DE102015116408A1 - Device for data projection - Google Patents

Abstract

There are described devices and methods for data projection in which color fringes can be avoided, for example by using a holographic ground glass, and / or image impairments can be avoided by a zeroth order of scattering, for example by an oblique arrangement of the ground glass or by using a holographic screen ,

Description

The present application relates to devices for data projection, in particular for data input, in particular for so-called head-up displays (HUDs). For example, the present application relates to such methods and devices which can be used in vehicles, especially in motor vehicles.

Generic devices for data projection, in particular for data reflection are increasingly used to provide data to a user in a simple manner. The term "data" is to be understood generally, mirrored data may include, for example, images, videos, symbols, characters and / or numbers.

One field of application of such data-reflecting devices is the vehicle sector, e.g. a driver of a vehicle, such as a driver of an automobile, to provide data while driving. This can be done, for example, by appropriate elements, e.g. in the form of a so-called head-up display, in a windshield of a vehicle, whereby the driver does not have to direct his gaze to a display, for example, a combination instrument to obtain data, but can essentially perceive this data without his gaze essential to turn away from the road.

Such devices are for example in a general manner from the DE 10 2008 039 737 A1 known. Here, a holographic optical element in a windshield for providing reflection to the human eye is proposed, the concepts being explained in particular for oblique windshields of passenger cars.

Further examples of data reflection, which can also be used for automotive applications, for example, are known from US Pat WO 2014/115095 A2 known. A holographic screen is used, and depending on the distance of this screen from a human eye, a special contact lens is needed to easily focus on that screen.

In some such devices, a ground glass is used to create a scattering intermediate image. Such a ground glass can be used in transmission or in reflection. The scattering on a microstructure of a conventional ground glass is based on the physical effect of the diffraction and is thus wavelength-dependent. The use of a conventional ground glass, for example of sandblasted glass, therefore leads to a color fringe of the intermediate image.

Holographic optical elements in a windshield, also referred to as holographic head-up displays, mean that they can image the intermediate image generated by the ground glass holographically as a virtual image behind the windshield. Wavelength-selective volume holograms used for this purpose diffract the light of one or more specific discrete wavelengths into a desired solid angle where the observer's eye may be located. This solid angle is also called Eyebox.

If the intermediate image generated by a projector is not scattered efficiently enough by the ground glass screen, an unscattered zeroth order remains, which directly corresponds to transmitted light or reflected light from the projector. In conventional designs, this unwanted zeroth order is also accepted by the head-up display and can lead to significant quality degradation of the virtual image as it overlays it.

It is therefore an object to provide devices and ground glass in which color fringes are avoided and / or in which quality losses are reduced by the zeroth order of inter-screen projection. This object is achieved with a device according to claim 1, a ground glass according to claim 3, a ground glass according to claim 5 and a device with such a ground glass according to claim 10. The subclaims define further embodiments.

According to a first aspect, there is provided a data projection apparatus comprising:
a diffusing screen,
a projector for projecting data onto the diffusing screen, and
at least one further optical component for imaging an intermediate image produced by the diffusing screen to an eye of an observer,
wherein the diffusing focusing screen is positioned relative to the projector such that the projector illuminates the diffusing screen obliquely at an angle other than 90 ° so that unscattered light from the screen does not reach the observer's eye.

Such an arrangement of a ground glass can suppress a zero-order influence.

For example, in the first aspect, the ground glass is so inclined to one Incident beam arranged by a projector that a zero-order beam does not or not significantly to a head-up display, such as a holographic head-up display, passes.

The diffusing screen may include a roughened glass mat.

According to a second aspect, there is provided a ground glass for a data projection apparatus, comprising:
a holographic structure, wherein the holographic structure is arranged to scatter at least two different wavelengths, the holographic structure being further configured to generate equal scattering angles for each of the at least two wavelengths independent of the wavelength.

By using such a ground glass color fringes can be reduced.

In the second aspect, therefore, e.g. a holographic focusing screen with holograms for different wavelengths, preferably a red, a green and a blue wavelength used. The holograms are matched to one another such that scattering angles are substantially the same, whereby the formation of color fringes can be avoided.

The holographic structure may be arranged to scatter the at least two different wavelengths in a direction different from a direction of unscattered light, e.g. at least 10 °, at least 20 ° or at least 30 °.

According to a third aspect, there is provided a ground glass for a data projection apparatus, comprising:
a holographic structure, wherein the holographic structure is arranged to diffuse light having at least two different wavelengths, the holographic structure being arranged to diffuse the at least two wavelengths in a direction different from a direction of unscattered light, eg by at least 10 °, at least 20 ° or at least 30 °, so to speak to provide a directional "scattering lobe".

By using such a directional scattering lobe, it is possible to avoid or at least alleviate the aforementioned problem with respect to zero order beams.

The above focusing screens may be transparent for wavelengths outside the at least two wavelengths.

The ground glass can have a respective holographic layer for each of the at least two wavelengths.

The ground glass can comprise a volume hologram and / or a surface hologram.

The at least two wavelengths may include a wavelength in the red region, a wavelength in the green region and a wavelength in the blue region, so that the ground glass is usable for the projection of colored images with an RGB projector.

In addition, a data projection apparatus is provided, comprising:
a ground glass as described above,
a projector for projecting data onto the screen, and
at least one further optical component for directing an intermediate image generated at the ground glass to an eye of an observer.

The projector may be configured to project based on a wavelength in the red region, a wavelength in the green region, and a wavelength in the blue region (RGB projector).

The at least one further optical component may comprise a holographic element, wherein the holographic element is arranged to generate a virtual image for viewing by the eye.

The at least one further optical component may comprise a component arranged in a window of a vehicle.

The device can be designed as a head-up display or as an image projector.

Hereinafter, various embodiments of the present invention will be explained in more detail with reference to the accompanying drawings. Show it:

1 1 a schematic representation of a device for data projection, in particular data reflection, according to an exemplary embodiment,

2 a device for data input according to an embodiment,

3 a device for data reflection according to a further embodiment,

4 a device for data input according to a further embodiment, and

5 a representation for illustrating the manufacture of a holographic focusing screen for use in embodiments.

In the following, various embodiments will be explained in detail. These embodiments are merely illustrative and are not to be construed as limiting. For example, embodiments having a variety of features, elements, and details are described, which should not be construed as requiring all of these features, elements, or details for implementation. Rather, in other embodiments, some of the elements, features, and details may be omitted and / or replaced by alternative features, elements, and details. Elements, features and details of various embodiments may be combined.

In 1 is a schematic representation of a device for data projection, for example, for data reflection in a vehicle shown. The device of 1 includes a projector 10 , which data to be displayed on a screen 11 projected to produce an intermediate image. The projector 10 may be in particular a projector, which for the production of color images two or more different wavelengths, in particular three wavelengths, connects. The three wavelengths preferably comprise a red, a green and a blue wavelength (RGB projection). For this purpose, for example, the ground glass 11 be scanned with three lasers of appropriate colors. The intermediate image is then removed from the ground glass 11 about other components 12 to one or both eyes 13 imaged by a user. The Elements 12 For example, they may include imaging optical components such as lenses or holographic elements. In one embodiment, the elements comprise 12 a head-up display, which may be formed for example by a holographic element provided in or on a windshield of a vehicle.

The arrangement of components in 1 one another is merely schematic and not restrictive. While in the embodiment of the 1 the screen 11 works in transmission, in other embodiments, a ground glass 11 to be used in reflection.

In a first aspect, the screen is 11 from the projector 10 illuminated at an angle (different from the illustrated vertical illumination), so that a zeroth order (essentially unscattered light) from the ground glass 11 not or not essential to the eye 13 arrives. In a second aspect, the ground glass is 11 a holographic focusing screen which has holograms, for example volume holograms or surface holograms, for different colors (for example red, green, blue). The design of the holograms can then be chosen so that the dispersion for the different colors is the same, so that no color fringes form.

In a third aspect, a holographic focusing screen is used, which is a "scattering lobe" in the direction of the other optical elements 12 which is designed so that a possibly occurring zeroth order is not to the eye 13 arrives. In other words, scattering angles of the holograms are optimized accordingly so that the scattering takes place at least to a very large extent in a desired direction. The various aspects will now be described with reference to the 2 to 4 explained in more detail with concrete examples.

To avoid repetitions wear in the 2 to 4 Corresponding elements the same reference numerals and will not be explained in detail several times.

2 shows a head-up display according to an embodiment, which is an example of the above-mentioned first aspect. In the embodiment of the 2 is a projector 20 provided, which as for the projector 10 of the 1 can be configured, for example, can emit red, green and blue light, or in some other way project desired data, for example by conventionally known for projectors techniques such as by means of a micromirror device (DMD) or the like. The projector 20 projects an image onto a screen 21 which in the case of 2 a conventional ground glass, such as sandblasted glass may be. Here is the screen 21 obliquely to an axis, which through the projector 20 defined, or, in other words, the projector 20 Illuminates the screen 21 at an angle 22 (in 2 , as usual in optics, drawn to the vertical). The intermediate image corresponding to that of the ground glass 21 scattered light reaches a windshield 24 , which at least in a partial area, for example in an area 25 , has integrated a deflection optics as a head-up display. For example, in the area 25 be arranged an optic, as for example in the cited prior art or - as a holographic element - in the German Patent Application 10 2015 101 687.7 describe is. Through the optical element 25 this will be on the screen 21 projected image on a virtual image 26 imaged by a viewer (represented by an eye 27 ) within an eyebox. In that area 25 In particular, an imaging hologram can be arranged. Such a hologram in the area 25 may also have corresponding holograms or holographic functions for different wavelengths used, for example red, green and blue. A device like the one in 2 shown, for example, as a head-up display for a motor vehicle with the windshield 24 be used.

A zeroth order, ie one through the ground glass 21 passing beam, in 2 With 23 however, does not reach the area 25 and thus will not ultimately be of the eye 27 detected. Thus, the unscattered zeroth order can be suppressed or at least reduced.

A disadvantage of the device 2 It is that only a relatively small fraction of the light intensity can be used for the head-up display.

One way to overcome this disadvantage would be to use a specially adapted high-efficiency ground glass with virtually zero order. However, conventional classical lenses with such properties scatter relatively strongly depending on the wavelength, in particular blue light stronger than red light, which in turn would lead to comparatively strong color fringes.

With reference to the 3 and 4 arrangements are now being discussed with which such disadvantages can be avoided.

In 3 is a head-up display according to an embodiment shown in which a holographic screen 30 is used. The holographic screen 30 is doing by a projector 20 illuminated in reflection, being from the screen 30 backscattered light in turn into an area 25 is directed with a corresponding deflection optics, such as a holographic element on a windshield. Apart from the use of the holographic screen 30 and the use of the ground glass in reflection corresponds to the embodiment of 3 the embodiment of the 2 ,

The projector 20 can in the embodiment of 3 for example, the ground glass 30 with a variety of different colors, for example with a red, a green and a blue laser beam. The holographic focusing screen can then have surface and / or volume holograms for the corresponding colors. Thus, three discrete holographic scattering functions for the three different colors can be realized. These three discrete holographic scattering functions can be realized in one layer, but also in three separate layers. For such layers, for example, a photopolymer may be used in a film which is appropriately exposed or another volume holographic layer.

With such a design for several discrete wavelengths, for example three discrete wavelengths, identical scattering angles for the different wavelengths can be realized, so that substantially no color fringes (or even no color fringes with exact fabrication) occur.

In addition, a scattering direction (scattering lobe) of the ground glass 30 be set so that most of the light is in the direction of the area 25 is scattered. Thus, a comparatively high efficiency can be achieved.

In this case, the geometric arrangement may be selected such that a theoretically occurring zero order does not belong to the range 25 arrives. For example, in this case, the scattering direction of the ground glass 30 differ by at least 10 °, preferably by at least 20 ° or at least 30 °, from a direction of zero order.

The production of the holographic ground glass described can be effected in an analogous manner, ie by holographic exposure of a photosensitive material (production of a master) or by optical replication of such a master. A holographic focusing screen in transmission (eg 40 in 4 ) with a desired preferred direction of the scattering lobe can be as in 5 described described. On a holographic layer (photosensitive material) 50 falls a spherical wave 52 a coherent laser 51 , Additionally applies to this layer 50 a diffuse scattered wave 53 with a certain preferred direction, via which the desired preferred direction of the scattering lobe can be determined. Such exposure of the layer 50 can be done separately for each desired wavelength.

The scattered wave 53 can be by means of scattering on a conventional ground glass (or any scattering body) or by means of an optoelectronic device Lcos, DMD, phase modulator or similar. produce.

The preparation of the holographic ground glass in reflection (eg 30 in 3 ) can suitably - only that here are the two waves 52 . 53 from different sides to the holographic layer 50 fall.

In 4 is a modification of the embodiment of 3 with a holographic screen 40 , which is operated in transmission. Apart from this difference, the embodiment corresponds to the 4 the embodiment of the 3 , and the screen 40 can with regard to their properties in terms of color fringes and / or direction of a scattering lobe as above for the ground glass 30 be set up explained.

The in the 2 to 4 shown angle arrangements are only illustrative and may vary. For example, the angles shown may be different, and / or the arrangement may also be realized mirrored on a horizontal line.

While in the 2 to 4 Head-up displays used in windshields as an example, the techniques illustrated, in particular the focusing screens of the 3 and 4 and / or the oblique illumination of the ground glass 21 of the 2 also applicable in other projection systems with scattering matt-glass-generated intermediate images, for example in despeckers with diffuser lenses, for example rotating or otherwise moving diffusers, or projection screens, for example for cinema applications.

The illustrated embodiments are thus not to be construed as limiting.

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 102008039737 A1 [0004]
• WO 2014/115095 A2 [0005]
• DE 102015101687 [0041]

Claims (14)

A data projection apparatus comprising: a diffusing focusing screen ( 11 ; 21 ), a projector ( 10 ; 20 ) for projecting data onto the diffusing screen ( 11 ; 21 ), and at least one further optical component ( 12 ; 25 ) for imaging a through the diffusing screen ( 11 ; 21 ) generated intermediate image to an eye ( 13 ; 27 ) of a viewer, wherein the diffusing screen ( 11 ; 21 ) relative to the projector ( 10 ; 20 ) is arranged such that the projector ( 10 ; 20 ) the diffusing screen ( 11 ; 21 ) at an angle ( 22 ) not equal to 90 °, so that unscattered light ( 23 ) from the ground glass not to the eye ( 27 ) of the observer. Apparatus according to claim 1, wherein the diffusing screen ( 11 ; 21 ) comprises a roughened glass matt disc. Focusing screen ( 11 ; 30 ; 40 ) for a data projection apparatus comprising: a holographic structure, wherein the holographic structure is arranged to scatter at least two different wavelengths, the holographic structure being further configured to generate equal scattering angles for each of the at least two wavelengths independent of the wavelength. Focusing screen ( 11 ; 30 ; 40 ) according to claim 3, wherein the holographic structure is arranged to scatter the at least two different wavelengths in a direction different from a direction of unscattered light. Focusing screen ( 11 ; 30 ; 40 ) for a data projection apparatus, comprising: a holographic structure, wherein the holographic structure is arranged to diffuse light having at least two different wavelengths, the holographic structure being arranged to scatter the at least two wavelengths in a direction different from one another A distinction is made between unscattered light. Focusing screen ( 11 ; 30 ; 40 ) according to one of claims 3 to 5, wherein the ground glass ( 11 ; 30 ; 40 ) is transparent to wavelengths outside the at least two wavelengths. A ground glass according to any one of claims 3 to 6, wherein the ground glass has a respective holographic layer for each of the at least two wavelengths. A ground glass according to any one of claims 3 to 7, wherein the ground glass comprises a volume hologram and / or a surface hologram.  A ground glass according to any one of claims 3 to 8, wherein the at least two wavelengths comprise a wavelength in the red region, a wavelength in the green region and a wavelength in the blue region. A data projection apparatus comprising: a ground glass ( 11 ; 30 ; 40 ) according to one of claims 3 to 9, a projector ( 10 ; 20 ) for projecting data on the ground glass ( 11 ; 30 ; 40 ), and at least one further optical component ( 12 ; 25 ) for steering one of the focusing screen ( 11 ; 30 ; 40 ) generated intermediate image to an eye ( 13 ; 27 ) of a viewer. Device according to one of claims 1, 2 or 10, wherein the projector ( 10 ; 20 ) is configured to project based on a wavelength in the red region, a wavelength in the green region, and a wavelength in the blue region. Device according to one of claims 1, 2, 10 or 11, wherein the at least one further optical component is a holographic element ( 12 ; 25 ), wherein the holographic element ( 12 ; 25 ), a virtual image ( 26 ) for viewing through the eye ( 27 ) to create. Device according to one of claims 1, 2 or 10 to 12, wherein the at least one further optical component ( 12 ; 25 ) one in a disc ( 24 ) of a vehicle component ( 25 ). Device according to one of claims 1, 2 or 10 to 13, wherein the device is designed as a head-up display or as an image projector.

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