DE102015226425A1 - Backlight device for backlighting a display unit for a head-up display, head-up display and method for backlighting a display unit for a head-up display - Google Patents

Abstract

The invention relates to a backlighting device (400) for backlighting a display unit (402) for a head-up display (100). The backlighting device (400) comprises at least one light source (404) for emitting a light beam (406) and at least one aperture (408) arranged between the light source (404) and the display unit (402) and having at least one aperture (410) for generating a beam cone (412) having a predetermined width using the light beam (406). Here, the diaphragm (408) and / or the diaphragm opening (410) is movable in at least one direction to change an angle of incidence of the beam cone (412) on the display unit (402).

Description

State of the art

The invention is based on a device or a method according to the preamble of the independent claims.

Modern vehicles may be equipped with a head-up display for displaying information in a field of view of a driver.

Disclosure of the invention

Against this background, with the approach presented here, a backlighting device for backlighting a display unit for a head-up display, a head-up display, a method for backlighting of such a display unit and further a control unit, which uses this method, according to the main claims presented. The measures listed in the dependent claims advantageous refinements and improvements of the independent claim device are possible.

A backlighting device for backlighting a display unit for a head-up display is presented, the backlighting device having the following features:
at least one light source for emitting a light beam; and
at least one aperture arranged between the light source and the display unit and having at least one aperture for generating a beam cone with a predetermined width using the light beam, wherein the aperture and / or the aperture is movable in at least one direction by an incident angle of the beam cone to change the display unit.

The display unit may be, for example, a liquid crystal display or a MEMS display. A head-up display may be understood to mean a display device for displaying information in a field of view of a driver of a vehicle. For example, a light source can be understood to mean a light emitting diode or laser diode or an arrangement of a plurality of such diodes. An aperture can be understood to mean an opaque, for example plate-shaped element. Depending on the embodiment, the diaphragm may be stationary, wherein the diaphragm opening may be movable within the diaphragm, or the diaphragm may be additionally or alternatively movable as a whole. For example, the width of the beam cone in dependence on a width of a viewing window, also called eyebox, in which the driver can perceive an image generated by the display unit, be predetermined.

The approach presented here is based on the finding that an incident angle of a beam cone on a display unit of a head-up display can be changed by the use of a diaphragm with a movable diaphragm opening. By changing the angle of incidence, for example, a position of an eyebox of the head-up display can be changed, for example to track the eyebox of an eye position of a viewer of the head-up display.

By means of the backlighting device, for example, an autostereoscopic head-up display, abbreviated to asHUD, with iris-controlled tracking and optics adapted to an imaging unit can be realized. This has the advantage that the eyeboxes of the head-up display can be tracked by means of a simple aperture in the backlight.

The creation of narrow eyeboxes for the two eyes of the observer represents a major challenge in the design of an autostereoscopic head-up display. The aim is to represent an image with sufficient homogeneity, brightness, low granulation and sufficient contrast in the eyeboxes. By way of example, the narrow eyeboxes for representing the two partial images can be produced in narrow solid angles by a correspondingly narrow emission on the display unit of an imaging unit.

Conventionally, a tracking of the eyeboxes generated with the eye movement of the observer, for example, realized by the entire imaging unit or at least the entire projection or backlight unit is rotated by a motor. This can be caused by the motorized system latency in the tracking.

According to one embodiment, the approach proposed here is based on a special backlighting device for backlighting the display unit, in which the required emission angles can be achieved, for example, by means of the apertures of the optical elements used in a homogenization stage of the backlighting device. As a result, it is possible to dispense with a scattering surface or a microlens array directly behind the display unit, for example an LCD module, and thus avoid granulation of the image or show-through of a microlens structure. By using a diaphragm at a suitable location of the backlight device, a sharp eyebox can be produced, wherein the system can be designed such that a displacement of the diaphragm results in a displacement of the illuminated eyebox. This has the advantage that the Eyebox can be tracked to the eye of the observer by a simple displacement of a small aperture.

Depending on the embodiment, the diaphragm can be realized as an electronic or mechanical diaphragm. By using such a trackable shutter, the latency can be substantially reduced or almost completely eliminated.

The efficiency of the system can, for example, be further increased by the following measures.

By using a LED backlit LCD module as a display unit, speckle formation can be avoided.

By realizing the radiation conditions required on the display unit by means of a corresponding design of elements in the homogenization stage, it is possible to dispense with a scattering surface or a microlens array directly behind the display unit. As a result, granulation in the image and a shine through of microlens array structures can be avoided.

The tracking can be realized for example by a controllable aperture in the backlighting device. This allows the system to follow low-latency head movements.

By tracking using the aperture tracking of the actual image generator can be omitted, which space can be saved.

The low supply of the diaphragm has the advantage that the system is relatively insensitive to the coupling of mechanical vibrations.

For example, the display unit can remain stationary during the tracking by means of the diaphragm. Thereby, deterioration of the image quality by rotating the display unit can be avoided.

According to one embodiment, an illumination of a microlens array contained in the homogenization stage can additionally be controlled. This allows a particularly high efficiency of the system can be achieved, since the light is concentrated on the eyeboxes to be illuminated.

According to one embodiment, the backlighting device can be realized with at least one collimating element arranged between the light source and the diaphragm for collimating the light beam. Additionally or alternatively, depending on the embodiment, the backlighting device may comprise at least one expansion element arranged between the diaphragm and the display unit for expanding the beam cone or at least one projection element arranged between the expansion element and the display unit for projecting a beam cone widened by the expansion element onto the display unit. By a collimation element, for example, a collimating lens can be understood. The expansion element may in particular be a microlens array. By a projection element, for example, a mirror or a projection lens can be understood. By this embodiment, a homogeneous backlighting of the display unit can be ensured.

According to a further embodiment, the light source can be designed to track the light beam of a movement of the diaphragm and, additionally or alternatively, of the diaphragm aperture. For this purpose, the light source may for example be rotatably arranged in the backlighting device. Alternatively, the light source may be stationary, wherein the light beam can be tracked by means of a movable reflection element, such as a rotating mirror, the movement of the aperture. This can prevent that the light beam is shaded when moving the aperture.

The backlighting device may further comprise at least one actuator for moving the shutter. The actuator can be designed to move the light source in addition to or as an alternative to the diaphragm. In this case, the diaphragm and the light source can be mechanically coupled to one another, for example. By this embodiment, the diaphragm or the light source can be moved precisely and quickly.

It is advantageous if the diaphragm is designed to change a size of the diaphragm opening. The aperture may be configured to additionally or alternatively change a shape of the aperture. The change of the aperture can be done by a mechanical or electrical control of the aperture. By this embodiment, a change of a shape or a size of the beam cone and thus an eyebox generated by the beam cone is made possible.

According to a further embodiment, the diaphragm may have at least one additional diaphragm opening for producing an additional beam cone with a predetermined width using the light beam. The additional aperture may be movable in at least one direction to change an angle of incidence of the additional beam cone on the display unit. This embodiment enables the generation of multiple beam cones using a single light source. In this case, the diaphragm can be formed, for example, to direct the beam cone into a beam path to a first subsection of the display unit for generating a first stereoscopic field and the additional beam cone in a beam path to a second subsection of the display unit for generating a second stereoscopic field.

For example, the backlighting device may include an additional light source for emitting an additional light beam to the additional aperture, wherein the aperture may be configured to generate the additional beam cone using the additional light beam.

It is also advantageous if the diaphragm opening and the additional diaphragm opening are arranged offset from one another in the x and / or y direction. An x-direction can be understood as an x-axis extending within a main plane of extension of the diaphragm. Correspondingly, a y-direction can be understood to mean a y-axis which extends within the main extension plane and which can be oriented orthogonally to the x-axis. By this embodiment, the beam cone and the additional beam cone can be deflected in different directions.

Furthermore, it is advantageous if the diaphragm is designed to change a distance between the diaphragm opening and the additional diaphragm opening.

For example, such a change in the distance can be effected by a mechanical or electrical control of the diaphragm. This makes it possible to change a distance between the beam cone and the additional beam cone.

The approach presented here also creates a head-up display with the following features:
a display unit; and
a backlighting device according to one of the preceding embodiments.

According to one embodiment, the display unit may have a first subsection for generating a first stereoscopic field and a second subsection for generating a second stereoscopic field. In this case, the backlighting device can be designed to backlight the first section with the beam cone and the second section with an additional beam cone. This embodiment enables the generation of a stereoscopic image using a single display unit.

According to another embodiment, the display unit may be configured to generate a first stereoscopic field. The head-up display can have a further display unit for generating a second stereoscopic field and a further backlighting device for backlighting the further display unit. The further backlighting device may have at least one further light source for emitting a further light beam and at least one further diaphragm arranged or arrangeable between the further light source and the further display unit with at least one further diaphragm opening for producing a further beam cone with a predetermined width using the further light beam. In this case, the further diaphragm and, additionally or alternatively, the further diaphragm opening can be movable in at least one direction to an angle of incidence of the other Beam cone to change the other display unit. By this embodiment, the two fields can be generated on different display units independently of each other.

Advantageously, the head-up display may comprise a beam splitter, which may be designed to reflect the first stereoscopic field into a beam path to a first eye of a viewer of the head-up display and, additionally or alternatively, the second stereoscopic field in FIG to transmit a beam path to a second eye of the observer. This can improve the visual quality of the image in the field of view of the observer.

The approach described here also provides a method for backlighting a display unit for a head-up display according to one of the preceding embodiments, wherein the method comprises the following steps:
Activating the light source to emit the light beam; and
Providing a control signal in response to activating the light source to move the aperture and / or the aperture.

In one embodiment, the method may include a step of reading a sensor signal. The sensor signal may represent an eye position of a viewer of the head-up display detected by at least one sensor. Accordingly, in the step of providing, the control signal may be provided using the sensor signal to change the angle of incidence of the beam cone in response to the eye position. As a result, the field of view in which the observer can perceive the image generated by the display unit can be increased.

This method can be implemented, for example, in software or hardware or in a mixed form of software and hardware, for example in a control unit.

The approach presented here also provides a control unit that has units that are designed to perform the steps of a variant of a method presented here in corresponding facilities to drive or implement. Also by this embodiment of the invention in the form of a control device, the object underlying the invention can be achieved quickly and efficiently.

For this purpose, the control unit can have at least one arithmetic unit for processing signals or data, at least one memory unit for storing signals or data, at least one interface to a sensor or an actuator for reading sensor signals from the sensor or for outputting control signals to the actuator and / or or at least a communication interface for reading or outputting data embedded in a communication protocol. The arithmetic unit may be, for example, a signal processor, a microcontroller or the like, wherein the memory unit may be a flash memory, an EPROM or a magnetic memory unit. The communication interface can be designed to read or output data wirelessly and / or by line, wherein a communication interface that can read or output line-bound data, for example, electrically or optically read this data from a corresponding data transmission line or output to a corresponding data transmission line.

In the present case, the control unit can be used in connection with a control of a head-up display, in particular an autostereoscopic head-up display, in a vehicle.

Also of advantage is a computer program product or computer program with program code which can be stored on a machine-readable carrier or storage medium such as a semiconductor memory, a hard disk memory or an optical memory and for carrying out, implementing and / or controlling the steps of the method according to one of the embodiments described above is used, especially when the program product or program is executed on a computer or a device.

Embodiments of the invention are illustrated in the drawings and explained in more detail in the following description. It shows:

1 a schematic representation of a head-up display according to an embodiment;

2 a schematic representation of a basic operation of an autostereoscopic head-up display according to an embodiment;

3 a schematic representation of an imaging unit for an autostereoscopic head-up display;

4 a schematic representation of a head-up display according to an embodiment;

5 a schematic representation of a head-up display from 4 ;

6 a schematic representation of an autostereoscopic head-up display with two backlighting devices according to an embodiment;

7 a schematic representation of an illumination of a microlens array 6 ;

8th a schematic representation of a backlight device with a movable light source according to an embodiment;

9 a schematic representation of a head-up display with a deflection mirror according to an embodiment;

10 a schematic representation of a head-up display with a deflection mirror according to an embodiment;

11 a schematic representation of an autostereoscopic head-up display with two-part display unit according to an embodiment in side view;

12 a schematic representation of an autostereoscopic head-up display 11 in the plan view;

13 a schematic representation of a diaphragm of the 11 and 12 ;

14 a schematic representation of an autostereoscopic head-up display according to an embodiment;

15 a schematic representation of an autostereoscopic head-up display according to an embodiment;

16 a schematic representation of a portion of a backlighting device according to an embodiment;

17 a schematic representation of a portion of a backlighting device 16 ;

18 a flowchart of a method according to an embodiment; and

19 a schematic representation of a control device according to an embodiment.

In the following description of favorable embodiments of the present invention, the same or similar reference numerals are used for the elements shown in the various figures and similar acting, wherein a repeated description of these elements is omitted.

1 shows a schematic representation of a head-up display 100 according to an embodiment. The head-up display 100 is in a vehicle 102 built-in.

The head-up display 100 forms an image plane of an imager unit 104 , PGU (picture generating unit), using a head-up display optics 106 on a virtual, in front of the vehicle 102 located canvas 108 from. This will take a driver of the vehicle 102 that from the imager unit 104 generated image increases true. This image is superimposed, for example, with a driving scene and appears from the perspective of the driver at a defined distance from a windshield of the vehicle on the virtual screen 108 , As an imaging element within the imager unit 104 For example, an LCD module is used.

The illustrated virtual image is an enlarged image of that from the imager unit 104 generated image. The head-up display optics 106 is designed to increase this image accordingly. Here, the required magnification with the distance of the virtual screen 108 increase, ie, that of the imager unit 104 The larger the distance in which the image is to be displayed in the field of vision of the driver, the larger the image produced is. For example, the virtual screen points 108 a distance of about 15 m.

2 shows a schematic representation of a basic operation of an autostereoscopic head-up display 100 according to an embodiment. In contrast to 1 is the head-up display 100 realized here as an autostereoscopic head-up display system. This is the head-up display 100 designed to produce separate partial images for the left and right eye. This can be a 3-D effect can be achieved. For example, the two partial images are already being processed by the imaging unit 104 generated. About the head-up display optics 106 The light of the partial images is made available to the respective eye in a smaller eyebox.

Here, the two partial images for the left and right eyes are displayed on a display unit of the image generator unit 104 emitted in different directions and via the head-up display optics 106 fed to the respective eye in a corresponding Eyebox.

At the head-up display 100 For example, it is a projection-based system based on a DLP or LCoS projector. The head-up display 100 However, it can also be realized on LCD basis. Here, a liquid crystal display is provided with a corresponding backlight.

3 shows a schematic representation of an imager unit 104 for an autostereoscopic head-up display. Shown is a possible concept of an imager unit based on two LCD modules 300 as projectors. The two LCD modules 300 are arranged such that the two partial images on the projection surface radiate in slightly different directions in order to hit the respective eyebox.

The two fields are by means of a beam splitter 302 superimposed and each have their own backlighting in the form of a light emitting diode 304 on. The backlighting expands the light accordingly. This is how the LCD modules shine 300 in cones that illuminate the Eyebox for the left and right eye via the head-up display optics. To the necessary beam widening to produce the Abstrahlkegel on the LCD modules 300 can each generate directly behind the LCD modules 300 a scattered surface 306 or a microlens array. Also shown are illumination optics 308 as well as two field lenses 310 ,

This may cause deterioration of image quality and eyebox shaping. For example, scattered surfaces that radiate into narrow angles to create narrow eyeboxes can result in granulation in the image content. In addition, the scattering is often there in the form of a Gaussian profile, which can decrease the eyebox brightness to the edge of the Eyebox. If the observer moves his eye within the eyebox, he perceives differently bright images, which may make the images appear inhomogeneous. When using microlens arrays, chromatic effects can develop, which can lead to color gradients in the image. In addition, small microlenses can have a diffractive effect and lead to a crosstalk of a partial image in the wrong eye. If a microlens array is arranged close to an imaging plane of the head-up display optics, the magnification of the head-up display optics can lead to imaging of the microlens structure, which can then be perceived as a lens grid in the image.

Also in 3 indicated is a possible tracking system, characterized by a dashed line and an arrow. The tracking system is designed, for example, around the entire imaging unit 104 around a central in the imager unit 104 to turn lying axis of rotation.

The rotation changes the directions of the radiation relative to the subsequent head-up display optics so that the eyeboxes of both eyes move with the observer. The area in which the eyeboxes can be moved and within which the observer can perceive the displayed image can also be referred to as the totality box.

Alternatively, an entire lighting system behind the LCD modules 300 around the LCD modules 300 to be turned around.

4 shows a schematic representation of a head-up display 100 according to an embodiment. The head-up display 100 includes according to this embodiment, a backlight device 400 for backlighting a display unit 402 , The backlighting device 400 has a light source 404 , here a light-emitting diode, for emitting a light beam 406 and one between the light source 404 and the display unit 402 arranged aperture 408 with a shutter 410 on. The light beam 406 is through the aperture 410 to a beam cone 412 formed at a certain angle of incidence on the display unit 402 meets. According to this embodiment, the aperture is 408 and thus the aperture 410 displaceable, so by moving the aperture 408 the angle of incidence of the beam cone 412 can be varied.

For realizing movable eyeboxes by means of tracked aperture, the display unit 402 which is part of a preceding on the basis of 1 to 3 can be described imaging unit, for example, by a multi-stage optical system as a backlighting device 400 backlit, by the appropriate radiation conditions on the display unit 402 can be generated. Advantageously, the eyebox forming takes place here by placing the panel 408 in a suitable place.

In 4 illustrates the operation of the system proposed here using an exemplary embodiment. Here, the light of the light source 404 by means of an optional collimation element 414 , here a collimation lens, in the direction of an optional expansion element 416 passed in the form of a microlens array. Between the collimation element 414 and the expansion element 416 is the controllable aperture 408 arranged, which is linearly displaceable according to this embodiment. The beam cone 412 irradiated microlenses of the expansion element 416 are trained to the light of the beam cone 412 dilate. The thus expanded beams are by means of an optional projection element 418 , here a projection lens, on the display unit 402 superimposed, which is realized for example as an LCD module.

The different points on the display unit 402 are hit by light rays from all illuminated microlenses. From every point on the display unit 402 emits a light cone whose beam width of the width of the aperture 408 depends. About the head-up display optics 106 become the light cones of the individual display points in an eyebox 420 superimposed for one eye. By moving the aperture 408 becomes the display unit 402 illuminated from another direction, so that a beam cone results from the display unit 402 off in another direction. About the head-up display optics 106 become the individual rays of the ray cone in the Eyebox 420 that are within a total box 422 is displaceable, superimposed.

Through the aperture 408 becomes the beam cone 412 defined with a certain width to over the head-up display optics 106 a narrow eyebox 420 to create. By moving the iris 408 can the eyebox 420 in the design area of the Gesamteyebox 422 be moved.

5 shows a schematic representation of a head-up display 100 out 4 with deflected eyebox 420 , The illustration illustrates the generation of the from a single display point 500 originating beam cone 412 on the display unit 402 through which the eyebox 420 is formed. The beam cone 412 consists of individual partial beams of the different microlenses of the expansion element 416 together.

By moving the aperture 408 becomes the eyebox 420 within the total box 422 postponed. As in 5 to recognize, all the more rays through the display point 500 passed, the wider the front of the expansion element 416 located aperture 410 is, resulting in a wider beam cone 412 leads. The width of the beam cone 412 thus determines the width of the eyebox 420 , ie the eyebox width can be defined by the width of the aperture 410 to adjust.

In this way it is possible by moving the aperture 408 the complete area of the total box 422 to track. Because with this form of tracking only the aperture 408 is moved, no space for the swinging out of the entire imaging unit must be kept. By eliminating a large engine can also be saved space. As a result, the design can be easily integrated into specified installation spaces in a vehicle. Due to the reduced space requirement, for example, conflicts with a steering column of the vehicle can be avoided.

The display unit 402 For example, it is stationary, which avoids that the display unit 402 moved out of the image plane during tracking and thus degrades the image quality.

By virtue of such a homogenization stage of an LCD illumination, various requirements can therefore be fulfilled at the same time. On the one hand can through the aperture of the expansion element 416 the complete total box 420 to be served. The aperture 408 results in an effectively lower utilized aperture of the expander element 416 , whereby the beam width is adjusted so that the head-up display optics 106 a sharp eyebox can be produced. Another advantage of the backlighting device 400 consists in the uniform illumination of the display unit 402 because the individual illuminated channels of the expansion element 416 evenly on the display unit 402 be superimposed.

According to an alternative embodiment, the backlighting device 400 also several expansion elements 416 , For example, a plurality of microlens arrays have. By using several such expansion elements, the system can be adapted to a wider light source. As a result, for example, multiple light sources can be used for backlighting, whereby the brightness can be increased.

While that in 5 For the realization of an autostereoscopic head-up display, it is necessary to provide two eyeboxes at the same time, whereby the two eyeboxes each offer the observer a different partial image.

For this purpose, the display unit 402 For example, be configured to switch time-sequentially between the two fields. Accordingly, the aperture 408 be formed to analogously to a switching of the display unit 402 Jump sequentially between different positions in order to guide the two partial images into the two eyeboxes. This can be the aperture 408 For example, be realized as an electronic shutter, as described in more detail below.

Alternatively, the two partial images can be generated by means of two display units, the display units being superimposed by means of a beam splitter and each having its own backlighting and its own controllable diaphragm, as described below with reference to FIG 6 described.

6 shows a schematic representation of an autostereoscopic head-up display 100 with two backlight devices 400 . 600 according to an embodiment. In contrast to a preceding by means of 5 Head-up display described has the head-up display 100 according to this embodiment, in addition to the backlight device 400 another backlighting device 600 for backlighting another display unit 602 on. The further backlighting device 600 is analogous to the backlighting device 400 with a further light source, a further diaphragm with a movable diaphragm opening for generating a further beam cone 604 with a predetermined width and an optional further expansion element 605 for expanding a light beam emitted by the further light source.

The display unit 402 is designed to be made using the beam cone 412 to generate a first stereoscopic field. In a corresponding manner, the further display unit 602 designed to be made using the further beam cone 604 to generate a second stereoscopic field.

Exemplary is in 6 a simulation of an autostereoscopic head-up display system with LCD-based imaging unit and tracking by means of integrated in the backlight aperture. The simulated system is shown starting from microlens arrays as expansion elements 416 . 605 the homogenization stage in the backlight of the two display units 402 . 602 , Via a projection lens 418 and an additional angle-deflecting backlight optics 606 become the display units 402 . 602 each lit evenly. A beam splitter 608 is designed to overlay two analog paths, each path having its own display unit and each path providing a field. In the other display unit 602 associated path is an optional deflecting mirror for adaptation to a vehicle space 610 brought in. Through the respective panel in front of the expansion elements 416 . 605 then the Eyebox of the respective field can be adjusted, as follows from 7 described.

The partial images are, for example, via the head-up display optics 106 and a combiner 612 steered into the eyeboxes.

Below are examples of possible system parameters of the head-up display 100 listed. The first column contains parameters, the second column the values assigned to the parameters, and the third column a description. Assemblers Yes aspherical VID 5 m virtual screen distance FOV 10 ° × 4 ° Field of View EB 140 mm × 60 mm Eyeboxgröße MLA 32 mm × 12 mm Dimensions MLA

7 shows a schematic representation of an illumination of expansion elements 416 . 605 out 6 , The illustration shows incident beams of the two expansion elements located in the different paths 416 . 605 superimposed in a diagram. The two expansion elements are the same size. With complete illumination of one of the expansion elements, the partial image would flood the complete total box. However, to illuminate only a small eyebox for an eye, only a smaller part of a widening element is used.

The illustrated points of incidence of the light rays thus give the used area of the expansion elements 416 . 605 for certain eyebox positions again, in which an observer with an eye relief of, for example, 65 mm in the middle of the Gesamteyebox. By means of the diaphragms on the expansion elements in size of the illuminated area shown here, an eyebox can thus be formed at the respective location of the observer's eye. By shifting the aperture, the respective eyebox shifts in the same way. To be able to move the illuminated eyeboxes over the complete total box of, for example, 140 mm width, the panels are here over a width of a widening element, for example, 32 mm displaced. This means that the bezels should be placed 0.23 mm in front of the corresponding expansion element to achieve eyebox positioning with 1mm accuracy. The requirements for a tolerance of the aperture as tracked adjusting units, for example by means of a motor, can thus be correspondingly low.

In 7 are the results of the utilized range of expander elements from the system according to 6 shown. The expansion elements have, for example, dimensions of 32 mm wide and 12 mm high. The expansion element in the respective path is designed, for example, such that it is able to serve the totalysis box. The individual Eyeboxes for each eye are smaller and move within the Gesamteyebox with the movement of the observer's eye. The respectively used areas of the expansion elements for an observer located in the middle of the total byte box are shown. With complete illumination of the expansion elements, the impact points of the used beams shown here thus show that area in which the diaphragm should be cut out for the respective partial image. As the observer moves, the apertures shift accordingly to the left or right.

The system shown here provides in its backlight light for illuminating the complete Gesamteyebox in which an eye is allowed to move. Through a diaphragm light rays are shadowed, which are not needed for the respective field.

The autostereoscopic approach presented here also offers the potential for further increases in efficiency. In principle, one eye of the observer does not move across the entire area of the total box. As soon as one eye comes out of the design area, it is no longer necessary to operate the other eye, which reduces the effective area to be followed by one eye. With a total box width of, for example, 140 mm and an average eye relief of 65 mm, the area to be tracked for an eye thus reduces to 75 mm. If the offered light is restricted to this area, this increases the amount of light in the small eyebox and thus the efficiency by about twice.

By additionally tracking the radiation of the LED backlight, the efficiency can be further increased. This will be explained below with reference to 8th described in more detail.

According to one embodiment, the diaphragms are not realized as mechanical but electronic diaphragms, for example in the form of LCD cells. In this case, the diaphragms can be designed to turn black pixels to be shaded. By using an LCD cell as an aperture light can be lost because the LCD cell polarizes the light and has only a finite transmission. However, if the polarization of the transmitted light is adapted to the respective display unit to be irradiated, which may be an imaging LCD module, for example, the loss due to the polarization can be reduced.

For example, such an electronic shutter may be configured to switch as fast as the corresponding display unit can switch time sequentially between two stereoscopic partial images. For example, the display unit may be configured to switch between the two partial images at a frequency of 120 Hz, so that the respective partial image can be perceived by the observer with a perceived pleasant frequency of 60 Hz.

8th shows a schematic representation of a backlighting device 400 with movable light source 404 according to an embodiment. In the backlight device 400 is, for example, a backlighting device, as described above with reference to 4 to 7 is described. According to this embodiment, the light source 404 designed as a controllable LED to increase the efficiency of the system.

Due to the aperture 408 , is the aperture of the expansion element 416 only a certain part used. Here is the light source 404 designed so that it only the aperture 410 illuminates and is self-tracking. The light source 404 lights up in a certain angle range, which after collimation by the Kollimationselement 414 the aperture 410 illuminates. To achieve such a narrow radiation, the light source 404 be executed for example with a reflector or an attachment lens.

Moves the aperture 410 , so will the light source 404 for example, according to rotated or shifted to the illumination of the aperture 410 to track. The tracking of the light source 404 may alternatively be realized by means of a small deflection mirror or other suitable optical element. To the light source 404 synchronous to a movement of the aperture 410 can track the light source 404 optional mechanical with the panel 408 be coupled. This eliminates the need for an additional actuator for tracking.

For example, the light source 404 trained to the light beam 406 to radiate in a narrow cone, the aperture 410 in front of the expansion element 416 fully illuminates. If the panel moves over the expansion element 416 to track the eyebox of the overall system, so does the light source 404 turned. This lights the light source 404 the aperture 410 continue full. By doing so on the aperture 410 Focused light increases the efficiency of the system.

9 a schematic representation of a head-up display 100 with a deflection mirror 900 according to an embodiment. The head-up display 100 is essentially the same as based on 5 described head-up display, with the difference that the head-up display 100 instead of the aperture with the deflection mirror 900 for shaping the beam cone 412 is executed.

With a corresponding beam shaping of the light source 404 can be dispensed with the aperture, whereby the mechanical complexity of the tracking can be further reduced. 9 shows an example of a system with a rotating mirror as a deflection mirror 900 directly after the light source 404 , Through the deflection mirror 900 can different areas of the expansion element 416 be illuminated, causing the eyebox 420 can be moved. About the deflection mirror 900 becomes the light beam 406 such as in the form of a narrow-angle cone on the expansion element 416 reflected.

10 shows a schematic representation of a head-up display 100 with the deflection mirror 900 according to an embodiment. In contrast to 9 is the deflection mirror 900 , here also a rotating mirror, in a beam path between the projection element 418 and the display unit 402 arranged. According to this embodiment, the deflection mirror 900 formed to one of the expansion element 416 Beam cone radiated in a first direction in a second direction deviating from the first direction, for example by 90 degrees, on the display unit 402 redirect. This leads to the deflection mirror 900 the entire irradiated beam cone at different angles on the display unit 402 , This will cause the radiation on the display unit 402 correspondingly inclined, causing a shift of the eyebox 420 in the total box 422 leads.

According to one embodiment, the expansion element 416 and the corresponding lenses designed so that they have a narrow eyebox 420 produce. The display unit 402 This is illuminated with a beam cone that passes over the sides of the display unit 402 radiates. This allows the display unit 402 even with twisted deflection mirror 900 be fully lit. Upon rotation of the deflecting mirror 900 becomes the emission direction of the light beams on the display unit 402 also distracted, causing the eyebox 420 moves accordingly.

11 shows a schematic representation of an autostereoscopic head-up display 100 with two-part display unit 402 according to an embodiment in the side view. In contrast to a preceding on the basis of 1 to 10 described head-up display is the head-up display 100 according to 11 with a in a first section 1100 for generating a first stereoscopic field and a second subsection 1102 for generating a second stereoscopic field divided display unit 402 realized. Accordingly, the aperture 408 next to the aperture 410 an additional aperture 1104 which is designed to use the light beam 406 an additional beam cone 1106 to form the second subsection 1102 backlit. The through the aperture 410 generated beam cone 412 in contrast, backlit the first section 1100 ,

This in 11 shown stereo head-up display 100 with display division, according to one embodiment, the beam splitter 608 on. The beam splitter 608 is formed to the two subsections 1100 . 1102 so virtually superimposed that the first field is reflected in a beam path to a first eye of the observer and the second field is transmitted in a beam path to a second eye of the observer. According to this embodiment, the beam splitter is 608 substantially perpendicular to the display unit 402 between the two subsections 1100 . 1102 , The two subareas 1100 . 1102 lie in the in 11 shown side view on top of each other.

The two aperture 410 . 1104 For example, they are formed as open aperture slots that are offset from each other.

12 shows a schematic representation of an autostereoscopic head-up display 100 out 11 in the plan view. The two sections of the display unit 402 be here by the staggered apertures 410 . 1104 illuminated from a different angle, which leads to the generation of eyeboxes in different places.

Through the mutually offset apertures 410 . 1104 In each case an eyebox for different eye positions is generated, with the aperture 410 is trained to the eyebox 420 to generate, and the additional aperture 1104 is designed to be an additional eyebox 1200 within the total box 422 to generate. As a result, each partial image supplied to each eye, that of the respective subsection of the display unit 402 is produced. Due to the spatial distribution of the display unit 402 in the two sections, it is no longer necessary, the display unit 402 quickly switch between two sub-images. This allows the display unit 402 , which can be realized in particular as an LCD module, even at low temperatures use.

13 shows a schematic representation of a panel 408 from the 11 and 12 , To recognize the two here exemplified as rectangular aperture slots shaped apertures 410 . 1104 , The apertures 410 . 1104 are arranged offset to each other both in the x-direction and in the y-direction. The x and y directions are in 13 characterized by corresponding coordinate axes x and y, respectively, in the plane of the diaphragm 408 lie.

Alternatively to the in 13 shown aperture 408 with a fixed distance between the apertures 410 . 1104 For example, two mechanically decoupled diaphragms each with an aperture can be used, which can be moved independently. Alternatively, the aperture 408 be configured to use a additional actuator to set a slot spacing between the apertures. It is also conceivable to use a diaphragm with a variable slot width.

By using such apertures, the system can be adjusted to the individual eye distance of the observer, since different slot spacings lead to eyeboxes of different distances from each other. The width of the eyeboxes can be adjusted by a variable aperture slot width. As the observer moves forward or backward, a respective eyebox width can be adjusted to prevent crosstalk of a partial image into the wrong eye.

14 shows a schematic representation of an autostereoscopic head-up display 100 according to an embodiment. According to this embodiment, the display unit 402 implemented as a MEMS-based display.

Such a MEMS display offers the advantage of rapid switching, even at low temperatures, making it particularly suitable for use in motor vehicles.

The display unit 402 works with micromechanical shutters, which are time sequentially switchable and by the light source 404 and an additional light source 1400 can be irradiated time synchronously. The display unit 402 builds their image content pixel by pixel using the micromechanical shutter for each pixel. One of the additional light source 1400 emitted light beam, for example, by means of an additional Kollimationselementes 1402 , such as a collimating lens, to be collimated.

The in 14 shown system structure is with the in 5 shown system structure comparable. Because the display unit 402 Time sequentially switches between the two fields, both eyeboxes 420 . 1200 be generated with the same display unit. The eyeboxes 420 . 1200 can by moving the aperture 408 be tracked. The light sources 404 . 1400 light up an area over the actual apertures 410 . 1104 goes. The aperture 408 is movable in this area, without any tracking of the light sources 404 . 1400 is required.

For the display unit 402 is time sequential through the two apertures 410 . 1104 Illuminates and displays each of the first and second field, also called subpicture on. This makes the eyeboxes time-sequential 420 . 1200 built for the left and right eye. The tracking is done by moving the aperture 408 ,

15 shows a schematic representation of an autostereoscopic head-up display 100 according to an embodiment. In contrast to 14 are the two light sources 404 . 1400 according to 15 movable.

In 15 a variant of the system is shown in which the light sources 404 . 1400 only illuminate the area of their respective associated aperture. Thus, it is necessary for the two light sources to move the shutter 408 to track. This tracking can be realized for example by a corresponding rotation of the two light sources. Alternatively, the head-up display 100 a deflection mirror similar to the basis of 9 and 10 described deflecting mirror for tracking the light emitted from the two light sources light rays. It is also conceivable to use a deflecting lens in the vicinity of the light sources 404 . 1400 as stated below by 16 is described.

According to 15 the tracking is done by a shift of the aperture 408 and by a rotation of lighting units in the form of the light sources 404 . 1400 , Because the light sources 404 . 1400 are formed, in each case only the area of the apertures 410 . 1104 Illuminate, higher efficiency compared to the system 14 reached.

16 shows a schematic representation of a portion of a backlighting device 400 according to an embodiment. The backlighting device is, for example, a preceding one with reference to FIG 4 to 15 described backlight device. The backlighting device 400 includes one in a beam path of the light source 404 emitted light beam 406 arranged Umlenklinse 1600 for deflecting the light beam 406 , here a cylindrical lens. According to this embodiment, the Umlenklinse 1600 between the light source 404 and the collimation element 414 arranged.

The light beam 406 is through the Umlenklinse 1600 led the light beam 406 depending on their position in different directions on the Kollimationselement 414 passes. By a shift of the Umlenklinse 1600 becomes the light cone of the light source 404 deflected so that he moved accordingly to the collimation element 414 incident. Alternatively, the Umlenklinse 1600 designed as a liquid lens with variable lens curvature. The Umlenklinse 1600 For example, in a preceding on the basis of 8th and 15 described head-up display can be used.

17 shows the backlight device 400 out 16 , The 16 and Fig. 17 show the deflections of the light beam 406 for two different positions of the Umlenklinse 1600 ,

18 shows a flowchart of a method 1800 for illuminating a display unit for a head-up display according to an embodiment. The procedure 1800 For example, in connection with a preceding on the basis of 1 to 17 described head-up display are performed. This is done in one step 1810 the light source is activated to emit the light beam. In response to activating the light source, in a further step 1820 a control signal provided to move the aperture or the aperture.

According to an optional embodiment, in one step 1830 a sensor signal representing a detected by at least one sensor eye position of a viewer of the head-up display read. Accordingly, in step 1820 provided the control signal using the sensor signal to change the angle of incidence of the beam cone formed by the aperture opening in dependence on the eye position.

The steps 1810 . 1820 . 1830 can be executed continuously.

19 shows a schematic representation of a control device 1900 according to an embodiment. The control unit 1900 can, for example, in connection with a control of a preceding on the basis of 1 to 18 described head-up displays are used. For this purpose, the control unit 1900 an activation unit 1910 which is adapted to an activation signal 1915 to generate the light source and to the light source and to a delivery unit 1920 to send. The delivery unit 1920 is designed to operate using the activation signal 1915 a control signal 1925 to provide control of the aperture. For example, the control signal is used 1925 for controlling an actuator for moving the diaphragm or pixels of an electronic shutter.

If an exemplary embodiment comprises a "and / or" link between a first feature and a second feature, then this is to be read so that the embodiment according to one embodiment, both the first feature and the second feature and according to another embodiment either only first feature or only the second feature.

Claims (15)

Backlight device ( 400 ) for backlighting a display unit ( 402 ) for a head-up display ( 100 ), wherein the backlighting device ( 400 ) has the following features: at least one light source ( 404 ) for emitting a light beam ( 406 ); and at least one between the light source ( 404 ) and the display unit ( 402 ) arranged or can be arranged aperture ( 408 ) with at least one aperture ( 410 ) for generating a beam cone ( 412 ) with a predetermined width using the light beam ( 406 ), whereby the diaphragm ( 408 ) and / or the aperture ( 410 ) is movable in at least one direction to an angle of incidence of the beam cone ( 412 ) on the display unit ( 402 ) to change. Backlight device ( 400 ) according to claim 1, with at least one between the light source ( 404 ) and the aperture ( 408 ) arranged collimation ( 414 ) for collimating the light beam ( 406 ) and / or at least one between the diaphragm ( 408 ) and the display unit ( 402 ) arranged expansion element ( 416 ) for expanding the beam cone ( 412 ) and / or at least one between the expansion element ( 416 ) and the display unit ( 402 ) arranged projection element ( 418 ) for projecting one of the expansion element ( 416 ) expanded beam cone ( 412 ) on the display unit ( 402 ). Backlight device ( 400 ) according to one of the preceding claims, in which the light source ( 404 ) is adapted to the light beam ( 406 ) a movement of the diaphragm ( 408 ) and / or the aperture ( 410 ) track. Backlight device ( 400 ) according to one of the preceding claims, with at least one actuator for moving the diaphragm ( 408 ) and / or the light source ( 404 ). Backlight device ( 400 ) according to one of the preceding claims, in which the diaphragm ( 408 ) is adapted to a size and / or shape of the aperture ( 410 ) to change. Backlight device ( 400 ) according to one of the preceding claims, in which the diaphragm ( 408 ) at least one additional aperture ( 1104 ) for generating an additional beam cone ( 1106 ) with a predetermined width using the light beam ( 406 ), wherein the additional aperture ( 1104 ) is movable in at least one direction to an angle of incidence of the additional beam cone ( 1106 ) on the display unit ( 402 ) to change. Backlight device ( 400 ) according to claim 6, wherein the aperture ( 410 ) and the additional aperture ( 1104 ) are arranged offset in the x and / or y direction to each other. Backlight device ( 400 ) according to claim 6 or 7, wherein the diaphragm ( 408 ) is formed to a distance between the aperture ( 410 ) and the additional aperture ( 1104 ) to change. Head-Up Display ( 100 ) having the following features: a display unit ( 402 ); and a backlighting device ( 400 ) according to one of the preceding claims. Head-Up Display ( 100 ) according to claim 9, wherein the display unit ( 402 ) a first subsection ( 1100 ) for generating a first stereoscopic field and a second subsection ( 1102 ) for generating a second stereoscopic field, wherein the backlighting device ( 400 ) is adapted to the first subsection ( 1100 ) with the beam cone ( 412 ) and the second subsection ( 1102 ) with an additional beam cone ( 1106 ) to backlight. Head-Up Display ( 100 ) according to claim 9, wherein the display unit ( 402 ) is configured to generate a first stereoscopic field, wherein the head-up display ( 100 ) another display unit ( 602 ) for producing a second stereoscopic field and a further backlighting device ( 600 ) for backlighting the further display unit ( 602 ), wherein the further backlighting device comprises at least one further light source for emitting a further light beam and at least one between the further light source and the further display unit (US Pat. 602 ) arranged or can be arranged further diaphragm with at least one further diaphragm opening for generating a further beam cone ( 604 ) having a predetermined width using the further light beam, wherein the further aperture and / or the further aperture opening is movable in at least one direction to an angle of incidence of the further beam cone ( 604 ) to the further display unit ( 602 ) to change. Head-Up Display ( 100 ) according to claim 10 or 11, with a beam splitter ( 608 ), which is designed to bring the first stereoscopic field into a beam path to a first eye of a viewer of the head-up display ( 100 ) and / or to transmit the second stereoscopic field into a beam path to a second eye of the observer. Procedure ( 1800 ) for backlighting a display unit ( 402 ) for a head-up display ( 100 ) according to any one of claims 9 to 12, wherein the process ( 1800 ) includes the following steps: Activate ( 1810 ) of the light source ( 404 ) to the light beam ( 406 ) to send out; and deploy ( 1820 ) of a control signal ( 1925 ) in response to activating the light source ( 404 ) to the aperture ( 408 ) and / or the aperture ( 410 ) to move. Procedure ( 1800 ) according to claim 13, with a reading-in step ( 1830 ) of a sensor signal which comprises an eye position of an observer of the head-up display detected by at least one sensor ( 100 ), wherein in the step of providing ( 1820 ) the control signal ( 1925 ) is provided using the sensor signal to determine the angle of incidence of the beam cone (FIG. 412 ) depending on the eye position. Control unit ( 1900 ) with units ( 1910 . 1920 ), which are adapted to the steps of a method ( 1800 ) according to claim 13 or 14 execute and / or to control.

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