GB2240206A

GB2240206A - Display device for domestic electrical appliances

Info

Publication number: GB2240206A
Application number: GB9100296A
Authority: GB
Inventors: Piero Durazzani
Original assignee: Industrie Zanussi SpA
Current assignee: Industrie Zanussi SpA
Priority date: 1990-01-11
Filing date: 1991-01-08
Publication date: 1991-07-24
Also published as: IT223858Z2; FR2656946A1; IT9034002U1; GB9100296D0; IT9034002V0; FR2656946B3; DE9100205U1; ES2034916A6

Abstract

An electroluminescent display device is adapted for domestic electrical appliances, for indicating the working programs which can be set by way of selector members provided in the control panel of such machines. The display comprises at least one support screen of transparent material, to whose internal surface are successively applied by means of screen printing in superposed relationship a first layer of conductive ink containing indium oxide and which operates as a positive electrode, a second layer electroluminescent material, preferably zinc sulphide doped with salts of transition metals such as copper and manganese, a third layer of conductive ink containing silver or graphite and which operates as a negative electrode, and a fourth layer of electrically insulating material such as insulating varnish or ink.

Description

DISPLAY DEVICE FOR DOMESTIC ELECTRICAL APPLIANCES The invention relates to a display device of simple type which can be used for indicating the operational status of domestic electrical appliances such as clothes washing machines, dishwashing machines and the like.

Display devices for domestic electrical appliances such as clothes washing machines, dishwashing machines and the like are known which are of fluorescent type or of a type using liquid crystals which are driven by way of electronic control circuits suitably disposed in the domestic electrical appliance and capable of generating specific output signals for indicating the operational status of such machines and the operating programs selected therein in the form of letters, numbers and/or symbols.

Those display devices operate in a satisfactory and reliable fashion while however suffering from the disadvantage of being of a complicated structure and requiring the provision of specific electronic control circuits for indicating the operational status and the programs selected in the machines.

According to the present invention, there is provided a display device the working programs of which can be set by way of selector members provided in the control panel of such machines, comprising at least one support screen of transparent material, to whose internal surface are successively applied by means of screen printing in superposed relationship a first layer of electrically conductive ink and which operates as a first electrode, a second layer of electroluminescent material, a third layer of electrically conductive ink and which operates as a second electrode, and a fourth layer of electrically insulating material, said layers being provided with graphic and/or numerical symbols which can be illuminated by said second layer when an electrical voltage is applied across said first and third layers.

The invention will be further described by way of non-limitative example with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic front view of a domestic electrical appliance incorporating a display device according to the invention, and Figure 2 is a diagrammatic view of the various component parts of the present display device.

Referring to figure 1, shown therein is a domestic electrical appliance such as a clothes washing machine 3, dishwashing machine, cooker or the like, comprising a casing 4 provided in its upper front part with a control panel 5 in which are disposed the selector members 6 for setting the various operating programs to be performed, and at least one display device 7 according to the invention for indicating the programs selected and the operating status of the associated machine.

With reference to figure 2, the display device is substantially formed by a support mask or screen 8 of suitable transparent plastics material such as methacrylate or the like, the visible external surface 9 of which is smooth and untreated while its internal surface 10 which is turned towards the front part of the casing 4 of the appliance is covered by means of screen printing with a series of mutually superposed layers which will be described hereinafter, in which are provided the graphic and/or numerical symbols of the operating programs to be performed and the signals for indicating the operational status of the machine.

Successively applied to the above mentioned internal surface 10 of the transparent screen 8 are a first layer 11 of electrically conductive ink of per se known type which preferably has indium oxide as the principal constituent thereof, operating as a positive electrode which can be powered from the electrical mains by way of a rectifier (not shown), a second layer 12 of electroluminescent material of conventional type which is preferably formed by semiconductor crystals of zinc sulphide doped with salts of transition metals such as copper and manganese, which is capable of becoming luminescent in the presence of an electrical voltage, and a third layer 13 of electrically conductive ink of conventional type preferably formed on the basis of silver or graphite and acting as a negative electrode which can be supplied from the electrical mains by way of said rectifier.Finally, applied to the layer 13 of conductive ink is a fourth layer 14 of electrically insulating material which is preferably formed by transparent insulating varnish or ink of per se known type, which acts as electrical insulation between the laminate structure produced in the above described manner and the metal material of the casing 4 of the appliance, against which the laminate structure is applied.In that way the display device of the above configuration is of a simple construction and can be easily produced using materials which are available particularly on the market, and is also set in operation without requiring the use of particular control circuits, as is the case with the present display devices, by supplying all the indications to be displayed to the positive and negative conductors 11 and 13, which are connected into the electrical circuit of the appliance and which are turned on selectively in the order laid down by the programmer-timer of the appliance itself, that fact governing the lighting of the respective indications, with consequential improved reading thereof.

A plurality of sets of the conductors 11 and/or 13 may be provided to be selectively energised to provide respective character or graphic displays appropriate to the current state of operation of the appliance.

Claims

1. A display device the working programs of which can be set by way of selector members provided in the control panel of such machines, comprising at least one support screen of transparent material, to whose internal surface are successively applied by means of screen printing in superposed relationship a first layer of electrically conductive ink and which operates as a first electrode, a second layer of electroluminescent material, a third layer of electrically conductive ink and which operates as a second electrode, and a fourth layer of electrically insulating material, said layers being provided with graphic and/or numerical symbols which can be illuminated by said second layer when an electrical voltage is applied across said first and third layers.

2. A display device according to claim 1 wherein the material of the first layer comprises indium oxide.

3. A display device according to claim 1 or 2 wherein the material of the second layer comprises semiconductor crystals formed of zinc oxide doped with a salt of a transition metal.

4. A display device according to claim 1, 2 or 3 wherein the third layer is formed of silver or graphite.

5. A display device according to any one of the preceding claims, wherein the fourth layer is an electrically insulating varnish or ink.

6. A display device constructed and arranged to operate substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

7. A domestic appliance having a display panel incorporating a display device according to any one of the preceding claims.