Method and arrangement for enhancing the privacy screen effect of a monitor

Abstract

Method for enhancing the privacy effect of a screen (1) which allows switching between an operating mode with privacy effect and an operating mode without privacy effect and which is arranged in the dashboard of a motor vehicle, comprising the following steps, - Display of an image content (2) on a screen (1), wherein the screen (1) has a privacy screen effect that allows viewing only from a limited angle range, - Emission of light from at least one light source (3) at least onto the eyes of a viewer (4) of the screen (1) who is positioned laterally, i.e., not frontally, to the screen (1) and who is therefore located within the area of ​​the screen's privacy effect, wherein the light source (3) and the screen (1) are spatially separated from each other, so that light from the light source (3) enters the viewer's (4) eyes from a different spatial direction than the light entering the viewer's (4) eyes from the screen (1), wherein the viewer (4) corresponds to the driver of the motor vehicle, and furthermore, wherein the at least one light source (3) is only switched on when the screen's (1) privacy-effect operating mode is also switched on. - wherein furthermore, the luminance of the light source (3) visible to the viewer (4) is at least five times, preferably ten times, particularly preferably one hundred times greater than the luminance of the screen (1) still visible to the viewer (4) from his viewing position within the scope of the privacy screen effect, - so that the visual shielding effect of the screen (1) is enhanced due to the light seen by the eyes of said viewer (4) of at least the light source (3) and the associated pupil constriction and / or eye adaptation.

Description

Field of the invention

[0001] In recent years, great strides have been made in widening the viewing angle of LCDs. However, there are often situations where the very large viewing area of ​​a screen can be a disadvantage. Information, such as banking details and other personal and sensitive data, is becoming increasingly available on mobile devices such as notebooks and tablet PCs. Accordingly, people need control over who can see this sensitive data; they need to be able to choose between a wide viewing angle in order to share information on their display with others, e.g. when looking at holiday photos or for advertising purposes. On the other hand, they need a narrow viewing angle if they want to keep the image information confidential.A similar problem arises in vehicle construction: The driver must not be distracted by image content, such as digital entertainment programs, when the engine is running, while the passenger also wants to consume the same content while driving. Therefore, a screen that can switch between the corresponding display modes is required. State of the art

[0002] Additional films based on micro-louvres have already been used for mobile displays to achieve visual privacy. However, these films were not switchable; they always had to be applied and removed manually. They also had to be transported separately from the display when not in use. A major disadvantage of using such louvre films is the associated light loss.

[0003] US Pat. No. 6,765,550 A1 describes such a privacy screen using micro-louvres. The biggest disadvantage here is the mechanical removal or installation of the filter, as well as the loss of light in protected mode.

[0004] US Pat. No. 5,993,940 A describes the use of a film with evenly spaced, small prism strips on its surface to achieve a privacy mode. Development and production are quite complex.

[0005] In WO 2012 / 033583 A1, switching between unobstructed and restricted view is achieved by controlling liquid crystals between so-called "chromonic" layers. This results in a loss of light and is quite complex.

[0006] US 2012 / 0235891 A1 describes a very complex backlight in a display. Fig. 1 and Fig. 15 not only uses multiple light guides, but also other complex optical elements such as microlens elements 40 and prism structures 50, which transform the light from the rear illumination on its way to the front illumination. This is expensive and complex to implement and also involves light loss. According to the variant according to Fig. 17 in US 2012 / 0235891 A1, both light sources 4R and 18 produce light with a narrow illumination angle, with the light from the rear light source 18 first undergoing a complex conversion process into light with a wide illumination angle. This complex conversion, as already noted above, significantly reduces brightness.

[0007] According to JP 2007-155783 A, special optical surfaces 19 are used, which are complex to calculate and manufacture, and which then deflect light into different narrow or wide areas depending on the angle of incidence. These structures resemble Fresnel lenses. Furthermore, there are interference edges that deflect light in undesirable directions. Thus, it remains unclear whether truly meaningful light distributions can be achieved.

[0008] US 2013 / 0308185 A1 describes a special light guide with steps that emits light across a large surface in different directions, depending on the direction from which it is illuminated from a narrow side. In conjunction with a transmissive image display device, e.g. an LC display, this makes it possible to create a screen that can be switched between free and restricted view modes. A disadvantage of this is that the restricted view effect can only be created for left / right or for top / bottom, but not for left / right / top / bottom simultaneously, as is necessary for certain payment transactions, for example. In addition, even in restricted view mode, residual light is still visible from blocked viewing angles.

[0009] WO 2015 / 121398 A1 by the applicant describes a screen of the type described above. In this case, scattering particles are present in the volume of the corresponding light guide, which are essential for switching between operating modes. However, the polymer scattering particles selected there generally have the disadvantage that light is coupled out of both large surfaces, causing approximately half of the useful light to be emitted in the wrong direction, namely toward the backlight, where it cannot be adequately recycled due to their design. Furthermore, the polymer scattering particles distributed throughout the volume of the light guide can, under certain circumstances, particularly at higher concentrations, lead to scattering effects that reduce the privacy effect in the protected operating mode.

[0010] Furthermore, WO 2019 / 002 496 A1 by the applicant discloses a design with a dual, switchable backlight to enable multiple operating modes of a screen. A disadvantage of this design is that, due to scattering effects in the optical design, residual light can still reach a viewer from the side, such as the driver of a car, at larger angles.

[0011] DE 2015 015 516 B4, filed by the applicant, describes a design that allows for multiple operating modes of a screen. In this case, any residual light from the sides is directly blended onto the screen in privacy mode. The disadvantage of this is that the image contrast is reduced and the screen does not appear black from the sides in privacy mode.

[0012] DE 10 2018 004 401 A1, filed by the applicant, describes a method for correcting image data for a screen. For example, the brightness and contrast of a screen that can be switched between several operating modes are reduced precisely when a side viewer, such as a vehicle driver, is looking at the screen in privacy mode. A disadvantage of this method is the need for technical evaluation of the driver's eye position.

[0013] DE 11 2015 005 433 T5 discloses an occupant monitoring system and method. This system uses an image capture unit (camera) to monitor the driver. A disadvantage of this system is that the privacy-protecting effect of a screen cannot be enhanced.

[0014] Finally, DE 2017 008 287 A1 discloses a method and arrangement for temporarily preventing the usability of sensors and / or interfaces of a mobile device. Even with the method disclosed therein, the privacy-protecting effect of a screen cannot be enhanced.

[0015] The aforementioned methods and arrangements generally have the disadvantage that they significantly reduce the brightness of the base screen and / or require a complex and expensive optical element for mode switching and / or reduce the resolution in the freely viewable mode. In particular, achieving a very strong privacy shielding effect, in which a viewer within the privacy shielding area only perceives a dark image, is only achievable with the state of the art with great effort or, depending on the design, sometimes not at all. Description of the invention

[0016] The object of the invention is therefore to describe a method and an arrangement by means of which the privacy-protection effect of a screen can be significantly improved. The invention should be implementable using simple means and operate as independently as possible of the method of generating the privacy-protection effect. Furthermore, the invention should present the viewer in the privacy-protection area with an image that is perceived as dark as possible.

[0017] This object is achieved according to the invention by a method for enhancing the privacy effect of a screen which allows switching between an operating mode with privacy effect and an operating mode without privacy effect and which is arranged in the dashboard of a motor vehicle, comprising the following steps, - display of an image content on a screen, where the screen (permanent or temporary, ie switchable on and off) has a privacy screen effect that allows viewing only from a limited angle range, - radiation of light from at least one light source directly (or indirectly) at least onto the eyes of a viewer of the screen, who is positioned to the side, i.e. not frontally, of the screen and who is thus in the area of ​​the privacy-protection effect of the screen, wherein the light source and the screen are spatially separated from one another, so that light from the light source enters the eyes of the viewer from a different spatial direction than the light which enters the eyes of the viewer from the screen, wherein the viewer corresponds to the driver of the motor vehicle, and wherein furthermore the at least one light source is only switched on when the operating mode of the screen with privacy effect is also switched on, - the luminance of the light source visible to the viewer is at least five times, preferably ten times, particularly preferably one hundred times as high as the luminance of the screen still visible to the viewer from his viewing position within the scope of the privacy effect, - so that the privacy-shielding effect of the screen is enhanced due to the light seen by the eyes of said viewer, at least from the light source, and the consequent pupil constriction and / or eye adaptation.

[0018] It is essential to note that the image content is more difficult or even impossible for the viewer to recognize when the light source is switched on than without the light from the light source. The effect of the viewer seeing a dark (i.e., black) image from their current position is amplified by the aforementioned pupil constriction and / or eye adaptation, since the residual light often still present at oblique angles in the privacy shield area is now perceived by the viewer as even weaker, i.e., darker.

[0019] "Sideways, i.e., not frontally," specifically means that the viewer in question is not positioned within a horizontal deviation of 5 degrees, 7 degrees, 10 degrees, or a maximum of 15 degrees from the perpendicular bisector (depending on the application). The "horizontal" axis is defined here as parallel to the top edge of the screen. The screen's privacy-protection effect is therefore preferably active at least horizontally.

[0020] Preferably, the light source and / or the screen can be dimmed in their luminance depending on the ambient brightness.

[0021] Another advantageous embodiment is conceivable here: Using eye position tracking for the viewer, a control unit uses a look-up table to determine the residual light value seen there based on the viewer's eye position and the screen's dimming values, and then controls or dims the brightness of the light source accordingly. This ensures that the luminance of the light source visible to the viewer is at least five times, preferably ten times, and particularly preferably more than one hundred times greater than the luminance of the screen still visible to the viewer within the scope of the privacy effect from their viewing position (e.g., from 25 or 40 degrees horizontally next to the screen).

[0022] The aforementioned "look-up table," or table of values, can be created, for example, using measurements empirically determined on the specific screen. It then contains, for example, the residual luminance still visible in each horizontal angle relative to the screen, measured from the perpendicular bisector.

[0023] The table can also be expanded by entering the combined values ​​for horizontal and vertical angles. Furthermore, the table should generally take into account the dimming status of the screen, i.e., different (usually lower) values ​​will be stored for one or more day modes (bright) than for a night mode.

[0024] Finally, the table advantageously contains the brightness of the light source to be set for each residual luminance at a defined angle in order to activate the agent-effect relationships according to the invention.

[0025] The fact that light from the light source enters the observer's eyes from a different spatial direction than the light that enters the observer's eyes from the screen is also considered to be the case if only an angle of the spherical coordinates of the directions of incidence of the light from the light source and the light from the screen differs (for example, measured from the center of the surface).

[0026] The aforementioned visible luminance of the light source naturally requires a corresponding illuminance at the viewer’s eyes.

[0027] In further designs, there is not just one light source, but rather several light sources.

[0028] The screen optionally allows switching between an operating mode with privacy protection and an operating mode without privacy protection. Arrangements of this type are described, for example, in WO 2019 / 034557 A1 or WO 2019 / 002496 A1 of the applicant.

[0029] In a further advantageous embodiment, the light source is designed to be directional, meaning it does not emit light in all spatial directions. The radiation is directed, in particular, toward the said viewer or an eye box for the viewer's presumed eye position.

[0030] The light source also advantageously emits a defined light spectrum that lies partly or entirely in the visible wavelength range. This spectrum can produce white light or evoke certain color perceptions in the viewer, such as light blue, turquoise, green, red, yellow, or others.

[0031] Particularly preferably, a maximum luminance of the light source is defined such that the light from the light source does not dazzle the viewer at a given ambient brightness.

[0032] The method according to the invention becomes particularly important when used in a motor vehicle. In this case, the light source advantageously corresponds to at least one light source (e.g., an LED, LED array, or a light guide) in the dashboard, a cluster instrument in the dashboard, ambient lighting within the vehicle, and / or another lighting device. In this way, the head of the observer, i.e., the driver, can be suitably exposed to light from the light source(s).

[0033] However, it is also possible for the method according to the invention to be used in the rear: there, one rear passenger would then correspond to the viewer and another rear passenger would see the screen directly in front of him (at an angle of a maximum of 5 to 10 degrees around the perpendicular bisector of the screen).

[0034] The object of the invention is further achieved by an arrangement for enhancing the privacy effect of a screen, which allows switching between an operating mode with privacy effect and an operating mode without privacy effect, and which is arranged in the dashboard of a motor vehicle, comprising - the said screen, wherein the screen (permanent or temporary) has a privacy screen effect that allows viewing only from a restricted angle range, and wherein the screen can display image content, - at least one light source for radiating light directly at least onto the eyes of a viewer of the screen, who is arranged to the side, i.e. not frontally, of the screen and who is thus in the area of ​​the privacy-protection effect of the screen, wherein the light source and the screen are spatially separated from one another, so that light from the light source enters the eyes of the viewer from a different spatial direction than the light which enters the eyes of the viewer from the screen, wherein the viewer corresponds to the driver of the motor vehicle, and wherein furthermore the at least one light source is only switched on when the operating mode of the screen with privacy effect is also switched on, - the luminance of the light source visible to the viewer is at least five times, preferably ten times, particularly preferably one hundred times as high as the luminance of the screen still visible to the viewer from his viewing position within the scope of the privacy effect, - so that the privacy-protecting effect of the screen is enhanced due to the light seen by the eyes of said viewer from at least the light source 3 and the consequent pupil constriction and / or eye adaptation.

[0035] The design variants and means-effect relationships of the method according to the invention specified above apply here, which will not be repeated here for reasons of redundancy.

[0036] In principle, the performance of the invention is maintained if the parameters described above are varied within certain limits.

[0037] It is understood that the features mentioned above and those to be explained below can be used not only in the combinations indicated, but also in other combinations or in isolation, without departing from the scope of the present invention.

[0038] The invention is explained in more detail below with reference to drawings which also show features essential to the invention. Fig. 1 a schematic diagram illustrating the method according to the invention, applied in a motor vehicle and shown in a side perspective, Fig. 2 a schematic diagram illustrating the method according to the invention, applied in a motor vehicle and shown in a bird's eye view, Fig. 3 a schematic diagram illustrating the method according to the invention in a second embodiment, applied in a motor vehicle and shown in a lateral perspective, and Fig. 4 a schematic diagram to illustrate the method according to the invention in a third embodiment variant, applied in a motor vehicle and shown in a lateral perspective.

[0039] The drawings are not to scale and only represent schematic diagrams. Fig. Figure 1 is a schematic diagram illustrating the method according to the invention, applied in a motor vehicle and shown in a lateral perspective. The method according to the invention for enhancing the privacy effect of a screen 1, which allows switching between an operating mode with privacy effect and an operating mode without privacy effect, and which is embedded in a console of the dashboard of the motor vehicle, comprises the following steps: - Representation of an image content 2 on a screen 1, wherein the screen 1 (in this example temporary, i.e. switchable on and off, e.g. according to WO 2019 / 034557 A1 or WO 2019 / 002496 A1 of the applicant) has a privacy screen effect that allows viewing only from a limited angle range, wherein the design in this example is such that the viewer 4, i.e. the driver, should not be able to recognize any image from his possible viewing angles when the privacy screen effect is switched on (whereby, for technical reasons, a complete blanking to 0 cd / m 2 residual light luminance in the direction of the driver is not reached), - radiation of light (here indicated by a dashed arrow) from at least one light source 3 directly at least onto the eyes of a viewer 4 (here the driver), who is arranged to the side, i.e. not frontally, of the screen 1 and who is thus in the area of ​​the privacy shielding effect of the screen 1, wherein the light source 3 and the screen 1 are spatially separated from one another, so that light from the light source 3 enters the eyes of the viewer 4 from a different spatial direction than the light which enters the eyes of the viewer 4 from the screen 1, wherein the viewer 4 corresponds to the driver of the motor vehicle, and wherein furthermore the at least one light source 3 is only switched on when the operating mode of the screen 1 with privacy shielding effect is also switched on, - wherein the luminance of the light source 3 visible to the viewer 4 is at least five times, preferably ten times, particularly preferably more than one hundred times as high as the luminance of the screen 1 still visible to the viewer 4 within the scope of the privacy effect from his viewing position (for example from 25 or 40 degrees horizontally next to the screen 1), - so that the privacy-protection effect of the screen 1 is enhanced due to the light seen by the eyes of said viewer 4 from at least the light source 3 and the consequent pupil constriction and / or eye adaptation.

[0040] It is essential to the invention to note here that the image content 2 is therefore more difficult or even no longer recognizable for the viewer 4 when the light source 3 is switched on than without the light from the light source 3. The effect that the viewer 4 sees a dark (black) image from his position is intensified due to the aforementioned pupil reduction and / or eye adaptation, since the residual light that is often still present at oblique angles in the privacy screen area is now perceived by the viewer 4 as even weaker, i.e. darker. Any residual contrast that still exists is thus almost or even completely reduced, so that the viewer 4 can no longer recognize anything on the screen 1.

[0041] Typical values ​​for the aforementioned residual light from side views, which, for example, at angles of 25 degrees (horizontal, according to the above definition) are theoretically reduced to 0 cd / m 2 should be darkened, are about 1 cd / m 2, if the peak brightness at a horizontal angle of 0 degrees is approximately 100 cd / m 2 (night mode), and about 5 cd / m 2 , if these are at 500 cd / m 2 (day mode).

[0042] If, according to the invention, the luminance of the light source 3 visible to the viewer 4 is at least five times, preferably ten times, particularly preferably more than one hundred times as high as the luminance of the screen 1 still visible to the viewer 4 within the scope of the privacy effect from his viewing position (25 degrees horizontal), the luminance of the light source 3 in night mode is accordingly at least 5 cd / m 2 (fivefold), 10 cd / m 2 (tenfold) or 100 cd / m 2 (hundredfold) and in day mode at least 25 cd / m 2 (fivefold), 50 cd / m 2 (tenfold) or 500 cd / m 2 (one hundredfold). Other values ​​are, of course, possible.

[0043] Another advantageous embodiment is conceivable here: Eye position tracking of the viewer 4 ensures that a control unit uses the eye position of the viewer 4 and the dimming values ​​of the screen 1 to determine the value of the residual light value seen there via a look-up table and controls or dims the brightness of the light source 3 accordingly. This always ensures that the luminance of the light source 3 visible to the viewer 4 is at least five times, preferably ten times, particularly preferably more than one hundred times as high as the luminance of the screen 1 still visible to the viewer 4 within the scope of the privacy effect from his viewing position (for example, from 25 or 40 degrees horizontally next to the screen 1).

[0044] The aforementioned "look-up table," i.e., a table of values, can be created, for example, using empirically determined measurement values ​​on the specific screen 1. It then contains, for example, for each horizontal angle relative to screen 1, measured from the perpendicular bisector, the residual luminance still visible in this direction.

[0045] The table can also be expanded by entering the combined values ​​for horizontal and vertical angles. Furthermore, the table should generally take into account the dimming status of screen 1, i.e., different (usually lower) values ​​will be stored for one or more day modes (bright) than for a night mode.

[0046] Finally, the table advantageously contains the brightness of the light source 3 to be set for each residual luminance at a defined angle in order to activate the agent-effect relationships according to the invention.

[0047] "Sideways, i.e., not frontally," specifically means that the viewer 4 in question is not within a horizontal deviation of 5 degrees, 7 degrees, 10 degrees, or a maximum of 15 degrees from the perpendicular bisector (depending on the application), which is the case with the driver as viewer 4 in a motor vehicle. As already mentioned, the "horizontal" axis is defined parallel to the upper edge of the screen. The privacy-protection effect of screen 1 is therefore preferably active at least in the horizontal direction.

[0048] The Fig. Figure 2 illustrates the method according to the invention and described above using a schematic diagram, with the scene shown here from a bird's-eye view. The light source 3 here corresponds, for example, to an LED or an LED array (of course with a corresponding control unit) mounted at the upper edge of the windshield or near the makeup mirror (not shown in the drawing).

[0049] The aforementioned visible luminance of the light source 3 naturally requires a corresponding illuminance at the eyes of the observer 4.

[0050] In further embodiments not shown in the drawing, not only one light source 3 may be present, but rather several light sources 3a, 3b, 3c, ... are present.

[0051] Preferably, the light source 3 and / or screen 1 can be dimmed in their luminance depending on the ambient brightness.

[0052] Furthermore, the light source 3 advantageously emits a defined light spectrum that lies partially or entirely in the visible wavelength range. This spectrum can produce white light or evoke certain color perceptions in the viewer 4, such as light blue, turquoise, green, red, yellow, or others.

[0053] Particularly preferably, a maximum luminance of the light source 3 is defined such that the light of the light source 3 does not dazzle the viewer 4 at a given ambient brightness.

[0054] The Fig. Figure 3 shows the application where light source 3 corresponds to at least one cluster instrument in the dashboard, which emits a corresponding luminance. This also allows the head of the viewer 4, i.e., the driver, to be suitably exposed to light from light source 3.

[0055] In a further advantageous embodiment, the light source 3 is designed to be directed, ie it does not radiate light in all spatial directions. The radiation is directed in particular toward the said observer 4 or an eye box for the presumed eye position. Such a case is Fig.4: Here, a light source 3 (again depicted stylized) is located directly at the upper right corner of the screen 1. Due to focusing and / or simple directional limitation by means of a spatial aperture, such as an opaque tube, the light emitted by this light source 3 is visible exclusively to the driver. A passenger—not shown in the drawing—would not perceive this light at all.

[0056] This again makes it essential to the invention that the light from the light source 3 enters the eyes of the viewer 4 from a different spatial direction than the light which enters the eyes of the viewer 4 from the screen 1. This is the case here because an angle of the spherical coordinates of the light incidence directions of the light from the light source 3 and the light from the screen 1 differs (for example, measured from the center of the surface), because the light source 3 is arranged above the image surface of the screen 1.

[0057] The object of the invention is further achieved by an arrangement for enhancing the privacy effect of a screen 1 which allows switching between an operating mode with privacy effect and an operating mode without privacy effect and which is arranged in the dashboard of a motor vehicle, comprising - said screen 1, wherein the screen 1 has a privacy screen effect that allows viewing (temporarily or permanently) only from a restricted angle range, and wherein the screen 1 can display image content 2, - at least one light source 3 for radiating light directly at least onto the eyes of a viewer 4 of the screen 1, who is arranged laterally, i.e. not frontally, from the screen 1 and who is thus in the area of ​​the privacy shielding effect of the screen 1, wherein the light source 3 and the screen 1 are spatially separated from one another, so that light from the light source 3 enters the eyes of the viewer 4 from a different spatial direction than the light entering the eyes of the viewer 4 from the screen 1, wherein the viewer 4 corresponds to the driver of the motor vehicle, and wherein furthermore the at least one light source 3 is only switched on when the operating mode of the screen 1 with privacy shielding effect is also switched on, - wherein the luminance of the light source 3 visible to the viewer 4 is at least five times, preferably ten times, particularly preferably one hundred times as high as the luminance of the screen 1 still visible to the viewer 4 from his viewing position within the scope of the privacy effect, - so that the privacy-protection effect of the screen 1 is enhanced due to the light seen by the eyes of said viewer 4 from at least the light source 3 and the consequent pupil constriction and / or eye adaptation.

[0058] The design variants and means-effect relationships of the method according to the invention specified above apply here, which will not be repeated here for reasons of redundancy.

[0059] The inventive method and the inventive arrangement described above each achieve the stated objective: They can significantly improve the privacy-protection effect of a screen. The invention can be implemented using simple means and operates virtually independently of the method used to create the privacy-protection effect. Furthermore, the invention presents the viewer in the privacy-protection area with a fundamentally dark (preferably black) image—depending on the original design of the privacy-protection effect.

[0060] The invention described above, in conjunction with an image display device, can be advantageously used wherever confidential data is displayed and / or entered, such as when entering a PIN or displaying data at ATMs or payment terminals. However, as described above, the invention can be particularly advantageously used in cars when a driver must not be distracted by content and must be able to see nothing but a dark, black image.

Claims

[1] Method for enhancing the privacy effect of a screen (1) which allows switching between an operating mode with privacy effect and an operating mode without privacy effect and which is arranged in the dashboard of a motor vehicle, comprising the following steps: - displaying an image content (2) on a screen (1), wherein the screen (1) has a privacy screen effect that allows viewing only from a limited angle range, - radiation of light from at least one light source (3) at least onto the eyes of a viewer (4) of the screen (1), who is arranged laterally, i.e. not frontally, from the screen (1) and who is thus in the area of the privacy shielding effect of the screen (1), wherein the light source (3) and the screen (1) are spatially separated from one another, so that light from the light source (3) enters the eyes of the viewer (4) from a different spatial direction than the light entering the eyes of the viewer (4) from the screen (1), wherein the viewer (4) corresponds to the driver of the motor vehicle, wherein furthermore the at least one light source (3) is only switched on when the operating mode of the screen (1) with privacy shielding effect is also switched on, - wherein furthermore the luminance of the light source (3) visible to the viewer (4) is at least five times, preferably ten times, particularly preferably one hundred times as high as the luminance of the screen (1) still visible to the viewer (4) from his viewing position within the scope of the privacy effect, - so that the privacy-protection effect of the screen (1) is enhanced due to the light seen by the eyes of said viewer (4) from at least the light source (3) and the consequent pupil constriction and / or eye adaptation. [2] Method according to claim 1, characterized by that the light source (3) emits light in a directed manner, ie not in all spatial directions, this radiation being directed in particular towards the said observer (4) or an eye box for his presumed eye position. [3] Method according to one of the preceding claims, characterized bythat the light source (3) and / or screen (1) are dimmed in their luminance depending on the ambient brightness. [4] Method according to one of the preceding claims, characterized by that the light source emits a defined light spectrum that lies partly or entirely in the visible wavelength range. [5] Method according to one of the preceding claims, characterized by that a maximum luminance of the light source (3) is defined such that the light of the light source (3) does not dazzle the viewer (4) at a given ambient brightness. [6] Method according to one of claims 3 to 5, characterized bythat a control unit uses eye position tracking to determine from the eye position of the viewer 4 and the dimming values of the screen 1 via a look-up table which value the residual light value seen there is in each case and dims the brightness of the light source 3 accordingly, so that it is always ensured that the luminance of the light source 3 visible to the viewer 4 is at least five times, preferably ten times, particularly preferably more than one hundred times as great as the luminance of the screen 1 still visible to the viewer 4 from his viewing position within the framework of the privacy effect. [7] Use of the method according to one of the preceding claims, wherein the light source (3) corresponds to at least one lighting means in the dashboard, a cluster instrument in the dashboard, an ambient lighting within the vehicle and / or another lighting device. [8] Arrangement for enhancing the privacy effect of a screen (1) which allows switching between an operating mode with privacy effect and an operating mode without privacy effect and which is arranged in the dashboard of a motor vehicle, comprising - said screen (1), wherein the screen (1) has a privacy screen effect that allows viewing only from a limited angle range, and wherein the screen (1) can display image content (2), - at least one light source (3) for radiating light at least onto the eyes of a viewer (4) of the screen (1), who is arranged laterally, i.e. not frontally, from the screen (1) and who is thus located in the area of the privacy shielding effect of the screen (1), wherein the light source (3) and the screen (1) are spatially separated from one another, so that light from the light source (3) enters the eyes of the viewer (4) from a different spatial direction than the light entering the eyes of the viewer (4) from the screen (1), wherein the viewer (4) corresponds to the driver of the motor vehicle, and wherein furthermore the at least one light source (3) is only switched on when the operating mode of the screen (1) with privacy shielding effect is also switched on, - wherein furthermore the luminance of the light source (3) visible to the viewer (4) is at least five times, preferably ten times, particularly preferably one hundred times as high as the luminance of the screen (1) still visible to the viewer (4) from his viewing position within the scope of the privacy effect, - so that the privacy-protection effect of the screen (1) is enhanced due to the light seen by the eyes of said viewer (4) from at least the light source (3) and the consequent pupil constriction and / or eye adaptation.

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