CN111948819A - Display device and method for displaying images for a vehicle and carrier element - Google Patents

Abstract

Display device and method for displaying images and carrier element for a vehicle. The present invention relates to a display device (110) for displaying an image for a vehicle, wherein the display device (110) has a first hologram element, a second hologram element and a polarizing element. Here, the polarizing element is arranged between the first hologram element and the second hologram element.

Description

Display device and method for displaying images and carrier element for vehicles

technical field

The invention is based on a display device and a method for displaying images and a carrier element for a vehicle of the type according to the independent claims.

Background technique

DE 10 2007 007 162 A1 describes holographic information displays.

SUMMARY OF THE INVENTION

Against this background, an improved display device and an improved method for displaying images and an improved carrier element for vehicles according to the independent claims are presented with the solutions presented here. Advantageous refinements and refinements of the device specified in the independent claims are possible by means of the measures recited in the dependent claims.

In the context of automated driving, application situations arise in which, for example, a window panel of a vehicle can be used as a projection surface as a display device. By means of the solution presented here, a display device is achieved which enables the reflection of the light beam and, additionally or alternatively, the transmission of the light beam, in order to be able to present image content to the user.

A display device for displaying an image for a vehicle is described, wherein the display device has a first hologram element, a second hologram element and a polarizing element. Here, the polarizing element is arranged between the first hologram element and the second hologram element.

The display device can be arranged, for example, in a vehicle, which is shaped for transporting people, for example, and additionally or alternatively objects. The display device can be arranged, for example, on a panel of a vehicle, such as a windshield of the vehicle. The image may be, for example, an image stored in a storage device or generated, but may also be at least partially acquired by, for example, a camera. The first holographic element and also the second holographic element can transmit or reflect the light beam, for example, depending on the polarization. The first holographic element and the second holographic element can, for example, have different reflection or transmission properties with respect to the same polarization of light. The polarizing element can, for example, absorb the light or change the polarization direction of the light, eg circularly polarize the light beam. Transmission can currently be understood as passing light at or through the relevant holographic element.

The solution presented here is based on the recognition that a very flexible manipulation of the output of the image is achieved by a sandwich design of the polarizing element between the first and second holographic elements. For example, by targeted incidence of light with a defined polarization, the light can be transmitted at the first holographic element, wherein the light is reflected by the second holographic element. In contrast, if, for example, light with a different polarization is incident on the first hologram element or the second hologram element in the beam path, the light is reflected, for example, at the first hologram element and transmitted at the second hologram element. Particularly advantageously, it is then possible to use polarizing elements which change the polarization of the light after reflection at one of the holographic elements, so that the reflection properties of the light at the first or second holographic element are then relatively The light that is initially incident on the display device is different. As a result, the selection of the polarization of the light incident on the display device can be very cleverly defined by means of static structural measures in which direction the image represented by the light is to be output.

According to one embodiment, the first holographic element can be shaped as a reflection holographic plate and the second holographic element can be shaped as another reflection holographic plate or as a transmission holographic plate. Advantageously, the light beam can for example be reflected into the interior of the vehicle or transmitted in a direction away from the interior, so that the image is visible from areas outside the vehicle.

According to one embodiment, the first holographic element and the second holographic element may be oriented such that light reflected by the first holographic element onto the second holographic element can be transmitted through and reflected from the second holographic element Light onto the first holographic element can be transmitted. Advantageously, different image contents can thus be displayed for internal projection and external projection, depending on which polarization of the light is incident on the display device.

The display device has a polarizing element, which can be formed as a polarizing filter and additionally or alternatively as a retardation element, in particular a λ/4 retardation layer. As a polarizing filter, the polarizing element can, for example, absorb light or change the polarization of light when passing through the polarizing element. As a polarizing filter, the polarizing element may be configured to pass only light having a predetermined polarization. As retardation elements, polarizing elements can, for example, change the polarization and/or phase of passing electromagnetic waves, such as light waves. Advantageously, the visibility of the image from different sides of the display device can thereby be adjustable.

According to one embodiment, the display device can have a beam splitter which can be shaped for splitting the light beam, in particular wherein the beam splitter can be arranged between the first holographic element and the second holographic element. The beam splitter can be realized, for example, as a layer which, according to one embodiment, can be arranged between the polarizing element and the second holographic element. Advantageously, the beam splitter can split the light beam so that it is output at different sides of the display device.

According to one embodiment, the beam splitter can be shaped to transmit the light beam in a polarization-dependent manner and additionally or alternatively to reflect the light beam. The resulting display possibility of the image can advantageously protect the privacy of the user, for example inside the vehicle, since the image is displayed in the interior of the vehicle when the light beam is reflected.

According to one embodiment, the display device can have a projector unit, which can be shaped so that the light beam can exit in the light path to the first holographic element. The projector unit can be, for example, a laser output unit or an LED projector unit and/or be arranged on a roof element of the vehicle and/or be connected to the vehicle electronics. Thereby, eg safety-related information can be faded in for the user of the vehicle.

According to one embodiment, the projector unit can be shaped for adjusting and additionally or alternatively switching the polarization direction of the light beam, in particular wherein the projector unit can be configured to enable different adjustable polarization directions at different times output beam. This means that the projector unit can have, for example, a phase delay element. Advantageously, by adjusting the polarization direction, the transmissive and reflective displays can be individually switchable for the inner view or the outer view, respectively, so that it is possible to define very efficiently by adjusting the polarization of the light beam to be output: in which part of the display device The image should be visible on one side.

According to one embodiment, the projector unit can be oriented relative to the first holographic element such that the light beam emitted by the projector unit can be at least partially transmitted by the first holographic element. Advantageously, the see-through display and the reflective display for the interior view or exterior view can thus be individually switchable in each case.

Furthermore, a carrier element, in particular a carrier plate, is introduced which has a display device according to one of the variants mentioned above. According to one embodiment, the display device can be arranged between two plates of the carrier element. In this way, the display device can be integrated into the vehicle element, so that a very compact design and the provision of an adjustable output of images by means of the display device are created.

The carrier element can be implemented, for example, as a panel of the vehicle, into which, for example, the display device can be embedded, for example, can be arranged between two panels. Advantageously, a separate display unit can thus be avoided, which, for example, may limit the field of view of the driver of the vehicle.

Furthermore, according to one embodiment, the carrier element can be formed as a plastic sheet or a glass sheet. Advantageously, the driver can thus view unrestricted by the carrier element.

Furthermore, a method for displaying an image using a display device for a vehicle in one of the previously described variants is introduced, the method comprising the steps of incident, the step of passing and reflection and additionally or alternatively Transmission step. In the incident step, the light beam is incident on the first hologram element in a predetermined polarization direction. In the passing step, the light beam passes through the polarizing element. In the step of reflecting and additionally or alternatively transmitting, the light beam is reflected and additionally or alternatively transmitted in the second holographic element as a function of the polarization direction of the light beam.

The method can be carried out, for example, in a vehicle which is shaped for transporting persons and additionally or alternatively objects. Advantageously, the privacy of the user of the vehicle can be protected by this method in that the image content to be output is projected onto the display device by selecting the polarization of the light with which the image content is output.

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

Description of drawings

Embodiments of the solutions presented here are shown in the drawings and explained in more detail in the description that follows.

Figure 1 shows a schematic diagram of a display unit and a carrier element with a projector unit according to one embodiment;

Figure 2 shows a schematic cross-sectional view of a display device according to one embodiment;

FIG. 3 shows a schematic cross-sectional view of a display device according to one embodiment;

Figure 4 shows a schematic cross-sectional view of a display device with a projector unit according to one embodiment;

FIG. 5 shows a schematic cross-sectional view of a display device with a projector unit according to one embodiment; and

Figure 6 shows a flowchart of a method for displaying an image, according to one embodiment.

Detailed ways

In the ensuing description of the advantageous embodiments of the invention, the same or similar reference numerals are used for elements that are shown in different figures and function similarly, wherein repeated description of these elements is omitted.

FIG. 1 shows a schematic diagram of a projector unit 105 and a carrier element 100 of a display device 110 according to one embodiment. The carrier element 100 is realized according to this embodiment as a plate, which is used in particular in a vehicle. This is, for example, a panel of a vehicle. The vehicle can be realized, for example, as a passenger car, but also as a commercial vehicle. The projector unit 105 is shaped for transmitting an image onto a projection surface, which is also referred to hereinafter as the display device 110 . The display device 110 is arranged according to this embodiment between the two plates of the carrier element 100 and has a first holographic element, a polarizing element and a second holographic element. According to this embodiment, the display device 110 is thus designed to exit the light beam 115 in the light path to the first holographic element. Here, the projector unit 100 is shaped for adjusting and/or switching the polarization direction of the light beam 115 . The projector unit 100 is furthermore designed to output the light beam 115 with different adjustable polarization directions at different times. The projector unit 100 is oriented according to this embodiment relative to the first holographic element such that the light beam 115 emitted by the projector unit is at least partially transmitted by the first holographic element. This means that the light output by the projection unit 100 is reflected and/or transmitted in the form of the light beam 115 so that the image transmitted via the light beam 115 is visible in the area 120 inside the vehicle and/or in the area 125 outside the vehicle. Display device 110 is correspondingly designed to display images. In order to display the image, for example, a method for displaying the image using the display device 110 can be carried out, which method is described in more detail in one of the subsequent figures.

In other words, the scheme presented here describes a bidirectional holographic display projection for a vehicle. The core of the described scheme is to embed the layer structure of the display device 110 into the plate, which means that the first holographic element, also called a reflective hologram (Reflektions hologramm), also called a retardation film or λ/4 retardation The polarizing element of the layer, optionally a polarization dependent beam splitter and a second holographic element, which may also be called a reflection holographic plate, but also a transmission holographic plate, are embedded in the plate. The holographic element serves as a projection surface for a display device, which may also be referred to as a display system. For this purpose, the projector unit 105 focuses the projected image points on the projection surface of the holographic element, whereby the image points of the image content produced are visible from the defined solid angle range scattered by the holographic element. In this way, an interior view and an exterior view can be realized, which can be realized via the generation of the image content of the projector unit 105 with the respective polarization independently of each other. The angle of incidence of the light from the projector unit 105 is selected here so that the conditions of the acceptance angle of the holographic element are respected.

FIG. 2 shows a schematic cross-sectional view of a display device 110 according to one embodiment. The display device 110 may correspond to the display device 110 described in FIG. 1 . The display device 110 is also designed according to this embodiment to display images. The display device 110 according to this embodiment has a first holographic element 200 , a polarizing element 205 , a beam splitter 210 and a second holographic element 115 arranged according to this embodiment between the first plate 220 and the second plate 225 . The first holographic element 200 is implemented here as a reflection holographic plate. The second holographic element 215 is shaped according to this embodiment as a further reflection holographic plate or a transmission holographic plate. This means that according to this embodiment not only the first holographic element 200 but also the second holographic element 215 reflects the light beam 115 and the second holographic element 215 additionally or alternatively transmits the light beam 115 . Optionally, the first holographic element 200 can also transmit the light beam 115 according to this embodiment. According to one embodiment, the reflection or transmission of the holographic elements 200 , 215 is related to the angle of incidence of the light beam 115 and the polarization of the light beam 115 . If, for example, the angle of incidence of the light beam 115 lies outside the reception range (ie the predetermined angular range) of the first holographic element 200 and/or the second holographic element 215, the first holographic element and/or the second holographic element do not act on the beam 115 and beam 115 is transmitted.

The polarizing element 205 is shaped as a λ/4 retardation layer according to this embodiment. The polarizing element 205 is configured to polarize or change the polarization of the light beam 115 . According to this embodiment, the polarizing element 205 is arranged between the first holographic element 200 and the second holographic element 215 . The light beam 115 strikes a beam splitter 210 from the polarization element, which is correspondingly arranged between the first hologram element 200 and the second hologram element 215 , more precisely between the polarization element 205 and the second hologram element between 215. The beam splitter 210 is here shaped to split the light beam 115 and to transmit and/or reflect polarization-dependently according to the embodiment. If the light beam 115 is transmitted, for example, at the beam splitter 210 , it is reflected at the second holographic element 215 in the direction of the first holographic element 200 . In this case, according to the exemplary embodiment, the light beam 115 passes through the beam splitter 210 again and is split, which passes both the polarizing element 205 and the first holographic element 200 and displays an image in the region 120 of the vehicle interior.

If the light beam 115 is reflected at the beam splitter 210 according to the polarization direction, the light beam passes through the polarizing element 205 until the light beam 115 strikes the first holographic element 200 . In this case, the light beam 115 is reflected by the first hologram element 200 in the direction of the second hologram element 215 , so that the light beam 115 is transmitted in a region 125 outside the vehicle.

In other words, the light or beam 115 of the projector unit after passing through the first holographic element 200 and the polarizing element 205 is divided by the beam splitter 210 into a reflected part and a transmitted part according to its polarization. The reflected portion re-passes the polarizing element 205 and is reversed at the first holographic element 200 at the defined solid angle before it re-passes the polarizing element 205 and is transmitted in the beam splitter 210 and the second holographic element 215 scattering. The part that is first transmitted at the beam splitter 210 is backscattered at the second holographic element 215 at a defined solid angle and passes through the layer structure of the beam splitter 210 , the polarizing element 205 and the first holographic element 200 in a transmissive manner, respectively . Thereby, the display of different image contents for internal projection and external projection is achieved based on the polarization of the image sent by the projector unit. Furthermore, according to this embodiment, the transmissive and/or reflective display for the interior and exterior views, respectively, can be switched on individually by adjusting the polarization of the light sent by the projector unit. Furthermore, the display of the interior view is not necessarily visible from outside the vehicle according to this embodiment and thus meets the criteria for the privacy of the user inside the vehicle.

FIG. 3 shows a schematic cross-sectional view of a display device 110 according to one embodiment. The display device 110 may correspond to the display device 110 described in FIG. 2 . According to this embodiment, only another beam 300 is shown in addition to beam 115'. The light beam 115 in FIG. 3 is polarized and is therefore marked with reference numeral 115 ′ relative to the illustration in FIG. 2 where the light beam 115 is unpolarized. In this way, two different polarization directions of light beam 115' or another light beam 300 can be visualized, thereby reflecting and/or transmitting images. Also according to this embodiment, the light beam 115 ′ is reflected at the beam splitter 210 , since the polarization direction shown according to the arrow 305 first points in the counterclockwise direction and after passing through the polarization element 205 is converted into a vertical linear polarization. The light beam 115 ′ passes through the polarization element 205 until it is reflected at the beam splitter 210 in the direction of the first holographic element 200 due to the polarization direction after passing through the polarization element 205 . At the first hologram element 200 , according to this exemplary embodiment, the light beam 115 ′ is reflected again in the direction of the second hologram element 215 and changes the polarization direction here, so that the polarization direction extends clockwise. The light beam 115 ′ is then transmitted into a region 125 outside the vehicle.

In other words, the depicted beam 115' changes with polarization are shown for the interior view. The circularly polarized light beam 115 ′ emitted from the projector unit first passes through the first holographic element 200 . The angle of incidence lies here outside the reception range of the first hologram element 200 , so that the first hologram element 200 has no effect on the incident light beam 115 . Next, the light beam 115 ′ passes through the polarizing element 205 and is thereby linearly polarized and oriented so as to be reflected at the polarization dependent beam splitter 210 . After this reflection, the light beam 115' passes through the polarizing element 205 again and is circularly polarized again. The light beam 115 ′ is now in the angular range processed by the first holographic element 200 upon impact and is thus backscattered by the first holographic element 200 into the defined spatial range. After scattering at the first holographic element 200 , the light beam 115 ′ passes through the polarizing element 205 again, whereby the light beam assumes a linear polarization in the passing direction to the beam splitter 210 . The light beam 115' is transmitted through the beam splitter 210 due to its linear polarization in the pass-through direction and passes through the second holographic element 215 at an angle other than the acceptance angle of the second holographic element. The light beam 115' is transmitted because the light beam 115' passes through the second holographic element 215 outside the second holographic element's acceptance angle.

According to this embodiment, the further light beam 300 passes through the first holographic element 200 , the polarizing element 205 and the beam splitter 210 until the further light beam 300 is reflected at the second holographic element 215 in the direction of the first holographic element 200 , which further The polarization direction of a light beam extends clockwise. Here, the other light beam 300 maintains its polarization direction. According to this exemplary embodiment, the further light beam 300 passes through the beam splitter 210 , which splits the further light beam 300 , and also passes through both the polarizing element 205 and the first holographic element 200 , until the image is displayed in the region 120 of the vehicle interior.

In other words, the other beam 300 is circularly polarized in the opposite direction of rotation to the beam 115'. Another light beam 300 passes through the first holographic element 200 outside the angular range processed by said first holographic element. Next, another light beam 300 passes through the polarizing element 205 and is thus linearly polarized in the passing direction of the beam splitter 210 . After transmission through the beam splitter 210, another light beam 300 strikes the second holographic element 215 within the angular range processed by the second holographic element and is backscattered by the optical function of the second holographic element 215 to a defined in the solid angle range. The backscattered further light beam 300 then re-passes the beam splitter 210 and the polarizing element 205 and is thus circularly polarized. Upon impinging on the first holographic element 200 , the further light beam 300 split by the beam splitter 210 lies outside the processed angular range of the first holographic element 200 and is thus transmitted until it is in the region 120 of the vehicle interior Display the image.

FIG. 4 shows a schematic cross-sectional view of a display device 110 with a projector unit 105 according to one embodiment. The display device 110 may correspond to the display device 110 described in FIG. 1 . The display device 110 according to this embodiment has a first holographic element 200 , a polarizing element 205 and a second holographic element 215 arranged according to this embodiment between the first plate 220 and the second plate 225 . According to this embodiment, the polarizing element 205 is implemented as a polarizing filter. According to this embodiment, the projector unit 105 is also designed to output light beams 115 or 115 ′ in the direction of the first holographic element 200 at different times, which light beams are then reflected or transmitted at the first holographic element 200 . .

In other words, a layer structure with the first holographic element 200 , the polarizing element 205 and the second holographic element 215 is introduced according to this embodiment, which layer structure is arranged between the first plate 220 and the second plate 225 , which means embedded in in the carrier element 100 . If the polarization direction indicated by the passing arrow 305 of the projection unit 105 coincides with the passing direction of the polarizing element 205 , not only the first holographic element 200 but also the second holographic element 215 is recorded and displayed not only inside the vehicle but also in the Visible from outside the vehicle. The diffraction efficiency of the first holographic element 200 is adjusted here in order to transmit a certain part of the light beam 115 or 115 ′ to the second holographic element 215 . In this way, the brightness of an external display can also advantageously be adjusted, for example, in that, according to one embodiment, the polarization direction is slightly rotated towards the transmitted or reflected polarization direction of the polarization element 205 .

According to this embodiment, the polarization direction of the projector unit 105 is adjusted to the passing direction of the polarization element 205 . Thereby, the light beam 115 or 115' also reaches the second holographic element 215 and is shown to be visible in transmission.

FIG. 5 shows a schematic cross-sectional view of a display device 110 with a projector unit 105 according to one embodiment. The display device 110 shown here may correspond to the display device 110 described in FIGS. 1 and 4 .

In other words, the polarization direction of the projector unit 105 is adjusted to the absorbed polarization of the polarization element 205 . The light beam 115 is thus absorbed after the first holographic element 200, so that the image is only visible in reflection.

However, if the polarization direction of the beam 115 is different from that shown in FIG. 5 , the beam 115 or 115 ′ is rotated in a direction other than the cut-off direction according to this embodiment, eg by a phase retardation element in the projector unit 105 . It is not absorbed in the polarizing element 205 and reaches the second holographic element 215 . In this way, the display is visible from the outside.

FIG. 6 shows a flowchart of a method 600 for displaying an image, according to one embodiment. The method 600 may be applied in a display device as described in FIGS. 1 to 5 according to this embodiment. The method 600 here includes a step 605 of incidence, a step 610 of passing, and a step 615 of reflection and/or transmission. In the incident step 605, the light beam is radiated onto the first holographic element in a predetermined polarization direction. In passing step 610, the light beam passes through the polarizing element. In the reflection and/or transmission step 615, the light beam is reflected or transmitted in the second holographic element in relation to the polarization direction of the light beam.

If an embodiment includes an "and/or" association between a first feature and a second feature, this can be understood as such that the embodiment according to one embodiment has not only the first but also the second feature and according to another An embodiment has either only the first feature or only the second feature.

Claims (12)

1. A display device (110) for displaying an image for a vehicle, wherein the display device (110) has the following features:

-a first holographic element (200);

-a second holographic element (215); and

-a polarizing element (205), wherein the deflecting element (205) is arranged between the first holographic element (200) and the second holographic element (215).

2. The display device (110) of claim 1,

wherein the first holographic element (200) is shaped as a reflective holographic plate and the second holographic element (215) is shaped as another reflective holographic plate or as a transmissive holographic plate.

3. The display device (110) according to claim 1 or 2,

wherein the first holographic element (200) and the second holographic element (215) are oriented such that light reflected by the first holographic element (200) onto the second holographic element (215) is transmitted through the second holographic element (215) and light reflected by the second holographic element (215) onto the first holographic element (200) is transmitted through the first holographic element (200).

4. The display device (110) according to any one of the preceding claims,

wherein the polarizing element (205) is shaped as a polarizing filter and/or as a retardation element, in particular as a lambda/4 retardation layer.

5. The display device (110) according to any one of the preceding claims,

having a beam splitter (210) shaped for splitting a light beam (115; 115', 300), in particular wherein the beam splitter (210) is arranged between the first and the second holographic element (200, 215).

6. The display device (110) of claim 4,

wherein the beam splitter (210) is shaped for transmitting and/or reflecting the light beam (115; 115', 300) in dependence of polarization.

7. The display device (110) according to any one of the preceding claims,

has a projector unit (105) which is shaped to emit a light beam (115; 115', 300) in the light path to the first holographic element (200).

8. The display device (110) of claim 7,

wherein the projector unit (105) is shaped for adjusting and/or switching the polarization direction of the light beam (115; 115', 300), in particular wherein the projector unit (105) is configured for outputting the light beam (115; 115', 300) at different times with different adjustable polarization directions.

9. The display device (110) according to claim 7 or 8,

wherein the projector unit (105) is oriented with respect to the first holographic element (200) such that a light beam (115; 115', 300) emitted by the projector unit (105) is at least partially transmitted by the first holographic element (200).

10. A carrier element (100), in particular a carrier plate, having a display device (110) according to one of the preceding claims, in particular wherein the display device (110) is arranged between two plates (220, 225).

11. The carrier element (100) according to claim 10,

wherein the carrier element (100) is at least partially shaped as a plastic or glass plate.

12. A method (600) for displaying an image using a display device (110) for a vehicle according to any of the preceding claims, wherein the method (600) comprises the steps of:

-causing the light beam (115; 115', 300) to be incident (605) on the first holographic element (200) in a predetermined polarization direction;

-passing (610) said polarizing element (205) by said light beam (115; 115', 300); and

-reflecting (615) and/or transmitting the light beam (115; 115', 300) in the second holographic element (215) in relation to the polarization direction of the light beam (115; 300).

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