GB2102170A

GB2102170A - A residual heat display for an electric cooker

Info

Publication number: GB2102170A
Application number: GB08213459A
Authority: GB
Inventors: Dr Hartmut Dittrich; Arno Bauer
Original assignee: Diehl GmbH and Co
Current assignee: Diehl Verwaltungs Stiftung
Priority date: 1981-05-09
Filing date: 1982-05-10
Publication date: 1983-01-26
Also published as: GB2102170B; FR2505596A1; DE3118414A1; FR2505596B1; DE3118414C2

Abstract

A circuit arrangement (1) consists of a signal production circuit (2) producing a signal which is associated with the temperature of a hot-plate, and a comparator circuit (3) which compares the temperature signal with various presettable values which correspond to specific temperature settings of the hot-plate, and controls on at least one one-figure multisegment display arrangement (6) in such a way that for at least three different temperature ranges different symbols are representable with hot plates switched on or off. <IMAGE>

Description

SPECIFICATION A residual heat display for an electric cooker The invention relates to a residual heat display for an electric cooker, which display is capable of displaying that the residual heat in a heating element or elements of the cooker is above or below a threshold temperature value.

Residual heat displays for electric cookers are known more especially in the case of cookers having heating elements including glass-ceramics hot-plates. German Offenlegungsschrift No.

25 45 239 shows an electronic temperature regulator for heating elements, for example hot plates, in which a control-panel or keyboard is provided for the input of the desired power or temperature stage. Serving to display the controlling state of the input control-panel or keyboard is a seven-segment display which is controlled by way of a diode matrix. Moreover a zero key or a cut-off switch is provided on the control panel by which, after the respective heating element is switched off, the sevensegment display is coupled to a resistance sensor (which is in thermal communication with the hotplate) by way of an appropriate circuit arrangement.If now the temperature of the hotplate, after the power supply has been switched off, exceeds a specific threshold value, for example 45cm, then the seven-segment display is so controlled that it supplies a warning display. In this respect an "H" may be represented.

This arrangement thus serves exclusively to warn the user that, for example, a hot-plate is still so hot that, in the event of hand contact, there is a risk of injury. There is no other indication of how high the temperature of the hot-plate actually is after the power supply is cut-off.

Since, however, such a hot-plate can, after a cooking operation, be heated to a temperature higher than 2000C, it is possible to still utilise heat stored in the hot-plate. It is possible to utilise heat stored in other heating elements after the power supply has been switched off.

An object of the present invention is to provide a residual heat display which makes possible a deliberate utilisation of residual heat. In some embodiments circuit parts already present in an electric cooker may be used to this end.

Furthermore, the display of the residual heat should be clearly distinguishable from the operational or control display of the electric cooker.

According to the present invention there is provided a residual heat display for an electric cooker having one or more heating elements, for example hot-plates, and one or more sevensegment display arrangements for displaying the temperature setting or state of the heating element or elements with the element or elements switched on and/or for displaying the on/off switching state of said element or elements, and the residual heat display comprising a two-stage display of temperature of the element or elements with the element or elements switched off, and having a circuit arrangement for ascertaining a threshold temperature of the or each element, characterised in that the circuit arrangement consists of a signal production circuit and a comparator circuit which is capable of comparing several values indicative of temperature and an electrical signal, associated with the temperature of the heating element or elements is producible by the signal production circuit when the element or elements are switched on and when the element or elements are switched off, which signal can be compared by the comparator circuit with predeterminable values corresponding to the temperature stages to be displayed, and in that the residual heat display comprises one or more at least one-figure multi-segment display arrangements which are utilisable as a function of the temperature of the heating element or elements with the element or elements switched on and off, and for at least three different temperature ranges different symbols are displayable on the respective multisegment display arrangement.

Further advantages can be gathered from the sub-claims.

Thus, for example, the circuit arrangement can in accordance with the invention be combined with the control arrangement for heating the heating element or elements so that, for example, a store arrangement and a selection interface are jointly usable for controlling the multi-segment display arrangement.

Furthermore, it is possible to develop the residual heat display in such a way that the symbols displayed with the power supply switched off are identical with those which are associated with the respectively selected power or temperature stage with heating elements switched on. For better differentiation, also for the residual heat display with heating elements switched off different symbols can be used than those which are used with heating elements switched on.

Furthermore, it is possible to provide twocolour display elements, so that different colours can be used for the operational or setting display and for the residual heat display.

Further according to the invention there is provided a residual heat display for displaying an indication of at least three values of residual heat present in at least one heating element, for example a hot-plate of cooking apparatus, the display comprising an multi-segment display arrangement in respect of the or each heating element, said at least three values of residual heat being displayable on the or on the respective multi-segment display arrangement by selected combinations of segments displayed, said combinations indicating that the temperature of said at least one heating element is below and/or above threshold values of temperature and/or within a specific temperature range, said selected combinations of segments displayed being by way of a circuit arrangement of the display having a comparator circuit which in use is capable of comparing the value of an electrical signal indicative of the amount of residual heat in said at least one heating element, fed to the comparator by way of a temperature sensor or sensors of the display, arranged in use adjacent the or each heating element, with preset temperature values to control which combination of segments is selected to display different values of residual heat.

Two embodiments of a residual heat display in accordance with the present invention will now be described, by way of example only, with reference to the accompanying illustrative schematic drawings, in which, Figure 1 shows a seven-segment display arrangement of a preferred exemplary embodiment of a residual heat display; Figure 2 shows a 1 6-segment display arrangement of a further preferred exemplary embodiment of a residual heat display; Figure 3 shows a block diagram of a circuit arrangement useable with either display arrangement shown in Figures 1 and 2; Figure 4 shows a modified block diagram of a circuit arrangement useable with either display arrangement as shown in Figures 1 and 2 and which is combined with a power control for heating element or elements of an electric cooker.

Usually, during cooking on a manuallyoperable electric cooker, the power supply remains switched on right until the end or right until shortly before the end of the cooking operation. Modern cookers, more especially those having glass-ceramics cooking surfaces, still have a considerable heat capacity, so that the cooking surface has, after the end of the cooking operation, a considerable amount of residual heat which is generally given off uselessly to the environment. Similarly, cooking ovens, especially in the case of those having radiation heating, have a great amount of stored heat.

In order to save on energy consumption, it now appears meaningful to utilise this residual heat. In order to do this it is necessary to have enough information regarding the existing amount of available heat; or for estimating this amount of heat, information regarding the temperature of the hot-plate or hot-plates or of the oven after the power supply has been switched-off.

For the residual heat display, preferably, an already existing display arrangement is used which in the case of an electric cooker in operation displays either the switched-on power setting or stage, or the temperature setting or stage associated with this power stage. Upon use of a seven-segment display, this can be, for example the settings or stages 1 to 9. Now, similarly the numerals 1 to 9 can be utilisd for displaying residual heat, in which respect the display of the residual heat of, for example, a hot plate after it is switched-off is so associated with the individual temperature stages that it corresponds to the temperatures achievable in each case (temperature level set) in the individual power stages switched-on.

Shown in Figure 1 is a residual heat display with a seven-segment display arrangement. In this respect, of the seven-segment display arrangement. In this respect, of the sevensegment display shown schematically in Figure 1 a, only the three horizontal bars are used.

Figures 1 b, c and d show the representation of different symbols by means of three, two and one bars. Thus a four-stage residual heat display can be realised since a no-bar combination may be selectable. Associated with the three display stages in accordance with Figures 1 b, c and dare three terms indicative of three temperature settings which are conventionally 'High Heat", "Medium Heat" ("Simmering"), and "Low Heat".

The fourth stage, for example, for "cold" or "hotplate off" can be displayed, for example, as shown in Figures 1 e, or 1 f respectively, by means of a zero or capital letter "A".

Shown in Figure 2 is a 1 6-segment display arrangement of a further embodiment of a residual heat display.

Figure 2a shows schematically a conventional 1 6-segment display. With such a display arrangement, in a very simple manner also the numbers 10 to 1 9 can be represented, that is to say the display of more than 9 power settings or stages with the power supply on is possible. The right-hand half of the 1 6-segment display is used like a seven-segment display, and a "1" is representable by the two vertical bars arranged to the left thereof. The number 12 is shown as an example in Figure 2b.

Also the representation of letters is possible with such a 16-segment display arrangement. In the case of a four-stage residual heat display, as described with reference to Figure 1, the following letters can be displayed in accordance with the said temperature stages: F for FORTKOCHEN (High Heat) (Figure 2c) G for GAREN (simmer) (Figure 2d) W for WARMALTEN (low heat) (Figure 2e) K for KALT (cold or off) (Figure 2f).

Within the scope of the present invention, a display of the residual heat with more than four stages, and with other symbols, is possible.

In order to aid distinction, for a user, between, on the one hand, the display of the power or temperature stages selected, for example, of a hot-plate when switched on and, on the other hand, the residual heat display, a display arrangement can be chosen which displays two different colours. For example, with a heating element switched on, the colour "red" can be used and, with the heating element switched off, in other words for the display of the residual heat, the colour "yellow" can be used. Furthermore, it is possible to have the display arrangements work in two different kinds of operation. As an example, when the heating elements are on the display can be permanently in operation, and the residual heat displayed intermittently, in other words, for example, a blinking operation.Furthermore, it is possible, with intermittent operation of the display arrangement, to display alternately the residual heat and a symbol for "switched off".

This is, preferably, meaningful when the same symbols are used for the display of the temperature settings or stages, or respectively switching stages, with the heating elements switched on and also for the residual heat display.

Shown in block diagram in Figure 3 is a circuit arrangement 1 for ascertaining the temperature of, for example, a hot-plate. The circuit arrangement 1 consists of a signal production circuit 2 and a comparator circuit 3 which is capable of comparing several values.

The signal production circuit 2 receives, by way of one or more information lines 4, information regarding the temperature of the hot-plate. In the simplest case, in this respect a resistance sensor coupled to the hot-plate is connected to the signal production circuit 2. The signal production circuit 2 produces an electrical signal which is associated with the temperature of the hot-plate and which is fed to the comparator circuit 3 by way of one or more signal lines 5. The comparator circuit 3 compares this signal, with various presettable or predeterminable values which are associated with the selected residual heat stages, and controls accordingly a display arrangement 6 for displaying the various residual heat stages.

A simple circuit arrangement 1 in accordance with the invention for determining the temperature of the hot-plate consists of a Wheatstone Bridge circuit, and one branch thereof may be formed, for example, by a heat conductor used as a temperature sensor. The electrical signal tapped at the diagonal branch of the bridge circuit is fed to the comparator circuit 3 which, in this example, is composed of several Schmitt trigger circuits connected in parallel, the switch-over points of which are set for different suitable values. The display arrangement 6 consists, for example of a seven-segment display element which is so connected to the outputs of the Schmitt trigger circuits by way of a diode network that, for example, depending on the temperature of the hot-plate, three, two or one horizontal bars are displayed.If the temperature of the hot-plate drops below, for example 450C, then the display arrangement 6 is completely switched off and no bars may be displayed.

Shown in Figure 4 is a further block diagram of the circuit arrangement 1 which is combined with a circuit for controlling heating arrangements 7 for heating the hot-plates by way of a central unit 8. The circuit arrangement 1 consists of the signal production circuit 2, the comparator circuit 3 and an interface (SCHNITTSTELLE) 9 for controlling the display arrangement 6. Furthermore, the central unit 8 contains a control arrangement 10 and a store arrangement 11, and the control arrangement 10 is connected to a manuallyactuable operating arrangement 1 2.

By means of the operating arrangement 12 through an input line 13 the control arrangement 10 is set to a specific power or temperature setting or stage. The control arrangement 10 is connected by way of first command and data lines 14 to the store arrangement 1 1, which stores the data, associated with the set power or temperature stage, regarding cooking duration and so forth. The control arrangement 10 controls the power supply for the heating arrangements in accordance with the set switching stage and is connected by way of a first display line 1 5 to the interface 9 for controlling the display arrangement 6.

The signal production stage 2 receives, by way of the information lines 4, data regarding the temperature state of the hot-plates associated with the respective heating arrangements 7, and produces an electrical signal which is associated with this temperature and which is fed by way of the signal lines 5 to the comparator circuit 3. The comparator circuit 3 is connected by way of second command and data lines 1 6 to the store arrangement 11. The comparator circuit 3 compares the signal, associated with the hotplate temperature, with the predeterminable values which are stored in the store arrangement.

Moreover, the comparator circuit 3 is connected by way of a second display line 17 to the interface 9 for controlling the display arrangement 6.

Depending on the number of predetermined comparison values and the temperature of the hot-plate, the display arrangement 6 is controlled in such a way, by way of the interface 9, that the various symbols, already described above, are represented to display the various residual heat stages.

Within the scope of the invention it is also possible to use, as central unit 8, a microprocessor with an appropriate periphery, or a one-chip microcomputer. Systems exist (for example Texas-lnstruments, TMS 1000) which can be connected directly to a control panel or keyboard used as operating arrangement 12.

Further inputs can serve to take over information regarding the thermal state of the hot-plate. To control the power supply to the heating arrangements 7, a suitable interface circuit, for example relays or thyristors, is necessary. Upon use for example of fluorescent displays as display arrangement 6, a direct control by the microprocessor is possible, and upon use of other display elements a conventional driver circuit may be necessary.

Claims

1. A residual heat display for an electric cooker having one or more heating elements, for example hot-plates, and one or more seven-segment display arrangements for displaying the temperature setting or stage of the heating element or elements with the element or elements switched on and/or for displaying the on/off switching state of said element or elements and the residual heat display comprising a twostage display of temperature of the element or elements with the element or elements switched off, and having a circuit arrangement for ascertaining a threshold temperature of the or each element, characterised in that the circuit arrangement consists of a signal production circuit and a comparator circuit which is capable of comparing several values indicative of temperature, and an electrical signal associated with the temperature of the heating element or elements is producible by the signal production circuit when the element or elements are switched on and when the element or elements are switched off, which signal can be compared by the comparator circuit with predeterminable values corresponding to the temperature stages to be displayed, and in that the residual heat display comprises one or more at least one-figure multi-segment display arrangements which are utilisable as a function of the temperature of the heating element or elements with the element or elements switched on and off, and for at least three different temperature ranges different symbols are displayable on the respective multisegment display arranqement.

2. A display as claimed in Claim 1, in which the circuit arrangement is combined with a control arrangement of the heating element or elements; an information store arrangement and a common interface between the comparator circuit and control arrangement is provided for the control of the multi-segment display arrangement or arrangements of the residual heat display.

3. A display as claimed in Claim 2, in which the store arrangement, in use, stores the predeterminable values for the comparator circuit, and stores data according to which the control arrangement controls the power fed to the heating element or elements, as a function of the selected power and/or temperature setting or stage.

4. A display as claimed in any one of Claims 1 to 3, in which the display of the temperature of the heating element or elements when said element or elements are switched off corresponds to that display which is associated with the power or temperature setting or stage with the heating element or elements switched on.

5. A residual heat display as claimed in any one of Claims 1 to 4, in which cross-bars of the multisegment display arrangement or arrangements are used for the display of the temperature of the heating element or elements when switched off to display the temperature ranges exclusively, in which respect the number of cross-bars shown decreases with decreasing temperature.

6. A display as claimed in any one of Claims 1 to 5, in which the or each multi-segment display arrangement can display, depending on the operating setting or state "On/Off" of the heating element or elements, different types of operation.

7. A display as claimed in Claim 6, in which the or each multi-segment display arrangement in the one operating setting or state of the heating element or elements is permanently in operation, and in the other operating state is intermittently in operation.

8. A display as claimed in any one of Claims 1 to 7, in which the multi-segment display arrangement or arrangements, with the heating element or elements switched off, are intermittently in operation, and in which between the display of the symbols corresponding to the temperature a symbol for the setting or state "switched off" is displayable.

9. A display as claimed in any one of Claims 1 to 8, in which the multi-segment display arrangement or arrangements can, depending on the operating setting or state of the element or elements, be switched over to different colours.

1 0. A residual heat display for displaying an indication of at least three values of residual heat present in at least one heating element, for example a hot-plate of cooking apparatus, the display comprising a multi-segment display arrangement in respect of the or each heating element, said at least three values of residual heat being displayable on the or on the respective multi-segment display arrangement by selected combinations of segments displayed, said combinations indicating that the temperature of said at least one heating element is below and/or above threshold values of and/or within a specific temperature range, said selected combinations of segments displayed being by way of a circuit arrangement of the display having a comparator circuit which in use is capable of comparing the value of an electrical signal indicative of the amount of residual heat in said at least one heating element, fed to the comparator by way of a temperature sensor or sensors of the display, arranged in use adjacent the or each heating element, with preset temperature values to control which combination of segments is selected to display different values of residual heat.

11. A display as claimed in Claim 10, in which the or each multi-segment display arrangement is adapted to display the temperature setting and/or on/off setting of the heating element or elements.

12. A display as claimed in Claim 10 or Claim 11, in which the residual heat of a heating element or elements is displayable after said element or elements are switched off.

13. A display as claimed in Claim 12, in which the residual heat is displayed intermittently, a symbol to indicate that the respective element is switched-off being displayable during said intermittent operation.

14. A display as claimed in any one of Claims 10 to 13, in which the residual heat of a heating element or elements is displayable while said element or elements are switched on.

1 5. A display as claimed in Claim 14 when dependent from Claim 11 or any claim dependent therefrom in which the display of residual heat with the heating element or elements switched on is intermittent and the temperature setting and/or on/off setting of the heating element or elements is displayable during said intermittent operation.

1 6. A residual heat display substantially as herein described and illustrated with reference to Figures 1, 3 and 4 of the accompanying drawings.

1 7. A residual heat display substantially as herein described and illustrated with reference to Figures 2, 3 and 4 of the accompanying drawings.

1 8. An electric cooker including one or more residual heat displays as claimed in any one of the preceding claims.