Reflection Display System and Method for Operating a Reflection Display System With Masking Detection

Abstract

A method for operating a reflection display system for displaying a display image for a vehicle occupant of a motor vehicle by reflection of the display image on a reflection surface, in particular on a front windscreen, includes outputting a sequence of measurement display images with different patterns with different lighting intensities in some regions; detecting a brightness signal by an ambient brightness sensor while each measurement display image of the sequence is being displayed in order to obtain a brightness profile of the brightness signals; evaluating the profile of the brightness signals with respect to a predefined reference brightness profile which specifies brightness signals when the display surface is uncovered, for the sequence of measurement display images with constant ambient brightness; and signaling the presence of a foreign object on the display surface depending on the result of the evaluation.

Claims

1.-12. (canceled)

13. A method for operating a reflection display system for displaying a display image for a vehicle occupant of a motor vehicle by reflection of the display image on a front windshield, wherein a display unit is configured to output the display image via a display surface of the display unit, the display unit being arranged on an upper side of a dashboard such that a reflection of the display image via the front windshield is perceptible in an eye region of a vehicle occupant, the method comprising: outputting a sequence of measurement display images with different patterns with different luminous intensities from region to region; detecting a respective brightness signal by an ambient brightness sensor while a respective measurement display image of the sequence is being displayed in order to obtain a brightness profile of the brightness signals; evaluating the brightness profile of the brightness signals with respect to a predefined reference brightness profile which specifies brightness signals when the display surface is unmasked for the sequence of measurement display images when there is constant ambient brightness; and depending on a result of the evaluating, signaling a presence of a foreign object on the display surface.

14. The method according to claim 13, wherein each of the measurement display images has a pattern which has a first region of high luminous intensity in front of a remaining region of low luminous intensity.

15. The method according to claim 14, wherein the first regions of high luminous intensity of all the measurement display images cover an entire display region.

16. The method according to claim 14, wherein at least one pattern of the measurement display images comprises: one or more strip-like regions of high luminous intensity with otherwise a darkly displayed background; checkerboard regions of high luminous intensity with otherwise a darkly displayed background; or regions of different luminous intensity with otherwise a darkly displayed background.

17. The method according to claim 13, wherein the method is performed upon determining that an enabling condition is satisfied, wherein the enabling condition comprises at least one of: an ambient brightness lies not above a first predefined threshold value, or a gradient of a variation of the ambient brightness lies below a second predetermined threshold value.

18. The method according to claim 13, wherein the sequence of measurement display images is run through within a time period of less than 1 s.

19. The method according to claim 18, wherein the time period is less than 100 ms.

20. The method according to claim 13, wherein the sequence of measurement display images is provided within a predefined video sequence, the brightness profile being recorded at corresponding output times of the measurement display images when outputting the video sequence.

21. The method according to claim 13, wherein evaluating the profile of the brightness signals is carried out with respect to a predefined reference brightness profile, by the brightness signals sensed by the ambient brightness sensor being evaluated differentially, by respective differences arising between two measurement display images when there is a known sequence of measurement display images being compared with a corresponding predefined difference of the brightnesses according to the reference brightness profile, and by the presence of the foreign object being detected when a comparison shows that there is a deviation.

22. A reflection display system for displaying a display image for a vehicle occupant of a motor vehicle by reflection of the display image on a front windshield, the reflection display system comprising: a display unit, which is configured to output the display image via a display surface of the display unit, the display unit being arranged on an upper side of a dashboard such that a reflection of the display image via the front windshield is perceptible in an eye region of a vehicle occupant; an ambient brightness sensor, which is configured to detect an ambient brightness and to provide a corresponding brightness signal; and a control unit, which is configured to: output a sequence of measurement display images with different patterns with different luminous intensities from region to region; detect a respective brightness signal by the ambient brightness sensor while a respective measurement display image of the sequence is being displayed in order to obtain a brightness profile of the brightness signals; evaluate the brightness profile of the brightness signals with respect to a predefined reference brightness profile which specifies brightness signals when the display surface is unmasked for the sequence of measurement display images when there is constant ambient brightness; and depending on a result of an evaluation, signal a presence of a foreign object on the display surface.

23. The reflection display system according to claim 22, wherein the ambient brightness sensor is arranged such that an output of a region of high luminous intensity by the display unit influences a measurement of the brightness signal.

24. The reflection display system according to claim 22, wherein the display unit is arranged in a depression such that the display image that is displayed on the display surface of the display unit is not directly perceptible in the eye region.

25. The reflection display system according to claim 24, wherein the ambient brightness sensor is arranged in the depression.

26. The reflection display system according to claim 25, wherein the ambient brightness sensor is arranged to a side of the display unit.

27. A motor vehicle comprising: the dashboard between the front windshield of the motor vehicle and a steering column; and the reflection display system according to claim 22.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0050] FIG. 1 shows a schematic cross-sectional representation of a reflection display system in a motor vehicle.

[0051] FIG. 2 shows a flow diagram to represent a sequence of a method for detecting and signaling a foreign object on the display surface.

[0052] FIGS. 3a and 3b show a schematic representation of a sequence of displayed measurement display images along with a correspondingly sensed brightness signal for the case where a masking foreign object is not present and the case where there is a foreign object masking the display.

DETAILED DESCRIPTION OF THE DRAWINGS

[0053] FIG. 1 shows a schematic cross-sectional representation through a motor vehicle with a reflection display system 1. The reflection display system is arranged on an upper side of a dashboard 4 and has a display unit 2, which comprises a display surface 3 for displaying a display image. The display unit 2 is arranged on the upper side of the dashboard 4 under a front windshield 5.

[0054] The display surface 3 is aligned with respect to the front windshield 5 such that a display image displayed on the display surface of the display unit 2 is reflected on a lower region of the inner side of the front windshield 5 and can be perceived by a vehicle occupant in an eye region B. This allows the alignment of the display unit 2 or its display surface to be preferably substantially parallel to the longitudinal and transverse axes of the vehicle or to deviate from them by an angle of no more than 0-20.

[0055] The display unit 2 may be fitted in a depression 6 of the dashboard, so that a direct view of the display surface 3 of the display unit 2 by the vehicle occupant is not possible and dazzling of the vehicle occupants by the glare of direct light from the display surface 3 into the eye region B is avoided. Furthermore, the display surface 3 of the display unit 2 is aligned such that a displayed display image is reflected on the inner side of the front windshield 5 and can be perceived by a vehicle occupant in an eye region B as a reflection image on the front windshield 5.

[0056] The display unit 2 is preferably designed as a micro-LED display unit in order to provide a bright display image, so that the reflection produced can be perceived via the corresponding region of the front windshield 5 even when there is high ambient brightness.

[0057] Since the display unit 2 is arranged in the depression 6 on the upper side of the dashboard 4, a foreign object 7 can also get into this depression 6 and consequently come to lie on the display surface 3 of the display unit 2. A display image displayed on the display unit 2 can then not be perceived, or only partially, by a vehicle occupant as a reflection image.

[0058] The display unit 2 is designed as a micro-LED display unit in order to provide a bright display image, so that the reflection produced can be perceived via the corresponding region of the front windshield 5 even when there is high ambient brightness.

[0059] An ambient brightness sensor 12 which is designed for measuring the ambient brightness may be arranged in the depression 6. With the aid of a control unit 10, the operation of the reflection display system is controlled. In particular, the control unit 10 can measure the ambient brightness with the aid of the ambient brightness sensor 12 and set the display image emitted by the display unit 2 with regard to the luminous intensity. The aim here is to set the luminous intensity of the display image such that the display image can be perceived by a user even when there is high ambient brightness.

[0060] To detect whether or not a foreign object 7 is resting on the display surface 3, the control unit 10 may also be designed to perform a method such as is described in conjunction with FIGS. 2, 3a and 3b.

[0061] FIG. 2 shows on the basis of the flow diagram the sequence of the method for detecting and signaling a foreign object 7 on the display surface 3, FIGS. 3a and 3b schematically show a sequence of displayed measurement display images along with a correspondingly sensed brightness signal for the case where no foreign object 7 is resting on the display surface 3 of the display unit 2 and the case where a foreign object 7 is partially masking the display surface 3.

[0062] In step S1, it is first checked whether an enabling condition for performing masking detection is satisfied. The enabling condition checks whether the ambient brightness condition(s) is/are suitable for performing a measurement of masking of the display surface 3 by a foreign object 7.

[0063] An enabling condition may concern a measure of the ambient brightness. For this purpose, the ambient brightness may be measured, preferably with the display unit 2 deactivated for a short time. If the ambient brightness lies not above a predefined threshold value, it can be established that the enabling condition is not satisfied, since differences of the brightness signal when there is high ambient brightness can only be evaluated inaccurately or cannot be evaluated.

[0064] A further enabling condition, in which it is checked whether the ambient brightness fluctuates greatly, i.e. a variation of the ambient brightness has a gradient that exceeds a predefined threshold value, may alternatively or additionally also be checked. The enabling condition is satisfied if the gradient lies below a predefined threshold value.

[0065] If the enabling condition is satisfied (alternative: yes), the method is continued with step S2, otherwise a return is made to step S1.

[0066] In step S2, a first or a further measurement display image is displayed on the display unit 2. The measurement display image may provide a pattern in which a region of high luminous intensity is output, in particular with white pixels of high intensity, and the remaining regions are output with low luminous intensity, in particular with black pixels of low or not high luminous intensity. For example, the measurement display image may output as a region of high luminous intensity a strip on the otherwise darkly displayed region, as shown for example in FIG. 3a.

[0067] The output measurement display image leads to a brightness signal of the ambient brightness sensor 12, which in step S3 is measured at the same time as the display of the respective measurement display image. Along with the ambient brightness, the brightness signal is also influenced by the brightness of the measurement display image. Generally, the brightness sensed depends on the region of high luminous intensity. It is essential that the brightness signal is sensed at the point in time of the display of the measurement display image.

[0068] In step S3, the measured ambient brightness is also buffer-stored in a profile.

[0069] In step S4, it is checked whether a further measurement display image for the output of a sequence of measurement display images is provided. This further measurement display image may be output at a time close to the previous measurement display image. Alternatively, the further measurement display image may be part of a displayed video sequence.

[0070] If a further measurement display image is to be output (alternative: yes), a return is made to step S2 and the further measurement display image is output. Otherwise (alternative: no), the method is continued with step S5.

[0071] In step S5, the recorded profile of brightness signals, which specifies the strength/intensity of the brightness sensed by the ambient brightness sensor 12 during each displayed measurement image, is compared with a reference brightness profile. The reference brightness profile specifies successive brightness signals for the sequence of measurement display images when there is an unmasked display surface 3 of the display unit 2.

[0072] In order to make the measurement independent of the ambient brightness, only the differences between the brightness signals that have been recorded during the output of the individual measurement display images are compared with the corresponding differences of the brightness signals of the reference brightness profile. Preferably, for this purpose the brightness signals of three or more measurement display images are used.

[0073] The procedure is illustrated in FIGS. 3a and 3b. The cases of an unmasked display surface 3 and a masked display surface 3 are shown. The procedure involves outputting a sequence of measurement display images, which in each case have a pattern of a strip-like region with high luminous intensity alongside the remaining region of the display surface with low luminous intensity and represent the resultant brightness signal M for the case where a foreign object 7 is not present (FIG. 3a) and the case where there is a foreign object 7 (FIG. 3b) masking the display. It can be seen that, when a foreign object 7 is lying in a region of the display surface 3 on which the measurement display image outputs a high luminous intensity, a reduced magnitude of the brightness signal with respect to the reference signal is obtained. Forming the difference between the measured brightness signals allows this deviation to be reliably detected even when there are different ambient brightnesses.

[0074] In order to reduce the dependence on fluctuations of the ambient brightness, the sequence of the measurement images may be executed within a short time period, in particular within a time period of less than 1 s, in particular less than 100 ms.

[0075] In step S6, it is checked whether the differences between the brightness signals, i.e. the intensities of the brightness signals, indicate a deviation of the differences between the intensities with respect to the measurement display images with respect to the reference profile (without the presence of a foreign object). A deviation is obtained when there is a deviation of more than a threshold amount, in order to make allowance for measurement tolerances. If this is the case (alternative: yes), masking of the display surface, i.e. the presence of a foreign object 7 on the display surface 3, is detected and the method is continued with step S7, otherwise (alternative: no), the method is continued with step S1.

[0076] In step S7, the presence of a foreign object 7 on the display surface 3 is signaled. The signaling may take place with the aid of an optical or acoustic signal or in some other way that draws the attention of the vehicle occupants, in particular a driver, to the fact that the display is at least partially masked.

[0077] The measurements may be performed a number of times to increase the robustness, so that signaling of masking only takes place if the presence of a foreign object has been detected in a number of successive measuring operations.

[0078] Identifying that measurement display image in which a deviation from the reference profile has been detected allows the location of the masking to be likewise detected, since the masking must be over a region of high luminous intensity.

[0079] The measurement display images may have different patterns, which have different luminous intensities from region to region. Since different pixels act in different ways on the brightness signal sensed by the ambient brightness sensor 12, different patterns of the measurement display images bring about different brightness signals. The respective patterns of the measurement display images may comprise: [0080] one or more strip-like regions of high luminous intensity with otherwise a darkly displayed background; [0081] checkerboard regions of high luminous intensity with otherwise a darkly displayed background; or [0082] regions of different luminous intensity, in particular with otherwise a darkly displayed background.

[0083] The measurement display images of the sequence of measurement display images are preferably chosen such that each region of the display image over all the measurement display images of the sequence is provided at least once as a region of high luminous intensity. In this way, resting of a foreign object 7 on the display surface 3 can be detected at every location of the display surface 3, since a significantly lower brightness signal is measured when a measurement display image is displayed with a region of high luminous intensity that is covered by a foreign object 7.

LIST OF REFERENCE SIGNS

1 Reflection display system
2 Display unit
3 Display surface

4 Dashboard

5 Front windshield

6 Depression

7 Foreign object
10 Control unit
12 Ambient brightness sensor