WO2006061633A1

WO2006061633A1 - Electric toasters

Info

Publication number: WO2006061633A1
Application number: PCT/GB2005/004737
Authority: WO
Inventors: Leslie Alexander Gort-Barten; Brian Milton
Original assignee: Dualit Limited
Priority date: 2004-12-10
Filing date: 2005-12-09
Publication date: 2006-06-15
Also published as: AU2005313103A1; GB0427097D0; EP1830686A1; GB2420966A; GB2420966B

Abstract

An electric toaster having heating elements connectable to an electrical power supply includes a toast colour selection means for setting a selected time period for a toasting cycle, defrost means selectable when toasting items from frozen, and control means responsive to the toast colour selection means and the defrost means. The control means is operable when the defrost means is selected sequentially to cause power to flow to the heating elements for a first period of time, to discontinue or reduce the power flowing to the heating elements for a second period of time, and to restore power to the heating elements for a period of time set by the toast colour selection means.

Description

ELECTRIC TOASTERS

This invention relates to electric toasters and more especially to such toasters for toasting bakery products such as slices of bread, sandwiches, bread buns, teacakes, bagels, crumpets and baps.

Toasters commonly have radiant heating elements which are arranged to be set a short distance from one or both sides of the food product to be toasted, the degree or colour of toasting being determined by the length of time during which the heating elements are energised. A "toast colour selection" setting control is conventionally provided for selecting a time period for a toasting cycle. For example a selected time period is typically selectable within the range 5 seconds to 240 seconds.

Typical of such toasters are those disclosed in our British Patents 2289210B and 2318502B. The toasters disclosed in these Patents provide relatively consistent toasting of bakery and other products by adding several boost periods to the period set by the toast colour selection control if the toaster has not been used for predetermined elapsed intervals of time.

Electric toasters are frequently used to toast frozen bakery products, for example slices of bread taken straight from a freezer. Many electric toasters have a control setting for such occasions which effectively extends the toasting cycle by, for example, 30 seconds. This simply ensures that a bread slice is more appropriately coloured when ejected from the toaster. Such items do, however, lack the evenness of toasting and quality achieved when toasting from fresh.

The Applicant has discovered that the evenness of toasting and quality of a product toasted from frozen can be improved if the toasting cycle is interrupted after an initial powered defrosting period to ensure that the product is fully defrosted before the toasting cycle is restarted and completed. One reason for the improvements achieved is that the interruption in the toasting cycle ensures that the temperature profile across the thickness, height and width of the previously frozen item is generally constant, or substantially so before operation of the toasting cycle and before any browning of the product surfaces occurs.

One object of this invention is, therefore, to provide an electric toaster having a de-frost function which enables a product to reach a relatively even temperature throughout its surface area and thickness following an initial heating period and before full toasting of the product.

In accordance with the present invention, there is provided an electric toaster having heating elements connectable to an electrical power supply, toast colour selection means for setting a selected time period for a toasting cycle, defrost means selectable when toasting items from frozen, and control means responsive to the toast colour selection means and the defrost means, the control means being operable when the defrost means is selected sequentially to cause power to flow to the heating elements for a first period of time, to discontinue or reduce the power flowing to the heating elements for a second period of time, and to restore power to the heating elements for a period of time set by the toast colour selection means.

In another aspect, the invention provides an electric toaster having heating elements connectable to a source of electricity, the toaster including inter alia defrost means for use when toasting food items from frozen, the defrost means, when selected, operating sequentially to cause power to pass to the heating elements for a first period of time, on completion of the first time period to prevent power to pass to the heating elements for a second period of time, and on completion of the second time period to cause power to pass to the heating elements for completion of a toasting cycle. The first period of time is preferably between 20 and 40 seconds, typically 30 seconds. The second period of time is preferably between 15 and 30 seconds, typically 20 seconds.

In a preferred embodiment, the toaster includes a browning control switch operable to select any one of a multiplicity of time-dependent settings. Typically, ten such settings are provided. The toaster may comprise a plurality of toasting slots and a toasting slot selector switch operable to cause power to flow to only one such slot, more than one such slot or all such slots.

One embodiment of an electric toaster in accordance with the invention, will now be described, by way of example only, with reference to the accompanying drawings of which:-

Figure 1 is a side view of a toaster incorporating the present invention; and

Figure 2 is a view to an enlarged scale of a detail of the toaster shown in Figure 1.

The illustrated toaster is of a kind commonly used in domestic or commercial establishments and is provided with a main body casing 1 which houses conventional electrical heating elements positioned on each side of toasting slots 3 formed in the upper surface of the casing. The heating elements are divided into banks which can be either separately or collectively powered thereby enabling the toaster to be operated in a single slot or multi-slot mode. A lifting mechanism operated by a lever 4 is provided to enable slices of bread located in the slots to be lowered into or lifted from the casing interior. Located within a compartment 5 at one end of the casing is an electronic circuit connectable to a source of mains electricity through a conventional lead and plug (not shown). The circuit operates to transmit power to the electrical heating elements and operation of the circuit is controlled through a micro chip or like component as will be described below.

Positioned on the outer face of the compartment 5 is a browning control knob 6 rotatable to select any one of a multiplicity of time- dependent settings. As shown, there are ten such settings. Once a preferred degree of browning has been established, the control knob 6 can be left in the preferred setting for future toasting cycles. Also positioned on the outer face of the compartment 5 is a rotatable toasting slot selector switch 7 by means of which the toaster can be operated using only one, two or all three toasting slots. A position marker 8 is positioned above the slot selector switch 7 and an LED display 9 is positioned above the browning control knob 6 which either lights up or changes colour when the toaster is in use.

A defrost button 11 is provided for use when a frozen food item (e.g. a slice of bread direct from a freezer) is to be toasted. Operation of button 10 enables the micro-chip controller to cause power to flow to the selected heating elements for a set period of, say, 30 seconds to effect partial defrosting of the frozen item without causing browning of the exposed surfaces of the bread slice. The controller then switches off power to the elements for a preset period of, for example, 20 seconds to enable defrosting to be completed. On completion of this time period the controller operates to cause power to flow once more to the heating elements for a time period dictated by the setting selected for the browning control knob 6. Through this operation the temperature profile across the thickness, height and width of the bread slice after the initial defrost and resting time is generally constant before initiation of the selected toasting cycle. Finally, a start button 11 is positioned alongside the defrost button for initiating a conventional toasting cycle. For a toasting cycle including the defrost function, depression of the defrost button 11 initiates the required toasting cycle.

The electronic circuit (not shown) housed within the compartment 5 is subject to the settings selected through the slot selection switch 7 and the browning control knob 6, and operation of the defrost button 11 or start button 12. This circuit acts as or includes a control to ensure effective operation of the described toaster.

In addition the circuit (which operates at low voltage via the main power supply) may include a timing circuit including a time booster sub circuit which allows the time selected by the toast colour selection means to be increased by a time boost period. Thus, the timing circuit may be arranged to measure the elapsed time since a previous toasting cycle. In this case, the timing circuit supplies a signal to the microchip and the microchip is arranged to boost the current cycle time period by a time boost period which is added to the selected time period by the toast colour selection setting.

The circuit may also include a thermistor arranged to measure the temperature within the casing of the toasting machine. If the temperature exceeds a predetermined temperature, preferably above 3O⁰C, for example 32⁰C, the thermistor supplies a signal to the microchip and the microchip cancels any boost period which would otherwise be added. This ensures that if the toasting machine is unplugged from one power source and then reconnected to a power source whilst still hot, the current toasting time cycle will not be increased above the selected time period by any boost period. Thus, the time booster sub circuit provides an extra time period to be added to the time dictated by the selected setting for the browning control knob 6 dependent on the temperature inside the toaster and the number of times the toaster has been used in a predetermined time period, normally 30 minutes. Typical boost time periods are for first time used 20 seconds, for second time used 10 seconds, for the third time used 5 seconds and for the fourth time and subsequent times used 0 seconds. At the maximum pot setting, the auto-boost feature is disabled. The unit needs to be operated for a period in excess of 20 seconds before it will decrement the auto-boost time period.

It will be appreciated that the foregoing is merely exemplary of electric toasters in accordance with the invention and that modifications can readily be made thereto without departing from the true scope of the invention.

Claims

CLAIMS:

1. An electric toaster having heating elements connectable to an electrical power supply, toast colour selection means for setting a selected time period for a toasting cycle, defrost means selectable when toasting items from frozen, and control means responsive to the toast colour selection means and the defrost means, the control means being operable when the defrost means is selected sequentially to cause power to flow to the heating elements for a first period of time, to discontinue or reduce the power flowing to the heating elements for a second period of time, and to restore power to the heating elements for a period of time set by the toast colour selection means.

2. An electric toaster having heating elements connectable to a source of electricity, the toaster including inter alia defrost means for use when toasting food items from frozen, the defrost means, when selected, operating sequentially to cause power to pass to the heating elements for a first period of time, on completion of the first time period to prevent power to pass to the heating elements for a second period of time, and on completion of the second time period to cause power to pass to the heating elements for completion of a toasting cycle.

3. A toaster as claimed in claim 1 or claim 2 in which the first period of time is between 20 and 40 seconds.

4. A toaster as claimed in any one of the preceding claims wherein the second period of time is between 15 and 30 seconds.

5. A toaster as claimed in any one of the preceding claims further comprising a browning control switch operable to select any one of a multiplicity of time-dependent settings.

6. A toaster as claimed in any one of the preceding claims comprising a plurality of toasting slots and a toasting slot selector switch operable to cause power to flow to only one such slot, more than one such slot or all such slots.

7. An electric toaster substantially as herein described and as described with reference to the accompanying drawings of which:-