Method for displaying image content in at least two operating modes

Abstract

Method for displaying image content in at least two operating modes B1 for a viewing mode with a restricted viewing angle and B2 for a viewing mode with no restricted viewing angle, comprising the following steps - providing a first image generator (1) which emits image content in a restricted viewing angle, - Providing a second imager (2) which radiates image content into an unrestricted viewing angle, wherein the second imager (2) is arranged in front of the first imager (1) in the viewing direction and is at least partially transparent to light emanating from the first imager (1), wherein the second imager (2) is designed such that it deflects at least 90% of the light passing through it by a maximum of 10° over at least 50% of its surface, - switching on the first imager (1) for the operating mode B1 for a viewing mode with a restricted viewing angle, wherein the second imager (2) is switched transparently and, due to its limited scattering properties, only negligibly scatters the light emanating from the first imager (1) when passing through the second imager (2), so that the restricted viewing angle is not eliminated, - switching on at least the second image generator (2) for the B2 operating mode for a viewing mode with no restricted viewing angle, - wherein the first image generator (1) is further switchable between a viewing mode B1A with a restricted viewing angle and a viewing mode B1B with an unrestricted viewing angle, so that when the viewing mode B1A is used and the second image generator (2) is switched to transparent, the operating mode B1 is created, and so that when the viewing mode B1B is used and the second image generator (2) is switched on, a third operating mode B3 is created, in which image contents are displayed in two planes simultaneously in a viewing mode with an unrestricted viewing angle, and so that when the viewing mode B1A is used and the second image generator (2) is switched on, a fourth operating mode B4 is created, in which image contents are displayed in two planes simultaneously in a restricted viewing angle and outside the restricted viewing angle only the contents displayed on the second image generator (2) in one plane can be seen.

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.

[0002] 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

[0003] 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.

[0004] 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.

[0005] 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.

[0006] 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.

[0007] 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.

[0008] US 2016 / 0098692 A1 describes a method for processing a transaction using an ATM. This allows the use of a display with multiple viewing levels.

[0009] US 2011 / 0175902 A1 describes a multi-layer display. The achievable separation of images in different directions is limited.

[0010] WO 2004 / 036286 A1 describes a multiview display that combines multiple display layers. Here, too, the achievable separation of images in different directions is limited.

[0011] DE 10 2014 204 462 A1 discloses a display device for presenting content that is recognizable depending on the viewing angle. Partial overlay of the image content is used to make certain image components visible only from limited directions. This reduces the image resolution.

[0012] GB 2418518 A describes a screen that can switch between a private and a public mode using a guest-host interface. The privacy effect of the disclosed solution is limited.

[0013] DE 197 37 942 A1 discloses a display unit that uses a dual-cell technology to switch between a private and a public mode. Typically, with dual-cell technology, the privacy shield is limited at larger angles.

[0014] Finally, DE 10 2018 004 401 A1 of the applicant discloses a method for correcting image data for a screen. This method can be applied to various types of privacy screens.

[0015] The aforementioned methods and arrangements generally have the disadvantage that they significantly reduce the brightness of the basic screen and / or require a complex and expensive optical element for mode switching and / or reduce the resolution in the freely viewable mode. Description of the invention

[0016] The object of the invention is therefore to describe a method and a screen with which a switchable privacy screen effect can be achieved for a screen with a simple structure. The invention should be implementable using simple means and operate as independently as possible of the method of generating the privacy screen effect. Furthermore, the invention should optionally offer the possibility of displaying different images in different directions.

[0017] This object is achieved according to the invention by a method for displaying image contents in at least two operating modes B1 for a viewing mode with a restricted viewing angle and B2 for a viewing mode with no restricted viewing angle, comprising the following steps - Providing a first imager that emits image content into a restricted viewing angle, - Providing a second imager which radiates image content in an unrestricted viewing angle, wherein the second imager is arranged in front of the first imager in the viewing direction and is at least partially transparent to light emanating from the first imager, wherein the second imager is designed such that it deflects at least 90% of the light passing through it by a maximum of 10° over at least 50% of its surface, - Switching on the first imager for the operating mode B1 for a viewing mode with a restricted viewing angle, wherein the second imager is switched transparent and, due to its limited scattering properties, only negligibly scatters the light emanating from the first imager when passing through the second imager, so that the restricted viewing angle is not eliminated, - Switching on at least the second image sensor for operating mode B2 for a viewing mode with no restricted viewing angle.

[0018] The first image sensor can be switched between a viewing angle restricted viewing mode B1A and a viewing angle unrestricted viewing mode B1B, so that - when using the viewing mode B1A and transparent switching of the second image sensor, the operating mode B1 is created, - when using the viewing mode B1B and switching on the second image generator, a third operating mode B3 is created, in which image contents are displayed in two planes simultaneously in a viewing mode with no restricted viewing angle, and so that - when using the viewing mode B1A and switching on the second image sensor, a fourth operating mode B4 is created in which image contents are displayed simultaneously in two planes in a restricted viewing angle and outside the restricted viewing angle only the contents displayed on the second image sensor can be seen in one plane.

[0019] The second image generator is preferably even designed such that it deflects at least 90%, preferably more than 95%, of the light passing through it by a maximum of 10° on at least 80% of its surface or its entire image-displaying surface.

[0020] “Negligible” with regard to scattering means, for example, that at an angle of, for example, 40° horizontally from the surface normal, a maximum of 1% of the luminance emitted by the first imager at an angle of 0° is added by scattering.

[0021] Furthermore, in operating mode B2, the first image sensor can either be switched off, or a dark, preferably black, image content can be displayed on the switched-on first image sensor. This minimizes the overlay on the image displayed on the second image sensor, ie, minimizes interference.

[0022] A further advantageous embodiment of the invention is that, in operating mode B1, an image content is displayed on the switched-on second image sensor that blends any residual light from the first image sensor that is visible outside the restricted viewing angle. Such an image content can, for example, be a full-surface gray image or a full-surface, not-too-bright, monochrome image. In this case, "not too bright" means that only a few to several cd / m 2 Completely different image content is, of course, possible.

[0023] The first imager can be, for example, an LCD, microLED, miniLED, or OLED screen, on or in which an optical component is mounted to direct the light, such as a 3M™ Vikuiti louvre filter. Alternatively, the first imager can be configured differently to illuminate only a limited viewing angle. In this context, a limited viewing angle can mean, for example, an angular range of + / -30 degrees or + / -20 degrees around the perpendicular bisector of the first imager, applied in the horizontal and / or vertical direction. Alternatively, the reference can also be a straight line inclined relative to the perpendicular bisector instead of the perpendicular bisector.

[0024] The second imager can be, for example, a transparent LCD, microLED, miniLED, or OLED screen. An augmented reality screen, a scatter projection, or a screen based on polymer dispersed liquid crystals (PDLC) are also possible. Transparent in this context means that at least 15% of the light incident on the second imager from behind passes through it. This value applies to unpolarized light.

[0025] A further embodiment of the invention provides that the first imager emits image content at a restricted viewing angle only on a portion of its image surface, while the remaining portion emits image content at an unrestricted viewing angle. The remaining portion would thus be visible at all times from any viewing direction.

[0026] Furthermore, it is possible for the first imager to be at least partially transparent, where "transparent" means that at least 15% of the light incident on the first imager from behind passes through it. Transparent in this context also means that at least 15% of the light incident on the second imager from behind passes through it. This value applies to unpolarized light.

[0027] Finally, it is conceivable that by switching on the second image sensor in operating mode B2, a modified operating mode B2A is created, in which image contents are displayed simultaneously in two planes in a restricted viewing angle and outside the restricted viewing angle only the contents displayed on the second image sensor can be seen in one plane.

[0028] The above-mentioned method according to the invention can be used, for example, in a motor vehicle.

[0029] In principle, the performance of the invention is maintained if the parameters described above are varied within certain limits.

[0030] 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.

[0031] The invention is explained in more detail below with reference to drawings which also show features essential to the invention. Fig. 1 a schematic representation of the method according to the invention in operating mode B1, Fig. 2 a schematic representation of the method according to the invention in operating mode B2, Fig. 3 a schematic representation of the method according to the invention in operating mode B1, in which a special embodiment for blending residual light comes into play, Fig. 4 a schematic representation of the method according to the invention in operating mode B1, wherein the first screen has two display areas, Fig. 5 a schematic representation of the method according to the invention, in which a special embodiment for generating a further operating mode B3 comes into play, Fig. 6 a schematic representation of the method according to the invention, in which a special embodiment for generating a further operating mode B4 comes into play, as well as Fig. 7 a schematic representation of the method according to the invention in an extended embodiment in which different image contents are radiated into different angular ranges.

[0032] The drawings are not to scale and only represent schematic diagrams. Fig. Figure 1 shows a schematic representation of the method according to the invention in operating mode B1.

[0033] The method according to the invention for displaying image content in at least two operating modes B1 for a viewing mode with a restricted viewing angle and B2 for a viewing mode with no restricted viewing angle comprises the following steps: - Providing a first imager 1 that emits image content into a restricted viewing angle (the restricted viewing angle is stylized by the black triangle; the dashed arrows indicate that only low residual light values ​​are emitted into these viewing angles, which do not exceed a maximum of 5% of the peak brightness - for example, but not necessarily in the vertical direction; ideally, the residual light values ​​would be zero candelas per square meter), - Providing a second imager 2 which emits image content in an unrestricted viewing angle, wherein the second imager 2 is arranged in front of the first imager 1 in the viewing direction and is at least partially transparent to light emanating from the first imager 1, wherein the second imager 2 is designed such that it deflects at least 90% of the light passing through it by a maximum of 10° over at least 50% of its surface, - Switch on the first imager 1 - as in Fig. 1 - for the operating mode B1 for a viewing mode with a restricted viewing angle, wherein the second imager 2 is switched transparent and, due to its limited scattering properties, only negligibly scatters the light emanating from the first imager 1 when passing through the second imager 2, so that the restricted viewing angle is not eliminated, whereby the viewer 3 can indeed see the displayed image content, but not - at least not well - the viewer 4, who is outside the restricted viewing angle (which is why the viewer 4 is shown in dashed lines), - Switch on at least the second imager 2 - as in Fig. 2- for the B2 operating mode for a viewing mode with no restricted viewing angle.

[0034] The first image sensor 1 and the second image sensor 2 together form a screen 5, which has control electronics not shown in the drawing.

[0035] It is also true that the first image generator 1 can be switched between a viewing mode B1A with a restricted viewing angle and a viewing mode B1B with no restricted viewing angle, so that - when using the viewing mode B1A and transparent switching of the second image generator 2, the operating mode B1 is created (see Fig. 1), - when using the viewing mode B1B and switching on the second image generator 2, a third operating mode B3, which is Fig. 5 is illustrated, in which image contents are displayed in two levels simultaneously in a viewing mode that is not restricted in the viewing angle (these image contents then have a certain spatial effect for the viewers 3 and 4 due to the two levels), and so that - when using the viewing mode B1A and switching on the second image generator 2, a fourth operating mode B4, which Fig. 6 is shown, in which image contents are displayed in two planes at the same time in a restricted viewing angle for the viewer 3 and outside the restricted viewing angle, e.g. for the viewer 4, only the contents displayed on the second image generator 2 can be seen in one plane.

[0036] The Fig. Figure 2 shows a schematic representation of the method according to the invention in operating mode B2. The wide triangle here is intended to represent, in a stylized manner, that the second imager 2 emits image content within an unrestricted viewing angle, since the viewers 3 and 4 are now simultaneously positioned within the viewing angle.

[0037] The second image generator 2 is preferably even designed such that it deflects at least 90%, preferably more than 95%, of the light passing through it by a maximum of 10° on at least 80% of its area or its entire image-displaying area.

[0038] “Negligible” with regard to scattering means, for example, that at an angle of, for example, 40° horizontally from the surface normal, a maximum of 1% of the luminance emitted by the first imager at an angle of 0° is added by scattering.

[0039] The first imager 1 can, for example, be an LCD, microLED, miniLED, or OLED screen, on which or in which an optical component is mounted to direct the light, such as a 3M™ Vikuiti louvre filter. Alternatively, the first imager 1 can be configured differently to illuminate only a limited viewing angle.

[0040] In this context, a restricted viewing angle can, for example, mean an angular range of + / -30 degrees or + / -20 degrees around the perpendicular bisector of the first image sensor 1, applied in the horizontal and / or vertical direction. Alternatively, the reference can also be a straight line inclined relative to the perpendicular bisector.

[0041] The second image sensor 2 can, for example, be a transparent LCD, microLED, miniLED, or OLED screen. An augmented reality screen, a scatter projection, or a screen based on polymer dispersed liquid crystals (PDLC) are also possible. Transparent in this context means that at least 15% of the light incident on the second image sensor 2 from behind passes through it. This value applies to unpolarized light.

[0042] Furthermore, in operating mode B2, the first image sensor 1 can either be switched off, or a dark, preferably black, image content can be displayed on the switched-on first image sensor 1. This ensures the least possible overlap, ie, the least possible interference, with the image displayed on the second image sensor 2.

[0043] Alternatively, it is conceivable that by switching on the second image generator 2 in the operating mode B2, a modified operating mode B2A is created, in which image contents are displayed in two planes simultaneously in a restricted viewing angle and outside the restricted viewing angle only the contents displayed on the second image generator 2 can be seen in one plane.

[0044] A further advantageous embodiment of the invention, which is Fig. 3, is that in operating mode B1, an image content is displayed on the switched-on second image sensor 2, which overlays any residual light from the first image sensor 1 that is visible outside the restricted viewing angle. Such image content can, for example, be a full-surface gray image or a full-surface, non-bright, monochrome image. Non-bright in this case means that only a few to several cd / m 2 , maximum 30 cd / m 2 , are radiated. In Fig. 3 apply to Fig. 1 above. The dotted arrows, on the other hand, represent a stylized representation of the light emitted by the second image generator 2 of the aforementioned image content for cross-fading. Cross-fading also disadvantageously affects the limited angular range in which the viewer 3 can and should see the displayed image content. However, since the cross-fading, as described above, only introduces a low level of brightness, a clearly visible, high-contrast image remains for the viewer 3. To further improve the quality of the image visible to the viewer 3, the image content displayed on the second image generator 2 can be adaptively controlled depending on the image content of the first image generator 1. Darker image content on the first image generator 1 then also enables darker image content on the second image generator 2.

[0045] A further embodiment of the invention, which is Fig. 4, provides that the first image generator 1 emits image content at a restricted viewing angle only on a partial area 1a of its image surface, while on the remaining part 1b, image content is emitted at an unrestricted viewing angle. The remaining part would thus be visible at any time from any viewing direction, in particular also for the viewer 4, while only the viewer 3 can see the image content of the partial area 1a visible at a restricted viewing angle. This embodiment variant can be advantageously used both in the above-described and in the further embodiments of the invention described below.

[0046] In Fig.Figure 7 shows a schematic representation of the method according to the invention in an expanded embodiment, in which different image contents are radiated into different angular ranges W1 and W2. This is a variant of a method for displaying two different image contents I1 and I2 in different viewing angles W1 and W2, comprising the following steps - Providing a first image generator 1 which radiates the image content I1 into the viewing angle W1, - Providing a second imager 2 which radiates the image content I2 into the viewing angle W2, wherein the second imager 2 is arranged in front of the first imager 1 in the viewing direction and is at least partially transparent to light emanating from the first imager 1, wherein the second imager 2 is designed such that it deflects at least 90% of the light passing through it by a maximum of 10° over at least 50% of its surface, - due to the limited scattering properties of the second imager 2, the light emanating from the first imager 1 is only negligibly scattered when passing through the second imager 2, so that the viewing angle W1 for the image content I1 is not canceled out.

[0047] The viewing angles W1 and W2, which can also be referred to as viewing angle ranges, should be partially or completely different. Overlapping is certainly possible depending on the application. "Different" in this sense should also include the fact that at a viewing angle W1, a slight residual light is emitted into the same geometric angular range as at the viewing angle W2, but in the angular range W2, the same geometric angular range is exposed to significantly more light than just residual light. The image contents I1 and I2 can be emitted simultaneously or, if necessary, sequentially into the viewing angles W1 and W2.

[0048] Here too, the second image generator 2 is preferably designed such that it deflects at least 90%, preferably more than 95%, of the light passing through it by a maximum of 10° on at least 80% of its surface or its entire image-displaying surface.

[0049] “Negligible” with regard to scattering means, for example, that at an angle of, for example, 40° horizontally from the surface normal, a maximum of 1% of the luminance emitted by the first imager at an angle of 0° is added by scattering.

[0050] In a special embodiment, this method variant also makes it possible to set the viewing angles W1 and W2 in such a way that they supply the two eyes of one and the same observer simultaneously or sequentially with different image contents I1 and I2, so that a spatial impression is created.

[0051] The aforementioned method according to the invention can be used, for example, in a motor vehicle. In this case, viewer 3 would correspond to the passenger, and viewer 4 would correspond to the driver, so that, if necessary, content is not visible to the driver. In the latter method variant, the driver can see a different image content I2 than the passenger.

[0052] The inventive method described above achieves the stated objective: It allows a switchable privacy screen effect to be achieved with a simple structure. The invention can be implemented using simple means and operates largely independently of the method of generating the privacy screen effect. Furthermore, the invention offers a possibility of displaying different images in different directions.

[0053] The invention described above can be applied wherever confidential data is displayed and / or entered, such as PIN entry or data display at ATMs or payment terminals, as well as data protection on mobile devices. However, as described above, the invention can be used particularly advantageously in cars when a driver must not be distracted by image content.

Claims

[1] Method for displaying image content in at least two operating modes B1 for a viewing angle restricted viewing mode and B2 for a viewing angle unrestricted viewing mode, comprising the following steps - providing a first image generator (1) which emits image content in a restricted viewing angle, - Providing a second imager (2) which radiates image content into an unrestricted viewing angle, wherein the second imager (2) is arranged in front of the first imager (1) in the viewing direction and is at least partially transparent to light emanating from the first imager (1), wherein the second imager (2) is designed such that it deflects at least 90% of the light passing through it by a maximum of 10° over at least 50% of its surface, - switching on the first imager (1) for the operating mode B1 for a viewing mode with a restricted viewing angle, wherein the second imager (2) is switched transparently and, due to its limited scattering properties, only negligibly scatters the light emanating from the first imager (1) when passing through the second imager (2), so that the restricted viewing angle is not eliminated, - switching on at least the second image generator (2) for the B2 operating mode for a viewing mode with no restricted viewing angle, - wherein the first image generator (1) is further switchable between a viewing mode B1A with a restricted viewing angle and a viewing mode B1B with an unrestricted viewing angle, so that when the viewing mode B1A is used and the second image generator (2) is switched to transparent, the operating mode B1 is created, and so that when the viewing mode B1B is used and the second image generator (2) is switched on, a third operating mode B3 is created, in which image contents are displayed in two planes simultaneously in a viewing mode with an unrestricted viewing angle, and so that when the viewing mode B1A is used and the second image generator (2) is switched on, a fourth operating mode B4 is created, in which image contents are displayed in two planes simultaneously in a restricted viewing angle and outside the restricted viewing angle only the contents displayed on the second image generator (2) in one plane can be seen. [2] Use of the method according to claim 1 in a motor vehicle.

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