Lighting device and method for projecting a symbol onto a roadway

Abstract

Lighting device for projecting a symbol (12) onto a roadway (10) for a motor vehicle, with a left headlight having a plurality of first light sources for illuminating the road (10), a right headlight spaced apart from the left headlight, having a plurality of second light sources for illuminating the road (10), a control device for projecting a symbol (12) onto the roadway (10) using the left headlight and the right headlight, wherein the control device splits the symbol (12) to be projected into a left partial image (20) and a right partial image (22) and the control device is designed to allow the left partial image (20) to be projected only by the left headlight and the right partial image (22) only by the right headlight, characterized by the fact that The left partial image (20) projected by the left headlight and the right partial image (22) projected by the right headlight overlap in a separating border area (24) with a predefined width within the range of the positional tolerances of an expected offset of the partial images (20, 22) to represent the symbol (12).

Description

[0001] The invention relates to a lighting device and a method by which a motor vehicle can project a symbol onto a roadway.

[0002] From DE 10 2015 201 764 A1 a motor vehicle is known in which a headlight can display a symbol on a roadway by means of a correspondingly adapted light distribution.

[0003] From DE 10 2016 119 567 A1 a headlight system is known in which a projected symbol can be composed of two partial images projected by different headlights, which can overlap or be adjacent to each other.

[0004] From DE 10 2014 214 552 A1 it is known to project a light symbol by switching a laser light spot on and off at high frequency in front of a motor vehicle.

[0005] DE 10 2014 002 308 A1 shows a lighting device of a motor vehicle with two LED headlights that illuminate the same area simultaneously.

[0006] DE 10 2009 051 265 A1 shows a display unit of a motor vehicle, with the help of which image information can be displayed on a vertically running wall.

[0007] DE 10 2016 001 915 A1 shows a lighting device with a left and a right pixel light system, in which the respective pixel light systems can perform different lighting functions and the pixels illuminated by the different pixel light systems overlap exactly.

[0008] There is a constant need to be able to clearly recognize a symbol projected by a spotlight.

[0009] The object of the invention is to specify measures that enable good recognizability of a symbol projected by a headlight.

[0010] The problem is solved according to the invention by a lighting device having the features of claim 1 and a method having the features of claim 10. Preferred embodiments of the invention are specified in the dependent claims and the following description, each of which can individually or in combination represent an aspect of the invention.

[0011] According to the invention, a lighting device for projecting a symbol onto a roadway for a motor vehicle is provided, comprising a left headlight having a plurality of first light sources, in particular provided by a display, for illuminating the roadway, a right headlight spaced apart from the left headlight having a plurality of second light sources, in particular provided by a display, for illuminating the roadway, and a control device for projecting a symbol onto the roadway using the left headlight and the right headlight, wherein the control device splits the symbol to be projected into a left partial image and a right partial image, and the control device is configured to allow the left partial image to be projected only by the left headlight and the right partial image only by the right headlight.wherein the left partial image projected by the left headlight and the right partial image projected by the right headlight overlap in a separating border area with a predefined width within the range of positional tolerances of an expected offset of the partial images to represent the symbol.

[0012] The headlights of a motor vehicle are generally positioned at the left and right edges of the vehicle, i.e., off-center to the vehicle's central axis. If a symbol is projected onto the road from one of the headlights, essentially centered on the vehicle, so that the driver can intuitively perceive it, one edge of the symbol will be farther from the corresponding headlight than the opposite edge. Consequently, the light beams from the points of light projecting one edge travel a different distance than those projecting the other edge. This results in different angles relative to the horizontal and / or vertical at which the respective light beams strike the road.This can cause one light source to project a larger pixel than another light source in the same headlight. Especially if the symbol is projected at a considerable distance from the vehicle, the pixels at the farther edge of the symbol can be so large that they can be perceived by the driver as such, resulting in a stair-step effect. The farther edge of the symbol, formed by multiple projected light sources as a light / dark boundary, can thus be perceived by the driver as a stair-stepped or pixelated line rather than a straight one. This can impair the perceived sharpness of the symbol and make it more difficult to see.

[0013] Due to the control unit's division of the symbol into a left and a right sub-image, it is possible for the sub-image projected further away by one headlight to be projected by the headlight positioned closer to it. Because of the shorter beam path and the larger, less shallow angle at which the corresponding light beam strikes the road surface, the pixels projected to form the edge are smaller than if this area were projected by the other headlight. This avoids a pixelated edge to the symbol or at least reduces the extent of stair-stepping effects at the symbol's edge.By dividing the symbol to be projected into sub-images to be displayed by different spotlights, a pixelated stair-step effect at the edges of the symbol can at least be reduced, thus enabling good recognizability of a symbol projected by a spotlight.

[0014] It should be noted that an exact projection of the partial images directly onto one another can be difficult, and that the projected partial images may overlap at least partially in their dividing line areas when displaying the symbol. For example, unevenness in the surface, pitching movements of the vehicle, and / or variations in the spacing of the headlights can lead to an offset of the projected partial images. However, the perceived sharpness at the light / dark boundaries at the edge of the symbol is not affected, so good recognizability is maintained even with a partial offset of the projected partial images.In particular, with a projected symbol where the dividing line runs through an illuminated area, a partial overlap of the dividing edge areas of the sub-images can be intentionally provided. This prevents a dark stripe between the sub-images, which would be noticeable to the driver as an image defect, if the sub-images are offset from each other. This can be the case, for example, if the symbol is intended to illuminate a lane for motor vehicles between a median strip and the edge of the road. With a projected symbol where the dividing line runs through an unilluminated area, a gap can be intentionally provided between the sub-images. This prevents the illuminated areas, which are normally separated, from merging and blurring together if the sub-images are offset from each other.This can be the case, for example, if two virtual lanes for the tires of the motor vehicle are to be represented as a symbol on the roadway to indicate the further route of the motor vehicle.

[0015] The headlight can have multiple light sources, particularly LEDs, which illuminate, for example, a display projected by a lens. The headlight's light source can generate the symbol using LEDs, an LCD (liquid crystal display), and / or a DMD (dot matrix display), which can provide multiple, individually controllable light sources for projecting the respective assigned pixel. The LCD and / or DMD can provide a multitude of regularly arranged light sources, which can be individually switched on and off by the control unit to assemble a specific symbol with the pixels projected onto the road by these light sources. The lighting control unit can, in particular, display multiple different symbols.This can lead to situations where symbols need to be projected that would likely result in a jagged, pixelated edge if projected by only one headlight, and other symbols where such a jagged edge is not a concern. Preferably, the control device is designed to divide the symbol into sub-images and project these sub-images from the different headlights only when a jagged, pixelated edge is likely to occur when projected by only one headlight. Particularly with smaller symbols and / or symbols projected at a short distance from the headlights at a shallow angle to the road, it may be sufficient to project the symbol from only one headlight. This minimizes the effort required to project the symbol.At the same time, distributing a symbol that would be difficult to display with a single spotlight across multiple spotlights allows for a comparatively low resolution of the light sources. This eliminates the need to increase the number of light sources or reduce their size, thus keeping manufacturing costs low.

[0016] In particular, the first and second sub-images each have a substantially similar, overlapping dividing line. If the sub-images are substantially identical in a dividing line adjacent to the sub-images, which may have a predefined width within the range of the positional tolerances of an expected offset between the sub-images, then a partial overlap of the projected sub-images caused by an offset has essentially no effect on the displayed symbol. In this case, the symbol may have a narrower width on the order of the offset and / or may exhibit increased brightness in the area of ​​the overlapping dividing line regions of the projected sub-images, but these deviations are generally not consciously perceived by a driver as impairing the perception of the symbol.

[0017] Preferably, the dividing line area runs longitudinally along a dividing line between the first and second sub-images, remaining essentially unchanged. A longitudinal offset of the sub-images thus does not result in a sudden jump in lines crossing the dividing line. Instead, the longitudinal dividing line can run within a region of the symbol where lines crossing the dividing line are avoided as much as possible.

[0018] Preferably, the dividing line area remains essentially unchanged within a width that runs perpendicular to a dividing line between the first and second sub-images. A transverse offset of the sub-images can therefore only lead to a change in brightness in the area of ​​the dividing line. Blurring of areas of the symbol that are actually separated by light / dark contrasts can be avoided.

[0019] The dividing line can be a straight line, allowing for a simple division of the symbol into sub-images. However, it is also possible for the dividing line to have a different shape, particularly to avoid image distortions at the edges of the projected sub-images. For example, the dividing line can be curved and / or zigzag-shaped, perhaps to appropriately divide clearly defined sections of the symbol into the different sub-images.

[0020] In particular, the symbol is designed without illumination within the dividing line area. This allows the dividing line to run through a dark area of ​​the symbol where essentially no projected pixels are intended. As a result, any offset between the partial images cannot be perceived by the driver.

[0021] Preferably, the symbol has a left illumination area contained only in the left part of the image and a right illumination area contained only in the right part. The left illumination area and the right illumination area can be clearly separated from each other by a dark area in which no projected pixels are provided. This makes it particularly easy to divide the left illumination area and the right illumination area for projection onto the left headlight and the right headlight.

[0022] It is particularly advantageous for the first and / or second light sources to be arranged regularly, especially with substantially identical spacing, in rows and columns. This makes it easier to deactivate and / or activate different light sources row by row and / or column by column for the projection of a specific geometrically defined symbol, so that it is not necessary to control all light sources individually. This allows for faster switching of the light sources.

[0023] In particular, the control device is designed to position a longitudinal dividing line in the symbol to be projected, dividing the symbol into a left and a right sub-image, at a position in the transverse direction where the symbol remains essentially unchanged in the longitudinal direction and within a certain border width in the transverse direction. The dividing line is positioned, in particular, off-center to the symbol's transverse extent. The dividing line, preferably a straight line, does not necessarily have to run through the center of the symbol. Instead, the dividing line can be positioned such that as few image defects as possible are to be expected in the symbol composed of the projected sub-images. This allows, in particular, the resulting sub-images to be of different sizes.

[0024] Preferably, the control device is configured to project an irregularly shaped central area of ​​the symbol exclusively from either the first or the right headlight. Complex shapes in the central area of ​​the symbol can be assigned to either the left or the right sub-image, thus avoiding a central division of the symbol that could lead to perceptible image errors if the projected sub-images are misaligned. For example, an arrow-shaped central area of ​​the symbol can be assigned only to the left or only to the right sub-image, preventing the arrowhead from becoming blurred due to a misalignment of the projected sub-images.

[0025] The invention further relates to a method for projecting a symbol onto a roadway for a motor vehicle, in which, in particular with the aid of the lighting device which can be designed and further developed as described above, a left partial image of the symbol is projected only from a left headlight and a right partial image of the symbol is projected only from a right headlight spaced apart from the left headlight in such a way that the left partial image projected by the left headlight and the right partial image projected by the right headlight overlap in a separating border area with a predefined width in the range of the positional tolerances of an expected offset of the partial images to represent the symbol.

[0026] The method can be further developed, particularly as explained above with regard to the lighting device. By dividing the symbol to be projected into partial images to be illuminated by different spotlights, a pixelated stair-stepping effect at the edges of the symbol can be at least reduced, thus ensuring good recognizability of a symbol projected by a spotlight.

[0027] The invention is explained below by way of example with reference to the accompanying drawing, using a preferred embodiment as an example, wherein the features shown below can represent an aspect of the invention, either individually or in combination. It shows: Fig. 1: A schematic representation of the principle of projecting a symbol using a lighting device.

[0028] In Fig. Figure 1 shows a roadway 10 where a symbol 12 is projected onto the roadway 10 from only the left headlight of a motor vehicle's lighting system. In the illustrated embodiment, the projected symbol is a roadway illumination, with the projected pixels of the symbol 12 projected only onto the right lane of the roadway 10 to clarify for the driver the area of ​​the roadway 10 that he or she can drive on. The symbol 12 projected onto the roadway 10 has a substantially trapezoidal shape. Since the symbol 12 is projected only from the left headlight, the path of the projected light at a left edge 14 pointing towards the center of the roadway is shorter than the path of the projected light at a right edge 16 pointing towards the right edge of the roadway.Since the headlight has a plurality of light point sources of a display arranged in rows and columns, it is possible that a light / dark boundary imaged by a long beam path, as is the case with the right edge 16 of the in . Fig. The symbol 12 shown in 1 appears pixelated and has a stair-like gradient instead of a straight line.

[0029] To reduce the stepped appearance of the right edge 16 of the projected symbol 12, the lighting device is designed such that, in such a situation, a control unit splits the symbol 12 before projection along a dividing line 18 into a left partial image 20 to be projected by the left headlight and a right partial image 22 to be projected by a right headlight. Since the right partial image 22 differs from the one shown in Fig. In the situation shown in 1, if the light is projected not from the left headlight but from the right headlight, the beam path for the right edge 16 is shorter, so that the Fig. The depicted stair-step effect can be reduced or even avoided.

[0030] In the illustrated embodiment, the dividing line 18 for splitting the symbol 12 into the sub-images 20 and 22 is not positioned centrally, but off-center within the symbol 12. This allows the dividing line 18 to be positioned at a point in the transverse direction where the right edge 16 lies completely within the right sub-image 22. A possible offset between the left sub-image 20 projected by the left headlight and the right sub-image 22 projected by the right headlight therefore does not result in a jump in the right edge 16 of the symbol 12 that is perceptible to the driver. Furthermore, the dividing line 10 can be positioned at a point and / or run from bottom to top, such that the dividing edge areas 24 of the left sub-image 20 and the right sub-image 22, which adjoin the dividing line 18 laterally, are essentially identical.The separating edge areas 24 can have a predefined edge area width in the transverse direction, which may be on the order of a possible offset of the left partial image 20 to the right partial image 22. If there is a possible offset of the left partial image 20 projected by the left headlight to the right partial image 22 projected by the right headlight, there is no change in the shape of the symbol 12 perceptible to the driver. Image errors perceptible to the driver in the symbol 12, which is composed of the projection of the left partial image 20 and the right partial image 22, can thus be avoided.

Claims

[1] Lighting device for projecting a symbol (12) onto a roadway (10) for a motor vehicle, with a left headlight having a plurality of first light sources for illuminating the road (10), a right headlight spaced apart from the left headlight, having a plurality of second light sources for illuminating the road (10), a control device for projecting a symbol (12) onto the roadway (10) using the left headlight and the right headlight, wherein the control device splits the symbol (12) to be projected into a left partial image (20) and a right partial image (22) and the control device is designed to allow the left partial image (20) to be projected only by the left headlight and the right partial image (22) only by the right headlight, characterized by , that The left partial image (20) projected by the left headlight and the right partial image (22) projected by the right headlight overlap in a separating border area (24) with a predefined width within the range of the positional tolerances of an expected offset of the partial images (20, 22) to represent the symbol (12). [2] Lighting device according to claim 1 characterized by , that the first partial image (20) and the second partial image (22) each have a substantially similar separating border area (24) that points towards each other. [3] Lighting device according to claim 1 or 2 characterized by , that the separation margin area (24) runs essentially unchanged in the longitudinal direction along a separation line (18) between the first partial image (20) and the second partial image (22). [4] Lighting device according to one of claims 1 to 3 characterized by, that the separation margin area (24) runs essentially unchanged in a margin width running transversely to a separation line (18) between the first partial image (20) and the second partial image (22). [5] Lighting device according to any one of claims 1 to 4 characterized by , that the symbol (12) within the separating border area (24) is designed to be unilluminated. [6] Lighting device according to any one of claims 1 to 5 characterized by , that the symbol (12) has a left illumination area contained only in the left sub-image (20) and a right illumination area contained only in the right sub-image (22). [7] Lighting device according to any one of claims 1 to 6 characterized by that the first light sources and / or the second light sources are arranged regularly in rows and columns. [8] Lighting device according to any one of claims 1 to 7 characterized by, that the control device is designed to position a longitudinal dividing line (18) in the symbol (12) to be projected into a left partial image (20) and a right partial image (22) at a position in the transverse direction where the symbol (12) is essentially unchanged in the longitudinal direction and within a border width in the transverse direction, wherein the dividing line (18) is in particular positioned off-center to the extension of the symbol (12) in the transverse direction. [9] Lighting device according to any one of claims 1 to 8 characterized by , that the control device is designed to project a central area of ​​the symbol (12), in which the central area is irregularly designed, exclusively from the first headlight or exclusively from the right headlight. [10] Method for projecting a symbol (12) onto a roadway (10) for a motor vehicle, wherein a left partial image (20) of the symbol (12) is projected only from a left headlight and a right partial image (22) of the symbol (12) is projected only from a right headlight spaced apart from the left headlight, such that the left partial image (20) projected by the left headlight and the right partial image (22) projected by the right headlight overlap to represent the symbol (12) in a dividing border area (24) with a predefined width in the range of the positional tolerances of an expected offset of the partial images (20, 22).

Images