GB2071338A

GB2071338A - Touch responsive control panel

Info

Publication number: GB2071338A
Application number: GB8107530A
Authority: GB
Original assignee: CH IND Ltd
Current assignee: CH IND Ltd
Priority date: 1980-03-11
Filing date: 1981-03-10
Publication date: 1981-09-16

Abstract

A control panel for consumer durable equipment comprises front and back sheets (6, 7) carrying and separating electrodes (9a, 9b, 10) of capacitance touch switches. The control circuit of the equipment is operated by actuation of the capacitance switches by an operator bringing his finger into contact with the surface of the sheet (6) overlying one of the switches. <IMAGE>

Description

SPECIFICATION Control panel Conventional control panels for so-called "consumer durable" equipment, such as washing machines, tumbler dryers, and dish washers, incorporate electro-mechanical switches which are movable through complementary apertures in the control panel. Such switches provide clearances and crevices in which grease and other dirt can accumulate leading to possible malfunction of the switch, and poor hygiene.

Furthermore, the switches are comparatively unsophisticated for controlling electronic microcircuity, the use of which in this field the inventor considers to be a requirement in the near future.

In accordance with the present invention, a control panel for consumer durable equipment comprises a sheet of electrically non-conductive material and two-dimensional electrical circuitry, including a plate of at least one capacitance switch, attached to the back of the sheet, whereby in use, an operator can bring a finger into contact with the front of the sheet in proximity to the plate to operate the switch.

By two-dimensional circuitry is meant a printed or etched circuit.

The circuitry may be provided directly on a face of the sheet or may be provided on a second sheet of electrically non-conductive material which is attached to the back of the first sheet. If the circuitry is provided on the back of the front sheet or on the front of the back sheet, it will be sandwiched between the two sheets and will be protected from the environment.

The capacitance switch will normally comprise a second plate cooperating with the first plate and forming part of further two-dimensional circuitry attached to the sheet or sheets and separated from the first circuitry by a sheet, which may be the front and/or back sheet, of electrically nonconductive dielectric material. This construction ensures an accurate spacing of the plates of the capacitance switch and hence a constant and predetermined capacitance enabling the switch to be built into a tuned circuit. The second plate may be divided into two separate parts which cooperate with a common first plate to form separate capacitors. When the first plate is then at least partially earthed by an operator's finger, the resulting charge disturbance on the two parts of the second plate can be utilized in a tuned circuit.

As is known in other fields, the operation of the capacitance switch results from the finger of the operator, who is assumed to be earthed, disturbing the charge carried by the plates of the switch and hence producing a pulse in the associated control circuit, incorporating the twodimensional circuitry. The predetermined positioning of the first plate of the capacitance switch relatively to the front surface of the front sheet ensures that the distance between the front surface of the front sheet against which the operator's finger is placed, and the adjacent plate of the capacitance switch is accurately predetermined so that the circuit response is equally accurately predetermined. This enables the circuit to be tuned so that a recognisable response results from the operator placing his finger near or against the appropriate part of the panel for a certain length of time.Provided that the operator is properly instructed, this can avoid unwanted switch operation, for example by an uninstructed child.

The new control panel may be in the form of a trim panel which is bonded or otherwise secured at a window in a main panel of the equipment casing. Alternatively, it may be an integral part of a main panel of the casing. In either event it may present a smooth surface which can be wiped clean.

The panel may have the properties of a socalled "dead panel", that is to say that when viewed from the front, the panel appears to be opaque, but legends may be caused to appear at respective locations on the panel by local illumination from the rear. Such legends may indicate alternative programes to be selected, or the step to which a programme has advanced, or particularly in the present case to indicate the positions at which the capacitance switch or switches is or are located so that the operator can touch at the appropriate point. For example illumination may be provided through or around a capacitance switch plate of the circuit to illuminate at the front of the panel and overlying the capacitance switch a word such as "touch".The panel may be rigid but preferably has some flexibility, particularly if it is to be adhesively bonded as a trim panel or fitted to a cylindrical object. Although other materials may be suitable for front and back sheets, plastics materials are thought to be most appropriate for both sheets. Thus, by way of example, the back sheet may be made of a polyester resin and have on its front face a printed area to provide the circuitry incorporating one plate of the or each capacitance switch. The front sheet may then be a textured polyvinyl chloride sheet, the back face of which is printed to present a "dead panel" appearance and on which further legend is printed for back illumination through the panel.The front face of the front sheet may be printed with further circuitry incorporating the other plate of the or each capacitance switch, this circuitry being covered by an electrically non-conductive translucent layer. The completed laminate may have projecting tails from the encapsulated circuitry for connection to the control circuit in the equipment or connection can be made by spring loaded point contacts.

Since the essential control circuitry may be incorporated in the control panel, it is possible for different models of similar equipment to be made up from a common equipment casing with a selected one of a range of different control panels representing different programmes.

An example of a piece of equipment fitted with a control panel in accordance with the present invention is illustrated in the accompanying drawings, in which: Figure 1 is a diagrammatic perspective view of the piece of equipment: and, Figure 2 is an exploded view of the control panel.

The piece of equipment has a box casing 3, which may be made of sheet steel, a door 4, and a control panel 5 which controls via an electrical control circuit conventional electrically operated devices, such as motors and valves, of the piece of equipment.

The control panel consists of a laminate of two dielectric sheets 6 and 7 which are bonded together and screwed via corner screw holes 8 to the face of the casing 3 overlying a window in the casing. The panel carries the plates of nine capacitance switches. Thus the back plate 7 is printed with a metal film to provide nine plates each formed of separate parts 9a and 9b. Similarly the front sheet 6 is printed with a metal film to provide nine plates 10, indicated in Figure 2 by the dotted lines. Each plate 10 overlies a corresponding one of the composite plates 9a, 9b and corresponds to the overall generally rectangular shape of the composite plate 9a and 9b.The plates 9a, 9b may be printed on the front or back surface of the back sheet 7 and the plates 10 may be printed on the front or back of the front sheet 6, provided that both sets of plates are not one on the front of the back sheet and the other on the back of the front sheet, otherwise they would not be separated by the dielectric material. It is preferred that at least one of the sets of plates be mounted on the front of the back sheet 7 or on the back of the front sheet 6, so that they are securely encapsulated between the sheets. Connections to the control circuit from the plates 9a, 9b may be made directly to the plates if that set of plates are printed on the back of the back sheet 7. However, if the plates are sandwiched between the two sheets 6 and 7, tails for connection to the control circuit may also be printed as indicated diagrammatically at 11.The separation of the composite plates 9a, 9b into separate parts is used, as already mentioned, when the switches are connected into tuned circuits.

The front surface of the front sheet 6 may be covered with a layer of electrically non-conductive material, so that when the plates 10 are printed on the front of the front sheet 6, they are not directly exposed. The switches are operated by the operator bringing his finger into contact, or at least immediate proximity, of the front surface of the front sheet 6, overlying one of the plates 1 0. In order that the operator will know where to touch the front surface of the panel, the position of each switch is indicated by a surrounding border 1 2. In addition the space within the border 12 may carry appropriate data. Further indication to the operator that a particular switch has been operated or is next due for operation in a particular programme is available by means of lamps fitted behind the control panel in alignment with windows 13 and 14 in the sheets 7 and 6 respectively. Provided that the sheets 6 and 7 are transparent, or at least translucent, it is sufficient for the windows to be provided by unprinted portions of the plates 9a and 1 0. A coating is provided on the front of the front sheet 6, this must also be provided with a window, or at least be translucent, at least in alignment with the window 14.

Claims

1. A control panel for consumer durable equipment, the panel comprising a sheet of electrically non-conductive material and two dimensional electrical circuitry, including a plate of at least one capacitance switch, attached to the back of the sheet whereby, in use, an operator can bring a finger into contact with the front of the sheet in proximity to the plate to operate the switch.

2. A panel according to claim 1, wherein the circuitry is provided on a second sheet of electrically non-conductive material which is attached to the back of the first sheet.

3. A panel according to claim 1 or claim 2, in which the circuitry is sandwiched between the first and the or a second sheet which is attached to the back of the first sheet.

4. A panel according to any one of the preceding claims, in which the capacitance switch comprises a second plate cooperating with the first plate and forming part of further two dimensional circuitry attached to the sheet or sheets and separated from the first circuitry by a sheet of electrically non-conductive dielectric material.

5. A panel according to claim 4, in which the second plate is divided into two separate parts which cooperate with a common first plate to form separate capacitors for connection in a tuned circuit.

6. A panel according to claim 1, substantially as described with reference to the accompanying drawings.

7. An item of consumer durable equipment incorporating a control panel according to any one of the preceding claims.