DE102021213836A1 - Method, computer program and device for controlling an imaging unit of a display device, and display device - Google Patents

Abstract

The present invention relates to a method, a computer program with instructions and a device for controlling an imaging unit of a display device. The invention also relates to a display device for use with such a method or such a device. In a first step, a viewer is detected (S1). An eye position of the viewer with respect to an eyebox is then determined (S2). An illumination characteristic of an illumination unit of the imaging unit is then adapted (S3) in such a way that a light cone emerging from the imaging unit into the eyebox is restricted to an area around the eye position.

Description

The present invention relates to a method, a computer program with instructions and a device for controlling an imaging unit of a display device. The invention also relates to a display device for use with such a method or such a device.

Such display devices can be used, for example, for a head-up display for a means of transportation. A head-up display, also referred to as a HUD, is understood to mean a display system in which the viewer can maintain his line of sight, since the content to be displayed is displayed in his field of vision. While such systems were originally used mainly in the aviation sector due to their complexity and costs, they are now also being installed in large series in the automotive sector.

Head-up displays generally include an imaging unit or PGU (Picture Generating Unit), an optics unit, and a mirror unit. The imaging unit generates the image and uses at least one display element for this purpose. The optics unit directs the image to the mirror unit. The mirror unit is a partially reflective, translucent disc. The viewer thus sees the content displayed by the imaging unit as a virtual image and at the same time the real world behind the pane. In the automotive sector, the windshield is often used as a mirror unit, and its curved shape must be taken into account in the display. Due to the interaction of the optics unit and the mirror unit, the virtual image is an enlarged representation of the image generated by the imaging unit. The imaging unit and the optics unit are generally separated from the environment by a housing with a transparent cover. A liquid crystal display (LCD: Liquid Crystal Display) with a lighting unit for the imaging unit is currently usually used for head-up displays.

The viewer can only look at the virtual image from the position of the so-called eyebox. An area is referred to as an eyebox, the height and width of which corresponds to a theoretical viewing window. As long as one eye of the viewer is within the eyebox, all elements of the virtual image are visible to the eye. If, on the other hand, the eye is outside of the eyebox, the virtual image is only partially or not at all visible to the viewer. The larger the eyebox, the less restricted the viewer is when choosing his seating position. Due to the design, the size of the eyebox is limited by the limitations of the light path in the device and in the installation slot. Under the structural conditions, the eyebox is usually designed so that it can be tracked to adapt to viewers in different seating positions. Adjusting one of the mirrors in the head-up display is usually used to adjust the position of the eyebox.

In some cases, e.g. for augmented reality applications or for comfort reasons, a large and static eyebox is used from which the viewer can see the virtual image. The luminous flux required to display the virtual image increases with the expansion of the static eyebox, and with it the power consumption of the lighting unit and the heat generated in the head-up display. As a result, the temperature range for operating the head-up display is severely restricted. In addition, the imaging unit can be temporarily or permanently impaired or even destroyed in the event of additional solar radiation in the head-up display.

Against this background describes DE 10 2015 215 180 A1 a method for adjusting the brightness of a display of a head-up display in a motor vehicle. The method involves determining where the viewer's gaze is directed on the display of the head-up display. Depending on this, a reduced brightness is set in each case in areas of the display where the viewer's gaze is not directed. No reduced brightness is set on the display where the viewer's gaze is directed.

DE 10 2013 001 380 A1 describes a method for operating a display device of a motor vehicle, in which a gaze detection device is used to detect whether a user's gaze is directed at an area assigned to the display device. If it is detected that the user's gaze has been averted from the area assigned to the display device, the brightness of the display device is reduced from a first brightness value to a second brightness value by means of a control device.

It is an object of the present invention to provide alternative solutions for controlling an imaging unit of a display device.

This object is achieved by a method having the features of claim 1, by a computer program with instructions having the features of claim 7, by a device with the Features of claim 8 and solved by a display device having the features of claim 9. Preferred developments of the invention are the subject matter of the dependent claims.

• - Bestimmen einer Augenposition eines Betrachters in Bezug auf eine Eyebox; und
• - Anpassen einer Beleuchtungscharakteristik einer Beleuchtungseinheit der bildgebenden Einheit derart, dass ein von der bildgebenden Einheit in die Eyebox austretender Lichtkegel auf einen Bereich um die Augenposition eingeschränkt ist.

According to a first aspect of the invention, a method for controlling an imaging unit of a display device comprises the steps:

• - determining an eye position of a viewer with respect to an eyebox; and
• - Adaptation of an illumination characteristic of an illumination unit of the imaging unit in such a way that a light cone exiting from the imaging unit into the eyebox is restricted to an area around the eye position.

• - Bestimmen einer Augenposition eines Betrachters in Bezug auf eine Eyebox; und
• - Anpassen einer Beleuchtungscharakteristik einer Beleuchtungseinheit der bildgebenden Einheit derart, dass ein von der bildgebenden Einheit in die Eyebox austretender Lichtkegel auf einen Bereich um die Augenposition eingeschränkt ist.

According to a further aspect of the invention, a computer program comprises instructions which, when executed by a computer, cause the computer to carry out the following steps for controlling an imaging unit of a display device:

• - determining an eye position of a viewer with respect to an eyebox; and
• - Adaptation of an illumination characteristic of an illumination unit of the imaging unit in such a way that a light cone exiting from the imaging unit into the eyebox is restricted to an area around the eye position.

The term computer is to be understood broadly. In particular, it also includes control units, embedded systems and other processor-based data processing devices.

The computer program can be provided for electronic retrieval, for example, or it can be stored on a computer-readable storage medium.

• - ein Auswertemodul zum Bestimmen einer Augenposition eines Betrachters in Bezug auf eine Eyebox; und
• - ein Steuermodul zum Anpassen einer Beleuchtungscharakteristik einer Beleuchtungseinheit der bildgebenden Einheit derart, dass ein von der bildgebenden Einheit in die Eyebox austretender Lichtkegel auf einen Bereich um die Augenposition eingeschränkt ist.

According to a further aspect of the invention, a device for controlling an imaging unit of a display device has:

• - an evaluation module for determining an eye position of a viewer in relation to an eyebox; and
• - a control module for adapting an illumination characteristic of an illumination unit of the imaging unit in such a way that a light cone exiting from the imaging unit into the eyebox is restricted to an area around the eye position.

According to a further aspect of the invention, a display device has an imaging unit, wherein an illumination characteristic of an illumination unit of the imaging unit can be adjusted in such a way that a light cone exiting from the imaging unit into an eyebox is restricted to an area around an eye position of a viewer.

In the solution according to the invention, a variable lighting characteristic of a lighting unit of the imaging unit ensures that light is provided only in the relevant part of the eyebox, in which the viewer's eyes are located. The rest of the eyebox remains dark. In this way, the brightness of the display is not reduced to the viewer, i.e. the entire display area continues to appear illuminated to the viewer. However, the display appears dark to another observer whose eyes are outside the cone of light. The solution according to the invention increases the efficiency of the display device and thus reduces the power consumption and heat generation. This ensures that the working temperature of the imaging unit is reduced and sufficient robustness against solar radiation is ensured. A smaller illuminated area of the eyebox also requires fewer light sources in the lighting unit. This reduces the number of parts required, such as lenses, power supply lines or controllers, and thus the costs.

According to one aspect of the invention, the adjustment of the lighting characteristic includes an adjustment of a direction of the light cone. Such an adjustment of the direction of the light cone, i.e. a change in the angular distribution of the light from the lighting unit, can be implemented without great effort. For example, the direction of the cone of light can be set such that the axis of the cone intersects a connecting line between the viewer's eyes essentially in the middle.

According to one aspect of the invention, the adjustment of the direction of the light cone includes an activation of selected light sources of the imaging unit. A simple way of adjusting the direction of the light cone is to switch individual light sources or groups of light sources with different radiation characteristics on or off in a targeted manner. The different radiation characteristics can be realized, for example, by the light sources being positioned differently in relation to an optical plate which, for example, forms a combination of a lens and a scattering element.

According to one aspect of the invention, the adjustment of the direction of the light cone comprises a mechanical adjustment of an angle-changing element on an illumination side of the imaging unit. The angle-changing element can be, for example, a mirror or an optical disk. A controllable actuating element, for example a linear motor, is provided for the adjustment. By tilting a mirror, the direction of the light reflected by the mirror can be controlled in a targeted manner. Likewise, the direction of the light transmitted through the optical plate can be adjusted by displacing an optical plate, for example a combination of a lens and a diffusing element, relative to a light source. In both cases, only inexpensive mechanical adjustment options are required.

According to one aspect of the invention, content displayed by a display element of the imaging unit is tracked according to an illuminated area of the display element. In this way, with a corresponding distance between the display element and the element that changes the angle, a displacement of the eyebox can be implemented.

According to one aspect of the invention, the viewer is captured with a camera to determine the eye position. The eye position can be easily determined by evaluating images from a camera. In addition, cameras are already available in many application environments in which a display device according to the invention can be used. For example, current motor vehicles often have a camera for monitoring the interior or the driver, so that no additional sensors are required to determine the eye position.

A display device according to the invention is preferably used in a head-up display for a means of transportation, e.g. a head-up display for a motor vehicle.

Further features of the present invention will become apparent from the following description and the appended claims in conjunction with the figures.

character list

• 1 shows schematically a head-up display according to the prior art for a motor vehicle;
• 2 shows schematically a head-up display with a display device according to the invention;
• 3 shows an enlarged view of a first embodiment of an imaging unit of a display device according to the invention;
• 4 shows an enlarged view of a second embodiment of an imaging unit of a display device according to the invention;
• 5 shows an enlarged view of a third embodiment of an imaging unit of a display device according to the invention;
• 6 shows schematically a means of locomotion with a head-up display that uses a display device according to the invention;
• 7 shows schematically a method for controlling an imaging unit of a display device;
• 8th shows schematically a first embodiment of a device for controlling an imaging unit of a display device; and
• 9 12 schematically shows a second embodiment of a device for controlling an imaging unit of a display device.

character description

For a better understanding of the principles of the present invention, embodiments of the invention are explained in more detail below with reference to the figures. The same reference symbols are used in the figures for the same or equivalent elements and are not necessarily described again for each figure. It goes without saying that the invention is not limited to the illustrated embodiments and that the features described can also be combined or modified without going beyond the protective scope of the invention as defined in the appended claims.

1 shows a schematic diagram of a head-up display according to the prior art for a motor vehicle. The head-up display has a display device 1 with an imaging unit 10 and an optical unit 13 . A beam of rays SB1 emanates from a display element 11 and is reflected by a folding mirror 21 onto a curved mirror 22 which reflects it in the direction of a mirror unit 2 . The mirror unit 2 is shown here as a windshield 20 of the motor vehicle. From there, the bundle of rays SB2 arrives in the direction of an eye of an observer 3.

The viewer 3 sees a virtual image VB, which is outside the motor vehicle above the hood or even in front of the motor vehicle located. The virtual image VB is an enlarged representation of the image displayed by the display element 11 due to the interaction of the optics unit 13 and the mirror unit 2 . A speed limit, the current vehicle speed and navigation instructions are shown here symbolically. As long as the eye of the viewer 3 is within an eye box 4 indicated by a rectangle, all elements of the virtual image VB are visible to the viewer 3 . If the eye of the viewer 3 is outside of the eyebox 4, then the virtual image VB is only partially visible to the viewer 3 or not at all. The larger the Eyebox 4 is, the less restricted the viewer is when choosing his seating position.

The curvature of the curved mirror 22 matches the curvature of the windshield 20 and ensures that the image distortion is stable across the entire eyebox 4. The folding mirror 21 serves to ensure that the path covered by the bundle of rays SB1 between the display element 11 and the curved mirror 22 is long, and at the same time the optics unit 13 is still compact. The imaging unit 10 and the optics unit 13 are separated from the environment by a housing 14 with a transparent cover 23 . The optical elements of the optical unit 13 are thus protected, for example, against dust located in the interior of the vehicle. An optical film or polarizer 24 is also located on the cover 23. The display element 11 is typically polarized and the mirror unit 2 acts like an analyzer. The purpose of the polarizer 24 is therefore to influence the polarization in order to achieve uniform visibility of the useful light. A glare shield 25 serves to surely absorb the light reflected through the boundary surface of the cover 23 so as not to cause glare to the viewer. In addition to the sunlight SL, the light from another interfering light source 5 can also reach the display element 11 . In combination with a polarization filter, the polarizer 24 can also be used to reduce incident sunlight SL.

2 shows schematically a head-up display with a display device 1 according to the invention. The head-up display largely corresponds to the head-up display 1 However, in this case, an illumination characteristic of an illumination unit 12 of the imaging unit 10 can be adjusted in such a way that a light cone emerging from the imaging unit 10 into the eyebox 4 is restricted to an area around the eye position. For this purpose, the imaging unit 10 receives corresponding control commands SB from a device 50 for controlling the imaging unit 10.

3 shows an enlarged view of a first embodiment of an imaging unit 10 of a display device according to the invention. The imaging unit 10 has a display element 11 . In this example, the display element 11 is a liquid crystal display. The display element 11 is illuminated by a lighting unit 12 . An angle-changing element 17 is arranged between the lighting unit 12 and the display element 11 . The angle changing element 17 in this embodiment is an optical plate 170, eg a combination of a lens and a diffusing element. The optical plate 170 can be moved by means of an actuating element 18 . The actuating element 18 can be a linear motor, for example. By moving the optical plate 170, the direction of the light transmitted through the optical plate 170 can be adjusted, whereby the direction of a light cone 15 emerging from the imaging unit 10 can be adjusted such that the light cone emerging into the eyebox is focused on an area around the eye position is restricted. The change in direction of the light cone 15 is in 3 as well as in 4 and 5 exaggerated for clarity.

In fact, the change in angle required is very small, so that the center of the light cone 15 is only shifted insignificantly given the generally very small distance between the optical plate 170 and the display element 11 .

4 shows an enlarged view of a second embodiment of an imaging unit 10 of a display device according to the invention. In this case, too, the imaging unit 10 has a display element 11 and a lighting unit 12 . However, in this embodiment, the light emanating from the lighting unit 12 is reflected in the direction of the display element 11 by means of an angle-changing element 17 . The angle-changing element 17 is a rotatably mounted mirror 171. An adjusting element 18, for example a linear motor, makes it possible, by rotating the mirror 171, to set the direction of the light reflected by the mirror 171 and thus of the exiting light cone 15 in such a way that that the cone of light exiting the eyebox is restricted to an area around the eye position.

5 12 shows an enlarged view of a third embodiment of an imaging unit 10 of a display device according to the invention. In this embodiment too, the imaging unit 10 has a display element 11 and a lighting unit 12 . In this case, however, the lighting unit 12 comprises a plurality of light sources 16, which can be controlled individually or in groups. The light emitted by the light sources 16 impinges on an optical plate 170, eg a combination of a lens and a diffusing element. The direction of the light transmitted through the optical plate 170 can be adjusted by a targeted control of the light sources 16 . In this way, the direction of a light cone 15 emerging from the imaging unit 10 can in turn be adjusted in such a way that the light cone emerging into the eyebox is restricted to an area around the eye position.

6 shows schematically a means of transportation 40, in which a solution according to the invention is implemented. In this example, the means of transportation 40 is a motor vehicle. The motor vehicle has a display device 1 according to the invention, which in this case is part of a head-up display. An imaging unit of the display device 1 is controlled by a device 50 . A sensor system 41 can be used, for example, to record data relating to the vehicle environment. The sensor system 41 can in particular include sensors for detecting the surroundings, for example ultrasonic sensors, laser scanners, radar sensors, lidar sensors or cameras. The information recorded by the sensors 41 can be used to generate content to be displayed for the head-up display. The driver can be recorded with a camera 42 for monitoring the interior. From the images captured by camera 42, an eye position of the driver relative to the eyebox of the head-up display can be determined. In this example, further components of the motor vehicle are a navigation system 43, through which position information can be provided, and a data transmission unit 44. The data transmission unit 44 can be used, for example, to establish a connection to a backend, for example to obtain updated software for components of the motor vehicle. A memory 45 is provided for storing data. The exchange of data between the various components of the motor vehicle takes place via a network 46.

7 FIG. 1 schematically shows a method for controlling an imaging unit of a display device. In a first step, an observer is captured S1, for example with a camera. An eye position of the viewer with respect to an eyebox is then determined S2. An illumination characteristic of an illumination unit of the imaging unit is then adapted S3 in such a way that a light cone emerging from the imaging unit into the eyebox is restricted to an area around the eye position. A direction of the light cone is preferably adapted for this purpose, for example by means of an activation of selected light sources of the imaging unit. Alternatively, an angle-changing element can be mechanically adjusted on an illumination side of the imaging unit, for example a mirror or an optical plate. Preferably, content displayed by a display element of the imaging unit is tracked according to an illuminated area of the display element.

8th shows a simplified schematic representation of a first embodiment of a device 50 for controlling an imaging unit of a display device 1. The device 50 has an input 51, via which, for example, images B of a camera 42 for interior surveillance are received. An evaluation module 52 is set up to determine an eye position of a viewer in relation to an eyebox by evaluating the received data. A control module 53 is set up to adjust an illumination characteristic of an illumination unit of the imaging unit in such a way that a light cone emerging from the imaging unit into the eyebox is restricted to an area around the eye position. A direction of the light cone is preferably adapted for this purpose, for example by means of an activation of selected light sources of the imaging unit. Alternatively, an angle-changing element can be mechanically adjusted on an illumination side of the imaging unit, for example a mirror or an optical plate. For this purpose, the control module 53 can output corresponding control commands SB to the display device 1 via an output 56 of the device 50 . Preferably, content displayed by a display element of the imaging unit is tracked according to an illuminated area of the display element.

The evaluation module 52 and the control module 53 can be controlled by a control module 54 . If necessary, settings of the evaluation module 52, the control module 53 or the control module 54 can be changed via a user interface 57. If required, the data generated in the device 50 can be stored in a memory 55 of the device 50, for example for later evaluation or for use by the components of the device 50. The evaluation module 52, the control module 53 and the control module 54 can be used as dedicated Be realized hardware, for example as integrated circuits. Of course, they can also be partially or fully combined or implemented as software running on a suitable processor, such as a GPU or a CPU. The input 51 and the output 56 can be implemented as separate interfaces or as a combined interface.

9 shows a simplified schematic representation of a second embodiment of a device 60 for controlling an imaging unit of a display device. The device 60 has a processor 62 and a memory 61 . For example, the device 60 is a control unit or an embedded system. Instructions are stored in the memory 61 which, when executed by the processor 62, cause the device 60 to carry out the steps according to one of the methods described. The instructions stored in the memory 61 thus embody a program which can be executed by the processor 62 and implements the method according to the invention. Device 60 has an input 63 for receiving information. Data generated by the processor 62 is provided via an output 64 . In addition, they can be stored in memory 61. The input 63 and the output 64 can be combined to form a bidirectional interface.

Processor 62 may include one or more processing units, such as microprocessors, digital signal processors, or combinations thereof.

The memories 55, 61 of the devices described can have both volatile and non-volatile memory areas and can include a wide variety of memory devices and storage media, for example hard disks, optical storage media or semiconductor memories.

Reference List

1

display device

2

mirror unit

3

viewer

4

eyebox

5

stray light source

10

imaging unit

11

display element

12

lighting unit

13

optical unit

14

Housing

15

cone of light

16

light source

17

Angle changing element

170

optical disc

171

Mirror

18

actuator

20

windshield

21

folding mirror

22

curved mirror

23

Transparent cover

24

Optical film/polarizer

25

glare protection

40

means of transportation

41

sensors

42

camera

43

navigation system

44

data transfer unit

45

Storage

46

network

50

contraption

51

Entry

52

evaluation module

53

control module

54

control module

55

Storage

56

Exit

57

user interface

60

contraption

61

Storage

62

processor

63

Entry

64

Exit

B

camera image

SB

control command

SB1

bundle of rays

SB2

bundle of rays

SL

sunlight

vb

virtual image

S1

capturing a viewer

S2

determining an eye position

S3

Adjusting a lighting characteristic

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 102015215180 A1 [0006]
• DE 102013001380 A1 [0007]

Claims (11)

Method for controlling an imaging unit (10) of a display device (1), with the steps: - determining (S2) an eye position of a viewer (3) in relation to an eyebox (4); and - Adapting (S3) an illumination characteristic of an illumination unit (12) of the imaging unit (10) such that a light cone (15) emerging from the imaging unit (10) into the eyebox (4) is restricted to an area around the eye position. procedure according to claim 1 , wherein the adjustment (S3) of the lighting characteristic comprises an adjustment of a direction of the light cone (15). procedure according to claim 2 , wherein the adjustment of the direction of the light cone (15) includes a control of selected light sources (16) of the imaging unit (10). procedure according to claim 2 , wherein the adjustment of the direction of the light cone (15) comprises a mechanical adjustment of an angle-changing element (17) on an illumination side of the imaging unit (10). procedure according to claim 4 , wherein the angle-changing element (17) is a mirror (171) or an optical plate (170). Method according to one of claims 2 until 5 , Contents displayed by a display element (11) of the imaging unit (10) being tracked according to an illuminated area of the display element (11). A computer program comprising instructions which, when executed by a computer, enable the computer to carry out the steps of a method according to any one of Claims 1 until 6 to control an imaging unit (10) of a display device (1). Device (50) for controlling an imaging unit (10) of a display device (1), having: - An evaluation module (52) for determining (S2) an eye position of a viewer (3) in relation to an eye box (4); and - a control module (53) for adapting (S3) an illumination characteristic of an illumination unit (12) of the imaging unit (10) in such a way that a light cone (15) emerging from the imaging unit (10) into the eyebox (4) onto an area around the eye position is restricted. Display device (1) with an imaging unit (10), wherein an illumination characteristic of an illumination unit (12) of the imaging unit (10) can be adjusted in such a way that a light cone (15) emerging from the imaging unit (10) into an eyebox (4) is restricted to an area around an eye position of a viewer (3). Display device (1) according to claim 9 , wherein the imaging unit (10) comprises light sources (16) that can be controlled individually or in groups or a mechanically adjustable angle-changing element (17) on an illumination side. Display device (1) according to claim 9 or 10 , wherein the display device (1) is part of a head-up display for a means of transportation (40).

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