Classifications

• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
  • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
  • G02B6/0033—Means for improving the coupling-out of light from the light guide
  • G02B6/0035—Means for improving the coupling-out of light from the light guide provided on the surface of the light guide or in the bulk of it
• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
  • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
  • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
  • G02F1/1323—Arrangements for providing a switchable viewing angle
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
  • B60K35/00—Instruments specially adapted for vehicles; Arrangement of instruments in or on vehicles
  • B60K35/20—Output arrangements, i.e. from vehicle to user, associated with vehicle functions or specially adapted therefor
  • B60K35/21—Output arrangements, i.e. from vehicle to user, associated with vehicle functions or specially adapted therefor using visual output, e.g. blinking lights or matrix displays
  • B60K35/22—Display screens
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
  • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
  • G02B6/0033—Means for improving the coupling-out of light from the light guide
  • G02B6/0035—Means for improving the coupling-out of light from the light guide provided on the surface of the light guide or in the bulk of it
  • G02B6/0036—2-D arrangement of prisms, protrusions, indentations or roughened surfaces
• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
  • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
  • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
  • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
  • G02F1/1333—Constructional arrangements; Manufacturing methods
  • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
  • G02F1/133524—Light-guides, e.g. fibre-optic bundles, louvered or jalousie light-guides
• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
  • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
  • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
  • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
  • G02F1/1333—Constructional arrangements; Manufacturing methods
  • G02F1/1347—Arrangement of liquid crystal layers or cells in which the final condition of one light beam is achieved by the addition of the effects of two or more layers or cells
  • G02F1/13471—Arrangement of liquid crystal layers or cells in which the final condition of one light beam is achieved by the addition of the effects of two or more layers or cells in which all the liquid crystal cells or layers remain transparent, e.g. FLC, ECB, DAP, HAN, TN, STN, SBE-LC cells

Definitions

• US Pat. No. 5,956,107 A discloses a switchable light source with which a screen can be operated in a number of modes.
• the disadvantage here is that all light decoupling is based on scattering and therefore only low efficiency and non- optimal light direction effects can be achieved. In particular, the achievement of a focused cone of light is not disclosed in detail.
• CN 107734118 A describes a screen that uses two background lights to make the viewing angle of a screen controllable.
• the upper of the two backlights should emit focused light.
• a lattice with opaque and transparent sections is mentioned in particular as a configuration for this.
• the same presumably means that the light from the second backlight, which has to penetrate the first in the direction of an LCD panel, is also focused and the public viewing mode, which is actually intended for a wide viewing angle, suffers a significant narrowing of the angle.
• US 2007/030240 A1 describes an optical element for controlling the light propagation direction of light originating from a backlight.
• This optical element requires, for example, liquid crystals in the form of PDLCs, which is expensive on the one hand and critical to safety, particularly for end customer applications, since PDLC liquid crystals generally require voltages in excess of 60V for their circuitry.
• CN 1987606 A in turn describes a screen that uses two backlights to make the viewing angle of a screen controllable.
• a "first light plate” is used, which must be wedge-shaped in order to enable the intended focused light output. Precise details for achieving the focused light extraction with the appropriate Winkelbe conditions are not disclosed.
• US 2018/0267344 A1 describes a structure with two flat lighting modules.
• the light from the lighting module located at the back in the viewing direction is focused by a separate structure. After focusing, the light still has to pass through the front lighting module, which has scattering elements. Thus, strong light focusing for privacy protection cannot be optimally implemented.
• US 2007/0008456 A1 discloses the division of a light emission angle into at least 3 areas, two areas of which are generally exposed to light. It follows that a privacy screen in which a so illuminated display is used, cannot be viewed from just one direction.
• WO 2015/121398 A1 by the applicant describes a screen of the type described initially.
• scattering particles are present in the volume of the corresponding light guide, which is essential for switching the operating mode.
• the scattering particles selected there made of a polymer usually have the disadvantage that light is coupled out from both large areas, which means that about half of the useful light is emitted in the wrong direction, namely towards the background lighting, and not in sufficient light there due to the structure Scope can be recycled.
• the scattering particles made of polymer that are distributed in the volume of the light guide can, under certain circumstances, especially at higher concentrations, lead to scattering effects that reduce the visual protection effect in the protected operating mode.
• US2020/012129 A1 discloses a lighting device and a screen that describe two lights for switching between a narrow and a wide viewing mode.
• one of the light guides is formed with fibers.
• the scattering decoupling structure of a light conductor is limited to certain strips in the projection direction. This is disadvantageous for homogeneous image illumination and usually also causes unwanted moiré effects in the structure, for example in interaction with the pixel columns or rows of an LCD panel above.
• the aforementioned methods and arrangements usually have the disadvantage that they significantly reduce the brightness of the basic screen and/or require an active, or at least a special, optical element for mode switching and/or a complex and require expensive manufacturing and/or reduce the resolution in free-to-view mode.
• a screen that can be operated in at least two operating modes B1 for a free view mode and B2 for a restricted view mode.
• Such a screen comprises a transmissive image display device, which modulates light incident on it to display image content, and which can be operated in the first operating mode B1 for the free view mode and in the second operating mode B2 for the restricted view mode, the image display device being an LCD panel is.
• An illumination device is arranged behind the transmissive image display device in the viewing direction of an observer onto the screen, which can be operated in the at least two operating modes B1 for the free view mode and B2 for the restricted view mode, with the illumination device in the first operating mode B1 emits light in a non-restricted viewing angle range and in the second operating mode B2 light in a contrast restricted viewing angle range.
• the image display device can be configured in two ways.
• the image display device comprises either an LCD panel with two liquid crystal layers, one of which is used to modulate the light in order to enable the display of the image content, and the other of which is used to define the viewing angle range in the first operating mode B1 for to switch the free view mode large and to restrict in the second operating mode B2 for the restricted view mode.
• the corresponding arrangement is preferably designed as a module and also includes a polarization filter behind the rear liquid crystal layer, between the two and in front of the front liquid crystal layer.
• liquid crystal layer which is used to switch the viewing angle range in the first operating mode B1 for an unobstructed viewing mode and in the second operating mode B2 for a restricted viewing mode dus to restrict, is in the viewing direction of an observer in front of the other liquid crystal layer and switches the viewing angle range through different polarization for the two operating modes B1 and B2.
• color and image-modulated light is already polarization-coded to determine the viewing angle range, so that in the B2 operating mode from oblique viewing directions at least 90%, preferably over 97%, is extinguished at the front polarization filter, which acts as an analyzer, with vertical However, not consideration.
• Other polarization properties are modulated accordingly for operating mode B1, so that it can pass through the analyzer from essentially all directions of incidence.
• the image display device comprises a dual-view LCD panel, which simultaneously displays two selectable image contents in different viewing angle ranges, with the two image contents being identical or different in the first operating mode B1 for a free view mode, and with in the second operating mode B2 for a limited view mode, at least one of the image contents is permanently black or monochrome, so that only a black or informationless, monochrome image is visible from the corresponding viewing angle area.
• White images are also to be regarded as monochromatic in this context.
• a dual-view LCD panel can comprise, for example, a barrier screen, a lenticular or a prism grid, which images selected groups of pixels in different viewing angle ranges in each case. By acting on these pixel groups, it is then possible to determine which pixels, and thus which respective image content, can be perceived from which viewing angle range.
• the screen also includes a control for the transmissive image display device and the lighting device for switching between the at least two operating modes B1 and B2.
• the control for the transmissive image display device and the lighting device for switching between the at least two operating modes B1 and B2 preferably comprises an electronic device which preferably, but not necessarily, synchronously processes the two operating modes B1 and B2 both for the image display device and for the lighting device 2a toggles.
• the lighting device comprises a planar backlight and one in front of the backlight in a viewing direction arranged, plate-shaped light guide with two opposing large areas, which are connected via narrow sides, the light guide on at least one of the large areas and / or within its volume has decoupling elements. Lamps are arranged laterally on the narrow sides of the light guide.
• the decoupling elements are in shape and number per area and in their
• each decoupling element is smaller in each case in its horizontal len and vertical dimensions than the minimum width and fleas of the smallest pixels of the image display device.
• the pixels will usually be color sub-pixels, but can also be monochromatic pixels.
• the decoupling elements are preferably selected in terms of their shape and number per surface and in their extent in such a way that in projection directions parallel to the surface normal of the light guide, parts or the entire surface of at least two decoupling elements are in each case for at least a subset of the smallest pixels of the image display direction are arranged below each smallest pixel of this subset of the image reproduction device.
• the subset can also include all the smallest pixels.
• the backlight emits light in a limited angular range.
• the light guide is at least 50% transparent to the light emitted by the background lighting.
• the background lighting is switched on and the lighting means are switched off, in the first operating mode B1 at least the lighting means are switched on.
• the light guide emits light, which is coupled laterally into at least one of its narrow sides, into a restricted angle range.
• the light guide is at least 30% transparent for the light emanating from the background lighting.
• the lamps are switched on and the background lighting is switched off in the second operating mode B2, and at least the background lighting is switched on in the first operating mode B1.
• the viewing angle range and the restricted angle range overlap by at least 50%, preferably by at least 75%, particularly preferably by at least 85%.
• the particular advantage of combining these measures to implement the two operating modes B1 and B2 both in the image display device and in the lighting device is that, in particular, the modes of action that restrict the viewing angle range for the second operating mode B2 complement each other, so that the privacy screen in this has a particularly strong effect in restricted viewing mode.
• the lighting device preferably emits light in a definable, restricted viewing angle range such that outside of this restricted viewing angle range, which is measured in a selectable plane that intersects the screen, at most 50%, preferably at most 20% , particularly preferably at most 10% of the highest luminance present within the restricted viewing angle range is present as the maximum luminance value.
• a plane for defining the measurement can advantageously include, for example, the perpendicular bisector of the screen and be parallel to the lower edge of the screen to within a tolerance of 7 degrees.
• a "large” viewing angle range for example, an angle range measured in the above-mentioned plane comes into question, which extends from about -60° to +60° or from about -60° to +30°, without restricting the generality of angle of 0° should coincide with the perpendicular bisector.
• a "restricted" viewing angle range would be, for example, from about -30° to +30°, or also from about -20° to +30° (asymmetry is possible), or from about -10° to +50°.
• any area that is smaller than the hemisphere in front of the screen can be considered as a limited viewing angle area.
• said restricted viewing angle range is designed asymmetrically about the surface normal of the background lighting.
• the asymmetrical design preferably takes place in a selectable preferred direction. This is particularly so in in-vehicle applications helpful, for example when a screen according to the invention is arranged as a so-called center information display in the dashboard approximately in the middle between the driver and front passenger.
• the restricted angle range for the view that is only released for the front passenger in operating mode B2 must be designed asymmetrically, i.e. directed towards the front passenger.
• the preferred direction in which the asymmetry is formed corresponds here to the horizontal.
• At least one optical component is arranged between the image display device and the light guide, preferably a diffuser (this can be isotropic or anisotropic) and/or a prismatic film (this can also have an isotropic or anisotropic effect).
• a diffuser this can be isotropic or anisotropic
• a prismatic film this can also have an isotropic or anisotropic effect.
• the decoupling elements are distributed over at least one of the large areas and/or within the volume of the light guide in such a way that the light radiated into the light guide by the lamps and decoupled from the light guide by the decoupling elements has the following Conditions fulfilled: 1) At least 50% of the amount of light coupled out on one of the large areas between an angle range of -50° and +50° to the surface normal of the large area is between an angle range of -20° and +20° in relation to one or two predetermined preferred directions perpendicular to each other and to the surface normal, and/or at least 70% of the amount of light emitted on one of the large surfaces between an angular range of -50° and +50° to the surface normal of the large surface is emitted between an angular range of -30° and +30 ° radiated in relation to the one or two preferred directions, and 2) at least 50% of those emitted from the light line
• the quantity of light coupled out is coupled out in the direction away from or towards the backlight.
• the lighting device can
• the light guide preferably consists of a transparent, thermoplastic or thermoelastic polymer, eg plastic, or of glass.
• the light guide or its substrate can contain at least 40 percent by weight polymethyl methacrylate, preferably at least 60 percent by weight polymethyl methacrylate on its weight.
• it can be polycarbonate (PC), for example.
• the decoupling elements can basically be distributed in different ways in or on the light guide during production of the light guide according to adaptable and predeterminable conditions for the decoupling of the light.
• the decoupling elements are locally limited structural changes in the volume and/or on the surfaces of the light guide. Additional optical layers that are attached to the surfaces of the light guide, i.e., e.g. diffusion layers, reflection layers, (dual) brightness-enhancing, collimating or polarization-recycling layers ((dual) brightness enhancement film - (D)) BEF) or reflective polarizers.
• the structure of the decoupling elements can be specified so that the effect of each decoupling element is at least approximately known and the properties of the light guide or of the light emerging from the light guide can be defined in a targeted manner by a definable distribution of the decoupling elements.
• the required properties for the decoupling elements, which are essential for the invention, in terms of their number per unit area, their shape, their orientation and extent in three dimensions and their distribution over at least one of the large areas and/or within the volume of the light guide can, for example, be an optics simulation software such as "LightTools" from Synopsis or another provider and then physically implemented accordingly.
• the distribution of the decoupling elements on at least one of the large areas and/or within the volume of the light guide is advantageously specified in such a way that the decoupled light achieves a luminance homogeneity of 70% on at least 70% of the surface of the light guide.
• the luminance homogeneity can be defined as Lv min /Lv max , i.e. as the ratio of the lowest luminance value to the highest value of an area.
• Another applicable regulation for measuring the luminance homogeneity is defined in the "Uniformity Measurement Standard for Displays V1.3" by the "German Automotive OEM Work Group Displays". It is possible that decoupling elements are attached to both large surfaces and/or optionally in the volume.
• the decoupling elements for decoupling light on at least one of the large areas of the light guide preferably consist of microlenses and/or micropris men and/or diffractive structures and/or three-dimensional structural elements and/or scattering elements with a maximum extension in their largest dimension that is smaller than 100 microns, preferably less than 50 microns.
• diffractive structures it can be a flologram or a grating/diffraction grating, for example.
• the outcoupling elements themselves can also have the external shape of microlenses, microprisms, scattering elements and/or diffractive structures. They can then be configured in particular as flea spaces, which are then formed in the volume of the light guide.
• the flea spaces can be empty of air, but are preferably filled with a gaseous, liquid or solid material.
• the material has a refractive index which differs from that of the material used for the light guide; it is preferably lower.
• the flare value of the material also preferably deviates from that of the material used for the light guide, and is preferably higher. Advantages of these configurations are higher efficiency in light extraction.
• the flea spaces can also be formed if the light guide is formed from two substrate layers connected to one another, the substrate layers are preferably of the same type.
• the connection can be chemical, physical or by gluing.
• the flea spaces are then designed as material recesses on at least one of the boundary surfaces of the substrate layers.
• the decoupling elements are attached to at least one of the large surfaces of the light guide, they are advantageously formed from a plastic or glass structured with a tool, the structure of which was embossed using a tool. This is possible, for example, in mass production by a UV-curing material - eg a lacquer, a monomer, etc.
• a light guide substrate which is structured by means of a tool and cured by UV radiation, eg polymerized.
• UV radiation eg polymerized.
• Other radiation curable materials can also be used.
• the formation of the recesses for the realization of the decoupling elements can be realized, for example, mechanically, lithographically or by printing, or also by applying, converting, removing or dissolving material.
• lattice structures, microprisms - either convex with a proportion of plastic on the surface pointing outwards and/or concave as an embossing or recess within the surface layer of the structured plastic - other three-dimensional structural elements with other shapes, or even microlenses can be used inexpensively and implemented with suitability for mass production.
• Concavely formed and convexly formed structures can equally be used.
• the background lighting consists, for example, of a flat radiator, preferably a further light guide with further light sources arranged on the side or on the back, and at least one light collimator integrated into the flat radiator and/or arranged in front of it, such as at least one prism foil and/or at least one privacy filter (lamella filter).
• the background lighting can basically be constructed like an LED backlight, for example as a so-called direct-lit LED backlight, edge LED backlight, OLED or as another surface emitter, on which e.g. at least one permanent privacy filter (with micro-lamellas ) is upset.
• One advantage of the invention is that the requirements for the background lighting are generally reduced compared to the prior art: the combination of the view-restricting effects of the image display device and the lighting device (in which the background lighting is integrated) do not have to as in the prior art, privacy contrasts of 100:1 or better can be achieved. On the contrary, values of 10:1 in the background lighting are already extremely helpful, to greatly improve the privacy effect of the image display device in the B2 mode.
• a residual light of the image display device in the B2 operating mode of, for example, 0.5% of the maximum brightness at an angle of -40 degrees would already drop to 0.05% if at -40 degrees the lighting device was only 10% (but not the harder to reach value of 1%) of the maximum brightness.
• means for reducing or controlling reflections for example an anti-reflection coating, can be arranged.
• the former is useful, for example, when the passenger is watching entertainment content that could distract the driver.
• a screen according to the invention can also be used to input or display confidential data, for example PIN numbers, e-mails, SMS or passwords, at ATMs, payment terminals or mobile devices.
• confidential data for example PIN numbers, e-mails, SMS or passwords, at ATMs, payment terminals or mobile devices.
• the lighting means mentioned can be LEDs or LED lines or laser diodes. Other variants are conceivable and are within the scope of the invention.
• the desired restricted angular ranges for the B2 mode for a restricted view can be defined and implemented independently for the horizontal and vertical directions, respectively.
• a larger angle (or possibly no restriction at all) in the vertical direction could make sense than in the horizontal direction, for example if people of different sizes should see an image at ATMs, while the side view should remain severely or completely restricted .
• security regulations often require restricted visibility in mode B2, both horizontally and vertically. In principle, the performance of the invention is retained if the parameters described above are varied within certain limits.
• FIG. 1 shows a schematic diagram for decoupling light, which is coupled into a light guide from the side, from the lower large area of the light guide, on which the decoupling elements are located, with the light exiting the light guide on the upper large area,
• 2 shows a schematic diagram for decoupling light that is coupled into a light guide from the side, from the upper large surface of the light guide, on which the decoupling elements are located, with the light exiting the light guide on the upper large surface
• 3 shows a schematic diagram of a screen in a first embodiment in a first operating mode B1 for a clear view mode
• FIG. 4 shows a schematic diagram of a screen in a first embodiment in a second operating mode B2 for a limited view mode
• FIG. 5 shows a schematic diagram of an exemplary form of a decoupling element
• FIG. 6 shows a schematic diagram of a screen in a second embodiment in the first operating mode B1 for a clear view mode
• FIG. 7 shows a schematic diagram of a screen in a second embodiment in the second operating mode B2 for a restricted view mode.
• FIG. 1 shows a schematic diagram for decoupling light that is coupled into a light guide 3 from the side of light sources 4, on the lower large surface of the light guide 3, on which the decoupling elements 6 are located.
• the coupled light leaves the light guide 3 on the upper large area.
• the light is decoupled from the upper large area of the light guide 3 in a wide angle (greater than 60°).
• the location of the decoupling elements 6 is indicated by the number 6, but the actual decoupling elements 6 are not shown here because they have to be microscopically small.
• Light from the light sources 4, e.g. from LEDs is thus coupled into the light guide 3 from the side.
• rays of the coupled light are thrown back into the light guide 3 on the outer wall until they finally (possibly repeatedly) hit a decoupling element 6 for the desired decoupling.
• the decoupling is stylized by the thin rays.
• the illustration in FIG. 1 is highly stylized for better visibility; in reality, a very large number of beam paths in the light guide 3 is implemented. In addition, light refractions at refractive index transition surfaces are not taken into account.
• Fig. 2 shows a schematic diagram for the decoupling of light, the side of
• Lamps 4 is coupled into a light guide 3, from the upper large area of the Light guide 3, on which the decoupling elements 6 are located.
• the light also leaves the light guide 3 here through the upper large area.
• FIG. 1 applies here analogously.
• the only technical difference here is the position and, if necessary, the design of the decoupling elements 6, which are now on top of the light guide 3 and thus decouple the light directly upwards. In this case, the decoupled light does not have to pass through the light guide 3 again, in contrast to the given units according to FIG.
• FIGS. 3, 4, 6 and 7 are sectional representations.
• 3 shows a schematic diagram of a screen 1a in a first embodiment in a first operating mode B1 for a clear view mode
• FIG. 4 in a second operating mode B2 for a restricted view mode.
• a screen 1a which can be operated in at least the two operating modes B1 for a free view mode and B2 for a restricted view mode, initially comprises a transmissive image display device 1, which modulates light incident on it to display image content, and in at least a first operating mode B1 for a clear view mode and in a second mode B2 for a restricted view mode can be operated.
• the image display device 1 is an LCD panel.
• an illumination device 2a which can be operated in the at least two operating modes B1 for an unobstructed view mode and B2 for a restricted view mode, with the illumination device 2a in the first operating mode B1 light in an unrestricted viewing angle range and in the second operating mode B2 emits light in a contrast restricted viewing angle range.
• the screen 1a also includes a control for the transmissive image display device 1 and the lighting device 2a for switching between the at least two operating modes B1, as shown by way of example in FIG. 3, and B2, as shown by way of example in FIG.
• the lighting device 2a comprises at least one extensive backlight 2, which emits light in a limited angular range, a plate-shaped light guide 3 located in front of the backlight 2 in the viewing direction, which is attached to at least one of the large areas and / or within its volume decoupling elements 6 , whereby the light guide 3 is at least 50% transparent to the light emanating from the background lighting 2, and lamps 4 arranged laterally on the narrow sides of the light guide 3.
• operating mode B2 the background lighting 2 is switched on and the lamps 4 are switched off, whereas in the B1 operating mode at least the lamps 4 are switched on.
• FIG. 3 the passage of the light (thin arrows) originating from the illumination device 2a through the image display device 1 in all directions is indicated by the bold arrows.
• the bold arrows in FIG. 4 indicate that the image display device 1 only lets light through in a restricted viewing angle range (bold dashed arrows mean that the light is not let through there or only lets through a maximum of ten percent).
• light from the illumination device 2a that is restricted only in the viewing angle range also strikes the image display device 1.
• the particular advantage of combining these measures to implement operating modes B1 and B2 both in the image display device 1 and in the lighting device 2a is that, in particular, the modes of action that restrict the viewing angle range for operating mode B2 complement each other, so that the privacy screen in has a particularly strong effect in this restricted viewing mode.
• the control - not shown in the drawing - for the transmissive image reproduction device 1 and the lighting device 2a for switching between the at least two operating modes B1 and B2 preferably comprises an electronic device which preferably, but not necessarily, the two operating modes B1 and B2 synchronously respectively for both the image display device 1 and the lighting device 2a.
• the image display device 1 comprises an LCD panel with two liquid crystal layers, one of which is used to modulate the light in order to enable the display of said image content, and the other of which is used to increase the viewing angle range in the first mode B1 for one To switch large free view mode and restrict in the second mode B2 for a restricted view mode.
• the corresponding arrangement is preferably designed as a module and also includes a polarization filter behind the rear liquid crystal layer, between the two and in front of the front liquid crystal layer.
• the image display device 1 comprises a dual
• Visible LCD panel which simultaneously displays two selectable image contents in different viewing angle ranges, with the two image contents being identical or different in the first operating mode B1 for the free view mode, and with at least one of the image in the second operating mode B2 for the restricted view mode - Content is permanently black or monochrome - which also includes white - so that only a black or information-less, colored image is visible from the corresponding viewing angle area,
• the liquid crystal layer that is used to switch the viewing angle range in the first operating mode B1 for a free view mode and to restrict it in the second operating mode B2 for a restricted view mode in the viewing direction of one viewer in front of the other Liquid crystal layer is located and the viewing angle range switches through different polarization for the two modes B1 and B2.
• color and image-modulated light is already polarization-coded to determine the viewing angle range, so that in the B2 operating mode from oblique viewing directions at least 90%, preferably over 97%, is extinguished at the front polarization filter (which acts as an analyzer), with vertical
• Other polarization properties are modulated accordingly for operating mode B1, so that it can pass through the analyzer from essentially all directions of incidence.
• the lighting device 2a preferably emits light in a definable, restricted viewing angle range such that outside of this restricted viewing angle range, which is measured in a selectable plane that intersects the screen 1a, at most 50%, preferably preferably at most 20%, particularly preferably at most 10% of the highest luminance present within the restricted viewing angle range is present as the maximum luminance value.
• a level defining the measurement can advantageously, for example, contain the perpendicular bisector on the screen and lie parallel to the lower edge of the screen 1a with a tolerance of 7 degrees.
• a "large” viewing angle range for example, an angle range measured in the above-mentioned plane comes into question, which extends from about -60° to +60° or from about -60° to +30°, with the generality not being restricted angle of 0° should coincide with the perpendicular bisector.
• a "restricted" viewing angle range would be, for example, from about -30° to +30°, or also from about -20° to +30° (asymmetry is possible), or from about -10° to +50°.
• the decoupling elements 6 for decoupling light on at least one of the large areas of the light guide 3 preferably consist of microlenses and/or micropris men and/or diffractive structures and/or three-dimensional structural elements and/or scattering elements with an extension in their largest dimension of max times 100 microns, preferably a maximum of 50 microns.
• diffractive structures it can be a flologram or a grating/diffraction grating, for example.
• FIG. 5 shows a basic sketch of an exemplary form of a decoupling element 6, here in the form of a microprism.
• This type of decoupling element can be distributed homogeneously or preferably inhomogeneously (i.e. for example--apart from exceptions--in greater numbers per area with increasing distance from the illuminants 4) on one or both large areas and/or in the volume of the light guide 3 e.g. as an air-filled recess.
• Other forms of decoupling elements 6 are of course possible.
• the decoupling elements are chosen in their shape and number per area and in their extent such that the horizontal and vertical dimensions of each decoupling element are smaller than the minimum of width and size of the smallest pixels of the image display device.
• the pixels will usually be color sub-pixels, but can also be monochromatic pixels.
• the decoupling elements are preferably selected in terms of their shape and number per surface and in their extension in such a way that in projection directions parallel to the surface normal of the light guide, parts or the entire surface of at least two decoupling elements for at least a subset of the smallest pixels of the image display unit Direction 1 are arranged device below each smallest pixel of this subset of the image display.
• the subset can also include all the smallest pixels.
• FIG. 6 shows a schematic diagram of a screen 1a in a second embodiment in the first operating mode B1 for a clear view mode and FIG. 7 in the second operating mode B2 for a restricted view mode.
• This configuration is an alternative to the configuration shown in FIGS. 3 and 4 .
• 6 and 7 comprises at least one extensive backlighting 2, a plate-shaped light guide 3 located in front of the backlighting 2 in the viewing direction, which decouples on at least one of the large areas and/or within its volume elements 6, wherein the light guide 3 is at least 30% transparent to the light emanating from the background lighting 2, and wherein the light guide 3 emits light coupled into at least one of its narrow sides into a limited angular range, and laterally on the narrow sides of the light guide 3 arranged lamps 4.
• the first operating mode B1 for the restricted view mode according to FIG. 6 at least the backlight 2 is switched on, whereas in the second operating mode B2 for the clear view mode according to FIG hold are.
• the lighting device 2a can also contain a collimation film at a suitable point in the structure, for example a lens or prism grid above or below the plate-shaped light guide 3.
• the light guide 3 preferably consists of a transparent, thermoplastic or thermoelastic polymer, eg plastic, or of glass.
• the light guide or its substrate can comprise at least 40 percent by weight polymethyl methacrylate, preferably at least 60 percent by weight polymethyl methacrylate, based on its weight.
• it can be polycarbonate (PC), for example.
• the decoupling elements 6 can basically be distributed in different ways in or on the light guide during the production of the light guide 3 according to adaptable and predeterminable conditions for the decoupling of the light.
• the decoupling elements 6 are locally limited structural changes in the volume and/or on the surfaces of the light guide.
• additional optical layers that are attached to the surfaces of the light guide 3, ie, for example, diffusion layers, reflection layers, (dual) brightness-enhancing, collimating or polarization-recycling layers ((dual) brightness enhancement film - ( D) BEF) or reflective polarizers.
• These additional layers which do not come under the term “decoupling element” 6, are only connected to the light guide 3 at the edges, if at all, but are usually only loosely attached in the area of the large areas and do not form a physical unit with the light guide 3 .
• paints applied to the large areas which combine with the light guide 3 by chemical reactions or other forces (eg van der Waals forces), form a physical unit and can no longer be separated from one another; such paints therefore do not count as an additional layer in the sense mentioned above.
• the structure of the decoupling elements 6 can be specified so that the effect of each decoupling element 6 is known at least approximately and properties of the light guide 3 or the light emerging from the light guide 3 can be defined in a targeted manner by a definable distribution of the decoupling elements 6.
• the required properties, which are essential for the invention, for the decoupling elements 6 in terms of their number per unit area, their shape, their orientation and extent in three dimensions and their distribution over at least one of the large areas and/or within the volume of the light guide 3 can, for example, be an optics simulation software such as "LightTools" from Synopsis or other providers and then physically implemented accordingly. It is possible for decoupling elements 6 to be attached to both large areas and/or optionally in the volume of the light guide 3 as well.
• the background lighting 2 consists, for example, of a flat radiator, preferably another light guide with additional light sources arranged on the side or on the back, and at least one light collimator integrated into the flat radiator and/or arranged in front of it, such as at least one prismatic film and/or or at least one privacy filter (lamella filter).
• the background lighting 2 can basically be constructed like an LED backlight, for example as a so-called direct-lit LED backlight, edge LED backlight, OLED or as another surface radiator on which, for example, at least one permanent privacy filter (with micro-lamellae ) is upset.
• An advantage of the screen described above is that the requirements for the background lighting 2 are generally reduced compared to the prior art: through the combination of the view-restricting effects of the image display device 1 and the lighting device 2a (in which the background lighting 2 is integrated is), it is not necessary to achieve privacy contrasts of 100:1 or better, as is the case with the prior art. On the contrary, values of 10:1 in the background lighting 2 are already extremely helpful in order to greatly improve the visual protection effect of the image display device 1 in the B2 operating mode.
• a residual light of the image display device 1 in the B2 operating mode of, for example, 0.5% of the maximum brightness at an angle of -40 degrees would already drop to 0.05% if at -40 degrees the lighting device was only 10% (but not the value of 1%) of the maximum brightness that is more difficult to achieve.
• the screen is used particularly advantageously in a vehicle for the selective display of image content only for the passenger in mode B2 or simultaneously for the driver and the passenger in mode B1.
• the former is useful, for example, when the passenger is watching entertainment content that could distract the driver.
• a screen as described above can also be used to enter or display confidential data, for example PIN numbers, e-mails, SMS or passwords, at ATMs, payment terminals or mobile devices.
• the lighting device described above and the screen that can be implemented with it solve the problem: a screen was described with which information can be reliably displayed by means of an optionally restricted viewing angle, with a free , unrestricted view is possible in the viewing angle.
• the highest possible resolution, ie the native resolution of the screen used is visible in both operating modes.
• the limited viewing angle achieves a comprehensive visual protection effect without placing increased demands on the lighting device used.
• the screen described above can advantageously be used wherever confidential data is displayed and/or entered, such as when entering a PIN or for displaying data at ATMs or payment terminals or for entering passwords or when reading e-mails on mobile phones Devices. As described above, it can also be used in cars.

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• 2021
  • 2021-04-26 DE DE102021110645.1A patent/DE102021110645B4/de active Active
• 2022
  • 2022-04-12 WO PCT/EP2022/059770 patent/WO2022228890A1/de active Application Filing
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