GB2407401A

GB2407401A - Mains Controlled Timer.

Info

Publication number: GB2407401A
Application number: GB0418707A
Authority: GB
Inventors: Bernd Raunig; Jurgen Hellwig; Werner Arnold
Original assignee: Diehl AKO Stiftung and Co KG
Current assignee: Diehl AKO Stiftung and Co KG
Priority date: 2003-10-23
Filing date: 2004-08-21
Publication date: 2005-04-27
Also published as: GB0418707D0

Abstract

An electronic timer (10) is proposed which is supplied with a mains voltage (U) so as to operate on the basis of the rated frequency (fn) of the mains, and which is connected to control means (12) which include an internal clock generator (14). The control means (12) include determination means which detect when the available mains frequency (f) does not correspond to the rated frequency (fn) (frequency disturbance). In the event of such a frequency disturbance being detected by the determination means, the control means deliver a clock signal from the internal clock generator (14) so as to be able to bypass said frequency disturbance. The electronic timer (10) can be used for example in electronic domestic appliances, such as electric cookers, ovens, microwave ovens or the like.

Description

Mains-controlled Timer The present invention relates to an electronic

timer according to the preamble of Claim 1 as well as to a method of controlling an electronic timer according to the preamble of Claim 7.

Electronic timers of this type can be used in many kinds of electronic domestic appliance, such as for example cookers, microwave ovens, dishwashers etc., but can also be used in other electronic devices, such as alarm clocks or the like.

Thus DE 43 11 935 C2, for example, discloses a domestic appliance, in particular an electric cooker or oven, in which the timer can be disconnected from the electric mains for purposes of reducing power consumption and can be reconnected as required by the user. To eliminate the need to reset the timer to the actual time of day after its reconnection, the timer takes the form of a radio-controlled timer.

Furthermore DE 198 04 399 C2 describes, inter alla, an electric domestic appliance having a timer powered by at least one solar cell. In addition, the domestic appliance also has an accumulator so that, when it is disconnected from the household electric mains, the timer and other electric components can be powered by the solar cell and/or by the accumulator in order, even without the mains power supply, to enable the domestic appliance to react visibly when the operator sets it.

t)E 00 689 Al discloses an electric domestic appliance having a timer as well as t., f.'Ctl: " ergy storage battery, in whici1 case, ir I' . c.ent. disconnection or failure of the mains voltage, the timer automatically remains connected to the electric energy storage battery so as to carry on producing time-of-day signals, so that the time display connected to the timer automatically displays the correct time of day when the mains voltage is switched on again.

The present invention is based on the objective of providing a mainspowered electronic timer, in which negative effects as a result of frequency disturbances of the mains voltage can be prevented or suppressed.

This objective is achieved by an electronic timer having the features specified in Claim 1. Advantageous embodiments and developments of the timer are the subject matter of dependent claims 2 to 6.

The electronic timer, which is supplied with mains voltage so as to operate on the basis of the rated frequency of the mains and is connected to control means including an internal clock generator, is characterized according to the present invention in that the control means include determination means which recognize when the mains frequency supplied by the mains does not correspond to the rated frequency (frequency disturbance), and in that, in the event of frequency disturbance being detected by the determination means, the control means provide a clock signal from the internal clock generator. With this electronic timer, a possibly faulty operation, as a result of frequency disturbance as described above, is prevented or suppressed, since such frequency disturbance can be detected by the control means and in this case a clock signal from the internal clock generator is triggered, the frequency of which substantially corresponds to that of a signal produced by the timer when the rated frequency of the mains is available.

In one embodiment of the invention, in the event of such frequency disturbance being detected, the control means prevent all other functions of the appliance in which the timer and control means are incorporated.

In a preferred working example of the invention, the control means also include comparison means which compare a signal with mains fiequency applied to first input terminal with a time schedule produced by the internal clock generator and deliver the result of this comparison to the determination means so as to detect any frequency disturbance. In an alternative embodiment, the control means further include comparison means which compare a signal with mains frequency applied to a first input terminal with a signal with rated frequency applied to a second input terminal, the noise of the latter signal being suppressed by means of a noise- suppression circuit, and deliver the result of this comparison to the detemmination means.

The timer according to the present invention can be a timer of an electronic domestic appliance, such as for example an electric cooker, an oven, a microwave oven, a dishwasher or the like. However, the timer may also be a timer for example of an alarm clock.

According to a second aspect of the invention, the above objective is achieved by a method of controlling an electronic timer, said method having the features of Claim 7.

Advantageous embodiments and developments of the method according to the invention are specified in sub-claims 8 to 10.

The method of controlling an electronic timer supplied with mains voltage, so as to operate on the basis of the rated frequency of the mains, comprises the procedural steps of detecting when the available mains frequency does not correspond to the rated frequency of the mains (frequency disturbance) and, in the event of a frequency disturbance being detected, delivering an internal clock signal.

An instance of frequency disturbance can be detected by a comparison of the available mains frequency with an internal time schedule or alternatively by a comparison of the available mains frequency with a hardware noise-suppressed signal of the mains voltage.

The above as well as additional features and advantages of the present invention will become clearer on reading the following description of a preferred working example and refernng to the attached drawings which are as follows: Fig. 1 is a block diagram of an electronic domestic appliance fitted with a timer according to the present invention; and Fig. 2 is a flow diagram for purposes of illustrating the method according to the invention of controlling the electronic timer of Fig. 1.

Fig. 1 shows a block diagram of an electronic domestic appliance, such as for example an oven, an electric cooker, a microwave oven, a dishwasher or the like, in which a timer according to the present invention is incorporated. With the aid of Fig. 2, the method of controlling this timer according to the invention is then described in more detail.

The electronic domestic appliance comprises one or more consumers 30 which, according to the type of electronic domestic appliance, can for instance be a microwave generator, an induction coil of a hotplate, or the like. The consumer 30 is activated by a power unit 28. When the main switch 18 is switched on, this power unit 28 is supplied via a power supply 16 with a mains voltage U of the mains frequency f, which should generally correspond to the rated frequency fin of the mains. Moreover the power unit 28 is activated by way of control means 12 and a timer 10 so as to control the consumer 30 of the electronic domestic appliance according to the user's requirements and according to pre-stored programmes of the control means 12.

Apart from supplying the power unit 28, the power supply 16 also supplies the timer 10, control means 12, various control elements 22 and a display unit 24 of the domestic appliance with the mains voltage U. Moreover, the timer 10 operates on the basis of the mains frequency f supplied to it or, ideally, the rated frequency fin of the mains, more specifically the clock signal made available by the timer 10 to the power unit 28 and to the control means 12 is mains synchronous. At this point, mention should be made of the fact that the timer 10 can be a component integrated into the control means 12 as well as a separate component of the electronic domestic appliance.

Furthermore the eont''l r. ,a is 12 are connected to control elements 22 so as control the power unit 28 in accordance with a programme set by the user using the control elements 22. The control means 12 are also connected to the display unit 24 so as to control the corresponding display. Moreover an energy storage device 26, for example an accumulator or a lifetime battery, can be provided which, in the event of a mains failure, can supply the control means 12 with energy for a certain period of time and which also ensures the storage of the pre-stored programmes of the control means 12 independently ofthe mains supply.

An internal clock generator 14 is also integrated into the control means 12. In principle this internal clock generator 14 can, however, also be provided as a component which is separate from the control means 12. This internal clock generator 14 provides, as required, an internal clock signal which has a frequency which substantially corresponds to that of the clock signal produced by the timer 10 when the rated frequency fin of the mains is available.

The mains voltage U is supplied via the power supply 16 to a first input terminal 15a and to a second input terminal 15b of the control means 12. The second input temminal 15b of the control means 12 is coupled with a noise-suppression circuit (not represented) which suppresses the noise of the applied signal with mains frequency f so as to produce a hardware noise-suppressed signal with rated frequency En of the mains voltage U. Moreover the control means 12 include comparison means (not represented), which compare the signal with mains frequency f applied to the first input terminal 15a and the hardware noise-suppressed signal with rated frequency fin, which is applied to the second input terminal 15b and is noise-suppressed by means of the noise-suppression circuit, and deliver the result of this comparison to determination means (not represented). Based on the result of the comparison, the detemmination means detect whether or not the mains frequency f made available from the mains U corresponds to the rated frequency fin (i.e. whether there is any frequency disturbance). Moreover the control means 12 naturally also detect whether a mains voltage U is actually present.

In an alternative embodiment, which is not represented, the control means 12 may also have only the first input terminal 15a, to which a signal of the mains voltage U with mains frequency is applied, and the second input temminal 1 5b can be Jispensed with. In this case, the comparison means (not represented) compare the signal with mains frequency f applied to the first input temminal 15a with an internal timing or clock schedule of the control means 12, which is produced by the internal clock generator 14, and deliver the result of this comparison to the determination means (not represented). Whereas with this variant the second input terminal 1 5b and the noise suppression circuit can be dispensed with, as a result of which the configuration of the control means 12 is simplified, with the first alternative specified above the result of the comparison is more reliable, since the hardware noise-suppressed signal of the second input terminal 1 5b actually corresponds to the rated frequency fin of the mains.

The mode of operation of the control means 12 is described in greater detail below with the aid of the flow diagram in Fig. 2.

First of all, in step S10, it is checked whether a mains voltage U is actually present. If not, in step S12, the mains failure is processed in a way known per se, i.e. the loads are switched off, in which case the control means 12 can continue working for a short time via the integrated energy storage device. The control system then goes back to the beginning again with the checking of step S10.

If, in step S10, the presence of a mains voltage U has been detected, in step S14 it is checked by means of the above-described comparison means and determination means of the control means 12, as specified above according to the first or second alternative, whether or not the available mains frequency f of the mains voltage U corresponds to the rated frequency En. If the available mains frequency f corresponds to the rated frequency En, then the control means 12 carries on working in normal operation (step S16). If, however, there is a frequency disturbance, i.e. the available mains frequency f does not correspond to the rated frequency fn of the mains, the control moves on to step S18.

In step S18, the control means 12 provide an internal clock signal produced by the internal clock generator 14, the frequency of which substantially corresponds to that of a signal produced by the timer 10 when mains voltage U with rated frequency En is applied. (All additional functions can in this case be prevented or interrupted by the control means 12.) Then the control system goes back again to start once more with step S10.

The above-described frequency disturbances of the mains voltage U are generally only of short duration, so that with the method according to the invention such a frequency disturbance can be bypassed and during this short period of time a corresponding clock signal can be made available by the internal clock generator 14, so that the domestic appliance or the like carries on working with the correct clock pulse according to the rated frequency In of the mains. Thus bypassing of short- term frequency disturbances of the mains of the type described above can be accomplished easily and with a simple configuration of the control means and timer.

List of Reference Numerals Timer 12 Control means 14 Intemal clock generator 1 5a First input temminal I Sb Second input terminal 16 Power supply 1 8 Switch Mains supply 22 Control elements 24 Display unit 26 Energy storage device 28 Power unit Consumer U Mains voltage f Mains frequency fin Rated frequency

Claims

Patent Claims 1. An electronic timer (10), which is supplied with a mains

voltage (U) so as to operate on the basis of the rated frequency (fin) of the mains and which is connected to control means (12) which include an internal clock generator (14), characterized in that the control means (12) include determination means, which detect when the available mains frequency (f) does not correspond to the rated frequency (fn) (frequency disturbance), and in that, in the event of a frequency disturbance being detected by the detemmination means, the control means (12) deliver a clock signal from the internal clock generator (14).
2. A timer according to Claim 1, characterized in that, in the event of a frequency disturbance being detected, the control means (12) prevent all other functions.
3. A timer according to Claim 1 or 2, characterized in that the control means (12) further include comparison means which compare a signal with mains frequency (f) applied to a first input terminal (15a) with a time schedule produced by the internal clock generator (14), and deliver the result of this comparison to the determination means.
4. A timer according to Claim 1 or 2, characterized in that the control means (12) further include comparison means which con,r:..< a signal with mains frequency (f) applied to a first input terminal (15a) with a signal with rated frequency (fn) which is applied to a second input terminal (15b) and is noise-suppressed by means of a noise-suppression circuit, and deliver the result of this comparison to the determination means.
5. A timer according to one of Claims I to 4, characterized in that the timer (10) is also integrated into the control means (12).
6. A timer according to one of Claims 1 to 5, characterized in that the timer (10) is a timer of an electronic domestic appliance.
7. A method of controlling an electronic timer (10), which is supplied with a mains voltage (U), so as to operate on the basis of the rated frequency (fin) of the mains, characterized by the following procedural steps: detecting when the available mains frequency (f) does not correspond to the rated frequency (fin) (frequency disturbance) and, in the event of a frequency disturbance being detected, delivering an internal clock signal.
8. A method according to Claim 7, characterized in that, in the event of a frequency disturbance being detected, all other functions are prevented.
9. A method according to Claim 7 or 8, characterized in that an instance of frequency disturbance is detected by a comparison of the available mains frequency (f) with an internal time schedule.
10. A method according to Claim 7 or 8, characterized in that an instance of frequency disturbance is detected by a comparison of the available mains frequency (f) with a hardware noise-suppressed signal of the mains voltage.
11. An electronic timer as substantially described herein with reference to figure 1.
12. A method of controlling an electronic timer as substantially described herein with reference to figure 2.