Thermoplastic interlayer providing optical correction and a laminated vehicle window having the same

Abstract

The present invention relates to a laminated panel made of thermoplastic material for a vehicle window comprising an interlayer with an inner wall (32) and an outer wall (34) extending adjacent to each other in a wedge angle (a) form in a cross-sectional shape, wherein a local flattened region (35) is adjusted such that providing an optical correction against the distortion of the wedge angle (a) in the inner and / or outer wall (32, 34).

Description

[0001] DESCRIPTION

[0002] THERMOPLASTIC INTERLAYER PROVIDING OPTICAL CORRECTION AND A LAMINATED VEHICLE WINDOW HAVING THE SAME

[0003] TECHNICAL FIELD

[0004] The present invention relates to a thermoplastic interlayer and a laminated panel structure having this interlayer, particularly a vehicle window and its production method.

[0005] BACKGROUND OF THE ART

[0006] A vehicle window is a laminated panel structure that includes an outer panel, an inner panel, and a thermoplastic interlayer containing PVB provided directly adjacent between them. When light passes from one medium to another, its angle changes according to the refractive index of the medium it passes through. When light advancing from inside the vehicle hits the glass, part of it reflects and part of it refracts into the glass. As the light progresses through the glass and exits into the external environment, part of it reflects and the remaining part transmits to the outside. Because the reflection angles of light beams reflected from the inner and outer surfaces of the glass are different, particularly in vehicle windows with head-up displays (HUD), a secondary image can be formed. To eliminate this, the laminated panel structure has been modified, and a wedge-shaped thermoplastic interlayer with a cross- sectional profile tapering from top to bottom has been used. The wedge shape of the interlayer, with its thickness profile tapering from top to bottom, modifies the optical properties of the glass’s light reflection, causing the double images to overlap. Thus, the projection image reflected onto the inner surface of the vehicle window is reduced to a single image. However, when a camera is mounted on the same vehicle window to enable autonomous driving through Advanced Driver Assistance Systems (ADAS), optical distortions occur in the camera image due to the varying thickness of the interlayer in the vertical direction.

[0007] EP3458259 describes a vehicle window with a laminated panel structure for a vehicle with a head-up display and a forward-facing camera. The system for a vehicle comprises a window assembly adapted to be installed within the front opening of the vehicle frame. The window assembly includes an inner transparent sheet, an outer transparent sheet, and an interlayer of polymer disposed between the inner transparent sheet and the outer transparent sheet. The interlayer is configured wherein a first portion of the interlayer has a first variable thickness profile and wherein a second portion of the interlayer has a second variable thickness profile, with the first portion of the interlayer distinct from the second portion of the interlayer. The system also includes a front-facing camera positioned within the vehicle for receiving light transmissions from an object located outside the vehicle through the first portion. The system may also include a head up display- associated with the second portion of the interlayer.

[0008] OBJECT OF THE INVENTION

[0009] The object of the invention is to increase the imaging accuracy in a vehicle window with a laminated panel with a thermoplastic interlayer of gradually varying thickness.

[0010] In order to achieve above objective, the invention comprises a laminated panel made of thermoplastic material for a vehicle window, comprising an interlayer with an internal wall and an external wall extending adjacent to each other in a wedge angle form in a cross-sectional shape, and it further comprises a local flattened region adjusted to provide optical correction against the distortion of the wedge angle in the internal and / or external wall. The flattened region, which compensates for the optical distortion created by the wedge angle on the transparent laminated panel, helps a camera or lens placed behind the flattened region to obtain a clearer image when the laminated panel is used in a vehicle window. This increases the performance of camera-based systems such as Advanced Driver Assistance Systems (ADAS) and autonomous driving systems and offers a safer driving experience when adapted to a vehicle with a vehicle window.

[0011] Preferably, the body of the interlayer is selected from the group consisting of polyvinyl butyral (PVB), polyurethane, ethylene vinyl acetate, ionomer resin, or their combination. The mentioned products are thermoplastic materials with suitable optical and mechanical properties for the body of the interlayer to be used in a vehicle window.

[0012] Preferably, the flattened region is in a depression form. In this case, the flattened region can be precisely formed on the inner or outer wall of the wedge-shaped interlayer, for example, by applying pressure or by molding the interlayer.

[0013] Preferably, the flattened region is adjusted near a thick upper edge of the inner wall. This ensures sufficient mechanical strength against internal stresses that the flattened region will create on the laminated interlayer and prevents cracking or similar damage. Preferably, the base part of the flattened region is adjusted to form a counter wedge angle equal to the wedge angle relative to the corresponding inner and / or outer wall. This compensates for the optical distortion caused by the wedge angle on the interlayer by refracting the light in the opposite direction in the flattened region, ensuring clarity.

[0014] A preferred application includes a production method for a laminated panel as described above. Here, the depression region is obtained by applying an ironing process to the inner and / or outer wall. The ironing process refers to the simultaneous application of heat and pressure, which provides plastic shaping to the laminated panel.

[0015] Preferably, the ironing process involves heating the interlayer to an ironing temperature range of 40-80°C in advance and pressing it with an ironing element having a shape slightly larger than the depression region. The selected temperature range has been found to optimize the optical properties without causing structural damage to the interlayer body.

[0016] Preferably, in the ironing process, the ironing element is adjusted to apply pressure to the interlayer in the range of 1 to 5 bar. The selected pressure value prevents microcracks during the thermoplastic shaping of the interlayer and improves optical properties.

[0017] Preferably, a mechanical actuator is adjusted to compress the ironing element to the interlayer at the determined pressure value. This allows precise control of achieving the desired optical properties in the interlayer.

[0018] Preferably, the surface of the ironing element in contact with the interlayer contains a coating layer of Teflon or similar or a polytetrafluoroethylene. This prevents thermoplastic interlayers, particularly those like PVB, from sticking to the application surface during plastic shaping.

[0019] A preferred configuration includes a laminated vehicle window containing an interlayer as described above. The vehicle window includes an outer panel resting along an inner wall corresponding to the outer wall of the interlayer and an inner panel at least partially resting along the outer wall corresponding to the inner wall of the interlayer. In this way, the laminated vehicle window is suitable for use in both head-up display and functional devices with optical sensors like cameras to obtain accurate images.

[0020] Preferably, the vehicle described above includes a camera adjusted to look at the flattened region from its lens. This allows the forward-facing camera to capture a clear image without the need for additional software or optical elements for correction. Preferably, the flattened region is adjusted perpendicular to a lens axis passing through the center of the camera lens. This has been found to provide the optimal clarity for the camera.

[0021] BRIEF DESCRIPTION OF THE FIGURES

[0022] Figure 1 is a cross-sectional side view of a vehicle window with a laminated panel structure and a camera aligned with the inner panel of the vehicle.

[0023] Figure 2 is a front view of a representative construction of a PVB interlayer used in a laminated vehicle window.

[0024] Figure 3 is a schematic side cross-sectional view of a representative construction related to the production of the interlayer.

[0025] DETAILED DESCRIPTION OF THE INVENTION

[0026] In this detailed description, the invention and its preferred embodiments are explained solely for better understanding of the subject matter without limitation.

[0027] In Figure 1 , a vehicle windshield partially shown in cross-section is adapted with a camera (1 ) at the front. The vehicle windshield includes an inner panel (10) with a thickness of 0.7- 2.5 mm made of glass, an outer panel (20) with a thickness of 0.7-2.5 mm made of glass, and an interlayer (30) made of polyvinyl butyral (PVB) with a thickness of approximately 0.76 mm, forming a laminated panel (10) with a total thickness of 2.5-6 mm. The inner panel (10) is trapezoidal and has an inwardly curved inner wall (12).

[0028] Here, the terms inner and outer for the panels (10, 20) respectively refer to the corresponding direction of the transparent panels concerning the driver’s compartment of the vehicle when the laminated vehicle window is mounted on the front frame of the vehicle chassis (not shown). Thus, when the vehicle window is mounted, the inner panel (10) faces inward and partially covers the passenger compartment of the vehicle, and the outer panel (20) faces outward.

[0029] In the head-up display system (HUD) (not shown), to reduce ghost image formation, the interlayer (30) is produced in a wedge-shaped cross-section tapering from top to bottom. The wedge angle (a) is determined to be 0.026°. In this structure, the inner wall (32) of the interlayer (30) facing the inner panel (10) makes a smaller angle compared to the outer wall (34) facing the outer panel (20) relative to the vehicle’s interior. For example, the inner wall (32) forms an angle of 3 degrees with the corresponding inner panel’s (10) outer wall (14), while the outer wall (34) forms an angle of 5 degrees with the corresponding outer panel’s (20) inner wall (22). This situation causes light refraction along the lens axis (x) of the camera (1 ) passing through the center of the forward-facing lens (2) in a laminated vehicle window with an interlayer (30) having an untreated wedge shape and causes the lens (2) to transmit an optically distorted image to the camera (1). The solution proposed in the invention resolves this issue with a flattened region (35) applied to the inner wall (32) of the interlayer (30) adhered to the outer wall (14) of the inner panel (10). The flattened region (35) has at least the width of the lens (2) and is in the form of a cylindrical depression entering the inner wall (32) along the lens axis (x). The flattened region (35) has a planar base part (36), and the counter wedge angle (o’) formed with the inner wall (32) is equal and opposite to the wedge angle (a). In the example, the counter wedge angle (o’) is determined to be 0.026°. The base part (36) of the depressed flattened region (35) extends inward from the inner wall (32) of the interlayer (30) parallel to the lens axis (x). The circular cross-section of the flattened region (35) is aligned coaxially with the lens axis (x). On the other hand, the outer wall (34) of the interlayer (30) placed on the inner wall (22) of the outer panel (20) is completely flat and sits entirely on the inner wall (22) of the flat outer panel (20) without any protrusion or recess. Similarly, the outer wall (24) of the outer panel (20) is flat and extends parallel to the inner wall (22). The inner wall (12) of the inner panel (10) parallel to the outer wall (14) is in a flat form and extends at an angle to the camera lens (2). Here, the angle of the inner panel (10) relative to the vehicle chassis and the supporting camera (1) is determined by standards.

[0030] In Figure 2, the interlayer (30) is shown from the front view of its outer wall (34). The trapezoid-shaped interlayer (30) is approximately the same size as the inner panel (10) and the outer panel (20). The base part (36) of the flattened region (35) is positioned in a circular form near the upper edge (33) of the interlayer (30), known as the sensor window area.

[0031] In Figure 3, the production method of the interlayer (30) is schematically shown. Here, the thin and flat interlayer (30) cut from PVB material in a trapezoid form is placed from its inner wall (32) to an ironing element (40). A mechanical actuator (44) having a mold-forming cavity and an electric heater (not shown) is placed in the cavity with a Teflon coating layer (42). The cavity has a core extending outward in the form of the flattened region (35). The core (46) forms a counter wedge angle (o’). A fixed pressure plate (48) with a flat panel structure rests on the outer wall (34) of the interlayer (30) placed in the cavity. The mechanical actuator (44) advances axially towards the pressure plate (48), compressing the interlayer (30). The core (46) heated by the electric heater rests on the inner wall (32) of the interlayer (30), thermoplastically forming the flattened region (35) in the depression shape on the interlayer (30). The PVB interlayer (30) cools down, and the vehicle window production is carried out by creating a laminated panel structure between the inner panel (10) and the outer panel (20) using known production methods.

[0032] REFERENCE NUMBERS

[0033] 1 Camera 35 Flattened region

[0034] 2 Lens 36 Base part

[0035] 10 Inner panel 38 Skirt

[0036] 12 Inner wall 40 Ironing element

[0037] 14 Outer wall 42 Coating layer

[0038] 20 Outer panel 44 Mechanical actuator

[0039] 22 Inner wall 46 Core

[0040] 24 Outer wall 48 Pressure plate

[0041] 30 Interlayer a Wedge angle

[0042] 32 Inner wall a’ Counter wedge angle

[0043] 33 Upper edge x Lens axis

[0044] 34 Outer wall

Claims

CLAIMS1. A laminated panel made of thermoplastic material for a vehicle window comprising an interlayer with an inner wall (32) and an outer wall (34) extending adjacent to each other in a wedge angle (a) form in a cross-sectional shape, characterized by a local flattened region (35) adjusted such that providing an optical correction against the distortion of the wedge angle (a) in the inner and / or outer wall (32, 34).

2. A laminated panel according to claim 1 , wherein the body of the interlayer (30) is selected from the group consisting of polyvinyl butyral, polyurethane, ethylene vinyl acetate, ionomer resin, or their combination.

3. A laminated panel according to any of the preceding claims, wherein the flattened region (35) is in a depression form.

4. A laminated panel according to any of the preceding claims, wherein the flattened region (35) is adjusted near a thick upper edge (33) of the inner wall (32).

5. A laminated panel according to any of the preceding claims, wherein the base part (36) of the flattened region (35) is adjusted to form a counter wedge angle (o’) equal to the wedge angle (a) relative to the corresponding inner and / or outer wall (32, 34).

6. A production method for production of a laminated panel according to any of the preceding claims, comprising the step of obtaining the depression region (35) by applying an ironing process to the inner wall (32) and / or outer wall (14).

7. A production method according to claim 6, wherein the ironing process comprising the step of heating the interlayer (30) to an ironing temperature range of 40-80°C in advance and pressing it with an ironing element (40) having a shape slightly larger than the depressed region (35).

8. A production method according to claim 7, wherein the ironing element (40) is adjusted to apply pressure in the range of 1 to 5 bar to the interlayer (30).

9. A production method according to claim 8, wherein a mechanical actuator (44) is adjusted to compress the ironing element (40) to the interlayer (30) at the determined pressure value.

10. A production method according to claims 6-8, wherein the surface of the ironing element (40) in contact with the interlayer (30) is containing a coating layer (42) of polytetrafluoroethylene.

11. A laminated vehicle window comprising an interlayer according to claims 1-4, wherein an outer panel (20) is resting along an inner wall (22) corresponding to the outer wall (34) of the interlayer and an inner panel (10) at least partially resting along the outer wall (14) corresponding to the inner wall (32) of the interlayer.

12. A vehicle with a laminated vehicle window according to claim 11 , wherein a camera (1 ) is configured to face at the flattened region (35) from its lens (2).

13. A vehicle according to claim 12, wherein the flattened region (35) is adjusted perpendicular to a lens axis (x) passing through the center of the camera lens (2).

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