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EP-4735961-A1 - SWITCHABLE HOLOGRAPHIC DISPLAY

EP4735961A1EP 4735961 A1EP4735961 A1EP 4735961A1EP-4735961-A1

Abstract

In a first aspect, the invention relates to a holographic display device for the switchable display of images, wherein a light source, a light guide and at least two holographic diffraction gratings are configured for illumination of the at least two holographic diffraction gratings by light from the light source coupled into the light guide. Each holographic diffraction grating generates an image. Furthermore, a controllable light gate is allocated to each holographic diffraction grating. The light gate is configured to regulate the brightness of the generated image. In a further aspect, the invention relates to an operating device comprising a holographic display device as described and at least one operating element having at least one sensor. The sensor can detect an interaction with the operating element and output a detection signal. Furthermore, a control device is comprised which controls the light gate depending on the detection signal.

Inventors

  • ERLER, Christoph
  • KUEHL, Siemen

Assignees

  • Carl Zeiss Jena GmbH

Dates

Publication Date
20260506
Application Date
20240626

Claims (16)

  1. 1. Holographic display device (1) for the switchable display of images (6), comprising a light source (4), a light guide (2) and at least two holographic diffraction gratings (3), which are designed to illuminate the at least two holographic diffraction gratings (3) by light (5) from the light source (4) coupled into the light guide (2), wherein each holographic diffraction grating (3) is designed to couple light out of the light guide when illuminated by the light source (4) in order to generate an image (6), wherein each holographic diffraction grating (3) is assigned a controllable light gate (7) which is designed to regulate a brightness of the respectively generated image (6).
  2. 2. Holographic display device (1) according to claim 1, wherein the light gate (7) is arranged at least in parts in a beam path of the coupled-out light (8) of the associated diffraction grating (3).
  3. 3. Holographic display device (1) according to one or more of the preceding claims, wherein the light gate (7) is arranged to control the transmission of light depending on an applied control signal, wherein the controllable transmission preferably comprises at least two different transmission values.
  4. 4. Holographic display device (1) according to the preceding claim, wherein the transmission values comprise a first and a second value, wherein at the first transmission value the image (6) is visible and wherein at the second transmission value the image (6) is not visible.
  5. 5. Holographic display device (1) according to one or more of the preceding claims, wherein the light gate (7) comprises a first polarization filter (9) and a second polarization filter (10) and a controllable polarization modulator (11) arranged between the polarization filters (9, 10).
  6. 6. Holographic display device (1) according to the preceding claim, wherein the first polarization filter (9), the second polarization filter (10) and the controllable polarization modulator (11) are arranged in a beam path of the coupled-out light (8) of the associated diffraction grating (3).
  7. 7. Holographic display device (1) according to the preceding claim 5, wherein the second polarization filter (10) and the controllable polarization modulator (11) are arranged in a beam path of the coupled-out light (8) of the associated diffraction grating (3), wherein the first polarization filter (9) is a common first polarization filter (9) for all light gates (7, 7', 7"), which is arranged between the light source (4) and the holographic diffraction gratings (3, 3', 3").
  8. 8. Holographic display device (1) according to one or more of the preceding claims, wherein the light guide (2) has a planar extension, wherein the light guide (2) has a coupling-out surface (14) for coupling out the light from the light guide (2), which is arranged along the planar extension of the light guide (2), wherein the holographic diffraction gratings (3) are preferably arranged along the coupling-out surface (14).
  9. 9. Holographic display device (1) according to the preceding claim, wherein the light gate (7) is applied at least in part to the coupling-out surface (14).
  10. 10. Holographic display device (1) according to the preceding claim, wherein a low-refractive layer (15) is included on the coupling-out surface (14) at least between the holographic diffraction grating (3) and the parts of the light gate (7).
  11. 11. Holographic display device (1) according to the preceding claim, wherein a refractive index difference between the light guide (2) and the low-refractive layer (15) is at least 0.3, wherein preferably the light guide (2) has a refractive index between 1.45 and 2.0 and wherein preferably the low-refractive layer (15) has a refractive index between 1.37 and 1.47.
  12. 12. Holographic display device (1) according to one or more of the preceding claims, wherein an air gap is included between the light guide and the parts of the light gate.
  13. 13. Holographic display device (1) according to one or more of the preceding claims, wherein the holographic diffraction gratings (3) are arranged next to one another, wherein preferably a plurality of holographic diffraction gratings (3) are arranged directly adjacent to one another or wherein preferably a plurality of holographic diffraction gratings are arranged at a distance from one another, wherein a distance is preferably at least 1 mm, more preferably at least 2 mm and in particular 3 mm or more.
  14. 14. Holographic display device (1) according to one or more of the preceding claims, wherein the holographic diffraction gratings (3) and/or the generated images (6) have an extent of at least 10 x 10 mm 2 .
  15. 15. Operating device (26) comprising a holographic display device (1) according to one or more of the preceding claims, wherein at least one operating element (27) is included with at least one sensor (21), wherein the sensor is configured to detect (23) an interaction (22) with the operating element (27) and to output a detection signal (24), and a control device, wherein the control device is configured to control the light gates (7) depending on the detection signal (25).
  16. 16. Operating device (26) according to the previous claim, wherein for at least two holographic diffraction gratings (3) a control element (27) associated with the respective holographic diffraction grating (3) is included, wherein the light gates (7) associated with the respective holographic diffraction grating (3) are controlled depending on the detection signal of the control element (27) associated with the diffraction grating (3).

Description

SWITCHABLE HOLOGRAPHIC DISPLAY DESCRIPTION In a first aspect, the invention relates to a holographic display device for the switchable display of images, wherein a light source, a light guide and at least two holographic diffraction gratings are set up for illuminating the at least two holographic diffraction gratings by light from the light source coupled into the light guide. Each holographic diffraction grating generates an image. In addition, a controllable light gate is assigned to each holographic diffraction grating. The light gate is set up to regulate a brightness of the image generated in each case. In a further aspect, the invention relates to an operating device comprising a holographic display device as described and at least one operating element with at least one sensor. The sensor can detect an interaction with the operating element and output a detection signal. Furthermore, a control device is included which controls the light gate depending on the detection signal. Background and state of the art: Illuminated displays, including holographic ones, are known from the prior art. Often, such holographic illuminated displays use a light guide into which light is coupled and which includes a holographic structure for coupling out and image generation. Often, a so-called edge-lit arrangement is used, in which light is coupled into a light guide at an angle greater than the angle of total reflection and is then coupled out of the light guide by a holographic structure enclosed by the light guide to create the display. If you want to create several images, especially images of the same color, in this way, you can accommodate them together in a light guide or a single edge-lit arrangement, or you can use a separate light guide or edge-lit arrangement for each image. In the first case, the brightness of the images can only be controlled together and in particular switched on and off, namely by regulating the illumination light accordingly. Unfortunately, separate control of the brightness of individual images, which are generated by holographic structures illuminated with a common light guide and in particular by a single edge-lit arrangement, is not possible at all or only in a complicated and problematic way. Object of the invention: The object of the invention is to provide an improved holographic display device without the disadvantages of the prior art. In particular, the object of the invention is to provide a holographic display device which uses a single light guide to illuminate holographic structures in order to generate several images, whereby the brightness of the images can be individually controlled in a simple and effective manner. It is also the object of the invention to provide an improved operating device with a holographic display. Summary of the invention: The object is solved by the features of the independent claims. Preferred embodiments of the invention are described in the dependent claims. In a first aspect, the invention relates to a holographic display device for the switchable display of images, comprising a light source, a light guide and at least two holographic diffraction gratings. The light source, light guide and the at least two holographic diffraction gratings are designed to illuminate the at least two holographic diffraction gratings by light from the light source coupled into the light guide. Each holographic diffraction grating is designed to couple light out of the light guide when illuminated by the light source in order to generate an image. In addition, a controllable light gate is assigned to each holographic diffraction grating. The light gate is arranged and designed to regulate a brightness of the image generated in each case. A holographic display device for the switchable display of images is preferably a device that generates images through holographic diffraction gratings, which are thus displayed as it were. These images are in particular switchable, which preferably means that properties of the images, in particular their brightness, can be influenced by a switching process. One could also speak of a controllability of the brightness of the images. Switchable displays of images include in particular images that can be switched on and off. A light guide is preferably a body that is transparent to electromagnetic radiation in a certain wavelength range, which, when coupled into the light guide accordingly, makes it possible to guide this electromagnetic radiation, i.e. in particular to "transport" it along a certain path within the light guide, for example directly and/or via a so-called wave guide through reflections, especially total internal reflections, at the boundary surfaces of the body. The electromagnetic radiation is preferably in the visible range, in particular between 380 nanometers (nm) and 780 nm. Transparent preferably means that one can essentially see through the base body. Transparent means in particular that the base body has