CROSS REFERENCE TO RELATED APPLICATION

This application claims priority under 35 USC 119 to German Patent Appl. No. 10 2020 132 161.9 filed on Dec. 3, 2020, the entire disclosure of which is incorporated herein by reference.

BACKGROUND

Field of the Invention

This invention relates to a method and a system for deducing a reproduction error in high definition (HD) matrix headlights of vehicles, wherein the reproduction error is a deviation from a predefined image refresh frequency.

Related Art

High definition (abbreviated to “HD”) main headlights of a vehicle generate light images in an area in front of the vehicle. The headlights obtain video signals corresponding to the light images with a predefined image refresh frequency via a video interface. The prior art discloses a number of methods that are intended to guarantee an error-free data transmission from a video interface.

DE 10 2018 124 530 A1 proposes a device for outputting images in a manner that can be validated by an observer. More particularly, a camera provides a temporally changing camera image, and a temporally variable signature is projected into a camera optical unit so that an observer of the camera image can recognize a frozen camera image as an image transmission error.

DE 10 2016 013 502 A1 describes a method for monitoring a data transmission for transmission errors. In particular, a total image stream containing a predefined check image sequence is transmitted from a transmitter to a receiving device. An evaluation unit at the receiver end, checks an instantaneous state of the check sequence for a deviation from a predefined target value.

DE 10 2016 103 037 A1 relates to a method for checking a functionality of a camera monitor system for a motor vehicle. The method includes storing additional information together with input image data generated by a camera in an input image file. A test device of the camera monitor system ascertains the functionality of the system on the basis of the additional information.

Currently available HD matrix headlight systems cannot detect a frozen video signal. The term “frozen” is used by a person skilled in the art to denote a video signal that is not updated with the predefined image refresh frequency. The scheduled updating of the video signal may fail to occur if a video processing control device does not carry out image updating, e.g., due to an internal software error. Moreover, a reduction of the image refresh frequency can occur due to an excessive number of computation operations, and this cannot be recognized at the present time. Both error possibilities must be avoided to ensure traffic safety of the headlight system during operation of a vehicle, and the system must not cause other road users to be dazzled.

An object of the invention is to provide a method for monitoring HD headlights in which a video signal of the video interface is checked in regard to its image refresh frequency. The checking is to be effected between the HD headlight system and the video interface. A system also is provided to implement the method.

SUMMARY

A method for monitoring an image refresh frequency of high definition (HD) headlights is provided. At least one HD matrix headlight or HD headlight designed for a vehicle has a control unit and a light source. The light source has a display with a multiplicity of light point sources, and the control unit causes the light source to generate light images in continued temporal succession for a predefined time duration. Each light image is updated by a respective next light image at a predefined image refresh frequency corresponding to the inverse of the predefined time duration. With respect to the predefined image refresh frequency, a video signal composed of image information items and signal information items is provided to the control unit of the at least one HD headlight by a video interface. A temporally changing information item is impressed on the signal information items of the video signal by the video interface. The control unit of the at least one HD headlight checks the signal information items of the video signal with respect to the temporally changing information item and assesses correspondence with the temporal succession available to the at least one HD headlight. The control unit then initiates a substitute reaction of the at least one HD headlight in the event of erroneous correspondence.

The signal information items of the video signal also are referred to as META-data by those skilled in the art. The image information items contain image data formed, e.g., from image information units, so-called pixels, strung together in lines. These signal information items can be attached to the image data in additional lines. According to the invention, the temporally changing information item is introduced in the additional lines, e.g., by virtue of the fact that for this purpose at a location in the additional lines at least one information unit corresponding to an individual pixel of the image data is agreed between the video interface and the HD headlight.

The predetermined image refresh frequency can be, e.g., 60 fps, where “fps” is the abbreviation of “frames per second”. This corresponds to a predefined time duration of 16 ms, following which the at least one HD headlight expects an updated video signal from the video interface. An absence of the temporal change in the information unit agreed for this purpose in the signal information items of the video signal enables the control unit of the HD headlight to recognize that a currently reproduced light image, e.g., cannot be adapted to events in the meantime, e.g., possible changes in a current traffic situation. According to the invention, the control unit thus initiates a substitute reaction for the sake of safety.

In one embodiment of the method, the temporally changing information item is represented by a single byte. In this case, the single byte assumes a value that changes between 0x0 and 0x255 with respect to each time step. In order to be able to ascertain an interruption in a direct succession of video signals provided with the predefined image frequency, e.g., a change from 0x0 (corresponding to “black”) to 0x255 (corresponding to “white”) and again to 0x0, the change alternating with the predefined image frequency, is sufficient.

In one embodiment of the method, the single byte is incremented bit by bit with respect to each time step. Thus, the HD headlight can advantageously recognize deviations from the temporal succession in a simple manner if a single incremental counter value running with the image refresh frequency in the control unit leads to a deviation from the value of the single byte being incremented bit by bit in the signal information item.

In a further embodiment, the erroneous correspondence is formed by a reduced image refresh frequency of the video signal provided by the video interface vis-à-vis the predefined image refresh frequency. The control unit deduces a value of the reduced image refresh frequency from the temporally changing information item. For this purpose, the control unit can use a temporal reference, such as the incremental counter running in the control unit or a time signal provided via a CAN (controller area network) bus, in order, through comparison with the temporally changing information item, to deduce a deviation factor between the video signals provided by the video interface with reduced image frequency and the predefined image refresh frequency.

In yet another embodiment, the substitute reaction of the at least one HD headlight is formed by a renewed reproduction of the respective light image. This can be done, e.g., if the respective light image, within standard specifications, does not constitute a hazard for possible oncoming traffic.

In another refined embodiment, the substitute reaction of the at least one HD headlight is formed by a reproduction of a light image corresponding to a low-beam light.

The invention also relates to a system for monitoring an image refresh frequency of HD headlights. The system comprises at least one HD headlight designed for a vehicle and a video interface. The at least one HD headlight comprises a control unit and, as a light source, has a display having a multiplicity of light point sources. The at least one HD headlight is designed to generate a respective light image in continued temporal succession for a predefined time duration by means of the control unit, and to update the respective light image, with respect to a predefined image refresh frequency corresponding to the inverse of the predefined time duration, by a respective next light image. The video interface is designed, with respect to the predefined image refresh frequency, to provide a video signal composed of image information items and signal information items to the control unit of the at least one HD headlight and to impress a temporally changing information item on the signal information items of the video signal. The control unit of the at least one HD headlight is designed to check the signal information items of the video signal, in regard to the temporally changing information item, for correspondence with the temporal succession available to the at least one HD headlight and to initiate a substitute reaction of the at least one HD headlight in the event of erroneous correspondence.

In one configuration of the system, the temporally changing information item is represented by a single byte. The single byte assumes a value that changes between 0 and 255 with respect to each time step.

In a refined configuration of the system, the value of the single byte is increased bit by bit with respect to each time step.

In a further configuration of the system, the erroneous correspondence is formed by a reduced image refresh frequency of the video signal provided by the video interface vis-à-vis the predefined image refresh frequency. The control unit additionally may be designed to deduce a value of the reduced image refresh frequency from the temporally changing information item.

In yet another configuration of the system, the substitute reaction of the at least one HD headlight is formed by a renewed reproduction of the respective light image.

In a further configuration of the system, the substitute reaction of the at least one HD headlight is formed by a reproduction of a light image corresponding to a low-beam light.

Further advantages and configurations of the invention are evident from the description and the accompanying drawing.

It goes without saying that the features mentioned above and those yet to be explained below can be used not only in the combination respectively indicated, but also in other combinations or by themselves, without departing from the scope of the present invention.

