DE202020102811U1 - Composite pane for a head-up display - Google Patents

Abstract

Composite pane (100) for a head-up display in a HUD area and at least one transparent screen device in a display area, at least comprising an outer pane (1) and an inner pane (2), which have a thermoplastic intermediate layer (3) are connected to one another, a first liquid crystal layer (p) which reflects p-polarized light being arranged in the thermoplastic intermediate layer (3) in the HUD area and a second liquid crystal layer (d) which is diffusely reflecting light being arranged in the display area.

Description

The invention relates to a composite pane for a head-up display in a HUD area combined with at least one transparent screen device in a display area.

Modern automobiles are increasingly being equipped with so-called head-up displays (HUDs). With a projector, typically in the area of the dashboard, images are projected onto the windshield, reflected there and perceived by the driver as a virtual image (seen from the driver) behind the windshield. This allows important information to be projected into the driver's field of vision, such as the current driving speed, navigation or warning notices that the driver can perceive without having to take his eyes off the road. Head-up displays can make a significant contribution to increasing traffic safety.

The problem with the head-up displays described above arises that the projector image is reflected on both surfaces of the windshield. As a result, the driver not only perceives the desired main image, which is caused by the reflection on the interior surface of the windshield (primary reflection). The driver also perceives a slightly offset, usually less intense secondary image, which is caused by the reflection on the outside surface of the windshield (secondary reflection). The latter is commonly referred to as a ghost. This problem is generally solved in that the reflecting surfaces are arranged at a deliberately chosen angle to one another, so that the main image and the ghost image are superimposed, as a result of which the ghost image is no longer noticeable.

Windshields usually consist of two glass panes, which are laminated and connected to each other via a thermoplastic film. If the surfaces of the glass panes are to be arranged at an angle as described above, it is customary to use a thermoplastic film with a non-constant thickness. One also speaks of a wedge-shaped film or wedge film. The angle between the two surfaces of the film is called the wedge angle. The wedge angle can be constant over the entire film (linear change in thickness) or change depending on the position (non-linear change in thickness). Laminated glasses with wedge foils are made of, for example W02009 / 071135A1 , EP1800855B1 or EP1880243A2 known. The radiation from the HUD projector has so far often been essentially s-polarized due to the better reflection characteristics of the windshield compared to p-polarization. However, if the driver wears polarization-selective sunglasses that only transmit p-polarized light, he can hardly or not see the HUD image. There is therefore a need for HUD projection arrangements which are compatible with polarization-selective sunglasses.

The DE 10 2014 220 189 A 1 discloses a HUD projection arrangement which is operated with p-polarized radiation in order to generate a HUD image which is also perceptible with polarization-selective sunglasses. Since the angle of incidence is typically close to the Brewster angle and p-polarized radiation is therefore only reflected to a small extent from the glass surfaces, the windshield has a reflective structure which can reflect p-polarized radiation in the direction of the driver. A single metallic layer with a thickness of 5 nm to 9 nm, for example made of silver or aluminum, is proposed as the reflective structure. The p-polarized HUD image can be seen by drivers with and without polarization-selective sunglasses.

Another technology for realizing a head-up display using p-polarisibased light is based on using a functional film in composite panes that can reflect p-polarized light by using certain liquid crystals that are coated on a substrate material, such as Carrier films made of triacetate (TAC), polyethylene terephthalate (PET), polyethylene (PE), polyamide (PA), or other conventional polymeric materials are applied.

Furthermore, there are considerations not only to present the necessary information for the driver in optimal HUD images in his field of vision behind the windshield, but also for a possible passenger or another viewer on the same composite window, usually the windshield of a vehicle To provide screen function. It is often more pleasant for the passenger to use a display that appears to be on the laminated glass as a transparent screen.

The object of the present invention is therefore to provide a composite pane, in particular for use as a windshield in a vehicle, which has various display functions, in particular a head-up display and at the same time has at least one further display device which meets the requirements and Requirements for the driver and front passenger are adapted and enable optimized display of information and data for these people.

The object is achieved by a device according to claim 1. Advantageous refinements are in particular the subject of the dependent claims, the description and the figures.

According to the invention, a composite pane for at least one head-up display in a HUD area and at least one transparent screen device in a display area is provided, which comprises at least one outer pane and one inner pane, which are connected to one another via a thermoplastic intermediate layer, a first liquid crystal layer, which reflects p-polarized light, and a second liquid crystal layer, which diffusely reflects light, is arranged in the thermoplastic intermediate layer in the HUD area.

According to the invention, a composite pane is thus provided with which both at least one HUD display can be realized next to one another through the reflection of p-polarized light, and at least one transparent screen function through the diffuse-reflecting liquid crystal layer. The differently reflecting liquid crystal layers provided according to the invention thus advantageously enable different display devices in combination, which at the same time can also be adapted to the different needs and requirements for the driver and front passenger and which enable optimized display of information and data for these people.

According to the invention, the composite pane therefore has a so-called HUD area, which is usually arranged on the driver's side in the case of a windshield. The HUD area comprises the area of the composite pane that can be irradiated by a projector, which is also referred to as the HUD zone. The HUD area is therefore intended to be at least partially irradiated (in the HUD zone) by a projector for generating the HUD image. The radiation from the projector is then reflected in the direction of the viewer (driver), whereby a virtual image is generated which the viewer perceives from behind the windshield, that is to say as located outside the vehicle. According to the invention, a liquid crystal layer is arranged in this HUD area within the intermediate layer, which liquid layer can reflect p-polarized radiation from the projector in the direction of the viewer (driver). P-polarized radiation is advantageously not reflected on the (glass) panes of the composite pane, so that no or hardly any disturbing double images occur. A wedge-shaped cross section of the composite pane, by providing a wedge film in the intermediate layer, can advantageously be dispensed with. In particular, this simplifies the manufacturing and material costs compared to such a design of the HUD area.

According to the invention, the composite pane also has at least one so-called display area, which in the case of a windshield is usually arranged on the passenger side. The front passenger does not need to display the driver information in the field of vision behind the windshield and it is usually perceived as pleasant to use a display that appears to be directly on the composite window as a transparent screen. The inventive design of the display area with the diffuse-reflecting liquid crystal layer in the intermediate layer enables such a display function, while at the same time the composite pane in the display area advantageously appears to be transparent from the driver's point of view and does not obstruct the view. Liquid crystal films with cholesteric liquid crystals, which reflect light diffusely, as the basis for the realization of a transparent screen are, for example, in US20180052264 , WO20161175183 , WO2018169095 or the JP2018180122 described by Fujifilm.

The outer pane and the inner pane are preferably made of glass, in particular of soda-lime glass. In principle, however, the panes can also be made from other types of glass (for example borosilicate glass, quartz glass, aluminosilicate glass) or transparent plastics (for example polymethyl methacrylate or polycarbonate). The thickness of the outer pane and the inner pane can vary widely. Preferably, panes with a thickness in the range from 0.8 mm to 5 mm, preferably from 1.4 mm to 2.5 mm are used, for example those with the standard thicknesses of 1.6 mm or 2.1 mm.

The outer pane, the inner pane and the thermoplastic intermediate layer can be clear and colorless, but also tinted or colored. In a preferred embodiment, the total transmission through the laminated glass is greater than 70%. The term total transmission refers to that through ECE-R 43, Appendix 3rd , § 9.1 established procedures for testing the light transmission of motor vehicle windows. The outer pane and the inner pane may not be biased, partially biased or biased independently of each other. If at least one of the disks should have a prestress, this can be a thermal or chemical prestress. The composite pane is preferably bent in one or more directions of space, as is customary for motor vehicle panes, with typical radii of curvature in the range from approximately 10 cm to approximately 40 m. The composite pane can also be flat, for example if it is intended as a pane for buses, trains or tractors.

According to the invention, the liquid crystal layers, that is to say the p-pol reflecting and the diffuse-reflecting liquid crystal layers, are arranged flat next to one another within the intermediate layer of the composite pane. The liquid crystal layers are introduced into the composite pane as functional foils. Corresponding liquid crystal layers are applied as a coating on carrier films made of triacetate (TAC), polyethylene terephthalate (PET), polyethylene, (PE), polyamide (PA), or other conventional polymeric materials. High-precision coating processes for the production of such functional liquid crystal films are available and known in the prior art, and the functional films, both those which are diffusely reflective and those which reflect p-polarized light, are commercially available. In the manufacturing process of the composite pane according to the invention, the liquid crystal foils are, for example, sandwiched between two layers of thermoplastic material, for example between a first and a second thermoplastic polymer foil.

The first thermoplastic film and / or the second thermoplastic film for forming the intermediate layer can have a plastic, for example selected from the group consisting of polyvinyl butyral (PVB), ethylene vinyl acetate (EVA), polyurethane (PU), polypropylene (PP), polyacrylate, Polyethylene (PE), polycarbonate (PC), polymethyl methacrylate (PMMA), polyvinyl chloride (PVC), polyacetate resin, casting resins, polyacrylates, fluorinated ethylene-propylene copolymers, polyvinyl fluoride and / or ethylene-tetrafluoroethylene copolymers. PVB is particularly preferably used.

The different liquid crystal coatings can each be applied to a single carrier film, which are then arranged next to one another in a layer of the intermediate layer, preferably flush and without gaps. Alternatively, the different liquid crystal coatings can also be applied to a single carrier film. This has the advantage that the arrangement in the layer stack to be laminated is simplified during manufacture and that a gap formation between the liquid crystal layers can be excluded from the outset.

The composite pane can be produced by methods known per se. The outer pane, the inner pane and the layers of the intermediate layer are arranged in a stack, over one another. According to the invention, the two different p-pol and difffus reflecting liquid crystal films, or alternatively the liquid crystal film with the two different liquid crystal coatings and their different reflective properties (p-pol and diffusely reflecting) are sandwiched between at least a first and a second thermoplastic polymer film of the intermediate layer and arranged. The outer pane and the inner pane are then laminated to one another via the intermediate layer, for example by autoclave processes, vacuum bag processes, vacuum ring processes, calender processes, vacuum laminators or combinations thereof. The connection of the outer pane and inner pane is usually carried out under the action of heat, vacuum and / or pressure.

Figure list

The invention is explained in more detail below with reference to a drawing and exemplary embodiments. The drawings are schematic and are not to scale. The drawings in no way limit the invention.

• 1 eine schematische Draufsicht auf eine erfindungsgemäße Verbundscheibe 100 mit einem HUD-Bereich und einem Display-Bereich,
• 2 einen schematischen Querschnitt durch eine erfindungsgemäße Verbundscheibe aus 1;
• 2A eine vereinzelte Querschnittsdarstellung der erfindungsgemäß eingesetzten funktionellen Flüssigkristallfolie aus 2 zur Ausbildung eines Head-Up-Displays,
• 2B zeigt eine vereinzelte Querschnittsdarstellung der erfindungsgemäß eingesetzten funktionellen Flüssigkristallfolie aus 2 zur Ausbildung eines transparenten Bildschirms.
• 3 einen schematischen Querschnitt durch eine andere Ausgestaltung einer erfindungsgemäßen Verbundscheibe 100 aus 1.
• 3A zeigt eine vereinzelte Querschnittsdarstellung der erfindungsgemäß eingesetzten funktionellen Flüssigkristallfolie aus 3 mit unterschiedlichen Flüssigkristallbeschichtungen.

Show it:

• 1 is a schematic plan view of a composite pane according to the invention 100 with a HUD area and a display area,
• 2nd a schematic cross section through a composite pane according to the invention 1 ;
• 2A an isolated cross-sectional view of the functional liquid crystal film used according to the invention 2nd to form a head-up display,
• 2 B shows an isolated cross-sectional view of the functional liquid crystal film used according to the invention 2nd to form a transparent screen.
• 3rd a schematic cross section through another embodiment of a composite pane according to the invention 100 out 1 .
• 3A shows an isolated cross-sectional view of the functional liquid crystal film used according to the invention 3rd with different liquid crystal coatings.

Detailed description

The invention will be illustrated in more detail below with reference to the figures. It should be noted that different aspects are described, which can be used individually or in combination. This means that any aspect can be used with different embodiments of the invention unless explicitly shown as a pure alternative.
Furthermore, for the sake of simplicity, reference is generally only made to one entity taken. Unless explicitly noted, the invention can also have several of the entities concerned. In this respect, the use of the words "a", "a" and "one" is only to be understood as an indication that in a simple embodiment at least one entity is used.

1 shows a schematic plan view of a composite pane according to the invention 100 using the example of a windshield. When installed, the windshield has a roof edge at the top D and below an engine edge M on. On the driver side F is a HUD area H in the liquid crystal layer according to the invention p (please refer 2nd and 3rd ) is arranged, which reflects p-polarized light from a projector in the direction of an observer (driver) and can then perceive an image lying behind the windshield in his field of vision. The visibility of the driver information in the field of vision contributes significantly to safety, since the driver does not have to change the direction of view in order to read the information.

2nd shows a schematic cross-sectional view of the composite disc 100 along the section line XX ' 1 , The individual layers from which the composite pane according to the invention, in particular a windshield, is formed, are shown.
The outer pane 1 is in the installed position facing the environment while the inner pane 2nd is facing the interior. In between are the different layers of the intermediate layer 3rd shown. The thermoplastic films 2, 3 are preferably made of polyvinyl butyral (PVB) and can have a thickness of 0.38 mm, for example. Sandwiched between the thermoplastic foils 4, 5 are side by side on the driver's side F a carrier film T1 with liquid crystal coating p and a second carrier film T2 on the passenger side B with a liquid crystal coating d arranged. The carrier films T1 and T2 with the respective liquid crystal coating are commercially available. It is preferably located on the carrier film T1 facing surface of the liquid crystal coating p another carrier film T1 ' (Not shown). The liquid crystal coating p is sandwiched between the carrier films T1 and T1 ' appropriate. Analogously, the carrier film can also be used T2 facing surface of the liquid crystal coating d a carrier film T2` (not shown) may be attached. The carrier foils are expedient T1 , T2 and their respective liquid crystal coating d , p designed essentially in the same thickness and before lamination to the composite pane 100 positioned as gap-free as possible in the layer stack to be formed. An arrangement comprising four carrier foils is preferred T1 , T1 ' , T2 , T2` used, a difference in thickness being avoided in this case too. As a result, the composite pane is designed to be as visually appealing as possible free of visible transitions between the HUD area and the display area. The carrier films T1 , T1` , T2 , T2` can be formed from the same or from different polymers. For example, they can be transparent polyethylene terephthalate (PET) films, for example with a thickness of 0.05 mm. The liquid crystal layer p reflects p-polarized light from a projector towards a viewer (driver) and the viewer can then see an image behind the windshield in his field of vision, for example with information and data from the driver assistance systems, without having to take his eyes off the road. At the same time, it allows in the composite pane 100 arranged liquid crystal layer d , the design of a transparent screen on the passenger side B , whereby the passenger can perceive the image apparently lying on the compound window, while at the same time this area remains transparent to the driver and the unobstructed view is not impaired.

2A shows an isolated cross-sectional view of the functional liquid crystal film used according to the invention 2nd to form a head-up display, consisting of a carrier film (substrate) T1 and a liquid crystal coating p (Liquid crystal layer) reflecting p-polarized light. That on this liquid crystal layer p The reflected image is, as already described above, by an observer (driver) in his field of vision behind the composite pane 100 perceived lying.

2 B shows an isolated cross-sectional view of the functional liquid crystal film used according to the invention T2 out 2nd to form a transparent screen from a carrier film (substrate) and a liquid crystal coating d (Liquid crystal layer) that diffusely reflects light. An observer perceives the image reflected on this liquid crystal layer as apparently lying on the composite pane.

3rd shows a schematic cross-sectional view of another embodiment of the composite pane according to the invention 100 along the section line XX ' 1 , The individual layers from which the composite pane according to the invention is formed are shown. The structure largely corresponds to that in 2nd shown construction. Unlike the one in 2nd shown embodiment of the composite disc 100 are the different liquid crystal layers p , d , ie the p-pol reflective liquid crystal layer and the diffuse reflective liquid crystal layer d however on a uniform carrier film T3 (Substrate) applied. This configuration has the advantage that in the manufacture of the composite pane 100 the positioning can be done more easily and a gap formation between the liquid crystal layers p , d or slipping of the liquid crystal layers p and d to each other can be excluded from the outset.

3 A shows an isolated cross-sectional view of the functional liquid crystal film used according to the invention 3rd to form a head-up display in combination with a transparent screen made of a carrier film (substrate) and a liquid crystal coating p (Liquid crystal layer), which reflects p-polarized light and an adjacent liquid crystal coating d (Liquid crystal layer) that diffusely reflects light. That on the p-pol reflective liquid crystal layer p reflected image is perceived by a driver in his field of vision lying behind the compound window. A passenger can, however, through the diffuse-reflective liquid crystal layer d perceive an image that apparently lies on the laminated pane, while at the same time this part of the laminated pane appears transparent to the driver, so that there is no impairment of the view.

According to the invention, a composite pane 100 provided by the configuration with liquid crystal layers with different reflection properties, namely at least one liquid crystal layer p which reflects p-polarized light and secondly at least one liquid crystal layer d the light diffusely reflects a combination of a head-up display and a transparent screen. The differently reflecting liquid crystal layers provided according to the invention thus advantageously enable different display devices in combination, which at the same time can also be adapted to the different needs and requirements for the driver and front passenger and which enable optimized display of information and data for these people. The production is easily transferable into existing processes and series production.

Reference list

100

Composite disc

D

Roof edge

M

Motor edge

F

driver's side

B

Passenger side

p

Liquid crystal layer, p-pol reflective

d

Liquid crystal layer, diffusely reflective

1

Outer pane

2nd

Inner pane

3rd

Intermediate layer

4, 5

thermoplastic film

T1

Carrier layer (substrate) for p-pol liquid crystal layer p

T2

Carrier layer (substrate) for diffusely reflecting liquid crystal layer d

T3

uniform carrier layer (substrate) with two liquid crystal layers ( p , d )

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• WO 2009/071135 A1 [0004]
• EP 1800855 B1 [0004]
• EP 1880243 A2 [0004]
• DE 102014220189 A [0005]
• US 20180052264 [0013]
• WO 20161175183 [0013]
• WO 2018169095 [0013]
• JP 2018180122 [0013]

Claims (1)

Composite pane (100) for a head-up display in a HUD area and at least one transparent screen device in a display area, at least comprising an outer pane (1) and an inner pane (2), which have a thermoplastic intermediate layer (3) are connected to one another, a first liquid crystal layer (p) which reflects p-polarized light being arranged in the thermoplastic intermediate layer (3) in the HUD area and a second liquid crystal layer (d) which is diffusely reflecting light being arranged in the display area.

Images