METHOD FOR OPERATING A 3D DISPLAY AND 3D DISPLAY ARRANGEMENT

Description

[0001] The invention relates to a method for operating a 3D display, wherein vision rays are generated by means of an LC panel, wherein the vision rays can be deflected by at least one LC optic.

[0002] In addition, the invention relates to a 3D display arrangement with an LC panel, with a first LC optic, with a second LC optic and with a gaze detection device.

[0003] A challenge in developing 3D displays is that the display resolution is significantly reduced when a 3D view is required. This is due to the need to generate different views for a 3D display. Stereoscopic displays only require two views, but this reduces the area in which 3D vision is possible. Light field displays, on the other hand, generate views or viewing rays for many different viewing areas. This significantly improves the 3D impression. Generally speaking, the more views a 3D display generates for the same viewing area, the better the 3D impression.

[0004] 3D displays typically use static optical elements to restrict the viewing area for individual pixels to a narrow angle. This restriction allows different content to be displayed for the viewer's right and left eyes. These optical elements are either barriers, lenticular / microlenses, and / or waveguides with output structures. 1D LCDs are also used as barriers. These can be dynamically switched, allowing the barrier to be adjusted with the help of an eye-tracking camera so that each eye sees a separate image. This increases the area in which 3D vision is possible while simultaneously reducing the number of different viewing areas required.

[0005] Solutions using fixed optical components require significantly higher resolutions because many more views need to be generated to enable 3D viewing across a larger field of view. The variant with an active barrier for a 3D display reduces this problem. However, all solutions inevitably result in a limited depth range in which the viewer can experience 3D vision from in front of the display.

[0006] In addition, there are known variants of 3D displays in the prior art that utilize the concept of holography. These systems employ laser light sources and, among other things, phase displays. The greatest challenge with this technology is its wavelength dependency. This makes these systems very complex.

[0007] US Patent 2014 / 0028933 A1 discloses a 3D display system comprising a backlight panel, a display panel, a light distribution device, and a polarization state controller. The display panel is configured to display a two-dimensional (2D) image in 2D mode or a 3D image in 3D mode. The light distribution device is configured to transmit the 2D image in 2D mode and to split the 3D image into a left and a right image. Furthermore, the polarization state controller is located between the display panel and the light distribution device and is configured to rotate the polarization direction of the light emitted by the display panel in 2D mode.

[0008] EP 2 802 148 A1 discloses a display device comprising an image-generating device that displays a sequence of images. The sequence comprises sub-sequences that are temporarily interleaved. The images are composed of a plurality of pixels. Each pixel emits a set of light rays that are essentially non-divergent, at least in the horizontal direction. A beam-guiding device directs the light rays from the pixels to different viewing points.

[0009] The invention is therefore based on the objective of providing a method for operating a 3D display and a 3D display arrangement that enables the lightest possible construction while simultaneously achieving a high resolution of a three-dimensional view.

[0010] In the present invention, this problem is solved by the features of the characterizing part of claim 1, in that a gaze detection device tracks the position of the left eye and the right eye of a viewer of the 3D display, that at least one first imaging function is assigned to the LC optics, by which sight rays can be directed into the area of ​​the left eye, that at least one second imaging function is assigned to the LC optics, by which sight rays can be directed into the area of ​​the right eye, and that the switching between the first imaging function and the second imaging function is synchronous with the refresh rate of the LC panel.

[0011] An LC panel is a liquid crystal display or liquid crystal screen, the function of which is based on the fact that liquid crystals influence the polarization direction of light when a certain level of electrical voltage is applied.

[0012] In this case, "sight lines" refers to views used in the creation of 3D views to generate a three-dimensional perception for the viewer by guiding different views of an image into the viewer's field of vision.

[0013] Liquid crystals, hereinafter referred to as LC (Liquid Crystals), are able to change their refractive index depending on the applied electric field. This occurs because the LCs change their orientation relative to the optical axis when the intensity of the electric field is altered. When the electric field is switched off, the LCs orient themselves to their original position, in which the light beam passes through the element (almost) without refraction. The unstressed orientation of the LCs is determined by an orientation-prescribing layer. This layer can be applied to two substrates, such as glass, between which the LCs are located. The electrodes that generate the electric field can also be applied to the substrate glass and are nearly transparent.When the voltage is applied, depending on the design of the LC optics, a change in the light spot size (focus change), a symmetrical spot expansion in one or two axes, a shift of the light spot and / or an asymmetrical blurring of the light spot can be achieved.

[0014] The eye-tracking device is designed to enable the recording and / or analysis of eye movements. This can preferably be an eye-tracking camera.

[0015] An imaging function refers to the setting of the LC optics, including the corresponding intensity of the electric field required to direct the respective line of sight in the appropriate horizontal direction towards the viewer's eyes. The imaging function is linked to the eye-tracking device so that the relevant line of sight can be directed towards the viewer, thus avoiding the generation of irrelevant views outside the user's field of vision.

[0016] An advantage of the present invention is that it creates a flexible and dynamically adaptable system which allows for changes in the imaging function through software control. By directing light specifically to the eyes, system efficiency is increased and significantly fewer rays are required. Furthermore, this reduction to the eyes does not noticeably reduce the overall resolution and significantly decreases the required computing power.

[0017] It may be possible to use a backlight or illumination that is horizontally collimated and focused by a lens in the 3D display so that only an area of ​​8 mm to 16 mm in front of the display is visible at a distance of 600 mm to 1000 mm. The switchable LCD optics then "shift" the light to the current position of the viewer's eye.

[0018] Further preferred embodiments of the invention result from the other features mentioned in the dependent claims.

[0019] According to the invention, at least one first LC optic and one second LC optic are provided, and the first imaging function is assigned to the first LC optic and the second imaging function is assigned to the second LC optic.

[0020] Furthermore, according to the invention, the image rays exiting the LC panel have a first polarization state, and a polarization switch is provided by which the image rays can be switched from the first polarization state to a second polarization state and from the second polarization state to the first polarization state. The polarization switch is capable of rotating the polarization of the image rays by 180°. In this way, switching between the first imaging function and the second imaging function can be performed synchronously with the refresh rate of the LC panel by indirectly controlling the first LC optics or the second LC optics, respectively, via the polarization switch.

[0021] Furthermore, according to the invention, the first LC optic is designed for the first polarization state and the second LC optic is designed for the second polarization state. The two different LC optics make it possible to maintain two different imaging functions or optical functions, between which a rapid switch can be made using the polarization switch. In this way, optical rays in the first polarization state can be directed alternately, for example, to the left eye of the viewer, while optical rays in the second polarization state are directed to the right eye of the viewer. At a sufficiently high refresh rate, the viewer does not perceive such a change and experiences three-dimensional vision.

[0022] In a further embodiment of the method according to the invention, it is preferred that the first polarization state corresponds to a P-polarization and that the second polarization state corresponds to an S-polarization. The polarization switch can switch between the P-polarization and the S-polarization.

[0023] In a further advantageous embodiment of the method according to the invention, the LC panel is operated at a refresh rate of 120 Hz. For the actual display of the 3D image, a refresh rate of 60 Hz is desired. An imaging optic is provided for each eye, and the polarization switch toggles between these two functions at 120 Hz, synchronized with the 120 Hz of the LC panel, so that ultimately a 3D view is produced with a refresh rate of 60 Hz.

[0024] The aforementioned problem is also solved by a aforementioned 3D display arrangement comprising an LC panel, a first LC optic, a second LC optic, and a gaze detection device, wherein sight rays can be generated by the LC panel, wherein the sight rays leaving the LC panel can be deflected by the first LC optic and the second LC optic, wherein the position of the left eye and the right eye of a viewer of the 3D display arrangement can be tracked by the gaze detection device, wherein the first LC optic is assigned at least one first imaging function by which sight rays can be deflected into the area of ​​the left eye, and wherein the second LC optic is assigned at least one second imaging function by which sight rays can be deflected into the area of ​​the right eye.

[0025] In a first embodiment of the 3D display arrangement according to the invention, a polarization switch is arranged between the LC panel and the first LC optics, which is designed to rotate the polarization of the sight rays by 180°.

[0026] In a further embodiment of the 3D display arrangement, the eye-tracking device is designed as an eye-tracking camera. The eye-tracking camera does not need to be located directly adjacent to the other elements of the 3D display arrangement. For example, if the 3D display arrangement is used in a vehicle, preferably a motor vehicle, the eye-tracking camera can be positioned in a suitable location in the cockpit area, allowing for easy tracking of the eyes of, for example, the driver or passenger. The data recorded by the eye-tracking camera can be transmitted via cable or wirelessly to an evaluation unit within the 3D display arrangement, which also controls the evaluation and adjustment of the display functions.

[0027] Advantageously, in a further preferred embodiment of the 3D display arrangement, it is provided that a method according to the invention can be carried out using the 3D display arrangement. The above descriptions of the method according to the invention also apply accordingly to the 3D display arrangement according to the invention.

[0028] Unless otherwise stated in individual cases, the various embodiments of the invention mentioned in this application can be advantageously combined with one another.

[0029] The invention is explained below using exemplary embodiments with reference to the accompanying drawings. These show: Figure 1 is a schematic representation of the implementation of an embodiment of a method according to the invention or a schematic representation of an embodiment of a 3D display arrangement according to the invention, Figure 2 is an arrangement of liquid crystals, Figure 3 is a schematic representation of a targeted alignment of liquid crystals, Figure 4 is an exemplary electrode structure of an LC optic and Figure 5 is a schematic representation of the structure of an imaging function.

[0030] Figure 1Figure 1 shows the structure of a 3D display 10 or a 3D display arrangement. The 3D display 10 comprises an LC panel 12, i.e., a liquid crystal display. The LC panel 12 emits light rays 14. The LC panel 12 can also be illuminated by a suitable light source L. In this embodiment, the light source L is a horizontally collimated light source, which is additionally equipped with a lens (not shown). The collimated light is focused by the lens in the 3D display 10 such that only an area of ​​8 mm to 16 mm in front of the 3D display 10 at a distance of 600 mm to 1000 mm is visible. The light rays 14 leaving the LC panel 12 have a first polarization state. In this embodiment, the first polarization state is P-polarization.

[0031] The optical rays 14 leaving the LC panel 12 encounter an LC optic 16. The LC optic 16 is designed to redirect optical rays 14 according to an imaging function, which depends, among other things, on the data from an eye-tracking device 18, such that relevant optical rays 14 reach the left eye 20 or the right eye 22 of a viewer of the 3D display 10. The LC optic 16 comprises a first LC optic 24 and a second LC optic 26. The first LC optic 24 is designed to process optical rays 14 with a first polarization state, while the second LC optic 26 is designed to process optical rays 14 with a second polarization state.

[0032] A polarization switch 28 is arranged between the LC panel 12 and the LC optics 16. The polarization switch 28 is designed to convert the visual rays 14 from the first polarization state (P-polarization) to the second polarization state (S-polarization) and vice versa. By switching between the two polarization states, views for the left eye 20 and the right eye 22 can be created independently of each other. With a sufficiently high refresh rate, the viewer thus receives a three-dimensional effect. In this embodiment, the refresh rate is set to 120 Hz. The polarization switch 28 switches synchronously with the refresh rate of the LC panel 12. Thus, the viewer is presented with a three-dimensional image at a total refresh rate of 60 Hz.

[0033] The imaging function is the setting of the LC optics 16, which is required to direct the respective visual rays 14 in the corresponding horizontal direction of the viewer's left eye 20 or right eye 22. The imaging function is linked to the eye-tracking device 18 so that the relevant visual rays 14 can be directed towards the viewer, thus avoiding the generation of irrelevant views outside the user's field of vision.

[0034] The Figures 2 and 3Figure 3 shows an arrangement of liquid crystals 30 and their orientation when an electric field is applied. The liquid crystals 30 are able to change their refractive index depending on the applied electric field. This occurs when the liquid crystals 30 change their orientation relative to the optical axis as the intensity of the electric field is altered. When the electric field is switched off, the liquid crystals 30 return to their original position, in which the light beam passes through the element (almost) without refraction. The orientation of the liquid crystals when the electric field is deactivated is determined by an orientation-prescribing layer, a type of structural layer. These layers are applied to two substrates, in particular glass, between which the liquid crystals 30 are located. The electrodes, which generate the electric field and are not shown here, are also applied to the substrate glass and are nearly transparent.When the voltage is applied, depending on the design of the liquid crystal-based LC optics, 16 changes in the light spot size (focus change), symmetrical spot expansions in one or both axes, displacements of the light spot and / or symmetrical blurring of the light spot can be caused.

[0035] Figure 4 This shows how the electrode structures and the electric field of the LC optics 16 are designed and how they are combined with the LC panel 12. This layout enables the implementation of a lenticular lens known from the prior art and simultaneously the generation of a prism / 1D lens function for light guidance. The pixel structure 32 of the LC panel 12 is shown. Below it, the electrode structure 34 of the LC optics 16 is schematically arranged. When using a cylindrical lens, the underlying electric field 36 of the LC optics 16 is designed with a superimposed guidance function 38 as shown.

[0036] Figure 5 This shows how an imaging function can be structured. The aim is to image 8 to 16 subpixels 40, preferably 10 subpixels 40, onto a baseline 42 of 10 mm to 30 mm using a lens. Reference symbol list

[0037] 103D display 12LC panel 14 Beam of sight 16LC optics 18 Eye detection device 20 Left eye 22 Right eye 24 First LC optics 26 Second LC optics 28 Polarization switch 30 Liquid crystal 32 Pixel structure 34 Electrode structure 36 Electric field 38 Steering function 40 Subpixel 42 Baseline illumination

Claims

1. Method for operating a 3D display (10), wherein viewing rays (14) are generated by means of an LC panel (12), wherein the viewing rays (14) are able to be deflected by at least one LC optical system (16), characterized in that a gaze capture device (18) tracks the position of the left eye (20) and the right eye (22) of a viewer of the 3D display (10), in that the LC optical system (16) is assigned at least one first imaging function linked to the gaze capture device, by means of which imaging function viewing rays (14) can be directed into the region of the left eye (20), in that the LC optical system (16) is assigned at least one second imaging function linked to the gaze capture device, by means of which imaging function viewing rays (14) can be directed into the region of the right eye (22), and in that switching between the first imaging function and the second imaging function takes place synchronously with the vertical refresh rate of the LC panel (12), wherein at least one first LC optical system (24) and one second LC optical system (26) are provided, and in that the first imaging function is assigned to the first LC optical system (24) and in that the second imaging function is assigned to the second LC optical system (26), wherein the viewing rays (14) which leave the LC panel (12) have a first polarization state, in that a polarization switch (28) is provided, by means of which the viewing rays (14) can be converted from the first polarization state to a second polarization state and from the second polarization state to the first polarization state, and wherein the first LC optical system (24) is designed for the first polarization state and in that the second LC optical system (26) is designed for the second polarization state.

2. Method according to claim 1, characterized in that the first polarization state corresponds to a P-polarization and in that the second polarization state corresponds to an S-polarization.

3. Method according to any of claims 1 or 2, characterized in that the LC panel (12) is operated at a vertical refresh rate of 120 Hz.

4. 3D display arrangement comprising an LC panel (12), a first LC optical system (24), a second LC optical system (26) and a gaze capture device (18), wherein viewing rays (14) can be generated by the LC panel (12), wherein the viewing rays (14) leaving the LC panel (12) can be deflected by the first LC optical system (24) and the second LC optical system (26), wherein the position of the left eye (20) and the right eye (22) of a viewer of the 3D display arrangement can be tracked by the gaze capture device (18), wherein the first LC optical system (24) is assigned at least one first imaging function linked to the gaze capture device, by means of which imaging function viewing rays (14) can be deflected into the region of the left eye (20), wherein the second LC optical system (26) is assigned at least one second imaging function linked to the gaze capture device, by means of which imaging function viewing rays (14) can be deflected into the region of the right eye (22), wherein a method according to any of claims 1 to 3 can be carried out by means of the 3D display arrangement.

5. 3D display arrangement according to claim 4, characterized in that a polarization switch (28) is arranged between the LC panel (12) and the first LC optical system (24), which switch is configured to rotate the polarization of the viewing rays (14) by 180°.

6. 3D display arrangement according to claim 4 or 5, characterized in that the gaze capture device (18) is an eye-tracking camera.