Method for displaying the area behind a vehicle and display device

Abstract

The invention relates to a method for displaying the space behind a vehicle on demand, comprising the following method steps: A) Taking multiple rear-view images behind a vehicle, B) Analysis of rear-view images, identifying objects and / or situations relevant to driving safety, C) Capturing the eyes of the driver of the vehicle, D) Analysis of the eye-space images, whereby the driver's gaze direction and the gaze duration associated with the respective gaze direction are identified, E) Display of the area behind the vehicle on a display element, wherein the rear-view images are displayed on the display element when, in process step B), relevant objects and / or situations are detected for which a rated hazard potential exceeds a limit value, or when the viewing duration detected in process step D), with the driver's gaze directed towards the display element, is longer than a limit viewing duration. The invention also relates to a display device and a vehicle with a display device.

Description

[0001] The invention relates to a device for the on-demand display of the area behind a vehicle. The method can be used, for example, to simulate a rearview mirror. The method automatically analyzes the area behind the vehicle for potential hazards that could affect driving safety. Furthermore, the method determines the direction in which the driver is looking. Depending on the detected hazards in the area behind the vehicle or the driver's direction of view, a display element showing the area behind the vehicle is activated as needed. The invention also relates to a display device configured to execute the method. Finally, the invention relates to a vehicle equipped with such a display device.

[0002] Traditionally, rearview mirrors are used to display the area behind a vehicle. These mirrors reflect light and give the driver a direct view of the area behind the vehicle. As an alternative, electronic rearview mirror systems exist, which display an image captured by a camera on a screen positioned within the driver's field of vision. Thanks to high-resolution cameras and displays, electronic rearview mirror systems can already improve the image quality of the area behind the vehicle compared to traditional mirrors. However, electronic rearview mirror systems, especially those with high resolution, consume a significant amount of power, which can reduce the driving range of electric vehicles.Furthermore, both traditional rearview mirrors and displays of electronic rearview mirror systems are often positioned in the driver's field of vision in such a way that, when not in use, they obstruct the view forward from the vehicle.

[0003] DE10 2015 202 846 A1 describes a vehicle vision system with a display. The vehicle vision system serves as an electronic rearview mirror system, with the display being transparent and mounted on the windshield. The vehicle vision system continuously determines the driver's line of sight and activates the display on the windshield as soon as the driver looks at the display for a certain period of time.

[0004] German patent application DE 10 2022 118 578 A1 describes a method for a motor vehicle to adjust the visibility of an emergency vehicle. The method analyzes images of the area behind the vehicle captured by a camera to determine whether an emergency vehicle, such as an ambulance, is visible. If an emergency vehicle is detected, it is highlighted on a traditional rearview mirror using a color filter or displayed on a screen located inside the vehicle.

[0005] CN 113978366 A describes an intelligent, electronic rearview mirror system and a method for its operation. The rearview mirror system detects the driver's line of sight and displays a camera image of the area behind the vehicle on different screens, depending on the direction of sight. Furthermore, the captured camera image is analyzed by an intelligent algorithm for potentially hazardous objects, and any detected potentially hazardous objects are displayed on a central screen in the vehicle.

[0006] DE 10 2023 135 814 A1 discloses a visualization system for a motor vehicle which, in particular, can control a basic illumination on the display surface with a basic brightness level by means of a control module. Furthermore, DE 10 2023 135 814 A1 discloses an associated visualization method.

[0007] The object of the invention is to provide advantageous solutions that make the space behind a vehicle more ergonomic for the driver and improve driving safety. Furthermore, the solutions should exhibit reduced electrical energy consumption.

[0008] The problem is solved by a method having the features of claim 1, by a representation device having the features of claim 7, and by a vehicle having the features of claim 10. Advantageous embodiments with expedient further developments of the invention are specified in the dependent claims.

[0009] The method according to the invention serves to display the area behind a vehicle on demand and comprises the following method steps: A) Recording multiple rear-view images behind a vehicle using a rear-view camera, B) Analysis of the rear-view images by a control unit, whereby objects and / or situations relevant to driving safety are recognized and the objects and / or situations are assessed based on their hazard potential for driving safety, C) Capturing the eyes of the vehicle's driver using multiple interior cameras, taking multiple eye images, D) Analysis of the eye-space images by a gaze-tracking unit, whereby the driver's gaze direction and the gaze duration associated with the respective gaze direction are detected, E) Display of the area behind the vehicle on a display element, wherein the display element comprises at least one at least partially transparent display element arranged in front of a barrier layer, wherein the barrier layer is transparent in a rest state and opaque in a blocked state and can be switched from the rest state to the blocked state by an activation signal, wherein the rear-space images are displayed on the display element and the barrier layer is switched to the blocked state when, in process step B), relevant objects and / or situations are detected for which the assessed hazard potential exceeds a limit value, or when the viewing duration detected in process step D), with the driver's gaze directed towards the display element, is longer than a limit viewing duration.

[0010] A display that is activated only when it is necessary for the driver's ergonomic safety and driving safety is understood to be a display that only occurs when required for ergonomic reasons. In other cases, the display may not be activated or may be deactivated. In the method according to the invention, preferred process steps A) to E) are carried out continuously. These process steps can also be carried out simultaneously.

[0011] In the first process step (A), several rear-view images are captured by a rear-view camera. These images show the area behind the vehicle. The camera can be positioned, for example, at the rear of the vehicle or on one of its sides. It is also possible to use multiple rear-view cameras, each capturing images from different positions on the vehicle. In the second process step, the previously captured rear-view images are analyzed by a control unit. This control unit is a computer or controller. During the analysis, which is preferably performed by an intelligent algorithm running as a computer program on the control unit, objects and / or situations relevant to the vehicle's driving safety are automatically detected.Object recognition is performed on previously recorded rear-view images. Recognized objects can include, for example, other vehicles, buildings or trees, lane markings, speed limits, and traffic signs. By analyzing sequentially recorded rear-view images, situations are also identified in which the temporal and spatial behavior of the recognized objects is determined. Such identified situations allow for the prediction of the likely behavior of the recognized objects. For example, an approaching emergency vehicle can be detected. By recognizing the situation through several rear-view images recorded at different times, it is also possible to determine whether the emergency vehicle is, for example, about to overtake. The recognized objects and / or situations are evaluated based on their potential hazard to the vehicle's driving safety. This evaluation can also be referred to as classification.The assessed hazard potential is later compared with a limit value for hazard potential in process step E). Parallel to or concurrently with process steps A) and B), process step C) is carried out, in which the driver's eyes are captured by several interior cameras. For this purpose, multiple eye images are taken by different interior cameras at different times. In process step D), these eye images are then analyzed by an eye-tracking unit, which records and identifies the driver's gaze direction (i.e., the direction in which the driver is currently looking) and the corresponding gaze duration. In process step D), a data set is thus recorded for each eye image, consisting of the gaze direction (which can be represented, for example, by a vector) and the corresponding gaze duration in that direction.

[0012] In process step E), the area behind the vehicle is then displayed, preferably as needed, on a display element. The display element comprises a transparent display element, which can be configured as a display or screen. This display element serves to show the previously recorded rear-view images, thus providing a type of electronic rear-view mirror system. The display element further comprises a barrier layer, which is transparent in a resting state and opaque in a blocked state. The display element is arranged on or in front of the barrier layer.

[0013] In its resting state, the combination of the display element and the barrier layer can be completely transparent. In a blocked state, the barrier layer is opaque and therefore not transparent, preventing any light from falling onto the display element from behind. In the blocked state, this prevents interfering light influences from making the representation of the area behind the vehicle unclear or illegible on the display element. When a representation of the area behind the vehicle is required, the barrier layer is switched to the blocked state. This switching or transition is triggered by an activation signal output by the control unit. Switching the barrier layer to the blocked state occurs in two different cases: firstly, activation occurs when, according to procedural law B), objects and / or situations are detected for which the assessed hazard potential exceeds a threshold value.This means that if objects and / or situations classified as particularly dangerous are automatically detected, a highly visible display appears on the screen. In this way, the driver is automatically alerted to a hazardous situation. In a second scenario, the display switches to a locked state if the driver's gaze direction, detected in step D), is directed towards the screen and the duration of that gaze exceeds a certain threshold. This means that if the driver looks at the screen for an extended period, it is automatically activated in a highly visible mode. The driver can therefore activate the screen simply by looking at it, for example, if they want a view of the area behind the vehicle.This can occur, for example, when the driver is reversing or about to overtake. According to the invention, the blocking layer is only switched to the blocked state when an automatic analysis of the rear-view images detects a dangerous situation or when the driver actively seeks a display of the area behind the vehicle. In other cases, the blocking layer remains in its inactive and transparent state, ensuring that the entire display element is transparent and does not obstruct the driver's view forward. Furthermore, when the blocking layer is in its inactive state, electrical energy is saved for operating the display device, which, particularly in electrically powered vehicles, can be used for other tasks within the vehicle.The method according to the invention thus improves both driving safety by providing a highly ergonomic electronic rearview mirror system and the vehicle's energy efficiency, since electrical energy is only required to operate the display device when needed. In a state where the blocking layer is in its idle state, either the rearward images can be displayed on the display element, or this display can be deactivated when the blocking layer is switched to the blocking state. The method according to the invention thus provides a synergistic effect, whereby the on-demand activation of the display device saves electrical energy and improves and enhances the forward view from the vehicle compared to known electronic rearview mirror systems.An additional advantage is the automatic detection of safety-relevant objects and / or situations, which are automatically displayed to the driver. This significantly improves overall driving safety. When the blocking layer is switched to the blocked state, a highly visible display appears on the screen, unaffected by interfering light sources such as oncoming headlights, a low sun, or similar factors.

[0014] In one embodiment of the invention, the analysis in process step B) is performed by a neural network implemented in the control unit. This neural network is trained on datasets that include the assignment of objects and / or situations to a hazard potential for driving safety. In this embodiment, the neural network forms an intelligent algorithm that automatically recognizes objects and / or situations and assesses their hazard potential for driving safety. Prior to the execution of the process, the neural network was trained on datasets in which objects and / or situations are assigned to a hazard potential.Furthermore, the neural network was trained to assign geometries detected in the rear-view images to objects such as vehicles, cyclists, pedestrians, and other objects relevant to driving safety. Preferably, the training of the neural network continues during the execution of the procedure. This can be achieved, for example, by establishing a data connection with a central server, from which the control unit continuously receives further data sets for training the neural network. These continuously provided data sets can also be locally related to the vehicle's location and contain specific information about that location. Object recognition and hazard potential assessment by the neural network occur in real time. Such a neural network represents a form of artificial intelligence (AI).

[0015] In one embodiment of the invention, it is provided that in process step B), when assessing the potential hazard to driving safety posed by the detected objects and / or situations, at least one additional signal from at least one sensor arranged in or on the vehicle is used, and this signal is compared with the results of the analysis of the rear-view images. In this embodiment, at least one sensor arranged on or in the vehicle is considered for the analysis in process step B). The analysis is therefore not based solely on the recorded rear-view images but is supplemented by further input parameters. For example, such a sensor can be a radar or lidar sensor, which also detects the area behind the vehicle.In this way, at least two different sources of information are used to analyze the situation behind the vehicle, thus avoiding or reducing errors in the detection of objects and / or situations. Furthermore, it is possible, for example, to consider the signal from a steering angle sensor in the analysis, thereby incorporating the driver's own driving into the assessment of the hazard potential. This further improves the assessment of the hazard potential for the driver's own actions.

[0016] In one embodiment of the invention, it is provided that in process step E), if relevant objects and / or situations are detected in process step B) for which the assessed hazard potential is below the limit value, or if the viewing duration detected in process step D), with the driver's gaze directed towards the display element, is shorter than a limit viewing duration, the area behind the vehicle is not displayed on the display element. In this embodiment, the area behind the vehicle is not displayed unless the driver is consciously looking at the display element or the automatically assessed hazard potential of the objects and / or situations behind the vehicle is below the limit value. In this way, a significant amount of electrical energy is saved, since no display occurs at all.Furthermore, the entire display element is transparent, thus allowing the driver a clear view forward from the vehicle.

[0017] In one embodiment of the invention, process steps A) to E) are performed continuously. After process step E), if relevant objects and / or situations are detected in process step B) for which the assessed hazard potential is below the limit value, or if the viewing duration detected in process step D) is shorter than the limit viewing duration (given the driver's gaze directed at the display element), process step F) is initiated in which the blocking layer is switched to the standby state. In this embodiment, a further process step F) is initiated after the blocking layer has previously been in the blocking state. For example, the driver can actively look at the display element for an extended period, thereby switching the blocking layer to the blocking state and providing a clear display of the area behind the vehicle.If the driver subsequently loses interest in the area behind the vehicle and looks in another direction, this is automatically detected, and process step F) is initiated, in which the barrier layer is switched to a transparent standby state. In this case, it is possible for the rear view images to continue to be displayed on the display element, which then behaves at least partially transparently. Alternatively, the display on the display element can be deactivated. In this embodiment, a previously activated display is deactivated as soon as there is no longer a need for a display. In this way, electrical energy for operating the display element is saved.

[0018] In one embodiment of the invention, it is provided that in process step E), the brightness and / or contrast of the rearview images on the display element is adjusted by the control unit to the current lighting conditions, wherein the control unit reads data from at least one brightness sensor which is arranged on or in the vehicle. In this embodiment of the method, the way the rearview images are displayed on the display element is adapted to the currently prevailing lighting conditions. For this purpose, at least one brightness sensor determines the current lighting conditions. Depending on the currently prevailing lighting conditions, the brightness of the display is adjusted. For example, the brightness is reduced at night to prevent the display from being dazzling for the driver.However, if there is currently a high level of brightness, for example due to sunlight or headlights from other vehicles, the brightness and contrast of the display will be increased to ensure that all objects in the display are clearly recognizable.

[0019] The display device according to the invention serves to display the area behind a vehicle as needed and comprises: - at least one rear-view camera aimed at the area behind the vehicle, - several interior cameras aimed at the eyes of the driver of the vehicle, - at least one display element which is arranged in the field of vision of a driver of the vehicle who is driving the vehicle, wherein the display element comprises at least one at least partially transparent display element which is arranged in front of a barrier layer, wherein the barrier layer is transparent in a rest state and opaque in a blocked state and can be switched from the rest state to the blocked state by an activation signal, - at least one control unit which is connected to the rear-view camera and the display element via a data connection, - at least one eye-tracking unit which is connected via a data link to the interior cameras and the control unit, wherein the control unit is configured to perform a procedure according to one of the embodiments described above.

[0020] The display device according to the invention is at least partially integrated into a vehicle. The display device comprises at least one rear-view camera, which is directed towards the area behind the vehicle. The rear-view camera can, for example, be arranged at the rear of the vehicle. Preferably, the rear-view camera is a high-resolution camera. Furthermore, the display device comprises several interior cameras, which are directed towards the eyes of a driver operating the vehicle. Depending on the driver's head position and direction of gaze, it is possible that their eyes are not always captured by all interior cameras. However, by providing several interior cameras, it is ensured that the eyes are always captured by at least one interior camera. The interior cameras can, for example, be arranged on the headliner, the center console, or the A-pillars of the vehicle.Furthermore, at least one display element is provided, which is positioned within the driver's field of vision. The display element can, for example, be located on or in the vehicle doors. Alternatively, the display element can preferably be positioned in the upper area of ​​the windshield, where traditional analog rearview mirrors are also located. The display element has a multi-layered structure: facing the driver is a display element, which is designed as a screen or display. On the side of the display element facing away from the driver, a barrier layer is arranged, which can be switched from a transparent standby state to an opaque blocked state by an activation signal. In the blocked state, the barrier layer prevents light from falling onto the display element from the side facing away from the driver and thus interfering with the visibility of the display.The display device further comprises a control unit, which is implemented as a computer or controller. The control unit is connected to the rear-view camera and the display element via a data connection. A gaze-tracking unit is also provided, which is connected to the interior cameras and the control unit via a data connection. The gaze-tracking unit is designed to analyze the eye images captured in process step C). The gaze-tracking unit can be integrated into the control unit. The control unit is configured to perform a process according to one of the embodiments described above. The advantages, advantageous configurations, and effects mentioned above in connection with the method also apply to the display device according to the invention.

[0021] In one embodiment of the display device, the display element is configured as a display comprising a plurality of organic light-emitting diodes (OLEDs), and / or the barrier layer is configured as a polymer-dispersed liquid crystal layer, and the activation signal is generated by an electrical voltage, and / or the interior cameras are configured as infrared cameras. In this embodiment, the display element is configured as a display or screen comprising a plurality of pixels, each formed by an OLED. Such a display can also be referred to as an OLED display, which can be manufactured with high resolution and a very thin layer. Such an OLED display exhibits very high color fidelity and good contrast. Furthermore, such a display is flexible and can therefore be installed in various locations within the vehicle.Preferably, the barrier layer is arranged directly adjacent to the display. The barrier layer can be implemented as a polymer-dispersed liquid crystal layer. Such a barrier layer can also be referred to as a PTLC layer. By applying an electrical voltage, which constitutes the activation signal, such a barrier layer can be switched from a transparent standby state to an opaque blocking state. In the blocking state, only a very small electrical current is required to maintain the opaque behavior. Simultaneously, a very fast switching between the transparent standby state and the opaque blocking state is possible. Preferably, the interior cameras are implemented as infrared cameras, since infrared cameras allow for accurate detection of the driver's eyes even in low light conditions, such as at night.

[0022] In one embodiment of the display device, the display device comprises at least one further sensor, which is connected to the control unit via a data link. This sensor is selected from the group consisting of: radar sensor, lidar sensor, vehicle speed sensor, direction indicator sensor, brightness sensor, or steering angle sensor. The display device preferably also includes one or more sensors that provide signals supporting the analysis of the rear-view images by the control unit or the analysis of the eye images by the eye-tracking unit. The signals provided by the sensor can be used to confirm or verify the analysis results based on the rear-view and eye images. This further enhances detection reliability.A sensor from the group consisting of a lidar sensor, vehicle speed sensor, direction indicator sensor, or steering angle sensor can be used to provide signals to support the analysis in process step B) and provide additional information for the correct assessment of the hazard potential of objects and / or situations behind the vehicle. A sensor from the group consisting of a direction indicator sensor, light sensor, or steering angle sensor can be used to support the analysis in process step D) and provide additional information about the driver's behavior in the vehicle, including their gaze direction and associated gaze duration.

[0023] The vehicle according to the invention comprises a display device according to one of the embodiments described above. The display device is arranged, at least partially, in or on the vehicle. The advantages, advantageous configurations, and effects mentioned above in connection with the method and the display device also apply to the vehicle according to the invention.

[0024] The features and combinations of features mentioned above in the description, as well as those subsequently mentioned in the figure description and / or shown in the figures alone, can be used not only in the combinations specified, but also in other combinations or on their own, without departing from the scope of the invention. Thus, embodiments that are not explicitly shown or explained in the figures, but which can be derived and generated from the explained embodiments by separate combinations of features, are also to be considered as encompassed and disclosed by the invention.

[0025] Further advantages, features, and details of the invention will become apparent from the claims, the following description of preferred embodiments, and the drawing. The drawing shows: Fig. 1 a flowchart of an embodiment of the method according to the invention.

[0026] Fig. Figure 1 shows a flowchart of an embodiment of the method according to the invention. The illustrated embodiment of the method serves to display the area behind a vehicle on demand. In the illustrated embodiment, this area is displayed only when a need is detected, either because a driver looks at the display element or when the analysis of the rear-view images detects objects and / or situations and assesses their hazard potential as higher than a threshold. In all other cases, the area behind the vehicle is not displayed. In this way, electrical energy for operating the display element can be saved, and the ergonomics of the driver looking forward from the vehicle can be improved.

[0027] The process begins with start 1. Preferably, the process is started together with the commissioning of a vehicle, particularly when starting off. In the illustrated embodiment, the first process steps A) to E) are carried out continuously. In a first process step A), rear-view images are captured, showing the area behind the vehicle. At least one rear-view camera is used for this purpose. In the second process step B), these rear-view images are analyzed by the control unit, whereby objects and / or situations relevant to driving safety are recognized and the objects and / or situations are assessed based on their potential hazard to driving safety.The detection and analysis are performed automatically, preferably by a neural network that has been previously trained on a large number of datasets to assess the hazard potential of objects and / or situations detected in the rear-view images. This neural network is implemented in the control unit. The analyses in process step B) are performed in real time and have the advantage of automatically detecting dangerous situations behind the vehicle. In a third process step C), several interior cameras capture images of the driver's eyes. These eye images serve as the basis for the analysis in process step D), in which a gaze-tracking unit automatically detects the current gaze direction and the duration associated with that gaze direction. Knowing the gaze direction and its duration makes it possible to assess where and on which object the driver is currently looking.In the flowchart in . Fig. In step D) of procedure 1, a first query A1) is shown. This query A1) facilitates the explanation of the following step E). Query A1) checks whether the analysis in step B) detected objects and / or situations that were assessed as having a hazard potential above a threshold value. This threshold value defines a hazard potential above which the driver must pay particular attention to the area behind the vehicle. Furthermore, query A1) checks whether the analysis in step D) showed that the driver is looking at the display element, and the duration of this gaze must be longer than a threshold viewing duration. If this is the case, it is assumed that the driver is consciously looking at the display and wants to see a representation of the area behind the vehicle.This has the advantage that the driver does not need to activate the display with a further command or input, but that this is triggered automatically by looking in the right direction. If at least one of the conditions from process step B) or process step D) is met, process step E) is initiated and the area behind the vehicle is displayed on the screen. If neither of the conditions from process steps B) or D) is met, process step E) is not initiated and the area behind the vehicle is not displayed on the screen. Instead, the first process steps A) to D) are continuously repeated.

[0028] In a case where process step E) is initiated, the barrier layer of the display element is switched to an opaque blocking state by an activation signal from the control unit. The area behind the vehicle is then displayed on the element. In this way, the area behind the vehicle is now clearly visible on the display element, with the barrier layer preventing interfering light from affecting the visibility of the display. Even while the area behind the vehicle is being displayed, the first process steps A) to D) continue to be repeated continuously. This is symbolized by the arrow leading upwards from process step E) on the left side to process step A).In this way, results from the analyses in process steps B) and D) are continuously determined and made available for subsequent process steps. A second query A2) is shown after process step E). This second query A2) checks whether a condition from process steps B) or D) still exists after the blocking state of the blocking layer has been activated. If the analysis in process step B) shows that the hazard potential of detected objects and / or situations behind the vehicle is below the limit value, and simultaneously the analysis in process step D) shows that the driver is no longer looking at the display element or that any gaze directed at it has a duration below the limit value, then process step F) is initiated, in which the blocking layer is switched to the transparent resting state.After process step F), process steps A) to D) are executed continuously again until one of the necessary conditions to initiate process step E) is met in query A1) and the area behind the vehicle is again displayed on the display element. The process in the illustrated embodiment continues until it is terminated by end 2. Preferably, end 2 of the process occurs together with the deactivation or switching off of the vehicle. Fig. Figure 1 shows the two queries A1) and A2) to simplify the description of the procedure. It is also possible to perform the first query A1) within procedure step E) and the second query A2) within procedure step F). REFERENCE MARK LIST: 1 Start A) Procedure step A) B) Procedure Step B) C) Procedure step C) D) Procedure step D) E) Procedure step E) F) Procedure step F) A1) first query A2) second query 2 End

Claims

[1] Method for displaying the space behind a vehicle on demand, comprising the following process steps: A) Recording multiple rear-view images behind a vehicle using a rear-view camera, B) Analysis of the rear-view images by a control unit, whereby objects and / or situations relevant to driving safety are recognized and the objects and / or situations are assessed based on their hazard potential for driving safety, C) Capturing the eyes of the vehicle's driver using multiple interior cameras, taking multiple eye images, D) Analysis of the eye-space images by a gaze-tracking unit, whereby the driver's gaze direction and the gaze duration associated with the respective gaze direction are detected, E) Display of the area behind the vehicle on a display element, wherein the display element comprises at least one at least partially transparent display element arranged in front of a barrier layer, wherein the barrier layer is transparent in a rest state and opaque in a blocked state and can be switched from the rest state to the blocked state by an activation signal, wherein the rear-space images are displayed on the display element and the barrier layer is switched to the blocked state when, in process step B), relevant objects and / or situations are detected for which the assessed hazard potential exceeds a limit value or when, in process step D), the viewing duration detected, with the driver's gaze directed towards the display element, is longer than a limit viewing duration. [2] Method according to claim 1, characterized by, that the analysis in process step B) is carried out by a neural network which is implemented in the control unit, wherein the neural network is trained by data sets which include an assignment of objects and / or situations to a hazard potential for driving safety. [3] Method according to one of claims 1 or 2, characterized by , that in procedure step B) when assessing the hazard potential for driving safety caused by the detected objects and / or situations, at least one additional signal from at least one sensor located in or on the vehicle is used, and this signal is compared with the results of the analysis of the rear-view images. [4] Method according to any one of claims 1 to 3, characterized by, that in procedure step E) in a case where relevant objects and / or situations are detected in procedure step B) for which the assessed hazard potential is below the limit value or if the viewing duration detected in procedure step D) is shorter than a limit viewing duration when the driver's gaze is directed towards the display element, the area behind the vehicle will not be displayed on the display element. [5] Method according to any one of claims 1 to 4, characterized by, that the procedure steps A) to E) are carried out continuously and after procedure step E), if relevant objects and / or situations are detected in procedure step B) for which the assessed hazard potential is below the limit value or if the viewing duration detected in procedure step D), with the driver's gaze directed towards the display element, is shorter than the limit viewing duration, a procedure step F) is initiated in which the blocking layer is switched to the resting state. [6] Method according to any one of claims 1 to 5, characterized by , that in process step E) the brightness and / or contrast of the display the rear-view images on the display element is adjusted by the control unit to the current lighting conditions, wherein the control unit reads data from at least one brightness sensor which is arranged on or in the vehicle. [7] Display device for displaying the area behind a vehicle on demand, comprising - at least one rear-view camera aimed at the area behind the vehicle, - several interior cameras aimed at the eyes of the driver of the vehicle, - at least one display element which is arranged in the field of vision of a driver of the vehicle who is driving the vehicle, wherein the display element comprises at least one at least partially transparent display element which is arranged in front of a barrier layer, wherein the barrier layer is transparent in a rest state and opaque in a blocked state and can be switched from the rest state to the blocked state by an activation signal, - at least one control unit which is connected to the rear-view camera and the display element via a data connection, - at least one eye-tracking unit which is connected via a data link to the interior cameras and the control unit, wherein the control unit is configured to perform a method according to any one of claims 1 to 6. [8] Display device according to claim 7, characterized by that the display element is designed as a display comprising a multitude of organic light-emitting diodes and / or the barrier layer is designed as a polymer-dispersed liquid crystal layer and the activation signal is formed by an electrical voltage and / or the interior cameras are designed as infrared cameras. [9] Display device according to claim 7 or 8, characterized bythat the display device comprises at least one further sensor which is connected to the control unit via a data link, wherein the sensor is formed by a sensor from the group of the following sensors: radar sensor, lidar sensor, vehicle speed sensor, direction indicator sensor, brightness sensor or steering angle sensor. [10] Vehicle with a display device according to any one of claims 7 to 9.

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