DE102014220189B4 - Head-up display and method for generating a virtual image using a head-up display and using p-polarized light in a head-up display - Google Patents

Abstract

Head-up display (1) comprising - an image generation unit (2) and - a disk arrangement (3), wherein - the image generation unit (2) is set up to emit p-polarized light (4p), - the disk arrangement (3) has a reflective structure (5) which is set up to reflect p-polarized light (4), the reflective structure consisting of a structured metallic coating (5) which has a plurality of thin metal strips, characterized in that for the structured metallic coating (5) is used for a windshield heater in the pane assembly (3) existing metallic coating.

Description

field of invention

The present invention relates to a head-up display, comprising an image generation unit and a pane arrangement. Furthermore, the invention relates to a method for generating a virtual image using an aforementioned head-up display and the use of p-polarized light in a head-up display.

Background of the Invention

Head-up displays (HUDs) are used, for example, in land vehicles, in particular passenger cars (cars), and in aircraft. In land vehicles, the pane arrangement is typically formed by the windshield in order to be able to dispense with a separate pane in the driver's field of vision, since a separate pane is perceived as annoying and can impair traffic safety. In aircraft, on the other hand, separate panes, typically combiner panes, are often used. Combiner HUDs are currently also being offered in the automotive environment, particularly in price-sensitive segments.

Out of U.S. 2005/0270655 A1 a head-up display comprising an image generation unit and a panel arrangement is known, wherein the image generation unit is set up to emit p-polarized light, and the panel arrangement has a reflective structure which is set up to reflect p-polarized light. Also U.S. 7,355,796 B2 shows a similar head-up display. Out of WO 2013/190958 A1 a corresponding head-up display is known, in which a so-called wire-grid polarizer is used.

According to known methods for generating a virtual image using a head-up display, the image generation unit usually generates an image using s-polarized or non-polarized light and deflects it so that it falls at a certain angle of incidence onto the usually (quasi-)transparent Disc arrangement hits, which reflects s-polarized light significantly more than p-polarized light. The reflected image can already be perceived optically sufficiently well by a user located in the reflection area.

Since the s-polarized light of the image generation unit is reflected at both boundary surfaces of the pane arrangement to the air, an undesirable double image is created. In order to reduce its separation, the pane arrangement can be provided with a pane with a wedge-shaped cross-section, whereby the light from the image generation unit is reflected in such a way that the user perceives the two individual images of the double image as at least almost congruent from the nominal position. The inventors of the present invention have found that it is problematic, however, that polarization-selective sunglasses typically filter out s-polarized light, so that a user wearing such sunglasses can hardly (or in the model case not at all) can be perceived optically.

Summary of the Invention

The object of the present invention can therefore be to provide a head-up display and a method of the type mentioned at the outset, in which the displayed image is also visible well through polarization-selective sunglasses, but in any case without or with a reduced double image.

The object is achieved by the head-up display according to claim 1, by the method for generating a virtual image using a head-up display according to claim 7 and by using p-polarized light in a head-up display claim 8

The head-up display according to the invention comprises an image generation unit and a disk arrangement, the image generation unit being set up to emit p-polarized light and the disk arrangement having a reflective structure which is set up to reflect p-polarized light, the reflective structure consists of a structured metallic coating which has a plurality of thin metal strips, and for the structured metallic coating a metallic coating present for a windshield heater in the window arrangement is used. In other words, a system is provided which has both a head-up display with an image generation unit and the window arrangement of the vehicle.

It should be noted that the reflective structure is set up, possibly in combination with the pane, to reflect p-polarized light.

The image generation unit generates an image by emitting p-polarized light and throwing it onto the pane arrangement and thus also onto its reflective structure, for which purpose the light from the image generation unit can be deflected accordingly, in particular by an optics module. In particular, the image generation unit can be set up to produce only p-polarized light to emit. However, in one exemplary embodiment, the image generation unit can also emit p-polarized light and light polarized in a different way, that is to say a mixture. Conventional pane arrangements would reflect p-polarized light in such a way that a user located in the reflection area could perceive the image as significantly weakened, regardless of whether he was wearing polarization-selective sunglasses or not. The reflective structure of the present invention causes p-polarized light to reach the user by reflection to a sufficient extent so that he can easily perceive it optically. In particular, the image of the head-up display is also visible through polarization-selective sunglasses that filter out s-polarized light. A double image is clearly suppressed, since a relevant reflection only occurs on the outside of the pane. The reflective structure is a structured metallic coating. The metallic coating can, for example--less depending on the direction of polarization of the light--reflect approximately 30% or 50% of the light emitted by the imaging unit and transmit approximately 70% or 50%, but other values can also be realized.

According to the invention, the reflective structure includes a metallic coating. The metallic coating makes it possible, in particular, for p-polarized light from the image generation unit to be reflected more strongly than s-polarized light at a given angle of incidence of the light from the image generation unit—at least in certain wavelength ranges. Furthermore, this contributes to reducing material and production costs by using - at least in a modified form - metallic coatings that are already present in the pane arrangement and serve as windshield heating for defrosting.

The metallic coating may cover at least a portion of the surface of the pane assembly, preferably the portion of the pane assembly on which the light from the imaging unit impinges. It is also possible for the entire surface of the pane arrangement to be covered by the metallic coating. According to the invention, the metallic coating is structured. Such a structured coating can work in a polarization-selective manner. The structuring can be in the form of e.g. B. be designed in the form of a lattice vapor-deposited fine wires. A particularly high reflectivity for p-polarized light of the image generation unit can advantageously be achieved by an electric field component parallel to the wires.

By way of example, the metallic coating consists of silver or aluminum and has a layer thickness of 5 nm to 9 nm, in particular 7 nm, with deviations from the specified layer thickness in the range of ±30% being included. This embodiment contributes to reflecting a particularly high proportion of the p-polarized light generated by the imaging unit. In particular, in the visible wavelength range, as the wavelength increases, a higher proportion of the p-polarized light generated by the image generation unit can be reflected, so that the colors in the upper visible wavelength range can be represented particularly well.

In addition to a metallic coating, the reflective structure may include non-metallic elements, e.g. B. prisms, holograms or photonic crystals, in which particular light of the imaging unit is reflected with an angle of reflection unequal to the angle of incidence and can be directed to a user of the head-up display.

According to a further embodiment, it is advantageously provided that the light emitted by the image generation unit is projected onto the pane arrangement at an angle of incidence in an angular range between 55° and 70°. To generate the angle of incidence in said angular range, the light generated by the imaging unit z. B. be deflected accordingly by means of an optical module. This embodiment makes it possible, in particular, to suppress a double image as much as possible in that the reflective structure of the pane element almost exclusively reflects p-polarized light emitted by the image generation unit in the direction of a user's field of vision. On the other hand, a large proportion of the p-polarized light emitted by the image generation unit is particularly strongly transmitted by the rest of the pane arrangement in the stated angle of incidence range and only a particularly small proportion is reflected. This effect is particularly high when the p-polarized light generated by the image generation unit impinges on the pane arrangement at an angle of incidence in the Brewster angle range.

According to a further embodiment, the light of the image generation unit is emitted onto the pane arrangement at Brewster's angle.

The pane arrangement can advantageously have two boundary surfaces running parallel to one another, so that this embodiment can be described as wedge-free. A wedge-shaped cross section of the disc arrangement can be dispensed with. This simplifies the finish in particular production and material costs. The boundary surfaces each represent the transition from the pane arrangement to the surrounding medium, for example to the inside air of the vehicle interior of a car on the one hand and to the outside air of the outside environment of the car on the other hand. This embodiment can, for example, the 2 be removed.

According to a further embodiment, it is advantageously provided that the pane arrangement has a first pane element and a second pane element, with the reflective structure being arranged between the first pane element and the second pane element. Here z. For example, the first pane element forms an inner pane facing the passenger compartment of a car and the second pane element forms an outer pane facing the outside environment. This embodiment contributes in particular to protecting the reflective structure from external environmental influences in a particularly reliable manner. In particular, the reflective structure can be arranged in a sandwich-like manner, ie it touches both pane elements.

In this connection it is particularly advantageous that the reflecting structure has a metallic coating which is applied to the first pane element or the second pane element. In this way, in particular, the manufacturing effort can be reduced by applying the metallic coating to one of the disk elements and then connecting it to the other disk element. Alternatively, it is provided that an intermediate film is arranged between the first pane element and the second pane element, on which the metallic coating is applied. The intermediate film preferably consists of polyvinyl butyral (PVB) and covers the entire area or a large area of the pane elements. This has the advantage, in particular in the event of a breakage of the pane, that most of the splinters can adhere to the intermediate film and in particular only partially or not at all get into the passenger compartment of the car.

• - Bereitstellen eines Head-Up-Display nach einem der vorstehenden Ansprüchen,
• - Emittieren von p-polarisiertem Licht mittels der Bilderzeugungseinheit und
• - Reflektieren des p-polarisierten Lichts mittels der reflektierenden Struktur.

The inventive method according to claim 7 for generating a virtual image by means of a head-up display comprises the steps:

• - Providing a head-up display according to any one of the preceding claims,
• - emitting p-polarized light by means of the imaging unit and
• - reflecting the p-polarized light by means of the reflecting structure.

With regard to advantageous embodiments and developments of the method according to the invention, the statements made in connection with the head-up display according to the invention apply accordingly, so that reference is made thereto to avoid repetition. The same applies to the likewise inventively provided use of p-polarized light in a head-up display according to claim 8, wherein the p-polarized light from a p-polarized light-reflecting structure of the pane arrangement into the field of vision of a user of the head-up display displays is reflected.

According to a further embodiment, a vehicle with a head-up display as described herein is specified.

character list

• 1 eine schematische Darstellung eines Pkws mit einem Ausführungsbeispiel eines erfindungsgemäßen Head-Up-Displays,
• 2 den Strahlengang an dem Head-Up-Display aus 1 in einer vergrößerten schematischen Seitenansicht,
• 3 ein Flussdiagramm für ein Ausführungsbeispiel eines erfindungsgemäßen Verfahrens zur Erzeugung eines virtuellen Bilds mittels eines erfindungsgemäßen Head-Up-Displays,
• 4 den Strahlengang durch ein Head-Up-Display mit einem Lambda/2-Element,
• 5 den Strahlengang durch ein Ausführungsbeispiel des erfindungsgemäßen Head-Up-Displays mit einer strukturiert ausgeführten metallischen Beschichtung,
• 6 den Strahlengang durch ein Head-Up-Display mit einer metallischen Beschichtung und einem Lambda/4-Element sowie
• 7 den Strahlengang durch ein Head-Up-Display mit einem Lambda/4-Element.

Exemplary embodiments of the invention are explained in more detail below with reference to the drawing. This shows:

• 1 a schematic representation of a car with an embodiment of a head-up display according to the invention,
• 2 out the beam path on the head-up display 1 in an enlarged schematic side view,
• 3 a flowchart for an embodiment of a method according to the invention for generating a virtual image by means of a head-up display according to the invention,
• 4 the beam path through a head-up display with a lambda/2 element,
• 5 the beam path through an embodiment of the head-up display according to the invention with a structured metallic coating,
• 6 the beam path through a head-up display with a metallic coating and a lambda/4 element as well as
• 7 the beam path through a head-up display with a lambda/4 element.

Detailed description of exemplary embodiments

1 10 shows a passenger car 10 with an exemplary embodiment of a head-up display according to the invention, which comprises an image generation unit 2 and a pane arrangement 3 made of glass. In addition to glass, other materials such. B. plastic can be used. A user N is sitting in the interior I of the car on the driver's seat, so that the virtual image generated by the head-up display 1 can reach the user N's field of vision. The user N wears polarization-selective sunglasses S, which are impermeable or almost impermeable to s-polarized light.

The image generation unit 2 comprises a TFT unit, not shown, which generates and emits p-polarized light, represented by a light beam 4p in the drawing. How to continue 2 As can be seen, the pane arrangement 3 comprises a reflective structure which, in this exemplary embodiment, consists of a metallic coating 5 made of aluminum with a layer thickness of 7 nm. This metallic coating 5 is set up to have a partially reflective effect on p- and s-polarized light in such a way that approximately 50% of the light—regardless of its direction of polarization—is transmitted.

The pane arrangement 3 also has a first pane element in the form of an inner pane 3i and a second pane element in the form of an outer pane 3a. The metallic coating 5 is applied to the outside of the inner pane 3i facing away from the interior I of the car 10 and touches the inside of the outer pane 3a facing the interior I of the car 10 like a sandwich. The outside of the outer pane 3a facing away from the interior I forms an outer boundary surface 6 with the outside air 7 surrounding the passenger car 10 and the inside of the inner pane 3i facing the interior I forms an inner boundary surface 7 with the inner race 8 located in the interior I. The boundary surfaces 6 and 7 run parallel to each other. In other words, the disk assembly is wedge-free.

3 shows the sequence of an exemplary embodiment of the method according to the invention for generating a virtual image using the head-up display 1 1 and 2 . First, in a first step 100, the head-up display 1 after 1 and 2 provided. Subsequently, in a second method step 200, p-polarized light 4p is generated by means of the image generating unit 2. The light beam 4p generated by the image generation unit 2 is directed onto the pane arrangement 3 at an angle of incidence of approximately 64°. In a third method step, the light beam 4p is reflected by the metallic coating 5 in such a way that the reflected portion of the light beam 4p reaches the user N's field of vision. The reflected light beam 4p is also p-polarized and is not filtered out by the sunglasses S of the user N, but is transmitted, so that the user N can visually perceive the virtual image generated by the head-up display 1 without a double image.

4 shows the beam path through a pane arrangement 3 of a head-up display 1 not claimed here, the pane arrangement as in 1 and 2 an inner pane 3i and an outer pane 3a. A lambda/2 element 9 is arranged between the inner pane 3i and the outer pane 3a, which together with the outer boundary surface 6 of the outer pane 3a facing away from the interior I forms a reflective structure 5.

1. 1. Das von der Bilderzeugungseinheit 2 erzeugte p-polarisierte Licht 4p verlässt in Richtung der Scheibenanordnung 3 abgelenkt die Bilderzeugungseinheit 2.
2. 2. Beim Auftreffen auf die innere Grenzfläche 7 der Innenscheibe 3i wird bei dazu geeignetem Einfallswinkel ein relativ geringer, nicht dargestellter Anteil des p-polarisierten Lichts 4p reflektiert (schwacher Fresnelreflex) und ein relativ hoher Anteil des p- polarisierten Lichts 4p durchläuft die Innenscheibe 3i.
3. 3. Beim Auftreffen des p-polarisierten Lichts 4p auf dem zwischen der Innenscheibe 3i und der Außenscheibe 3a angeordneten Lambda/2-Element 9 dreht Letzteres die Polarisation des Lichts 4p um ca. 90°, d. h., das p-polarisierte Licht 4p wird in s-polarisiertes Licht 4s gewandelt.
4. 4. Das nunmehr s-polarisierte Licht 4s durchläuft die Außenscheibe 3a und trifft mit einem derartigen Einfallswinkel auf deren äußere Grenzfläche 6, dass ein relativ hoher Anteil des s-polarisierten Lichts 4s reflektiert wird (starker Fresnelreflex) und ein relativ geringer, nicht dargestellter Anteil des s-polarisierten Lichts 4s die Außenscheibe 3a verlässt.
5. 5. Beim Auftreffen auf dem Lambda/2-Element 9 dreht Letzeres die Polarisation des s-polarisierten Lichts 4s erneut um ca. 90°, so dass das s-polarisierte Licht 4s wieder in p-polarisiertes Licht 4p gewandelt wird.
6. 6. Das nunmehr wieder p-polarisierte Licht 4p durchläuft die Innenscheibe 3i in Richtung des Innenraums I und trifft mit einem derartigen Einfallswinkel auf die innere Grenzfläche des ersten Scheibenelements 3i, dass es relativ stark transmittiert und relativ gering reflektiert wird.
7. 7. Das transmittierte, p-polarisierte Licht 4p tritt durch die Gläser der Sonnenbrille S des Nutzers N.

In detail, the beam path runs as follows:

1. 1. The p-polarized light 4p generated by the image generation unit 2 leaves the image generation unit 2 deflected in the direction of the pane arrangement 3.
2. 2. When it hits the inner boundary surface 7 of the inner pane 3i, a relatively small proportion of the p-polarized light 4p (not shown) is reflected at a suitable angle of incidence (weak Fresnel reflection) and a relatively high proportion of the p-polarized light 4p passes through the inner pane 3i .
3. 3. When the p-polarized light 4p impinges on the lambda/2 element 9 arranged between the inner pane 3i and the outer pane 3a, the latter rotates the polarization of the light 4p by approx. 90°, i.e. the p-polarized light 4p becomes in s-polarized light 4s converted.
4. 4. The now s-polarized light 4s passes through the outer pane 3a and strikes its outer boundary surface 6 with such an angle of incidence that a relatively high proportion of the s-polarized light 4s is reflected (strong Fresnel reflection) and a relatively small proportion, not shown of the s-polarized light 4s leaves the outer pane 3a.
5. 5. When it strikes the lambda/2 element 9, the latter rotates the polarization of the s-polarized light 4s again by approximately 90°, so that the s-polarized light 4s is converted back into p-polarized light 4p.
6. 6. The now again p-polarized light 4p passes through the inner pane 3i in the direction of the interior I and hits the inner boundary surface of the first pane element 3i with such an angle of incidence that it is transmitted relatively strongly and reflected relatively little.
7. 7. The transmitted, p-polarized light 4p passes through the lenses of the sunglasses S of the user N.

5 shows the beam path through a pane arrangement 3 of an embodiment of the head-up display 1 according to the invention, the reflective structure consisting of a structured metallic coating 5 which has a plurality of thin metal strips. The disk arrangement 3 comprises, as in 1 and 2 shown, an inner pane 3i and a Outer pane 3a, between which the reflective structure is arranged.

• 1. Das von der Bilderzeugungseinheit 2 erzeugte p-polarisierte Licht 4p verlässt in Richtung der Scheibenanordnung 3 die Bilderzeugungseinheit 2.
• 2. Beim Auftreffen auf die innere Grenzfläche 7 der Innenscheibe 3i wird bei dazu geeignetem Einfallswinkel ein relativ geringer, nicht dargestellter Anteil des p-polarisierten Lichts 4p reflektiert (schwacher Fresnelreflex) und ein relativ hoher Anteil des p- polarisierten Lichts 4p durchläuft die Innenscheibe 3i.
• 3. Beim Auftreffen des p-polarisierten Lichts 4p auf der reflektierenden Struktur 5 werden in diesem Beispiel ca. 50 % des p-polarisierten Lichts 4p transmittiert und ein relativ hoher Anteil des übrigen p-polarisierten Lichts 4p reflektiert. Ebenfalls ist es gemäß diesem Ausführungsbeispiel möglich, dass die Bilderzeugungseinheit 3 nicht-polarisiertes Licht erzeugt und auf die Scheibenanordnung 3 bzw. die reflektierende Struktur 5 lenkt, da Letztere s-polarisiertes Licht zu nahezu 100 % transmittiert.
• 4a. Das transmittierte p-polarisierte Licht 4p durchläuft die Außenscheibe 3a und trifft mit einem derartigen Einfallswinkel auf deren äußere Grenzfläche 6, dass ein relativ hoher Anteil des p-polarisierten Lichts 4p transmittiert wird (schwacher Fresnelreflex) und ein zu vernachlässigender, nicht dargestellter Anteil des p-polarisierten Lichts 4p reflektiert wird. Ein Doppelbild wird dadurch im Falle der überwiegenden p-Polarisation des einfallenden Lichts vermieden.
• 4b. Das reflektierte p-polarisierte Licht 4p hingegen durchläuft erneut die Innenscheibe 3i (diesmal in Richtung des Innenraums I) und trifft mit einem derartigen Einfallswinkel auf deren innere Grenzfläche 7, dass ein relativ hoher Anteil des p-polarisierten Lichts 4p transmittiert wird (schwacher Fresnelreflex) und ein zu vernachlässigender, nicht dargestellter Anteil des p-polarisierten Lichts 4p reflektiert wird.
• 5. Das transmittierte, p-polarisierte Licht 4p tritt durch die Gläser der Sonnenbrille S des Nutzers N.

In detail, the beam path runs as follows:

• 1. The p-polarized light 4p generated by the image generation unit 2 leaves the image generation unit 2 in the direction of the pane arrangement 3.
• 2. When it hits the inner boundary surface 7 of the inner pane 3i, a relatively small proportion of the p-polarized light 4p (not shown) is reflected at a suitable angle of incidence (weak Fresnel reflection) and a relatively high proportion of the p-polarized light 4p passes through the inner pane 3i .
• 3. When the p-polarized light 4p impinges on the reflecting structure 5, approximately 50% of the p-polarized light 4p is transmitted in this example and a relatively high proportion of the remaining p-polarized light 4p is reflected. According to this exemplary embodiment, it is also possible for the image generation unit 3 to generate non-polarized light and direct it onto the pane arrangement 3 or the reflecting structure 5, since the latter transmits almost 100% of s-polarized light.
• 4a. The transmitted p-polarized light 4p passes through the outer pane 3a and strikes its outer boundary surface 6 with such an angle of incidence that a relatively high proportion of the p-polarized light 4p is transmitted (weak Fresnel reflection) and a negligible proportion of the p -polarized light 4p is reflected. A double image is thereby avoided in the case of predominantly p-polarization of the incident light.
• 4b. The reflected p-polarized light 4p, on the other hand, passes through the inner pane 3i again (this time in the direction of the interior I) and strikes its inner boundary surface 7 with such an angle of incidence that a relatively high proportion of the p-polarized light 4p is transmitted (weak Fresnel reflex). and a negligible portion, not shown, of the p-polarized light 4p is reflected.
• 5. The transmitted, p-polarized light 4p passes through the lenses of the sunglasses S of the user N.

6 shows the beam path through a pane arrangement 3 of a head-up display 1 not claimed here, the pane arrangement 3 comprising an inner pane 3i and an outer pane 3a, between which a metallic coating 9 is arranged. A reflective structure 5 is formed overall by a lambda/4 element 10 likewise arranged between the inner pane 3i and the outer pane 3a and by the outer boundary surface 6 of the outer pane 3a facing away from the interior I.

• 1. Das von der Bilderzeugungseinheit 2 erzeugte linear-p-polarisierte Licht 4p verlässt in Richtung der Scheibenanordnung 3 abgelenkt die Bilderzeugungseinheit 2.
• 2. Beim Auftreffen auf die innere Grenzfläche 7 der Innenscheibe 3i wird bei dazu geeignetem Einfallswinkel ein relativ geringer, nicht dargestellter Anteil des p-polarisierten Lichts 4p reflektiert (schwacher Fresnelreflex) und ein relativ hoher Anteil des p- polarisierten Lichts 4p durchläuft die Innenscheibe 3i.
• 3. Beim Auftreffen des p-polarisierten Lichts 4p auf das Lambda/4-Element 10 wird dieses in zirkular polarisiertes Licht 4z gewandelt. Durch die metallische Beschichtung 9, hier der Übersichtlichkeit halber zusammen mit dem Lambda/4-Element 10 dargestellt, wird ein Anteil transmittiert und ein anderer reflektiert, der nun wiederum von dem Lambda/4-Element 10 in s-polarisiertes Licht gewandelt wird.
• 4a. Das nunmehr s-polarisierte Licht 4s durchläuft erneut die Innenscheibe 3i (diesmal in Richtung des Innenraums I).
• 4b. Das nunmehr zirkular-polarisierte Licht 4z hingegen durchläuft die Außenscheibe 3a und trifft mit einem derartigen Einfallswinkel auf deren äußere Grenzfläche 6, dass ein Anteil des zirkular-polarisierten Lichts 4z als s-polarisiertes Licht 4s reflektiert wird (Fresnelreflex) und der übrige Anteil des vorher z-polarisierten Lichts 4z als p-polarisiertes Licht 4p die Außenscheibe 3a verlässt.
• 5. Das reflektierte s-polarisierte Licht 4s durchläuft die Außenscheibe 3a in Richtung des Innenraums I. Beim Auftreffen auf das Lambda/4-Element 10 wandelt Letzeres das s-polarisierte Licht 4s in zirkular polarisiertes Licht 4z.
• 6. Das nunmehr zirkular-polarisierte Licht 4z durchläuft die Innenscheibe 3i und trifft mit einem derartigen Einfallswinkel auf deren innere Grenzfläche 7, dass ein nicht dargestellter Anteil des zirkular-polarisierten Lichts 4z als s-polarisiertes Licht 4s reflektiert wird (Fresnelreflex) und der übrige Anteil des z-polarisierten Lichts 4z als überwiegend p-polarisiertes Licht 4p die Innenscheibe 3i verlässt.
• 7. Das transmittierte, überwiegend p-polarisierte Licht 4p tritt durch die Gläser der Sonnenbrille S des Nutzers N.

In detail, the beam path runs as follows:

• 1. The linearly p-polarized light 4p generated by the image generation unit 2 leaves the image generation unit 2 deflected in the direction of the pane arrangement 3.
• 2. When it hits the inner boundary surface 7 of the inner pane 3i, a relatively small proportion of the p-polarized light 4p (not shown) is reflected at a suitable angle of incidence (weak Fresnel reflection) and a relatively high proportion of the p-polarized light 4p passes through the inner pane 3i .
• 3. When the p-polarized light 4p impinges on the lambda/4 element 10, it is converted into circularly polarized light 4z. Through the metallic coating 9, shown here together with the lambda/4 element 10 for the sake of clarity, one part is transmitted and another is reflected, which is now in turn converted by the lambda/4 element 10 into s-polarized light.
• 4a. The now s-polarized light 4s again passes through the inner pane 3i (this time in the direction of the interior I).
• 4b. The now circularly polarized light 4z, on the other hand, passes through the outer pane 3a and strikes its outer boundary surface 6 with such an angle of incidence that a portion of the circularly polarized light 4z is reflected as s-polarized light 4s (Fresnel reflex) and the remaining portion of the previously z-polarized light 4z leaves the outer pane 3a as p-polarized light 4p.
• 5. The reflected s-polarized light 4s passes through the outer pane 3a in the direction of the interior I. When it strikes the lambda/4 element 10, the latter converts the s-polarized light 4s into circularly polarized light 4z.
• 6. The now circularly polarized light 4z passes through the inner pane 3i and strikes its inner boundary surface 7 with such an angle of incidence that a portion of the circularly polarized light 4z (not shown) is reflected as s-polarized light 4s (Fresnel reflex) and the rest Portion of the z-polarized light 4z leaves the inner pane 3i as predominantly p-polarized light 4p.
• 7. The transmitted, predominantly p-polarized light 4p passes through the lenses of the sunglasses S of the user N.

The user still sees a double image without polarizing sunglasses, but continues to see the HUD display with the sunglasses on.

It should be noted that in the example of 6 the lower signal can also be used as a useful signal. The upper signal is a non-negligible, p-polarized signal, but it is attenuated more than in the other solutions. Since the p-polarized signal is the weaker of the two for the non-sunglasses wearer, the lower signal can also be used.

7 shows the beam path through a pane arrangement 3 of a head-up display 1 not claimed here, the pane arrangement 3 comprising an inner pane 3i and an outer pane 3a. A reflective structure 5 is formed by a lambda/4 element 10 arranged between the inner pane 3i and the outer pane 3a and by the outer boundary surface 6 of the outer pane 3a facing away from the interior I.

1. 1. Das von der Bilderzeugungseinheit 2 erzeugte linear-p-polarisierte Licht 4p verlässt in Richtung der Scheibenanordnung 3 abgelenkt die Bilderzeugungseinheit 2.
2. 2. Beim Auftreffen auf die innere Grenzfläche 7 der Innenscheibe 3i wird bei dazu geeignetem Einfallswinkel ein relativ geringer, nicht dargestellter Anteil des p-polarisierten Lichts 4p reflektiert (schwacher Fresnelreflex) und ein relativ hoher Anteil des p- polarisierten Lichts 4p durchläuft die Innenscheibe 3i.
3. 3. Beim Auftreffen des p-polarisierten Lichts 4p auf dem Lambda/4-Element 10 wandelt Letzteres das Licht 4p in zirkular-polarisiertes Licht 4z.
4. 4. Das nunmehr zirkular-polarisierte Licht 4z durchläuft die Außenscheibe 3a und trifft mit einem derartigen Einfallswinkel auf deren äußere Grenzfläche 6, dass ein Anteil des zirkular-polarisierten Lichts 4z als s-polarisiertes Licht 4s reflektiert wird verlässt.
5. 5. Das reflektierte s-polarisierte Licht 4s durchläuft die Außenscheibe 3a in Richtung des Innenraums I. Beim Auftreffen auf das Lambda/4-Element 10 wandelt Letzteres das s-polarisierte Licht 4p in zirkular polarisiertes Licht 4z.
6. 6. Das nunmehr zirkular-polarisierte Licht 4z durchläuft die Innenscheibe 3i und wird zu einem relativ großen Anteil von der Innenscheibe 3i transmittiert.
7. 7. Der p-polarisierte Anteil des transmittierten, vormals zirkular-polarisierten Lichts 4z tritt durch die Gläser der Sonnenbrille S des Nutzers N.

In detail, the beam path runs as follows:

1. 1. The linearly p-polarized light 4p generated by the image generation unit 2 leaves the image generation unit 2 deflected in the direction of the pane arrangement 3.
2. 2. When it hits the inner boundary surface 7 of the inner pane 3i, a relatively small proportion of the p-polarized light 4p (not shown) is reflected at a suitable angle of incidence (weak Fresnel reflection) and a relatively high proportion of the p-polarized light 4p passes through the inner pane 3i .
3. 3. When the p-polarized light 4p impinges on the lambda/4 element 10, the latter converts the light 4p into circularly polarized light 4z.
4. 4. The now circularly polarized light 4z passes through the outer pane 3a and strikes its outer boundary surface 6 with such an angle of incidence that a portion of the circularly polarized light 4z is reflected as s-polarized light 4s.
5. 5. The reflected s-polarized light 4s passes through the outer pane 3a in the direction of the interior I. When it strikes the lambda/4 element 10, the latter converts the s-polarized light 4p into circularly polarized light 4z.
6. 6. The now circularly polarized light 4z passes through the inner pane 3i and is transmitted to a relatively large extent by the inner pane 3i.
7. 7. The p-polarized portion of the transmitted, formerly circularly polarized light 4z passes through the lenses of the sunglasses S of the user N.

Claims (8)

Head-up display (1) comprising - an image generation unit (2) and - a disk arrangement (3), wherein - the image generation unit (2) is set up to emit p-polarized light (4p), - the disk arrangement (3) has a reflective structure (5) which is set up to reflect p-polarized light (4), the reflective structure consisting of a structured metallic coating (5) which has a plurality of thin metal strips, characterized in that for the structured metallic coating (5) is used for a windshield heater in the pane assembly (3) existing metallic coating. Head-up display (1) after claim 1 , characterized in that the light (4) emitted by the image generation unit (2) is projected onto the pane arrangement (3) at an angle of incidence in an angular range between 55° and 70°. Head-up display (1) according to one of the preceding claims, characterized in that the pane arrangement (3) has boundary surfaces (6, 7) running parallel to one another. Head-up display (1) according to one of the preceding claims, characterized in that the pane arrangement (3) has a first pane element (3i) and a second pane element (3a), the reflective structure (5) between the first pane element ( 3i) and the second disk element (3a). Head-up display (1) according to one of the preceding claims, characterized in that the metallic coating covers a region of the surface of the pane arrangement. Head-up display (1) according to one of the preceding claims, characterized in that the reflective structure (5) comprises, in addition to the metallic coating, non-metallic elements in which light from the imaging unit (2) is reflected at an angle of emergence unequal to the angle of incidence. Method for generating a virtual image by means of a head-up display (1) comprising the steps: (100) providing a head-up display (1) according to one of the preceding claims, (200) emitting p-polarized light (4p ) by means of the image generation unit (2) and (300) reflecting the p-polarized light (4p) by means of the reflective structure (5). Use of p-polarized light (4p) in a head-up display (1), the p-polarized light (4p) of an imaging unit of the head-up display being reflected by a p-polarized light-reflecting structure (5) of the pane arrangement (3) reflected into a viewing area of a user (N) of the head-up display (1), the reflective structure consisting of a structured metallic coating (5) which has a plurality of thin metal strips, and being structured for the carried out metallic coating (5) for a windshield heater in the disc assembly (3) existing metallic coating is used.

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