DE102017211691A1 - Visual field display device for a vehicle - Google Patents

Abstract

The invention relates to a visual field display device (1), in particular for a motor vehicle, comprising a projection unit (2) for generating a diverging or non-converging light beam (3) with a display information. In this case, the projection unit (2) is designed to generate a projection light of a predetermined first polarization type and has in a beam path (6) of the projection light of the first polarization on a propagation direction of the projection light rotatable polarizing element (24), wherein the polarization element (24) to a Changing the polarization of the projection light is formed and the effect and / or the type of polarization change by the rotation of the polarization element (24) is adjustable.

Description

Technical area

The invention relates to a visual field display device, in particular for a motor vehicle, comprising a projection unit for generating a non-converging, in particular a diverging light beam with a display information, wherein the projection unit is designed to generate projection light of a predetermined first polarization. The invention is also directed to a motor vehicle with a visual field display device of this type and to a method for operating such a vehicle.

Technical background

Visual field displays in a vehicle are commonly known as head-up display (HUD). Thus, a display information, for example an indication of a speed limit, as a virtual image is superimposed on the real environmental image in front of the vehicle observed by the driver. For this purpose, a visual field display device typically comprises a projection unit that generates light with desired display information and typically projects it onto the windshield of the vehicle, from which it is reflected towards the driver.

Since the angle of incidence of the light projected onto the windshield is close to the Brewster angle in conventional HUD configurations, predominantly s-polarized light is reflected at the interface of air to the glass or plastic windshield (ie, linearly polarized light whose polarization direction is perpendicular to typically vertical plane of incidence of the windshield is so horizontal parallel to the windshield is). For this reason, the projection units of many known field of view display devices are also designed for the preferred emission of s-polarized light. Consequently, without further measures, a HUD display using p-polarizing sunglasses would at best be greatly attenuated. P-polarizing sunglasses are designed to absorb primarily s-polarized light to avoid glare on reflective surfaces, such as puddle surfaces and the like, which also preferentially reflect s-polarized light.

To make a HUD display even when wearing p-polarizing sunglasses, therefore, for example, from DE 10 2015 205 243 A1 and DE 10 2013 206 505 A1 measures for increasing the reflected at a windshield portion of a p-polarized projection light known.

It is an object of the present invention to provide a visual field display device of the type mentioned, a corresponding motor vehicle and a suitable method for its operation, which allow the visibility of the display information of the visual field display device with the alternating use of polarizing filters, such as polarizing sunglasses by the driver so To improve significantly and flexibly, so that in principle no compromise on the visibility of the display information without the polarization filter must go hand in hand.

Disclosure of the invention

This object is achieved by a visual field display device according to claim 1 and a motor vehicle and a method for its operation according to the independent claims.

Further embodiments are specified in the dependent claims. All further features and effects mentioned in the claims and the description for the visual field display device also apply with respect to the vehicle or its operating method, and vice versa.

According to a first aspect, a visual field display device, in particular for a motor vehicle, is provided, which comprises a projection unit for generating a non-converging (i.e., not focused in an imaging manner on an image plane), in particular a diverging light beam with a display information. In this case, the projection unit is designed to generate a projection light of a predetermined first polarization type. Further, in a beam path of the projection light of the first polarization type, the projection unit has a polarization element rotatable about a propagation direction of the projection light (ie, about an optical axis of a corresponding optical system within the projection unit), the polarization element being configured to change the polarization type of the projection light and Effect and / or the type of polarization change by the rotation of the polarization element is adjustable and therefore particularly variable.

As mentioned above, in addition to the projection unit, the visual field display device may comprise a projection screen, which may for example represent a part of the windshield of a motor vehicle. The projection unit shown here is designed for projecting the diverging or non-converging light beam with a display information onto an at least partially reflecting interface of the projection screen, of which at least a portion of the projected light is reflected in the direction of the user.

An idea of the invention is to allow the user of the visual field display device to selectively change the polarization type of the light beam generated by the projection unit by providing a polarization element rotatable according to a user request within the projection unit. This allows the type of polarization of the light beam generated by the projection unit to be adjusted in operation in a simple and robust manner to a changing use of a polarizing filter, such as polarizing sunglasses for the user.

The rotatability of the polarization element about the propagation direction of the projection light - d. H. For example, an internal optical axis of the polarization unit, along which the projection light of the first polarization type propagates, offers a fundamentally unlimited flexibility of the adjustable polarization change. For example, by means of a polarization element in the form of a λ / 2 retardation plate, it is possible to rotate the polarization direction of a linearly polarized projection light by any angle α without loss of intensity, by rotating the polarization element at an angle a / 2 between the polarization direction of the projection light and a component-specific axis of the λ / 2-delay plate is set. Similarly, with a polarizing element in the form of a λ / 4 retardation plate, it is possible to leave a linear polarization of the projection light unchanged depending on the angular position of the λ / 4 retardation plate or in a circular or elliptical polarization with a desired axial length ratio of the ellipse to change.

The rotatability of the polarization element in operation can therefore be used in particular for a more effective use of the available total intensity of the projection light by the type of polarization of the projection light is flexibly adapted to an alternating use of a polarizing filter. For example, if the addition of a polarizing filter causes the intensity of the virtual display image to decrease, rotating the polarizing element may cause a suitable change in the polarization type of the projection light to a higher to the original maximum possible intensity of the virtual display image for the user can lead.

Since the rotatable polarizing element does not have to be moved out of the beam path of the projection light for setting (i.e., effecting and / or varying) a polarization change in the projection light, the solution set forth herein is extremely space-saving despite its high flexibility. Another peculiarity of the polarization element rotatable about an optical axis of the projection unit is that the number of possible rotational positions and thus the number of adjustable different polarization changes which can be set with a single suitable mechanical adjustment device are fundamentally unlimited.

In particular, the projection unit set forth herein can be combined with a projection screen, which in addition to the reflection of s-polarized light (ie perpendicular to the plane of incidence, usually horizontal and parallel to the projection screen polarized light) also to an increased reflection p-polarized light (ie parallel to the plane of incidence, so usually with a vertical component of linearly polarized light) is designed. As mentioned above, measures for an increased reflection of p-polarized light in projection screens of visual field display devices are known per se.

In a specific embodiment, the first polarization type corresponds to linear, in particular horizontal or substantially horizontal polarization of the projection light. Alternatively, a cyclic or elliptical polarization is possible. (Here and below, "substantially" means, in particular, a possible production or design-related possible deviation of up to about 10% of the relevant spatial directions or dimensions.)

In a possible development of this embodiment, the polarization element between a first rotational position in which the polarization of the projection light when passing through the polarization element remains substantially unchanged (neutral rotational position), and at least one second rotational position in which the polarization of the projection light when passing through the Polarization element is changed to a predetermined second polarization, rotatable. The second type of polarization may correspond, for example, to a linear polarization with a changed polarization direction or else a cyclic or elliptical polarization.

For example, for the reasons mentioned above, ie when using a windscreen which has at least one interface with preferred reflection of s-polarized light, the projection unit can be designed to generate an s-polarized projection light. Without polarizing glasses, this type of polarization would therefore lead to a high intensity of the virtual display image visible to the user of the visual field display device, so that the first, neutral Rotational position of the polarization element in which it causes no polarization change of the s-polarized projection light is suitable. On the other hand, when putting on p-polarizing sunglasses, the user of the visual field display device can obtain a p-polarized portion of the projection light of 0% up to 100% by appropriate rotation of the polarizing element, for example by rotating a λ / 2 retardation plate from the above neutral rotational position by 45 ° ° (second rotational position) - increase (s. 3 ). In particular, by the latter almost complete transformation of the polarization type of the projection light from the original first polarization mode to the second polarization mode corresponding to the polarization filter used, a particularly high intensity of the virtual display image generated by the visual field display device can be achieved.

In particular, the projection unit may comprise a light source and an imaging unit for generating the projection light with the display information, and imaging optics for projecting the generated projection light with the display information (in the form of the diverging or non-converging light beam) onto a reflection surface of a projection screen mentioned above. In this case, the polarization element can be arranged in particular between the imaging unit and the imaging optics, for example for reliably maintaining the optical quality of the entire display information immediately after the imaging unit.

The polarizing element may comprise, for example, a birefringent polymer layer, a birefringent crystal disk, a birefringent liquid crystal layer, or another type of optically anisotropic layer, as well as any combination of such components. In particular, a basically arbitrary polymer film, which has been given a mechanical anisotropy by a mechanical stretching, can be used as polarization element of the type set forth herein. Since a birefringent or optically anisotropic material has different light velocities for light polarized parallel to a component-specific axis and light polarized perpendicular thereto, a different change in the polarization mode of the projection light can be effected depending on the orientation of the component-specific axis relative to the polarization direction of the projection light. In other words, by rotating the component-specific axis about the propagation direction of the projection light, the type of polarization change achieved can be changed. In particular, a linear polarization of the projection light as it passes through the polarization element remains unchanged when the polarization direction is exactly parallel or perpendicular to said component-specific axis of the birefringent element.

In particular, the polarization element can comprise a λ / 4 retardation plate and / or a λ / 2 retardation plate, but this is not absolutely necessary. In other words, the effects set forth herein can in principle also be achieved with birefringent layers of other thicknesses. In particular, the projection light may indeed have a certain wavelength, in particular represent laser light. However, the projection light can basically be any kind of visible light.

It can be provided that the polarization element is rotatable by at least 15 °, by at least 30 ° or by at least 45 °, whereby a large part of the types of polarization change mentioned in the examples can already be achieved. It can also be provided that the polarization element can be rotated even further, ie by at least 60 °, by at least 75 ° or by at least 90 °, whereby further additional types of polarization change can be made possible.

• - zwischen mindestens zwei, mindestens drei, mindestens vier oder mindestens fünf verschiedenen vorbestimmten Drehpositionen drehbar ist, von denen jede eine jeweils unterschiedliche Polarisationsänderung beim Projektionslicht bewirkt, oder
• - kontinuierlich zwischen mehreren verschiedenen Drehpositionen drehbar ist, von denen jede eine jeweils unterschiedliche Polarisationsänderung beim Projektionslicht bewirkt.

In particular, the projection unit can be designed such that the polarization element

• is rotatable between at least two, at least three, at least four or at least five different predetermined rotational positions, each of which causes a respectively different polarization change in the projection light, or
• - Is continuously rotatable between a plurality of different rotational positions, each of which causes a different polarization change in the projection light.

By rotating the polarization element between more than two different rotational positions from the above-mentioned neutral rotational position with respect to the induced polarization change, the polarization mode of the projection light can be flexibly adapted to more than two different alternately used polarization filters, for example differently polarized sunglasses.

According to one embodiment, the projection unit comprises a mechanical adjustment device for rotating the polarization element, which may be designed to be manually controllable, in particular, by a user of the field of vision display device. For example, the adjustment at least partially electrically, such as by operating a corresponding electronic control panel or a mechanical control switch be controlled by the user, or purely mechanically, in particular by a suitable knob.

According to a further aspect, a motor vehicle is provided with a visual field display device of the type set forth herein, wherein the visual field display device is designed for fading in a display information into a field of vision of the driver. In particular, the projection unit may comprise an abovementioned mechanical adjusting device for rotating the polarization element, which is designed to be manually controllable by the driver.

Another aspect is a method for operating such a motor vehicle, the driver depending on the use of additional polarizing filter, in particular a polarizing sunglasses, by actuation of the mechanical adjustment such a change in the polarization of the projection light causes that for the driver (objectively, ie measurable with optical instruments) increases visible light intensity of the display information displayed by the visual field display device.

list of figures

• 1 eine schematische vertikale Querschnittsansicht einer Blickfeldanzeigevorrichtung der hierin dargelegten Art;
• 2 eine schematische Darstellung des Funktionsprinzips eines drehbaren Polarisationselements (in dessen neutraler Drehposition) in einer Blickfeldanzeigevorrichtung der hierin dargelegten Art ohne eingesetzten Polarisationsfilter;
• 3 eine schematische Darstellung des Funktionsprinzips des drehbaren Polarisationselements in der Blickfeldanzeigevorrichtung der 2 mit eingesetztem Polarisationsfilter und dementsprechend um 45° aus der neutralen Drehposition gedrehtem Polarisationselement.

Embodiments are explained in more detail below with reference to the examples shown in the accompanying drawings. The drawings are purely schematic, in particular they are not to be read as true to scale. Show it:

• 1 a schematic vertical cross-sectional view of a visual field display device of the type set forth herein;
• 2 a schematic representation of the operating principle of a rotatable polarization element (in its neutral rotational position) in a field of view display device of the type set forth herein without polarization filter inserted;
• 3 a schematic representation of the principle of operation of the rotatable polarizing element in the visual field display device of 2 with inserted polarization filter and accordingly by 45 ° from the neutral rotational position rotated polarization element.

Description of embodiments

1 shows in a highly simplified schematic vertical cross-sectional view of a visual field display device 1 the type set forth herein, which may in particular constitute a head-up display in a motor vehicle. The visual field display device 1 includes a projection unit 2 in operation, a non-converging (ie, not focused in an imaging manner on an image plane) light beam 3 generated with a desired display information (not shown) and on one above the projection unit 2 arranged partially translucent projection screen 4 projected.

From the projection screen 4 , which may be formed in particular as part of a windshield of the motor vehicle, is at least a portion of the light beam 3 to the eye 5 of the user, in this example the driver of the motor vehicle, reflected. In operation, the driver sees the display information as a virtual image (not shown) perceived at some distance from the windshield in front of the vehicle. Because the projection screen 4 is transparent, the virtual image superimposes the driver's visible real environment.

The projection unit 2 is with a light source 21 and an imaging unit 22 z. B. in the form of an LCD (ie, a liquid crystal panel) or a transparent display for generating a projection light with the display information provided. For projecting the generated projection light with the display information (in the form of the light beam 3 ) on the projection screen 4 is in the projection unit 2 usually also an imaging optics 23 provided, which may include, among other things, one or more deflection mirrors (not shown).

As detailed above, further is within the projection unit 2 in the beam path 6 (please refer 2 ) of the projection light, in 1 purely exemplary between the imaging unit 22 and the imaging optics 23 immediately after the imaging unit 22 a rotatable polarizing element 24 intended. This is designed, depending on its adjustable rotational position, the polarization of the polarization by the element 24 changing projection light.

To rotate the polarizing element 24 indicates the projection unit 2 a mechanical adjustment 25 of the type mentioned above, in this example by the user of the visual field display device 1 from outside the field of view display device 1 manually adjustable or adjustable by a controllable by the user positioner is designed. To effect a desired rotation of the polarizing element 24 around the propagation direction of the projection light, ie around an internal optical axis of the projection unit 2 (please refer 2 and 3 ), the required power transmission by means of a suitable power transmission element 26 of the mechanical adjustment 25 be implemented, for example by means of a Bowden cable or spindle drive. In particular, as a power transmission element 26 or as a part thereof, one in the projection unit 2 already to the movement of a deflection mirror of the imaging optics 23 provided mechanism can be used, for example, by means of a provided in this mechanics "gear switch" either between the adjustment of the deflection mirror and the polarization element 24 is changed. In particular, you can thereby without an additional motor for the mechanical adjustment 25 get along.

2 and 3 In order to explain the basic principle of operation of the rotatable polarizing element of the type set forth herein, simplified schematic representations of the beam path are shown 6 (indicated as a solid arrow straight line) of the projection light from the light source of the projection unit 2 a visual field display device 1 of the kind set forth herein to the eye 5 a viewer of the virtual display image (not shown). The visual field display device 1 of the 2 and 3 In particular, that of the 1 be, for clarity, the imaging optics 23 and the projection screen 4 are omitted.

The functional principle is in 2 and 3 purely by way of example with reference to a projection unit 2 which is used to generate s-polarized light (perpendicular to the usually vertical plane of incidence on the projection screen 4 as in 1 , ie, horizontally polarized light) is formed (as the above-mentioned first polarization mode). Purely symbolically generated in 2 a light source 21 unpolarized light (indicated by arrows pointing in all directions) while only s-polarized light is an imaging unit 22 in the form of an LCD (symbolically indicated by a vertical metal grid that absorbs p-polarized light with a vertically oscillating electric field and therefore lets through only s-polarized light).

In the beam path 6 of the projection light is a rotatable polarization element 24 Here, purely by way of example, this may be a stretched polymer film λ / 2 retardation plate having a half period retardation (eg, for a medium wavelength in non-monochromatic light) for light polarized parallel to the component specific axis A (indicated by dashed line) can cause relative to the perpendicular polarized light. A rotational position of the polarization element 24 and thus its component-specific axis A in the plane perpendicular to the propagation direction of the projection light level can by means of a mechanical adjustment 25 be set and changed.

In 2 a case is shown in which the user does not wear polarized sunglasses. So there are no additional polarization filters on the way of the projection unit 2 generated light beam 3 to the eye 5 the user exists. Therefore, in 2 a neutral rotational position of the polarization element 24 adjusted, whose component-specific axis A parallel to the polarization direction (s-polarization in the direction of the drawn horizontal axis x ) of the projection light and therefore no polarization change of the projection light as it passes through the polarization element 24 causes. S-polarized projection light of the light beam 3 therefore reaches the eye 5 the user with well visible intensity, what in 2 purely symbolic with a over the entire width (not shown) of the light beam 3 brightly illuminated mental perception screen 7 is illustrated.

In 3 is different from 2 the case illustrated in which a polarizing filter 8th on the way of the projection unit 2 generated light beam 3 to the eye 5 the user exists. The polarization filter 8th Here, by way of example, a p-polarizing (ie parallel to the vertical plane of incidence on the projection screen 4 as in 1 polarizing) sunglasses at the driver of the vehicle. The s-polarizing imaging unit 22 and the p-polarizing polarizing filter 8th represent crossed polarizers, so that no virtual image would be perceptible by the user without a polarization change of the projection light, which symbolically represented by hatched areas 7b mentally illustrated perception screen 7 is indicated.

As in 3 shown is that of the light beam 3 to the eye 5 the user transported display information by the appropriate rotation of the polarization element 24 by 45 ° from the neutral rotational position of 2 again made visible, ie by rotating the λ / 2-retardation plate in a second rotational position, in which the component-specific axis A is about 45 ° with the horizontal axis x includes. In this rotational position of the polarization element 24 In contrast to the x-direction s-polarized projection light, the λ / 2 retardation plate rotates its polarization by approximately 90 ° (in principle without loss of intensity), so that p-polarized projection light of the same intensity is the polarization element 24 Leaves and therefore also basically without loss of intensity, the p-polarizing polarizing filter 8th can happen. As a result, in 3 in the eye 5 the user a the polarization element 24 corresponding area 7a of the perception screen 7 brightly lit, ie the user can display the virtual display image of the visual field display device 1 see.

Rotating the polarizing element 24 For example, the user can manually through Activation / actuation of the mechanical adjustment device 25 be effected via an electronic control element, a mechanical knob or any other suitable control device.

Each of the other variants and specific embodiments of the visual field display device and of the vehicle mentioned above in the description and in the following claims may be used in accordance with the embodiments described in US Pat 1 . 2 and 3 be implemented examples shown. In particular, instead of the λ / 2 retardation plate, a λ / 4 retardation plate may be used as the polarization element 24 used in the in 3 shown rotational position would convert the s-polarized projection light into a circularly polarized light. However, it is immediately apparent that delay plates with a thickness and / or rotational position deviating from the very specific example shown in the figures can also be suitable for achieving an objectively highly visible visualization of the virtual display image for the user.

LIST OF REFERENCE NUMBERS

1

Head-up display device

two

projection unit

3

Light beam

4

projection screen

5

Eye of the user

6

Beam path of the projection light in the projection unit

7

perception screen

8th

Polarizing filter (sunglasses)

21

light source

22

imaging unit

23

imaging optics

24

rotatable polarization element

25

mechanical adjusting device for rotating the polarization element

26

Power transmission element of the mechanical adjusting device

QUOTES INCLUDE IN THE DESCRIPTION

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

Cited patent literature

• DE 102015205243 A1 [0004]

Claims (12)

A visual field display device (1), in particular for a motor vehicle, comprising a projection unit (2) for generating a diverging or non-converging light beam (3) with a display information, wherein the projection unit (2) - Is formed for generating a projection light of a predetermined first polarization type; and - In a beam path (6) of the projection light of the first polarization a rotatable about a propagation direction of the projection light polarization element (24), wherein the polarization element (24) is adapted to change the polarization of the projection light, so that the effecting and / or the Art a polarization change by the rotation of the polarization element (24) is adjustable. Visual field display device (1) after Claim 1 , wherein the first type of polarization corresponds to a linear polarization, in particular a horizontal polarization, of the projection light. Visual field display device (1) after Claim 1 or 2 wherein the polarization element (24) between a first rotational position in which the polarization of the projection light when passing through the polarization element (24) remains substantially unchanged, and at least one second rotational position in which the polarization of the projection light when passing through the polarization element (24 ) is changed to a predetermined second polarization, in particular around the axis of the beam path, is rotatable. A visual field display device (1) according to any one of the preceding claims, wherein - The projection unit (2) a light source (21) and an imaging unit (22) for generating the projection light with the display information and an imaging optics (23) for projecting the generated projection light with the display information on a reflection surface of a projection screen (4), in particular a windshield of a motor vehicle; and - The polarization element (24) between the imaging unit (22) and the imaging optics (23), preferably immediately after the imaging unit (22), is arranged. A visual field display device (1) according to any one of the preceding claims, wherein the polarization element (24) comprises a birefringent polymer layer and / or a birefringent crystal disk and / or a birefringent liquid crystal layer and / or a different type of optically anisotropic layer. A visual field display device (1) according to any one of the preceding claims, wherein the polarization element (24) comprises a λ / 4 retardation plate and / or a λ / 2 retardation plate. A visual field display device (1) according to any one of the preceding claims, wherein the polarization element (24) is rotatable at least 15 °, at least 30 °, at least 45 °, at least 60 °, at least 75 ° or at least 90 °. Visual field display device (1) according to one of the preceding claims, wherein the projection unit (2) is designed such that the polarization element (24) is rotatable between at least two, at least three, at least four or at least five different predetermined rotational positions, each of which causes a respectively different polarization change of the projection light, or - Is continuously rotatable between a plurality of different rotational positions, each of which causes a different polarization change of the projection light. A visual field display device (1) according to one of the preceding claims, wherein the projection unit (2) comprises a mechanical adjustment device (25) for rotating the polarization element (24), which is preferably manually adjustable by a user of the visual field display device (1) or controllable in accordance with a user specification , Motor vehicle with a visual field display device (1) according to any one of the preceding claims, wherein the visual field display device (1) is designed for fading a display information in a field of view of the user. Motor vehicle after Claim 10 wherein the projection unit (2) comprises a mechanical adjustment device (25) for rotating the polarization element (24), which is manually adjustable by the user or adjustable according to a user specification by a positioner. Method for operating a motor vehicle according to Claim 11 wherein, depending on the use of additional polarizing filters (8), in particular polarizing sunglasses, by actuating the mechanical adjusting device (25) such a change in the polarization type of the projection light causes the user to see the light intensity of the visual field display device (1) displayed information increased.

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