METHOD AND ARRANGEMENT FOR THE SECURE DISPLAY OF INFORMATION

Abstract

A method to operate a display screen D in at least two operating modes, B1 for a free viewing mode and B2 for a restricted viewing mode, comprising the following steps: arrangement of a switchable optical element immediately in front of a display screen as seen in a viewer's viewing direction, the said optical element ensuring switching between the at least two operating modes B1 and B2, presentation of an image content on the display screen, wherein the optical element contains a multitude of louvers, and wherein the optical effect of the louvers can be changed between transparent (B1) and luminous (B2) due to the fact that at least every twentieth louver contains triggerable layers that can be switched to be either transparent or brightly self-luminous.

Claims

1. A method to operate a display screen in at least two operating modes, a free-viewing mode and a restricted-viewing mode, comprising the following steps: arranging, immediately in front of a display screen in a viewing direction of a viewer, a switchable optical element that enables switching between the at least two operating modes, the optical element including a plurality of louvers, and at least every twentieth louver of the plurality of louvers includes a triggerable layer configured to be switched between a transparent state or a self-luminous state, thereby creating an optical effect; displaying an image content on the display screen, switching between the free-viewing mode and the restricted-viewing mode by causing the triggerable layer to be switched between the transparent state and the self-luminous state.

2. The method as claimed in claim 1, wherein the triggerable layer contains transparent OLEDs and/or an electroluminescent layer.

3. The method as claimed in claim, wherein those louvers which do not contain a triggerable layers contain passive light scattering portions, which, when illuminated with light from the triggerable layers, scatter this light and radiate it at least partially sideways in front of the display screen, with the haze of these passive light scattering portions being less than 4%, preferably less than 2%, measured in accordance with ASTM D1003.

4. The method as claimed in claim 1, wherein the display screen is an LCD screen, an OLED screen or an FED screen.

5. The method as claimed in claim 1, wherein optically transparent material as a filler is disposed between every two adjacent louvers, this material comprising optical casting resin, UV-curing material or acrylic glass.

6. A system for the secure display of image contents, which can be operated in at least two operating modes, a free-viewing mode and a restricted-viewing mode, comprising: a display screen, a switchable optical element that enables switching between the at least two operating modes and is arranged immediately in front of a display screen in a viewing direction of a viewer, wherein the optical element contains a multitude of louvers, wherein the optical effect of the louvers can be altered between transparent and luminous due to the fact that at least every twentieth louver contains triggerable layers that can be switched to be either transparent or brightly self-luminous.

7. The arrangement as claimed in claim 6, wherein the triggerable layer contains transparent OLEDs and/or an electroluminescent layer.

8. The arrangement as claimed in claim 6, wherein those louvers which do not contain a triggerable layers contain passive light scattering portions, which, when illuminated with light from the triggerable layers, scatter this light and radiate it at least partially sideways in front of the display screen, with the haze of these passive light portion being less than 4%, preferably less than 2%, measured in accordance with ASTM D1003.

9. The system as claimed in claim 6, wherein the display screen is an LCD screen, an OLED screen or an FED screen.

10. (canceled)

11. The method of claim 1, further comprising switching to the restricted-viewing mode, and entering confidential data.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Below, the invention and exemplary methods will be explained in more detail with reference to the accompanying drawings, which also show features essential to the invention, among others, and in which

[0058] FIG. 1 shows an implementation of the invented method in mode B1,

[0059] FIG. 2 shows an implementation of the invented method in mode B2, and

[0060] FIG. 3 shows an implementation of the invented method in mode B2, here with a different configuration of the louvers.

[0061] All drawings are merely schematic and not to scale.

DETAILED DESCRIPTION OF THE INVENTION

[0062] The invented method of operating a display screen 1 in at least two operating modes, viz. B1 for a free viewing mode and B2 for a restricted viewing mode, comprise the following steps as described hereinbefore: [0063] Arrangement of a switchable optical element 3 immediately in front of a display screen 1 as seen in a viewer's 5 viewing direction, the said optical element ensuring switching between the at least two operating modes B1 and B2, [0064] presentation of image content on the display screen 1, [0065] wherein the optical element 3 contains a multitude of louvers 4, and wherein the optical effect of the louvers 4 can be changed between transparent (B1) and luminous (B2) in such a way that at least every twentieth louver 4 contains triggerable layers 2 that can be switched to be either transparent or brightly self-luminous.

[0066] In the example illustrated by FIG. 1, each louver 4 contains triggerable layers 2, which can be switched to be either transparent or brightly self-luminous. Here, the said triggerable layers 2 are implemented, e.g., by transparent OLEDs, so that these louvers 4 can be switched between a transparent and a self-luminous state.

[0067] FIG. 1 shows an implementation of this invented method in mode B1. In this operating mode B1, the invention functions in such a way that the louvers 4 are all transparent (because the triggerable layers 2 are switched to be transparent) and therefore do not obstruct the view of the display screen 1 for any of the viewers 5 and 5a viewing from any directions.

[0068] FIG. 2 shows an implementation of the invented method in mode B2. In this operating mode B2, when the louvers 4 emit light (because the triggerable layers 2 are in the self-luminous state), they obstruct the view of the image content shown on display screen 1 for a viewer 5a at a viewing angle outside a in that the light radiated laterally by the display screen 1 is superimposed with light emitted by the louvers 4 (see the arrows extending from the louvers 4 in FIG. 2), which is almost exclusively visible if looked at from the side, e.g. from the viewing position of viewer 5a. For viewer 5, viewing is not restricted as long as he/she remains within angle . In FIG. 1 this can at best be hinted at, since, with dimensions in their correct relation, viewer 5 would have to be drawn markedly further above the display screen 1, for which the illustration lacks sufficient space.

[0069] Preferably, the louvers 4 are arranged vertically, i.e. at an angle of 90 degrees relative to the surface of the display screen 1. This angle substantially defines from what central angle an image can still be seen in the restricted viewing mode B2.

[0070] FIG. 3 shows a configuration in operating mode B2 in which only every other louver 4 contains triggerable layers 2 that can be switched to be transparent or brightly self-luminous. The remaining louvers 4 (those in between the ones just mentioned), which contain none of the said triggerable layers 2, rather contain passive light scattering means 6, which, when illuminated with light (see the solid arrowed lines in FIG. 3) emitted by the triggerable layers 2, will scatter this light and at least partially radiate it laterally to the front of the display screen 1 (see the dashed arrowed lines in FIG. 3), with the haze of these passive light scattering means 6 is smaller than 4% but preferably smaller than 2% as measured according to ASTM D1003. The entirety of all louvers 4, then, effects privacy protection as described above, as the light coming from the display screen is, at lateral angles, superimposed with that coming from the louvers in such a way that the image content displayed cannot be seen by viewer 5a. Viewer 5, on the other hand, can see the image almost unimpaired, since no, or almost no light is radiated normal to the display screen 1. In addition, the louvers 4 can, on their sides facing the viewer 5, contain opaque lines that make the louvers 4 opaque from the viewing direction and thus prevent light exit in the viewing direction.

[0071] It is important that the passive light scattering means 6 are transparent whenever no light is incident on them, i.e., that they exhibit low haze, because only then operating mode B1 is possible to happen.

[0072] Materials eligible for the passive light scattering means 6 are, for example, titanium dioxide particles of a mean particle size of 150-500 nm in a concentration, related to the weight of the respective louver, of 0.01-300 wt.-ppm. Other configurations are possible, say, with particles of barium sulfate, silsesquioxane particles or cross-linked polystyrene particles or yet other kinds of particles. As a rule, the scattering particles are homogeneously distributed within the respective louvers 4.

[0073] Furthermore, the passive light scattering means 6 may contain at least 40 wt.-%, preferably at least 60 wt.-%, of polymethyl methacrylate related to their (partial) weight.

[0074] The height of a louver 4 may vary, e.g., between 50 m and 500 m, or be greater or smaller if necessary. This height depends on the desired viewing distance in operating mode B2. The louvers 4 may have wall thicknesses between, e.g., 10 m and 50 m or greater. The average spacing between the center of one louver and the center of the nearest one is approximately equal to one time up to maximally ten times the order of magnitude of the louvers' wall thickness. Other dimensions are possible as well. Dimensioning is a matter of the experts' skill and, therefore, is not described in detail here.

[0075] Suitable electronic circuitry for triggering the display screen 1 and the switchable layers 2 is provided, of course.

[0076] The display screen 1 may be, e.g., an LCD screen, an OLED screen or an FED screen. Other configurations are possible, especially, but not exclusively, such using other types of self-luminous displays. Finally, some optically transparent material may be arranged as a filler between every two adjacent louvers 4. Such material may consist, e.g., of optical-quality casting resin, UV-curing material or acrylic glass. In this way, a robust construction will be achieved.

[0077] Analogously, the above explanations of the drawings FIG. 1 through FIG. 3 are also applicable to the invented arrangement. To avoid redundancy they are not repeated here.

[0078] The invented method and the invented arrangement described above make it possible, if and when desired, to present security-relevant information within a small angular viewing range only, so that it can only be seen by the person addressed, whereas information that is not security-relevant can be presented with the full resolution of the display screen in such a way that it can be seen from a wide angular viewing range and, thus, by third persons such as bystanders.

[0079] The invention solves the problem outlined at the start. It proposes a method and an arrangement for the secure display of information, which can be implemented in lot production at reasonable cost. As added advantages, the said method and arrangement hardly reduce the brightness of the base display screen, if at all; the technical approach is also applicable for self-luminous display types, and the extra power consumed in both operating modes and with all configurations of the invention is negligible. Switching between operating modes B1 and B2, too, requires a very small amount of power.