Vehicle windscreen heater

Abstract

Aspects of the present invention relate to a windscreen (10) for a vehicle (300) which comprises a camera aperture (14) defined by a transparent area surrounded by an opaque region (12). An electrical circuit (20) for heating the camera aperture(14) is located within the camera aperture. The electrical circuit (20) comprises wires (22) arranged in a pattern that conforms to the shape of the camera aperture (14). Aspects of the present invention also relate to a control system for controlling operation of the electrical circuit (20), where the electrical circuit (20) may be operated in a stepwise manner to allow preferential clearing of a portion of the camera aperture. A system (200) and a method (50) for controlling operation of the electrical circuit (20) is also disclosed along with computer readable instructions which are arranged to perform the method (50).

Description

[0001] VEHICLE WINDSCREEN HEATER

[0002] TECHNICAL FIELD

[0003] The present disclosure relates to a vehicle windscreen heater. Aspects of the invention relate to a windscreen, to a control system, to a system, to a vehicle, to a method and to computer readable instructions.

[0004] BACKGROUND

[0005] It is known to provide windscreen heaters in the form of an electrical circuit comprising a pattern of wires located on the windscreen. When an electric current is provided through the wires, the wires heat up due to their electrical resistance thereby evaporating or melting any condensation or ice which may be obscuring the view through the windscreen.

[0006] In recent years cameras have been increasingly used in vehicles for position control and advance collision warning systems for example. When vehicle cameras are positioned with a field of view which intersects a windscreen, it is important that the windscreen is clear when the camera is in use so that the camera may obtain a clear picture. It is known to use windscreen heaters to ensure a Clear field of view for vehicle mounted cameras.

[0007] It is also known to provide vehicle windows with heaters in the form of electrical circuits comprising a plurality of spaced wires. Such heaters are useful for heating the window to melt frost and ice which may impair a vehicle user’s field of view. Heaters comprising electrical circuits are commonly used to heat front windscreens and rear backlights of vehicles.

[0008] Vehicle users must either pre-condition their vehicles ready for use in cold or frosty conditions by operating the window heater before the anticipated departure time, or operate the heater upon entering the vehicle and wait until the heater has defrosted the window sufficiently before departing.

[0009] It is an aim of the present invention to address one or more of the disadvantages associated with the prior art.

[0010] SUMMARY OF THE INVENTION

[0011] Aspects and embodiments of the invention provide a windscreen for a vehicle, a control system, a system, a method and computer readable instructions as claimed in the appended claims. Other aspects may provide a window, a backlight and a vehicle.

[0012] According to an aspect of the present invention there is provided windscreen for a vehicle, wherein the windscreen comprises a camera aperture located in a particular area of the windscreen and an electrical circuit for heating the camera aperture, the electrical circuit comprising one or more wires arranged in a pattern, wherein the pattern conforms to the shape of the camera aperture. The camera aperture may be defined by a transparent area surrounded by an opaque region.

[0013] The present invention is advantageous as the shape of the area cleared by the electrical circuit conforms to the shape of the camera aperture thereby making efficient use of the energy required to clear the camera aperture.

[0014] Optionally the pattern is located entirely within the camera aperture so that all of the energy required for clearing is provided within the bounds of the camera aperture.

[0015] The shape of the camera aperture optionally comprises one or more substantially triangular, and / or one or more substantially trapezoid portions. This shape is beneficial when being used with an arrangement of three cameras located on the reverse side of a rear view mirror.

[0016] An outline of the pattern may define at least one substantially triangular and / or trapezoidal shape so as to conform to the shape of a substantially triangular and / or trapezoidal camera aperture.

[0017] In one example, the pattern may comprise a series of concentric substantially triangular and / or trapezoidal shapes. This is advantageous as it allows to close packing of the wires in the limited area of the camera aperture.

[0018] Optionally the electrical circuit comprises a first circuit region and a second circuit region, wherein the electrical circuit is configured so that the first and second circuit regions are independently operable. This allows the camera aperture to be preferentially heated so that more energy can be directed to a first area of the camera aperture to clear in preference to the remaining area.

[0019] According to another aspect of the present invention there is provided a control system for controlling a windscreen clearing system of a vehicle, the control system comprising one or more controller, the control system comprising one or more processors collectively configured to: receive a first input signal indicative of a request to clear a camera aperture of a windscreen; output a first control signal, wherein the first control signal comprises an instruction to operate a first region of an electrical circuit located on or embedded in the camera aperture; receive a second input signal indicative of a transparency of a first portion of the camera aperture; determine if the transparency of the first portion of the camera aperture satisfies a pre-determined transparency threshold criteria in dependence on the second input signal; and if the transparency of the first portion of the camera aperture satisfies the pre-determined transparency threshold criteria, output a second control signal comprising an instruction to operate a second region of the electrical circuit.

[0020] The control system is advantageous as it provides for automated preferential clearing of a first portion of the camera aperture followed by automated clearing of a second portion of the camera aperture. The control system comprises one or more controllers collectively comprising at least one electronic processor having an electrical input for receiving an input signal; and at least one memory device electrically coupled to the at least one electronic processor and having instructions stored therein; and wherein the at least one electronic processor is configured to access the at least one memory device and execute the instructions thereon so as to: receive a first input signal indicative of a request to clear a camera aperture of a windscreen; output a first control signal, wherein the first control signal comprises an instruction to operate a first region of an electrical circuit located on or embedded in the camera aperture; receive a second input signal indicative of a transparency of a first portion of the camera aperture; determine if the transparency of the first portion of the camera aperture satisfies a pre-determined transparency threshold criteria in dependence on the second input signal; and if the transparency of the first portion of the camera aperture satisfies the pre-determined transparency threshold criteria, output a second control signal comprising an instruction to operate a second region of the electrical circuit.

[0021] According to a further aspect of the present invention there is provided a windscreen clearing system comprising the control system and windscreen described above.

[0022] According to a still further aspect of the present invention there is provided a vehicle comprising a windscreen described above, the control system described above, or the system described above.

[0023] According to a yet further aspect of the present invention there is provided a method for controlling a windscreen clearing system of a vehicle, the method comprising: receiving a first input signal indicative of a request to clear a camera aperture; outputting a first control signal, wherein the first control signal comprises an instruction to operate a first region of an electrical circuit located on or embedded in the camera aperture; receiving a second input signal indicative of a transparency of a first portion of the camera aperture; determining if the transparency of the first portion of the camera aperture satisfies a pre-determined transparency threshold criteria in dependence on the second input signal; and if the transparency of the first portion of the camera aperture satisfies the pre-determined transparency threshold criteria, outputting a second control signal comprising an instruction to operate a second region of the electrical circuit.

[0024] According to another aspect of the present invention there is provided computer readable instructions which, when executed by a computer, are arranged to perform a method described above.

[0025] According to another aspect of the present invention there is provided a vehicle window, the window comprising an electrical circuit for heating the window, wherein the electrical circuit comprises a pattern of wires having a first region and a second region, wherein the wires forming the first region of the pattern have a resistance per unit length greater than that the wires forming the second region of the pattern. Optionally the area of the window occupied by the first region of the pattern is less than the area of the window occupied by the second region of the pattern.

[0026] The present invention is advantageous as the higher heat production of the greater resistance wires in the first region of the pattern provides the ability to preferentially defrost a particular area of the window. Where that area is relatively small compared to the overall size of the window, a targeted area of the window may advantageously be defrosted.

[0027] Optionally the first region of the pattern is located in a central portion of the window. This is beneficial as preferential defrosting of the central portion of the window allows a vehicle user to rapidly achieve a safe field of view. This may be achieved by the first region of the pattern being surrounded by the second region of the pattern. Alternatively, the second region of the pattern may comprise a first sub-region and a second subregion, wherein the first region of the pattern is located between the first and second sub-regions of the second region of the pattern.

[0028] In one example, the area occupied by the first region of the pattern may decrease in height from the centre of the first region of the pattern towards the edges of the first region of the pattern. This is advantageous as this shape provides both a wide and high field of view.

[0029] Optionally the wires forming the first region of the pattern have a first thickness and the wires forming the second region of the pattern have a second thickness providing the ability to change the resistance of the wires by varying their thickness.

[0030] The wires forming the first region of the pattern are optionally thinnerthan the wires forming the second region of the pattern to provide greater resistance per unit length in the first region of the pattern. Thinner wires allow for closer spacing of the wires without impairing visibility.

[0031] The wires forming the first region of the pattern may comprise a different material composition to the wires forming the second region of the pattern providing the ability to change the resistance of the wires by varying their material composition.

[0032] In one example, the wires forming the first region of the pattern may have a different cross-sectional area to the wires forming the second region of the pattern providing the ability to change the resistance of the wires by varying their cross-section.

[0033] Optionally the average distance between the wires forming the first region of the pattern is less than the average distance between the wires forming the second region of the pattern. This is advantageous as closer spacing of wires provides a greater density of heating elements.

[0034] At least some of the wires forming the first region of the pattern may optionally comprise a plurality of electrically parallel wires which extend between a first portion of wire forming a first electrical path in the second region of the pattern and a second portion of wire forming the first electrical path in the second region of the pattern. This provides an efficient method of incorporating the first region of the pattern with the second region of the pattern. The plurality of electrically parallel wires may comprise three electrically parallel wires to provide an even distribution of heat without undue complexity.

[0035] In one example, the backlight may comprise a window as described above, and the shape of the first region of the pattern of wires may conform to the shape of the intersection between the backlight and a predetermined rear view mirror field of view requirement in a predetermined vehicle design specification. This is advantageous as the backlight may be preferentially defrosted to provide a legal minimum area of visibility.

[0036] According to another aspect of the present invention there is provided a vehicle comprising the window or the backlight described above.

[0037] Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and / or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and / or features of any embodiment can be combined in any way and / or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and / or incorporate any feature of any other claim although not originally claimed in that manner.

[0038] BRIEF DESCRIPTION OF THE DRAWINGS

[0039] One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0040] Figure 1 shows a schematic view of part of a vehicle windscreen comprising a windscreen heater;

[0041] Figure 2 shows a block diagram illustrating a control system for controlling a windscreen clearing system of a vehicle;

[0042] Figure 3 shows a flow chart illustrating a method for controlling a windscreen clearing system of a vehicle;

[0043] Figure 4 shows a vehicle in accordance with an embodiment of the invention;

[0044] Figure 5 shows a schematic representation of a vehicle backlight; and

[0045] Figure 6 shows a vehicle in accordance with an embodiment of the invention.

[0046] DETAILED DESCRIPTION

[0047] A vehicle 300 in accordance with an embodiment of the present invention is described herein with reference to the accompanying Figure 4. As shown in Figure 4, a windscreen clearing system 200 is installed in the vehicle 300. The system 200 comprises a control system 100 and a windscreen 10.

[0048] With reference to Figure 1 , there is illustrated part of the windscreen 10 of the vehicle 400. The part to the windscreen 10 shown in Figure 1 is located towards the top centre (with reference to the vehicle 400 shown in Figure 4) of the windscreen 10. This part of the windscreen 10 comprises an opaque obscuration band 12 which surrounds a transparent camera aperture 14. It will be understood that the obscuration band 12 may continue along the top of the windscreen 10 (not shown in Figure 1). The lower portion 11 of the windscreen 10 located below the obscuration band 12 is transparent as is well known in the art.

[0049] The camera aperture 14 is shaped to at least partially correspond to the field of view of a set of cameras (not shown) which are mounted inside the vehicle 400. The camera aperture 14 in this example comprises a first portion 18 which is broadly trapezoidal in shape, and two outer portions 16 located on either side of the first portion 18 which are broadly trapezoidal in shape. It will be understood that the shape of the aperture 14 described above and shown in Figure 1 is not essential and can change as best suits the field of view of the camera or cameras which are positioned to within the vehicle 400.

[0050] The windscreen 10 comprises an electrical circuit 20 circuit for heating the camera aperture 14. The electrical circuit comprising a plurality of wires 22 arranged in a pattern which conforms to the shape of the camera aperture 14. As such, in this example, the pattern of the wires 22 has an outline which broadly comprises a first portion 28 which is broadly trapezoidal in shape, and two outer portions 26 located on either side of the central portion 28 which are broadly trapezoidal in shape.

[0051] In the example shown in Figure 1 , the pattern of wires 22 is located entirely within the camera aperture 14. In other examples the pattern of wires 22 may coincide with the edge of the camera aperture 14 and the obscuration band 14, or may overlap the obscuration band 14.

[0052] The pattern of wires 22 shown in the example of Figure 1 comprises a series of concentric generally triangular and / or trapezoidal shapes which broadly follow the shape of the camera aperture 14. However, this configuration is not essential and any pattern of wires may be used as desired. It is not necessary that the pattern of wires has a continuous wire delineating the outermost edge of the pattern. For example, the pattern of wires 22 may comprises a wave shape which varies in amplitude such that the envelope of the shape conforms to the shape of the aperture 14.

[0053] In the example shown in Figure 1 , the electrical circuit 20 comprises a first circuit region 24 and a second circuit region 25. The first circuit region 24 is located in the first portion 18 of the camera aperture 14, and the second circuit region 25 is located in each of the outer portions 16 of the camera aperture 14. The electrical circuit 20 is configured so that the first 24 and second 25 circuit regions are independently operable. This may be achieved by any suitable means known to those skilled in the art.

[0054] With reference to Figure 2, there is illustrated a control system 100 for controlling the windscreen clearing system 200 of the vehicle 300. The control system 100 comprises one or more controller 110. The control system 100 is configured to receive a first input signal 140 indicative of a request to clear a camera aperture of a windscreen. This may be received as a result of a vehicle user requesting windscreen clearing via a user interface (not shown), or as a result of data 135 received from a transparency sensor 105 indicating that the camera aperture 14 is not currently sufficiently transparent. In one example, the transparency sensor may be a vehicle mounted camera with a field of vision that intersects the camera aperture 14. Following receipt of the first input signal 140, the control system 100 is configured to output a first control signal 150 which comprises an instruction to operate the first region 24 of the electrical circuit 20. The control system 100 is also configured to receive a second input signal 141 indicative of the transparency of the first portion 18 of the camera aperture, where the second input signal 141 is derived from data 136 received from the transparency sensor 105. The control system 110 is configured to determine if the transparency of the first portion 18 of the camera aperture 14 satisfies a pre-determined transparency threshold criteria in dependence on the second input signal 141. If the transparency of the first portion 18 of the camera aperture 14 satisfies the pre-determined transparency threshold criteria, the control system is configured to output a second control signal 151 comprising an instruction to operate the second region 25 of the electrical circuit 20. The control system 100 thereby facilitates stepwise operation of the electrical circuit 20 allowing the first portion 18 of the camera aperture 14 to be cleared before the outer portions 16.

[0055] The control system 100 as illustrated in Figure 1 comprises one controller 110, although it will be appreciated that this is merely illustrative. The controller 110 comprises processing means 120 and memory means 130. The processing means 120 may be one or more electronic processing device 120 which operably executes computer-readable instructions. The memory means 130 may be one or more memory device 130. The memory means 130 is electrically coupled to the processing means 120. The memory means 130 is configured to store instructions, and the processing means 120 is configured to access the memory means 130 and execute the instructions stored thereon.

[0056] The controller 1 10 comprises an input means and an output means. The input means may comprise an electrical input of the controller 1 10, and the output means may comprise an electrical output of the controller 305. The input means is arranged to receive the first and second input signals 140, 141 from the user interface and / or transparency sensor 105 as the case may be. The output means is arranged to output the first and second control signals 150, 151 for controlling operation of the electrical circuit 20.

[0057] Figure 3 illustrates a method 50 according to an embodiment of the invention. The method 50 is a method of controlling a windscreen clearing system 200 of a vehicle 300, such as the vehicle 300 illustrated in Figure 4. In a first step 51 of the method 50 a first input signal 140 is received which is indicative of a request to clear the camera aperture 14. In a second step 52 a first control signal 150 is issued which comprises an instruction to operate a first region 24 of the electrical circuit 20 located on or embedded in the camera aperture. In a third step 53 a second input signal 141 indicative of a transparency of a first portion 18 of the camera aperture 14 is received, and in a fourth step 54 it is determined if the transparency of the first portion 18 of the camera aperture 14 satisfies a pre-determined transparency threshold criteria. This determination is made in dependence on the second input signal 141 . In a fifth step 55, if the transparency of the first portion 18 of the camera aperture 14 satisfies the pre-determined transparency threshold criteria, a second control signal 151 is output comprising an instruction to operate a second region 25 of the electrical circuit 20. If in the fourth step 54 it is determined that the transparency threshold criteria is not met, the method returns to the start of the fourth step 54 which repeats until the transparency threshold criteria is met. The method 50 may be performed by the control system 100 illustrated in Figure 2. In particular, the memory 130 may comprise computer-readable instructions which, when executed by the processor 120, perform the method 50 according to an embodiment of the invention.

[0058] A vehicle 5300 in accordance with an embodiment of the present invention is described herein with reference to the accompanying Figure 6. As shown in Figure 6, a backlight 510 is installed in a vehicle 5300.

[0059] Figure 5 shows a schematic view of a vehicle backlight 510. The backlight 510 comprises and electrical circuit 520 for heating the backlight 510. The electrical circuit 520 comprises a pattern of wires 522 which has a first region 524 and a second region 525. The first region 524 of the pattern comprises wires 526 which have a resistance per unit length which is greater than that the wires 527 which form the second region 525 of the pattern.

[0060] The first region 524 of the pattern is broadly trapezoidal in shape and located in a central portion of the backlight 510 such that the area occupied by the first region 524 of the pattern decreases in height from the centre of the first region 524 of the pattern towards the edges of the first region 524 of the pattern. It will be understood that this configuration is not essential and that the first region 524 of the pattern of wires 522 may be of any suitable shape.

[0061] In the example shown in Figure 5, the first region 524 of the pattern of wires 522 is located between an upper (with respect to Figure 5) first sub-region 528 and a lower second sub-region 529 of the second region 525 of the pattern. Therefore, in the example of Figure 5, the second region 525 of the pattern is not continuous. In an alternative example (not shown), the first region of the pattern 524 may be surrounded by the second region

[0062] 525 of the pattern.

[0063] The wires 526 which form the first region 524 of the pattern have a different thickness to the wires 527 which form the second region 525 of the pattern. In the example of Figure 5, the wires 526, 527 forming the first 524 and second 525 regions of the pattern of wires 522 respectively comprise the same material. The wires 526 forming the first region 524 of the pattern are thinner than the wires 527 forming the second region 525 of the pattern with the result that the resistance per unit length of the wires 526 forming the first region 524 of the pattern is greater than the resistance per unit length of the wires 527 which form the second region 525 of the pattern.

[0064] In alternative examples, the material composition of the wires 526, 527 forming the first 524 and second 525 regions of the pattern of wires 522 respectively may differ such that the relative thickness of the wires 526, 527 in each region of the pattern of wires 522 may differ from the example shown in Figure 5. If the resistivity of the wires 526, 527 forming the first 524 and second 525 regions of the pattern of wires 522 differ, the wires

[0065] 526 forming the first region 524 of the pattern may have the same thickness as the wires 527 which form the second region 525 of the pattern, may have a greater thickness than the wires 527 which form the second region 525 of the pattern, or may have a lesser thickness than the wires 527 which form the second region 525 of the pattern, provided in each case that the resistance per unit length of the wires 524 forming the first region of the pattern is greater than that the resistance per unit length of the wires 527 which form the second region 525 of the pattern. Similarly, the wires 526, 527 forming the first 524 and second 525 regions of the pattern of wires 522 respectively may have different cross-sectional shapes. Nonetheless, as long as the resistance per unit length of the wires 524 forming the first region of the pattern is greater than that the resistance per unit length of the wires 527 which form the second region 525 of the pattern any suitable combination of wire material, size and / or shape may be used.

[0066] In the example shown in Figure 5, the average distance between the wires 526 forming the first region 524 of the pattern is less than the average distance between the wires 527 forming the second region 525 of the pattern. In addition, the wires 526 forming the first region 524 of the pattern comprise a plurality of groups 530 of electrically parallel wires which extend between a first portion 532 of wire forming a first electrical path 531 in the second region 525 of the pattern and a second portion 534 of wire forming the first electrical path 531 in the second region 525 of the pattern. For clarity only one electrical path 531 and one group 530 of parallel wires are labelled in Figure 5. It will be understood that each wire 527 in the second region 525 of the pattern of wires 522 that is split by a group 530 of wires 526 in the first region 524 of the pattern of wires 522 is similarly arranged. In some cases a wire 527 in the second region 525 of the pattern of wires 522 may be split by more than one group 530 of wires from the first region 524 of the pattern of wires. Such a wire is labelled by reference numeral 536 as an example.

[0067] The group 530 of electrically parallel wires comprise three electrically parallel wires in the example of Figure 5. However, it will be understood that any number of electrically parallel wires may be used in any group 530 as desired. In another example, as shown by wires 538, 539 in Figure 5, a wire from the first region 524 of the of the pattern of wires may be arranged electrically in parallel with at wire from the second region 525 of the pattern of wires 522.

[0068] It is often desirable to defrost a particular portion of a backlight more rapidly that the remainder of the backlight. For example, some authorities set a rear view mirror field of view requirement requiring that a particular height and width at a set distance behind the rear of the vehicle be visible. If a portion of the backlight corresponding to the shape of the intersection between the backlight and the predetermined rear view mirror field of view requirement is defrosted more rapidly than the remainder of the backlight, the vehicle will become ready for safe operation more rapidly. Because the wires 526 in the first region 524 of the pattern of wires 522 have a greater resistance per unit length than the wires 527 in the second region 525 of the pattern of wires, the backlight in the portion of the backlight 510 occupied by the first region 524 of the pattern of wires 522 will defrost more rapidly than the portion of the backlight 510 occupied by the second region 525 of the pattern of wires 522 if a suitable distribution of wires 522, such as that shown in Figure 5, is utilised. It will be understood that other arrangements of wires 522 in first and second regions 524, 525 may be used to the same effect. The particular shape of the portion ofthe backlight 510 corresponding to the shape ofthe intersection between the backlight and the predetermined rear view mirror field of view requirement will differ depending on the particular, predetermined, vehicle design specification. It is typically the case that portion of the backlight 510 corresponding to the shape of the intersection between the backlight 510 and the predetermined rear view mirror field of view requirement has a surface area which is less than the remainder of the backlight 510. Therefore, the area of the backlight 510 occupied by the first region 524 of the pattern of wires 522 is less than the area of the backlight 510 occupied by the second region 525 of the pattern of wires 522. The backlight 510 may be configured so that the area of the backlight 510 occupied by the first region 524 of the pattern of wires 522 is less than the area of the backlight 510 occupied by the second region 525 of the pattern of wires 522 regardless of whether the smaller area occupied by the first region 524 of the pattern of wires 522 is deliberately designed to conform to the shape of the intersection between the backlight 510 and a predetermined rear view mirror field of view requirement.

[0069] It will be appreciated that various changes and modifications can be made to the present invention without departing from the scope of the present application. In particular, the present invention has been described in the context of a backlight 510 of a vehicle 5300. It will be appreciated that the invention may be used with any vehicle window. A backlight 510 of a vehicle 5300 may be referred to as a rear windscreen, or tailgate glass. Further aspects of the invention are described herein with reference to the following numbered clauses:

[0070] Clause 1.A vehicle window, the window comprising an electrical circuit for heating the window, wherein the electrical circuit comprises a pattern of wires having a first region and a second region, wherein the wires forming the first region of the pattern have a resistance per unit length greater than that the wires forming the second region of the pattern, and wherein the area of the window occupied by the first region of the pattern is less than the area of the window occupied by the second region of the pattern.

[0071] Clause 2. The vehicle window according to Clause 1 , wherein the first region of the pattern is located in a central portion of the window.

[0072] Clause 3. The vehicle window according to any preceding Clause, wherein the first region of the pattern is surrounded by the second region of the pattern.

[0073] Clause 4. The vehicle window according to Clause 1 or 2, wherein the second region of the pattern comprises a first sub-region and a second sub-region, wherein the first region of the pattern is located between the first and second sub-regions of the second region of the pattern.

[0074] Clause 5. The vehicle window according to any preceding Clause, wherein the area occupied by the first region of the pattern decreases in height from the centre of the first region of the pattern towards the edges of the first region of the pattern.

[0075] Clause 6. The vehicle window according to any preceding Clause, wherein the wires forming the first region of the pattern have a first thickness and the wires forming the second region of the pattern have a second thickness. Clause 7. The vehicle window according to Clause 6, wherein the wires forming the first region of the pattern are thinner than the wires forming the second region of the pattern.

[0076] Clause 8. The vehicle window according to any preceding Clause, wherein the wires forming the first region of the pattern comprise a different material composition to the wires forming the second region of the pattern.

[0077] Clause 9. The vehicle window according to any preceding Clause, wherein wires forming the first region of the pattern have a different cross-sectional area to the wires forming the second region of the pattern.

[0078] Clause 10. The vehicle window according to any preceding Clause, wherein the average distance between the wires forming the first region of the pattern is less than the average distance between the wires forming the second region of the pattern.

[0079] Clause 11 . The vehicle window according to any preceding Clause, wherein at least some of the wires forming the first region of the pattern comprise a plurality of electrically parallel wires which extend between a first portion of wire forming a first electrical path in the second region of the pattern and a second portion of wire forming the first electrical path in the second region of the pattern.

[0080] Clause 12. The vehicle window according to Clause 11 , wherein the plurality of electrically parallel wires comprise three electrically parallel wires.

[0081] Clause 13. A vehicle backlight, wherein the backlight comprises a window according to any preceding Clause, and wherein the shape of the first region of the pattern of wires conforms to the shape of the intersection between the backlight and a predetermined rear view mirror field of view requirement in a predetermined vehicle design specification.

[0082] Clause 14. A vehicle comprising the window according to any one of Clauses 1 to 12, or the backlight of Clause 13.

[0083] It will be appreciated that various changes and modifications can be made to the present invention without departing from the scope of the present application.

Claims

CLAIMS1 . A windscreen for a vehicle, wherein the windscreen comprises a camera aperture defined by a transparent area surrounded by an opaque region and an electrical circuit for heating the camera aperture(14), the electrical circuit comprising one or more wires arranged in a pattern, wherein the pattern conforms to the shape of the camera aperture.

2. The windscreen according to claim 1 , wherein the pattern is located entirely within the camera aperture.

3. The windscreen according to any preceding claim, wherein the shape of the camera aperture comprises one or more substantially triangular, and / or one or more substantially trapezoid portions.

4. The windscreen according to any preceding claim, wherein an outline of the pattern defines at least one substantially triangular and / or trapezoidal shape.

5. The windscreen according to any preceding claim, wherein the pattern comprises a series of concentric substantially triangular and / or trapezoidal shapes.

6. The windscreen according to any preceding claim, wherein the electrical circuit comprises a first circuit region and a second circuit region, wherein the electrical circuit is configured so that the first and second circuit regions are independently operable.

7. A control system for controlling a windscreen clearing system of a vehicle, the control system comprising one or more controller, the control system comprising one or more processors collectively configured to: receive a first input signal indicative of a request to clear a camera aperture of a windscreen; output a first control signal, wherein the first control signal comprises an instruction to operate a first region of an electrical circuit located on or embedded in the camera aperture; receive a second input signal indicative of a transparency of a first portion of the camera aperture; determine if the transparency of the first portion of the camera aperture satisfies a predetermined transparency threshold criteria in dependence on the second input signal; and if the transparency of the first portion of the camera aperture satisfies the pre-determined transparency threshold criteria, output a second control signal comprising an instruction to operate a second region of the electrical circuit.

8. A windscreen clearing system comprising the control system of claim 7 and a windscreen according to any one of claims 1 to 6.

9. A vehicle comprising a windscreen according to any one of claims 1 to 6, the control system of claim 7, or the system of claim 8.

10. A method for controlling a windscreen clearing system of a vehicle, the method comprising: receiving a first input signal indicative of a request to clear a camera aperture; outputting a first control signal, wherein the first control signal comprises an instruction to operate a first region of an electrical circuit located on or embedded in the camera aperture; receiving a second input signal indicative of a transparency of a first portion of the camera aperture; determining if the transparency of the first portion of the camera aperture satisfies a predetermined transparency threshold criteria in dependence on the second input signal; and if the transparency of the first portion of the camera aperture satisfies the pre-determined transparency threshold criteria, outputting a second control signal comprising an instruction to operate a second region of the electrical circuit.

11. Computer readable instructions which, when executed by a computer, are arranged to perform a method according to claim 10.

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