DE102014217180A1 - An image forming apparatus for a head-up display, head-up display, and method for generating an image for a head-up display - Google Patents

Abstract

The invention relates to an image generation device (106) for a head-up display (102). The image forming device (106) comprises at least one light source (108) for generating a light beam (114), at least one expansion element (110) arranged in a beam path of the light beam (114) to expand the light beam (114) and at least one A light modulator (112) disposed in an optical path of a light beam (116) flared by said expander member (110) for being illuminated simultaneously by said flare beam (116) at multiple angles and adapted to emerge from said flared light beam (116) to generate an image beam (122) representing an image (108).

Description

State of the art

The present invention relates to an image generation apparatus for a head-up display, to a head-up display, to a method for generating an image for a head-up display, to a corresponding control device and to a corresponding computer program.

Current head-up displays can image an image generated by an image generator unit, English picture generating unit (PGU), using an optical system on a virtual, located in front of the vehicle screen.

Such a projected virtual image can be perceived by a driver. In this case, the image can be superimposed with a driving scene and displayed at a defined distance from a windshield on the virtual screen.

For example, LCD modules can be used as imaging elements in the imaging unit.

Autostereoscopic head-up displays are also known, which work with separate partial images for left and right eye. This can produce a 3-D effect. In this case, the two partial images can already be generated by the imaging unit. The partial images can be made available to a respective eye in a corresponding eye movement region, also called an eyebox, via an optic of the head-up display.

Disclosure of the invention

Against this background, with the approach presented here, an image generation device for a head-up display, a head-up display, a method for generating an image for a head-up display, furthermore a control device that uses this method, as well finally presented a corresponding computer program according to the main claims. Advantageous embodiments emerge from the respective subclaims and the following description.

The approach proposed herein provides an image forming apparatus for a head-up display, the image forming apparatus comprising:
at least one light source for generating a light beam;
at least one expansion element disposed in a beam path of the light beam to expand the light beam; and
at least one light modulation device arranged in a beam path of a light beam expanded by the expansion element to be illuminated simultaneously by the expanded light beam from a plurality of angles and adapted to generate an image beam representing the image from the expanded light beam.

A head-up display can be understood as a visual field display device for projecting an image into a field of view of a viewer. In this case, the image can be projected, for example, into an eye movement area assigned to a respective eye of the observer. The head-up display may be installed in a vehicle to project the image into the field of vision of a driver by means of a windshield of the vehicle. An imaging device may be understood to mean a component of the head-up display which is designed to generate a light beam and to impose an image content to be displayed on the light beam. A light source may be, for example, a laser or LED source. An expansion element can be understood to mean an optical element for changing a light cone of the light beam, more precisely an opening angle of the light cone. The expansion element can be realized, for example, as a scattering surface, lens or microlens array. A light modulation device may be understood to mean a surface light modulator, such as an LCoS display or a micromirror array, in particular a DLP chip (digital light processing). An image may be understood to mean graphic information, such as a navigation arrow or a speed indicator.

The present approach is based on the finding that it is possible to direct a light beam generated by an imager unit of a head-up display by means of a surface light modulator directly on a mirror of the head-up display, without the light beam by means of a between the surface light modulator and the Mirror arranged scattered surface in addition to shape. This is achieved by the present approach in that such a scattering surface or another optical element suitable for shaping the light beam is integrated into the imaging unit and is arranged between the area light modulator and an illumination source for illuminating the area light modulator. Such an arrangement of the scattering surface between the surface light modulator and the illumination source, the display quality of the head-up display over conventional solutions can be significantly improved.

A virtual image represented by a head-up display is an enlarged image of a display of an imager unit. For this purpose, an optic of the head-up display has a certain magnification. The necessary magnification increases with a distance of the virtual screen, since the image generated by the imager unit must be increased more to take a desired field of view of the driver at a greater distance. The distance of the virtual screen is at current head-up displays at about 15 m.

In the reverse light path, enlarging the head-up display optics when exposed to sunlight can cause the sunlight to focus on the imager. This is then heated up and reaches temperatures that can destroy the imager. Temperature increases can be critical, especially for systems based on LCD modules, since the LCD modules can be permanently damaged even at a temperature of approx. 100 ° C. From about 95 ° C can lead to a delamination of the polarizing filter, from about 105 ° C to an isotropic liquid crystal and from about 125 ° C to a permanent liquid crystal damage.

There are known approaches according to which DLP or LCoS (liquid crystal on silicon) projectors can be used as a basis for projection-based head-up displays. In the process, an imager, for example an LCoS or DLP chip, is illuminated within the projector with collimated light. An LCoS chip, for example, rotates the polarization of the light with active pixels and reflects. As a result, the light of the active pixels can be deflected by a beam splitter located in front of the LCoS chip, while the light of inactive pixels with unchanged polarization direction is reflected back into the light source.

Typically, the image content created by the imager is imaged onto a scatter surface using a lens. On the scattering surface, therefore, a real, enlarged image of the imager is generated. Due to the almost collimated illumination of the imager, the angle at which the rays of a pixel intersect in focus on the scattering surface is very small. Nevertheless, in order to be able to view the pixel from different angles, the light rays of this pixel are fanned out by the scattered surface into a larger spatial area.

The imaging optics of the head-up display, the rays are distributed over the eyebox, whereby the pixel can be viewed from the entire eyebox. All rays seem to come from a virtual point behind the windshield. It creates the impression as if the entire image was in virtual screen distance in front of the vehicle.

A DLP projector works in a similar way to an LCoS projector, except that the DLP projector is not based on a polarization-dependent element but on small, hinged mirrors. In this case, the light of a lighting unit can be conducted through a TIR prism (total internal reflection). When the beams hit a micromirror array of the DLP chip, the active pixels are switched so that the reflected beam within the prism undergoes total internal reflection. As a result, the rays of the active pixels are guided to the objective. By mirroring non-active pixels, rays can be directed back to the light source.

By means of the present approach, a display system with a small imager can now be realized as an imager and without a scattering surface in the imaging path. As a result, impairments caused by scattering surfaces such as contrast reduction, granulation in the image, efficiency reduction and generation of stray light by scattering in undesired directions can be avoided. In particular, thereby the problem of backward irradiated sunlight can be defused.

For this purpose, the imager is provided with a special backlight, can be generated by the required Abstrahlkegel on the chip. This has the advantage that it is possible to dispense with a lens, as is required, for example, in a projector, in that the function of the objective and the image on the virtual screen can be taken over by the optics of the head-up display itself.

For the realization of a stereoscopic head-up display optionally a separation of the image information for left and right eye can be provided in separate eyeboxes. For example, the same mirrors can be used to produce the two eyeboxes. Due to the different emission directions of the two partial images on the display, the two eyeboxes can be operated independently of each other.

According to one embodiment of the approach presented here, the image generation for both eyes can take place by means of only one imager, by switching over between the respective sub-images in a time-sequential manner.

The image forming apparatus may be provided with at least one light beam focusing element disposed in the beam path of the expanded light beam between the expanding element and the light modulating device to focus the expanded light beam onto the light modulating device. A Lichtstrahlfokussierelement may be a lens. By the Lichtstrahlfokussierelement the expanded light beam can be precisely directed to the light modulation unit.

It is advantageous if the light modulation device is designed as LCoS display. Alternatively or additionally, the light modulation device can be designed as a micromirror array. Such an LCoS display or micromirror array can be provided relatively inexpensively and enables a variable deflection of the image beam in several directions.

Optionally, the expansion element can be designed as a scattering surface. Alternatively or additionally, the expansion element can also be designed as a microlens array. A scattering surface can be understood as a reflective or transmitting surface which is designed to fan out a light beam into a larger spatial area. A microlens array can be understood to mean a chip having a plurality of microlenses, by means of which the light beam can be widened. By means of this embodiment too, the beam shaping of the light beam required for backlighting of the light modulation device can be realized at relatively low cost.

The image forming device may also be provided with at least one light trap. In this case, the light modulation device can be designed to direct the image beam and, alternatively or additionally, a light beam incident on the light modulation device into the light trap. A light trap may be understood to mean an element for absorbing a light beam. As a result, the light beam can be dimmed. Furthermore, the light source can be protected against damage by a light beam impinging on the light modulating device by passing the light beam by means of the light modulating device into the light trap instead of back to the light source.

It is also advantageous if the light source, the light modulation device or the expansion element is rotatable or displaceable. As a result, a radiation direction of the image beam can be changed in a simple manner, for example in order to track the image beam of an eye movement.

According to a further embodiment, the imaging device may be provided with a fiber optic having a light input arranged in a beam path of the image beam, also called a fiber input, and designed to generate from the image beam a magnification beam representing an enlargement of the image. A fiber optic may be understood to mean an optical component having a plurality of glass fibers arranged parallel to one another as light guide. The fiber optic may, for example, have the shape of a funnel. In this case, the light entrance of a smaller opening correspond to two opposite openings of the funnel. In this way, the image represented by the image beam can be magnified without deteriorating the display quality of the image.

By means of such a fiber optic, for example, a pre-enlargement of an LCoS display can be realized. The pre-enlargement allows optics of the head-up display to directly enlarge the LCoS chip and image it on the virtual screen.

A major hurdle in the use of small imagers to be imaged directly is the correspondingly high magnification, which should be achieved by the head-up display optics. This can require a high optical effort and tighten the tolerance requirements. Current LCoS chips are available in relatively small chip sizes, such as 0.88 ", and smaller chips are more cost effective than larger variants.

By using fiber optics, the LCoS chip is enlarged in size without having to project the LCoS chip onto a scattering surface located outside the imaging device. Rather, the fiber optic can provide the enlarged image directly to a subsequent head-up display. As a result of the enlarging fiber optics, smaller and therefore more cost-effective LCoS chips can be used, whereby the production costs of the image forming apparatus can be reduced.

These elements can be used to enlarge a microdisplay with very little loss of quality. For conventional use, the fiber optic can be mounted directly on the microdisplay. In this case, the LCoS chip can be backlit accordingly, as described in more detail below.

In order to specifically direct the expanded light beam onto the light modulation device, the image generation device can be provided with at least one corresponding light guide element. A light-guiding element can be, for example, a beam splitter cube or a light guide plate. The light-guiding element can be designed to alternatively or additionally guide the image beam into the light input of the fiber optic. By means of the light-guiding element, an undesired scattering of the light beam or of the image beam can be avoided.

The image generation device may further comprise at least one image beam focusing element which is arranged in the beam path of the image beam between the light modulation device and the fiber optics in order to focus the image beam on the light input. The image-beam focusing element may be a lens. This ensures an accurate and sharp image of the light modulation device on the light entrance.

Furthermore, the image generating device can be provided with at least one further light source for generating a further light beam and at least one further expansion element. The further expansion element can be arranged in a beam path of the further light beam in order to widen the further light beam. In this case, the light modulation device can furthermore be arranged in a beam path of a further light beam which is widened by the further expansion element in order to generate from the expanded further light beam a further image beam representing a further image. In particular, the further image and the image may each represent a stereoscopic field. A stereoscopic field can be understood as a field of a stereo image pair, which creates a spatial impression of depth when viewed. In this case, one field may each be assigned to one eye of a viewer. Such an image forming apparatus enables realization of a stereoscopic head-up display.

The approach proposed here also provides a head-up display with an imaging device according to one of the embodiments described herein.

In this case, the imager, also called a light modulation device, can be an LCoS or DLP chip which is suitably illuminated and imaged directly enlarged by the head-up display optics, whereby the use of a scattering surface can be dispensed with. By means of a suitable backlighting of the imager, a display with stereoscopic functionality can be realized.

• – Durch den Verzicht einer Streufläche werden Auflösungsverluste durch eine Projektion vermieden.
• – Durch die Beschränkung auf Spiegeloptiken beim Aufbau des Head-up-Displays werden Verluste der Bildqualität durch chromatische Aberration vermieden.
• – Die Verwendung eines schnellen DLP-Chips erlaubt einen zeitsequenziellen Bildaufbau der verschiedenen Farben. Das Bild kann ohne Farbfilter erzeugt werden und erreicht somit eine hohe Effizienz.
• – Eine Stereofunktionalität kann unter Verwendung nur eines Imagers erreicht werden, wodurch beispielsweise unerwünschte Doppelbilder, wie sie bei einer Bildüberlagerung mittels eines Strahlteilers auftreten können, vermieden werden.
• – Die hohe Schaltgeschwindigkeit des DLP-Chips ermöglicht zusätzlich zum zeitsequenziellen Umschalten für den Farbbildaufbau ein weiteres zeitsequenzielles Umschalten zwischen den beiden Bildinhalten für linkes und rechtes Auge. Ein Bildaufbau kann beispielsweise mit einer Frequenz von 120 Hz erfolgen.
• – Durch die Verwendung weniger kleiner Komponenten lässt sich das Head-up-Display gut miniaturisieren und die Nachführung von Kopfbewegungen vereinfachen.
• – Durch die Verwendung von MEMS-Komponenten (MEMS = microelectromechanical systems) kann das System sehr robust gegenüber rückwärtiger Sonneneinstrahlung ausgeführt werden.
• – Durch die Verwendung eines DLP-Chips ist auch bei sehr niedrigen und sehr hohen Temperaturen die volle Funktionalität des Head-up-Displays gewährleistet, da ein solcher DLP-Chip in einem weiten Temperaturbereich arbeiten kann.

This offers the following advantages:

• - By eliminating a scattered surface resolution losses are avoided by a projection.
• - The limitation to mirror optics in the construction of the head-up display avoids losses of image quality due to chromatic aberration.
• The use of a fast DLP chip allows a time-sequential image build-up of the different colors. The image can be generated without color filter and thus achieves high efficiency.
• Stereo functionality can be achieved using only one imager, thus avoiding, for example, unwanted double images, such as can occur in image superimposition by means of a beam splitter.
• The high switching speed of the DLP chip allows, in addition to the time-sequential switching for the color image structure, a further time-sequential switching between the two image contents for left and right eye. An image structure can be done, for example, with a frequency of 120 Hz.
• - By using fewer small components, the head-up display can be well miniaturized and the tracking of head movements easier.
• - By using MEMS components (MEMS = microelectromechanical systems), the system can be made very robust against rearward solar radiation.
• - By using a DLP chip, the full functionality of the head-up display is guaranteed even at very low and very high temperatures, since such a DLP chip can operate in a wide temperature range.

Finally, the approach described herein provides a method for generating an image for a head-up display, the method comprising the steps of:
Irradiating an expanded light beam to a light modulation device to illuminate the light modulation device from multiple angles simultaneously; and
Generating an image beam representing an image from the expanded light beam through the light modulation device.

The approach presented here also creates a control unit which is designed to execute, to control or to implement the steps of a variant of a method presented here in corresponding devices. 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.

In the present case, a control device can be understood as meaning an electrical device which processes sensor signals and outputs control and / or data signals in dependence thereon. The control unit may have an interface, which may be formed in hardware and / or software. In the case of a hardware-based design, the interfaces can be part of a so-called system ASIC, for example, which contains various functions of the control unit. However, it is also possible that the interfaces are their own integrated circuits or at least partially consist of discrete components. In a software training, the interfaces may be software modules that are present, for example, on a microcontroller in addition to other software modules.

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.

The approach presented here will be explained in more detail below with reference to the accompanying drawings. Show it:

1 a schematic representation of a vehicle with a head-up display according to an embodiment of the present invention;

2 a simulation of a beam path in a head-up display with a DLP chip according to an embodiment of the present invention;

3a . 3b . 3c Charts for calculating spot sizes from different positions within an eyebox;

4 a schematic representation of an illuminated light modulation device according to an embodiment of the present invention;

5 a schematic representation of a vehicle with a head-up display according to an embodiment of the present invention;

6 a simulation of a beam path in a head-up display with a LCoS chip according to an embodiment of the present invention;

7 a simulation of a beam path in a vehicle-integrated head-up display with a LCoS chip according to an embodiment of the present invention;

8th a schematic representation of a space for a head-up display according to an embodiment of the present invention;

9 a schematic representation of a vehicle with a stereoscopic head-up display according to an embodiment of the present invention;

10a . 10b schematic illustrations of an image forming apparatus according to various embodiments of the present invention;

11 a simulation of a beam path in a stereoscopic head-up display according to an embodiment of the present invention;

12 a simulation of a beam path in a stereoscopic head-up display according to an embodiment of the present invention;

13 a diagram illustrating an image generation according to an embodiment of the present invention;

14 a simulation of a beam path in a stereoscopic head-up display according to an embodiment of the present invention;

15a . 15b Simulations of a ray trajectory in a stereoscopic head-up display according to an embodiment of the present invention;

16 a schematic representation of a stereoscopic head-up display with a LCoS chip according to an embodiment of the present invention;

17 a schematic representation of an image forming apparatus with a fiber optic according to an embodiment of the present invention;

18 a schematic representation of an image forming apparatus with a fiber optic according to an embodiment of the present invention;

19 a flowchart of a method for generating an image for a head-up display according to an embodiment of the present invention; and

20 a block diagram of a controller for performing a method according to an embodiment of the present invention.

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, with a repeated description of these elements is omitted.

1 shows a schematic representation of a vehicle 100 with a head-up display 102 according to an embodiment of the present invention. The head-up display 102 comprises an image forming device 104 , also called an imaging unit. In a housing of the image forming apparatus 106 are a source of light 108 , an expansion element 110 and a light modulation device 112 arranged. The light source 108 is designed to receive a beam of light 114 to generate and on in a beam path of the light beam 114 located expansion element 110 to steer. Here is the expansion element 110 between the light source 108 and the light modulation device 112 arranged. Exemplary is the light source 108 realized as LED lighting with one or more LEDs for blue, red and green light. The expansion element 110 is trained to get out of the light beam 114 an expanded light beam 116 to produce with an enlarged opening angle. The light modulation device 112 is so in a beam path of the expanded light beam 116 arranged them from the expanded light beam 116 illuminated from several angles simultaneously.

The light modulation device 112 , here a DLP chip, also called DLP imager, is trained to get out of the widened light beam 116 one a virtual picture 120 representing image beam 122 to create. In 1 reflects the light modulation device 112 the picture beam 122 directly on a mirror 124 a head-up display optics. At the mirror 124 it is according to this embodiment, a curved main mirror of the head-up display 102 , The mirror 124 is trained to image the picture 122 on a windshield 126 of the vehicle 100 to project. By means of the windshield 126 becomes the image beam 122 further into an eyebox 128 a driver 130 directed the virtual picture 120 behind the Windshield 126 on a virtual screen at a distance VID between the virtual screen and the eyebox 128 , also called virtual screen distance, perceives.

Optionally, in the beam path of the expanded light beam 116 between the light modulation device 112 and the expansion element 110 a Lichtstrahlfokussierelement 132 arranged, which is shown here as a lens. The light beam focusing element 132 is formed to the expanded light beam 116 on the active surface of the light modulation device 112 to focus and thus to ensure a homogeneous illumination of the active surface.

In addition, the in 1 shown image forming apparatus 106 with a light trap 134 intended. In this case, the light modulation device 112 formed to a radiation angle of the image beam 122 to vary such that the image beam 122 either on the mirror 124 meets or in the light trap 134 falls.

By means of the light trap 134 can also prevent one from the windshield 126 over the mirror 124 on the light modulation device 112 projected light beam, in particular sun rays, on the light source 108 is reflected by the light modulation device 112 this ray of light into the light trap 134 distracting. This can cause overheating of the light source 108 be avoided.

2 shows a simulation of a beam path in a head-up display 102 out 1 with a DLP chip 112 according to an embodiment of the present invention. The simulation of the display system 102 is performed in the optics simulation program Zemax. The head-up display 102 is trained to be a small imager in the form of the DLP chip 112 directly represent. This is indicated by the head-up display 102 four free-form mirrors, for example 202 on. The light path is simulated starting from the virtual image. The use of a light modulator in the form of the small imager 112 with high magnification on the virtual screen places high demands on the imaging optics. Due to the high number of freeform elements, in 2 the four freeform mirrors 202 , this claim can be fulfilled.

In order to improve the image quality, other elements such as free-form lenses or additional aspherical lenses can also be used. At the in 2 The optical design shown has been deliberately omitted on these elements to avoid chromatic aberrations and back reflections on non-fully anti-reflective surfaces.

The design is based on the following parameters by way of example: Virtual screen distance 5 m Field of view 9 ° by 4.5 ° Eyeboxgröße 120 mm by 60 mm DLP chip size 1"

These values are particularly suitable as presets for an autostereoscopic head-up display. This in 2 However, the design shown can also be used for other screen distances of about 3 m.

The design achieves an average spot size of 9.45 μm with an aperture of 8 mm, for example. The aperture is the diameter of a viewer's eye from the eyebox. The spot size is at the location of the display, ie the micromirror array in the form of the DLP chip 112 , certainly. It should as far as possible a spot size in the order of pixels of the display, in a DLP chip, for example 10 microns, can be achieved.

The 3a to 3c show diagrams for calculating spot sizes from different positions within an eyebox 1 , In this case, a position in the y-direction is shown on a y-axis and a position in the x-direction on an x-axis. As can be seen, the spot sizes in all eyebox positions are within the target range defined above.

The spot size evaluation results shown are determined using the Global Unified Tool from Bosch Car Multimedia. The in 3a plot shown describes the calculation from the eye position on the left edge of the eyebox, 3b the calculation from the middle of the eyebox and 3c the calculation on the right edge of the eyebox. The image coordinates correspond to the coordinates of the virtual image. Each scale indicates an RMS spot size in microns on the display. Display here refers to the light modulation device.

The simulation takes place backwards from the virtual image. That is, rays are simulated starting from a point of the virtual image (coordinates in the plot). These are focused on the display (spot size from the plot). A point viewed from the virtual screen from the center of the screen (center of the plots), viewed from the center of the eyebox (middle plot), reaches a spot size of about 6 μm on the display. Experience shows that the quality of the image from the display to the virtual image achieved in the actual head-up display is sufficient because the simulated spot size is below the dimension of a pixel of the display.

Current DLP chips are available in sizes up to 0.95 "and have a tilt angle of +/- 12 °, and future DLP chips can have tilt angles of +/- 16 ° and tilt directions across different axes of the chip It is to be expected that high-resolution applications will lead to the availability of larger DLP chips in view of the minimum attainable micromirror sizes on the chips.

4 shows a schematic representation of an illuminated light modulation device 112 out 1 according to an embodiment of the present invention. The light source 108 here is trained to the DLP chip 112 to illuminate off-axis. The DLP chip 112 is designed to be that of the light source 108 emitted light rays to tilt by a tilt angle of +/- 12 °, ie by a total of 24 °. This results in one of the DLP chip 112 reflected beam a maximum angle change of 48 °. Using this angle change, the light beams can either be used as useful light on the head-up display mirror 124 or as low beam in the light trap 134 be steered.

A calculation of the Lagrangian invariant using the above-mentioned parameters gives a full opening angle of 54.1 ° in the display transverse direction and 22.5 ° in the display longitudinal direction. One from the chip 112 outgoing light cone can be deflected with these angles over the small angle around the realized by the micromirrors angle of 48 °. This will deflect the full cone out of its original direction and into the light trap 134 directed. For current DLP chips with diagonal folding direction, the angle range to be folded is between the two values of 54.1 ° and 22.5 °.

5 shows a vehicle 100 with a head-up display 102 out 1 according to an embodiment of the present invention. In contrast to 1 has the in 5 shown head-up display 102 an LCoS chip instead of a DLP chip as a light modulation device 112 on.

According to this embodiment, the imager unit 106 three LEDs in the primary colors red, green and blue. The imager unit 106 is designed to overlay the three primary colors. After that, the light is transmitted through an optical element 110 widened. Such an expanding element 110 is realized for example as a scattering surface, refractive microlens array or hologram. Because the scattered area 110 Here only serves to form the backlight and the actual image content only at the imager, ie on the LCoS chip 112 , is built, the use of the scattering surface goes 112 is not associated with a deterioration in image quality, as may be the case with projection-based solutions, for example.

After the expansion of the light, the area becomes 110 by means of an optic 132 to the actual imager 112 displayed. This will be the imager 112 unlike common projectors with different angles illuminated simultaneously. Through the illustration of the expanding element 110 become point light sources on the LCoS chip 112 displayed. By this arrangement, despite the non-scattering property of the imager 112 a radiation behavior in different directions for each pixel are generated. This is the imager 112 directly viewable as a display and can by a subsequent head-up display optics, here by the mirror 124 to be imaged.

6 shows a simulation of a beam path in a head-up display 102 out 5 with an LCoS chip 112 according to an embodiment of the present invention. Unlike the in 2 shown simulation is in the in 6 Simulation shown an LCoS chip instead of a DLP chip as light modulation device 112 used.

7 shows a simulation of a beam path in a vehicle 100 integrated head-up display 102 with an LCoS chip 112 according to an embodiment of the present invention. In the vehicle 100 it can be in the 5 shown vehicle act. In contrast to 6 is the head-up display 102 here with the additional lighting optics 132 for the LCoS chip 112 shown.

8th shows a schematic representation of a space for a head-up display 102 according to an embodiment of the present invention. In 8th is a fitting in the CAD program Rhino space for the concept 7 shown. The fitted construction volume is for example 9.6 l. Thus, by this concept, installation spaces of less than 10 l can be achieved. The chip is displayed on four free-form mirrors and the windshield on the virtual screen. The characteristics of the head-up display design correspond to the parameters mentioned above, with the difference that the size of the LCoS chip is 0.88 ". This results in an average spot size of 16.4 μm.

9 shows a schematic representation of a vehicle 100 out 1 with a stereoscopic head-up display 102 according to an embodiment of the present invention. In contrast to 1 has the in 9 shown image forming apparatus 106 one from the light source 108 separate further light source 902 on. The other light source 902 is designed to receive another beam of light 904 to create. Another expansion element 906 is formed to the other light beam 904 expand and a correspondingly expanded further light beam 908 on the DLP chip 112 to steer. Here is the DLP chip 112 designed to come out of the expanded further light beam 908 another virtual picture 910 representing another image beam 912 to create.

According to this embodiment, the image forming apparatus is 106 trained to get the more picture 910 and the picture 120 ever to produce as a stereoscopic partial image. Here is the DLP chip 112 trained to by means of the mirror 124 and the windshield 126 the further image beam 912 in a right eye of the driver 130 assigned right eyebox 914 and the image beam 122 in a driver's left eye 130 assigned left eyebox 916 to steer. The driver 130 can thus the two fields 108 . 910 perceive as a single three-dimensional image.

To a stereoscopic head-up display 102 To realize, according to one embodiment, two separate backlight units can be used. This allows two separate eyeboxes 914 . 916 Illuminated separately for left and right eye.

To the rays of light the Eyeboxes 914 . 916 nachzuführen, as required for example in head movements, the backlight units can be displaced. Alternatively or additionally, the tracking can be achieved by slightly tilting the DLP chip 112 be realized.

For example, in the realization of two narrow eyeboxes 914 . 916 at the eye positions two strips corresponding to the eye positions, each having a width of about 20 mm of a total width of 120 mm used. This results in a realistically used width of about 85 mm. This area, which is narrow compared to an entire Eyebox, leads to smaller angular openings of the beam cone on the display 112 and, with a suitable tracking mechanism, facilitates the dimming of the light by the DLP chip 112 at the picture construction.

The 10a and 10b show schematic representations of an image forming apparatus 106 out 9 according to various embodiments of the present invention. In 10a is the entire image forming apparatus 106 rotatable. Thereby, the light modulation device becomes 112 , here the DLP chip, together with the two lighting units 108 . 902 turned. In 10b is only the light modulation device 112 rotatable. Alternatively, the image forming apparatus 106 or the light modulation device 112 be additionally displaceable.

Alternatively or additionally, the expansion element 110 and the further expansion element 906 be slidable or rotatable. The lighting units 108 . 902 may also be independently displaceable or rotatable in the image forming apparatus 106 be arranged.

11 shows a simulation of a beam path in a stereoscopic head-up display 102 out 9 according to an embodiment of the present invention. The head-up display 102 is here as an autostereoscopic head-up display with a small DLP imager 112 executed. The figure illustrates how the light emitted by a light surface passes through the DLP chip 112 can be distracted and led into the optics.

12 shows a simulation of a beam path in a stereoscopic head-up display 102 according to an embodiment of the present invention. In 12 are the in 11 shown components shown in detail. The lighting units 108 . 902 , shown here as illuminated areas, illuminate the DLP chip 112 each with a spherical concave mirror 1200 , The two are homogeneous luminous areas 108 . 902 designed to produce light cone with a defined by an angle α width and in certain directions. Such a luminous area can be generated by means of a microlens array or a special scattering surface, such as a holographic scattering surface.

The DLP chip 112 each has 12 ° folded micromirrors, the light in the direction of a first free-form mirror 1202 reflect. The light sources 108 . 902 can be realized as LEDs or lasers in RGB colors. For the color representation, the light sources 108 . 902 time sequential with the DLP chip 112 synchronized. In this case, the switching speeds are fast enough to allow the image structure and the switching between the image contents of the left and right eye, as described below with reference to FIG 13 shown.

13 shows a diagram illustrating an image generation according to an embodiment of the present invention. On a y-axis, an operating state of a light source is shown, wherein 0 corresponds to an off and 1 a switched-state of the light source. An x-axis shows a time course in milliseconds. Within a time interval of 8.3 ms (120 Hz), the colors red, green and blue of the two partial images are switched on one after the other. Within the plateaus, the DLP chip generates the partial image of the corresponding color for the corresponding eye. In this case, a time interval L is assigned to a left eye, a time interval R to a right eye and a time interval G to an entire image structure.

14 shows a simulation of a beam path in a stereoscopic head-up display 102 according to an embodiment of the present invention. The simulation shows two variants, such as the light depending on the tilt angle of the micromirrors on the DLP chip 112 is reflected. Unlike the 11 and 12 Here is the case illustrated in which the micromirrors of the DLP chip 112 Fold to -12 ° to put the light in the light trap 134 to steer. The simulation shows that on the DLP chip 112 incident light rays as well as the light trap 134 guided dimmed light beams spatially on the first free-form mirror 1202 pass. At a tilt angle of + 12 °, the light is used for imaging and the first free-form mirror 1202 directed.

The 15a and 15b show simulations of a beam path in a stereoscopic head-up display 102 out 9 according to an embodiment of the present invention. Currently available DLP chips typically have diagonal foldable micromirrors. As a result, a lighting and dimming across the diagonal is necessary, as in the 15a and 15b shown. The design shown here also allows dimming and thus the operation with currently available 0.95 "-DLP chips in the orthogonal structure.

15a shows the angle situation when lighting the DLP chip 112 with a folding angle over the chip diagonal. 15b shows the reflected rays for the image structure and the light trap 134 (similar 7 ). The simulated beams fill the large total box of 120 mm width. In stereo, only two sections of it are used, which correspond to the eyebox positions for the two eyes.

As a small imager alternatively a LCoS display or another microdisplay can be used. Advantageously, can be dispensed with the use of a LCoS display on a light trap.

16 shows a schematic representation of a stereoscopic head-up display 102 out 9 with an LCoS chip 112 according to an embodiment of the present invention. With a used width of the total box of 85 mm, ie two eyeboxes of 20 mm width each, arranged in a distance corresponding to a distance of 65 mm, results according to the Lagrangian invariant half an opening angle of 19.2 ° in the direction of width. The LCoS chip 112 So should allow for this approximation, an opening cone of about 40 °.

This dimension is for example with a polarization beam splitter cube 1600 Also known as PolCube. To track the eyeboxes, the LCoS chip 112 rotated together with its lighting unit (not shown here), reducing the light cone for the eyeboxes on the first mirror 124 of the head-up display 102 be scanned. For this, the image forming apparatus 106 be made rotatable. This takes advantage of the full design range of the total box of 120 mm width.

For color effects and different efficiencies for the different beam angles of the LCoS chip 112 To avoid, for example, a so-called wire-grid beam splitter can be used, in which the polarization-dependent optical function is achieved by small metal strips. This technology has the advantage of being largely independent of angle and color.

17 shows a schematic representation of an image forming apparatus 106 out 5 with a fiber optic 1700 according to an embodiment of the present invention. Shown is an illustration of the LCoS chip 112 on a fiber entrance 1702 the fiber optic 1700 which can also be called a light entrance. On the LCoS chip 112 is a polarization-dependent beam splitter cube 1704 arranged as a light-guiding element. The beam splitter cube 1704 is designed to light on the LCoS chip 112 to lead.

The light of active pixels is rotated there in its polarization direction and reflected. The image content is built up by not turning the light of black pixels and thus after reflection on the LCoS chip 112 is reflected back into the light source (not shown here). The reflected useful light passes through the beam splitter cube 1704 and meets an imaging optics 1706 , also called Bildstrahlfokussierelement. The imaging optics 1706 is shown here as a lens. The backlighting produces a certain beam angle, which is via the imaging optics 1706 is shown. The imaging optics 1706 is designed to handle the LCoS chip 112 on a real picture directly at the fiber entrance 1702 map. The fiber optics 1700 is designed to enlarge this real image and at the fiber entrance 1702 opposite fiber output 1708 to provide the head-up display optics for further magnification.

Because the LCoS chip 112 itself does not scatter, it can be suitably backlit by means of a widening element, such as in the form of a scattered surface, or by a holographic backlight, so that beam cone of required form emanate from him.

18 shows a schematic representation of an image forming apparatus 106 with a fiber optic 1700 according to an embodiment of the present invention. In contrast to 18 is here between the light modulation device 112 and the fiber entrance 1702 a light guide plate 1704 arranged as a light-guiding element. In this case, the light modulation device 112 , the light guide plate 1704 and the fiber optics 1700 be combined in a layered composite.

Through the light guide plate 1704 a laterally coupled-in LCoS backlighting is made possible. The light modulation device is in the form of the LCoS chip 112 laterally over the flat light guide plate 1704 illuminated. The laterally coupled-in light is polarized and becomes inside the light guide plate 1704 directed. The light meets the staggered construction of small polar mirrors 1800 as mirror elements within the light guide plate 1704 , The mirror elements 1800 are trained to move a portion of the light down to the LCoS chip 112 reflect. There, the image content is generated by rotating and mirroring the light in its polarization. The mirrored light now passes through the mirror elements 1800 and gets into the fiber optic 1700 coupled.

Due to the thin structure of such a lighting unit, the fiber optics 1700 very close to the LCoS chip 112 be placed to enlarge it and the enlarged image on the fiber output 1708 to provide.

The in the 17 and 18 illustrated imager concepts are in principle also suitable for the realization of an autostereoscopic head-up display. For this purpose, a separation of partial images for left and right eye can be provided. The switching speed of the LCoS chip 112 is fast enough to build up the two image contents in a color sequential manner.

A spatial separation of the light beams can be realized for example by a sequentially connected backlight, which can switch between two slightly different illumination angles.

19 shows a flowchart of a method 1900 for generating an image for a head-up display according to an embodiment of the present invention. It is in one step 1902 an expanded light beam is irradiated to a light modulating means to illuminate the light modulating means from plural angles simultaneously. In one step 1904 Finally, an image beam representing the image is generated by the light modulation device from the expanded light beam.

According to one exemplary embodiment, a micromirror array, for example a DLP chip, is virtually imaged by means of a head-up display optic. Since the DLP chip itself does not scatter, an adapted backlighting for beam shaping is provided. In this case, a homogeneously illuminating surface is imaged onto the micromirror array by means of a further optical system. Since this image serves for backlighting, it has a high tolerance and can be realized, for example, by simple spherical mirrors.

20 shows a block diagram of a controller 2000 for performing a method according to an embodiment of the present invention. The control unit 2000 has a radiating unit 2002 which is configured to cause the irradiation of an expanded light beam on a light modulation device to illuminate a light modulation device from several angles simultaneously. This can be done by the radiating unit 2002 with the example in the 1 and 5 shown light source 108 be connected. Alternatively or additionally, the Ausstrahleinheit 2002 with the likewise in the 1 and 5 shown expansion element 110 be connected, in particular if the expansion element 110 rotatable or displaceable or designed as a controllable microlens array.

Furthermore, the control unit includes 2000 a generating unit 2004 adapted to drive the light modulation device in response to the emission of the expanded light beam such that the light modulation device generates an image beam representing the image from the expanded light beam.

The embodiments described and shown in the figures are chosen only by way of example. Different embodiments may be combined together or in relation to individual features. Also, an embodiment can be supplemented by features of another embodiment.

Furthermore, the method steps presented here can be repeated as well as executed in a sequence other than that described.

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)

Image forming apparatus ( 106 ) for a head-up display ( 102 ), the image forming apparatus ( 106 ) has the following features: at least one light source ( 108 ) for generating a light beam ( 114 ); at least one expansion element ( 110 ), which in a beam path of the light beam ( 114 ) is arranged to the light beam ( 114 ) expand; and at least one light modulation device ( 112 ) in a beam path of one of the expansion element ( 110 ) expanded light beam ( 116 ) is arranged to move from the expanded light beam ( 116 ) from a plurality of angles to be illuminated simultaneously, and which is adapted to from the expanded light beam ( 116 ) a picture ( 108 ) ( 122 ) to create. Image forming apparatus ( 106 ) according to claim 1, characterized by at least one Lichtstrahlfokussierelement ( 132 ), which in the beam path of the expanded light beam ( 116 ) between the expansion element ( 110 ) and the light modulation device ( 112 ) is arranged to the expanded light beam ( 116 ) to the light modulation device ( 112 ) to focus. Image forming apparatus ( 106 ) according to one of the preceding claims, characterized in that the light modulation device ( 112 ) is designed as an LCoS display and / or as a micromirror array. Image forming apparatus ( 106 ) according to one of the preceding claims, characterized in that the expansion element ( 110 ) is designed as a scattering surface and / or as a microlens array. Image forming apparatus ( 106 ) according to one of the preceding claims, characterized by at least one light trap ( 134 ), wherein the light modulation device ( 112 ) is adapted to the image beam ( 122 ) and / or one on the light modulation device ( 112 ) incident light beam in the light trap ( 134 ) to steer. Image forming apparatus ( 106 ) according to one of the preceding claims, characterized in that the light source ( 108 ) and / or the light modulation device ( 112 ) and / or the expansion element ( 110 ) is rotatable and / or displaceable to a radiation direction of the image beam ( 122 ) to change. Image forming apparatus ( 106 ) according to one of the preceding claims, characterized by a fiber optic ( 1700 ), one in a beam path of the image beam ( 122 ) arranged light entrance ( 1702 ) and is adapted to from the image beam ( 122 ) to generate a magnification beam representing an enlargement of the image. Image forming apparatus ( 106 ) according to claim 7, characterized by at least one light-guiding element ( 1600 ; 1704 ), which is formed around the expanded light beam ( 116 ) to the light modulation device ( 112 ) and / or the image beam ( 122 ) on the light entrance ( 1702 ) to steer. Image forming apparatus ( 106 ) according to claim 7 or 8, characterized by at least one image-beam focusing element ( 1706 ), which in the beam path of the image beam ( 122 ) between the light modulation device ( 112 ) and the fiber optics ( 1700 ) is arranged to the image beam ( 122 ) on the light entrance ( 1702 ) to focus. Image forming apparatus ( 106 ) according to one of the preceding claims, characterized by at least one further light source ( 902 ) for generating a further light beam ( 904 ) and at least one further expansion element ( 906 ), which in a beam path of the further light beam ( 904 ) is arranged to the other light beam ( 904 ), wherein the light modulation device ( 112 ) further in a beam path of one of the further expansion element ( 906 ) expanded further light beam ( 908 ) is arranged to from the expanded further light beam ( 908 ) take another picture ( 910 ) representing another image beam ( 912 ), in particular where the further image ( 910 ) and the picture ( 108 ) each represent a stereoscopic field. Head-Up Display ( 102 ) with an image forming device ( 106 ) according to one of the preceding claims. Procedure ( 1900 ) for generating an image ( 108 ) for a head-up display ( 102 ), the process ( 1900 ) comprises the following steps: broadcasting ( 1902 ) of an expanded light beam ( 116 ) to a light modulation device ( 112 ) to the light modulation device ( 112 ) from several angles at the same time; and generating ( 1904 ) of a picture ( 108 ) representing the image ( 122 ) from the expanded light beam ( 116 ) by the light modulation device ( 112 ). Control unit ( 2000 ), which is designed to handle all steps of a process ( 1900 ) according to claim 12. Computer program adapted to perform all steps of a procedure ( 1900 ) according to claim 12. A machine-readable storage medium having a computer program stored thereon according to claim 14.

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