GB2169740A

GB2169740A - Optical display device for the individual working ranges of a baking and roasting oven

Info

Publication number: GB2169740A
Application number: GB08600833A
Authority: GB
Inventors: Heinz Schreiber
Original assignee: Licentia Patent Verwaltungs GmbH
Current assignee: Licentia Patent Verwaltungs GmbH
Priority date: 1985-01-16
Filing date: 1986-01-15
Publication date: 1986-07-16
Also published as: GB2169740B; DE3501150C2; FR2576089A1; GB8600833D0; FR2576089B1; DE3501150A1

Abstract

An optical display device is provided for indicating the individual working ranges of a baking and roasting oven operable selectively (e.g. with radiant heating or with hot-air circulation) and having a selector switch for the selection of one of the two modes of operation and a temperature selecting knob of a thermostat. The display device consists of a plurality of display panels 1-10 for the individual working ranges. A separate light-producing member 1'-10' is associated with each display panel. All the light- producing members 1'-10' are connected in parallel, a common resistor 12 being connected in series at the input side of the parallel-connected light-producing members 1'-10'. The individual light-producing members 1'-10' can be activated in succession through conducting paths 14; 15; 16, 16'; 17, 17' of a printed circuit board switch 13 by actuation of the temperature selecting knob. <IMAGE>

Description

SPECIFICATION Optical display device for the individual working ranges of a baking and roasting oven The invention relates to an optical display device for the individual working ranges of a baking and roasting oven which can be operated selectively in one of at least two methods of operation, namely, for example, in conventional manner with upper and lower radiant heating or with hot-air circulation, which has a selector switch for the selection of one of the two methods of operation and a temperature selecting knob of a thermostat for setting the temperature of the baking and roasting oven for the particular working range.

Baking and roasting ovens of the type in question are generally known. For reasons of safety, it is usual with such ovens, to make it optically visible that the appliance is switched on and hence is in operation. Illuminated indicator windows or display panels in the switch cover, which are associated with the individual switch knobs or setting knobs, or directly illuminated switch knobs or setting knobs which light up on being turned out of the zero position are used for this purpose, for example.

Each of these indicator devices is associated with a specific position of use and only indicates for this. In a baking and roasting oven which can be operated selectively in one of at least two possible methods of operation, for example with upper and lower "radiant heating" or with "hot-air circulation" and wherein the temperature of the baking and roasting oven for the baking or roasting range with the "radiant heating" method of operation is considerably higher (about 10 to 30or) than the "hot-air circulation" method of operation, the user cannot see, with one of the known indicator devices, whether the baking and roasting temperatures set for a certain baking or roasting operation or working range has been set correctly for the selected method of operation-"radiant heating or hot-air circulation".

It is therefore an object of the invention to provide a display device for a household appliance of the type initially mentioned which, with the setting of a baking or roasting temperature laid down for a specific baking or roasting operation and hence selection of a certain working range associated with the set temperature taking into consideration the particular method of operation pre-selected (radiant heating or hot-air circulation), signals the selected working range to the user so that the latter has a visible (optical) check of the working range set or selected and, in the event of a wrong temperature setting and hence wrongly selected working range, can immediately make a correction in the temperature setting.

The invention accordingly provides an optical display device for indicating the individual working ranges of a baking and roasting oven which can be operated in one of at least two optional modes of operation and which has a selector switch for selecting the desired mode of operation and a thermostat settable by a movable control knob for controlling the temperature of the oven in the selected mode of operation, said display device comprising a plurality of display panels arranged for illumination by corresponding light emitting elements, and the current paths of said light emitting elements being connected, on the one hand, in common to a resistor connected in series between said current paths and one supply voltage terminal and, on the other hand, to respective individual conductor tracks of a printed circuit board switch coupled to the control knob of said thermostat and arranged to couple said conductor tracks selectively to the supply voltage in accordance with the setting of the thermostat.

With the invention, the effect is achieved that, in accordance with the method of operation selected (radiant heating or hot-air circulation) and taking into consideration the set baking or roasting temperatures, the working range associated with the set temperature for a specific baking or roasting operation is automatically displayed, namely an optical indication of the working range for a specific item to be baked or roasted depending on the set baking or roasting temperature and the method of operation selected. Thus the user of a baking and roasting oven with a display device according to the invention is given an indication of the particular working range he is in as a result of his selection of the temperature setting and method of operation.This working range can then be corrected at any time by appropriate adjustment of the temperature selecting knob and this is again indicated to the operator by appropriate lighting up of another display panel.

As a result of the series connection of a common resistor before the parallel-connected light-producing members (glow-discharge or neon lamps), the effect is achieved that after the ignition of a light-producing member, the operating voltage drops at the light-producing member which is ignited. If, on further rotation of the temperature selecting knob, a second light-producing member (glow-discharge lamp) is connected thereto, the operating voltage present here is at first not sufficient to ignite the next (second) light-producing member.

Only when the switch contact of the lightproducing member which is in operation (switched on) is opened and its operating voltage is thus interrupted is the light-producing member indicating another working range of the baking and roasting oven immediately ignited and so caused to light up.

The invention is illustrated by way of example in the drawings, in which Figure 1 is a block diagram of a display device which consists of a plurality of illuminated display panels and is activated through conducting paths, and Figure 2 is a circuit diagram for the individual light-producing members of the display panels.

Referring to the drawings, a display device consisting of a plurality of illuininated display panels 1 to 10 for an electric baking and roasting oven is designated by 11. The oven can be operated selectively in one of at least two methods of operation which are provided, either in conventional manner with upper and lower "radiant heating", or exclusively by "hot-air circulation". The display panels 1 to 10 can be marked by inscriptions with the individual working ranges of the baking and roasting oven which can be set or selected.

Associated with the rise in the numbering of the display panels is a correspondingly higher temperature setting for the baking and roasting oven and hence also a specific "working range" for which the temperature setting in question is provided. The "working ranges begin at relatively low temperatures of about 90 to 115 C for meringues and end at temperatures of about 230 to 2600C for over-baking.

Associated with each of the display panels 1 to 10 as a light-producing member is a glow lamp 1' to 10'. All the glow lamps 1' to 10' are connected in parallel and are connected to an operating voltage by closing a contact 1" to 10" connected in series with each glow lamp. A single and therefore common resistor 12 may appropriately be connected in series with the input side of the parallel-connected glow lamps 1' to 10'.

The switching on of the display device 11 is effected through a sliding contact which is coupled to the temperature setting of the baking and roasting oven and cooperates with a printed-circuit disc 13 so that on rotation of the temperature selecting knob and hence setting of the temperature of the baking and roasting oven, the display device 11 is activated and, according to the position of the temperature selecting knob, signals the "working range associated with this position to the user by lighting up one of the display panels 1' to 10'. The printed-circuit disc 13 has a plurality of pairs of conducting paths 14, 15, 16, 17 to which operating voltage is applied through contacts 18, 19, 20, 21 of the baking and roasting oven thermostat (oven switch).

The one conducting path 16' or 17' of the pair of conducting paths 16 or 17 is divided into a plurality of separate conducting path sections 22, 23, 24... for the individual temperature ranges (working ranges). The conducting path 14 is responsible for the grill heating, the conducting path 15 for the grill and hot-air heating, the conducting path 16 for the upper and lower radiant heating and the conducting path 17 exclusively for the hot-air heating. The individual pairs of con ducting paths are appropriately connected through a sliding contact, not illustrated, which is coupled, in an entraining manner, to the adjusting shaft of the oven thermostat.

Claims

1. An optical display device for indicating the individual working ranges of a baking and roasting oven which can be operated in one of at least two optional modes of operation and which has a selector switch for selecting the desired mode of operation and a thermostat settable by a movable control knob for controlling the temperature of the oven in the selected mode of operation, said display device comprising a plurality of display panels arranged for illumination by corresponding light emitting elements, and the current paths of said light emitting elements being connected on the one hand, in common to a resistor connected in series between said current paths and one supply voltage terminal and, on the other hand, to respective individual conductor tracks of a printed circuit board switch coupled to the control knob of said thermostat and arranged to couple said conductor tracks selectively to the supply voltage in accordance with the setting of the thermostat.

2. An optical display device as claimed in Claim 1. wherein said light emitting elements comprise glow discharge lamps.

3. An optical display device as claimed in Claim 1. wherein said conductor tracks of said selector switch are arranged in a plurality of groups, each group of which is arranged to be coupled via said said printed circuit switch to a voltage source controlled by the said mode of operation selecting switch.

4. An optical display device substantially as described herein with reference to the accompanying drawings.