DE102016223338B3 - Head-up display and method for controlling a head-up display - Google Patents

Abstract

The present invention relates to a head-up display for a vehicle. It has a display unit (1) for generating different images (B (α, β)) for different viewing angles (φ (α, β)), a deflection unit (2) for deflecting the different images (B (α, β) ) of the display unit (1) emitting light beams at different viewing angles (φ (α, β)), a mirror unit (3, 31) for superimposing the light beams emanating from the display unit (1) with other light beams. The display unit (1) is designed to generate the different images (B (α, β)) one after the other, and the deflection unit (2) is designed to divert the light beams successively into different viewing angles (φ (α, β)) ,

Description

The present invention relates to a head-up display for a vehicle. In this case, information for the driver or another observer is projected on the windshield mirrored in the eye.

From the DE 10 2009 054 232 A1 a head-up display is known with a display unit for generating different images for different viewing angles, with a deflection unit for deflecting the emanating from the different images of the display unit light beams in different viewing angles, and with a mirror unit for superimposing the emanating from the display light beams other rays of light. The known head-up display has a grid of lens elements, a so-called microlens array, which is arranged between the display unit and a windscreen designed as a mirror unit. This head-up display works according to the so-called "integral imaging principle". A disadvantage of the known solution is to be considered that back reflections occur on the grid of lens elements in sunlight, which can not be suppressed by conventional anti-reflex measures so far that they do not visibly affect the virtual image. The "Integral Imaging Principle" requires a very high number of pixels and pixel density of the electro-optical imager, the display unit, for the desired performance of a head-up display.

According to the invention, instead of a grid of lens elements, a lighting unit with a time-varying beam angle is provided. The display unit is designed to generate the different images in temporal succession and the deflection unit is designed to divert the light beams one after the other into different viewing angles. This has the advantage that no microlens array is required, which could cause disturbing reflections of the ambient light. Particularly disturbing are the reflections caused by the uneven surface of the microlenses. Another advantage is that a lower number of pixels on the display unit is sufficient, whereby a cost-effective display unit can be used. Nevertheless, a high spatial resolution is achieved, for example, at four different viewing angles, the fourfold resolution is achieved by temporal multiplexing. Instead of every fourth pixel for one viewing angle, each pixel is then used for each viewing angle. Thus, the fourfold resolution is achieved. Alternatively, one quarter of the pixels are sufficient if the resolution remains the same.

At 9 or 16 different viewing angles, 1/9 or 1/16 of the number of pixels is sufficient. If, for example, a fourfold resolution is to be achieved here, then 4/9 or 4/16 of the number of pixels are needed. Thus, a smaller number of pixels is sufficient, namely 4/9 or 1/4 of the number of pixels required when using microlenses. The required higher alternating frequency of the images on the display unit and the alternating frequency of the deflection unit, for example 100 Hz or 400 Hz instead of 25 Hz, can be achieved with currently available technology without much effort. The display unit is preferably a self-luminous display, a radiating display or in general a display with a matrix structure for displaying images consisting of many pixels. The deflection unit is for example a so-called "digital micromirror device", also called DMD, which is arranged in the beam path after the self-luminous display, with translucent display after the light source and before or after the translucent display. The deflection unit can also be designed as a so-called "Spatial Light Modulator", also called SLM, for example as a liquid crystal element whose individual cells form a switchable differently inclined and differently oriented prism structure. The deflection unit can also be designed as a holographic element. In the simplest case, the mirror unit is the windshield of the vehicle or a so-called combiner, a transparent pane arranged in front of the windshield, which reflects the light beams coming from the display unit in the direction of the driver - or in general towards the viewer.

According to the invention, it is provided that the display unit is irradiated by a light source, and the deflection unit is arranged between the light source and the display unit. This has the advantage that reflections of the ambient light at the deflection unit are greatly reduced, since the ambient light has to pass through the display unit twice and is greatly attenuated.

Advantageously, the light source and deflection unit are formed as one unit. In this case, both the deflection unit and the light source can be designed by themselves or both in combination so that the desired radiation angles are achieved. A light source which is designed to generate light which is emitted in temporal succession at different emission angles is also within the scope of the invention.

Advantageously, the light source has a matrix structure consisting of light elements. The lighting elements are advantageously juxtaposed LED elements. These are tested and available at low cost. But others in Matrix form arranged light sources are useful here. Depending on which luminous element of the matrix structure is switched on, the light generated thereby leaves the deflection unit with a different emission angle. The deflection unit is in the simplest case a fixed lens which covers the entire matrix of luminous elements.

According to a variant, the deflection unit is a microlens matrix. In the case of the microlens element, a lens covers a plurality of luminous elements of the matrix structure; depending on the desired emission angle, that luminous element of the field which corresponds to the corresponding emission angle is switched on. Here, a plurality of uniformly distributed over the matrix structure light elements are each turned on simultaneously. This has the advantage that the waste heat arising during operation of the luminous elements is distributed uniformly over the light source. This advantageously contributes to stable operation and long life.

It is envisaged that the microlens array has nested prism elements. This has the advantage that with each prism element a larger area with a constant deflection angle is present than with pure lens elements. As a result, the lighting elements can also be larger in area without causing excessive deflection of the deflection angle. It comes with a smaller number of lighting elements, the display element is cheaper and less driving lines for the lighting elements are needed, the structure of the circuit is easier. As light elements here preferably light sources are used with sufficiently directed radiation characteristics. For example, laser diodes have such directional characteristics. Instead of prism elements which have a simple construction, it is also possible to use other optical elements, such as lenses, which are disassembled into elements and which are arranged alternately with elements of adjacent optical elements.

Advantageously, a head-up display according to the invention has a position sensor which detects the head or eye position of the vehicle driver or another observer. The corresponding position signal is sent to a control unit, which calculates from there the viewing angles required for the corresponding position. Only for these viewing angles images are generated and forwarded to the display unit. The deflection unit deflects only in these viewing angles. Instead of all provided in the device deflection angle so only those - optimally only two - deflection angle and associated images are generated, which correspond to the current position of the eyes or the head of the viewer. This has the advantage that a large reduction in the number of images to be displayed per unit time and the deflection angle to be generated is achieved. For example, instead of creating and displaying images for thirty different viewing angles, two images are generated for the two viewing angles corresponding to the detected eye position. If a certain deviation of the eye positions is to be compensated, it is provided to use four or six or another small number of, for example, thirty possible deflection angles corresponding to the currently detected eye position. Thus, a lower repetition frequency of the display unit is sufficient, a more cost-effective display unit can be used. For the lower number of images correspondingly a lower calculation effort. Head position detectors are already present in many vehicles for other reasons. These can be shared, whereby no or only a small additional effort is required for the implementation.

According to one embodiment of the invention, the position sensor is an eye position detector. Since the position of the eyes is detected, the deflection angles to be set and the images to be generated can be more accurately determined than in head position detection. The probability of irritation in the viewer is thereby further reduced. If the position of each eye is determined, then the viewing angles are optimally adjusted even to different eye distances.

Alternatively or in addition to the position detector, an adjustment element for manually adjusting the viewing angle is provided by the viewer. This is a cost effective solution if no position detector is present or for some reason can not be used. The latter is the case, for example, if the position detector is misted due to high humidity, or if reliable position detection can not be ensured for other reasons. The adjusting means can also be used advantageously for presetting, for example, different eye distances for different viewers. The position detection can provide in this case with viewer-specific information adapted to the respective viewer eye positions.

A method according to the invention consists in calculating images intended for different viewing angles, sequentially controlling the display unit with the calculated images, and controlling the deflection unit in a coordinated manner with the associated angle information. This has the advantages stated for the device claims.

Advantageously, the control for a sequence takes place little from each other distinctive viewing angles. This has the advantage that, in particular in the case of a deflection unit with moving parts, only slight change in position must take place from one position to the next, so that the system can be operated without great mechanical jumps. The sequence is, for example, a line-by-line passing through an n × n matrix, or a spiraling through of a corresponding matrix from outside to inside, where only a jump occurs at the end from inside to outside, or the like.

Alternatively, the control takes place with a sequence of viewing angles which differ greatly from one another. This has the advantage that closely adjacent viewing angles are generated more staggered in time. An observer who changes between adjacent viewing angles, thus gets no temporally too close to each other angularly offset images shown, there is only a slight risk of irritation. A corresponding sequence can be effected for example by the so-called Rösselsprungverfahren or another method in which at least one column or row is skipped from one to the next point in the sequence. For an n × n matrix of large n, the sum of the rows and columns skipped to the next point in the sequence is greater than n / 2.

According to the invention, it is provided to determine information about the position of the eyes of the observer, and to carry out the calculation of the images and the control of the display unit and of the deflection unit only for the deflection angle calculated from the determined position signal. This has the advantage that in the best case, only two viewing angles and the associated images need to be calculated and displayed. This simplifies the process considerably. Further advantages correspond to those already described for the device claims. The information is determined, for example, by means of a head position detector, an eye position detector or an adjusting element.

Further advantages and embodiments of the invention are also given in the following description of exemplary embodiments. Showing:

1 Head-up display according to a first embodiment

2 Head-up display according to a second embodiment

3 Detail of a deflection unit with microlenses

4 Detail of a deflection unit with microprisms

5 Detail of a deflection unit with a grid of optical components

6 flow chart

7 control sequence

1 shows an inventive head-up display, which is a display unit 1 a distraction unit 2 , a mirror unit 3 and a control unit 4 having. A light source 5 generates light which is transformed into a two-dimensional illumination matrix 21 the deflection unit 2 is directed. Above this there is a deflection element designed as a two-dimensional matrix 22 , It consists of microprisms here 23 , A condenser lens 24 derives this from the lighting matrix 21 generated and by the deflector 22 in a certain angular direction deflected light on the display unit 1 , The display unit 1 creates a two-dimensional array of pixels that together form an image. It is from the light coming from the deflection unit 2 comes, shines through. The light that the display unit 1 has happened is from the mirror unit 3 Here's a windshield 31 a motor vehicle is reflected. The reflected light as well as ambient light passing through the windshield 31 falls, get into the eye 61 of the driver. The control unit 4 generates an image B (α, β) to be superimposed on the ambient light for each viewing angle φ (α, β). The corresponding information is sent to the display unit 1 directed. The corresponding angle φ (α, β) is sent to the deflection unit 2 directed. This then adjusts the deflection angle φ (α, β) which matches the image B (α, β).

The image B (α, β) has in the illustrated example vehicle state information F, environmental information U and navigation information N. The vehicle state information F come, for example, from a tacho indicated here 41 , The environmental information U comes from a camera indicated here 42 , the navigation information N from a navigation device indicated here 43 , These become the control unit 4 supplied and processed by this.

A position sensor 64 detects the position of the eyes 61 the observer, who can be both the driver and another observer. The detected position signal PS is forwarded to the control unit. An adjustment element 65 Allows manual adjustment of the viewing angle, either instead of using a position sensor 64 or as a supplement to this, for example, to consider a different for each viewer eye distance. The adjusting 64 may be both a physical adjustment such as knob or slider, as well as, for example, a displayable and operable on a touch screen element.

The detected adjustment signal JS is also sent to the control unit 4 directed.

From the light source 5 For example, fiber optics go 51 out in the two-dimensional illumination matrix 21 end up. The light guides 51 are preferably switchable, so the different elements of the illumination matrix 21 controlled switched on and off. Instead of the illustrated light source 5 can also be an existing LED elements lighting matrix 21 be provided. The LEDs are then driven via control lines, which instead of the light guide 51 are provided, so also different elements of the illumination matrix 21 controlled switched on and off.

2 shows an inventive head-up display similar to 1 , The same parts are provided with the same reference numerals and not explained here. The light source 5 illuminates one along two axes 53 . 54 movable lens 52 , The mobility is by means of arrows on the axles 53 . 54 indicated. By the movement of the lens 52 Different lighting angles can be set. How to 1 described is the deflection angle φ of the control unit 4 specified.

According to a variant, the lens 52 fixedly arranged and the light source 5 becomes parallel to the axes 53 . 54 emotional. This is indicated by dashed arrows. According to another variant both lens 52 as well as the light source 5 moved in opposite directions. This has the advantage that the required deflections are less than when moving only one of these components.

According to another variant is instead of the light source 5 a two-dimensional illumination matrix 21 , similar to the one in 1 shown, provided, and the lens 52 is fixed. By turning on only one of the lighting elements 211 - 219 the illumination matrix 21 So nine different beam angles are achieved.

3 shows a detail of a deflection unit 2 with microlenses 25 , The light source 5 is here by grid-like LEDs arranged 55 . 551 . 552 . 553 educated. You can see that from a first LED 551 emitted light after passing through the microlenses 25 has a different radiation angle than that of a second LED 552 and a third LED 553 , Now only the position of the first LED 551 corresponding LEDs of the light source 5 turned on, so light is emitted according to a first angle. Another beam angle is achieved if only the position of the second LED 552 corresponding LEDs are turned on. In this way the desired deflection angle is adjusted.

4 shows a detail of a deflection unit 2 with microprisms 23 , Again, there is the light source 5 from grid-like arranged lighting elements 56 . 561 . 562 . 563 that are laser diodes here. Other light sources with sufficiently directed radiation characteristic can be advantageously used here. The light of the first light elements 561 points after passing through the first microprisms 231 a different output angle than that of the second light elements 562 generated light after passing through the second microprisms 232 , In this way the desired deflection angle is adjusted.

5 shows a detail of a deflection unit 2 with a grid of optical elements 26 , Here are the optical elements 261 . 262 . 263 . 264 arranged so that they deflect light incident on them from below in the drawing plane, while the optical elements 265 . 266 deflecting light from below upwards or downwards out of the plane of the drawing. Again, it is again provided that a light source, not shown, light from below on the deflection 2 passes. The optical elements 261 - 266 are distributed almost randomly over the surface of the grid in order to achieve a two-dimensional deflection.

6 shows a flowchart of a method for operating a head-up display according to the invention. In step S1, an angle α corresponding to the angular deflection in the X direction and an angle β corresponding to the angular deflection in the Y direction is determined. This is done according to a predetermined sequence, here represented by the patterns M1, M2. Shown here by way of example is a pattern M1 in which first the angle α in the first line, in the X direction, is varied, while the angle β remains fixed, after passing through the first line, the angle β is changed, the second line with modification of Go through angle α at constant β from right to left. The successive viewing angles differ only slightly from each other. In another pattern M2, the angles α and β are not changed in small steps, but in leaps and bounds. This is indicated by arrows. The successive viewing angles are thus very different here.

In step S2, an image B (α, β) provided for angles α, β as a viewing angle is calculated. In step S3, the deflection angle φ (α, β) is calculated. In step S4, the display unit 1 with the image B (α, β) and the deflection unit 2 with the angle φ (α, β) simultaneously driven. Subsequently, it returns to step S1 and determines the image and angle for a next pair α, β. This is done until the image to be displayed has been generated and displayed for all angle deflections. Then it proceeds accordingly with the temporally next image to be displayed.

In step S0, information about the position PS of the eyes of the observer is obtained. This can be done either selectively or in combination with the position sensor 64 and the adjusting element 65 , The calculation and control is based on the determined position PS. A corresponding lower number of images B and viewing angles φ are to be displayed or adjusted per unit of time. The sequence will be shortened accordingly.

7 shows an example of a driving sequence in which consecutive viewing angles φ deviate greatly from each other. By way of example, a 4 × 4 matrix is assumed here, which is traversed from top left to bottom right in the so-called ram jumping method. The individual continuous fields are numbered from 1-15. After reaching the field 15 becomes the field 16 jumped and from this to the field 1 , In this example, at least one row or column is skipped in each step, so the deflection angles are very different.

In other words, the present invention relates to the following:
In so-called "integral imaging", the angle of the light field is determined by the location of a pixel under the respective microlens. For this one needs a multiplicity of display pixels under each lens, which leads to high demands on the image generator altogether. The required large number of pixels is an economically difficult requirement to fulfill with current solutions. When the angle control according to the invention via the illumination eliminates the microlens. Each pixel of the display can be controlled in its beam angle by the angle of the lighting is varied globally in time and synchronously to the appropriate display content is displayed. Demands on the spatial resolution of the imager are decreasing, but temporal multiplexing requires higher frame rates. As there are no microlenses on the sun-facing side, there are no direct reflections on them either. Possible reflections on elements on the other side of the display are clearly attenuated, since the associated light is the display, the display unit 1 , happens twice and this typically has a low transmission.

It goes without saying that the measures mentioned in the individual exemplary embodiments and in the introduction to the description can also usefully be used in combinations other than those shown, and further developments are at the discretion of the person skilled in the art.

Claims (13)

Head-up display for a vehicle, comprising - a display unit ( 1 ) for producing different images (B (α, β)) for different viewing angles (φ (α, β)), - a deflection unit ( 2 ) for deflecting the different images (B (α, β)) of the display unit ( 1 ) outgoing light beams in different viewing angles (φ (α, β)), - a mirror unit ( 3 . 31 ) for superimposing on the display unit ( 1 ) outgoing light beams with other light beams, characterized in that the display unit ( 1 ) is designed to generate the different images (B (α, β)) one after the other and the deflection unit ( 2 ) is designed to deflect the light beams temporally successively into different viewing angles (φ (α, β)). Head-up display according to claim 1, characterized in that the display unit ( 1 ) from a light source ( 5 ), and the deflection unit ( 2 ) between light source ( 5 ) and display unit ( 1 ) is arranged. Head-up display according to claim 2, characterized in that the deflection unit ( 2 ) and light source ( 5 ) form a unit. Head-up display according to one of the preceding claims, characterized in that the light source ( 5 ) one of light elements ( 55 . 551 . 552 . 553 . 56 . 561 . 562 . 563 ) has existing matrix structure. Head-up display according to claim 4, characterized in that the deflection unit ( 2 ) a matrix of microlenses ( 25 ). Head-up display according to claim 5, characterized in that the matrix instead of microlenses ( 25 ) from microprisms ( 23 ) or other optical microelements ( 26 ) is formed. Head-up display according to one of the preceding claims, characterized in that it comprises a position sensor ( 64 ) and a control unit ( 4 ) having. Head-up display according to claim 7, characterized in that the position sensor ( 64 ) is an eye position detector. Head-up display according to one of the preceding claims, characterized in that it has an adjusting element ( 65 ) having. Method for activating a head-up display comprising the steps of - calculating (S2) images (B (α, β)) provided for different viewing angles (φ (α, β)), - sequentially activating (S4) a display unit ( 1 ) with the calculated images (B (α, β)), and - matched sequential driving (S4) of a deflection unit ( 2 ) with the associated angle information (φ (α, β)). A method according to claim 10, characterized in that the control for a sequence (M1) of slightly different viewing angle (φ (α, β)) takes place. A method according to claim 10, characterized in that the control for a sequence (M2) strongly differing viewing angle (φ (α, β)) takes place. The method of claim 10 with the further steps - determining (S0) information about the position (PS) of the observer's eyes, and - Calculating and driving according to the determined position (PS).

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