DE102021123105A1 - VEHICLE LIGHT AND VEHICLE WITH VEHICLE LIGHT - Google Patents

Abstract

The invention relates to a vehicle lamp (1) with at least one light source (2) and a liquid crystal display (6) downstream of the light source (2), the vehicle lamp (1) having a microlens array (14) downstream of the light source (2). The invention also relates to a vehicle light (20) with at least one light source (22), a first microlens array (26), a polarization grating (28), a raster wave plate (34) and a second microlens array (38), the vehicle light (20) a liquid crystal layer (42) arranged between the polarization grating (28) and the scanning waveplate (34). The invention also relates to a vehicle with such a vehicle lamp (1; 20).

Description

The invention is based on a vehicle light for projecting a light image and on a vehicle with the vehicle light.

• Eine Möglichkeit besteht darin, dass Projektionskanäle miteinander multipliziert werden. Das heißt, dass mehrere gleiche Kanäle in einem Projektor vorgesehen werden (multi-channel projector), indem mehrere identische Lichtmodule parallel zueinander montiert werden, um einen geringfügig unterschiedlichen Bildinhalt projizieren zu können. Somit illuminiert jeder Kanal die gleiche Fläche, so dass alle Motive in die gleiche Bildellipse (in der Nähe des Fahrzeugs) kommen. Beispielsweise gibt es einen MLA-Projektor mit sieben Kanälen, wobei jeder der Kanäle durch eine Lichtquelle (LED) und eine Sammellinse (Kollimationslinse), sowie ein (gemeinsames) Mikrolinsenarray gebildet wird. Alternativ gibt es einen Gobo-Projektor mit vier Kanälen, bei denen jeder Kanal aus einer Lichtquelle (LED), einer Beleuchtungsoptik/einem Taper, einem Graphical Optical Blackout (Gobo), einer Projektionslinse und einer Blende/Lochblende gebildet wird, wobei die Beleuchtungsoptik, das Gobo, die Linse und die Blende zusammengefügt sein können. Nachteilig an solchen Multi-Channel-Projektoren ist jedoch, dass sie eine große Anzahl an Lichtquellen sowie viel Bauraum benötigen.

There are essentially several options for animated/dynamic image display:

• One possibility is that projection channels are multiplied together. This means that several identical channels are provided in one projector (multi-channel projector) by installing several identical light modules parallel to one another in order to be able to project slightly different image content. Thus each channel illuminates the same area so that all subjects come within the same image ellipse (close to the vehicle). For example, there is an MLA projector with seven channels, each of the channels being formed by a light source (LED) and a converging (collimating) lens, and a (common) microlens array. Alternatively, there is a gobo projector with four channels, where each channel is formed from a light source (LED), an illumination optics/taper, a graphic optical blackout (gobo), a projection lens and an aperture/pinhole, the illumination optics, the gobo, lens and shutter can be joined together. A disadvantage of such multi-channel projectors, however, is that they require a large number of light sources and a lot of installation space.

Another possibility is that a fully dynamic projector based on a spatial light modulator (SLM) such as a digital micromirror device (DMD), a liquid crystal display (LCD), or liquid crystals on silicon (Liquid Crystal on Silicon, LCOS), in which each pixel can be switched on or off in order to be able to project any image content. However, this is expensive because of the digital micromirror device or liquid crystal display and the components used therewith, such as a total internal reflection prism (TIR prism) or a polarized beam splitter (polarized beam splitter).

For example, is from the DE 20 2019 101 801 U1 a device for projecting at least two individual images onto a projection surface is known, which has at least one light source for generating illuminating light, a passive LCD element with at least two individually controllable segments which are illuminated by the illuminating light emitted by the light source and in each case at least one of are assigned to two individual images, and has imaging optics which images the two segments for generating the two individual images onto the projection surface.

Also is from the DE 10 2019 124 697 A1 a device for projecting at least two images onto a projection surface is known, which has a light source for generating illuminating light, an image generating element which has at least two areas which can be illuminated by the illuminating light emitted by the light source and which are each associated with at least one of the two images , and has imaging optics which images the two areas of the image generation element to generate the two images on the projection surface, the light source having at least two individually controllable light source elements which are designed to transilluminate one of the two areas, or that the device has an aperture unit with at least two segments that can be switched transparent individually, which can be transilluminated by the illumination light emitted by the light source and are arranged in such a way that one of the two segments of the diaphragm unit can be switched transparent in each case in one area of the imaging element is transilluminated.

It is therefore the object of the present invention to create a vehicle light that is simple in terms of device technology and is inexpensive for the (semi-)dynamic projection of a light image.

The object with regard to the vehicle lamp is solved according to the features of claim 1 or according to the features of claim 9 and the object with regard to the vehicle is solved according to the features of claim 10 .

Particularly advantageous configurations can be found in the dependent claims.

According to the invention, a vehicle light is provided for projecting a light image onto an imaging surface/imaging optics. The vehicle lamp has at least one light source. In addition, the vehicle lamp has a first microlens array downstream of the light source, a polarization grating (PG) downstream of the first microlens array, a louvered/quarter wave plate (LWP) downstream of the polarization grating, and a second microlens array downstream of the grid waveplate. According to the invention, the vehicle lamp has a liquid crystal arranged between the polarization grating and the raster waveplate layer up. That is, the light emitted from the light source first passes through the first microlens array, then the polarization grating, then the liquid crystal layer sandwiched between two glass substrates with transparent or non-transparent contacts, then the scanning waveplate, and then the second microlens array. In other words, instead of a liquid crystal display that uses a polarizing filter/polarizer to convert unpolarized light into linearly polarized light, a polarization grating with polarization conversion system (PG-PCS) is used, which converts unpolarized light with an efficiency from 80 to 90% can be converted into linearly polarized light. In this case, instead of a glass substrate, the liquid crystal layer/a liquid crystal panel (LC panel) is arranged in the polarization grating polarization conversion system.

According to a preferred embodiment, the first microlens array can have a glass substrate and an array of convex microlenses arranged on a coupling side of the glass substrate. The first microlens array can preferably be designed to focus light coupled into the first microlens array into a field of discrete, unpolarized light cones. That is, the light emitted from the light source is incident on the convex microlenses and converged by the array (and focused on a lens surface of the second microlens array). In other words, the first microlens array delimits the incident light in an angular range in such a way that the light coupled into a microlens cannot exit through an adjacent microlens and thus cannot generate ghost images/crosstalks.

According to a preferred embodiment, the vehicle lamp can have a graphics mask arranged between the first microlens array and the polarization grating. By arranging the graphics mask between the first microlens array and the polarization grating, part of the light is blocked depending on the motifs/the image content of the graphics mask, ie for example 30% is reflected and 70% is absorbed. The provision of the graphics mask means that fewer, ie larger, pixels can also be used in the liquid crystal layer since the resolution is improved by the graphics mask and the vehicle light can be made more cost-effectively. Without a graphics mask, the resolution depends solely on the pixel size of the liquid crystal layer that serves as the imager. In this case, the pixel size of the liquid crystal layer should be significantly less than 560 ppi, ie significantly less than 45x45 µm ² , which is currently hardly achievable.

A microlens is understood to mean a lens that is a few micrometers to 1 millimeter or up to 3 to 4 millimeters in diameter.

According to a preferred embodiment, the liquid crystal layer can have two glass substrates, each coated with an electrode contact layer, and liquid crystals arranged between the glass substrates. In particular, the liquid crystal layer may be formed to retard light radiating through the liquid crystal layer by half a wavelength depending on a voltage applied to the electrode contact layers. In particular, the polarization of the light remains unchanged when a voltage is applied, while the polarization of the light is changed when no voltage is applied. This means that the liquid crystal layer exhibits the effect of a λ/2 wave plate/retardation plate and changes the polarization of the light accordingly. Thus, for circularly polarized light radiating into the liquid crystal layer, the helicity is reversed (left or right circular polarization). In this case, the electrode contact layer can have transparent or non-transparent contacts. That is, with voltage applied, the liquid crystals, here in an ON state, do not change the polarization state/polarization of the light cones, while the liquid crystals with no voltage applied, here in an OFF state, change the polarization state/polarization from right-handed polarization left-handed polarization or change from left-handed polarization to right-handed polarization. In other words, without an applied voltage, the liquid crystal layer fulfills the properties of a λ/2 plate and rotates the phase by 180°. For linear polarization, this means that vertical polarization is converted into horizontal polarization and horizontal polarization into vertical polarization. The polarization of a transverse wave is understood to mean the direction of its oscillation. If this direction changes quickly and disorderly, it is called an unpolarized wave. The degree of polarization indicates the ordered part.

According to a preferred embodiment, the polarization grating can be designed to delay light radiating through the polarization grating by half a wavelength. This means that the polarization grating is designed as a λ/2 plate. The polarization grating is based on predefined oriented liquid crystals in which the polarization of the light is changed (without an applied voltage). This has the effect that unpolarized light cones coupled into the polarization grating are separated into two light cones. This means that the polarization grating divides the light into two light cones with right-handed polarization (Right Circular Polarization) or left-handed polarization (Left Circular Polarization).

According to a preferred embodiment, the scanning waveplate can be designed to retard light radiating through the scanning waveplate by a quarter wavelength, so that the light emitted from the scanning waveplate (34) is uniformly linearly polarized. Preferably, the light changed by the liquid crystal layer can have a first linear polarization direction and the light not changed by the liquid crystal layer can have a second linear polarization direction, which is perpendicular to the first linear polarization direction. This means that the light cones coupled into the scanning wave plate are converted into uniformly polarized light. The scanning waveplate can preferably be formed by two λ/4 plates whose optical axes are perpendicular to one another. Thus, the circularly polarized light radiating through the scanning waveplate is converted into linearly polarized light. This means that the scanning waveplate is segmented in such a way that each segment (i.e. each λ/4 plate) always converts circularly polarized light into linearly polarized light with the same orientation. Thus, in the case of a voltage applied to the liquid crystal layer (i.e. LC is ON), the light is split by the polarization grating into two cones of light, with right-hand and left-hand polarization, which passes through the liquid crystal layer unchanged and hits the scanning waveplate, so that the light with right-handed polarization hits the corresponding λ/4 plate and is converted to vertically polarized light, while the light with left-handed polarization hits the λ/4 plate oriented perpendicular thereto and is also converted to vertically polarized light. The λ/4 plates are preferably arranged in such a way that the light cones split by the polarization grating each impinge on one of the λ/4 plates. For example, the light cones polarized to the right by the polarization grating can impinge on one λ/4 plate, while the light cones polarized to the left by the polarization grating impinge on the other λ/4 plate. This also means that the light cones should not hit the two λ/4 plates/segments of the λ/4 plates at the same time in order to avoid incorrect polarization conversion. In other words, what is changed/rotated or not changed/not rotated by the liquid crystal layer impinges on the raster waveplate in such a way that each circularly polarized light cone is converted into linearly polarized light by an associated λ/4 plate of the raster waveplate. The light cones exiting the polarization grating with right-hand polarization are converted by a different part/segment of the scanning waveplate (i.e., a different λ/4 plate) than the light cones exiting the polarization grating with left-hand polarization. Due to the fact that the (right-handed or left-handed) polarization is only retained when a voltage is applied (or alternatively not retained when a voltage is applied) due to the interposed liquid crystal layer, the light rotated through the liquid crystal layer is rotated by the scanning waveplate into another one, preferably rotated by 90° Direction polarized (e.g. with horizontal polarization) than the light (e.g. with vertical polarization) in which the direction of polarization has not been rotated by the liquid crystal layer.

According to a preferred embodiment, the second microlens array can have a glass substrate and an array of convex microlenses arranged on a coupling-out side of the glass substrate. The second microlens array can preferably be designed to project light that is coupled into the second microlens array and is polarized in the linear direction. Thus, the light polarized in the linear direction from the scanning waveplate can be projected onto the imaging surface.

According to a preferred embodiment, the vehicle lamp can have an analyzer, which is connected downstream of the second microlens array and is designed as a linear polarization filter. The polarization direction of the analyzer can preferably correspond to the linear polarization direction converted by the scanning wave plate, in particular to the first polarization direction. This ensures that only the linearly polarized light that has not been rotated by the liquid crystal layer is transmitted through the analyzer and the linearly polarized light that has been rotated by the liquid crystal layer (and thus has a polarization direction rotated by preferably 90°) is transmitted is absorbed/blocked by the analyzer.

According to a further aspect of the invention, a vehicle lamp is provided for projecting a light image onto an imaging surface/imaging optics. The vehicle lamp has at least one light source. In addition, the vehicle light has a liquid crystal display connected downstream of the light source. The liquid crystal display has two mutually arranged polarization filters, preferably rotated by 90°, two glass substrates arranged between the polarization filters, two electrode contact layers arranged between the glass substrates and liquid crystals arranged between the electrode contact layers. According to the invention, the vehicle light has a microlens array connected downstream of the light source. The microlens array has a glass substrate, a graphics mask applied to one side of the glass substrate, a first array of convex microlenses arranged on a coupling-in side of the glass substrate, and a second array of convex microlenses arranged on a coupling-out side of the glass substrate and aligned with the first array. Preferably, the graphics mask can be formed as a layer of patterned chrome or the like. The graphic mask is also often referred to as a mask or Graphical Optical Blackout (Gobo). The microlenses can preferably be made of plastic or consist entirely of it. A microlens is understood to mean a lens that is a few micrometers to 1 millimeter or up to 3 to 4 millimeters in diameter.

In other words, the invention relates to a vehicle light in which the advantages of a microlens array projector and an LCD projector are combined with one another. In the LCD MLA projector according to the invention, the light emitted by a light source is modulated by the liquid crystal display (LCD, Liquid Crystal Display) for specific areas by switching on or off individual segments of the liquid crystal display. The liquid crystal display can be used in conjunction with a spatial light modulator (SLM) such as, in particular, the micro lens array (MLA). It can thus be modulated which part of the graphic mask is illuminated. This has the advantage that a particularly efficient system is provided in which a maximum number of displayable, independent motifs is as large as the number of microlenses in an array, i.e. up to 120, 125 or 140 independent motifs. As a result, the vehicle lamp can be designed with fewer light sources (LEDs), can be fitted into a smaller installation space, and can be manufactured more cost-effectively. In addition, there are new possibilities to increase the brightness compared to a conventional LCD projector.

In other words, the liquid crystal display consists of a polariser/first polarizing filter, a (first) glass substrate with transparent electrical contacts, liquid crystals, a (second) glass substrate with transparent electrical contacts and an analyzer/second polarizing filter. Unpolarized, collected (LED) light is polarized linearly, i.e. in the vertical direction, for example, by the polarizer, whereby about 50% of the incident light is absorbed by the polarizer. The liquid crystals sandwiched between the two glass substrates can have an ON state or an OFF state depending on an applied voltage. In the ON state, molecules of the liquid crystals are rotated so that the direction of polarization of the light is changed/rotated by preferably 90°, i.e. to horizontal, for example. In the OFF state, the molecules of the liquid crystals align in the same orientation when a voltage is applied, so that the direction of polarization of the light is not changed. The analyzer has the function of allowing the light that is preferably rotated through 90°, i.e. polarized in the horizontal direction, for example, to pass through. Thus, the analyzer blocks the light passing through the OFF state of the liquid crystals and transmits the light of altered/manipulated polarization state, i.e., passing through the ON state of the liquid crystals.

According to the further aspect of the invention, the glass substrate of the microlens array is formed by the glass substrates of the liquid crystal display, the first array being arranged on a coupling-in side of a first glass substrate of the liquid-crystal display and the second array being arranged on a coupling-out side of a second glass substrate of the liquid-crystal display. In other words, the functions of the liquid crystal display and the microlens array can be linked. At this time, an optical thickness in terms of refractive indexes of the liquid crystals and the glass substrates should be the same for the microlens array.

According to a development of the preferred embodiment, the graphics mask can be formed by one of the electrode contact layers, which is designed as a non-transparent structured electrode contact layer.

This means that the non-transparent structured electrode contact layer forms the graphic mask through its non-transparent part.

According to an alternative development of the preferred embodiment, the graphics mask can be applied to an insulating layer, with the insulating layer being applied to one of the electrode contact layers. This means that the graphics mask is applied to the electrode contact layer with the interposition of an insulating layer, such as a dielectric layer, and only allows part of the incident light to pass depending on the motifs/the image content.

The at least one light source of the vehicle light can preferably be in the form of a light-emitting diode (LED). Alternatively, the at least one light source can be an organic LED (OLED) and/or a laser diode and/or a light source working according to a Laser Activated Remote Phosphor (LARP) principle and/or a halogen lamp and/or a a gas discharge lamp (High Intensity Discharge (HID)), and/or in connection with a projector working according to a Digital Light Processing (DLP) principle. A large number of alternatives are therefore available as a light source for the vehicle lamp according to the invention.

According to the present invention, a vehicle has a vehicle lamp according to the present invention.

The vehicle can be an aircraft or a water-based vehicle or a land-based vehicle. The land vehicle can be an automobile or a rail vehicle or a bicycle. The vehicle is particularly preferably a truck or a passenger car or a motorcycle. Furthermore, the vehicle can be designed as a non-autonomous or partially autonomous or autonomous vehicle.

• 1 einen schematischen Aufbau einer Fahrzeugleuchte für ein Fahrzeug gemäß einem ersten Beispiel des Stands der Technik,
• 2 einen schematischen Aufbau einer Fahrzeugleuchte für ein Fahrzeug gemäß einem zweiten Beispiel des Stands der Technik,
• 3 einen schematischen Aufbau in einer Explosionsdarstellung einer Fahrzeugleuchte für ein Fahrzeug gemäß einem ersten Ausführungsbeispiel,
• 4a und 4b einen schematischen Aufbau in einer Explosionsdarstellung einer Fahrzeugleuchte für ein Fahrzeug gemäß einem zweiten Ausführungsbeispiel, und
• 5 einen schematischen Aufbau in einer Explosionsdarstellung einer Fahrzeugleuchte für ein Fahrzeug gemäß einem dritten Ausführungsbeispiel.

The invention is to be explained in more detail below using exemplary embodiments. The figures show:

• 1 a schematic structure of a vehicle lamp for a vehicle according to a first example of the prior art,
• 2 a schematic structure of a vehicle lamp for a vehicle according to a second example of the prior art,
• 3 a schematic structure in an exploded view of a vehicle lamp for a vehicle according to a first embodiment,
• 4a and 4b a schematic structure in an exploded view of a vehicle lamp for a vehicle according to a second embodiment, and
• 5 a schematic structure in an exploded view of a vehicle lamp for a vehicle according to a third embodiment.

1 FIG. 12 shows a schematic structure of a vehicle lamp 1 according to a first example of the prior art, which is explained for a better understanding of the invention. The vehicle lamp 1 has a light source 2 which is 1 is not explicitly shown, but is only indicated with regard to their position. The light source 2 can contain collimating optics that collimate the light in the angular range into a predefined light cone, for example of ±10°. The light source 2 emits light towards an imaging surface 4 which is 1 is not explicitly shown, but is only indicated with regard to their position.

The vehicle light 1 has a liquid crystal display 6 connected downstream of the light source 2 . The liquid-crystal display 6 has two linear polarization filters 8, 10, which are preferably rotated by 90° relative to one another and are referred to as polarizer 8 and analyzer 10 below. Liquid crystals 12 are arranged between the polarizer 8 and the analyzer 10 and are arranged between two glass substrates (not shown explicitly). The glass substrates are each coated with an electrode contact layer via which a voltage can be applied so that molecules of the liquid crystals 6 align.

The vehicle lamp 1 has a microlens array 14 which is arranged downstream of the liquid crystal display 6 in the first exemplary embodiment. This means that the liquid crystal display 6 is arranged in front of the microlens array 14 in the beam path of the light.

The microlens array 14 has a glass substrate, on one side of which a graphics mask (not shown explicitly) is arranged. The graphic mask is designed in particular as a graphic optical blackout (gobo). Preferably, the graphics mask can be formed as a layer of patterned chrome or the like. The graphic mask can have a large number of motifs or an overall image content.

The microlens array 14 has a first array of convex microlenses arranged on a coupling-in side of the glass substrate and a second array of convex microlenses arranged on a coupling-out side of the glass substrate. The microlenses of the first array and the second array are aligned with each other. The microlenses can preferably be made of plastic or consist entirely of it. The second array of convex microlenses serves as imaging optics, so no additional lenses are required.

The liquid crystals 12 can be switched between an ON state 16 and an OFF state 18 in regions. In the example shown, the liquid crystals 12 are in the form of twisted nematic liquid crystals, although it is also possible to use other technologies for the liquid crystals. The ON state 16 is represented by a light area in the illustrated embodiment, while the OFF state 18 is represented by a dark/black area in the illustrated embodiment. Thus, unpolarized, collected (LED) light is linearly polarized by the polarizer 8, ie, for example, in the vertical direction. With no voltage applied to the liquid crystals 12, the liquid crystals 12 are in the ON state in which molecules of the liquid crystals 12 (due to an Orien applied to the glass substrates tationsschicht) are rotated and thus the polarization direction of the light by preferably 90 °, ie for example to horizontal, is changed. The analyzer 10 is arranged rotated by preferably 90° to the polarizer 8, so that the light rotated by the liquid crystals 12, which is now, for example, horizontally polarized, is transmitted. In other words, the liquid crystals 12 contribute to projection on the imaging surface 4 in the ON state. When a voltage is applied to the liquid crystals 12, the liquid crystals 12 are in the OFF state in which the molecules of the liquid crystals 12 align in the same orientation so that the direction of polarization of the light is not changed, ie remains polarized vertically, for example. The analyzer 10 is arranged rotated by preferably 90° to the polarizer 8, so that the light which is not rotated by the liquid crystals 12 and which is now, for example, vertically polarized, is not transmitted but is blocked. In other words, the liquid crystals 12 do not contribute to the projection on the imaging surface 4 in the OFF state. In this way, the individual motifs/image content assigned to the microlenses can be projected in a switchable manner. This means that light only shines through the microlenses in the area of which no voltage is applied to the upstream liquid crystal display 6 . Consequently, which part of the graphics mask is illuminated can be modulated.

Alternatively, although not illustrated, it would also be possible to form the liquid crystals such that, with no voltage applied to the liquid crystals, the liquid crystals are in the OFF state in which the molecules of the liquid crystals align in the same orientation so that the polarization direction of the light is not changed, i.e. remains vertically polarized, for example, and when the voltage is applied the liquid crystals are in the ON state in which the molecules of the liquid crystals are rotated (due to an orientation layer applied to the glass substrates) and thus the polarization direction of the Light is preferably changed by 90°, i.e. too horizontally, for example.

2 12 shows a second example of the vehicle lamp 1 of the related art. The structure of the vehicle lamp 1 according to the second example essentially corresponds to the structure of the first example. The construction of the vehicle lamp 1 according to the second example differs only in the arrangement of the microlens array 14. In the second example, the microlens array 14 is arranged in front of the liquid crystal display 6. This means that the liquid crystal display 6 is arranged behind the microlens array 14 in the beam path of the light. Thus, a portion of the light is reflected prior to entering the liquid crystal display 6 depending on the graphics mask of the microlens array 14 .

3 shows a first embodiment of the vehicle lamp 1 according to the invention. In the third embodiment, the functions of the liquid crystal display 6 and the microlens array 14 are linked. This means that the glass substrate of the microlens array 14 is formed by the glass substrates of the liquid crystal display 6, with the first array on a coupling-in side of a first glass substrate (in the beam path) of the liquid-crystal display 6 and the second array on a coupling-out side of a second glass substrate (in the beam path). Liquid crystal display 6 is arranged. Thus, the light linearly polarized by the polarizer 8 strikes the microlenses of the first array, is then rotated in the ON state 16 of the liquid crystals 12 or is not rotated in the OFF state 18 of the liquid crystals 12, then passes through the microlenses of the first array, and is then transmitted or blocked by the analyzer 10 depending on the ON state 16 or OFF state 18 .

In this case, the graphics mask of the microlens array 14 can be formed by one of the electrode contact layers, which is designed as a non-transparent structured electrode contact layer. This means that the non-transparent structured electrode contact layer forms the graphic mask through its non-transparent part. Alternatively, the graphics mask may be deposited on an insulating layer, with the insulating layer being deposited on one of the electrode contact layers. This means that the graphics mask is applied to the electrode contact layers with an insulating layer such as a dielectric layer in between, and only allows part of the incident light to pass depending on the motifs/the image content.

4a and 4b 12 shows a second embodiment of a vehicle lamp 20 in which the polarizer of the first embodiment has been replaced by a so-called polarization grating with polarization conversion system (PG-PCS). while showing 4a the vehicle lamp 20 with two exemplary motifs in an ON state while 4b 12 shows the vehicle light 20 in an OFF state with two example motifs.

The vehicle lamp 20 according to the second exemplary embodiment has a light source 22 . The light source 22 emits light toward an imaging surface 24 that is 4a and 4b is not explicitly shown, but is only indicated with regard to their position.

The vehicle lamp 20 has a first microlens array 26 downstream of the light source 22 . The first microlens array 26 can preferably have a glass substrate and an array of convex microlenses arranged on a coupling-in side of the glass substrate. In particular, the first microlens array 26 may be configured to converge (and focus on a lens surface of the second microlens array 38) light coupled into the first microlens array 26 . In other words, the first microlens array 26 limits the incoming light in an angular range such that the light coupled into a microlens cannot exit through an adjacent microlens and thus generate ghost images/crosstalks.

The vehicle light 20 has a polarization grating 28 connected downstream of the first microlens array 26 . In particular, the polarization grating 28 can be configured to diffract light radiating through the polarization grating 28 into a light cone with right-hand polarization and a light cone with left-hand polarization. The polarization grating is based on predefined oriented liquid crystals in which the polarization of the light is changed (without an applied voltage). Thus, the unpolarized light cones coupled into the polarization grating 28 are divided into two light cones 30, 32 that are separated in the angular range. That is, the polarization grating 28 splits the light into a cone of light with right-hand polarization (Right Circular Polarization) 30 and a cone of light with left-hand polarization (Left Circular Polarization) 32 .

The vehicle light 20 has a grid wave plate 34 connected downstream of the polarization grating 28 . In particular, the scanning waveplate 34 can be configured to retard light radiating through the scanning waveplate 34 by a quarter wavelength. This means that the light cones coupled into the scanning wave plate 34 are converted into uniformly polarized light. In particular, the light cones 30, 32, which are coupled into the scanning wave plate 34 and are separated in the angular range, are converted into linearly polarized light. The scanning waveplate 34 can preferably be formed by two λ/4 plates 34a, 34b, the optical axes of which are perpendicular to one another. The light cones 30, which emerge from the polarization grating 28 with right-hand polarization, from another part of the scanning wave plate 34, in 4a from the λ/4 plate 34a converted as the light cones 32 exiting the polarizing grating 28 with left-handed polarization into 4a from the λ/4 plate 34b. This causes the light cones 30, 32 in 4a converted to vertically polarized light 36.

The vehicle lamp 20 has a second microlens array 38 downstream of the grid wave plate 34 . The second microlens array 38 can preferably have a glass substrate and an array of convex microlenses arranged on a coupling-out side of the glass substrate. The second microlens array 38 can preferably be designed to project light that is coupled into the second microlens array and is polarized in the linear direction. Thus, the light linearly polarized from the scanning waveplate 34 can be projected onto the imaging surface 24 .

In addition, the vehicle light 20 has a liquid crystal layer 42 arranged between the polarization grating 28 and the grid wave plate 34 . In particular, the liquid crystal layer 42 may be formed to retard light radiating through the liquid crystal layer 42 by half a wavelength depending on an applied voltage. That is, the liquid crystal layer 42 exhibits the effect of a λ/2 wave plate/retardation plate and changes the polarization of the light accordingly. Thus, for circularly polarized light radiating into the liquid crystal layer 42, the helicity is reversed (left or right circular polarization). That is, with voltage applied, here in an ON state, the liquid crystals do not change the polarization state/polarization of the light cones 30, 32, while the liquid crystals 42 with no voltage applied, here in an OFF state, change the polarization state/polarization change from right-hand polarization to left-hand polarization and from left-hand polarization to right-hand polarization, respectively. In other words, without an applied voltage, the liquid crystal layer fulfills the properties of a λ/2 plate and rotates the phase by 180°. For linear polarization this would mean that vertical polarization is converted into horizontal polarization and horizontal polarization into vertical polarization.

Accordingly, the vehicle lamp 20 functions as follows: Light emitted by the light source 22 strikes the first microlens array 26 and is separated in the angular range. The light cones separated in the angular range by the first microlens array 26 impinge on the polarization grating 28 and are each divided into a right-hand polarized light cone 30 and a left-hand polarized light cone 32 . The right-hand polarized light cones 30 and left-hand polarized light cones 32 impinge on the liquid crystal layer 42 are delayed by half a wavelength or not changed depending on whether a voltage is applied. Thus, the right-hand polarized light cones 30 and left-hand polarized light cones 32 are not changed without an applied voltage (cf. 4a) , while the right-hand polarized light cone 30 and left-hand polarized light cone gel 32 change their handedness from right-handed to left-handed or from left-handed to right-handed when voltage is applied (cf. 4b) . Thereafter, the right-hand polarized light cones 30 and left-hand polarized light cones 32 hit the scanning waveplate 34, are delayed by a quarter wavelength, so that they are converted into linearly polarized light. The right-hand polarized light cone 30, unchanged by the liquid crystal layer 42, is converted by a first λ/4 plate 34a and the left-hand polarized light cone 32, unchanged by the liquid crystal layer 42, by a second λ/4 plate 34a to vertically polarized light 36 ( see. 4a) . In addition, the left-hand polarized light cone 32 rotated by the liquid crystal layer 42 is converted by the first λ/4 plate 34a and the right-hand polarized light cone 30 rotated by the liquid crystal layer 42 by the second λ/4 plate 34b to horizontally polarized light 40 ( see. 4b) . The linearly (ie vertically or horizontally) polarized light 38 or 40 impinges on the second microlens array 38 and is projected in the direction of the imaging surface 24 . The linearly (ie vertically or horizontally) polarized light 38 or 40 shines through the analyzer 44 and is blocked depending on its polarization direction (horizontally polarized light 40 is blocked, cf. 4b) or transmitted (vertically polarized light 38 is transmitted, cf. 4a) .

Preferably, the liquid crystal layer 42 may comprise two glass substrates each coated with an electrode contact layer and liquid crystals arranged between the glass substrates. In this case, the electrode contact layer can have transparent or non-transparent contacts.

The vehicle lamp 20 can preferably have an analyzer 44 which is connected downstream of the second microlens array 38 and is designed as a linear polarization filter. The polarization direction of the analyzer 44 can preferably correspond to the linear polarization direction converted by the scanning wave plate, in this case the vertical polarization direction. This ensures that only the linearly polarized light that has not been rotated by the liquid crystal layer 42 (i.e. the light with a vertical polarization direction) is transmitted through the analyzer 44 and the linearly polarized light that has been rotated by the liquid crystal layer 42 (i.e the light with horizontal polarization direction) is absorbed/blocked by the analyzer 44.

In summary, in the second embodiment of the vehicle lamp 20, instead of a liquid crystal display 6 (as in the first embodiment) which uses a polarization filter/polarizer 8 to convert unpolarized light into linearly polarized light, a polarization grating polarization conversion system is used, in which case in the first embodiment with a transmission of 50% can be achieved with the polarizer-analyzer combination and in the second exemplary embodiment with the PG-PCS a transmission of 80 to 90% can be achieved. In this case, a liquid crystal panel (LC panel) is arranged instead of a glass substrate in the polarization grating polarization conversion system.

In the second embodiment, the vehicle lamp 20 has a graphics mask 46 arranged between the first microlens array 26 and the polarization grating 28 . The graphic mask 46 is designed in particular as a graphic optical blackout (gobo). Preferably, graphics mask 46 may be formed as a layer of patterned chrome or the like. The graphics mask 46 can have a large number of motifs or an overall image content. The graphics mask 46 is applied in particular to a coupling-in side of the polarization grating 28 . That is, the light emitted from the light source is incident on the convex microlenses of the first microlens array 26 and converged by the array (and focused on a lens surface of the second microlens array 38). By arranging the graphics mask 46 between the first microlens array 26 and the polarization grating 28, part of the light is blocked depending on the motifs/the image content of the graphics mask 40, i.e. approximately 30% is reflected and 70% is absorbed.

In the 5 The third embodiment shown essentially corresponds to the second embodiment, the third embodiment only having no graphics mask 46 . This means that the liquid crystal layer 42 alone acts as an image generator, which is possible with a sufficiently small pixel size.

Reference List

1

vehicle light

2

light source

4

imaging surface

6

liquid crystal display

8th

polarizer

10

analyzer

12

liquid crystals

14

microlens array

16

ON state

18

OFF state

20

vehicle light

22

light source

24

imaging surface

26

First microlens array

28

polarization grating

30

Right-hand polarized light cone

32

Left-hand polarized light cone

34

grid wave plate

36

vertically polarized light

38

Second microlens array

40

horizontally polarized light

42

liquid crystal layer

44

analyzer

46

graphic mask

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely 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

• DE 202019101801 U1 [0004]
• DE 102019124697 A1 [0005]

Claims (10)

Vehicle light (20) for a vehicle for projecting a light image onto an imaging surface (24), having at least one light source (22), a first microlens array (26) connected downstream of the light source (22), a polarization grating (28 ), a grid wave plate (34) downstream of the polarization grating (28) and a second microlens array (38) downstream of the grid wave plate (34), characterized in that the vehicle lamp (20) has a lens arranged between the polarization grating (28) and the grid wave plate (34). Liquid crystal layer (42). Vehicle light (1) after claim 1 , characterized in that the first microlens array (26) has a glass substrate and an array of convex microlenses arranged on a coupling-in side of the glass substrate and/or the second microlens array (38) has a glass substrate and an array of convex microlenses arranged on a coupling-out side of the glass substrate . Vehicle light (1) after claim 1 or 2 , characterized in that the vehicle lamp (20) has a graphics mask (46) arranged between the first microlens array (26) and the polarization grating (28). Vehicle light (1) according to one of Claims 1 until 3 , characterized in that the liquid crystal layer (42) has two glass substrates, each coated with an electrode contact layer, and liquid crystals arranged between the glass substrates, the liquid crystal layer (42) being designed in order, depending on a voltage applied to the electrode contact layers, to shift light radiating through the liquid crystal layer by one to delay half a wavelength, in particular when a voltage is applied, the polarization of the light remains unchanged and without applied voltage, the polarization of the light is changed. Vehicle light (1) according to one of Claims 1 until 4 , characterized in that the polarizing grating (28) is adapted to diffract light radiating through the polarizing grating (28) into a cone of right-hand polarization and a cone of left-hand polarization. Vehicle light (1) according to one of Claims 1 until 5 , characterized in that the scanning waveplate (34) is designed to retard light radiating through the scanning waveplate (34) by a quarter wavelength, so that the light emitted from the scanning waveplate (34) is uniformly linearly polarized, the light passing through the liquid crystal layer (42) changed light has a first linear polarization direction and the light not changed by the liquid crystal layer (42) has a second linear polarization direction perpendicular to the first linear polarization direction. Vehicle light (1) after claim 6 , characterized in that the scanning waveplate (34) is formed by two λ/4 plates whose optical axes are perpendicular to one another. Vehicle light (1) according to one of Claims 1 until 7 , characterized in that the vehicle light (20) has an analyzer (44) connected downstream of the second microlens array (38), which is designed as a linear polarization filter, the polarization direction of the analyzer (44) preferably corresponding to the first linear polarization direction. Vehicle light (1) for a vehicle for projecting a light image onto an imaging surface (4), with at least one light source (2) and a liquid crystal display (6) connected downstream of the light source (2), the liquid crystal display (6) being two to one another, preferably around 90° rotated polarization filters (8, 10), two glass substrates arranged between the polarization filters (8, 10), two electrode contact layers arranged between the glass substrates and liquid crystals (12) arranged between the electrode contact layers, the vehicle lamp (1) being one of the light source (2) downstream microlens array (14), wherein the microlens array (14) has a glass substrate, a graphics mask applied to one side of the glass substrate, a first array of convex microlenses arranged on a coupling side of the glass substrate and a second array arranged on a coupling-out side of the glass substrate of convex microlenses points, the glass substrate of the microlens array (14) being formed by the glass substrates of the liquid crystal display (6), the first array on a coupling-in side of a first glass substrate of the liquid-crystal display (6) and the second array on a coupling-out side of a second glass substrate of the liquid-crystal display (6 ) is arranged. Vehicle with a vehicle lamp (1; 20) according to one of Claims 1 until 9 .

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