DE102019207011B4 - Lens for a motor vehicle and system comprising the lens - Google Patents

Abstract

A lens (110) for a motor vehicle (105), the lens (110) comprising: a first glass layer (160), a second glass layer (165), and a plastic layer (155) between the glass layers (160, 165); wherein a predetermined portion (135) of the lens (110) is set up for the passage of light to an optical sensor (130); a thermal isolator (150) configured to reduce heat flow along the lens (110) from the portion (135); and a heater (145) attached to the lens (110) within the portion (135); characterized in that one of the glass layers (160, 165) has a reduced thickness or has been removed in the area of the thermal insulator (150), and a material (170) which is thermally less conductive than one of the glass layers (160, 165), forms the thermal insulator (150) and fills up the reduced thickness or erosion, the material (170) being a polyester or an epoxy resin, the plastic layer (155) remaining unchanged or having a reduced thickness in the region of the thermal insulator (150).

Description

The present invention relates to a sensor mounted on a lens on a motor vehicle. In particular, the invention relates to improving the optical properties of the viewing pane in the area of the sensor.

A motor vehicle includes a windshield, on the inside of which a sensor is attached that is set up to optically detect an area in front of the motor vehicle. The front screen usually comprises glass and in unfavorable weather conditions can be covered with ice, snow or hoarfrost on the outside, so that the environmental detection of the sensor can be impaired. The windscreen can be actively heated to remove such weather-related deposits.

If the motor vehicle is in normal operation, the entire windscreen or a section can be heated using heated air. For faster heating, the windscreen can be provided with heating wires through which an electric current can be passed. However, such heating wires can change the optical properties of the front pane and in particular cause an uneven change in the refractive index, so that the optical path to the sensor can be disturbed and the environmental detection can be subject to distortion. A heating element attached to the front screen can be inefficient because the heat provided can be dissipated laterally through the glass front screen, so that the area relevant to the sensor is heated less. Heating by means of infrared radiation has also not proven itself due to limited performance and the optical distortions that may be caused.

DE 10 2007 012 993 A1 proposes providing a cut-out in a windshield for an IR camera mounted inside a vehicle.

DE 10 2004 054 161 B4 relates to an infrared light detection area of a windshield of a vehicle. A heating device is provided to counteract fogging or icing of the windshield in the detection area.

GB 2 271 139 A shows a windshield with an insert with increased transmissivity for infrared radiation.

As relevant prior art are also the US 2019/0061481 A1 , the DE 103 33 978 A1 , the DE 11 2015 004 685 T5 and the DE 10 2017 119 900 A1 to call.

One of the objects on which the present invention is based is to specify an improved technique for heating a viewing window of a motor vehicle in the area of an optical sensor. The invention solves this problem by means of the subject matter of the independent claims. Subclaims reflect preferred embodiments.

A lens for a motor vehicle includes a glass layer. A predetermined section of the viewing pane is set up for the passage of light to an optical sensor. Furthermore, the visor includes a thermal insulator which is set up to reduce a heat flow emanating from the section along the visor.

It has been recognized that thermal energy used to heat the portion of the lens can be dissipated through the glass layer along the lens so that it is not available to the portion. A flow of heat from the section into the surrounding glass layer can be reduced by the thermal insulator. As a result, the section can be heated faster or more intensely. It may take a shorter time to clear the section of snow, ice or hoarfrost, for example. The sensor can be fully used more quickly. The sensor can include a camera, for example, and can be used in general to control the motor vehicle, optionally also on an autonomously controllable motor vehicle.

It is preferable that the thermal insulator encloses the section. Thus, heat can be further improved concentrated at the portion. The enclosing is preferably complete, so that as far as possible there is no thermal bridge in any direction along the visor.

According to the invention, the viewing pane comprises a plastic layer which lies between an inner glass layer and an outer glass layer. Such a material is known as laminated safety glass (VSG).

According to the invention, the inner glass layer or the outer glass layer has a reduced thickness in the area of the thermal insulator or has been removed. A considerable insulation effect can already be achieved by reducing the cross-section of the inner glass layer. The outer glass layer and/or the plastic layer can remain unchanged. If the outer glass layer remains, resistance to Abrasion or scratching will remain high. If the plastic layer remains, its influence on the rupture behavior of the lens, especially when a person or an object impacts, can remain unchanged.

A thermal conductivity of glass is usually about an order of magnitude higher than that of the plastic layer. According to the invention, the plastic layer has a reduced thickness in the area of the thermal insulator or remains unchanged.

In the section designed for the passage of light itself, a high thermal conductivity along the viewing pane is generally desired in order to conduct heat from the heating device and to ensure good defrosting behavior. In this area there is preferably no change in the viewing pane. However, the thickness of glass or plastic can also be reduced or removed here, for example for production or safety reasons.

According to the invention, a material that is less thermally conductive than one of the glass layers fills in the reduced thickness or erosion. The material is filled in as a liquid or pasty and later hardens to form a solid or later binds to form a solid. According to the invention, a polyester or an epoxy resin is used. The material is preferably colorless and/or transparent, at least after curing, so that the optical properties of the viewing panel are impaired as little as possible.

In one embodiment, more material is filled in than removed or saved by the reduced thickness or erosion. The viewing pane can thus be slightly convex in shape in the area of the thermal insulator or on the section.

According to the invention, a heating device is attached to the viewing pane within the section. The heating device is preferably in contact with the viewing window and can enclose the section on an inside of the thermal insulator. Heat provided by the heater can be kept from dissipating in a direction away from the portion, so that the portion can be heated evenly in an improved manner. The heating device is preferably formed by an electrically conductive material that can be heated by means of an electric current.

The lens may include one of a front window, a rear window, and a side window of the automobile. In a further variant, a skylight or another window can also be affected.

In another embodiment, the material attached to the lens is opaque. The opaque material is preferably attached to the glass pane over a large area in such a way that it can be seen from the outside of the viewing pane. This allows outside sunlight to be used to heat the lens near the area.

A system includes a lens as described herein and a sensor assembly attached to the portion. The sensor arrangement includes an optical sensor, for example a camera, a depth camera or an optical range finder. Optionally, a heating device is attached to the sensor arrangement, which is set up to heat the section, for example by means of infrared radiation.

• 1 ein beispielhaftes System zur Verwendung an Bord eines Kraftfahrzeugs; und
• 2 einen Schnitt durch eine beispielhafte Sichtscheibe für ein Kraftfahrzeug darstellt.

The invention will now be described in more detail with reference to the attached figures, in which:

• 1 an exemplary system for use on board a motor vehicle; and
• 2 represents a section through an exemplary lens for a motor vehicle.

1 shows an exemplary system 100 for use on board a motor vehicle 105. The system 100 comprises a visor 110 and a sensor arrangement 115. The visor 110 is set up to an interior 120, in which a passenger of the motor vehicle 105 can stay, from an exterior space Separate 125, wherein a line of sight between both the interior 120 and the exterior 125 should be maintained. 1 shows an exemplary embodiment with a windshield 110. The interior 120 is in a lower area of the representation and the exterior 125 in an upper area. In terms of 1 a direction of travel of motor vehicle 105 runs from bottom to top.

The sensor arrangement 115 preferably comprises at least its optical sensor 130, for example a brightness sensor, a camera or a sensor for solar radiation. A plurality of sensors 130 can also be provided, which have different orientations or opening angles or can be sensitive to light of different wavelengths. In one embodiment, the sensor array 115 includes a light source.

Light that is exchanged between the sensor arrangement 115 and the outside space 125, falls through a predetermined section 135 of the viewing pane 110. An optional lens hood 140 is set up to shield light that is incident or exiting from the side in the interior. The lens hood 140 can extend in the manner of a funnel between the sensor arrangement 115 and an inner surface of the visor 110 in the area of the section 135 and optionally fulfill a holding function for the sensor arrangement 115 on the visor 110 . For this purpose, the lens hood 140 can be glued to the viewing pane 110 .

More preferably, a heating device 145 is provided on the viewing panel 110 which is set up to heat the viewing panel 110 in the area of the section 135 . In the present case, the heating device 145 comprises an electrically conductive material that lies as flat as possible on the viewing pane 110 and can have connections for connecting to a power source. The heating device is preferably located outside of section 135 in order not to impair optical properties of sensor arrangement 115, but at the same time as close as possible to section 135 in order to heat section 135. The purpose of the heating device 145 is to defrost the section 135 if necessary, ie to heat it to such an extent that ice, snow or hoarfrost in the outer space 125 is converted into water and also that the water located there evaporates or evaporates.

In order to prevent heat from being dissipated along the lens 110, it is proposed to provide a thermal isolator 150 which is attached in such a way that it restricts heat flow from the heater 145 in a direction away from the section 135 as much as possible. For this purpose, the thermal insulator 150 can be on a side of the heating device 145 remote from the section 135 and in particular can be attached to or in the viewing pane 110 .

der thermische Widerstand der Kunststoffschicht 155 ist üblicherweise bei ca. $\mathrm{0,2}\frac{W}{m\cdot K}.$

Der thermische Isolator 150 kann gebildet werden, indem eine oder mehrere der Schichten 155-165 in ihrer Stärke (also ihrer Ausdehnung zwischen dem Innenraum 120 und dem Außenraum 125, dieses Maß wird auch Dicke genannt) reduziert wird. Die Reduktion kann bis auf null geführt werden, sodass die Schicht 155-165 in diesem Bereich unterbrochen ist. Im Bereich der Reduktion kann sich Luft ansammeln, die eine Wärmeleitfähigkeit aufweisen kann, die mit ca. $\mathrm{0,03}\frac{W}{m\cdot K}$

üblicherweise noch deutlich unter jener der Kunststoffschicht 155 liegt. Alternativ dazu kann im Bereich der Reduktion ein Material 170 eingefüllt werden, das eine Wärmeleitfähigkeit aufweist, die bevorzugt geringer als die der Glasschichten 160, 165 ist.The viewing pane 110 is preferably designed as laminated safety glass and comprises a plastic layer 155 which lies directly between an inner glass layer 160 and an outer glass layer 165 and is connected to these over a large area. The plastic layer 155 can be produced from a thermoset, for example CR-39, an epoxy and/or an acrylic. The glass layers 160, 165 usually have relatively low thermal resistances in the range of approx. $0.7-1.0\frac{W}{m\cdot K};$

the thermal resistance of the plastic layer 155 is usually approx. $0.2\frac{W}{m\cdot K}.$

The thermal insulator 150 can be formed by reducing one or more of the layers 155-165 in their thickness (ie their extension between the interior 120 and the exterior 125, this dimension is also called thickness). The reduction can be taken down to zero, so that the layer 155-165 is interrupted in this area. Air can accumulate in the reduction area, which can have a thermal conductivity that is approx. $0.03\frac{W}{m\cdot K}$

is usually well below that of the plastic layer 155. As an alternative to this, a material 170 which has a thermal conductivity which is preferably lower than that of the glass layers 160, 165 can be filled in in the area of the reduction.

2 shows a section through an exemplary lens 110 for a motor vehicle 105. In the embodiment shown, the sensor 130 is in direct contact with the lens 110 and a lens hood 140 is not provided. One or more heaters 145 are adjacent portion 135 through which light from exterior 125 is intended to pass through visor 110 onto sensor 130 . A heating device 145 is preferably provided on the side of the interior space 120 and more preferably attached to the inner glass layer 160 in a planar manner.

In order to prevent heat from flowing away from the heating device 145 in 2 one or more thermal isolators 150 may be provided to decrease to the right and left. The heating device 145 is located along the surface of the visor 110 preferably between the section 135 and the thermal isolator 150. From the section 135, the thermal isolator 150 is thus on a remote side of the heating device 145.

The inner glass layer 160, the plastic layer 155 and/or the outer glass layer 160 can each range in thickness between the inner space 120 and the outer space 125 (in 2 recognizable as a vertical extension) may be reduced or completely interrupted. Material 170 can be filled in this area in order to at least approximately restore the strength of the visor 110 . In a preferred embodiment, only the inner glass layer 160 is reduced in thickness or interrupted. Optionally, the plastic layer 155 can also be reduced in thickness or interrupted. The outer glass layer 165 can be unchanged or less drastically reduced in thickness in order to obtain a mechanical load capacity in the outer space 125 .

in the in 2 In the illustrated embodiment, inner glass layer 160 and outer glass layer 165 are each breached and filled with material 170 to form thermal insulator 150 .

Reference List

100

system

105

motor vehicle

110

window

115

sensor arrangement

120

inner space

125

outdoor space

130

sensor

135

section

140

lens hood

145

heating device

150

thermal insulator

155

plastic layer

160

inner glass layer

165

outer glass layer

170

material

175

opaque layer

Claims (6)

A lens (110) for a motor vehicle (105), the lens (110) comprising: a first glass layer (160), a second glass layer (165), and a plastic layer (155) between the glass layers (160, 165); wherein a predetermined section (135) of the lens (110) is set up for the passage of light to an optical sensor (130); a thermal isolator (150) configured to reduce heat flow along the lens (110) from the portion (135); and a heater (145) attached to the lens (110) within the portion (135); characterized in that one of the glass layers (160, 165) has a reduced thickness or has been removed in the area of the thermal insulator (150), and a material (170) which is thermally less conductive than one of the glass layers (160, 165), forms the thermal insulator (150) and fills up the reduced thickness or erosion, the material (170) being a polyester or an epoxy resin, the plastic layer (155) remaining unchanged or having a reduced thickness in the region of the thermal insulator (150). viewing window (110). claim 1 , wherein the thermal insulator (150) encloses the portion (135). A lens (110) according to any one of the preceding claims, wherein the material (170) is optically transparent. viewing window (110). claim 1 or 2 , wherein the material (170) is opaque. A lens (110) according to any one of the preceding claims, wherein the lens (110) comprises one of a front window, a rear window and a side window of the motor vehicle (105). A system comprising a lens (110) according to any one of the preceding claims and a sensor assembly (115) attached to the portion (135).

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