GB1598504A

GB1598504A - Electrical connector device for establishing an electrical connection to a motor vehicle window heater

Info

Publication number: GB1598504A
Application number: GB693178A
Authority: GB
Original assignee: SACEX Srl
Current assignee: SACEX Srl
Priority date: 1978-02-21
Filing date: 1978-02-21
Publication date: 1981-09-23

Description

(54) AN ELECTRICAL CONNECTOR DEVICE FOR ESTABLISHING AN ELECTRICAL CONNECTION TO A MOTOR VEHICLE WINDOW HEATER (71) We, SACEX S.r.l., of Via Balossa, 23 Cormano (Milano) Italy, an Italian body corporate, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to an electrical connector device and in particular concerns a connector device for establishing an electrical connection to a motor vehicle window heater.

It is well known to incorporate resistance wires in adhesive backed transparent insulating sheet to form a heater which, when attached to a motor vehicle window and connected to the electrical supply of the vehicle, helps to keep the glass surface free from ice in cold weather and to prevent misting of the window under other weather conditions.

Such heaters.normally incorporate a predetermined number of wire resistances extending parallel to one another and connected electrically in parallel by means of a pair of end conductors which are provided on the insulating sheet and to which are attached respective clamps for connecting the element to a power source and to earth respectively.

However, a heater of this form must necessarily be manufactured in predetermined sizes; that is, a distinct heater must be provided for each different size and shape of motor vehicle window. Accordingly, a manufacturer is required to produce, and a vendor is required to stock, a wide range of similar goods between which the major difference is merely one of dimensions.

In an attempt to avoid needless duplication, separate connector devices for attachment to different lengths of sheet-like heater cut off from a continuous roll have been produced.

One such known connector device incorporates at least one conductive metallic strip provided with tongues which project from the device and establish electrical contact with the ends of the wire resistances provided on the insulating sheet. It is, however, frequently very difficult to obtain a good electrical connection between the tongues and the wires because involuntary shifting of the insulating sheet incorporating the wire resistances may cause the electrical contact between the wires and the tongues to fail, prejudicing the efficiency of the heater.

According to the present invention there is provided an electrical connector device for establishing an electrical connection to a motor vehicle window heater formed from a plurality of resistance wires provided on a transparent flexible insulating sheet, which device comprises an elongate base member made of electrically insulating material and having a trapezium-shaped cross-section, an adhesive layer, covered before use by a removable strip, provided on one of the two parallel surfaces of the base member to enable attachment of the base member to the insulating sheet, an elongate cover member made of electrically insulating material and formed with a longitudinal recess having a complementary shape to the shape of the base member for receiving the base member therein, an electrically conductive lining in the recess attached to at least one electrically conductive member which extends through a slot formed in the cover member to provide for an external electrical connection to the device, and fastening means for securing the base and cover members together with the base member received in the recess of the cover member so as to grip an inserted portion of the heater between the;two members and bring ends of the resistance wires of the heater into contact with the conductive lining of the recess.

The present invention thus provides a connector device for any length of a standard width sheet-like heater which ensures a good connection between the resistance wires and the conductive lining of the cover member of the device.

In a preferred embodiment of the present invention an adhesive layer, covered before use by a removable protective strip, is provided on the other of the two parallel surfaces of the base member to retain the trapped portion of the heater in position.

Preferably, the conductive lining of the cover member is formed from adhesive strips of metallic material, the adhesive side of which is covered before use by a removable protective layer.

The conductive lining of the cover member may be formed from isolated strips which, when connected to the ends of the resistance wires, divide the wires into isolated groups which may be connected in series by using a similar connector device at the opposite end of the heater.

Generally the connector device of the present invention is used in conjunction with a second similar device so that a connector device may be connected to each end of the heater to complete a circuit incorporating a warning lamp through the resistance wires of the heater.

By using two connector devices embodying the invention and by altering the number of isolated conductive strips forming the lining of the recess in the cover member, heaters operated by different voltage power supplies can be made to deliver the same heat output to provide the required demisting or deicing of the window.

The fastening means may be a screw so dimensioned that in use the screw threaded end nearly touches a window or glass surface to which the heater is attached so preventing the ends of the resistance wires moving away from said glass surface at this point.

In order that the invention may be more readily understood, embodiments thereof will now be described by way of example, with reference to the accompanying drawings, wherein: Figure 1 shows a sheet-like heater connected to a 6 volt power supply by means of a pair of connector devices according to a first embodiment of the present invention; Figure 2 is a similar view to Figure 1 but illustrating a second embodiment of the connector device for connecting the heater in a circuit having a 12 volt power supply; Figure 3 is a similar view to Figures 1 and 2, but illustrating a third embodiment of the connector device for connecting the heater in a circuit having a 24 volt power supply; Figure 4 is a cross-section through the connector device of Figure 7 along the line A-A in Figure 7 showing the parts of the device before assembly; Figure 5 shows a portion of a heater comprising a transparent insulating sheet on which are provided a plurality of parallel wire resistances; Figure 6 is a cross-section through the connector device of Figure 7 along the line A-A in Figure 7 and showing the device after assembly; and Figure 7 is a fragmentary plan view of a heater provided with a connector device embodying the invention and applied to a glass surface.

Referring now to the drawings, Figure 7 shows a glass surface 1 of, for example, the rear window of a motor vehicle to which is applied a heater which allows visibility through the glass surface to be improved during bad weather conditions. The heater comprises a strip of transparent, flexible sheet material 3, one face of which is provided with an adhesive layer 4 covered, prior to use, by a removable backing sheet 5 as shown in Figure 5. Provided on the sheet 3 are a plurality of resistance wires 7 which together form an electrical heating element. The wires 7 are connected in a power supply circuit by means of a pair of electrical end connectors 8 attached to the sheet 3.

As shown in Figures 4 and 6, an end connector 8 embodying the present invention comprises an elongate base member 9 having a trapezium-shaped transverse cross-section and an elongate cover member 17 formed with a longitudinally extending recess having a substantially trapezium-shaped transverse crosssection for receiving the base member 9.

The larger of the parallel surfaces of the base member 9 is covered with an adhesive layer 10 initially protected by a removable protective strip 11. Similarly, the other parallel face is covered with an adhesive layer 12 protected by a removable protective strip 13.

The base member 9 is formed with a screw threaded bores 14 at spaced locations along its length, i.e. at the ends and centre of the member 9 in the illustrated embodiments. The cover member 17 is provided with corresponding bores in each of which a bush 16 is rivetted.

When the end connector 8 is assembled (Figure 6) the respective bores in the base and cover members are aligned in order to receive screws 15, each of which screw-threadedly engages in the respective threaded bore 14 and serves to fasten together the base member 9 and the cover member 17. An electrically conducting strip 18, cut into predetermined lengths from a continuous roll and having an adhesive surface which before use of the strip is covered with a removable protective sheet, lines the entire interior surface of the recess in the cover member 17.

A slit is formed at each end of the cover member 17 to allow a connecting lug 20 electrically connected to the conductive strip 18 to extend out of the cover member 17. The lugs 20 provide for external electrical connections to the device, for example via line 21 and an earthed warning lamp 23 to the power source 22 and via line 24 to earth (see Figures 1 to 3).

To assemble a window heater using connector devices embodying the invention, a strip of the adhesive transparent sheet 3 is first cut to the requisite size (for a 6V power supply the width of the strip should incorporate six wires) ensuring that the strip is rather longer than the area to be heated to enable each end of the strip to be folded over the surface 12 of the base member 9.

The protective sheet 5 is then removed and the strip of the sheet 3 applied to the glass surface of, for example, the rear window of a motor vehicle. Next, the protective strips 11 are peeled off two base members 9, which are stuck in position parallel to each other and the required distance apart on the strip of the sheet 3 attached to the glass surface 1.

The protective strip 13 is removed from the members 9 to uncover the adhesive surfaces 12.

On each side of the area bounded by the base members 9 the excess length of sheet 3 is folded up over the respective base member so as to cover the respective faces 12 of the base members 9. The protective sheet is then removed from the conductive strips 18 cut from the roll of conductive material, a pair of lugs 20 are attached, as appropriate, to the ends of the strips 18 and the adhesive sides of the conductive strips 18 are fitted against the interior surfaces of the recesses of the respective cover members 17, forcing the lugs 20 through the corresponding slits in the cover members.

Each pair of corresponding members 9 and 17 is then joined together by means of the screws 15 which as they are tightened draw the members 9 and 17 together and press the conductive strips 18 into contact with the bared ends of the wires 7.

The electrical connection is completed by connecting one lug 20 to the supply line 21 and the other lug to earthing line 24.

In the embodiment of Figure 1, where a 6 volt power supply is used, a single conductive strip 18b is applied to each cover member 17 and one lug 20 is attached to one end of each strip 18b, so that the individual wires 7 are all connected in parallel between lines 21 and 24.

In order to maintain the same heating power and visibility through the glass surface when using a 12 volt power supply 22 to power the heater as in Figure 2, two isolated shorter conductive strips 18a of equal length may be provided in one connector device and only a single conductive strip 18b in the other device, as shown in Figure 2, thus dividing the six resistances into two series connected groups 7a and 7b each comprising three resistances connected in parallel. Each of the conductive strips 18a of the one device has a connection lug 20, one for connection to the supply line 21 and the other for connection to the earthing line 24.

When a 24 volt power supply 22 is used as in Figure 3, each of the two end connectors may incorporate two isolated conductive strips. As shown in Figure 3, each connector device is provided with two isolated strips of different lengths the strips being so placed that the longer conductive strip 1 8d of one device is directly opposite the shorter strip I 8c of the other device. A lug 20 is attached to each of the shorter strips 18c, so that the resistances are divided into three series connected groups 7a, 7b and 7c, each comprising two resistances connected in parallel.

The potential drop across each resistance wire 7, 7a, 7b or 7c is therefore the same in each of the three embodiments described above although power supplies of different voltage are used. Accordingly, each of the three heaters will produce the same amount of heat and have a similar effect in demisting or deicing a window to which it is attached.

WHAT WE CLAIM IS: 1. An electrical connector device for establishing an electrical connection to a motor vehicle window heater formed from a plurality of resistance wires provided on a transparent flexible insulating sheet, which device comprises an elongate base member made of electrically insulating material and having a trapezium-shaped cross-section, an adhesive layer, covered before use by a removable strip, provided on one of the two parallel surfaces of the base member to enable attachment of the base member to the insulating sheet, an elongate cover member made of electrically insulating material and formed with a longitudinal recess having a complementary shape to the shape of the base member for receiving the base member therein, an electrically conductive lining in the recess attached to at least one electrically conductive member which extends through a slot formed in the cover member to provide for an external electrical connection to the device, and fastening means for securing the base and cover members together with the base member received in the recess of the cover member so as to grip an inserted portion of the heater between the two members and bring ends of the resistance wires of the heater into contact with the conductive lining of the recess.

2. A device according to claim 1, wherein an adhesive layer, covered before use by a removable strip is provided on the other of the two parallel surfaces of the base member to retain the trapped portion of the heater in position.

3. A device according to claim 1 or 2, wherein the conductive lining of the recess is formed from a continuous strip of adhesive metallic material, the adhesive side of the material being covered prior to use by a removable protective layer.

4. A device according to any one of claims 1 to 3, wherein the conductive lining of the recess is formed from a plurality of isolated conductive strips which, in use, contact the ends of the resistance wires to divide the wires into a plurality of groups which are connected electrically in series with the wires in each group being connected electrically in parallel.

5. A motor vehicle window heater formed from a plurality of resistance wires provided on a transparent flexible insulating sheet, in which heater a pair of connector devices according to any preceding claim are connected to respective ends of the heater for connecting the heater in a power supply circuit.

6. An electrical connector device according to claim 1 substantially as hereinbefore described

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. the strip of the sheet 3 applied to the glass surface of, for example, the rear window of a motor vehicle. Next, the protective strips 11 are peeled off two base members 9, which are stuck in position parallel to each other and the required distance apart on the strip of the sheet 3 attached to the glass surface 1. The protective strip 13 is removed from the members 9 to uncover the adhesive surfaces 12. On each side of the area bounded by the base members 9 the excess length of sheet 3 is folded up over the respective base member so as to cover the respective faces 12 of the base members 9. The protective sheet is then removed from the conductive strips 18 cut from the roll of conductive material, a pair of lugs 20 are attached, as appropriate, to the ends of the strips 18 and the adhesive sides of the conductive strips 18 are fitted against the interior surfaces of the recesses of the respective cover members 17, forcing the lugs 20 through the corresponding slits in the cover members. Each pair of corresponding members 9 and 17 is then joined together by means of the screws 15 which as they are tightened draw the members 9 and 17 together and press the conductive strips 18 into contact with the bared ends of the wires 7. The electrical connection is completed by connecting one lug 20 to the supply line 21 and the other lug to earthing line 24. In the embodiment of Figure 1, where a 6 volt power supply is used, a single conductive strip 18b is applied to each cover member 17 and one lug 20 is attached to one end of each strip 18b, so that the individual wires 7 are all connected in parallel between lines 21 and 24. In order to maintain the same heating power and visibility through the glass surface when using a 12 volt power supply 22 to power the heater as in Figure 2, two isolated shorter conductive strips 18a of equal length may be provided in one connector device and only a single conductive strip 18b in the other device, as shown in Figure 2, thus dividing the six resistances into two series connected groups 7a and 7b each comprising three resistances connected in parallel. Each of the conductive strips 18a of the one device has a connection lug 20, one for connection to the supply line 21 and the other for connection to the earthing line 24. When a 24 volt power supply 22 is used as in Figure 3, each of the two end connectors may incorporate two isolated conductive strips. As shown in Figure 3, each connector device is provided with two isolated strips of different lengths the strips being so placed that the longer conductive strip 1 8d of one device is directly opposite the shorter strip I 8c of the other device. A lug 20 is attached to each of the shorter strips 18c, so that the resistances are divided into three series connected groups 7a, 7b and 7c, each comprising two resistances connected in parallel. The potential drop across each resistance wire 7, 7a, 7b or 7c is therefore the same in each of the three embodiments described above although power supplies of different voltage are used. Accordingly, each of the three heaters will produce the same amount of heat and have a similar effect in demisting or deicing a window to which it is attached. WHAT WE CLAIM IS:

1. An electrical connector device for establishing an electrical connection to a motor vehicle window heater formed from a plurality of resistance wires provided on a transparent flexible insulating sheet, which device comprises an elongate base member made of electrically insulating material and having a trapezium-shaped cross-section, an adhesive layer, covered before use by a removable strip, provided on one of the two parallel surfaces of the base member to enable attachment of the base member to the insulating sheet, an elongate cover member made of electrically insulating material and formed with a longitudinal recess having a complementary shape to the shape of the base member for receiving the base member therein, an electrically conductive lining in the recess attached to at least one electrically conductive member which extends through a slot formed in the cover member to provide for an external electrical connection to the device, and fastening means for securing the base and cover members together with the base member received in the recess of the cover member so as to grip an inserted portion of the heater between the two members and bring ends of the resistance wires of the heater into contact with the conductive lining of the recess.

with reference to, and as illustrated in, the accompanying drawings.

7. A motor vehicle window heater according to claim 5, substantially as hereinbefore described with reference to, and as illustrated in, the accompanying drawings.