. The symmetrical amplifier circuit, shown in FIG. 2, consisting of the amplifier 20 and the further amplifier 30 thus has, at least in theory, an output-side offset voltage of zero for any temperatures. In addition to the above-described input-side offset voltage which is produced by the dark current of the photodiode 14, the elements of the amplifier 20 and the further amplifier 30, in particular the feedback resistor 58 and the further feedback resistor 66, also have a temperature dependence by which additional offset voltages are produced. Since a temperature profile of the region 26 is not completely uniform and the components of the amplifier 20 and the further amplifier 30 are not perfectly identical for production-related reasons, these additional offset voltages cannot be fully compensated by the compensation unit 22, however, as shown hereinafter in FIG. 3.

[0055] FIG. 3 shows a schematic diagram for illustrating temperature influences on the amplifier unit 18 and the compensation unit 22. A time is plotted in minutes on a horizonal scale 68. An offset voltage is plotted in volts on a left-hand vertical scale 70, wherein the left-hand vertical scale 70 ranges from 0 V to 0.015 V. An ambient temperature, in the region 26 in which the amplifier unit 18 and the compensation unit 22 are arranged, is plotted in degrees Celsius on a right-hand vertical scale 72, wherein a scale ranges from 0 C. to 150 C. A first curve 74 shows a path of the ambient temperature in the region 26. Over the time curve which is plotted on the horizontal scale 68 and which extends over a total of 7 hours, the ambient temperature rises in the region 26 from a starting value of ca. 20 C. to a maximum value of 125 C. A second curve 76 shows a first path of an offset voltage. For the measurement of the second curve 76, in each case a value of 1 G has been selected for the feedback resistor 58 and the further feedback resistor 66. A third curve 78 shows a further path of an offset voltage, wherein for the measurement of the third curve 78 in each case a value of 100 M has been selected for the feedback resistor 58 and the further feedback resistor 66. A fourth curve 80 shows a further path of an offset voltage at the output 56 of the amplifier 20, wherein for the measurement of the fourth curve 80 in each case a value of 10 M has been selected for the feedback resistor 58 and the further feedback resistor 66. It has been shown that the measured offset voltages are very low for all three curves 76, 78, 80, which is due to the partial compensation of the temperature influences by the compensation unit. For ambient temperatures of the region 26 of up to 75 C., the offset voltage is barely measurable and is below 0.01 V. The path of the second curve 76 initially rises slightly from an ambient temperature of 75 C. and more sharply from an ambient temperature of 100 C., wherein the offset voltage does not exceed a value of 0.015 V. The path of the third curve 78 rises slightly from an ambient temperature of 100 C. and reaches maximum values of ca. 0.03 V. The path of the fourth curve 80 indicates very small offset voltages below 0.01 V over the entire temperature range of the ambient temperature in the region 26.

[0056] FIG. 4 shows a schematic process flow diagram of a method for operating the household appliance apparatus 10. In the method, temperature influences on the conversion and/or amplification of the measurement signal are at least partially compensated. The method comprises at least two method steps. In a first method step 82 of the method, incident infrared radiation is converted by means of the photodiode 14 into the input-side measurement signal in the form of the photocurrent. In a second method step 84, the input-side measurement signal is amplified by the amplifier 20, as described above relative to FIG. 2. Temperature influences which occur during the conversion of the infrared radiation into the photocurrent and/or the amplification and which can be described as offset voltages, in the second method step 84 are at least partially compensated by means of the further amplifier 30 of the compensation unit 22, and namely as described above with reference to FIG. 2.

REFERENCE SIGNS

[0057] 10 Household appliance apparatus [0058] 12 Temperature sensor unit [0059] 14 Photodiode [0060] 16 Control unit [0061] 18 Amplifier unit [0062] 20 Amplifier [0063] 22 Compensation unit [0064] 24 High temperature region [0065] 26 Region [0066] 28 Electrical cable [0067] 30 Further amplifier [0068] 32 Printed circuit board [0069] 34 Feedback capacitor [0070] 36 Further feedback capacitor [0071] 38 Heating unit [0072] 40 Induction heating element [0073] 42 Cooktop plate [0074] 44 Cooktop [0075] 46 Surface [0076] 48 Further electrical cable [0077] 50 Household appliance [0078] 52 Inverting input [0079] 54 Non-inverting input [0080] 56 Output [0081] 58 Feedback resistor [0082] 60 Further inverting input [0083] 62 Further non-inverting input [0084] 64 Further output [0085] 66 Further feedback resistor [0086] 68 Horizontal scale [0087] 70 Left-hand vertical scale [0088] 72 Right-hand vertical scale [0089] 74 First curve [0090] 76 Second curve [0091] 78 Third curve [0092] 80 Fourth curve [0093] 82 First method step [0094] 84 Second method step