CN106054384B

CN106054384B - Viewing area display device for vehicle and method for displaying image in sight range of person

Info

Publication number: CN106054384B
Application number: CN201610229699.8A
Authority: CN
Inventors: T.维尔纳; R.菲斯
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2015-04-15
Filing date: 2016-04-14
Publication date: 2021-05-07
Anticipated expiration: 2036-04-14
Also published as: FR3035230B1; CN106054384A; DE102015206796A1; FR3035230A1

Abstract

The invention relates to a viewing zone display device (102) for a vehicle (100) for presenting images in the line of sight of a person. The viewing zone display device (102) has an imaging device (110) for providing a first partial image and a second partial image; an optical device (112) for projecting a first partial image along a first optical path (107) to a first eye region (105) of a first eye (104) that can be assigned to the person and a second partial image along a second optical path (207) to a second eye region (205) of a second eye (204) that can be assigned to the person; and means for reducing crosstalk between the first optical path (107) and the second optical path (207).

Description

Viewing area display device for vehicle and method for displaying image in sight range of person

Technical Field

The present invention relates to a viewing zone display device for a vehicle and a method for presenting an image in a sight line of a person.

Background

Head-up displays used in the area of vehicles image the image plane of the imaging unit onto a virtual image located in front of the vehicle by means of optical means.

DE 4004739 Al describes an optical system for the three-dimensional representation of information, with an optical element having a lens function, two light sources which are switched on and off alternately, and an information carrier.

Disclosure of Invention

The quality of the image presented in the case of using the viewing zone display device can be improved by: crosstalk between individual optical paths used to present an image is reduced.

A viewing zone display device for a vehicle for presenting images in the field of vision of a person is presented, having the following features:

an imaging device for providing a first partial image and a second partial image;

an optical device for projecting a first partial image along a first optical path to a first eye region that can be assigned to a first eye of a person and a second partial image along a second optical path to a second eye region that can be assigned to a second eye of the person.

An apparatus for reducing crosstalk between a first optical path and a second optical path.

A viewing area display device can be understood as a head-up display (HUD), in particular an autostereoscopic head-up display. The eye area of the person can be understood as the eye rim assigned to the eyes of the person. The imaging device can be understood as an imaging unit (PGU, image generation unit). The imaging device can comprise an imager for providing the first partial image and the second partial image or a first imager for providing the first partial image and a second imager for providing the second partial image. An optical device is to be understood as meaning an optical device, in particular a head-up optical device. The optical device can, for example, comprise a plurality of mirrors for deflecting light between the imager of the imaging device and the eye region. Furthermore, the windshield panel of the vehicle can, for example, be part of an optical device. In operation of the viewing zone display device, a person is able to perceive the first partial image by one eye of the person and the second partial image by a second eye of the person. The first partial image and the second partial image complement one another to form an image which is displayed in the region of the person's line of sight from the line of sight of the person. The optical paths of the two partial images can run closely next to one another. Thereby enabling crosstalk to be generated. Crosstalk can be understood as: the light rays passing through one of the light paths are coupled into the other of the light paths and pass along the light path to the eye region assigned to the light path. The means for reducing is configured to reduce or eliminate such crosstalk. In this regard, different embodiments of the device for reducing can be used, which can also be used in combination. The crosstalk can be reduced by: on the one hand, the coupling of light of a light path into a further light path is reduced or made difficult, and on the other hand, the light which has been coupled into the further light path via a light path is filtered out again. In an advantageous manner, the described principle for suppressing crosstalk can be applied to a viewing area display device in the form of an autostereoscopic display system.

According to one specific embodiment, the device for reducing crosstalk can have a first filter which is arranged and configured in the first light path in order to filter out light rays having the second characteristic. The device for reducing also has a second filter, which is arranged and configured in the second light path in order to filter out light rays having a first characteristic that differs from the second characteristic. The light rays having the first characteristic can be used to convey image information of the first partial image and the light rays having the second characteristic can be used to convey image information of the second partial image. The characteristics of the image can for example relate to the polarization or the spectrum of the light. If the light for transmitting the first partial image is not coupled into the second light path as desired, it can be filtered out using a second filter before reaching the second eye region. If the light for transmitting the second partial image is not coupled into the first light path as desired, it can be filtered out using the first filter before reaching the first eye region.

For example, the first characteristic can represent a first polarization and the second characteristic can represent a second polarization. The first filter can be a first polarization filter for filtering out light having the second polarization, and the second filter can be a second polarization filter for filtering out light having the first polarization. Light rays of different polarizations can be generated simply, so that in this way a feasible solution for avoiding the negative effects of crosstalk is achieved that can be realized simply.

In this case, the imaging device can be designed to provide the first partial image using light of the first polarization. Accordingly, the imaging device can be constructed so as to provide a second partial image using light of a second polarization. Accordingly, polarized light can be advantageously generated using a laser projector or a Liquid Crystal Display (LCD) that has been applied in conjunction with a viewing area display device.

Additionally or alternatively, the first characteristic can represent a first color spectrum and the second characteristic can represent a second color spectrum. Accordingly, the first filter can be a first interference filter for filtering out light rays having the second color spectrum, and the second filter can be a second interference filter for filtering out light rays having the first color spectrum. The color spectrum can have a plurality of individual colors. Thereby, the color spectrum can comprise light of different wavelengths. In this case, the individual colors comprised by the first color spectrum and thus the wavelengths comprised by the first color spectrum can differ from the individual colors comprised by the second color spectrum and thus the wavelengths comprised by the second color spectrum. The first interference filter can be designed to filter out the monochromatic colors comprised by the second color spectrum and thus the wavelengths comprised by the second color spectrum. Accordingly, the second interference filter can be configured to filter out the monochromatic colors comprised by the first color spectrum and thus the wavelengths comprised by the first color spectrum. In this way it can be ensured that the first eye region is reached only by light comprising the first color spectrum and the second eye region is reached only by light comprising the second color spectrum. The negative effects of crosstalk can thereby be reduced or eliminated.

In this case, the imaging device can be designed to provide a first partial image using primary colors of a first wavelength and a second partial image using primary colors of a second wavelength. In this case, the primary color of the first wavelength can be different from the primary color of the second wavelength. As primary colors, for example, red, green and blue can be used. In this way it is sufficient to define three wavelengths or wavelength ranges for each color spectrum, i.e. a total of six different wavelengths or wavelength ranges. It is thereby possible, for example, to use light with a first wavelength for the first partial image and light with a second wavelength, which is different from the first wavelength, for the second partial image for displaying the primary color red. Accordingly, light with a third wavelength can be used for the first partial image and light with a fourth wavelength, which is different from the third wavelength, can be used for the second partial image in order to display the primary color green. Finally, for displaying the primary color blue, light with a fifth wavelength can be used for the first partial image and light with a sixth wavelength, which is different from the fifth wavelength, can be used for the second partial image.

If the device for reducing crosstalk comprises a filter, the viewing zone display apparatus can advantageously have a tracking device for tracking the first filter for motion corresponding to the first eye region and the second filter for motion corresponding to the second eye region. In this way, it can be ensured that the filter remains in the beam path assigned to the person during operation of the viewing area display device even when the beam path is moved due to the movement of the person.

In addition or as an alternative to using a filter, the device for reducing cross-talk can have a first holographic optical function in an element for an imager of the backlit imaging device and a second holographic optical function in said element or a further element for the backlit imager. Diffraction effects that can be generated at the imager and that can cause crosstalk can be effectively impeded or reduced by such a backlight. The holographic optical function can also be matched to the diffraction characteristics of the imaging device. As the holographic optical function, for example, a hologram can be used. If the imaging device has a first imager for providing the first partial image and a second imager for providing the second partial image, a first holographic optical function for backlighting the first partial image and a second holographic optical function for backlighting the second partial image can be set. The imager can also be described as an imager. In order to illuminate the two eye frames, different optical functions are required, which can be implemented in both holograms, but can of course also be unified in a single hologram. In this way, the two optical functions can be implemented in different embodiments in the same element, but in two different holographic elements.

For example, the first holographic optical function can represent a hologram which is illuminated from the first eye region via the optical device and the imager during the recording of the hologram. Accordingly, the second holographic optical function can represent a hologram which is illuminated from the second eye region via the optical device and the imager during the recording of the hologram. The hologram can be photographed using an object wave (objektwell) and a reference wave. The object wave used can be formed by: the light is guided via the respective eye region, the optical device and the imager or the respective imager to the location at which the respective hologram is arranged during operation of the viewing zone display device. In this way, master holograms can be recorded in mass production, which master holograms are reproduced by means of a concatenated copy method. Thus, the first holographic function can represent the replicated first master hologram when using the concatenated copy method, and the second holographic function can represent the replicated second master hologram when using the concatenated copy method. In the case of using only one master hologram, the first holographic function and the second holographic function represent in a corresponding manner the master hologram that was replicated in the case of using the concatenated copy method. In an advantageous manner, it is not necessary in this way that each hologram installed in the last system has been exposed by the corresponding optical device. It is sufficient to create a master hologram by this exposure and to replicate it by concatenating the copies.

A corresponding method for presenting an image in the field of view of a person comprises the following steps:

providing a first partial image and providing a second partial image;

projecting a first partial image along a first optical path to a first eye region of a first eye which can be assigned to the person and a second partial image along a second optical path to a second eye region of a second eye which can be assigned to the person; and is

Cross-talk between the first and second optical paths is reduced,

the steps of the method can advantageously be carried out in the case of an apparatus using the mentioned viewing zone display device.

The step of reducing can be performed, for example, by filtering out light of a specific characteristic in a single light path or by a suitable backlight of the imaging device for providing the partial image.

Embodiments of the invention are illustrated in the accompanying drawings and specifically explained in the following description.

Drawings

In the drawings:

FIG. 1 is a vehicle with a viewing area display device according to one embodiment;

FIG. 2 is a vehicle with a viewing area display device according to one embodiment;

FIG. 3 is a view area display device according to one embodiment;

FIG. 4 is a view area display device according to one embodiment;

FIG. 5 is a schematic presentation of a viewing area display device, according to one embodiment;

FIG. 6 is a flow diagram of a method for presenting images, according to one embodiment;

FIG. 7 is a view area display device according to one embodiment;

FIG. 8 is a schematic illustration of an imaging apparatus for a viewing zone display device according to one embodiment;

FIG. 9 is a schematic illustration of an imaging apparatus for a viewing zone display device according to one embodiment;

FIG. 10 is a schematic illustration of an imaging apparatus for a viewing zone display device according to one embodiment;

FIG. 11 is a schematic illustration of an imaging apparatus for a viewing zone display device according to one embodiment;

FIG. 12 is a schematic display of a viewing area display device, according to one embodiment; and is

Figure 13 is a schematic presentation of a viewing area display device according to one embodiment.

Detailed Description

In the following description of advantageous embodiments of the invention, the same or similar reference numerals are used for elements which are illustrated in different figures and which function similarly, wherein repeated descriptions of such elements are omitted.

FIG. 1 illustrates a vehicle 100 with a viewing area display device 102 according to one embodiment. The driver is seated in the vehicle 100, only the driver's eyes 104 of which are shown in fig. 1. The driver's eyes 104 are located in an eye area 105, which is also described below as an eye box. The eye region 105 is thus understood to be the region in which the eye 104 is actually or in a hypothetical manner located. As the driver's head moves, then the eyes 104 move and the position of the eye area 105 tracks the movement of the eyes 104 accordingly. The viewing area display device 102 is designed to display a visible image for the driver on a virtual screen 106, which is located in the field of vision of the driver. To this end, the light is directed along the light path 107.

The viewing area display device 102 is designed as a heads-up display. The schematic structure of the viewing zone display device 102 shown in fig. 1 comprises an imaging apparatus 110 in the form of a PGU (image generating unit) and an optical apparatus 112 in the form of an optical device, also referred to as a HUD optical device. The imaging device 110 is also referred to as an imaging unit 110 hereinafter.

The head-up display 102 is designed to image the image plane of the imaging unit 110 onto a virtual image located in front of the vehicle 100 by means of the optical device 112. The driver thus perceives an enlarged image, which has been generated by the imaging unit 110. This image is superimposed on the driving scene and is located on the virtual screen 106 in a defined distance from the front window panel 114. Here, it is possible to realize the use of the LCD module as an element of imaging in the imaging unit 110. The front window panel 114 can also be interpreted as a part of the optical device 112.

The virtual image displayed is a magnified image of the display produced by the imaging unit 110. Thus, the HUD optics 112 possess a specific magnification. The necessary magnification increases with the distance of the virtual screen 106, since the image generated by the imaging unit 110 must be magnified more strongly in order to occupy the desired viewing area of the driver in a larger distance. For example, the virtual screen 106 can be located in a pitch of about 15 m.

As a virtual image, a marking or a character, for example, which emerges from the driver's view at the rear of the front window panel 114, can be displayed on the virtual screen 106 during operation of the head-up display 102.

FIG. 2 illustrates a vehicle 100 with a viewing area display device 102 according to one embodiment. This schematic diagram corresponds to the schematic diagram described with reference to fig. 1, wherein fig. 2 shows in principle the principle mode of operation of an autostereoscopic head-up display 102. Thus, the two

eyes

104, 204 of the driver are shown in fig. 2.

Eye 104 is located in eye region 105 and eye 204 is located in eye region 205.

The autostereoscopic HUD system 102 operates with separate partial images for the left and

right eyes

104, 204 by which a 3D effect similar to that known from cinema theatres can be produced. The imaging unit 110 has in addition already produced two partial images. The light rays of the partial images are then supplied to the

respective eye

104, 204 in a

smaller eye frame

105, 205 by the HUD optics 112. For this, two separate

optical paths

107, 207 are used.

FIG. 3 illustrates a viewing area display device 102 according to one embodiment. Here, it can refer to an embodiment of the viewing area display device 102 which is only schematically illustrated by means of fig. 2. Shown is a viewing area display device 102, exemplified by a HUD design for a magnifying smaller imager, a so-called imaging device. The imager of the imaging unit 110 virtually images through the four free-form mirrors 321, 322, 323, 324 and the windshield plate 114. The freeform mirrors 321, 322, 323, 324 and the windshield pane 114 can be interpreted as the optical device 112 of the viewing area display apparatus 102.

Fig. 4 shows a schematic presentation of the viewing area display device 102 according to one embodiment. Here, it can refer to the viewing area display device 102 described with the aid of fig. 2. It is shown that the viewing display apparatus 102 acts as a system subject to crosstalk, i.e. the system is manifested in crosstalk between the

optical paths

107, 207.

By scattering or diffraction at very different planes within the HUD system 102, a portion of the light for the eye 104 can be deflected in the direction of the other eye 204. Crosstalk from one eye 104 into the other eye 204 is generated. In order to block a portion of the light rays for the eye 104 from being deflected in the direction of the other eye 204, or in order to block light rays that have been deflected in the direction of the other eye 204 from contacting the eye 204, the optic zone display apparatus 102 is provided with a device for reducing crosstalk between the first light path 107 including light rays for the eye 104 and the second light path 207 including light rays for the eye 204, as described in detail below.

An important criterion for the quality of the stereoscopic display system 102 is an undesired crosstalk of the image information of one of the two eyes 104 into the other eye 204. This Crosstalk is referred to as Crosstalk (Crosstalk). An excessively large scale of crosstalk leads to excessive demands on the visual aspects such as discomfort, fatigue phenomena and can lead to a complete loss of the 3D impression.

Crosstalk interference can occur at different locations in an optical system and has different causes. First, the imaging unit 110 is susceptible to crosstalk interference when generating two different images of the autostereoscopic heads-up display 102. If, for example, a scattering surface is used for generating the two partial images, a cross-talk interference is generated in the wide eye box on the basis of the gaussian-like emission. The formation of crosstalk interference caused by diffraction effects at the imager 110 is also an important effect. LCD modules, for example, have a very narrow pixel grid (RGB sub-pixels in the range of about 30 μm) at high resolution. Such a grid acts diffractively as a grating and thus leads to higher orders of the eye-box which can produce noticeable crosstalk interference. Diffraction effects which produce similar crosstalk interference arise in direct imaging devices, for example in Digital Light Processing (DLP), in which a digital image is modulated onto the light beam, or in microlens arrays with small pitches (Pitch). The crosstalk interference thus generated is particularly difficult to eliminate, since it is generated directly at the imaged element 110 and must be suppressed without impairing the image information.

In the case of using a so-called apparatus for reducing crosstalk, crosstalk generated in the imaging unit to a partial image in the

wrong eye

104, 204 can be effectively reduced. In this case too, crosstalk interference caused by diffraction effects can be reduced in particular.

Fig. 5 shows a schematic presentation of the viewing area display device 102 according to one embodiment. As already explained, the viewing zone display device 102 is designed to project a first partial image through the first light path 107 in the direction of the first eye region 105 associated with the first eye and to project a second partial image through the second light path 207 in the direction of the second eye region 205 associated with the second eye, using an optical system. The viewing zone display device 102 has an imaging device in order to provide a first partial image and a second partial image.

The viewing zone display device 102 has means for reducing cross talk between the first optical path 107 and the second optical path 207. The reduction can be understood as: the crosstalk is stopped or reduced from the beginning, or at least already done. In this regard, the device for reducing as schematically illustrated in fig. 5 can have a plurality of

different elements

521, 523, 525, 527 which can be arranged at different positions, which can be used as such, individually or in combination.

According to one embodiment, the device for reducing comprises a

filter

521, 523 arranged in the

optical path

107, 207 between the imaging device 110 and the

eye region

105, 205.

In this case, the

filters

521, 523 can be integrated into the optical device 112 or arranged between the imaging device 110 and the optical device 112. The first filter 521 associated with the first light path 107 is designed to filter out light rays having a second property, which are used to represent a second partial image. The second filter 523 assigned to the second light path 207 is designed to filter out light rays having a first property, which are used to represent the first partial image. The first characteristic can be manifested as a first polarization of light used to present the partial image, and the second characteristic can be manifested as a second polarization of light used to present the partial image. In this case, the

filters

521, 523 can be designed as polarizing filters. Additionally or alternatively, the first characteristic can be represented as a first color spectrum and the second characteristic can be represented as a second color spectrum. In this case, the

filters

521, 523 or the

additional filters

521, 523 can be designed as interference filters.

According to one embodiment, the viewing zone display apparatus 102 includes a tracking device 530 configured to track the

filters

521, 523 if this is necessary based on the change in position of the

eye regions

105, 205. The tracking device 530 is implemented, for example, as a mechanical device configured to perform tracking in response to receipt of a control signal.

According to another embodiment, the apparatus for reducing further comprises holographic

optical elements

525, 527 in addition to or instead of the

filters

521, 523. Here, a first holographic optical element 525 is provided for the imager of the backlighting imaging device 110 which is provided for providing the first partial image, and a second holographic optical element 527 is provided for the imager of the backlighting imaging device 110 which is provided for providing the second partial image. The holographic

optical elements

525, 527 can be designed as separate components or as regions of the only component.

Thus, to reduce crosstalk, three principles are followed. The core of the first principle is to separate the polarization of the two partial images and to use

filters

521, 523 designed as polarization filters in the optical irradiation process, which provide the respective eye with only the polarization of one partial image. The second principle works similarly, but instead of splitting the polarization, a separation based on a different wavelength is used. The core of the third principle is the use of holographic optical elements 525, 527 (HOE) as backlight for the imager 110 in order to compensate the diffraction properties of the imager 110 with a corresponding phase grid (phasegitter). Thereby, scattering of light of the backlight in narrow angles is achieved, resulting in a low degree of crosstalk.

The reduction of the degree of crosstalk interference contributes positively to the image quality of the display system. The reduction of crosstalk hinders an excessive demand in the visual aspect and reduces the fatigue phenomena associated with the longer viewing of stereoscopic images. This enables comfortable and long-term use of the display system 102 and significantly improves comfort. On the other hand, the contrast of the individual partial images is increased by reducing crosstalk. The functions of conventional optical elements can be summed by holographically operating

elements

525, 527. Additionally, virtual light sources can be produced at arbitrary intervals, which exceed the spatial dimensions of the structure. The use of

holograms

525, 527 thus effectively reduces the construction space.

Holograms

525, 527 represent the functionality of a hologram, which can be implemented in separate elements or in one element according to different embodiments. If the

holographic functions

525, 527 are implemented jointly in one element, for example in the imager 110, the two

holographic functions

525, 527 can be illuminated from different directions in the operation of the viewing zone display device 102. The first eye region 105 can be served if the elements with

holographic functionality

525, 527 are illuminated from a first illumination direction. However, if the elements with

holographic functions

525, 527 are illuminated from the second illumination direction, the second eye area 205 can be served.

FIG. 6 illustrates a flow diagram of a method for presenting an image, according to one embodiment. The image can be displayed, for example (as shown by means of fig. 2), on a virtual screen in the field of vision of the person. In this case, in step 601, first of all two partial images are provided, for example in the case of the imaging device shown with the aid of fig. 2. In a step 603, which is carried out parallel in time to this, one of the partial images is conducted via a first optical path to a first eye of the person and the other of the partial images is conducted via a second optical path to a second eye of the person, for example if an optical device as shown in fig. 2 is used. In step 605, which is carried out in parallel in time, crosstalk between the optical paths is prevented or at least partially prevented, for example when the device for reduction shown with reference to fig. 5 is used.

FIG. 7 illustrates a viewing area display device 102 according to one embodiment. Shown is an example of a HUD design for magnifying a small imager. Illustrated is the

first element

110, 321, 322 of the viewing display 102, which has been described with the aid of fig. 3, relative to the direction of the

light path

107, 207. Here, since the

paths

107, 207 for the two partial images for the left and right eyes are spatially completely separated, the polarization filters 521, 523 can filter out the crosstalk light into the wrong eye.

Instead of

polarizing filters

521, 523, interference filters can be used in a corresponding manner, when light of different color spectra are used for the purpose of transmitting partial images through the

paths

107, 207.

Fig. 8 shows a schematic illustration of an imaging device 110 for use in a viewing zone display apparatus according to an embodiment. Shown is a schematic example of an imaging device 110 in the form of a PGU with two

LED projectors

810, 811. The

LED projectors

810, 811 can be interpreted as imagers of the imaging device 110. The light rays of the two

projectors

810, 811 are correspondingly polarized by means of polarization filters 821, 823, respectively. The polarizing filter 821 assigned to the first LED projector 810 is implemented as a +45 ° polarizing filter and the polarizing filter 823 assigned to the second LED projector 811 is implemented as a-45 ° polarizing filter. The partial images of the

LED projectors

810, 811 polarized at 90 ° to one another can then be filtered out in the optical system in the wrong eye by separate imaging paths, for example if the polarizing filter shown in fig. 7 is used. Element 825 is embodied as a scattering surface or a microlens array.

Fig. 9 shows a schematic illustration of an imaging device 110 for use in a viewing zone display apparatus according to an embodiment. Shown is a schematic example of an imaging device 110 in the form of a PGU with two

LED projectors

910, 911. The

laser projectors

910, 911 can be interpreted as imagers of the imaging device 110. The two partial images have been polarized by using the

laser projectors

910, 911. The

projectors

910, 911 are designed so that the images of the projectors are 90 ° polarized with respect to each other. The polarized partial images can then be filtered out in the optical arrangement in the wrong eye by separate imaging paths, for example if the polarizing filter shown in fig. 7 is used.

Fig. 10 shows a schematic illustration of an imaging device 110 for use in a viewing zone display apparatus according to an embodiment. A schematic example of an imaging device 110 in the form of a PGU is shown for which two

LCDs

1010, 1011 are superimposed. The

LCDs

1010, 1011 can be interpreted as imagers of the imaging device 110. The partial images are linearly polarized by the two

LCDs

1010, 1011. The respective orientation of the polarization filters located on the LCD module can produce partial images which are polarized at 90 ° to one another and can be filtered out by optical means, for example if the polarization filter shown in fig. 7 is used. Each of the LCD modules includes a scattering surface or microlens array 825 and a light emitting diode 1025. The imaging unit further comprises a beam splitter 1030.

Fig. 11 shows a schematic illustration of an imaging device 110 for use in a viewing zone display apparatus according to an embodiment. Shown is a schematic example of an imaging device 110 in the form of a PGU with two light-emitting

diode devices

1110, 1111, with which a small imager 1140, here for example a DLP chip, i.e. a chip for modulating a digital image to a light beam, is directly imaged. Each of the light emitting

diode devices

1110, 1111 includes a light emitting diode 1142, a polarizing filter 1044, a collimating lens 1146, a microlens array 1148, and a projection lens 1150. The polarizing filter 1144 of the light emitting diode device 1110 is implemented as a +45 ° polarizing filter, and the polarizing filter 1144 of the light emitting diode device 1111 is implemented as a-45 ° polarizing filter. By means of the LED light polarized by the pass filter, the two partial images of the imaging device 110 are likewise polarized by 90 ° to one another and can be filtered out in the subsequent optics in the wrong imaging path, for example if the polarizing filter shown in fig. 7 is used.

Hereinafter, embodiments for reducing crosstalk by laser irradiation and a polarization filter are described in detail with the aid of fig. 3 to 11.

If the imaging device 110 uses polarized light when generating partial images for the left and right eyes, crosstalk can be hindered by: the corresponding wrong polarization is filtered from the optical path of the light for one eye. For this purpose, an optical design is used, in which the two

light paths

107, 207 for the partial images are completely separated at least one point.

In fig. 3, a drawn HUD optic 112 for a small imager is shown. This imager is enlarged and virtually imaged by four free-form mirrors 321, 322, 323, 324 and windshield plate 114. A cut-away portion of such a HUD system is shown in fig. 7. Shown are the imager of the imaging unit 110, the first two

mirrors

321, 322 and additionally incorporated polarization filters 521, 523. In this embodiment, the

optical paths

107, 207 of the two partial images are also completely separated from one another. This enables the positioning of two

polarizing filters

521, 523 into the

paths

107, 207 of the

small eyeboxes

107, 207 for one eye each. Cross talk of light into the eye-

box

107, 207 of the other eye is effectively filtered.

To produce the two polarization directions, LEDs with further polarization filters 821, 823, 1044 can be used, for example, as backlights of the imager in the imaging device 110 in the form of a PGU. Another principle here is to use a laser backlight which, by itself, has been polarized beforehand, as described with the aid of fig. 9. In this case, the efficiency of the overall system is further increased, since a large useful light fraction is not filtered.

The tracking of the eye-

frames

105, 205 in case of head movements of the user also forces the tracking of the two

polarizing filters

521, 523. However, the area to be tracked of this

filter

521, 523 is small and must be implemented only in one axis. The time requirements for such tracking are also below the requirements for e.g. spectacle frame tracking itself, since the

polarizing filters

521, 523 possess well-spaced apertures and have some overlap with respect to the spectacle frame beam. For tracking, a tracking device 530, schematically shown in fig. 5, can be used.

The imaging device 110, also referred to as an imaging unit, can be variously implemented. In principle, the described solution can be used in each imaging unit 110, which can provide two partial images in different polarizations. In this case, the radiation of the display of the imaging unit 110 is adapted accordingly to the optical arrangement used for the imaging HUD mirrors 321, 322, 323, 324.

According to one embodiment, an imaging unit 110 is used, which is realized by two

projectors

810, 811 projecting onto a scattering surface or microlens array 825, as shown in fig. 8. Here, the two

projectors

810, 811 are positioned in such a way that the two partial images are emitted in different directions of the projection surface. The two partial images thus produced can be polarized at 90 ° to one another by using

polarization filters

821, 823. The partial images thus polarized take completely

separate paths

107, 207 in the subsequent imaging optics at least one point. If a partial image flows into the

wrong path

107, 207 due to crosstalk interference, it can be filtered out there.

In the case of the use of

laser projectors

910, 911, the polarization properties of the laser light can be directly utilized in the respective design of the

projectors

910, 911, as shown in fig. 9. Here, the

projectors

910, 911 can also be implemented as flying spot projectors.

A possible solution for an LCD module based imaging unit 110 is shown in fig. 10. Here, the two

LCDs

1010, 1011 are backlit by means of a beam splitter 1030 in such a way that they project two partial images for the stereoscopic view. The backlight is formed by means of the LED light rays in such a way that the two partial images are emitted in slightly different directions after the beam splitter 1030. The corresponding partial images are polarized in a natural manner by the

LCDs

1010, 1011. If the polarization of the

LCDs

1010, 1011 is designed accordingly, partial images polarized at 90 ° to one another are realized, which are then filtered out in the subsequent optical device.

Likewise, a direct imaging scheme with a small imager 1140 can be implemented using polarized partial images. Fig. 11 shows an example of this, in which a DLP chip is imaged as imager 1140. The backlight of the imager 1140 is done from two different directions to realize two partial images. Here, the light of the LED 1142 is polarized and collected by the collimating lens 1146. After the homogenization phase based on the microlens array 1148 and the projection lens 1150, the light is directed to the imager 1140.

According to another embodiment, an imager scheme is implemented in which two liquid crystal on silicon (LCoS) chips, i.e., two liquid crystals on a silicon substrate, are illuminated accordingly.

In general, the proposed solution can be applied to various imaging units. In this case, the partial images need not be polarized at ± 45 °. However, it is advantageous to polarize each other at 90 °, since the two partial images are thus effectively separated from each other. The use of ± 45 ° additionally provides the advantage that the windshield panel 114 reflects the two partial images with almost the same intensity and the two partial images thus remain equally bright. However, the actual design can also differ from this.

As an alternative to the filtering based on the polarization filters 521, 523 shown in fig. 7, interference filters can be used, if the primary colors of the partial images are respectively spectrally offset from one another for both eyes. The image for the left eye then uses a different wavelength for the red, green and blue than the other partial images. For this purpose, laser irradiation with a narrow frequency width is suitable. The system is then operated with six different wavelengths. For this purpose, laser displays with, for example, up to six different wavelengths and associated interference filters can be used. In this way crosstalk suppression can be performed by the interference filter. The arrangement of the interference filter can correspond to the arrangement of the polarization filter described.

Fig. 12 shows a schematic presentation of a viewing area display device 102 according to one embodiment. The viewing zone display device 102 is used to capture holographic optical elements (which according to this embodiment are holographic functions, also described below as hologram 525). The recorded hologram 525 can then be used during operation of the viewing zone display device 102 to backlight an imager 1260 of the imaging device 110, for example to backlight the imager 1260 in the form of a DLP chip or LCoS chip.

To capture the hologram 525, the object wave 1261 and the reference wave 1262 are conducted to the hologram 525. Object wave 1261 is generated by illumination 1264, whose light is conducted through optics 112 and imager 1260 to hologram 525, which can be considered part of imaging device 110 after its capture.

Thus, fig. 12 shows an arrangement of structures for capturing a hologram 525 by an imager 1260, for example in the form of a DLP chip. Illumination 1264 is effected from the location of the eyebox and is conducted through the imager 1260 and the optics 112 to the hologram 525. In combination with the reference wave 1262, a certain phase pattern is formed, which is embossed into the hologram 525.

The hologram 525 produced in this way can be used as a master hologram, which can be replicated using a concatenated copy method.

Fig. 13 shows a schematic presentation of a viewing area display device 102 according to one embodiment. Here, it can refer to the viewing area display device described with reference to fig. 12, to which illumination 1366 is applied in order to generate a backlight for an imager 1260 of the imaging device 110 by means of the hologram 525, so that the partial image is conducted via the beam path 107 guided by the optical device 112 to the eye region 105 in the form of an eye rim. In this way, the light rays propagating through the optical path 107 can be interpreted as reconstruction (Rekonstrukton).

Thus, for example, a hologram 525 recorded as described with reference to fig. 12 can be projected by: the illumination 1366 is performed from the other side. The object wave applied during the recording is thereby generated in the opposite direction, and the eye box 105, from which the illumination is performed during the recording, is formed again by the imager 1260 and the optical device 112.

With the help of fig. 5 and 12 and 13, cross-talk reduction based on HOE backlights is described below in different embodiments.

The imager 1260 of the display system additionally possesses diffractive properties, which are produced in very small structures in the first place. A conventional high-resolution LCD 1260 has pixels which already have a diffractive effect due to the grid structure of the arrangement of the pixels. Typically, the grid is resolved more finely than the true illustrated pixel size by a factor of 3, since a single pixel comprises three sub-pixels for red, green and blue (sub-pixels about 30 μm). Likewise, an imager imaging device 1260, such as an LCoS chip or DLP chip, operates with a pixel size in the diffraction range (about 10 μm).

In backlights with a large range of angles (such as are used in normal displays), such diffraction effects enter the background because the diffraction orders of different angles will overlap. However, the narrower the illumination angle, the more the diffraction effect appears. In particular, in autostereoscopic displays it is important to realize a narrow emission cone at the PGU display 1260, since the image information for the two eyes should be clearly separated from each other. The higher diffraction orders of the imager structure generate diffracted light, which can be cross-talk into the wrong eye box. This makes image quality difficult, cross-talk occurs, and contrast is reduced.

A way to reduce this effect is to use filters in the light path, said use being the principle already described.

A further possibility is to use the holographic optical element 525 as a backlight for phase patterns suppressing higher diffraction orders. This can be achieved by a corresponding hologram 525.

Such a hologram 525 can be produced by reverse shooting through an imager 1260 as shown, for example, in fig. 12. Here, the photographing is performed by the optical device 112 to be used later and the imager 1260 itself. A specific phase pattern is thus impressed into the hologram 525 together with the reference wave 1262, which again produces the object wave 1261 exactly in a later projection. Then there are no higher diffraction orders anymore, because they are eliminated by the phase pattern of the hologram 525. The huygens fundamental wave generated in the grating of the diffractive element 1260 then modulates differently in different directions.

In the projection of hologram 525, as shown in FIG. 13, object wave 1261 is now generated in reverse by: the illumination 1366 is positioned on the other side of the hologram 525. In this fashion, the eye box 105 is re-imaged by the imager 1260 and the optical device 112.

Similar to the recording by the optical device 112, a corresponding hologram 525 can be calculated and recorded directly mechanically. The depicted hologram 525 can be replicated advantageously at the expense of connecting copies.

According to another embodiment, instead of the broadcast hologram 525 recorded in fig. 12, a hologram operating in reflection is used. The holograms are characterized by sharper spectral separation and sharper spaced radiation angles.

At this time, the second eye frame can be formed by another independent hologram 527, which is photographed and illuminated similarly to the first hologram 525.

The

holograms

525, 527 are in principle also capable of recording different phase patterns for the three primary colors red, green and blue. The

holograms

525, 527 can thus be used for the three primary colors of the

eyeboxes

105, 205 accordingly.

The

holograms

525 and 527 are imaged by laser light, but the

holograms

525 and 527 thus imaged can also be projected by using LED light as illumination 1366. The basic function does not disappear here, but the spectral width of the LED leads to a widening or erosion of the

eye rim

105, 205 produced in this way to some extent. The extent of erosion at the edge of the

eye rim

105, 205 is dependent primarily on the spectral width of the LED. The solution for holding the

eye frame

105, 205 still narrower is to use a much narrower eye frame at the time of the recording than is to be reconstructed later. Furthermore, filters or LEDs using a spectrum optimized to narrow frequency characteristics can be considered.

Claims

1. A viewing area display device (102) for a vehicle (100) for presenting images in the line of sight of a person, with the following features:

an imaging device (110) for providing a first partial image and a second partial image which are completely independent;

an optical device (112) for projecting a first partial image along a first single optical path (107) to a first eye region (105) that can be associated with a first eye (104) of the person and a second partial image along a second single optical path (207) to a second eye region (205) that can be associated with a second eye (204) of the person; and

an apparatus for reducing crosstalk between a first optical path (107) and a second optical path (207).

2. The viewing zone display device (102) according to claim 1, in which the apparatus for reducing crosstalk can have a first filter (521) arranged and configured in the first light path (107) so as to filter out light rays having the second characteristic, and a second filter (523) arranged and configured in the second light path (207) so as to filter out light rays having the first characteristic different from the second characteristic.

3. A visual region display device (102) according to claim 2 in which the first characteristic represents a first polarization and the second characteristic represents a second polarization and the first filter (521) is a first polarization filter for filtering out light having the second polarization and the second filter (523) is a second polarization filter for filtering out light having the first polarization.

4. The viewing zone display apparatus (102) according to claim 3, in which the first imaging device is configured to provide the first partial image using light having a first polarization and the second imaging device is configured to provide the second partial image using light having a second polarization.

5. The viewing zone display device (102) of claim 2 in which the first characteristic represents a first color spectrum and the second characteristic represents a second color spectrum, and the first filter (521) is a first interference filter for filtering out light having the second color spectrum, and the second filter (523) is a second interference filter for filtering out light having the first color spectrum.

6. The viewing zone display device (102) according to claim 5, in which the imaging device (110) is configured to provide a first partial image if a primary color of a first wavelength is used and a second partial image if a primary color of a second wavelength is used, wherein the primary color of the first wavelength is different from the primary color of the second wavelength.

7. The viewing zone display device (102) according to any one of claims 2 to 6 with a tracking device (530) for tracking the first filter (521) in correspondence with the motion of the first eye region (105) and the second filter (523) in correspondence with the motion of the second eye region (205).

8. The viewing zone display device (102) according to claim 1, in which the means for reducing cross talk has a first holographic optical function in an element (525) for adding backlighting to an imager (1260) of said imaging apparatus (110) and a second holographic optical function in said element (525) or a further element (527) for adding backlighting to an imager (1260) of said imaging apparatus (110).

9. The viewing zone display device (102) of claim 8 in which the first holographic optical function represents a hologram that is illuminated from the first eye region (105) through the optical apparatus (112) and imager (1260) during capture of the hologram, and in which the second holographic optical function represents a hologram that is illuminated from the second eye region (205) through the optical apparatus (112) and imager (1260) during capture of the hologram.

10. The viewing zone display device (102) of claim 9 in which the first holographic function and the second holographic function represent at least one replicated master hologram using a concatenated copy method.

11. A method for presenting an image in a line of sight of a person, wherein the method comprises the steps of:

providing a first partial image and a second partial image which are completely independent;

projecting a first partial image along a first single optical path (107) to a first eye region (105) that can be associated with a first eye (104) of the person and a second partial image along a second single optical path (207) to a second eye region (205) that can be associated with a second eye (204) of the person; and

crosstalk between the first optical path (107) and the second optical path (207) is reduced.